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Biomedical subjects

B A Stewart

Publications and source records attributed to B A Stewart.

27 records · Page 2Linked to original sources
PubMed1990

The blind loop syndrome in children.

Anatomical abnormalities of the small bowel that cause intestinal stagnation result in bacterial overgrowth and a blind loop syndrome (BLS). Bacterial breakdown of bile salts and deamination of protein lead to malabsorption, steatorrhea, and fat-soluble vitamin deficiencies. Four children developed BLS as a complication of necrotizing enterocolitis, jejunal atresia, gastroschisis, and biliary atresia. BLS was suggested by abdominal pain, feculent vomiting, steatorrhea, and hypoalbuminemia. Dilated, stagnant bowel loops were demonstrated in each instance by upper gastrointestinal contrast study. Positive intestinal bacterial aspirates were confirmatory. Antibiotic treatment in two patients improved symptomatology but all children ultimately required surgery. Surgical procedures consisted of blind loop resection, intestinal plication, and catheterization of the bilioenteric conduit. All patients are now asymptomatic but one child suffers from parenteral nutrition-related cirrhosis and another requires chronic antibiotic therapy.

Bacterial Infections↗
PubMed1990

Biliary atresia registry, 1976 to 1989.

The Registry provides information about 904 children with biliary atresia from more than 100 institutions. There was a 1.4 to 1 female predominance; racial distribution was 62% caucasian, 20% black, 11% Hispanic, 4.2% asian, and 1.5% American Indian. Eight hundred sixteen (90%) underwent corrective surgery (median age at operation, 69 days). Intraoperatively, 70% had totally obliterated extrahepatic bile ducts, 22% had patency of the gallbladder and distal common duct, whereas only 8% had "correctable" biliary atresia (proximal duct patency). A variety of reconstructions were used, but the majority of patients had a Roux-en-Y portoenterostomy with or without exteriorization. Follow-up was available for 670 children (74%) with average length of follow-up of 5 years (range, 1 to 16 years). Five-year actuarial survival was 48% following Kasai's operation, but was less than 10% (at 3 years) if no operative correction was done. Survival was unaffected by sex, type of reconstruction, or cholangitis. Predictors of a bad outcome were (1) caucasian race; (2) operative age greater than 60 days; (3) presence of cirrhosis at initial biopsy; (4) totally nonpatent extrahepatic ducts; (5) absent ducts at the level of transection in the liver hilus; and (6) subsequent development of varices or ascites. Identification of factors predictive of the ultimate outcome provide a basis for either continued efforts with management of Kasai's operation or for early referral for liver transplantation.

Age Factors↗
PubMed1990

Congenital biliary tract disease.

Jaundice in the pediatric patient requires prompt and directed evaluation. This dictum is highlighted in infants with biliary atresia, in whom the progressive sclerosing process results in complete obliteration of patent but microscopic hilar biliary structures by 4 months of age. Kasai's operation, if done before that time, will re-establish bile drainage in 90% of infants. One fourth to one third of patients achieve long-term jaundice-free survival. Complications of cholangitis, portal hypertension, and fat malabsorption are experienced by many patients. In children with early or late operative failure, liver replacement now offers legitimate hope for extended survival. Choledochal cyst is a conglomerate of pancreaticobiliary anomalies consisting of a choledochal cyst, a common-channel-type pancreaticobiliary junction, intrahepatic cystic disease, and partial obstruction of the distal common bile duct. Many patients have one or more of these malformations. It is now widely accepted that the preferred treatment of choledochal cyst is total excision of the diseased biliary duct with reconstruction by Roux-en-Y choledochojejunostomy. "Internal" excision avoids injury to other structures in the hepatoduodenal ligament, particularly if pericystic inflammation is present. Congenital perforation of the common bile duct responds in most cases to simple peritoneal drainage of the perforation. Retention of the tube cholecystostomy is useful for subsequent cholangiographic follow-up. Tube cholecystostomy may also be useful for irrigation of the biliary tract in infants with inspissated bile syndrome.

Biliary Atresia↗
PubMed1988

Liver transplantation and the Kasai operation in biliary atresia.

To assess the respective morbidity of the Kasai operation and liver transplantation in treating biliary atresia from the perspective of the referring institution, we analyzed the clinical course of 43 consecutive patients hospitalized at our institution from October 1980 to December 1985. Morbidity was arbitrarily defined as complications that required hospitalization, cholangitis, rejection, and was calculated by dividing the actual days hospitalized by the days "at risk." Morbidity assigned to transplantation also included pretransplant hospitalizations necessitated for life-sustaining treatment after referral. The morbidity in 40 patients who were treated by the Kasai procedure was 16.1%, which could be broken down to 50.6% in those who died after operation, 17.4% in those patients subsequently referred for transplantation, and 10.2% in the 16 patients successfully treated. Thirteen of the latter have perfect or near perfect liver function and are in excellent health. The morbidity of the 17 patients who were referred for liver transplantation, including two referred immediately after initial exploration, was 16.0%, which could be broken down to 10.4% before transplantation and 49.8% afterwards. Seven patients died awaiting transplantation, all but one of whom were referred during the first year of life. The average time spent on the waiting list was 203 days. Biliary atresia remains a disease of high morbidity regardless of treatment. Continued hospitalizations are necessary for ongoing Kasai management and life-sustaining treatment following transplant referral. The time spent on transplant waiting lists is protracted, and many patients die before obtaining a new liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Biliary Atresia↗
PubMed1984

Degradation of crystalline ergocalciferol [vitamin D2, (3 beta,5Z,22E)-9,10-secoergosta-5,7,10(19),22-tetra en-3-ol].

