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Biomedical subjects

P Sandor

Publications and source records attributed to P Sandor.

At least 55 records · Page 3Linked to original sources
PubMed1990

Disturbed hypothalamic blood flow autoregulation in the rat following hypophysectomy: a role of pituitary beta-endorphin?

The effect of hypophysectomy on hypothalamic blood flow autoregulation was studied in anesthetized, artificially ventilated rats. Local hypothalamic blood flow (HBF, H2-gas clearance method) was measured. Efficiency of autoregulation was tested by determining HBF during standardized hemorrhagic hypotension when systemic arterial pressure was lowered to 80, 60 and 40 mm Hg by consecutive, step-wise bleeding. HBF autoregulation was well maintained until 80 mmHg, but not completely at 60 and 40 mmHg arterial pressure in the sham-operated control group. In contrast, autoregulation was abolished at all levels in the hypophysectomized rats: HBF followed the changes in arterial pressure in these animals. Following hypophysectomy, the concentration of immunoreactive beta-endorphin (beta-EP) decreased drastically in plasma but remained unchanged in cerebrospinal fluid. Administration of beta-EP (200 pg/100 g b. wt.) to hypophysectomized rats by the intravenous route had no effect on autoregulation, while intracerebroventricular administration of the same dose restored autoregulation. The present findings suggest that the pituitary plays a role in hypothalamic blood flow autoregulation.

Animals↗
PubMed1990

Tourette syndrome: a follow-up study.

We describe a long-term follow-up study (1-15 years) of 33 patients with Tourette syndrome who were treated with pimozide (2-18 mg), haloperidol (2-15 mg), or no drugs. Both drugs produced comparable relief of symptoms at follow up; however, significantly more patients on haloperidol (eight of 17), compared with those on pimozide (one of 13), discontinued treatment (p less than or equal to 0.05). Haloperidol produced significantly more acute dyskinesias/dystonias than pimozide (p less than or equal to 0.03); otherwise, the adverse effect profile was similar for the two drugs. In particular, we found no increased incidence of ECG abnormalities in patients treated with pimozide. A prospective, randomized, double-blind crossover trial is required to determine whether there are significant differences in efficacy between pimozide and haloperidol in treatment of Tourette's disorder.

Adolescent↗
PubMed1989

Beta-endorphin and central control of arterial blood pressure during challenge of circulatory homeostasis.

A variety of neurotransmitters and neuropeptides appear to participate in the central control mechanisms of arterial blood pressure. Our knowledge of these mechanisms is limited as yet. In the present study the involvement of the opioid peptide beta-endorphin in circulatory homeostasis was studied. Under conditions in which beta-endorphin does not affect basal blood pressure and heart rate this peptide had a pronounced prohypotensive influence in normotensive rats. This was found for two conditions during which circulatory homeostasis was challenged. Firstly, during blood letting in a rat model employed to test blood pressure regulation during hemorrhage, and secondly, for the central hypotensive action of alpha-methyldopa. In the first model hypotension was produced by stepwise bleeding to respectively 80, 60 and 40 mmHg mean arterial pressure. Intracerebroventricular (i.c.v.) administration of an antiserum raised against beta-endorphin or of naloxone (s.c. or i.c.v.) caused a significant increase in the required bleeding volume, whereas an opposite action was observed after the injection of morphine (s.c.) or of beta-endorphin (i.c.v.). The role of beta-endorphin in the hypotensive action of alpha-methyldopa, given intracisternally (i.c.) was evaluated in conscious rats equipped with chronic cannulas. Pretreatment with the opiate antagonist naltrexone (i.c.) caused an inhibition of the hypotension and bradycardia induced by alpha-methyldopa. This effect of the receptor antagonist was mimicked by i.c. administration of a beta-endorphin antiserum. Taken together, these data point to a hypotensive influence exerted by endogenous beta-endorphin under conditions during which circulatory homeostasis are challenged.

Animals↗
PubMed1987

Influence of centrally administered alpha- and gamma 2-melanocyte-stimulating hormone on hypothalamic blood flow autoregulation in the rat.

