Adhesive properties of connexin hemichannels.

Gap junctions are intercellular channels formed by hemichannels (or connexons) from two neighboring cells. Hemichannels, which are composed of proteins called connexins, can function as conduits of ATP and glutamate, and interact with adhesion molecules and other signaling elements. As a result, their functional repertoire is expanding into other roles, such as control of cell growth or cell migration. Here we further elucidate the involvement of hemichannels in cell-cell adhesion by analyzing how connexins regulate cell adhesion without the need of gap junction formation. Using a short-term aggregation assay with C6-glioma and HeLa cells stably transfected with connexin (Cx) 43 or Cx32, we found that the connexin type dictates the ability of these cells to aggregate, even though these two cell types do not usually adhere to each other. We have also found that high expression of Cx43, but not Cx32 hemichannels, can drive adhesion of cells expressing low levels of Cx43. Aggregation was not dependent on high levels of extracellular Ca(2+), as Ca(2+) removal did not change the aggregation of Cx43-expressing cells. Our data confirm that connexin hemichannels can establish adhesive interactions without the need for functional gap junctions, and support the concept that connexins act as adhesion molecules independently of channel formation.

Gap-junction-mediated propagation and amplification of cell injury.

Gap junctions are conductive channels that connect the interiors of coupled cells. We determined whether gap junctions propagate transcellular signals during metabolic stress and whether such signaling exacerbates cell injury. Although overexpression of the human proto-oncogene bcl2 in C6 glioma cells normally increased their resistance to injury, the relative resistance of bcl2+ cells to calcium overload, oxidative stress and metabolic inhibition was compromised when they formed gap junctions with more vulnerable cells. The likelihood of death was in direct proportion to the number and density of gap junctions with their less resistant neighbors. Thus, dying glia killed neighboring cells that would otherwise have escaped injury. This process of glial 'fratricide' may provide a basis for the secondary propagation of brain injury in cerebral ischemia.

ATP-mediated glia signaling.

Glia calcium signaling has recently been identified as a potent modulator of synaptic transmission. We show here that the spatial expansion of calcium waves is mediated by ATP and subsequent activation of purinergic receptors. Ectopic expression of gap junction proteins, connexins (Cxs), leads to an increase in both ATP release and the radius of calcium wave propagation. Cx expression was also associated with a phenotypic transformation, and cortical neurons extended longer neurites when co-cultured with Cx-expressing than with Cx-deficient cells. Purinergic receptor activation mediated both these effects, because treatment with receptor antagonists restored the glia phenotype and slowed neurite outgrowth. These results identify a key role of ATP in both short-term calcium signaling events and in long-term differentiation regulated by glia.

Comparative analysis of serological markers of chronic delta infection: HDV-RNA, serum HDAg and anti-HD IgM.

To study the concordance, sensitivity and specificity of HDV-RNA determination by molecular hybridization, serum HDAg by immunoblot and anti-HD IgM by commercial enzyme immunoassay as compared to intrahepatic HDAg detection by an immunoperoxidase method, a statistical analysis was applied to the results of serum sample and liver biopsy determinations in 50 patients with chronic delta hepatitis (38 positive to tissue HDAg and 12 negative). Of the 38 patients with hepatic HDAg, HDV-RNA was found in 31 (82%), serum HDAg by immunoblot in 27 (71%) and anti-HD IgM in 33 (87%). Among the 12 patients without hepatic HDAg, one was found with serum HDAg using the immunoblot technique, two (17%) had HDV-RNA, and 7 (58%) had anti-HD IgM. Serum HDAg determination by immunoblot was the most specific test, followed by HDV-RNA analysis. The least specific was the anti-HD IgM technique. The anti-HD IgM test was the most sensitive, followed by HDV-RNA and serum HDAg. The concordance with intrahepatic HDAg detection was highest for HDV-RNA determination, followed by HDAg in serum. The least degree of concordance was found with anti-HD IgM determination. These results suggest that the determination of HDV-RNA by the hybridization method can be of great value for the diagnosis and monitoring of chronic delta hepatitis.

