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Biomedical subjects

E Hong

Publications and source records attributed to E Hong.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Current practice of exercise stress testing among pediatric cardiology and pulmonology centers in the United States.

The objective of this study was to characterize current practice patterns for clinical exercise stress testing (EST) in children in the United States. We conducted a survey of 109 pediatric cardiology programs and 91 pediatric pulmonology programs at children's hospitals or university hospitals in the United States. A total of 115 programs from 88 hospitals responded (response rate, 58%). A higher percentage of cardiology programs (98.7%) have exercise laboratories compared with pulmonology programs (77.5%). Sixty-three percent of respondents have both a treadmill and a cycle ergometer. A larger proportion of respondents (76%) rely primarily or exclusively on treadmill, whereas a smaller number use cycle ergometer (24%). Sixty-seven percent of respondents reported that they include metabolic measurements in EST protocols. Respondents have varying minimum age criteria for EST, with 9% reporting < or = 4 years, 25% reporting 5 years, 31% reporting 6 years, 16% reporting 7 years, and 20% reporting > or =8 years. Programs using cycle ergometers tend to test children at a younger age and to measure metabolic parameters. Seventy-nine percent of respondents use Bruce and modified Bruce protocols. Institutional protocols are used by 14%. Ninety percent of respondents use technicians to perform EST and 8% use nurses, but 76% require physician presence during testing. The majority of respondents (57%) perform < 100 pediatric tests per year. There are wide variations in the current practice of EST among pediatric subspecialty programs in the United States. Treadmills are used more frequently than cycle ergometers, and Bruce and modified Bruce protocols are commonly used. Most survey respondents measure metabolic parameters during EST.

Adolescent↗
PubMedDate not supplied

Analgesic efficacy and bioavailability of ketorolac in postoperative pain: a probability analysis.

BACKGROUND: The analgesic efficacy and bioavailability of 30 mg intramuscular ketorolac was studied in 24 patients with severe or very severe postoperative pain. METHODS: Pain and pain relief were determined by a five-point verbal rating scale and data were submitted to a probability analysis. Ketorolac plasma levels were determined by high-performance liquid chromatography. RESULTS: Two patients chose not to finish the study; 22 patients completed the study achieving at least good pain relief. Of these 22 patients, 13 reached complete pain relief. Ketorolac was rapidly absorbed. Notwithstanding, pain relief increased gradually, showing considerable delay with regard to plasma concentrations. Analysis of the probability-time curves revealed that 25% of the patients obtained moderate pain relief at 7 min after ketorolac administration, 50% at 11 min, 75% at 29 min, and 95% at 60 min. Good pain relief was achieved in 25, 50, and 75% of the patients at 1.1, 1.8, and 2.7 h, respectively. Complete pain relief was achieved in 25% and 50% of the patients at 2.6 h and 3.7 h, respectively. The probability of exhibiting an acceptable pain relief in responsive patients for more than 5 h was 0.97. No serious side effects were detected. CONCLUSIONS: Results show that 30 mg intramuscular ketorolac is an adequate treatment for postoperative pain in the Mexican population. Therefore, the use of higher doses is not justified. Due to gradual installation of analgesia, administration of additional analgesic medication before 1 h is not recommended.

Adult↗
PubMedDate not supplied

Nature of the central serotonin receptors mediating hypotension.

The stimulation of central serotonin receptors leading to a decrease in blood pressure is well documented, but the nature of these receptors is not well known. It was therefore decided to characterize such receptors by assessing the modifications in blood pressure and heart rate after the intracerebroventricular administration of several drugs to anesthetized cats. Serotonin produced a dose-related decrease in blood pressure and heart rate, while parachloroamphetamine produced a slowly developing increase in blood pressure, and quipazine did not affect any of the parameters measured. The hypotension produced by serotonin was not modified by pretreatment with methysergide, was partially antagonized by quipazine, and was completely blocked by tolazoline. The present findings suggest that the central serotonin receptors which modulate blood pressure are different not only from peripheral receptors, but also from other receptors of this type.

