Adult human liver slice cultures: Modelling of liver fibrosis and evaluation of new anti-fibrotic drugs

BACKGROUND

Liver fibrosis can result in end-stage liver failure and death.

AIM

To examine human liver fibrogenesis and anti-fibrotic therapies, we evaluated the three dimensional ex vivo liver slice (LS) model.

METHODS

Fibrotic liver samples (F0 to F4 fibrosis stage according to the METAVIR score) were collected from patients after liver resection. Human liver slices (HLS) were cultivated for up to 21 days. Hepatitis C virus (HCV) infection, alcohol (ethanol stimulation) and steatosis (palmitate stimulation) were examined in fibrotic (F2 to F4) liver slices infected (or not) with HCV. F0-F1 HLS were used as controls. At day 0, either ursodeoxycholic acid (choleretic and hepatoprotective properties) and/or α-tocopherol (antioxidant properties) were added to standard of care on HLS and fibrotic liver slices, infected (or not) with HCV. Expression of the biomarkers of fibrosis and the triglyceride production were checked by quantitative reverse transcription polymerase chain reaction and/or enzyme-linked immunosorbent assay.

RESULTS

The cultures were viable in vitro for 21 days allowing to study fibrosis inducers and to estimate the effect of anti-fibrotic drugs. Expression of the biomarkers of fibrosis and the progression to steatosis (estimated by triglycerides production) was increased with the addition of HCV and /or ethanol or palmitate. From day 15 of the follow-up studies, a significant decrease of both transforming growth factor β-1 and Procol1A1 expression and triglycerides production was observed when a combined anti-fibrotic treatment was applied on HCV infected F2-F4 LS cultures.

CONCLUSION

These results show that the human three dimensional ex vivo model effectively reflects the in vivo processes in damaged human liver (viral, alcoholic, nonalcoholic steatohepatitis liver diseases) and provides the proof of concept that the LS examined model permits a rapid evaluation of new anti-fibrotic therapies when used alone or in combination.

Hepatitis C virus: Morphogenesis, infection and therapy

Hepatitis C virus (HCV) is a major cause of liver diseases including liver cirrhosis and hepatocellular carcinoma. Approximately 3% of the world population is infected with HCV. Thus, HCV infection is considered a public healthy challenge. It is worth mentioning, that the HCV prevalence is dependent on the countries with infection rates around 20% in high endemic countries. The review summarizes recent data on HCV molecular biology, the physiopathology of infection (immune-mediated liver damage, liver fibrosis and lipid metabolism), virus diagnostic and treatment. In addition, currently available in vitro, ex vivo and animal models to study the virus life cycle, virus pathogenesis and therapy are described. Understanding of both host and viral factors may in the future lead to creation of new approaches in generation of an efficient therapeutic vaccine.

[DNA vaccine encoding alpha-fetoprotein with fused ornithine decarboxylase degradation signal significantly suppresses hepatocellular carcinoma growth in mice]

Hepatocellular carcinoma (HCC) is among the most frequent malignancies in humans. HCC therapy is not efficient and the usual outcome is poor. In this regard, novel approaches to treat and prevent HCC are urgently needed. The Alpha-fetoprotein (AFP) is a serological marker of HCC. Recently it has been shown, that the DNA vaccines expressing AFP are capable in generating immune response against AFP. However, both, the immunization procedures and DNA vaccines used before were complex and not always very effective. We have shown that DNA vaccine encoding HIV-1 reverse transcriptase (RT) with fused ornithine decarboxylase (ODC) degradation signal induced a strong Th-1 immune response against RT in mice. Using this approach we designed a set of novel DNA vaccines bearing AFP and ODC degradation signal. Results obtained on transfected cells demonstrated efficient expression and fast proteasomal degradation of the recombinant AFP. The anti-tumor immune response stimulation was shown in immunized animals and most importantly a notable retardation of tumor growth was observed as a result of protective vaccination.

