The influence of age on isometric and isotonic rat detrusor contractions.

BACKGROUND: Reductions in detrusor shortening velocity and detrusor contractility have been observed in association with aging. The reasons for these changes are unclear. METHODS: We examined the isometric and isotonic responses of detrusor, taken from the bladder body, to adenosine 5'-triphosphate (ATP), noradrenaline (NA), serotonin, and acetylcholine (Ach) in vitro, using bladders from young (30 days) and old (365 days) Sprague-Dawley rats, to determine whether there were any significant age-related differences. RESULTS: Isometric contractions with ATP at doses of 10(-3) to 10(-2) molar concentrations produced greater contractile forces in old rats when compared to young rats (p = .0136 at 10(-2) mole of ATP). Isotonic contractions at similar concentrations also produced significant differences between the young and the old rats, the latter being faster (p = .0225). Isometric contraction with noradrenaline produced significant differences between young and old rats, the latter being stronger. This became apparent at 10(-4) molar concentration of noradrenaline (p = .0043). Isometric contractions with serotonin also produced significantly greater contractions in the old rats when compared to young rats. The differences became apparent at 10(-4) molar concentration of serotonin (p = .045). There were no age-related differences in isotonic and isometric contractile responses to acetylcholine in the doses used in our experimental setup. CONCLUSIONS: Age-related differences in isometric function were detected in response to ATP, NA, and serotonin. Differences in isotonic function were only found in response to ATP and Ach.

Epitope mapping of HBsAg using a panel of human anti-HBs antibodies.

Mapping of B cell epitopes on HBsAg was performed using a panel of human anti-HBs antibodies. Synthetic peptides representing different regions of HBsAg failed to inhibit the binding of two antibodies which recognized non-conformational HBsAg determinants in dot-blot ELISA and HBsAg polypeptide bands in immunoblot analysis. Cross-inhibition studies using five of the antibodies conjugated to horseradish peroxidase suggested that at least three different epitopes are recognised by the panel of antibodies, two of which are within the 'a' group determinant.

Comparison of an EBV transformed cell line and an EBV hybridoma cell line producing the same human anti-HBs monoclonal antibody.

A stable human-mouse heterohybridoma secreting human anti-HBs monoclonal antibody in continuous culture for 12 months was generated. It grew faster than the parent EBV transformed lymphoblastoid cell line (LCL) but produced the same level of specific antibody. The LCL was positive for the Epstein-Barr Virus Nuclear Antigen (EBNA), human CD 23 and contained a diploid number of human chromosomes. The heterohybridoma was negative for EBNA, CD 23 and mouse Ly-1 mouse, despite retaining a full complement of diploid mouse chromosomes and a limited number of human chromosomes.

Development and characterization of human anti-HBs antibodies.

Peripheral blood mononuclear cells (PBMC) from 13 healthy hepatitis B vaccines were transformed with the Epstein-Barr virus (EBV) and lymphoblastoid cell lines (LCL) producing antibodies to hepatitis B surface antigen (anti-HBs antibodies). Seven LCL and two clones secreting human anti-HBs monoclonal antibody were generated and their antibodies purified. One clone was fused with a mouse myeloma and the antibody from a cloned anti-HBs secreting heterohybridoma purified. One of the 10 purified human anti-HBs antibodies was characterized as IgG4, the remainder were IgG1. The antibodies had either kappa or lambda light chains. Five of the antibodies which were conjugated to horseradish peroxidase recognised the "a" group determinants.

Lymphotropic viruses in 'common variable' immunodeficiency--PCR analysis of lymphocyte DNA for HIV-1 and HHV-6.

DNA of circulating lymphocytes obtained from 17 patients with 'common variable' immunodeficiency (CVID) was tested for the presence of HIV-1 sequences, using a variety of primers complementary to conserved regions of HIV-1 genomes. None of the patients was positive. The DNA from 12 CVID patients was tested for the presence of human herpesvirus 6 (HHV-6), using appropriate primers for this virus which is known to remain latent following primary infection in the majority of people during childhood. Similar numbers of patients and normal subjects were positive (about 30%), suggesting that CVID patients are not particularly prone to reactivation of this virus. Despite previous anecdotal reports of an unexplained association between HIV-1 and CVID, we conclude that there is no evidence that this virus is implicated in the pathogenesis of CVID. A role for HHV-6 also seems unlikely.