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Biomedical subjects

G M Davis

Publications and source records attributed to G M Davis.

At least 109 records · Page 6Linked to original sources
PubMed1985

Serum and dialysate concentrations of cephalexin following repeated dosing in CAPD patients.

Oral cephalexin, 1 to 2 g daily for 3 days, was given to six stable, noninfected patients receiving maintenance continuous ambulatory peritoneal dialysis (CAPD). The peak serum concentration after a 2 g initial dose was between 73 and 123 mg/L. On the second and third day in five patients who received a 2 g daily oral dose, the serum concentrations were between 35 and 118 mg/L in serum obtained 1 to 1.5 hours after the dosing. Similar serum concentrations were seen in one patient who only received a 1 g oral dose on the second and third day. Cephalexin concentrations in the peritoneal dialysate reached a peak on the first day between 4 to 14 hours after the dose and were between 31 to 78 mg/L. During the second and third day, the highest cephalexin concentration was 118 mg/L and the lowest was 12 mg/L. The data are consistent with the feasibility of oral cephalexin for treatment of CAPD-associated peritonitis with microorganisms that are sensitive to these levels of cephalexin.

Administration, Oral↗
PubMed1985

Muscle strength and aerobic power--a study of lower-limb disabled males.

The relationship between arm strength and aerobic power (VO2 peak) was examined in 35 lower-limb disabled males. Equations related predicted VO2 peak to simple measurements of isokinetic and/or static strength. Covariance analysis (ANCOVA) showed that after allowance for level of habitual activity and lesion level there was a highly significant relationship between VO2 peak and simple strength measurements (greater for isokinetic than for static data). The findings suggest that in the wheelchair-bound the extent to which arm strength is developed has more impact upon cardiovascular performance than does the anatomical level of the lesion.

Adolescent↗
PubMed1984

Cardiorespiratory and metabolic responses during Tai Chi Chuan exercise.

Tai Chi Chuan is a form of traditional Chinese exercise which has been widely practised in China for preventive and therapeutic purposes. The present study was designed to determine the physiological demands of this exercise modality. Eleven healthy males, aged 28.4 years, were studied for oxygen cost and related metabolic variables, heart rate and blood pressure during the performance of the Long-Form Tai Chi Chuan of Yang's style. Data was collected by an automated respiratory gas analyzer (Jeger Ergooxyscreen) and ECG telemetry during a 17-25 minute performance session (X = 22 minutes). The average energy cost for the Long-Form Tai Chi Chuan was 4.1 Mets, corresponding to a mean VO2 value of 1.03 l X min-1 or 14.5 ml X kg-1 X min-1. The mean peak heart rate during the exercises was 134 beats per minute. These values suggest that the Long-Form Tai Chi Chuan may be classed as moderate exercise, and its intensity does not exceed 50% of the individual's maximum oxygen intake.

Adult↗
PubMed1983

Field testing: assessment of physical fitness of disabled adults.

The objectives of this investigation were (i) to develop simple field-test procedures for examining the cardio-respiratory and muscular strength fitness of lower-limb disabled individuals and (ii) to compare fitness levels across disabilities and physical activity levels. Forty-nine disabled adults (42 males and 7 females) were classified according to (i) functional and/or muscular deficit and, (ii) level of habitual physical activity. A forearm ergometer test was used to determine peak oxygen intake (VO2 peak). Sex-specific regression equations developed from the direct test were used in conjunction with a modified Astrand-Ryhming equation to predict VO2 peak from sub-maximal test results. Likewise, an equation was developed to predict isokinetic upper body strength (UBS) from cable tensiometry and hand grip force. The predictive power of the sub-maximal ergometer test was fair (r = 0.67), while the isometric strength measurements were relatively effective in predicting isokinetic total UBS (r = 0.82). Class 1 differed significantly from all other classes with respect to VO2 peak and UBS. The more active individuals also achieved significantly higher scores (p less than 0.05) for both variables. This study shows that an estimate of peak oxygen intake and UBS can be obtained from simple field tests and that active disabled individuals are more fit than their inactive counterparts.

Adolescent↗
PubMed1981

Cardiorespiratory fitness and muscular strength of wheelchair users.

