PubMed Health⌕ Search

Biomedical subjects

G C Santos

Publications and source records attributed to G C Santos.

At least 19 recordsLinked to original sources
PubMed2006

Brazilian medical publications: citation patterns for Brazilian-edited and non-Brazilian literature.

Today, the quality of a scientific article depends on the periodical in which it is published and on the number of times the article is cited in the literature. In Brazil, the criteria for the evaluation of this scientific production are improving. However, there is still some resistance, with authors arguing that Brazilian publications must be preferentially addressed to the national readers and, therefore, they should ideally be written in Portuguese. In order to determine the kind of scientific journals cited in the reference lists of articles published in medical periodicals edited in Brazil, in the present study we determine the rate of Portuguese/English citations. Three issues of 43 periodicals (19 indexed in SciELO, 10 in PubMed, 10 in LILACS, and 4 in the ISI-Thompson base) of different medical specialties were analyzed, and the number of both Portuguese and English citations in the reference list of each article was recorded. The results showed that in Brazilian-edited journals the mean number of citations/article was 20.9 +/- 6.9 and the percentage of citations of international non-Brazilian periodicals was 86.0 +/- 11.2%. Of the latter, 94.4 +/- 7.0 are indexed by ISI-Thompson. Therefore, we conclude that Brazilian medical scientists cite the international non-Brazilian periodicals more than the national journals, and most of the cited papers are indexed by ISI-Thompson.

Bibliometrics↗
PubMed2006

Inducing mutations in the mouse genome with the chemical mutagen ethylnitrosourea.

When compared to other model organisms whose genome is sequenced, the number of mutations identified in the mouse appears extremely reduced and this situation seriously hampers our understanding of mammalian gene function(s). Another important consequence of this shortage is that a majority of human genetic diseases still await an animal model. To improve the situation, two strategies are currently used: the first makes use of embryonic stem cells, in which one can induce knockout mutations almost at will; the second consists of a genome-wide random chemical mutagenesis, followed by screening for mutant phenotypes and subsequent identification of the genetic alteration(s). Several projects are now in progress making use of one or the other of these strategies. Here, we report an original effort where we mutagenized BALB/c males, with the mutagen ethylnitrosourea. Offspring of these males were screened for dominant mutations and a three-generation breeding protocol was set to recover recessive mutations. Eleven mutations were identified (one dominant and ten recessives). Three of these mutations are new alleles (Otop1mlh, Foxn1sepe and probably rodador) at loci where mutations have already been reported, while 4 are new and original alleles (carc, eqlb, frqz, and Sacc). This result indicates that the mouse genome, as expected, is far from being saturated with mutations. More mutations would certainly be discovered using more sophisticated phenotyping protocols. Seven of the 11 new mutant alleles induced in our experiment have been localized on the genetic map as a first step towards positional cloning.

Alkylating Agents↗
PubMed2005

Antigen retrieval methods and estrogen receptor immunoexpression using 1D5 antibody: a comparative study.

Long-term formalin tissue fixation results in antigen masking, probably through aldehydic linkage between proteins and fixative molecules. Immunohistochemistry results depend on the type of the detection procedure and the type of antibody used for the reaction. Considering the difficulty in working with estrogen receptor (ER) antibodies and the lack of standardization of the antigen retrieval methods, we quantified the immunoexpression of ER using the 1D5 antibody and a standard streptavidin-biotin detection procedure retrieving with microwave oven, steamer, pressure cooker, and water bath in a set of SBR grade 2 invasive breast carcinomas. Pressure-cooking provided the best results. No significant differences were observed in using the other methods. Pressure-cooking should be recommended as the method of choice for standardization of the ER immunohistochemical reaction.

Antibodies, Monoclonal↗
PubMed2003

Sporothrix schenckii lipid inhibits macrophage phagocytosis: involvement of nitric oxide and tumour necrosis factor-alpha.

The role of cell-wall compounds in the immune response to sporotrichosis is unknown. The effect of cell-wall compounds and exoantigen obtained from Sporothrix schenckii in macrophage/fungus interaction was analysed with respect to nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha). The lipid compound of the cell wall plays an important role in the pathogenesis of this mycosis and was found to inhibit the phagocytic process and to induce high liberation of NO and TNF-alpha in macrophage cultures in the present study. This is a very interesting result because it is the first report about one compound of the fungus S. schenckii that presents this activity.

