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Biomedical subjects

Y J Silva

Publications and source records attributed to Y J Silva.

At least 19 recordsLinked to original sources

Optimal revascularization of segmental pancreatic transplant.

Vascular anastomotic thrombosis is one of the most frequent complications after segmental transplantation of the pancreas (STP). We propose a new type of vascular anastomosis to reduce the rate of vascular thrombosis following STP. For this purpose we used double arterial-double venous anastomosis (DADVA). Four different types of vascular anastomosis used for STP were studied and compared. The rate of vascular anastomotic thrombosis was evaluated in correlation with the type of vascular anastomosis used. Traditional vascular anastomosis (TVA) was complicated by vascular thrombosis in 51.9% of cases. DADVA reduced rate of vascular thrombosis to 2.6% (P < 0.01).

Animals↗

Cyclic guanine monophosphate (cGMP) an intracellular mediator of cavernosal smooth muscle relaxation following penile vascular surgery.

BACKGROUND: We describe a new surgical method for treatment of male impotence. This procedure allows preservation of erectile tissues and avoids the need for implantable devices. It was demonstrated, that after this procedure sustained and reproducible erections were feasible. The role of cyclic guanine monophosphate (cGMP) in generation of erection following this procedure was studied. METHODS: Concentration of cGMP in erectile tissues was studied in the chronic canine experimental model. cGMP measurements were obtained using enzymeimmunoassay method. RESULTS: It was detected that the process of erection was accompanied with increased concentration of cGMP in the involved erectile structures (from 39.59 +/- 8.95 and 39.39 +/- 8.54 pm/g to 78.67 +/- 24.05 and 81.62 +/- 18.80 pm/g respectively with p = 0.0001). Concentration of cGMP did not change in the control (from 41.14 +/- 5.38 to 39.26 +/- 7.59 pm/g with p = 0.4568). CONCLUSION: It can be concluded, that proposed new surgical procedure causes erection not by simple distention of erectile tissue sinuses by arterial blood. Arterial blood inflow is accompanied by activation of intracellular mechanisms responsible for smooth muscle relaxation in erectile tissues. Normal values of cGMP concentration in canine erectile tissues are also reported.

Animals↗

Blood flow in the pancreatic segment before and after transplantation.

BACKGROUND: Blood flow in the pancreas before and after transplantation has not been studied sufficiently. Blood flow in the pancreatic transplant as a function of type vascular anastomosis used has not been explored. AIM: The objective of our study was to study blood flow in the intact pancreas prior to harvesting and at different time periods after transplantation. Two different types of vascular anastomosis were used for segmental transplantation of the pancreas. Blood flow in the transplanted pancreas was compared in this two experimental groups. METHODS: Study was conducted on 61 mongrel dogs. Autotransplantation of a pancreatic segment was performed to the left iliac vessels. There were two randomized experimental groups. In the first group (26 animals) traditional vascular anastomosis was used to revascularize pancreatic graft. Proximal end of splenic artery was anastomosed to iliac artery in "end to side" manner. Portal end of splenic vein was anastomosed to iliac vein in "end to side" manner as well. Splenic ends of splenic artery and vein were ligated. In the second group (35 animals) double arterial double venous anastomosis was used. For this purpose, after completing traditional vascular anastomosis, second arterial anastomosis was created distal to the first one between distal end of splenic artery and iliac artery in "end to side" fashion. Second venous anastomosis was performed distal to the first one between splenic end of splenic vein and iliac vein in "end to side" fashion. Blood flow in the pancreatic segment was measured using direct blood flow measurement method and electromagnetic flowmetry. After transplantation of pancreatic segment, blood flow was measured in the pancreatic graft 3 min, 1 h, 1 and 6 months following transplantation. RESULTS: Blood flow in the pancreas before harvesting was 0.69 +/- 0.01 ml/min/g. Blood flow in the pancreatic transplant in traditional vascular anastomosis group was higher than blood flow in the normal pancreas (1.13 +/- 0.05 ml/min/g after one month and 1.00 +/- 0.05 ml/min/g after six months (p < 0.01)). Blood flow in the double arterial double venous anastomosis group was not statistically significantly different from blood flow in the normal pancreas at 1 and 6 months after transplantation (0.70 +/- 0.02 and 0.67 +/- 0.02 ml/min/g accordingly). CONCLUSION: Double arterial double venous anastomosis provided more physiological blood flow to the graft, than traditional vascular anastomosis.

Anastomosis, Surgical↗

Serum levels of interleukin 1 and tumor necrosis factor alpha correlate with peritoneal adhesion grades in humans after major abdominal surgery.