Animals↗
PubMedDate not supplied

[Vasodilator drugs that act by stimulating guanylate cyclase in vascular smooth muscle].

Many exogenous and endogenous vasodilator substances produce their effects by stimulation of guanylate cyclase in vascular smooth muscle and increasing cyclic 3',5'-guanosine monophosphate (cGMP) levels. Activation of such enzyme leads to vasodilatation. Possibly as a consequence of a change in the pattern of protein phosphorylation, including dephosphorylation of the light chain myosin and of a decrease in the bioavailability of free calcium. Guanylate cyclase exists in two different forms in the vascular smooth muscle cells: a cytosolic (soluble) and the other associated to membranes (particulate). The nitro vasodilators and vasodilators with endothelium-dependent activity, act by main stimulation of the soluble guanylate cyclase, while the atrial natriuretic factor acts specifically on the particulate form of the enzyme. Guanylate cyclase represents the final path in the vasodilatation induced by diverse endogenous and exogenous substances, an aspect that has created a great interest among investigators due to its possible physiological, physiopathological and therapeutic implications. The more relevant aspects related with the mechanism of action of this numerous group of drugs are deeply analyzed in the present review.

Animals↗
PubMedDate not supplied

[Pharmacokinetics and antihypertensive effect of pelanserin in dogs ].

Pelanserin pharmacokinetics were studied in six normotensive dogs after intravenous and oral administration. Additionally, the relationship between pelanserin plasma levels and its antihypertensive effect was studied in six hypertensive dogs after a single oral administration. Plasma level-time curves were fitted to an open two compartments model. Pelanserin bioavailability after oral dosing was about 30%, this could be due to a poor absorption from the gastrointestinal tract or to an important hepatic biotransformation by first pass effect. On the other hand, oral administration of pelanserin resulted in a significant antihypertensive effect that was not followed by tachycardia. Pelanserin plasma levels did not significantly correlate with the obtained antihypertensive effect. These results suggest that the observed effect was not only due to an action at peripheral level, but other mechanisms could likely be involved, probably with participation of the central nervous system. The pharmacokinetic and pharmacodynamic profiles of pelanserin allow to predict that this drug could have a place in the therapeutics of arterial hypertension.

Animals↗
PubMedDate not supplied

[Clinical and pharmacokinetic comparison of 2 oral preparations of nifedipine: 10 mg capsules and 20 mg delayed-release tablets].

The effects and pharmacokinetic parameters of two oral formulations of nifedipine, 10 mg capsule (Adaltat) and 20 mg slow release tablet (Adalat a.p.). With the 10 mg capsule nifedipine was rapidly absorbed, reaching a maximum concentration of 120 +/- 39 ng/ml in 0.52 +/- 0.07 h, and also rapidly eliminated with an apparent halflife of 5.51 +/- 0.64 h. A fall in blood pressure and a raise in heart rate, that significantly correlated with plasma levels, were observed. 83% of the subjects reported headache, that was probably due to the sudden increase in plasma levels. With the 20 mg slow release tablet nifedipine absorption was slower, reaching a maximum concentration of 39 +/- 7 ng/ml in 1.82 +/- 0.43 h, and the apparent half-life (16.89 +/- 3.14 h) was longer than with the capsule. A fall in blood pressure was observed that significantly correlated with plasma levels; however, there was no significant correlation between these and changes in heart rate. Only 17% of the subjects reported headache. Pharmacokinetic data indicate that, in most subjects, nifedipine therapeutics plasma levels (over 15 ng/ml) can be maintained with the administration of a 20 mg slow release tablet every 12 hours. This, joined to the reduction in side effects, suggest that this formulation is the adequate alternative in chronic treatments with nifedipine, such as arterial hypertension.

Administration, Oral↗
PubMedDate not supplied

[Atrial natriuretic factor].

