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Biomedical subjects

S Feldman

Publications and source records attributed to S Feldman.

At least 307 records · Page 17Linked to original sources
PubMed1981

Amygdalectomy Inhibits adrenocortical responses to somatosensory and olfactory stimulation.

Adrenocortical responses, as measured by plasma corticosterone, to ether stress, photic, acoustic, sciatic and olfactory stimulation, were studied in amygdalectomized and in intact rats. While amygdalectomy had no effect on the adrenocortical responses following ether stress or photic and acoustic stimulation, the responses following sciatic and olfactory stimulation were markedly reduced. These results, taken together with our previous studies, suggest that the amygdala participates in the transmission of adrenocortical responses to olfactory stimulation and has also a modulatory facilitatory effect on the adrenocortical response to somatosensory stimulation. Amygdalectomy also reduced the effect of dexamethasone on basal plasma corticosterone secretion, indicating that the amygdala may participate in the feedback regulation of pituitary-adrenal function.

Acoustic Stimulation↗
PubMed1981

Leadership in mental health: changing the guard for the 1980s.

The author reviews the leadership changes that have taken place in mental health organizations and the factors that have influenced these changes as the mental health field has developed. The administrators of the early mental hospitals were physicians and laymen. By the mid 1840s, the physician-administrator had become dominant, but this changed with the social values of the 1960s and the growth of community mental health centers. Most recent has been the movement into leadership positions by professional administrators without clinical training. The author suggests that the mental health leaders of the 1980s must understand that administration is substantially modified by the subject matter and the values of the mental health field. He feels that the administrator must never lose touch with the experience of being a patient.

Administrative Personnel↗
PubMed1981

Neural pathways mediating basal and stress-induced secretion of luteinizing hormone, follicle-stimulating hormone, and testosterone in the rat.

Adult male rats, intact or bearing complete, anterior, or posterior hypothalamic deafferentations (CHD, AHD, or PHD, respectively) or bilateral medial forebrain bundle (MFB) lesions, were acutely exposed to visual, audiogenic, or thermal stress. Two to 30 min after stress onset, the rats were decapitated, and trunk blood was collected from serum LH, FSH, and testosterone (T) determinations. While basal serum LH levels were found to be normal in all experimental groups, FSH levels were reduced in CHD and AHD rats, and serum T concentrations were found to be 3-fold greater than control values in the AHD group. In intact animals, exposure to all modalities caused significant elevations in serum levels of both LH and T, with no effect on FSH secretion. In the CHD and AHD groups, the LH and T responses were eliminated, with the exception of the T response to heat exposure, which persisted in CHD animals. In the PHD group, the LH and T responses persisted and were, in fact, potentiated. Bilateral medial forebrain bundle lesions inhibited the LH and T responses to audiogenic and thermal, but not to visual, stimulation. These data demonstrate that 1) basal FHS, but not LH, secretion is dependent upon extrahypothalamic afferents to the medial basal hypothalamus; 2) acute neurogenic stress stimulates LH and T, but not FSH, secretion; and 3) central nervous system sites, rostral to the medial basal hypothalamus, mediate the stress-induced elevations in LH release.

Acoustic Stimulation↗
PubMed1981

Site and mode of action of indomethacin on the hypothalamo-hypophyseal-adrenal axis: a temporal study in intact, hypothalamic-deafferentated, and hypothalamic-lesioned male rats.

Adult male rats were given single sc injections of indomethacin (IM; 5 mg/100 g BW) and sacrificed 2-24 h later. IM effects upon serum ACTH and corticosterone (CS) levels, rectal temperature, and hypothalamic and adenohypophyseal prostaglandin E2 (PGE2) and cAMP contents were observed. Rectal temperature was normal for 5-10 h post injection and later decreased by approximately 2.5 C. Both hypothalamic and adenohypophyseal PGE2 concentrations were reduced from 2-24 h after IM administration; no changes in cAMP content were observed. Serum ACTH and CS levels were elevated 4- and 6-fold, respectively, over the entire period observed. In animals with complete hypothalamic deafferentations, the ACTH and CS responses to IM were as marked as they were in intact rats. In rats with hypothalamic lesions in which the ACTH and CS responses to ether stress were attenuated, marked ACTH and CS secretory responses to IM were seen. It is concluded: 1) that the main site of action of systemically administered IM on the hypothalamohypophyseal-adrenal axis, is within the adenohypophysis; 2) that this effect is mediated by PGE2, and cAMP is not involved; and 3) that central nervous system PGs may be involved in the maintenance of basal body temperature in the rat.

