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Biomedical subjects

B T Mellion

Publications and source records attributed to B T Mellion.

6 recordsLinked to original sources
PubMed1993

Childhood intervertebral disc calcification.

Two cases of intervertebral disc calcification in children are reported. A 13-year-old boy presented with right subscapular pain radiating into the axilla with radiographic demonstration of multiple calcified intervertebral discs and a herniated fragment of calcified nucleus pulposus at T2-3. His condition improved with conservative therapy, and follow-up radiographic evaluation revealed resolution of the herniated calcified disc material. A second case of multiple intervertebral disc calcifications was observed incidentally in an asymptomatic 6-year-old boy. The clinical presentation of this condition, its incidence, natural history, proposed etiologies, treatment options, and outcome are reviewed.

Adolescent↗
PubMed1989

Anterior sacral meningocele and tuberculous spondylitis of the sacrum in a patient with neurofibromatosis. Case report and review of the literature.

We report a case of an adult male with neurofibromatosis and chronic low back pain. Evaluation revealed an anterior sacral meningocele, pulmonary tuberculosis, and later in the course of his illness, an osteolytic tuberculous mass in the sacrum. The patient was treated medically with a good outcome. The nature of anterior sacral meningoceles and tuberculosis spondylitis, the differential diagnoses, and relevant treatment options are discussed.

Adult↗
PubMed1983

Inhibition of human platelet aggregation by S-nitrosothiols. Heme-dependent activation of soluble guanylate cyclase and stimulation of cyclic GMP accumulation.

Recent studies have suggested that cyclic GMP accumulation in platelets mediates the antiaggregatory effects of certain nitrogen oxide-containing agents such as sodium nitroprusside, nitric oxide, nitrosoguanidines, and related agents. The vasodilator effect of these agents may involve the formation of S-nitrosothiol intermediates which relax vascular smooth muscle, elevate tissue levels of cyclic GMP, and activate guanylate cyclase. The purpose of this study was to investigate the effects of various synthetic S-nitrosothiols on human platelet aggregation. The S-nitroso derivatives of N-acetylpenicillamine, cysteine, and beta-D-thioglucose inhibited human platelet aggregation in a concentration-dependent fashion when ADP, collagen, U46619, or sodium arachidonate was employed as the aggregating agent. The antiaggregatory effects of the S-nitrosothiols were associated with a rapid and marked increase in intracellular platelet cyclic GMP levels, whereas cyclic AMP levels remained unchanged. Additionally, S-nitrosothiols disaggregated platelets which had been aggregated while concomitantly elevating platelet cyclic GMP levels. Moreover, guanylate cyclase, partially purified from the soluble fraction of human platelets, was markedly activated by S-nitrosothiols in a heme-dependent manner. Methemoglobin, a hemoprotein with a high affinity for nitric oxide, partially reversed the antiaggregatory effects, attenuated the accumulation of cyclic GMP, and inhibited the activation of guanylate cyclase by S-nitrosothiols. These data are consistent with the hypothesis that S-nitrosothiols could serve as active intermediates in the inhibitory action of sodium nitroprusside, nitric oxide, and related nitrogen oxides on platelet aggregation.

Blood Platelets↗
PubMed1980

Reversal of 5HT-induced bronchoconstriction by PGI2: distribution of central and peripheral actions.

In anesthetized, mechanically ventilated, and vagotomized cats, we studied the distribution of the bronchodilatory effects of prostaglandin I2 (PGI2) in central and peripheral airways. In the intact-chest cat, bolus intravenous injection of PGI2 in a range of doses from 3 to 100 micrograms produced dose-dependent reversal of 5-hydroxytryptamine- (5HT) induced bronchoconstriction. Bronchodilatory effects were manifested by a pronounced decrease in central airways flow resistance, as estimated by measurement of lung resistance and by an increase in dynamic lung compliance (Cdyn). A similar distribution and magnitude of airway effects were produced by intravenous administration of PGE1 in a range of doses from 0.3 to 10 micrograms. PGI2 significantly reversed the frequency dependence of compliance induced by infusion of 5HT. The PGI2 metabolite, 6-keto-PGF1 alpha, was without effect on pulmonary mechanics. Comparison of right- versus left-heart administration of PGI2 did not point to a significant role of the bronchial circulation in the airway effects of PGI2. Comparison of the effects of PGI2 and PGE1 on cat bronchial and parenchymal strips contracted by 5HT showed both prostaglandins to have predominant action on bronchial smooth muscle with PGI2 being 3-10 times less active than PGE1. These data suggest that PGI2 has central airway bronchodilator activity, similar to, but less potent than PGE1. In addition, they suggest that PGI2 has significant dilator activity in certain peripheral areas of the lung, as well.

Animals↗
PubMed1979

Cardiovascular actions of prostacyclin (PGI2) in the cat.

The cardiovascular actions of the newly discovered bicyclic prostaglandin, prostacyclin, or PGI2, were compared with those of PGE1 in the anesthetized cat. PGI2 decreased systemic arterial pressure, increased cardiac output and decreased systemic vascular resistance. The decreases in systemic vascular resistance were similar when PGI2 was injected into the left or right atrium, suggesting that prostacyclin is not inactivated in the feline pulmonary vascular bed. PGE1 also decreased systemic arterial pressure and increased cardiac output; however, left atrial administration of this substance produced greater reductions in systemic vascular resistance than right atrial injections, suggesting that PGE1 is inactivated in the feline lung. PGI2 also caused dose-related decreases in perfusion pressure in the renal, hindquarters and mesenteric vascular beds and had the greatest vasodilator activity in the mesenteric vascular bed. PGE1 decreased perfusion pressure in the 3 regional beds, and the overall dilator effects of PGI2 and PGE1 in the peripheral circulation were quite smiliar. The present data show that PGI2 is a potent peripheral vasodilator in the cat and since this substance is not inactivated in the lung, it could serve as a circulating hormone in this species.

Animals↗