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Biomedical subjects

M F Silva

Publications and source records attributed to M F Silva.

31 records · Page 2Linked to original sources
PubMed1995

The role of somatic structure of the fungus Paracoccidioides brasiliensis upon B cell activation in experimental paracoccidioidomycosis.

In this study, we report an increase of the number of antibody-secreting cells and the augmentation of antibody production against unrelated antigens in mice infected with the fungus P. brasiliensis, as well as in mice inoculated with cell wall preparation isolated from P. brasiliensis (CW). The immunomodulatory effect of the live fungus and the CW preparation was dose-dependent, and their actions were mainly restricted to the i.v. or i.p. inoculation simultaneously with the sheep erythrocyte challenge by the i.v. route or restricted to i.p. inoculation of CW when bovine serum albumin (BSA) antigen was used. The dependence of antibody production on different routes of CW inoculation was correlated with the number of antigen-specific B cells in the spleen as determined by direct and reverse plaque-forming cell assays. The immunization schedules using CW preparation caused a preferential production of IgM and IgG3 antibodies. The results also showed that the hyperactive humoral immune response of mice induced by i.p. inoculation of CW was devoid of polyclonal B cell activation compared with the effects observed for the lipopolysaccharide (LPS)-treated groups. Paracoccidioides brasiliensis CW components may have potent immunological properties related to the non-specific B cell activation found in paracoccidioidomycosis.

Animals↗
PubMed1995

Veno-occlusive dysfunction of corpora cavernosa: comparison of diagnostic methods.

Pump cavernosometry, pharmaco-cavernosometry, gravity cavernosometry and the intracavernous pressure drop test are the most used tests for the diagnosis of venoocclusive dysfunction. To verify whether patients show equivalent results in each of these four tests, and to ascertain whether there is any influence of the sequence of the exams over the results, 123 male patients with erectile dysfunction, aged 21 to 82 years (mean 48), were evaluated. All were submitted to the four tests in randomized sequence. Two criteria were used to define the normal results of pump cavernosometry and pharmaco-cavernosometry, both based on patients with normal veno-occlusive function. The incidence of normal results varied from 6.5% in pump cavernosometry according to criterion I to 64.2% in pharmaco-cavernosometry according to criterion II. Results of the four tests agreed completely (all normal or all abnormal) in 43.9% of the patients when criteria I was used and 58.3% with criteria II. Incidence of normal results in each test did not vary according to the sequence in which the exams were done. Pump cavernosometry, pharmaco-cavernosometry, gravity cavernosometry and intracavernous pressure drop test did not show equivalent results for individual patients. Results were not influenced by the sequence of the tests.

Adult↗
PubMed1994

Protection against tuberculosis by passive transfer with T-cell clones recognizing mycobacterial heat-shock protein 65.

We have previously shown that mice vaccinated by injection with J774 macrophage-like tumour cells that expressed Mycobacterium leprae heat-shock protein (hsp) 65 as a transgene had acquired a remarkably high degree of protection against subsequent challenge with virulent M. tuberculosis. We show here that antigen-specific T cells cloned from spleens of such vaccinated animals can transfer a high level of protection to non-vaccinated recipients. The most efficient cells were of T-cell receptor (TCR) alpha beta+ and CD4- CD8+ type and specifically lysed mycobacteria-infected macrophages. These findings are consistent with the importance for protective immunity of engaging the endogenous antigen-presenting pathway to bias the immune response towards a cytolytic action against a mycobacterial antigen that is expressed at the surface of infected macrophages. TCR gamma delta+ and TCR alpha beta+ cells interacted synergistically.

Animals↗
PubMed1987

Effects of water-soluble components of cheese on experimental caries in humans.

The effect of water-soluble components of extra-old Cheddar cheese on experimental caries was tested by means of the seven-day intraoral cariogenicity test (ICT). Two bovine enamel blocks were placed in each buccal flange of the dental appliances of five volunteers. One side of each appliance (experimental) was dipped in a 25% water extract of the cheese for five min, while the other side (control) was dipped in de-ionized water. Immediately thereafter, the appliance was returned to the subject's mouth, and two 60-second rinses with 10% sucrose were performed. These procedures were repeated six times per day. The cheese-extract dippings reduced the cariogenicity of the sucrose by an average of 55.7% (p less than 0.01), as assessed by enamel microhardness. Neither the mean resting pH nor the mean minimum pH in response to sucrose was significantly different between the experimental and control sides. The concentration of calcium was significantly higher in plaque from the experimental side (32.44 micrograms/mg) as compared with the control side (19.36 micrograms/mg, p less than 0.01). The concentration of plaque phosphorus was higher on the experimental side (12.90 micrograms/mg) than on the control side (9.61 micrograms/mg); however, the difference was not statistically significant. These results show that cheese has one or more water-soluble components which reduce experimental caries in human subjects.

