PubMed Health⌕ Search

Biomedical subjects

J D Elashoff

Publications and source records attributed to J D Elashoff.

At least 19 recordsLinked to original sources
PubMed1995

Bronchiolitis obliterans in single-lung transplant recipients.

The presentation and clinical course of bronchiolitis obliterans (BO) in single-lung transplant (SLT) recipients has thus far not been well described. We retrospectively analyzed the serial spirometry of 15 SLT patients with BO. All the patients fulfilled the criteria for BO syndrome, and 11 of the 15 had histologically documented BO. Based on serial FEV1 analysis, we identified three patterns of presentation and progression of BO. The first pattern (n = 6) was characterized by a rapid onset and a relentless progressive course; the second pattern (n = 5) was characterized by a similar rapid onset and initial rapid decline, but was followed by stabilization in lung function; the third pattern (n = 4) was characterized by an insidious onset and course. In all patients, a permanent reduction in the mean forced expiratory flow during the middle half of the forced vital capacity appeared to be an early sensitive index for the development of BO. An appreciation of these different modes of presentation and progression of BO is potentially important in the assessment of prognosis and management of the SLT recipient.

Adult↗
PubMed1994

Disproportionate ileal digestion on canine food consumption. A possible model for satiety in pancreatic insufficiency.

In animals, ileal sensors of nutrients signal satiety more potently than similar sensors in jejunum. We postulated that inadequate food intake and weight loss in human pancreatic insufficiency might arise by the displacement of digestion to ileum, where excessive release of digestive products would enhance satiety. To test this idea, we studied dogs prepared with pancreatic fistulas, which allowed reversible switching of pancreatic juice from entry at duodenum to entry at mid-small intestine. Dogs were studied in a crossover design over successive eight-day periods. Food consumption and body weight were measured while the dogs had continuous access to food. Diversion of pancreatic juice to mid-intestine significantly (P < 0.01) depressed food intake by an average of 28%. Diversion also significantly (P < 0.01) reduced body weight. The findings support the idea that insufficient food intake in human pancreatic insufficiency may result from stimulation of ileal satiety mechanisms.

Animals↗
PubMed1994

Stimulation of duodenal motility by hyperosmolar mannitol depends on local osmoreceptor control.

Duodenal motility is stimulated by hyperosmolar solution. Since intestinal distension also stimulates intestinal motility, this increase in the motility response may be due to either stimulation of duodenal local osmoreceptor control or intestinal distension resulting from osmotic equilibration. To test which mechanism is primarily responsible for this osmotically sensitive effect, we compared the number of duodenal spike bursts in five dogs equipped with duodenal fistulas that allowed for the preservation or removal of intestinal distension. The response to 300 vs. 1,200 mosM mannitol was compared under three experimental perfusion methods: 1) distension was preserved both proximal and distal to the fistula (DD); 2) distension proximal to the fistula was removed (rD); and 3) distension both proximal and distal to the fistula was removed (rr). The test solutions had access to either the whole gut (DD and rD) or only the first 10 cm of the duodenum (rr). We found that 1) there were more spike bursts after the hyperosmolar solution (dose effect, P < 0.05, analysis of variance); 2) there was no significant difference between the three experimental methods; and 3) the stimulating effect of hyperosmolar solution depended on the first 10 cm of the duodenum. Thus, since hyperosmolar solution increased duodenal motility regardless of whether intestinal distension was preserved or removed, the stimulating effect of hyperosmolar solution on duodenal motility was primarily the result of a local osmoreceptor control mechanism located in the first 10 cm of the duodenum.

Analysis of Variance↗
PubMed1994

Control of canine gastric emptying of fat by lipolytic products.

