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Biomedical subjects

E Sim

Publications and source records attributed to E Sim.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Comparison of the value of magnetic resonance tomography and computerized tomography in the follow-up of augmentation-plasties with carbon fiber ligaments of the anterior cruciate ligament].

17 patients--treated with unidirectional carbon-fibre-ligaments augmentation for the anterior cruciate ligament--have been followed-up by MRI and CT. The question has been, whether both methods show comparable results. The interval between operation and follow-up has been 34 months in average (43 to 30). Significance was put on the probants bedding. MR-Imaging in two planes seems to be essential to show the artificial ligament's integrity in its extraarticular "over the top"-position. Satisfying corresponding results could be found in MRI and CT.

Adolescent↗
PubMed1988

Metabolites of procainamide and practolol inhibit complement components C3 and C4.

Drug-induced systemic lupus erythematosus arises from toxic side-effects of administration of hydralazine, isoniazid, procainamide and practolol. Hydralazine and isoniazid are nucleophilic drugs and inhibit the covalent binding reaction of complement components, C3 and C4, an effect likely to lead to deposition of immune complexes (a feature of systemic lupus erythematosus). Procainamide and practolol do not themselves inhibit C3 and C4. A range of metabolites and putative metabolites of procainamide and practolol were synthesized, and tested for their ability to inhibit the covalent binding reactions of C3 and C4. The highly nucleophilic hydroxylamine metabolite of procainamide was strongly inhibitory in both tests, as was a putative hydroxylamine metabolite of practolol. These studies indicate a potential role for the hydroxylamine metabolites in mediating the toxic side-effects of procainamide and practolol, and emphasize the need for adequate measurements of hydroxylamine metabolites in human tissue.

Acecainide↗
PubMed1988

Interaction of nucleophilic compounds with complement component C4.

Drugs which induce systemic lupus erythematosus as a toxic side effect have been shown to inhibit the covalent binding of C4, which is an important event in immune complex clearance in normal individuals. Human C4 is encoded at two polymorphic loci, C4A and C4B within the Major Histocompatibility Complex and patients with idiopathic SLE are more likely to have a non-functional (null) C4A gene. The C4A and C4B gene products differ in reactivity with C4A being more reactive with nitrogen nucleophiles, including hydralazine and isoniazid (drugs which induce SLE), than with oxygen nucleophiles. We have established an assay system which allows the effect of nucleophiles on C4 in animal sera to be investigated. It has been found that in comparing reactivity of guinea-pig C4 with human C4A and human C4B that guinea-pig C4 is like human C4A and shows greater reactivity towards nitrogen nucleophiles than towards oxygen nucleophiles. This suggests that the guinea-pig should be a good animal model for drug-induced SLE.

Animals↗
PubMed1988

The effect of indication on the risk of hypersensitivity reactions associated with tolmetin sodium vs other nonsteroidal antiinflammatory drugs.

A retrospective cohort study using 1980-1984 Medicaid billing data from 3 US states was performed to assess the relative risk of hypersensitivity reactions from different nonsteroidal antiinflammatory drugs (NSAID). Comparing tolmetin sodium to other NSAID, pooling the data across the 3 US states using the Mantel-Haenszel procedure, gave an overall relative risk (95% confidence interval) of 1.1 (0.8-1.4). After adjusting for multiple potential confounding variables using logistic regression, an odds ratio (95% confidence interval) of 0.9 (0.6-1.2) was observed. These data do not confirm previous suggestions that use of tolmetin is associated with a higher risk of hypersensitivity reactions than use of other NSAID.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1987

Transcutaneous oxygen monitoring and retinopathy of prematurity.

This study was performed to determine whether the use of continuous tcPO2 monitoring could reduce the incidence of ROP in preterm infants receiving oxygen therapy. Two hundred and ninety-six infants with birth weights less than or equal to 1300 grams were randomly assigned to a continuous monitoring (CM) or a standard care (SC) group. CM infants had tcPO2 monitored continuously as long as they required supplemental oxygen while SC infants had tcPO2 monitored only during the more acute state of their illness. Management of both groups was otherwise identical. One hundred and one of 148 infants in the CM and 113 of 148 patients in the SC groups survived. Mean birth weights and gestational age were similar in both groups. Duration of mechanical ventilation and oxygen therapy was also similar. The overall incidence of ROP was 51% in the CM and 59% in the SC group. As birth weight for infants greater than or equal to 1000 grams increased a higher risk for developing ROP was noted in the SC group. Four infants in the CM and 5 in the SC group developed cicatricial ROP. These results suggest that continuous tcPO2 monitoring may reduce the incidence of ROP in infants with birth weights greater than 1000 grams, but not in the smaller infants in whom this complication occurs more frequently and is more severe.

