Terminal differentiation of human keratinocytes and stratum corneum formation is associated with caspase-14 activation

Programmed cell death of epidermal keratinocytes (KC) results in the formation of cornified cells, which constitute the outermost skin layer, the stratum corneum. Here we show by reverse transcription-polymerase chain reaction, western blot, and immunohistochemistry that epidermal KC express caspase-14, a member of the caspase family of pro-apoptotic proteases, in a tissue-specific manner. Caspase-14 protein abundance strongly increases during terminal differentiation of KC in vivo and in vitro. Under conditions that lead to stratum corneum formation caspase-14 cleavage products, which indicate proenzyme activation, appeared in the KC lysates. Cleavage of the enzyme was also detected in lysates from normal human epidermis and in extracts of stratum corneum. Our findings demonstrate that caspase-14 is activated during KC differentiation and strongly suggest that it is involved in the formation of the human skin barrier.J Invest Dermatol 115:1148-1151 2000

Melanin binds reversibly to thermostable DNA polymerase and inhibits its activity

We found that both RNA and cDNA preparations derived from melanocytes contain a RT-PCR inhibitor that copurified with nucleic acids. Investigation of the candidate inhibitor melanin revealed that it potently blocks PCR at concentrations below 200 ng/ml, whereas 100 microg/ml melanin was required to inhibit reverse transcription. Melanin and thermostable DNA polymerase preferentially formed a distinct complex with reduced migration velocity as compared to pure polymerase in nondenaturating polyacrylamide gel electrophoresis. The inhibition of the enzyme by melanin could be reversed by diluting solutions of preformed complexes or by adding excess amounts of other proteins such as bovine serum albumin or dry milk. Our findings demonstrate that melanin is a potent inhibitor of thermostable DNA polymerase in vitro and that the inhibitory effect is conferred by a direct and reversible polymerase-melanin interaction.

Fibrinolysis associated with human neoplasia: production of plasminogen activator by human tumours

The plasminogen-dependent fibrinolytic activity of several human tumours has been studied. The following neoplastic tissues, which were obtained from cancer patients by either surgery or biopsies, were examined: cervical, mammary, prostatic, ovarian, lung carcinomas, melanoma, basalioma. Fibrinolysis was measured in lysates either of tumour tissue specimens or of respective cell cultures. This measurement was based on release of radioactivity from 125I-fibrin-coated Petri dishes. All examined tumours showed elevated levels of plasminogen-dependent fibrinolytic activity. However, normal control tissues had little or no activity. These results indicate that the fibrinolysis might be useful in differentiating between malignant and normal tissues.

Hsa-mir-145 is the top EWS-FLI1-repressed microRNA involved in a positive feedback loop in Ewing's sarcoma

EWS-FLI1 is a chromosome translocation-derived chimeric transcription factor that has a central and rate-limiting role in the pathogenesis of Ewing's sarcoma. Although the EWS-FLI1 transcriptomic signature has been extensively characterized on the mRNA level, information on its impact on non-coding RNA expression is lacking. We have performed a genome-wide analysis of microRNAs affected by RNAi-mediated silencing of EWS-FLI1 in Ewing's sarcoma cell lines, and differentially expressed between primary Ewing's sarcoma and mesenchymal progenitor cells. Here, we report on the identification of hsa-mir-145 as the top EWS-FLI1-repressed microRNA. Upon knockdown of EWS-FLI1, hsa-mir-145 expression dramatically increases in all Ewing's sarcoma cell lines tested. Vice versa, ectopic expression of the microRNA in Ewing's sarcoma cell lines strongly reduced EWS-FLI1 protein, whereas transfection of an anti-mir to hsa-mir-145 increased the EWS-FLI1 levels. Reporter gene assays revealed that this modulation of EWS-FLI1 protein was mediated by the microRNA targeting the FLI1 3'-untranslated region. Mutual regulations of EWS-FLI1 and hsa-mir-145 were mirrored by an inverse correlation between their expression levels in four of the Ewing's sarcoma cell lines tested. Consistent with the role of EWS-FLI1 in Ewing's sarcoma growth regulation, forced hsa-mir-145 expression halted Ewing's sarcoma cell line growth. These results identify feedback regulation between EWS-FLI1 and hsa-mir-145 as an important component of the EWS-FLI1-mediated Ewing's sarcomagenesis that may open a new avenue to future microRNA-mediated therapy of this devastating malignant disease.

