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Biomedical subjects

W D Reed

Publications and source records attributed to W D Reed.

At least 37 records · Page 2Linked to original sources

Validation of prognostic models in primary biliary cirrhosis.

Prognostic models in primary biliary cirrhosis have been validated for large population groups but the predictive value for individual patients has not been tested. We used data from ten deceased patients with primary biliary cirrhosis to test three prognostic models: the Shapiro model (bilirubin); the Christensen model (age, bilirubin, albumin, presence of cirrhosis or cholestasis, azathioprine treatment); and the Dickson model (age, bilirubin, albumin, prothrombin time, oedema). The predictive value of each model for individual patients was determined by assessing whether it would have accurately predicted appropriate timing of liver transplantation in patients prior to death. The Dickson model predicted that four of nine cases would have been considered for liver transplantation one year before death and one of seven cases two years before death. The Christensen model predicted that this procedure would have been considered in three of seven cases two years before death. The Shapiro model was demonstrated to be the least predictive of the three tested. Although none of the three models assessed was found to accurately predict survival, no model predicted a worse survival than actually occurred. Liver transplantation is indicated in those cases with a poor predicted survival.

Aged↗

Bile duct antibodies crossreacting with blood group antigens in primary sclerosing cholangitis.

Indirect immunoperoxidase histochemistry was used to localise and determine the disease, species, and tissue specificity of bile duct antibodies in primary sclerosing cholangitis. Serum was collected from: 29 patients with primary sclerosing cholangitis, 18 patients with ulcerative colitis alone, 19 patients with extrahepatic biliary obstruction of other causes, and 42 healthy control subjects. Bile duct antibodies reacted with an antigen localised to the small and large intrahepatic bile ducts. When blood group A human liver was used they were detected in 34% of patients with primary sclerosing cholangitis. They were not detected when blood group O human liver was used. Bile duct antibodies that reacted with obstructed and normal rabbit liver were detected in 34% and 17% respectively of patients with primary sclerosing cholangitis but were also present in similar proportions of control subjects. Colon antibodies that reacted with human and rabbit colon were found in 52% and 24% respectively of patients with primary sclerosing cholangitis. Absorption studies using blood group substances A and B abolished the reactivity of bile duct antibodies with human and rabbit liver and that of colon antibodies' with rabbit colon. Colon antibodies that reacted with human colon were not absorbed. Absorption studies using isolated peripheral white blood cells did not affect reactivity of bile duct or colon antibodies. We conclude that bile duct antibodies are disease, species, and tissue non-specific and react with blood group A/B antigens present in human and rabbit bile ducts and rabbit colon. This suggests that they do not play a role in the pathogenesis of primary sclerosing cholangitis.

Antibody Specificity↗

Genetic control of mouse cytomegalovirus-induced myocarditis.

Mouse cytomegalovirus (MCMV) infection of mice induced myocarditis, characterized by a mononuclear cell infiltrate with associated necrosis of myofibres. Myocarditis was observed in parallel with viral inclusion-bearing cells in the heart during the acute phase of the infection. Myocarditis also persisted after the acute phase when viral antigens were no longer detectable by immunoperoxidase histochemistry and infectious virus could not be cultivated from various organs. The influence of host genetic factors on the development of cytomegalovirus-induced myocarditis was investigated using H-2 congenic and recombinant inbred mouse strains. Analysis of congenic variants with C57BL/10 and BALB/c backgrounds and the A/J strain revealed that genes linked to the H-2 complex influenced susceptibility to peak levels of MCMV-induced myocarditis seen 7 and 10 days post-infection. In addition, non-H-2 genes of the BALB/c background were important in determining the severity of myocarditis. Analysis of the strain distribution pattern of the CXB recombinant inbred series did not disclose the identity of the BALB/c non-H-2-linked allele conferring susceptibility to MCMV-induced myocarditis. The level of myocarditis seen in the F1 hybrid between the high-responder BALB/c and low-responder C57BL/6 strains suggested dominant inheritance. The amount of viral replication in the major target organs did not correlate with the severity of myocarditis. In conclusion, at least two genes, one mapping to the H-2 complex and another non-H-2-linked gene, influenced the development of myocarditis in MCMV-infected mice.

Animals↗

Autoantibodies to cardiac myosin in mouse cytomegalovirus myocarditis.

