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Biomedical subjects

D Carson

Publications and source records attributed to D Carson.

At least 91 records · Page 5Linked to original sources
PubMed1984

The immune response to Epstein-Barr nuclear antigen: conformational and structural features of antibody binding to synthetic peptides.

Naturally developing human antibodies to the Epstein-Barr nuclear antigen recognize synthetic peptides containing sequences from the unusual glycine-alanine region of this protein. We tested antibody binding to a series of peptides of from five to 20 amino acids in length. Peptides as small as seven amino acids could bind but optimal results required chain lengths of 15. Binding was extremely sensitive to small changes in the length and sequence of the peptide, and also to the temp of the reaction. The changes can be ascribed to two factors: (1) deletion of the site of antigen binding and (2) loss of peptide secondary structure.

Amino Acid Sequence↗
PubMed1984

Perceptions of childhood diarrhoea and its treatment in rural Zimbabwe.

In the course of a study on the acceptability and feasibility of home-based oral rehydration therapy in rural Zimbabwe, information was collected on attitudes and beliefs about diarrhoea and on action taken in response to an episode of diarrhoea in a child. Diarrhoea was found to be a perceived threat at community and family level and numerous possible causes of diarrhoea were described which were assigned to two broad classes: (1) 'physical' causes, such as a polluted environment, diet and teething and (2) 'social and spiritual' causes such as those associated with a depressed fontanelle. These domains were not, however, mutually exclusive; 76% of the described episodes of diarrhoea were attributed to 'physical' causes, 15% to 'social and spiritual' causes and 8% to a combination of both. Reported utilization rates of the formal health services were unexpectedly high. In contrast, we recorded a low demand for indigenous herbalists (n'angas). Home management was common and comprised the administration of indigenous herbal remedies, of sugar and salt solutions, of over-the-counter drugs or of enemas. These remedies were given on their own or alongside the treatment prescribed by a health worker. A number of variables were examined to assess their influence on health-seeking behaviour: perceived cause and severity of the illness, socio-demographic characteristics of the respondent or child and accessibility of the health services.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Automatic and expectancy-based priming effects in a digit naming task.

In a voice reaction time task, subjects named target digits that were horizontally flanked by noise digits or by a neutral symbol (#). For the control subjects, the noise digits were uncorrelated with the target digit, whereas for three experimental groups, the value of the noise digit predicted the target digit by an arithmetic rule (target = noise, target = noise + 1, target = noise - 1) on 75% of the trials. Patterns of reaction time facilitation and inhibition relative to the control condition among the four subject groups illustrated differing time courses of involuntary and expectancy-based priming. For prediction rules requiring an arithmetic transformation (expect N = 1 and expect N - 1), responses to predicted targets were slowed by response competition at short stimulus-onset asynchrony (SOAs) but greatly facilitated by expectancy at longer SOAs.

Adult↗
PubMed1983

Environmental effects on urinary volumes, biochemical constituents and their inter-relation.

This study has found low 24-h urine volumes in British expatriates in Saudi Arabia and suggests the possibility of urate stone formation in spite of the air-conditioned environment in which they were living. Urine volume was shown to be significantly correlated with calcium excretion in both sexes and to urate and sodium in males. Differences in 24-h urine concentrations of some but not all constituents between British-born subjects living in Britain and Saudi Arabia have been demonstrated.

Adult↗
PubMed1983

Transplantation of T-lymphocyte-depleted bone marrow between HLA-mismatched individuals.

Four patients with acute leukemia received transplants from HLA-mismatched, related donors. Marrow cells that had been depleted of T lymphocytes using a monoclonal anti-T-lymphocyte antibody and rabbit complement were used. In vitro studies showed that 80-97% of the mature T lymphocytes were removed using this procedure. Infusion of the treated marrow was accomplished without complications, and engraftment occurred in each case. Graft-versus-host disease occurred in 3 of the 4 patients. These results show that additional manipulations of the marrow will be required to allow complete T lymphocyte removal from the marrow before the feasibility of this approach in HLA-mismatched patients can be determined.

Acute Disease↗
PubMed1983

Metabolic compensation for profound erythrocyte adenylate kinase deficiency. A hereditary enzyme defect without hemolytic anemia.

