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Biomedical subjects

M Horowitz

Publications and source records attributed to M Horowitz.

At least 595 records · Page 33Linked to original sources
PubMedDate not supplied

Pituitary adenylate cyclase activating polypeptide (PACAP) reduces food intake in mice.

Pituitary adenylate cyclase activating peptide (PACAP) is a peptide that is present in the hypothalamus and other areas of the rat brain. This study demonstrates that PACAP reduces food intake after intracerebroventricular injection in food-deprived mice. Behavioral analysis suggests that this decrease in food intake is, in part, compensated for by an increase in other behaviors. Pituitary adenylate cyclase activating peptide also was demonstrated to antagonize increased food intake resulting from administration of neuropeptide Y. Thus, PACAP joins a growing list of neuropeptides involved in the central regulation of food intake.

Animals↗
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The effect of ovarian steroids and photoperiod on body fat stores and uncoupling protein 2 in the marsupial Sminthopsis crassicaudata.

To determine the effects of photoperiod and ovarian steroids on fat stores in the marsupial S. crassicaudata, animals were ovariectomised (OVX) or sham operated, and maintained under either short-day (SD) or long-day (LD) photoperiods for 104 days. Photoperiod had no effect on body weight in the sham animals. In the LD OVX animals, body weight fell and remained below baseline for about 45 days, whereafter it returned to baseline. In contrast, body weight of SD OVX animals increased over the first 45 days then returned to baseline. Tail width (a reflection of body fat stores) increased in both sham and OVX animals exposed to SD. When exposed to LD, tail width increased only in the OVX animals. There was no effect of either photoperiod or OVX on total cumulative energy intake. Leptin mRNA expression was increased in the LD OVX animals compared to the shams. Photoperiod had no effect on UCP2 mRNA expression in any tissue; however, OVX decreased UCP2 mRNA expression in muscle. These data indicate that in S. crassicaudata: (a) fat mass increases in response to both SD photoperiod and OVX and they have additive effects; (b) the effects of photoperiod on fat mass are mediated by both gonadal steroid dependent and independent mechanisms; (c) alterations in UCP2 mRNA expression may mediate the effect of OVX, but not photoperiod; and (d) UCP2 mRNA is differentially regulated in muscle and fat.

Adipose Tissue↗
PubMedDate not supplied

Selective processing of visual alcohol cues in abstinent alcoholics: an approach-avoidance conflict?

When symptomatic individuals selectively attend to emotionally relevant stimuli, the ability to shift attention away from such material is impaired. Subjects may, however, seek to avoid further processing of these stimuli, which would facilitate attentional shifts. This was examined in a group of abstinent alcoholics' responses to stimuli related to alcohol. Eight alcohol and eight neutral words served as cues in a covert attention task. The cues were either valid (2/3 of trials) or invalid (1/3 of trials) indicators of where a response target would appear after 100 or 500 milliseconds. The short interval was expected to interact with an initial approach toward the alcohol word, while the long interval would interact with a subsequent avoidance of the stimulus. As predicted, the alcoholics showed slower reaction times (RTs) to targets invalidly cued by alcohol words in the short interval, reflecting increased difficulties to shift attention. However, the alcoholics demonstrated faster RTs to targets invalidly cued by the alcohol words in the long interval. This indicates that the alcohol cue elicited emotional associations that, subsequent to initial stimulus identification, trigger an interrupting function of the attentional system.

Adult↗
PubMedDate not supplied

Antral compensation after proximal gastric vagotomy.

Proximal gastric vagotomy (PGV) has little impact on the normal pattern of solid gastric emptying, despite denervation of the proximal two thirds of the stomach and loss of the proximal gastric pump. In four healthy volunteers and four patients with PGV, we investigated the possible compensatory mechanisms that may come into play after proximal denervation of the stomach. We measured antropyloroduodenal motility with a 10-lumen sleeve/side-hole catheter for 180 minutes after ingestion of a dual-isotope radiolabeled mixed liquid/solid meal. Patients with PGV exhibited faster liquid emptying, but the rate of solid emptying was similar to that in healthy volunteers. The frequency of propagated antropyloric pressure wave was similar between the two groups, but patients with PGV exhibited less isolated pressure waves in the proximal antrum. The amplitude and duration of pressure waves recorded in the distal antrum were significantly increased in the PGV patients as compared to healthy volunteers. Although the pattern of propagated antral contractions and solid gastric emptying remains unchanged after PGV, there is an increase in the amplitude and duration of distal antral contractions, which may compensate for loss of proximal gastric pumping mechanisms.