Hepatitis E virus infection in acute hepatitis in Spain.

In order to study the prevalence of hepatitis E virus (HEV) infection in developed countries, IgG and IgM anti-HEV were determined in serum samples from 382 patients with acute viral hepatitis (244 hepatitis A, 48 hepatitis B and/or D, and 90 non-A, non-B, non-C hepatitis), 76 healthy subjects, 55 hemophiliacs and 50 patients on hemodialysis. IgG anti-HEV antibodies were detected and confirmed by a synthetic peptide-based EIA in 5 (5.6%) non-A, non-B, non-C acute hepatitis, in 3 (6.5%) B and D acute hepatitis, in 10 (4%) acute A hepatitis, in 3 (5.5%) of 54 healthy adults in none of the hemophiliacs and in 3 (6%) patients on hemodialysis. IgM anti-HEV antibodies were only detected in two cases of acute hepatitis B and/or D. Analysis of serial serum samples demonstrated IgG anti-HEV seroconversion in 3 of the 18 confirmed cases; one of them was also positive for IgM anti-HEV. All 3 acute anti-HEV-positive hepatitis cases occurred in adults, were community-acquired (two of them were intravenous drug addicts) and had a self-limited course. These results demonstrate that HEV is a minor cause of acute hepatitis in Spain. A similar low rate of IgG anti-HEV antibodies was detected in patients with different diseases, suggesting that HEV has a very low epidemiological impact. An apparent association of HEV infection with hepatitis B and D suggests a possible parenteral transmission of a mainly enteral pathogen.

Rapid detection of lamivudine-resistant hepatitis B virus polymerase gene variants.

The amino acid substitution from methionine to valine or isoleucine at the YMDD (tyrosine, methionine, aspartate, aspartate) motif of the HBV polymerase gene is the main mutation responsible for resistance to lamivudine treatment. Detection of emerging HBV variants by direct sequencing of the HBV genome is excessively time-consuming for studying large numbers of clinical samples. The aim of the study was to analyse the emergence of lamivudine-resistant HBV genotypes by means of restriction fragment length polymorphism (RFLP) of the PCR product generated from a fragment of domain C of the polymerase gene, in clinical samples from patients receiving treatment. The results with this method were compared with those obtained with a direct sequencing technique. In total, 139 serum samples were studied from 37 patients with chronic hepatitis B, obtained at pre-treatment and at 9, 12, 18 and 24 months of treatment. Variants were detected by cleavage of the products of the three PCRs with the following enzymes: FokI (identifies the normal variant, YMDD, and the mutant variant YVDD), SspI (identifies the mutant variant, YIDD) and Alw44I (identifies the variant, YVDD). The digested fragments were separated by electrophoresis in 3% agarose gel. Of the 139 serum samples analysed, the wild-type YMDD sequence was detected in 106 (76%), the YVDD variant in 20 (15%) and the YIDD variant in 13 (9%) cases. The non-mutated variant, YMDD, was detected in all the pre-treatment samples. After 9 months of treatment the mutant variant was detected in four of 37 serum samples analysed (11%) (two YVDD and two YIDD). At 12 months, 12 of the 37 serum samples (32%) showed mutations in the YMDD sequence (seven YVDD and five YIDD). Among the 16 serum samples obtained at 18 months, nine had the YMDD variant (56%) (seven YVDD and two YIDD). At 24 months, variants in the YMDD sequence were detected in eight of the 12 patients treated (66%) (four YVDD and four YIDD). HBV genotypes were confirmed by direct sequencing, with consistent results. In 45% of cases, the emergence of HBV variants was not associated with ALT breakthrough. The PCR-RFLP assay used in this study, in perfect concordance with direct sequencing, is an accurate method for genotyping lamivudine-resistant HBV variants. Since it is a rapid low-cost technique, PCR- RFLP is suitable for large-scale screening of these polymorphisms in clinical samples.