Animals↗
PubMed2000

Selective inhibitory effects of niflumic acid on 5-HT-induced contraction of the rat isolated stomach fundus.

The effects of niflumic acid (NFA), an inhibitor of calcium-activated chloride currents I(Cl(Ca)), were compared with the actions of the voltage-dependent calcium channel (VDCC) blocker nifedipine on 5-hydroxtryptamine (5-HT)- and acetylcholine (ACh)-induced contractions of the rat isolated fundus. NFA (1 - 30 microM) elicited a concentration-dependent inhibition of contractions induced by 5-HT (10 microM) with a reduction to 15. 5+/-6.0% of the control value at 30 microM. 1 microM nifedipine reduced 5-HT-induced contraction to 15.2+/-4.9% of the control, an effect not greater in the additional presence of 30 microM NFA. In contrast, the contractile response to ACh (10 microM) was not inhibited by NFA in concentrations </=100 microM, although this response was partly inhibited by nifedipine (1 microM) to 67.6+/-11. 8% of the control value. NFA (1 - 30 microM) did not affect contraction induced by either 20 mM or 60 mM KCl, suggesting that this drug was not acting via blockade of VDCCs or activation of potassium channels. In contrast, 3, 5-dichlorophenylamine-2-carboxylic acid and 4, 4'-diisothiocyanatostilbene-2,2'-disulphonic acid were less selective in their inhibitory effects, inducing reductions of 60 mM KCl-induced contraction at concentrations >/=10 microM. Our results show that NFA can exert selective inhibitory effects on the chloride-dependent 5-HT-induced contractions of the rat fundus. The data support the hypothesis that activation of Cl((Ca)) channels leading to calcium entry via VDCCs is a mechanism utilized by 5-HT, but not by ACh, to elicit contraction of the rat fundus.

Acetylcholine↗
PubMed2000

Endocrine cells in the denervated intestine.

This study deals with the effects of myenteric denervation of the proximal jejunum on endocrine cell population of the crypt-villus unit, 5 months after treatment with benzalkonium chloride (BAC). Male Wistar albino rats weighing on average 100 g were allocated to two groups: the BAC group - the proximal jejunal serosa was treated with 2 mM BAC for 30 min, and the control group - treated with saline solution (0,9% NaCl). There was a significant reduction in neurone number in the jejunal myenteric plexus of the BAC group and the endocrine cell population (serotoninergic and argyrophilic cells) was significantly increased in this intestine segment. In conclusion, the present findings provide further evidence that the myenteric denervation induced by BAC may lead to the development of a local imbalance of the neurotransmitters, with a consequent induction of enteroendocrine cell (argyrophilic and serotoninergic cells) hyperplasia in the crypt and villus.

Animals↗
PubMed1999

Fine-needle aspiration cytology and immunocytochemistry of soft-tissue extramedullary plasma-cell neoplasms.

This study presents 19 patients with extramedullary plasma-cell tumors diagnosed by fine-needle aspiration (FNA) cytology together with immunocytochemistry. Eight patients had primary extramedullary plasmacytoma, while 11 patients had tumors secondary to myeloma. The most common localization was soft tissue (9 cases), followed by lymph nodes (5), scalp (3), and oral and nasal mucosa (2). All FNA smears were cellular, and 12 cases showed dissociated monomorphic plasma cells. Seven cases showed a dominance of immature bare nuclei, which made then difficult to diagnose conclusively using cytomorphology only. Immunocytochemistry demonstrated monoclonal expression of light immunoglobulin chains in all cases which, together with demonstration of CD 38 positivity and cytomorphology, allowed a conclusive diagnosis of plasmacytoma.

Adult↗
PubMed1999

Fine needle aspiration of thoracic lesions: experience in a Brazilian cancer center.

STUDY OBJECTIVES: This study is a retrospective analysis of cytological specimens of fine needle aspiration (FNA) of thoracic lesions under computed tomography guidance, over a 2-year period to assess the diagnostic performance of cytology method. DESIGN: A total of 134 aspirations were performed using a 22 and 20 gauge needle (spinal long). The cytological diagnosis was achieved in 126 cases (94%). The histopathological findings were correlationed in order observe the cytologic diagnosis performance. PATIENTS: The cases were obtained from patients examined at A. C. Camargo Hospital ambulatory. RESULTS: There were 89 cases of malignant lesions (66.4%), 27 benign lesions (20%) and 10 cases (7.5%) of suspected for malignancy. The correlation with histopathology was possible in cases with previous histopathological exams and with tissue diagnosis after puncture. The correlation between FNA and histology showed an overall sensitivity of 77%, specificity of 100%, false-negative rate of 20% and no false-positive results. CONCLUSIONS: We conclude that FNA is a sensitive and highly specific technique for the diagnosis of thoracic neoplasms.

