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Biomedical subjects

S E Schwartz

Publications and source records attributed to S E Schwartz.

At least 19 recordsLinked to original sources
PubMed2000

Predicting language production in children and adolescents with Down syndrome: the role of comprehension.

Predictors of language production skills in 12-minute narratives are investigated cross-sectionally in 48 children and adolescents with Down syndrome (trisomy 21), aged 5 to 20 years, in comparison to 48 control children aged 2 to 6 years matched statistically for nonverbal mental age and mother's years of education. Two models were evaluated by hierarchical regression analyses using predictors drawn from the domains of group membership, chronological age, cognition, socioeconomic status, and hearing screening status (Model I) and, additionally, comprehension performance (Model II). Results showed that Model II was more successful. In the DS group, it explained 68% of the variability in number of different words, 80% in MLU, and 32% in intelligibility. Corresponding percentages for the control group were 72%, 71%, and 26%. A mechanism linking comprehension of input to early stages of production practice through activation of the early speech motor area is proposed.

Adolescent↗
PubMed1998

Language skills of children and adolescents with Down syndrome: II. Production deficits.

Hypotheses that children and adolescents with Down syndrome show (a) a specific expressive language impairment, (b) a "critical period" for language acquisition, (c) a "simple sentence syntactic ceiling" in production, and (d) deficit in grammatical morphology were investigated cross-sectionally. Conversational and narrative language samples from 47 children and adolescents with Down syndrome (Trisomy 21), aged 5 to 20 years, were compared to those from 47 control children aged 2 to 6 years matched statistically for nonverbal mental age. Children with Down syndrome appear to have a specific language impairment, compared to control children, in number of different words and total words (in the first 50 utterances) and in mean length of utterance (MLU). Total utterance attempts per minute were more frequent in the Down syndrome group. Narrative samples contained more word tokens, more word types, and longer MLU than conversation samples, for both groups. Intelligibility of narratives was significantly poorer for the Down syndrome group than controls. Analyses of narrative language sample by age sub-group showed no evidence of a critical period for language development ending at adolescence, nor of a "syntactic ceiling" at MLUs corresponding to simple sentences for the Down syndrome group. Omissions of word tokens and types were more frequent in the older Down syndrome than the younger control sample, matched on MLU.

Adolescent↗
PubMed1994

Pharmacodynamics of racemic and S(-)-atenolol in humans.

The cardiovascular actions of racemic atenolol (RSATN) have been well characterized in humans, but the actions of S(-)-atenolol (SATN) when administered alone are unknown. In this study, responses of heart rate (HR) and Doppler-derived aortic blood flow profiles to upright treadmill exercise were compared after oral administration of 50 mg SATN and 100 mg RSATN in eight healthy, adult, male volunteers. After a single-blind, placebo run-in period, subjects were randomly allocated in a double-blind, crossover fashion to receive SATN and RSATN. Each study period was separated by a 7-day washout period. Multiple submaximal exercise tests were performed and data were collected over the 24 hours after each treatment. Both SATN and RSATN significantly (P < .05) blunted peak exercise HR by 38 +/- 3 and 37 +/- 3 beats/min, respectively. Aortic blood flow acceleration measured during peak exercise decreased after SATN and RSATN, by 13 +/- 4 and 13 +/- 3 m/sec2, respectively (P < .05). No difference in hemodynamic effect was observed between treatments. Pharmacodynamic parameters derived from plasma S(-)-atenolol concentration-effect (HR) curves after SATN, RSATN, and total atenolol plasma concentrations after RSATN did not differ significantly. Predicted maximum reductions in heart rate (Emax) and EC50 for S(-)-atenolol after SATN were 39.6 +/- 5.8 beats/min and 38.4 +/- 40.9 ng/ml versus 34.5 +/- 8 beats/min and 25.9 +/- 29.9 ng/ml for RSATN, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Language skills of children and adolescents with Down syndrome: I. Comprehension.

