High Blood Pressure Induced by Audiovisual Stimulation in Young Rats: Effect of Antihypertensive Agents

ABSTRACT

High systolic blood pressure (BP) was induced in young Wistar rats by daily exposure for 30 mins to environmental stimuli consisting of intense (100 dB) sound of 7500 cps and flashing light (0.3 cps). Maximal BP enhancement was obtained after the application of both these stimuli for 3 consecutive days. Such a hypertensive response was detected 24 hrs, but not 1 hr after the trial. High BP backed to normal 72 hrs after discontinuation of the audiovisual stimulation trials. Clinically effective antihypertensive agents (clonidine, prazosin, propranolol, practolol and metoprolol) as well as a new compound under investigation (cicletanine) were proved active in this model. Normotensive nonstressed rats run in parallel did not show any variation in their BP after administration of the same dose of the drugs assayed. This experimental model of hypertension may be a useful tool not only to test new antihypertensive agents but also to study the intriguing question of the role of stress in the development and maintenance of essential hypertension.     

Prevalence and Predictors of Left Ventricular Diastolic Dysfunction in a Hispanic Patient Population

Minimal data exist on attributes of diastolic dysfunction in the Hispanic population. The purpose of this study was to evaluate the prevalence and predictors of diastolic dysfunction in a Hispanic patient population. We performed a retrospective review of 166 consecutive echocardiograms in a southwestern Texas Hospital that caters to a large Hispanic patient population. We identified all echocardiograms that met criteria for diastolic dysfunction and assessed baseline demographics and comorbidities in the cohort of Hispanic patients. A multivariate analysis was performed to identify the independent predictors of diastolic dysfunction. A total of 129 out of 166 patients (77.8%) were of Hispanic origin. Out of the 129 patients, 87 (67.4%) had some degree of diastolic dysfunction in this population suggesting a high prevalence in the study cohort. In the diastolic dysfunction group, the mean age was 64.5 ± 13.9, 37% were male and 63% female, 78% had diabetes, 85% had hypertension, and 49% had some degree of renal insufficiency (stages 3–5). A logistic multivariate analysis showed that diabetes was an independent predictor of diastolic dysfunction with odds ratio of 2.69 (95% confidence interval [CI], 1.06–6.28; p = 0.038). Similarly age (per year increase) and chronic kidney disease were independent predictors of diastolic dysfunction. We demonstrated that older age, presence of diabetes, and renal dysfunction are independent predictors of diastolic dysfunction in the Hispanic patient population. Strategies geared toward reducing diabetes and preventing renal dysfunction are likely to decrease prevalence of diastolic dysfunction and heart failure in this community.     

The risk of cardiovascular disease associated with proteinuria in renal transplant patients

Proteinuria in the general population has been shown to be associated with cardiovascular disease, which is the main cause of death in renal transplantation. We investigated the effect of proteinuria on cardiovascular disease after renal transplantation in 532 renal transplant patients with functioning grafts for more than 1 year. Patients were classified into two groups depending on the presence of persistent proteinuria. We analyzed graft and patient survival, posttransplantation cardiovascular disease, and main causes of graft loss and death. Five- and 10-year graft and patient survival rates were lower in the group with proteinuria. The main cause of death was vascular disease in both groups. The presence of posttransplantation cardiovascular disease was higher in the group with proteinuria. Persistent proteinuria was associated with graft loss (RR=4.18), patient death (RR=1.92), and cardiovascular disease (RR=2.45). In conclusion, persistent proteinuria was an independent risk factor for increased cardiovascular morbidity and mortality in renal transplant patients.     

Histologic characterization of acute spinal cord injury treated with intravenous methylprednisolone

OBJECTIVE: Many substances have been investigated for attenuation of spinal cord injury after acute trauma; however, pharmacologically only steroid administration has shown clinical benefits. This study attempts to characterize local spinal cord histologic response to human dose equivalent (HDE) intravenous methylprednisolone (MP) administration in a rodent model of acute spinal cord injury. DESIGN: Forty-eight Sprague-Dawley rats were divided equally into control and experimental groups. Each group was subdivided into eight sets of three animals each, according to postinjury intervals. Paraplegia after lower thoracic laminectomy was achieved using a standardized weight drop technique. INTERVENTION: Within one hour, experimental animals were treated with HDE MP followed by 23-hour continuous infusion of HDE MP. Spinal cords were harvested at variable intervals postinjury and prepared for histologic/immunohistochemistry examination. MAIN OUTCOME MEASUREMENTS: Edema, necrosis, and glial fibrillary acidic protein (GFAP) positivity in the specimens from treated/control groups were graded by microscopy and immunohistochemistry staining and compared in a blinded manner by a qualified neuropathologist and senior authors. RESULTS: Minimal differences were observed between control and MP-treated animals at zero and four hours. At eight hours, increased white matter and medullary edema was evident in control versus MP-treated rats. This trend continued through twelve, sixteen, twenty-four, forty-eight, and seventy-two hours. No difference was observed in the astrocytic response to injury by GFAP immunohistochemistry between the groups. CONCLUSIONS: Histologically, MP reduces the development of severe edema and preserves spinal cord architecture adjacent to the site of injury. In contrast, MP does not alter the development of spinal cord necrosis or astrocytic response at the zone of injury.     

