Current Protein and Peptide Science, 2006, 7, 487-499487
1389-2037/06 $50.00+.00
? 2006 Bentham Science Publishers Ltd.Anticancer α-Helical Peptides and Structure / Function Relationships Un-derpinning Their Interactions with Tumour Cell Membranes
Sarah R. Dennison 1, Michelle Whittaker 1, Frederick Harris 2 and David A. Phoenix 1,*
1Faculty of Science, University of Central Lancashire, Preston, PR1 2HE, England, UK; 2Department of Forensic and Investigative Science, University of Central Lancashire, Preston, PR1 2HE, England, UK
Abstract: Cancer is a major cause of premature death and there is an urgent need for new anticancer agents with novel
mechanisms of action. Here we review recent studies on a group of peptides that show much promise in this regard, ex-
emplified by arthropod cecropins and amphibian magainins and aureins. These molecules are α-helical defence peptides,
which show potent anticancer activity (α-ACPs) in addition to their established roles as antimicrobial factors and modu-
lators of innate immune systems. Generally, α-ACPs exhibit selectivity for cancer and microbial cells primarily due to
their elevated levels of negative membrane surface charge as compared to non-cancerous eukaryotic cells. The anticancer
activity of α-ACPs normally occurs at micromolar levels but is not accompanied by significant levels of haemolysis or
toxicity to other mammalian cells. Structure / function studies have established that architectural features of α-ACPs such
as amphiphilicty levels and hydrophobic arc size are of major importance to the ability of these peptides to invade cancer
cell membranes. In the vast majority of cases the mechanisms underlying such killing involves disruption of mitochon-
drial membrane integrity and / or that of the plasma membrane of the target tumour cells. Moreover, these mechanisms do
not appear to proceed via receptor-mediated routes but are thought to be effected in most cases by the carpet / toroidal
pore model and variants. Usually, these membrane interactions lead to loss of membrane integrity and cell death utilising
apoptic and necrotic pathways. It is concluded that that α-ACPs are major contenders in the search for new anticancer
drugs, underlined by the fact that a number of these peptides have been patented in this capacity.
INTRODUCTION
Cancer is the most prevalent cause of premature death in
the Western world [1] and the incidence of the condition is
rising, especially in cases such as prostate cancer [2] and
childhood leukaemia [3]. It is generally accepted that envi-
ronmental factors, such as tobacco smoking and infections,
coupled to physiological predisposition, such as inherited
oncogenes, hormonal imbalance and autoimmune disorders,
may precipitate the onset of a cancerous condition. However,
the biochemical mechanisms associated with carcinogenesis
are not fully understood and despite extensive research pro-
grammes, an effective cure is lacking for many cancers and
the treatments that are available are frequently inadequate for
full recovery of the patient [4]. Some progress has been
made in that it is often possible to increase the life expec-
tancy and the quality of life for cancer patients by employing
drug therapy and / or surgery with a view to remission and /
or palliation [5]. Current effective cancer treatment modali-
ties include surgery, radiotherapy, and cytostatic chemother-
apy and to capitalise on the advantages of each treatment
modality whilst keeping the disadvantages to a minimum,
multi-modal therapy is usually most efficacious [6].
The majority of drugs used in anticancer chemotherapies
tend to exhibit activity against proliferating cells by inhibit-
ing nucleic acid synthesis. However, at the concentrations
required to control tumour growth, most chemotherapeutic *Author correspondence to this author at the Faculty of Science, University
of Central Lancashire, Preston, PR1 2HE, England, UK; Tel: +1772
893481; Fax: +1772 894981; E-mail: daphoenix@https://www.doczj.com/doc/bb9965141.html, agents also affect healthy cells thereby causing undesirable side effects [7]. Treatment is further complicated by the fact that in the long term, tumours can gradually acquire resis-tance to therapeutic drugs. This resistance may be due to one or more factors: only low concentrations of drug may be able to reach the centre of the tumour; only a small proportion of the target tumour cells may be in a susceptible state for treatment, for example in the case of drugs that are cell cycle dependent or where the tumour cells may express proteins that endow the tumour with biochemical resistance mecha-nisms to the drug. In the latter case the tumour cell is often capable of pumping therapeutic drugs out of the cells using multi-drug resistant proteins [8]. Resistance is therefore a major problem to the success of a cancer treatment and the panacea for the condition would be a new family of drugs that acts exclusively on cancer cells and is not prone to common effectors of multi-drug resistance [9].ANTICANCER PEPTIDES Over the last decade, it has become increasingly clear that many defence peptides possess anticancer activity [10-12]. These peptides play a crucial role as antimicrobial agents in the innate immune systems of organisms ranging from insects to mammals [13-21] although there is increas-ing evidence that they have a diverse range of functions in modulating immunity, which have an impact on infections and inflammation [22]. In their antimicrobial capacity, de-fence peptides have been found to be active against fungi,viruses, parasites and protozoa in addition to Gram-positive and Gram-negative bacteria [17, 23-28]. Extensive studies on the antimicrobial action of defence peptides have shown
488 Current Protein and Peptide Science, 2006, Vol. 7, No. 6Dennison et al.
that they all exhibit membrane interactive properties and whilst some appear to attack intracellular targets, in most cases, direct attack on the microbial membrane itself is the primary killing mechanism used by these peptides [29, 30]. The current view is that the anticancer activity of defence peptides also primarily derives from the membrane interac-tive abilities of these peptides and involves invasion of the mitochondrial membrane and / or the plasma membrane of cancer cells [10-12].
To facilitate their membrane interactions, the vast major-ity of defence peptides are cationic and amphiphilic with those that adopt α-helical structure the most studied [19, 24]. Currently, this latter group includes the majority of defence peptides that have been shown to also possess anticancer activity and these may be broadly divided into two sub-groups: peptides in the first of these subgroups (Table 1) are toxic to microbes, cancerous and non cancerous cells alike and are exemplified by melittin [31], human LL37 [32], alamethicin [33] and pardaxin [34]. Peptides in the second of these subgroups (Table 1) generally exhibit both antimicro-bial and anticancer specificity at comparable levels, usually in the low micromolar range (< 10-5 M). At these levels, peptides of this subgroup are not significantly haemolytic or toxic to other mammalian cells [11, 12], which makes them of clear medical interest. Examples of this subgroup include magainins and cecropins and as antimicrobial agents, these peptides are already undergoing clinical trials [17, 35-38] and have been the subject of patents [39-41]. More recently, magainins, cecropins and other members of this subgroup have begun to receive increased attention as a potential source of therapeutically useful anticancer agents [11] and for clarity, these peptides are referred to here as α-helical anticancer peptides (α-ACPs).
A diverse spectrum of organisms are known to produce α-ACPs as shown by cecropins, which have potent antican-cer activity [11, 42-47] and have been isolated from the silkworm Hyalophora cecropia [48], insects and mammals [49, 50]. However, the richest source of α-ACPs is the skin of amphibians and peptides isolated from this source include the families of magainins, aureins, citropins, dahleins, maculatins, uperins and caerins. A well-established example of the first of these families is magainin II, which was origi-nally isolated from the skin of the African clawed frog, Xenopus laevis [51]. In vitro, magainin II has been shown to exhibit activity against a wide range of cancer cell lines in-cluding, breast, lung and bladder cancers, along with mela-nomas, lymphomas and leukemias [52-56]. In vivo, local treatment with magainin II was found to completely ablate a subcutaneous xenograft model of melanoma tumor growth in nude mice [54] whilst the application of magainin peptides greatly improved the survival of animals with ascites-producing tumours [55]. The remaining families of amphib-ian peptides described above are obtained from the skin of various closely related species of Australian frogs of the Litoria and Uperoleia genera [16]. Each of these families was tested for anticancer activity using the testing regime of the National Cancer Institute of the USA (http:// https://www.doczj.com/doc/bb9965141.html,;
[57]). It was found that peptides from each family exhibited activity against cell lines representing circa 55 cancers, in-cluding: renal, ovarian, prostate, colon, breast, lung and bladder cancers, along with melanomas, leukemias and can-cers of the central nervous system [16].Aurein 1.2 from Litoria raniformis [58] and citropin 1.1 from Litoria citropia [59, 60] are the best characterised α-ACPs from these families with each killing upward of 90% of the cancer cell lines tested [57, 61].
THE SELECTIVITY OF α-ACPS FOR CANCER CELLS
It is generally accepted that electrostatic interactions con-stitute the major factor underpinning the ability of α-ACPs to preferentially target and invade cancer cell membranes [11]. Thus at levels when they are tumouricidal, these pep-tides, which are generally cationic, are not significantly at-tracted to normal vertebrate cells whose plasma membranes carry an overall neutral charge on their outer surface: pri-marily due to the fact that the major lipid components these
Table 1.Sequences Data for α-ACPs and α-Helical Defence Peptides
Table 1 shows the sequences of typical α-ACPs from amphibians, including: aurein 1.2, citropin 1.1, maculatin 1.1 [16] and ma-gainin [153], along with those of typical α-helical defence peptides, including melittin [31], pardaxin [34] and almethicin [33].
In the latter peptide, Ac denotes an acetyl group and U represents α-methylalanine [33]. Also shown is the amphiphilicity, as the mean hydrophobic moment (<μH>), and mean hydrophobicity (
Peptide Segment sequence<μH>
Aurein 1.2GLFDIIKKIAESF-NH20.710.21
Citropin 1.1GLFDVIKKVASVIGGL-NH20.640.34
Maculatin 1.1GLFGVLAKVAAHVVPAIAEHF-NH20.480.45
Magainin 1GIGKFLHASGKFGKAFVGEIMKS-COOH0.56-0.01
Melittin GIGAVLKVLTTGLPALISWIKRKRQQ-NH20.570.25
Pardaxin GFFALIPKIISSPLFKTLLSAVGSALSSSGGQE0.500.59
Alamethicin Ac-UPUAUAQUVUGLUPVUUEQF-OH0.30-0.11
Anticancer α-Helical Peptides and Structure Current Protein and Peptide Science, 2006, Vol. 7, No. 6 489
membranes are zwitterionic, including: phosphatidylethano-lamine, phosphatidylcholine and sphingomyelin [62, 63]. At tumouricidal levels, α-ACPs also generally show insignifi-cant levels of haemolysis. The first major barrier presented to these peptides by euthrocytes is their outer glycocalix layer and it has been suggested that these cationic peptides become attached to negatively charged sialic acid moieties within the glycocalix. The low affinity of α-ACPs for zwitte-rionic membranes than makes it difficult for them to divorce from the glycocalix barrier and partition into the membrane thus inhibiting haemolysis [10].