Birth Weight↗
PubMed1987

Retinopathy of prematurity. A randomized, prospective trial of transcutaneous oxygen monitoring.

To determine whether the use of continuous transcutaneous oxygen monitoring (tcPO2) could reduce the incidence of retinopathy of prematurity (ROP) in pre-term infants receiving oxygen therapy, a randomized, prospective trial of constant monitoring using the transcutaneous oxygen monitor versus intermittent monitoring of oxygen was performed on a population of premature infants at very high risk for the development of ROP. Two hundred ninety-six infants were randomly assigned to either a constantly monitored (CM) or standard care (SC) group. CM infants had tcPO2 monitored continuously as long as they required supplemental oxygen, whereas SC infants had tcPO2 monitored only during the more acute state of their illness. Management of both groups was otherwise identical. One hundred one of 148 infants in the CM group and 113 of 148 in the SC group survived. The overall incidence of ROP was 51% in the CM group and 59% in the SC group (no significant difference). In infants over 1000 g birthweight, as the weight increased there was increasing risk of developing ROP in the SC group. The odds ratio for the ROPsc:ROPcm reached 7.6 in infants between 1200 and 1300 g in infants with Apgar scores greater than or equal to 8 at 5 minutes. The incidence of cicatricial ROP was similar in both groups: four in the CM and five in the SC group.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Erythrocyte complement receptor type 1 (CR1) expression and circulating immune complex (CIC) levels in hydralazine-induced SLE.

Family studies were carried out to look at CR1 expression in 24 hydralazine-induced SLE patients (Hz Reactors), who had been off the drug for at least 1 year and were clinically well at the time of the study. Mean expression of CR1 was reduced by 27% in the group of hypertensives who had developed Hz-induced SLE compared with a group of 35 normal individuals. CR1 expression was also slightly reduced in the relatives of the Hz Reactors compared to the normal group. Using a solid-phase Clq binding assay, CIC levels were found to be elevated in the plasma of the Hz reactors and an inverse relationship was found between CR1 levels and CIC levels in this patient group. Both CR1 levels and CIC levels in Hz Reactors and normal individuals were constant over the 36 weeks studied. This study suggests that there is an association between an inability to deal efficiently with CIC and susceptibility to developing Hz-induced SLE.

Antigen-Antibody Complex↗
PubMed1987

Upper gastrointestinal tract bleeding from oral potassium chloride. Comparative risk from microencapsulated vs wax-matrix formulations.

A retrospective cohort study was performed to assess the relative risk of upper gastrointestinal (UGI) tract bleeding from two formulations of potassium chloride. Relevant information was obtained from 1980 through 1984 Medicaid billing data from the states of Michigan, Minnesota, Florida, and Ohio. After patients with a history of UGI tract bleeding prior to their first prescription for either of the two potassium chloride preparations under study were excluded, data were analyzed for 28,790 patients (143,512 patient-months) dispensed a microencapsulated formulation exclusively and 76,118 patients (560,341 patient-months) dispensed a wax-matrix formulation exclusively. The risk of UGI tract bleeding within 30 days after each prescription for the drug of interest was examined. After sampling from the undiseased study subjects and adjusting for multiple potential confounding variables using logistic regression, an odds ratio (95% confidence interval) of 0.67 (0.52 to 0.85) was observed.

Administration, Oral↗
PubMed1987

Influence of transcutaneous oxygen monitoring on the incidence of retinopathy of prematurity.

This study was performed to determine whether the use of continuous transcutaneous oxygen tension (tcPO2) monitoring could reduce the incidence of retinopathy of prematurity in preterm infants receiving oxygen therapy. A total of 296 infants with birth weights less than or equal to 1,300 g were randomly assigned to a continuous monitoring or a standard care group. Infants in the continuous monitoring group had tcPO2 monitored continuously as long as they required supplemental oxygen, and infants in the standard care group had tcPO2 monitored only during the more acute state of their illness. Management of both groups was otherwise identical. Of 148 infants in the continuous monitoring group, 101 survived; of the 148 patients in the standard care group, 113 survived. Mean birth weights and gestational ages were similar for both groups. Duration of mechanical ventilation and oxygen therapy was also similar. The overall incidence of retinopathy of prematurity was 51% in the continuous monitoring group and 59% in the standard care group. As birth weight for infants greater than or equal to 1,000 g increased, a higher risk of retinopathy of prematurity developing was noted in the standard care group. Cicatricial retinopathy of prematurity developed in four infants in the continuous monitoring group and five in the standard care group. These results suggest that continuous tcPO2 monitoring may reduce the incidence of retinopathy of prematurity in infants with birth weights greater than 1,000 g but not in the smaller infants in whom this complication occurs more frequently and is more severe.

