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Biomedical subjects

B A Wilson

Publications and source records attributed to B A Wilson.

At least 127 records · Page 7Linked to original sources
PubMed1986

Skeletal muscle lactate release and glycolytic intermediates during hypercapnia.

The effects of respiratory acidosis on glycolysis in the autoperfused canine gastrocnemius-plantaris were studied using anesthetized dogs that were ventilated either with air (n = 30) or with 4% CO2-21% O2-75% N2 (n = 30). The left muscle group was stimulated at 3 Hz for up to 20 min, after which the active and the contralateral resting muscles were removed and frozen in liquid N2. Blood flow, VO2, Vco2, and tension development were unaffected by CO2. Glycogen catabolism was not affected, but lactate release (La) was lower (P less than 0.05) during activity with CO2; and greater fructose 6-phosphate, fructose 6-phosphate/fructose 1,6-diphosphate, and alpha-glycerophosphate/dihydroxyacetone phosphate ratios resulted (P less than 0.05). With respiratory acidosis, muscle lactate tended to accumulate early in contractions, but a net lactate uptake occurred during the last 10 min of contractions. Thus, respiratory acidosis reduced lactate efflux and there was a net uptake late in the contraction period. Glycogen phosphorylase did not appear to be affected by the respiratory acidosis, but there was evidence of inhibition at the phosphofructokinase step as well as a tendency for lactate to accumulate within the muscle. La often occurred in a direction contrary to the muscle-venous lactate concentration difference with either air or CO2 and La also decreased far more rapidly over time than did the arterial-venous H+.

Acidosis, Respiratory↗
PubMed1986

Studies on potential biological control agents of immature mosquitoes in sewage wastewater in southern California.

Three biological control agents, a copepod, Mesocyclops leuckarti pilosa, and two fish, Cyprinodon macularius and Poecilia reticulata, were evaluated for their survival in secondary sewage effluent (SSE) and predation potential on mosquito larvae. Results showed that the survival of M. l. pilosa was not significantly affected in SSE or SSE diluted (50%) with water. In predation tests, the copepod consumed from 50 to 90% of the 1st-instar larvae of Culex quinquefasciatus in 24 to 72 hr and P. reticulata fed on almost all stages (egg to pupa) of the test mosquitoes. Survivorship of P. reticulata and C. macularius in SSE was not significantly affected by SSE under both greenhouse and sewage aquaculture conditions. Poecilia reticulata was distributed towards the influent end and C. macularius towards the effluent end of the aquaculture ponds, indicating the former species can tolerate higher levels of pollution which exists at the influent end of the pond. However, low water temperature and dissolved oxygen may be detrimental to these fish species in sewage aquacultural systems.

Animals↗
PubMed1984

Effects of centrally administered naloxone on phrenic nerve activity.

The present study examined the effect on respiration of naloxone administered centrally. Experiments were performed on anesthetized, paralyzed cats whose vagi and carotid sinus nerves had been cut. The animals' end-tidal pCO2 and body temperature were kept constant with servocontrollers. Naloxone administered into the third cerebral ventricle in doses of 40 micrograms/kg and 400 micrograms/kg resulted in significant (P less than 0.05) increases in phrenic neural activity. The response to the 400 micrograms/kg dose was significantly greater (P less than 0.05) than the response to the 40 micrograms/kg dose. A dose of 40 micrograms/kg naltrexone administered to each of two animals produced similar increases in respiratory activity. These data indicate that in the preparation studied endogenous opiates exert a tonic inhibitory effect on respiration through their action on central opiate receptors.

Animals↗
PubMed1983

Effects of hypercapnia and hyperoxia on metabolism during exercise.

It has been postulated that the respiratory acidosis associated with hyperoxia (HO) may mediate some of the metabolic effects that are traditionally attributed to the elevation in PaO2. Five subjects performed 30 min of steady-state exercise (65% VO2max) on eight occasions while inspiring either 21 or 60% O2 in combination with 0, 2, 4, or 6% CO2. Statistical significance was accepted if P less than 0.05. The four HO tests were associated with increased VO2 and lower R and blood lactate. However, when compared to the four normoxic tests, all of the hypercapnic (HC) conditions (independent of the inspired O2 percent) had statistically lower blood lactate. Hypercapnia was associated with lower R values and increased blood H+. Regression analysis demonstrated relationships between H+ and R, as well as between H+ and blood lactate. These findings are independent of whether 21 or 60% O2 was inspired, and support the hypothesis that acidosis, not PO2, mediates the effects related to HO.

