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Biomedical subjects

N Silva

Publications and source records attributed to N Silva.

At least 19 recordsLinked to original sources
PubMed2006

Evidence of allopolyploidy in Brachiaria brizantha (Poaceae: Paniceae) through chromosome arrangement at metaphase plate during microsporogenesis.

In the hexaploid (2n = 6x = 54) accession B176 of Brachiaria brizantha, one cytological characteristic differentiated it from the other accessions previously analyzed with the same ploidy level. Nearly 40% of meiocytes displayed the chromosome set arranged at two metaphase plates at the poles of the cell, close to the membrane. In these cells, both metaphase plates were arranged in an angle to form a typical tripolar spindle. Therefore, cells did not show normal chromosome segregation at anaphase I. Only nine univalent chromosomes migrated from each plate to the opposite pole with the remainder staying immobile on the plate. As a result of such spindle orientation and chromosome behavior, trinucleate telophases I were recorded. After telophase, cytokinesis eliminated the small nuclei into a microcyte. The second division proceeded normally, with the presence of microcytes in all phases. The origin of such an abnormality was explained on the hexaploid level of the accession which could have resulted by chromosome doubling of a triploid derived from species that did not display the same behavior for spindle organization. The high percentage of meiotic abnormalities recorded in this accession compromises fertility and renders it inadequate for the breeding program.

Brachiaria↗
PubMed2006

Coagulase gene polymorphism of Staphylococcus aureus isolated from goat mastitis in Brazilian dairy herds.

AIMS: To investigate the coagulase gene polymorphism of Staphylococcus aureus isolated from mastitic goat's milk. METHODS AND RESULTS: A typing procedure based on coagulase gene polymorphism was used to discriminate S. aureus isolated from goat mastitis. Thirty-six strains collected from goats belonging to herds from northern Ceara State and Serrana region of Rio de Janeiro State were analysed. Based on restriction fragment length polymorphism of 3' end coagulase gene, the goat strains were grouped into 11 types. In northern Ceara herds, the predominant type was found in 60% of the strains, while in the Serrana region herds the two most common accounting for 62.5% of the strains. CONCLUSIONS: The analysis of the coa gene proved to be useful for typing S. aureus from goat mastitis. Although the results showed that goats from the studied regions were infected by S. aureus strains harbouring more than one coagulase genotype, only one or two types predominated. SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of the prevalent strains within a herd or region is a necessity. The important virulence factors could be identified in such strains and this information can then be used as a specific base to develop S. aureus mastitis control measures.

Animals↗
PubMed2004

Cell differentiation and infectivity of Leishmania mexicana are inhibited in a strain resistant to an ABC-transporter blocker.

We analysed whether markers of cell differentiation and infectivity differed when compared to the parental sensitive strain [NR(Gs)] in an in vitro selected Leishmania strain [NR(Gr)] resistant to Glibenclamide, an ATP-binding-cassette (ABC)-transporter blocker. The data show that the cell body area was larger in NR(Gr) compared to NR(Gs) and that functional characters associated with an infective metacyclic phenotype, such as resistance to the lytic effect of the alternative complement pathway and expression of the Meta-1 protein, were reduced. The infectivity of NR(Gr) to J774.1 macrophages was also significantly reduced. These results suggest that resistance in Leishmania against Glibenclamide, a general blocker of P-glycoproteins, could produce functional modifications that may be relevant for Leishmania differentiation, infectivity and survival.

ATP-Binding Cassette Transporters↗
PubMed2003

Effects of different disinfection treatments on the natural microbiota of lettuce.

