An application of randomization for detecting evidence of thermoregulation in timber rattlesnakes (Crotalus horridus) from northwest Arkansas.

Most reptiles maintain their body temperatures within normal functional ranges through behavioral thermoregulation. Under some circumstances, thermoregulation may be a time-consuming activity, and thermoregulatory needs may impose significant constraints on the activities of ectotherms. A necessary (but not sufficient) condition for demonstrating thermoregulation is a difference between observed body temperature distributions and available operative temperature distributions. We examined operative and body temperature distributions of the timber rattlesnake (Crotalus horridus) for evidence of thermoregulation. Specifically, we compared the distribution of available operative temperatures in the environment to snake body temperatures during August and September. Operative temperatures were measured using 48 physical models that were randomly deployed in the environment and connected to a Campbell CR-21X data logger. Body temperatures (n=1,803) were recorded from 12 radiotagged snakes using temperature-sensitive telemetry. Separate randomization tests were conducted for each hour of day within each month. Actual body temperature distributions differed significantly from operative temperature distributions at most time points considered. Thus, C. horridus exhibits a necessary (but not sufficient) condition for demonstrating thermoregulation. However, unlike some desert ectotherms, we found no compelling evidence for thermal constraints on surface activity. Randomization may prove to be a powerful technique for drawing inferences about thermoregulation without reliance on studies of laboratory thermal preference.

Alterations in the in vivo torque-velocity relationship after Achilles tendon rupture. Further evidence of speed-specific impairment.

The torque-velocity relationship of the ankle plantar flexors was determined in 31 patients recovering from Achilles tendon rupture. Isokinetic torque measurements were made at speeds of 0 to 240 degrees.s-1 at 24 degrees.s-1 intervals. Measurements of instantaneous torque were made at joint angles corresponding to neutral and 10 degrees plantar flexion. In 17 patients treated surgically, there was little difference between the injured and the uninjured leg. In contrast, patients who were treated by casting exhibited major differences between the injured and uninjured legs. This difference became amplified when torque values at 10 degrees plantar flexion were compared. Additionally, the differences between the injured and uninjured legs were not uniform. The differences in torque were greatest at slow test speeds and least at fast test speeds. Comparisons of the injured surgical and injured nonsurgical legs demonstrated that the surgical group had significantly greater torque. This difference was also speed specific. These findings demonstrate that both groups exhibited speed-specific impairment with the loss of muscle strength being greatest at slow speeds. Also, the degree of impairment was dependent on the ankle position at which torque was measured. Surgical treatment provides better functional results as observed by the torque-velocity relationship.

A comparison of foot-switch and EMG analysis of varus deformities of the feet of children with cerebral palsy.

Fifty-one children with cerebral palsy who were candidates for surgery for equinovarus deformities of the foot had their gait evaluated by means of foot-switches and electromyography to determine the contribution of the anterior tibialis and posterior tibialis muscles to the deformity. Seven EMG patterns and five foot-switch patterns were identified, but there was no correlation between the EMG and foot-switch patterns. Foot-switch data alone could not identify the deforming muscles or their patterns, so are not adequate for planning surgical correction of varus feet of children with cerebral palsy.

Body composition of Peruvian children with short stature and high weight-for-height. I. Total body-water measurements and their prediction from anthropometric values.

Total body water (TBW) was measured by 18O dilution in 139 undernourished, preschool Peruvian children with high weight-for-height. Values for TBW as a percent of body weight were relatively high, averaging 67.4 +/- 6.4%. Depending upon the method of calculation, mean values for the sample population for percent fat ranged from 9.4-18.5%. Regression of TBW on lean body mass suggested that hydration of the fat-free body was higher than for normally nourished children of comparable age. Thus, the increased weight-for-height in these children did not result from increased fat tissue, but from increased hydration of the fat-free body. TBW was most highly correlated with height and weight, both with r = 0.95. Equations predicting TBW from either height or weight were significantly different from those developed by other investigators to predict TBW for normal, well-nourished American children.

Total parenteral nutrition-related cholestasis in infants.

