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Biomedical subjects

J L Cameron

Publications and source records attributed to J L Cameron.

At least 235 records · Page 13Linked to original sources
PubMed1986

Long-term patency of the mesocaval C shunt.

Reports of thrombosis rates as high as 40 percent with the mesocaval H shunt led us to review our results with the mesocaval C shunt in 33 consecutive patients. Their ages ranged from 23 to 69 years (mean 50 +/- 12 years). There were 21 male and 12 female patients. The causes of portal hypertension included alcoholic cirrhosis in 13 patients, primary biliary cirrhosis in 6 patients, postnecrotic cirrhosis in 6 patients, cryptogenic cirrhosis in 3 patients, the Budd-Chiari syndrome in 4 patients, and portal vein thrombosis in 1 patient. Twelve patients were in Child's class A, 8 were in Child's class B, and 13 were in Child's class C. Operative mortality was 24 percent (8 of 33 patients) but occurred only in class C patients under nonelective conditions. Shunt patency was determined by one or more of the following: autopsy, angiography, and a lack of recurrent varices or hemorrhage. Autopsies were performed in 12 patients from 1 week to 72 months after operation. All 12 C shunts were widely patent. Angiography was performed in 13 patients from 1 to 38 months postoperatively. All 13 C shunts were patent; however, 2 eventually stenosed and attempts at ballon angioplasty were only moderately successful. Follow-up to time of death or to date was possible in 24 of 25 survivors, and ranged from 3 to 123 months. Evidence of recurrent varices, variceal hemorrhage, or both developed in only two patients (2 of 24, 8 percent), both of whom had stenosed shunts.

Adult↗
PubMed1986

Bacterial contamination of ambulance oxygen humidifier water reservoirs: a potential source of pulmonary infection.

The risk and benefit of oxygen humidification during ambulance transport is unknown. We cultured the water in plastic multiple-use bottles of humidifiers on 30 randomly selected area ambulances during November 1985. There were 22 positive cultures. Potentially pathogenic bacteria (four Pseudomonas maltophilia, three Pseudomonas aeruginosa, one Klebsiella pneumoniae, and one Staphylococcus epidermidis) were found in nine samples. Assuming that the water in ambulance humidifiers should have been sterile, the findings are statistically significant (P less than .01). Because there is no evidence that humidification is of benefit for nonintubated patients receiving oxygen at flow rates of 4 L/min or less when environmental humidity is adequate, we suggest that such patients should receive oxygen without humidification during ambulance transport. All other patients requiring oxygen during ambulance transport should continue to receive humidified oxygen. If a multiple-use humidifier reservoir is to be used, a written policy for its use must be developed and there must be appropriate documentation of compliance with the policy. An alternative is to replace the multiple-use humidifier reservoir with single-use sterile disposable devices, which cost approximately $2.00 per unit.

Ambulances↗
PubMed1986

Experimental pancreatic allotransplantation in large animals. The role of donor kidney and cyclosporine in modifying rejection.

Experiments were carried out in outbred dogs and pigs to evaluate the relative immunogenicity of pancreatic islets and segmental pancreas grafts, and whether these could be ameliorated by transplanting a kidney simultaneously from the same donor animal. Various immunosuppressive regimens were also studied. Pancreatic islet allografts never normalized blood glucose in totally pancreatectomized recipients despite the use of cyclosporine (CsA) in high doses (40 mg/kg/day) and the simultaneous transplantation of a kidney from the same donor. These grafts which never "took" contrast sharply with the experience of pancreatic islet autografts prepared in the same way and inoculated into the spleen, which in all nine instances normalized blood glucose in pancreatectomized recipients. Segmental transplants were performed in swine with duct drainage into the jejunum. Totally pancreatectomized pigs died at 7.8 +/- 1.0 days. In recipients suppressed with low-dose azathioprine (Az) and prednisone (Pred) pancreas grafts alone were rejected in 12.9 +/- 10 days. Synchronous pancreas and kidney transplants treated similarly extended the mean survival of pancreatic grafts to 20 +/- 10 days--which, however, was not significant (P less than 0.1 greater than 0.05). Mean survival time of pancreatic grafts in recipients receiving CsA at 20 mg/kg/day and prednisone 1 mg/kg/day was 14 +/- 6.3 days. The combination of CsA 20 mg/kg/day, Az 2 mg/kg/day, and Pred 1 mg/kg/day prolonged the mean survival time to 39.8 +/- 22 days. These results allow us to conclude that: crude preparations of islet tissue invariably capable of normalizing blood sugar at day 4 when used as autografts failed to "take" despite the existence of alternative sources of antigen present in a well vascularized kidney from the same donor, and despite very high dosages of CsA; triple immunosuppressive therapy had synergistic effects on pancreatic allograft survival; and simultaneous transplantation of kidney and pancreas had little effect on survival times of the pancreas or the kidney.

