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Biomedical subjects

A C Castro

Publications and source records attributed to A C Castro.

18 recordsLinked to original sources
PubMed2001

Genetic and phenotypic features of Streptococcus pyogenes strains isolated in Brazil that harbor new emm sequences.

In the present study, 37 group A Streptococcus (GAS) strains belonging to 13 new emm sequence types identified among GAS strains randomly isolated in Brazil were characterized by using phenotypic and genotypic methods. The new types were designated st204, st211, st213, st809, st833, st854, st2904, st2911, st2917, st2926, st3757, st3765, and st6735. All isolates were susceptible to the antimicrobial agents tested, except to tetracycline. They all carried the speB gene, and 94.6% produced detectable SpeB. Most strains belonging to a given emm type had similar or highly related pulsed-field gel electrophoresis profiles that were distinct from profiles of strains of another type. The other characteristics were variable from isolate to isolate, although some associations were consistently found within some emm types. Unlike the other isolates, all type st213 isolates were speA positive and produced SpeA. Strains belonging to st3765 were T6 and opacity factor (OF) negative. Individual isolates within OF-positive emm types were associated with unique sof gene sequence types, while OF-negative isolates were sof negative by PCR. This report provides information on new emm sequence types first detected in GAS isolates from a geographic area not extensively surveyed. Such data can contribute to a better understanding of the local and global dynamics of GAS populations and of the epidemiological aspects of GAS infections occurring in tropical regions.

Antigens, Bacterial↗
PubMed2000

Method to obtain endoscopic esophageal samples for primary cell culture: focus on infectious contamination.

Cell culture techniques hold great importance for the development of molecular biology. However, when used to study oncology, most of the samples come from surgical specimens. Endoscopy is a interesting alternative to get samples for culture. We studied a protocol to allow the control of infectious contamination potentially related to endoscopy, which could preclude it as a method to obtain cells for culture. Esophageal biopsies from 30 patients were taken through upper gastrointestinal endoscopy, using a previously flamed forceps, and were cultivated with and without amphotericin. Our results showed contamination in 3.3% of the wells without the antifungal and in 0.8% of those with it. Regarding the 30 cases studied, the described protocol was able to provide samples free of contamination in all of them.

Biopsy↗
PubMed2000

Molecular cloning, purification and immunological responses of recombinants GroEL and DnaK from Streptococcus pyogenes.

To better understand the roles of heat shock proteins in streptococcal diseases, the groEL and dnaK genes from Streptococcus pyogenes were cloned and their products (GroEL and DnaK) and derivatives (F2GroEL, F3GroEL and C1DnaK) purified as His-tagged fusion proteins. Western blot analysis of the purified proteins with sera from individuals with streptococcal diseases demonstrated that 29 out of 36 sera tested were reactive with GroEL and eight recognized DnaK. Rabbit antiserum against myosin recognized both GroEL and DnaK. Antibodies raised against purified F2GroEL and DnaK reacted with myosin in the ELISA but not in a Western immunoblot. These data indicate that the S. pyogenes GroEL and DnaK may be important immunogens during streptococcal infections. Furthermore, we provide evidence of an immunogenic relatedness of the GroEL and DnaK proteins with myosin that could play a role in the pathogenesis of streptococcal non-suppurative sequelae.

Animals↗
PubMed1998

Very late antigen 4 (VLA4) antagonists as anti-inflammatory agents.

In recent years antagonists of very late antigen-4 (VLA4, also known as integrin alpha(4) beta(1)) have shown great promise in treating inflammatory disorders in a number of animal models. The most advanced in this endeavor is a humanized anti-alpha(4) antibody, Antegren, which is in phase II clinical trials for multiple sclerosis. The first reported small-molecule VLA4 antagonist to advance into clinical trials is currently in phase I as an aerosol for treating asthma. A number of peptides, cyclic peptides and peptidomimetics have been disclosed and are in preliminary stages of development.

Amino Acid Sequence↗
PubMed1998

Genetic relationships among the different phenotypes of Streptococcus dysgalactiae strains.

