Do first- and second-year preclinical course scores predict student performance during the surgical clerkship?

The study proposed to determine if a preclinical basic science index comprised of anatomy, behavioral medicine, biochemistry, microbiology, pathology, pharmacology, and physiology courses or any one of these basic science courses would predict student performance during surgical clerkship. The basic science index demonstrated a correlation of 0.55 and 0.35 with the individual student's written and oral clerkship scores, respectively. A stepwise multiple regression using a backward stepping algorithm was applied; the dependent variables were oral and written clerkship scores, and the independent variables were the basic science courses. Microbiology, pathology, and physiology course scores were predictors of written score (R = 0.60). Pathology course scores were the sole predictor of oral score (R = 0.43). Medical student basic science performance was not a strong forecaster of performance on the surgical clerkship. The pathology basic science score was the only consistent predictor of performance on the written and oral evaluations given at the end of the clerkship.

Adverse cardiodynamic effects of vasopressin not avoided by selective intra-arterial administration.

In this study, lysine-vasopressin, administered either as a continuous, intravenous infusion (1 unit/kh/hour) or as a selective infusion into the superior mesenteric artery (0.2 unit/minute), produced equal (25%), significant (p less than 0.05), and sustained (60 minute) reductions in portal pressure. Compared to intravenous administration, selective intra-arterial infusion of vasopressin resulted in similar reductions incardiac output (38%), myocardial contractility (23%), and coronary flow (53%). Since these adverse cardiodynamic effects were not avoided by selective intra-arterial infusion, it would appear that administration of vasopressin as a continuous infusion through a peripheral vein remains the most rapid and practical method of administering the drug.

Papillary cystic and solid tumors of the pancreas: a pancreatic embryonic tumor? Studies of three cases and cumulative review of the world's literature.

BACKGROUND: The papillary cystic and solid tumor of the pancreas is rare. It occurs predominantly in young women, and most present a benign behavior. The pathogenesis of this tumor has attracted a number of investigations but remains unclear. METHODS: We present three patients with this tumor and a review of 289 others from the world's literature, a total of 292 cases. On the basis of the analyses of the clinical and pathologic features from the reported cases, the pathogenesis of this unusual tumor has been further explored. RESULTS: Ninety percent of the patients were female, with a mean age of 23.9 years. The tumors were usually quite large with a mean diameter of 10.3 cm. Ninety-two percent of these tumors were totally or partially cystic. Rupture of the capsule resulted in hemoperitoneum in eight cases, five of which were without any identifiable cause. Forty-three tumors (14.7%) have been recognized as malignant. The overall prognosis has been excellent and an aggressive approach to resection is indicated. CONCLUSIONS: The results of immunohistochemical staining and electromicroscopy were rather diverse, but most, including the current cases, support the hypothesis that the tumor originates from pleuripotential embryonic stem cells. Thus the term pancreatic embryonic tumors seems preferable to papillary cystic and solid tumor of the pancreas to delineate the origin of the tumor and to reflect some of its biologic characteristics.

Observations on fifty distal splenorenal shunts.

Fifty patients underwent conventional distal splenorenal shunts for bleeding esophageal varices. Five patient died within 30 days, giving an operative mortality of 10%. Three patients were lost of follow-up, but 47 patients were evaluated. Twelve patients died, 11 of liver failure, with more than half of the deaths occurring with 1 year, three fourths within 2 years, and all within 3 years after operation. Eleven patients rebled, and seven of these were among those who died. Sixteen patients had ascites prior to operation, but all responded to aggressive medical therapy. Twenty-two patients were available for study 2 or more years following operation. Eighteen (82%) are well with no encephalopathy, although the remaining four (18%) have had transient episodes of encephalopathy. Sixteen of the 18 patients judge their lifestyles to be productive. If the patient survived 24 months or longer, he had a four in five chance of living a normal life.

Primary malignant peritoneal mesothelioma. A report of seven cases and a review of the literature.