[Critical amino acids of ornitin decarboxylase degron: the presence and C-terminal arrangement is insufficient for alfa-fetoprotein degradation]

Mouse ornithine decarboxylase (ODC) degrades in proteasome in an ubiquitin-independent manner with an averagehalf-life of 2 h. The 37 amino acid long C-terminal fragment known as a degradation signal (degron) is responsible for the effective degradation of ODC. Recently, amino acids being critical for degradation in the ODC-degron have been mapped. Mutations of Cys441 and Ala442 led to protein stabilization, while a substitution of other amino acids composing ODC-degron had almost no effect on the protein turnover; whereas insertions or deletions in region between Ala442 and ODC C-terminus diminished greatly rate of protein degradation, e.g. positioning of the key amino acids from the C-terminus was shown to be crucial. Using these data we introduced both key amino acids into the alfa-fetoprotein with truncated exportation signal (deltaAFP), at the same distance from the C-terminus as they being in the ODC (deltaAFPCAG and deltaAFPLCAG). Removal of N-terminal exportation signal prevented secretion of modified proteins. Using in silico approach we demonstrated no significant difference in hydrophobicity or secondary structure between C-terminus of deltaAFP and mutated proteins. The degradation kinetics of deltaAFP, deltaAFPCAG, deltaAFPLCAG in cyloheximide-chase and proteasome inhibition assay (using MG132) was identical. Obtained results suggest that introduced substitutions are insufficient for effective recognition of mutated deltaAFP by26S proteasome. We assume thatadditional amino aci ds composing ODC-degron or their combine action could also affect degradation. Besides that, one cannot exclude that conformation of the mutated deltaAFP limits its C-terminus accessibility to proteasome.

[Alpha oscillations of human brain elicited by illusory contour perception]

We examined the changes in the phase-locked and total alpha oscillations of EEG during perception of illusory (Kanizsa square) and non-illusory images in 16 healthy adults. We applied a wavelet-based time-frequency analysis to compute alpha band power, statistical evaluation was performed using repeated-measures ANOVA and the non-parametric multi-way analysis. Results showed that both stimuli provoked an initial increase of total alpha power emerging not later than in 100 ms after the stimulus onset. The increase was caused by the phase-locked alpha response, and the illusory contour was systematically followed by a higher level of alpha power than the non-illusory one. Further suppression of total alpha power occurred within the time window of 200-500 ms after the stimulus onset and did not depend on the stimulus type. Both stages of the total alpha response were more prominent over the parieto-occipito-temporal scalp areas. We hypothesize that the first stage of alpha response is related to the modulation of the activity of neural circuits participating in processing of a coherent pattern whereas a later suppression of total alpha power links to the orienting processes.

Endogenous JSRV-like proviruses in domestic cattle: analysis of sequences and transcripts

Jaagsiekte retrovirus is an exogenous (exJSRV) beta-retrovirus with a simple genome. It causes lower airway epithelial cell tumors in small ruminants. Endogenous (enJSRV) counterparts of exJSRV are present in different copy numbers in numerous Bovidae family members. This work has focused on enJSRV in Simmental (Germany) and Limousine (France) beef breeds of domestic cattle and domestic goat. Of the enJSRV sequences in cattle, the orf-x sequences were about 99% identical, the LTR sequences were about 97% identical and the env sequences were nearly 95% identical to the corresponding endogenous sequences in sheep. A significant polymorphism of the proviral sequences between the cattle breeds was noted. Clonal analyses of the amplicons suggest two enJSRV proviruses in cattle genome. The endogenous sequences revealed in goat were closer to enzootic nasal tumor virus (ENTV) from goat rather than to enJSRV from sheep. The expression of enJSRV in cattle was partial (env only) and detected exclusively in bone marrow.