Bicarbonates↗
PubMed1982

The effects of hypercapnia on the metabolic response to steady-state exercise.

Studies on isolated muscle and resting man have demonstrated that altering CO2 stores influences intracellular lactate production and/or tissue lactate release. In the present project, subjects (N = 6) performed steady-state exercise for 30 min while inspiring 0, 2, 4, or 6% CO2 and 21% O2. They were tested on eight occasions, four at 50% and four at 65% VO2max. Arterialized venous blood PCO2 increased in proportion to FICO2 (P less than 0.05). Blood pH had a similar but inverse relationship, decreasing from 7.371 to 7.233 (P less than 0.05). The VI increased directly with PCO2 (P less than 0.05), but no differences were found for VO2 or VO2. The R decreased in proportion to PCO2 (P less than 0.05) at both exercise intensities. Blood lactate was reduced (P less than 0.05) with CO2. At 65% VO2max lactate had an inverse linear relationship with blood PCO2 (P less than 0.05). The mean lactate decreased 43% from 3.88 mM . l-1 with 0% CO2 to 2.22 mM . l-1 with 6% CO2. The R shift suggest that carbohydrate metabolism may have been inhibited and lipid metabolism enhanced.

Acidosis, Respiratory↗
PubMed1981

Erythrocyte metabolism: kinetic and electrophoretic analyses of pig red cell hexokinase.

The mature erythrocyte of the pig has been observed to possess the slowest metabolic rate of any mammalian cell type. Previous studies in this laboratory suggested that the hexokinase isolated from these cells was inhibited by glucose in concentrations in excess of 0.2 mM. In the present study, the enzyme was isolated by utilizing DEAE-Sephadex A-50, ammonium sulfate precipitation, DEAE-cellulose (DE-52), and Sephadex G-100 gel-filtration. Studies on the hexokinase isolated from the pig mature erythrocyte by the above procedures revealed two distinct isozymes of hexokinase that do not behave kinetically and electrophoretically as those previously found in other mammalian red blood cells. The isozyme isolated from the erythrocyte of the young adult pig (less than six months of age) migrated at a slower electrophoretic rate than the one isolated from the adult pig (more than six months of age). Coupled with the observed difference in electrophoretic mobilities were changes in the apparent Km values as well as Vmax as a function of substrate concentration. In spite of the changes observed in relation to glucose, the apparent Km for Mg-ATP-2 was not altered during development. Diphosphoglycerate (DPG) was observed to be a "linear-mixed" inhibitor of both isozymes with respect to Mg-ATP-2. An experimental designed to determined the type of inhibition by DPG on the type I isozyme isolated from the horse erythrocyte revealed competitive inhibition with the Mg-ATP-2 site. Free Mg activated both isozymes in low concentrations (less than 2.5 mM) but inhibited the enzymatic activity as the concentration was elevated. The data suggest that both the young adult and the adult pig erythrocyte possess two distinct type III isozymes of hexokinase.

Adenosine Triphosphate↗
PubMed1981

Standardization of work intensity for evaluation of exercise-induced bronchoconstriction.

Reactivity of airways to 6 min of graded intensity treadmill work was studied in nine asthmatic and 15 non-asthmatic subjects. After performing a progressive VO2 max treadmill test, each subject completed five 6-min exercise tests at selected intensities: 40, 60, 80, and 100% VO2 max; and at 80% of VO2 max predicted from heartrate. Pulmonary function measures recorded after exercise demonstrated a direct relationship between work intensity and exercise induced bronchoconstriction (EIB) for both groups, with the asthmatics showing their lowest values at 80% VO2 max. Heartrate-set work intensities produced a wide range of aerobic demand, thus significantly increasing the variability of the EIB response recorded.

Adult↗
PubMed1981

Effects of positive end-expiratory pressure breathing on exercise-induced asthma.

