Publications by authors named "Marcelo Vinícius Oliveira Vespúcio"

5 Publications

  • Page 1 of 1

Intraosseous schwannoma of mandibular symphysis: case report.

Braz Dent J 2006 ;17(3):255-8

Department of Morphology, Stomatology and Physiology, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.

Schwannoma (neurilemmoma) is a benign neoplasm originated from the neural sheath and occurring most frequently in the head and neck. Intraosseous schwannomas are rare. The mandible is the most common site of occurrence for these lesions. This article reports the case of an intraosseous schwannoma located in the mandibular symphysis of an 11-year-old boy. The lesion was surgically removed and no radiographic evidence of recurrence was observed after 5 years.
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March 2007

[Effects of intrinsic denervation of the jejunum after extensive enterectomy in the rat bowel syndrome].

Acta Cir Bras 2006 Jan-Feb;21(1):43-6. Epub 2006 Feb 13.

Departamento de Patologia, Faculdade de Medicina de Ribeirão, USP.

Purpose: To investigate the effects of intrinsic denervation of the jejunum after the extensive intestinal resection in rats.

Methods: Thirty male Wistar rats were distributed into three groups, depending on the experimental procedure: Group C (control), Group R (resection) and Group D (resection plus denervation). The body weight gain and a histomorphometric study of the jejunal mucosa were performed.

Results: The mean body weight of the group D animals showed a higher increase when compared to group R (D=312.2+/-21 g and R=196.7+/-36.2g). The number of jejunum myenteric neurons was smaller in group D (344.8+/-34.8 neurons/mm) when compared to other groups (R=909.0+/-55.5 and C=898.5+/-73.3). A hyperplasia of the jejunum mucosal epithelium was observed in the group D but also in the group R (R=7.3+/-3.9 mm2 and D=10.8+/-4.3 mm2), when compared to group C (C=5.8+/-3.0 mm2). The epithelial cell proliferation of the jejunum was higher in group D animals (48.7%) when compared to the other groups (R=31.9% and C=23.6%).

Conclusions: The denervated animals presented an increase the body weight gain and mucosal cell proliferation responses when compared to the control group. This experimental model may provide new strategies for the surgical treatment of the short bowel syndrome.
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August 2006

A study of the effects of pinealectomy on intestinal cell proliferation in infant newborn rats.

Acta Cir Bras 2006 Jan-Feb;21(1):16-20. Epub 2006 Feb 13.

University Hospital, FMRP, USP, São Paulo, Brazil.

Purpose: Study the proliferation rate of jejunum and large intestine crypt epithelial cells, in rats pinealectomized immediately after birth.

Methods: Twenty-four male Wistar rats were distributed into two groups: Acute group (n=12) and Chronic group (n=12). Six animals of each group were operated for removal of the pineal gland (pinealectomy-PnX), and other six were controls (sham pinealectomy-C). Animals from acute and chronic group were sacrificed 15 and 90 days after the surgery, respectively.

Results: In acute group, pinealectomy of new-born rats has not caused significant alteration in cell proliferation (PnX=58.77+/-1.77 and C=60.88+/-1.10 in the descending colon/PnX=31.56+/-0.45 and C=31.73+/-0.47 in the proximal jejunum) and in crypt cell population (PnX=24.92+/-4.82 and C=23.60+/-2.48 in the descending colon/PnX=39.92+/-3.49 and C=44.32+/-5.56 in the proximal jejunum). However, in chronic group there was an uprising crypt cell production per crypt in the proximal jejunum (PnX=57.54+/-2.19 and C=47.19+/-7.3)and in the descending colon (PnX=37.78+/-2.22 and C=17.92+/-2.28).

Conclusion: As the increase of intestinal crypts epithelial cells in chronic group is a carcinogenesis predetermining factor, the understanding of the interaction between pineal gland and this event has great importance.
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August 2006

A new experimental model to study preneoplastic lesions in achalasia of the esophagus.

Acta Cir Bras 2005 Nov-Dec;20(6):418-21. Epub 2005 Nov 8.

FMRP, University of São Paulo, Brazil.

Purpose: Develop an experimental model to study esophageal preneoplastic lesions induced by diethylnitrosamine in rats with achalasia.

Methods: Male Wistar rats were divided into four groups: control--C (n=8); rats with megaesophagus--B (n=8); rats treated with DEN--D (n=15) and rats with megaesophagus plus DEN--BD (n=15). Megaesophagus can be experimentally obtained in rats by topical application of benzalkonium chloride. The morphology and PCNA labeling index of the epithelium were evaluated.

Results: The morphometric analysis showed an increase in epithelial thickness in the animals of group BD (2166+/-1012 mm2) when compared to the other groups (C = 878+/-278 mm2; B = 1746+/-144 mm2 and D = 1691+/-697 mm2), mainly due to basal layer hyperplasia, besides an increase in the keratin of the superficial layer. The PCNA labeling index in the basal layer was significantly higher in the group BD (0.695+/-0.111) when compared to the other groups (C = 0.490+/-0.132; B = 0.512+/-0.215 and D = 0.477+/-0.198).

Conclusions: Our data confirm in an experimental model the previous observation in humans of increased epithelial cell proliferation during the esophageal carcinogenic process in achalasia and may be useful to further studies on the mechanisms of the esophageal carcinogenesis and the the design of follow-up endoscopic studies for patients with achalasia.
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July 2006

Hyperplasia of the colonic neuroendocrine cells after pinealectomy in rats. The new evidence for the existence of connections between the distant parts of the diffuse neuroendocrine system.

Neuro Endocrinol Lett 2005 Oct;26(5):511-4

Department of Pathology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil.

Objectives: The diffuse neuroendocrine system (DNES) participates in the systemic homeostasis and may work as a unified system with integrated functions but anatomically disperse. However, the mechanisms that are involved in the integration of the distant parts of the DNES are poorly known. This study is aimed on the effects of a pinealectomy on the population of the neuroendocrine cells (NECs) in the colon of rats.

Methods: A group of seven newborn rats and one of adult rats were submitted to a pinealectomy. The animals were sacrificed after 15 days and 90 days, respectively. The control groups of adult and newborn rats were subjected to a 'sham surgery' and then sacrificed after similar periods of time. Paraffin-included sections of the colon samples were stained by the Churukian-Schenk method in order to selectively stain the NECs. The NEC index was estimated by the expression: iNEC = NECs population per crypt/Total cell population of the crypt. The results were expressed as median and absolute range, and the statistical significance was demonstrated by the Mann-Whitney (U) test.

Results: The morphometric analysis showed a significant increase in the number of colonic NECs of the adult rats subjected to a pinealectomy when compared to the controls. No statistical difference was observed between the iNECs of the newborn groups of rats.

Conclusion: This finding suggests the existence of regulatory mechanisms that integrate distant parts of the DNES, by adapting the population of the endocrine cells after the ablation of an important component of the system. Further studies on the mechanisms involved in the integration of the DNES may be facilitated by the simple experimental model that we propose.
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October 2005