Carvedilol protects ischemic cardiac mitochondria by preventing oxidative stress.

Ischemia negatively affects mitochondrial function by inducing the mitochondrial permeability transition (MPT). The MPT is triggered by oxidative stress, which occurs in mitochondria during ischemia as a result of diminished antioxidant defenses and increased reactive oxygen species production. It causes mitochondrial dysfunction and can ultimately lead to cell death. Therefore, drugs able to minimize mitochondrial damage induced by ischemia may prove to be clinically effective. We analyzed the effect of carvedilol, a beta-blocker with antioxidant properties, on mitochondrial dysfunction. Carvedilol decreased levels of TBARS (thiobarbituric acid reactive substances), an indicator of oxidative stress, which is consistent with its antioxidant properties. Regarding cell death by apoptosis, although ischemia did increase caspase-8-like activity, there were no changes in caspase-3-like activity, which is activated downstream of caspase-8; this may indicate that the apoptotic cascade is not activated by 60 minutes of ischemia. We conclude that carvedilol protects ischemic mitochondria by preventing oxidative mitochondrial damage, and, by so doing, it may also inhibit the formation of the MPT pore.     

Cysticercosis of the brain. The value of computed tomography

Incidence and radiologic findings of neurocysticercosis were investigated in a series of 23,800 consecutive head examinations using computed tomography (CT). The condition was diagnosed in 168 cases (0.7%). The parenchymatous form was the most common presentation (96.3%), while the meningeal form corresponded to only 11.9 per cent of cases. These two forms coexisted in some cases. These findings reversed the knowledge on the condition based on conventional radiography. The different CT appearances in the brain are described and a new radiologic protocol for the CT evaluation of the condition is advocated, which includes a follow-up after a trial cure with Praziquantel in the presence of cysts not associated with suggestive brain calcifications. CT was more sensitive than conventional radiography in the differentiation between dead and living larvae, thus having an impact on the therapeutic management of the patients.     

Identification of a surface protein (p100) associated with two glycosyl-phosphatidylinositol-linked molecules (Thy-1 and ThB) by natural anti-lymphocyte autoantibodies.

Our previous study of natural autoantibodies showed that anti-lymphocyte antibodies are frequently produced by perinatal B cells from normal strains of mice. One-third of these monoclonal antibodies (mAb) recognized similar epitopes on the surface of thymocytes. In the present report, we have characterized the molecule recognized by three of these mAb (D10, G7, 22). These mAb identified a 100-kDa protein (p100) on the surface of thymocytes. This protein resolved into 70-kDa polypeptide chains under reducing conditions. Inhibition experiments as well as antibody immunoprecipitations in the presence of mild detergents revealed non-covalent association of the p100 with Thy-1 and ThB. A similar multimolecular complex was identified following chemical cross-linking of thymocyte surface proteins. Analysis of several Thy-1-defective mutant cells lines, and thymocytes treated with phosphatidylinositol-specific phospholipase C (PI-PLC) showed that the expression of p100 was strongly influenced by Thy-1 molecule. The p100 was resistant to PI-PLC treatment and was not released into the supernatant as was the case for Thy-1 and ThB molecules. These data lead us to propose that the p100 is a transmembrane protein, the expression of which in the plasma membrane is dependent on the association or presence of Thy-1 molecule.     

Design-based stereological estimation of hepatocyte number, by combining the smooth optical fractionator and immunocytochemistry with anti-carcinoembryonic antigen polyclonal antibodies.

BACKGROUND/AIMS: Hepatocytes (HEP) have been the major target for structural quantification in the liver, but an estimation of their total number (N), their percentage in relation to the global number of liver cells and the evaluation of the percentage of binucleated hepatocytes (BnHEPs) have never been performed with modern design-based stereological techniques. The establishment of sound technical guidelines and baseline quantitative data in non-pathological conditions are relevant to properly evaluate HEP hyperplasia and BnHEP responses. METHODS: In this study, we combined immunocytochemistry with sound design-based stereology for estimating the N of HEP and the N of non-hepatocytic cells (NHCs). For obtaining systematic uniform random sections (30 microm thick), a smooth fractionator sampling scheme was applied to the liver of five male Wistar rats (3 month old). Those sections were immunostained with polyclonal antibodies against carcinoembryonic antigen. Because biliary canaliculi were then marked, an unequivocal counting of mononucleated hepatocytes (MnHEP) and BnHEP was allowed. RESULTS: The N of HEP was estimated to be 1.93 x 10(9), with a coefficient of error (CE) of 0.02, corresponding to 129 x 10(6) HEP/g of liver. BnHEP represented 26% of total HEP number. The N of NHC was estimated as 1.31 x 10(9) (CE=0.02). CONCLUSION: The strategy here presented provides a reliable method for accessing the N of HEP (distinguishing MnHEP from BnHEP) in situations in which these parameters are relevant, namely for evaluating the magnitude of an hyperplastic liver response from its very early onset.     

Colonization with methicillin-resistant Staphylococcus aureus after liver transplantation.

