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Biomedical subjects

B Leonard

Publications and source records attributed to B Leonard.

13 recordsLinked to original sources
PubMed1995

Effects of cooperative learning groups during social studies for students with autism and fourth-grade peers.

We investigated the use of cooperative learning groups as an instructional strategy for integrating 2 students with autism into a fourth-grade social studies class. Baseline consisted of 40 min of teacher-led sessions including lecture, questions and discussion with students, and the use of maps. The intervention condition consisted of 10 min of teacher introduction of new material, followed by cooperative learning groups that included tutoring on key words and facts, a team activity, and a whole class wrap-up and review. An ABAB design showed increases for target students and peers for the number of items gained on weekly pretests and posttests, the percentage of academic engagement during sessions, and durations of student interaction during the intervention.

Autistic Disorder↗
PubMed1995

Interactions between location and task affect the spatial and directional firing of hippocampal neurons.

When rats forage for randomly dispersed food in a high walled cylinder the firing of their hippocampal "place" cells exhibits little dependence on the direction faced by the rat. On radial arm mazes and similar tasks, place cells are strongly directionally selective within their fields. These tasks differ in several respects, including the visual environment, configuration of the traversable space, motor behavior (e.g., linear and angular velocities), and behavioral context (e.g., presence of specific, consistent goal locations within the environment). The contributions of these factors to spatial and directional tuning of hippocampal neurons was systematically examined in rats performing several tasks in either an enriched or a sparse visual environment, and on different apparati. Place fields were more spatially and directionally selective on a radial maze than on an open, circular platform, regardless of the visual environment. On the platform, fields were more directional when the rat searched for food at fixed locations, in a stereotypic and directed manner, than when the food was scattered randomly. Thus, it seems that place fields are more directional when the animal is planning or following a route between points of special significance. This might be related to the spatial focus of the rat's attention (e.g., a particular reference point). Changing the behavioral task was also accompanied by a change in firing location in about one-third of the cells. Thus, hippocampal neuronal activity appears to encode a complex interaction between locations, their significance and the behaviors the rat is called upon to execute.

Animals↗
PubMed1994

NG-Nitro-L-arginine protects against ischaemia-induced increases in nitric oxide and hippocampal neuro-degeneration in the gerbil.

To assess the effects of the nitric oxide synthase inhibitor NG-Nitro-L-arginine on behavioural, biochemical and histological changes following global ischaemia, the Mongolian gerbil was used. Ischaemia was induced by bilateral carotid occlusion for 5 min. NG-Nitro-L-arginine was administered i.p. at either 1 or 10 mg/kg 30 min, 6, 24, and 48 h after surgery. 5 min bilateral carotid occluded animals were hyperactive 24, 48 and 72 h after surgery. NG-Nitro-L-arginine caused some attenuation in this hyperactivity. The activity of nitric oxide synthase was increased in the cerebellum, brain stem, striatum, cerebral cortex and hippocampus of 5 min bilateral carotid occluded animals. NG-Nitro-L-arginine reversed the increase in nitric oxide synthase activity in all brain regions. Extensive neuronal death was observed in the CA1 layer of the hippocampus in 5 min bilateral carotid occluded animals 96 h after surgery. NG-Nitro-L-arginine significantly protected against the neuronal death of cells in the CA1 layer.

Amino Acid Oxidoreductases↗
PubMed1991

Induction of chromosome changes by metal compounds in cultured CHO cells.

The effect of 4 metal salts on the induction of chromosome aberrations and sister chromatid exchange (SCE) in cultured Chinese hamster ovary (CHO) cells was investigated. It was observed that CdCl2, NiCl2, CrO3 and HgCl2 were effective in causing various types of chromosome aberrations. The percentages of abnormalities increased with increasing doses of the metals used. These metal compounds also raised the SCE rates compared to 5-bromo-2'-deoxyuridine controls. The importance of rapid screening of potentially hazardous metals is described.

