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Biomedical subjects

J L Cameron

Publications and source records attributed to J L Cameron.

At least 199 records · Page 11Linked to original sources
PubMed1990

Pattern of oxytocin concentrations in the plasma and cerebrospinal fluid of lactating rhesus monkeys (Macaca mulatta): evidence for functionally independent oxytocinergic pathways in primates.

Two populations of oxytocin-staining neurons have been identified in the paraventricular nucleus: magnocellular neurons that terminate in the posterior pituitary and parvocellular neurons that terminate elsewhere in the central nervous system. Whether these oxytocin neurons are functionally separate was tested by measuring oxytocin concentrations in samples of peripheral blood and cerebrospinal fluid (CSF) obtained simultaneously from lactating rhesus monkeys during suckling. Lactating animals bearing temporary subarachnoid and venous catheters were maintained in a constant photoperiod (0600-1800 h). Samples of CSF were continuously withdrawn by peristaltic pump (0.1 mL/15 min) for 2-4 consecutive days from subarachnoid catheters with the tips placed at the T12-L1 level of the spinal column in four lactating monkeys 4 months postpartum and again after weaning. On 2 of these days, we observed and recorded periods of infant suckling and collected peripheral blood samples (1.2 mL) from the mother at 5-min intervals for 60 min. Oxytocin was measured in blood and CSF by RIA. Oxytocin concentrations increased in the plasma of the lactating monkeys during periods of nursing, with peak concentrations ranging from 4-16.7 microU/mL. No increase in plasma oxytocin was found on the day after the infant was weaned. Variations in the concentrations of oxytocin in CSF were independent of the suckling stimulus and plasma oxytocin concentrations and occurred during observed periods of no nipple contact by the infant and at the time of weaning after the infant had been removed from the mother. Each lactating animal also displayed a normal circadian variation in CSF oxytocin concentrations, with peak and nadir levels during light and dark hours, respectively. We conclude that release of oxytocin into the CSF of lactating monkeys is disassociated from release into the peripheral circulation. The data further support the conclusion that neuronal pathways giving rise to oxytocin in the CSF and the periphery are anatomically and functionally separate in primates.

Animals↗
PubMed1990

Isolated ventral pancreatitis in a patient with pancreas divisum.

A previously healthy 22-yr-old woman was found to have chronic pancreatitis restricted to the ventral pancreas in association with pancreas divisum. When conservative treatment failed, sphincteroplasty of both papillae was performed with good results. This well-documented case represents a clear exception to the commonly held concept that obstruction of the dorsal duct is the essential pathogenic factor in the development of pancreatitis associated with pancreas divisum. The importance of visualizing both the dorsal and ventral pancreatic ducts to direct therapy for patients with idiopathic pancreatitis is discussed. Theories of the pathogenesis of concomitant pancreatitis and pancreas divisum are reviewed.

Adult↗
PubMed1990

The natural history of pancreatic pseudocysts documented by computed tomography.

The clinical courses of 75 patients with pancreatic pseudocysts documented by computed tomography (CT) were retrospectively reviewed. History, physical examination, laboratory findings and CT scan data were analyzed. The treatment regimen followed during the period spanning the review dictated nonoperative management for those patients with asymptomatic pseudocysts who were able to tolerate oral intake. Operative management was used only for patients with persistent abdominal pain or enlargement or complications of pseudocyst. Approximately one-half of the patients (n = 36, 48 per cent) were managed nonoperatively, and the remainder (n = 39, 52 per cent) were treated operatively. In the group managed nonoperatively, with a mean follow-up period of one year, 60 per cent had complete resolution of the pseudocyst documented roentgenographically, and 40 per cent had pseudocysts that remained stable or decreased in size. Only one pseudocyst-related complication developed in the nonoperative group. No pseudocyst-related mortality occurred in either group. The size of the pseudocyst was a significant predictor of the need for operative drainage. Pseudocysts greater than 6 centimeters in diameter required surgical treatment in 67 per cent, significantly more frequently (p less than 0.05) than the 40 per cent of patients who required operative treatment for pseudocysts less than 6 centimeters in diameter. We conclude that a large proportion of patients with pancreatic pseudocysts, without specific indications for operative treatment, can be safely managed nonoperatively, with careful clinical and roentgenographic follow-up study.