The effect of intracerebroventricularly (i.c.v.) administered alpha-melanocyte-stimulating hormone (MSH) and gamma 2-MSH on hypothalamic blood flow autoregulation was studied in anesthetized rats at different levels of standardized arterial hypotension. Autoregulation was impaired upon i.c.v. administration of 5 micrograms/kg gamma 2-MSH while alpha-MSH caused no changes. Since this effect of gamma 2-MSH was identical to that produced by i.c.v. naloxone in the same model, gamma 2-MSH may be a functional antagonist of central opioid mechanisms participating in the control of cerebral blood flow autoregulation.

Animals↗
PubMed1987

Central opioid mechanisms and cardiovascular control in hemorrhagic hypotension.

Bleeding volume during standardized hemorrhagic hypotension was studied in anesthetized, artificially ventilated rats after specific stimulation or blockade of opiate receptor systems. Hypotension was produced by stepwise bleeding to 80, 60, and 40 mmHg systemic arterial pressure. Subcutaneous administration of morphine 15 min before the bleeding resulted in a decrease, whereas subcutaneous administration of naloxone resulted in a significant increase in the required bleeding volume. Intracerebroventricularly administered met-enkephalin, dynorphin, or specific antisera against these peptides caused no characteristic alterations of the bleeding volume although met-enkephalin and dynorphin caused a significant decrease at the 40 mmHg level. Bleeding volume, however, was markedly reduced when beta-endorphin was intracerebroventricularly administered and significantly elevated by intracerebroventricular administration of a diluted beta-endorphin antiserum. These data suggest that 1) opioid mechanisms are participating in the control of blood pressure and of bleeding volume during blood loss, 2) these control mechanisms might be activated centrally, and 3) beta-endorphin or a closely related peptide plays a major role in these control mechanisms.

Animals↗
PubMed1986

Continuous measurement of cerebral blood volume in rats with the photoelectric technique: effect of morphine and naloxone.

The validity of a photoelectric method for continuous cerebral blood volume (CBV) measurement was tested and modified for the rat's brain. A new way of introducing a miniature light source between the two hemispheres and fixing a light sensitive silicone blue cell to the outer surface of the parietal bone was developed. Light extinction factor of the rat's blood was determined experimentally (Eb rat = 1.38 +/- 0.15) in order to calculate absolute CBV value in this species, resulting in a 4.77 +/- 0.13 vol % absolute CBV value. Data obtained in anesthetized, artificially ventilated rats by simultaneous recording of CBV and local cerebral blood flow (H2-gas clearance technique) show that local hypothalamic blood flow decreased significantly after morphine (1.0 mg/kg s.c.), while total CBV remained unchanged. Opiate receptor blockade with naloxone (1.0 mg/kg s.c.) on the contrary, as well as naloxone and morphine administration, caused no change in local hypothalamic blood flow, but resulted in a significant increase of total cerebral blood volume.

Animals↗
PubMed1983

Variations in drug free fraction during alcohol withdrawal.

1 Free fractions of diazepam, propranolol and warfarin were determined in 15 male chronic alcoholics in alcohol withdrawal. 2 On admission the mean free fraction of diazepam was 25% above and propranolol 44% below the limits of normal range, while the mean warfarin free fraction was in high normal range. One week later mean free fraction of diazepam declined by 20% while propranolol and warfarin increased by 24% and 19% respectively (P less than 0.05). 3 Propranolol free fraction and alpha 1-AGP concentrations were highly correlated (linear r = -0.83, P less than 0.001). In contrast the sources of variation in diazepam and warfarin free fraction were more complex and less certain. 4 Statistically significant changes of drug free fractions in serum of chronic alcoholics were observed during alcohol withdrawal. The extent and direction of these changes differed for various classes of drugs and their potential causes appear to be quite different. 5 Clinically important changes in drug effect may be present acutely, within the dosing interval, as a result of altered drug binding. These are more likely when the clinical response is closely related to drug concentration and will occur within the dosing interval due to larger fluctuations in free drug concentration, even though the average free drug concentration will remain unchanged. 6 Total drug level changes will be observed during alcohol withdrawal even in absence of detectable changes of drug metabolism.

