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J Feldman

Publications and source records attributed to J Feldman.

At least 181 records · Page 10Linked to original sources
PubMed1989

[From alpha 2-adrenergic to endazoline receptors].

Studies of the central hypotensive mode of action of the imidazolines of which clonidine is the leading molecule suggest the presence of non-catecholamine binding sites called imidazoline receptors. Our group showed that neither the endogenic ligand of alpha-adrenergic receptors, noradrenaline, nor any other tested catecholamine or phenylethylamine have hypotensive effects at the site of action of all imidazolines, the lateral reticular nucleus of the brainstem. In addition, a population of membrane binding sites which take up labelled clonidine and which are insensitive to noradrenaline have been demonstrated in the lateral reticular nucleus. An endogenic non-catecholamine substance whose structure is currently under identification and which is recognised by these receptors has been isolated from the brain tissues of various mammals. All this experimental evidence supports the hypothesis that the hypotensive effects of imidazoline-like substances are related to their action on brainstem receptors specific to this endogenic ligand which we propose to call endazoline. Rilmenidine, which has a chemical structure similar to that of the imidazolines, has a higher relative selectivity for the imidazoline binding sites than the reference molecule (clonidine). A central antihypertensive agent without the classical sedative effects associated with this class of drug could result. A study of the structure-activity relationship is needed to confirm this hypothesis.

Animals↗
PubMed1989

Correlation between the inhibitory effect on catecholaminergic ventrolateral medullary neurons and the hypotension evoked by clonidine: a voltammetric approach.

Neuronal activity was monitored in vivo by differential voltammetry, an electrochemical technique measuring the metabolism of catecholamines. This technique was used to determine the influence of low doses of clonidine (starting from 2 micrograms/kg i.v.) on the activity of the catecholaminergic neurons of the nucleus reticularis lateralis region, site of its hypotensive action, and of the locus ceruleus, which is involved in its sedative effect. There was a correlation between the hypotensive effect of low doses of clonidine (2, 5 and 10 micrograms/kg i.v.) and the decrease of the neuronal metabolic activity within the ventrolateral medulla, whereas only higher doses of clonidine (50 micrograms/kg i.v.) decreased the metabolic activity in the locus ceruleus. Thus, we demonstrate in vivo differences in sensitivity toward the same drug of two different neuronal structures that are involved in the regulation of the cardiovascular and wakefulness functions, respectively. The present study also shows that clonidine has a preferential action on a medulla oblongata region that contains imidazoline-preferring receptors, namely the nucleus reticularis lateralis region, rather than on the locus ceruleus region, that contains mainly alpha-2 adrenoceptors.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

Differences in the ability of yohimbine to antagonize the hypotensive effect of clonidine in normotensive and spontaneously hypertensive anesthetized rats.

Low doses of yohimbine (1, 5 and 10 micrograms/kg), injected i.c.v. to spontaneously hypertensive rats as pretreatment, prevented the hypotensive effect of clonidine (standard dose of 5 micrograms/kg). At the opposite, the same doses of yohimbine did not influence the hypotensive effect of clonidine in control groups of normotensive animals (Wistar-Kyoto rats) treated under the same conditions. Interestingly, we observed that the central hypotensive effect of clonidine was greater in the hypertensive animals than in normotensive rats. Thus, we concluded that the central hypotensive effect of clonidine is affected by very low doses of yohimbine in spontaneously hypertensive rats and not in normotensive control animals. The yohimbine insensitive effect might be due to the action of clonidine on one type of medullary receptors specific to the imidazoline structure. On the physiopathological side, it seems therefore that, in hypertensive animals, there is a yohimbine sensitive mechanism, perhaps an alpha-2 adrenoceptor stimulating effect, which is nonexistent in normotensive animals.

Animals↗
PubMed1988

A controlled trial of d-fenfluramine in bulimia nervosa.

A double-blind, placebo-controlled trial of d-fenfluramine in bulimia nervosa was undertaken in order to assess its efficacy in controlling bulimic behavior and relieving more general symptoms. A high proportion of the patients evaluated were reluctant to enter the drug trial in spite of the offer of additional supportive psychotherapy and counselling on dietary control. Moreover, 17 out of the 42 enrolled patients withdrew halfway through the 12 week trial. Were it not for this high rate of defaulting, there might be clearer support for the efficacy of d-fenfluramine in reducing the frequency of overeating and self-induced vomiting in these bulimic patients. An unexpected finding was that among the noncompleters, those on d-fenfluramine had experienced relief of their bulimic symptoms. The persistence of depressive symptoms and features of the eating disorder probably contributed to the noncompleters leaving the trial. Reassuring findings were the absence of weight loss and serious unwanted effects from d-fenfluramine. By itself, d-fenfluramine did not benefit some of the patients with severe bulimia nervosa, but it may yet prove a useful adjunct to psychological treatments.

Adolescent↗
PubMed1988

A cohort study of alkaloidal cocaine ("crack") in pregnancy.

