Hyperventilation following head injury: effect on ischemic burden and cerebral oxidative metabolism

OBJECTIVE: To determine whether hyperventilation exacerbates cerebral ischemia and compromises oxygen metabolism (CMRO2) following closed head injury. DESIGN: A prospective interventional study. SETTING: A specialist neurocritical care unit. PATIENTS: Ten healthy volunteers and 30 patients within 10 days of closed head injury. INTERVENTIONS: Subjects underwent oxygen-15 positron emission tomography imaging of cerebral blood flow, cerebral blood volume, CMRO2, and oxygen extraction fraction. In patients, positron emission tomography studies, somatosensory evoked potentials, and jugular venous saturation (SjO2) measurements were obtained at Paco2 levels of 36+/-3 and 29+/-2 torr. MEASUREMENTS AND MAIN RESULTS: We estimated the volume of ischemic brain and examined the efficiency of coupling between oxygen delivery and utilization using the sd of the oxygen extraction fraction distribution. We correlated CMRO2 to cerebral electrophysiology and examined the effects of hyperventilation on the amplitude of the cortical somatosensory evoked potential response. Patients showed higher ischemic brain volume than controls (17+/-22 vs. 2+/-3 mL; p相似文献   

Functional and Morphologic Maturation of the Superficial Nephrons RELATIONSHIP TO TOTAL KIDNEY FUNCTION

The functional and morphologic pattern of superficial nephron development was studied in guinea pigs ranging in age between 2 h and 38 days. Concomitent measurements of total kidney function and glomerular counts were also performed.Superficial nephron glomerular filtration rate was found to increase from 0.92 to 19.32 nl/min. The filtration rate of the entire kidney rose from 0.19 to 1.31 ml/min. During the first 15 days of life the average rate of increase in glomerular filtration rate per nephron (0.48 nl/min.day), obtained by dividing the increase in total kidney glomerular filtration rate by glomerular number, was more than twice the observed rate of increase in the superficial nephrons (0.21 nl/min.day). During the remainder of the first month, the increase in superficial nephron glomerular filtration rate (0.97 nl/min.day) was greater than the average increase for all nephrons (0.71 nl/min.day). Thus, the initial increase in total kidney glomerular filtration rate was primarily a consequence of the activity of the deep nephrons, whereas during the ensuing period the superficial nephrons appeared to be the sole contributors to the change in total kidney glomerular filtration rate.The increase in superficial nephron glomerular filtration rate was found to correlate closely with the increase in proximal tubular length. Functional glomerulotubular balance was maintained throughout the entire period of renal maturation.     

Adenovirus 38: a new human adenovirus species of subgenus D

From the stool of a Dutch girl, a new virus (LJ) was isolated that by morphological, biological, and immunological criteria was a human adenovirus. Because of its hemagglutinating activity for rat and human red blood cells and its DNA restriction enzyme pattern, the virus was classified as a member of subgenus D. It was distinct in neutralization tests from all other human adenoviruses. The hemagglutinin was antigenically similar to that of adenoviruses 13 and 39, but the DNA differed from that of these two species. It is proposed to call virus LJ candidate Mastadenovirus h 38. Two other viruses belonging to the same new species were isolated in the USA.     

The effects of naloxone on circulating metabolites,glycoregulatory hormones and gut peptides during pelvic surgery

Summary. The role of endogenous opioid peptides in mediating the endocrine and metabolic response to pelvic surgery was investigated. Fourteen patients were studied; seven were infused with the specific opioid antagonist, naloxone, at a rate of 20 μg kg^-1 (body weight) hr^-1, while the remainder acted as a control group. Naloxone exacerbated the glycaemic response to surgery but had no statistically significant effect on changes in the glycoregulatory hormones, pancreatic glucagon, insulin, cortisol and growth hormone. However, there was a wide individual variation in the glucagon response to naloxone with marked stimulation in some patients. Naloxone infusion increased plasma pancreatic polypeptide secretion during the 1st hour of surgery and reversed the decline in plasma motilin concentrations, but had no effect on circulating somatostatin, vasoactive intestinal polypeptide, gastrin, enteroglucagon and neurotensin values. We conclude that endogenous opioid peptides have only a limited role in modulating the endocrine and metabolic response to surgery.     

Prolonged recovery of retinal structure/function after gene therapy in an Rs1h-deficient mouse model of x-linked juvenile retinoschisis.

X-linked juvenile retinoschisis (RS) is a common cause of juvenile macular degeneration in males. RS is characterized by cystic spoke-wheel-like maculopathy, peripheral schisis, and a negative (b-wave more reduced than a-wave) electroretinogram (ERG). These symptoms are due to mutations in the RS1 gene in Xp22.2 leading to loss of functional protein. No medical treatment is currently available. We show here that in an Rs1h-deficient mouse model of human RS, delivery of the human RS1 cDNA with an AAV vector restored expression of retinoschisin to both photoreceptors and the inner retina essentially identical to that seen in wild-type mice. More importantly, unlike an earlier study with a different AAV vector and promoter, this work shows for the first time that therapeutic gene delivery using a highly specific AAV5-opsin promoter vector leads to progressive and significant improvement in both retinal function (ERG) and morphology, with preservation of photoreceptor cells that, without treatment, progressively degenerate.