Biomedical subjects

J L Cameron

Publications and source records attributed to J L Cameron.

At least 181 records · Page 10Linked to original sources

PubMed1991

Slowing of pulsatile luteinizing hormone secretion in men after forty-eight hours of fasting.

To determine whether short periods of fasting can suppress the activity of the reproductive axis in normal healthy men, eight men were studied on a fed day and again after 48 h of fasting. Subjects were between 20-32 yr of age and ranged from 84-119% of normal body weight. Blood samples were collected on day 1 (a fed day) and day 3 (after 48 h of fasting) at 15-min intervals from 0800-1600 h through indwelling venous catheters. Fasting for 48 h resulted in a significant decrease in mean LH, FSH, and testosterone concentrations. The mean LH concentration decreased from 2.94 +/- 0.59 IU/L on the fed day to 1.07 +/- 0.14 IU/L after 48 h of fasting, and there was an accompanying decrease in LH pulse frequency (from 5.13 +/- 0.29 to 2.63 +/- 0.62 pulses/8 h) and mean baseline LH concentration (from 1.83 +/- 0.52 to 0.51 +/- 0.07 IU/L), but no significant decrease in LH pulse amplitude. In a second study, blood samples were collected from five subjects who were allowed to eat normally between days 1 and 3; these individuals showed no difference in LH secretion. To begin to examine the possibility that an activation of the hypothalamic-pituitary-adrenal axis leads to the suppression of reproductive hormone levels that occurred after 48 h of fasting, cortisol levels were measured in all plasma samples. There was no significant difference in mean cortisol concentrations on fed vs. fasted days or when cortisol concentrations were examined as hourly means across the 2 days. These results indicate that activity of the reproductive axis can be suppressed in normal healthy men by 48 h of fasting. It appears unlikely that activation of the adrenal axis is the cause of this suppression of reproductive axis activity.

Adult↗

PubMed1991

Choledochal cysts: classification and cholangiographic appearance.

A classification scheme for choledochal cysts is outlined and their appearance on cholangiograms is illustrated. Choledochal cysts are uncommon anomalies of the biliary system and are probably congenital in origin. They are manifested by cystic dilatation of the extra- or intrahepatic biliary tree or both. The classification system described here divides choledochal cysts into one of five main types. The most common, which is manifested by cystic or focal segmental dilatation of the common bile duct or fusiform choledochal dilatation, accounts for 80-90% of cases.

Cholangiography↗

PubMed1991

The role of cholecystokinin in the pathogenesis of acute pancreatitis in the isolated pancreas preparation.

In a variety of animal models of acute pancreatitis, cholecystokinin-receptor antagonists have ameliorated the injury response. These results suggest that cholecystokinin may play a primary role in the pathogenesis of pancreatitis initiated by multiple stimuli. In an effort to test this theory, a sensitive and high affinity cholecystokinin-receptor antagonist L364,718 was administered to four different models of acute pancreatitis that were produced in the ex vivo perfused canine pancreas preparation. The four models of pancreatitis were initiated by cerulein infusion, partial duct obstruction with secretin stimulation, oleic acid infusion, and a 2-hour period of ischemia. In each model, pancreatitis was manifest by edema formation, weight gain, and hyperamylasemia during a 4-hour perfusion. In cerulein infusion-induced pancreatitis L364,718 inhibited edema formation and weight gain (31 +/- 5 gm versus 7 +/- 6 gm; p less than 0.05) and significantly decreased plasma amylase activity (36,605 +/- 21,216 U/dl versus 9421 +/- 5149 U/dl; p less than 0.05). The acute pancreatitis induced by the other three stimuli was not ameliorated by L364,718 treatment. We conclude that in the ex vivo-perfused canine pancreas preparation cerulein-induced pancreatitis is mediated at least in part by the cholecystokinin receptor. Early blockade of the cholecystokinin receptor was of no benefit in treating the other models of pancreatitis, suggesting that cholecystokinin is not involved in the early pathogenesis.

Acute Disease↗

PubMed1991

Transduodenal exploration of the common bile duct in patients with nondilated ducts.