Birth Weight↗
PubMed1986

Phenotyping of human complement component C4, a class-III HLA antigen.

The plasma complement protein C4 is encoded at two highly polymorphic loci, A and B, within the class-III region of the major histocompatibility complex. At least 34 different polymorphic variants of human C4 have been identified, including non-expressed or 'null' alleles. The main method of identification of C4 polymorphic allotypes is separation on the basis of charge by agarose-gel electrophoresis of plasma. On staining by immunofixation with anti-C4 antibodies, each C4 type gives three major bands, but, since individuals can have up to five allotypes, the overlapping banding pattern is difficult to interpret. We show that digestion of plasma samples with carboxypeptidase B, which removes C-terminal basic amino acids, before electrophoresis, produces a single, sharp, distinct band for each allotype and allows identification of the biochemical basis of the multiple banding pattern previously observed in C4 phenotype determination.

Carboxypeptidase B↗
PubMed1985

The generation of active fragments of complement receptor type 2 by trypsin digestion.

B lymphocytes and Raji cells express the complement receptor type 2 (CR2) of 145 kDa which recognises the C3d fragment of C3. When intact cells are treated with trypsin, CR2 is degraded. There is a parallel loss in C3d-mediated rosetting and in proteins which bind to C3d-Sepharose. Initially 97 and then 83 kDa fragments of CR2 are produced which retain C3d binding activity. These fragments are associated with the cell surface and mediate rosetting. Purified 125I-labelled CR2, solubilised in detergent, produces fragments of apparently identical size on treatment with trypsin. The 83 kDa fragment produced by trypsin treatment closely resembles the major C3d binding protein spontaneously released into Raji cell culture medium.

B-Lymphocytes↗
PubMed1985

Hydralazine binds covalently to complement component C4. Different reactivity of C4A and C4B gene products.

Long-term treatment with hydralazine is sometimes associated with deposition of immune complexes and development of systemic lupus erythematosus (SLE) as an adverse side-effect. Hydralazine inhibits the covalent binding reaction of the complement protein C4. We show that when hydralazine inhibits C4, it becomes covalently bound to the polypeptide chain containing the active site thiol ester. C4 is encoded at 2 adjacent polymorphic loci, C4A and C4B, within the major histocompatibility complex. We show that hydralazine binds more efficiently to the C4A than to the C4B gene product and suggest that C4 type may predispose patients to hydralazine-induced SLE.

Complement C4↗
PubMed1984

Analysis of C3-receptor activity on human B-lymphocytes and isolation of the complement receptor type 2 (CR2).

The rosetting of defined C3-fragment-coated sheep erythrocytes to B-cell-enriched tonsil lymphocytes was measured. The rosetting lymphocytes were homogeneous with respect to expression of C3b, iC3b and C3d receptors. Isolation of receptors for C3 fragments from surface-radioiodinated lymphocytes by affinity chromatography on immobilized C3u, iC3b and C3d,g produced two proteins with partially overlapping specificities. A protein of 240 000 Mr, recognized by the monoclonal antibody To5 and identified as CR1 (complement receptor type 1), had affinity for C3u and iC3b. A protein of 145 000 Mr, recognized by the monoclonal antibody B2, had affinity for all three C3 fragments. Inhibition of rosetting by antibodies to these proteins indicates that CR1 is responsible for C3b-mediated rosetting and that the 145000-Mr receptor (CR2) is responsible for C3d-mediated rosetting. Partial inhibition by both anti-CR1 and anti-CR2 antibodies of iC3b-mediated rosetting indicates that both receptors are involved in iC3b-mediated rosetting. No other protein appears to be involved in tonsil B-cell rosetting to C3-fragment-coated cells. A method for preparing CR2 from tonsil lymphocytes based on affinity chromatography on C3d,g-Sepharose has been developed. Forty tonsil pairs (2 X 10(10) B-cells) yield about 40 micrograms of pure protein equivalent to a purification of 6500-fold from a detergent extract.

Antibodies↗
PubMed1984

Drugs that induce systemic lupus erythematosus inhibit complement component C4.

The syndrome resembling systemic lupus erythematosus (SLE) associated with long-term treatment with hydralazine and isoniazid seems to be due to the drugs themselves rather than their metabolites. This syndrome is associated with deposition of immune complexes; and in the complement system inhibition of C4 is likely to increase deposition of immune complexes. In vitro, hydralazine and isoniazid inhibited 50% of the binding of C4 at 840 mumol/l and 1.05 mmol/l, respectively--ie, within the concentration ranges that have been used in therapy. Acetylated metabolites were not inhibitory at the maximum concentrations tested; and iproniazid, which does not cause SLE, gave 50% inhibition only at a concentration far exceeding that used in therapy.

Acetylation↗