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Biomedical subjects

N Richardson

Publications and source records attributed to N Richardson.

17 recordsLinked to original sources
PubMed1995

Total antioxidant capacity and lipid peroxidation during liver transplantation.

1. We assessed plasma total antioxidant capacity using enhanced chemiluminescence and plasma lipid peroxides in eight patients undergoing orthotopic liver transplantation and 26 healthy control subjects. 2. The antioxidant capacity of plasma decreased significantly on reperfusion of the donor liver (P < 0.05) during liver transplantation, although levels were not lower in patients than in control subjects. 3. Pre-reperfusion antioxidant capacity correlated negatively with the concentration of lipid peroxidation products appearing in the plasma by the end of the transplant (P < 0.02), but did not correlate with vitamin A or E concentrations. 4. This study provides evidence of oxidant stress during liver transplantation, as shown by antioxidant utilization associated with increased lipid peroxidation.

Adult↗
PubMed1995

The effect of anticoagulant choice on apparent total antioxidant capacity using three different methods.

We assessed total antioxidant capacity using three different methods, in plasma samples treated with either EDTA or heparin as anticoagulant, from 26 healthy subjects. Total antioxidant capacity was determined using an oxygen electrode (as the total peroxyl radical-trapping antioxidant parameter), by enhanced chemiluminescence, and by measurement of the antioxidant-mediated quenching of the absorbance of a radical cation. The choice of anticoagulant had a profound effect on antioxidant capacity with heparinized plasma giving consistently higher values than plasma anticoagulated with EDTA. Using the oxygen electrode the mean value was 786.5 +/- 171.5 mumol/L (heparin) compared to 681.4 +/- 160.4 mumol/L (EDTA, P < 0.01). The chemiluminescence technique gave a mean antioxidant capacity of 915.6 +/- 214.1 mumol/L in heparin samples and 714.4 +/- 195.4 mumol/L in EDTA samples (P < 0.0001). The absorbance quenching technique gave a mean value of 867.0 +/- 199.2 mumol/L (heparin) and 675.5 +/- 245.4 mumol/L (EDTA, P < 0.001). All methods tested showed comparable results for EDTA plasma, but the chemiluminescence technique gave higher apparent antioxidant capacity than either of the two techniques when heparin plasma was used. We suggest that either heparin is interacting to enhance antioxidant protection perhaps through release of superoxide dismutase, or the chelation of metal ions by EDTA is limiting the activity of antioxidant metalloenzymes. Consistency in the choice of anticoagulant is clearly extremely important.

Adult↗
PubMed1992

A statewide public and professional education program on fragile X syndrome.

Fragile X syndrome is reported to be the most common inherited cause of mental retardation known, but the majority of affected individuals are as yet undiagnosed. The project described in this paper was developed to increase the public and professional awareness of fragile X syndrome in the state of New Jersey. As a result there were increased efforts at diagnostic screening, provision of client and family support services, and prevention. This educational program proved to be a cost-effective method for increasing community awareness of a genetic disease on a statewide level.

Adolescent↗
PubMed1992

Randomized controlled study of a retiree health promotion program. The Bank of American Study.

The initial results of a 12-month controlled trial of a health promotion program in 5686 Bank of America retirees, randomized into full program, questionnaire only, and insurance claims only groups, were analyzed to determine whether the health promotion program was effective. Comparisons were between program and questionnaire only groups for self-reported health habit changes, health risk scores, medical care utilization, and days confined to home, and between all groups for insurance claims data. The intervention, or full program, included health habit questionnaires administered every 6 months, individualized time-oriented health risk appraisals, personal recommendation letters, self-management materials, and a health promotion book. Twelve-month changes in health habits, health status, and economic variables favored the full program group in 31 of 32 comparisons and were statistically significant at the .05 level in two-tailed tests in 19 comparisons and at the .01 level in two-tailed tests in 13 comparisons. Over 12 months, overall computed health risk scores decreased by 4.3% in the full program experimental group and increased by 7.2% in the questionnaire only control group. Total direct and indirect costs decreased by 11% in the experimental group and increased by 6.3% in the questionnaire only control group. Analysis of claims data confirmed these trends. A low-cost health promotion program for retirees was effective in changing health behaviors and has potential to decrease health care utilization.