The classification of lower-limb disabilities is commonly based on the site of the spinal cord lesion or the amount of functional muscle. Another important variable in assessing wheelchair users is their ability to carry out the activities of daily living. The cardiorespiratory fitness of those with lower-limb disabilities is usually assessed with arm-ergometry and wheelchair tests, each of which has some advantages. Muscle strength and endurance are also important aspects of the disabled person's ability to function. Fitness is often poor in the disabled, and normal wheelchair use does not seem to prove an adequate training stimulus. Exercise with an arm ergometer and with pulleys and participation in vigorous wheelchair sports can improve physical condition. Participation in exercise programs should be based on the results of a fitness assessment and on the level of the spinal cord lesion in those with paraplegia. Progression in such programs should be gradual to ensure that the exerciser does not become discouraged and drop out of classes before fitness is increased. Data on wheelchair athletes suggest that, with persistence, many individuals in wheelchairs can adjust relatively well to their disabilities.

Arm↗
PubMed1981

Cardio-respiratory fitness and muscular strength in the lower-limb disabled.

The International Year of the Disabled Person has focused increased attention upon the fitness status of the wheelchair-confined. Review of the world literature indicates that cardio-respiratory assessment has been based relatively equally upon forearm cycling or wheelchair ergometry; each of these techniques have particular advantages. The evaluation of muscular strength and endurance has received much less attention, in spite of the importance of these factors to the daily function of the lower-limb impaired. Also neglected in the past has been the psychological correlates of spinal cord trauma and their possible interaction with attitudes concerning physical activity. Fitness is often poor in the disabled, and everyday wheelchair propulsion does not seem to provide a sufficient stimulus for cardio-respiratory adaptation. Additional training in the form of forearm pedalling, exercises with weights or wheelchair sports may provide an effective means of improving cardio-respiratory fitness and muscle function. Indeed, research on disabled athletes has suggested that with persistent sports participation or fitness conditioning many wheelchair-confined individuals can make a relatively good physiological and psychological adaptation.

Hemodynamics↗
PubMed1979

Increasing minority recruitment to the health professions by enlarging the applicant pool.

Over an eight-year period, 707 students from minority groups or with economically disadvantaged backgrounds were selected from junior and senior-high-school classes throughout the state of Arizona and admitted to a Med Start program emphasizing careers in the health professions. The program featured recruitment into clubs, training in leadership, counseling by other minority students, work experience and specialized courses in English, mathematics and basic biologic sciences. Attrition was remarkably low. At the time of follow-up study, 369 of these students had sought further education beyond high school, and 220 of this group had enrolled in or completed health-education programs. Although obviously not a controlled experiment, this experience suggests that the pool of minority and economically disadvantaged applicants for careers in the health professions can be enlarged.

Arizona↗
PubMed1978

Relationship between maximal oxygen uptake and left ventricular function in exercise.

Left ventricular systolic time intervals (STI's), cardiac output, and arterial blood pressures were measured during bicycle ergometer work in three groups of 10 young men (aged 20-33 yr) who represented average (VO2max = 42-45 ml.kg-1.min-1), moderate (VO2max = 50-56 ml.kg-1.min-1), and high (VO2max = 59-72 ml.kg-1.min-1) levels of cardiovascular fitness. The subjects were studied using noninvasive procedures at steady-state heart rate of approximately 110, 130, and 150 beats.min-1. At all exercise levels, the fitter subjects displayed slightly shorter values for the preejection period (PEP) compared with less fit groups. Significantly (P less than 0.05) larger stroke volumes, longer left ventricular ejection times (LVET), faster mean systolic ejection rates and lower PEP/LVET ratios were found in the group with the highest aerobic capacity. Although these observations appear to indicate a superior mean level of left ventricular performance in groups who represent high levels of cardiovascular fitness, it was concluded that the use of STI values by themselves to describe the cardiovascular fitness of an individual would not be warranted.

Adult↗
PubMed1978

Reliability of noninvlasive methods for measuring cardiac function in exercise.

Externally recorded systolic time intervals (STI's), indirect (CO2 re-breathing) cardiac output, and auscultatory blood pressures were measured during upright bicycle ergometer work in 20 healthy men, aged 24-56 yr. The subjects were studied on 2 separate days at steady-state work loads chosen to represent light (mean heart rate (HR) = 96 beats.min-1), moderate (HR = 118 beats.min-1) and heavy (HR = 147 beats.min-1) exercise. In addition to determinations of cardiac output, systolic time intervals, and blood pressure, the individual's mean systolic ejection rate (stroke volume/left ventricular ejection time) was calculated as a measure of left ventricular function. In general, heart-rate-corrected STI's were found to be reliable and reproducible. Reliability coefficients for total electromechanical systole and left ventricular ejection time ranged from 0.93 to 0.96 while those for the preejection period and its subcomponents were between 0.63 and 0.88. The reliability of cardiac output, stroke volume, mean systolic ejection rate, and systolic blood pressure was also considered to be acceptable but tended to be higher during moderate and heavy work (r = 0.85-0.95) compared to light exercise (r = 0.60-0.83).