This study investigates the development of vocabulary and syntax comprehension skills cross-sectionally in 48 children and adolescents with Down syndrome (Trisomy 21), aged 5-20 years, in comparison to 48 control children aged 2-6 years matched statistically for nonverbal mental age and mother's years of education. Age-equivalent scores on vocabulary (PPVT-R) and syntax (TACL-R) comprehension tests differed in the Down syndrome group but not the control group; vocabulary comprehension was relatively more advanced than syntax. Age-equivalent scores on nonverbal cognitive subtests of pattern analysis and short-term memory for bead arrangements (Stanford-Binet, 4th ed.) also differed for the Down syndrome group but not the control group, indicating an unusual pattern of nonverbal cognitive function in the Down syndrome group. Stepwise multiple regression analyses showed that chronological age and mean mental age, collectively, accounted for 78% of the variability in vocabulary comprehension and 80% of the variability in syntax comprehension in the Down syndrome group, with total passes on a hearing screening accounting for an additional 4% in each case. Implications for research are discussed.

Adolescent↗
PubMed1990

Fast mapping of words in event contexts by children with Down syndrome.

Fast mapping of novel words for objects was compared in 48 children and adolescents with Down syndrome (ages 5:6-20:6), who were delayed in expressive language acquisition compared to mental age, and 48 normally developing children matched for mental age (chronological ages 2:0-6:0). Normal and Down syndrome groups did not differ in their ability to infer a connection between the novel word and referent (100% vs. 100%), to comprehend the novel word after a single exposure (83% vs. 73%), and to recall the location in which they hid the novel referent (83% vs. 75%). Nor did they differ in their ability to produce the novel word correctly (at least two out of three phonemes in order: 48% vs. 40%). When retested after an hour of other activity, only the production task showed a significant, and comparable, decrement. Comparing youngest and oldest quarters of each group showed improved memory for location in both, improved comprehension in the Down syndrome group, and improved production in the control group. Adults (n = 12), in contrast, performed perfectly on all tasks except the delayed word production. Neither intelligibility differences nor use of real word labels accounts for the failure to find a difference between groups. Fast mapping skills were unrelated to expressive language deficit in these children with Down syndrome.

Adolescent↗
PubMed1988

Sustained pectin ingestion: effect on gastric emptying and glucose tolerance in non-insulin-dependent diabetic patients.

The effects of sustained pectin ingestion on gastric emptying, glucose tolerance, and hormone responses were studied in 12 stable, non-insulin-dependent (type 2) diabetic patients. Patients were placed on a 2400 kcal, low-fiber (3 g) diet for 2 wk, followed by 4 wk of an isocaloric diet supplemented with 20 g apple pectin/d. Gastric-emptying half-time, plasma glucose, glucagon, and human pancreatic polypeptide levels were determined. Gastric-emptying half-time was prolonged 43% (p less than 0.025) by pectin supplementation and returned to normal 3 d after its discontinuation. Fiber supplementation decreased the incremental area under the glucose tolerance curve from 34.8 +/- 3.0 to 27.9 +/- 3.2 mmol/L (p less than 0.01) but did not affect hormonal responses to a meal. Sustained pectin ingestion slowed the gastric-emptying rate and improved glucose tolerance; however, a direct relationship could not be demonstrated between changes in gastric emptying and changes in the incremental area under the glucose curve (r = 0.22).

Adult↗
PubMed1987

Prevention of aspirin-induced gastric mucosal injury by histamine H2 receptor antagonists: a crossover endoscopic and intragastric pH study in the dog.

Histamine H2 receptor antagonists have been reported to protect the gastric mucosa of animals and humans against aspirin-induced damage. It is unclear, however, whether this protective effect can be observed at doses less than those needed to markedly inhibit gastric acid secretion. We have developed a single-dose endoscopic assay system of aspirin-induced gastric mucosal injury in normal conscious dogs. In this model, severe gastric mucosal injury and a decrease in the pH of the gastric luminal contents were consistently demonstrated 2 h after the oral administration of 100 mg/kg of aspirin. Pretreatment with three histamine H2 receptor antagonists (cimetidine, ranitidine, BMY-25271), prevented both of these effects in a dose-related manner. All three H2 receptor antagonists reduced gastric mucosal injury only at doses that were greater than those required to prevent the aspirin-induced decrease in gastric luminal pH or to inhibit histamine-stimulated gastric acid secretion in Heidenhain pouch dogs. Plasma levels of aspirin were not altered by histamine H2 receptor antagonism. These results indicate that acid inhibition is an important component of the mechanisms whereby histamine H2 receptor antagonists protect the gastric mucosa from aspirin-induced damage in the dog.