Dietary fat is ingested in three forms: 1) in solid food, 2) as aqueous emulsions, and 3) as unemulsified, liquid oil. On the basis of a scant previous literature, we postulated that liquid fat (emulsions or oils) would empty from the stomach at speeds that varied with the amounts ingested but that this dynamic would be modulated by feedback inhibition from lipolytic products. To test these ideas, we used a gamma camera to track gastric emptying of 123I-labeled fat in dogs with chronic pancreatic fistulas by which lipase was excluded from or replenished in the duodenum in varied amounts after dogs were fed 15-, 30-, and 60-g loads of liquid fat given with solid foods or as emulsions. We also tracked concurrent gastric emptying of 113mIn, which marked the solid food phase or the water phase of emulsions. In some studies, we used a potent and specific inhibitor (orlistat) of pancreatic and gastric lipases to assess how lipolytic products modulated emptying of liquid fat. In the absence of pancreatic enzymes, both oils and emulsions emptied initially at high speeds that varied with fat loads, but emptying slowed 20 min after ingestion of emulsions and 60 min after ingestion of unemulsified oil. Studies with orlistat indicated that these changes in rates resulted from liberation of gastric lipolytic products. Emptying of oil emulsions was not altered by duodenal replenishment with pancreatic enzymes, but emptying of unemulsified oil was inhibited in a dose-related fashion, such that maximal inhibition was achieved when pancreatic enzymes were replenished at > or = 40% of normal amounts. Studies with orlistat confirmed that this dose-dependent slowing was due specifically to lipase. Emptying of solid food was much more sensitive to replenishment with enzymes, so that a 10% replenishment maximally inhibited solid emptying.

Animals↗
PubMed1994

The relationship between oxygen consumption and work rate in patients with airflow obstruction.

The oxygen cost of augmented ventilation is increased in patients with chronic obstructive pulmonary disease, either at rest or during exercise. Thus, if excessive demands are placed on the respiratory muscles during exercise in these patients, we postulate that the total oxygen consumption (VO2) may increase relative to the work rate compared to control subjects. The aim of this study was to examine the relationship between VO2 and work rate during exercise in patients with airflow obstruction. A retrospective analysis of data collected over 7 years was conducted. Patients with airflow obstruction (n = 131) were compared and contrasted with those in whom pulmonary function studies (spirometry, lung volumes) were normal (n = 199). Severity of airflow obstruction (ie, mild moderate, severe) was determined, using the 95 percent confidence limits for the ratio of FEV1 to FVC. Incremental exercise studies were performed on a cycle ergometer. Resting VO2 was not significantly different across the groups with airflow obstruction measured either directly or normalized for body weight. The VO2max was significantly reduced in the patients with severe airflow obstruction, compared with the normal group, as well as the patients with mild and moderate airflow obstruction. No differences were noted in the slope of VO2 plotted against work rate in the patients with airflow obstruction (regardless of the severity of the obstruction) and individuals in whom results of pulmonary function tests were normal. In addition, when gender was taken into account, there was essentially no difference in the slopes for either male or female subjects across all groups. Stepwise, linear regression failed to demonstrate any variable or variables that were strongly related to slope. We postulate that the maintenance of a normal slope of VO2 on work rate in patients with airflow obstruction, in whom the oxygen cost and work of breathing is likely increased, may mask a significant reduction in nonrespiratory VO2 (for example, to exercising skeletal muscles).

Aged↗
PubMed1993

Nutrient feedback inhibition of gastric emptying plays a larger role than osmotically dependent duodenal resistance.

The slowing of gastric emptying by hyperosmolar solutions has been postulated to result from the triggering of duodenal osmoreceptor feedback on the stomach. We tested the idea that the inhibition of gastric emptying by a hyperosmolar solution depended on the duodenal resistance and the triggering of nutrient-specific feedback by tracking gastric emptying of 300 and 1,200 mosmol/kgH2O test solutions in 12 dogs in which duodenal resistance was either removed (by temporarily diverting chyme from uncorked duodenal fistula) or preserved (by keeping duodenal fistula corked). Mannitol was used to test osmolality alone, and glucose was used to examine the combined effects of osmolality and nutrient-specific inhibitory feedback. We found that: 1) the slowing effect of hyperosmolality was more marked with the duodenal resistance preserved (P < 0.05; analysis of variance), 2) the slowing effect of glucose was greater than that of mannitol for all conditions (P = 0.01; analysis of variance), and 3) the inhibitory effect of mannitol was localized to the duodenum. We conclude that inhibition of gastric emptying by hyperosmolar mannitol depended primarily on duodenal resistance, while the inhibitory effect of hyperosmolar glucose depended on nutrient-specific feedback on the stomach more than duodenal resistance.

Animal Nutritional Physiological Phenomena↗
PubMed1993

Prediction of maximal exercise capacity in obstructive and restrictive pulmonary disease.

