Effect of Ag Addition on the Electrochemical Performance of Cu10Al in Artificial Saliva.

In this work we proposed to evaluate the corrosion resistance of four different alloys by electrochemical techniques, a binary alloy Cu10Al, and three ternary alloys Cu10Al-xAg (x = 5, 10, and 15 wt.%) to be used like biomaterials in dental application. Biomaterials proposed were tested in artificial saliva at 37°C for 48 h. In addition, pure metals Cu, Al, Ag, and Ti as reference materials were evaluated. In general the short time tests indicated that the Ag addition increases the corrosion resistance and reduces the extent of localized attack of the binary alloy. Moreover, tests for 48 hours showed that the Ag addition increases the stability of the passive layer, thereby reducing the corrosion rate of the binary alloy. SEM analysis showed that Cu10Al alloy was preferably corroded by grain boundaries, and the Ag addition modified the form of attack of the binary alloy. Cu-rich phases reacted with SCN(-) anions forming a film of CuSCN, and the Ag-rich phase is prone to react with SCN(-) anions forming AgSCN. Thus, binary and ternary alloys are susceptible to tarnish in the presence of thiocyanate ions.

Inheritance of resistance to pyrethroids in Triatoma infestans, the main Chagas disease vector in South America.

An outbreak of pyrethroid resistance was recently detected in Triatoma infestans from northern Argentina. To analyze the inheritance of the resistant phenotype, we carried out experimental crosses between resistant (R) and susceptible (S) strains captured in Argentina during 2005. The R strain was collected from sprayed houses in the north of the province of Salta while the S strain was collected in the province of Chaco. Both strains were bred in the laboratory for reciprocal crosses (F1), intercrosses (F2) and backcrosses (BC). The descendents were tested by a standard insecticide resistance bioassay. Resistance ratios were 1 for S strain, 103.36 for R strain and 18.34 for F1. The regression lines of F1 generations (R×S and S×R) showed no significant differences and were closer to that of the R parents, indicating that inheritance of deltamethrin resistance in T. infestans is autosomal and incompletely dominant (D=0.20). Chi-square analysis from responses of intercross and backcross progenies rejected the hypothesis of a single gene being responsible for resistance. The minimum number of independent segregation genes was three, as calculated with Lande's method. The genetic basis here described for the resistant phenotype indicate that, under pyrethroid selective pressure, the resistant genotypes could be easily spread to susceptible insects from resistant individuals, posing a major threat to vectorial control of Chagas disease.

First report of the genus Retortamonas (Sarcomastigophora: Retortamonadidae) in birds.

In studies carried out on the parasites infecting ostriches (Struthio camelus) in Spain, trophozoites of Retortamonas sp. have been found in the intestinal contents of 28 out of 146 slaughtered ostriches. The species infecting ostriches could not be determined from the morphological data available. However, these findings are important as they constitute the first report of the genus Retortamonas in birds.

Biological characterization of Trypanosoma cruzi strains.

Biological parameters of five Trypanosoma cruzi strains from different sources were determined in order to know the laboratory behaviour of natural populations. The parameters evaluated were growth kinetics of epimastigotes, differentiation into metacyclic forms, infectivity in mammalian cells grown in vitro and parasite susceptibility to nifurtimox, benznidazole and gentian violet. Differences in transformation to metacyclic, in the percentage of infected cells as well as in the number of amastigotes per cell were observed among the strains. Regarding to pharmacological assays, Y strain was the most sensitive to the three assayed compounds. These data demonstrate the heterogeneity of natural populations of T. cruzi, the only responsible of infection in humans.

Relationship between biological behaviour and randomly amplified polymorphic DNA profiles of Trypanosoma cruzi strains.

Once known some biological characteristics of six Trypanosoma cruzi strains, randomly amplified polymorphic DNA (RAPD) analysis was made. Cluster analysis by UPGMA (unweighted pair group method analysis) was then applied both to biological parameters and RAPD profiles. Inspection of the UPGMA phenograms indicates identical clusters, so supporting that usefulness of biological parameters to characterization of T. cruzi strains still remains.

[Effects of bezafibrate in the diet of hypertensive patients with dyslipidemia and hyperfibrinogenemia]. / Efecto de bezafibrato en la dieta de hipertensos con dislipidemia e hiperfibrinogenemia.

OBJECTIVE: To evaluate the fibrinogen and lipids response to diet plus bezafibrate in insulin-resistant patients with arterial hypertension and mixed hyperlipidemia. METHODS: A randomized double blind parallel design was used during a 90 days treatment period. Fibrinogen, lipids, insulin and peptide C assays as well as a glucose tolerance test were done at the start and end of treatment. The 28 patients received a hypolipemic diet low in refined sugars with bezafibrate added (400 mg/day) in 15 and a placebo in 13. RESULTS: The groups were similar in age, blood pressure and BMI. At the end of treatment, fibrinogen, cholesterol, triglycerides and LDL-C were lower in both groups as compared to the initial values, but only in the bezafibrate group there were: a) significant decrease in triglycerides (64 mg/dL, p 0.01); and b) marginal changes in fibrinogen (decreased 35 mg/dL, p = 0.09), total cholesterol (decreased 26 mg/dL, p = 0.10) and glucose/insulin ratio (increased from 4.4 to 5.2, p = 0.09). Bezafibrate lowered slightly the insulin level but did not affect peptide C. A correlation of changes in fibrinogen levels and the 60 min insulin concentration in the glucose tolerance test was higher in the bezafibrate group (r = 0.61) than in the placebo group (r = 0.23). CONCLUSIONS: In insulin resistant patients with high cardiovascular risk, bezafibrate and a placebo added to a hypolipemic diet decreased plasma fibrinogen. Bezafibrate lowered significantly the levels of triglycerides in these patients.

