Genetic variability in the Guahibo population from venezuela

Four communities from Guahibo of Venezuela were analyzed for the genetic variants of nine erythrocyte enzymes and five serum proteins. Of the 14 loci determined, four were monomorphic. Significant frequency differentiation among communities, was present for ESD and TF markers. In general, Guahibo allele frequencies are in the variation ranges described for South American groups. The analysis indicates a relatively higher affinity of Guahibos with other Venezuelan groups within an irregular pattern of genetic distances that are likely related to the complex demographic history of the South American groups. Genetic diversity estimates reveal a moderate degree of genetic structure between the four Guahibo communities. This intra‐tribal variability in Guahibo appears to be lower than in Venezuelan Piaroa but higher than in other Amerindians and could be attributed to a combined effect of low population size and relative isolation of communities. At a continental level, the distribution of genetic diversity is consistent with preferential population movements along the eastern and western coastal areas. Am. J. Hum. Biol. 14:21–28, 2002. © 2002 Wiley‐Liss, Inc.     

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.     

A flow visualization study of an anatomic coronary artery anastomosis model with an implant.

Flow Streamlining Devices is a new tool in Coronary Artery Bypass Grafting (CABG). They aim in: a) Performing a sutureless anastomosis to reduce thrombosis at the veno-arterial junction, and b) Providing a hemodynamically efficient scaffolding to reduce secondary flow disturbances. Thrombosis and flow disturbances are factors that have been reported as contributing factors to the development of intimal hyperplasia (IH) and failure of the graft. By reducing thrombosis and flow disturbances, it is expected that IH will be inhibited and the lifetime of the graft extended. To evaluate the hemodynamic benefits of such an implant, two models were designed and fabricated. One simulated the geometry of the conventional anastomosis without an implant, and the other simulated an anastomosis with a flow streamlining implant. Identical flow conditions relevant to a coronary anastomosis were imposed on both models and flow visualization was performed with dye injection and a digital camera. Results showed reduction of disturbances in the presence of the implant. This reduction seems to be favorable to hemodynamic streamlining which may create conditions that may inhibit the initialization of IH. However, the compliance and geometric mismatch between the anastomosis and the implant created a disturbance at the rigid compliant wall interface, which should be eliminated prior to clinical applications.     

Treatment of Status Epilepticus in Adults: Guidelines of the Italian League Against Epilepsy

Summary:  Status epilepticus (SE) is a medical emergency which can lead to significant morbidity and mortality and requires prompt diagnosis and treatment. SE is differentiated into generalized or partial SE on the basis of its electro-clinical manifestations. The guidelines for the management of SE produced by the Italian League against Epilepsy also distinguish three different stages of SE (initial, established and refractory), based on time elapsed since the onset of the condition and responsiveness to previously administered drugs. Treatment should be started as soon as possible, particularly in generalized convulsive SE, and should include general support measures, drugs to suppress epileptic activity and, whenever possible, treatments aimed at relieving the underlying (causative) condition. Benzodiazepines are the first line antiepileptic agents, and i.v. lorazepam is generally preferred because it is associated with a lower risk of early relapses. If benzodiazepines fail to control seizures, i.v. phenytoin is usually indicated, though i.v. phenobarbital or i.v. valproate may also be considered. Refractory SE requires admission to an intensive care unit (ICU) to allow adequate monitoring and support of respiratory, metabolic and hemodynamic functions and cerebral electrical activity. In refractory SE, general anesthesia may be required. Propofol and thiopental represent first line agents in this setting, after careful assessment of potential risks and benefits.     

Phylogenetic relationships of snake venom toxic proteins

Two kinds of distance matrices have been formed from minimum mutational distances and absolute hydrophobicity differences obtained by comparison of aligned homologous sequences of 56 toxins from venom of snakes belonging to 7 genera. Phylogenetic trees were constructed from these distance matrices, employing the unweighted pair-group method using arithmetic averages (UPGMA). The Pearson product-moment correlation coefficient has been used to estimate the agreement between the original distance matrix and that obtained directly from the dendrogram. For all these procedures the set of computer programs PHYTREE (written in BASIC for micro-computer, and available from the author) has been used.     

The magnetic resonance of small hepatocarcinoma. A comparison with echography, computed tomography, digital angiography and computed tomography with lipiodol]

Diagnostic techniques as a whole and periodic ultrasonography (US) in particular frequently allows tumors < 3 cm (small hepatocellular carcinomas) to be detected in patients suffering from liver cirrhosis. Multifocal diseases are a major limitation to surgery. Recently, MR imaging has shown its capabilities in the diagnosis of small hepatocellular carcinomas. In our study the diagnostic value of MR imaging was compared with that of US, of pre- and post-contrast CT, of digital angiography and of CT after lipiodol injection (Lipiodol CT). The morphologic and signal intensity MR features of small hepatocellular carcinomas were investigated. Fifteen cirrhotic patients with 31 nodules of hepatocellular carcinoma < 3 cm were examined. All patients were studied with US, MR imaging, angiography and Lipiodol CT; 12/15 patients underwent CT. Histologic confirmation was obtained in 12 nodules (2 at surgery and 10 by means of percutaneous biopsy); in the extant 19 cases the diagnosis was made by combining US, CT, MR, angiographic and lipiodol-CT findings; in 9 tumors < 1 cm Lipiodol retention one month after angiography was considered as diagnostic. MR imaging detected 21/31 nodules (63%), US 22/31 (66.6%), CT 12/24 (50%), angiography 24/31 (74%), lipiodol CT 29/31 (92.5%). Mc Nemar test showed no difference in sensitivity between MR imaging and CT, MR and angiography, MR and US, lipiodol CT and angiography; however, the differences between the detection rates of MR imaging and Lipiodol CT and CT and lipiodol CT and US were statistically significant (p < 0.05). The difference in sensitivity between the detection rates of lipiodol CT and US was just above the threshold value which is usually considered significant (p = 0.065). One false positive was observed on US and none with MR, CT, angiography and lipiodol CT. On Se T1-weighted images 18 nodules were hyperintense, 2 isointense and 2 hypointense; on proton-density images 14 nodules were hyperintense, 7 isointense and none hypointense. On SE T2-weighted images 18 nodules were hyperintense, 3 isointense and none hypointense. A pseudocapsule was seen in 10/17 nodules (58%), especially on T1-weighted images. Accuracy and limitations of each technique and morphologic and signal intensity MR findings of small hepatocellular carcinoma are discussed. We believe that US is still the best diagnostic technique for the screening of hepatocellular carcinomas in cirrhotic livers.(ABSTRACT TRUNCATED AT 400 WORDS)