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Biomedical subjects

T N Pappas

Publications and source records attributed to T N Pappas.

At least 91 records · Page 5Linked to original sources
PubMed1992

The technique of laparoscopic cholecystectomy in children.

Twelve children underwent elective laparoscopic cholecystectomy for symptomatic cholelithiasis during a 10-month period in one institution. The operative technique that has been described for adults was modified because of the smaller dimensions of pediatric patients. These modifications are discussed in this report, as are new alternatives for evaluating the common duct. No operative complications or conversions to open cholecystectomy occurred, and no complications after surgery were seen during an average follow-up period of 4.5 months. The benefits of laparoscopic cholecystectomy include decreased pain and ileus after surgery, shortened hospitalization, and improved cosmesis. Laparoscopic cholecystectomy is safe and efficacious in children, and it compares favorably with traditional cholecystectomy in the pediatric age group.

Adolescent↗
PubMed1992

Mechanisms of major biliary injury during laparoscopic cholecystectomy.

Laparoscopic cholecystectomy has become the procedure of choice for surgical removal of the gallbladder. The most significant complication of this new technique is injury to the bile duct. Twelve cases of bile duct injury during laparoscopic cholecystectomy were reviewed. Eight injuries were of a classic type: misidentification of the common duct for the cystic duct, resection of part of the common and hepatic ducts, and associated right hepatic arterial injury. Another injury was similar: clip ligation of the distal common duct with proximal ligation and division of the cystic duct, resulting in biliary obstruction and leakage. Three complications arose from excessive use of cautery or laser in the region of the common duct, resulting in biliary strictures. Evaluation of persistent diffuse abdominal pain led to the recognition of ductal injury in most patients. Ultimately, 10 patients required a Roux-en-Y hepaticojejunostomy to provide adequate biliary drainage. One patient had a successful direct common duct repair, and the remaining patient underwent endoscopic dilatation.

Adult↗
PubMed1992

Intracerebroventricular neuropeptide Y stimulates bile secretion via a vagal mechanism.

UNLABELLED: The effect of intracerebroventricular injection of neuropeptide Y on biliary secretion was studied in conscious dogs, prepared with gastric and duodenal fistulas and cerebroventricular guides. Bile secretion was increased in a dose-dependent fashion by intracerebroventricular neuropeptide Y. The peak increase was seen after 500 pM/kg of neuropeptide Y which resulted in a 30 x 2% increase in bile flow over the period 30-150 minutes after injection. ( CONTROL: 23 x 2 (1 x 2) ml/2 hours; neuropeptide Y 500 pM/kg: 30 x 5 (1 x 1) ml/2 hours). Biliary lipid composition was not altered significantly but bicarbonate output was increased at all doses tested. Intravenous infusion of neuropeptide Y (1000 pM) for 1 hour had no significant effect. Intracerebroventricular neuropeptide Y (1000 pM/250-300 mg body weight) also increased bile flow in urethane-anaesthetised rats. This effect was abolished by cervical vagotomy. The demonstration of a central stimulation of alkaline bile flow suggests that bile secretion may be subject to central modulation.

Animals↗
PubMed1992

Malignant biliary obstruction: efficacy of thin-section dynamic CT in determining resectability.

