Effect of hemodilution on brain tissue during global ischemia

This study evaluates the effect of blood volume and hematocrit changes on brain tissue during temporary global ischemia. Normal saline was administered intravenously to 55 gerbils to achieve hypo-, normo-, and hypervolemic hemodilution and uniform 30% hematocrit reduction. Each group had unilateral carotid artery ligation and temporary (20 minute) contralateral carotid occlusion. After ten days or death, brains were harvested, preserved in formalin, sectioned in a manner which provided adequate samples of both cortex and hippocampus, and stained with H&E and luxol fast blue. They were then examined and staged microscopically for white and gray matter infarction, edema, and neuronal injury and loss. Histologic studies were performed in a randomized and blinded manner and were classified by one of four categories: normal, minimal, moderate, and severe changes. Three of ten (30%) controls survived ten days but had severe neuronal loss, minimal cerebral edema and a minimal to moderate number of white matter strokes. Survival was best in animals treated with hypovolemic hemodilution (43%). Other rates were: normovolemic (33%), controls (30%), and hypervolemic (8.3%). The degree of brain tissue damage was markedly less in the normovolemic group. In this model, normovolemic hemodilution followed by hypovolemic hemodilution offered the best overall cerebral protection during global ischemia.     

von Willebrand factor as a marker of endothelial cell activation following BMT.

Endothelial cell activation may play a role in thrombotic complications of BMT such as hepatic veno-occlusive disease (VOD), right atrial line thrombosis and microangiopathic haemolysis. To assess this, von Willebrand factor antigen (vWF:ag) was measured in 72 patients (25 allografts, 46 autografts and one syngeneic) during the first 6 weeks post-transplant. There was a significant rise in vWF:ag in both allografts and autografts but a greater increase was seen in the allografts. The changes in vWF:ag did not correlate with changes in C reactive protein showing that this was not merely an acute phase response. vWF multimers were normal in a subgroup of uncomplicated transplants showing that there was no large scale endothelial cell disruption. Patients with VOD did not have changes in vWF:ag that were consistently different from uncomplicated controls. Three of four patients who developed line thrombosis had higher levels of vWF:ag compared with control groups; multimeric structure of the vWF was again normal. These results show that there is endothelial cell activation post-BMT and that this is greater in allografts compared with autografts, thus suggesting a possible mechanism for the higher incidence of VOD in this group. There were no useful predictive markers of VOD or thrombosis in individual patients.     

An open-label efficacy pilot study with pimecrolimus cream 1% in adults with facial seborrhoeic dermatitis infected with HIV

BACKGROUND: Seborrhoeic dermatitis (SD) is a common dermatosis in human immunodeficiency virus (HIV)-positive patients, many of whom do not respond satisfactorily to conventional topical treatments such as corticosteroids and antifungals. OBJECTIVE: A pilot study to investigate the efficacy and tolerability of pimecrolimus cream 1% in HIV-positive patients with facial SD. METHODS: In a single-centre study, 21 HIV-infected patients with mild to severe SD were treated twice daily with pimecrolimus cream 1% for 14 days. Thereafter, treatment was discontinued and patients followed up for 5 weeks. Skin involvement at baseline and on days 7, 14, 21, 35 and 49 was assessed using a four-point clinical score and digital photography. MAIN OUTCOME MEASURES: Efficacy and safety of pimecrolimus cream 1% treatment and incidence of relapse in the follow-up phase. Results Marked improvement was seen in clinical parameters at day 7, with >or= 90% patients clear of symptoms at day 14. Relapse was observed at day 35 but signs were milder than at baseline. All patients responded to therapy, despite their immunological status. Pimecrolimus did not alter CD4(+) and CD8(+) T-cell counts or viral load during the treatment period. CONCLUSION: Pimecrolimus cream represents a new, effective therapeutic option for facial SD in HIV patients.     

Maximum relaxation rate of the diaphragm during weaning from mechanical ventilation.

BACKGROUND--The maximum relaxation rate (MRR; percentage fall in pressure/10 ms) of oesophageal (POES) and transdiaphragmatic (PDI) pressure slows under conditions of loaded breathing, and has been measured previously in normal subjects. MRR has not been measured in intubated patients weaning from mechanical ventilation. METHODS--Five postoperative patients who were expected to wean and nine patients who had previously failed were studied. POES and PDI MRR, peak oesophageal pressure during spontaneous breathing, maximum oesophageal pressure, and the inspiratory duty cycle were measured at rest during mechanical ventilation, in the first two minutes of spontaneous breathing, and after reventilation in those patients who failed, or before extubation in those patients who succeeded. RESULTS--At rest POES MRR in intubated patients had a range of 5.6-11 and PDI MRR 6.9-10.0, with a coefficient of variation of 9.9% and 7.3% respectively. POES and PDI MRR were similar before and after extubation in five postoperative patients, and POES MRR was reflected by endotracheal MRR measured at the airway. In five patients who failed to wean POES and PDI MRR slowed by 47% and 44%, and fully recovered after 10 minutes reventilation. In four patients who were successfully weaned MRR was unchanged during spontaneous breathing. At the time when MRR decreased, the respiratory muscles were heavily loaded in relation to their strength. CONCLUSIONS--Weaning failure occurs when the applied load exceeds the capacity of the respiratory muscles, and this is associated with a slowing of respiratory muscle MRR.