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Biomedical subjects

C R Paula

Publications and source records attributed to C R Paula.

33 records · Page 2Linked to original sources

Acute effect of aflatoxin B1 on different inbred mouse strains II.

The acute effects of Aflatoxin B1(AFB1) were evaluated on C57B1/6, CBA/J, and Balb/c mice challenged with a single intraperitoneal dose of the mycotoxin (60 mg/Kg animal weight). 90 mice per strain were divided into three groups of 30 animals each: the intoxicated group and control groups I and II. Intoxicated mice were injected intraperitoneally with AFB1 dissolved in corn oil, while control I mice received corn oil only (0.01 ml/g) by the same route. Lots of 10 animals from the intoxicated and control groups were sacrificed 24, 72 and 168 hours after challenge. Control mice II remained untreated and were used as standards of normality for biochemical (hepatic and renal function) and hematological evaluation. AFB1 was detected in the liver of C57B1/6 and CBA/J mice 24 hours (1.46 and 0.75 ng/g, respectively), 72 hours (2.30 and 0.08 ng/g, respectively), and 168 hours (2.18 and 0.25 ng/g, respectively) after challenge. The mycotoxin was also observed in the liver of B10A mice (6.20 ng/g) 72 hours post-injection. The most evident histological lesions were observed 168 hours after treatment in C57B1/6 and B10A mice. Serum levels of alkaline phosphatase in intoxicated C57B1/6 and B10A mice were significantly higher than those of control I and II animals. The histopathologic lesions and biochemical changes were very discrete in Balb/c and CBA/J mice. It is included that strains C57B1/6 and B10A are more susceptible than strains CBA/J and Balb/c to the acute effects of AFB1. Such difference probably reflects each strain's ability to biotransform and eliminate AFB1 and its metabolites.

Aflatoxin B1↗

Biochemical, antigenic and allergenic characterization of crude extracts of Drechslera (Helminthosporium) monoceras.

In a previous study with airborne mould extracts we verified that Drechslera (Helminthosporium) monoceras presented stronger reactions than those presented by 42 other moulds isolated in São Paulo city. In the present study, we evaluated the biochemical composition and the antigenicity of crude extracts obtained from vegetative and conidial stage of D. monoceras using Czapeck broth (CB) modified and tris-HCl for extraction. The maximum values of total proteins and lipids were verified in the crude extract obtained in the 28th day of growth, and maximum values of carbohydrates were observed in the extracts of the 16th, 22nd and 26th days. The fractionated proteins by SDS-PAGE presented bands with molecular weights between 14.4 to 67 Kd; the 28th day extract showed a larger number of bands. The carbohydrates and amino acids were characterized by thin-layer chromatography. The antigenicity of the crude extracts was verified by immunodiffusion reaction in agar against rabbit hyperimmune sera. Precipitation lines were observed in all studied extracts and common antigenic molecular populations. Based on the above results, the 28th day extract was selected to verify the induction of IgE antibody responses in immunizations of Balb/c and cAF-1 mice, and titer by passive cutaneous anaphylaxis test using Wistar rats. The maximum titers obtained were 160 in cAF-1 mice and 1.280 in Balb/c mice. The results suggest that the 28th day extract contains allergenic fractions and should be chosen for future studies related to fractionation, characterization and standardization in diagnostic methods and immunotherapy.

Allergens↗

Oral manifestations of diabetes mellitus in controlled and uncontrolled patients.

The authors studied the oral manifestations of a sample of 70 diabetic patients, divided into controlled and uncontrolled patients. Medical history and stomatological data were analyzed and diabetic controlled patients were matched to uncontrolled patients. The main symptoms observed were hyposalivation, taste alterations and burning mouth, with the main sign being parotid enlargement. The lesions observed were candidosis of the erythematous type and proliferative lesions both associated to the use of total prosthesis. No pathognomic lesions or alterations could be observed in relation to the disease. The frequency of carriers of Candida albicans and also the lesions observed could be compared to normal patients also using total dentures.

Candidiasis, Oral↗

Mycoflora of the toxic feeds associated with equine leukoencephalomalacia (ELEM) outbreaks in Brazil.

The mycoflora of 39 feed samples associated with 29 Equine Leukoencephalomalacia (ELEM) outbreaks was studied from 1988 to 1990, in Brazil. Microbiological examination indicated Fusarium spp. as the most frequent mold which occurred in 97.4% of samples followed by Penicillium spp. in 61.5% and Aspergillus spp. in 35.9%. The moisture content of feed implicated in death of horses was above 15% which can favor the development of Fusarium spp. From the genus, F. moniliforme was the predominant species with an occurrence of 82.0%. Two additional species, not commonly associated with animal toxicosis, were isolated in low frequency, F. proliferatum (12.8%) and F. subglutinans (2.6%). It is important to emphasize that the isolation of F. proliferatum and F. subglutinans from feed obtained from the epizootic areas has not been documented previously in Brazil.

Animal Feed↗

Oral yeasts in patients with cancer of the mouth, before and during radiotherapy.