Expression and function of astrocytic gap junctions in aging.

Astrocytic gap junctions have been implicated in a variety of signaling pathways essential to normal brain function. However, no information exists on the prevalence of gap junction channels and their function in the aging brain. Here we have compared the expression of the two most abundant astrocytic gap junction proteins in young and senescent brains and quantified the extent of functional gap junction coupling. The expression level of Cx43 peaked in 7-month-old mice. The relative numbers of Cx43 immunoreactive plaques were 596+/-61, 734+/-62, and 755+/-114 in 3-, 7-, and 21-month-old mice, whereas plaques size averaged 0.9+/-0.1 microm(2) (3 months), 1.3+/-0.1 microm(2) (7 months), and 0.7+/-0.1 microm(2) (21 months). The expression level of Cx30 was also highest in 7-month-old animals (315+/-49 plaques, size 0.8+/-0.07 microm(2) vs. 585+/-51 plaques, size 0.9+/-0.1 microm(2) in 3- and 7-month-old mice, respectively), but only 262+/-63 plaques (size 0.4+/-0.04 microm(2)) in 21-month-old mice. Western blot analysis revealed that the content of both Cx43 and Cx30 remained relatively constant at 3, 7, and 21 months. The fluorescence recovery of photobleach technique (FRAP) was used to evaluate coupling in freshly prepared hippocampal slices. Gap junction coupling did not change significantly as a function of aging, but a tendency towards reduced coupling was observed as the animals aged. Average fluorescence recovery after 2 min was 63+/-6% in younger animals, 59+/-5% in adult animals, and 54+/-4% in old brain. These observations indicate that although astrocytic gap junction proteins are maintained at high levels through the entire lifespan of mice, aging is associated with changes in the number and size of both Cx30 and Cx43 gap junction plaques.

[Evaluation of replacement therapy in emphysema caused by alpha 1-antitrypsin deficiency]. / Evaluación del tratamiento sustitutivo del enfisema por déficit de alfa-1-antitripsina.

Assessment of alpha 1-antitrypsin replacement therapy (AAT) for emphysema. Patient characteristics were analyzed along with the possible side effects of the treatment and its efficacy in maintaining appropriate AAT blood levels. Lung function changes were also studied. The treatment protocol began with 4 weekly intravenous doses of 60 mg/kg AAT (Prolastin) and continued with monthly doses of 240 mg/kg. AAT serum levels were measured before each dose. Every 6 months pulmonary function tests (spirometry, plethysmography and CO transfer) were performed. Thirteen patients (mean age 46 yr) have been studied since 1988. Mean initial FEV1 was 0.79 l. Over 250 doses have been infused with no significant side effects reported. AAT levels before treatment in 3 patients were lower than that considered protective (50 mg/dl). Function tests results indicated stabilization of spirometric values in most cases. Diagnosis of AAT deficiency is delayed considerably, meaning that significant functional deterioration takes place before replacement therapy begins. No side effects of treatment have been observed. Until an appropriate interval between doses has been established, each patient's AAT levels must be monitored.

[Prevalence and incidence of hepatitis A in patients with hepatitis B and C]. / Prevalencia e incidencia de la infección por el virus de la hepatitis A en pacientes con hepatitis crónica B y C.

BACKGROUND: Patients with chronic hepatitis are in risk to acquire a fulminant hepatitis associated with hepatitis A virus superinfection. PATIENTS AND METHODS: Antibodies against hepatitis A were study in serum from 353 patients with chronic hepatitis B or C. RESULTS: The prevalence of IgG-HAV antibodies was 81% in chronic hepatitis C patients, and 77% in chronic hepatitis B patients. The presence of anti-HAV antibodies was related to the patients' age. None case of acute hepatitis A in chronic hepatitis patients was detected. CONCLUSIONS: The prevalence of anti-HAV antibodies is high in patients with chronic viral hepatitis but the incidence of the disease is low. Hepatitis A vaccination should do with previously screening.

