Biomedical subjects

J Elashoff

Publications and source records attributed to J Elashoff.

At least 19 recordsLinked to original sources

PubMed1998

Accuracy of ultrasonic pachymetry and videokeratography in detecting keratoconus.

PURPOSE: To compare the accuracy of ultrasonic pachymetry measurements and videokeratography-derived indices in distinguishing keratoconus patients from those with normal eyes. SETTING: A subspecialty cornea practice (Los Angeles, California, USA) and the Keratoconus Genetics Research Project. METHODS: Corneal thickness was measured by ultrasonic pachymetry at the center and inferior margins of the pupil of 142 normal and 99 keratoconus patients The corneal surface topography of patients was studied with the Topographic Modeling System (TMS-1). The videokeratographs obtained were analyzed with a computer program that automatically calculates two indices derived from data points in the central and paracentral cornea: central K and I-S values. Linear discriminant analysis was used to determine the correct classification percentages using pachymetry measurements and indices derived from videokeratography as the independent variables. RESULTS: The range of corneal thickness in normal and keratoconic eyes overlapped considerably. In the discriminant analysis, videokeratography indices provided a 97.5% correct classification rate and pachymetry data, an 86.0% rate (P < .01, McNemar's test). CONCLUSION: Keratoconus is more accurately distinguished from the normal population by videokeratography-derived indices than by ultrasonic pachymetry measurements. This may be due to the large variation in corneal thickness in the normal population or the inability of ultrasonic pachymetry to accurately detect the location of corneal thinning in keratoconus by measuring standard points on the cornea. Pachymetry should not be relied on to exclude or diagnose keratoconus because the false-negative and false-positive rates are unacceptably higher than those obtained by videokeratography.

Cornea↗

PubMed1996

Upper gastrointestinal hemorrhage clinical--guideline determining the optimal hospital length of stay.

PURPOSE: Physicians lack objective outcome data to define the medically appropriate length of stay (LOS) for patients hospitalized with acute upper gastrointestinal hemorrhage (UGIH), resulting in wide variations in resource utilization and quality of care. A clinical practice guideline with the ability to assign relative risk for adverse events is proposed. METHODS: A comprehensive scoring system was derived from the literature by using four variables; hemodynamics, time from bleeding, comorbidity, and esophagoduodenoscopy findings. The discriminatory ability, potential safety, and impact on resource utilization of the clinical practice guideline was measured in a retrospective, observational study. RESULTS: Seventy percent of UGIH patients (349 of 500) achieved low-risk status according to the guideline, and, were therefore potentially suitable for early discharge from the hospital. If low-risk patients were discharged based upon the guideline, mean (+/- SD) hospital LOS would have been decreased from 4.8 +/- 2.4 days to 2.7 +/- 1.4 days; mean reduction was 2.1 bed-days per patient (95% CI 1.8 to 2.3, P <0.001). LOS would have increased in 4% of cases. Adopting the guideline's recommendation of early discharge would have resulted in a 0.6% (95% CI 0.07 to 2.1) complication rate, with no worsening of quality of care, as judged by implicit review. CONCLUSIONS: The proposed clinical practice guideline may safely reduce hospital LOS for selected low-risk patients with acute UGIH. Moreover, it also may reduce premature discharge of high-risk patients prone to life-threatening events.

Acute Disease↗

PubMed1996

Videokeratography database of normal human corneas.