In this study, water and eight sanitizing solutions (vinegar at 6, 25, and 50%; acetic acid at 2 and 4%; peracetic acid at 80 ppm, sodium hypochlorite at 200 ppm, and sodium dichloroisocyanurate at 200 ppm) were compared in terms of their effectiveness against the natural microbiota of lettuce. All of the samples were kept in contact with the sanitizing solutions for 15 min, and the effectiveness of a sanitizing agent was evaluated on the basis of the number of decimal reductions of the total aerobic mesophilic count, the mold and yeast count, the total coliform count, and the Escherichia coli count. The average initial levels of these organisms in the samples were 6.94 log10 CFU/g for aerobic mesophilic microorganisms, 5.62 log10 CFU/g for molds and yeasts, and 3.25 log10 CFU/g for total coliforms. Of 10 samples analyzed, only 4 contained E. coli, and the average initial level of this microorganism in these 4 samples was 1.64 log10 CFU/g. Salmonella was not detected in any of the samples tested. The decimal reductions of the populations of aerobic mesophilic microorganisms, molds and yeasts, total coliforms, and E. coli were 0.78, 0.87, 0.82, and >0.14 log10 CFU/g, respectively, in water; 2.89, >3.41, >2.21, and >0.26 log10 CFU/g, respectively, in 50% vinegar; 2.42, >3.20, >1.99, and >0.26 log10 CFU/g, respectively, in 25% vinegar; 1.83, 2.57, 1.58, and >0.26 log10 CFU/g, respectively, in 6% vinegar; 3.91, >3.58, >2.25, and >0.26 log10 CFU/g, respectively, in 4% acetic acid; 3.37, >3.53, >2.25, and >0.26 log10 CFU/g, respectively, in 2% acetic acid; 1.85, 2.32, 1.44, and >0.20 log10 CFU/g, respectively, in 80 ppm of peracetic acid; 2.63, 2.75, 1.91, and >0.26 log10 CFU/g, respectively, in 200 ppm of sodium hypochlorite; and 3.23, >3.08, >1.95, and >0.26 log10 CFU/g, respectively, in 200 ppm of sodium dichloroisocyanurate. Statistical analysis of the results showed that the effectiveness levels for all of the sanitizing agents tested were equivalent to or higher than that for sodium hypochlorite at 200 ppm.

Bacteria↗
PubMed2001

Effect of some granular insecticides currently used for the treatment of maize crops (Zea mays) on the survival of inoculated Azospirillum lipoferum.

Four insecticides, carbofuran, chlormephos, terbufos and benfuracarb, currently used on maize (Zea mays) at sowing, were tested for their compatibility with Azospirillum lipoferum strain CRT1 used as an inoculant to improve maize growth and yield. The growth or survival of A lipoferum was studied in the presence of the insecticides: (1) in liquid and solid cultures of the bacteria, (2) when a commercial inoculant (Azogreen-m, Liphatech, Meyzieu, France) was inoculated directly on insecticide granules, (3) when inoculated Azogreen-m granules were mixed with insecticide granules and (4) when inoculated Azogreen-m granules were delivered separately to the seed bed. Of the four insecticides tested, only terbufos had a slight effect on growth of A lipoferum in solid cultures. All the insecticides decreased the survival of A lipoferum when the bacteria were inoculated directly on to the granules, or when inoculated Azogreen-m granules were mixed with an insecticide. We hypothesize that the discrepancies between bacterial culture tests and survival studies might be explained by the conditions of desiccation encountered during inoculation of the granules. Desiccation stress could increase the toxic effect of the insecticides. We therefore suggest including desiccation stress in the biotest used to assess inoculant-pesticide compatibility.

Azospirillum↗
PubMed2001

Evaluation of efficacy and safety of itraconazole oral solution for the treatment of oropharyngeal candidiasis in aids patients.

This study was a non-comparative multicenter clinical trial to evaluate the efficacy and tolerability of itraconazole oral solution 200 mg/day (100 mg twice a day in the fasting state) for the treatment of oropharyngeal candidiasis in AIDS patients. We included 50 patients who were treated and followed for up to 3 weeks after ending therapy in the analysis. Mycological cures at the end of therapy occurred in 20/50 patients (40%), but colonization by Candida sp. was recorded in 42/50 (84%) by the end of follow-up. A high rate of clinical response was observed in 46/50 (92%), and the response was sustained for up to 21 days after stopping therapy in 24/46 patients (52%). Clinical relapses were documented among 22 patients, but all causative fungal organisms associated with a relapse were susceptible to itraconazole. There were many patients with persistence or recurrence of Candida, but without mucositis. Relapse of Candida mucositis was significantly related to low levels of CD(4) lymphocytes exhibited by symptomatic patients. The drug was well tolerated by all but 1 patient. We conclude that itraconazole oral solution (100 mg bid for 7-14 days) is a well tolerated and effective treatment for suppressing the symptoms of oropharyngeal candidiasis in AIDS patients. Patients with severe immunosuppression may relapse and require frequent cycles of treatment or longterm suppressive therapy.

