Effect of ankle position on isometric quadriceps strengthening

A prospective study of 20 normal subjects was undertaken to determine the effect of three ankle positions (active dorsiflexion, active plantar flexion, natural or rest position) on comfort and facilitation of quadriceps contraction in isometric strengthening in a supine position with the hip and knee fully extended. Surface EMG activity was found to be greatest for the vastus lateralis followed by the vastus medialis and least for the rectus femoris. Equal facilitation was apparent with either active ankle dorsiflexion or plantar flexion. Both were superior to the natural (rest) position. In situations where isometric quadriceps exercises are required, the authors recommend either active ankle dorsiflexion or plantar flexion to facilitate quadriceps strengthening. The choice between the two positions should be based on patient comfort.     

Xylose disposition in humans as a function of age

D-xylose disposition was examined in 24 healthy men between 32 and 85 years of age. Xylose was administered as a 5 gm iv infusion and as a 25 gm po solution. Serum xylose concentrations and urinary excretion of intact xylose were determined. There were statistically significant inverse relationships with age for each of the following parameters after intravenous infusion: elimination rate constant (r2 = 0.71); systemic clearance (r2 = 0.66); renal clearance (r2 = 0.66); and nonrenal clearance (r2 = 0.35). Similar inverse relationships were found after oral dosing for the elimination rate constant (r2 = 0.69) and renal clearance (r2 = 0.54). There was no significant age relationship for the apparent volume of distribution or the steady-state volume of distribution. The percentage of the oral and intravenous dose recovered in urine up to 5 hours after dosing was significantly and inversely correlated with age. The implications of the latter finding are discussed with regard to the interpretation of the xylose tolerance test used to assess gastrointestinal absorptive capacity.     

Pursuit gaze defects in acute and chronic unilateral parieto-occipital lesions

Isolated abnormalities of pursuit gaze were studied in 8 patients with unilateral acute (hemorrhage) or chronic (tumor) lesions of the parieto-occipital lobes. Ipsilateral pursuit was impaired in all patients, being superimposed with cogwheel saccades. Foveal pursuit was more disturbed than full-field pursuit. Impairment of contralateral pursuit was observed in all patients, but was severe only after acute involvement of the nondominant hemisphere. These findings provide further evidence for some asymmetric organization of hemispheric command of ocular movements. In these patients with hemianopia, the bilateral alterations of pursuit gaze probably correspond to an inter- and intrahemispheric disconnection syndrome.     

The cytochromes P-450 concentrations in microsomes of liver, kidney and duodenal mucosa of the camel, sheep and goat

The concentration of microsomal cytochromes P-450, and of protein in the homogenate, cytosol and microsomes were measured in the liver, kidney and duodenal mucosa of healthy well-fed male and female camels, sheep and goats. For comparison, data from the liver of male and female rats were also obtained. The protein concentrations in the tissues of adult animals were broadly similar in the four species. The concentration of cytochromes P-450 was highest in the liver, followed by the kidney, then the duodenal mucosa in all the species. No cytochromes P-450 were detected in the tissues of immature (less than 1 mo) male goats, whereas the female goat had the highest concentrations of these enzymes in the liver and kidney when compared with the respective tissues in the other species studied. Males had higher activity of cytochromes P-450 than females in the three tissues, except in the duodenal mucosa of sheep, where males had lower activity than females. In camel liver and sheep kidney, the amount of cytochromes P-450 were similar in the two sexes. The present results suggest that the mature female goat is the species best equipped to handle xenobiotics which are detoxified by the cytochromes P-450 and other drug metabolizing enzymes in diseased or malnourished animals is suggested as these two conditions are known to modify drug metabolizing enzymes.