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Biomedical subjects

S Carlson

Publications and source records attributed to S Carlson.

At least 73 records · Page 4Linked to original sources
PubMed1996

The effects of prefrontal intracortical microinjections of an alpha-2 agonist, alpha-2 antagonist and lidocaine on the delayed alternation performance of aged rats.

A selective alpha-2 agonist medetomidine, a selective alpha-2 antagonist atipamezole and lidocaine were injected into the prefrontal cortex of aged rats that had been trained to perform a delayed alternation (DA) task in a T maze. Medetomidine at the dose of 0.01 microgram/microliter improved the memory task performance in four of five rats. The fifth rat improved its performance at the dose of 1.0 microgram/microliter. Atipamezole did not have any effect on the task performance. The effect of a systemic dose of medetomidine (3 micrograms/kg), which was previously shown to improve the task performance in old rats, was reversed by an intracortical injection of atipamezole. Lidocaine impaired the DA performance significantly. The results suggest that the beneficial effects of medetomidine on the working memory of old rats are mediated at least partly through the prefrontal cortex.

Adrenergic alpha-Agonists↗
PubMed1996

Medetomidine, atipamezole, and guanfacine in delayed response performance of aged monkeys.

The effects of a highly selective alpha-2 adrenergic agonist medetomidine and its antagonist atipamezole were studied on the delayed response task performance of aged monkeys. Medetomidine, at the dose of 1.0 micrograms/kg, improved the memory task performance, whereas atipamezole had no effect on the performance at any dose. It has earlier been shown that alpha-2 adrenergic agonists clonidine and guanfacine improve age-associated memory impairment, but also contradictory effects of clonidine have been reported. There is evidence that the ability of alpha-2 agonists to improve DR task performance is due to its selective action on the alpha-2A receptor subtype. Clonidine and medetomidine are much less selective than guanfacine with respect to alpha-2A and alpha-2B receptor subtypes. Therefore, we also studied the effect of guanfacine on the memory task performance of the same aged monkeys in the same testing conditions to compare the effectiveness of these two alpha-2 adrenergic compounds. Guanfacine improved memory task performance at the dose of 0.0001 mg/kg. The results indicate that alpha-2 agonists, independent of their different selectivity with respect to alpha-2A/2B receptor subtypes, are beneficial drugs in improving the performance in the delayed response task.

Adrenergic alpha-Agonists↗
PubMed1996

The role of nutrition in the development of normal cognition.

The goal of this section of the meeting was to review the relation between nutrition and cognition. The topics selected for discussion included generalized malnutrition, iodine deficiency, iron metabolism, and the relation of fatty acids to the development of the nervous system. Each subject is immense and demands a detailed exposition, but can be treated here only in brief form. However, these short essays should give some insight into the status of our current knowledge.

Brain↗
PubMed1996

Liver uptake function measured by IODIDA clearance rate in liver transplant patients and healthy volunteers.

Hepatobiliary scintigraphy with 99Tc(m)-diethyl-iodo-HIDA (IODIDA), an iminodiacetic acid derivative, is used to assess hepatocyte function and to visualize the hepatobiliary system. The aim of this study was to evaluate whether it is possible to describe liver function by calculating the clearance rate of IODIDA from the blood. Clearance rate was evaluated in 18 liver transplant patients (28 studies) and 11 healthy volunteers (11 studies). Two different clearance rates were calculated: the clearance of IODIDA from the blood due to liver uptake and the total clearance of IODIDA from the blood due to all possible routes of elimination. Both for the healthy controls and the liver transplant patients, there was an excellent correlation between these two methods (r = 0.92 and r = 0.93, respectively), indicating that the liver is the only essential pathway for elimination of IODIDA from the blood. The difference in clearance rate between healthy controls and liver transplant patients was highly significant (P < 0.01), corresponding to the clinical condition of the two groups. We conclude that the clearance rate of IODIDA, based on a simple measurement from the time-activity curve derived from a blood pool region of interest, is a reliable test of liver function.

