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Biomedical subjects

S Spector

Publications and source records attributed to S Spector.

At least 145 records · Page 8Linked to original sources
PubMed1976

Response of asthmatics to methacholine and suggestion.

Effects of diluent, methacholine, and suggestion on pulmonary function were studied in 9 asthmatic subjects. On day 1, flavored diluent was given as a control preparation. On day 2, increasing concentrations of similarly flavored methacholine were administered. On day 3, the effect of flavored diluent plus suggestion was studied. Although all variables were affected, the dose-response relationships for methacholine were most pronounced for specific airway conductance and airway resistance, in contrast to maximal mid-expiratory flow, forced expiratory volume in 1 sec, and forced vital capacity. Suggestion toward bronchoconstriction significantly affected only the plethysmographic parameters, specific airway conductance, and airway resistance, and not the spirometric variables. Both airway resistance and 1-sec forced expiratory volume showed slight, but significant, changes as a result of bronchodilator suggestion, which was used to overcome the suggestion toward bronchoconstriction. Because suggestion had a greater effect on large airways than peripheral airways, a role for the vagus is implied. Thus, any protocol using body plethysmography must consider a possible effect of suggestion on results.

Adolescent↗
PubMed1976

Stereospecific radioimmunoassay for propranolol isomers.

Antisera against propranolol were produced in rabbits immunized with propranolol conjugated to bovine serum albumin. The antiserum against dl-propranolol recognized both d- and l-propranolol to the same degree. However, antiserum against l-propranolol was able to discriminate the l-propranolol selectively. The antisera were used to develop radioimmunoassays for dl-propranolol and l-propranolol. The assay can detect as little as 10 pg of propranolol. Metabolites of propranolol do not interfere with the assay unless concentrations are very high. Serum and heart levels of l-propranolol and the d-isomer were determined in the rat after i.v. injection (1 mg/kg) of dl-propranolol. l-Propranolol declines rapidly in the blood after the injection. Concomitantly, there is a rapid accumulation of l-propranolol by the heart. The d-form of propranolol remains in the blood and is metabolized rapidly as reflected by a shorter half-life (23.8 minutes) than the one found for l-propranolol (5.20 minutes).

Animals↗
PubMed1975

The diposi tion of morphine in surgical patients.

The disposition of serum morphine following administration of 10 mg/70 kg was determined by a sensitive and specific radioimmunoassay in 31 anethetized surgical patients ranging in age from 23 to 75 yr. Following iv injection, 93 per cent of the morphine disappeared from the serum within 5 min. The early serum levels of the drug (2 min) correlated directly with the patients' ages (r equal to 0.63, p smaller than 0.01). Patient 23 to 50 yr of age averaged 0.29 mug/ml, whereas patients 51 to 75 ur of age averaged 70 percent higher, 0.49 mug/ml. The serum half-life between 10 and 240 min was independent of age and averaged about 2 hr after either iv or im administration. Following im admininstration, morphine was rapidly absorbed, with peak levels occurring within 10 to 20 min. The decline in morphine serum levels paralleled the decline in morphine analgesia and was coincident with the apperance of morphine glucuronide in the serum. These studies demonstrate the applicability and specificity of the radioimmunoassay for morphine and suggest that serum levels of morphine may be a useful and objective indicator of its pharmacologic activity.

Adult↗
PubMed1975

Presence of norepinephrine and related enzymes in isolated brain microvessels.

Norepinephrine and the enzymes involved in its synthesis and degradation were found to be associated with isolated brain microvessels. The significance of these results are discussed with respect to adrenergic innervation of the cerebral microvessels and thereby neural regulation of the cerebral microcirculation.

Animals↗
PubMed1975

Sex hormones and tyrosine hydroxylase activity in vascular and adrenal tissue.

Vascular tyrosine hydroxylase (TH) activity did not appear to be affected by the sex hormones. There were no differences in enzyme activity in the mesenteric artery or vein taken from male and female normotensive or spontaneously hypertensive rats. Castration of either male or female rats did not alter mesenteric artery or vein TH activity, and the administration of estradiol, progesterone, or testosterone also had no effect on vascular TH activity. However, the sex hormones did alter activity in other tissues. Estradiol and progesterone administration to intact female rats increased adrenal TH activity, whereas castration of the male rat decreased it. Although the sex hormones were not important regulators of TH in blood vessels, vascular TH activity did appear to be under some hormonal regulation since hypophysectomy decreased mesenteric artery enzyme activity. Hypophysectomy studies also indicated that adrenal TH activity was under some hormonal regulation.

Adrenal Glands↗
PubMed1975

Immunopharmacological studies using 5-hydroxytryptamine antibody.

An antibody to serotonin (5-HT) was tested on several preparations in which 5-HT is considered to be involved. The antibody was capable of effectively competing with 5-HT receptor sites for free molecules of 5-HT. It inhibited the uptake of 3H-5HT by blood platelets and may explain the reduced endogenous 5-HT concentration in blood platelets of immunized rabbits. The decreased platelet content of 5-HT was substantiated by electron microscopic studies which showed a reduction in the number of 5-HT-containing subcellular storage organelles in platelets from these animals. The 5-HT antibody inhibited the 5-HT-induced contraction of aortic strips in a tissue bath preparation. When given intraventricularly, it inhibited for a time the sedative actions of reserpine thus adding new evidence to the often postulated role of 5-HT in the actions of reserpine.

