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Biomedical subjects

B Kennedy

Publications and source records attributed to B Kennedy.

At least 109 records · Page 6Linked to original sources
PubMed1990

Epinephrine synthesis in the rat iris.

Epinephrine (E) alters blood flow, intraocular pressure and pupillary constriction. The rat iris contained E-forming activity that was moderately specific for a phenylethanolamine and was inhibited by the phenylethanolamine-N-methyltransferase (PNMT) inhibitor SKF 29661. Unilateral superior cervical ganglionectomy decreased iris norepinephrine (NE) 63%, but failed to lower PNMT activity or E in the iris. Removal of both adrenal medullae markedly lowered circulating E levels, but had no effect on iris E. Further treatment with 6-hydroxydopamine and reserpine greatly lowered iris NE levels, but failed to decrease either iris E or E forming activity. The rat iris has non-neuronal E-forming enzymes which appear to synthesize most of the E contained in the iris.

Adrenal Glands↗
PubMed1989

Extraadrenal adrenaline formation by two separate enzymes.

Adrenaline (A) is synthesized in the adrenal medullae by the enzyme phenylethanolamine-N-methyltransferase (PNMT). After surgical removal of the adrenal medullae tissue A levels ranged from 22% of control in the heart to 125% of control in the liver. Use of a novel assay to measure tissue A formation revealed that many tissues can synthesize A using PNMT and another enzyme that N-methylates both noradrenaline and dopamine. These enzymes are non-neuronal, inducible and synthesize a major fraction of tissue and urine A.

Adrenal Medulla↗
PubMed1989

Rat renal epinephrine synthesis.

Rats that underwent adrenal demedullation had a 93% decrease in plasma epinephrine (E) levels, but did not decrease their renal E. Even further treatment with 6-hydroxydopamine and reserpine failed to lower renal E levels. Similarly, urine E levels failed to decrease after adrenal demedullation and renal denervation. There is a renal E-synthesizing enzyme that differs from adrenal phenylethanolamine-N-methyltransferase (PNMT) in that it is only weakly inhibited by SKF 29661 and can synthesize epinine from dopamine, while adrenal PNMT does so poorly. When an adrenalectomized rat received intravenous [3H]methionine, its urine contained radioactivity that appeared to be [3H]E, with small amounts of [3H]epinine. However, after [3H]methionine was infused in the renal artery, the major product in urine appeared to be [3H]epinine, with a small amount of [3H]E. Adrenal demedullation induced renal E synthesis, but denervation returned the rate of renal E synthesis to control values. The combination of adrenal demedullation, 6-hydroxydopamine, and reserpine treatments increased renal E-forming activity to 350% of control. We conclude that appreciable portions of renal and urinary E are synthesized in the kidney by an enzyme distinct from PNMT. The enzyme is induced by some treatments that lower E and NE levels.

Adrenal Glands↗
PubMed1989

Personality dysfunction in depressed adolescents.

The personality characteristics of 35 consecutively assessed adolescents who met the DSM-III criteria for a current depressive disorder were assessed using independent structured interviews and paper and pencil measures. Sixty-five percent of the sample met the criteria for an Axis II personality disorder. The single most common diagnosis was borderline personality disorder (30%). Depressed adolescents with a concurrent personality disorder were less self-confident, displayed more neuroticism, and were emotionally reliant on others. They also demonstrated greater cognitive distortion. Teenagers who present with a depressive disorder warrant a comprehensive personality assessment. The combination of affective and personality disorder in such patients is associated with attitudes and interpersonal problems which should be therapeutically addressed in addition to symptomatic treatment of the depressed mood. Clinicians should be aware that depressed adolescents with personality disorder may be more likely to make a suicide attempt.

Adolescent↗
PubMed1988

A sensitive radioenzymatic assay for epinephrine forming enzymes.