Five volunteers, all with a history of childhood asthma that had persisted, though at a reduced severity and incidence, through their teens to the present, performed six treadmill runs on separate days for 6 min at 80% of VO2 max followed by 20 min of recovery. Two trials were completed under each of the following conditions: normal, positive end-expiratory pressure breathing (PEEP) during the work, and PEEP post-exercise. For each trial, forced vital capacity maneuvers (FVC) were completed twice at rest, at the 3rd and 6th min of exercise, and every 5 min during the 20-min recovery. No significant effects of PEEP in resting pulmonary function values was found nor was PET CO2 altered for rest, exercise, or recovery for PEEP vs normal trials. For the normal exercise tests, post-exercise broncho-constriction was shown by at 30% to 50% decrease in FEV1.0, 30% to 40% drop in PEF, and a 45% to 65% decrease in maximal flow at 50% VC (MEF50), comparing post-exercise values to rest. PEEP during and PEEP post conditions significantly (P less than 0.01) decreased the severity of exercise-induced asthma (EIA) as PEFR and FEV1.0 values remained within 20% of rest levels and MEF50 within 30%. Since PET CO2 was not altered by the PEEP conditions, the airway response cannot be mediated through CO2 effect, It is known that PEEP does reduce air trapping, but since PEEP during work had a lasting effect into recovery this indicates that some additional mechanism may be involved.

Adult↗
PubMed1980

Entrainment of breathing rate to movement frequency during work at two intensities.

Ten males and six females exercised on an electrically braked cycle ergometer. Three conditions were tested: preferred pedal frequency with no cues; preferred frequency established by listening to a metronome and preferred frequency maintained by watching a digital display. Each condition was performed at a low workload and a high workload, and this set of tests was repeated once. During each test, computer sampling of pedal and breath information occurred, and the relationship of breath signal occurrences to pedal signals was plotted by a post stimulus histogram program. Fourier analysis of psh data (Time Series Spectrum Estimation) decomposed each histogram into it's frequency components. The magnitude of the frequency at the fundamental of the pedal period (F1), and it's first harmonic (F2), were assessed using F ratios. For retest results, preferred condition, 100% of subjects were entrained for both low and high workloads. With the metronome, 87% were entrained at the low workload and 94% at the high workload. For both workloads, 94% were entrained when watching a digital printout of pedal frequency. For preferred pedal rate, at the two workloads tested, the results of this study strongly support the existence of entrainment, and provide evidence for neurogenic input to ventilatory control during steady state work.

Adult↗
PubMed1980

Maximal oxygen uptake during free, tethered, and flume swimming.

The purpose of this study was 1) to compare the maximal oxygen uptake (VO2max) obtained in swimmers during tethered swimming, free swimming, and flume swimming, and 2) to determine whether an arm-ergometer test would provide comparable results. In the first experiments the VO2max for tethered swimming (2.67 +/- 0.26 l/min) and flume swimming (2.62 +/- 0.26 l/min) were not different (P greater than 0.05) and were highly correlated (r = 0.99). However, with arm ergometry a significantly lower VO2max (2.36 +/- 0.24 l/min) occurred from those found in the two swimming tests (P less than 0.05). Other experiments demonstrated that the tethered swimming VO2max (3.53 +/- 0.27 l/min) and the free swimming VO2max (3.55 +/- 0.28 l/min) also provide results that were similar (P greater than 0.05) and highly correlated with each other (r = 0.99). Differences between tethered and flume swimming, and tethered and free swimming were small, being 1.2 +/- 1.6% and 0.6 +/- 0.9%, respectively. Differences between tethered swimming and arm ergometry VO2max were large, 14.7 +/- 2.4%, despite the high correlation (r = 0.97) between these measurements. Predictions of a swimming VO2max from the arm-ergometer data yielded a considerable error (+/-7.1% and +/-7.4%). The present results indicate that flume swimming, free swimming, and tethered swimming yield essentially identical VO2max results.

Adolescent↗
PubMed1980

Exercise efficiency: validity of base-line subtractions.

In evaluating the efficiency of humans performing exercise, base-line subtractions have been used in an attempt to determine the efficiency of the muscles in performing the external work. Despite the fact that base lines have been criticized previously, they have been widely used without adequate analysis of the implications involved. Calculations of efficiencies using data available in the literature for isolated muscle preparations revealed that base-line subtractions result in unreasonably high efficiencies. This suggests strongly that the base lines are invalid. To be valid, a base line must continue unchanged under all the conditions in which it is applied. Previously published data indicate clearly that exercise base lines change with increasing work rate and are therefore invalid. The use of base lines is further complicated by elastic energy storage in some types of exercise. Although exercise efficiencies using base line subtractions may be useful, they do not indicate muscle efficiency. Perhaps future studies of exercise metabolism should be directed less at refining base lines and more toward describing and quantifying the determinants of energy expenditure.