Myocarditis accompanies sublethal mouse cytomegalovirus (MCMV) infection in susceptible BALB/c mice and persists beyond the acute phase of infection, in the absence of demonstrable virus antigen but in the continuing presence of autoantibodies to cardiac muscle. Heart tissue autoantibodies of the IgG class were first detected by ELISA in sera at Days 3-5 post-infection (PI) and persisted to Day 100, in two strains of MCMV-infected mice which are susceptible (BALB/c) and resistant (C57BL/10) to MCMV-induced myocarditis. Analysis by immunoblot showed that autoantibodies in early immune sera (Day 10) from both mouse strains reacted with the contractile proteins troponin, tropomyosin and myosin, as well as with other unidentified polypeptides within normal mouse organ homogenates. However, the dominant reactivity of late immune sera (Day 100) was to a 200,000 molecular weight (MW) polypeptide in muscle homogenates identified as the heavy chain of myosin. Autoantibodies reacting with the cardiac or striated muscle isoforms of myosin were assessed by ELISA in BALB/c and C57BL/10 mice. At Days 28, 56 and 100 PI only the susceptible BALB/c strain had high titres of autoantibodies reacting with the cardiac isoform of myosin. Increasing the virus dose given to C57BL/10 mice resulted in slight increases in titres of anti-myosin antibody; however, the peak antibody titres did not approach those of BALB/c mice and persisting myocarditis did not develop. Absorption experiments showed that cardiac myosin-specific antibodies were present in immune sera from susceptible BALB/c mice at Day 100 but not in resistant C57BL/10 mice by ELISA and immunoblot. These results demonstrate that autoimmunity to myosin is a prominent feature of the humoral autoimmune response following MCMV infection, and that there are differences both in fine isoform specificity and titre of anti-myosin antibodies between strains of mice that develop persisting myocarditis and strains that do not. Cardiac myosin-specific autoantibodies may play an immunopathogenic role in CMV-induced myocarditis.

Animals↗

Autoantibodies to isolated human hepatocyte plasma membranes in liver disease. I. Specificity for chronic active hepatitis.

Circulating autoantibodies reacting with human hepatocyte plasma membranes (HHPM) were quantitated in acute and chronic liver disease using an enzyme-linked immunosorbent assay (ELISA). Anti-HHPM were found most frequently in patients with chronic active hepatitis (CAH), a disease postulated to result from autoimmune processes directed at organ-specific antigens on the surface of hepatocytes. The high incidence of anti-HHPM in CAH (75%) contrasted significantly with all other groups assayed, including primary biliary cirrhosis (44%), alcoholic liver disease (21%), acute viral hepatitis (17%), and chronic persistent hepatitis (8%). The titers of anti-HHPM in CAH were significantly greater than in other liver disease and control groups. Anti-HHPM quantitated by ELISA correlated with hepatocellular membrane staining by indirect immunofluorescence. Autoantibodies to HHPM were found with an equivalent frequency in three etiological subgroups of CAH: autoimmune CAH, hepatitis B virus (HBV)-related CAH, and CAH associated with excess alcohol consumption. Anti-HHPM of the IgG and IgA isotypes were found in the highest frequency. There was a trend for patients with a histologically more severe disease to have higher titers of anti-HHPM. Immunoblots of SDS-PAGE-separated HHPM showed antibodies to react with a number of polypeptides, some of which appeared human specific. These data suggest that isolated HHPM are a source of relevant hepatocellular membrane antigens. Further studies of the different antigenic specificities of anti-HHPM are required to define which of these may be of pathogenetic importance in chronic active hepatitis.

Autoantibodies↗

Evaluation of omeprazole in reflux oesophagitis.

In patients with reflux disease, pH monitoring has shown that omeprazole virtually eliminates oesophageal exposure to a pH of less than 4. Motility studies concurrent with pH monitoring have indicated that reflux continues on omeprazole, its effect on acid exposure being entirely dependent on elevation of gastric pH. Omeprazole and placebo have been compared in 64 patients with erosive or ulcerative oesophagitis; the 4-week healing rates were 81% with omeprazole, 20 mg or 40 mg daily, and 6% with placebo. The efficacies of omeprazole at doses of 20 mg and 40 mg daily, were then compared in 164 patients. At 4 weeks, oesophagitis was healed in 70% and 82% of patients for the 20 mg and 40 mg doses respectively (p = 0.05). Eight-week healing rates (79% for 20 mg and 85% for 40 mg) did not differ significantly. Symptom response was excellent for both doses. Relapse of oesophagitis was determined over 6 months for patients healed with omeprazole. Relapse was shown to occur in 88 of 107 patients by 6 months. Omeprazole is a highly effective treatment for erosive/ulcerative peptic oesophagitis, 40 mg daily being marginally superior to 20 mg. Relapse is almost inevitable within 6 months of cessation of therapy.