Animals↗
PubMed1986

Inhibition of gonadotropin secretion in castrated male rhesus monkeys (Macaca mulatta) induced by dietary restriction: analogy with the prepubertal hiatus of gonadotropin release.

The purpose of this study was to examine further the notion that in higher primates, analogous neuroendocrine mechanisms may underlie the hiatus in LH and FSH secretion during prepubertal development and the suppression of gonadotropin release in adults during states of malnutrition. To this end, the metabolic sequelae and the gonadotropin response to restricted food intake (RFI) were determined in nine castrated male rhesus monkeys. The results obtained were then evaluated in light of current understanding of the neuroendocrine bases of the ontogeny of gonadotropin secretion in primates. A reduction in food intake from approximately 1150 Cal/day to approximately 200 Cal/day for 20-34 days resulted in declines in body weight and circulating LH and FSH concentrations. The reduction in body weight and the suppression of LH secretion were statistically significant (P less than 0.05). The decrease in gonadotropin secretion induced by RFI was fully restored by the chronic iv intermittent infusion of GnRH (0.1 microgram/min for 3 min every hour). These findings graphically demonstrate that RFI, or a sequelae of this nutritional perturbation, inhibits gonadotropin secretion, in the absence of feedback influences by gonadal hormones, by an action at a suprapituitary level that is mediated by interruption of intermittent hypothalamic GnRH discharge. The apparent arrest of the neural mechanism that governs the timing of intermittent GnRH discharge, the so-called GnRH pulse generator, was associated with decreases in plasma insulin (P = 0.078), T4 (P less than 0.05), and T3 (P less than 0.05) concentrations and with a significant (P less than 0.05) elevation in circulating cortisol levels. Although a general decrease in circulating amino acid levels was not observed during RFI, plasma glutamate concentrations were significantly (P less than 0.05) reduced by the nutritional perturbation. RFI resulted in unremarkable hypoglycemia. While the suppression of gonadotropin secretion in castrated male monkeys during RFI resembled, in certain aspects, the hiatus in gonadotropin secretion during prepubertal development, the endocrine and metabolic concomitants of these two physiological states exhibited important differences. Thus, the contemporary notion that the study of dietary restriction in adult primates may provide insights into the neuroendocrine mechanisms that govern the timing of the onset of puberty in these species should not be accepted without careful consideration.

Amino Acids↗
PubMed1986

Effects of cysteamine administration on the in vivo incorporation of [35S]cysteine into somatostatin-14, somatostatin-28, arginine vasopressin, and oxytocin in rat hypothalamus.

The effect of cysteamine injection on the in vivo incorporation of [35S]cysteine into somatostatin-14 (SRIF-14), SRIF-28, arginine vasopressin (AVP), and oxytocin (OXT) in rat hypothalamus was studied. [35S]Cysteine was injected into the third ventricle 1 h, 4 h, or 1 week after cysteamine (300 mg/kg, sc) injection; animals were killed 4 h later. The drug was found to substantially reduce immunoreactive SRIF levels, but not OXT or AVP, 4 h after its injection. Cysteamine also caused large reductions in label incorporation into SRIF-14, SRIF-28, and OXT 1 and 4 h after drug injection. However, [35S]cysteine incorporation into AVP was increased substantially at these time points, while that into acid-precipitable protein was normal. One week after cysteamine injection, label incorporation into all hypothalamic peptides was normal. Cysteine specific activity was also measured after [35S]cysteine injection and was found to be similar in treatment and control groups. The results suggest that cysteamine inhibits the syntheses of SRIF-14, SRIF-28, and OXT and stimulates that of AVP.