Mesothelioma of the peritoneum is a rare malignant neoplasm easily mistaken by both surgeon and pathologist for one of the more common neoplasms of the abdomen. Review of our records from metropolitan-area hospitals for the past 15 years identified seven patients with primary peritoneal mesotheliomas. Their diagnosis, management, and survival is analyzed. We report a case of an extended survivor (7 years) and one of a long-term survivor (15 years), as well as what we believe to be the only case in the literature presenting with a coexistent malignant neoplasm. Prevention of this commonly fatal neoplasm is linked to avoiding occupational exposure to asbestos; long-term survival for a few patients may be achieved with correct identification of the neoplasm and aggressive management. This report includes a review of the literature.

Criteria for the selection of 'early' carcinomas of the rectum. Are they valid?

We retrospectively reviewed 76 cases of adenocarcinoma of the lower rectum treated by abdominoperineal resection between 1975 and 1985 to elucidate the relationship between pathologic stage and both the size and histologic grade of the tumor. Our results showed evidence of lymphatic invasion in 50% of the 36 patients with tumors 4.0 cm or less in diameter, 51% of the 68 patients with tumors of either a high or moderate degree of differentiation, and an alarming 53% of the 34 patients whose tumors satisfied both criteria simultaneously. Finally, a substantial proportion (25%) of patients who had only partial invasion of the muscular layer also had lymphatic metastases. These results differ significantly from what has been previously reported and lead us to conclude that the commonly used criteria of size and histologic grade are inadequate criteria and do not allow confident selection of patients with lesions suitable for local treatment.

A series of 20 successful Warren shunts.

Recent reports suggest that the distal splenorenal shunt does fulfill its physiological promises. The portal and the gastroesophagealsplenic areas are divided into separate "venous watersheds." As a result, varices are decompressed but portal hypertension is preserved. It should, therefore, have its greatest advantage for patients with the most severe impairment of hepatic reserve. In this evaluation, the procedure was considered the operation of choice for all shunt candidates who had a patent splenic vein. A series of 20 patients, 12 with Laënnec cirrhosis, seven with postnecrotic cirrhosis, and one with Wilson disease, survived shunting and were discharged from the hospital. One patient died of hepatic coma eight weeks after operation. If lengthy follow-up studies confirm its capacity to prevent hemorrhage, the distal splenorenal shunt may be the safest elective shunt operation for patients with cirrhosis.

Traumatic mesenteric arteriovenous fistula presenting as the superior mesenteric artery syndrome.

Arteriovenous fistulas of the mesentery are rare sequelae of abdominal injuries or operations. Symptoms, when present, are most often due to intestinal ischemia or portal hypertension. Cardiac failure is less common, and the case described in this report is, to our knowledge, the first in which the patient presented with duodenal obstruction--the superior mesenteric artery syndrome. A bruit is an expected finding and a thrill is pathognomonic of an arteriovenous fistula. With rare exception, operation is indicated to dismantle the fistula.

Primary duodenal tumors: a diagnostic and therapeutic dilemma.

The case records of ten patients with benign, three with endocrine, and 19 with malignant duodenal tumors were reviewed. Patients with benign tumors had episodes of bleeding that were recurrent in a number of cases. The endocrine tumors were all gastrinomas; patients had ulcer diathesis associated with the Zollinger-Ellison syndrome. All malignant tumors were symptomatic, with chronic gastrointestinal blood loss or duodenal obstruction. All benign tumors were demonstrated preoperatively, but only ten of 19 malignant tumors were confirmed preoperatively. The data suggest that duodenal tumors masquerade as more common diseases and as a result, their diagnosis and treatment are delayed inordinately. Awareness of this problem is encouraged, and a more aggressive diagnostic effort in selected patients, including fiberoptic endoscopy, is suggested.

Total proctocolectomy and ileostomy: procedure of choice for acute toxic megacolon.

Of 42 critically ill patients with toxic megacolon, 31 required emergency surgery, and 11 were treated without operation. Of the 11 patients treated by medical measures alone, there were two deaths (18%): one early, secondary to undiagnosed colonic perforation, and one late death from recurrent ulcerative colitis. Nine of ten survivors (90%) experienced continued morbidity, and five (50%) required subsequent elective surgery. Thirty-one patients required emergency operation for failure of medical treatment (19), colonic perforation (ten), and uncontrolled hemorrhage (two). Early and late morbidity was 74% (two-thirds occurring after subtotal colectomy and ileostomy). Surgical mortality was 19% (8% over the last ten years).