Adolescent↗
PubMed1996

Identification of the galE gene and a galE homolog and characterization of their roles in the biosynthesis of lipopolysaccharide in a serotype O:8 strain of Yersinia enterocolitica.

A clone that complements mutations in Yersinia enterocolitica lipopolysaccharide (LPS) core biosynthesis was isolated, and the DNA sequence of the clone was determined. Three complete open reading frames and one partial open reading frame were located on the cloned DNA fragment. The first, partial, open reading frame had homology to the rfbK gene. The remaining reading frames had homology to galE, rol, and gsk. Analysis of the galE homolog indicates that although it can complement an Escherichia coli galE mutant, its primary function in Y. enterocolitica is not in the production of UDP galactose but, instead, some other nucleotide sugar required for LPS biosynthesis. This gene has been renamed lse, for LPS sugar epimerase. The rol homolog has been demonstrated to have a role in Y. enterocolitica serotype 0:8 O-polysaccharide antigen chain length determination. An additional galE homolog has been identified in Y. enterocolitica by homology to the E. coli gene. The product of this gene has UDP galactose 4-epimerase activity in both E. coli and Y. enterocolitica. This gene is linked to the other genes of the galactose utilization pathway, similar to what is seen in other members of the family Enterobacteriaceae. Although Y. enterocolitica 0:8 strains are reported to have galactose as a constituent of LPS, a strain containing a mutation in this galE gene does not exhibit any LPS defects.

Cloning, Molecular↗
PubMed1995

D-xylose hydrogen breath tests compared to absorption kinetics in human patients with and without malabsorption.

The D-xylose breath H2 test may be useful in characterizing intestinal absorptive function. Our aim was to determine whether breath H2 following D-xylose administration reflects the extent to which the D-xylose is absorbed by comparing it to a kinetic model of D-xylose absorption. Twenty-five subjects were studied. They ingested 15 g D-xylose on the first day and 25 g D-xylose on the third day. On the second day they received 10 g intravenous D-xylose along with 15 g oral lactulose. Multiple serum and urine samples were obtained for D-xylose content to calculate its rate constants and extent of absorption by multicompartmental analysis. Breath H2 determinations were obtained every 15 min for 3 hr following the 15 g D-xylose and lactulose ingestion. Peak breath H2 concentration correlated with extent of absorption (r = -0.787, P < 0.001), K0, the rate constant for nonabsorptive loss (r = 0.744, P < 0.001), and 5-hr urine content (r = -0.705, P < 0.001). Area under the breath H2 curve also correlated with these parameters: extent of absorption (r = -0.770, P < 0.001), K0 (r = 0.662, P < 0.001), 5-hr urine content (r = -0.629, P < 0.012). Peak D-xylose breath H2 to peak lactulose breath H2 showed no correlation with extent of absorption. The extent of absorption was higher with the 15-g dose than the 25-g dose in all patients tested (P < 0.01). (ABSTRACT TRANCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

A spatial oculomotor memory-task performance produces a task-related slow shift in human electroencephalography.

Electroencephalographic (EEG) deflections in humans related to the performance of memory-guided saccades were studied in this work. The EEG deflections were recorded during 2 spatial oculomotor delayed response tasks in which the subject was instructed to make a saccade either to the right or to the left depending on the spatial location of the cue which had been shown in the beginning of the delay period. The EEG deflections were compared to those recorded during a control task in which the subject also made a saccade to the right or to the left after a delay but the requirement to keep spatial information actively in mind was minimized. A slow delay-related shift was recorded during all task conditions. The slow shift was positive in the most frontal and negative in the more posterior recording sites. The negative slow shift in the more posterior recording sites was larger in the memory tasks than in the control task. Since the memory and the control tasks differed mainly in their requirement to hold spatial information in mind it is suggested that the difference in the magnitude of slow shifts between the memory and the control tasks reflects neural activity related to spatial working memory. But although the oculomotor responses in all tasks were similar, the preparatory activities for the impending eye movements may not have been similar and in addition to working memory may have contributed to the observed differences in the slow shifts.