The species Streptococcus dysgalactiae was proposed to accommodate a heterogeneous group of streptococci associated with infections in animals and human beings. This taxon is now considered to include animal isolates of alpha-haemolytic group C streptococci, previously called S. dysgalactiae; animal and human isolates of beta-haemolytic group C streptococci, previously called 'S. equisimilis'; beta-haemolytic group L strains associated with infections in animals and, rarely, in humans; and beta-haemolytic group G strains isolated from humans. DNA-DNA reassociation experiments (hydroxyapatite method) and multilocus enzyme electrophoresis (MEE) were performed on reference strains and clinical isolates to determine the genetic relationships among these different phenotypic categories. DNA-DNA hybridization tests showed that they were related at the species level, despite the phenotypic and host heterogeneity. Both genotypic and phenotypic characterization indicated that S. dysgalactiae could be separated into two major sub-groups. The first sub-group contained alpha-haemolytic strains that showed levels of DNA relatedness with the type strain of S. dysgalactiae ranging from 84 to 90% and from 82 to 88% under optimal (55 degrees C) and stringent (70 degrees C) conditions, respectively. The second sub-group contained beta-haemolytic strains showing levels of relatedness ranging from 71 to 79% (55 degrees C) and from 62 to 73% (70 degrees C). Percentage divergence varied from 0.5 to 1.0% (alpha-haemolytic group) and from 2.0 to 3.5% (beta-haemolytic group). A dendrogram based on phenotypic similarity between the enzyme bands produced by MEE showed a Jaccard similarity coefficient of 0.45 between the subclusters formed by the two sub-groups. The results of phenotypic and genotypic characterization were consistent with a published proposal to divide S. dysgalactiae into two subspecies, S. dysgalactiae subsp. dysgalactiae and S. dysgalactiae subsp. equisimilis, with a few modifications.

Animals↗
PubMed1998

Expression of heat-shock proteins in Streptococcus pyogenes and their immunoreactivity with sera from patients with streptococcal diseases.

The heat-shock response of Streptococcus pyogenes following exposure to elevated growth temperatures, and the immunological reactivity of heat-shock proteins (HSPs) in streptococcal infections were studied. Two major proteins of 65 and 75 kDa were expressed when a S. pyogenes strain was shifted from 37 degrees C to heat-shock temperatures of 40, 42 and 45 degrees C. Such proteins are members of the GroEL and DnaK families recognised in a Western blot assay with polyclonal antibodies against Escherichia coli GroEL and E. coli DnaK, respectively. Two-dimensional autoradiograms of polypeptides labelled at 37 or 42 degrees C showed an increased intensity of three spots at 42 degrees C. A monoclonal antibody (MAb) against HSP 63 of Bordetella pertussis also recognised the 65-kDa inducible protein, although MAbs against Mycobacterium tuberculosis HSP 65 failed to recognise this protein. Immunoblot analysis of sera from individuals with rheumatic fever or uncomplicated streptococcal diseases revealed seven major immunogenic protein bands, two of which also reacted with anti-E. coli GroEL and DnaK polyclonal antibodies. Furthermore, antibodies to the GroEL and DnaK proteins were also detected in sera from patients with either rheumatoid arthritis or systemic lupus erythematosus. These results demonstrated a heat-shock response of S. pyogenes, and indicated the presence of an immune response against HSPs in streptococcal diseases.

Arthritis, Rheumatoid↗
PubMed1994

Biochemical properties and whole-cell protein profiles of group G streptococci isolated from dogs.

Whole-cell protein profiles obtained by SDS-PAGE were used in conjunction with physiological tests to differentiate strains of Streptococcus canis isolated from dogs. Fermentation of trehalose and lactose, aesculin hydrolysis together with production of beta-D-glucuronidase and alpha-D-galactosidase allowed the demonstration of nine different biotypes. However, visual analysis of the protein patterns and comparison by the coefficient of Dice showed minor differences in band patterns among strains. Only two different profiles were observed. Although a correlation between biotyping and protein profile has been found, this kind of analysis did not provide the basis for a typing method.

Animals↗
PubMed1979

South American blastomycosis of epididymis.

Reported herein is the first Brazilian case of epididymal involvement by South American blastomycosis, and apparently the second case to be reported in the world literature.

Amphotericin B↗
PubMed1971

Reduction of nucleic acid content in Candida yeast cells by bovine pancreatic ribonuclease A treatment.

Yeast as a source of protein for human consumption is limited by its relatively high nucleic acid content. In this study, we developed an enzymatic method of decreasing the nucleic acid content. Candida utilis cells, heat-shocked at 80 C for 30 sec, were treated with bovine pancreatic ribonuclease A. Maximum leakage of nucleic acid was observed when the incubation temperature was between 55 and 65 C, the pH of the system from 6.75 to 8.0, and the enzyme-to-cell ratio 1:10,000 on a weight-by-weight basis. Other factors, such as yeast strain, age of cells, and method of propagation, did not influence the susceptibility of the yeast cells to the action of ribonuclease. Buffers and monovalent cations had no inhibiting effects. Magnesium and calcium ions at concentrations greater than 0.001 m showed marked inhibition on the rate of nucleic acid leakage. This enzymatic method reduced the nucleic acid content of yeast cells from 7.5 to 9.0% to 1.5 to 2.0% with no significant concomitant loss of protein.