AIDS-Related Opportunistic Infections↗
PubMed2001

Comparison of culture media, simplate, and petrifilm for enumeration of yeasts and molds in food.

The efficacy of three culture media, dichloran rose bengal chloramphenicol (DRBC), dichloran 18% glycerol agar (DG18), and potato dextrose agar (PDA) supplemented with two antibiotics, were compared with the Simplate and Petrifilm techniques for mold and yeast enumeration. The following foods were analyzed: corn meal, wheat flour, cassava flour, bread crumbs, whole meal, sliced bread, ground peanuts, mozzarella cheese, grated parmesan cheese, cheese rolls, orange juice, pineapple pulp, pineapple cake, and mushroom in conserve. Correlation coefficients of DRBC versus PDA and DG18 for recovering total mold and yeast counts from the composite of 14 foods indicated that the three media were generally equivalent. Correlation coefficients for Petrifilm versus culture media were acceptable, although not as good as between culture media. Correlation coefficients of Simplate versus DRBC, DG18, PDA, and Petrifilm for recovering total yeasts and molds from a composite of 11 foods demonstrated that there was no equivalence between the counts obtained by Simplate and other culture media and Petrifilm, with significant differences observed for the most foods analyzed.

Agar↗
PubMed2000

Inactivation of bovine herpesvirus 1 in semen using a hyperimmune egg yolk semen extender.

Hyperimmune egg yolk semen extender was used for the inactivation of bovine herpesvirus (BHV-1) in experimentally infected bovine semen. As much as 5 x 10(4) TCID50/ml of virus was inactivated in semen as assayed by tissue culture. Moreover the hyperimmune egg yolk semen extender did not produce any adverse effect on the quality of the semen after being frozen/thawed in comparison with normal egg yolk semen extender (P > 0.05). The hyperimmune egg yolk semen extender is considered an important tool for containing the spread of BHV-1 from infected semen.

Animals↗
PubMed2000

Sinus tissue pharmacokinetics after oral administration of amoxicillin/clavulanic acid.

OBJECTIVES: The in vitro synergy of the amoxicillin/clavulanic acid combination has not always translated in vivo into clinical superiority compared with amoxicillin alone. Specifically, conflicting reports have disputed the superiority of the combination in the treatment of both acute otitis media and acute sinusitis. One possible reason for this may have to do with inadequate target tissue pharmacokinetics. To explore this possibility in the sinuses, we undertook the present investigation. STUDY DESIGN: A randomized, open, single-dose, sinus tissue pharmacokinetic study with oral amoxicillin/clavulanic acid. METHODS: Twenty-three adult patients with chronic rhinosinusitis who had been selected for surgery were randomly allocated to receive a tablet of 875/125 mg amoxicillin/clavulanate 2 to 4 hours before surgery began. During the operation tissue samples were collected at specific sinonasal sites for determination of both amoxicillin and clavulanic acid concentration levels. RESULTS: Amoxicillin displayed adequate tissue levels throughout the sinuses, high enough to cover common susceptible pathogens. However, the presence of clavulanate was detected in only half of the sinonasal tissue samples. CONCLUSIONS: The kinetics of oral clavulanic acid apparently fails to provide a widespread anti-beta-lactamase activity capable of enhancing the activity of amoxicillin in all parts of the sinuses. Despite this, amoxicillin/clavulanic acid maintains a central role in the treatment of acute rhinosinusitis, because amoxicillin is still the most effective oral beta-lactam against Streptococcus pneumoniae, a particularly virulent and increasingly resistant upper respiratory tract pathogen. Also, as our data show, a concomitant anti-beta-lactamase activity can be expected to occur, although in an unpredictable fashion.

Adult↗
PubMed1999

Trypanosoma cruzi meningoencephalitis in HIV-infected patients.