Adult↗
PubMedDate not supplied

A benign polymorphism in the aspartoacylase gene may cause misinterpretation of Canavan gene testing.

We found normal individuals whose aspartoacylase gene Y231X mutation site consistently gave no signal in a primer extension assay. We determined the nucleotide sequence of the relevant region of the gene in those individuals, and found a new allele with a thymidine residue at the mutation site instead of a cytidine. Since both TAC and TAT code for tyrosine, this sequence polymorphism has no effect on the amino acid sequence of the ASPA protein. We found the relative frequencies of the 693C and the 693T alleles in the tested population to be 0.75 and 0.25 respectively.

Amidohydrolases↗
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Life event questionnaires for measuring presumptive stress.

Cumulative stress from the impact of life events has become an important variable in psychosomatic and psychological research. This article provides both short and long life events questionnaires that add to incidence information the remoteness or recency in time of a given experience. In the weight assignment system that leads to a single presumptive stress score, events remote in time have less influence than recent events. The reliability of weight assignment was checked in subject groups that differed by sex, age, and status. Women weighted life events as more stressful than did men; other differences in groups were less important. In spite of the sex differential, review of these data suggests use of the same weight assignments for all subgroups rather than differential weighting by sex and age. Reliability was also checked by test and retest methods in contrast to common sense expectation, a disappointingly low level of reliability was found. The implications for investigative use of life events questionnaires are discussed.

Adult↗
PubMedDate not supplied

A scale for measuring the occurrence of positive states of mind: a preliminary report.

It may be as important to measure a failure to achieve desirable states of mind as it is to measure negative moods. The proposed measure of positive states of mind was found to be internally consistent, sensitive to degrees of life stress, well accepted, quick to administer, and amenable to use as a repeated measure in longitudinal studies. Data from 187 men and women in a college student sample are reported.

Affect↗
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Additional validation of a scale to assess positive states of mind.

OBJECTIVE: Numerous studies have linked stress and negative states to adverse health outcomes. However, in addition to engendering negative states, stress may impair capacities to experience positive states. Such failure to experience positive states may represent a risk factor for poor health in and of itself. The research reported here examines a brief, easily repeated measure of positive states of mind (PSOM) including: focused attention, productivity, responsible caretaking, restful repose, sharing, sensuous nonsexual pleasure, and sensuous sexual pleasure. METHOD: The PSOM Scale and measures of psychological distress, stress, and physical symptoms were administered in four independent samples: two samples of college students and two samples of pregnant women, one undergoing a potentially stressful medical procedure (amniocentesis). The relationship between PSOM scores and several conceptually related, but distinct, psychological variables was examined, controlling for the effect of social desirability where necessary. RESULTS: The range of scores on the items of the PSOM indicated that impairments of ability to have the relevant experiences did occur in the subjects who were experiencing stress. The overall PSOM Scale score consistently showed an inverse relationship with anxiety and with indicators of stress. In addition, lower scores on the PSOM Scale were associated with more somatic symptomatology. CONCLUSION: The results provide evidence that positive states of mind are linked to negative psychological states and are responsive to stressful events. The PSOM scale provides a useful, brief measure for research in stress and health.

Adaptation, Psychological↗
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Use of the AO/ASIF external fixator in children.

Sixteen children with 20 fractures were treated with the AO/ASIF tubular fixator (Synthes, Ltd., Paoli, PA). Most of the fractures were open, but the fixator was also used in closed fractures in children with head injuries or other forms of trauma. There were 10 fractures of the tibia, 5 of the femur, 3 of the pelvis, and 2 involving the humerus. Average follow-up was 26 months, with the fixators in place for an average of 7 weeks. Fracture union occurred after an average of 16 weeks. This system is easier to apply, less complicated, and lighter than other types of fixators.

Adolescent↗
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Motor mechanisms associated with slowing of the gastric emptying of a solid meal by an intraduodenal lipid infusion.