A child with hemolytic anemia was found to have severe erythrocyte adenylate kinase (AK) deficiency, but an equally enzyme-deficient sibling had no evidence of hemolysis. No residual enzyme activity was found in erythrocytes by spectrophotometric methods that could easily have detected 0.1% of normal activity. However, concentrated hemolysates were shown to have the capacity to generate small amounts of ATP and AMP from ADP after prolonged incubation. Hemolysates could also catalyze the transfer of labeled gamma-phosphate from ATP to ADP. Intact erythrocytes were able to transfer phosphate from the gamma-position of ATP to the beta-position, albeit at a rate substantially slower than normal. They could also incorporate 14C-labeled adenine into ADP and ATP. Thus, a small amount of residual AK-like activity representing about 1/2,000 of the activity normally present could be documented in the deficient erythrocytes. The residual activity was not inhibited by N-ethylmaleimide, which completely abolishes the activity of the normal AK1 isozyme of erythrocytes. The minute amount of residual activity in erythrocytes could represent a small amount of the AK2 isozyme, which has not been thought to be present in erythrocytes, or the activity of erythrocyte guanylate kinase with AMP substituting as substrate for GMP. Peripheral blood leukocytes, cultured skin fibroblasts, and transformed lymphoblasts from the deficient subject manifested about 17, 24, and 74%, respectively, of the activity of the concurrent controls. This residual activity is consistent with the existence of genetically independent AK isozyme, AK2, which is known to exist in these tissues. The cause of hemolysis in the proband was not identified. Possibilities include an unrelated enzyme deficiency or other erythrocyte enzyme defect and intraction of another unidentified defect with AK deficiency.

Adenine↗
PubMed1983

Increased frequency of rheumatoid factor precursor B lymphocytes after immunization of normal adults with tetanus toxoid.

Vaccination of normal adults with tetanus toxoid induced a two-three-fold rise in the frequency of IgM anti-IgG (rheumatoid factor, RF) B lymphocytes inducible by the polyclonal B cell activator, Epstein-Barr virus. The increase in IgM-RF precursors occurred earlier, was greater in magnitude, and was more sustained than the change in plasma IgM-RF. It was associated with a rise in total IgM levels, and correlated positively with the magnitude of the IgG anti-tetanus antibody response, but not with levels of circulating immune complexes. The ability of apparently innocuous infections and immunizations to increase the frequency of IgM-RF precursor B lymphocytes may be the reason for the previously noted expansion in this autoreactive B cell pool between birth and adulthood.

Adult↗
PubMed1982

A comparison of terbutaline and ethanol in the treatment of preterm labor.

Ninety-two women in preterm labor were randomly assigned to either terbutaline or ethanol. In women with intact membranes, terbutaline was significantly more effective than ethanol in preventing progressive cervical dilation during the first 36 hours of treatment while betamethasone was given to the mother. Additionally, pregnancy was maintained significantly longer in women with intact membranes who were treated with terbutaline (15 +/- 4 days) rather than with ethanol (10 +/- 3 days). However, only 18% of women in each treatment group maintained their pregnancy beyond 36 weeks' gestation. In women with ruptured membranes and cervical dilation less than 4 cm, terbutaline was significantly better than ethanol in maintaining pregnancy for a minimum of 36 hours. Serious maternal side effects were not observed with terbutaline or ethanol, although a majority of women also received betamethasone. Neither drug caused serious adverse neonatal effects.

Apgar Score↗
PubMed1979

Effect of growth rate on lipid and lipoteichoic acid composition in Streptococcus faecium.

The lipid composition of Streptococcus faecium (S. faecalis ATCC 9790) was analyzed at various growth rates. Diphosphatidylglycerol and the non-ionic lipid fraction containing diacylglycerols and neutral glycolipids appeared to accumulate relative to cellular mass as the culture mass doubling time increased from 30 to 80 min. Within the same range of doubling times the non-ionic lipid fraction appeared to become substantially enriched with diacylglycerols. All lipid species and cellular lipoteichoic acid accumulated relative to the cellular mass at doubling times exceeding 80 min, although diacylglycerol accumulation exceeded that of all other compounds studied.