AIM: To form a database of videokeratography patterns and quantitative indices describing normal human corneas using the absolute scale. METHODS: Both eyes of 195 normal subjects were examined with a TMS-1 videokeratoscope. Videokeratographs were divided into 10 categories based on a classification scheme devised from the absolute scale and analysed with 10 quantitative indices devised to describe phenotypic features of keratoconus videokeratographs. Correlations were sought between videokeratograph patterns and quantitative indices. Additionally, data were analysed for differences in age, sex, and ethnicity. RESULTS: For symmetric videokeratography patterns, analysis in the absolute scale was similar to a previous study done in the normalised scale. In the asymmetric categories, analyses differed markedly. Using the absolute scale and our classification scheme more variation in normal videokeratography patterns could be appreciated. There was good correlation between quantitative indices and videokeratography patterns. Neither videokeratography patterns nor indices differed significantly between sex, ethnic groups, or age using two way analysis of variance. CONCLUSIONS: Pattern analysis of videokeratographs in the absolute scale using, a standard classification scheme, may be more useful in trying to determine whether a cornea is normal or represents subtle early disease than analysis in the normalised scale. Quantitative indices could remove the subjectivity from the decision making process thus facilitating universal reproducibility of videokeratography data interpretation.

Adult↗

PubMed1995

Isogravitational heterogeneity of perfusion after unilateral lung transplantation.

1. Single-photon emission computerized tomography in both an intact canine model and man has demonstrated an aspect of pulmonary perfusion to be independent of gravitational forces. 2. Using technetium 99m-labelled macroaggregated albumin single-photon emission computerized tomographic imaging, we investigated normal human subjects (n = 5), stable unilateral lung transplant recipients (n = 6) and transplant recipients with chronic allograft dysfunction related to obliterative bronchiolitis (n = 5). 3. In coronal isogravitational sections, a 1 x 1 x N pixel strip (medial to lateral) was constructed through the 'core' pixel of maximal radioactive counts. The counts were measured for the 'core' pixel and at two mid-points (medial and lateral) between the core pixel and the lung edges. Coefficients of variation were computed for each isogravitational strip and compared between groups. Fractional whole-lung perfusion was determined for left versus right lungs of normal subjects and allograft versus native lungs of transplant recipients. 4. Using these indices, 'isogravitational heterogeneity' (i.e. increased 'core' versus peripheral perfusion) was observed in allografts and native diseased lungs after unilateral transplantation. Despite significantly increased fractional whole-lung perfusion directed to the allografts (84.8% +/- 3.0% and 75.8% + 12.1% for stable unilateral lung transplant recipients and patients with obliterative bronchiolitis respectively) compared with normal lungs (50.2% +/- 1.2% and 49.8% +/- 1.2% for left and right respectively), 'isogravitational flow heterogeneity' (i.e. increased 'core' versus peripheral perfusion) was preserved after transplantation. 5. These findings suggest that 'isogravitational heterogeneity' was maintained despite increased unilateral pulmonary perfusion and the presumed increase in pulmonary capillary recruitment and/or distension.

Adult↗

PubMed1992

Reproducibility of stress redistribution thallium-201 SPECT quantitative indexes of hypoperfused myocardium secondary to coronary artery disease.

To determine the reproducibility of quantitative indexes of hypoperfused myocardium by exercise thallium-201 single-photon emission computed tomography, duplicate studies were performed in 16 stable patients within 1 month. Twenty-three other patients, with intervals up to 13 months between studies, were retrospectively identified from medical records. Symptoms, weight, heart rate achieved and peak systolic blood pressure during the 2 studies were similar. Maximal counts circumferential profiles' polar maps were generated and divided into 3 vascular territories. The hypoperfused myocardium was defined as the percent stress profile points below the normal level. The observed values were compared between the 2 studies for each patient. Defect size ranged from 0 to 73%. The concordance correlation coefficient (a measure of the closeness of the data points to the line of identity) and mean absolute deviation were 0.94 and 4.5%, respectively, when all patients were considered together, 0.93 and 3.2%, respectively in the reproducibility group, and 0.94 and 5.1%, respectively, in the retrospective group. Inter- and intraobserver reproducibility were also very high. For individual vessels, the concordance correlation coefficients were all > or = 0.89 and the mean absolute deviations between 3.7 and 9%. Thus, in stable patients with repeat thallium studies within a year, the percent hypoperfused myocardium is highly reproducible.

Adult↗

PubMed1989

Pancreatobiliary responses to an intragastric amino acid meal: comparison to albumin, dextrose, and a maximal cholecystokinin stimulus.