Caspase-14: analysis of gene structure and mRNA expression during keratinocyte differentiation

Caspase-14 is expressed in a tissue-specific manner in mouse skin. Here we determined the complete caspase-14 cDNA sequence of human caspase-14 by rapid amplification of cDNA ends. Sequence comparison with a cosmid clone containing genomic DNA revealed that the human caspase-14 gene comprises seven exons. Facultative utilization of a cryptic splice acceptor site within intron 5 leads to the formation of two mRNA species. In situ hybridization of human skin showed that caspase-14 is expressed in the uppermost layer of living epidermal cells, i.e., the granular layer, in hair follicles and sebaceous glands. In vitro caspase-14 transcription was low in subconfluent cultures but strongly increased when keratinocyte differentiation was simulated by maintaining cells at confluence for several days. This transcriptional upregulation was suppressed in the presence of a high extracellular calcium concentration. Our findings show that caspase-14 is regulated at the level of transcription during keratinocyte differentiation in vitro and in vivo.

Antitumor activity of IL-32β through the activation of lymphocytes, and the inactivation of NF-κB and STAT3 signals

Cytokine and activation of lymphocytes are critical for tumor growth. We investigated whether interleukin (IL)-32β overexpression changes other cytokine levels and activates cytotoxic lymphocyte, and thus modify tumor growth. Herein, IL-32β inhibited B16 melanoma growth in IL-32β-overexpressing transgenic mice (IL-32β mice), and downregulated the expressions of anti-apoptotic proteins (bcl-2, IAP, and XIAP) and cell growth regulatory proteins (Ki-67 antigen (Ki-67) and proliferating cell nuclear antigen (PCNA)), but upregulated the expressions of pro-apoptotic proteins (bax, cleaved caspase-3, and cleaved caspase-9). IL-32β also inhibited colon and prostate tumor growth in athymic nude mice inoculated with IL-32β-transfected SW620 colon or PC3 prostate cancer cells. The forced expression of IL-32β also inhibited cell growth in cultured colon and prostate cancer cells, and these inhibitory effects were abolished by IL-32 small interfering RNA (siRNA). IL-10 levels were elevated, but IL-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) levels were reduced in the tumor tissues and spleens of IL-32β mice, and athymic nude mice. The number of cytotoxic T (CD8(+)) and natural killer (NK) cells in tumor tissues, spleen, and blood was significantly elevated in IL-32β mice and athymic nude mice inoculated with IL-32β-transfected cancer cells. Constituted activated NF-κB and STAT3 levels were reduced in the tumor tissues of IL-32β mice and athymic nude mice, as well as in IL-32β-transfected cultured cancer cells. These findings suggest that IL-32β inhibits tumor growth by increasing cytotoxic lymphocyte numbers, and by inactivating the NF-κB and STAT3 pathways through changing of cytokine levels in tumor tissues.