Exploration of the small common bile duct can be technically difficult and is associated with a significant risk of ductal injury or late stricture, or both. Transduodenal common duct exploration after sphincteroplasty (TCDE/S) is an alternative method of duct exploration that avoids choledochotomy. Cholecystectomy followed by TCDE/S was performed upon 28 patients with nondilated ducts and suspected choledocholithiasis. Common duct stones were retrieved in 17 patients. Failure to retrieve stones in the remaining 11 patients was attributed to either false-positive results of cholangiography, forceful passage of stones into the duodenum during the initial insertion of a Fogarty catheter through the cystic duct or a false-negative finding at duct exploration. There was no perioperative mortality. Two patients had asymptomatic postoperative hyperamylasemia. One patient had postoperative pancreatitis, hyperbilirubinemia and cholangitis that resolved with antibiotic therapy by the eighth postoperative day. Other complications included wound infection, delayed gastric emptying, pneumonia and otitis media. The over-all morbidity rate was 28.6 per cent. Long term follow-up was obtained in all 28 patients. All patients in the follow-up group are free of recurrent biliary tract disease. TCDE/S appears to be a safe and effective method of exploring the nondilated common bile duct.

Adult↗

PubMed1991

Suprarenal mesocaval shunt.

A new technique for performing a mesocaval shunt above the level of the renal veins is described. It should be considered an option for those patients with perirenal vena caval occlusion or obstruction who require surgical decompression of the portal venous system.

Adult↗

PubMed1991

Cerulein-induced pancreatitis in the ex vivo isolated perfused canine pancreas.

Infusion of supramaximal doses of the cholecystokinin analog cerulein is well established as an in vivo technique for inducing experimental pancreatitis in small animals. An attempt was made to simulate this model and initiate pancreatitis in the ex vivo isolated perfused canine pancreas. Control preparations gained minimal weight (mean 8.3 +/- 5.1 gm), demonstrated no edema accumulation, and did not develop hyperamylasemia (mean 1342 +/- 790 units) after 4 hours of perfusion. Electron microscopy after 4 hours of perfusion remained normal. Intraarterial cerulein infusion produced significant weight gain (mean 27.6 +/- 12.3 gm; p less than 0.001), edema formation, and marked hyperamylasemia (mean 26,838 +/- 21,341 units; p less than 0.001) after 4 hours of perfusion. During the 4-hour perfusion, electron microscopy of cerulein preparations demonstrated depletion of zymogen granules, condensing vacuole formation, and basolateral exocytosis. Pretreatment of cerulein preparations with the free radical scavengers superoxide dismutase and catalase and the iron chelator deferoxamine did not modify the pancreatitis. Continuous infusion of the nonpeptide cholecystokinin antagonist L364,718 reduced cerulein-induced weight gain (4.3 +/- 3.4 gm; p less than 0.001) and hyperamylasemia (9392 +/- 6718 units; p less than 0.05). We conclude that cerulein pancreatitis in the ex vivo isolated perfused canine pancreatic preparation is identical physiologically, biochemically, and morphologically with that seen in intact animals.

Acid-Base Equilibrium↗

PubMed1990

Clinical prediction rule for pulmonary infiltrates.

OBJECTIVE: To derive and validate a clinical rule for predicting pneumonic infiltrates in adult patients with acute respiratory illness. DESIGN: Prevalence studies in three settings. SETTING: Emergency departments of the University of Illinois Hospital at Chicago, the University of Nebraska Medical Center at Omaha, and the Medical College of Virginia at Richmond. PATIENTS: Symptoms, signs, comorbidity data, and chest roentgenogram results were recorded for 1134 patients from Illinois (the derivation set), 150 patients from Nebraska, and 152 patients from Virginia (the validation sets). All patients presented to the emergency department and had a chest roentgenogram to evaluate fever or respiratory complaints. MEASUREMENTS AND MAIN RESULTS: Within the training set, temperature greater than 37.8 degrees C, pulse greater than 100 beats/min, rales, decreased breath sounds, and the absence of asthma were identified as significant predictors of radiographically proved pneumonia in a stepwise logistic regression model (P = 0.001). The logistic rule discriminated patients with and without pneumonia in the training set with a receiver operating characteristic (ROC) area of 0.82. In the validation sets, the rule discriminated pneumonia and nonpneumonia with ROC areas of 0.82 and 0.76 after adjusting for differences in disease prevalence (P greater than 0.2 compared with the training set). The predicted probability of having pneumonia for patients with different clinical findings corresponded closely with the incidence of pneumonia among patients with such findings in the three settings. CONCLUSIONS: Among adults presenting with acute respiratory illness, a prediction rule based on clinical findings accurately discriminated patients with and without radiographic pneumonia, and was used in two other samples of patients without significant decrement in discriminatory ability. This rule can be used by physicians to develop more effective strategies for detecting pneumonia and for helping to determine the need for radiologic study among patients with acute respiratory disease.

Acute Disease↗

PubMed1990

Management of proximal cholangiocarcinomas by surgical resection and radiotherapy.