As with all in vivo drug resistance mechanisms, that of cancer cells to α-ACPs is thought to be multifactorial. For example, cholesterol is another major component of eukary-otic cell membranes [64] and has been shown to inhibit the action of α-ACPs such as cecropins by changing membrane fluidity, thereby retarding the membrane insertion of these peptides [65, 66]. Recent studies on erythrocytes have sug-gested that cholesterol may play a similar role in the mem-branes of red blood cells [67] and it is well established that these membranes contain high levels of the sterol [68]. Thus it may be that cholesterol-mediated resistance to membrane invasion by α-ACPs also contributes to the lack of haemo-lytic ability displayed by many of these peptides, as shown for a number of aureins [57].
The selectivity shown by α-ACPs for cancer cells is pri-marily ascribed to the negative outer surface charge carried by the plasma membranes of these cells [11]. The outer leaflet of these membranes contains higher than normal lev-els of anionic phosphatidylserine (PS) [69, 70], which is al-most completely absent from the outer leaflet of normal cell plasma membranes [62, 63]. Most recently, it was shown that a number of human cancer cell lines expose PS on their outer surface, which appeared to facilitate killing of these cells by NK-2, a known α-ACP [71]. These results are rein-forced by studies on aurein 1.2, which is an α-ACP known to possess high tumouricidal activity against a range of human glioma cells with an IC50 of circa 10 μM [57]. Presented here, our own investigations clearly show that aurein 1.2 rapidly partitions into model membranes formed from whole lipid extracts of membranes from cells of the 1321N human brain astrocytoma cell line [72], inducing large maximal surface pressure changes of circa 10.0 mN m-1 (Fig. 1A). The peptide showed similar kinetics and levels of interaction with model anionic membranes formed from pure PS but much lower rates of interaction and surface pressure changes with zwitterionic model membranes formed from pure phosphati-dycholine (Fig. 1B).In combination, these studies clearly support a role for PS in the anticancer activity of α-ACPs but nonetheless, the level of PS in the outer membrane of cancer cells is low, forming less than 10% of the total membrane phospholipids [73]. Such PS levels would make cancer cell membranes only marginally more anionic than their normal cell counterparts, which suggests that other factors may con-tribute to the selectivity shown by α-ACPs for these cells. Some authors have suggested that the increased levels of sialic acids associated with the tumour membrane surface may contribute to this selectivity [12]. These acids are nega-tively charged sugar residues that usually occupy exposed terminal positions on the oligosaccharide chains of mem-brane bound glycoconjugates [74]. This suggestion was strongly supported when it was found that the pre-treatment of tumour cells with neuraminidase to enzymatically digest sialyl residues and remove them from the cell surface greatly reduced the ability of several α-ACPs to target these mem-branes [75]. Other authors have observed that the lytic selec-tivity of α-ACPs may also be influenced by the high nega-tive transmembrane potentials associated with cancer cell membranes. This potential can be disturbed by membrane destabilisation, resulting in the loss electrolytes and cell death. In contrast, normal eukaryotic cell membranes have only low transmembrane potentials [10]. Work involving scanning electron microscopy showed that in relation to normal cells, tumourigenic cells possess higher numbers of microvilli [73] and it was suggested that the effectively in-creased outer surface area of these cells would enhance the selectivity of α-ACPs by enabling higher levels membrane binding by these peptides [76, 77]. Based on the above ob-servations, it is clear that differences in membrane composi-tion, membrane fluidity, and transmembrane potential can partly explain the selectivity of α-ACPs for cancer cells over normal eukaryotic cells [10, 11]. Generally supporting this conclusion, α-ACPs also show selectivity for bacterial mem-branes, which may be considered as functional analogues of cancer cell membranes, exhibiting anionic outer surfaces due to their high acidic lipid content. Nonetheless, it is still a matter of fact that other cationic α-helical defence peptides show no significant cell selectivity and are toxic to virtually all cell types. Moreover, there is also great variability in tar-get cell specificity within α-ACPs: some cecropins show selectivity and high toxicity to a broad range of bacterial cells [21, 46, 78] and cancer cells [11, 42-47]. In contrast, aureins show no significant activity towards Gram-negative bacteria but selectivity and high toxicity towards Gram-positive bacteria, which is accompanied by comparable anti-cancer activity with a limited number of cell lines [57]. Moreover, for a given α-ACP, there can be great variability in the killing efficacy of the peptide when directed against cells of different cancer types [11]. Currently, there does not appear to be a unifying concept(s) that is able to fully ex-plain these observations but it would seem that a negatively charged membrane is only a general prerequisite for target cell selectivity by cationic α-ACPs and α-helical defence peptides. Indeed, several studies have suggested that this selectivity may also depend upon the physiochemical and structural characteristics of the peptide along with the or-ganisation and composition of both the target membrane and its associated outer layers [79, 80]. Consistent with this sug-gestion, several previous statistical studies have shown that when subgrouped according to their ranges of target organ-isms, α-helical defence peptides exhibit significant differ-ences between a number of their physiochemical and struc-tural properties [24, 28, 81]. Using the approach of these latter authors, a recent study attempted to gain insight into the selectivity of α-ACPs by comparing the properties of these peptides to those of α-helical defence peptides with selectivity for either bacterial targets or a broader range of microbial targets [12]. Significant differences between the net positive charge of these peptide groups were revealed (Table 2) and consistent with these findings, our own com-positional analyses here (Fig. 2) showed that lysine demon-strated a markedly higher frequency of occurrence in α-ACPs than in the α-helical defence peptides analysed by
490 Current Protein and Peptide Science, 2006, Vol. 7, No. 6Dennison et al. Fig. (1A). Shows the interactions of aurein 1.2 with monolayer mimics of membranes of Staphylococcus aureus (A) and membranes of cells from the 1321N human brain astrocytoma cell line (B). In both cases, these monolayers were formed by spreading whole lipid extracts of cells onto an aqueous subphase to give an initial surface pressure of 30 mN m-1, mimetic of naturally occurring membranes. Aurein 1.2 (4μM) was then introduced into the subphase and changes in surface pressure monitored all as described in Dennison et al., [155]. The peptide induced surface pressure changes of 9 mN m-1 with S. aureus membrane mimics and 10 mN m-1 with astrocytoma membrane mimics. Fig. (1B) used the same experimental conditions except that lipid monolayers were either formed from pure PS to give an anionic monolayer (A) or pure PC to give a zwitterionic monolayer (B). For (A) surface pressure changes of circa 9 mN m-1 were observed whereas for (B), lower surface pressure changes of circa 2 mN m-1 were exhibited. Bacterial cells were grown according to Dennison et al., [156] and cancer cells according to Harris et al [157]. Total lipid extraction were derived from these cells using the methodology of Bligh and Dyer [158] and used to form monolayers as described by Dennison et al. [155].
these latter authors. It may be that positive charge or the snorkelling activity of this residue [82] is important to the selectivity of α-ACPs. The studies of Dennison et al., [12] also showed that there were significant differences between the sequence lengths and molecular weights of α-ACPs and those of α-helical defence peptides with selectivity for bacte-rial targets (Table 2). Previous studies have suggested that sequence length and molecular weight do not have a direct effect on the microbial selectivity of defence peptides [24, 28] but given that anticancer activity is not known to be a naturally occurring function of α-ACPs, it may be that these size properties have some influence on their selectivity for cancer cell membranes. Currently, we are investigating this possibility, which received some recent support when it was reported that sequence length can influence the efficacy of aureins and other closely related amphibian peptides with anticancer activity [16].
THE INTERACTION OF α-ACPS WITH CANCER CELL MEMBRANES
Based on data from microbial studies, two generic mod-els have been proposed to explain the ability of α
-helical
Anticancer α-Helical Peptides and Structure Current Protein and Peptide Science, 2006, Vol. 7, No. 6 491Table 2.Physiochemical Properties of α-ACPs and α-Helical Defence Peptides
Table 2 shows the ranges of a number of physiochemical properties of α-ACPs and α-helical defence peptides, which were active
against either Gram-positive and Gram-negative bacteria [{G+, G-} peptides] or Gram-positive and Gram-negative bacteria, and
fungi [{G+, G-, F} peptides]. Analysis of variance (ANOVA) showed that there were no significant between these peptide groups
for pI and arc size (F 2,175 = 0.040, p = 0.96, in both cases). However, the net charges of α-ACPs were significantly different to
those of either {G+, G-} peptides or {G+, G-, F} peptides (F 2,175 = 18.781, p = 0). ANOVA also showed that the sequence lengths
of these α-ACPs differed to {G+, G-} peptides but were similar to those of {G+, G-, F} peptides (F 2,175 = 10.415 p = 0). Paral-
leling this trend, the molecular weights of α-ACPs showed significant differences to {G+, G-} but similarity to {G+, G-, F} pep-
tides (F 2,175 = 7.72, p = 0.01). Data for α-ACPs was taken from Dennison et al., [12] and or α-helical defence peptides from Den-
nison et al., [24].Peptides Molecular mass
range
(kDa)
Length range (resi-dues)Net charge range pI range Hydrophobic arc range (°)α-ACPs 1.4 to 4.7
13 to 400 to 12 6 to12.6
40 to 240{G+, G-} 1.2 to 7.4
10 to 68-1 to +16 6.7 to 12.440 to 300{G+, G-, F} 1.4 to 4.913 to 460 to +10 5.6 to 12.7
40 to 240Fig. (2). Shows the relative frequency of occurrence of amino acid residues in the primary structures of a dataset of α-ACPs (white) and in those of a dataset comprising α-helical defence peptides (grey), which were active against either Gram-positive and Gram-negative bacteria {G+, G-} or Gram-positive and Gram-negative bacteria, and fungi {G+, G-, F}. In general, the two datasets of peptides showed similar over-all compositions and comparable number of polar and apolar residues. However, lysine and isoleucine showed significantly higher levels of occurrence in α-ACPs than in α-helical defence peptides. The datasets used for this compositional analysis are available at website (https://www.doczj.com/doc/bb9965141.html,/facs/science/biology/bru/amp_data.htm).
defence peptides to invade target cell membranes, which are
the carpet mechanism and the barrel-stave model of pore
formation [23, 83] and are represented in Fig. (3) and Fig.