Adenocarcinoma↗
PubMed1998

Multivariate survival analysis of 128 cases of oral cavity minor salivary gland carcinomas.

BACKGROUND: Minor salivary gland carcinomas are uncommon tumors of the oral cavity. The decision regarding treatment remains controversial. The main objective of this paper is to report on the survival results of 128 patients treated in a single institution. METHODS: Tumor sites were: hard palate (62 cases), tongue (16 cases), buccal mucosa (13 cases), soft palate (12 cases), and other sites (25 cases). The most common histology was mucoepidermoid carcinoma (76 cases). Clinically metastatic lymph nodes were palpable in 21 patients. Cox regression technique was used to construct the mathematical-statistical models, aiming to predict the risks of recurrence and of death as functions of the different variables under study. RESULTS: The 5-year overall survival rates were, respectively, 85.9% and 87.7% in the groups of patients treated by surgery or combined therapy. There were significant differences in survival rates according to N stage, bone involvement, tumor histology, sex, and type of surgery. CONCLUSIONS: Most of the recurrences were at the site of primary tumor; neck metastases were rare at presentation and after initial treatment. Prognosis involves several factors related to stage, histology, and treatment.

Adolescent↗
PubMed1996

Effect of chronic ethanol consumption on the activities of residual small bowel brush-border enzymes after proximal jejunum resection in the rat.

Ethanol consumption has a toxic effect on the epithelium of the small bowel, but enterocyte maturity is very difficult to measure under these circumstances. However, when ethanol intake is combined with enterectomy, enterocyte immaturity is greater, permitting an easier separation of these two effects. In a group of rats (13 male Wistar rats weighing approximately 220 g) fed a liquid diet containing 35% ethanol for 4 weeks after resection of the proximal jejunum, the residual small intestine brush border maltase, sucrase, and lactase activities were similar to those of a pair-fed control group (13 animals). However, alkaline phosphatase activity was decreased in the mucosa and in the enterocyte brush border, probably because of the lower activity of this enzyme in the jejunum-ileum remnant of the alcoholic group.

Alcoholism↗
PubMed1995

Ileum brush border alkaline phosphatase activity in an experimental model of chronic alcoholism after small bowel proximal resection in the rat.

Literature reports that chronically ingested ethanol induces changes in the morphology of the small bowel mucous membranes. It has a topical toxic effect on the epithelium of the proximal jejunum and a blood-borne effect on the epithelium of the ileum because its absorption is almost complete in the stomach, duodenum and proximal jejunum. In addition there are also reports showing stimulation of enterocyte proliferation after segmental intestine resection. In this report we compare a group of rats submitted to resection of the proximal jejunum and fed a liquid diet containing 35% of the total calories intake as ethanol for four weeks to its control pair-fed group. In both groups we studied the mucosal alkaline phosphatase (APase) activity by histochemical as well as biochemical methods. We found a decreased APase activity in the homogenate of the intestinal mucous membrane in the alcoholic group and a reduced enzymatic activity in the brush border of the ileum enterocytes, as demonstrated by histochemical qualitative and densitometric assays. The result suggests that this change in APase activity of the brush border may represent enterocyte immaturity induced by long-standing ethanol intake in the remnant ileum after proximal resection.

Alcoholism↗
PubMed1993

Myenteric neuron number after acute and chronic denervation of the proximal jejunum induced by benzalkonium chloride.

The effects of benzalkonium chloride (BAC) on the number of myenteric neurons after acute (until 10 days after BAC application) and chronic (30 and 60 days after BAC application) denervation of the proximal jejunum were determined in rats. There was a significant reduction in the number of myenteric neurons of all segments treated with BAC. The extent of denervation varied with time, and it was reduced in the denervated segments of the chronic group in comparison with the acute group. This may be due to the neuroplasticity phenomenon appearing during the chronic phase.

Animals↗
PubMed1992

Accumulation of brown adipose tissue and nutritional status. A prospective study of 366 consecutive autopsies.