OBJECTIVE: Several authorities advocate the use of preoperative angiography to determine the resectability of pancreatic and periampullary tumors, claiming that CT alone is not sufficiently accurate for this purpose. Our objective was to assess the value of CT in predicting surgical resectability in patients with malignant biliary obstruction. MATERIALS AND METHODS: We performed a retrospective analysis of 380 consecutive cases of malignant biliary obstruction spanning a 4-year period. Most patients (230) were treated nonoperatively. Sixty-seven patients had surgery, pathologic confirmation of malignancy, and preoperative CT scans available for review. The CT scans were assessed for surgical resectability of tumor by an interpreter who did not know the patient's history. RESULTS: Forty-two patients had pancreatic adenocarcinoma, six had ampullary carcinoma, seven had cholangiocarcinoma, and 12 had other malignant neoplasms. Of 47 patients with tumors thought to be unresectable on the basis of CT findings, 42 had tumors that were found to be unresectable at surgery (positive predictive value, 89%). Of 20 patients with tumors thought to be resectable, 16 had tumors that were surgically resectable (positive predictive value, 80%). CT did not show metastases to duodenal lymph nodes (n = 2), portal vein infiltration (n = 1), and small hepatic metastases (n = 1). Visualization of most of these at angiography would not be expected. The CT finding of infiltration of the periarterial fat around the celiac or superior mesenteric arteries was reliable for predicting surgical unresectability. Lymphadenopathy and infiltration of nonperivascular fat planes were less reliable predictors of unresectability. CONCLUSION: Although some findings on CT that suggest unresectability are less reliable than others, the accuracy of CT compares favorably with reports on the accuracy of angiography for assessing tumor resectability in cases of malignant biliary obstruction. The addition of angiography to the examination of patients with potentially resectable lesions is not justified when high-quality, thin-section dynamic CT has been performed.

Adenocarcinoma↗
PubMed1991

Intraoperative use of a 2-mm choledochoscope for the exploration of small bile ducts and the pancreatic duct.

Intraoperative visualization of the biliary and pancreatic ducts can be difficult in a nondilated system. Very small extra- and intrahepatic bile ducts occasionally require visualization but do not admit the traditional 6.5-mm intraoperative flexible choledochoscope. We have prospectively examined the use of a 2-mm choledochoscope for the intraoperative evaluation of the biliary and pancreatic ducts in 36 patients. In 27 patients, the choledochoscope was advanced through the cystic duct stump for examination of the common bile duct following cholangiography. The scope was successfully passed into the cystic duct stump and into the common bile duct in 76 per cent of patients. Inability to pass the scope through the cystic duct was usually due to acute angulation of the cystic duct/common duct junction. In an additional five patients, intraoperative cholangiography revealed a filling defect in a very small duct. A choledochotomy was made and the 2-mm choledochoscope was used to exclude the presence of stones in a small bile duct. In four patients the choledochoscope was used during a Puestow procedure to visualize and help extract stones in the tail and head of the gland. No complications occurred in these patients due to the use of the choledochoscope. We conclude that the 2-mm choledochoscope aids in internal visualization of small intra- and extrahepatic bile ducts and the pancreatic duct. It may be useful as an adjunct to cholangiography in determining the nature of filling defects.

Bile Duct Diseases↗
PubMed1990

Primary hypertrophic pyloric stenosis in the adult.

Analysis of 100 consecutive patients with pyloric outlet obstruction revealed that 37% of the obstructions were secondary to peptic ulcer disease and 42% were caused by malignant neoplasm. Only a single patient with primary hypertrophic pyloric stenosis was identified, and whether this lesion is a cause or effect of peptic ulcer disease remains unclear. Similarly, the association of this entity with congenital pyloric stenosis is unknown.

Adult↗
PubMed1990

The effect of taste on gastric and pancreatic responses in dogs.

Six mongrel dogs with gastric and esophageal fistulas (n = 4) or with gastric and pancreatic fistulas (n = 2) were studied to determine the role of taste on gastric and pancreatic secretion. Stimulation of the back of the throat with a range of tastants produced gastric acid, bicarbonate, protein, and pancreatic polypeptide levels that were statistically equivalent to those produced with stimulation of the entire tongue. This suggests that the vagus nerve is the primary mediator of the cephalic phase response to tastants. There were marked individual differences among dogs in the responses to the ten tastants that were tested. On average, monosodium glutamate and seltzer, which mongrel dogs do not normally encounter in their diets, produced lower gastric acid secretion and pancreatic polypeptide release than sweet, sour, salty, bitter, and meaty tastes. The gastric acid secreted by the dogs with esophageal fistulas in response to tastes was only one-half as large as levels previously reported for sight/smell of food and only one sixth as large as those obtained with sham feeding.

Animals↗
PubMed1990

Geranyl-geranyl acetone: a novel stimulant of secretin release in the dog.