Five cases of Trypanosoma cruzi meningoencephalitis in HIV-infected patients are reported. All patients presented with mass lesions on head computed tomographic scan, trypanosomes in the cerebrospinal fluid and failure to respond to antitoxoplasmosis therapy. Benznidazole therapy was associated with clinical improvement in 1 patient. Another 4 patients had T cruzi identified in a peripheral smear. T cruzi needs to be considered in the differential diagnosis of HIV-infected patients with central nervous system mass lesions if they have a history of appropriate exposure.

AIDS-Related Opportunistic Infections↗
PubMed1999

Expression of a pilin subunit BfpA of the bundle-forming pilus of enteropathogenic Escherichia coli in an aroA live salmonella vaccine strain.

Enteropathogenic Escherichia coli (EPEC) is a major cause of childhood diarrhea in developing countries and is a leading cause of severe diarrheal illness among Brazilian infants. As one approach to constructing a vaccine candidate against diarrhea caused by EPEC, we evaluated whether the pilin subunit (BfpA) of the bundle-forming pilus (BFP) could be expressed by a live Salmonella vaccine strain. Several copies of the coding region of BfpA (bfpA) were amplified by PCR from a preparation of the EAF plasmid of EPEC strain B171 and cloned into plasmid vectors. An intact copy of bfpA was subcloned into the heat inducible prokaryotic expression vector pCYTEXP1, and the resulting pBfpA was used to transform the aroA S. typhimurium strain SL3261, generating SL3261(pBfpA). The recombinant vaccine strain was able to express, but not to process, rBfpA as evidenced by a prominent 21 kDa protein that crossreacted with anti-BFP antiserum found only in extracts of heat-treated SL3261(pBfpA), but not in strains of untreated SL3261(pBfpA) or SL3261 not carrying the plasmid. Furthermore, rBfpA accumulation was not toxic to the Salmonella host, as evidenced by similar plating efficiencies between induced and uninduced strains of SL3261(pBfpA). Finally, SL3261(pBfpA) orally administered to BALB/c mice was capable of eliciting a sustained and vigorous humoral immune response to BfpA, achievable even with a single oral dose of approximately 10(9) organisms. Therefore, this pilin product may serve as a potential immunogen as part of a live combined vaccine strategy to prevent two of the major public health problems in Brazil--salmonellosis and EPEC childhood diahrrea.

Administration, Oral↗
PubMed1999

Evaluation of the effects of different trypsin treatments on semen quality after BHV-1 inactivation, and a comparison of the results before and after freezing, assessed by a computer image analyzer.

Semen infected experimentally with infectious bovine rhinotracheitis virus (BHV-1) was treated with trypsin at concentrations of 0.30%, 0.25% and 0.15%, with or without (w or w/o) trypsin inhibitor in order to render the semen virus free. The trypsin treatments (at 0.30% and 0.25% by concentration) inactivating the virus up to 10(4) TCID50/ml, and its effects on semen quality were assessed weekly from the 1st to 20th week after being frozen. The following parameters were determined using a computerized semen analysis system (Hamilton Thorn motility analyzer, HTM): total motility, progressive motility and linearity of sperm cells. The results showed that the total and progressive motility of sperm cells were reduced in frozen/thawed semen, principally in the semen treated with trypsin at concentrations of 0.30%. Moreover, the plasma membranes were damaged by trypsin treatments (0.30% by concentration), as determined by the hypoosmotic swelling test (HOS test). These findings suggest that trypsin treatments were effective against the virus however the effects on semen quality and the possibility of a decrease in semen fertility were clear. Trypsin treatment could be recommended at a maximum concentration of 0.25% (w/o trypsin inhibitor) on semen with a high concentration and high motility values of spermatozoa before freezing.

Animals↗
PubMed1999

Production of enterotoxins and toxic shock syndrome toxin by Staphylococcus aureus isolated from bovine mastitis in Brazil.