(4). To use this latter model, peptides must be sufficiently
long to span the bilayer and would initially bind electrostati-
cally to the headgroup region of target membranes in an ori-
entation parallel to the bilayer surface (Fig. 3A ). Subsequent
peptide aggregation and insertion into the membrane at an
angle perpendicular to the bilayer surface would then lead to
the formation of a transmembrane pore. To create this pore,
the hydrophobic faces of the α-helical peptides associate with the bilayer core and the hydrophilic faces of the pep-tides form the aqueous lumen (Fig. 3B ). It is well established that alamethicin, produced by the fungus Trichoderma viride [33], and pardaxin, a shark repellent neurotoxin secreted by sole fish of the genus Pardachirus [34], are non-selective α-helical defence peptides that use this latter mechanism of membrane invasion to facilitate their biological activity.Based on these observations it was suggested that use of the barrel-stave pore model of membrane invasion may be char-acteristic of non-selective α-helical defence peptides [10] but most recently, evidence has been presented, showing that α-
492 Current Protein and Peptide Science, 2006, Vol. 7, No. 6Dennison et al. Fig. (3). Represents peptides using the barrel-stave pore mechanism to invade membranes. These α-helical peptides must be sufficiently long to span the bilayer and initially, bind to the membrane in an orientation that lies with the α-helical long axis roughly parallel to the bilayer surface (Fig. (3A)). The apolar face of the peptide interacts with the hydrophobic acyl chain region of the membrane whilst the polar face of the peptide associates with the lipid headgroup region. Subsequent peptide aggregation leads to membrane insertion at an angle perpendicular to the bilayer surface and the formation of a transmembrane pore. To create this pore, the hydrophobic faces of the α-helical peptides associ-ate with the bilayer core and the hydrophilic faces of the peptides form the aqueous lumen of the construction (Fig. (3B)). Fig. (3) was adapted from Dennison et al. [24].
ACPs may also invade membranes using this model. A num-ber of groups have studied the membrane interactive behav-iour of ceratotoxins, which are found in the reproductive accessory glands of the medfly Certitis capitata [72, 84-86]. These peptides adopt α-helical structure in the presence of lipid and in this conformation, are sufficiently long to span the bilayer [87]. Ceratotoxins show low levels of haemolysis that are accompanied by strong broad range antibacterial activity, the levels of which correlate well with their high levels of pore-forming activity [86, 88, 89]. The pores formed by these peptides have been unambiguously shown to involve the construction of voltage dependent ion chan-nels according to the barrel-stave model [89, 90]. These pep-tides show many of the characteristics associated with α-ACPs although, as yet, they do not appear to have been in-vestigated in this capacity. The focus of a number of authors has been the membrane interactive properties of maculatin 1.1, which is found in the skin of the Australian frog Litoria genimaculata [91] and is closely related to aurein 1.2 and citropin 1.1 (Table 1). The peptide is α-helical at the mem-brane interface [92, 93] and in this conformation, is suffi-ciently long to span the bilayer [94]. At comparable micro-molar levels, maculatin 1.1 showed anticancer and antimi-crobial activity [16] and a strong preference for anionic membranes over zitterionic membranes [92, 93] but low lev-els of haemolysis [95], thus showing the hallmark character-istics of α-ACPs. In a novel approach, the lytic abilities of maculatin 1.1 were investigated using confocal fluorescence microscopy and single giant unilamellar vesicles (GUVs), which incorporated fluorescent probes of differing molecular weight [94]. It was found that whilst overall integrity of the GUVs membrane was maintained, the peptide rapidly in-duced the release of entrapped low molecular weight probes from these vesicles but showed no such ability with probes of higher molecular weight. These latter authors suggested that this differential release of molecular weight probes re-sulted from the permeation of GUVs by transmembrane pores, which were formed from oligomers of maculatin 1.1 via a mechanism that was consistent with the barrel stave pore mechanism.
The carpet mechanism of membrane invasion [23, 24] utilises a mode of initial membrane binding and orientation that is similar to that proposed for the barrel stave pore for-
mation. However in the carpet mechanism, aggregation of
Anticancer α-Helical Peptides and Structure Current Protein and Peptide Science, 2006, Vol. 7, No. 6 493 Fig. (4). Represents peptides using the carpet mechanism to invade membranes. The α-helical peptides utilise a mode of initial membrane binding and orientation that is similar to that described in Fig. (3) for the barrel stave pore formation. However in the carpet mechanism, ag-gregation of on the target membrane surface imposes a positive curvature strain by increasing the distance between membrane lipid head groups (Fig. (4A)). At a critical concentration, these aggregated α-ACPs realign, causing the membrane surface to cavitate inwards and ulti-mately form a toroidal pore (Fig. (4B)). In this pore, participating α-helical peptides remain in close association with membrane lipid head groups, which leads to the formation of pores that are lined by these polar head groups and the hydrophilic faces of the peptides (Fig. (4B)). These pores are proposed to be transient and lysis of the bilayer then occurs when numerous toroidal pores coalesce forming ‘islands’ in the membrane, ultimately leading to membrane micellization (Fig. (4C)). Fig. (4) was adapted from Dennison et al., [24].
peptide molecules on the target membrane surface imposes a positive curvature strain by increasing the distance between membrane lipid head groups (Fig. 4A). At a critical concen-tration, these aggregated peptide molecules realign, causing the membrane surface to cavitate inwards and ultimately form a toroidal pore (Fig. 4B). In further contrast to the bar-rel stave pore formation, the carpet mechanism requires that peptide molecules remain in close association with mem-brane lipid head groups, which leads to the formation of pores that are lined by these polar head groups and the hy-drophilic faces of the α-helical peptides (Fig. 4B). These pores are proposed to be transient and lysis of the bilayer then occurs when numerous toroidal pores coalesce, ulti-mately leading to membrane micellization (Fig. 4C) [96, 97]). Recent studies have shown that pardaxin can utilise the
carpet mechanism to invade membranes, in addition to the
494 Current Protein and Peptide Science, 2006, Vol. 7, No. 6Dennison et al.
barrel-stave pore model, and it was suggested by these authors that similar versatility may be shown by other such peptides [98]. Consistent with this observation, melittin, which is a non-selective α-helical defence peptide found in the venom of the honey bee Apis mellifera [31], has been reported to invade membranes using the barrel-stave pore model [94, 99-101] and most recently, the carpet / toroidal pore mechanism [102, 103]. It has previously been suggested that use of the carpet mechanism / toroidal pore formation may be characteristic of selective α-helical defence peptides [10] and appears to be that most favoured to facilitate cancer cell membrane invasion by α-ACPs. Based on both experi-mental evidence [104] and molecular modelling [105, 106] it is generally accepted that magainins and cecropins use the carpet mechanism / toroidal pore formation to exert their antimicrobial activity [23] and there is accumulating evi-dence that these peptides utilise similar mechanisms to kill cancer cells [107, 108]. More recently, patch clamp studies on a single cell from a stomach carcinoma cell line showed that cecropin B induced transient pores in these cells with increasing levels of these pores leading to cell lysis [47]. These authors proposed a mechanism of pore formation for the peptide, which showed strong similarities to the toroidal pore model. Confocal microscopy showed that a fluores-cently labelled magainin II analogue was able to cross the plasma membrane of the human cervical carcinoma HeLa cell line, which was suggested by further analyses to involve the toroidal pore mechanism [109]. Most recently, scanning electron microscopy was used to study the morphological changes induced by the action of magainin II on single cells of the 486P bladder cancer cell line. Micrographs clearly showed that the plasma membrane of these cells was dis-rupted and a pore type mechanism appeared to be involved, which showed similarities to the carpet / toroidal pore mechanism [52]. Using the approach described above for studies on maculatin 1.1, Ambroggio et al.,[94] showed that aurein 1.2 and citropin 1.1 induced the instantaneous release of entrapped fluorescent probes from GUVs, regardless of the molecular weight of the probe, which was accompanied by complete membrane destabilisation. Previous studies have shown that both peptides insert into membranes an an-gle of circa 50° but possess insufficient length to span the bilayer [92]. Taken with their own data, this led Ambroggio et al., [94] to propose that aurein 1.2 and citropin 1.1 desta-bilise membranes using the carpet mechanism and thereby exert their anticancer and antimicrobial activity. Moreover, the latter two studies led to the suggestion that aurein 1.2 and citropin 1.1 may utilise a previously undescribed variation on the carpet mechanism and destabilise membranes through the use of oblique orientated α-helices [24, 110]. These α-helices possess hydrophobicity gradients along their long axis, which causes them to insert into membranes at a shal-low angle of between 30° and 60° thereby destabilising membrane structure and promoting a range of membrane-related processes including pore formation [111, 112]. A theoretical analysis of aurein 1.2 and citropin 1.1 showed that these peptides possessed hydrophobicity gradients, lev-els of amphiphilicity and other structural characteristics that are strongly associated with oblique orientated α-helical structure [110]. More recent analyses have shown that many other α-ACPs are candidates to form such structure and it was suggested that oblique orientated α-helices may be commonly used to invade cancer cell membranes [12].
Another variation on the carpet mechanism, the Shai, Huang and Matsazuki (SHM) model [113], was proposed to account for the fact that some α-helical defence peptides can traverse the membrane of microbial cells and attack intra-cellular targets. Essentially the SHM model generalizes the carpet mechanism, incorporating aspects from several previ-ous models, and proposes that upon the disintegration of transient toroidal pores, peptides can be become translocated onto the inner surface of the membrane [113]. Clearly, this or similar mechanisms could also account for the ability of α-ACPs and other α-helical defence peptides to assume cy-toplasmic locations, thereby facilitating their ability to in-vade mitochondrial membranes and attack other intracellular targets [10, 11].