[Systemic lupus erythematosus: valvular regurgitation and its relation to anticardiolipin antibodies]. / Lupus eritematoso sistémico: insuficiencia valvular y su relación con anticuerpos anticardiolipinas.

The aim of this study was to assess the relationship between the incidence and severity of valvular regurgitation and the presence of high levels of anticardiolipin antibodies in a group of patients with systemic lupus erythematosus. Fifty patients aged 35.5 +/- 13.4 years and 84 healthy age and sex matched controls were studied with two dimensional echocardiography with color flow imaging. IgG and IgM anticardiolipin antibodies were measured in all patients within a week of the echocardiographic study. Patients had a similar incidence of aortic, tricuspid and pulmonic regurgitation than normals. However there was a greater incidence of mitral regurgitation among patients (56 vs 21% p < 0.001). The seven patients with moderate or severe mitral regurgitation had Libman Sacks vegetations of the valve. Twenty five of 28 patients with mitral regurgitation had increased anticardiolipin antibodies; moreover, these levels were significantly higher among patients with mitral regurgitation and thickened mitral valves than those with normal valves. Patients with increased anticardiolipin antibodies had a higher incidence of Libman Sacks vegetations. No association between the presence of these antibodies and the severity of aortic, pulmonic or tricuspid regurgitation was observed. It is concluded that the incidence of mitral valve regurgitation is increased in systemic lupus erythematosus and related to raised anticardiolipin antibodies.

[Differential diagnosis of congestive cardiomyopathy and myocardial ischemia: two-dimensional echocardiography has a limited value]. / Diagnóstico diferencial de la miocardiopatía dilatada y miscardiopatía isquémica: la ecocardiografía bidimensional tiene un valor limitado.

Two dimensional echocardiographic studies were performed in 70 patients with chronic heart failure. Thirty six had dilated cardiomyopathy and normal coronary arteries and 34 had ischemic cardiomyopathy with severe multivessel coronary disease. All patients had a dilated and hypocontractile left ventricle. Ejection fraction assessed by radionuclide ventriculography was less than 40% in all patients. Regional wall motion abnormalities were detected in 16 (44%) of 36 patients with dilated cardiomyopathy and 22 (65%) of 34 patients with ischemic cardiomyopathy (NS). High echodensity of the regional wall motion abnormality suggesting a myocardial scar were found in 4 (25%) of 16 patients with dilated cardiomyopathy and in 9 (41%) of 22 with ischemic cardiomyopathy (NS). Diffuse wall motion abnormalities were present in 20 (56%) patients with dilated cardiomyopathy and 12 (35%) with ischemic cardiomyopathy (NS). Right ventricular dilatation was found in 21 (58%) and 20 (59%) patients with dilated and ischemic cardiomyopathy, respectively (NS). No differences between groups were found regarding the left ventricular size and function. In conclusion, two dimensional echocardiography cannot be reliably used in patients with chronic heart failure to differentiate dilated cardiomyopathy from ischemic cardiomyopathy.

[Valvular insufficiency in dilated cardiomyopathy diagnosed by color Doppler echocardiography]. / Insuficiencia valvular en la miocardiopatía dilatada diagnosticada mediante ecocardiografía Doppler color.

In order to assess the incidence of valvular regurgitation in dilated cardiomyopathy, 26 patients, aged 32 to 61 years, were prospectively studied by two-dimensional echocardiography and color doppler flow imaging. Patients were in New York Heart Association functional class III or IV. All patients underwent coronary angiography which excluded coronary artery disease. Contrast ventriculography showed a dilated and hypocontractile left ventricle and right ventricular endomyocardial biopsy excluded specific heart muscle disease. Regurgitant flows were observed as a mosaic pattern and were semiquantitatively classified as mild, moderate or severe according to the width and depth of the regurgitant jets. Twenty-six (100%) patients had mitral regurgitation, 9 (34,6%) had aortic regurgitation, 12 (46.2%) had tricuspid regurgitation and 11 (42.3%) had pulmonary regurgitation. Multivalvular regurgitation was observed in 77% of patients occurring across two, three, or all four valves in 30.8%; 30.8% and 15.4% of patients, respectively. Two dimensional echocardiography color flow imaging shows a high prevalence of multivalvular regurgitation in patients with dilated cardiomyopathy.

[Cardiac tamponade as the first manifestation of cancer]. / Taponamiento cardiaco como primera manifestacion del cancer.

We report 3 patients having cardiac tamponade as the initial presentation of cancer. At the onset of symptoms all three patients were incorrectly diagnosed. Pulsus paradoxus and cardiomegaly on the Chest X-Ray were the main clinical features. Two dimensional echocardiography was vital revealing massive pericardial effusion with diastolic right atrial and ventricular collapse. All patients had bloody pericardial fluid removed and the histopathology of the metastatic pericardial tissue showed lung cancer, thymoma and lymphoma.

[Lactic acidosis in diabetic patients associated with buformin]. / Acidosis láctica en diabéticos asociada a buformina.

We report two diabetic patients who developed lactic acidosis following the use of Buformin. Treatment consisted of mechanical ventilation, massive bicarbonate administration, circulatory support with dopamine and peritoneal dialysis. Despite this, both patients died.