Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The electrophysiologic effects and efficacy of diltiazem were evaluated with programmed electrical stimulation of the heart in 12 patients with supraventricular re-entrant tachycardia (five with atrioventricular nodal tachycardia and seven with circus movement tachycardia the accessory pathway being concealed in 4). Diltiazem was infused over 1 minute at the dose of 0.25 mg/kg and the electrophysiologic parameters were evaluated at 5 and 30 minutes. Diltiazem prolonged the AH interval from 83.5 +/- 58 to 99 +/- 55 msec (P less than 0.05), effective and functional refractory periods of atrioventricular node from 244 +/- 40 to 268 +/- 56 msec (P less than 0.05) and from 432 +/- 124 to 468 +/- 130 msec (P less than 0.005) respectively, lowered the atrial pacing rate inducing second-degree atrioventricular block from 159 +/- 32 to 134 +/- 33 beats/min (P less than 0.005) and decreased systolic and diastolic blood pressure from 143.5 +/- 33 to 132.5 +/- 22 mm Hg (P less than 0.05) and from 90 +/- 15 to 82.5 +/- 9 (P less than 0.05), respectively. Diltiazem prevented the reinduction of the tachycardia in 4 of 5 patients with atrioventricular nodal tachycardia and in 4 of 7 with circus movement tachycardia. The mechanism of action of diltiazem consisted of depression of conduction in atrioventricular node in anterograde fashion while there were no effects on refractoriness of the accessory pathway. The drug was well tolerated with no adverse effects. Diltiazem, therefore, appears an effective and safe drug in the acute treatment of re-entrant supraventricular tachycardia.
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PMID:Intravenous diltiazem in patients with paroxysmal re-entrant supraventricular tachycardia. 272 88

Clonidine can produce symptomatic sinus bradycardia or atrioventricular (AV) block in some patients. Electrophysiologic studies have been performed after intravenous clonidine in patients showing such side effects; these have demonstrated variable depression of sinus and AV nodal function. We have evaluated the electrophysiologic and hemodynamic effects of chronic oral treatment with either clonidine (0.2 to 0.5 mg every 12 hours; n = 7) or another centrally active alpha 2-agonist, tiamenidine (0.5 to 1.5 mg every 12 hours; n = 7), in otherwise healthy hypertensive human volunteers. At dosages that modestly lowered diastolic blood pressure, both agents significantly slowed sinus rate and increased the atrial pacing rate producing AV nodal Wenckebach. Clonidine also significantly increased corrected sinus node recovery time and lowered cardiac output while similar (but statistically insignificant) trends were seen with tiamenidine. We conclude that chronic oral treatment with these alpha 2-agonists depresses sinus and AV nodal function in virtually all subjects, including those without manifest conduction system disease.
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PMID:Electrophysiologic and hemodynamic effects of chronic oral therapy with the alpha 2-agonists clonidine and tiamenidine in hypertensive volunteers. 289 89

The major antihypertensive mechanism of calcium antagonists is by decreasing the systemic vascular resistance, modified by the counter-regulatory responses of the baroreflexes and the renin-angiotensin-aldosterone system. In severe hypertension, the concept that calcium overload of the vascular myocyte could precipitate or aggravate peripheral vasoconstriction provides a logical basis for the use of these agents as first choice therapy; nifedipine, especially, has been well tested. As monotherapy for mild to moderate hypertension each of the three first-generation agents compares well with beta-blockers. Calcium antagonists may have a special role in the therapy of certain patient groups (elderly, black) or in those subjects whose life style involves intense physical or mental exertion (hemodynamics better maintained than with beta-blockade) or in patients with early end-organ damage such as left ventricular hypertrophy or renal insufficiency. However, the goal blood pressure may not be reached during monotherapy so that drug combinations may be required. Further indications for these compounds are as follows. Verapamil and diltiazem are frequently used in supraventricular tachycardias including acute and chronic atrial fibrillation. In the arrhythmias of the Wolff-Parkinson-White syndrome, there is the potential danger of provocation of anterograde conduction. Further indications for calcium antagonists, still under evaluation, include congestive heart failure (controversial), hypertrophic cardiomyopathy (verapamil), primary pulmonary hypertension (high doses required), Raynaud's phenomenon (nifedipine and diltiazem effective), peripheral vascular disease (proof not yet documented), cerebral insufficiency and subarachnoid hemorrhage (nimodipine promising), migraine, exertional bronchospasm, renal disease, atherosclerosis (experimental), and primary aldosteronism (nifedipine inhibits aldosterone release). Second-generation agents include dihydropyridines, such as nitrendipine, nicardipine, felodipine, amlodipine, nisoldipine, nimodipine, and isradipine. From these will be selected agents that are longer acting and provide higher vascular selectivity. New preparations of existing agents include slow-release formulations of nifedipine, verapamil, and diltiazem. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine. Yet caution is required when calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Calcium channel antagonists. Part III: Use and comparative efficacy in hypertension and supraventricular arrhythmias. Minor indications. 315 29