Adrenal Glands↗
PubMed1981

Acute transverse myelitis: incidence and etiologic considerations.

There have been few population-based studies of acute transverse myelitis (ATM). Therefore, incidence and population selectivity of this disorder in different regions is not well known. Data on all Jewish patients with ATM throughout Israel were collected for the period 1955 through 1975. Based on 62 patients who satisfied rigid diagnostic criteria, the average annual incidence rate was 1.34 per million population. No significant difference in incidence was noted between European/American-born and Afro/Asian-born populations. There was no significant seasonal or annual fluctuation in frequency. In 37% of the patients, a history of infection prior to ATM was reported, more commonly among younger patients. ATM rarely evolved into multiple sclerosis. More than one-third of the patients with ATM made a good recovery; in another one-third recovery was only fair; 14 patients failed to improve and 3 died. If other population-based studies of ATM were undertaken, comparison with our results might shed further light on the causes of this disorder.

Acute Disease↗
PubMed1981

Effect of blood sampling schedules on protein drug binding in the rat.

The effect of repetitive blood sampling schedules on the plasma protein binding of a highly protein-bound drug, dicumarol, was investigated in the rat. Blood samples were withdrawn at pre-determined intervals and hematocrit, total plasma protein, plasma albumin and free fatty acids were measured. Plasma protein binding of [14C]dicumarol was assessed by equilibrium dialysis. Withdrawal of 1 ml of blood every hour for 12 hr produced a significant decrease at 2 hr in hematocrit (42%), total plasma protein (14.5%), plasma albumin (31.4%) and an increase in free fatty acids (238%) compared to the control (O time) levels. The free fraction of dicumarol in the plasma increased 1350%, from 0.38 to 5.13%. Sampling schedules involving blood withdrawal of 0.5 mg/2 hr and 1 ml/2 hr producing less dramatic changes, but in all cases the free fraction of dicumarol was elevated at the 12-hr time period. An inverse relationship was found between plasma albumin concentrations and dicumarol-free fraction. The blood sampling schedule was found to alter the pharmacological response (prothrombin time) and pharmacokinetics of dicumarol after an 8 mg/kg i.v. dose. These results illustrate the influence multiple blood sampling can exert on pharmacodynamic parameters in studies involving small laboratory animals and highly protein-bound drugs.

Animals↗
PubMed1981

Bioavailability of allopurinol oral and rectal dosage forms.

The bioavailability of allopurinol from orally administered tablets and rectally administered suppositories is reported. Two types of rectal suppositories (cocoa butter and polyethylene glycol) were compounded and contained 300 mg allopurinol (from oral tablets). Five healthy volunteers received 300 mg allopurinol orally from tablets or rectally from suppositories in a randomized, three-way crossover design. Serial blood samples were drawn for 72 hours following administration and were analyzed by high-pressure liquid chromatography for allopurinol and its metabolite, oxipurinol. The interaction between allopurinol and PEG was studied in vitro using a dialysis method. Serum allopurinol levels following oral administration of tablets peaked at 1.5 +/- 0.23 microgram/ml at 5.20 +/- 0.65 hours. Allopurinol was not detectable after administration of cocoa butter/allopurinol suppositories; oxipurinol peaked at 0.34 +/- 0.14 microgram/ml at 13 +/- 11 hours. The bioavailability of allopurinol from the cocoa butter suppository, relative to the tablet, was 5.77 +/- 2.5%. Neither allopurinol nor oxipurinol was detectable (less than 0.1 microgram/ml) in the sera of persons following administration of PEG suppositories. Dialysis studies showed decreased loss of allopurinol from the dialysis sac as PEG concentration increased. The rectal suppositories of allopurinol used in this study did not appear to be an efficient means of administering this drug.

Administration, Oral↗
PubMed1980

Corticotrophin and corticosterone secretory patterns following acute neurogenic stress, in intact and in variously hypothalamic deafferented male rats.

Adult male rats, intact (N) or bearing complete (CHD), anterior (AHD), or posterior (PHD) hypothalamic deafferentations, were acutely exposed to either visual or audiogenic stimulation. At 2, 4, 10 or 30 min following the onset of stress exposure the animals were decapitated and trunk blood was collected for ACTH (RIA) and corticosterone (CS, CBG) determinations. Basal serum concentrations of both hormones were elevated in CHD and AHD, but not in PHD animals as compared to N animals. In N rats, exposure to both stresses resulted in elevated serum ACTH and CS concentrations, with the ACTH response to audiogenic but not visual stimulation being biphasic. In CHD animals, serum ACTH concentrations decreased, and those of CS were unchanged following stress exposure. While audiogenic stimulation caused elevation in serum levels of both hormones in AHD rats, the normal ACTH and CS response to visual stimulation were completely abolished by anterior hypothalamic deafferentation. In PHD animals, no ACTH response to either of the stress exposures was apparent; in spite of this, partial CS responses were elicited. These data thus describe the temporal aspects of the ACTH and CS secretory responses to different neurogenic stresses, and provide insight into the neural pathways mediating these responses.