Amino Acids↗
PubMedDate not supplied

The effect of subminimal inhibitory concentrations of penicillin on growth rate and haemolysin activity of group G Streptococcus.

The influence of the subminimal inhibitory concentrations (1/3 and 1/4 of the MIC) of penicillin on growth rate and on haemolysin production of a strain of group G Streptococcus was studied. It was shown that 1/3 of the MIC almost completely inhibited the bacterial growth, but it was not able to inhibit haemolysin activity in the culture supernate. The generation time of bacteria grown in 1/4 of the MIC was approximately twice longer than that of the control culture. In all cultures, the haemolysin, after being produced (or liberated), reached a peak and decreased to low levels, which could suggest that group G Streptococcus produces some end products of metabolism that are able to inhibit haemolysin activity.

Hemolysin Proteins↗
PubMedDate not supplied

[Intra-abdominal pulmonary sequestration in an adult: report of an operated case and review of the literature].

A 39-year-old man presenting fever and abdominal pain for three days was operated. He had similar but less severe complaint three weeks before. On admission, his temperature was around 38 degrees C and the abdomen was slightly tender in the left upper quadrant. His blood count showed 24,600 white cells/ml. Urinalysis, serum amylase and blood electrolytes were normal. Abdominal and chest roentgenograms were normal. An ultrasound examination showed an 8.7 x 6.2 cm cystic mass behind the spleen. At surgical intervention, a tumoral mass attached to the left hemidiaphragm, spleen and left adrenal gland was resected. The patient recovered uneventfully. The pathological examination showed pulmonary tissue and the diagnosis was that of an extrathoracic bronchopulmonary sequestration.

Abdomen↗
PubMedDate not supplied

Extragonadal sperm reserves, sperm-depletion rates, numbers of sperm per mating, and fertility with successive matings by intact or unilaterally vasectomized rats.

Because of the high rates of sperm production and large extragonadal sperm reserves of sexually rested male rats, mating trials are insensitive for detecting test-induced alterations in sperm production rates. Mating trials might be more sensitive if, independently of any experimental treatments under study, the number of sperm per mating was closer to the minimum requirements for normal fertility. The present study was undertaken to assess the impact of unilateral vasectomy and/or matings with up to three females in succession, for 1 hour each, on the number of sperm per mating and fertility, in comparison to corresponding values for males allowed unlimited matings with a receptive female overnight. Unilateral vasectomy did not affect sperm production, extragonadal sperm reserves, or removal of contralateral sperm during ejaculation (P > 0.05) but caused a 50% decrease in sperm numbers per mating. Sperm output, judged from numbers of residual extragonadal sperm in unmated and mated males, was excessive (290 x 10[6]) during conventional overnight mating with intact males and during the first and second hours of restricted mating (105 and 184 x 10(6) respectively, for intact males; one-half of these amounts for unilaterally vasectomized males). In contrast, sperm output during the third successive mating was minimal (nonmeasurable) but adequate, since pregnancy rates were similar for females mated first, second, or third in succession (P > 0.05). Since successive matings reduce the number of sperm per mating by natural methods, this approach may enhance the sensitivity of mating tests when applied for assessing the potential effects of experimental treatments on sperm production.

Animals↗
PubMedDate not supplied

Inherent variability among measures of fertility of rats and its implications in the design of mating trials.

Mating trials are used extensively to assess the effects of experimental treatments on the fertility of male or female subjects. Such trials are often insensitive because many measures of fertility are associated with large inherent variability, which makes it difficult to confirm, by statistical significance, that observed differences among treatment means are actually due to treatment rather than due to chance. Unfortunately, and despite this insensitivity, most researchers choose replication arbitrarily on the basis of cost, convenience, or conventional practice and interpret results without assessing the actual power and sensitivity of their experiments. This study was undertaken to characterize the relationship between the number of rats used in fertility trials and experimental power and sensitivity. The variables examined included pregnancy rates, numbers of fetuses per mated or per pregnant female, numbers of fetuses per corpus luteum, and numbers of fetal resorptions. The relationship between replication and experimental power and sensitivity was estimated via statistical approaches utilizing data from Sprague-Dawley rats used in a mating trial at 105-109 days of age. Tabular data are presented showing the numbers of rats needed per treatment group as a function of the minimal treatment differences to be detected and type II error probability selected. The application of these data in the planning of future studies and in interpreting their outcome is discussed.

Animals↗