Mitochondria are established targets for anticancer ther-apy and the ability of cationic species such as α-ACPs to target mitochondrial membranes is generally driven by the transmembrane potential across this membrane system [114, 115]. Most recently, it was shown that magainin 1 killed cells from the human leukemia cell line, HL-60, without significant disruption of the plasma membrane but was ac-companied by a series of events associated with permeabili-sation of the mitochondrial membrane and the induction of apoptosis [116]. The peptide was found to induce an increase in the level of reactive oxygen species found in the cell, which is an early signal of apoptosis [117, 118] and to pro-mote the release of cytochrome c from mitochondria. It is well established that cytochrome c release leads to the acti-vation of caspase 3, which is responsible for many of the hallmark effects of apoptosis [119, 120]. Elevated levels of caspase 3 activity were detected in HL-60 cells that had been treated with magainin 1 along with a number of major effects arising from apoptosis, including proteasome activation [121], increased nuclear condensation and DNA fragmenta-tion [122]. Interestingly, recent studies on an analogue of magainin II suggested that the anticancer action of the pep-tide involved disruption of the plasma membrane and / or the mitochondrial membrane [109]. These studies showed that the peptide was able to translocate across the plasma mem-brane of cells of the cervical carcinoma HeLa cell line and the internalised peptide was found to induce high levels of cell cytoxicity, which was proposed to arise from dissipation of the plasma membrane potential and leakage of intracellu-lar molecules and / or mitochondrial damage leading to apoptosis. In contrast to these magainin peptides, BMAP-28 (Bovine myeloid antimicrobial peptide), was shown une-quivocally to kill cancer cells through disruption of both the mitochondrial and the plasma membranes [75]. The peptide has been shown to possess all the physiochemical hallmarks of α-ACPs and to possess high toxicity to a range of myeloid and lymphoid cancer cell lines at levels similar to its antimi-crobial activity [75, 123]. The anticancer activity of BMAP-28 was found to be primarily due to plasma membrane per-meabilisation and necrosis [75] but other effects were re-vealed when these latter authors made a more detailed study on the action of the peptide on the U937 myeloid cell line. A Ca2+ influx into the cytosol was detected in the early steps of plasma membrane permeabilization, which appeared to trig-ger membrane blebbing, DNA fragmentation and other
Anticancer α-Helical Peptides and Structure Current Protein and Peptide Science, 2006, Vol. 7, No. 6 495
events consistent with apoptosis [75]. It is generally accepted that mitochondrial events control the apoptosis process [124], and to further characterize the anticancer activity of BMAP-28, the effects of the peptide on mitochondria were investigated [125]. These latter authors showed that BMAP-28 promoted permeabilisation of the mitochondrial mem-brane and depolarization of the inner mitochondrial mem-brane, both in single U937 cancer cells and in iso-lated mitochondria. Further investigation suggested that this ability underpinned the BMAP-28-mediated induction of apoptosis in U937 cells and resulted from the peptide’s ca-pacity to mediate opening of the mitochondrial permeability transition pore [125], which is a supramolecular protein complex occurring at contact points between the mitochon-drial outer and inner membranes [126]. Previous studies have shown that opening of this pore leads to the mitochon-drial permeability transition, which is characterized by a sudden increase in the permeability of the inner mitochon-drial membrane to solutes with molecular mass below 1500 Da [127]. These events promote membrane depolarization, mitochondrial swelling and other apoptotic events, leading to the loss of outer mitochondrial membrane integrity and the translocation of pro-apoptotic proteins from the mitochon-drial intermembrane space to the cytosol with subsequent activation of caspases [115, 120]. It was suggested by [125] that in addition to inducing necrosis through membrane per-meabilisation, BMAP-mediated disruption of the mitochon-drial membrane would contribute to the induction of apopto-sis observed in their previous study [75]. It was also ob-served by [125] that in addition to these mechanisms, the anticancer activity of BMAP-28 could involve other modes of action such as the induction of apoptosis via the facilita-tion of increased cytoplasmic Ca2+. Indeed, a number of anti-cancer mechanisms that do not directly involve membrane disruption have been reported for both α-ACPs and other cytolytic peptides [10, 11]. However, in general, these mechanisms lie beyond the scope of this review and will not be further discussed.
STRUCTURE / FUNCTION ANALYSES OF α-ACPS AND THEIR MEMBRANE INTERACTIONS The foregone discussion has established that α-ACPs exhibit comparable efficacy in their anticancer and antimi-crobial activities, and that these activities involve the com-mon function of membrane invasion, which is clearly illus-trated by studies on aurein 1.2. It has been previously shown that the peptide is effective against cancer cells of glioma cell lines and bacterial cells from Gram-positive organisms at comparable levels of circa 10-5 M [92]. Fig. (1A) shows that at the same micromolar concentration, the peptide ex-hibits kinetics of interaction and induces maximal surface pressure changes in monolayer mimics of Staphylococcus aureus membranes that are similar to those observed in monolayer mimics of 1321N glioma cell membranes.The number of close parallels between the anticancer and antimi-crobial mechanisms of α-ACPs clearly suggests that the two activities of the peptides may involve similar structure / function relationships and to gain insight into this possibility, several studies have compared structural characteristics of α-ACPs to those of α-helical defence peptides. Our own com-positional analyses showed that each of these groups of pep-tides contained polar and apolar residues in roughly equal proportions, suggesting comparable levels of amphiphilicty in each case (Fig. 2). Graphical analysis of α-ACPs showed that these peptides formed strongly amphiphilic α-helices, which were comparable in residue distribution to those of α-helical defence peptides, whilst ANOVA (Table 2) showed that the arc sizes of α-helices from these three peptide groups exhibited no significant differences [12]. Given the crucial role of structural amphiphilicity in the antimicrobial function of α-helical defence peptides, these latter authors attempted to relate the amphiphilicity of α-ACPs to their anticancer function. At this juncture, it is perhaps worthy of note that the extent of these analyses was severely restricted due to the lack of detail provided with regards to tumour cell lines in many reports of peptides with anti-cancer activity. Nonetheless, Dennison et al. [12] quantified the amphiphil-icity of a number of α-ACPs and regressed these values against their lethal doses when directed against Jurkat and K562 tumour cell lines respectively. A significant negative linear correlation between these parameters was revealed by these analyses (Fig. 5) and although limited, these data clearly suggested that for the α-ACPs studied, higher levels of amphiphilicity were important for higher levels of anti-cancer activity and a comparable relationship was recently reported for α-helical defence peptides [24, 28]. To investi-gate this suggestion further, Dennison et al., [12] plotted the amphiphilicity of α-ACPs versus their hydrophobicity, which gives a measure of affinity for the membrane interior [128]. A hydrophobic moment plot of these data points [12] showed that most of α-ACPs represented would be predicted to be surface active according to the criteria of Eisenberg et al.,[129]. This class of α-helices partitions into membranes in a manner that closely parallels the initial stages of the bar-rel pore model and the carpet mechanism (Fig. 3 and Fig. 4), aligned such that the α-helical long axis lies approximately parallel to the interface and the polar / apolar interactions of the α-helix with the membrane are energetically satisfied [130]. In general, surface active α-helices are highly am-phiphilic and insert strongly into membranes, which is well illustrated in Fig. (1A). Aurein 1.2 has a particularly high amphiphilicity (Table 1) and Fig. (1A) shows that the pep-tide induces large pressure changes of circa 9 mN m-1 in monolayer mimics of both cancer and microbial membranes, a value that is comparable to those reported for a number of other strongly surface active α-helices [131]. Dennison et al., [12]also undertook a linear regression analysis of their hydrophobic moment plot of α-ACPs, which revealed a strong negative correlation between the amphiphilicity and hydrophobicity of these peptides these parameters (Fig. 6). These data clearly suggested that an appropriate balance between amphiphilicity and hydrophobicity is required for the anticancer activity of the α-ACPs studied. Similar bal-ances between these parameters have been reported neces-sary for the membrane interactions of α-helical defence pep-tides [24] and several other classes of surface active α-helices [132-134].
In combination, these studies clearly support the view that the anticancer activity of α-ACPs may predominantly derive from structure / function relationships that facilitate the invasion of cancer cell membranes by these peptides [10-12]. Nonetheless, it has been observed that the mechanisms underlying these processes of membrane invasion are rela-
496 Current Protein and Peptide Science, 2006, Vol. 7, No. 6Dennison et al.
Fig. (5). Shows a plot of the amphiphilicity of α-ACPs, measured as the mean hydrophobic moment (<μH>) [154],versus their anticancer activity, determined as the peptide dose required to kill 50% of target cancer cells (LD50). The target cells represented in these plots were from the K562 (black) and Jurkat (grey) cell lines. Regression analysis of these data indicated a strong negative linear correlation between <μH> and LD50 (R2 = 0.81 in both cases), which ANOVA showed to possess a particularly significant F statistic in both cases with F(1,6) = 21.00; p = 0.0059; and F(1,6) = 22.23; p = 0.005 respectively. These analyses clearly show that amphiphilicity is important to the anticancer activity of α-ACPs. Fig. (5) was adapted from Dennison et al., [12].
Fig. (6). Shows hydrophobic moment analysis of α-ACPs. The amphiphilicity of α-ACPs was measured as the mean hydrophobic moment, (<μH>) whilst their affinity for the membrane interior was measured by < H > according to [154]. Regression analysis of these data indi-cated a strong negative linear correlation between these parameters (R2 = 0.64), which ANOVA shoed to possess a particularly significant F statistic ([F(1, 32) = 56.11; p = 1.93 x 10-8). These analyses indicated that a characteristic balance between amphiphilicity and hydrophobicity is important to the ability of α-ACPs to invade cancer cell membranes. Fig. (6) was adapted from Dennison et al., [12].
Anticancer α-Helical Peptides and Structure Current Protein and Peptide Science, 2006, Vol. 7, No. 6 497
tively non-specific [135], which implies that these processes will not involve receptor based mechanisms. Earlier studies had suggested that the anticancer activity of magainins may involve a tumour cell receptor [56, 108] although later stud-ies did not support this idea [107]. More recent studies have strongly argued against protein receptor based mechanisms for both α-ACPs and other defence peptides with anticancer activity. It has been shown that D-amino acid analogues of: magainin [54, 55, 136], cecropin [136-139]citropin 1.1 [61], maculatin 1.1 [140], melittin [136] and others [10] show anticancer and antimicrobial activity at levels comparable to those of the parent L-amino acid peptides. Nonetheless, the possibility of some α-ACPs using receptor based mecha-nisms should not be discounted completely as the use of such mechanisms by pore-forming peptides is not without prece-dent. Nisins are class I bacteriocins, which are cationic am-phiphilic lantibiotics that are produced by Lactococcus lac-tis, and are highly active against other Gram-positive species [141]. Micromolar levels of these peptides were found to induce transient pores in model membranes and comparisons to magainins led to the proposal that nisins may use a toroi-dal pore type mechanism for bacterial membrane invasion [142]. However, this model could not explain the fact that the in vivo antibacterial activity of nisins contrasted to that of magainins by occurring at nanomolar levels. It is now known that nisins target the cell wall precursor lipid II, which func-tions as a receptor for these peptides, and that receptor-binding induces a twofold mode of antibacterial action by the peptides: Cell wall biosynthesis is inhibited, thereby promoting bacterial membrane permeabilisation, and the affinity of nisins for these membranes is greatly increased. In turn, this increased affinity leads to the formation of well defined pores using a highly specific mechanism that in-volves both nisin and lipid II molecules and most recently, a model been proposed to describe this mechanism [143]. A number of other lantibiotics have been reported to target lipid II and permeabilise the membranes of target bacteria [143, 144] whilst some class IIa bacteriocins that show specificity for Listeria may also use a receptor-mediated pore-forming mechanism to exert their antibacterial action [145-147]. Based on the generally close correspondence between the antimicrobial and anticancer activity of many peptides, a recent study tested nisins for activity against cells of the HL-60 leukaemia cell [116]. No activity was detected but this appeared to be one of the few such studies con-ducted, which is surprising given that nisins have virtually no toxicity to humans as witnessed by their use in the food industry and packaging systems [148].