The yeasts of patients with oral cancer has been studied before and during Xr-therapy. Gram and PAS smears revealed an increase of yeast-like structures, during treatment, from 56% to 66% of the cases. Before radiotherapy oral yeasts were isolated from 56% of the patients with cancer represented by Candida albicans (30%); C. tropicalis (12%); C. glabrata and C. krusei (4%), besides six other different species (2%). During radiotherapy yeasts were isolated in 72% of the cases, as follow: C. albicans (36%); C. tropicalis (16%); Rhodotorula rubra (6%); C. kefyr; C. krusei and Pichia farinosa (4%), besides other nine species (2%). C. albicans serotype A represented 93% of the isolated samples, before treatment and 88.8% during Xr-therapy.

Adult↗

Dimorphism of Scopulariopsis brevicaulis: morphogenesis of the mould to yeast phase.

The dimorphism of Scopulariopsis brevicaulus was induced in malt agar (Oxoid), at 37 degrees C and 5-10% rate of CO2. Six cultures of S. brevicaulus were converted from hyphae to yeast-like cells by the following processes: One was that the hyphae formed intercalar and terminal chlamydoconidia-like cells. These cells increased in size, gained double contour and gave rise to budding cells. The other process was via conidia that assumed yeast characteristics. So, a transformation cycle M----Y was proposed. The yeast-like form presented slow reversion to the mould phase, standing, many times, in transition forms. A high concentration of sugars, peptone, temperature of cultivation of 37 degrees C and 5-10% rate of CO2 seem to be favourable factors for the maintenance of the yeast phase. Ethanol, E.D.T.A., potassium nitrate, temperature of 25 degrees C and aerobiosis are considered favourable factors to conversion of the mould phase.

Animals↗

In vitro study of the antibiotic activity of diterpenes.

The antibiotic activity of 16 diterpenes and of 2 phenanthrene derivatives of diterpene origin, isolated from Brazilian plants was investigated against bacteria, yeasts, dermatophytes and aflatoxin-producing fungi. Eight of the compounds were completely inactive. None showed inhibitory activity against the Gram-negative bacteria assayed or against the Aspergillus species. The phenanthrene derivatives, chemically very similar to phytoalexins isolated from orchids, were especially active.

Bacteria↗

Evaluation of a fluorescent method (fluorescein diacetate and ethidium bromide solution) in the study of the viability Cryptococcus neoformans strains.

The effectiveness of the fluorescent viability test (fluorescein diacetate-FDA and ethidium bromide-EB-solution) compared to the plaque counting test (Miles & Misra M & M) was performed on 10 samples of Cryptococcus neoformans cultivated in Sabouraud dextrose agar at 25 degrees C. The optimum incubation period of 50 minutes was determined. Growth curves of the fungal strains studied based on the mean cell number were drawn for both the FDA & EB and M & M methods. The statistical evaluation (Student's T test) of the average sum of the viable cell counts showed that the FDA-EB method is more sensitive than the M & M test for the studied species. The growth curves of the samples usually followed a homogeneous pattern comparable to other non-dimorphic fungi.

Animals↗

A new fluorescent viability test for fungi cells.

The fluorescein diacetate-ethidium bromide (FDA-EB) fluorescence method, primarily used to determine viability of mammalian cells, was applied to several fungi species. Living fungi cells produced fluorochromasia, i.e., an intracellular accumulation of fluorescein which could be easily visualized as a green color under the U.V. microscope. Dead cells showed a red bright color due to ethidium bromide penetration. The FDA-EB test can be successfully employed to assay yeast and yeast like cells viability since a good correlation was observed between this assay and the colony count technique. The main advantages of FDA-EB test are its speed, high sensitivity and simplicity.

Fluoresceins↗

Postharvest and stored corn in Brazil: mycoflora interaction, abiotic factors and mycotoxin occurrence.

The mycoflora of 130 samples of postharvest and stored corn was analysed throughout one year. The sample originated from Riberirão Preto, State of São Paulo, Brazil. The influences of abiotic factors (moisture content, relative humidity, temperature, rainfall) and mycotoxin occurrence were also verified. The isolation of the fungi was performed with Potato Dextrose Agar. Fungi were identified by using standard techniques. The determination of mycotoxins (aflatoxins, ochratoxin A, sterigmatocystin, zearalenone, deoxynivalenol and fumonisin B1) was carried out by thin-layer chromatography. The Fusarium spp. was the most dominant fungi (83.8%) followed by Penicillium spp. (55.3%), Aspergillus spp. (40.7%) and 11 other filamentous fungi. All of these were isolated from grains with moisture contents of 12.3-17.8%, an average temperature of 18.4-24.1 degrees C, a relative humidity between 64.0 and 97.5% and rainfall of up to 337 mm. With regard to the number of colony forming units (cfu), Fusarium spp. was the main contaminant, varying from 545 x 10(3) to 1.5 x 10(3). The Simple linear correlation analysis showed significant positive correlation of the Fusarium genus with moisture content of grains, and a significant negative correlation in relation to the minimum and medium temperatures, rainfall and relative humidity. The linear correlation of the Penicillium and Aspergillus genera with the abiotic factors was not significant. In the samples analysed only one contained aflatoxin B1.