Animals↗
PubMed1986

Small-bowel diverticulitis: CT findings.

Three patients with subsequently proven small-bowel diverticulitis were studied with preoperative CT. In all three cases, an inflammatory mass was present, two involving the terminal ileum and cecum and one involving the jejunum. While the findings in the two cases of ileal diverticulitis simulated appendicitis, in the case of jejunal diverticulitis the diagnosis was suggested on the basis of CT findings. Small-bowel diverticulitis should be included in the differential diagnosis if an inflammatory mass involving the small bowel is demonstrated on CT.

Aged↗
PubMed1986

Prospective, randomized trial of nasogastric suction in patients with acute pancreatitis.

The efficacy of nasogastric (NG) suction was evaluated in a prospective, randomized trial in 60 patients with acute pancreatitis of mild to moderate severity. Group I, NG (29 patients) was treated with NG suction, and group II, no NG (31 patients) was treated without NG suction. The presentation, cause of pancreatitis, and clinical parameters at the time of admission of the two groups were similar. The use of NG suction had no discernible benefit during hospitalization. There were no differences in duration of abdominal pain, the interval until bowel sounds returned, the need for narcotic administration, or the length of time intravenous fluid therapy was needed. When compared with group II, no NG, patients in group I, NG tended to resume oral intake later (5.0 +/- 0.3 versus 3.9 +/- 0.5 days) and remain hospitalized longer (13.1 +/- 2.6 versus 10.7 +/- 2.0 days). The incidence of serious complications, such as pancreatic abscess, pseudocyst, biliary obstruction, or pulmonary failure, was no different between the groups. This study demonstrates that the routine use of NG suction in patients with acute pancreatitis of mild to moderate severity is of no benefit in altering the clinical course.

Acute Disease↗
PubMed1986

Oxygen-derived free radicals and acute pancreatitis: a review.

The role of oxygen-derived free radicals in the pathogenesis of acute pancreatitis has been investigated in a series of studies using an ex vivo, perfused canine pancreas preparation. Three models of experimental acute pancreatitis have been developed in this preparation: ischemic pancreatitis, gallstone pancreatitis, and alcohol-induced pancreatitis. In each model, the pancreas becomes edematous, gains weight, and the perfusate develops hyperamylasemia during the 4 hour period of perfusion. Pretreatment with the free radical scavengers superoxide dismutase and catalase significantly ameliorates these manifestations of pancreatic injury in each of the three models. The source of the free radical generation was investigated by pretreating the preparation with allopurinol, a quite specific inhibitor of xanthine oxidase. In each of the three models, this also significantly ameliorated the injury process. These experiments demonstrate that oxygen-derived free radicals, generated by activated xanthine oxidase, appear to play a central role in the pathogenesis of acute pancreatitis in these models. These findings shed light on the fundamental pathophysiology of this disease and may provide the basis for more effective therapy in the future.

Acute Disease↗
PubMed1986

Pancreatitis or duodenal perforation after peri-Vaterian therapeutic endoscopic procedures: diagnosis, differentiation, and management.

