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Biomedical subjects

D Holbert

Publications and source records attributed to D Holbert.

At least 37 records · Page 2Linked to original sources
PubMed1988

Effect of carbohydrate ingestion on exercise endurance and metabolism after a 1-day fast.

Fasting before an exercise event has been demonstrated to decrease endurance. The purpose of this study was to investigate whether this decrement in performance after fasting could be reversed by ingestion of a carbohydrate solution before and during exercise. Nine fit male subjects ran to exhaustion at approximately 70% VO2max in two counterbalanced trials. The subjects were fasted for 21 h before both trials, and the trials were arranged so that the subjects ingested either a carbohydrate (CHO) or placebo (PL) solution. Although ratings of perceived exertion were significantly lower in the CHO trial, there were no differences in endurance time to exhaustion in the two trials (102 +/- 8 min in the PL trial and 106 +/- 8 min in the CHO trial). There were no differences between trials for the VO2, heart rate, and blood lactate concentrations. As expected, the blood glucose and insulin concentrations were higher in the CHO trial. The respiratory exchange ratio was significantly higher in the CHO trial at 40 min of exercise and tended to be higher at all other times, suggesting a greater reliance on carbohydrate and less on fat as an energy source. This seemed to be confirmed by the significantly lower plasma glycerol concentration, which suggested less fat mobilization in the CHO trial. Ingestion of a glucose polymer solution increased carbohydrate utilization in fasted subjects, but exercise performance was not improved.

Adult↗
PubMed1988

Intentionality of college students regarding North Carolina's 21-year drinking age law.

The purpose of this study was to examine the intentions of underage students at a southeastern university as to a new 21-year drinking law. Students (N = 440) in introductory health classes were given a questionnaire prior to the law's enactment. Major findings included: 90% were alcohol users, with 85% beginning regular alcohol use by age 18. Only 6% intended to stop drinking, 70% planned to change their location of use, and 22% intended to use other drugs more. Seventy percent intended to obtain alcohol from their friends, and 21% intended to use a false or borrowed identification. Serious questions about potential negative impacts of the law are raised.

Adult↗
PubMed1988

Training and validating the use of geriatric simulated patients.

After presenting four patient roles during an audio-taped final examination of 68 second-year medical students' interview skills, seven geriatric simulated patients evaluated the interview skills of the students. Reviews of randomly-selected audiotapes revealed that the patients were highly consistent and accurate in their evaluations, indicating that geriatric simulated patients may be an untapped resource for medical training.

Aged↗
PubMed1988

Body fat distribution, plasma lipoproteins and the risk of coronary heart disease of male subjects.

Recent studies have related waist to hip ratio (WHR) to the incidence of coronary heart disease (CHD), but the causes underlying this relation are not fully known. The purpose of this study was to determine if waist to hip ratio is associated with the concentration of plasma lipids and apolipoproteins (apoproteins) that predispose individuals to a higher CHD risk. Plasma lipids and apoprotein concentrations were determined in 100 male volunteers, ranging in age from 19-68 yr, and WHR ranging from 0.89-1.09. Significant positive associations were found between WHR, plasma glucose (r = 0.25, P = 0.01), cholesterol (r = 0.21, P = 0.04), LDL cholesterol (r = 0.22, P = 0.03), triglycerides (r = 0.25, P = 0.01) and the ratio of total cholesterol to HDL-cholesterol (r = 0.30, P = 0.002). Negative associations were found between WHR and HDL-cholesterol (r = -0.19, P = 0.05), plasma apoprotein A-I (4 = -0.28, P = 0.005) and the ratio of plasma apoprotein A-I to apoprotein B (r = -0.26, P = 0.01). To determine the extent to which these correlations were independent of age and body fat content, a subsample of 15 pairs matched on age and percent body fat, but differing in WHR was selected from the larger sample. In the group with high WHR (1.06) HDL-cholesterol and apo A-I levels were lower and apo B higher than in the group with low WHR (0.96). Total cholesterol, triglycerides and LDL cholesterol levels in the group with high WHR were also higher but marginally significant statistically. These results show that WHR is associated with plasma lipid and apolipoprotein concentrations that are more predisposing to CHD and that males with male type obesity may be at a higher risk of CHD development than those with female type, regardless of age or degree of obesity.