Detection and characterization of betaretroviral sequences, related to sheep Jaagsiekte virus, in Africans from Nigeria and Cameroon

Jaagsiekte retrovirus (JSRV) causes ovine pulmonary adenomatosis (OPA) that resembles bronchioloalveolar carcinoma (BAC) in humans. To test the possible role of JSRV in human diseases, DNA specimens from 103 individuals either healthy or suffering from lung carcinomas were analyzed for JSRV sequences. orf-x sequences were detected in 19 of 64 samples and gag-prt sequences in 4 of 38 samples, predominantly in individuals from Africa. Sequences obtained from orf-x amplimers varied in-between each other and differed from control endogenous ovine JSRV sequence. No association with lung cancer was found. This is the first report of JSRV-like sequences detected in humans.

Defective human T-cell leukaemia virus type 1 (HTLV-1) genomes: no evidence in serologically indeterminate german blood donors but new type detected in established cell lines

Individuals reactive in antibody screening tests (ELISA) and with one or more reactions to HTLV-1 proteins on Western blotting, but lacking the criteria of a confirmed HTLV infection, are not exceptional in regions with a low prevalence of HTLV-1/-2 infections. PCR analysis of these indeterminate samples, using "diagnostic" pol and tax sets of primers, give negative results. However, expression of HTLV-1 defective proviruses with internal deletions undetectable by PCR with diagnostic primers could have taken place. Seven German HTLV-1 ELISA-reactive blood donors, who showed reactivity also in Western blots against several viral proteins, and twenty haemophiliacs, were examined by nested PCR and/or PCR/Southern hybridisation with primers designed for detection of HTLV-1 defective proviruses. No HTLV-1-specific amplification products were obtained. However, HTLV-1 defective proviruses with large internal deletions were detected in four out of five cell lines established from symptomatic HTLV-1 cases and two in HUT-102 cells. In two amplicons, short inverted rRNA sequences between gag and env fragments of HTLV-1 defective proviruses were revealed. These results do not exclude the presence of defective HTLV-1 proviruses in individuals with indeterminate serology although this is unlikely.

[C-reactive protein and defect in lipid transport blood system in patients with rheumatoid arthritis]

In 88 patients with rheumatoid arthritis lipid-protein spectrum of the blood serum were determined biochemically and by means of nefelometric technique, C-reactive protein (CRP) was measured with enzyme immunoassay. An increase in CRP concentration was associated with lowering of apoA1 and HDL FL, triglycerides. Thus, elevation of CRP in RA reflects not only activity of inflammation but also defects in serum lipid-transport system by the atherogenic type.

[Defective proviruses of the human T-cell leukemia virus: structure and classification]

Peripheral blood mononuclear cells of 24-70% individuals infected with HTLV-1 contain defective proviruses (dp) in addition to the full size ones. Most of them remain silent lacking regions sufficient for viral genes transcription except those activated under cell promoter or retaining viral open reading frames (orfs). It is still unclear whether these proviruses are associated with the development of T-cell leukemia in adults, tropic spastic paresis, or myelopathy. Classification of previously reported dp is presented, their origin and possible function in human HTLV-1 associated diseases are discussed.

Path-dependent neutralization of multiply charged Ar ions incident on Au(110)

Using a time-of-flight technique we have investigated the backscattering of 5 keV Ar(2+) and Ar(11+) projectiles from Au(110). A strong dependence on target azimuth is found for the neutral flux resulting from (quasi)binary projectile collisions with target atoms, while for the charged components only a weak dependence is seen. A deconvolution of the observed dependences based on trajectory simulations clearly shows site-specific neutralization differences between the various possible binary collisions occurring with surface atoms. Such differences must be properly accounted for in order to permit meaningful comparison with theory.