The diagnosis, differentiation, and management of severe pancreaticoduodenal complications occurring after therapeutic endoscopic sphincterotomy and related procedures on the ampulla of Vater were reviewed for 254 patients. Five patients had duodenal (peri-Vaterian) perforation and six patients had clinically significant pancreatitis. Most patients were not suspected of having a significant complication the night of the procedure despite abdominal pain. Computer tomography proved to be the most accurate test for establishing the existence of a significant complication. A periduodenal collection of fluid (abscess) without significant pancreatic enlargement was the predominant complication in patients with duodenal perforation. In patients who had pancreatitis after peri-Vaterian procedures, generalized pancreatic enlargement and peripancreatic edema were most prominent. Four of the five patients with duodenal perforation required surgical drainage; all recovered. In contrast, four of the six patients with pancreatitis had medical therapy. One patient with pancreatitis died after multiple pancreatitic debridements were done. A second patient with pancreatitis who underwent exploration eventually recovered. Pancreaticoduodenal complications after therapeutic endoscopic sphincterotomy and related procedures are difficult to diagnose early; they should be suspected early and approached aggressively to limit morbidity and death.

Ampulla of Vater↗
PubMed1985

Experimental ischemic pancreatitis: treatment with albumin.

Acute pancreatitis was initiated in the isolated ex vivo, perfused canine pancreas preparation by exposing the gland to a 2 hour period of ischemia before a 4 hour perfusion period. The pancreatitis was manifested by edema formation, weight gain, and hyperamylasemia. When the osmotically active agent albumin was added to the perfusate at the end of the ischemic period, virtually no edema developed, weight gain was minimal, and the amylase level remained within normal limits during the subsequent 4 hour perfusion period. This suggests that a change in capillary permeability may be an early step in the pathogenesis of ischemia-induced pancreatitis in this experimental model.

Acute Disease↗
PubMed1985

Barrett's esophagus: its prevalence and association with adenocarcinoma in patients with symptoms of gastroesophageal reflux.

The pathologic reports of all 1,020 esophageal biopsy specimens obtained between 1975 and 1981 in patients with symptoms of gastroesophageal reflux were reviewed. Barrett's esophagus was identified in 84 patients (8 percent). The 362 patients seen between 1980 and 1981 were reviewed in detail. The symptoms in patients with Barrett's esophagus differed from those of the patients without Barrett's esophagus. Dysphagia was more often present in the former group (34 percent versus 16 percent, p less than 0.05) and epigastric distress was less frequent (11 percent versus 27 percent, p less than 0.05). Objective findings of hiatal hernia, esophageal stricture, and esophageal ulcers occurred more commonly in patients with Barrett's esophagus than in those without Barrett's esophagus (70 percent versus 48 percent, 31 percent versus 4 percent, and 14 percent versus 6 percent, respectively, p less than 0.05). Mid esophageal strictures were associated almost exclusively with Barrett's esophagus (five of six patients). At esophagoscopy, erythema was seen more commonly with Barrett's esophagus. The diagnosis was suspected by the endoscopist in only 34 percent of patients subsequently demonstrated histopathologically to have Barrett's esophagus. There was no significant difference in the prevalence of a positive Bernstein test result or gastroesophageal reflux on upper gastrointestinal series in patients with and without Barrett's esophagus. However, a hypotensive lower esophageal sphincter was found more commonly in patients with Barrett's esophagus (100 percent versus 53 percent, p less than 0.05). Thirteen of the 84 patients with Barrett's esophagus (15 percent) had a coexistent adenocarcinoma arising from Barrett's mucosa. These patients, when compared with the patients with Barrett's esophagus without carcinoma, were more often male (77 percent versus 51 percent, p = 0.1), more often had dysphagia (69 percent versus 34 percent, p less than 0.05), and more frequently had a comparatively short duration of symptoms (67 percent versus 36 percent, p less than 0.05). Our findings suggest that patients with Barrett's esophagus have a high risk of development of carcinoma. Because the entity is often not recognized at endoscopy, routine esophageal biopsy should be performed on all patients undergoing esophagoscopy for symptoms of gastroesophageal reflux. Patients with known Barrett's esophagus should be followed closely with repeated endoscopy and biopsy.

Adenocarcinoma↗
PubMed1985

Follicle-stimulating hormone within and secreted from anterior pituitaries of female golden hamsters during the estrous cycle and after ovariectomy.