Aged↗
PubMed1990

Vigilance ratios implicate biological rhythms.

Vigilance research has been focused on differences, yet ratios might have intrinsic, numerical significance. Reanalysis of data from Watkins' 1963 psychophysical experiment and 49 vigilance reports showed that individual and group ratios, including errors or misses: detections, were related to roots (particularly of base 1/12 and multiples), powers, e-base ratios (EBR), and fractions. Examples are given from well-known experiments of remarkably exact relationships between conditions, time periods, etc. It is suggested that these phenomena are the product of biological rhythms. Theoretical implications are briefly discussed and the advantages of ratio analysis noted, as when this method proved that criterion beta changes, given as nonsignificant, formed part of an ordered set. In a real-world application, the frequency of lane-drifts in O'Hanlon and Kelly's 1977 report is shown to follow a mathematical pattern.

Arousal↗
PubMed1986

Anti-idiotypic sera against monoclonal anti-progesterone antibodies: production in rabbits and rats and characterization of specificity.

Antisera were raised in rabbits and rats against three mouse monoclonal anti-progesterone IgG1 antibodies. Anti-idiotypic antibodies were isolated from rabbit sera by successive passage over immunoadsorbent columns of normal mouse Ig and the specific immunizing monoclonal, with elution from the latter. Radioimmunoassays for anti-idiotype and free idiotype were established, enabling detection of idiotype in sera of mice immunized with progesterone-BSA conjugate. Binding of rabbit anti-idiotype to anti-progesterone monoclonals was partially inhibitable by free progesterone-hemisuccinate or progesterone-ovalbumin conjugate. While showing considerable specificity for their respective inducing monoclonals, the anti-idiotypes also cross-reacted in varying degrees with the other anti-progesterone monoclonals, demonstrating the presence of IdI and IdX determinants. The patterns of cross-reactivity showed some correlation with the relative isoelectric points and combining-site specificities of the anti-progesterones. The specificities of rat and rabbit anti-idiotypes were similar, but not identical.

Animals↗
PubMed1985

Effector functions of a monoclonal aglycosylated mouse IgG2a: binding and activation of complement component C1 and interaction with human monocyte Fc receptor.

Aglycosylated monoclonal anti-DNP mouse IgG2a produced in the presence of tunicamycin was compared with the native monoclonal IgG2a with respect to its ability to interact with the first component of complement, C1, and to compete with human IgG for binding to human monocyte Fc receptors. The aglycosylated IgG2a was found to bind subcomponent C1q with an equivalent capacity to the native IgG2a, but the dissociation constant was found to be increased three-fold. When activation of C1 by the glycosylated and aglycosylated IgG2a was compared, the rate of C1 activation by the aglycosylated IgG2a was reduced approximately three-fold. In contrast aglycosylation was accompanied by a large decrease (greater than or equal to 50-fold) in the apparent binding constant of monomeric IgG2a to human monocytes. The data suggest that the aglycosylated IgG2a has a structure which differs in the CH2 domain from the native IgG2a, and that the heterogeneous N-linked oligosaccharides of this monoclonal IgG2a which occur at a conserved position in the CH2 domain play a role in maintaining the integrity of its monocyte-binding site. This lack of monocyte binding may result either from a localized conformational change occurring in a single CH2 domain or from an alteration in the CH2-CH2 cross-domain architecture which is normally structured by a pair of opposing and interacting oligosaccharides. The minimal changes in C1q binding and C1 activation suggest that the oligosaccharides are, at most, indirectly involved in these events.

Animals↗
PubMed1985

A workplace health education program that reduces outpatient visits.

A workplace health education program aimed at reducing unnecessary outpatient visits was offered through 22 California employers. A total of 5,200 employees attended a presentation, received self-help books, and completed self-administered questionnaires. All visits for their households were monitored for up to 15 months. The study utilized a quasi-experimental staggered intervention design involving eight different cohorts, before/after comparisons, with statistical adjustment for seasonality and other intervening variables. Visit rates for households insured only by Blue Cross of California were reduced by 17% (P = 0.001), or 2.0 visits per household per year. For all participants, the reduction was 7.2% (P = 0.06), or 0.8 visits. Reductions were seen for all age and educational strata. The program was most effective among households with first dollar fee-for-service insurance coverage. Households with insurance requiring co-payments had less reduction. No reduction was seen among health maintenance organization (HMO) members. The study concludes that a minimal cost, self-care workplace intervention can reduce outpatient visits by important magnitudes.