Ninety-six patients with proximal cholangiocarcinomas were managed surgically. Fifty-three patients (55 percent) were resected, 39 curatively (41 percent), and 43 (45 percent) underwent palliative stenting. The preoperative placement of Ring catheters and the operative use of silastic transhepatic biliary stents greatly facilitated the surgical management of these lesions. Sixty-three patients (66 percent) also received postoperative radiotherapy. Hospital mortality was 4 percent (four deaths). Hospital mortality was 2 percent after resection (1 of 53 patients) and 7 percent after palliative stenting (3 of 43 patients). All deaths resulted from sepsis. One, 3, 5, and 10-year survivals for the entire group were 49 percent, 12 percent, 5 percent, and 2 percent, respectively. One, 3, 5, and 10-year survivals in the resected group (66 percent, 21 percent, 8 percent, and 4 percent, respectively) were superior to those in the stented group (27 percent, 6 percent, 0 percent, and 0 percent, respectively). Radiotherapy appeared to significantly extend survival in those patients undergoing palliative stenting, but not in those undergoing resection. We conclude that surgical resection of proximal cholangiocarcinomas can be performed safely and that it significantly prolongs survival. Further improvement in long-term survival will depend on advances in adjuvant therapy.

Adenoma, Bile Duct↗

PubMed1990

Preoperative assessment of malignant hepatic tumors.

Over a 31-month period, 100 patients with malignant hepatic tumors were preoperatively evaluated with three imaging techniques. The results of intravenously enhanced computed tomography (CT) scan, selective hepatic arterial contrast CT, and magnetic resonance imaging (MRI) were compared with operative findings. A total of 227 lesions were identified, with the sensitivity for tumor detection being arteriographically enhanced CT 94% (p less than 0.01), MRI 70%, and CT 66%. This advantage for arteriographically enhanced CT was most marked for lesions less than 1 cm in diameter (82% versus 20% for MRI and 5% for CT; p less than 0.01). Arteriographically enhanced CT was also most sensitive in assessing tumor margins. MRI was clearly superior to arteriographically enhanced CT or CT in detecting vascular involvement (85% versus 30% and 8%, respectively; p less than 0.01). No imaging technique was sensitive in determining extrahepatic involvement. Arteriographically enhanced CT was also best at predicting the operative procedure. The combination of arteriographically enhanced CT and MRI was the best predictor of true disease. We conclude that both arteriographically enhanced CT and MRI should be used for preoperative assessment of hepatic malignancies.

Adolescent↗

PubMed1990

Diagnosis and management of the Budd-Chiari syndrome.

Occlusion or obstruction of hepatic venous outflow results in the Budd-Chiari syndrome. The disorder should be suspected in any patient who suddenly develops massive ascites, and the diagnosis can be confirmed quickly and accurately by hepatic venography. In the absence of surgical intervention, survival is rare. Inferior venacavography and percutaneous liver biopsy can be performed safely in these patients, and both procedures provide useful information for the selection of appropriate surgical therapy. Most cases of the Budd-Chiari syndrome are amenable to mesocaval or mesoatrial shunting. Those patients with documented cirrhosis or fulminant hepatic failure are best managed by orthotopic liver transplantation.

Budd-Chiari Syndrome↗

PubMed1990

The interposition mesocaval shunt.

The interposition mesocaval C-shunt is an excellent alternative for the management of bleeding esophageal varices. The comparable operative mortality, long-term survival, and minimal operative time and blood loss make it the emergency shunt of choice. The C-shunt modification has improved long-term patency and ease of operation. The interposition mesocaval shunt also is increasing in importance as the best portosystemic shunt in those patients who may eventually require liver transplantation.

Esophageal and Gastric Varices↗

PubMed1990

Postoperative bile duct strictures.

Bile duct strictures are an uncommon but serious complication of primary operations on the gallbladder or biliary tree. Most strictures occur as a result of injury to the bile duct during cholecystectomy. In addition, strictures can occur at the site of previous biliary anastomoses for reconstruction of the biliary tree. Most patients with benign bile duct strictures present soon after their initial operation; however, in some cases, presentation is delayed for years. Cholangiography is essential for defining the anatomy of the biliary tree prior to management. In many cases, nonoperative biliary drainage is useful to treat sepsis and biliary fistulas. A number of alternatives exist for elective repair of bile duct strictures. Experience would suggest, however, that a choledochojejunostomy or hepaticojejunostomy performed through a Roux-en-Y limb of jejunum is the preferable management in most cases. Postoperative biliary stenting may be valuable in optimizing the results. Nonoperative management by percutaneous transhepatic or endoscopic balloon dilatation has been reported to be successful in a number of small series. Long-term results are limited, however. Comparative data suggest that surgical repair for benign postoperative strictures is associated with fewer long-term problems and with similar overall morbidity and costs.