[Molecular characterization of two variants of alpha-1-antitrypsin deficiency: PI Mpalermo and PI Plovel]. / Caracterización molecular de dos variantes deficitarias de la alfa-1-antitripsina: PL Mpalermo y PL Plovel.

BACKGROUND: Alpha 1 antitrypsin (AAT) is a highly polymorphic protein, having more than 75 different variants. In this work two rare AAT deficient variants were characterized by DNA study. PATIENTS AND METHODS: Members of three generations of two separate families were studied. In family 1, the index case was affected with pulmonary emphysema and presented AAT deficiency (23 mg/dl). In family 2, the index case had a normal pulmonary function, an AAT serum level of 72 mg/dl and a phenotype heterozygous for an AAT variant migrating in the P variant region. The AAT variants were characterized by polymerase chain reaction amplification of the coding exons and direct sequencing of the amplification products. RESULTS: Direct DNA sequencing from a member of family 1 demonstrates that in the exon II of the normal M1 (Val213) allele there was a 3-bp deletion (TTC), corresponding to Phe51 or Phe52. This mutation is characteristic of the Pl Mpalermo variant. In our study, Pl Mpalermo was detected in six members of three generations of this same family. Sequencing of exon III in a member of family 2, identified in the common M1 (Val213) allele a single base substitution of GAT-GTT, with the resulting amino acid change Asp256 for Val256. This mutation characterizes the Pl Plovel allele. The Pl Plovel was also detected in nine members of five others independent families. All of them have AAT serum levels between 80 and 102 mg/dl. None of the studied subjects had clinical evidence of lung disease. CONCLUSIONS: The results of our study show the presence of the two AAT deficient variants in Spain and suggest that the Pl Plovel variant might be more common than expected.

Rapid method for the detection of anti-HCV antibodies in patients with chronic hepatitis C.

OBJECTIVE: to evaluate the usefulness of a simple, rapid, qualitative technique (MedMira Rapid Test) to detect antibodies against hepatitis C virus (HCV) and compare this approach with an immunometric technique in patients with chronic hepatitis C infected with different genotypes. METHODS: anti-HCV antibodies were determined with the MedMira rapid technique and an immunometric method in samples from 138 patients with chronic hepatitis C infected with different HCV genotypes, and in 50 samples from healthy individuals. RESULTS: the MedMira rapid technique detected anti-HCV antibodies in 135 (98%) of 138 serum samples from patients with chronic hepatitis C, whereas the immunometric method gave positive results in all 138 samples. Three of the 138 anti-HCV-positive samples identified with the immunometric method and confirmed by inmunoblotting were repeatedly negative with the MedMira rapid technique. Two of these samples were genotype 1 and the third was not genotyped. All samples from the control group were negative for anti-HCV antibodies by both methods. The sensitivity and specificity of the MedMira rapid technique relative to the immunometric technique were 98% and 100% respectively. CONCLUSION: the MedMira rapid technique is a quick, specific and sensitive method that is easy to use by nonspecialized personnel, and is a good alternative to other, slower methods for the diagnosis of chronic hepatitis C.

[Study of HLA-II antigens in chronic hepatitis C and B and in acute hepatitis B]. / Estudio de los antígenos HLA-II en las hepatitis crónicas C y B y en las hepatitis agudas B.

The aim of this study was to analyze the variability of the HLA-II system in a series of patients with chronic hepatitis B, chronic hepatitis C and acute hepatitis B to know whether there is any relationship between the polymorphism of the HLA system, the different types of hepatitis and the evolution of the infection. HLA-II antigens were determined by a PCR technique in serum samples of 24 controls, 22 cases of chronic hepatitis C, 38 cases of chronic hepatitis B and 11 with acute hepatitis B. The prevalence of the HLA-DR4 antigen was lower in the cases of chronic hepatitis B (10.5%) and C (13.6%) than in the controls (33.3%), particularly the DRB1*0401 allele (p = NS). The prevalence of HLA-DR6 was similar in chronic hepatitis B (42.1%) and acute hepatitis B (45.5%). Predominance of the DRB1*1301 and DRB1*1302 alleles were, however, observed in acute hepatitis B (36.4%) versus chronic hepatitis B (13%). These data suggest that immunologic factors such as HLA antigens may influence in the susceptibility to infection by HBV and HCV. The use of PCR techniques which discriminate between the different alleles of the HLA antigens may provide better knowledge of the immune response.