Acute Disease↗
PubMed1990

Carcinoma of the pancreas: are we making progress?

Over the past several decades no disease has frustrated clinicians more than carcinoma of the pancreas. At the time of diagnosis most patients have been unresectable. Recent reports suggest that when resection is possible, pancreaticoduodenectomy can be performed safely and survival extended by adjuvant therapy.

Carcinoma↗
PubMed1990

Solid and papillary epithelial neoplasms of the pancreas.

Seven patients with solid and papillary epithelial neoplasms of the pancreas are reported. All were young women with a mean age of 22 years (range, 16 to 33 years old). Each patient had a large asymptomatic abdominal mass. The tumors ranged in size from 7 to 20 cm (average size, 13 cm) and were evenly distributed throughout the head, body, and tail of the pancreas. One patient had a metastatic tumor to her liver, which was unresectable. All other patients underwent resection, which included two distal pancreatectomies, two total pancreatectomies, one pancreaticoduodenectomy, and one local excision. Four of the seven patients had evidence of local invasions alone, and one had a liver metastasis and local invasion. All patients had the characteristic histologic pattern of a solid and papillary epithelial pancreatic neoplasm. All patients are alive with a mean follow-up of 10 years (range, 4 to 20 years). This is an unusual malignant neoplasm of the pancreas occurring predominantly in young women. Even though they are locally invasive, long-term survival is the rule. Surgical therapy should be aggressive, since liver metastasis may occur.

Adolescent↗
PubMed1989

Retained and recurrent bile duct stones: operative management.

Retained and recurrent bile duct stones can now be treated by a variety of nonoperative means. These include retrieval through instrumentation of the T-tube tract, chemical dissolution, endoscopic papillotomy, or lithotripsy. Operative management, however, is an alternative means of therapy that carries negligible mortality, minimal morbidity, and a high success rate. If operative management is used, for most patients common duct exploration, stone retrieval, and T-tube insertion will suffice. However, if the patient has risk factors that suggest the possibility of further stone disease, a drainage procedure such as a sphincteroplasty or choledochoduodenostomy should be added. Nonoperative management is now the first choice for managing retained or recurrent bile duct stones. If these methods fail or cannot be utilized, operative management can be used with a similar low mortality, low morbidity, and high success rate.

Anastomosis, Surgical↗
PubMed1989

Pancreatic lymphoma. Is surgery mandatory for diagnosis or treatment?

From 1982 to 1986, nine patients with non-Hodgkin's lymphoma primarily involving the pancreas were managed at the Johns Hopkins Medical Institutions. This group of nine patients represents 2.2% of patients with non-Hodgkin's lymphoma (nine of 402) and 4.9% of all patients presenting with pancreatic malignancies (nine of 182) at the Johns Hopkins Medical Institutions during this period. Computed tomography (CT) scan findings of a large pancreatic mass (6 cm) with extrapancreatic extension and significant retroperitoneal lymph node enlargement suggested lymphoma. Diagnosis was established by radiographically-guided needle biopsy in four patients, by laparotomy in four, and by peripheral lymph node biopsy in one. In five jaundiced patients, initial chemotherapy with the nonhepatotoxic agents cyclophosphamide and prednisone resulted in marked tumor regression, allowing for early resolution of jaundice and subsequent addition of more aggressive adriamycin containing combination chemotherapy. Overall, complete remission has occurred in six of nine patients, with a median survival of 24 months (range 4-69 months). It is concluded from this experience that the majority of patients with pancreatic lymphoma can be managed without surgery. Excellent control of symptoms, including jaundice, as well as long-term remission, can be obtained with chemotherapy alone. The only role for surgery in this setting may be to aid in establishing the diagnosis when percutaneous biopsy is nondiagnostic.

Aged↗
PubMed1989

Benign postoperative biliary strictures. Operate or dilate?