We evaluated the predictive value of resting pulmonary function tests (PFTs) in the determination of maximal exercise capacity in patients with obstructive and restrictive ventilatory disease. We performed resting PFTs and an incremental exercise study on a bicycle ergometer in 146 patients with chronic obstructive pulmonary disease (COPD) and 68 patients with restrictive disease. The patients with obstructive disease were further subdivided into mild, moderate, and severe based on the severity of their airway obstruction (mean +/- SD:FEV1, 2.78 +/- 0.77, 2.12 +/- 0.74, and 1.06 +/- 0.47, respectively). Correlation coefficients for PFTs vs VO2max and VEmax in restricted patients was generally low (DL = 0.67 and 0.34, IC = 0.58 and 0.35, FVC = 0.57 and 0.35, TLC = 0.35 and 0.18). In patients with COPD, the maximum voluntary ventilation (MVV) was the single best predictor of VO2 in all groups with correlation coefficients of 0.75, 0.69, and 0.89 in the mild, moderate, and severe subgroups, respectively. Similarly, the MVV was the best predictor of VEmax in all groups with correlation coefficients of 0.59, 0.64, and 0.89 in the three subgroups. The correlation with FEV1 was slightly less for both VO2max (0.69, 0.65, and 0.87) and VEmax (0.52, 0.64, 0.64) in the mild, moderate, and severe subgroups, respectively. Our findings show that PFTs are unreliable in predicting VEmax and VO2max in restricted patients. In patients with obstruction, the MVV is the single best predictor of VO2max and VEmax in all three categories, but was not significantly improved by stepwise multiple regression with additional PFT variables. Higher correlations were obtained in the severe group in whom the correlation with VO2max and VEmax was 0.89. However, the 95 percent confidence interval of the estimate for VO2 and VE was relatively large (+/- 0.16 L/min and +/- 6.6 L/min, respectively). We conclude that although several PFTs correlate significantly with maximum exercise, the large variance precludes their use to accurately predict maximum performance in individual patients with COPD.

Aged↗
PubMed1992

Gastric emptying of solid food is most potently inhibited by carbohydrate in the canine distal ileum.

Although glucose sensors regulating the gastric emptying of liquid meals are uniformly distributed throughout the canine small intestine, some data suggest that the distal small bowel more potently inhibits gastric emptying of solid foods. The aims of this study were to compare (a) the inhibition of gastric emptying by glucose sensors in the proximal intestine with the feedback from the distal intestine, (b) these effects on the gastric emptying of solids vs. liquids, and (c) the inhibitory effect of unhydrolyzed starch with glucose. In 7 dogs with chronic duodenal fistulas, the second, third, and fourth quarters of small bowel were perfused via chronically implanted transmural catheters. Gastric emptying of either solids or liquids was tracked by gamma camera while gastric output was diverted out the duodenal fistula and the small bowel perfused with test solutions of glucose (0.06-2.0 mol/L), 0.15 mol/L NaCl, or 8.5% soluble starch. It was found that (a) gastric emptying of solids but not liquids was approximately 3 times more potently inhibited by glucose in the fourth quarter vs. the first or second quarter of small bowel, and (b) only hydrolyzed starch inhibited gastric emptying of solids.

Analysis of Variance↗
PubMed1992

Noninvasive determinations of the anaerobic threshold. Reliability and validity in patients with COPD.

We compared the intraobserver and interobserver agreement of blood (BGT) and gas exchange (GET) methods for determination of the anaerobic threshold (AT) in patients with COPD. In addition, we determined the sensitivity and specificity of the gas exchange methods for determination of the AT. Two noninvasive methods, the V-slope (VS) and the ventilatory equivalents method (VEM) were compared with two blood sampling methods, the log standard HCO3 (SB) vs log VO2 (SBT) and base excess (BE) vs VO2 (BET). Twenty-nine patients with COPD (FEV1 < 60%) performed incremental exercise tests to exhaustion while breath-by-breath gas exchange measurements were made. Blood samples were drawn at the end of each minute for SB and BE. Two trained observers determined the VO2 at the threshold for each of the four indices on two separate occasions two weeks apart. Our results demonstrated the following: only modest interobserver and intraobserver agreement was noted by Spearman rank correlations; the VEM was as sensitive as the VS in COPD patients; and the presence of a true metabolic acidosis was not reliably predicted by GET methods. Moreover, although the blood methods accurately identified the presence of metabolic acidosis, there was disagreement on the actual point of the BGT. We conclude that gas exchange indices were not helpful for the determination of metabolic acidosis in patients with COPD.

Adult↗
PubMed1991

Effects of anabolic-androgenic steroids on muscular strength.

