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Biomedical subjects

H Will

Publications and source records attributed to H Will.

246 records · Page 14Linked to original sources
PubMedDate not supplied

Expression of hepatitis B virus antigens in attenuated Salmonellae for oral immunization.

The aim of our work is to identify hepatitis B virus antigens that can be stably expressed in attenuated Salmonellae and elicit protective immune responses as live oral route vaccines. As a first carrier system, we expressed T-cell and B-cell epitopes of hepatitis B virus as fusion proteins with the non-toxic subunit B (LT-B) in attenuated Salmonellae. These recombinant Salmonellae elicited anti-LT-B T- and B-cell immune responses and anti-HBV nucleocapsid antigen (HBcAg) T-cell responses when fed to mice. To combine the protective potential and the high immunogenicity of HBc with the induction of virus neutralizing antibodies to HBV surface antigen, we constructed vectors expressing hybrid HBc/pre-S particles in which the pre-S epitopes were surface-exposed. With one of these vectors, stable constitutive high level expression of hybrid HBc/pre-S2 particles was achieved in several attenuated Salmonella strains. When recombinant Salmonellae expressing such hybrid HBc/pre-S2 fusion proteins were fed to mice, the animals developed high titres of anti-HBcAg-specific serum IgG after a single or multiple oral immunizations, depending on the strain used as a carrier. In addition, lower titered antibodies against the pre-S2 antibody-binding sites were elicited. This is the first HBV antigen eliciting high-titered immune responses after a single oral immunization in recombinant Salmonellae. The immunogenicity of periplasmic LT-B and cytoplasmic HBc/pre-S2 shows that surface exposure of a foreign antigen is not a prerequisite for its immunogenicity in live attenuated Salmonellae.

Administration, Oral↗
PubMedDate not supplied

Signals regulating hepatitis B surface antigen transcription.

About 200 million people are chronic carriers of hepatitis B surface antigen (HBsAg), but since hepatitis B virus (HBV) cannot be propagated in vitro, HBsAg transcription has been studied only in cell lines containing HBV DNA integrated into chromosomes, and HBsAg-related mRNAs 2.0 to 2.5 kilobases (kb) long have been described. We have analysed the transcripts produced in an infected chimpanzee liver and in a rat cell line containing HBV DNA. In contrast to previous suppositions we report here that the major S gene transcript initiates close to the S gene, that is, within the 'pre-S' region and is processed/polyadenylated at a site situated within the core gene. The efficiency of processing/polyadenylation at this site varies between the chimpanzee liver and the rat cell line studied. The S gene promoter does not contain a TATA box but instead has a sequence homologous to that which positions the 5' ends of the major simian virus 40 (SV40) late transcript.

Animals↗
PubMedDate not supplied

Liver graft infection by HBV S-gene mutants in transplant patients receiving long-term HBIg prophylaxis.

BACKGROUND/AIMS: HBV reinfection of transplant livers occurs frequently even in the presence of high doses of anti-HBs immunoglobulins. We analyzed, retrospectively, whether and which type of S-gene variants were selected by long-term polyclonal anti-HBs (HBIg) treatment leading to reinfection of patients transplanted because of chronic HBs-positive end-stage liver disease. METHODOLOGY: The preS2/S gene of the viral genomes obtained from sera before transplantation and during HBV reinfection was amplified by PCR and directly sequenced. RESULTS: According to transaminase and HBV DNA hybridization analysis, 3/18 (17%) liver transplant patients had HBV and hepatitis recurrence during anti-HBs therapy. A HBV S-gene mutant containing a G to A nucleotide mutation at position 587, converting Glycine to Arginine (G145A), was identified in all three patients as the dominant population at reinfection but not pre-transplantation. Contrary to the S-gene, no consistent nucleotide changes were found in the pre-S2 region of HBV genomes when comparing the reinfection and pre-transplantation samples. CONCLUSIONS: These data demonstrate that long-term polyclonal anti-HBs immunoprophylaxis selected the most commonly described G145R S-gene escape HBV variant which became the dominant virus population and was responsible for graft infection. Therefore, immunoglobulins with high affinity for the G145R HBs variant should be included in HBIg to prevent recurrent HBV infection in transplant patients.

Adult↗
PubMedDate not supplied

Quench-flow measurements of initial rates of Ca2+ accumulation by isolated cardiac sarcoplasmic reticulum.

Using a quench-flow technique, the initial velocity of Ca2+ accumulation by isolated cardiac sarcoplasmic reticulum was estimated at free Ca2+ ion concentrations in the range encountered in the myoplasm during the cardiac contraction cycle. With cardiac microsomes exhibiting a Ca2+ accumulative capacity of 25.6 nmol Ca2+/mg protein, initial rates were found to increase from 3.7 to 33.4 nmol Ca2+/mg protein/sec, when the free Ca2+ ion concentration was raised from 0.2 to 18.0 muM. Preincubation of the cardiac microsomes with a party purified soluble cardiac protein kinase, MgATP, and cAMP led to a significant increase in the initial Ca2+ accumulation rate.

Animals↗
PubMedDate not supplied

[Assessment of grief exemplified pregnancy loss: development and initial results on the validity of the Munich Grief Scale].

Bereavement research is hampered conceptually by confounding of grief and depression, methodologically by a lack of generally agreed-upon measures. Therefore we developed the Munich Grief Scale (MGS) based on the Perinatal Grief Scale (PGS, Potvin et al. 1989) and results from a previous study. Validation included comparisons with standardized self-report scales of depression, anxiety and physical symptoms. It was based on a follow-up study of 125 patients who had miscarried and 3 comparison groups who either suffered from a miscarriage or a stillbirth. Self-reports were compared to expert ratings of grief and depression. The MGS is a economical, reliable self- and expert rating scale after pregnancy loss. The applicability of the grief measures to other kinds of bereavements remains to be determined.

Abortion, Spontaneous↗