The aim of this study was to define better the motor phenomena associated with the slowing of gastric emptying by a duodenal lipid infusion. Antral, pyloric and duodenal motility were recorded in 10 healthy subjects with a manometric assembly which incorporated multiple perfused side-holes and a sleeve sensor positioned astride the pylorus. The gastric emptying of a standard solid meal and the distribution of the ingesta between the proximal and distal stomach were monitored with a radionuclide technique. A triglyceride emulsion was infused into the duodenum for 45 min once 25% of the meal had emptied. The infusion caused significant slowing in the rate of gastric emptying (P less than 0.01). This slowing in gastric emptying was associated with the suppression of pressure waves in the distal antrum (P less than 0.01) and proximal duodenum (P less than 0.01), the induction of pressure waves isolated to a narrow pyloric segment (P less than 0.01), and a redistribution of ingesta from the distal to proximal stomach. These findings suggest that pressure waves isolated to the pylorus, changes in the intragastric distribution of ingested food, and changes in proximal duodenal motility may all act in concert with changes in antral motility to regulate the gastric emptying of solids.

Adult↗
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The effect of chilli on gastrointestinal transit.

The effects of chilli on gastrointestinal transit (gastric emptying, orocaecal transit, whole gut transit) were evaluated in eight healthy volunteers. In each subject, gastrointestinal transit of a standard test meal was measured on two separate days. On one of these occasions, 20 g of chilli powder was added to the meal. Gastric emptying was quantified with a radioisotopic technique, orocaecal transit by measurement of breath hydrogen concentrations and whole gut transit by counting the number of radio-opaque markers in the stool. The rate of gastric emptying was slower (P less than 0.05) and whole gut transit was faster (P less than 0.02) after the meal containing chilli, compared with the other meal. There was no significant difference in orocaecal transit. These results show that ingestion of chilli is associated with significant effects on gastric emptying and intestinal transit.

Adult↗
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Stimulation of pyloric contractions by intraduodenal triglyceride is persistent and sensitive to atropine.

Intraduodenal lipid infusion stimulates phasic and tonic pyloric contractions and suppresses antral contractions. This study determined: (i) whether this response is sustained over 90 min; and (ii) the role of muscarinic mediation of this response. Antropyloroduodenal motility was recorded in 17 healthy volunteers with a sleeve/sidehole manometric assembly. Subjects received either a 90 min intraduodenal infusion of saline or triglyceride (20% Intralipid) at a rate of 1 mL/min; 30 min after the start of this infusion, the eight subjects who received triglyceride were given intravenous atropine 15 micrograms/kg over 30 s, followed by a maintenance infusion of 4 micrograms/kg/h until the study was completed. Intraduodenal triglyceride infusion stimulated isolated pyloric pressure waves consistently, producing a median rate of 2.4 per min after 30 min of triglyceride infusion, compared with a median rate of 0 per min pre-infusion. In intravenous saline studies, there was a reduction (P < 0.05) in the median rate of isolated pyloric pressure waves to 1.3 per min at 90 min, when compared with pyloric pressure waves at 30 min. Atropine reduced isolated pyloric pressure waves to a median rate of 0 per min, significantly different from preatropine (P < 0.01) and from intravenous saline studies (P < 0.0001). These results indicate that the phasic pyloric response to intraduodenal lipid persists during 90 min stimulation, albeit with significant attenuation. In humans, muscarinic cholinergic blockade prevents the occurrence of triglyceride stimulated localized pyloric contractions.

Adult↗
PubMedDate not supplied

Stereospecific effects of tryptophan on gastric emptying and hunger in humans.

The amino acid tryptophan (tryp) is a potent inhibitor of gastric emptying in both animals and humans. Animal studies suggest that this effect may be specific for the L-enantiomer. The effects of D- and L-tryptophan on gastric emptying, intragastric distribution and appetite in humans were evaluated. Ten volunteers ingested 300 mL of either L-tryp (50 mmol/L), D-tryp (50 mmol/L) or normal saline labelled with 99mTc sulfur colloid on three occasions, separated by between 3 and 7 days. Hunger and fullness were measured with a visual analogue scale at -2, 15, 30 and 60 min after ingestion of each drink. Saline emptied faster from the stomach than both L-tryp and D-tryp (P < 0.05) and D-tryp emptied faster than L-tryp (P < 0.005). Emptying from the proximal stomach was fastest for saline (P < 0.05) and faster for D-tryp than L-tryp (P < 0.005). Emptying from the distal stomach was faster for saline than both D- and L-tryp (P < 0.05). A reduction in hunger (P < 0.05) and a non-significant trend for an increase in fullness were observed after all three drinks. At 60 min, fullness was greater after L-tryp than after ingestion of D-tryp (P < 0.01). These observations indicate that the effect of tryptophan on gastric emptying in humans is stereospecific, consistent with the concept that stereospecific receptors for tryptophan exist in the human small intestine.

