Biomedical subjects

J M Risser

Publications and source records attributed to J M Risser.

26 records · Page 2Linked to original sources

PubMed1990

Bone density in eumenorrheic female college athletes.

Information is limited on the effect of exercise on bone density in young eumenorrheic athletes. We studied 12 Caucasian intercollegiate volleyball players (V), nine basketball players (B), ten swimmers (S), and 13 non-athletes (N) with bone density measurements by photon absorptiometry of their calcaneus and lumbar spine (L2-L4). The effect of athletic status on bone density was analyzed by multivariate analysis of covariance, with height and weight as covariates. The bone densities reported below are mean +/- SE, adjusted for the covariates; units = g.cm-2, P less than 0.005. The swimmers had a significantly lower mean density in the lumbar spine than all other groups; the non-athletes' mean density was also lower than that of volleyball players (V = 1.31 +/- 0.03, B = 1.26 +/- 0.04, N = 1.18 +/- 0.03, S = 1.05 +/- 0.03). The volleyball and basketball players' mean calcaneal densities were greater than those of the swimmers and non-athletes (V = 0.530 +/- 0.017, B = 0.564 +/- 0.023, N = 0.438 +/- 0.018, S = 0.375 +/- 0.019). The higher bone densities for athletes in vertical weight-bearing activities are consistent with some but not all published data. The swimmers' low bone density in the lumbar spine, less than published values for amenorrheic runners, was unexpected.

Absorptiometry, Photon↗

PubMed1989

Influence of the D-2 dopamine receptor agonist quinpirole on the odor detection performance of rats before and after spiperone administration.

The influence of five doses of the D-2 receptor agonist quinpirole (0.025, 0.05, 0.075, 0.10, and 0.20 mg/kg IP) on the odor detection performance of 21 adult male Long Evans rats was assessed using high precision olfactometry and a go/no-go operant task. Additionally, ten rats were pre-treated with the D-2 receptor antagonist spiperone (0.62 mg/kg IP) and their performance monitored following quinpirole administration. Treatments were administered every third day in a counterbalanced order, with the quinpirole injections occurring 15 min before, and the spiperone injections 35 min before, the 260-trial test sessions. Quinpirole injection resulted in a dose-dependent decrease in odor detection performance, as measured by the percentage of correct trials and by the non-parametric signal detection sensitivity index SI. Prior treatment with spiperone eliminated these effects. Dose-related influences of quinpirole on (a) the average latency to initiate a detection response (i.e., the S + response latency), (b) the total session duration, and (c) the number of aborted trials were also eliminated or greatly attenuated by prior spiperone injection. These results suggest that D-2 receptors may be involved in the modulation of odor detection performance and related behaviors.

Acetates↗

PubMed1989

No influence of adrenalectomy on measures of taste sensitivity in the rat.

The influence of adrenalectomy on the taste sensitivity and responsivity of Long-Evans rats to sodium chloride and sucrose tastants presented separately and in mixtures was examined using high precision gustometry, computer-controlled go/no-go operant procedures, and nonparametric signal detection measures. Relative to baseline levels, adrenalectomized rats' plasma corticosterone levels decreased by 328% while sodium chloride and water consumption increased by 548% and 165%, respectively. The same measures remained unchanged in sham-operated animals. Taste sensitivity and responsivity to sodium chloride and sucrose did not differ between adrenalectomized and sham-operated animals and discrimination performance remained the same between the groups as well. The present results support and extend previous findings that adrenalectomy and the resultant corticosteroid deficiency does not influence taste sensitivity or responsivity in the rat.

Adrenal Cortex↗

PubMed1988

Iron deficiency in female athletes: its prevalence and impact on performance.

The prevalence of iron deficiency and its impact on performance have not been adequately investigated in non-endurance athletes. This study evaluated these factors in 100 female intercollegiate athletes in various sports, and in 66 non-athletes. All subjects had determinations of hemoglobin, ferritin, and transferrin saturation. Athletes reported on diet, menses, and symptoms. Athletes and coaches described mood and performance. Iron-deficient athletes were treated with iron; others received placebo. The same data were collected at season's end. Initially 31/100 (31%) athletes had iron deficiency (ferritin less than 12 ng.ml-1; transferrin saturation less than 16%, or both) compared to 30/66 (45.5%) controls (not statistically significant). Compared to normal athletes, iron-deficient athletes did not have more symptoms of iron deficiency or differences in mood state, but they considered their performance to be worse (P less than 0.05). Their total iron intakes were similar, as were menstrual blood losses. At re-evaluation, 7/45 (15.6%) initially normal athletes were iron-deficient; 14/22 (63.6%) initially iron-deficient athletes were normal. Athletes receiving an iron supplement and their coaches did not report a greater improvement in performance or mood than athletes receiving a placebo. Female college athletes frequently had iron deficiency that could be successfully treated during the season, while some untreated normal athletes became iron-deficient. Iron deficiency and its treatment had no significant impact on symptoms or mood, but affected subjective assessment of performance.

