Biomedical subjects

M K Stuart

Publications and source records attributed to M K Stuart.

7 recordsLinked to original sources

PubMed2003

Monoclonal antibodies to elongation factor-1alpha inhibit in vitro translation in lysates of Sf21 cells.

Elongation factor-1alpha (EF-1alpha) is an enzyme that is essential for protein synthesis. Although EF-1alpha offers an excellent target for the disruption of insect metabolism, agents known to interfere with EF-1alpha activity are toxic to humans. In this article, we describe the development of monoclonal antibodies (MAbs) that can disrupt the activity of insect EF-1alpha without cross-reacting with the human enzyme. MAbs were generated to EF-1alpha from Sf21 cells derived from the fall armyworm, Spodoptera frugiperda, by immunizing mice with EF-1alpha eluted from SDS-PAGE gels. The MAbs reacted with EF-1alpha in eggs and first through fifth instars of the fall armyworm in immunoblots of SDS-PAGE gels, but did not recognize EF-1alpha in human carcinoma cells and normal tissues. MAbs with the ability to recognize EF-1alpha in its native conformation, identified through immunoprecipitation experiments, were added to Sf21 cell lysates to determine whether the antibodies could inhibit incorporation of [(35)S]methionine into newly synthesized in vitro translation products. Of the four EF-1alpha-specific MAbs tested, three significantly inhibited protein synthesis when compared to the negative control antibody (P < 0.001, one-way ANOVA; followed by Dunnett's test, P < 0.05).

Animals↗

PubMed1998

An antibody diagnostic for hymenopteran parasitism is specific for a homologue of elongation factor-1 alpha.

An enzyme-linked immunosorbent assay (ELISA) useful for identifying noctuid pests parasitized by hymenopteran endoparasitoids was recently described. The ELISA employed a monoclonal antibody (MAb 9A5) that appeared highly polyspecific for parasitoid antigens, yielding banding patterns more typical of a polyclonal antiserum than of a monoclonal antibody in immunoblots of parasitoid homogenates subjected to SDS-PAGE. Although MAb 9A5 appeared capable of binding to dozens of parasitoid antigens, no cross-reactivity for noctuid antigens was evident by either immunoblotting or ELISA. In the study described here, immunoprecipitation, SDS-PAGE, and N-terminus amino acid sequencing were used to identify the protein recognized by MAb 9A5 as a homologue of elongation factor-1 alpha (EF-1 alpha). The propensity for EF-1 alpha to bind to cytoskeletal components, the additional subunits of EF-1, and other proteins may account for the apparent polyspecificity of MAb 9A5 in immunoblots of whole-body parasitoid homogenates. The presence of a unique hymenopteran epitope suggests that EF-1 alpha molecules from other insect groups could similarly express novel determinants. These determinants may prove useful not only for insect detection, but also as targets for selective insecticides that act by inhibiting protein synthesis.

Amino Acid Sequence↗

PubMed1991

Physiological correlates to 800 meter running performance.

Much of the previous research efforts aimed at determining those physiological characteristics that contribute to distance running success have centered around distances greater than 1500 meters with little attention to events such as the 800 meter run. Therefore, this investigation examined the relationship between selected physiological and body composition, characteristics and performance in an 800 meter run. Measurements of body composition, VO2max, running economy, and performance times for 100 and 300 meter dashes were obtained on 11 male track athletes. Stepwise multiple regression analysis was performed using 800 meter race time as the dependent variable. Although the combination of 300 and 100 meter run times, percent body fat, running economy and VO2 max as independent variables accounted for the greatest amount of total variance (r2 = .89), the additional variance explained by the model did not increase significantly (p greater than 0.05), when VO2max, percent body fat, and running economy were added to a model which contained 300 and 100 meter run time (r2 = .85) as the explanatory variables. These data offer additional support for the notion that much of the intramuscular ATP produce and utilized during an 800 meter run comes from anaerobic metabolic pathway.

Adult↗

PubMed1990

Monoclonal IgM rheumatoid factor-like anti-globulins enhance the inhibitory effects of Plasmodium falciparum-specific monoclonal antibodies in vitro.

Monoclonal IgM rheumatoid factor-like anti-globulins were produced by in vitro stimulation of naive BALB/c spleen cells with lipopolysaccharide, and by hyperimmunization of mice with merozoites of Plasmodium falciparum, followed by fusion of the spleen cells to mouse myelomas. In vitro, these anti-globulins augmented the inhibitory effects of P. falciparum-specific polyclonal mouse sera and monoclonal IgG1 and IgG2b antibodies by binding to Fc fragments of IgG molecules attached to blood-stage parasites. In some instances, the presence of anti-globulins correlated with an increase in the number of schizonts which failed to disperse merozoites. In other cases, parasitaemia remained low in the absence of the schizont inhibition phenomenon, suggesting that anti-globulins contribute to host cell protection not only by agglutinating merozoites, but also by increasing the density of the antibody coat surrounding the parasites, thus interfering with parasite receptor-erythrocyte ligand interactions. The anti-globulins were not inhibitory when added to parasite cultures containing IgG not specific for P. falciparum. These results may help explain the function of IgM anti-globulins found at elevated serum levels in some patients with malaria or other chronic infectious diseases.

