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Biomedical subjects

M G Scott

Publications and source records attributed to M G Scott.

123 records · Page 7Linked to original sources
PubMed1985

Inaccurate values for direct bilirubin with some commonly used direct bilirubin procedures.

We compared five methods for the determination of total and direct bilirubins in serum samples from normal controls, subjects with Gilbert's syndrome, and serum pools containing about 50 and 150 mg of total bilirubin per liter. The Kodak Ektachem method and a diazotized sulfanilic acid method with 0.15 mmol/L sodium nitrite concentrations are the only methods that gave accurate direct bilirubin values, as judged by liquid-chromatographic results. The aca method that involved p-nitrobenzene diazonium tetrafluoroborate and another diazotized sulfanilic acid method with a higher concentration of sodium nitrite (0.8 mmol/L) yielded falsely high values for direct bilirubin, which could lead to clinical confusion. The more recently introduced diazotized sulfanilic acid method of the aca gave substantially better results than the p-nitrobenzene diazonium tetrafluoroborate method but was still inaccurate. Systematic investigation of these procedures revealed that the overestimation of direct bilirubin by the diazotized sulfanilic acid method was related to the amount of unconjugated bilirubin present and its ability to react as direct bilirubin in the presence of higher concentrations of sodium nitrite. Inherent properties of p-nitrobenzene diazonium tetrafluoroborate appeared to be responsible for inaccuracies in that method, which could not be corrected by varying reagent concentration or the reaction conditions.

Adult↗
PubMed1984

Mitogen-induced human IgG subclass expression.

To investigate human isotype expression among lymphocyte populations, we have studied IgG subclass production by splenocytes, tonsil cells, and peripheral blood lymphocytes (PBL) after stimulation with a panel of nine mitogens. Response magnitudes varied with tissues: all mitogens produced the strongest responses with splenocytes and the smallest with PBL. In addition, the IgG subclass maximally stimulated by a particular mitogen also depended on the tissue studied. For example, LPS mainly stimulated IgG2 in PBL and IgG1 in spleen. Interestingly, the response patterns seen in splenocytes suggest a large and coordinate expression of IgG1 and IgG3 subclasses. Implications of these findings are discussed with respect to immunoglobulin gene organization and human disease states.

Antibody Specificity↗
PubMed1984

Effects of azotemia on results of the boronate-agarose affinity and ion-exchange methods for glycated hemoglobin.

We evaluated the effect of azotemia on results for glycated hemoglobin as measured by a boronate-agarose affinity method and an ion-exchange chromatographic procedure with saline preincubation and found a good correlation. However, values for glycated hemoglobin in samples from nondiabetic patients with various degrees of azotemia were consistently higher with the ion-exchange column procedure (mean, 8.5%) than with the boronate affinity method (mean, 6.2%). The latter method may thus be preferred for monitoring glycated hemoglobin in diabetic patients with impaired renal function.

Boronic Acids↗
PubMed1983

A unique DR-related B cell differentiation antigen.

The Ia or class II molecules in both mouse and man are the basis for the genetic control of the immune response. In addition to DR, other class II antigens have been described in man. We describe a new human Ia antigen K19, recognized by three monoclonal antibodies (HK-9, HK-19, and HK-20). This antigen has the general biochemical characteristics of an Ia antigen but is different from a DR antigen. Further, this antigen is found only on mature B lymphocytes and not on monocytes and activated T cells. Thus, this antigen may represent a new Ia-like molecule that is preferentially expressed on mature B cells.

Animals↗
PubMed1982

Preferential idiotype-isotype associations in antibodies to dinitrophenyl antigens.

Murine IgG antibodies to DNP-protein are predominantly IgG1 and IgG2 whereas those against DNP-Ficoll (DNP-F) are mainly IgG3. Isotype restriction in this and other systems may mean that certain heavy chain variable regions (VH) are preferentially associated with particular constant regions (CH) in the immune response. We studied idiotypes of several monoclonal antibodies to DNP in an effort to identify VH regions that may be restricted in this way. Two idiotypes, 7-17 and 8-11, identified on IgG3 hybridomas raised against DNP-Ficoll, were expressed prominently both in immune sera and by IgG3-secreting plaque-forming cells (PFC) against DNP-F. By contrast, these idiotypes were barely detectable in antisera to DNP-proteins and were not expressed by IgG1- or IgG2-secreting PFC. Thus, the 7-17, and 8-11 idiotypes may be restricted to IgG3 and to responses to T-independent DNP antigens. Conversely, the 460 idiotype was expressed prominently in antisera to DNP-proteins but only weakly in antisera to DNP-F. The 460 idiotype was found on IgG1 and IgG2 PFC but not on PFC secreting IgG3. These results suggest that in heterogeneous immune responses to a single antigenic determinant, certain VH regions may be preferentially associated with particular CH isotypes.

Animals↗
PubMed1978

On the structure of the vascular body in the domestic fowl.

The microscopic structure of the vascular body has been described. Three cell types have been identified. The arrangement of blood and lymph vessels has been demonstrated by means of injection techniques, and these vessels have been investigated at an ultrastructural level. The function of the vascular body is discussed.