Geranyl-geranyl acetone (GGA), a new acyclic polyisoprenoid, anti-ulcer drug appears to exert its beneficial effect by stimulating bicarbonate secretion from the stomach and pancreas. Its efficacy in stimulating pancreatic bicarbonate is particularly striking, and this study was designed to examine the mechanism for this action. Since it is structurally similar to the side chain of the prostaglandin molecule, its ability to stimulate bicarbonate secretion could be a direct one. On the other hand, the magnitude of pancreatic bicarbonate response (about 50% of maximal response to secretin) suggests it might act by releasing secretin. Two types of experiments were performed in dogs with pancreatic fistulas: first, secretagogue interactions were examined by studying the effect of intraduodenal GGA (8 mg/kg) or its carrier (control) on the dose-response curves to exogenous secretin and cholecystokinin octapeptide (CCK-8); second, the effect of graded doses of intraduodenal GGA on pancreatic bicarbonate and plasma secretin-like immunoreactivity (SLI) responses was tested directly. Pancreatic bicarbonate responses (micromoles per 30 min) were to secretin doses of 32, 125, and 500 ng/kg/h. Without and with GGA, responses were 74 +/- 27, 952 +/- 215, and 2,000 +/- 425 and 599 +/- 110, 1,624 +/- 472, and 2,129 +/- 398 ng/kg/h, respectively. Similarly, the bicarbonate responses to CCK-8 were augmented. Basal plasma SLI was 1.5 +/- 0.6 pM/ml. Peak plasma SLI in response to 2, 4, and 8 mg of GGA intraduodenally were 6.8 +/- 0.7, 8.9 +/- 3.1, and 19.6 +/- 2.7 pM/ml, respectively. It is concluded that GGA is a potent stimulant of pancreatic bicarbonate secretion, and this action appears to be mediated by the release of duodenal secretin.

Animals↗
PubMed1990

100 consecutive common duct explorations without mortality.

It has been suggested that the incidence of morbidity and mortality after common duct exploration no longer justifies its use in patients with a gallbladder in situ. Therefore endoscopic sphincterotomy has been advocated for removal of common duct stones before cholecystectomy in selected patients. The purpose of this study was to determine our current rate of retained common duct stones and the morbidity and mortality rates associated with common duct exploration. Charts of 100 consecutive patients who underwent cholecystectomy and common duct exploration from January 1982 through December 1986 were reviewed. Indications for duct exploration included jaundice, dilated common bile duct, gallstone pancreatitis, multiple small stones, and abnormal intraoperative cholangiogram. Common duct exploration was done by manual technique or choledochoscopy, as determined by the surgeon's preference. Only two patients required duodenotomy for extraction of difficult stones. There were no deaths in this series of consecutive common duct exploration. The total morbidity rate was 15.7%, which included a 5.3% incidence of retained common duct stones. There was a 7.4% major complication rate, including deep vein thrombosis, bleeding gastric ulcer, and pneumonia. The remaining complications were minor and did not prolong hospitalization. There was one wound infection and no postoperative pancreatitis. None of the complications were directly attributable to choledochotomy or duct exploration. All retained common duct stones were removed by endoscopic retrograde cholangiopancreatography or by angiographic basket and did not require reoperation. It is concluded that operative common duct exploration not requiring duodenotomy is safe and does not appreciably increase the incidence of complications after cholecystectomy. Endoscopic sphincterotomy continues to be the preferable alternative to operative common duct exploration for patients with retained common duct stones.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1989

Gastric distension is a physiologic satiety signal in the dog.

Gastric distension is thought to produce satiety, but whether this effect is seen during physiologic distension by food is unknown. The purpose of this study was to determine whether levels of gastric distension seen during a meal have a satiety effect and whether the nutrient value of the meal was important. Four dogs were prepared with gastric, duodenal, and esophageal fistulas. Physiologic distension was determined by allowing the animals to eat liquid nutrient diet until sated and measuring the volume consumed and the time it took to consume it (means 2000 ml in 4 min). To test the effect of gastric distension on satiety, distension was produced during sham feeding by infusions of either liquid nutrient, inert liquid (Karaya), or by a water-filled balloon. Lower degrees of distension were also tested to determine if a dose-response relationship existed. Balloon, inert, and nutrient distension all inhibited sham feeding dose-dependently. Peak inhibitions of sham feeding caused by physiologic gastric distension (balloon, inert, nutrient) were 69 +/- 5%, 67 +/- 12%, and 61 +/- 6%, respectively. In all cases, maximal distension terminated sham feeding before the end of the feeding period. The effect of gastric distension on feeding was not blocked by pretreatment with atropine (50 micrograms/kg). Thus, graded degrees of gastric distension, comparable to those seen during ingestion of a normal meal, produced graded inhibition of food intake by a noncholinergic mechanism and independent of the nutrient properties of the food.