Anterior pituitary (AP) glands were removed from groups of female golden hamsters at 0900 h on estrus (E), diestrus I (DI), and diestrus II (DII) and at 1200 h and 1500 h on proestrus (P12 and P15), as well as at 0900 h from ovariectomized hamsters (OVX). Hemipituitaries were incubated in culture medium with or without 10(-8) M luteinizing hormone-releasing hormone (LHRH) for 3 h at 37 degrees C to determine the magnitude of basal and LHRH-stimulated follicle-stimulating hormone (FSH) release. All samples were assessed for FSH activity by radioimmunoassay and radioreceptor assay. In a second set of experiments, AP were removed from E, DII, and OVX hamsters and bisected. One hemipituitary was homogenized in 10 mM Tris-HCl and the other half was incubated for 3 h. Follicle-stimulating hormone forms present within pituitary extracts or secreted into medium were separated by an isoelectric focusing technique, chromatofocusing. Basal FSH release was lowest in AP collected on DII and P12, higher in AP collected on E and DI, and highest in AP from OVX. Luteinizing hormone-releasing hormone-stimulated release of FSH was highest in AP obtained on DII and P12, lower in AP collected on E and DI, and lowest in AP from OVX. Radio-receptor-to-radioimmunoassay ratio of secreted FSH was greatest when basal FSH secretion was low and LHRH sensitivity was high (DII and P12) and least when basal FSH secretion was high and LHRH sensitivity low (E and after OVX).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

The role of endogenous gonadotropin-releasing hormone in the control of luteinizing hormone and testosterone secretion in the juvenile male monkey, Macaca fascicularis.

To determine what changes occur in the activity of gonadotropin-releasing hormone (GnRH) neurons during pubertal development in primate species we tested the hypotheses that there are morphologic differences between GnRH-containing neurons in juvenile versus adult monkeys, and the low activity of the reproductive axis is governed by hypothalamic GnRH release in monkeys prior to puberty. We removed the brains from 5 juvenile and 5 adult male monkeys (Macaca fascicularis) and blocked, sectioned, and prepared each hypothalamus for light microscopic immunocytochemistry for GnRH-containing cells. The distribution and number of GnRH-containing neurons were similar in adult and juvenile brains; however, GnRH-containing perikarya in adult brains were significantly larger in total cross-sectional area (200 +/- 12 vs. 169 +/- 8 micron 2, P less than 0.05) and in cross-sectional area of the cytoplasm (139 +/- 2 vs. 88 +/- 6 micron 2, P less than 0.05) than in juvenile brains. In another group of 10 juvenile male macaques, we administered an antiserum to GnRH (Fraser #94; 2 ml/kg, i.v.) and monitored the effects on plasma luteinizing hormone (LH) and testosterone concentrations. The percentage of plasma samples with detectable LH levels decreased significantly (from 26.67 +/- 8.3% to 5.3 +/- 3.4%, P less than 0.05) after GnRH antiserum administration; however, plasma testosterone concentrations (0.08 +/- 0.02 ng/ml) remained unchanged. We conclude that during pubertal maturation in primate species there is increased synthesis and release of GnRH from a population of GnRH neurons that are active prior to puberty.

Animals↗
PubMed1985

The pathogenesis of acute pancreatitis. The source and role of oxygen-derived free radicals in three different experimental models.

