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Biomedical subjects

R G Bevilacqua

Publications and source records attributed to R G Bevilacqua.

At least 19 recordsLinked to original sources
PubMed2001

Abnormal expression of MDM2 in prostate carcinoma.

Mutation of p53 is rare in localized prostate carcinoma. The oncoprotein MDM2, whose gene has a response element for p53, promotes the degradation of p53 protein and inhibits its transcriptional activation of genes related to cell cycle arrest and apoptosis, constituting a negative feedback control. We studied p53 and MDM2 expression by immunohistochemistry and looked for mutations in p53 exons 5 to 8 by polymerase chain reaction-single strand conformational polymorphism in 118 patients submitted to radical prostatectomy for localized prostate cancer. In 28 cases, we studied cell proliferation by immunohistochemistry, using antibody for Ki-67, and apoptosis by the deoxynucleotidyl transferase mediated dUTP biotin nick end labeling technique. Although no p53 mutations were found, p53 protein was detected in 31.4% of the cases, and these cases had higher Gleason scores (P = .03) and more advanced tumor stages (P = .02). MDM2 was overexpressed in 40.7% of the cases, and these cases had greater tumor volumes (P = .001). Tumors that were positive for both p53 and MDM2 were larger (P = .003) and of more advanced stage (P = .03). Within the 28-case subset, the proliferative index was higher among MDM2-positive tumors (P = .046), and the apoptotic index was lower among p53-positive tumors (P = .01). We conclude that, although p53 mutation is a rare event in prostate carcinogenesis, the detection of p53 protein by immunohistochemistry is common and is associated with decreased apoptosis and increased histologic grade and tumor stage. We also conclude that the overexpression of MDM2 has a role in prostate carcinogenesis, being frequently detected and associated with increased cell proliferation and tumor volume. Finally, we propose that the MDM2-positive/p53-positive phenotype identifies prostate cancers with aggressive behavior.

Adenocarcinoma↗
PubMed1999

Prevention of neoplastic port site implants in laparoscopy: an experimental study.

Enthusiasm about the application of videolaparoscopy to oncologic diseases has been limited by the growing number of port site implants. Adult Wistar rats were submitted to 6-7 mm Hg carbonic gas pneumoperitoneum. Rats were randomly divided into two groups: group I rats with tumor (200,000 viable cells of Walker tumor) and group 11 rats with no tumor. The pneumoperitoneum was deflated after 30 min. Group I was further randomized into five groups: no treatment; or abdominal irrigation with saline, heparin, chemotherapy (doxorubicin), or chemotherapy associated with heparin. After a period lasting no more than 18 days, the abdominal wall and intraperitoneal organs macroscopically affected were studied histologically. Chemotherapy groups had no port site implants and were significantly different (p < 0.05) than the no treatment, saline, and heparin solution groups, which had incisional implants at frequencies of 100%, 85.7%, and 82.5%, respectively. Intraperitoneal irrigation with chemotherapy solution was effective in preventing incisional implants in this animal model.

Animals↗
PubMed1998

Hemodynamic and metabolic effects of CO2 pneumoperitoneum in an experimental model of hemorrhagic shock due to retroperitoneal hematoma.

BACKGROUND: Diagnostic laparoscopy has been used in abdominal trauma patients, although its role is not well defined. The safety of laparoscopic evaluation in trauma patients with severe intraabdominal hemorrhage has not yet been analyzed. The purpose of this study is to evaluate the hemodynamic and metabolic effects of CO2 pneumoperitoneum (COI) in hemorrhaged animals through a retroperitoneal hematoma (RH). METHODS: Twenty-two 15-20-kg mongrel dogs were monitored for systemic and pulmonary hemodynamics, inferior vena cava pressure, and arterial blood gases. After 1 h of baseline, all animals were submitted to a RH. After 45 min the dogs were randomized into two groups. Control (CTR): dogs were submitted only to a RH; pneumoperitoneum (PN): dogs were submitted to a RH and 45 min later they were insufflated to an intraabdominal pressure of 10 mmHg with medical-grade CO2 gas for 30 min. Echocardiography was performed, only in PN animals, at baseline, 45 and 60 min after RH. RESULTS: RH induced a shock condition with low, sustained levels of arterial pressure, cardiac index, left ventricular stroke index, base excess, and oxygen delivery which were further depressed following COI. Three deaths occurred in the PN group, all of them toward the end of COI. During COI, hypercapnia was observed in one animal. COI did not impair systolic function or ejection fraction. CONCLUSIONS: COI with an IAP of 10 mmHg may be deleterious in animals with hemorrhagic shock due to an intraabdominal lesion. These findings could be clinically significant in abdominal trauma patients.

