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Biomedical subjects

J L Walker

Publications and source records attributed to J L Walker.

154 records · Page 9Linked to original sources

Neurological and behavioral toxicity of kryptopyrrole in the rat.

Ten rats were given 9.1 to 82 mg/kg of 2,4-dimethyl-3-ethylpyrrole (kryptopyrrole) and the behavioral and electroencephalographic effects were studied. Kryptopyrrole was found to decrease EEG voltage, disrupt synchronization and induce abnormal spiking at a variety of cortical sites. Intermittent periods of low frequency hypersynchronous EEG activity was consistently elicited by kryptopyrrole. These waves bear a resemblance to the hypersynchronous EEG patterns associated with hallucinatory agents such as LSD-25. Marked behavioral alterations were observed following the initial injection including ataxia, hyperventilation, locomotor depression and catelepsy. Kryptopyrrole causes major central nervous system dysfunction, and these findings are discussed in the context of a drug-induced model of psychoses.

Animals↗

Fluid replacement preferences in heat-exposed workers.

This study examined fluid intake, weight changes, and palatability of water and a carbohydrate-electrolyte (ECHO) beverage in two groups of eight subjects performing 4 hours of simulated industrial work while wearing impermeable protective clothing. Subjects also rated the palatability of a flavorless orange-colored water and four commercially available orange-flavored fluid-replacement drinks. Subjects worked 30 min at 300 Kcal/hour (moderate work rate), followed by 30 min of rest for a total of 4 hours in each of three environments: 18, 23, 27 degrees C wet bulb globe temperature (WBGT). Eight subjects drank water and eight drank an ECHO beverage (Drink 1). Mean sweat production was similar between groups at each WBGT, (p > 0.05). Mean weight changes expressed as percentage of total body weight for the water-drinking group were -0.25 (+/- 0.16) kg in 18 degrees C, -0.55 (+/- 0.09) kg in 23 degrees C, and -0.93 (+/- 0.13) kg in 27 degrees C. Mean weight changes for the ECHO-drinking group were 0.49 (+/- 0.12) kg in 18 degrees C, 0.13 (+/- 0.12) kg in 23 degrees C, and -0.02 (+/- 0.14) kg in 27 degrees C. Each change was significantly different from that of the water-drinking group at the same temperatures (p < 0.05). Mean pre- to post-trial palatability rating results for all temperatures revealed differences in taste perception with strong preferences for Drinks 1 and 2 (pre to post): Drink 1, 3.8 to 3.6; Drink 2, 3.8 to 3.7; Drink 3, 3.0 to 2.7, Drink 4 (water), 3.2 to 3.0, and Drink 5, 2.1 to 1.6. Drinks 1 and 2 were rated significantly more palatable (p < 0.05) than Drink 3. All drinks had a reduced flavor appeal from 3.18 (+0.96) preratings to 2.92 (+1.01) postratings (p < 0.05). Mean voluntary consumption during work across the three temperatures was 1561.5 mL (+/- 720.1) for ECHO versus 1062.7 mL (+/- 666.4) for water (p = 0.054). The water group experienced greater weight loss than the ECHO group, suggesting a greater rate of dehydration when water was used for fluid replacement.

Adult↗

Use of Ilizarov external fixator to treat joint pterygia.

Joint pterygia are rare conditions characterized by joint-flexion contractures and webbing of the overlying skin and subcutaneous structures. Treatment is difficult because the neurovascular bundle is often displaced into the web, and only moderate success has been reported with past treatment options. A retrospective review was performed on five patients with six involved joints: two antecubital pterygia and four popliteal pterygia. The Ilizarov technique was used for gradual correction of pterygia through the joint (arthrodiastasis). Primary treatment goals included improvement in functional extension, hygiene independence, and cosmesis. Ambulation was also an objective in the patients with popliteal pterygia. For inclusion in this study, a minimum of 2 years' follow-up was required after the device was removed. Preoperative goals were met in four of the six joints. Initial improvement in total arc of motion was noted; however, some regression was common. Complications were frequent, and there was a learning curve for proficiency with the Ilizarov technique. We believe that the Ilizarov technique provides a treatment option for antecubital and popliteal pterygia.

Child↗

Hip abnormalities in children with Charcot-Marie-Tooth disease.

Hip dysplasia was recently observed in association with Charcot-Marie-Tooth disease (CMT). We retrospectively reviewed available radiographs of 74 of 100 children with clinically and electrodiagnostically proven CMT and noted six cases of hip dysplasia. Minor hip abnormalities, most commonly increased neck shaft angles, were noted in 21 other patients. Type I usually causes more weakness and had more hip dysplasia than type II. A female predominance was noted but may have resulted from sampling of more immature radiographs in males. Most dysplasia was asymptomatic and was detected only on screening radiographs.

Adolescent↗

Gender differences in attrition from orthopaedic surgery residency.

We conducted a national survey of orthopaedic surgery residency program directors regarding resident attrition. Female residents had a statistically higher attrition rate than male residents (p < 0.001). The female early withdrawal residents left voluntarily and for personal reasons more often than their male counterparts. These tendencies, however, were not statistically significant. We feel that more in-depth counseling of female medical students and increased mentoring for women in orthopaedic residency could help prevent this attrition.

Career Choice↗