Adult↗
PubMed1985

Enhancement of hydrophobic interaction, negative charge and phagocytosis by dinitrophenyl ligand coupling to Salmonella typhimurium 395 MS.

Dinitrophenylation of Salmonella typhimurium bacteria increased their hydrophobicity, negative charge, and interaction with PMNL in vitro, effects which are similar to the consequences of S-R mutation in S. typhimurium. The effects are ascribed to the hydrophobicity of the dinitrophenyl (DNP) ligand. Coupling of DNP-groups to the bacteria also enhanced their clearance by the reticuloendothelial system after intravenous injection into mice. Extensive DNP-coupling to the bacteria led to rapid deposition of injected bacteria outside the reticuloendothelial system. The kinetics of DNP-coupling showed saturation at 4-5 X 10(7) DNP groups per bacterium, similar for S and R bacteria, boiled and nonboiled. After 2 h of reaction with fluoro-2,4-dinitrobenzene (FDNB) more than 80% of the total DNP coupling observed after 4 h had occurred. The capacity of MOPC-315 IgA myeloma protein, which possesses anti-DNP activity, to bind to dinitrophenylated bacteria paralleled the number of DNP groups per bacterium, but smaller numbers of IgA molecules were bound. Approximately one IgA molecule bound per thousand DNP ligands. Only when bacteria were boiled prior to DNP coupling was agglutination observed after the addition of anti-DNP-IgA.

Binding Sites, Antibody↗
PubMed1985

The effects of binding mouse IgA to dinitrophenylated Salmonella typhimurium on physicochemical properties and interaction with phagocytic cells.

The binding of mouse IgA antibody to DNP-conjugated bacteria enhanced the hydrophobic interaction when measured in dextran-poly(ethyleneglycol) two-phase systems and hydrophobic interaction chromatography. Similarly the interaction with polymorphonuclear leukocytes in vitro increased. In contrast, the rate of clearance of IgA-reacted bacteria from the blood stream of mice, after intravenous injection, was reduced under the conditions tested. Our data showed, with respect to increased hydrophobic interaction and opsonization, that binding of IgA antibody to bacteria produced less pronounced effects than those of IgG antibody binding. In contrast, secretory IgA antibody binding has been shown to reduce hydrophobic interaction and phagocytosis. Thus, serum IgA antibody has properties intermediate to IgG and SIgA with respect to hydrophobicity and opsonization.

Animals↗
PubMed1985

Vigilance missed signals may have preferred average lags.

The randomness of average missed signal lags (AMSL) in experiments on vigilance was investigated. This measure was taken from group data in a sample of 116 published visual reports (on which an ad hoc cluster analysis was carried out) and from the 1966 results for 48 subjects tested by Smith, Lucaccini, Groth, and Lyman. Evidence of a 4-min. periodicity was found. This apparent effect of a biorhythm may extend the explanation of the absolute level of performance and, possibly, of the vigilance decrement. Depending on the effect-size, it might also have relevance for the practical problem of the maintenance of alertness.

Arousal↗
PubMed1977

Biosynthesis and characterization of intracellular IgDkappa in a case of CLL.

A case of chronic lymphocytic leukaemia (CLL) with diffuse intracellular IgDkappa is reported. No serum paraprotein or urinary Bence-Jones protein were detected. No surface immunoglobulin was found on the neoplastic lymphocytes, but the cells had receptors for Fcgamma and the C3 component of complement consistent with other cases of CLL. Biosynthetic studies confirmed that the cells synthesized IgDkappa but there was no evidence for secretion of IgD into the culture medium. The cells did not produce Ig of any other class. The intracellular IgD occurred predominantly as deltakappa units with no covalent links between the chains. These findings are discussed.

Binding Sites, Antibody↗