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Biomedical subjects

J C Porres

Publications and source records attributed to J C Porres.

61 records · Page 4Linked to original sources
PubMed1985

Radioimmunoassay for detecting hepatitis B core antigen in serum from patients with chronic hepatitis B infection.

The core antigen component of hepatitis B virus (HBV), HBcAg, may be used as a marker of viral replication. We describe a radioimmunoassay for HBcAg in serum, and compare results with those by other similar methods. Samples are centrifuged over a sucrose gradient containing 2-mercaptoethanol, and the resulting pellets are resuspended in a nonionic detergent solution. After a bead coated with anti-HBcAg is incubated with this suspension, 125I-labeled anti-HBcAg is added, and is also bound by the antigen. The specificity of the method was verified by blocking with purified IgG antibodies to HBcAg. When we tested by this method for HBcAg in sera from 60 patients with chronic HBV infection, all those with circulating HBV-DNA polymerase tested positive for HBcAg. All sera from HBV-negative controls showed no detectable HBcAg. The correlation between the presence of HBcAg and HBV-DNA polymerase was significant (r = 0.715, p less than 0.001). Samples can be tested more quickly and easily with this method, and its sensitivity compares well with that of other similar methods.

Chronic Disease↗
PubMed1985

Vaccination against hepatitis B in renal dialysis units: short or normal vaccination schedule?

Three I.M. injections of hepatitis B vaccine (Merck Sharp & Dohme) were administered, according to the recommended schedule (0, 1, 6 mos), to seronegative individuals of one renal dialysis unit (33 patients, 58 health care personnel) and, according to a shorter regimen (0, 1, 3 mos), in another unit of similar characteristics (30 patients, 53 health care personnel). Staff members and renal patients received, respectively, 20 y 40 mcg of vaccine per injection. In the early vaccination phase, the two regimens did not lead to a difference in seroconversion rates nor in anti-HBs titers. After a 9-month surveillance, lower seroconversion rates, although not significant, were observed with the accelerated regimen among staff members (84.2%) and renal patients (79.2%) as compared with 93% and 87.5%, respectively, following the normal schedule. At the same time, anti-HBs titers were significantly lower (p less than 0.001) in the staff (316 RIA U) and patients (93 U) vaccinated according to the short regimen than in their respective counterparts (4196 and 1047 U) assigned to the normal schedule. A fourth dose of vaccine given to subjects with low and no anti-HBs titers significantly increased seroconversion and anti-HBs levels, although with little success among the former non-responders.

Adult↗
PubMedDate not supplied

Hemagglutination and immunofluorescence studies on polymerized human serum albumin binding activity in chronic hepatitis B virus infection.

The binding activity of polymerized human serum albumin was determined in 202 HBsAg carriers. The presence of polymerized human serum albumin receptor sites was tested by hemagglutination and differentiated from antihuman albumin antibodies by immunofluorescence, isolation of IgG and IgM fractions and testing of HBsAg anti-HBs immune complexes. A granular pattern with anti-HBs was specific for polymerized human serum albumin receptor sites as demonstrated with purified HBsAg. In addition, a linear pattern with fluoresceinated antihuman immunoglobulins might suggest the presence of antihuman albumin antibodies (which was generally due to an IgG antibody). However, a granular pattern with fluoresceinated antihuman immunoglobulins may indicate the presence of HBsAg anti-HBs immune complexes. A weak linear pattern was also observed simultaneously in these cases, probably due to IgM antihuman albumin antibodies or an antipolymerized human serum albumin receptor site antibody. Of 202 HBsAg-positive patients, 71 showed polymerized human serum albumin receptor sites activity. The highest percentage of polymerized human serum albumin receptor sites was found among patients showing HBeAg and hepatitis B virus DNA polymerase positivity (96%), followed by HBeAg positivity and hepatitis B virus DNA polymerase negativity (48%), and anti-HBe positivity and hepatitis B virus DNA polymerase negativity (17%). In addition, a significant correlation between polymerized human serum albumin titers and hepatitis B virus DNA polymerase was found (r = 0.573, p less than 0.01). However, at similar HBeAg titer, patients who were positive for hepatitis B virus DNA polymerase had a higher polymerized human serum albumin receptor sites titer than those who were negative for hepatitis B virus DNA polymerase.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

IgG and IgM autoantiidiotype antibodies against antibody to HBsAg in chronic hepatitis B.

Antibody directed against HBsAg carries idiotypic determinants that may induce an autoantiidiotype antibody response. We describe a solid-phase radioimmunoassay which allows specific detection of either IgG or IgM antibody to antibody directed against HBsAg. Among 138 chronic hepatitis B virus carriers, IgG autoantiidiotype was detected in 98 (71%) and IgM autoantiidiotype in 10 (80%). The autoantiidiotype reaction was blocked with antibody directed against HBsAg after removal of immune complexes by polyethylene glycol precipitation. The prevalence and levels of both classes of autoantiidiotype antibodies were highest in patients with hepatitis B virus DNA or HBeAg in serum. During follow-up, patients who lost hepatitis B virus DNA and HBeAg from serum had lower titers of autoantiidiotype and were less likely to have autoantiidiotype than patients who persisted in having hepatitis B virus DNA and HBeAg in serum. Thus, the presence and titer of autoantiidiotype correlated with serologic evidence of active viral replication in chronic hepatitis B. These findings suggest that the antibody directed against HBsAg response may play a role in modulating viral replication in chronic hepatitis B.

Adult↗