Animals↗
PubMed1985

Partial neuromuscular blockade and cardiovascular responses to static exercise in man.

In human subjects sustained static contractions of the quadriceps femoris in one leg were performed with the same absolute and the same relative intensity before and after partial neuromuscular blockade with either decamethonium or tubocurarine which reduced strength to about 50% of the control value. During the contractions performed with the same absolute force, the magnitude of the cardiovascular responses (heart rate and blood pressure) was greater during neuromuscular blockade than during control contractions. During the contractions involving the same relative force the magnitude of the cardiovascular responses was almost the same with and without neuromuscular blockade. These findings were independent of the drug used. The metabolic part of the exercise pressor reflex was assessed by the application of an arterial cuff 1/2 min before cessation of exercise and for the following 3 min of rest. Although heart rate and blood pressure decreased after cessation of exercise, application of the tourniquet resulted in higher post-exercise values and this effect was seen both with and without neuromuscular blockade. Muscle biopsies from the subjects' m. vastus lateralis were analysed for fast- and slow-twitch fibre composition showing 27-66% slow-twitch fibres. No correlation was found between cardiovascular responses to static exercise, with or without neuromuscular blockade, and fibre type predominance. The results suggest that the involvement of fast- or slow-twitch muscle fibres does not play a dominant role in the cardiovascular responses to static exercise in man. Both central command and reflex neural mechanisms are of importance, and it appears that these two control mechanisms are redundant and that neural occlusion may be operative. However, when partial neuromuscular blockade induces a disproportion between an increase in central command and a constant or decreasing muscle tension and metabolism, the larger signal arising from central command determines the magnitude of the cardiovascular responses.

Adult↗
PubMed1983

Further studies of the turnover of dog antithrombin III. Study of 131I-labelled antithrombin protease complexes.

Fresh plasma containing 131I-antithrombin III (*I-AT) was coagulated and incubated at 37 degrees C for 2 hr. A "complex peak," separated on heparin-agarose contained AT and *I-AT antigen but no heparin cofactor activity. Crossed immunoelectrophoresis showed only AT complexes. SDS PAGE showed 80% of the *I-AT in a major band (approximately 80,000 daltons), 15% in a minor band (approximately 100,000 daltons) and the rest in trace bands (approximately 60,000 and/or 115,000 daltons). Ammonia treatment of the complex peak released alpha-thrombin. After i.v. injection 80% of the complexed *I-AT, chiefly as the major band, left the plasma with t 1/2 approximately 15 min and was almost immediately catabolized to low molecular weight breakdown products. A major catabolic site was the liver. A simple kinetic model describes the findings approximately.

Animals↗
PubMedDate not supplied

Financial and time costs to parents of severely disabled children.

This paper considers the financial burden of parents caring for severely disabled children. A model to predict parents' out-of-pocket expenses and caregiving time demands is described. Discriminant analysis correctly classified high and low group membership for out-of-pocket expenses and caregiving time at 72 percent and 77 percent, respectively. Expected rates were 50 percent. Time spent caregiving was the best predictor for out-of-pocket expenses, and out-of-pocket expenses was the best predictor of caregiving time. A need-based approach for the distribution of resources that recognizes and adjusts for caregiving time and out-of-pocket costs is recommended.

Adolescent↗
PubMedDate not supplied

Zuni Diabetes Project.

Widespread type II diabetes among North American Indians and certain other populations is a relatively recent medical phenomenon. Increased prevalence of diabetes appears to be related to sudden cultural shifts toward sedentary lifestyle and increased caloric intake. These changes, super-imposed on a genetic predisposition to diabetes, pose a community health threat to the Zuni and similar populations. Regular aerobic exercise is clearly beneficial to most type II diabetics. The key public health issue is how to establish community participation in effective aerobic activity. The Zuni Diabetes Project, fully described here, serves as a model in this respect.

Adult↗