Bile Ducts↗

PubMed1990

Primary sclerosing cholangitis.

Primary sclerosing cholangitis is a rare disease of unknown etiology. Sclerosis of the bile ducts may actually be the final result of multiple factors such as autoimmune, bacterial, congenital, drug, or viral injury. The most commonly associated diseases are ulcerative colitis and chronic pancreatitis. Except in the earliest stages of the disease, liver histologic findings are not specific. Most patients present with jaundice, pain, and pruritus, although an increasing number of asymptomatic patients with inflammatory bowel disease and abnormal liver function are being identified. Cholangiography is key to the diagnosis and is usually pathognomonic except in the unusual case where primary sclerosing cholangitis is confused with cholangiocarcinoma. Many forms of medical therapy have been tried, including antibiotics, azathioprine, cholestyramine, colchicine, cyclosporine, D-penicillamine, steroids, and ursodeoxycholic acid. To date, none of these medications has been proved to alter the course of this disease. Recent reports of ursodeoxycholic acid trials have been encouraging, but long-term results of ongoing randomized trials have yet to be published. In recent years, balloon dilatation of biliary strictures has been accomplished via endoscopic and percutaneous transhepatic approaches. However, in patients with primary sclerosing cholangitis, these nonoperative manipulations must be done repeatedly, may entail multiple general anesthetics, and are difficult to perform. We believe that a direct surgical approach to the biliary tree with long-term transhepatic stenting is indicated in selected patients with severe hilar or extrahepatic stricturing, persistent jaundice or recurrent cholangitis, and no evidence of cirrhosis. Hepatic transplantation should be reserved for patients with primary sclerosing cholangitis who have well-established cirrhosis and have not responded to other therapeutic measures.

Cholangitis, Sclerosing↗

PubMed1990

Cholangiocarcinoma.

The diagnosis of cholangiocarcinoma can now be made with greater rapidity and accuracy. In the clinical setting of obstructive jaundice, a CT scan or sonogram may suggest cholangiocarcinoma if dilated intrahepatic ducts are seen with a nondilated extrahepatic biliary tree. The diagnosis is confirmed by cholangiography, and the tumor is staged by the combination of cholangiography and angiography. If the tumor extensively involves both lobes of the liver or involves the main portal vein or hepatic artery, the lesion is considered unresectable. These patients are best palliated nonoperatively, but they should still have an attempt at a tissue diagnosis, as various other lesions can masquerade as cholangiocarcinoma. In comparison, if the tumor is confined to or is distal to the hepatic duct bifurcation, extends into only one lobe of the liver, or involves only the right or the left portal vein or hepatic artery, the lesion may be resectable, and exploration is indicated. As many as half of all patients explored with curative intent will have a successful resection. Various surgical options are appropriate for patients undergoing tumor resection, depending on the site and extent of the lesion. Similarly, several surgical options are possible for palliation in patients with unresectable cholangiocarcinoma. The role of radiotherapy in the management of cholangiocarcinoma is uncertain. Our results, like those of many other retrospective analyses, suggest that radiotherapy prolongs survival after curative resection as well as after palliative stenting. However, further data from randomized studies are necessary to support or refute this impression. Further studies of adjuvant chemotherapy or hormonal therapy will also be necessary to improve patient survival.

Adenoma, Bile Duct↗

PubMed1990

Is preoperative angiography useful in patients with periampullary tumors?

Ninety patients with periampullary tumors, staged by CT scan and believed to be resectable, were staged further by visceral angiography. Most of these patients (78) had carcinoma of the head of the pancreas. Visceral angiography was normal in 62 patients. Major vessel encasement (17 patients) or occlusion (11 patients) was identified in 28 patients. There were no complications related to angiography. Among the 62 patients with normal angiograms, 48 underwent a pancreaticoduodenectomy, for a resectability rate of 77%. Among the 17 patients with vessel encasement, the resectability rate was 35%. For the 11 patients with vessel occlusion, the resectability rate was 0%. Combined with CT scan, visceral angiography is a useful adjunct in the staging of patients with periampullary tumors. Major vessel occlusion precludes resection, and major vessel encasement makes resection unlikely. If visceral angiography is normal, it is very likely that the tumor will be resectable.

Adenocarcinoma↗

PubMed1990

The triad of Streptococcus bovis bacteremia, colonic pathology, and liver disease.