Adipose Tissue↗
PubMed1987

Note on the choice of statistic for testing hypotheses regarding seasonality.

The Kolmogorov-Smirnov one-sample test and the Pearson chi-square test are discussed regarding their application for testing hypotheses of seasonality in births. This paper addresses some points mentioned in an earlier paper by McCullough and argues that the chi-square procedure may be the better test.

Biometry↗
PubMed1987

Personality traits of smokeless tobacco users and nonusers: a comparison.

This study investigated the personality characteristics of male university students who were either users or nonusers of smokeless tobacco. The hypotheses attempted to determine any differences in personality characteristics between users and nonusers of smokeless tobacco, and examine differences in personality characteristics according to the amount of smokeless tobacco used. A university sample of 289 males revealed 19% (55) prevalence of smokeless tobacco users. Each subject was administered Cattell's Sixteen Personality Factor Questionnaire and a demographic questionnaire. An analysis of variance revealed that smokeless tobacco users exhibited significant differences (p less than .01) in both personality characteristic A (more reserved, less outgoing socially) and personality characteristic I (self-reliant, less sentimental), and significant difference (p less than .05) in personality characteristic Q2 (more conforming, group dependent). No significant differences were noted in personality among persons who used varying amounts of smokeless tobacco.

Adolescent↗
PubMed1987

Prevalence of smokeless tobacco use in Pitt County, North Carolina.

The purpose of this study was to estimate the prevalence of smokeless tobacco use in the largest tobacco-producing county in the United States. A 1-in-100 systematic random telephone sample was taken from the county telephone directory. A total of 280 complete questionnaires were obtained. Results indicate that .40 +/- .042 [p +/- SE(p)] males and .09 +/- .024 of females use smokeless tobacco. The point prevalence for the total population was estimated to be .15.

Adolescent↗
PubMed1986

Career preferences and decision-making habits of first-year medical students.

Few studies that examine the career decisions of medical students have been based upon theories of decision-making. Several theories were used by the present authors to study differences among first-year medical students in North Carolina who preferred family medicine and those who preferred other specialties. Responses by 358 first-year students to a career preferences questionnaire administered in the fall of their freshman year revealed that students who preferred family medicine were more interested than other students in using medicine as a tool to help people. They were equally persistent and thorough in their career decision-making, were at an earlier stage of decision-making, and had less concern with themselves compared with other students. Decision-making theory helps to explain the relationships found in earlier studies between students' characteristics and their specialty preferences. The results of the present study also may explain the reason for the decrease during medical school in the number of students who prefer family medicine as a career. Those results show that first-year medical students who prefer family medicine are at an earlier stage of the decision-making process than other first-year medical students.

Career Choice↗
PubMed1986

Longevity of colonies of Anaplasma marginale in midgut epithelial cells of Dermacentor andersoni.

Colonies of Anaplasma marginale in midgut epithelial cells of experimentally infected Dermacentor andersoni were studied in adult ticks 1, 3, and 6 months old. Longevity of the parasite in ticks was assessed by evaluating its infectivity for splenectomized calves; calves were exposed by feeding ticks and by inoculation of tick gut homogenates. Longevity was also evaluated by determining size, type, and density of colonies in male and female ticks. The effect of incubation (2.5 days at 37 C) on colony density was also examined for ticks at each age period. All methods used to assess longevity of A marginale in ticks (tick transmission, calf inoculation, and histologic studies) indicated a decrease of the numbers of organisms in 6-month-old ticks. Furthermore, when tick gut homogenates from 6-month-old nonincubated ticks were not infectious for susceptible calves, incubation of ticks before dissection restored infectivity of homogenates. Colonies of A marginale were detected in gut tissues of 6-month-old ticks that were not infective; therefore, infectivity of ticks could not be confirmed merely by presence of A marginale colonies.

Anaplasma↗
PubMed1983

Influence of parasitemia level at feeding on development of Anaplasma marginale Theiler in Dermacentor andersoni Stiles.