Animals↗
PubMed1997

Hyperthermia increases the metastatic potential of murine melanoma.

Hyperthermia, either alone or combined with radio-, immuno- or chemotherapy, can control tumor growth, but its effect on metastasis is still controversial. In the present study, we investigated the influence of hyperthermia on the metastatic potential of B16-F10 murine melanoma cells. Incubation of melanoma cells at 43 degrees C for 30 min led to a significant decrease in cell viability. About half of the cells survived the acute exposure to heat. These thermoresistant cells displayed a longer lag phase as compared to control unheated B16-F10 melanoma cells. Other parameters of cell growth such as doubling time and saturation density were equivalent in both control and thermoresistant cells. Both control and treated cells were adherent, but thermoresistant cells failed to spread during the first 48 h after heat exposure. B16-F10 cells colonize the lungs of C57BL/6J mice when injected intravenously; the number of lung colonies is a measure of the metastatic potential of injected cells. Median values of 22, 10.5 and 31 colonies per injected mouse were observed for control cells, cells heated to 43 degrees C for 30 min and thermoresistant cells, respectively, with statistically significant differences between groups (Mann-Whitney test, P < 0.02). Thus, despite its cytotoxic action, heat exposure induced the acquisition of a more metastatic phenotype in a subpopulation of B16-F10 cells.

Animals↗
PubMed1992

Identification of the external branch of the superior laryngeal nerve during thyroidectomy.

Seventy-six patients underwent preoperative vocal evaluation and were randomized into 3 groups: (1) those with the superior thyroid pole dissected by the first author, with the external branch of the superior laryngeal nerve (EBSLN) identified by means of a nerve stimulator; (2) those patients whose dissection was executed by a resident, with no nerve search; and (3) those whose dissection was undertaken by the first author, without any nerve search. Postoperative analysis consisted of voice evaluation and electromyography of the cricothyroid muscle. No lesion occurred in patients in group 1. Twenty-eight percent of patients in group 2 and 12% in group 3 experienced a complete lesion of the EBSLN (p = 0.0123). When the patients in group 1 were compared with the patients with 62 nerves corresponding to nonoperated thyroid lobes, patients in group 1 exhibited no increased risk, whereas a significantly increased hazard was evident in both groups 2 (p = 0.0002776) and 3 (p = 0.0346393). In this study, effective prevention of iatrogenic EBSLN lesions during thyroidectomies was achieved only by the intraoperative identification of the nerve with the nerve stimulator.

Adult↗
PubMed1991

Prognostic factors in primary retroperitoneal soft-tissue sarcomas.

We analyzed independent treatment variables (age, sex, signs and symptoms, site, size, histopathologic findings, grade, and clinical presentation) and treatment-dependent variables (resectability, type of operation, surgical margins, surgical boundaries, microscopic margins, adjuvant radiotherapy, and adjuvant chemotherapy) in 80 patients with primary retroperitoneal soft-tissue sarcomas admitted from 1982 through 1988. Both univariate and multivariate analysis of survival and disease-free survival were performed. The major factor in survival outcome was the ability to completely resect the lesion. When the 62 patients who underwent complete resection were examined, the only independent prognostic factor for both survival and disease-free survival was grade. We conclude that completeness of resection and grade of the lesion are primary determinants of survival. Once all tumor is macroscopically removed, no advantage could be demonstrated by more extensive surgical resection or current adjuvant therapy.