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of infection after orthotopic liver transplantation (OLT). Colonization with MRSA is associated with a higher risk of infection. Previous studies have shown a high prevalence of MRSA colonization among OLT candidates. However, the risk of colonization with MRSA after OLT is still unclear. The objective of this study was to estimate the incidence and the factors associated with colonization with MRSA after OLT. This was a prospective cohort study including patients submitted to OLT between the years 2000 and 2002. Surveillance cultures of nasal swab specimens were performed within the 1st 72 hours of hospital admission and, subsequently, on weeks 2, 6, 13, and 26. Patients whose baseline cultures revealed nasal carriage of MRSA were excluded. A total of 60 patients were included in the study. The median follow-up was 72 days. A total of 9 patients (15%) became colonized. In multiple logistic regression analyses, the use of a urinary catheter for > or =5 days (P = .006), postoperative bleeding at the surgical site (P = .009), and preoperative use of fluoroquinolones (P = .08) were associated with a higher risk of colonization. Patients without any of these risk factors did not become colonized. In conclusion, nasal carriage of MRSA is frequently acquired after OLT. Periodic postoperative screening for MRSA carriage should be an integral component in programs designed to reduce nosocomial MRSA transmission in these patients. Further studies are needed to set up and validate a predictive model that could allow targeting postoperative screening to high-risk OLT recipients.     

Superficial femoral artery recanalization with self-expanding nitinol stents: long-term follow-up results.

PURPOSE: Since long-term patency and device integrity of nitinol stents in SFA lesions are not well studied, we examined clinical outcome, patency and device integrity after stenting long lesions using a standardized implantation technique. METHODS: Between 2001 and 2006, 59 patients (74 lesions) were treated with the same nitinol self-expandable stent (Zilver, Cook, USA) and technique for SFA recanalization. Clinical charts and imaging were retrospectively reviewed for patency (primary and assisted-primary), and device integrity. RESULTS: Patients were 74.5 (10.9) years old (range 49 to 93), 64% male, 42% diabetic, 62% hypertensive and 67% current or former smokers. Lesions were 23% TASC B, 16% TASC C, or 61% TASC D. Mean recanalization length was 19 cm (range 3 to 53). Mean number of stents per patient was 2.8 (total 210). Mean follow-up time was 2.4 years (range 3 days to 4.8 years). Kaplan-Meier estimates for primary patency rates were 90%, 78%, 74%, 69%, and 69% at 1, 2, 3, 4 and 4.8 years, respectively. Ten restenoses at a mean of 500 (388) days (1-1251 days) were successfully recanalized. The assisted primary patency rates were 96%, 90%, 90%, 90% and 90% at 1, 2, 3, 4 and 5 years, respectively. Six complete occlusions could not be reverted by a second recanalization procedure, and were treated by surgical bypass (1 case), amputation (3 cases), or medical management (2 cases). One (1.04%) Class II stent fracture was noted. CONCLUSIONS: SFA recanalization with a standardized implantation technique and nitinol stents provides good long-term primary and assisted-primary patency.     

Bis(cyclopentadienyl)zirconium dichloride supported on zeolites for ethylene polymerization

Y zeolites with different sodium contents and a sodium mordenite were evaluated as support for bis(cyclopentadienyl)zirconium dichloride as catalyst for ethylene polymerization. The results showed that, although the activities of the supported catalysts were lower than that of the homogeneous system, the average molecular weight of the polyethylene produced from the former was in general much higher than that of the polymer produced in solution. Contrary to the expected trend if the specific area was the dominant factor for catalyst activity, the best catalyst was the one supported on NaM zeolite. Thus, our results indicate that the concentration of framework aluminium atoms is the dominant factor, but that the contribution of the external surface is also important.     

Use of the microorganism Bacillus stearothermophilus as a model to evaluate toxicity of the lipophilic environmental pollutant endosulfan

Microorganisms are very powerful tools for the supply of information about the toxic effects of lipophilic compounds, since an impairment of cell growth usually occurs as a result of perturbations related, in most cases, with the partition of toxicants in membranes. The thermophilic eubacterium Bacillus stearothermophilus has been used as a model system to identify α- and β-endosulfan interactions with the membrane possibly related with the insecticide toxicity. Two approaches have been pursued: (a) bacterial growth is followed and the effects of endosulfan isomers determined; (b) biophysical studies with the fluorescent fluidity probe 1,6-diphenyl-1,3,5-hexatriene (DPH) were performed to assess the effects of α- and β-endosulfan on the organization of the membrane lipid bilayer. The effects on growth were quantitatively evaluated by determination of growth parameters, namely the lag phase, the specific growth rate and the cell density reached by cultures in the stationary phase. Growth inhibition by α and β-endosulfan dependent on the concentration is diminished or removed by the addition of 2.5 m Ca²⁺ to bacterial cultures. Fluorescence DPH polarization consistently showed opposite effects of Ca²⁺ and α- and β-endosulfan on the physical state of bacterial polar lipid dispersions.