Adult↗
PubMed1995

Pyogenic granuloma in Barrett's esophagus mimicking esophageal carcinoma.

A 31-year-old white man with a history of testicular carcinoma and lymphoma developed severe reflux esophagitis with stricture formation requiring repeated dilatation. Barrett's esophagus was histologically confirmed. The Barrett's mucosa was observed endoscopically and became polypoid, mimicking an esophageal carcinoma. The polyp was evaluated by endoscopic ultrasonography and ultrasonically guided aspiration cytology. It was managed by snare cautery removal, which showed a pyogenic granuloma.

Adult↗
PubMed1995

Effect of cocaine on sexual behaviour in male stumptail macaques (Macaca arctoides).

The effect of cocaine (0.01-1.0 mg/kg) on sexual behaviour was studied in four male stumptail macaques (Macaca arctoides). Following drug-saline control administration, the behaviour of the male monkey with a female was observed for 30 min in two different behavioural conditions; in one of the conditions the baseline sexual activity was low, and in the other it was high (partial or complete separation of the male and the female between the sessions, respectively). The reversal of the cocaine-induced effects was attempted by haloperidol (0.003-0.01 mg/kg), a dopamine-2-receptor antagonist. Cocaine (0.1-1.0 mg/kg) produced a highly significant dose-dependent suppression in the number of ejaculations. The cocaine-induced suppression of ejaculatory behaviour was completely reversed by haloperidol. Haloperidol at the dose range used did not in itself influence ejaculatory behaviour. The effect of cocaine on grooming, nonejaculatory mounting, aggression, or perineal investigations did not reach statistical significance. The possibility that cocaine at very low doses (0.01-0.1 mg/kg) might increase sexual activity was excluded in the behavioural condition with a low basal sexual activity. The results indicate that cocaine dose-dependently suppresses ejaculatory behaviour as a result of dopamine-2-receptor-mediated mechanisms. The cocaine-induced suppression of ejaculatory behaviour might be explained by the strong rewarding effect of cocaine alone.

Animals↗
PubMed1995

The Healthy Eating Index: design and applications.

OBJECTIVE: To develop an index of overall diet quality. DESIGN: The Healthy Eating Index (HEI) was developed based on a 10-component system of five food groups, four nutrients, and a measure of variety in food intake. Each of the 10 components has a score ranging from 0 to 10, so the total possible index score is 100. METHODS/SUBJECTS: Data from the 1989 and 1990 Continuing Survey of Food Intake by Individuals were used to analyze the HEI for a representative sample of the US population. STATISTICAL ANALYSES PERFORMED: Frequencies, correlation coefficients, means. RESULTS: The mean HEI was 63.9; most people scored neither very high nor very low. No one component of the index dominated the HEI score. People were most likely to do poorly in the fruit, saturated fat, grains, vegetable, and total fat categories. The HEI correlated positively and significantly with most nutrients; as the total HEI increased, intake for a range of nutrients also increased. DISCUSSION/CONCLUSIONS: The HEI is a useful index of overall diet quality of the consumer. The US Department of Agriculture will use the HEI to monitor changes in dietary intake over time and as the basis of nutrition promotion activities for the population.

Adolescent↗
PubMed1995

Modification of the acoustic startle response in hearing-impaired C57BL/6J mice: prepulse augmentation and prolongation of prepulse inhibition.

Modification of acoustic startle amplitude by a 10-ms tone prepulse (S1) was evaluated as a function of the interstimulus interval (ISI) between the onset of S1 and the onset of the startle-evoking stimulus (S2). Subjects were normal-hearing 1-month-old C57BL/6J (C57) mice and CBA/CaJ mice and 5-month-old C57 mice with high-frequency hearing loss. With a 2-ms ISI, 5-month-old C57 mice (but not the normal-hearing mice) exhibited pronounced prepulse augmentation (PPA) of startle: Amplitudes were much larger when S1 was present. Prepulse inhibition (PPI) occurred with ISIs of 10-100 ms in all subject groups. With long ISIs of 200 and 500 ms, however, PPI was strong only in 5-month-old C57 mice and only with S1 frequencies of 8, 12, and 16 kHz. Physiological studies of neural plasticity have shown that frequencies of 8-16 kHz become "over-represented" (more neurons responding) in the central auditory system of C57 mice, suggesting a link with prolonged PPI observed here.