An epidemiological study was conducted to estimate the proportion of infants on total parenteral nutrition (TPN) who developed cholestasis and to identify risk factors associated with the development of this disease. Data were abstracted from medical records of 624 infants less than or equal to 30 days of age who were treated with TPN. A case of TPN-related cholestasis was defined as an infant whose serum level of direct bilirubin was greater than or equal to 1.5 mg/dl subsequent to initiation of TPN. Risk factors were assessed using multiple logistic regression analysis. Forty-six of 624 infants in the cohort (7.4%) were classified as having TPN-related cholestasis. The multivariable analysis indicated that cholestasis was associated with intracranial hemorrhage, patent ductus arteriosus, sepsis and gastrointestinal conditions that require surgery. Two distinct processes appear to have occurred: in infants who experienced patent ductus arteriosus or intracranial hemorrhage (conditions associated with hypoxia) where TPN may be the necessary trigger for the development of cholestasis, and in infants with gastrointestinal conditions requiring surgery or sepsis, where cholestasis may develop with or without parenteral infusions.

Achilles tendon rupture. A review of the literature comparing surgical versus nonsurgical treatment.

Rupture of the Achilles tendon is being reported more frequently. Results published in the literature in the past 25 years were reviewed to determine the overall outcome comparing surgical with nonsurgical treatment and to identify areas needing further study. The rerupture rate for surgically treated patients was 12/777 or 1.54%, while that for nonsurgically treated patients was 40/226 or 17.7%. The complication rate for surgical treatment was 155/775 or 20.0%, while the nonsurgical rate was 2/20 or 10%. Most complications did not affect the eventual outcome. Time lost from work averaged 13 weeks for surgically treated patients and nine weeks for nonsurgically treated patients. Results of tests for functional recovery after treatment were slightly better for surgically treated patients and were worse for patients with reruptures treated nonsurgically. No study tested strength at a specified joint angle; this constitutes a major flaw in strength-testing studies, because strength is related to the functional joint position. The difference in cost between surgical and nonsurgical treatment, including the cost of rerupture treatment, may not be significant.

Hypogonadism, hyperprolactinaemia, and temporal lobe epilepsy in hyposexual men.

Previously unrecognised temporal lobe epilepsy (TLE) was diagnosed in 11 of 16 hyposexual men. 6 had neuroendocrine abnormalities (hypogonadism in 4 and hyperprolactinaemia in 2). 4 men with hypogonadism and TLE had persistently subnormal serum testosterone, with a blunted luteinising hormone (LH) response to luteinising hormone releasing hormone (LHRH) in 2 and, in these men, unlike those with isolated hypogonadism, there was no improvement in libido or potency when parenteral testosterone was given. Men with TLE and hyperprolactinaemia had normal serum testosterone and an enhanced serum LH response after LHRH, but effective doses of the dopaminergic agonists, bromocriptine or pergolide, did not produce sustained normoprolactinaemia. In the men with neuroendocrine dysfunction and TLE the most effective therapeutic sequence was first to treat the epilepsy with anticonvulsants and then to add appropriate neuroendocrine therapy. In 2 men hormone levels became normal and sexual function was restored on anticonvulsant therapy alone.

Hyperprolactinaemia in males with and without pituitary macroadenomas.

To ascertain whether in hyperprolactinaemic men pituitary macroadenomas represent the end stage of a disease process wherein the only early symptom is impotence, the features of 16 hyperprolactinaemic men with radiological evidence of pituitary macroadenomas were compared with those of 10 hyperprolactinaemic men without pituitary macroadenomas. All were impotent and 25 had low serum testosterone levels. The group with pituitary macroadenoma was older (48.1 vs 63.2 years) and had tolerated impotence for longer (10.4 +/- 6.0 vs 4.5 +/- 2.1 years). 6 of them had visual field defects (none in the other group), 14 had hypopituitarism (1 in the other group), and 14 were initially seen for problems other than sexual dysfunction (whereas all 10 without pituitary macroadenomas were seen primarily for evaluation of recent onset of impotence). In the macroadenoma group bromocriptine restored serum prolactin levels in 13 of the 16 and serum testosterone and potency in 5, whereas in the non-tumour group it restored serum prolactin levels in all 10 and serum testosterone and potency in 9.