At The Johns Hopkins Hospital from 1979 through 1987, 42 patients had 45 procedures for benign postoperative biliary strictures. Three patients were managed with both surgery and balloon dilatation. Twenty-five patients underwent surgical repair with Roux-Y choledocho- or hepaticojejunostomy with postoperative transhepatic stenting for a mean of 13.8 +/- 1.3 months. Twenty patients had balloon dilatation a mean of 3.9 times and were stented transhepatically for a mean of 13.3 +/- 2.0 months. The two groups were similar with respect to multiple parameters that might have influenced outcome. Mean length of follow-up was 57 +/- 7 and 59 +/- 6 months for surgery and balloon dilatation, respectively. No patients died after any of the procedures. The same definition of a successful outcome was applied to both groups and was achieved in 88% of the surgical and in only 55% of the balloon dilatation patients (p less than 0.02). Significant hemobilia occurred more often with balloon dilatation (20% vs. 4%, p less than 0.02). The total hospital stay and cost of balloon dilatation was not significantly different from surgery. We conclude that surgical repair of benign postoperative strictures results in fewer problems that require further therapy. Nevertheless balloon dilatation is an alternative for patients who are at high risk or who are unwilling to undergo another operation.

Catheterization↗
PubMed1989

Pylorus-preserving Whipple pancreaticoduodenectomy: postoperative evaluation.

The pylorus-preserving Whipple pancreaticoduodenectomy is becoming a popular alternative to the standard Whipple operation. Fluoroscopy plays an important role in postoperative assessment. The authors evaluated images of 50 consecutive patients who had undergone the newer procedure. Thirty-one complications were identified. Two normal variants that could be confused with abnormalities were noted: (a) the featureless appearance of the duodenal bulb may be mistaken for extravasation, and (b) contrastmaterial filling of the proximal jejunal loop at an end-to-end anastomosis with retained invaginated pancreas may be mistaken for intussusception. Another pitfall was failure to evaluate the pancreaticojejunostomy anastomosis fully, resulting in false-negative radiologic interpretations when leaks were present. The approach to postoperative examination of patients who have undergone the pylorus-preserving Whipple procedure is different from that of patients who have undergone the standard procedure. Radiologists should be familiar with this approach, the normal postoperative anatomy, and pitfalls in imaging so that complications can be diagnosed and treated.

Adult↗
PubMed1989

Circadian rhythm of oxytocin in the cerebrospinal fluid of rhesus and cynomolgus monkeys: effects of castration and adrenalectomy and presence of a caudal-rostral gradient.

Oxytocin and vasopressin (AVP) were previously reported to have a diurnal rhythm in cerebrospinal fluid (CSF) collected from the cervical cistern of chaired, intact male rhesus monkeys. In the present study, we continuously sampled CSF from temporary indwelling catheters placed in the spinal subarachnoid space of unanesthetized monkeys maintained on tether and swivel systems. CSF was collected from intact and castrate female rhesus monkeys and intact female and castrate, adrenalectomized male cynomolgus monkeys to determine if oxytocin and AVP rhythms are expressed in spinal subarachnoid CSF, if the magnitude of the CSF rhythm displays a rostral-caudal gradient, and if the rhythm is present in adrenalectomized and castrate monkeys, or is specific to the sex or species of macaque. Monkeys, maintained on a 12-hour light/dark cycle with lights on from 06.00 to 18.00 h, had 19-gauge epidural catheters introduced at the L4-L5 intervertebral space and advanced cephalad in the subarachnoid space. The proximal end of the catheter was connected to a peristaltic pump for continuous removal of CSF (0.5 ml/h) and hourly CSF samples were radioimmunoassayed for oxytocin and AVP. For rostral-caudal studies, the distal tip of the catheter was repositioned every few days to collect CSF from 3 levels of the spinal subarachnoid space: C5-6, T5-6, T12-L1. Each animal had a diurnal CSF oxytocin rhythm with peak and trough oxytocin levels during early light and dark periods, respectively. The magnitude of the oxytocin rhythm differed among animals, but was consistent in an animal from day to day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗
PubMed1989

Total parenteral nutrition and alternate energy substrates in treatment of severe acute pancreatitis.