Efficiency↗
PubMed1980

The effects of hypercapnia on metabolic responses to progressive exhaustive work.

Altering CO2 storage has been shown to influence lactate metabolism. However, the metabolic effects on man during physical activity have not been well documented. Subjects (n = 8) performed a progressive bicycle test (beginning at 0 and increasing 30 W every 4 min to exhaustion) on two occasions (once inspiring compressed air and once 4% CO2 and 21% O2). The work time, peak Vo2, VCO2, and HR achieved were the same in the two trials for each subject. The VI was significantly (p less than or equal to 0.05) elevated throughout the CO2 work and the recovery. The O2 debt increased from a mean of 5.87 to 7.761 with CO2, although the difference was not significant. Blood lactate was lower (p less than or equal to 0.05) from the onset of the work and throughout both the exercise and the 30 min. recovery period. Peak lactate was decreased from a mean of 9.59 to 6.99mM.1(-1). The oxygen cost of the work was not altered but the blood lactate response to the activity was significantly depressed. The reduction in lactate could be due to glycolytic inhibition and enhanced fat metabolism. The data support, but do not prove, this hypothesis.

Adult↗
PubMed1979

Interaction of hyperoxia and blood flow during fatigue of canine skeletal muscle in situ.

Right and left gastrocnemius-plantaris muscle preparations in 20 dogs anesthetized with pentobarbital sodium were used to investigate the effect of hyperoxia on tension maintenance. Muscles were stimulated via the sciatic nerve for 20 min at 60 200-ms tetanic contractions/min (10 impulses/contraction). Direct muscle stimulation after the experimental period resulted in no significant change in tension. In control experiments the tension developed by the right or left muscles over the 20 min was not different. The tension developed by muscles perfused with hyperoxic blood decreased 14% after 20 min, whereas tension in the normoxic muscles decreased 35%. Blood flow in the hyperoxic muscles was significantly higher at 20 min (P less than 0.05). Pump perfusion of one of a pair of normoxic muscles resulted in a tension decrease of 13% in the pump-perfused muscles, whereas tension in the control muscles decreased 34%. Tension maintenance was flow dependent. The effect of hyperoxia could be mediated through the involvement of oxygen in the long-term control of muscle blood flow.

Animals↗
PubMed1978

Inducers of DNA synthesis present during mitosis of mammalian cells lacking G1 and G2 phases.

The cell cycle analysis of Chinese hamster lung fibroblast V79-8 line by the premature chromosome condensation method has confirmed the absence of measurable G1 and G2 periods. Sendai virus-mediated fusion of mitotic V79-8 cells with G1 phase HeLa cells resulted in the induction of both DNA synthesis and premature chromosome condensation in the latter, indicating the presence of the inducers of DNA synthesis above the critical level not only throughout S phase, as it is in HeLa, but also during mitosis of V79-8 cells. No initiation of DNA synthesis was observed when G1 phase HeLa cells were fused with mitotic CHO cells. These results indicate that the presence or absence of a G1 period in the cell cycle depends on the levels of the inducers of DNA synthesis present in the cell during mitosis.

Cell Cycle↗
PubMed1978

Relation between oxygen uptake and developed tension in dog skeletal muscle.

Isometric developed tension of in situ gastro-cnemius-plantaris and semitendinosus muscles of the dog was increased 30% with twitch contraction frequency over the range of 0.5--2.0 tw/sc. Developed tension was decreased 75% after 30--40 min of 11--14 tw/s contractions, fatigue. Recovery from fatigue was slow. Intravenously injected K+ after fatigue increased developed tension 50%. Infusions of epinephrine, norepinephrine, and ouabain did not change developed tension. When the oxygen uptake of gastrocnemius-plantaris muscle was measured during twitch contractions at 0.5, 1.0, and 2.0 tw/s before and after fatigue and after injection of K+, the oxygen uptake was found to be directly related to the developed tension.

Action Potentials↗
PubMed1978

A board searches for a CEO.

The board of directors of Mercy Hospital, Urbana, IL, recently chose to conduct its own search for a new CEO. Research on other self-directed searchers, delineation of the hospital's needs, and development of criteria for the CEO led to the screening of candidates. Both the board and the new CEO believe that the selection method--a time- and energy-consuming one--contributed greatly to the current mutual satisfaction.

Governing Board↗