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Biomedical subjects

S Ramos

Publications and source records attributed to S Ramos.

At least 73 records · Page 4Linked to original sources
PubMed1995

The allograft valve in heart transplantation and valve replacement. Genetic assessment of the origin of the cells by means of deoxyribonucleic acid profiles.

Assessment of the cellular origin of allograft valves is essential in comprehending their biologic behavior and in improving preparation methods. In this study we retrospectively analyzed 10 allografts obtained from patients who underwent valve replacement or heart transplantation. Histologic evaluation and deoxyribonucleic acid amplification by polymerase chain reaction technology with fluorescence labeled primers was performed on different parts of the valve leaflets. Automated analyses of the obtained amplimers showed in the heart transplantation group the presence of receptor cells interspersed with native donor cells in three cases. Preliminary results for the valve replacement group are inconclusive as yet.

Adult↗
PubMed1995

Can the location of the large septal artery be predicted?

The aim of this study is to establish anatomical landmarks for the trajectory of the large septal artery. Thirty hearts were dissected, 20 of which had no cardiac pathology and the remaining with different cardiac conditions. One large septal artery was located in 27 of these hearts, two large septal arteries in 2 and three large septal arteries in 1. For all cases there existed one large septal artery in the lower border of the anterior limb of the septomarginal trabecula. When more than one large septal artery was encountered, the first was located within the subendocardial outflow tract of the left ventricle, the second was in the lower border of the anterior limb of the septomarginal trabecula and the third 1.5 cm below the second.

Adolescent↗
PubMed1995

Activation of murine macrophages by silica particles in vitro is a process independent of silica-induced cell death.

We have tested the murine macrophagic cell line RAW 264.7 for its ability to undergo activation after exposure to silica particles in vitro. When exposed to silica under controlled conditions (each cell having access to about 10 silica particles), RAW 264.7 cells were able to phagocytose the particles. Concomitantly, there was a significant increase in tumor necrosis factor alpha (TNF alpha) mRNA accumulation and TNF alpha secretion. The level of TNF alpha production by RAW 264.7 cells increased up to 5-fold 48 h after phagocytosis of silica particles with very low cell toxicity. The phagocytic stimulus did not induce nitric oxide production. When cells were exposed to a higher number of silica particles, cell activation was attained at shorter times but a substantial number of cells were damaged at 48 h. Interferon gamma (IFN gamma) alone induced an increased production of TNF alpha in RAW 264.7 cells, not further augmented by a subsequent exposure to silica of the IFN gamma-treated cells. Other macrophage-like cell lines as well as primary peritoneal macrophages were able to phagocytose silica particles but showed different abilities to produce and secrete TNF alpha once phagocytosis took place. Therefore, RAW 264.7 cells were chosen as a model for in vitro studies of the long-term response of macrophages to silica.

Animals↗
PubMed1994

Clozapine disposition covaries with CYP1A2 activity determined by a caffeine test.

In a previous study we showed that the disposition of clozapine after a single oral dose is unrelated to either debrisoquine or S-mephenytoin hydroxylation polymorphism. The same 14 healthy subjects studied in that investigation were given 150 mg of caffeine. The reciprocal of plasma clozapine AUC (0,24), was correlated with an index of the N3-demethylation of caffeine (rs = 0.84; P = 0.0024), used as a measure of cytochrome P4501A2 (CYP1A2) activity. N1- and N7-demethylation indices of caffeine also reflect CYP1A2 activity and were also correlated with clozapine clearance (rs = 0.89 and 0.85; P = 0.0013 and 0.0023; respectively). No significant relationships with xanthine oxidase and N-acetyl transferase activity, also assessed by a caffeine test, were found. This study suggests that clozapine is metabolised by CYP1A2 to a major extent.

Administration, Oral↗
PubMed1993

Activation of adenylate cyclase in cdc25 mutants of Saccharomyces cerevisiae.

The activation of adenylate cyclase by guanine nucleotides and 6-deoxyglucose was studied in membrane preparations from S. cerevisiae mutants lacking the CDC25 gene product. Adenylate cyclase from cdc25 ts membranes was activated by GTP and GppNHp in membranes from cells collected after glucose was exhausted from the medium. The activation was also observed in membranes from repressed cells at 2.5 mM Mg2+. It is also shown that 6-deoxyglucose can activate adenylate cyclase in the absence of CDC25 gene product. The relative amount of membrane-bound adenylate cyclase was drastically reduced in cdc25 ts membranes when subjected to the restrictive temperature, while no significant change was observed in the wild type. These data suggest that Cdc25 might not be required in certain conditions for the guanine nucleotide exchange reaction in Ras and that it might be implicated in anchoring the Ras/adenylate cyclase system to the plasma membrane.