CONCLUDING REMARKS
Studies using in vitro models have established that α-ACPs show selectivity for cancer cells probably via the tar-geting their anionic membranes although other factors not yet elucidated appear to be involved. These results have mo-tivated a number of in vivo studies designed to improve the ability of both α-ACPs and other defence peptides to target cancer cells. Strategies developed by these studies include: the construction of designed peptides; the creation of prolytic peptides that can be cleaved upon interaction with target cancer cells; conjugating peptides with ligands that are ex-pressed on the cancer cell membrane; the linking of peptides to ligand hormones such as gonadotropins and the use of
vector-mediated delivery of genes encoding peptides into
cancer cells [10, 11, 149].
Based on in vitro systems, it has been established that the
major mechanisms of anticancer activity used by all known
α-ACPs involves invasion of the mitochondrial and / or plasma membrane, does not require membrane receptors and
generally proceed via the carpet / toroidal pore mechanism
and variants. This ability to invade membranes is primarily
governed by membrane-based factors such as lipid composi-
tion and the gross structural properties of α-ACPs such as
amphiphilicity. It has previously been predicted that the
relatively non-specific nature of these membrane invasion
mechanisms would make development of cancer cells with
resistance to α-ACPs unlikely [12]. Cancer cells with multi
drug resistance (MDR) is a major problem in anticancer
therapy, most commonly arising from the over-expression of
P-glycoprotein, a membrane-bound efflux pump that actively
removes many conventional anticancer drugs [150, 151].
Prompted by these predictions, in vivo investigations have
shown that both α-ACPs and other defence peptides are able
to kill cancer cells with P-glycoprotein mediated MDR with
equal or better efficacy than the corresponding wild type cell
lines [10, 11]. These results were a major finding and re-
search into ability of α-ACPs to kill cancer cells with MDR
was further inspired by the observation that these peptides
could synergise with some conventional anticancer drugs
such as S-fluorouracil and cytarabine against cancer cells
[42]. Application of this combinatorial strategy to kill MDR
cancer cells showed that the efficacy of a number of α-ACPs
was enhanced by co-treatment with conventional anticancer
drugs such as cisplatin, etoposide and doxorubicin at non-
toxic levels [10, 11].
It is clear from this review that α-ACPs are serious con-
tenders in the search for new anticancer drugs with novel
mechanisms of action. Indeed, a measure of their perceived
promise as therapeutic agents and potential as commercial
propositions is provided by the fact that a number of these
peptides, along with their analogues and designed α-ACPs,
have recently been patented as putative anticancer com-
pounds [41, 152]. Further examples of such patented α-
ACPs are available at: https://www.doczj.com/doc/bb9965141.html,/
patft/index.html, website of the United States Patent and
Trademark Office.
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Received: November 14, 2005Accepted: February 06, 2006
四种翻译方法 1.直译和意译 所谓直译，就是在译文语言条件许可时，在译文中既保持原文的内容，又保持原文的形式——特别指保持原文的比喻、形象和民族、地方色彩等。 每一个民族语言都有它自己的词汇、句法结构和表达方法。当原文的思想内容与译文的表达形式有矛盾不宜采用直译法处理时，就应采用意译法。意译要求译文能正确表达原文的内容，但可以不拘泥与原文的形式。（张培基） 应当指出，在再能确切的表达原作思想内容和不违背译文语言规范的条件下，直译有其可取之处，一方面有助于保存原著的格调，另一方面可以进新鲜的表达方法。 Literal translation refers to an adequate representation of the original. When the original coincides or almost tallies with the Chinese language in the sequence of vocabulary, in grammatical structure and rhetorical device, literal translation must be used. Free translation is also called liberal translation, which does not adhere strictly to the form or word order of the original.（郭著章） 直译法是指在不违背英语文化的前提下，在英译文中完全保留汉语词语的指称意义，求得内容和形式相符的方法。
脐带间充质干细胞的研究进展 间充质干细胞（mesenchymal stem cells,MSC S ）是来源于发育早期中胚层 的一类多能干细胞[1-5]，MSC S 由于它的自我更新和多项分化潜能，而具有巨大的 治疗价值 ,日益受到关注。MSC S 有以下特点：(1)多向分化潜能，在适当的诱导条件下可分化为肌细胞[2]、成骨细胞[3、4]、脂肪细胞、神经细胞[9]、肝细胞[6]、心肌细胞[10]和表皮细胞[11, 12]；(2)通过分泌可溶性因子和转分化促进创面愈合；(3) 免疫调控功能，骨髓源（bone marrow ）MSC S 表达MHC-I类分子，不表达MHC-II 类分子，不表达CD80、CD86、CD40等协同刺激分子，体外抑制混合淋巴细胞反应，体内诱导免疫耐受[11, 15]，在预防和治疗移植物抗宿主病、诱导器官移植免疫耐受等领域有较好的应用前景；(4)连续传代培养和冷冻保存后仍具有多向分化潜能，可作为理想的种子细胞用于组织工程和细胞替代治疗。1974年Friedenstein [16] 首先证明了骨髓中存在MSC S ，以后的研究证明MSC S 不仅存在于骨髓中，也存在 于其他一些组织与器官的间质中：如外周血[17]，脐血[5]，松质骨[1, 18]，脂肪组织[1]，滑膜[18]和脐带。在所有这些来源中，脐血(umbilical cord blood)和脐带(umbilical cord)是MSC S 最理想的来源，因为它们可以通过非侵入性手段容易获 得，并且病毒污染的风险低，还可冷冻保存后行自体移植。然而，脐血MSC的培养成功率不高[19, 23-24]，Shetty 的研究认为只有6%，而脐带MSC的培养成功率可 达100%[25]。另外从脐血中分离MSC S ，就浪费了其中的造血干/祖细胞(hematopoietic stem cells/hematopoietic progenitor cells,HSCs/HPCs) [26, 27]，因此，脐带MSC S (umbilical cord mesenchymal stem cells, UC-MSC S )就成 为重要来源。 一．概述 人脐带约40 g, 它的长度约60–65 cm, 足月脐带的平均直径约1.5 cm[28, 29]。脐带被覆着鳞状上皮，叫脐带上皮，是单层或复层结构，这层上皮由羊膜延续过来[30, 31]。脐带的内部是两根动脉和一根静脉，血管之间是粘液样的结缔组织，叫做沃顿胶质，充当血管外膜的功能。脐带中无毛细血管和淋巴系统。沃顿胶质的网状系统是糖蛋白微纤维和胶原纤维。沃顿胶质中最多的葡萄糖胺聚糖是透明质酸，它是包绕在成纤维样细胞和胶原纤维周围的并维持脐带形状的水合凝胶，使脐带免受挤压。沃顿胶质的基质细胞是成纤维样细胞[32]，这种中间丝蛋白表达于间充质来源的细胞如成纤维细胞的，而不表达于平滑肌细胞。共表达波形蛋白和索蛋白提示这些细胞本质上肌纤维母细胞。 脐带基质细胞也是一种具有多能干细胞特点的细胞，具有多项分化潜能，其 形态和生物学特点与骨髓源性MSC S 相似[5, 20, 21, 38, 46]，但脐带MSC S 更原始，是介 于成体干细胞和胚胎干细胞之间的一种干细胞，表达Oct-4, Sox-2和Nanog等多
精神分裂症的病因及发病机理 精神分裂症病因：尚未明，近百年来的研究结果也仅发现一些可能的致病因素。（一）生物学因素1．遗传遗传因素是精神分裂症最可能的一种素质因素。国内家系调查资料表明：精神分裂症患者亲属中的患病率比一般居民高6.2倍，血缘关系愈近，患病率也愈高。双生子研究表明：遗传信息几乎相同的单卵双生子的同病率远较遗传信息不完全相同 的双卵双生子为高，综合近年来11项研究资料：单卵双生子同病率（56.7%），是双卵双生子同病率（12.7%）的4.5倍，是一般人口患难与共病率的35-60倍。说明遗传因素在本病发生中具有重要作用，寄养子研究也证明遗传因素是本症发病的主要因素，而环境因素的重要性较小。以往的研究证明疾病并不按类型进行遗传，目前认为多基因遗传方式的可能性最大，也有人认为是常染色体单基因遗传或多源性遗传。Shields发现病情愈轻，病因愈复杂，愈属多源性遗传。高发家系的前瞻性研究与分子遗传的研究相结合，可能阐明一些问题。国内有报道用人类原癌基因Ha-ras-1为探针，对精神病患者基因组进行限止性片段长度多态性的分析，结果提示11号染色体上可能存在着精神分裂症与双相情感性精神病有关的DNA序列。2．性格特征：约40%患者的病前性格具有孤僻、冷淡、敏感、多疑、富于幻想等特征，即内向