Chimeric matrix proteins encoded by defective proviruses with large internal deletions in human T-cell leukemia virus type 1-infected humans

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia/lymphoma (ATLL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and other diseases. The mechanisms of virus pathogenesis are still obscure. The occurrence of defective proviruses in HTLV-1-infected cell lines and the peripheral blood mononuclear cells (PBMC) of infected individuals is a frequent feature of virus infection. We detected defective proviruses with large internal deletions in PBMC from ATLL and HAM/TSP patients and in asymptomatic HTLV-1 carriers. Seventeen PCR-amplified defective proviruses were sequenced, and three types of deletions were found. Besides truncated MA and the 5' end of the genome, truncated CA, truncated SU, and more frequently truncated TM linked to the pX region were detected. Reverse transcription-PCR analysis of PBMC from ATLL patients and asymptomatic carriers also revealed RNA transcripts with large internal deletions. Analysis of two RT-PCR cDNA clones confirmed a Gag-TM-pX structure of the transcripts. Most defective proviruses contained numerous internal stop codons, but some were capable of coding for the truncated MA linked to a variable out-of-frame peptide. Cloned defective proviruses with long open reading frames were subjected to in vitro transcription-translation followed by radioimmunoprecipitation, which showed expression of chimeric proteins between 8 and 12 kDa. Possible roles of defective proviruses and chimeric proteins are discussed, although there is no firm association with pathogenesis.

Two types of HTLV-1 particles are released from MT-2 cells

The MT-2 cell line transformed by human T-cell leukemia virus type 1 (HTLV-1) contains one complete provirus and seven defective proviruses. Four defective genomes have an identical structure (LTR-MA-deltaCA-pX-LTR) with an open reading frame that spans from MA to pX, giving rise to a 3.4-kb (24S) RNA transcript encoding a chimeric Gag-pX protein, p28. MT-2 cells release two distinct types of virions. The major "classic" type of particle has a buoyant density of 1.155-1.16 g/cm3 and contains the standard HTLV-I structural proteins and reverse transcriptase (RT). In addition, about 5% of particles are "light," approximately 1.12 g/cm3, and contain p28, RT activity, and the 3.4-kb RNA transcript. RT-PCR and in vitro translation indicate that some of the classic HTLV-1 particles package 3.4-kb RNA as well as full-length 8.5-kb RNA. In addition to matrix features, the p28 protein has a motif resembling a zinc finger at the C-terminal, pX0 region, which may play a role in the assembly of the defective light virions.

Plasmovirus: replication cycle of a novel nonviral/viral vector for gene transfer

We recently described a novel nonviral/viral vector for gene transfer, the plasmovirus (Noguiez-Hellin P, Robert-le Meur M, Laune S, et al. C R Acad Sci Paris, Sciences de la Vie. 1996;319:45-50; Noguiez-Hellin P, Robert-le Meur M, Salzmann J-L, et al. Proc Natl Acad Sci USA. 1996;93:4175-4180). Plasmoviruses are plasmids capable of expressing all the viral genes required for generating infectious particles and packaging a defective genome containing a transgene. Transfected as plasmids, plasmoviruses transform the transduced cells into packaging cells that release infectious replication-defective retrovirus vectors (RV) containing a transgene, which are capable of infecting nearby cells. We previously showed that such a vector can efficiently "propagate" the transgene after transfection. Here we examine in greater detail the different steps of plasmovirus replication in vitro in human (143 B TK-) and murine (NIH 3T3 TK-) cells. Molecular-biological analysis revealed plasmovirus-coded protein expression starting from 24 hours post-transfection, followed by the detection of infectious RV 48 hours post-transfection. The gag proteins were correctly processed in the released particles. Electron microscopic analysis revealed typical type C particles. Nonintegrated plasmovirus DNA was not toxic for the cells and could be detected for at least 14 days post-transfection. While the transfected gag gene and the transgene could also be detected throughout this period, we observed that env-coded proteins decreased after 72 hours post-transfection. Nevertheless, the production of RV resulted in the propagation of the transgene in the culture, with stable integration of plasmovirus proviral DNA into the host genome of infected cells. We show that this propagation results in a major improvement in therapeutic efficacy using an HSV1-TK transgene and ganciclovir treatment, when compared to that of plasmovirus constructs that cannot propagate. Altogether, these results demonstrate the functionality of this gene transfer method and suggest that improvements in the vector design enhance its efficacy.

