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Biomedical subjects

B Clark

Publications and source records attributed to B Clark.

At least 127 records · Page 7Linked to original sources
PubMed1983

beta 2 microglobulin plasma levels reflect disease activity in rheumatoid arthritis.

Elevated plasma levels of beta 2 microglobulin have been described in rheumatoid arthritis (RA) but their relationship to disease activity is unclear. In patients treated for 6 months with auranofin (AF) there was a significant fall (p less than 0.05) in beta 2M levels pari passu with improvement in disease activity as measured by a fall in C-reactive protein. In addition, 26 patients with mild RA had beta 2M levels within the normal range. It is concluded that beta 2M plasma levels reflect disease activity in RA.

Anti-Inflammatory Agents↗
PubMed1982

A Canadian community mental health program: a clerkship experience.

The authors describe a consultation-liaison relationship between a community psychiatry outpatient service and private community family practitioners, including some problems and solutions that have arisen as a result of this relationship. A medical student clerkship in this consultation-liaison setting is particularly useful in orienting students to community aspects of psychiatric care in primary care practice. Since 50% of medical students from McMaster University enter some form of primary care activity, this exposure and sensitization to community mental health activities is especially relevant.

Community Mental Health Services↗
PubMed1982

Studies on paracetamol-induced lipid peroxidation.

Post-mitochondrial supernatants isolated from livers of rats given a single large oral dose of paracetamol (800 mg/kg) showed rapid rates of lipid peroxidation when incubated in vitro. As a result of paracetamol administration the level of reduced glutathione (GSH) declined to approx. 20-25% of the peak physiological value. Addition of reduced GSH to the supernatant inhibited the peroxidation. Paracetamol-induced lipid peroxidation was inhibited in vitro by antioxidants (e.g. vitamin E) but was unaffected by superoxide dismutase and mannitol. N-acetyl cysteine and cysteamine inhibited lipid peroxidation in vitro in a cytosol-dependent manner in the absence of glutathione. Lipid peroxidation probably occurs simultaneously with the proposed covalent binding of the active metabolite of paracetamol. Since the former process is known to cause severe and extensive membrane damage, it may be a very important factor in paracetamol-induced liver necrosis.

Acetaminophen↗
PubMed1982

A monoclonal antibody recognizing a determinant common to HLA-A3 and A11.

Spleen cells from a mouse immunized with an AML cell expressing HLA-A3 produced a hybridoma secreting an anti-HLA-A3, A11 monoclonal antibody, 26D3. By complement-dependent cytotoxicity at dilutions to 1:10(4) the ascites antibody lysed 13/13 A3, 15/15 A11, and 8 other lymphocytes from a panel of 98 donors. The 26 D3 immunoprecipitated a molecule consisting of subunits of 44,000 and 12,000 daltons. Monoclonality of the antibody was demonstrated by isoelectric focusing and protein A affinity chromatography.

Animals↗
PubMed1982

Beta adrenergic receptors in pigmented ciliary processes.

Beta adrenergic receptors from membrane fragments of pigmented sheep eyes were studied and characterised by ligand binding techniques after the removal of melanin. In a representative experiment the beta max (total number of beta receptors) was 394.9 fmol/mg protein. The receptor affinity (Ka) was 440 pM. The potency series of drugs to displace 125I-HYP from the receptors was timolol = (-) propranolol greater than (+) propranolol greater than salbutamol greater than practolol. beta 1 Receptors were not detected in the ciliary processes. beta 2 Receptors were the prominent adrenergic receptors present. The theory as to how beta blockers work in glaucoma, their site of action, and the potential role of beta 2 blockers for use in intraocular pressure control is discussed.

Albuterol↗
PubMed1982

Metabolism and excretion of a chromone carboxylic acid (FPL 52757) in various animal species.

1. The disposition of the chromone carboxylic acid (FPL 52757) in several species has been investigated. The compound is extensively metabolized by hydroxylation in rat, mouse, ferret, squirrel monkey, cynomolgus monkey, rabbit, hamster, stumped-tailed macaque and baboon (e.g. 50-100% in rat, cynomolgus monkey and squirrel monkey). 2. The plasma clearance of the chromone in rat, rabbit and squirrel monkey was 138, 44 and 59 ml/kg per h respectively. Plasma clearance by the dog was slower (13 ml/kg per h) and due mainly to elimination of unchanged compound. 3. As the dog is particularly susceptible to FPL 52757-induced hepatotoxicity the parent compound may be responsible. Species which clear the compound rapidly compared with the dog did not show a hepatotoxic response. 4. Although metabolism occurs in man the clearance is still slow (15 ml/kg per h) and may be one reason for human susceptibility to a mild hepatotoxic effect with the compound.

Animals↗
PubMed1982

The mechanism of hepatotoxicity of a chromone carboxylic acid (FPL 52757) in the dog.

1. The chromone carboxylic acid (6,8-diethyl-5-hydroxy-4-oxo-4H-1-benzopyran-2-carboxylic acid) is hepatotoxic in dogs (at 40 mg/kg per day). This toxicity did not appear to be mediated by a reactive metabolite, as the compound was not metabolized by the dog, and phenobarbitone pretreatment (20 mg/kg per day) protected rather than potentiated. 2. Other studies in the dog showed that the chromone caused increases in the biliary excretion of alkaline phosphatase (17-fold), gamma-glutamyl-transpeptidase (9-fold), and 5'-nucleotidase (13-fold) which paralleled the biliary concentration of the drug (up to 1.3 mg/ml) and was accompanied by a reduction in bile flow. 3. The excretion of the chromone into the biliary tract of the dog was shown to be saturable, and therefore high hepatocellular concentrations of the drug and subsequent liver damage could result. 4. The toxicity of the chromone when administered to rat by retrograde biliary infusion, and the lysis of erythrocytes in vitro, are related to detergent properties of the drug and add confirmatory evidence for a mechanism of toxicity in the dog. 5. It is concluded that the chromone itself is responsible for the toxicity in the dog due to its detergent properties causing damage to the hepatobiliary tract. The protection by phenobarbitone and also by methionine may have been due to an increased bile flow reducing biliary concentrations.