型性格。3．其它：精神分裂症发病与年龄有一定关系，多发生于青壮年，约1/2患者于20～30岁发病。发病年龄与临床类型有关，偏执型发病较晚，有资料提示偏执型平均发病年龄为35岁，其它型为23岁。80年代国内12地区调查资料：女性总患病率（7.07%。）与时点患病率（5.91%。）明显高于男性（4.33%。与3.68%。）。Kretschmer在描述性格与精神分裂症关系时指出：61%患者为瘦长型和运动家型，12.8%为肥胖型，11.3%发育不良型。在躯体疾病或分娩之后发生精神分裂症是很常见的现象，可能是心理性生理性应激的非特异性影响。部分患者在脑外伤后或感染性疾病后发病；有报告在精神分裂症患者的脑脊液中发现病毒性物质；月经期内病情加重等躯体因素都可能是诱发因素，但在精神分裂症发病机理中的价值有待进一步证实。（二）心理社会因素1．环境因素①家庭中父母的性格，言行、举止和教育方式（如放纵、溺爱、过严）等都会影响子女的心身健康或导致个性偏离常态。②家庭成员间的关系及其精神交流的紊乱。③生活不安定、居住拥挤、职业不固定、人际关系不良、噪音干扰、环境污染等均对发病有一定作用。农村精神分裂症发病率明显低于城市。2．心理因素一般认为生活事件可发诱发精神分裂症。诸如失学、失恋、学习紧张、家庭纠纷、夫妻不和、意处事故等均对发病有一定影响，但这些事件的性质均无特殊性。因此，心理因素也仅属诱发因
脐带血造血干细胞库管理办法（试行） 第一章总则 第一条为合理利用我国脐带血造血干细胞资源，促进脐带血造血干细胞移植高新技术的发展，确保脐带血 造血干细胞应用的安全性和有效性，特制定本管理办法。 第二条脐带血造血干细胞库是指以人体造血干细胞移植为目的，具有采集、处理、保存和提供造血干细胞 的能力，并具有相当研究实力的特殊血站。 任何单位和个人不得以营利为目的进行脐带血采供活动。 第三条本办法所指脐带血为与孕妇和新生儿血容量和血循环无关的，由新生儿脐带扎断后的远端所采集的 胎盘血。 第四条对脐带血造血干细胞库实行全国统一规划，统一布局，统一标准，统一规范和统一管理制度。 第二章设置审批 第五条国务院卫生行政部门根据我国人口分布、卫生资源、临床造血干细胞移植需要等实际情况，制订我 国脐带血造血干细胞库设置的总体布局和发展规划。 第六条脐带血造血干细胞库的设置必须经国务院卫生行政部门批准。 第七条国务院卫生行政部门成立由有关方面专家组成的脐带血造血干细胞库专家委员会（以下简称专家委
员会），负责对脐带血造血干细胞库设置的申请、验收和考评提出论证意见。专家委员会负责制订脐带血 造血干细胞库建设、操作、运行等技术标准。 第八条脐带血造血干细胞库设置的申请者除符合国家规划和布局要求，具备设置一般血站基本条件之外， 还需具备下列条件： （一）具有基本的血液学研究基础和造血干细胞研究能力； （二）具有符合储存不低于1 万份脐带血的高清洁度的空间和冷冻设备的设计规划； （三）具有血细胞生物学、HLA 配型、相关病原体检测、遗传学和冷冻生物学、专供脐带血处理等符合GMP、 GLP 标准的实验室、资料保存室； （四）具有流式细胞仪、程控冷冻仪、PCR 仪和细胞冷冻及相关检测及计算机网络管理等仪器设备； （五）具有独立开展实验血液学、免疫学、造血细胞培养、检测、HLA 配型、病原体检测、冷冻生物学、 管理、质量控制和监测、仪器操作、资料保管和共享等方面的技术、管理和服务人员； （六）具有安全可靠的脐带血来源保证； （七）具备多渠道筹集建设资金运转经费的能力。 第九条设置脐带血造血干细胞库应向所在地省级卫生行政部门提交设置可行性研究报告，内容包括：
高一英语翻译技巧和方法完整版及练习题及解析 一、高中英语翻译 1．高中英语翻译题：Translation: Translate the following sentences into English, using the words given in the brackets. 1．究竟是什么激发小王学习电子工程的积极性？(motivate) 2．网上支付方便了客户，但是牺牲了他们的隐私。(at the cost of) 3．让我的父母非常满意的是，从这个公寓的餐厅可以俯视街对面的世纪公园，从起居室也可以。(so) 4．博物馆疏于管理，展品积灰，门厅冷落，急需改善。(whose) 【答案】 1．What on earth has motivated Xiao Wang’s enthusiasm/ initiative to major in electronic engineering? 2．Online payment brings convenience to consumers at the cost of their privacy. 3．To my parents’ satisfaction, the dining room of this apartment overlooks the Century Park opposite the street and so it is with the sitting room. 或者What makes my parents really satisfy is that they can see the Century Park from the dining room of this apartment, so can they from the living room. 4．This museum is not well managed, whose exhibits are covered with dust, and there are few visitors, so everything is badly in need of improvement. 或The museum whose management is reckless, whose exhibits are piled with dust and whose lobby is deserted, requires immediate improvement. 【解析】 1．motivate sb to do sth 激发某人做某事，on earth究竟，major in 以…为专业，enthusiasm/ initiative热情/积极性，故翻译为What on earth has motivated Xiao Wang’s enthusiasm/ initiative to major in electronic engineering? 2．online payment网上支付，brings convenience to给…带来方便，at the cost of以…为代价，privacy隐私，故翻译为Online payment brings convenience to consumers at the cost of their privacy. 3．To my parents’ satisfaction令我父母满意的是，后者也那样so it is with。也可以用主语从句What makes my parents really satisfy 表语从句thatthey can see the Century Park from the dining room of this apartment。overlooks俯视，opposite the street街对面，living room 起居室。故翻译为To my parents’ satisfaction, the dining room of this apartment overlooks the Century Park opposite the street and so it is with the sitting room.或者What makes my parents really satisfy is that they can see the Century Park from the dining room of this apartment, so can they from the living room. 4．not well managed/ management is reckless疏于管理，be covered with dust/ be piled with dust被灰尘覆盖，few visitors游客稀少，be badly in need of improvement/ requires immediate improvement亟需改善。故翻译为his museum is not well managed, whose exhibits
精神分裂症的发病原因是什么 精神分裂症是一种精神病，对于我们的影响是很大的，如果不幸患上就要及时做好治疗，不然后果会很严重，无法进行正常的工作和生活，是一件很尴尬的事情。因此为了避免患上这样的疾病，我们就要做好预防，今天我们就请广州协佳的专家张可斌来介绍一下精神分裂症的发病原因。 精神分裂症是严重影响人们身体健康的一种疾病，这种疾病会让我们整体看起来不正常，会出现胡言乱语的情况，甚至还会出现幻想幻听，可见精神分裂症这种病的危害程度。 (1)精神刺激：人的心理与社会因素密切相关，个人与社会环境不相适应，就产生了精神刺激，精神刺激导致大脑功能紊乱，出现精神障碍。不管是令人愉快的良性刺激，还是使人痛苦的恶性刺激，超过一定的限度都会对人的心理造成影响。 (2)遗传因素：精神病中如精神分裂症、情感性精神障碍，家族中精神病的患病率明显高于一般普通人群，而且血缘关系愈近，发病机会愈高。此外，精神发育迟滞、癫痫性精神障碍的遗传性在发病因素中也占相当的比重。这也是精神病的病因之一。 (3)自身：在同样的环境中，承受同样的精神刺激，那些心理素质差、对精神刺激耐受力低的人易发病。通常情况下，性格内向、心胸狭窄、过分自尊的人，不与人交往、孤僻懒散的人受挫折后容易出现精神异常。 (4)躯体因素：感染、中毒、颅脑外伤、肿瘤、内分泌、代谢及营养障碍等均可导致精神障碍，。但应注意，精神障碍伴有的躯体因素，并不完全与精神症状直接相关，有些是由躯体因素直接引起的，有些则是以躯体因素只作为一种诱因而存在。 孕期感染。如果在怀孕期间，孕妇感染了某种病毒，病毒也传染给了胎儿的话，那么，胎儿出生长大后患上精神分裂症的可能性是极其的大。所以怀孕中的女性朋友要注意卫生，尽量不要接触病毒源。 上述就是关于精神分裂症的发病原因，想必大家都已经知道了吧。患上精神分裂症之后，大家也不必过于伤心，现在我国的医疗水平是足以让大家快速恢复过来的，所以说一定要保持良好的情绪。
文言文翻译技巧和方法 一、基本方法：直译和意译文言文翻译的基本方法有直译和意译两种。所谓直译，是指用现代汉语的词对原文进行逐字逐句地对应翻译，做到实词、虚词尽可能文意相对。直译的好处是字字落实;其不足之处是有时译句文意难懂，语言也不够通顺。所谓意译，则是根据语句的意思进行翻译，做到尽量符合原文意思，语句尽可能照顾原文词义。意译有一定的灵活性，文字可增可减，词语的位置可以变化，句式也可以变化。意译的好处是文意连贯，译文符合现代语言的表达习惯，比较通顺、流畅、好懂。其不足之处是有时原文不能字字落实。这两种翻译方法当以直译为主，意译为辅。 二、具体方法：留、删、补、换、调、变。 “留”：就是保留。凡是古今意义相同的词，以及古代的人名、地名、物名、官名、国号、年号、度量衡单位等，翻译时可保留不变。例如：《晏子使楚》中的“楚王”、“晏婴”、“晏子”等不用翻译。 “删”，就是删除。删掉无须译出的文言虚词。例如：“寡人反取病焉”的“焉”是语气助词，可不译，本句的意思就是“我反而自讨没趣。”(《晏子使楚》)又如：“子猷、子敬俱病笃，而子敬先亡”中的“而”是连词，可不译，整句意思是“子猷与子敬都病重，子敬先死去。” “补”，就是增补。(1)变单音词为双音词，如《桃花源记》中“率妻子邑人来此绝境”，“妻子”一词是“妻子、儿女”的意思;(2)补出省略句中的省略成分，如《人琴俱亡》中“语时了不悲”，翻译为：(子猷)说话时候完全不悲伤。 “换”，就是替换。用现代词汇替换古代词汇。如把“吾、余、予”等换成“我”，把“尔、汝”等换成“你”。“调”就是调整。把古汉语倒装句调整为现代汉语句式。例如《人琴俱亡》中“何以都不闻消息”，“何以”是“以何”的倒装，宾语前置句，意思是“为什么”。“变”，就是变通。在忠实于原文的基础上，活译有关文字。“子猷问左右”(人琴俱亡))中的“左右”指的是“手下的人”，“左右对曰”(《晏子使楚》中的“左右”指的是“近臣”。 古文翻译口诀古文翻译，自有顺序，首览全篇，掌握大意；先明主题，搜集信息，由段到句，从句到词，全都理解，连贯一起，对待难句，则需心细，照顾前文，联系后句，