Recent experimental work has suggested that oxygen-derived free radicals may play an important role in initiating the early capillary injury in acute pancreatitis. Data from models of ischemic injury in other organs have suggested the enzyme xanthine oxidase is important in generating oxygen-derived free radicals. The present study was performed to determine whether xanthine oxidase is the source of free radical production in experimental pancreatitis. Utilizing the isolated, perfused, ex vivo canine pancreas preparation, three models of pancreatitis were initiated with (1) free fatty acid infusion (FFA), (2) partial duct obstruction and secretin stimulation (POSS), and (3) ischemia (ISCH). In each model, during a 4-hour perfusion, edema developed, weight gain occurred (FFA 120.6 +/- 21.1 gm; POSS 44.5 +/- 6.9 gm; ISCH 63.3 +/- 14.0 gm), and the serum amylase became elevated (FFA 1827 +/- 397 u/dl; POSS 10,171 +/- 1487 u/dl; ISCH 1860 +/- 365 u/dl). When the xanthine oxidase enzyme inhibitor allopurinol was added to the perfusate prior to the 4-hour perfusion, edema formation was absent or minimal, weight gain was significantly less (FFA 15.2 +/- 2.5 gm p less than 0.05; POSS 8.8 +/- 2.7 gm p less than 0.001; ISCH 12.3 +/- 2.8 gm p less than 0.01), and the amylase remained normal or the elevation was significantly decreased (FFA 996 +/- 189 u/dl p less than 0.05; POSS 3021 +/- 1074 u/dl p less than 0.001; ISCH 993 +/- 214 u/dl p less than 0.002). These data confirm that oxygen-derived free radicals play an important role in the pathogenesis of experimental acute pancreatitis, and suggest that the enzyme xanthine oxidase may well be the source of their production.

Acute Disease↗
PubMed1985

Nonoperative management of benign postoperative biliary strictures.

Selected benign biliary strictures can be treated safely and successfully by percutaneous balloon dilatation. Primary biliary strictures appear to be less responsive to balloon dilatation alone and require stenting with large catheters (16-20 F) for several months to permit scarring around the catheter. A long period of healing around such a large-bore stent is crucial to the success of such treatment. The most important physiologic indicators for successful dilatation are a long period of stricture challenge with a catheter placed proximal to the dilated segment to allow bile to drain internally across the previously strictured segment, and a near anatomic result as demonstrated by cholangiogram.

Adolescent↗
PubMed1985

Metabolic changes during maturation of male monkeys: possible signals for onset of puberty.

There is a close relationship between the metabolic status of a maturing animal and the timing of puberty onset. However, the signals linking metabolic status to the maturation of the reproductive axis remain unknown. We looked for metabolic differences before and after puberty by comparing plasma profiles of insulin, glucose, amino acids, beta-hydroxybutyrate, and glycerol between juvenile and adult monkeys in fed and fasted states. Thirteen juvenile and 13 adult male crab-eating macaques (Macaca fascicularis) were fed a mixed meal, and blood samples were collected at intervals between 1.5 and 52 h after the meal. Plasma insulin concentrations decreased in a similar manner in both groups during the first 16 h of fasting. By 20 h after a meal, basal insulin levels were significantly lower (P less than 0.025) in juveniles compared with adults and remained so until the end of the fast. Circulating levels of glucose were similar in juveniles and adults immediately after a meal and then decreased significantly (P less than 0.025) in juveniles by 28 h of fasting and in adults by 52 h of fasting. Plasma concentrations of all large neutral amino acids (i.e., tyrosine, tryptophan, phenylalanine, valine, leucine, and isoleucine, LNAA) except tryptophan decreased more precipitously in juveniles than in adults during the first 20 h of fasting. However, the ratios of tyrosine to other LNAA and tryptophan to other LNAA were similar in juveniles and adults at all times. beta-Hydroxybutyrate concentrations were low in both groups until 24 h after a meal, at which time plasma levels increased more rapidly and attained higher values in juveniles compared with adults.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1985

Percutaneous transhepatic biliary drainage for bile leaks and fistulas.

Percutaneous transhepatic cholangiography and biliary drainage were performed in 12 patients with major injuries to the bile ducts manifested by biliary leaks and fistulas. Eleven of the 12 patients had had inadvertent biliary trauma during surgery. In six patients, the biliary leaks sealed with percutaneous drainage. In other patients requiring definitive surgical procedures on the biliary tract, initial percutaneous drainage allowed these procedures to be delayed until the patients' clinical condition improved. Percutaneous biliary drainage is an important adjunct to the management of patients with traumatic extravasation of bile into the peritoneal cavity or biliary-cutaneous fistula.

Abscess↗