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Biomedical subjects

J J Thomas

Publications and source records attributed to J J Thomas.

32 records · Page 2Linked to original sources
PubMed1966

Interactions of oxygen at high pressure and radiation in Drosophila.

Oxygen at high pressure (OHP) and X-irradiation can interact in the fruit fly Drosophila melanogaster to potentiate toxic actions characteristic of one agent alone. 1000 kvp X-irradiation in doses of 30, 60, and 75 kr accelerated the acute immobilization of young male Drosophila by oxygen at 7.8 atm, up to rates twice that observed with such oxygen pressure alone. X-irradiation alone in these dosages did not acutely immobilize the Drosophila. X-irradiation during exposure to 7.8 atm pO(2) was more effective and consistent in producing this potentiation than was X-irradiation that preceded exposure to OHP. Acute OHP toxicity in young female Drosophila was not potentiated by 75 kr of X-irradiation. On the other hand, shortening of the life span of young male Drosophila by the above doses of X-irradiation was augmented significantly by a concurrent 40 min exposure to OHP (which alone did not significantly decrease life span). This shows, for the first time, that oxygen can affect not only the acute effects of radiation, but also the residual irreversible effects indicated by the life span shortening.

Animals↗
PubMedDate not supplied

Treadmill exercise during adenosine infusion is safe, results in fewer adverse reactions, and improves myocardial perfusion image quality.

BACKGROUND: Combining low-level treadmill exercise with adenosine infusion may result in fewer bradyarrhythmic complications by increasing sympathetic tone and may improve myocardial perfusion image quality by decreasing background activity. METHODS: Patients referred for outpatient pharmacologic stress myocardial perfusion imaging performed simultaneous treadmill exercise (mean 2.2 metabolic equivalents) throughout 6-minute adenosine infusion (adenosine-exercise n = 507). Patients unable to exercise and those with left bundle branch block received adenosine infusion alone (adenosine-nonexercise n = 286). Adverse reaction data were collected on all patients and compared by sex. Background-to-target activity was calculated in a blinded fashion on 200 randomly selected patients. RESULTS: During the period from April 1996 to December 1998, 507 patients (64%) underwent adenosine-exercise testing, whereas 286 (36%) underwent adenosine-nonexercise testing. Hypotensive and arrhythmic (atrioventricular block, sinus bradycardia, and new onset atrial fibrillation or flutter) adverse reactions occurred less often during adenosine-exercise than during adenosine-nonexercise. Neither death nor myocardial infarction occurred in either group. In the adenosine-exercise group, 2.8% of patients experienced an adverse reaction versus 5.6% of the adenosine-nonexercise group (P = .04). The reduction in adverse reactions occurred in both men and women, although women had significantly more adverse reactions than men (5.7% vs 1.8%, P = .004). Liver/heart and gut/heart ratios were lower in the adenosine-exercise group (1.05+/-0.42 vs. 1.21+/-0.55 , P = .01; 0.61+/-0.21 vs. 0.69+/-0.24, P = .03, respectively). CONCLUSIONS: Compared with adenosine infusion alone, combining low-level treadmill exercise with adenosine in outpatients is safe, better tolerated, and improves image quality. Women were more likely to experience adverse reactions than men.

Adenosine↗
PubMedDate not supplied

Materials-based, imagery-based, and rote exercise occupational forms: effect on repetitions, heart rate, duration of performance, and self-perceived rest period in well elderly women.

OBJECTIVES: This study extends previous research that contrasted occupational forms with elderly persons living in institutions to include elderly women living independently. In addition to differences in number of repetitions elicited, the current study measured heart rate response and perceived rest period duration. METHOD: Forty-five women over the age of 65 years were randomly assigned to one of three occupational forms: materials based (kicking a balloon), imagery based (kicking an imaginary balloon), and rote exercise (performing a kicking movement without a balloon or imagery prompt). Subjects were instructed to perform the assigned lower-extremity movement until they fatigued and after a self-determined period of rest indicated when they felt able to do another set of movements. Dependent variables included number of repetitions of movement, heart rate (at baseline, at completion of movements, at end of rest period), duration of movement, and self-perceived rest period. Group means for each variable were compared using analyses of variance. RESULTS: Groups showed no significant difference in baseline and demographic data. Subjects in the materials-based occupational form performed significantly more repetitions and required a significantly longer self-perceived rest period than subjects in the imagery-based and rote exercise forms. There were no significant differences among the groups for heart rate response. Duration of movement and number of repetitions variables were strongly correlated (r = .95), indicating lack of independence. CONCLUSIONS: The materials-based occupational form elicited a quantitatively different performance than the other forms. Given the relatively fuller experience (i.e., interaction with an object, clear objective) of the materials-based form, an occupational form that has added meaning for the person appears to result in enhanced performance when compared with forms that lack strong meaning and suggest more limited purposes.

Aged↗
PubMedDate not supplied

An electromyography study of wrist extension orthoses and upper-extremity function.

OBJECTIVE: This study examined the effect of commonly used long and short styles of commercially produced wrist extension orthoses on the activity of the proximal muscles of the shoulder and elbow and on wrist flexor and extensor muscle activity. METHOD: While 17 women between 22 and 40 years of age (M = 26.6) performed a specified movement wearing each of the two styles of orthosis and without an orthosis, their motor unit recruitment of five proximal joint muscle groups, wrist extensors, and wrist flexors was measured by surface electromyography. RESULTS: Motor unit recruitment was significantly greater in both orthosis conditions for four of five proximal muscles and for wrist flexors. There were no significant differences between the short and long orthosis conditions for proximal muscle groups. CONCLUSION: Wearing a wrist extension orthosis appears to place additional stress on the proximal joint musculature beyond that found without splint use. The study has implications for the prescription of wrist extension orthoses, especially for patients whose proximal joints are already compromised.

Adult↗
PubMedDate not supplied

Perceived risk as a constraint on occupational performance during hot and cold water pouring.

OBJECTIVE: Occupational therapists are interested in quality of movement under different environmental conditions. It has been shown that during reaching tasks, the physical aspects of the objects to be grasped can influence the quality of movement. This study investigated whether perceived risk (water temperature) affected the quality of movement during a pouring task. METHOD: In a counterbalanced, repeated measures design, 56 participants (M = 27.1 years, SD = 7.4 years) poured hot, then cold water to prepare hot and cold beverages. Dependent variables included movement time, displacement, peak velocity, percentage of movement time to peak velocity, and movement units. Data were analyzed with paired t tests. RESULTS: Participant performance in displacement and movement time was significantly different when considering the entire pouring task for both the hot and the cold conditions (ps < .05). In addition, significant differences were found in the discrete movement "sub-portions" of the pouring task (ps < .05). CONCLUSION: Perceived risk is an element of meaning that the occupational therapist can consider in providing the person with just enough challenge to facilitate successful performance. By varying the amount of perceived risk in the occupational form, the therapist can help the person experience and develop the range of movement strategies required by everyday occupations. Future research is needed to corroborate these findings in simple and more complex occupations as well as to examine perceived risk in special populations.

Activities of Daily Living↗