精神分裂症的病因是什么 精神分裂症是一种精神方面的疾病，青壮年发生的概率高，一般 在16～40岁间，没有正常器官的疾病出现，为一种功能性精神病。 精神分裂症大部分的患者是由于在日常的生活和工作当中受到的压力 过大，而患者没有一个良好的疏导的方式所导致。患者在出现该情况 不仅影响本人的正常社会生活，且对家庭和社会也造成很严重的影响。 精神分裂症常见的致病因素： 1、环境因素：工作环境比如经济水平低低收入人群、无职业的人群中，精神分裂症的患病率明显高于经济水平高的职业人群的患病率。还有实际的生活环境生活中的不如意不开心也会诱发该病。 2、心理因素：生活工作中的不开心不满意，导致情绪上的失控，心里长期受到压抑没有办法和没有正确的途径去发泄，如恋爱失败， 婚姻破裂，学习、工作中不愉快都会成为本病的原因。 3、遗传因素：家族中长辈或者亲属中曾经有过这样的病人，后代会出现精神分裂症的机会比正常人要高。 4、精神影响：人的心里与社会要各个方面都有着不可缺少的联系，对社会环境不适应，自己无法融入到社会中去，自己与社会环境不相
适应，精神和心情就会受到一定的影响，大脑控制着人的精神世界， 有可能促发精神分裂症。 5、身体方面：细菌感染、出现中毒情况、大脑外伤、肿瘤、身体的代谢及营养不良等均可能导致使精神分裂症，身体受到外界环境的 影响受到一定程度的伤害，心里受到打击，无法承受伤害造成的痛苦，可能会出现精神的问题。 对于精神分裂症一定要配合治疗，接受全面正确的治疗，最好的 疗法就是中医疗法加心理疗法。早发现并及时治疗并且科学合理的治疗，不要相信迷信，要去正规的医院接受合理的治疗，接受正确的治 疗按照医生的要求对症下药，配合医生和家人，给病人创造一个良好 的治疗环境，对于该病的康复和痊愈会起到意想不到的效果。
卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规 范(试行)》的通知 【法规类别】采供血机构和血液管理 【发文字号】卫办医政发[2009]189号 【失效依据】国家卫生计生委办公厅关于印发造血干细胞移植技术管理规范(2017年版)等15个“限制临床应用”医疗技术管理规范和质量控制指标的通知 【发布部门】卫生部(已撤销) 【发布日期】2009.11.13 【实施日期】2009.11.13 【时效性】失效 【效力级别】部门规范性文件 卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范（试行）》的通知 （卫办医政发〔2009〕189号） 各省、自治区、直辖市卫生厅局，新疆生产建设兵团卫生局： 为贯彻落实《医疗技术临床应用管理办法》，做好脐带血造血干细胞治疗技术审核和临床应用管理，保障医疗质量和医疗安全，我部组织制定了《脐带血造血干细胞治疗技术管理规范（试行）》。现印发给你们，请遵照执行。 二〇〇九年十一月十三日
脐带血造血干细胞 治疗技术管理规范（试行） 为规范脐带血造血干细胞治疗技术的临床应用，保证医疗质量和医疗安全，制定本规范。本规范为技术审核机构对医疗机构申请临床应用脐带血造血干细胞治疗技术进行技术审核的依据，是医疗机构及其医师开展脐带血造血干细胞治疗技术的最低要求。 本治疗技术管理规范适用于脐带血造血干细胞移植技术。 一、医疗机构基本要求 （一）开展脐带血造血干细胞治疗技术的医疗机构应当与其功能、任务相适应，有合法脐带血造血干细胞来源。 （二）三级综合医院、血液病医院或儿童医院，具有卫生行政部门核准登记的血液内科或儿科专业诊疗科目。 1.三级综合医院血液内科开展成人脐带血造血干细胞治疗技术的，还应当具备以下条件： （1）近3年内独立开展脐带血造血干细胞和（或）同种异基因造血干细胞移植15例以上。 （2）有4张床位以上的百级层流病房，配备病人呼叫系统、心电监护仪、电动吸引器、供氧设施。 （3）开展儿童脐带血造血干细胞治疗技术的，还应至少有1名具有副主任医师以上专业技术职务任职资格的儿科医师。 2.三级综合医院儿科开展儿童脐带血造血干细胞治疗技术的，还应当具备以下条件：
英汉翻译的基本方法和技巧 翻译是信息交流过程中极其复杂的社会心理现象。语言知识是翻译的基础。此外，翻译还涉及到推理、判断、分析和综合等复杂的心理认识过程。翻译的方法和技巧是翻译工作者在长期的实践中根据两种语言的特点总结归纳出来的一般规律。这些规律可以指导我们的翻译实践，使我们能更自觉、更灵活地处理翻译过程中所遇到的各种语言现象。下面就英译汉中的一些方法和技巧结合翻译实例作一概述。 1. 词义的选择 一词多义和一词多类是英汉两种语言都有的一种语言现象。因此，在平日的翻译练习和测试中，我们在弄清原文句子结构后，务必注意选择和确定句中关键词的词类和词义，以保证译文的质量。通常可从以下三个方面来考虑词义选择： 1)根据词在句中的词类来选择词义 例如：Censorship is for the good of society as a whole. Like the law, it contributes to the common good. ［译文］：审查是为了整个社会的利益。它像法律一样维护公众利益。 ［注释］：本句中like作介词，意为"像……一样"。但like作动词用，则意为"喜欢；想要"。例如：He likes films with happy endings. (他喜欢结局好的电影。)又如：Would you like to leave a message? (你要不要留个话儿?)此外，like还可以作形容词用，意为"相同的"，如：Like charges repel; unlike charges attract.(电荷同性相斥，异性相吸。) 2)根据上下文和词在句中的搭配关系选择词义 例1 According to the new s chool of scientists, technology is an overlooked force in expanding the horizons of scientific knowledge. ［译文］：新学派的科学家们认为，技术在扩大科学知识范围过程中是一种被忽视的力量。 ［注释］：school一词常被误译为"学校"，其实，school还有一个词义"学派"。可见，正确选择词义对译文质量有重要影响，而文章的上下文和逻辑联系是翻译中选择词义的重要依据。 例2 Now since the assessment of intelligence is a comparative matter we must be sure that the scale with which we are comparing our subjects provides a "valid" or "fair" comparison. ［译文］：既然对智力的评估是比较而言的，那么我们必须确保，在对我们的对象进行比较时，我们所使用的尺度要能提供"有效的"和"公平的"比较。 ［注释］：许多人把scale译为"范围"，和文章的语篇意思和句子的确切含义大相径庭。
精神分裂症应该怎么治疗 1、坚持服药治疗 服药治疗是最有效的预防复发措施临床大量统计资料表明，大多数精神分裂症的复发与自行停药有关。坚持维持量服药的病人复发率为40%。而没坚持维持量服药者复发率高达80%。因此，病人和家属要高度重视维持治疗。 2、及时发现复发的先兆，及时处理 精神分裂症的复发是有先兆的，只要及时发现，及时调整药物和剂量，一般都能防止复发，常见的复发先兆为：病人无原因出现睡眠不好、懒散、不愿起床、发呆发愣、情绪不稳、无故发脾气、烦躁易怒、胡思乱想、说话离谱，或病中的想法又露头等。这时就应该及时就医，调整治疗病情波动时的及时处理可免于疾病的复发。 3、坚持定期门诊复查 一定要坚持定期到门诊复查，使医生连续地、动态地了解病情，使病人经常处于精神科医生的医疗监护之下，及时根据病情变化调整药量。通过复查也可使端正人及时得到咨询和心理治疗解除病人在生活、工作和药物治疗中的各种困惑，这对预防精神分裂症的复发也起着重要作用。 4、减少诱发因素 家属及周围人要充分认识到精神分裂症病人病后精神状态的薄弱性，帮助安排好日常的生活、工作、学习。经常与病人谈心，帮助病人正确对待疾病，正确对待现实生活，帮助病人提高心理承受能力，学会对待应激事件的方法，鼓励病人增强信心，指导病人充实生活，使病人在没有心理压力和精神困扰的环境中生活。 首先是性格上的改变，塬本活泼开朗爱玩的人，突然变得沉默寡言，独自发呆，不与人交往，爱干净的人也变的不注意卫生、生活
懒散、纪律松弛、做事注意力不集中，总是和患病之前的性格完全 相悖。 再者就是语言表达异常，在谈话中说一些无关的谈话内容，使人无法理解。连最简单的话语都无法准确称述，与之谈话完全感觉不 到重心。 第三个就是行为的异常，行为怪异让人无法理解，喜欢独处、不适意的追逐异性，不知廉耻，自语自笑、生活懒散、时常发呆、蒙 头大睡、四处乱跑，夜不归宿等。 还有情感上的变化，失去了以往的热情，开始变的冷淡、对亲人不关心、和友人疏远，对周围事情不感兴趣，一点消失都可大动干戈。 最后就是敏感多疑，对任何事情比较敏感，精神分裂症患者，总认为有人针对自己。甚至有时认为有人要害自己，从而不吃不喝。 但是也有的会出现难以入眠、容易被惊醒或睡眠不深，整晚做恶梦或者长睡不醒的现象。这些都有可能是患上了精神分裂症。 1.加强心理护理 心理护理是家庭护理中的重要方面，由于社会上普遍存在对精神病人的歧视和偏见，给病人造成很大的精神压力，常表现为自卑、 抑郁、绝望等，有的病人会因无法承受压力而自杀。家属应多给予 些爱心和理解，满足其心理需求，尽力消除病人的悲观情绪。病人 生活在家庭中，与亲人朝夕相处，接触密切，家属便于对病人的情感、行为进行细致的观察，病人的思想活动也易于向家属暴露。家 属应掌握适当的心理护理方法，随时对病人进行启发与帮助，启发 病人对病态的认识，帮助他们树立自信，以积极的心态好地回归社会。 2.重视服药的依从性 精神分裂症病人家庭护理的关键就在于要让病人按时按量吃药维持治疗。如果不按时服药，精神病尤其是精神分裂症的复发率很高。精神病人在医院经过一系统的治疗痊愈后，一般需要维持2~3年的
英语翻译技巧 5.拆句法和合并法： 这是两种相对应的翻译方法。拆句法是把一个长而复杂的句子拆译成若干个较短、较简单的句子，通常用于英译汉；合并法是把若干个短句合并成一个长句，一般用于汉译英。汉语强调意合，结构较松散，因此简单句较多；英语强调形合，结构较严密，因此长句较多。所以汉译英时要根据需要注意利用连词、分词、介词、不定式、定语从句、独立结构等把汉语短句连成长句；而英译汉时又常常要在原句的关系代词、关系副词、主谓连接处、并列或转折连接处、后续成分与主体的连接处，以及意群结束处将长句切断，译成汉语分句。这样就可以基本保留英语语序，顺译全句，顺应现代汉语长短句相替、单复句相间的句法修辞原则。如： （1） Increased cooperation with China is in the interests of the United States. 同中国加强合作，符合美国的利益。（在主谓连接处拆译） （2）I wish to thank you for the incomparable hospitalityfor which the Chinese people are justly famous throughout the world. 我要感谢你们无与伦比的盛情款待。中国人民正是以这种热情好客而闻明世界的。（在定语从句前拆译） 6.倒置法： 在汉语中，定语修饰语和状语修饰语往往位于被修饰语之前；在英语中，许多修饰语常常位于被修饰语之后，因此翻译时往往要把原文的语序颠倒过来。倒置法通常用于英译汉, 即对英语长句按照汉语的习惯表达法进行前后调换，按意群或
进行全部倒置，原则是使汉语译句安排符合现代汉语论理叙事的一般逻辑顺序。有时倒置法也用于汉译英。如： （1）At this moment, through the wonder of telecommunications, more people are seeing and hearing what we say than on any other occasions in the whole history of the world. 此时此刻，通过现代通信手段的奇迹，看到和听到我们讲话的人比整个世界历史上任何其他这样的场合都要多。（部分倒置） （2）I believe strongly that it is in the interest of my countrymen that Britain should remain an active and energetic member of the European Community. 我坚信，英国依然应该是欧共体中的一个积极的和充满活力的成员，这是符合我国人民利益的。（部分倒置） （3）改革开放以来，中国发生了巨大的变化。 Great changes have taken place in China since the introduction of the reform and opening policy.(全部倒置) 7.倒置法： 在汉语中，定语修饰语和状语修饰语往往位于被修饰语之前；在英语中，许多修饰语常常位于被修饰语之后，因此翻译时往往要把原文的语序颠倒过来。倒置法通常用于英译汉, 即对英语长句按照汉语的习惯表达法进行前后调换，按意群或进行全部倒置，原则是使汉语译句安排符合现代汉语论理叙事的一般逻辑顺序。有时倒置法也用于汉译英。如： （1）At this moment, through the wonder of telecommunications, more people are seeing and hearing what we say than on any other occasions in the whole history of the world.