Epinephrine (E) is formed in the adrenal medulla by phenylethanolamine-N-methyltransferase (PNMT), and in other tissues. Enzymes other than PNMT may be able to synthesize E, but this has been difficult to investigate because most assays do not have E as their final product. This assay produces 3H-E from norepinephrine (NE) and 3H-S-adenosylmethionine. The 3H-E is isolated on alumina, 3H-S-adenosylmethionine is precipitated and the 3H-E is suspended in diethylhexyl phosphoric acid in toluene for scintillation counting. The assay is sensitive and linear over a wide range. E was formed by most tissues tested. Brain and adrenal contained an enzyme specific for NE, but cardiac ventricle contained an enzyme that methylated both NE and dopamine. Denervated tissues in adrenal medullectomized rats contained very little NE, but still had E and E forming enzyme present. This assay detects a non-neuronal E forming enzyme with activity in vitro and in vivo.

Adrenal Medulla↗
PubMed1987

Cardiovascular, catecholamine and psychological responses to TRH in four types of affective disorder patients.

When 500 micrograms of TRH is given intravenously, an increase in TSH, blood pressure, plasma catecholamines and positive emotions follows. Four groups of patients with major, minor or bipolar depression or schizoaffective disorder increased their TSH levels by similar amounts after TRH. The neurohormone also significantly increased diastolic blood pressure by 5.5 +/- 1.6 mm Hg, and decreased heart rate by 7.6 +/- 1.3 beats/min. There was a weak trend for bipolar depressives to have less cardiovascular response to TRH than the other groups. Plasma norepinephrine (NE) was higher after TRH than after placebo. The NE response differed between patient groups (P = .0023) because of a smaller response by major depressives. TRH decreased anger, tension and depression, and increased friendliness. Positive emotional responses were significantly greater in the bipolar depressives than in other groups. Forty-one other studies have found a subnormal TSH response does not distinguish between subtypes of the affective disorders, but cardiovascular, catecholamine and mood responses may do so.

Adult↗
PubMed1987

Tissue somatostatin levels in three models of genetic obesity in rats.

A potential role for somatostatin (SRIF) in the pathogenesis of the hyperinsulinemia of obese rats was considered. SRIF like immunoreactivity (ng/mg protein) was therefore measured in hot 2 N acetic acid extracts of pancreas, stomach, pituitary, and hypothalamus in tissues obtained from three models of genetic obesity in rats. These models included the obese and lean controls of LA/N-cp, SHR/N-cp, and Zucker rats. To assess the effects of diet on SRIF levels, mixed diets were provided ad lib which contained a carbohydrate as either sucrose or starch. Some groups were fed chow diets. No significant dietary effects on tissue levels of SRIF were obtained. However, two of the three models (Zucker and SHR/N-cp) showed phenotypic effects on SRIF levels in pancreas; namely, obese rats showed a significantly greater concentration of SRIF (P less than 0.0005 and less than 0.0002, respectively) than did the lean littermates. These findings were confirmed by measurement of total pancreas SRIF content. Gastric levels were significantly altered only in the obese Zucker rats (P less than 0.005) where obese tissues had lower concentrations than those of lean animals. However similar directional changes in pancreas and stomach were observed in all models. It is concluded that the hyperinsulinemia of the obese animals studied is not due to absolute deficiency in pancreatic SRIF content. It is postulated however that decreased pancreatic SRIF secretion (paracrine or otherwise) relative to pancreatic insulin content could still play a role.

Animals↗
PubMed1986

Alternating lateralization of plasma catecholamines and nasal patency in humans.

The nose receives both sympathetic and parasympathetic innervation that is manifested by the alternating dominance of sympathetic activity on one side with concurrent parasympathetic dominance on the other. This ultradian rhythm of autonomic function, known as the nasal cycle, averages 2-3 hours in length. Previous experiments have shown that the nasal cycle is correlated in an inversely coupled fashion to the alternating dominance of activity in the two cerebral hemispheres, suggesting a common mechanism of regulation. Here we show that there is an alternation in catecholamine levels of blood drawn from anticubital veins that may also correlate with the nasal cycle. Radioenzymatic measurement of norepinephrine, epinephrine, and dopamine in blood sampled simultaneously from both arms every 7.5 minutes for periods of 3-6 hours demonstrated alternating high levels of catecholamine in one of the two arms. This alternating lateralization of neurotransmitters was observed in 7 out of 7 experiments using resting human male subjects. The ratio of norepinephrine in the two arms also parallels the pattern of airflow in the nasal cycle. This study suggests that the autonomic nervous system may alternate in activity through paired structures.