Protein composition and morphology of human foamy virus intracellular cores and extracellular particles

Characterization of human foamy virus (HFV) gag-encoded precursors and the search for a Gag-Pol polyprotein and mature proteins derived from proteolytic processing were carried out in HFV-infected cells and with purified preassembled cores and extracellular virus by Western blotting and radioimmunoprecipitation using antisera against synthetic peptides corresponding to putative Gag and protease proteins. Precursor proteins, Pr78gag/74gag and Pr135pol, were found in the nucleus of epithelial and fibroblast cells 3-4 days after HFV infection. Kinetic analysis of HFV Pr78gag and Pr74gag indicated that Pr78gag is a precursor to Pr74gag. South-Western blot analysis indicated that Pr78gag and Pr74gag have properties associated with nucleic acid binding protein although they lack the typical zinc-finger motifs found in retroviral nucleocapsid proteins. Western blot analyses of preassembled HFV cores isolated from the cytoplasm of infected cells and purified by sucrose gradient centrifugation demonstrated the presence of Pr78gag/74gag and Pr135pol, but no proteolytically processed Gag proteins were observed. The majority of extracellular HFV particles were found to have pentagon-shaped cores, as observed intracellularly, and are believed to be the immature extracellular form of the virus. The highest concentration of extracellular particles, estimated by EM, Western blot, and reverse transcriptase assays were found in sucrose gradient fractions having a density of 1.21-1.24 g/cm3. Western blot analysis revealed that Pr78gag/74gag and Pr135pol were the major viral proteins associated with these extracellular particles, as only small amounts of putative proteolytically cleaved capsid (p32) were observed. Our results support the notion that Pol is translated independent of Gag in HFV-infected cells.

Type D retrovirus markers in healthy Africans from Guinea

Sixteen matching sera and DNA samples from healthy African blood donors living in rural areas of Guinea were analysed for the presence of type D retrovirus markers. Screening for the antibodies against structural proteins of Mason-Pfizer monkey virus (M-PMV) was carried out by Western blot with a purified M-PMV as an antigen. Eight out of 16 sera samples were found to contain antibodies against at least two gag gene-coded proteins, and three of these were weakly positive against env gene-coded protein. Using PCR amplification and Southern hybridization, we detected M-PMV-like gag sequences in 11 out of 16 samples and env-related sequences in 8 out of 16 samples. Six DNAs were found to contain both M-PMV gag- and env-related sequences. Restriction endonuclease analysis of the PCR-amplified gag sequences from two individuals and direct DNA sequencing analysis of the amplimers confirmed their M-PMV-like origin. Detection of antibodies and M-PMV-related sequences in blood donors from Guinea, but not in French or Algerian blood donors, indicated exogenous SRV infection in humans from certain geographic areas of Western Africa.

[Detection of markers of the human T-cell leukemia virus in patients with T-cell lymphoma and Kaposi's sarcoma]

Nine patients with Kaposi's sarcoma and five suffering from T-cell lymphoma have been examined. Antibodies to HTLV-1 were not found in these patients. The primary cellular cultures were isolated from blood and lymph nodes of the patients. Viral particles (type C) were found in the culture obtained from the patient with lymphoma of T-cell origin. DNAs from the primary cellular cultures from patients with lymphoma or sarcoma contained the sequences homologous to gag-gene of HTLV-1. The data suppose the patients with T-cell lymphoma and Kaposi's sarcoma to carry HTLV-1 virus.

High level of HTLV-I specific protein expression in a patient with adult T-cell leukemia, chronic progressive myelopathy and Kaposi's sarcoma

Analysis was made of serum anti-HTLV-I antibodies, virus-specific proteins in peripheral blood lymphocytes (PBL) and proviruses in lymphocyte DNA of a patient with adult T-cell leukemia (ATL), Kaposi's sarcoma, and chronic myelopathy. Using Western blot and PCR (with HIV-1 specific primers), it was shown that Kaposi's sarcoma was not linked to HIV infection. Western blot analysis of serum revealed antibodies against p19, p24 and Pr 53 of HTLV-I. Examination of proteins in fresh PBL by Western blot revealed a high level of HTLV-I specific protein expression. Southern blot analysis of the patient's DNA revealed two different sites for HTLV-I provirus integration.