Little is known about how gastric and pancreatobiliary responses differ after intake of elemental diets from responses to polymeric food. We therefore compared pancreatic and biliary secretions after gastric instillation of albumin (7 g%, with dextrose 21 g%) with an elemental diet in 6 healthy volunteers. The elemental diet contained amino acids (7 g%, with dextrose 21 g%) in the same molar composition as the albumin. Furthermore, we studied the effect of a pure intragastric dextrose solution (21 g%) on pancreatobiliary secretions, as glucose constitutes a major component of elemental diet formulas. The various pancreatobiliary responses were tested against a maximal i.v. cholecystokinin stimulus. The dextrose, amino acid, and albumin meals emptied at similar rates, and gastric emptying was completed within 3 h. Similar pancreatobiliary responses were observed after the albumin and amino acid meals, but response to both the amino acid and albumin meals was smaller than to the intravenous cholecystokinin stimulus. The glucose meal caused a marked and sustained stimulation of pancreatobiliary outputs, which did not differ significantly from the other test meals. However, lower cholecystokinin levels were observed after the glucose meal compared with distinct cholecystokinin release after the albumin and amino acid meals. We conclude first that there are no major differences in secretory responses between elemental (amino acid) and polymeric (protein) meals and second, that intragastric pure glucose meals strongly stimulate pancreatobiliary secretions. The marked pancreatic and biliary responses to intragastric dextrose cannot be fully explained on the basis of cholecystokinin release, suggesting that this response is probably mediated by neural mechanisms.

Adult↗

PubMed1988

Gastric emptying of mixed solid-liquid meal in patients with intestinal pseudoobstruction.

Gastric emptying of solids and liquids was evaluated simultaneously in 11 patients with intestinal pseudoobstruction. Despite a normal upper gastrointestinal series in most patients, over two thirds of the patients had abnormal gastric emptying of solids and/or liquids. Half these patients exhibited delayed emptying of solids and accelerated emptying of liquids. Alterations in motility patterns were observed in the four patients tested including decreased frequency or absence of migrating motor complexes originating in the stomach, shortening or absence of phase I, and loss of distinct fasted and fed patterns. Both basal values and mean postprandial increments in serum gastrin concentrations were lower in the patients, whereas no significant difference was found for pancreatic polypeptide concentrations when compared to normals. Our findings emphasize the functional heterogeneity of patients with intestinal pseudoobstruction. In addition, in contrast to previous reports which used barium meals to access gastric function, we observed a high prevalence of gastric emptying disturbances in these patients, suggesting that the motility disturbance is not restricted to the small intestine.

Adult↗

PubMed1988

Human postprandial gastric emptying of 1-3-millimeter spheres.

Microspheres of pancreatin should empty from the stomachs of patients with pancreatic insufficiency as fast as food. The present study was undertaken in 26 healthy subjects to identify the size of spheres that would empty from the stomach with food and to determine whether different meals alter this size. Spheres of predefined sizes were labeled with 113mIn or 99mTc. Using a gamma-camera, we studied the concurrent gastric emptying of spheres labeled with 113mIn and of chicken liver labeled with 99mTc in 100-g, 154-kcal or 420-g, 919-kcal meals, or the concurrent emptying of 1-mm vs. larger spheres. One-millimeter spheres emptied consistently (p less than 0.01, paired t-test) faster than 2.4- or 3.2-mm spheres when ingested together with either the 420- or 100-g meals. Thus, in the 1-3-mm range of diameters, sphere size was a more important determinant of sphere emptying than meal size. Statistical analyses indicated that spheres 1.4 +/- 0.3 mm in diameter with a density of 1 empty at the same rate as 99mTc-liver. Our data indicate some commercially marketed microspheres of pancreatin will empty too slowly to be effective in digestion of food.

Adult↗

PubMed1986

Gastric emptying of liquids in normal subjects and patients with healed duodenal ulcer disease.