Adult↗
PubMed1987

Effects of cheese extract and its fractions on enamel demineralization in vitro and in vivo in humans.

In order to isolate and identify the most active anti-cariogenic components(s) of aqueous cheese extract (CE), we separated it into low (LMW) (MW less than 500), medium (MMW) (500 less than MW less than 10,000), and high (HMW) (MW greater than 10,000) molecular weight fractions by means of the Amicon ultrafiltration system. These fractions were then tested in vitro with a bacterial system containing S. mutans, adapted from that of Turtola (1977). The LMW fraction reduced the demineralization caused by the fermentation of sucrose by 96% (p less than 0.001) as compared with the water control; this was not significantly different from a 50% concentration of the CE. The MMW and HMW fractions reduced demineralization by 36 and 42%, respectively. The concentrations of acid-soluble calcium and phosphorus in CE, LMW, MMW, and HMW were 1509 and 462, 991 and 310, 231 and 7, and 162 and 3 micrograms/mL, respectively. A solution containing the same levels of calcium and phosphorus as CE was somewhat more effective in reducing demineralization in vitro than was CE itself (p less than 0.01). In vivo, the addition of these same calcium and phosphorus levels to a 10% sucrose solution reduced its cariogenicity by 67% (p less than 0.001), as judged by the intra-oral cariogenicity test (ICT). Plaque calcium and phosphorus concentrations were significantly higher in the ICT plaque samples subjected to the sucrose-Ca,P solution (p less than 0.01) than in the sucrose control. The resting pH, minimum pH, and shape of the pH curves produced by the sucrose control and sucrose-Ca,P were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Evaluation of the therapeutic activity of fluconazole in acute experimental infection caused by Trypanosoma cruzi].

On hand of information that fluconazole can inhibit Trypanosoma cruzi, infection, an experimental investigation in acutely infected mice treated with 200 mg/kg daily of this drug during one month was carried out. Parasitemia patency, blood culture, sub-inoculation and histologic examination were the parameters used to evaluate the potential therapeutic activity of the drug. The results did not confirm the hypothesis, but it would be desirable to conduct new trials with this and other imidazole compounds.

Acute Disease↗
PubMedDate not supplied

Urological evaluation of sexual partners of women with human papillomavirus (HPV) infection.

Cancer of the uterine cervix has been related to HPV infection, based on clinical and laboratory data. The high recurrence rate in couples undergoing treatment for HPV infection points to a probable viral reservoir, either in subclinical lesions or in male internal genital organs. We have evaluated 31 men, all sexual partners of women with HPV infection. Eleven patients (35.5%) had related lesions: 4 (12.9%) with condyloma acuminatum; 5 (16.1%) with lesions revealed by magnified examination after reaction with 5% acetic acid and 2 (6.5%) with condyloma and subclinical lesions. A short-term follow-up confirmed a successful treatment with podophyllin.

Adult↗
PubMedDate not supplied

[Oral hygiene in university students].

The family income of students entering the University suggests that they should be aware of basic rules of oral hygiene. Thus, oral hygiene was evaluated in a study conducted on 336 1st-year students enrolled in the Pharmacy and Dentistry Course of Ribeirão Preto, USP. The results showed that 42% of the students consult a dentist twice a year; the frequency of tooth brushing was four times a day, with no difference between the use of soft (48%) and medium (49%) brushes, and brushing time was 1 to 5 min. The students use dental floss (87%) and rinse their mouth with Cepacol (37%), and females brush their tongue at higher frequency (70%). Fifty-two percent of the students reported the occurrence of gingival bleeding when they brush their teeth.

Adult↗
PubMedDate not supplied

[Experimental evaluation in mice of vitamin B complex repellent activity against Culex quinquefasciatus].

One untested but widely held opinion in Brazil is that oral use of vitamin B complex is useful as a mosquito repellent. We exposed Balb-C mice to a large number of Culex quinquefasciatus females, after giving vitamin B complex to mice (drops by mouth). There was no difference between mice attractiveness to mosquitoes in the vitamin B group compared to normal, but very few of the females bite mice in both groups, so the experiment was inconclusive. We suggest further experiments in this subject, using other models were the animals are more attractive to mosquitoes.

Animals↗
PubMedDate not supplied

Intestinal transit and opaque enema study in chagasic mice.

The report concerns as experimental study utilizing thirty-three mice inoculated subcutaneously with 1000 blood forms of Trypanosoma cruzi. Intestinal transit and morphology of colon were studies by means of X-rays. In subacute stage intestinal transit was normal. In chronic stages the mice displayed a delay in evacuation time. In one out of 12 animals the opaque enema documented the existence of megacolon.

Animals↗