Antibodies to gag gene coded polypeptides of type D retroviruses in healthy people from Guinea-Bissau

Antibodies to proteins of Mason-Pfizer monkey virus (M-PMV) were screened in sera from 61 healthy donors living in Guinea-Bissau (4 HIV-1 and HIV-2 antibody positive HIV = human immunodeficiency virus), from 19 healthy French European blood donors, and from 9 French patients with induced immunodeficiency prior to bone marrow transplantation (all HIV-1 antibody negative). In 30 (49%) of the African sera tested, antibodies reacting against p27 and/or p14 were detected by western blot. Some of these cases were confirmed to be positive using radioimmuno precipitation assay. Only one serum from a French blood donor was detected by western blot to be slightly positive against p27 M-PMV. Thirty-two sera screened for M-PMV were also tested for squirrel monkey retrovirus by western blot. In eight (25%) sera antibodies at least against p36 were detected. Among squirrel monkey retrovirus positive sera, three were also positive with p27 M-PMV. The other five were found to be M-PMV negative.

Study of the gag-coded polyproteins of type D retroviruses. Block of glycosylation inhibits the processing of major structural protein

The study of the gag-coded glycosylated polyprotein (gPr78gag) from type D retrovirus-producing cells is reported. It is shown that glycosylation inhibitors tunicamycin and 2-deoxy-D-glucose are blocking the synthesis of gPr78gag. This demonstrates that gPr78gag is a N-glycan. The protein part of gPr78gag is supposedly identified (MW = 65 k). The inhibitors used partially stopped the processing of gag-coded polyprotein Pr78gag into core protein p27 as shown in pulse-chase experiments.

[The mechanism of water transport in the epidermis]

Possible mechanisms of water transport through Stratum Corneum (SC) in the process of insensible perspiration are investigated. Electrometric methods developed for measuring water flow density through SC are used. Data showing the reverse osmotic mechanism of water transport through the SC selective membrane are obtained. It is shown that the water flow density through SC controlling the evaporation rate from the skin surface in the process of insensible perspiration depends upon the skin capillary pressure.

Chrysanthemum virus B: antibodies to structural protein in mammals and Mg2(+)-dependent reverse-transcriptase activity

Human plasma has been found to contain antibodies reacting with the structural protein of chrysanthemum virus B (CV-B) and about 10 times less intensively with the structural protein of another carlavirus, the potato virus M. It has been shown that the antibodies bind to CV-B through their F(ab)2 fragments. No reaction with proteins of other plant viruses or retroviruses was observed. Antibodies reacting with CV-B protein are also present in the plasma of green monkey, goat, rabbit, and mouse, their level being somewhat lower than in man. In addition, Mg2(+)-dependent reverse transcriptase activity reaching maximum at 37 degrees C was detected in the CV-B preparations. It is suggested that humans and the mammals in question developed antibodies to CV-B which could enter into some enzymatic reactions at the body temperature.

[Antibodies against structural proteins of carlaviruses in human and other mammals]

The study of four isolates of chrysanthemum B-virus (CVB) has shown the virus to have a single 40 Kd structural protein able to dissociate under the definite conditions forming the truncated (for 3 and 6 Kd) polypeptides having preserved their whole antigenic determinants. The human plasma is shown to contain antibodies reacting with the structural protein B-BX and, approximately 10 times weaker with the structural protein of another carlavirus, potato M-virus. Interaction of antibodies with CVB is found to take place due to F(ab)2 fragments. The analogous reaction with the proteins of other plant viruses or retroviruses has never been registered. Antibodies reacting with CVB protein are also present in the plasma of green monkey, rabbit, mouse and goat but in lesser quantities than in human plasma. Two possible explanations are proposed for the presented data, either immunization of mammalians by the protein or peptide containing its antigenic determinant, or the accidental coincidence of CVB antigenic determinant with some viral, bacterial or fungal determinant widespread in mammalians.