Animals↗
PubMed1985

Analysis of publication output of internal medicine faculty members.

The number of publications per year produced by a department of internal medicine faculty is analyzed. The output of the younger faculty members (40 years or less) averaged 1.4 publications a year, and the annual output of the older faculty (over 40 years) averaged 2.3 publications (p less than 0.05). The site of their primary clinical responsibilities did not significantly affect their publication productivity. In all subspecialty sections, the output of older faculty members correlated well with that of younger faculty members (p less than 0.005). The productivity of section chiefs correlated well with the productivity of younger faculty members in their respective sections (p less than 0.001). Younger faculty members who later entered private practice had a lower (p less than 0.02) publication output than those who left for another academic position. The output of faculty members is related to the age of the faculty members, overall sectional productivity, and productivity of the section chief.

Adult↗
PubMed1984

Indomethacin enhances histamine-stimulated acid production in rabbit isolated fundic glands.

The effects of 10(-4)M indomethacin on tissue prostaglandin E2 levels, cyclic AMP concentrations, and acid secretion as measured by the intraglandular accumulation of [14C]aminopyrine were evaluated in unstimulated and histamine-stimulated isolated rabbit fundic glands. Indomethacin (10(-4)M) reduced endogenous prostaglandin E2 content by 52% in unstimulated glands. Indomethacin tripled histamine (10(-6)-10(-4)M-stimulated aminopyrine uptake while not affecting aminopyrine accumulation in unstimulated glands. Indomethacin did not affect cyclic AMP levels in either the unstimulated or stimulated condition.

Aminopyrine↗
PubMed1983

Patterns of diagnostic testing in the academic setting: the influence of medical attendings' subspecialty training.

Internists with subspecialty training (subspecialists) constitute the majority of the medical faculty members and the test-ordering behavior of these subspecialists influences how house officers and students solve clinical problems. To assess whether test-ordering patterns are influenced by the ward attendings' subspecialty status, we identified the number of gastrointestinal endoscopic procedures, bone marrow procedures and exercise stress tests that were ordered on 9608 patients admitted to a medical service during a 3 year period. The patient management was supervised by attendings, 8 of whom were generalists and 37 of whom were subspecialists. House officers supervised by generalists ordered 23% fewer gastrointestinal procedures, 47% fewer bone marrow procedures, 43% fewer exercise stress tests and 29% fewer total procedures than house staff supervised by subspecialists (P--not significant, P less than 0.001, P less than 0.05 and P less than 0.01, respectively). House officers perceive a difference between the test-ordering patterns of subspecialists and generalists. They attribute this difference to post-residency training and believe that the use of more tests indicates a greater compulsion toward an exhaustive evaluation.

Diagnostic Services↗
PubMed1983

Dietary fiber decreases cholesterol and phospholipid synthesis in rat intestine.

The effects of fiber ingestion on the incorporation of oleic acid into triglyceride and lecithin, acetate incorporation into cholesterol, and monosaccharide and amino acid transport were determined in rat intestine. Prolonged pectin (10% by weight) ingestion caused a decrease in jejunal and ileal cholesterol synthesis (33% and 52%, respectively). Pectin ingestion reduced cholesterol synthesis by 60% in ileal crypt cells, but did not affect cholesterol synthesis in the jejunal or ileal villus cells or in jejunal crypt cells. Cholesterol synthesis in isolated crypt cells was markedly less than in isolated villus cells. Prolonged ingestion of a fiber-free diet supplemented with either cellulose or pectin (10% and 5% by weight, respectively) decreased jejunal lecithin glucose and leucine absorption but did not affect jejunal triglyceride synthesis.

Acetates↗
PubMed1982

Effects of dietary fiber on intestinal ion fluxes in rats.