We have characterized the dose-response of inhibition of gastric emptying by acid, glucose, and fat in duodenal ulcer (DU) patients and normals (N) matched by age and sex. Gastric emptying was measured by the George technique while intragastric pH was maintained constant by intragastric titration. Acid, glucose, and fat inhibited gastric emptying in a dose-dependent fashion in both groups. DU patients emptied all three types of meals faster than normals, but differences were only seen at the lower doses of glucose or with the less potent doses of acid and fat. With low concentrations of glucose and at all concentrations of acid, DU patients emptied the meals faster than normals only in the first 5 min; but with fat the differences persisted throughout the 30-min test. Differences in gastric emptying of liquid meals in DU patients vs normals are small, and they occur with nutrient as well as acid meals. The variable responses obtained with the different concentrations may explain the inconsistencies found by other workers.

Citrates↗

PubMed1986

Canine resistances to gastric emptying of liquid nutrients after ulcer surgery.

In two groups of dogs, we studied average rates of gastric emptying of 0.15 M NaCl, 0.6 M glucose, or 0.04 M oleate liquid meals while gastric pressures were controlled by a barostat and compared this emptying to spontaneous gastric emptying of the same three meals. In the first group of dogs, this comparison was made before and after truncal vagotomy + pyloroplasty (TVP); and in the second group, before and after antrectomy, first with gastroduodenostomy (A-BI) and then with Roux-Y bypass (A-RY). Under barostatically controlled gastric pressures, gastric emptying of oleate and glucose remained slower than emptying of saline before as well as after TVP or A-BI and A-RY. However, all operations accelerated initial spontaneous emptying, compressing differences between half-emptying times of the three meals. We conclude postfundic resistances remain after TVP or antrectomy but may act too late to alter rapid initial emptying.

Animals↗

PubMed1986

Effects of viscosity and fluid outflow on postcibal gastric emptying of solids.

It is known that the food-filled stomach retains large spheres or pieces of food, allowing the passage of food particles or of plastic spheres with diameters mainly below 2 mm. We have recently shown that spheres having densities greater or less than water emptied from the food-filled canine stomach more slowly than spheres of the same diameter with a density of 1. Thus, hydrodynamics seem to govern gastric emptying of spheres. The present studies were undertaken to determine how altering other hydrodynamic factors, viscosity and velocity of fluid outflow, might affect gastric sieving. Ten mongrel dogs were prepared with chronic duodenal fistulas, which allowed collecting and measuring of emptied spheres and food. The dogs were fed a standard meal of 75 g of steak plus 25 g of 99mTc-labeled chicken liver. Immediately afterward, 50 3.2-mm Teflon spheres were instilled into the stomachs along with 200- or 800-ml volumes of saline or saline plus guar (a viscous polysaccharide). Whether 200- or 800-ml volumes were instilled, the guar significantly sped the emptying of the spheres. Fluid outflow was twice as fast after the 800-ml instillates, but the faster outflow with the 800 ml of saline did not speed emptying of spheres. With the guar instillates, the faster outflow slightly sped the emptying of the spheres and significantly increased the diameter of emptied particles of 99mTc-labeled chicken liver. We conclude that meal viscosity significantly affects gastric sieving.

Animals↗

PubMed1986

Potency of natural and synthetic canine gastrin-releasing decapeptide on canine antral muscle.

The carboxyl terminal decapeptide of gastrin-releasing peptide (GRP-10), a small, naturally occurring bombesin-like peptide, has been isolated from canine antral muscle, synthesized, and its bioactivity compared with other synthetic and natural gastrin-releasing peptides on stimulation of spontaneously occurring contractions of canine circular antral muscle in vitro. Concentrations of peptides were verified by amino acid analysis and radioimmunoassay. In this system three forms of natural canine GRP, synthetic GRP-10, synthetic porcine gastrin-releasing heptacosapeptide (GRP-27), [Gln3]GRP-10, and [Arg3]GRP-10 all were similar in potency to synthetic amphibian bombesin. These results differ from the low activity of GRP-10 previously reported in rat brain. The full biological potency on canine antral motility and the presence of GRP-10 in nerve fibers in the gut and in the spinal cord suggest a possible role for this peptide as a neurotransmitter or neuromodulator in regulation of smooth muscle contraction.