[One year treatment with lamivudine in different hepatitis B virus related hepatic diseases]. / Tratamiento con lamivudina durante un año en distintas formas de afectación hepática por el virus de la hepatitis B.

BACKGROUND: Three month administration of lamivudine in patients with chronic hepatitis B produces a transitory inhibition of the DNA of the hepatitis B virus (HBV). AIM: The aim of this study was to evaluate the efficacy and safety of one year treatment with lamivudine in patients with chronic hepatitis B and liver transplantation (LTx) with recurrence of HBV infection. PATIENTS AND METHODS: Sixteen patients with chronic hepatitis B, 4 patients with decompensated hepatic cirrhosis and 4 patients having undergone LTx with recurrence of HVB infection were treated with the oral administration of 100 mg/day of lamivudine for one year. RESULTS: At 3 months of treatment, the HBV-DNA became negative in 94% of the cases of chronic hepatitis B, in 10% of those with decompensated hepatic cirrhosis and in 100% of the cases of LTx. At one year of treatment, the HBV-DNA was negative in 81% of the chronic hepatitis B, in 100% of the decompensated cirrhotics and in 100% of the LTX cases which survived. The tolerance to treatment was excellent in all the cases. In 34% of the cases, mutations were observed in the gene of the polymerase DNA at one year of treatment. CONCLUSIONS: Lamivudine produces intense, rapid inhibition in viral replication not only in chronic hepatitis B but also in cases of decompensated cirrhosis or recurrence following liver transplantation. Around 30% of the patients undergoing one year of treatment with lamivudine developed gene mutations of the HBV polymerase.

[Seroepidemiology of hepatitis A virus infection in medical and nursing students. The role of vaccination]. / Seroepidemiología de la infección por el virus de la hepatitis A en estudiantes de medicina y enfermería. Papel de la vacunación.

BACKGROUND: Recent seroepidemiologic studies have demonstrated a decrease in the prevalence of hepatitis A virus infection (HAV) in relation with an improvement in hygienic conditions. The prevalence of anti-HAV in a group of health care students was studied and a vaccination program initiated in this collective. METHODS: Serum anti-HAV determination was performed by an enzymoimmunoanalysis method. A inactivated hepatitis A vaccine was administered. RESULTS: Only 18.5% of the subjects between 17-23 years-old presented anti-HAV antibodies. The prevalence of anti-HAV was related with age and the number of partners. All of the 129 immunized individuals responded to the HAV vaccine with protector antibody titles. CONCLUSION: The present study demonstrates the decrease in HAV infection among youths as well as the immunogenicity of the anti-hepatitis A vaccine.

[Study of hepatitis B virus replication and infection by other hepatitis viruses in patients with chronic hepatitis B virus infection]. / Estudio de la replicación del virus de la hepatitis B e infección por otros virus hepatotropos en pacientes con infección crónica por el virus B.