Adrenocorticotropic Hormone↗
PubMed1980

Chemoprophylaxis for Pneumocystis carinii pneumonitis: outcome of unstructured delivery.

Sulfamethoxazole-trimethoprim was administered prophylactically to 786 patients judged to be at sufficient risk for development of Pneumocystis carinii pneumonitis. The selection of patients, administration of the agents, and surveillance for compliance were the responsibility of the attending oncologists rather than specialists in infectious diseases, as in an earlier trial at this center. The recommended dosage was trimethoprim, 150 mg/sq m/day, and sulfamethoxazole, 750 mg/sq m/day. Over a three-year study period, nine cases of P carinii pneumonitis occurred at this institution, with none attributable to drug failure. Adverse reactions, skin rashes mainly, were noted in 43 patients, and one patient died with Stevens-Johnson syndrome. These results confirm the efficacy of sulfamethoxazole-trimethoprim in preventing P carinii pneumonitis in childhood cancer patients and illustrate the feasibility of large-scale unstructured delivery of the combination to patients with malignant diseases frequently associated with this pneumonia.

Adolescent↗
PubMed1980

The role of the medial septal nucleus in mediating adrenocortical responses to somatosensory stimulation.

In view of the demonstrated involvement of the hippocampus in the mediation of adrenocortical responses following sciatic nerve stimulation, the role of the septum and the preoptic area in the transmission of this response was investigated. Changes in plasma corticosterone following ether stress and photic acoustic, or sciatic nerve stimulation were studied in intact rats and in animals with lesions in the medial septal nucleus and the preoptic area. The response to ether stress and to photic and acoustic stimulation was normal in these animals. However, the adrenocortical response to sciatic nerve stimulation was partially reduced in the rats with lesions in the superior, but not in the inferior preoptic area, and it was completely blocked in those with medial septal lesions. Our previous and present experiments indicate that the ventral hippocampus, the fimbria, the septum, and anterior hypothalamic afferents mediate the adrenocortical response to somatosensory stimulation.

Acoustic Stimulation↗
PubMed1980

Permeability of everted rat small intestine to lidocaine and derivatives.

The transfer rates of lidocaine and five derivatives were measured across the everted rat intestine. No obvious relationship was observed between the first-order rate constants for transfer and the lipophilicity of the compounds as measured by their apparent partition coefficients. The intestinal mucosal epithelium also did not appear to be the rate-limiting barrier for the passage of these agents across the intestinal membrane regardless of the respective clearance of the compound. It is suggested that the ionized form of these agents may be capable of crossing the intestinal barrier at substantial rates, although it is not known if a similar situation exists in vivo. The transfer rate is believed to be due to the passage of intact drug and not the metabolite.

Animals↗
PubMed1980

A semi-automatic device for pacemaker function analysis.

An external semi-automatic Pacemaker Function Analyzer (PFA) has been designed for routine examination (screening) of ambulatory-paced patients in general medical practice. The evaluation of the pacemaker (PM) function is based on recognition, decoding, and measurement of the occurrence of QRS complexes and pacing artifacts, and on logic processing of the decoded data. In this way, the state of the batteries and the integrity of the electronic circuitry and the electrodes can be determined. Other PFA applications concern supervision of hospitalized patients by interfacing the analyzer with the monitoring system of a Coronary Care Unit (CCU), transtelephone checking, and adaptation for use in specialized pacemaker clinics. The performance of the PFA was checked on 92 ambulatory patients. The PFA system recognized all but 0.29% of the QRS complexes and 0.21% of the pacing artifacts. Thirty-two of these patients were tested simultaneously by the PFA and the pacemaker clinic physician, both arriving at the same results. Twelve hospitalized patients were monitored in the CCU, after permanent PM implantation, for an average of 4 hours per patient. Although the PFA indicated 5% false-negative alarms for the hospitalized patients, it should be stressed that every true PM failure was promptly detected. It is anticipated that routine use of the PFA for management of paced patients will reduce the expenses incurred by frequent visits, as well as simplify the follow-up and surveillance of ambulatory and hospitalized patients, thereby facilitating the work of the medical staff.

Coronary Care Units↗