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Biomedical subjects

S Feldman

Publications and source records attributed to S Feldman.

At least 289 records · Page 16Linked to original sources
PubMed1982

Projecting demand for cardiac pacemakers.

A cardiac pacemaker implantation program involves substantial resources of money, facilities, and manpower. This paper presents a model for forecasting future numbers of implants, thus enabling the more efficient use of such resources. The model embraces both new implants and replacements, both short-term and long-term planning, and can be used with relevant data from any source.

Dialysis↗
PubMed1982

Adrenocortical responses following limbic stimulation in rats with hypothalamic deafferentations.

In view of the involvement of limbic structures in adrenocortical regulation, their afferent projections to the mediobasal hypothalamus were investigated. Electrical stimulation via chronically implanted electrodes in the dorsal hippocampus, the medial septal nuclei, the basolateral amygdala or the mesencephalic reticular formation all elicited a significant increment in plasma corticosterone levels in adult male rats under pentobarbital anesthesia. Complete or anterior hypothalamic deafferentation blocked these adrenocortical responses completely, and posterior hypothalamic deafferentation attenuated them to a marked extent. In animals with bilateral medial forebrain bundle lesions, hippocampal stimulation had no effect upon plasma corticosterone levels. These studies demonstrate that extrahypothalamic effects upon adrenocortical secretion are neurally mediated, and that the integrity of neural pathways impinging upon the mediobasal hypothalamus from both the rostral and the caudal directions is essential to these effects.

Adrenal Cortex↗
PubMed1981

Modification of responses to sensory and hippocampal stimuli in neurons of the rat mediobasal hypothalamus in the presence of iontophoretically applied cortisol.

The effects of iontophoretic cortisol on evoked activity was studied in rat tuberal hypothalamic units. Evoked activity from visual, auditory, sciatic nerve and hippocampal stimulation was examined in same neurons both before and during local cortisol administration. Hippocampal stimuli were studied in isolation and as conditioning stimuli for one of the sensory modalities. A constant background glutamate current was frequently used in order to shorten observation periods and to enhance inhibition of firing. Even though the predominant effect of cortisol on spontaneous firing was to reduce the firing rate, the effect of the hormone on evoked responses of all kinds was to reduce the size of the response, independent of sign, and even to reverse the nature of the response, from control facilitation to inhibition or from control inhibition to facilitation. Evoked responses in many units whose spontaneous activity was not affected by cortisol were altered by hormone. Of particular interest are a group of cells which are normally silent and respond to afferent stimulation with inhibition. The responses in these cells are reduced or changed to excitation in the inhibition. The responses in these cells are reduced or changed to excitation in the presence of cortisol and they may represent local inhibitory interneurons. The findings are related to the negative feedback of adrenocorticosteroids on CRF and ACTH release.

Animals↗
PubMed1981

Effects of hypothalamic deafferentations on adrenocortical responses in the rat following hippocampal stimulation.

Adrenocortical responses, as expressed by changes in plasma corticosterone levels, following ether stress and dorsal hippocampal stimulation, were studied in intact rats and in rats with complete, anterior of posterior hypothalamic deafferentations. Ether stress produced normal responses in all experimental groups. In the three groups with hypothalamic deafferentations, the adrenocortical response following hippocampal stimulation was completely blocked, when compared to intact animals. The results suggest that the hippocampal signal enters the hypothalamus anteriorly, but that caudal propagation and posterior re-entry into the hypothalamus are also essential for the adrenocortical activation by the hippocampus.

Adrenal Cortex↗
PubMed1981

Effects of sciatic nerve stimulation on ACTH secretion, in intact and in variously hypothalamic deafferentated male rats.

Serum ACTH levels were determined by RIA following sciatic nerve stimulation, in intact rats and in rats bearing anterior (AHD), posterior (PHD) or complete (CHD) hypothalamic deafferentations. In both N and PHD groups, serum ACTH concentrations were markedly elevated following stimulation. In CHD animals this response was completely eliminated, and in the AHD group only a very slight and marginally significant increase in serum ACTH occurred, upon stimulation. These results demonstrate that the increased corticosterone secretion which occurs following sciatic nerve stimulation is due to elevated blood levels of ACTH, and confirm that this somatosensory stimulation impinges upon the hypothalamus from the rostral directions.

Adrenocorticotropic Hormone↗
PubMed1981

Effects of demand for performance, self-monitoring of arousal, and increased sympathetic nervous system activity on male erectile response.

Clinical programs for the treatment of impotence generally have been successful but without experimental verification of their individual components or factors associated with the development of impotence. Twenty-four normal males participated in an investigation comparing factors believed to inhibit or facilitate penile tumescence. The effects of demand for performance, self-monitoring of erection, and increased SNS activity, were evaluated. Subjects were exposed to sexual stimuli under these conditions and measurements of penile responses were taken. Results indicated that there were no differential effects on penile responses between demand and no-demand or between self-monitoring and no self-monitoring. Increased SNS activity appeared to facilitate loss of erection, but only after, and not during, the sexual stimulus. The clinical and theoretical implications of these findings are discussed, and suggestions are made for future research.

Adult↗
PubMed1981

Surgical management of ectopic ureterocele.

Nine patients with ectopic ureterocele, complete duplication, and nonvisualization of the upper renal segment are presented. All were managed with heminephrectomy and partial ureterectomy only. The procedure immediately controlled urosepsis, and ultimately was successful in the management of associated reflux. Excision of ureterocele and reimplantation of the ipsilateral ureter was unnecessary.

Adolescent↗
PubMed1981

The role of the medial forebrain bundle in the mediation of the hypothalamic-hypophyseal-adrenal responses to acute neurogenic stress.

Adult male rats, intact (N) or bearing bilateral lesions in the medial forebrain bundle (MFB), were acutely exposed to visual, audiogenic, or thermal stress, during the following which serum ACTH and corticosterone (CS) levels were determined. The marked elevations in serum concentrations of both ACTH and CS which occurred in intact animals following photic stimulation were absent in MFB rats. The normal ACTH and CS responses to audiogenic stress were slightly delayed and attenuated, respectively, in the operated group, whereas the responses of both hormones to exposure to elevated environmental temperature were partially blocked in lesioned, as compared to intact, animals. These results demonstrate that the MFB is involved in mediating the ACTH, as well as the CS secretory responses to acute stress exposure. More specifically, the role of the MFB, vís-à-vis the hypothalamo-hypophyseal-adrenal axis, appears to be in the transmission of sensory input from rostral brain areas posteriorly.

Adrenocorticotropic Hormone↗
PubMed1981

Salicylate absorption from a bismuth subsalicylate preparation.

The active ingredient in Pepto-Bismol (PB) (Norwich-Eaton), a common antidiarrheal, is bismuth subsalicylate. The absorption of salicylate after oral PB was studied in six fasted men. Plasma concentrations of total salicylate and the urinary excretion profile of salicylate were determined as a function of time and dose. After 60 ml PB, 500.1 +/- 33.6 mg (mean +/- SD) salicylate were recovered in urine, representing 95.0 +/- 6.4% of salicylic acid equivalents in 60 ml of the formulation. Peak plasma salicylate levels were reached 0.5 to 3 hr after ingestion and averaged 40.1 +/- 17.3 micrograms/ml. Absorption of salicylate was also essentially complete after 15- and 30-ml doses of the antidiarrheal preparation, and a linear relationship between dose and recovery of salicylate in the urine was found. Salicylate kinetics was nonlinear after a multiple-dose regimen of 60 ml every 6 hr for five doses.

Adult↗