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Biomedical subjects

A B Ibrahim

Publications and source records attributed to A B Ibrahim.

18 recordsLinked to original sources
PubMed2005

Seroepidemiology of hepatitis A in patients with chronic liver disease.

Hepatitis A virus (HAV) rarely causes fulminant hepatic failure in the general population. Yet it is a cause of significant morbidity and mortality in patients with chronic liver disease (CLD), in whom routine HAV vaccination is recommended. However, studies of HAV seroprevalence and exposure predictors in populations with CLD are scarce. We have studied a cohort of 473 patients with various causes of CLD between July 2000 and June 2002. Patients were stratified on the basis of age, gender, ethnicity and aetiology of liver disease. The HAV seroprevalence in patients with CLD was compared with that in the general population. We used a logistic regression analysis to identify independent predictors of HAV exposure. Of the 473 patients studied, HAV seroprevalence was available for 454 individuals. HCV, HBV, alcohol, and HCV and alcohol were the causes of CLD in 337, 72, 37 and eight patients, respectively. The overall HAV seroprevalence was 55% in the studied cohort. The age-stratified HAV prevalence for ages 21-30, 31-40, 41-50, 51-60, 61-70 and greater than 70 years was 44, 51, 44, 63, 65 and 64%, respectively. Hispanic ethnicity, Asian ethnicity, alcohol use and ages of 51-70 years were found to be independent predictive variables of prior exposure to HAV. HAV infection in patients with CLD causes considerable morbidity and mortality. We demonstrated that age-stratified seroprevalence of HAV in patients with CLD of various aetiologies is significantly higher than that of the general population, and identified several independent predictors of HAV prior exposure.

Adult↗
PubMed2004

Same day outpatient transjugular liver biopsies in haemophilia.

Patients with haemophilia are at increased risk of hepatitis C infection because of prior transfusion of blood products. Virtually all haemophiliacs who received pooled blood products before the mid-1980s have been infected with hepatitis C. A liver biopsy is important to identify the extent of liver disease, and to help determine the necessity of interferon therapy. With factor replacement, in-hospital liver biopsy is safe. Thirty patients with haemophilia were evaluated for chronic hepatitis C infection. Eleven patients subsequently underwent successful transjugular liver biopsy in the outpatient setting after appropriate factor replacement. Mean +/- SD pre- and posthaemoglobin values were 15.8 +/- 0.79 and 14.4 +/- 0.71 g dL(-1) (P = ns). There was no significant change in heart rate, systolic or diastolic blood pressure during the monitoring period (P = ns) and no major complication was noted in perioperative follow-up. The mean length of the liver biopsy specimens was 1.7 +/- 0.3 cm, mean grade was 2 +/- 0.6 and mean stage was 2.3 +/- 1.2. Our experience demonstrates that outpatient transjugular liver biopsy can be safely performed in patients with haemophilia in the outpatient setting, avoiding the cost and need for hospital admission.

Adult↗
PubMed1982

Dietary fat affects immune response, production of antiviral factors, and immune complex disease in NZB/NZW mice.

Autoimmune-prone (NZB x NZW)F1 (B/W) mice fed three nearly isocaloric diets with varied fat content showed a marked difference in their spontaneous development of immune complex disease and their immune response. Those animals received the diets high in either unsaturated or saturated fats had more severe immune complex nephritis and died earlier than mice on the low-fat diet. Endogenous production of the mouse xenotropic virus was unaffected by dietary fats, but the serum lipoproteins associated with antiviral activity were increased to levels as high as 1:600,000 in the B/W mice on the high-fat diets. These lipoproteins may be partially responsible for the decreased mitogenic response of spleen cells from mice fed the two high-fat diets. The mice receiving a diet high in saturated fats produced substantially higher titers of natural thymocytotoxic autoantibody, an IgM class of antibody, than did the mice maintained either on the high-unsaturated-fat or low-fat diet. In contrast, the mice receiving the diet high in unsaturated fats made significantly greater levels of antibodies to double-stranded DNA, an IgG, than did the mice kept on the two other diets. These results suggest that the type of fat in the diet could affect the serum level of different immunoglobulin classes. The data provide further evidence that the amount of dietary lipids alone can influence cellular and humoral immune responses and the spontaneous development of immune complex disease.