Animals↗
PubMed1982

Prediction of IQ and language skill from perinatal status, child performance, family characteristics, and mother-infant interaction.

193 basically healthy working-class and middle-class mothers and their infants participated in a 4-year longitudinal study which focused on the relative potency of several clusters of variables for predictions of intellectual and language outcome during the preschool years. The major results were: (1) Measures of perinatal or infant physical status were extremely weak predictors of 4-year IQ or language. (2) Assessments of child performance were poor predictors prior to 24 months, but excellent predictors from 24 months on. (3) Assessments of mother-infant interaction and general environmental quality were among the best predictors at each age tested, and were as good as measures of child performance at 24 and 36 months in predicting IQ and language. (4) Measures of the family ecology (level of stress, social support, maternal education) and parent perception of the child, especially when assessed at birth, were strongly related to child IQ and language within a low-education subsample, but not among mothers with more than high school education. Patterns of prediction were similar for 48-month IQ and 36-month receptive language; predictions were notably weaker for 36-month expressive language.

Child Development↗
PubMed1981

Adenocarcinoma of the sweat gland of the vulva: light and electron microscopic study.

A sweat gland carcinoma, a rare tumor of the skin which arose in the posterior fourchette in a 53-year-old white woman, was studied by light and electron microscopy. The tumor formed cords or small acini infiltrating into the stroma with foci of Pagetoid appearance. The cells showed poor intercellular cohesions. PAS and mucin strains were negative. Ultrastructurally the tumor cells in the periphery of the acini were firmly attached to the collagenous matrix with a few pseudopodia. A basal lamina was seen in some areas. The cytoplasm was filled with many ribosomes and moderately developed mitochondria. The bundles of microfilaments in the perinuclear zone were characteristic findings in this tumor. The ultrastructure of this tumor confirmed that this was carcinoma of the sweat gland, which closely resembled intraductal carcinoma of the breast.

Adenocarcinoma↗
PubMed1981

Immunoglobulin concentrations in the duodenal fluids of infants and children. II. The effect of pancreozymin and secretin.

A study was conducted to determine whether pancreozymin and secretin affect the levels of immunoglobulins in duodenal fluid of children. The subjects consisted of 45 infants and children without gastrointestinal disease. Ig-A concentrations in duodenal fluid were significantly increased (P less than 0.02) after secretion administration (2 U./kg) as compared to resting fluid levels (18.3 +/- 0.8 vs. 12.9 +/- 1.1 mg./gm. protein). Secretin also produced a significant increase (P less than 0.0002) in Ig-M duodenal fluid levels (25.5 +/- 3.6 vs. 13.8 +/- 1.4 mg./gm. protein). Duodenal fluid Ig-G concentrations were not significantly changed in response to secretin (30.7 +/- 2.3 vs. 29.1 +/- 1.2 mg./gm. protein) or to pancreozymin (29.0 +/- 0.8 mg./gm. protein). Pancreozymin administration (2 U./kg) produced a significant decrease (P less than 0.01) in Ig-A concentration (11.2 +/- 0.8 mg./gm. protein) and a significant increase (P less than .0002) in the Ig-M levels of human duodenal fluid (20.8 +/- 1.8 mg./gm. protein).

Adolescent↗
PubMed1980

Characterization of three different human T cell membrane antigens, two being present on T lymphocyte subpopulations.

Heteroantisera were raised in rabbits to thymocytes, HSB2 cells, and Sezary cells. Following absorption with Ia-positive leukemia cells, these sera appeared to be specific for different T cell antigens. Both the anti-HSB2 and the anti-Sezary sera reacted with approximately 50% and the antithymocyte serum with 100% of normal peripheral blood T lymphocytes. None of the sera reacted with B cells. The apparent molecular weights of the antigens being detected were determined by immunoprecipitation followed by SDS polyacrylamide gel electrophoresis. A dimer of 170,000 daltons consisting of two similar 85,000-dalton polypeptide chains was immunoprecipitated by the anti-HSB2 serum whereas single polypeptides of 53,000 and 64,000 daltons were immunoprecipitated by the anti-Sezary and antithymocyte sera, respectively.

Animals↗
PubMed1980

Thresholds for detection of constant rotary acceleration during vibratory rotary acceleration.

The effects of vibratory angular acceleration (aR) on detection thresholds for constant aR in a dynamic flight simulator are reported in three experiments. Detection thresholds were determined for 10 pilots and four nonpilots using a random, double-staircase procedure while the subjects sat erect in a device which rotated about an earth-vertical axis. Constant aRs were presented for 0.5 and 1.0 s with concurrent, vibratory aR at 1 and 5 Hz, and thresholds with no vibratory aR were established. The thresholds were obtained while the subjects observed a visual reference in the enclosed cockpit in two experiments and in total darkness in a third. The results confirmed earlier experiments showing an inverse relationship between the duration of constant aR and detection threshold and showed that the detection thresholds in darkness were higher than with a visual reference present. Two analyses of variance revealed no significant differences in thresholds across the three vibration conditions. These results indicate that vibratory aRs of fairly high levels can be present in a dynamic flight stimulator without masking the pilot's ability to detect either maneuver or disturbance motions.

Acceleration↗