Amino Acids↗

PubMed1986

Characterization of substance P effects on canine antral muscle.

Synthetic substance P increased the frequency and amplitude of spontaneously occurring contractions of circular and longitudinal muscle strips from canine gastric antrum in vitro. In longitudinal muscle, ED50 values calculated for frequency and amplitude were 3.7 X 10(-9) M and 9.7 X 10(-7) M, respectively. The effect of substance P on frequency in both layers and on amplitude in the circular layer was myogenic and unrelated to receptors for acetylcholine, norepinephrine, serotonin, histamine, and enkephalins. In the longitudinal muscle the amplitude response was partially inhibited by tetrodotoxin, atropine, and hexamethonium. The effect on amplitude but not on frequency was dependent on extracellular calcium. When compared to other stimulants of antral muscle contraction, the biological potency of substance P was higher than that of acetylcholine but significantly lower than that of gastrin and bombesin. Two putative substance P antagonists ([D-Pro2,D-Phe7,D-Trp9]substance P and [D-Pro2, D-Trp7,9]substance P) did not block the response of longitudinal muscle to substance P. Only the chronotropic response to substance P showed consistent, prolonged desensitization. These findings suggest that the mechanisms mediating the response to substance P in the canine antrum are different from other reported tissues.

Animals↗

PubMed1985

Gastric emptying and pancreatic polypeptide response to carbohydrate meals.

This study examined pancreatic polypeptide responses to isocaloric meals of radioactively labeled glucose or starch in six normal and seven vagotomized subjects. Liquid glucose meals were ingested with the subject both erect and supine and starch meals were ingested in the upright posture as a solution and as solid balls. In normal subjects, each meal left the stomach at a similar rate and the resultant pancreatic polypeptide responses were not significantly different from one another. Emptying rates varied markedly in vagotomized subjects depending upon the physical consistency of the carbohydrate ingested and the patient's posture. Despite these differences, pancreatic polypeptide responses to each meal were almost identical. These studies demonstrate that the pancreatic polypeptide response to carbohydrate meals is still present several years after vagotomy and is unaffected by alterations in the rate of gastric emptying after vagotomy and by the physical consistency and chemical nature of the carbohydrate ingested.

Adult↗

PubMed1985

Effects of vagotomy on satiety induced by gastrointestinal hormones in the rat.

Cholecystokinin, bombesin and pancreatic polypeptide are all reported to induce satiety in rodents. To test the hypothesis that cholecystokinin and bombesin induce satiety through release of pancreatic polypeptide, we compared the satiety inducing properties of each peptide in rats trained to eat a liquid diet (Magnacal). Studies were repeated after transabdominal truncal vagotomy (n = 8) or sham operation (n = 8). Peptides were given by intraperitoneal injection, and the volume of Magnacal ingested over a 2 hr period measured. After the injection of saline, unoperated rats (n = 16) ingested 30 +/- 2.3 ml of Magnacal. Caerulein (9 nmol/kg) and bombesin (27 nmol/kg) significantly inhibited food intake to 8 +/- 2.5 ml and 20 +/- 2.1 ml respectively. In contrast pancreatic polypeptide (27 nmol/kg) had no significant effect on food intake. Both caerulein and bombesin retained the ability to reduce food intake after vagotomy although the effects of caerulein were somewhat blunted. No significant changes in serum pancreatic poly peptide concentrations were observed after either the caerulein or bombesin injection. As both peptides release pancreatic polypeptide in higher mammals, species differences in release mechanisms appear to exist. We would conclude that caerulein and bombesin induced satiety is independent of pancreatic polypeptide release and that the weight loss induced by pancreatic polypeptide in obese rodents is unlikely to be due to induction of satiety.