Dose-Response Relationship, Drug↗

The role of T cells in mouse cytomegalovirus myocarditis.

BALB/c mice infected with murine cytomegalovirus (MCMV) developed myocarditis. Athymic nu/nu mice infected with the virus did not develop myocarditis, in contrast to heterozygous T-cell competent nu/+mice. MCMV-infected BALB/c mice given cyclosporin A(CsA) a drug which inhibits the activation of T cells, showed a delay in the development of myocarditis relative to CsA-untreated mice infected with MCMV. However, BALB/c mice infected with MCMV, regardless of CsA treatment, developed both anti-MCMV antibodies and autoantibodies. Nu/nu mice infected with MCMV did not produce the anti-MCMV antibody response or the multiple autoantibody response which was observed in nu/+ MCMV-infected mice. Both nu/nu and CsA-treated animals displayed greater organ distribution of viral antigen than control MCMV-infected animals. These results suggest that the presence of a thymus is required for both the development of myocarditis and the multiple autoantibody response, which includes autoantibodies to cardiac muscle, and that CsA immunosuppression does not abrogate either myocarditis or the antibody response in mice following MCMV infection.

Animals↗

Healing and relapse of severe peptic esophagitis after treatment with omeprazole.

We have studied the response of erosive or ulcerative esophagitis to treatment with omeprazole and its subsequent relapse on cessation of therapy in 196 patients. In the first phase of the study omeprazole (20 or 40 mg daily) was compared with placebo in 64 patients. After 4 wk there was endoscopic healing in 81% (25 of 31) of omeprazole-treated patients and in only 6% (2 of 32) of placebo-treated patients. Endoscopic healing of esophagitis was accompanied by symptom relief and histologic healing of ulceration. In the second (dose finding) phase a further 132 patients were randomized to omeprazole (20 or 40 mg daily) and endoscopic healing was assessed. In patients with the mildest grade of ulcerative esophagitis (grade 2), healing occurred at 4 wk in 87% receiving 20 mg and in 97% receiving 40 mg. In patients with grade 3 esophagitis, 67% (20 mg) and 88% (40 mg) were healed. Less than half the patients with grade 4 esophagitis (Barrett's ulcers or confluent ulceration) healed with either 20 mg (48%) or 40 mg (44%). Regression analysis in the 164 omeprazole-treated patients showed no evidence that healing was influenced by factors other than severity of esophagitis at entry and omeprazole dose. In phase 3 of the study the rate of endoscopic relapse was determined in 107 endoscopically healed patients after stopping omeprazole. Erosive or ulcerative esophagitis recurred in 88 of 107 (82%) by 6 mo. Neither initial dose, grade of esophagitis, nor smoking was shown to influence relapse rate. Omeprazole is a highly effective treatment for peptic esophagitis. The 40-mg/day dosage produces endoscopic healing slightly more quickly than the 20-mg/day dosage, and the initial endoscopic gradings are of prognostic value. Relapse occurs rapidly when treatment is stopped.

Adult↗

Multiple autoantibodies following cytomegalovirus infection: virus distribution and specificity of autoantibodies.

Multiple autoantibodies were found in the sera of BALB/c, C57BL/10 and C3H mice following mouse cytomegalovirus (MCMV) infection. The complex pattern of intra-organ, intratissue and intracellular reactivity observed by immunoperoxidase histochemistry suggested that many autoantibodies of varying specificities were elicited. This evidence from immunoperoxidase histochemistry was confirmed by immunoblot, where autoantibodies binding to polypeptides of a variety of sizes and tissues of origin were observed. In addition to these central findings, the tissue and organ distribution of MCMV in three mouse strains of differing genetic resistance were described. No correlation was found between the distribution of virus and the tissue and organ specificity of the autoantibodies produced following infection. Inflammatory responses accompanied MCMV infection in a number of tissues. In BALB/c mice, myocarditis and salivary gland inflammation were evident at Day 56 post-infection in the absence of MCMV, but in the presence of autoantibodies to cardiac muscle and salivary duct epithelium. This model for virus-induced autoimmunity can be applied to studies of the relationship between virus infection, autoimmunity and disease.