Isolation and characterization of a 2.3-kilobase-pair cDNA fragment encoding the binding domain of the bovine leukemia virus cell receptor

An immunoscreening strategy was used to isolate a cDNA clone encoding the binding domain for the external glycoprotein gp51 of the bovine leukemia virus (BLV). Three recombinant phages demonstrating BLV binding activity and containing 2.3-kbp cDNA inserts with identical nucleotide sequences were isolated from a lambda gt11 cDNA library of bovine kidney cells (MDBK). One clone, BLVRcp1, hybridized with a 4.8-kb mRNA from cells of bovine origin and was also found to be conserved as a single-copy gene in murine, bovine, ovine, primate, canine, feline, and porcine DNAs. The same gene is amplified in caprine DNA isolated from a BLV-induced tumor. The longest open reading frame of BLVRcp1 encodes a protein fragment of 729 amino acids with a putative receptor structure. BLVRcp1 cDNA was cloned in the eucaryotic expression vector pXT-1 and transfected into murine NIH 3T3 and human HEp-2 cells. Cells expressing BLVRcp1 mRNA became susceptible to BLV infection. BLVRcp1 has no known physiological function and has no significant homology with sequences registered in the GenBank and EMBL data libraries (31 July 1992). Expression of deleted constructs of BLVRcp1 indicates that the BLV binding region is encoded at the 5' side of the receptor clone.

Reverse transcription-polymerase chain reaction products of alternatively spliced mRNAs form DNA heteroduplexes and heteroduplex complexes

Reverse transcription-polymerase chain reaction (RT-PCR) is frequently used to simultaneously detect mRNA isoforms, which are generated by alternative splicing. Here we characterize two previously unrecognized RT-PCR products of vascular endothelial growth factor (VEGF) RNA. DNA products with apparent sizes of 600 and 1200 base pairs (bp) were detected at high cycle numbers. Heat denaturation of the smaller product and subsequent reannealing revealed that it was a heteroduplex consisting of two different DNA strands. These were identified by DNA sequencing as the amplification products of two VEGF transcripts, i.e. VEGF121 and VEGF165, which differ by the presence of one exon. S1 nuclease analysis showed that this exon is bulged out as a single-stranded loop. Purified heteroduplexes in solution were found to form a 1200-bp DNA product which could be reconverted into 600-bp DNA heteroduplexes by mild denaturation at 70 degreesC. These findings suggest that this product is formed by base pairing of complementary heteroduplex loops and represents a novel four-stranded DNA structure.

Acute effect of multiple ozone metrics on mortality by season in 34 Chinese counties in 2013-2015

BACKGROUND

Although numerous multicentre studies have estimated the association between ozone exposure and mortality, there are currently no nationally representative multicentre studies of the ozone-mortality relationship in China.

OBJECTIVE

To investigate the effect on total (nonaccidental) and cause-specific mortality of short-term exposure to ambient ozone, and examine different exposure metrics.

METHODS

The effects of short-term exposure to ozone were analysed using various metrics (daily 1-h maximum, daily 8-h maximum and daily average) on total (nonaccidental) and cause-specific (circulatory and respiratory) mortality from 2013 to 2015 in 34 counties in 10 cities across China. We used distributed lag nonlinear models for estimating county-specific relative risk of mortality and combined the county-specific relative rates by conducting a random-effects meta-analysis.

RESULTS

In all-year analyses, a 10 μg m^-3 increase in daily average, daily 1-h maximum and daily 8-h maximum ozone at lag02 corresponded to an increase of 0.6% (95% CI: 0.33, 0.88), 0.26% (95% CI: 0.12, 0.39) and 0.37% (95% CI: 0.2, 0.55) in total (nonaccidental) mortality, 0.66% (95% CI: 0.28, 1.04), 0.31% (95% CI: 0.11, 0.51) and 0.39% (95% CI: 0.16, 0.62) in circulatory mortality, and 0.57% (95% CI: -0.09, 1.23), 0.11% (95% CI: -0.22, 0.44) and 0.22% (95% CI: -0.28, 0.72) in respiratory mortality, respectively. These estimates had a different seasonal pattern by cause of death. In general, the seasonal patterns were consistent with the times of year when ozone concentrations are highest.

CONCLUSIONS

Our findings suggest that in China, the acute effects of ozone are more closely related to daily average exposure than any other metric.