With the correct selection of drug and patient, the calcium antagonists as a group can be remarkably effective at relatively low cost of serious side effects. Almost all side effects are dose related. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil (or diltiazem) is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine which actually has the most marked negative inotropic effect. Yet caution is required when even calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide. The most marked interaction with digoxin is that with verapamil, which may raise digoxin levels by over 50%. Combination therapy of calcium antagonists with beta-blockers is increasingly common, and is probably safest in the case of dihydropyridines. Other combinations being explored are those with angiotensin-converting enzyme inhibitors and diuretics.
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PMID:Calcium channel antagonists. Part IV: Side effects and contraindications drug interactions and combinations. 315 4

Normally the pacemaker of the mammalian heart is located in the sinus node. In the rabbit the sinus node can be subdivided into two regions, the center of the node where the impulse originates and the border zone through which the impulse is conducted towards the atrium. Conduction properties of both regions were investigated. It appeared that conduction velocity increases and refractoriness decreases when one goes from the nodal center towards the atrium. The tissue mass of the atrium is large in comparison to the sinus node and normally the resting membrane potential of atrial fibers is more negative than that of nodal fibers; consequently, a potential difference exists causing a current flow between both areas. Evidently this hyperpolarizing current flow depresses impulse formation in the border zone fibers which have better intrinsic pacemaker properties than fibers in the nodal center. If the impulse has reached the atrium it is conducted with a relatively high safety factor and will reach the AV node in principle without difficulty. The AV node, if deprived of sinus nodal dominance, develops spontaneous activity originating from the lower nodal fibers. Also in this structure, electrotonic depression by surrounding tissue causes deceleration of the pacemaker.
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PMID:Impulse propagation from the SA-node to the ventricles. 331 92

Bone marrow transplantation (BMT) is often followed by significant morbidity and mortality due to protracted immunodeficiency. We have hypothesized that the bone marrow-ablative regimen may delay the recovery of normal immune function following transplantation by impairing the interaction of host endothelial cells with circulating graft-derived lymphocytes. This report compares the relative effects of busulfan (an alkylating drug) and gamma-irradiation on the tissue-specific localization potential of lymphocytes and the eventual recovery of immune function within syngeneic murine transplant recipients. Localization of normal lymphocytes into peripheral lymph nodes of irradiated BMT recipients was markedly less (less than 50%) than in busulfan-treated or normal mice over the first 2 months post-BMT. This finding correlated with irradiation-induced endothelial cell edema and microvascular occlusions within lymphocyte-receptive areas of the nodal microvasculature. The effect of both preparative regimens on the recovery of contact hypersensitivity (CHS) was also analyzed. This response recovered more quickly (between 1 and 2 months) in busulfan-pretreated animals. Further experiments demonstrated that the decrease in CHS responsiveness appeared, in part, related to a depression in the capacity of lymphocytes to localize into skin sites of antigen deposition within irradiated mice. The impairment of tissue-specific lymphocyte localization may represent a novel mechanism by which whole body irradiation can contribute to delayed immunologic reconstitution following bone marrow transplantation.
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PMID:Recovery of contact hypersensitivity responses following murine bone marrow transplantation: comparison of gamma-irradiation and busulfan as preparative marrow-ablative agents. 331 44