Animal Nutritional Physiological Phenomena↗
PubMed1989

Characterization of in vivo acid secretory responses of rabbit with comparison to dog and rat.

Even though rabbit gastric glands are a commonly used model for the study of gastric physiology, little is known about the secretion of gastric acid in the rabbit in vivo. Gastric acid secretion in response to pentagastrin, histamine, and bethanechol stimulation, and the effect of specific cholinergic and histamine H2-receptor blockers was studied in 62 urethane-anesthetized rabbits. Additionally, the responses of eight conscious rabbits prepared with chronic gastric fistula were compared with similarly prepared conscious dogs (n = 10) and conscious rats (n = 18). In anesthetized rabbits, maximal pentagastrin stimulation resulted in acid outputs only 22% that of maximal histamine stimulation, but this was enhanced by restoring cholinergic tone with a subthreshold infusion of bethanechol. In conscious rabbits, pentagastrin was an effective stimulant, resulting in maximal acid output 70% that of maximal histamine stimulation. This is in contrast to the in vitro findings reported reported by others utilizing isolated gastric glands and cells. Histamine was a potent stimulant of acid secretion in both the anesthetized and conscious rabbit, an observation that parallels the in vitro findings. Unlike the dog and rat, atropine was ineffective as an inhibitor of histamine-stimulated acid secretion in the conscious rabbit, although it was marginally effective against histamine in anesthetized rabbits and against pentagastrin in conscious rabbits. It is concluded that cholinergic tone plays a crucial role in pentagastrin-stimulated acid secretion in the rabbit. This may be an explanation for the poor response to pentagastrin described in isolated rabbit gastric gland preparations.

Animals↗
PubMed1989

Physiologic approaches to the control of obesity.

Morbid obesity is a major health problem in this country and throughout the world. In addition to its social stigma (in the western world), obesity exacerbates several disease states such as diabetes, hypertension, cardiac disease and restrictive lung disease. When effective medical treatment of obesity becomes available, it will depend in part upon understanding the physiologic factors that control satiety. This review summarizes the information available on brain and gut control mechanisms of satiety. Brain nuclei located in the lateral hypothalamus, ventromedial hypothalamus, and other paraventricular areas are the sites of action for potent neuropeptides, such as cholecystokinin (CCK) and neuropeptide Y, that appear to regulate feeding. Exogenous CCK has been used clinically to decrease meal size in obese patients. The sites of the satiety cascade that are most often manipulated are the gastric and intestinal phases. Physiologic gastric distension is a potent inhibitor of feeding, whereas the intermeal interval may be regulated by intestinal signals released by food in the gut. Jejunal-ileal bypass has fallen from favor and has been replaced by gastric restrictive procedures that create a small proximal gastric pouch that empties into the small bowel (gastric bypass) or the distal stomach (gastroplasty). These operations rely partially on their ability to produce gastric distension in the proximal gastric pouch at an early stage during a meal. Thus, failure results if the pouch compensates by distending or if the stoma widens with subsequent loss of slow emptying. Improved medical and surgical treatment will be designed to intervene at specific sites of the satiety cascade as knowledge of the physiologic control mechanisms of satiety increases.

Bombesin↗
PubMed1988

Postprandial neurohormonal control of gastric emptying.