Brazil↗

Candidin: comparison of two antigens for cutaneous delayed hypersensitivity testing.

A candidin, which is a suspension of killed yeast cells, is commonly used for intradermal tests of delayed hypersensitivity, to evaluate the immunological cellular competence of the patient, when the test is applied along with other similar tests. When working with a cellular antigen, the histopathology of positive skin tests reveals a cellular infiltrate which not only presents a characteristic hypersensitivity reaction but also a neutrophilic abscess in the central part. This research presents the results of a comparison between the yeast cell suspension and the polysaccharide antigens, both obtained from the same strains of Candida albicans. The results obtained by skin tests in one hundred individuals were 61.0% with the polysaccharide antigen and 69.0% with the yeast cell suspension antigen. Concordant results concerning the two antigens were observed in 82.0% of the individuals. The discussion section presents an assumption to explain the differences of positivity obtained with the two antigens. We conclude that the polysaccharide antigen can be utilized in the intradermal test of delayed hypersensitivity to Candida albicans.

Anti-Bacterial Agents↗

[Fluorescent method (fluorescein diacetate and ethidium bromide) to study the viability of Cryptococcus neoformans in liquor].

The utilization of the fluorescent method (fluorescein diacetate DF and ethidium bromide BE), to verify the viability of fungal cells, was studied in 40 samples of liquor, from patients with neurocryptococcosis. For removing leukocytes and red blood cells, which produce interfering fluorescence, good results were obtained with 0.3% saponin solution. After processing of liquor, 0.1 ml aliquots of resulting suspension were mixed to equal volumes of fresh DF-BE solution. The best incubation period for staining was 30 minutes, resulting in good differentiation between viable (green fluorescence) and non viable (red fluorescence) cells.

Cerebrospinal Fluid↗

Hyaluronidase and chondroitin sulphatase production by different species of Candida.

The production of hyaluronidase and chondroitin sulphatase by Candida albicans, Candida tropicalis, Candida parapsilosis, Candida guilliermondii and Candida krusei was investigated using a complex culture medium (Sabouraud glucose agar) and a chemically defined medium. Among the 63 C. albicans isolates tested, 61 (97.8%) were found to be hyaluronidase and chondroitin sulphatase producers; one isolate produced only chondroitin sulphatase and one other was unable to produce either enzyme. The second major hyaluronidase and chondroitin sulphatase producing species was C. tropicalis followed by C. guilliermondii, C. parapsilosis and C. krusei. Among the C. albicans isolates tested no relation between the source of isolation and the amount of hyaluronidase and chondroitin sulphatase produced was found.

Candida↗

Candidin in immediate hypersensitivity. Comparison of two antigens.

One hundred outpatients in a Clinic of Allergy were submitted to intradermic tests with two types of candidins. The main focus of the research was the comparison of two antigens obtained from the same strains of Candida albicans: one a suspension of yeast cells and the other, a polysaccharide. The readings, taken 20 minutes after the intradermic injections, with positive results were considered as hypersensitivity of the immediate type. Positive results were obtained in 74% of the patients with the yeast cell antigen and in 73% with the polysaccharide antigen. This research mainly deals with the advantages that can be obtained by using the polysaccharide antigen in intradermic tests for evaluating hypersensitivity of the immediate type.

Anti-Bacterial Agents↗

Characterization of allergenic fractions from Drechslera monoceras.

Drechslera monoceras, a fungus of the Deuteromycota phylum, is fairly frequent in Brazil, and is spread through the atmosphere. In previous studies done in the city of Sao Paulo, it was found that in relation to 42 other fungi extracts, the crude extract of this fungi demonstrated a more intense cutaneous reaction in patients with respiratory allergies. Biochemical, antigenic and allergenic evaluations were carried out at various growth stages of this fungus. Based on these facts, the purpose of this research was the fractionation and allergenic characterization of the allergenic extract of D. monoceras to be used in diagnosis and immunotherapy in patients with positive cutaneous reaction to this fungus. In the city of Sao Paulo, 13 of 248 patients with respiratory allergy (asthma and/or rhinitis) showed positive reaction following cutaneous tests (skin prick tests). The crude extract of D. monoceras was fractionated by SDS-PAGE. The visible fractions were then separated by electroelution to be inoculated into BALB/c mice to evaluate the production of IgE antibody. The IgE content was detected by passive cutaneous anaphylaxis test in Wistar rats, and two fractions of approximate molecular weights of 14.4 and 36 KDa reacted to the test. The in vitro allergenic characterization was carried out by Western blotting, and three fractions of approximate molecular weights of 14.4, 36 and 60 KDa were positive. It was concluded that the extract of D. monoceras has at least three allergenic determinants, which can be used for diagnosis and immunotherapy in patients with respiratory allergy to this fungi.

Allergens↗