Adult↗
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The effects of abdominal irradiation for seminoma of the testis on gastrointestinal function.

To evaluate the long-term effects of abdominal irradiation for the treatment of seminoma of the testis on gastrointestinal function, 15 randomly selected patients who had been treated for stage I seminoma of the testis 2-10 years previously had the following parameters of gastrointestinal function evaluated: gastrointestinal symptoms; absorption of bile acid; vitamin B12; lactose and fat; gastric emptying; small intestinal and total gut transit; and intestinal permeability. Results were compared to those obtained in 18 normal volunteers. There was an increased prevalence of gastrointestinal symptoms (P < 0.01) in the patients and stool frequency was above the control range in two of them. Gastric emptying was faster (P < 0.01) in the patients. There were no significant differences in vitamin B12, bile acid, lactose or fat absorption, small intestinal transit or whole gut transit between the two groups, although faecal fat excretion was greater than the control range in three of the patients. At least one parameter of gastrointestinal function was abnormal in 11 of the 15 patients. Patients with right-sided seminoma had a greater bowel frequency when compared to those with left-sided seminoma (P < 0.05). We conclude that mild abnormalities in gastrointestinal function occur frequently when abdominal irradiation is used to treat stage I seminoma.

Abdomen↗
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Coping with grim news from genetic tests.

Clinicians need to recognize and respond to stress response syndromes that may occur after patients have received genetic testing for inherited susceptibility to serious diseases. For patients whose test results convey high risk, increased attention to prevention, surveillance, and early medical treatment may be possible, but the grim news may also lead to a formation of symptoms ranging from extreme denial to unwelcomed intrusive ideas and feelings. Genetic counseling alone may be insufficient for some people, and evaluation and psychotherapy for stress response syndromes may be indicated for them.

Adaptation, Psychological↗
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Thermoregulation under conditions of impaired body fluid/osmotic balance in mammals.

The state of body hydration has a marked effect on thermoregulation during heat stress. Heat stressed hypohydrated mammals reduce evaporative cooling and metabolic rate, and allow their body temperature to rise. This outcome is not a failure in thermoregulation, but readjustment, leading to improved physical avenues for heat dissipation and water conservation. The modulation of the thermoregulatory system is mostly central. This is exhibited by decreased sensitivity of the thermoregulatory integration center and by an upward shift of temperature thresholds for heat dissipation activities. New evidence suggests alterations in effector organs as well. In the euhydrated body, hyperosmolarity and hypovolemia, the consequences of hypohydration, via activation of osmoreceptors and low pressure baroreceptors, induce the same thermoregulatory responses as hypohydration does. Single unit studies on hypothalamic slices provide a neuronal basis for osmoregulation-thermoregulation interaction. The possible role of arginine vasopressin (AVP) as a central modulator in this interaction is discussed.

Animals↗
PubMedDate not supplied

Mechanical and metabolic performance of the rat heart: effects of combined stress of heat acclimation and swimming training.

Although the individual effects of heat acclimation and swimming exercise on cardiovascular reserve and efficiency have been studied, the relative and cumulative effects of these interventions have not. Myocardial developed force, coronary flow (CF), and oxygen consumption during baseline conditions and during pacing-induced tachycardia were therefore studied in isolated perfused hearts from four groups of rats: normothermic sedentary (C), heat acclimated sedentary (AC), normothermic swimmers (CS), and heat acclimated swimmers (ACS). Normothermic temperature was 24 degrees C. Heat acclimation was attained by continuous exposure to 34 degrees C for one and two months. Swimmers had two daily 75 minute sessions for five days a week with water temperatures of 33-35 degrees C and 36-38 degrees C for CS and ACS rats, respectively. After one month AC animals showed a remarkable decrease in O2 consumption. In contrast, ACS increased both O2 consumption and the maximal isometric force generated. After two months, O2 consumption of AC rats continued to be low. The heart failed to restitute the force developed at high pacing frequency. In these rats CF was remarkably low and remained unchanged with increased pacing. In contrast ACS maintained the ability to develop force at all pacing rates at a level similar to that of the normothermic C and ACS rat hearts, but at high oxygen cost. The data suggest that the AC heart is more efficient but cannot meet demands at high pacing rates. In contrast, swimming in the heat improved performance of ACS temporarily, without decreasing the metabolic rate.

Acclimatization↗