Abnormal left renal vein. No barrier to Warren shunt.

The purpose of the distal splenorenal shunt is to provide decompression of gastroesophageal varices while avoiding insult to the diseased liver. However, the technical difficulty of the operation has prevented widespread application of the procedure. It is important, therefore, that the technical problems an hazards of the operation continue to undergo analysis. This report has described successful establishment of a Warren shunt in three patients with abnormalities of the left renal vein. Previous left nephrectomy or an anomaly of the left renal vein does not preclude the use of the distal splenorenal shunt in the treatment of variceal hemorrhage.

Isoproterenol in offsetting adverse effects of vasopressin in cirrhotic patients.

Vasopressin administered as a peripheral infusion (40 U/hr) significantly reduced portal vein pressure in ten awake patients with cirrhosis and portal hypertension. A vasopressin-induced reduction in cardiac output occurred in five of the ten patients (50 per cent). Vasopressin-induced changes in systemic arterial pressure, heart rate, and portal venous pressure were independent of alterations in cardiac output. When the five patients with vasopressin-induced reductions in cardiac output were given a combination of vasopressin and isoproterenol, cardiac output was maintained and the reduction in portal vein pressure was equal to that observed with unopposed vasopressin therapy. Thus, the addition of isoproterenol prevented a vasopressin-induced reduction in cardiac output while permitting vasopressin to reduce portal vein pressure.

Peripheral vasopressin for safe and adequate control of portal hypertension during shunt operations.

Nine patients with cirrhosis and portal hypertension were given intraoperative vasopressin (40 U/hr) in a continuous peripheral infusion during establishment of a distal splenorenal shunt. In all patients a significant and sustained reduction in portal venous pressure was achieved. As a result, blood loss during dissection and the time required for operation were minimized. The expected vasopressin-induced reduction in cardiac output was limited to a transient decrease at 5 minutes. There were no significant cardiac arrhythmias. These results suggest that vasopressin given through a peripheral vein during shunt operations is safe and facilitates dissection by providing significant and sustained reductions in portal venous pressure.

Isolated perfusion of pancreas with mitomycin C.

The current treatment of pancreatic cancer with resection and/or radiation is considered unsatisfactory because of a high incidence of failure and a moderate incidence of complications. A sizable number of these patients present with localized or regional disease. Regional high-dose chemotherapy, such as with isolated perfusion, may offer an alternative therapy with low treatment-related morbidity and mortality and better end results in this group of patients. In an effort to develop such a treatment modality, we evaluated the pharmacokinetics and toxicity of mitomycin C (MMC) during isolated perfusion of pancreas in a canine model. From this study, it appears that a dose of 0.25 mg MMC/kg body weight is most suitable for isolated perfusion of pancreas at 39 degrees C, maintaining flow rate and pressure within physiologic range. Isolated perfusion with a dose of 0.25 mg/kg body weight has very mild short- and long-term toxicities and markedly increases drug delivery to the pancreas, duodenum, and peripancreatic lymph nodes, making it the most suitable dose for possible clinical application.

History of the pancreas.

The pancreas was generally ignored in antiquity, both as an organ and as a seat of disease. The first description of the pancreas is attributed to Herophilus. It was in the 17th century that the main duct of the organ was described and its significance demonstrated. At that time, Brunner thought that the pancreas was not essential to digestion, and he failed to associate the pancreas with diabetes. Claude Bernard discovered the function of the pancreas in digestion. In 1922, Banting and Best obtained isletin and demonstrated the capacity of the substance to cause a dog to recover from diabetic coma. In 1889, Reginald Fitz firmly established pancreatitis as a disease entity. In 1927, the first case of hyperinsulinism due to a tumor of the islet cells was reported. Twenty-eight years later, Zollinger and Ellison described two patients with unusually severe peptic ulcer disease, both of whom had noninsulin-secreting tumors of the pancreatic islets. Subsequently, gastrin was isolated as the hormone responsible for this syndrome. In March 1940, Dr. O. Whipple performed the first recorded one-stage pancreaticoduodenectomy. Much progress has been made since then and today transplantation of isolated islets and portions of whole pancreas is a reality.

Influence of clerkship structure and timing on individual student performance.