The use of total parenteral nutrition (TPN) in the treatment of 73 patients with acute severe pancreatitis was prospectively studied during a two year period. Patients were divided into three groups on the basis of calorie substrate used. Glucose and twice weekly lipid infusion (glucose based) were used in 60 per cent; 27 per cent required daily lipid infusion (lipid based), and 13 per cent received no lipid because of pre-existing hyperlipemia or thrombocytopenia (no lipid). Nutritional indices (albumin, transferrin and total lymphocyte count) were initially abnormal in more than 80 per cent of patients, and 50 per cent had three or more of Ranson's criteria. After TPN, 81 per cent had improved nutritional indices, and none had hypertriglyceridemia or aggravation of pancreatitis develop. Patients who received lipid based or no lipid had higher insulin requirements (p less than 0.01) than those receiving mainly glucose. Mortality was increased tenfold (2.5 versus 21.4 per cent, p less than 0.01) in patients who did not achieve positive nitrogen balance. We conclude that TPN, either lipid or glucose based, is a safe and effective therapy to reverse the malnutrition of acute pancreatitis and that failure to achieve positive nitrogen balance is associated with increased mortality.

Acute Disease↗
PubMed1989

Current status of pancreaticoduodenectomy for periampullary carcinoma.

Pancreaticoduodenectomy has undergone numerous modifications since the original description by Whipple et al. of a successful two-stage radical resection of the head of the pancreas and duodenum in 1935. For most of the 50 years that the Whipple procedure has been performed, the morbidity and mortality rates have been high, and few long-term survivors have been reported. Over the past decade, a number of institutions have reported a dramatic decline in operative morbidity and mortality as well as an improved survival for those undergoing pancreaticoduodenal resection. Between 1969 and 1986, 88 patients underwent pancreaticoduodenal resection for periampullary cancer at the Johns Hopkins Hospital. In an effort to detect recent trends in operative morbidity and mortality for those undergoing pancreaticoduodenal resection, the patients were divided into two groups on the basis of two time periods. Forty-one patients underwent pancreaticoduodenectomy for periampullary cancer between 1969 and 1981, while 47 patients underwent pancreaticoduodenectomy between 1981 and 1986. There were no significant differences between the two groups in terms of mean age, sex distribution, duration of symptoms before presentation or mean weight loss. Likewise, preoperative laboratory data were similar for both groups of patients. In addition, mean tumor size was similar in both groups, as was the incidence of positive lymph nodes. Among the 41 patients operated upon during the first period, hospital morbidity and mortality rates were 59% and 24%, respectively. In contrast, hospital morbidity and mortality rates were 36% and 21%, respectively among the 47 patients operated upon during the recent period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1989

Acute cholecystitis occurring as a complication of percutaneous transhepatic drainage.

Sepsis is a common occurrence during long term transhepatic biliary drainage. Most of these episodes are attributed to cholangitis, are relatively minor and can be managed nonoperatively. During a 42 month period, nine patients who had sepsis develop after biliary drainage were found to have acute cholecystitis, a complication not previously noted after this procedure. Seven of the nine patients had an underlying malignant lesion, and three of these patients had undergone percutaneous biliary drainage for palliation of unresectable or metastatic tumor. Eight of the nine patients underwent cholecystectomy whereas percutaneous cholecystostomy was used in one patient with an unresectable cholangiocarcinoma. Operative and pathologic evidence of acute cholecystitis was present in all, but only two patients had gallstones. Seven patients survived the surgical procedure and were discharged at an average of 11.7 days postoperatively. Based on this series, we propose that acute cholecystitis should be considered as a source of sepsis in patients undergoing biliary drainage who do not respond to antibiotics and catheter manipulations. Moreover, cholecystectomy should be performed at the time of laparotomy, if prolonged transhepatic drainage is planned for unresectable malignant conditions.

Acute Disease↗
PubMed1988

Transhepatic venous collaterals in a patient with the Budd-Chiari syndrome.

A patient with large transhepatic venous collaterals between the right and middle hepatic veins bypassing a short inferior vena caval occlusion is described. Obstruction of the hepatic veins led to the development of the Budd-Chiari syndrome, ascites, and crural edema. A mesoatrial shunt was performed which resulted in complete recovery.

Adult↗