Animals↗
PubMed1977

Estimation of blood enflurane concentrations by gas-liquid chromatography.

A simple and reliable method for the estimation of enflurane concentrations in whole blood is described. This involves exraction with n-heptane and estimation by gas-liquid chromatography using methoxyflurane as an internal standard. Reproducibility was good and extraction from whole blood was reliable.

Chromatography, Gas↗
PubMed1977

Clinical impressions of enflurane.

Enflurane was used in 150 non-selected patients and was found to be a most satisfactory inhalation anaesthetic. Induction and recovery times were rapid and these characteristics, together with its rather pleasant smell, made it readily acceptable to the patient. Although such features suggest that it would be an ideal agent for children, very high concentrations of enflurane were required to produce adequate anaesthesia in infants and small children. Normal sinus rhythm continued following the injection of adrenaline during enflurane anaesthesia and adequate muscle relaxation was obtained for lower abdominal surgery. The degree of metabolic breakdown of enflurane is considerably less than with other inhalation agents and, if this is reflected in terms of minimal renal and hepatic toxicity, there is every reason to believe that enflurane may be preferable to the volatile anaesthetics currently in use.

Adolescent↗
PubMed1977

Ultrastructural studies on the differentiation of spermatids in the domestic fowl.

Four phases of spermatid maturation are recognized on the basis of nuclear morphology. The formation of the acrosome, perforatorium and axial filament complex are described in relation to these phases. The functional significance of the microtubular systems in nuclear elongation and spermatid curvature are discussed. A membranous structure, hitherto unidentified, and referred to in this study as the 'membrane body' is compared with the chromatoid body. Morphological evidence suggests that this structure, together with the annulate lamellae, removes excessive nuclear material.

Animals↗
PubMedDate not supplied

Chlordiazepoxide metabolite accumulation in liver disease.

Chlordiazepoxide 40mg daily was used to prevent delerium tremens in a 64-year-old female with alcoholic liver disease. After 20 days, the drug was stopped because of the onset of progressive drowsiness. The kinetics of chloridazepoxide were within the predicted range for patients with liver disease, but the elimination half-lives of desmethylchlordiazepoxide and demoxepam were greatly prolonged at 346 hours and 150 hours, respectively. It is suggested that metabolite accumulation may have contributed to the coma, which is an unusual reaction to chlordiazepoxide.

Chlordiazepoxide↗
PubMedDate not supplied

Expression of human IgG subclasses.

Human immunoglobulin G (IgG) can be divided into four subclasses that are selectively expressed. For instance, carbohydrate antigens preferentially elicit IgG2 antibodies, whereas protein antigens usually elicit IgG1 and IgG3. Elucidating the biological basis of the selective expression of these IgG subclasses is important to our understanding immunodeficiencies and B lymphocyte development. To investigate clinical importance of IgG subclass deficiencies, a sensitive and specific assay has been developed for IgG subclasses using particle concentration fluorescence immunoassay. Preliminary clinical studies have already shown that infection-prone individuals often have selective IgG2 subclass deficiency. Normal levels of IgG2, however, do not rule out an immunodeficiency in the infection-prone individuals because some individuals have normal levels of IgG subclasses and are poorly responsive to antigens of bacteria. Based on animal studies, two contrasting models of B cell development have been advanced. One model of B cell development proposes a single lineage and proposes that a B cell can successively switch and produce any IgG subclass. The other model proposes multiple lineages and proposes that a B cell can express only some IgG subclasses. It has been found by us that anti-PC antibodies are mostly IgG2 with some IgG1, and that the V region of IgG1 anti-PC antibody is different from that of IgG2 antibody. Our finding, therefore, suggests that B cells producing anti-PC antibodies are progeny of not one ancestral B cell that has successively switched, but two independent ancestral B cells. Cellular studies using polyclonal activators also suggest that regulatory mechanisms for IgG1 and IgG3 are different from those of IgG2 and IgG4. Taken together, we favor the multi-lineage model better than the single lineage model of human B cell development.

Animals↗
PubMedDate not supplied

Comparing the efficacy of cisapride and ranitidine in oesophagitis: a double-blind, parallel group study in general practice.

Patients with endoscopically confirmed oesophagitis (n = 49) were treated for 8 weeks with either cisapride (10 mg four times a day) or ranitidine (150 mg twice a day) in a double-blind study in general practice. Mean overall symptom scores fell from 10.8 to 4.5 in the cisapride group and from 9.9 to 4.4 in the ranitidine group over the course of the study. The proportion of patients reporting improvements in individual symptoms in the two treatment groups (cisapride and ranitidine respectively) were: heartburn, 66% and 55%; acid regurgitation, 53% and 47%; epigastric pain, 60% and 52%; satiety, 57% and 47%; bloating, 69% and 71%; belching, 65% and 72%; nausea, 62% and 85%; vomiting, 77% and 66%; poor appetite, 50% and 75%. Improvement in the endoscopic grade of oesophagitis was observed in 66% of patients receiving cisapride and 63% of those receiving ranitidine. It was concluded that cisapride is as effective as ranitidine in relieving the symptoms of oesophagitis and in healing oesophageal erosions.

Adolescent↗