Animals↗
PubMed1995

Epithelial adhesion in yeast species: correlation with surface expression of the integrin analog.

Epithelial adhesion and expression of the integrin analog, a putative candidal adhesion, were correlated for 33 clinical and laboratory isolates of Candida albicans, other Candida species, and Saccharomyces cerevisiae. On flow cytometry with saturating concentrations of the monoclonal antibody OKM1, surface fluorescence was highest for C. albicans at 67.8% +/- 1.7% and significantly reduced for Candida tropicalis (32.0% +/- 2.6%), Candida parapsilosis (18.3% +/- 2.4%), Candida glabrata (3.3% +/- 0.8%), Candida lusitaniae (2.9% +/- 1.0%), Candida krusei (0.7% +/- 0.1%), and Saccharomyces cerevisiae (1.7% +/- 0.2%) (P < .006 for all other species vs. C. albicans). Adhesion to a human epithelial cell line was highest for C. albicans at 49.8% +/- 3.5%, lower for C. tropicalis (44.7% +/- 4.6%), and incrementally reduced for all other species (< 25%) (P < .012). The correlation between integrin expression and epithelial adhesion was highly significant (P = .0066; r2 = .8). Surface expression of the integrin analog predicts epithelial adhesion for yeast species isolated in opportunistic infections.

Antigens, Fungal↗
PubMed1995

Intestinal epithelia (T84) possess basolateral ligands for CD11b/CD18-mediated neutrophil adherence.

The process of active intestinal inflammation can be modeled by the migration of neutrophils [polymorphonuclear leukocytes (PMN)] across monolayers of the human intestinal cell line T84. We now evaluate the polarity of early adhesive events occurring between human PMN and ligands on intact T84 monolayers. Transient Ca2+ depletion (tr-Ca-depl) of confluent monolayers grown on permeable supports (2 mM EDTA, 12 min, 37 degrees C) resulted in disruption of tight junctions separating apical and basolateral domains (resistance fell from 973 +/- 35 to 57.4 +/- 3.8 omega.cm2 after 12 min). The columnar T84 phenotype was not grossly altered by tr-Ca-depl. Access to basolateral membrane proteins from the apical surface after tr-Ca-depl was confirmed by enzyme-linked immunosorbant assay and immunofluorescence, using antibodies to the basolateral proteins E-Cadherin and beta 1-integrin. The effects of tr-Ca-depl on early events in PMN adhesion were next assessed. Neutrophils (2 x 10(6)) were applied to the apical surface of monolayers followed by stimulation with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (100 nM, 5 min, 37 degrees C) and quantitation. In comparison with control monolayers, tr-Ca-depl increased subsequent PMN adhesion (1.7 +/- 0.24 vs. 3.1 +/- 0.28 x 10(4) adherent PMN/monolayer; P < 0.005), which was inhibited 80% by anti-CD11b/CD18 antibodies. These experiments suggest that PMN adhere to subjunctional ligands on T84 cells in a CD11b/CD18-dependent fashion.

CD18 Antigens↗
PubMed1994

Prepulse inhibition of the startle response in mice: relationship to hearing loss and auditory system plasticity.

Prepulse inhibition was used with C57BL/6J (C57) mice to assess behavioral-perceptual correlates of previously demonstrated physiological changes in the central auditory system associated with age-related hearing loss. Normal-hearing CBA/CaJ (CBA) mice and DBA/2J (DBA) mice, which exhibit extremely rapid hearing loss, were also tested. Tone prepulse stimuli (S1s) were presented 100 ms prior to a startle-evoking noise stimulus (S2), and a decrease in startle amplitude served as the measure of startle modification. As high-frequency hearing declined in C57 mice between 1 and 12 months of age, the efficacy of lower-frequency S1s was significantly enhanced. CBA mice exhibited no age-related changes in startle modification. DBA mice exhibited changes similar to those observed in C57s but at an accelerated rate. The enhanced behavioral saliency of low and middle frequencies in C57 and DBA mice appears to be a consequence of neural plasticity in the central auditory system.