Adolescent↗
PubMed1986

Central muscarinic effects of physostigmine on mood, cardiovascular function, pituitary and adrenal neuroendocrine release.

The mechanism by which physostigmine exerts its behavioral, neuroendocrine and cardiovascular effects was explored in two separate experiments. In the first, the centrally-acting cholinesterase inhibitor physostigmine was compared with the non-centrally-acting agent neostigmine. In contrast to physostigmine, neostigmine caused no effects. In the second experiment, pretreatment with scopolamine, in contrast to methscopolamine, attenuated physostigmine's effects. The results suggest that physostigmine exerts its effects via a central muscarinic mechanism.

Adrenal Cortex↗
PubMed1986

Osmolality of enteral formulas for maternal phenylketonuria.

Osmolalities of individual products and composite diets used in the treatment of maternal phenylketonuria were measured. Mathematical equations were developed which predict osmolality. Quantitative information on osmolalities of enteral formulas for women with maternal phenylketonuria may help clinicians plan diets to avoid the risk of gastrointestinal disturbances and to increase acceptability.

Enteral Nutrition↗
PubMed1986

Central and peripheral cholinesterase inhibition: effects on anterior pituitary and sympathomimetic function.

Ten physically healthy inpatients of mixed diagnosis received, in a randomized, counterbalanced double-blind paradigm, physostigmine (22 micrograms/kg) and neostigmine (11 micrograms/kg). Infusions were separated by at least 2 days. The differential effects of physostigmine and neostigmine on plasma concentrations of cortisol, prolactin, growth hormone, ACTH, beta-endorphin/beta-lipotropin-like immunoreactivity, dopamine, norepinephrine, and epinephrine are reported. Administration of physostigmine, unlike that of neostigmine, was associated with statistically significant increases in plasma concentrations of cortisol, prolactin, ACTH, beta-endorphin/beta-lipotropin-like immunoreactivity, and epinephrine, presumably via central mechanisms. In a separate study, 15 subjects, mostly depressed inpatients, were pretreated with methscopolamine (0.75 mg) on one day and scopolamine (0.5 mg) on another day, at least 2 days apart, in a randomized, counterbalanced double blind paradigm and subsequently on each day received physostigmine (22 micrograms/kg). Scopolamine significantly attenuated the physostigmine-associated increase in plasma concentrations of cortisol, growth hormone, prolactin, ACTH, and dopamine compared to methscopolamine, and a close-to-significant attenuation of epinephrine as well. These results provide further evidence that physostigmine's effects on plasma concentrations of pituitary hormones and epinephrine occur via central mechanisms and are muscarinically mediated.

Adrenocorticotropic Hormone↗
PubMed1986

Evaluation of new insect growth regulators against mosquitoes with notes on nontarget organisms.

Three new insect growth regulators (IGRs) were tested against Culex, Aedes and Psorophora mosquitoes. In the laboratory the 3 IGRs were active in the range of 0.3 to 1.5 ppb against Cx. quinquefasciatus. In field tests, the IGRs fenoxycarb and S-31183 formulations yielded complete control of floodwater mosquitoes at the rates of 0.005 to 0.01 lb AI/acre. In field tests against Cx. tarsalis, S-31183 formulations produced complete inhibition of emergence at the rates of 0.005 to 0.025 lb AI/acre. Fenoxycarb formulation produced similar results at the rate of 0.1 lb AI/acre. It is possible that initial and residual field activity of both IGRs can be increased by employing suitable formulations.

Animals↗