Identification of a human cDNA encoding a novel Bcl-x isoform

Alternative splicing has been shown to generate two isoforms of the apoptosis regulator bcl-x, Bcl-xL and Bcl-xS, in humans. Here we describe the identification and characterization of a third splice variant of the human bcl-x gene. It differs from previously described bcl-x transcripts in two respects: (1) a novel facultative intron is spliced out at the 5' untranslated region and (2) the open reading frame arises from a continuous genomic sequence extending over the splice donor sites utilized by the bcl-xL and bcl-xS transcripts. Since the resulting molecule has an organisation homologous to mouse and rat Bcl-x beta we suggest calling this novel protein human Bcl-x beta. Northern blot analysis revealed that bcl-x beta mRNA is expressed in numerous cell lines. Like Bcl-xL, h-Bcl-x binds to the pro-apoptotic protein Bax, suggesting a functional activity in vivo.

Characterization of a cDNA clone, encoding a 70 kDa heat shock protein from the dermatophyte pathogen Trichophyton rubrum

Trichophyton rubrum is an anthropophilic fungus causing up to 90% of chronic cases of dermatophytosis. To characterize T. rubrum proteins at the molecular level, we established a cDNA library of this pathogen. Here we describe a recombinant cDNA clone identical to eukaryotic 70kDa heat-shock proteins (HSPs). Western blot analysis using an anti HSP70 monoclonal antibody detected a recombinant fusion protein in Escherichia coli transformed with the expression vector containing the cloned cDNA insert. Southern blot analysis of T. rubrum genomic DNA detected no other members of the HSP70 gene family. Further analysis revealed the presence of two introns within the ORF of the HSP70 gene. In Northern blot analysis, the cDNA clone was hybridized to a RNA species of about 3.5kb which was constitutively expressed by cells cultured at 27 degrees C and was strongly up-regulated after culture at 37 degrees C. In summary, we have cloned the first member of the HSP family of dermatophytes and characterized it as a member of the Dnak subfamily of 70kDa HSPs.

Alternative splicing of caspase-8 mRNA during differentiation of human leukocytes

Caspase-8 is a key initiator of death receptor-induced apoptosis. Here we provide evidence that caspase-8 expression is subject to posttranscriptional regulation in human leukocytes. Resting peripheral blood lymphocytes preferentially use a distant splice donor site at the 3'-end of caspase-8 exon 8 to generate mRNAs with a truncated open reading frame. When lymphocytes were activated, the expression of caspase-8 variants was shifted to caspase-8/a and b which lack the extension of exon 8. The opposite change of the splicing pattern was found in a neutrophil differentiation model. Promyelocytic HL-60 cells mainly expressed caspase-8 mRNAs with the normal exon 8, but the splicing pattern was changed to the distant exon 8 splice site during DMSO-induced differentiation of HL-60 cells. In spite of the presence of these novel mRNAs, the corresponding translation products were not detectable in either cell type. Our findings suggest that leukocyte differentiation and alternative splicing of caspase-8 pre-mRNA are inter-dependent processes.

DNA-to-protein cross-linking in synchronized HeLa cells exposed to ultra-violet light

The U.V.-induced DNA-to-protein cross-linking in synchronously growing HeLa cells exhibits age-dependent variations. The maximum yield of cross-linking is observed during S-phase and exposure of mid-S cells to 250 ergs/mm2 renders about 22 per cent of DNA unextractable owing to cross-linking with proteins. Cells irradiated in G1 or G2 exhibit much smaller amount of cross-linking. The unextracted DNA was recovered from the protein fraction, and the addition of 0-5 per cent trypsin solution rendered all the DNA extractable. Fluctuations in the age-response pattern for the yield of DNA-protein cross-links varies throughout the cell-cycle in the same way as the efficiency for cell-killing, i.e. cells are resistant in G1, sensitive as they move into and through the S phase, and resistant again in G2. Dose-response curves determined at different times in the cycle reveal that up to about 500 ergs/mm2 the amount of DNA recovered from S cells decreased for about 8 per cent for every 100 ergs/mm2 of U.V. light. The amount of recovered DNA remained unchanged for cells exposed to 500 ergs/mm2 in the middle of S, for as long as 8 hours after exposure, i.e. for as long as the experiments were carried out no recovery from this damage was observed.