Adenylyl Cyclases↗
PubMed1993

Glucose activation of adenylate cyclase in Saccharomyces cerevisiae mutants lacking glucose-phosphorylating enzymes.

The "in vitro" activation by glucose of the RAS-adenylate cyclase system in membranes from a strain of Saccharomyces cerevisiae lacking any functional glucose kinase activity presents similar features to those of the wild type. However, this triple mutant appears to be unable to produce the glucose-induced increase of cAMP levels "in vivo". The results obtained in vitro indicate that the signal transduction mechanism is active in the mutant cells and suggest that the absence of intracellular acidification in vivo might be responsible for the lack of response to glucose.

3-O-Methylglucose↗
PubMed1993

Pathogen-specific risk factors and protective factors for acute diarrheal disease in urban Brazilian infants.

To evaluate potential risk factors and protective factors for acute diarrheal disease in urban infants, 500 infants < or = 12 months old with diarrhea and 500 age-matched control subjects coming to a São Paulo emergency room were studied. On multivariate analysis, these apparently sporadic community-acquired cases of diarrhea were significantly associated with hospitalization in the month before onset (odds ratio [OR], 3.4), day care center exposure (OR, 2.0), prior diarrhea in another household member (OR, 4.4), and low family income (OR, 1.8). Breast-feeding infants < 6 months old (OR, 0.3) and boiling household drinking water (OR, 0.4) were protective. Enteropathogenic Escherichia coli (EPEC; OR, 12.0) and Salmonella (OR, 7/0, discordant pairs) infections were associated with prior hospitalization, rotavirus infections were associated with day care (OR, 6/0), and breast-feeding was protective against EPEC infections (OR, 0.1). These results suggest that certain preventive strategies can prevent a substantial proportion of cases of diarrheal disease in Brazilian infants.

Acute Disease↗
PubMed1993

[Cardiovascular syphilis. Report of 2 cases].

We present two cases of cardiovascular syphilis being one of them a curious case of chronic pericardial effusion associated with cardiovascular complications of lues. In this article we will make as well a review of cardiovascular syphilis.

Adult↗
PubMed1992

[Pulmonary stenosis in adults. Report of a clinical case].

The authors report a case of valvular pulmonary stenosis in a 60 years old patient, admitted to hospital with heart failure and angor pectoris. Four years previously a VVI pacemaker had been implanted for complete heart block. At the time of the admission he had two pacemakers leads in the right ventricle; one of them was retained and functionless since the changing of the generator which occurred 1 year before. The usual complications of endocardial pacemakers are discussed, as well as the natural course and surgery indications for valvular pulmonary stenosis in adults.

Humans↗
PubMed1992

A prospective randomized double blind study of perioperative antibiotic use in the grafting of ulcers of the lower extremity.

We conducted a prospective, randomized, double blind study of the use of a perioperative antibiotic in the skin grafting of arterial and venous ulcers of the lower extremity. Ninety-four patients were randomized and 90 were available for analysis. There was no statistically significant difference in graft "take" or incidence of recipient site infection in the antibiotic versus the no antibiotic group.

Cefazolin↗
PubMed1991

In vitro activation of the Saccharomyces cerevisiae Ras/adenylate cyclase system by glucose and some of its analogues.

Using crude membrane preparations of Saccharomyces cerevisiae, we have demonstrated that glucose and glucose analogues which are not efficiently phosphorylated activate the guanine nucleotide-dependent adenylate cyclase in vitro. The activation appears to be mediated by the Ras proteins. Moreover, data are presented indicating that glucose and its analogues activate adenylate cyclase by stimulating the exchange of guanine nucleotides at its regulatory component. Thus, it has been possible to show the action of a physiological effector on the nucleotide exchange reaction in a member of the ras superfamily.

Adenylyl Cyclases↗
PubMed1991

Medullary carcinoma of thyroid: a re-evaluation of the cytological criteria of diagnosis.

We have reviewed the fine needle aspiration cytology appearances of a series of 31 consecutive and histologically confirmed medullary carcinomas of the thyroid. Despite the absence of a totally specific diagnostic feature, this retrospective re-evaluation indicates that a preoperative diagnosis of medullary carcinoma of the thyroid is possible in almost every case. The features occurring most commonly include a dispersed cell pattern in which round or spindle shaped cells with eccentric speckled nuclei were seen showing slight pleomorphism with inconspicuous nucleoli. In a third of cases fine red granularity was present in the cytoplasm in slides stained with Giemsa and by the Papanicolaou technique.

Adolescent↗