Administration, Oral↗

PubMed1987

Nipple attachment and survival in neonatal olfactory bulbectomized rats.

Seven-day-old rat pups were olfactory bulbectomized, cortical lesioned, or sham lesioned, tested for nipple attachment 24 hr after surgery, then housed with their dam and weighed daily for the next 7 days. On the basis of histological findings the bulbectomized animals were divided into two subgroups: Those with removal of all olfactory bulb tissue (n = 9) and those in which some cellular elements remained in the lesioned area (n = 7). There were no differences between sham and cortical lesioned groups for nipple attachment behavior or weight gain. The completely bulbectomized pups did not show nipple attachment, lost weight each day, became moribund and had to be sacrificed by the fifth postoperative day. Deficits in incompletely bulbectomized pups were somewhat less severe and each of these survived and maintained or gained weight in the latter part of the test period. These results suggest that suckling may be critically dependent upon olfaction in 8 day or older pups and that significant savings in this behavior may be mediated by small remnants of olfactory bulb tissue.

Animals↗

PubMed1987

Suckling behavior in rat pups with lesions which destroy the modified glomerular complex.

Seven-day-old sham operated rats and those with lesions of the rostral medial, lateral, or posterior medial olfactory bulbs were tested postoperatively for nipple attachment behavior and weighed daily. The posterior medial lesions included the area of the modified glomerular complex (MGC), a region of the bulb that has been implicated in suckling behavior. There were no significant differences among groups in nipple attachment latency or weight gain. These results do not support the notion that the MGC is essential for suckling in neonatal rats.

Animals↗

PubMed1987

The horizontal-vertical illusion: independence of line bisection and a comparison line.

Undergraduate students in social science and architecture did not differ in their accuracy of adjusting the vertical lines of L and inverted-T figures to be equal to a 1-in. horizontal line (the adjustment task) or in producing a 1 in. long line in the vertical or horizontal plane on a blank sheet of paper (the production task). In the adjustment task vertical lines were made significantly shorter than the horizontal comparison line and the shortening of the vertical line was significantly greater for the inverted-T than for the L-figure. In the production task lines drawn in the horizontal plane did not differ significantly from 1 inch but those drawn in the vertical plane were significantly shorter than 1 inch. Further, the magnitude of this error was equal to that obtained with the inverted-T figure. These results demonstrate that, while line bisection (the bisection of the horizontal by the vertical in the inverted-T figure) contributes to the horizontal-vertical illusion, the illusion clearly exists in the absence of a comparison line and can be accounted for as an overestimation of the vertical line.

Adult↗

PubMedDate not supplied

A comparison of fat-free mass estimates in men infected with the human immunodeficiency virus.

BACKGROUND: Loss of lean-body mass has been found to be predictive of death from wasting in HIV-infected individuals. Several clinically applicable, noninvasive methods for estimating body wasting are available, but the comparability of these methods is not known. The objective of this study was to assess the agreement between estimates of lean-body mass in HIV-infected men. METHODS: Lean-body mass was measured by bioelectrical impedance assessment, by prediction equations that used anthropometric measurements, and by total body electrical conductivity as the comparison method in 27 outpatient HIV-infected men seen at the Houston Veterans Affairs Special Medicine Clinic. Agreement was assessed by comparing the difference between two methods (the bias) with the mean of those two methods. This statistical approach evaluates whether two methods are similar enough that measurements from one might accurately replace those of the other. RESULTS: The mean +/- SE for lean-body mass were 55.98 +/- 1.96 kg for total body electrical conductivity and 55.18 +/- 1.27 kg for bioelectrical impedance assessment; they ranged from 55.18 +/- 1.27 to 63.71 +/- 1.89 kg for the prediction equations. CONCLUSIONS: In individual subjects, no alternate method gave estimates of lean-body mass that were the same as estimates from total body electrical conductivity. One prediction equation (Brozek) gave estimates that might be useful for following changes in fat-free mass over time because the bias did not change substantially for increasing values of lean-body mass. On the other hand, because there were no statistically significant differences between the mean lean-body mass estimates by total body electrical conductivity and those measured by bioelectrical impedance assessment or a prediction equation on the basis of body mass index, the latter two methods might be useful in assessing lean-body mass in groups.

Adult↗