Adult↗
PubMed1983

Lecithin in the treatment of Gilles de la Tourette's syndrome.

Five patients with Tourette's syndrome were administered a mean dose of 512 mg/kg per day of oral lecithin. None of the patients exhibited sustained clinical improvement in symptom severity. No significant changes in serum prolactin or growth hormone were observed during lecithin administration.

Administration, Oral↗
PubMed1982

How adequate are warnings and first and instructions on consumer product labels?: an investigation.

A random survey of 1,019 household product labels was conducted by the NYPCC in retail markets in the New York metropolitan area. The purpose of this survey was to determine whether household product labels adequately define what a consumer should do in the event of a poisoning. The quality of poison warnings, first aid instructions, and the extent of ingredients listed were evaluated. In a qualitative and quantitative analysis of 1,019 household product labels it was found that 85% of the product labels had inadequate first aid information. Of these, 53% demonstrated insufficient labeling, 6% had incorrect, potentially harmful instructions, and in 26% of the cases instructions were absent entirely. In addition, 31% of these 1,019 products had no ingredients' list.U

Consumer Product Safety↗
PubMed1981

Effect of short- and long-term alcohol use on phenytoin kinetics in chronic alcoholics.

Phenytoin kinetics during long-term alcohol use and withdrawal were studied in 11 male alcoholics with a history of withdrawal seizures and no evidence of chronic liver disease. Ethanol, 20% v/v, was given for 6 days after admission to maintain the blood alcohol level between 500 and 800 mg/l and phenytoin suspension, 150 mg, was given orally or intravenously (on three occasions) every 12 hr for 20 days. The mean (+/- SD) total phenytoin clearance in 9 of 11 subjects was 0.023 +/- 0.006 l/kg/hr during the alcohol ingestion period. Clearance rose to 0.033 +/- 0.013 l/kg/hr (P less than 0.05) during alcohol withdrawal. Total steady-state concentration after 3 wk ranged from 3.4 to 29.9 mg/l, while the weight-corrected dose range was only 3.7 to 5.5 mg/kg/day. Inter- and intra-subject variation in bioavailability was small (0.93 to 1.03). Phenytoin free fractions ranged from 9.09% to 17.75% and changes in total and free phenytoin concentration correlated (r2 = 0.92, P less than 0.001). The data are compatible with the hypothesis that increased phenytoin clearance during alcohol withdrawal is due to the increased metabolic rate of the drug secondary to enzyme induction by ethanol, which becomes unmasked on cessation of drinking. In most alcoholics standard-dose phenytoin (300 mg/l) will induce lower than usual plasma concentrations.

Administration, Oral↗
PubMed1981

Development of optimal treatment tactics for alcohol withdrawal. I. Assessment and effectiveness of supportive care.

The relative roles of supportive care and pharmacotherapy in the treatment of alcohol withdrawal are not established. A reliable and validated withdrawal severity assessment scale (Clinical Institute Withdrawal Assessment for Alcohol, CIWA-A) was developed to assess initially and then follow the clinical course of 38 hospitalized chronic alcoholics requiring hospitalization for withdrawal but without serious concurrent medical or surgical problems. Supportive care, consisting of standardized half-hourly patient assessment (CIWA-A) and nursing care, was used as the initial treatment for all patients. Twenty-eight (74%) patients with clinical supportive care successes within 8 hours, 75% within 4 hours. Two responding patients subsequently developed evidence of withdrawal at 48 hours (hallucinations) and 72 hours (seizure). Ten patients (26%) did not respond to supportive care and required drug therapy in addition. Responders to supportive care drink more by history and have less severe liver disease than nonresponders. There are no other apparent predictors of the patients who require drug therapy. Three quarters of hospitalized patients, without serious medical complications, in alcohol withdrawal respond to intensive supportive care. However, pharmacotherapy is essential for nonresponders and patients with hallucinations.

Adolescent↗