Enterococcus faecalis↗
PubMed1979

Effects of cerulenin on antibiotic-induced lysis of streptococcus faecalis (S. faecium).

Addition of the antibiotic cerulenin to cultures lowered the minimal effective concentration of penicillin G or methicillin required to produce bacterial lysis and killing. This effect was most pronounced at subinhibitory antibiotic concentrations. Cerulenin had no significant effects on lysis or killing induced in the presence of D-cycloserine, fosfomycin, bacitracin, or vancomycin.

Anti-Bacterial Agents↗
PubMed1978

Effect of cerulenin on Streptococcus faecalis macromolecular synthesis and cell division.

The antibiotic cerulenin has been used to study macromolecular synthesis and cell division in Streptococcus faecalis. The data suggest that lipid and lipoteichoic acid synthesis as well as cell number increase are affected prior to any observable effects on overall mass increase or DNA, RNA, protein, or peptidoglycan synthesis. Treatment with cerulenin of cultures growing at various rates and analysis of the subsequent cell divisions indicate that the antibiotic may block a cell cycle event that precedes the completion of chromosome replication by about 10 min.

Antifungal Agents↗
PubMed1975

Serum IgE levels during the potentiated reagin response to egg albumin in rats infected with Nippostrongylus brasiliensis.

Rats were immunized with 10 mug EA and alum; a low titer IgE anti-EA response was observed; subsequent infection with N. brasiliensis greatly potentiated this response. Serum from these rats was tested for its IgE content by a recently developed radioimmunoassay for rat IgE. The average serum level of IgE was 1.15 mug/ml; this level was not altered by immunization, but infection with N. brasiliensis was accompanied by an 80-fold increase in concentration of serum IgE. This increase could not be accounted for by IgE anti-EA or anti-worm antibodies. Infection with N. brasiliensis appears to have an adjuvant effect on IgE antibody responses to diverse environmental antigens as well as the experimentally induced IgE anti-EA response.

Adsorption↗
PubMed1974

Immunochemical analysis of the idiotypes of mouse myeloma proteins with specificity for levan or dextran.

This paper deals solely with idiotypic determinants, the configurations of which are modified when the antibody bearing them interacts with its ligand. This phenomenon is measured as an inhibition of the reaction between anti-idiotype and idiotype. Two points are made: (a) The assay for ligand-modifiable determinants can be used to determine the "size" of the combining site. This is illustrated here with the anti-alpha(1 --> 6) dextran mouse myeloma immunoglobulin W3129. Whether the interaction between a homologous series of alpha(1 --> 6) oligosaccharide ligands and the combining site of W3129 is measured by inhibition of precipitation with alpha(1 --> 6) dextran (4) or of binding of W3129 to anti-W3129 idiotype, the finding is the same. The order of inhibition is isomaltohexaose = isomaltopentaose >> isomaltotetraose > isomaltotriose >>> isomaltose. The combining site is optimally complementary to isomaltopentaose. (b) Cross-idiotypic specificity is closely correlated with cross-combining specificity; the converse is not true. This is illustrated here with three groups of mouse myeloma immunoglobulin, each specific for alpha(1 --> 3) dextran, alpha(1 -->6) dextran, beta(2 --> 1) or beta(2 --> 6) levan. If a given anti-idiotypic serum cross-reacted with several myeloma proteins, they always had similar combining specificity. Thus the three proteins, J558, MOPC 104E, and UPC 102, which cross-react with anti-J558 have combining specificity for alpha(1 --> 3) dextran; cross-reacting W3082, UPC 61, and Y5476 have specificity for levan; and cross-reacting W3129 and W3434 have specificity for alpha(1 --> 6) dextran. This extends previous studies with proteins specific for phosphorylcholine (7) or gamma-globulin (8). As expected, the converse is not true, for proteins may have combining specificity for alpha(1 --> 6) dextran e.g. QUPC 52, or levan e.g. J606, UPC 10 and yet not carry the above-mentioned reference idiotypes. The correlation between cross-idiotypic and combining specificity breaks down when idiotypic determinants which are not modifiable by ligand are studied. The implications of this are pointed out since most investigations deal with ligand-nonmodifiable determinants.

Animals↗