Blood Pressure Determination↗
PubMed1976

Monograph on "Lithoglyphopsis" aperta, the snail host of Mekong River schistosomiasis.

We discuss the morphology, histology, ecology, distribution, systematics, and evolutionary relationships of "Lithoglyphopsis" aperta Temcharoen, the snail host of Mekong River Schistosoma sp., and part of a vast, complex, endemic hydrobid fauna consisting of 11 genera and over 80 species. "L" aperta is a member of the Hydrobiidae (as broadly outlined by Fretter & Graham, 1962), subfamily Triculinae (as defined by Davis, 1968b). "L" aperta cannot be assigned to Ltihoglyphopsis because its shell and radula differ from those of the type-species, L. modesta (Gredler) from China, and because L. modesta is apparently more closely allied to other Mekong River genera in these traits. The female reproductive system of "L." aperta is similar to that of Tricula burchi Davis, a species from NW Thailand outside the Mekong River drainage. It is not possible to assign aperta to a named genus until the morphologies of numerous other hydrobiid taxa in the Mekong River are unknown. "L." aperta is typically hydrobiid in grade of morphological organization, in the nervous digestive, ctenidial and male reproductive systems. Differences from other hydrobiid taxa are in the female reproductive system and micromorphological features of the digestive tract. "L." aperta and species of Tricula from Thailand have a female reproduction system where sperm enter at the posterior end of the mantle cavity and travel to the bursa copulatrix via a spermathecal duct. These and related traits are the basis for the subfamily Triculinae. Hydrobiid taxa from Europe (Hydrobiinae s.s.) belong in a different phyletic line, where sperm enter the female reproductive system at the anterior end of the mantle cavity and travel via a ciliated groove in the palial oviduct to the bursa copulatrix. "L." aperta, as well as taxa of the Pomatiopsinae (e.g. Oncomelania, Pomatiopsis), differ from most known mesogastropods in lacking a hypobranchial gland. "L." aperta, other triculines, pomatiopsines and hydrobiines, as well as taxa studied in the Bithyniidae, Truncatellidae and Assimineidae differ from other mesogastropods, e.g. Viviparidae, Pleuroceridae, Littorinidae, etc., in that the salivary glands are dorsal to the nerve ring i.e. do not pass through the nerve ring. "L." aperta lives on solid substrata, particularly wood, shells and leaves in the Mekong River from Khemarat, Thailand, to the Cambodian border, 200 river miles downstream. The range probably extends another 100 river miles downstream to Kratie, Cambodia. It is an "r"-selected species by having a high density-independent mortality and using much of its resources for reproduction. The species is a colonizer in a river with severe annual floods. Females live less than 12 months; they apparently lay eggs in late January or February and die. In early March neither adults nor young can be collected. By mid or late March young suddenly flourish. The new generation does not mature until late May or June, after the beginning of the rainy season...

Animals↗
PubMed1975

Distribution of Oncomelania hupensis in the Napu Valley of Central Sulawesi, Indonesia.

Fifteen colonies of Oncomelania hupensis were found near trails transecting the North Lore District, Napu Valley, Central Sulawesi. Habitats were in abandoned rice fields, uncultivated grazing areas for livestock, roadside ditches and, in one case, an actively worked rice field. Marsh grasses, Ischaemum barbatum and Laersia hexandra, were the most common plants in oncomelanid habitats. Other mollusks found in association with O. hupensis were Radix sp., Melanoides sp., Gyraulus sp., Idiopoma sp., Thiara sp., Opeas sp. and Indopyrgus sp. in that order of frequency. Schistosoma japonicum cercariae, as determined by mouse exposures, were shed from snails collected at four foci. In Sulawesi, O. hupensis and S. japonicum were found in high mountain valleys near, or above, 1,000 meters in elevation. Oncomelania hupensis, however, were not found in what appeared to be suitable habitats at lower elevations in the same drainage systems.

Animals↗