Twenty-four patients of comparable age, blood pressure, and degree of dementia were classified by an "Ischemic Score" based on clinical features into "multi-infarct" and "primary degenerative" dementia. Regional cerebral blood flow (CBF) was measured by the intracarotid xenon 133 method. Both groups showed a decreased proportion of rapidly clearing brain tissue (largely gray matter). Cerebral blood flow per 100 gm brain per minute was normal in the primary degenerative group but low in the multi-infarct group. This suggests the blood flow is adequate for metabolic needs of the brain in patients with primary degenerative dementia but inadequate for those with multi-infarct dementia. There was no correlation between degree of dementia and CBF in the primary degenerative group but an inverse relationship existed in the multi-infarct group. Reactivity of blood vessels to reduction of arterial carbon dioxide pressure was normal in both groups.

Background The management of complex orthopedic infections usually includes a prolonged course of intravenous antibiotic agents. We investigated whether oral antibiotic therapy is noninferior to intravenous antibiotic therapy for this indication. Methods We enrolled adults who were being treated for bone or joint infection at 26 U.K. centers. Within 7 days after surgery (or, if the infection was being managed without surgery, within 7 days after the start of antibiotic treatment), participants were randomly assigned to receive either intravenous or oral antibiotics to complete the first 6 weeks of therapy. Follow-on oral antibiotics were permitted in both groups. The primary end point was definitive treatment failure within 1 year after randomization. In the analysis of the risk of the primary end point, the noninferiority margin was 7.5 percentage points. Results Among the 1054 participants (527 in each group), end-point data were available for 1015 (96.3%). Treatment failure occurred in 74 of 506 participants (14.6%) in the intravenous group and 67 of 509 participants (13.2%) in the oral group. Missing end-point data (39 participants, 3.7%) were imputed. The intention-to-treat analysis showed a difference in the risk of definitive treatment failure (oral group vs. intravenous group) of −1.4 percentage points (90% confidence interval [CI], −4.9 to 2.2; 95% CI, −5.6 to 2.9), indicating noninferiority. Complete-case, per-protocol, and sensitivity analyses supported this result. The between-group difference in the incidence of serious adverse events was not significant (146 of 527 participants [27.7%] in the intravenous group and 138 of 527 [26.2%] in the oral group; P = 0.58). Catheter complications, analyzed as a secondary end point, were more common in the intravenous group (9.4% vs. 1.0%). Conclusions Oral antibiotic therapy was noninferior to intravenous antibiotic therapy when used during the first 6 weeks for complex orthopedic infection, as assessed by treatment failure at 1 year. (Funded by the National Institute for Health Research; OVIVA Current Controlled Trials number, ISRCTN91566927.)

The cerebral blood flow, oxygen extraction and oxygen utilization has been measured regionally in 22 dements, and 14 aged normal volunteers. Ten demented patients were studied twice at a six-month interval from initial measurements. The use of a steady-state 15O technique and positron tomography for measuring regional cerebral blood flow, regional oxygen extraction fraction and mean cerebral oxygen utilization is discussed. The limitations of measurements are reviewed in the light of the present results and the current state of technological development in positron emission tomography is discussed. A decline in cerebral blood flow and mean cerebral oxygen utilization was correlated with increasing severity of dementia in both degenerative and vascular dements. The decline was coupled, both for the cerebral hemisphere as a whole and regionally. There was no increase in oxygen extraction ratio globally, and therefore no evidence to support the existence of a chronic ischaemic brain syndrome. Focal abnormalities in oxygen utilization were observed for both vascular and degenerative groups. In the vascular group, parietal defects were the most pronounced. Individual derangements of the regional pattern varied, reflecting the different unique patterns of ischaemic damage in these patients. In the degenerative group, parietal and temporal defects were seen in the less severe group, but a profound depression in the frontal regions with relative sparing of occipital area characterized the severe degenerative dements.

The relationships between cerebral blood flow (CBF), arterial oxygen content, whole blood viscosity and the transport of oxygen to the brain have been studied in 54 subjects with variations in arterial oxygen content resulting from alterations in haemoglobin concentration ranging from 5.7 to 19.1 g/dl. A highly significant relationship was found between CBF and arterial oxygen content, CBF altering to maintain the rate of transport of oxygen to the brain within certain limits. No significant effect of changes in blood viscosity was evident. In a multiple regression analysis arterial oxygen content emerged as the major determinant of CBF and after this effect had been taken into account there was no significant influence of blood viscosity, arterial pCO2, age or mean arterial blood pressure. The results imply that the alterations in CBF found in subjects with anaemia and polycythaemia are primarily physiological and not caused by the accompanying alterations in blood viscosity. It is proposed that the response of the cerebral circulation to arterial oxygen content is mediated by a local mechanism sensitive to alterations in local tissue oxygen tension.