[Advantages and disadvantages of silver staining of proteins in polyacrylamide gel]

Sensitivity of protein staining with Serva blue G-250 (Coomassie brilliant blue G-250 analogue) in polyacrylamide gel was determined. It has been shown that protein staining with 0.1% Serva blue G-250 results in the recovery of 80 to 35 ng of single protein, that is almost 10 times higher than reported previously for Coomassie brill. blue G-250 (or R-250) staining. The comparison of the sensitivity of Serva blue G-250 protein staining in PAAG and AgNO3 has shown that AgNO3 staining was approximately 18-30 (but not 100 times, as it had been thought before) times more effective for the majority of proteins under study. Silver staining of some proteins, for instance ribonuclease and a number of retrovirus-specific structural proteins, was of lower efficacy. Thus, to obtain reliable results protein electrophoresis in PAAG should be followed by both staining procedures.

[Nonstructural glycosylated polyproteins coded for by the gag gene of retrovirus type D expressed on the plasma membrane]

Studies of virus-specific proteins of type D retroviruses by radioimmunoprecipitation (RIP) using various radioactive precursors demonstrated in HEp-2 cells producing these retroviruses the presence of two glycosylated gag-coded polyproteins with molecular weights of 78 K and 90 K. The same polyproteins were found by lactoperoxidase iodination and RIP on the plasma membrane of the cells. Comparative studies of these glycoproteins by the limited proteolysis method showed the sites for trypsin action in them to be located in similar places of protein bases which indicated their structural relationship. It is suggested that glycosylated gag-coded polyproteins of retroviruses (including type D retroviruses) play the role of receptors for certain mitogens the seizure of which stimulates cell proliferation.

[Electrical properties of the horny layer of human epidermis and its water transport]

Experimental evidence was obtained concerning the connection between the electric parameters of epidermis horny layer of the man's skin and water transport in the course of imperceptible perspiration. Two-layer diffusion model of water transport was considered.

[Dynamics of relaxation of the triboelectric charge on the surface of the horny layer of the epidermis]

Some results are presented of relaxation process of the triboelectric charge placed on the outer surface of human epidermis ("stratum cornium"). In measurements the characteristic time of the relaxation process was equal to tau approximately 10 divided by 10(3) sec. The measured values of tau and capacity of the high-resistivity stratum of epidermis (C approximately 10(+4) pF/sm2) lead to resistivity of "stratum cornium" R approximately 10(9) divided by 10(11) omega X sm2.

[High-resolution electrophoresis in a new polyacrylamide-gel block]

A new gel block for electrophoretic separation is offered. When viewed frontally, the block has a form of a trapezium. During electrophoresis a gradient of voltage is formed in such a block, as a result of which the mobility of macromolecules to be separated markedly decreases. The combination of the block with polyacrylamide gel gradient makes it possible to raise the resolving power of electrophoresis up to 300-400 dalton. The new gel block can be applied successfully to the performance of fine biochemical assays and molecular-biological studies of proteins, glycoproteins and nucleic acids.

[Processing of proteins coded by the gag gene of retrovirus type D from HEp-2 cells]

The early products of translation of the gag gene of retrovirus type D from HEP-2 cells were studied. The radioimmunoprecipitation test in the pulse-chase modification showed the proteins, products of the gag gene translation of this retrovirus, to be formed from polyprotein with a molecular weight of 78000. The use of serine proteinases inhibitors revealed 2 additional polyproteins with molecular weights of 37000 and 33000. The authors suggest a probable scheme of Pr78 processing which includes an initial cleavage of this polyprotein in two parts (37000 and 33000, respectively) followed by formation of viral structural proteins from these parts upon further cleavage.