抗体介导的排斥反应与临床

随着器官移植体液免疫理论的发展与抗体检测技术的进步,抗体介导的排斥反应(AMR)已逐渐被认识和引起关注。其治疗难度大、逆转率较低,已成为导致移植物失功的重要原因。本文较为系统地介绍了AMR的免疫机制、诊断与防治进展,以及供者特异性抗体的检测技术和临床意义,从而提出供者特异性抗体是引起移植物排斥反应特别是慢性排斥反应的主要原因,移植受者需常规监测抗体以利及时干预和治疗。     

Bacterial colonization in hemodialysis temporary dual lumen catheters: a prospective study

AIMS: The use of hemodialysis temporary dual-lumen catheters is often complicated by infections, which may be a significant cause of death among patients with end stage renal disease (ESRD). The aim of this study was to assess the incidence of bacteremia and bacterial colonization related to non-tunneled, non-cuffed, dual-lumen temporary catheters in patients with ESRD submitted to hemodialysis. METHODS: This study included 29 patients with ESRD. After catheter implantation, patients were monitored throughout the period of catheter permanence by means of blood samples collected weekly from a peripheral vein. Bacteria were isolated and identified according to CLSI recommendations. When catheters were removed for any reason, their tips were evaluated microbiologically. RESULTS: A total of 194 blood samples from the 29 patients implanted with 55 catheters were analyzed. Of these, 15.5% (30 samples) demonstrated bacterial growth, principally Staphylococcus epidermidis (64.5%). Twenty patients (68.9%) presented at least one positive blood culture during follow-up. The median time for catheter colonization was 18.5 days (95% CI: 16.8-30.3). Of the 55 catheters implanted, 28 (50.9%) showed bacterial colonization, corresponding to 23.4 episodes/1000 catheter/days and 9.2 episodes of bacteremia /1000 catheter/days. Fifteen of 28 catheter tips analyzed showed bacterial growth (53.5%). In 14 of these (93.3%), there was agreement between the isolates from the catheter tip and blood cultures. Of 24 episodes of positive blood cultures from 20 different patients in 17 episodes (70.8%), the patients showed no clinical signs or symptoms of bacteremia. CONCLUSIONS: The high incidence of catheter colonization, the correlation between blood and catheter tip cultures, and the occurrence of frequent cases of asymptomatic bacteremia justify the proposal of routine peripheral blood collections to monitor patients undergoing hemodialysis with temporary dual-lumen catheters.     

Effects of ischemic liver preconditioning on hepatic ischemia/reperfusion injury in the rat

To minimize bleeding during major liver resections or liver transplantation, surgical measures have been adopted that induce ischemia-reperfusion injury (I/R) which may significantly contribute to morbidity and mortality of partial liver resections. Several methods have sought to minimize I/R hepatic lesions. The present project assessed the protective role of ischemic preconditioning (IPC) in rat livers. The IPC was accomplished by clamping the hepatic pedicle for 5 minutes, followed by a 5-minute reperfusion (R) period before a 2-hour ischemia. Thereafter, reperfusions of 1, 3, and 24 hours were compared among IPC and control groups without IPC. Liver biopsy and blood samples were measured for mitochondrial respiratory control ratio (RCR), serum aspartate aminotransferase (AST), and alanine aminotransferase (ALT). IPC protected liver mitochondrial function. Serum aminotransferase levels were significantly lower among animals undergoing IPC compared with groups without IPC. Thus, we verified the effects of IPC for hepatocellular protection against I/R lesions.     

Gastric Emptying of Solids and Semi-solids in Morbidly Obese and Non-obese Subjects: An Assessment Using the <Superscript>13</Superscript>C-Octanoic Acid and <Superscript>13</Superscript>C-Acetic Acid Breath Tests

Background It has been suggested that obesity is associated with an altered rate of gastric emptying. The objective of the present study was to determine whether the rates of solid and semi-solid gastric emptying differ between morbidly obese patients and lean subjects. Methods The Gastric-emptying time (GET) of solid and semi-solid meals were compared between lean healthy subjects and morbidly obese patients enrolled in two previously published studies. GET of solid and semi-solid meals was measured using the ¹³C-octanoic acid breath test and ¹³C-acetic acid breath test, respectively, in 24 lean and 14 morbidly obese individuals of both sexes. Student t-test was used to compare the mean data between the lean and morbidly obese groups. The influence of sex, gender, BMI and morbid obesity on the GET of solid meals was verified by linear regression analysis. Results Mean t(1/2) values of solid GET (± standard deviation) were 203.6 ±  76.0 min and 143.5 ± 19.1 min for lean and obese subjects, respectively (P = 0.0010). Mean t(lag) values of solid GET were 127.3 ± 42.7 min and 98.4 ± 13.0 min for lean and obese subjects, respectively (P = 0.0044). No significant difference in semi-solid GET was observed between the lean and morbidly obese groups. Conclusion The present study demonstrated a significantly enhanced gastric emptying of the solid meal test in morbidly obese patients when compared to lean subjects. This finding is compatible with the hypothesis that rapid gastric emptying in morbidly obese subjects increases caloric intake due to a more rapid loss of satiety.