Adenylyl Cyclases↗
PubMed1975

Disposition of naloxone: use of a new radioimmunoassay.

Understanding of the pharmacology of the narcotic antagonist naloxone has been limited by the lack of a convenient and sensitive method of assay. A radioimmunoassay for naloxone has been developed and is described. It is applicable for drug analysis in either serum or brain. The limit of sensitivity of the assay was 0.1 ng. Naloxone glucuronide, noroxymorphone (nor-naloxone) and morphine were not recognized by the antibody whereas naltrexone and 6-hydroxynaloxone were able to displace naloxone-3H from the antibody. The assay was of sufficient sensitivity to follow the serum levels of naloxone in man for up to 2 hours after an i.v. injection of 0.4 mg. In animal studies, the biologic half-lives of naloxone or morphine (5 mg/kg) were compared after s.c. injection in rats. The peak serum levels A (1 mu/mo), time to peak serum levels (less than 1/2 hour), and serum half-life (40 minutes) were comparable. However, the brain entry and egress of the two compounds differed markedly. Peak brain levels of naloxone occurred within 15 minutes and had declined by 50% within 1 hour, whereas the peak brain levels of morphine were sustained for up to 2 hours. At peak serum levels, the brain/serum ratio for morphine was 0.1 whereas for naloxone it was 15 times greater. We suggest the high brain/serum ratio of naloxone contributes to its potency whereas the rapid egress from the brain is important in the short duration of action of naloxone.

Animals↗
PubMed1975

Radioimmunoassay for desmethylimipramine.

This paper describes the production of antibodies against demethyl-imipramine (DMI). By using antisera, a radioimmunoassay was developed capable of detecting 0.2 ng of DMI which is linear up to 25 ng. The assay has been applied for the measurement of DMI in rat plasma and brain. The assay might find application especially when only limited amounts of blood, plasma or tissue are available.

Animals↗
PubMed1975

Correlation of chlorpromazine levels in rat brain and serum with its hypothermic effect.

The correlation between chlorpromazine (CPZ) levels in rat brain and serum with hypothermia was investigated. Even large differences between brain and serum concentrations of CPZ could be demonstrated at the two dosages of the drug investigated, the groups showed an identical hypothermic effect between 5 to 30 minutes, with maximum hypothermia being reached 1 hour. It also appears that when brain concentrations of CPZ were lower than 1 mug/g, body temperature returned to normal. We could not demonstrate any preferential uptake of CPZ into the hypothalamus, the proposed site at which CPZ acts to cause hypothermia.

Animals↗
PubMed1975

Antihypertensive drugs and catecholamine metabolism: effects of reserpine and hydralazine on tyrosine hydroxylase activity and norepinephrine concentrations in the spontaneously hypertensive rat.

The antihypertensive drugs, reserpine and hydralazine, produce different effects on tyrosine hydroxylase activity and norepinephrine levels in blood vessels and other tissues of the spontaneously hypertensive rat at doses which cause an equivalent reduction in blood pressure. Reserpine administration is associated with increased tyrosine hydroxylase activity in the mesenteric artery, mesenteric vein and adrenal, but the vasculature appears more sensitive to the effects of reserpine than the adrenal. This increase in tyrosine hydroxylase activity can be related to catecholamine depletion in the mesenteric artery, mesenteric vein and adrenal. Since chlorisondamine, a ganglionic blocking agent, diminished the ability of reserpine to increase tyrosine hydroxylase activity in the mesenteric artery and adrenal, it is likely that increased nerve activity is involved in regulation of the enzyme in both tissues. Hydralazine neither alters tyrosine hydroxylase activity in arteries or veins, nor depletes catecholamine levels in these tissues. In the adrenal, hydralazine increases tyrosine hydroxylase activity independently of any change in catecholamine levels. It would appear that changes in tyrosine hydroxylase activity produced by antihypertensive drugs are organ dependent and may involve both neuronal activity and amine depletion.

Adrenal Glands↗
PubMed1974

Increased collagen synthesis in blood vessels of hypertensive rats and its reversal by antihypertensive agents.

Collagen synthesis is increased in the aortas, mesenteric arteries, and to a lesser extent, in the hearts of rats either made hypertensive with desoxycorticosterone acetate-salt or that are spontaneously hypertensive. Several markers of collagen biosynthesis were shown to be increased, including prolyl hydroxylase (EC 1.14.11.2; proline, 2-oxoglutarate dioxygenase), prolyl hydroxylase-related antigen, total collagen content, and the incorporation of [(3)H]proline into total protein and into collagen. The antihypertensive agents chlorothiazide and reserpine, when administered before the onset of hypertension in the rats treated with desoxycorticosterone acetate-salt, prevented or diminished the increase in collagen biosynthesis. When reserpine was given after the onset of hypertension, prolyl hydroxylase activity was decreased concomitant with the decrease in blood pressure. Treatment with reserpine is particularly effective in diminishing arterial prolyl hydroxylase activity.

Animals↗