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.     

Vertical integration in health services: theory and managerial implications

A vertically integrated health care system is an arrangement whereby a health care organization offers, either directly or through others, a broad range of patient care and support services. This article discusses the market forces and strategic considerations driving the recent trend toward vertical linkages in health care markets and examines some of the managerial implications and issues associated with this vertical restructuring trend.     

Sex-linked pattern of collaterals in iliac artery occlusive disease

Aorto-femoral angiography carried out in 839 patients revealed that 139 males and females had uni- or bilateral occlusion of the common or external iliac arteries. Pelvic or lumbar/intercostal arteries served as collaterals in 786 patients. In the remaining 53 patients the collateral blood supply originated from the thoracic arteries. Among the 53 patients, only 7 were females. A chi 2-test revealed the difference to be significant (p less than 0.0005), indicating a sex-linked difference, a male preponderance, in the development of collateral circulation of thoracic origin.