The recent dramatic increase in the use of alkaloidal cocaine ("crack") has led to concern about possible deleterious fetal effects associated with its use during pregnancy. Crack, which is not destroyed by heating, can be smoked, and delivers a large quantity of cocaine to the vascular bed of the lung, producing an effect similar to that from intravenous injection. To describe the association of crack use with pregnancy outcome, we conducted a retrospective matched cohort study of 55 women who admitted to the use of crack during pregnancy and 55 non-drug-using women who delivered during the same period. The groups were matched for age, parity, socioeconomic status, alcohol use, and presence or absence of prenatal care. A significantly larger number of women using crack delivered at 37 weeks or earlier (50.9 versus 16.4%; P = .001). Crack-exposed infants were 3.6 times more likely to have intrauterine growth retardation (P less than .006) and 2.8 times more likely to have a head circumference less than the tenth percentile for gestational age (P less than .007). Premature rupture of the membranes was 1.8 times more common in the crack group (P less than .03). Sixty percent of crack-using mothers received no prenatal care. Abnormal neurobehavioral symptoms were present in a minority of infants and were usually mild.

Adult↗
PubMed1987

The blood pressure effects of alpha-adrenoceptor antagonists injected in the medullary site of action of clonidine: the nucleus reticularis lateralis.

We administered a series of alpha-blocking drugs to the nucleus reticularis lateralis (NRL) of the medulla oblongata, the main site for the hypotensive action of clonidine. These experiments were performed on pentobarbital anaesthetized cats. Drugs were injected through a needle which was stereotaxically inserted. Prazosin (6 nmol) was hypertensive (MBP = +25 +/- 8%), corynanthine had no effect and AR-C239 (7 nmol), another alpha 1-blocker, was hypotensive (MBP = -16 +/- 3.5%). The alpha 2-blockers, yohimbine and idaxozan, were hypotensive. The blood pressure effects of alpha-blocking drugs directly microinjected in the nucleus reticularis lateralis cannot be simply related to their selectivity for a particular subtype of alpha-receptors.

Adrenergic alpha-Antagonists↗
PubMed1987

Effect of insulin excess and deficiency on norepinephrine turnover in rats.

To examine whether insulin enhances norepinephrine (NE) turnover, an index of sympathetic nerve activity, the effects of excess insulin and streptozotocin (STZ) induced insulin deficiency were examined in Sprague-Dawley rats. Exogenous insulin caused hyperphagia and elevated (approximately 300%) urinary epinephrine excretion, but did not alter cardiac NE content or turnover. STZ-induced insulin deficiency caused hyperglycemia and hyperphagia, but also did not alter cardiac NE content or turnover. Insulin deficiency reduced hepatic NE content 18%, but did not affect NE turnover or content of kidney or spleen. These data do not support the hypothesis that insulin influences cardiac sympathetic nerve activity in rats.

Animals↗
PubMed1987

Investigations of factors influencing the prognosis of colon cancer.

Six hundred sixty patients from Downstate and Hackensack Medical Centers were restaged and reviewed to establish correlations with survival using Cox's proportional hazards model. Age, sex, tumor size, and total nodes examined in patients with involved nodes did not correlate with survival. Tumor depth, number of involved nodes, and total nodes examined in patients with uninvolved nodes did correlate with survival. Patients with metastatic invasion into an adjacent organ with uninvolved nodes had an excellent 5 year survival rate compared with patients who had full-thickness invasion into the serosa with uninvolved nodes. These observations need to be confirmed. The relationship of some of these factors to currently used staging systems has also been discussed.

Colonic Neoplasms↗
PubMed1987

Relationship of vaginal pH and Papanicolaou smear results to vaginal flora and pregnancy outcome.

Prematurity is a major cause of perinatal morbidity. Studies have implicated components of the vaginal flora in the etiology of some cases of preterm birth. Current scoring systems do not include factors which directly reflect the vaginal flora. Since Papanicolaou smears and the vaginal pH may be affected by the vaginal flora and are easy tests to perform, we studied their relationship to vaginal flora and pregnancy outcome. Among 231 patients, those with a vaginal pH greater than or equal to 4.4 were significantly more likely to carry Trichomonas vaginalis (P less than 0.03); Bacteroides species (P less than 0.01), and Mycoplasma hominis (P less than 0.001), and to have premature rupture of the membranes (P less than 0.01), and preterm rupture of the membranes (P less than 0.05). Patients with atypia reported on Papanicolaou smear more frequently carried M. hominis (P less than 0.01), and had premature rupture of the membranes (P less than 0.01). Although the high sensitivity and negative predictive value of those tests may make them useful additions to current scoring systems, their low specificity prevents them from being independent predictors of risk.

Female↗
PubMed1987

Pathologic effects of ESWL on canine renal tissue.