AIM: To study hepatitis B virus (HBV) replication in a series of patients with HBV infection and to analyze the frequency of associated hepatitis C virus (HCV) and hepatitis D (HDV) infection. PATIENTS AND METHOD: Serological markers of HBV, HCV and HDV, transaminase values and HBV DNA were studied in serum samples from 463 patients with chronic HBV infection. RESULTS: Three hundred ninety-six (85.5%) were classified as hepatitis B, 33 (7.1%) as hepatitis B and C, 17 (3.6%) as hepatitis B and D and 17 (3.6%) as hepatitis B, C and D. Sixty-seven percent of patients with hepatitis B and 33% of those with chronic hepatitis B were asymptomatic HBsAg carriers. HVB DNA was identified in 27.7% of patients with hepatitis B, in 24% of those with hepatitis B and C, in 11.7% of those with hepatitis B and D and in 29.4% of those with hepatitis B, C and D. HBV DNA and elevated transaminase levels were found in 63% of HBeAg-positive patients and in only 16% of those who were anti-HBe-positive. These latter were considered candidates for antiviral treatment. CONCLUSIONS: In our environment, most patients with HBV infection are asymptomatic HBsAg carriers. Viral replication and elevated alanine aminotransferase levels were found in 22% of the patients. Consequently, these patients are candidates for antiviral treatment. Between 3.6% and 7.1% of patients with hepatitis B presented coinfection with HCV or HDV, or both. No significant differences were found in HBV replication among the different groups.

[Quantitative determination of HBV-DNA in chronic hepatitis B: comparison of three methods]. / Determinación cuantitativa de ADN-VHB en la hepatitis crónica B: comparación de tres métodos.

The aim of this study was to evaluate a technique of quantitative determination of DNA-HBV in serum, bDNA Quantiplex, in a series of 90 patients with chronic HBV infection: 75 with chronic hepatitis B (24 HBeAg positive and 51 with anti-HBe) and 15 asymptomatic carriers of HBV (anti-HBe positive). The results were related to DNA-HBV determination by hydridation techniques in dot-blot and PCR. DNA-HBV was detected by the Quantiplex bDNA technique in 61 (81%) of the 75 patients with chronic hepatitis B, in 24 (100%) of the 24 HBeAg positive patients and in 37 (72%) of the 51 anti-HBe positive (p < 0.05) patients and in none of the asymptomatic HBV carriers. The median of DNA-HBV concentration was 4,000 pg/ml in the hepatitis HBeAg and 71 pg/ml in the ati-HBe positive (p < 0.05). A significant relation was observed between the ALT value and the DNA-HBV concentration (p < 0.05). DNA-HBV by dot-blot was positive in 22 (29%) of the chronic hepatitis B and in none of the asymptomatic HBV carriers. DNA-HBV was not observed by dot-blot in 39 patients positive for DNA-HBV by the Quantiplex bDNA technique. DNA-HBV by PCR was identified in 65 (87%) of the chronic hepatitis B and in one of the asymptomatic HBV carriers. The sensitivity of the Quantiplex bDNA technique (98% versus the PCR technique) is much greater than that observed with dot-blot. In conclusion, the determination of DNA-HBV by the Quantiplex bDNA technique may be considered a good method for evaluating the viremia and degree of viral replication in patients with chronic hepatitis B.

[Assessment of the PCR-Southern blot technique for the analysis of viremia in patients with acute hepatitis A]. / Valoración de la técnica de PCR-Southern blot para el análisis de la viremia en pacientes con hepatitis aguda A.

Assessment of viremia in hepatitis A virus (HAV) infection is not frequently performed with conventional methods because the techniques used are laborious, have low sensitivity are usually performed in feces. The aims of this study were to develop a polymerase chain reaction (PCR) and Southern blot technique to detect HAV-RNA in the serum of patients with acute HAV infection and to determine the relationship between HAV-RNA and anti-HAV IgM and alanine aminotransferase (ALT) levels. The presence of HAV-RNA was studied in 26 serum samples from 21 patients with acute hepatitis A. We also studied 11 samples from patients with acute hepatitis B and 15 samples from patients with non-A, non-E hepatitis. HAV-RNA was detected in 10 (38%) of the 26 serum samples from patients with acute hepatitis A. Simple PCR was positive in 5 samples and PRC-Southern blot was positive in 10. All the serum samples obtained during the first week of onset were HAV-RNA positive and 50% of those obtained during the second week were positive. None of the serum samples obtained after the second week of onset were HAV-RNA positive. None of the serum samples from the 11 patients with acute hepatitis B or from the 15 patients with non-A, non-E acute hepatitis were positive for HAV-RNA. No significant relationship was detected between HAV-RNA detection and an IgM anti-HAV or ALT positive result. In conclusion, the presence of HAV-RNA in acute hepatitis A is frequent but the PCR Southern blot technique is required for detection, which is transitory during the first weeks after onset.