Student oral and written surgical clerkship performances may be related to the clerkship structure and the time of year the students rotate through the clerkship. The influence of calendar block, hospital site (university hospital, affiliated private tertiary-care hospital, and rural preceptor experience), and the mix of general surgical versus subspeciality rotations on oral and written student surgery clerkship scores was analyzed. Multivariate analysis of variance revealed significant differences in score for calendar block (p = 0.02) only; this difference resided in the written examination. The various combinations of rotations were not different from one another in terms of measured outcome.

Anatomic characteristics of the pancreatic arteries. Radiologic observations and their clinical significance.

Major complications of operations that remove or transplant a portion of the pancreas appear related to the arterial blood supply. Hemorrhage is a result of inadequate control of the appropriate principal arteries, and ischemia and its consequences occur when the arterial blood supply to portions of preserved pancreas has been inadvertently interrupted. This radiographic study of the principal arteries of the pancreas demonstrates that these vessels may be visualized and their origin determined in the vast majority of cases. The application of data gained from preoperative arteriography can potentially decrease the incidence of major complications associated with removal or transplantation of portions of the pancreas.

Assessment of enterohepatic circulation of 3H-digoxin with a minimal interruption technique.

The biliary excretion of 3H-digoxin in rats prepared for bile sampling with minimal interruption of the enterohepatic circulation was compared with that in rats with complete interruption after intraduodenal or intravenous administration. Following dosage by either route, significantly more radioactivity was recovered from animals with nearly intact enterohepatic circulation. The method described allows direct measurement of this cycle in unanesthetized animals without the consequences of bile depletion.

Feeding the rat intravenously with ketone bodies following colon anastomosis.

Ketone bodies are an important metabolic fuel for the gastrointestinal system and as a consequence may promote colonic healing. Ketone bodies and glucose were compared in a dose dependent manner as nonprotein fuels for support of resected colon. Rats had their descending colons resected and received all nutrients by vein for 5 days postoperation. Colonic healing was evaluated from the air pressure required to break the wound. All rats received constant nutrients except for non-protein energy which was fed at 10.5, 21, 31.5, and 42 kcal/day using either glucose or monoacetoacetin as substrate. Colonic bursting pressure was measured on day 5 after surgery. When energy intake was 21 kcal/day or greater, the bursting pressure was two-thirds of nonwounded tissue and was independent of energy quantity and source. At 10.5 kcal/day, bursting pressure for glucose-fed animals was similar to that for animals with no added nonprotein energy while, in contrast, bursting pressure for animals fed monoacetoacetin was similar to that for animals fed 42 kcal/day. It was concluded that bursting pressure was influenced by dietary intake only if the energy intake was sufficiently low, and then ketone bodies were better than glucose for support of colonic healing.

Parenteral monoacetoacetin and liver regeneration interaction after partial hepatectomy in the rat.

Parenteral nutrients can be used to manipulate cell proliferation after partial hepatectomy. The relationship among macronutrients--glucose, monoacetoacetin, amino acids--and liver regeneration after partial hepatectomy was investigated. Male rats were anesthetized, received a 70% hepatectomy, and received a low-dose infusion of (1) glucose or (2) monoacetoacetin and a high-dose infusion of (3) glucose, (4) glycerol-glucose, or (5) monoacetoacetin-glucose beginning 6 hours after surgery. The five nonprotein nutrient combinations were infused with and without amino acids. Rats were killed 48 hours after partial hepatectomy, and the label and mitotic indices were determined. Each of the five treatments had a higher label index with amino acids present than with amino acids absent. Low-dose glucose and monoacetoacetin as well as high-dose glucose and glucose-glycerol had higher mitotic indices with amino acids than without amino acids. High-dose monoacetoacetin-glucose was associated with a greater mitotic index than was any other nonprotein substrate treatment, and this response was independent of amino acids being present or absent. In summary, (1) amino acids were needed for maximal cell proliferation rate; (2) the absence of amino acids and not the presence of glucose resulted in reduction of the label and mitotic indices for regenerating liver; (3) high-dose monoacetoacetin increased mitosis with or without amino acids; and (4) monoacetoacetin activity was dose dependent. The results indicate that the best nutrient for treatment of patients with liver injury is acetoacetate. The second best nutrient would be the combination of high-dose glucose and amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)