The introduction of extracorporeal shock wave lithotripsy (ESWL) has provided an avenue for dealing with many urinary stones noninvasively. The margin of safety for the kidney during shock wave administration is largely undefined. A pilot study was performed where six kidneys in five female mongrel dogs were shocked. Group A kidneys were given 1,776, 4,500, 6,000, or 8,000 shocks, respectively, at 18-24 kV. Group B kidneys received 1,600 and 8,000 shocks (18-24 kV). The number of shocks per electrode ranged from 500 to 4,538 and averaged 2,490. The dogs were sacrificed forty-eight to seventy-two hours (Group A) or twenty-eight to thirty-two days (Group B) post-treatment. Modest damage (hematoma and/or interstitial hemorrhage) was noted in all kidneys. Evidence of permanent change (fibrosis) was noted in both Group B kidneys. Complete necrosis of the kidney was not seen after administration of 8,000 shocks. These preliminary data indicate that lithotripsy can, in some circumstances, produce renal damage in the canine model.

Animals↗
PubMed1987

Reduction of asthenopia after accommodative facility training.

Five patients reporting asthenopia secondary to accommodative deficiencies underwent automated accommodative facility training. A matched-subjects, crossover design was used to control for placebo effects. All patients receiving automated accommodative training showed a marked increase in accommodative amplitude along with a concurrent reduction of asthenopia. Decreases of blur and increases of reading time were the most frequently reported changes by patients. This experiment shows the effectiveness of automated accommodative training in reducing asthenopia and improving accommodative facility.

Accommodation, Ocular↗
PubMed1987

Central cardiovascular effects of a noncatecholamine endogenous ligand for clonidine receptors.

Cats and rats anaesthetized with pentobarbital were used to study the central cardiovascular effects of the clonidine displacing substance (CDS). The potential influence of centrally applied CDS on the cardiovascular effects of clonidine was also investigated in both species. CDS is a brain substance which is not a catecholamine (CA) and which displaces completely the binding of tritiated clonidine to brain membranes. It was observed that direct application of CDS unilaterally to the nucleus reticularis lateralis (NRL), a privileged site of action for clonidine in the cat, increases markedly the mean arterial pressure (MAP) and does not affect the heart rate (HR). CDS also causes hypertension when infused into the left vertebral artery in the cat. When MAP reverted to baseline, the hypotensive effect of clonidine given by the same route is significantly prevented. In rats, the intracisternal administration of CDS increased MAP without affecting HR. Here also, the CDS pretreatment antagonized the hypotensive effect of i.v. clonidine as compared with control animals. It is concluded that CDS is an endogenous non-catecholamine ligand for receptors involved in the hypotensive effect of clonidine. This substance interferes with clonidine on these receptors. It is a candidate as a neuromodulator or a neurotransmitter involved in the blood pressure regulation at least in the NRL region.

Animals↗
PubMed1987

Training perception of air flow obstruction in asthmatics.

Eighteen asthmatics, aged 7 to 43, rated their breathing on a scale of 0 to 5 (worst to best). They were then informed of their predicted normal peak expiratory flow rate (PEFR) and instructed in proper PEFR measurement. Each subject then estimated and measured PEFR under physician supervision and subsequently rated breathing, estimated and measured PEFR at home twice daily recording the observations. At the initial home observation, the correlation coefficient (r1) between estimated and measured PEFR was .98. After ten observations r1 was greater than or equal to .97 in all 18 subjects (group mean .99). The r1 remained unchanged in those subjects who completed 28 and 42 observations. The r1 was .98 when only the observations where measured PEFR was less than 20% predicted were considered, demonstrating the validity of the relationship during abnormal expiratory flow. Multiple regression analysis showed no significant trend in the difference between estimated and measured PEFR over time after the initial observation. Of 12 subjects, 4 were significant underestimators of PEFR and 3 were overestimators, but the magnitude of either tendency was relatively small. The correlation coefficient (r2) between a subjective verbal breathing score and measured PEFR ranged from -.23 to .92 on an individual basis over the three time periods, with statistically significant group mean values of .37, .39, and .45 at 10, 28, and 42 observations, respectively. The r2 for observations where measured PEFR was abnormal was only .14 and not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Relation of private or clinic care to the cesarean birth rate.

The rising rate of cesarean births in the United States has been the focus of academic attention as well as attention from the media during the past decade. Although there is a consensus about the indications for cesarean delivery that have led to the increased rate (dystocia, malpresentation, fetal distress, and previous cesarean delivery), the influence of other key factors, such as whether the patient received care from a private physician or through a hospital clinic, has not been established. In a review of 65,647 deliveries in four Brooklyn hospitals between 1977 and 1982, we found that private physicians performed significantly more cesarean sections than house officers and attending physicians. Private patients giving birth to their first child were significantly more likely than clinic patients to undergo cesarean delivery if dystocia, malpresentation, or fetal distress was diagnosed, and private patients with one or more previous deliveries were significantly more likely to undergo cesarean delivery if dystocia or malpresentation was diagnosed. Private patients had fewer perinatal deaths, which were concentrated among infants with birth weights under 2000 g, but the infants of private patients had a significantly higher rate of low Apgar scores and birth injuries than the infants of clinic patients.

Adult↗