The delay in gastric emptying after a meal is thought to result from nutrient distention-induced release of peptides and neurotransmitters in the gut. The potential contribution of the brain and central neuropeptides to the postprandial regulation of gastric emptying has not been studied adequately. The purpose of this study was twofold: to examine the relative importance and pure central stimulation (sham feeding) or pure peripheral stimulation (duodenal feeding) on gastric emptying, and to determine whether relevant neuropeptides act in the brain to slow gastric emptying of a meal. Six mongrel dogs were prepared with esophageal fistulas, gastric fistulas, duodenal fistulas, and chronic lateral cerebroventricular guides. Gastric emptying of a 300 ml saline solution meal was measured by a phenol red dye dilution technique. Sham feeding of a blenderized meal through the esophageal fistula was used as a central cephalic stimulus. Intraduodenal oleic acid was used as a peripheral stimulus. Both sham feeding and intraduodenal oleic acid inhibited gastric emptying by 59 +/- 12 percent, 73 +/- 5 percent, respectively. In separate studies, we examined the effect on gastric emptying of a bolus injection into the lateral cerebral ventricle of graded doses of corticotropin-releasing factor (110 to 440 pmol/kg), cholecystokinin (16 to 128 pmol/kg), somatostatin-14 (55 pmol/kg), human calcitonin gene-related peptide (230 pmol/kg), and neuropeptide Y (62 to 250 pmol/kg). These peptides are known to affect satiety, gastric emptying, and gastric acid secretion. Of these, only neuropeptide Y and cholecystokinin had an effect on gastric emptying when administered into the lateral cerebral ventricle. Neuropeptide Y inhibited emptying by 28 +/- 8 percent and cholecystokinin accelerated emptying by 32 +/- 12 percent (p less than 0.05). Sham feeding inhibits gastric emptying to a similar degree as intraduodenal feeding, and of the neuropeptides tested, only neuropeptide Y inhibited gastric emptying when given into the brain. The central release of neuropeptides such as neuropeptide Y during a meal may trigger neural pathways that promote postprandial delay in gastric emptying. Central signals may be as important as peripheral signals in the postprandial control of gastric emptying. Further studies are needed to determine the mechanism by which sham feeding inhibits gastric emptying and whether central release of neuropeptide Y is involved.

Animals↗
PubMed1988

The effect of somatostatin on experimental intestinal obstruction.

The effect of somatostatin (SS-14) was tested in an anesthetized rabbit model of closed-loop ileal obstruction. Experimental groups included (1) immediate treatment (N = 6) receiving SS-14 2,000 pmol X kg-1 X h-1 intravenously (I.V.) beginning at the time of ileal obstruction, (2) delayed treatment (N = 5) receiving SS-14 beginning 6 hours following ileal obstruction, and (3) control (N = 6) receiving only hydration. After 24 hours, all rabbits were killed. Significantly decreased intestinal luminal volume and sodium and potassium output was observed with both immediate and delayed SS-14 treatment when compared to control. Additionally, the gross and microscopic pathologic features of intestinal distension, inflammation, and necrosis seen in control rabbits were absent in rabbits treated with SS-14. The known broad spectrum of physiologic activity of SS-14 on the gastrointestinal tract appeared beneficial in this rabbit model of intestinal obstruction.

Animals↗
PubMed1988

Surgical therapy of localized abdominal non-Hodgkin's lymphomas.

Non-Hodgkin's lymphomas may involve a variety of abdominal organs, including the liver, spleen, gastrointestinal tract, and retroperitoneum. The number of organs potentially involved and the noncontiguous mode of spread make non-Hodgkin's lymphoma a difficult tumor to evaluate at the time of laparotomy. To clarify the surgical management of patients with this tumor, we retrospectively reviewed the medical records of 202 patients with histologically proven abdominal lymphomas. Within this group, 36 patients underwent laparotomy before they had chemotherapy or radiation therapy. Ten patients were explored to establish a histologic diagnosis of lymphoma. The remaining 26 patients underwent laparotomy because of presumed benign disease. Twenty patients were found to have localized disease at laparotomy. Patients with localized disease demonstrated significantly better survival than patients with extranodal and nodal involvement (p less than 0.05). Four patients with local resection received no adjuvant therapy and were free of disease a median of 50 months after surgery.

Abdominal Neoplasms↗