Four splenectomized dairy calves were inoculated with a Virginia isolate of Anaplasma marginale Theiler and served as an infective source (donor) for laboratory-reared Dermacentor andersoni Stiles nymphs. Two donor calves developed higher parasitemias during tick feeding than did the 2 other donor calves. One month after molting, adult ticks were incubated at 37 C for 2.5 days to stimulate development of colonies of A marginale, and homogenates of gut were made from ticks fed on each donor calf. Eight susceptible, splenectomized dairy calves (2 per donor calf) were each inoculated IV with the gut homogenates collected from 50 adult ticks and were monitored for patent A marginale infection. Gut tissues from these same groups of ticks were processed for histologic studies. Homogenates from ticks infected on donor calves with lower parasitemias caused infections with longer prepatent periods (av, 43.25 days) than did similar homogenates made from ticks infected by feeding on donor calves with higher parasitemias (av, 31.0 days). Also, sections of gut tissues from ticks infected at the lower parasitemias contained fewer (av, 0.65) colonies/0.001 mm2 of tissue examined than did those from ticks infected at higher parasitemias (av, 6.31).

Anaplasma↗
PubMed1982

Morphologic characteristics of colonies of Anaplasma marginale Theiler in midgut epithelial cells of Dermacentor andersoni Stiles.

Colonies of Anaplasma marginale Theiler were studied in midgut epithelial cells of adult Dermacentor andersoni Stiles that were infected as nymphs. Colonies were categorized by light microscopy into 5 morphologic types that appear to represent stages in a developmental sequence. The mean diameter of the colony types ranged from 5.64 micrometer to type 1 colonies to 10.49 micrometers of type 5 colonies. Representatives of each colony type were selected by light microscopy and were sectioned for examination by electron microscopy. The morphologic features of individual A marginale organisms within colony types varied and included: (i) small electron-dense forms, (ii) larger reticulated forms, (iii) pleomorphic reticulated forms, and (iv) small particles. Types 1 and 2 colonies contained small, electron-dense forms. Type 3 colonies contained electron-dense forms, early reticulated forms, and small particles that were often outside of the parasite's limiting membrane. Type 4 colonies contained many reticulated forms that often had small particles within cell membranes. Type 5 colonies contained fewer well-formed reticulated forms than did type 4 and, in some cases, large masses of pleomorphic reticulated forms.

Anaplasma↗
PubMed1982

Influence of increased temperature on Anaplasma marginale Theiler in the gut of Dermacentor andersoni stiles.

Three splenectomized dairy calves were inoculated with a Virginia isolate of Anaplasma marginale Theiler and served as an infective source for laboratory-reared Dermacentor andersoni Stiles nymphs. One month after molting, groups of adult ticks were incubated at 37 C for 0, 1.5, 2.5, and 7 days. Gut homogenates were made from ticks representing each incubation period. Twenty-four susceptible, splenectomized dairy calves were each inoculated IV with a gut homogenate extracted from 50 adult ticks and monitored for patent A marginale infection. The prepatent periods were determined and used as a measure of infectivity. Gut homogenates made from ticks that had been incubated for 2.5 days produced infections with the shortest prepatent periods, an average of 28.5 days among 3 trials.

Anaplasma↗
PubMed1975

The effects of parity, litter size, season, and breeding protocol on the number of DBA/2J Ten mice available for weaning.

Data on the reproductive behavior of DBA/2J Ten mice, collected from October 1970 through March 1973 and utilizing a 2-female, 1-male breeding system, with the mice remaining together throughout their reproductive life indicates: a) Litter size tends to increase through the fourth litter, the first litter being much smaller than successive litters; b) Survival rates of litters with 2--4 pups increase with successive deliveries; c) Survival rates of litters with 5--9 pups are approximately the same regardless of parity; d) There is a circannual rhythm in the number of pups available for weaning da 21, which is attributable to changes in postnatal viability. Data collected using a breeding pen system, with isolation of females pre- and post-delivery (March 1973 to March 1974) indicates: a) There is a reduction in live litter sizes in later litters with this system; b) There is a large reduction in the proportion of pups surviving to weaning with this system when compared with the other breeding system.

Animals↗