A reliable method for monitoring the microvascular patency of free jejunal transfers in reconstructing the pharynx and cervical esophagus

Reconstruction of the pharynx and esophagus with revascularized segments of jejunum remains a time-proven entity. Most thromboses and subsequent flap failures have occurred within the first 24 hours after revascularization of the flap. What would therefore be desirable is a safe, proven monitoring system to assess the patency of the microvascular anastomoses and subsequent viability of the transferred bowel segment. This paper reports on such a monitoring system, which involves the creation of a surgical window on the anterior cervical flap. The jejunal serosa is tacked to this window, and a thin split-thickness skin graft is placed directly on the bowel. The technique is simple, safe, efficacious, and leaves no significant defect.

Induction of immune deficiency syndrome in rabbits by bovine leukaemia virus

Newborn rabbits were inoculated with bovine leukaemia virus (BLV). The majority of infected rabbits produced antiviral antibodies. All the seroconverted animals developed symptoms resembling AIDS and died several months after inoculation. The course of experimental infection of rabbits with BLV resembled in many respects the broad spectrum of clinical disorders associated with AIDS induced by HIV. Antibody response to virus proteins was followed by immune deficiency and signs of neuropathy, and the animals subsequently died of opportunistic infections. Virus transmission from infected babies to the mothers by contact was also observed. In some cases the virus was salvaged from lymphocytes of rabbits with the immune deficiency syndrome. The virus-specific sequences were found to be integrated at random in the DNA of haematopoietic cells and of some organs. Slight expression of viral RNAs in lymphocytes was found. Experimental infection of rabbits with BLV can be used in experiments to understand AIDS induction.

4-O-methylhonokiol, a PPARγ agonist, inhibits prostate tumour growth: p21-mediated suppression of NF-κB activity

BACKGROUND AND PURPOSE

The effects of 4-O-methylhonokiol (MH), a constituent of Magnolia officinalis, were investigated on human prostate cancer cells and its mechanism of action elucidated.

EXPERIMENTAL APPROACH

The anti-cancer effects of MH were examined in prostate cancer and normal cells. The effects were validated in vivo using a mouse xenograft model.

KEY RESULTS

MH increased the expression of PPARγ in prostate PC-3 and LNCap cells. The pull-down assay and molecular docking study indicated that MH directly binds to PPARγ. MH also increased transcriptional activity of PPARγ but decreased NF-κB activity. MH inhibited the growth of human prostate cancer cells, an effect attenuated by the PPARγ antagonist GW9662. MH induced apoptotic cell death and this was related to G(0) -G(1) phase cell cycle arrest. MH increased the expression of the cell cycle regulator p21, and apoptotic proteins, whereas it decreased phosphorylation of Rb and anti-apoptotic proteins. Transfection of PC3 cells with p21 siRNA or a p21 mutant plasmid on the cyclin D1/ cycline-dependent kinase 4 binding site abolished the effects of MH on cell growth, cell viability and related protein expression. In the animal studies, MH inhibited tumour growth, NF-κB activity and expression of anti-apoptotic proteins, whereas it increased the transcriptional activity and expression of PPARγ, and the expression of apoptotic proteins and p21 in tumour tissues.

CONCLUSIONS AND IMPLICATION

MH inhibits growth of human prostate cancer cells through activation of PPARγ, suppression of NF-κB and arrest of the cell cycle. Thus, MH might be a useful tool for treatment of prostate cancer.