Animals↗

The relationship between liver-specific lipoprotein and the hepatocyte plasma membrane.

Liver-specific lipoprotein (LSP) has been the subject of intense investigation as a candidate target antigen in chronic active hepatitis. Fundamental to the interest in LSP has been the belief that it is an antigen complex of hepatocyte plasma membrane origin. In this study the physical, biochemical and antigenic relationships between LSP and isolated hepatocyte plasma membrane (HPM) were investigated. Electron microscopic examination of LSP showed it to be devoid of plasmalemma sheets that were abundant in HPM. The plasma membrane marker enzyme 5'-nucleotidase was enriched 11-fold in HPM relative to liver homogenate, whereas the enzyme activity in LSP was 17% of that found in liver homogenate and only 1.5% of that found in HPM. The antigenic relationship between LSP and HPM was assessed using sera from rabbits immunized with either mouse LSP or mouse HPM. By filtration ELISA, antibody to LSP reacted poorly with entrapped HPM, relative to antibody to mouse HPM. Antisera to LSP and HPM were both effectively absorbed by the immunizing antigen, however antibody to LSP was not absorbed with HPM, and minimal cross-absorption of HPM antibody with LSP was found. By immunoblot of SDS-PAGE separated LSP and HPM, it was shown that antigenic cross-reactivity between LSP and HPM at the polypeptide level was rare. By immunofluorescence, antibody to LSP failed to react with the surface of viable mouse hepatocytes, whereas antibody to HPM showed linear fluorescence. The data show that the two preparations, LSP and HPM, are dissimilar antigen complexes. HPM may be a more appropriate preparation for the study of autoimmune liver disease than LSP.

5'-Nucleotidase↗

An enzyme-linked immunosorbent assay for the detection of hepatocyte plasma membrane antibodies.

An enzyme-linked immunosorbent assay (ELISA) using plates coated with hepatocyte plasma membranes (HPM) was developed for the measurement of antibodies directed at hepatocyte surface antigens. Precoating ELISA plates with poly-L-lysine (PLL) provided firm attachment for the adsorption of HPM. The use of HPM, in preference to whole hepatocytes, excludes pathologically irrelevant cytoplasmic antigens. In addition, there is no necessity for glutaraldehyde fixation which is commonly used in cellular assays to maintain cellular integrity and which may result in loss or alteration in antigenic specificities. The assay was used to study loss of tolerance to mouse HPM in mice immunized with rat HPM. Three mouse strains were immunized, each strain developed antibodies to rat HPM and autoantibodies to mouse HPM with autoantibody levels reaching a peak 6-10 weeks after commencement of immunization. The correlation between ELISA and indirect immunofluorescence for the measurement of HPM autoantibodies was 0.79 (P less than 0.001) within the serum titration range of 1:25 to 1:200. Antibody to control kidney plasma membrane (KPM) was also measured by ELISA, after elimination of endogenous alkaline phosphatase activity using levamisole. Immunization with rat HPM elicited organ-non-specific autoantibodies to KPM, but these were at lower levels than autoantibodies to HPM.

Alkaline Phosphatase↗

Adrenergic sensitivity of cultured murine trisomy 16 cells.

Murine trisomy 16 (Ts16) has been proposed as a model to study Down's syndrome (DS), because mouse chromosome 16 carries several genes homologous to loci on the human chromosome 21. A characteristic of DS is an increased sensitivity to adrenergic ligands. We have tested the sensitivity of murine Ts16 fibroblasts and embryonic cells to epinephrine and isoproterenol. A 2-4-fold reduction in the accumulated cyclic AMP (cAMP) was observed in response to these beta 1-adrenergic ligands. Since these cells also accumulated a 2-4-fold reduced amount of cAMP in response to prostaglandin E1, the data suggest that a change in the adenylcyclase of these cells exists which is not seen in cells derived from DS individuals. Therefore, murine Ts16 cells do not appear to constitute an appropriate model to study the altered adrenergic function of DS.

Adenylyl Cyclases↗

The effects of insulin and glucagon on ketone-body turnover.