Peritoneal adhesions are a leading cause of potential morbidity and mortality. We undertook this prospective study to determine the clinical relevance of interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) levels as biological markers for peritoneal adhesion formation in humans. Fifteen patients who had previous colectomies and were undergoing re-exploration for an elective vascular procedure were studied. Blood samples were collected from each patient preoperatively and 30 minutes after the abdominal incision was made. Serum levels of IL-1 and TNF-alpha were determined using enzyme-linked immunosorbent assay kits. Adhesions were graded using an adhesion scale of 0 (none), 1 (mild), 2 (moderate), and 3 (extensive, dense). Preoperative levels of IL-1 and TNF-alpha did not differ significantly among all patients (IL-1 level was 60 +/- 14 pg/mL, and TNF-alpha level was 45 +/- 11 pg/mL; mean +/- standard deviation). Significant correlation was observed between grades of adhesions and early intraoperative levels of IL-1 [101 +/- 36 pg/mL for grade 1 (n = 8) vs 298 +/- 73 pg/mL for grade 3 (n = 6); P < 0.01] and TNF-alpha (88 +/- 23 pg/mL for grade 1 vs 261 +/- 88 mL for grade 3; P < 0.02). We conclude that early elevations of IL-1 and TNF-alpha are reliable biological markers for postoperative adhesions in humans. Studies utilizing cytokines antibodies to these markers may further elucidate the efficacy of this method for prevention of peritoneal adhesions.

Abdomen↗

Gastrosplenic fistulas: a case report and review of the literature.

A case is presented of a patient who developed a gastrosplenic fistula during a course of chemotherapy for differentiated histiocytic lymphoma. The fistula was observed during upper gastrointestinal endoscopy (gastroscopy) and confirmed by CT scan with contrast. The fistula was followed endoscopically and noted to have closed spontaneously with confirmed closure at laparotomy. The clinical management of this complication is discussed, and the literature pertaining to this rare condition is reviewed.

Antineoplastic Combined Chemotherapy Protocols↗

Effects of interleukin-6 and its neutralizing antibodies on peritoneal adhesion formation and wound healing.

This study investigates the effects of preoperative IV administration of IL-6 and anti IL-6 on peritoneal adhesion formation and wound healing. Thirty-six male Sprague-Dawley rats (350-400 mg) were divided into three groups: control (group 1); IL-6 (group 2); and anti IL-6 (group 3). Under sterile conditions, all rats underwent a midline laparotomy. Ten cm2 of cecal serosa was abraded, the cecum further irritated with 0.1 ml of 70 per cent alcohol, and the incision closed in layers. At 3 weeks, peritoneal adhesions were graded using a score of 0 (none) to 3 (extensive, dense). Skin samples from incisional sites were examined tensiometrically (true stress and true strain), biochemically (collagen content), and histologically. Adhesion formation score was significantly increased in IL-6 group (2.78 +/- 0.44, Mean +/- SD) and decreased in anti IL-6 group (1.40 +/- 0.52) compared to control (2.00 +/- 0.50). (P < 0.03 by Kruskal Wallis test). There was no significant difference in true stress, true strain, and collagen content between the two treatment groups and controls at the 0.05 level by ANOVA. Histological analysis showed higher number of inflammatory cells and fibroblasts in IL-6 treated groups. We conclude that IL-6 plays a major role in peritoneal adhesion formation. Selective immunosuppression, using IL-6 neutralizing antibodies preoperatively, leads to a reduction of such adhesion formation without a significant effect on wound healing.

Abdomen↗

Preoperative administration of antibodies against tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) and their impact on peritoneal adhesion formation.

This study investigates the effects of preoperative intravenous administration of antibodies against TNF-alpha and IL-1 on peritoneal adhesion formation. Fifty-six Sprague-Dawley rats (350-400 gm) were used in this study. Eight rats were used to empirically determine the amount of anti TNF-alpha and anti IL-1 needed for complete in vivo neutralization. This amount was used for preoperative treatment of selected groups. Forty-eight rats were divided into four equal groups (n = 12). All rats underwent a midline laparotomy. Ten cm square of cecal serosa was abraded, the peritoneal cavity was irrigated with normal saline, and the incision was closed in layers. Cultures were obtained intraoperatively and rats with positive cultures were excluded. Rats in Group 1 were not treated (control), while rats in Groups 2, 3, and 4 were treated with anti TNF-alpha, anti IL-1, and a combination of anti TNF-alpha and IL-1 respectively. All rats were killed at 3 weeks, and peritoneal adhesions were graded using a scale of 0 (none) to 3 (extensive, dense). Rats treated with anti IL-1 (Group 3) and those treated with a combination of anti TNF-alpha and anti IL-1 (Group 4) had significantly fewer adhesions when compared with Group 1 (control) (P < 0.01 and < 0.005, respectively). Least adhesion formation was associated with Group 4 rats. In conclusion, selective immunosuppression, at a molecular level, appears to have a significant impact on rates of postoperative peritoneal adhesion formation.

Animals↗

Hemostasis and healing of superficial splenic injuries using Nd:YAG laser and nonsuture techniques: preliminary report.