Animals↗
PubMed1994

Reconstitution of cultured intestinal epithelial monolayers with a mucosal-derived T lymphocyte cell line. Modulation of epithelial phenotype dependent on lymphocyte-basolateral membrane apposition.

In vivo, epithelial cells which line the intestine are intimately associated with lymphocytes, termed intraepithelial lymphocytes. Previous studies have demonstrated that intraepithelial lymphocytes are present in the uninflamed mucosa, and become especially prominent in various human enteropathies including coeliac disease, tropical sprue, dermatitis herpetiformis, and giardiasis. Using the intestinal crypt cell line T84, and a previously well-defined human mucosa-derived lymphocyte (MDL) line with phenotypic features similar to (but not specific for) intraepithelial lymphocytes, we describe a co-culture model to study the functional sequellae of MDL-T84 cell interactions in vitro. A co-culture method was defined which permitted reconstitution of the paracellular spaces of physiologically confluent epithelial monolayers with MDL. Such co-cultures thus mimicked the correct geometry of intraepithelial lymphocytes-epithelial cell interactions. The presence of physiologically positioned MDL brought about specific and dramatic effects on intestinal epithelial monolayer function. In a dose-dependent fashion, the presence of MDL significantly attenuated barrier function (expressed as a decrease in monolayer resistance), decreased epithelial electrogenic Cl- secretion, and modulated epithelial-neutrophil interactions. Such effects were not reproduced in monolayers similarly reconstituted with inert polystyrene beads equivalent in size to MDL. These MDL-elicited effects on epithelial function specifically required direct MDL apposition to the epithelial basolateral membrane. Furthermore, this specific form of MDL-epithelial basolateral contact released soluble factors which were able to confer the MDL-reconstituted phenotype on virgin epithelial monolayers in the absence of MDL. We have previously shown that many aspects of the MDL converted epithelial phenotype described here can be induced by IFN-gamma. While IFN-gamma, a cytokine produced by many lymphocytes including intraepithelial lymphocytes, was detectable in conditioned supernatants from co-cultures, it existed at concentrations insufficient to fully explain the physiologic effects observed here.

Cells, Cultured↗
PubMed1994

Small intestinal HIV-associated enteropathy: evidence for panintestinal enterocyte dysfunction.

To characterize the absorptive defect of AIDS enteropathy, we have used a D-xylose kinetic model of proximal absorption and correlated these findings with Schilling's test for cobalamin absorption, measurements of distal intestinal function. In addition, we compared findings between duodenal and jejunal biopsy and aspirations to determine whether additional information can be obtained by sampling the more distal site. Twelve consecutive patients with AIDS who had 3 to 14 loose bowel movements per day and two stool study results negative for pathogens, were admitted for study. D-xylose testing with oral and intravenous doses was used to determine the rate constants for D-xylose absorption, Ka, and the rate constant for nonabsorptive loss, Ko. Duodenal and distal duodenal-jejunal endoscopic aspirations and biopsies were also performed. Minimal histologic abnormalities were seen in either the proximal or distal biopsy sites. There were no significant differences in mucosal blunting, abnormalities of the enterocytes, lamina propria infiltrate, or presence of microorganisms between duodenal and distal duodenal-jejunal sites. Seventy-five percent had no identifiable pathogens. Ten of 12 patients had diminished Ka, elevated Ko, or both. Two patients had a normal Ka and Ko. Eight of 10 had an abnormal Schilling's test result. Percentage weight loss correlated negatively with Ka (r = 0.75; p = 0.013) and with Schilling's test results (r = 0.65; p = 0.043. Ka correlated positively with Schilling's test results (r = 0.82; p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