Animals↗

PubMed1985

Hypergastrinemia develops within 24 hours of truncal vagotomy in dogs.

Postvagotomy hypergastrinemia may result from withdrawal of tonic vagal inhibitory mechanism(s) or from G-cell hyperplasia secondary to diminished acid secretion. Early development of hypergastrinemia, after vagotomy, would favor the first mechanism, whereas delayed development would favor the second. We sought to distinguish between these two mechanisms and to determine whether alterations in somatostatin release might mediate postvagotomy hypergastrinemia. We measured plasma concentrations of gastrin and somatostatinlike immunoreactivity basally and in response to meal (pH controlled at 5.5) and to insulin hypoglycemia before and after truncal vagotomy in 11 dogs. Basal and postprandial hypergastrinemia were established within 24 and 48 h after vagotomy, respectively. Basal and meal-stimulated plasma somatostatinlike immunoreactivity concentrations were unaltered by vagotomy, although insulin hypoglycemia-induced rises in plasma somatostatinlike immunoreactivity were abolished by vagotomy. Our data suggest that neither G-cell hyperplasia nor alterations in somatostatin release explain postvagotomy hypergastrinemia in the dog. The observations support the hypothesis that postvagotomy hypergastrinemia results from the withdrawal of a tonic vagal inhibitory mechanism of gastrin release that is independent of somatostatin. Whether the tonic vagal inhibition of gastrin is direct or indirect is unknown.

Animals↗

PubMed1985

The histology of the stomach in symptomatic patients after gastric surgery: a model to assess selective patterns of gastric mucosal injury.

We assessed selective patterns of histological injury in the gastric mucosa of 25 patients (12 Billroth II, 8 Billroth I, 5 vagotomy and pyloroplasty) with symptoms of alkaline reflux gastritis. Each patient had 12 biopsies taken from standardised sites. Histology was scored separately for surface epithelial changes and for inflammatory cells. The traditional grading of gastritis was also done using the categories of superficial and atrophic gastritis. The main histological changes were epithelial, especially in the pits (foveolae) of Billroth II patients. Although mild to moderate atrophic gastritis was present, the inflammatory cell density was only mild. Differences between surgery types for any given histological parameter became apparent only upon the analysis of regional changes within the stomach. Conventional grading of gastritis is based mainly on degrees of gland loss and thus is mainly of value to study chronic changes. However, the type of histological evaluation used here, with standardised biopsy sites, and separate scoring of epithelial and inflammatory changes is potentially more suitable to study shorter term changes as might occur with cytoprotective or damaging agents.

Biopsy↗

PubMed1985

Salicylic acid blocks indomethacin-induced cyclooxygenase inhibition and lesion formation in rat gastric mucosa.

Salicylic acid has been shown to decrease gastric mucosal lesions induced by indomethacin in the rat. In vitro, it has also been shown to counteract the inhibitory effect of indomethacin and aspirin on the cyclooxygenase enzyme system in seminal vesicle microsomes and in platelets and vascular tissue. The hypothesis that the mechanism of salicylic acid "protection" against indomethacin-induced gastric lesions involves interference with indomethacin-induced mucosal cyclooxygenase inhibition was tested. Male, fasted rats were treated with intragastric salicylic acid in doses of 50, 100, 200, 300, or 400 mg/kg concomitantly with a sc injection of 20 mg/kg of indomethacin. Gastric mucosal lesions and mucosal cyclooxygenase activity (as measured by ex vivo prostaglandin F2 alpha synthesis) were examined 3 hr later. Intragastric salicylic acid, 200-400 mg/kg, significantly reduced indomethacin-induced lesion formation, while counteracting significantly indomethacin inhibition of prostaglandin synthesis. Salicylic acid alone did not significantly change cyclooxygenase activity. It is concluded that topical salicylic acid can decrease indomethacin-induced gastric mucosal lesion in the rat, in part, by counteracting the inhibitory effect of indomethacin at the cyclooxygenase level.

Animals↗