Mapping of sequential epitopes recognized by monoclonal antibodies on the bovine leukaemia virus external glycoproteins expressed in Escherichia coli by means of antipeptide antibodies

A lambda gt11 cDNA library prepared from bovine leukaemia virus (BLV)-producing ovine cells was screened with a cocktail of anti-BLV gp51 monoclonal antibodies (MAbs). Four recombinant phages with inserts of about 2-5 kbp were isolated. One, lambda BLV-gp51-1, was sequenced and shown to encode the C-terminal part of gp51 and all of gp30. This insert was subcloned into pEV-vrf1 and expressed in Escherichia coli N-4830-1 cells. The BLV product and a series of antipeptide antibodies were used to localize the sequential epitopes defined on BLV envelope glycoprotein gp51 by their reactivity with MAbs. Epitope B was localized to amino acids 180 to 205, B' to residues 195 to 205, D and D' to residues 218 to 237, and A to amino acids 249 to 260. All the mapped sequential epitopes were localized in the C-terminal half of BLV gp51. The results of epitope mapping with bacterially produced gp51 confirm the map obtained using native viral glycoprotein.

Isolation of the missing 5'-end of the encoding region of the bovine leukemia virus cell receptor gene

The missing 5'-end of the encoding region of the bovine leukemia virus (BLV) cell receptor gene (BLVRcp1/5') was isolated from a lambda gt11 cDNA library using the 32P-labeled EcoRI-SamI fragment corresponding to the 5'-end of a 2.3 kbp cDNA fragment encoding the binding domain of the bovine leukemia virus cell receptor gene (BLVRcp1). The nucleotide and amino acid sequence analysis of the BLVRcp1/5' cDNA revealed that the 1058 bp EcoRI fragment at its 5'-end contained a new 114 amino acid long sequence, and at its 3'-end contained a completely identical 88 amino acid overlapping region with the 5'-end of the BLVRcp1 cDNA. The combined sequences of both cDNAs represent the whole encoding region of the BLV cell receptor gene. The longest open reading frame of the BLV cell receptor gene encodes a protein containing 843 amino acids with a calculated molecular mass of 94.2 kDa which concurs with experimentally detected native BLV receptor protein. Search for homology has shown that about 250 bp of the BLV cell receptor gene is highly homologous to Venter's tag sequences of an unidentified gene from the human brain library.

Activation of MAPK by potassium bisperoxo(1,10-phenanthroline)oxovanadate (V)

Potassium bisperoxo(1,10-phenantroline)oxovanadate (V) [bpV(phen)] is a potent protein tyrocine phosphatase inhibitor which mediates a variety of biological effects. The aim of these studies was to examine the role(s) of mitogen activated protein kinase (MAPK) pathways in PC12 cell proliferation and toxicity by bpV(phen). BpV(phen) exerts a bimodal effect in PC12 cells: proliferation at low and cell death at higher micromolar concentrations. Activation of MAPK by bpV(phen) depends on time and concentration. The phosphorylation pattern of extracellular regulated kinases (ERK 1/2), c-jun N-terminal activated kinases (JNK) and p38 in PC12 cells is strikingly different. Activation of JNK is sustained in PC12 cells. In contrast, ERK 1/2 activation is transient and treatment with PD98059 indicates that ERK activation by bpV(phen) is partly independent from the ras-MEK pathway. Stability studies of bpV(phen) in DMEM and PBS showed linear relationship with T1/2 about 6 h and 10 days in DMEM and PBS, respectively. Comparison between the time courses of MAPK activation and kinetics of bpV(phen) decomposition as assessed by 51V-NMR analysis show that the initial and maximal phosphorylation signals are produced in the presence of the complex bpV(phen) and not caused by the decomposition products of bpV(phen).