Adult↗
PubMed1990

Axillary dissection in melanoma. Prognostic variables in node-positive patients.

We evaluated the importance of 14 clinical and pathologic variables as determinants of prognosis in patients with malignant melanoma and positive regional lymph nodes at axillary dissection. The records of 197 patients operated on between 1974 and 1984 were reviewed. Univariate analysis indicated as prognostically significant the number (p less than 0.001) and percentage (p less than 0.001) of positive nodes, highest nodal status (p less than 0.001), macroscopic or microscopic nodal metastases (p = 0.002), presence or absence of extranodal disease (p = 0.003), clinical stage (III versus less than III, p = 0.015), and site (considered as trunk versus other locations, p = 0.02). However, by multivariate analysis, only three variables were shown to be independent determinants of survival: percentage of positive nodes (p = 0.004), presence or absence of extranodal disease (p = 0.012), and site (trunk versus other locations, p = 0.019). Combining these three variables, subsets of patients with markedly different prognoses could be generated. It is possible to predict a favorable outcome for patients with less than 10% positive nodes, no extranodal disease, and a primary lesion at a site other than the trunk. It is also possible to recognize that the prognosis is very poor for patients with extranodal disease and truncal primary lesions, regardless of the percentage of positive lymph nodes. Finally it was verified that the prognosis is always unfavorable when the percentage of positive lymph nodes is very high.

Adult↗
PubMed1985

Effects of protein depletion and repletion on experimental open wound contraction.

A controlled comparative study was conducted on the contraction of open wounds in protein-depleted and depleted-repleted Wistar rats. The wounds were photographed on days 1, 4, 8, 11, 15, 18, and 22 after infliction. The slides were projected and the areas corresponding to the wound were measured by planimetry. The results were analyzed using exponential regressions. Wound contraction was slowed in the protein-depleted animals but was normalized in the animals repleted immediately after the wound was produced. Comparing these results with observations from previous studies, the authors inferred that deficiencies in wound contraction in depleted animals are caused by morphological and functional changes in the granulation tissue. These deficiencies are promptly corrected by protein repletion.

Animals↗
PubMed1984

The effects of protein malnutrition on wound contraction: an experimental study.

The effects of protein malnutrition on wound contraction experimentally produced in Wistar rats were studied. The wounds were photographed on the first, fourth, eighth, eleventh, fifteenth, eighteenth, and twenty-second days. From dressings made from the projection of transparencies the contracted wounds were measured with a planimeter. Open wounds contracted more slowly in the malnourished group. Matching these observations with histopathological findings based on serial observations in these same animals, the differences between the contraction of open wounds in poorly nourished animals and in the control group seem to be associated with delay in the formation and the poor quality of granulation tissue in the malnourished.

Animals↗
PubMed1979

[Effects of choledochal perfusion with biliary acid solutions on activity of the sphincter of Oddi (author's transl)].

The changes of sphincter of Oddi's resistance, induced by choledochal perfusion of conjugated (taurocolic) and non-conjugated (colic) biliary acid solutions, in anesthetized dogs, were studied. The perfusions were made at a constant flow and intracholedochal pressures were registered. The mean number of contractions per minute, the mean maximal pressures and the mean minimal pressures in each study periods were analysed. The choledochal perfusion with the biliary acids solutions induced a slight but significative increase in sphincteric resistance. After 15 minutes, the perfusion with colic acid solution induced maximal pressures significantly more elevated than the ones observed with taurocolic acid solution. The non-conjugated solution induced a pressure tracing significantly distinct from the tracing observed with the conjugated acid solution. No changes in resistance were observed with a 2% NaCl solution. This implies that the observed changes in resistance were not related to osmotic stimulation of the sphincter of Oddi.

Ampulla of Vater↗