A double-isotope procedure was used to measure the effects of insulin and glucagon on ketone-body production and utilization (i.e. turnover) in the starved rat. Somatostatin was infused during the experiment to suppress the pancreatic release of either hormone. The immediate action of insulin in terms of ketone-body turnover that was most evident was a decreased production of 3-hydroxybutyrate, with no significant change in the turnover of acetoacetate. Similarly, the significant effect of glucagon infusion was to increase the production of 3-hydroxybutyrate, with minimum increase in acetoacetate turnover. The data support a direct effect of both hormones on the distribution of acetyl units derived from fatty acid beta-oxidation.

3-Hydroxybutyric Acid↗

A double-isotope method for the measurement of ketone-body turnover in the rat. Effect of L-alanine.

The synthesis of 4-3H-labelled ketone bodies, and their use along with 14C-labelled ketone-body precursors, is employed using an 'in vivo' rat infusion model to measure ketone-body turnover. The use of two isotopes is necessary to measure ketone-body turnover when ketogenesis may occur from more than one precursor such as glucose and fatty or amino acids. Requirements of isotopic equivalence in terms of metabolic similarity, valid stoichiometry and the lack of differences in the kinetics of relevant enzymes is demonstrated for the 4-3H- and 14C-labelled ketone bodies. The hypoketonaemic effect of L-alanine is shown by two distinct phases after the administration of L-alanine. During the first 12 min after alanine administration ther was a 50% decrease in acetoacetate and a 30% decrease in 3-hydroxybutyrate production, with no significant change in the utilization of either compound. The hypoketonaemic action of alanine during the following 16 min was primarily associated with an uptake of 3-hydroxybutyrate that was somewhat greater than the increase in its production. There were essentially equivalent decreases in production and utilization of acetoacetate, resulting in no significant net change in the level of this ketone body in the blood.

3-Hydroxybutyric Acid↗

Neurochemical changes in murine trisomy 16: delay in cholinergic and catecholaminergic systems.

Two strains of Mus musculus musculus, C57BL/6J and CD-1, and Mus musculus poschiavinus, the tobacco mouse, were used to study the effects of increased gene dosage of mouse chromosome 16 (MMU 16). A developmental delay has been found in the brains of murine trisomy 16 (Ts16) fetuses. Both the brain weight (in all three strains) and DNA content (in CD-1) were reduced, while protein content was unchanged in Ts16 compared to normal littermates. The daily increments of weight and protein (except in M. m. poschiavinus) were significantly greater in Ts16. The activities of choline acetyltransferase and acetylcholinesterase and muscarinic receptor binding were reduced. Their daily increments were also reduced to less than 56% that of littermates in Ts16 brains. The rate limiting enzymes of catecholaminergic neurons, tyrosine hydroxylase and dopamine beta-hydroxylase, and the concentration of catecholamines in the brains of Ts16 animals were lower. The activities of three other catecholaminergic enzymes, DOPA decarboxylase, catechol O-methyltransferase, and monoamine oxidase, were generally elevated in Ts16 brain, as were their daily increments. These observations indicate a significant developmental alteration in the maturation of the trisomic brain and suggest future avenues for defining the effect of increased gene dosage of MMU 16 in the CNS.

Acetylcholine↗

Autoantibody to liver-specific lipoprotein in the mouse: regulation by naturally occurring autoantigen specific suppressor cells.

Indirect and direct evidence is presented that normal, non-immune mice have cells which suppress antibody production to murine liver specific lipoprotein (LSP) autoantigens with little or no effect on the response to a closely related foreign antigen complex, rabbit LSP. Suppressor control mechanisms were suggested in low responder BALB/c mice which produced LSP autoantibody only after exposure to low dose X-irradiation or treatment with cyclophosphamide. Adoptive transfer experiments in X-irradiated BALB/c mice and untreated C57BL/6 mice showed that cells from normal mouse spleen prevented LSP autoantibody production when put into the circulation of mice prior to immunization with foreign rabbit LSP. This suppressor activity was destroyed by treatment with antisera to T cells and by low dose X-irradiation. The normal spleen cells were ineffective as suppressors if given after primary immunization with rabbit LSP had commenced. It is suggested that the adoptive transfer of normal spleen cells prior to immunization with foreign LSP supplements homeostatic mechanisms in favour of tolerance to LSP autoantigen. It is argued that the LSP autoantibody response in the mouse is a unique model for the study of autoantigen specific naturally occurring suppression.

Animals↗