Keratinocytes express the CD146 (Muc18/S-endo) antigen in tissue culture and during inflammatory skin diseases

The CD146 (or MUC18/MEL-CAM) antigen is a cell adhesion molecule of the immunoglobulin superfamily. Besides in melanoma, expression of CD146 antigen has been demonstrated in breast epithelia and hair follicles. We studied its expression by human keratinocytes in culture as well as in neoplastic and inflammatory skin diseases. Staining of primary cultured keratinocytes revealed expression of CD146 on the cell membrane, preferentially on cell-cell contact sites. Western blot analysis of keratinocytes detected a band of approximately 113 kDa, corresponding to the CD146 protein. In contrast to primary keratinocytes, neither CD146 protein nor mRNA expression was found in the keratinocyte-derived cell lines A431 and HaCaT. Treatment of keratinocytes with the proinflammatory cytokines interleukin-1 and interleukin-6, tumor necrosis factor-alpha, and interferon-gamma, resulted in no change of CD146 expression and incubation with phorbol 12-myristate 13-acetate led to a reduction of CD146 on keratinocytes. By contrast, when culturing keratinocytes in medium devoid of growth supplements, a distinct upregulation was observed as compared with culture in fully supplemented medium. In normal human epidermis expression of the CD146 antigen was not detectable. It was strongly upregulated, however, on suprabasal keratinocytes in psoriasis, in lichen planus, in the epidermis overlying skin neoplasms, and in viral warts. In squamous cell carcinomas and basal cell carcinomas only a minority of tumor cells expressed CD146. Our findings suggest that the CD146 antigen represents an activation marker of keratinocytes and may be involved in cutaneous inflammatory tissue reaction.

Protective vaccination against bovine leukaemia virus infection by means of cell-derived vaccine

Tests were performed to determine whether live mammalian cells producing env gene glycoproteins and main structural protein p24 of bovine leukaemia virus (BLV), heterologous to bovine species, could serve as an immunogen in cattle to prevent induction of bovine leukaemia. Ovine virus-non-producing clonal cells NP-2 were used as the immunogen. The NP-2 cells synthesized only the env gene products--glycoprotein gp51 and gp30 and main structural protein p24 of BLV. The NP-2 cells, inoculated into rats, induced an antibody response directed against envelope glycoproteins of BLV. The antibodies neutralized the infectivity of BLV as determined by the VSV/BLV pseudotype neutralization test. Similar results were obtained by vaccination of cattle with these cells. A dose of less than or equal to 2 x 10(6) live cells inoculated subcutaneously induced an antibody response in cattle, while a high dose of killed cells was ineffective. The antibodies in cattle were directed against env products of BLV. A group of 92 cows was vaccinated and followed up for 4 years. The antibody levels fluctuated slightly during the 4-year observation period, generally decreasing with time, but revaccination always increased the antibody titre. No transfer of seropositivity was observed to seronegative animals which were kept in contact with vaccinated ones. In a separate experiment a group of young heifers, after repeated vaccination, were challenged with a high dose of infectious virus and/or virus-producing cells. The response to BLV infection was followed by syncytial induction assay after co-cultivation of white blood cells with indicator cells CC81.(ABSTRACT TRUNCATED AT 250 WORDS)

The cell death regulatory protein bak is expressed in endothelial cells in inflamed tissues and Is induced by IFN-gamma in vitro

In the present report, we examined the endothelial expression of the anti- and pro-apoptotic proteins Bcl-2 and Bak in situ and in vitro. Endothelial cells (EC) in regular tissue of the bowel and the skin were essentially negative for both Bcl-2 and Bak. In contrast, EC within the walls of fistulas and abscesses in these organs stained distinctly for Bak, but remained Bcl-2-negative. In tissue culture both unstimulated human dermal microvascular endothelial cells (HDMEC) and human umbilical vein endothelial cells (HUVEC) expressed Bcl-2 and Bak constitutively. Exposure of EC to 200-1000 IU IFN-gamma downregulated Bcl-2 but upregulated Bak. This opposing regulation of Bcl-2 and Bak in vitro and the expression of Bak in EC adjacent to necrotic tissue areas suggests that this pro-apoptotic protein may play a decisive role in regulation of EC survival in vivo.