The effect of short-term fiber ingestion on jejunal ion fluxes was evaluated in rats using a standard Ussing chamber technique. Ingestion of cellulose and pectin decreased the mucosal to serosal fluxes of both Na and Cl but did not significantly alter serosal to mucosal fluxes; net fluxes of both Na and Cl were significantly lower in the group supplemented with dietary fiber as compared to those animals fed a fiber-free diet. Both potential difference and short-circuit current were higher in the fiber-free group than in the group supplemented with dietary fiber; tissue conductance, however, was unaffected by fiber ingestion. The residual flux of all three groups was virtually identical suggesting that electrical alterations observed after cellulose and pectin ingestion are not the result of ion fluxes other than Na and Cl. These data, coupled with previous observations that short-term fiber supplementation impairs glucose and leucine absorption, suggest that fiber ingestion alters the intestinal membrane, specifically sites of active transport.

Animals↗
PubMed1982

Sustained pectin ingestion delays gastric emptying.

The effects of sustained fiber ingestion on gastric emptying glucose tolerance, hormone responses, and jejunal absorption of glucose and lysine were studied in healthy volunteers. Subjects were placed on a low-fiber (3 g) diet for 2 wk, followed by 4 wk of an isocaloric diet supplemented with 20 g/day of either apple pectin (7 subjects) or alpha-cellulose (6 subjects). At the conclusion of each dietary period subjects ingested a low-fiber breakfast surface-labeled with 99mtechnetium sulfur-colloid. Gastric emptying half-time, plasma glucose, calcium, phosphorus, insulin, glucagon, gastrin, human pancreatic polypeptide, and motilin were determined. Gastric emptying half-time was prolonged approximately twofold after pectin supplementation (p less than 0.005) and returned to normal 3 wk after discontinuing pectin supplementation. Cellulose supplementation did not alter the gastric emptying rate. Plasma glucose, calcium, phosphorus, and hormonal responses to the meal were unchanged after either pectin or cellulose supplementation. Pectin ingestion did not impair intestinal absorption of glucose or lysine. In contrast to sustained cellulose ingestion, sustained pectin ingestion slows the gastric emptying rate; the mechanism underlying this adaptive effect is unknown.

Adolescent↗
PubMed1980

Permeability characteristics of muscle membrane.

Unidirectional flux rates of saturated fatty acids, saturated alcohols, and bile acids were measured in an intact rat diaphragm preparation. The logarithm of the permeability coefficients for fatty acids containing from five to ten carbon atoms was a linear function of the number of carbon atoms in the fatty acid chain. Incremental free energies of solution were +336 cal x mol-1 for the addition of a hydroxyl group and -258 cal x mol(-1) for the addition of a methylene group. These incremental free energies were similar to those obtained by other investigators in other animal tissues, and our data suggest a structural similarity between membranes in different tissues and in different species. The muscle membrane exhibited anomalously high permeabilities for fatty acids containing less than five carbon atoms. Since muscle lacks tight junctions, this result suggest that small non-electrolytes traverse polar regions or aqueous pores within the cellular membrane.

Alcohols↗
PubMed1980

Oxalate uptake by everted sacs of rat colon. Regional differences and the effects of pH and ricinoleic acid.

Hyperoxaluria is a complication of disorders associated with steatorrhea. The colon is the presumed site of enhanced oxalate absorption in patients with steatorrhea. We performed studies of colonic mucosal oxalate uptake in everted sacs of rat colon to determine the kinetics of colonic oxalate transport and to evaluate the effect of both pH and ricinoleic acid, a hydroxy fatty acid, on colonic oxalate uptake. Our study demonstrated that oxalate is transported throughout the colon by passive diffusion. Tissue uptake increased linearly with increasing oxalate concentrations and was unaffected by metabolic inhibitors, oxygen deprivation, or temperature changes. There were pH-dependent regional differences of oxalate uptake both in the presence and absence of ricinoleic acid. In the absence of ricinoleic acid, the highest oxalate uptake occurred at the lower pH values (5.4 and 6.4). In the presence of ricinoleic acid oxalate uptake was enhanced at the higher pH values (7.4 and 8.4); a finding most likely related to decreased solubility of ricinoleic acid at pH 5.4 and 6.4. Intraluminal pH is an important determinant of colonic oxalate uptake in the presence and absence of ricinoleic acid.

Animals↗