Increased amounts of brown adipose tissue have been reported to occur in association with several diseases. The objective of the present study was to determine whether brown adipose tissue accumulation is related to nutritional status. Histologic sections of periadrenal tissue prospectively obtained at consecutive autopsies from 366 adults were examined. The cases were separated into three groups: malnourished (101 autopsies), normotrophic (128 autopsies), and obese (137 autopsies), according to the Quetelet index. Of these patients, 89 had brown adipose tissue accumulation, 35 were malnourished, 32 were normotrophic, and 22 were obese. The results showed a correlation between brown adipose tissue and patient nutritional status and a higher brown adipose tissue accumulation in malnourished patients. Cardiovascular disease was the most common type of illness present in the cases with brown adipose tissue accumulation.

Adipose Tissue, Brown↗
PubMedDate not supplied

Immunocytochemical study of malignant lymphoma in serous effusions.

OBJECTIVE: To cytologically evaluate a large series of serous effusions associated with malignant lymphoma (ML), identify the immunoreaction patterns of the cells from selected positive cases and to investigate the correlation of cytomorphology with tissue section diagnosis. STUDY DESIGN: From 1966 to 1990, a review of the files of the Department of Anatomic Pathology, A. C. Camargo Hospital, disclosed 4,297 cases of serous effusions, 256 of which were associated with ML. Cytopathologically positive cases were selected for immunocytochemical study. All paraffin sections stained with hematoxylin and eosin were reviewed to confirm the malignancy of the cases. Immunostaining was performed on both cytocentrifuge slides previously stained with Papanicolaou stain and new sections of the biopsy samples using the immunoperoxidase method and avidin-biotin complex with monoclonal mouse antihuman B-cell marker L-26 and monoclonal (mouse) antihuman T-cell marker UCHL-1. RESULTS: Immunocytochemical reactions were performed in 54 cases: 22 were pan-B positive and 10 pan-T positive; 24 cases showed no reactivity for either monoclonal antibody. Immunohistochemical reactions were performed in 24 available cases: 15 were pan-B positive and pan-T positive; 3 cases showed no reactivity for either monoclonal antibody. Cytohistoimmunoreactions were similar in 11 pan-B positive cases and 2 pan-T positive cases. Three cases were negative for both markers, 4 cases were pan-T positive in tissue samples and negative in cytocentrifuge smears, 3 cases were pan-B positive in tissue and negative on cytology and 3 cases were negative for both markers in both tissue and cytologic specimens. CONCLUSION: Cytology is an effective method of evaluating serous effusions associated with malignant lymphoma: no false positive diagnosis was observed in this series. Immunophenotyping of lymphoid cells is useful to classify and confirm the cytologic diagnosis.

Animals↗
PubMedDate not supplied

[Colon adenocarcinoma with neuroendocrine and squamous cell differentiation. A case report].

A tubular adenocarcinoma of the colon with solid area composed by small cells that was found by immunohistochemistry study using antibody to neuron-specific enolase (NSE) to possess neuroendocrine differentiation is related. In another areas of the tumor were visualized keratinizing squamous cells. The presence of neuro-endocrine and squamous cells features provide further evidence that neoplastic colonic cells have the capacity for multi-directional differentiation. The implications of this combination in relation to theories of tumor origin and differentiation and the prognostic significance of neuro-endocrine cells in malignant neoplasms of the gastrointestinal tract are discussed.

Adenocarcinoma↗
PubMedDate not supplied

Effect of light curing method on volumetric polymerization shrinkage of resin composites.

Volumetric polymerization shrinkage of three resin composites (Suprafil, Z100 and Filtek P60) was determined using four light curing methods: method 1: continuous output with conventional intensity light; method 2: continuous output with higher intensity light; method 3: ramp output and method 4: pulse-delay output. Five disc-shaped specimens were prepared from each material for each curing method. Specimen weight was determined with an analytical electronic hydrostatic balance in air and in water before and after curing. Specific gravity values were then determined. Volumetric polymerization shrinkage was calculated using mathematical formulas. Mean volumetric polymerization shrinkage ranged from 1.882 (.015)% to 2.169 (.028)%. ANOVA indicated significant differences among the materials (p<.05). Light curing methods had no effect on volumetric polymerization shrinkage except for Z-100, where method 2 resulted in significantly higher shrinkage than methods 1 and 4. Suprafil shrunk significantly less than the other two materials in all curing methods.

Analysis of Variance↗