OBJECTIVE: To assess the effects of anabolic-androgenic steroids on human muscle strength. DATA SOURCES: A MEDLINE search for the period from January 1966 to April 1990, supplemented by manual searches of previous reviews, produced 30 studies in which subjects received more than one dose of the study steroid and in which changes in muscular strength were measured. STUDY SELECTION: Of the 30 studies, 14 were not included in the detailed data summary because they did not use a placebo control, did not randomize subjects to groups, or did not make objective strength measurements, or because percent change in strength data could not be abstracted. DATA EXTRACTION: Details of study design, reporting of results, and the adequacy and correctness of statistical methods were tabulated. Percent improvement in strength for the largest muscle group studied was computed, using the difference between results for the placebo and for the steroid-treated groups. DATA SYNTHESIS: Previously trained athletes show slightly greater improvements in strength in the anabolic-androgenic steroid-treated group than in the placebo group, with a median difference of 5% across the nine studies (range, 1.2% to 18.7%). A meta-analysis of the three studies with enough information to compute effect size showed a mean difference of 1.0 standard deviations (95% CI, 0.49 to 1.5). However, the poor overall quality of the studies in terms of design, sample size, and analysis; the lack of a dose-response effect across the narrow range of dosages tested; and the tendency for differences to be smaller in the larger studies throw these results into question. No evidence was found to support enhanced muscle strength with steroid use in eight studies in untrained normal volunteers. CONCLUSIONS: Anabolic steroids may slightly enhance muscle strength in previously trained athletes. No firm conclusion is possible concerning the efficacy of anabolic steroids in enhancing overall athletic performance. Results for the low steroid dosages studied in the published reports cannot be generalized to steroid-using athletes taking megadose regimens.

Anabolic Agents↗
PubMed1991

Power and validity of methods to identify variability genes.

A variability gene model [Magnus et al., Clin Genet 19:67-70, 1981] hypothesizes that environmental influences on the expression of additive genes for a quantitative trait such as cholesterol are under the control of alleles at a separate nonadditive locus. They suggest identifying such genes using an analysis of variance to compare absolute intrapair monozygotic twin trait differences between the genotypes of the postulated variability locus. However, quantitative traits such as cholesterol often have skewed distributions with a long right tail; what are the effects of such non-normality on the procedure suggested by Magnus et al. [1981]? We show that their method is a special case of the Levene tests, robust tests for variability differences. We introduce a statistical model representing sources of variability in twin pair differences and demonstrate with simulation studies that although the Levene tests have robust Type I error, power is enhanced when nonnormal data are transformed before analysis, and the apparent presence and degree of variability differences are dependent on the scale of analysis. These findings indicate the importance of appropriate transformation of the trait before analysis. Analysis of a well-characterized twin data set illustrates these conclusions.

Aged↗
PubMed1991

Precise gene dosage determination by polymerase chain reaction: theory, methodology, and statistical approach.

We developed a general method of quantifying relative copy numbers of specific DNA sequences based on the theoretical accumulation of polymerase chain reaction (PCR) products when two DNA sequences are amplified together (co-amplified). Our experiments illustrate the development and theory of the technique. The precision of our estimates is demonstrated by statistical confidence intervals. Tests for effects introduced by experimental factors were performed. The precision of the technique was established by examining the relative gene dosage of the X-linked dystrophin gene in human genomic DNAs from a male, a normal female, a 47,XXX female, and a 48,XXXX cell line. The sensitivity was sufficient to distinguish three copies of the gene from four copies; equivalent to detecting loss of heterozygosity in half the cells of a tumour. Confidence intervals allowed us to reject the hypothesis that there was no difference between DNA samples. Four sample pairs would be required to demonstrate relative gene dosage ratios of 2.0 to 1.0; eight sample pairs would be required to demonstrate a relative gene dosage ratio of 1.3 to 1.0. This method should be useful in detecting gene amplification and deletion in a variety of situations.

Base Sequence↗
PubMed1989

A randomized study of maintenance therapy with ranitidine to prevent the recurrence of duodenal ulcer.