卫生部关于印发《脐带血造血干细胞库设置管理规范(试行)》的通知 发文机关：卫生部(已撤销) 发布日期： 2001.01.09 生效日期： 2001.02.01 时效性：现行有效 文号：卫医发(2001)10号 各省、自治区、直辖市卫生厅局： 为贯彻实施《脐带血造血干细胞库管理办法（试行）》，保证脐带血临床使用的安全、有效，我部制定了《脐带血造血干细胞库设计管理规范（试行）》。现印发给你们，请遵照执行。 附件：《脐带血造血干细胞库设置管理规范（试行）》 二○○一年一月九日 附件： 脐带血造血干细胞库设置管理规范（试行） 脐带血造血干细胞库的设置管理必须符合本规范的规定。 一、机构设置 （一）脐带血造血干细胞库（以下简称脐带血库）实行主任负责制。 （二）部门设置 脐带血库设置业务科室至少应涵盖以下功能：脐带血采运、处理、细胞培养、组织配型、微生物、深低温冻存及融化、脐带血档案资料及独立的质量管理部分。 二、人员要求
（一）脐带血库主任应具有医学高级职称。脐带血库可设副主任，应具有临床医学或生物学中、高级职称。 （二）各部门负责人员要求 1．负责脐带血采运的人员应具有医学中专以上学历，2年以上医护工作经验，经专业培训并考核合格者。 2．负责细胞培养、组织配型、微生物、深低温冻存及融化、质量保证的人员应具有医学或相关学科本科以上学历，4年以上专业工作经历，并具有丰富的相关专业技术经验和较高的业务指导水平。 3．负责档案资料的人员应具相关专业中专以上学历，具有计算机基础知识和一定的医学知识，熟悉脐带血库的生产全过程。 4．负责其它业务工作的人员应具有相关专业大学以上学历，熟悉相关业务，具有2年以上相关专业工作经验。 （三）各部门工作人员任职条件 1．脐带血采集人员为经过严格专业培训的护士或助产士职称以上卫生专业技术人员并经考核合格者。 2．脐带血处理技术人员为医学、生物学专业大专以上学历，经培训并考核合格者。 3．脐带血冻存技术人员为大专以上学历、经培训并考核合格者。 4．脐带血库实验室技术人员为相关专业大专以上学历，经培训并考核合格者。 三、建筑和设施 （一）脐带血库建筑选址应保证周围无污染源。 （二）脐带血库建筑设施应符合国家有关规定，总体结构与装修要符合抗震、消防、安全、合理、坚固的要求。 （三）脐带血库要布局合理，建筑面积应达到至少能够储存一万份脐带血的空间；并具有脐带血处理洁净室、深低温冻存室、组织配型室、细菌检测室、病毒检测室、造血干/祖细胞检测室、流式细胞仪室、档案资料室、收/发血室、消毒室等专业房。 （四）业务工作区域应与行政区域分开。
精神分裂症患者在怎样的情况下会自杀 精神分裂症是最常见的一种精神病。早期主要表现为性格改变，如不理采亲人、不讲卫生、对镜子独笑等。病情进一步发展，即表现为思维紊乱，病人的思考过程缺乏逻辑性和连贯性，言语零乱、词不达意。精神分裂症患者随时有可能出现危险行为，这主要是指伤人毁物、自伤自杀和忽然出走。这些危险行为是受特定的精神症状支配的.那么精神分裂症患者在什么情况下会自杀呢？ 被害妄想：这是所有精神病人最常见的症状之一，多数病人采取忍耐、逃避的态度，少数病人也会“先下手为强”，对他的“假想敌”主动攻击。对此，最重要的是弄清病人的妄想对象，即：病人以为是谁要害他。假如病人的妄想对象是某个家里人，则应尽量让这位家属阔别病人，至少不要让他与病人单独在一起。 抑郁情绪：精神分裂症病人在疾病的不同时期，可能出现情绪低落，甚至悲观厌世。特别需要留意的是，有相当一部分自杀成功的病人，是在疾病的恢复期实施自杀行为的。病人在精神病症状消除以后，因自己的病背上了沉重的思想包袱，不能正确对待升学、就业、婚姻等现实问题，感到走投无路，因此选择了轻生。对此，家属一定要防患于未然，要尽早发现病人的心理困扰，及时疏导。 对已经明确表示出自杀观念的病人，家属既不要惊慌失措，也不要躲躲闪闪，要主动与病人讨论自杀的利弊，帮助病人全面、客观地评估现实中碰到的各种困难，找出切实可行的解决办法。 另外，这种病人在自杀之前，是经过周密考虑，并且做了充分预备的，例如写遗书、收拾旧物、向家人离别、选择自杀时间、预备自杀工具等。这类病人的自杀方式也是比较温顺的，多数是服药自杀。因此，他需要一定的时间来积攒足足数目的药物，这时就能看出由家属保管药品的重要性了。只要家属密切观察病人的情绪变化，是不难早期发现病人的自杀企图的。 药源性焦虑：抗精神病药的副作用之一是可能引起病人莫名的焦躁不安、手足无措，并伴有心慌、出汗、恐惧等。这些表现多是发作性的，多数发生在下午到傍晚时分，也有的病人在打长效针以后的2?3天内出现上述表现。这种时间上的规律性，有助于家属判定病人的焦虑情绪是否由于药物所致。病人急于摆脱这种强烈的痛苦，会出现冲动伤人或自伤，这些行为只是为了发泄和解脱，并不以死为终极目的。家属可以在病人发作时，给他服用小剂量的安定类药物，或者在医生的指导下，调整抗精神病药的剂量或品种，这样就可以有效地控制病人的焦虑发作。 极度兴奋：病人的精神症状表现为严重的思维紊乱、言语杂乱无章、行为缺乏目的性，这类病人也可能出现自伤或伤人毁物。由于病人的兴奋躁动是持续性的，家属有充分的思想预备，一般比较轻易防范。家属要保管好家里的刀、剪、火、煤气等危险物品，但最根本的办法，是使用大剂量的、具有强烈镇静作用的药物来控制病人的兴奋。假如在家里护理病人确有困难，则可以强制病人住院治
常用翻译方法和技巧 1. 四种翻译方法 1.1直译和意译 所谓直译，就是在译文语言条件许可时，在译文中既保持原文的内容，又保持原文的形式——特别指保持原文的比喻、形象和民族、地方色彩等。 每一个民族语言都有它自己的词汇、句法结构和表达方法。当原文的思想内容与译文的表达形式有矛盾不宜采用直译法处理时，就应采用意译法。意译要求译文能正确表达原文的内容，但可以不拘泥与原文的形式。（张培基） 应当指出，在再能确切的表达原作思想内容和不违背译文语言规范的条件下，直译有其可取之处，一方面有助于保存原著的格调，另一方面可以进新鲜的表达方法。 Literal translation refers to an adequate representation of the original. When the original coincides or almost tallies with the Chinese language in the sequence of vocabulary, in grammatical structure and rhetorical device, literal translation must be used. Free translation is also called liberal translation, which does not adhere strictly to the form or word order of the original.（郭著章） 直译法是指在不违背英语文化的前提下，在英译文中完全保留汉语词语的指称意义，求得内容和形式相符的方法。 意译是指译者在受到译语社会文化差异的局限时，不得不舍弃原文的字面意义，以求疑问与原文的内容相符和主要语言功能的相似。（陈宏薇） 简单地说，直译指在译文中采用原作的的表达方法，句子结构与原句相似，但也不排除在短语层次进行某些调整。 意译指在译文中舍弃原作的表达方法，另觅同意等效的表达方法，或指对原作的句子结构进行较大的变化或调整。（杨莉藜） Literal translation may be defined as having the following characteristics: 1, literal translation takes sentences as its basic units and the whole text into consideration at the same time in the course of translating. 2, literal translation strives to reproduce both the ideological content and style of the entire literary work and retain as much as possible the figures of speech and such main sentence structures or patterns as SV,SVO, SVC, SVA, SVOO, SVOC, SVOA formulated by Randolph Quirk, one of the authors of the book A Comprehensive Grammar of the English Language. Free translation may be defined as a supplementary means to mainly convey the meaning and spirit of the original without trying to reproduce its sentence patterns or figures of speech. And it is adopted only when and where it is really impossible for translators to do literal translation. (Liu Zhongde). 练习： 1. He walked at the head of the funeral procession, and every now and then wiped his crocodile tears with a big handkerchief. 他走在送葬队伍的前头，还不时用一条大手绢擦一擦他的鳄鱼泪。 2. It’s an ill wind that blows nobody good. 对有些人有害的事情可能对另一些人有利。 3. Every dog has his day. 人人皆有得意日。