Cytoskeletal assembly and ATP release regulate astrocytic calcium signaling.

We have studied the role of actin fiber assembly on calcium signaling in astrocytes. We found that (1) after astrocytes have been placed in culture, it takes several hours for organization of the definitive actin cytoskeleton. Actin organization and the number of cells engaged in calcium signaling increased in parallel. (2) Disruption of the actin cytoskeleton attenuated the calcium wave propagation; cytochalasin D treatment reduced the number of astrocytes engaged in calcium signaling. (3) Propagation of calcium waves depends on cytoskeletal function; inhibition of myosin light chain kinase suppressed wave activity. (4) Astrocytic calcium signaling is mediated by release of ATP and purinergic receptor stimulation, because agents that interfere with this cascade attenuated or reduced calcium signaling. Because purinergic receptors are fully functional shortly after plating and not affected by cytochalasin D, these observations indicate that cytoskeleton organization is a prerequisite for interastrocytic calcium signaling mediated by release of ATP.

Programmed cell death in the developing somites is promoted by nerve growth factor via its p75(NTR) receptor.

Neurotrophins control neuron number during development by promoting the generation and survival of neurons and by regulating programmed neuronal death. In the latter case, the cell death induced by nerve growth factor (NGF) in the developing chick retina is mediated by p75(NTR), the common neurotrophin receptor (J. M. Frade, A. Rodriguez-Tebar, and Y.-A. Barde, 1996, Nature 383, 166-168). Here we show that NGF also induces the programmed death of paraxial mesoderm cells in the developing somites. Both NGF and p75(NTR) are expressed in the somites of chick embryos at the time and the place of programmed cell death. Moreover, neutralizing the activity of endogenous NGF with a specific blocking antibody, or antagonizing NGF binding to p75(NTR) by the application of human NT-4/5, reduces the levels of apoptotic cell death in both the sclerotome and the dermamyotome by about 50 and 70%, respectively. Previous data have shown that Sonic hedgehog is necessary for the survival of differentiated somite cells. Consistent with this, Sonic hedgehog induces a decrease of NGF mRNA in somite explant cultures, thus showing the antagonistic effect of NGF and Sonic hedgehog with respect to somite cell survival. The regulation of programmed cell death by NGF/p75(NTR) in a mesoderm-derived tissue demonstrates the capacity of neurotrophins and their receptors to influence critical developmental processes both within and outside of the nervous system.

HEV identified in serum from humans with acute hepatitis and in sewage of animal origin in Spain.

BACKGROUND/AIMS: Hepatitis E virus (HEV) is an enterically transmitted pathogen that appears sporadically in non-endemic countries. We studied HEV as a causal agent of acute hepatitis cases in the Spanish population, and the role of pigs as an animal reservoir. METHODS: The presence of HEV-RNA was analysed by nested polymerase chain reaction in 37 serum samples from patients with acute viral hepatitis, 48 porcine serum samples, 6 pig faecal samples and 12 slaughter-house sewage samples. Presence of antibodies was also tested in porcine sera. RESULTS: HEV-RNA was found in 3 human serum samples from patients presenting IgG anti-HEV antibodies. Nucleotide sequence analysis identified 2 strains with 93.4% identity, phylogenetically most closely related to the Greece1 isolate, and more closely related to North American and other European strains than to those from endemic regions. HEV-RNA was also detected in slaughterhouse sewage mainly from pigs, presenting 92-94% nucleotide similarity compared to the strains detected in the human sera. Twenty-five per cent of the pigs tested presented IgG anti-HEV antibodies. CONCLUSIONS: These data suggest that the HEV could be more widespread than previously thought, and present new evidence of the close relationship between HEV strains detected in pigs and those from acute hepatitis patients.