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.     

Mechanics of the anterior drawer and talar tilt tests: A cadaveric study of lateral ligament injuries of the ankle

We analyzed the changes in lateral ligament forces during anterior drawer and talar tilt testing and examined ankle joint motion during testing, following an isolated lesion of the anterior talofibular ligament (ATFL) or a combined lesion of the ATFL and calcaneofibular ligament (CFL). 8 cadaver specimens were held in a specially designed testing apparatus in which the ankle position (dorsiflexion-plantarflexion and supination-pronation) could be varied in a controlled manner. Ligament forces were measured with buckle transducers, and joint motion was measured with an instrumented spatial linkage. An anterior drawer test was performed using an 80 N anterior translating force, and a talar tilt test was performed using a 5.7 Nm supination torque with intact ligaments, after sectioning of the ATFL, and again after sectioning of the CFL. The tests were repeated at 10° dorsiflexion, neutral, and 10° and 20° plantarflexion. In the intact ankle, the largest increases in ATFL force were observed during testing in plantarflexion, whereas the largest increases in CFL force were observed in dorsiflexion. Isolated ATFL injury caused only small laxity changes, but a pronounced increase in laxity was observed after a combined CFL and ATFL injury.     

Depressed antigen presentation function and membrane interleukin-1 activity of peritoneal macrophages after laparotomy

Although major tissue trauma produces profound depression of cell-mediated immunity, it is not known whether surgical trauma (i.e., midline laparotomy) has any adverse effect on the antigen presentation function and membrane interleukin-1 (IL-1) activity of peritoneal macrophages. To study this, C3H/HEJ (endotoxin-tolerant) mice were anesthetized. An approximately 1-inch midline abdominal incision was made, followed by abdominal closure. On days 1, 3, 5, and 7, peritoneal macrophages were harvested by means of peritoneal lavage, and antigen presentation capability was tested by incubating various numbers of peritoneal macrophages with 2 X 10(4) D10.G4.1 cells per well in the presence of conalbumin (400 micrograms/ml). The T helper cell clone (D.10.G4.1) proliferates on recognition of conalbumin in the context of Iak and also proliferates in the presence of membrane-bound IL-1 plus concanavalin A. To measure membrane IL-1 expression in peritoneal macrophages, Concanavalin A (10 micrograms/ml) was substituted for conalbumin. Cultures were incubated for 72 hours, pulsed with tritiated thymidine, and harvested. Peritoneal macrophages from laparotomized mice induced significantly less T helper cell proliferation on days 1 and 3 in the antigen presentation assay (37% and 30%, respectively; p less than 0.05) and in the membrane IL-1 assay (14% and 10%, respectively; p less than 0.05) as compared with the control. This difference was not detectable on day 5. More effective antigen presentation capability (167% of control; p less than 0.05) was seen on day 7. Thus laparotomy by itself produces marked depression of both antigen presentation function and membrane IL-1 activity of peritoneal macrophages, which may enhance susceptibility to intra-abdominal sepsis.     

GROWTH DISTURBANCES ASSOCIATED WITH UNTREATED BENIGN BONE CYSTS

Background: The occurrence of benign bone cysts adjacent to an active physis may be associated with a physeal arrest. That arrest may result from physeal penetration of the cysts itself, secondary pathologic fracture or the result of surgical curettage. Methods : The pre-treatment X-rays of patients attending the Bone Tumor Clinic at the Children's Hospital and Medical Center were reviewed. Those patients presenting with a bone cyst were identified and the affected side was compared to the normal side in order to determine growth discrepancies. Results: Three cases of benign bone cysts are presented that were located adjacent to a growing physis and produced growth disturbance in the absence of surgical intervention. Conclusions: The risk of growth disturbance in itself should not be a contraindication to surgical intervention.