This study was designed to compare Nd:YAG laser to fibrin glue, electrocautery, and avitene in the management of superficial splenic injury. Six dogs were submitted to laparotomy. A #11 blade scalpel was used to sharply excise the splenic capsule inflicting four 1" x 1" superficial injuries on each spleen. The lesions were treated. All animals had a second laparotomy ("first relaparotomy"); 2 dogs each were reexplored on postop days 3, 7, and 14. Morphologic and histologic observations were made. A third and final relaparotomy was performed on all dogs at 21 days with repeated morphologic and histologic assessments. Hemostatic times, grades of adhesions, and microscopic changes were not significantly different among the various treatments (P > 0.25). Capsular plaque formations were significantly different at the first relaparotomy (P < 0.01) and at final relaparotomy (P < 0.05). Both adhesions and capsular plaque formation were least at fibrin glue-treated sites, whereas Nd:YAG (1.06 microns) was most effective for average hemostatic time (mean = 109.67 s). Electrocautery produced the greatest necrosis at treatment sites. We conclude that all modalities are effective in controlling hemorrhage.

Animals↗

Pancreatic pseudocyst: a consequence of tandem laparoscopic cholecystectomy and endoscopic sphincterotomy.

Laparoscopic cholecystectomy has been considered the "gateway to the future" of surgery (1). Since its advent, laparoscopic surgery has emerged as a distinct surgical endeavor. Laparoscopic cholecystectomy offers several advantages over the open technique, including physical, economic, and cosmetic advantages. However, this new technique also has the potential for serious complications that could be incapacitating and indeed life threatening. We report a pancreatic pseudocyst after laparoscopic cholecystectomy and endoscopic sphincterotomy for removal of common bile duct stones.

Adult↗

Clinical significance of umbilicoportal manometry.

Ninety-six adult patients had measurements of portal pressur over 1 to 5 days via indwelling extraperitoneal umbilicoportal catheters. Liver biopsy specimens obtained during catheterization showed 50 patients to have a normal liver; the remainder had liver disease. Portal pressure averaged 16.08 +/- 2.87 (SED) cm of saline in normal patients. Ten patients, 6 with cirrhotic and 4 with normal livers, were recatheterized 1.5 days to 7 months later when they came to laparotomy. In all but one, portal pressures were decreased during anesthesia and laparotomy. Twenty additional patients undergoing cholecystectomy had portal pressures measured before and after laparotomy, and after recovery from anesthesia for 1 to 3 postoperative days. Laparotomy caused a decrease in portal pressure of 2.7 +/- 1.3 (SED) cm of saline; after recovery from anesthesia portal pressure was higher by 2.5 +/- 1.7 (SED) cm of saline. Umbilicoportal catheterization is a safe and accurate technique for studying the portal system. In the intact unanesthetized state, we consider 22 cm of saline to be the upper limit of normal for portal pressure.

Adolescent↗

In vivo use of human umbilical vessels and the ductus venosus arantii.

Clinical use of umbilical vessels in the neonate is commonplace. In the adult, surgical reopening of the umbilical vein is feasible in the majority of patients, providing direct access to the portal circulation. Umbilical vein catheterization allows for portal manometry in the intact, unanesthetized state. Prolonged catheterization has served to facilitate physiologic and pharmacologic studies hitherto unavailable. Selective splanchnic catheterization with hepatoportography permits roentgenographic studies, important in the evaluation of patients with hepatobiliary diseases. Clinically, the umbilical vein has been used in the study of portal hemodynamics, portal decompression and hemofiltration, portal arterialization and in evaluating hepatic trauma. This method of access to the portal circulation has provided a route for study of the effects of drugs, hormones and other biologic materials on the portal circulation and for administration of antibiotics and other chemotherapeutic agents into the portal system. The procedure of umbilical vein catheterization is simple and repeated catheterization is possible. The ductus venosus, on the other hand, is not clinically usable and pertinent information has been reviewed. The ex vivo use of neonatal umbilical veins as vascular conduits is not included in this review.

Adolescent↗

Exchange transfusion and major surgery in acute hepatic failure.

Of the many techniques available for short-term support of the failing liver, a closed "isovolemic" method of exchange transfusions remains simple and safe. We used this method to exchange 143 U. of blood in eight patients in Stage III/IV hepatic failure; four patients had no previous underlying liver disease. Significant improvements of biochemical and coagulation parameters resulted. Serum bilirubin, glutamic oxaloacetic transaminase and, lactic dehydrogenase levels fell from a mean, 24.7 mg. per 100 ml., 3,100 mU. per milliliter, 2,796 mU. per millilter, respectively, to 10.9 mg. per 100 ml., 122.9 mU. per milliliter, and 558.5 mU. per milliliter, respectively, 6 to 12 hours following transfusion. Prolongation of serum prothrombin and thrombin times (over controls) of 31.1 and 30.1 seconds (mean) were markedly decreased to 3.2 and 6.1 seconds 6 to 12 hours following transfusion; partial thromboplastin times were decreased from a mean 196.4 seconds to 87.8 seconds after the same period. Levels of Factors VII, IX, and X were increased transiently. Correlations of exchange transfusion to reversal of coma and improvements in electroencephalograms were poor. Two patients in coma were subjected to major surgery following exchange transfusion; one patient survived vagotomy and hemigastrectomy for stress bleeding and one withstood a temporary baboon liver heterotopic transplant which aided in recovery from coma. We recommend isovolemic exchange transfusion as specific treatment for coagulation abnormalities and as an over-all aid in lowering the mortality rate of patients in hepatic coma. Marked improvements in homeostasis make major surgery feasible.

Adolescent↗