The association of Streptococcus bovis endocarditis and colon carcinoma has been reported previously in small series in the medical, but not surgical, literature. Although the fecal carriage rate of S. bovis increases with colonic pathology, no explanation exists for the development of bacteremia in these cases. To explore the possible contribution of hepatic dysfunction to the development of portal and systemic bacteremia, the incidence of both colonic pathology and liver disease or dysfunction was determined in 92 patients with S. bovis endocarditis and/or bacteremia. Colonic and liver evaluation had been undertaken in 47% and 93% of patients, respectively. Among these patients, colonic pathology was identified in 51%, and liver disease or dysfunction was documented in 56%. Either the underlying colonic disease or alterations in hepatic secretion of bile salts or immunoglobulins may promote the overgrowth of S. bovis and its translocation from the intestinal lumen into the portal venous system. A compromised hepatic reticuloendothelial system may then contribute to the development of S. bovis septicemia and subsequent endocarditis. We conclude that S. bovis bacteremia is an indication to the clinician of the possibility of underlying liver disease as well as colon pathology.

Colonic Diseases↗

PubMed1990

Current management of the Budd-Chiari syndrome.

Twenty-six patients with the Budd-Chiari syndrome were treated surgically at the Johns Hopkins Hospital. Twenty-one of the patients were female and five were male, with a median age at diagnosis of 37 years. Nine patients had polycythemia vera, 6 were receiving estrogen therapy, 5 had a previous hepatitis A or B infection, and 4 had cirrhosis. There was one case each of hepatic malignancy, paroxysmal nocturnal hemoglobinuria, and idiopathic thrombocytopenic purpura. In five cases no etiologic factors or associated disorders were identified. Ascites was the most common presenting feature in this group of patients. Hepatic function at the time of diagnosis, as measured by standard serum chemistries, was only minimally abnormal. The diagnosis of the Budd-Chiari syndrome was confirmed in all 26 patients by hepatic vein catheterization. Inferior vena cavography was also performed and revealed caval occlusion in 4 patients, significant caval obstruction in 13 patients, and a normal vena cava in 9 patients. Interpretation of the vena cavogram was helpful in selecting the appropriate surgical procedure for each patient. Twenty-three of the twenty-six patients underwent percutaneous liver biopsy before operation, with no morbidity or mortality. Four patients had well-established cirrhosis noted on biopsy. Thirty mesenteric-systemic venous shunts were performed on the 26 patients. In 11 patients a mesocaval shunt was performed and in one instance conversion to a mesoatrial shunt was required as a second procedure. In 15 patients a mesoatrial shunt was performed as the initial procedure. Graft thrombosis occurring in 2 of these 15 patients prompted one revision in 1 patient and 2 revisions in the second patient. After mesenteric-systemic venous shunt, eight of the patients (31%) died before discharge from the hospital. The remaining 18 patients in this series were discharged from the hospital alive and well with patent shunts. Patients were followed for a median of 43 months (range, 9 months to 13 years). Five late deaths occurred between 5 and 84 months after the operation. Three- and five-year actuarial survival rates were 65% and 59%, respectively.

Adolescent↗

PubMed1990

Effect of estradiol and progesterone administration upon the circadian rhythm of oxytocin in the cerebrospinal fluid of rhesus monkeys.

The effect of administration of estradiol (E2) alone or combined with progesterone upon the circadian rhythm of oxytocin concentrations in cerebrospinal fluid (CSF) was examined in adult ovariectomized rhesus monkeys bearing temporary subarachnoid catheters and maintained in a constant photoperiod (lights on 06.00-18.00 h). Animals were subcutaneously implanted with silastic capsules containing 17 beta-E2 for 6 days and progesterone for the last 3 days of E2 administration. Hourly samples of CSF were collected before, during and after gonadal steroid administration and measured for oxytocin by RIA and reverse-phase high-performance liquid chromatography (RP-HPLC). A significant increase in the serum concentration of E2 and the plasma concentration of oxytocin neurophysin, but not the plasma concentration of oxytocin, was found during gonadal steroid administration. Each animal displayed a dirunal pattern of secretion of oxytocin in CSF with peak and trough levels during light and dark hours, respectively. No significant differences were found across experimental conditions in the following CSF oxytocin parameters: mean level of oxytocin in CSF during the light, dark, or light and dark hours combined; the daily phase or amplitude of the CSF oxytocin rhythm; the peak or nadir concentration of oxytocin in CSF; or the total amount of oxytocin secreted into the CSF as expressed as the area under the curve (multivariate repeated measures ANOVA). The CSF oxytocin parameters in the animals that were restudied using empty silastic implants were not significantly different across time (multivariate repeated measures ANOVA).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