The production of toxic shock syndrome toxin 1 (TSST-1) and enterotoxins (SE) A, B, C and D by bovine mastitis isolates of Staphylococcus aureus was evaluated by immunodiffusion using the Optimum-Sensitivity Plate method. S. aureus strains were isolated from bovine mastitis in 23 dairy herds in the state of Minas Gerais, Brazil, during 1994-9. Of 127 isolates, 83 (65.04%) produced one or several toxins, and among them production of SE was found in 54 (43.0%) isolates, of which 1138 (29.09%) secreted enterotoxin identified as type D. TSST-1 was found in 5829 (45.723.0%) isolates.

Animals↗
PubMed1999

Occurrence of Escherichia coli O157:H7 in hamburgers produced in Brazil.

The occurrence of Escherichia coli O157:H7 was evaluated in 886 samples of hamburgers produced by eight manufacturers in the south and southeast of Brazil from January to September of 1997. The pathogen was not detected in any of the samples analyzed, although 17 (1.9%) showed the presence of E. coli strains, which presented agglutination with O157 antiserum. These strains were not confirmed, since a subsequent identification indicated that they were fermentation positive for sorbitol, incapable of agglutination with the antisera of other commercial brands, and nonproducers of verocytotoxins. A high rate of false-presumptive-positive tests was observed with strains of enterobacteria when isolated by the culture method and when using a commercially purchased enzymatic immunoassay. This high rate of false presumptive positives was likely because the initial screening for sorbitol-negative strains was carried out using phenol red sorbitol 4-methylumbelliferyl-beta-D-glucuronide agar, which was shown to be inadequate for this purpose.

Animals↗
PubMed1998

Identification of the in vivo topically applied "human-identical" ceramides included in negatively charged liposomes.

Among the different classes of human epidermal lipids, Ceramides are definitely one of the most important and studied class judging from the significant amount of scientific information accumulated over the years, specially after being established its crucial role in skin physiology and pathophysiology. However, a clear demonstration of its usefulness resulting from the regular use of these substances included in topical formulations, either in a therapeutical or in a cosmetological perspective have not been entirely achieved. Many difficulties are normally present, from its origin to formulation and protocol design, and to the experimental demonstration of the relative efficacy of these compounds. In the present paper, the authors developed a systematic approach to the problem, using "human-identical" ceramides included into negatively charged liposomes, which were topically applied in a normalised panel of human healthy volunteers. Biological analysis were conducted with non-invasive methodologies by means of bioengineered reference methods (Epidermal capacitance, Evaporimetry; Light Transmission Profilometry; and High Resolution Ultrasonography). The experimental methodologies included the study of acute effects as well as the study of the effects resulting from continuous repeated application of formulations, basically expressed in terms of epidermal water content and skin surface profile. Additionally, an eventual protective "barrier" reinforcement resulting from ceramide application was also assessed by means of a SLS (5% solution) challenge-test. This systematic although preliminary approach indicated that these compounds do have a considerable impact on human skin physiology, justifying further research to clarify their potential use in human cutaneous health.

Adult↗
PubMed1997

Blastocystis hominis as a Potential Cause of Diarrhea in AIDS Patients: a Report of Six Cases in Bahia, Brazil.

The role of Blastocystis hominis as a human pathogen is controversial, although there is some evidence suggesting that it is the agent implicated in causing diarrhea in immunocompromised patients. We report 6 cases of AIDS patients presenting with diarrhea with no agents identified in their stools exceptB. hominis. In all cases, treatment was followed by complete recovery from symptoms and clearance of B. hominis from the patients' stools. In 2 cases, relapse of diarrhea was followed by a positive stool examination for B. hominis oocysts, which again disappeared after treatment. These findings provide additional evidence for considering B. hominis a potential intestinal pathogen in AIDS patients.

Journal Article↗
PubMed1997

Leprosy and AIDS: Report of a Fatal Case and Literature Review.

We report a severe fatal lepromatous leprosy case in an adult homosexual male 2 years after AIDS class IV was diagnosed. Multidrug therapy including thalidomide for erythema nodosum leprosum (ENL) was ineffective. The patient died with multiple large skin ulcerations due to multibacillary leprosy. Leprosy in AIDS patients may present as a severe uncontrolled disease, with extensive ENL unresponsive to therapy.

Journal Article↗