Animals↗
PubMed1975

Immune response to hepatitis B surface antigen.

A total of 69 persons were investigated for assessment of cell-mediated and humoral immunity to hepatitis B surface antigen (HBsAg). Three groups, each consisting of 20 normal persons, 20HBsAg carriers, and 20 convalescent hepatitis B patients, were studied for HBsAg, anti-HBs, and leukocyte migration inhibition with purified HBsAg. Sequential sampling if an additional group of nine acute hepatitis B patients defined the cellular and humoral immune response to HBsAg. The antigen was eliminated rapidly by mounting of cell-mediated immune response detectable for a limited period, followed by antibody response in relatively few patients moore than 3 months after clearance of circulating HBsAg.

Antibody Formation↗
PubMed1975

Specific immunotherapy proposed for hepatitis B virus infection.

Immune response to hepatitis B surface antigen (HBsAg), coinciding with removal of HBsAg from the circulation, has been shown to be a cell-mediated response assessed by leukocyte migration inhibition assay. Immune response to HBsAg is a T-cell dependent phenomenon in the nude mouse model. Immunological tolerance in man appears to stem from the absence of cellular and humoral immune response to HBsAg, causing a chronic carrier state which serves as an epidemiological reservior for the transmission of viral hepatitis type B. Specific immunotherapy in hepatitis may consist of adoptive transfer of immunity to HBsAg. It is proposed to be accomplished by administration of anti-HBs, transfer factor or 'immune-RNA'. The efficacy and safety of 'immune-RNA' administration to chronic carriers can be validated by leukocyte migration inhibition techniques in vitro and in HBsAg positive chimpanzees in vivo.

Animals↗
PubMed1973

Experimental induction of anergy to coccidioidin by antigens of Coccidioides immitis.

Failure to react to coccidioidin (anergy) often occurs in patients with disseminated coccidioidomycosis. One possible reason may be desensitization by excessive amounts of antigen. This was studied experimentally by injection of soluble and hyphal antigens of Coccidioides immitis into coccidioidin- and tuberculin-sensitive guinea pigs. Guinea pigs sensitized by injection of killed hyphal cells of C. immitis in complete Freund adjuvant were subsequently injected daily either with soluble coccidioidal antigen administered intraperitoneally or with hyphal antigen administered either subcutaneously or intraperitoneally. Gradual loss of cutaneous reactivity to coccidioidin occurred, but the reactivity to tuberculin remained unimpaired. The rapidity of desensitization was roughly proportional to the dose of antigen with desensitization occurring as early as 6 days after beginning injections. This anergic state was temporary, and reactivity returned several days after discontinuing injection of antigen. Injection of coccidioidal antigen led to production of coccidioidal complement-fixing antibody, but there was no consistent relationship between the antibody titer and state of cutaneous reactivity to coccidioidin. Peritoneal exudate or pulmonary alveolar cells from desensitized animals migrated freely in the presence of coccidioidin but were inhibited in the presence of tuberculin. Heat treatment did not impair the capacity of the soluble or hyphal antigen to induce anergy, thus suggesting that the antigen active in complement fixation was perhaps not involved in desensitization. Polysaccharide obtained by ethanol precipitation of dialyzed coccidioidin failed to induce anergy. Dialysis of the soluble coccidioidal antigen caused the loss of the desensitizing activity. Thus, specific desensitization could be induced by administration of large doses of coccidioidal antigen but dialyzable components appear important in this desensitization.

Animals↗
PubMed1972

Australia antigen (hepatitis B antigen): a conformational antigen dependent on disulfide bonds.

Reduction and alkylation of purified hepatitis-associated Australia antigen (hepatitis B antigen) resulted in a total loss of serologic activity. The reduced and alkylated protein formed a single band with a sedimentation coefficient of 31S on analytical ultracentrifugation, and no subunits were detected by Sephadex gel filtration. Although this preparation induced a delayed hypersensitivity response when injected into guinea pigs, it failed to stimulate humoral antibody formation. The data suggest that hepatitis B antigen is a conformational antigen critically dependent upon the disulfide bonds of the protein moiety.

Acetates↗