After an active duodenal ulcer has healed in response to medical therapy, the rate of recurrence during the subsequent year is relatively high. We therefore enrolled 140 patients with healed duodenal ulcers in a two-year randomized, double-blind trial comparing maintenance therapy (ranitidine, 150 mg nightly) with placebo for the prevention of recurrent duodenal ulceration. We performed endoscopy annually and when symptoms suggested the recurrence of ulcers. Verified recurrent ulcers in either group were treated for four or eight weeks with open-label ranitidine (150 mg twice a day). Patients whose ulcers healed within eight weeks resumed randomized treatment. Prophylactic therapy with ranitidine reduced the rate of ulcer relapses from 63 percent in the placebo group to 37 percent in the ranitidine group (P less than 0.05). Treatment with ranitidine extended the median ulcer-free interval from one to two years (P less than 0.05). The first recurrences of ulcer were asymptomatic in half the ranitidine group and in a quarter of the placebo group. Prophylactic therapy with ranitidine also reduced the frequency of recurrent ulcers that were unhealed by eight weeks, that were bleeding, that were in the stomach, or that were the second recurrent ulcer within six months, from 43 percent in the placebo group to 21 percent. Patients who drank alcohol, smoked, had a history of ulcer disease, or had duodenal scarring or erosion at the time of entry into the study were at the greatest risk for recurrence and benefited the most from prophylactic ranitidine. We conclude that prophylactic treatment with ranitidine is effective in preventing the recurrence of duodenal ulceration.

Clinical Trials as Topic↗
PubMed1988

Designing a clinical trial to demonstrate prevention of ulcer recurrence: modelling simulation approaches.

We describe a Markov chain model for the ulcer recurrence and healing process, review the available literature to obtain appropriate parameter estimates, and use this model to evaluate alternative clinical trial designs. We focus on designs aimed at supporting recurrence prevention claims for a duodenal ulcer maintenance treatment. Our results show that a trial with endoscopies scheduled only at four month intervals is inadequate to support recurrence prevention claims; discrimination between the null and alternative hypotheses is impossible because of the size and direction of expected biases in observed recurrences. Our results suggest that endoscopy intervals should be at most four weeks to establish a claim of ulcer prevention.

Clinical Trials as Topic↗
PubMed1986

Carbamylcholine, but not somatostatin or neurotensin, stimulates prostaglandin E2 release from the isolated perfused rat stomach.

Prostaglandin E2 release by carbamylcholine (10(-6) M), somatostatin (10(-10)-10(-8) M) and neurotensin (10(-10) - 10(-8) M) has been evaluated in the isolated perfused rat stomach. Carbamylcholine significantly stimulated gastric PGE2 release and increased the perfusion pressure, whereas somatostatin and neurotensin had no effect. Combination of carbamylcholine with somatostatin or neurotensin produced no increase over that found with carbamylcholine alone. The relationship between perfusion-pressure and PGE2 release was not causal. The present findings do not support a role for prostaglandins in the mechanism of somatostatin or neurotensin action in the stomach.

Animals↗
PubMed1986

Sex and smoking differences in duodenal ulcer mortality.

Data from the US Census Bureau and the National Center for Health Statistics suggest that differences in male and female smoking habits between 1920 and 1980 may have contributed to changes in duodenal ulcer mortality sex ratios. An attributable risk analysis suggests that between 43 per cent and 63 per cent of duodenal ulcer mortality for males results from smoking; the comparable figures for females being between 25 per cent and 50 per cent.

Aged↗
PubMed1985

Sucralfate therapy in patients with symptoms of alkaline reflux gastritis. A randomized, double-blind study.

The effects of sucralfate (6 g per day) and placebo on symptoms, endoscopic findings, and gastric mucosal histology were compared in 23 patients with symptoms of alkaline reflux gastritis who had undergone Billroth I, Billroth II, or vagotomy and pyloroplasty. Patients were randomly assigned to receive sucralfate (n = 11) or placebo (n = 12) for six weeks. Then all received six weeks of open sucralfate therapy before treatment codes were revealed. Twelve gastric biopsy specimens were obtained before patients began treatment and at six and 12 weeks. The two groups did not differ significantly with respect to symptom scores or endoscopic findings at baseline, after the double-blind phase, or after open sucralfate treatment. There were also no significant differences between the treatment groups with respect to epithelial cell scores and conventional gastritis scores. However, after the six-week, double-blind phase, the inflammatory cell score of the sucralfate-treated group was significantly lower (p less than 0.05) than that of the placebo-treated group (1.3 +/- 0.3 versus 1.9 +/- 0.4). After six weeks of open sucralfate treatment, patients who had initially received placebo had a significant reduction (1.4 +/- 0.3 versus 1.9 +/- 0.4) in their inflammatory cell score. Sucralfate lowered the inflammatory cell scores of patients with symptoms of alkaline reflux gastritis. This reduction, however, was not associated with an improvement in symptoms.

Aluminum↗