Animals↗

PubMed1986

Peak oxygen uptake in arm ergometry: effects of testing protocol.

The purpose of this investigation was to determine if a new proposed arm ergometer protocol was advantageous in eliciting higher peak oxygen uptake (peak VO2) when compared with two protocols currently referred to in the literature. Ten male subjects were tested on three different exercise protocols; a discontinuous test (DT), a continuous test (CT) and a new proposed jump-max test (JMT). The CT began at a work rate of 33 watts (W) (40 rpm) with the power output (PO) being increased 16 W every 3 minutes. The DT began without resistance on the ergometer flywheel (50 rpm) and the work rate was increased by 25 W every 3 minutes with a 1-minute rest between stages. The JMT began with a 3-minute pretest to determine a PO which elicited a HR of 120 +/- 5 beat min-1. After a 2-minute rest, subjects began exercise at the predetermined work rate (80 rpm) with the PO being increased 20 W each minute of the test. Oxygen uptake was measured minute by minute via open circuit spirometry. Peak VO2 was higher (p less than 0.05) in the JMT (mean +/- SEM = 2.36 +/- 0.06 l.min-1) when compared with either (means +/- SEM = 2.16 +/- 0.07 l.min-1) or the CT (means +/- SEM = 2.04 +/- 0.10 l.min-1). No difference (p greater than 0.05) existed in peak VO2 between the CT and the DT. These data suggest that the proposed JMT may result in a higher measured peak VO2 in subjects when compared with either DT or CT of moderate to long duration.

Adolescent↗

PubMed1986

Hemoglobin desaturation in highly trained athletes during heavy exercise.

It has been generally accepted that during exercise at sea level, the pulmonary system of normal, healthy individuals is capable of maintaining arterial oxygen tension at near resting levels. However, recent evidence questions whether this generalization applies to the highly trained endurance athlete who is capable of achieving very high levels of metabolic demand. Hence, the purpose of these experiments was to examine the relationship between maximal oxygen consumption (VO2max) and arterial oxygen-hemoglobin saturation (%SaO2) during short-term heavy exercise in trained athletes and untrained individuals. Ten trained distance runners and 7 untrained males exercised at 95% of VO2max for 3 min. Minute-by-minute measurement of %SaO2 was obtained via ear oximetry. The correlation coefficients between %SaO2 and VO2max during exercise were r = -0.68, r = -0.74, and r = -0.72 (P less than 0.05) for minutes 1 through 3, respectively. In general those individuals with the highest VO2max showed the greatest decrease in %SaO2. By comparison there was no difference (P greater than 0.05) in resting %SaO2 between the trained (96.3 +/- 0.2% [SE]) and the untrained (96.3 +/- 0.4%) subjects. However, at minute 3 of exercise, %SaO2 was significantly lower (P less than 0.05) in the trained subjects (87.0 +/- 0.7%) than in the untrained subjects (92.6 +/- 0.7%). These data demonstrate that arterial desaturation occurs in healthy, highly trained endurance athletes during heavy exercise and that the level of the arterial desaturation is inversely related to VO2max.

Adolescent↗

PubMed1981

Efficiency of trained subjects differing in maximal oxygen uptake and type of training.

This study was undertaken to examine the relationship between energy expenditure and work rate on a bicycle ergometer in five sprinters and five distance runners who differed in maximal oxygen uptake (VO2max) and type of training. Each subject performed at work rates of 30, 60, 90, 120, and 150 watts (W). The relationship between energy expenditure and work rates was most accurately described by a quadratic curve for both groups: for sprinters, energy expenditure (kJ) = 11.57 + 0.1812 (W) + 0.00046 (W)2; for distance runners, energy expenditure (kJ) = 11.74 + 0.1386 (W) + 0.00060 (W)2. Delta efficiency (delta work accomplished divided by delta energy expended X 100%) decreased as work rate increased. Statistical analyses revealed no significant differences between groups in delta efficiency at the same work rate (P greater than 0.25) or at the same relative work rate (P greater than 0.75). These results suggest that differences in VO2max and/or type of training have little or no causal effect on the decrease in delta efficiency with increasing work rate. The observed decrease in delta efficiency may be due to increases in metabolism not directly related to the performance of the external work or to an increasing amount of unmeasured work as work rate increases on a bicycle ergometer.

Adult↗