The products of the degradation of crystalline ergocalciferol were investigated. These studies showed that numerous acidic and neutral oxidation products were formed resulting in the complete destruction of the triene functionality. Separation of the neutral products by preparative TLC led to material identified as the Windaus ketone IIa, 2,3,3a,4,5,6,7,7a beta-octahydro-7a alpha-methyl-1R-(1 alpha,1R,4R,5-trimethyl-2E-hexenyl)-4H-inden-4-one.

Chromatography, Thin Layer↗
PubMed1983

Wheat pasture poisoning. I. An evaluation of cereal pastures as related to tetany in beef cows.

Forage samples were obtained from three wheat and rye mixed pastures (replications) from December 1979, to April 1980 (140 d), while they were being grazed by mature cows at the Southwestern Livestock and Forage Research Station, El Reno, Oklahoma. These samples were taken three times during December, twice monthly in January and February and weekly in March and April. Samples were analyzed for dry matter, ash, N, K, Ca, Mg, P, ash alkalinity, aconitic, malic and citric acids, total lipids, NO3-N, Na and total nonstructural carbohydrates (TNC). In vitro digestibility was also determined. The N:TNC ratio, estimated plasma Mg levels and K:(Ca + Mg) ratio (tetany ratio) were calculated. On d 105 (March 19), 16% (five of 32 head) of the cows developed tetany. At tetany, the forage K, protein, digestibility, ash alkalinity, aconitic acid and total lipids increased suddenly and markedly. Forage dry matter, TNC and ash decreased. Forage Ca and Mg were slightly below or equal to the animals' requirements and remained relatively constant during the period of tetany. Forage P increased about 2 wk before tetany and decreased after tetany occurred. The levels of forage NO3-N and Na did not appear to be related to the incidence of tetany. The N:TNC ratios exceeded .4 immediately before tetany and two sampling periods thereafter. The estimated plasma Mg levels were lowest at tetany and shortly thereafter and tetany ratio exceeded 2.2 during most of the study, with peaks of 3.2 in December, at tetany and in early April.

Animals↗
PubMed1980

Formylation of glucose by cefamandole nafate at alkaline pH.

An increase in the hydrolysis rate of the formyl moiety of cefamandole nafate was observed when the commercial product was reconstituted in 5% dextrose in water relative to the rate when the formulation was dissolved in water for injection or in 0.9% saline. The increase in ester cleavage was the result of nucleophilic attack of glucose on the formyl ester moiety. This transesterification produced small amounts of D-glucose-6-formate and other D-glucose diformates. The formation of these products is of no clinical significance since the antibiotic potency and stability of cefamandole are unaffected and no toxicological differences were observed in animal studies or in clinical trials when formulated cefamandole nafate was administered with or without glucose.

Cefamandole↗
PubMedDate not supplied

Quantal measurement and analysis methods compared for crayfish and Drosophila neuromuscular junctions, and rat hippocampus.

Quantal content of transmission was estimated for three synaptic systems (crayfish and Drosophila neuromuscular junctions, and rat dentate gyrus neurons) with three different methods of measurement: direct counts of released quanta, amplitude measurements of evoked and spontaneous events, and charge measurements of evoked and spontaneous events. At the crayfish neuromuscular junction, comparison of the three methods showed that estimates from charge measurements were closer to estimates from direct counts, since amplitude measurements were more seriously affected by variable latency in evoked release of quantal units. Thus, charge measurements are better for estimating quantal content when direct counts cannot be made, as in crayfish at high frequency of stimulation or in the dentate gyrus neurons. At the Drosophila neuromuscular junction, there is almost no latency variation of quantal release in realistic physiological solutions, and the methods based upon amplitudes and charge give similar results. Distributions of evoked synaptic quantal events obtained by direct counts at the crayfish neuromuscular junction were compared to statistical distributions obtained by best fits. Binomial distributions with uniform or non-uniform probabilities of release generally provided good fits to the observations. From best fit distributions, the quantal parameters n (number of release sites) and p (their probability of release) can be calculated. We used two algorithms to estimate n and p: one allows for non-uniform probability of release and uses a modified chi-square (chi 2) criterion, and the second assumes uniform probability of release and derives parameters from maximum likelihood estimation (MLE). The bootstrap estimate of standard errors is used to determine the accuracy of n and p estimates.

Animals↗