The atrial natriuretic factor represents a group of atrial peptides structurally and functionally related. These peptides produce the following effects: natriuresis, diuresis, vasodilation and inhibition of aldosterone release. Its discovery in 1981 opened a new horizon in the studies on body sodium and water homeostasis, as well as on blood pressure regulation. In a few years there have been spectacular advances in the knowledge of this new hormone. However, there are still many doubts and controversies concerning its exact physiological role. Its effects on renal function, vascular contractility and its relationship with other physiological systems are not completely understood. The versatility of functions in which atrial natriuretic factor participates has pointed new trends in the research of important clinical entities such as arterial hypertension and cardiac failure, and could be a starting point for the development of novel therapeutic agents. In this work, the experimental findings dealing with the participation of atrial natriuretic factor in several biological events are reviewed.

Animals↗
PubMedDate not supplied

[Serotoninergic receptors and cardiovascular diseases].

The seronin or 5-hydroxytryptamine (5-HT) is a biogenic amine involved in diverse physiologic and physiopathological processes in the cardiovascular system. 5-HT may lower the arterial blood pressure by an action on central 5-HT1A receptors, or may increase it by stimulation of 5-HT2 receptors located in vascular smooth muscle. It has been postulated that hypofunction of 5-HT1A receptors, or the exaggerated stimulation of 5-HT2 receptor may be associated with arterial hypertension and that agonists of the first type (indorenate or 8-OH-DPAT) or antagonists of the second type (ketanserin or pelanserin) allow the control of arterial hypertension. On the other land, ketanserin and pelanserin attenuated the hemodynamic manifestations in an experimental model of thromboembolism, suggesting that 5-HT is involved in such phenomenon. Finally, 5-HT could be related with the presence of angor pectoris during hypertension or atherosclerosis, diseases that are associated with a lesional of the vascular endothelium, a condition that favors the 5-HT induced vasoconstriction in coronary arteries.

Animals↗
PubMedDate not supplied

2-(2-Aminoethyl)-quinoline (D-1997): a novel agonist at 5-hydroxytryptamine1-like receptors in the canine basilar artery.

This study aimed to investigate the mechanisms involved in the contractile effects produced by the novel quinoline derivative, 2-(2-aminoethyl)-quinoline (D-1997), in the canine isolated basilar artery. For comparison, the effects of D-1997 were also evaluated on rat aorta. Canine basilar artery and rat aortic rings were prepared and mounted in organ baths to record isometric tension changes. The contractile effects of D-1997 in the basilar artery were compared with those produced by 5-hydroxytryptamine (5-HT) and the 5-HT receptor agonist quipazine. Thus, 4-HT (10(-10)-10(-6)M), D-1997 (3.1 x 10(-8)-10(-4) M) and quipazine (3.1 x 10(-7)-10(-4) M) each caused concentration-dependent contractions of the canine basilar artery with a rank order of agonist potency of 5-HT > D-1997 > quipazine. 5-HT and D-1997 exhibited similar maximum effects which were higher than that of quipazine. Similar concentrations of D-1997 failed to produce contraction in rat aorta. The effects of D-1997 in the basilar artery were not modified by incubation with either the 5-HT2 receptor antagonist ketanserin (0.01-1 microM), the 5-HT3 and 5-HT4 receptor antagonist ICS205930 (tropisetron; 0.1-10 microM), the 5-HT1A receptor antagonist spiroxatrine (0.01-1 microM), the beta-adrenoceptor blocker with high affinity for 5-HT1A and 5-HT1B binding sites (+/-)-pindolol (0.01-1 microM), or the alpha 1-adrenoceptor antagonist prazosin (0.01-1 microM). In contrast, the D-1997-induced responses were potently and concentration-dependently antagonized by the mixed 5-HT1-like and 5-HT2 receptor antagonist methiothepin (0.01-1 microM). It is concluded that D-1997 contracts the canine basilar artery by stimulating 5-HT1-like receptors unrelated to either the 5-HT1A or 5-HT1B receptor subtypes. The compound seems to be devoid of 5-HT2 receptor agonist properties in rat aorta.

Animals↗