Increasing recognition of the importance of calcium in the pathogenesis of cardiovascular disease has stimulated research into the use of calcium channel blocking agents for treatment of a variety of cardiovascular diseases. The favorable efficacy and tolerability profiles of these agents make them attractive therapeutic modalities. Clinical applications of calcium channel blockers parallel their tissue selectivity. In contrast to verapamil and diltiazem, which are roughly equipotent in their actions on the heart and vascular smooth muscle, the dihydropyridine calcium channel blockers are a group of potent peripheral vasodilator agents that exert minimal electrophysiologic effects on cardiac nodal or conduction tissue. As the first dihydropyridine available for use in the United States, nifedipine controls angina and hypertension with minimal depression of cardiac function. Additional members of this group of calcium channel blockers have been studied for a variety of indications for which they may offer advantages over current therapy. Once or twice daily dosage possible with nitrendipine and nisoldipine offers a convenient administration schedule, which encourages patient compliance in long-term therapy of hypertension. The coronary vasodilating properties of nisoldipine have led to the investigation of this agent for use in angina. Selectivity for the cerebrovascular bed makes nimodipine potentially useful in the treatment of subarachnoid hemorrhage, migraine headache, dementia, and stroke. In general, the dihydropyridine calcium channel blockers are usually well tolerated, with headache, facial flushing, palpitations, edema, nausea, anorexia, and dizziness being the more common adverse effects.
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PMID:Differential effects of 1,4-dihydropyridine calcium channel blockers: therapeutic implications. 332 59

The effects of quinidine (0.01-20 micrograms/ml) on spontaneous action potentials and membrane current systems of the rabbit atrioventricular node were studied. At therapeutic concentrations, this drug decreased the action potential amplitude, the maximal diastolic potential, the threshold potential as well as the maximal rate of depolarization and showed a negative chronotropic action. Quinidine, at 5 micrograms/ml, decreased the peak slow inward current by 30.2%, increased its time constant of inactivation by 27.3%, shifted the steady-state inactivation curve toward more negative membrane potentials by 2.8 mV and decreased its fully activated current. Quinidine exerted not only resting but also use-dependent blocking actions on the slow inward current. The depression of the action potential upstroke can thus be explained by the reduction in this current. The outward K+ tail current was decreased by 65.4% and its deactivation time constant was increased by 19.0%. These effects may have contributed to the prolongation of the action potential duration, the reduction in the maximal diastolic potential and the slowing of diastolic depolarization. Quinidine shifted the steady-state activation curve for this K+ current toward hyperpolarization by as much as 7.8 mV. It decreased the hyperpolarization-activated inward current by 16.3% and increased its activation time constant by 10.1%, but this current appeared to play a small role in reducing the rate of diastolic depolarization. These observations indicate that, depending upon dose, quinidine has the potential to decrease all of the time- and voltage-dependent ionic currents in atrioventricular nodal cells.
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PMID:Membrane actions of quinidine sulfate in the rabbit atrioventricular node studied by voltage clamp method. 334 48

In 12 patients, 20 to 80 years of age, 6 men and 6 women, with acute hellebore (Veratrum album) intoxication the electrocardiographic changes were studied. In 10 of them a characteristic ECG pattern was found: sinus bradycardia 38-40/m, shortening of the interval PQ up to 0.12-0.08 s and QTc up to 0.36-0.32 s, slow intraventricular conduction--transitory right and incomplete left bundle-branch block, rhythm disorders--atrial and substitutional ventricular extrasystoles, nodal rhythm (I patient), disturbed ventricular repolarization--depression of ST-segment, low and (or) pointed T waves. The authors are of the opinion that the bradycardia is due to a reflexively increased vagal tonus but the other changes of the ECG are caused by the direct toxic action of the hellebore alkaloids on the myocardium. This suggestion is supported by the fact that atropine corrects the bradycardia but not the other pathological changes of the ECG. They are beneficially influenced by the fast elimination of the toxins and the application of cardiotropic means--atriphos, cocarboxylase, vitamins of the group B.
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PMID:[Electrocardiographic studies of patients with acute hellebore (Veratrum album) poisoning]. 343 51

Natural killer (NK) cell activity and psychological status were measured at baseline and at 3 months into treatment, as part of the National Cancer Institute (NCI) Protocol 79-C-111, randomizing breast cancer patients to lumpectomy/radiation v mastectomy. Patients who were found to have positive axillary lymph nodes also received combination chemotherapy (Adriamycin [Adria Laboratories, Columbus, OH], plus Cytoxan [Mead Johnson Pharmaceuticals, Evansville, IN] or methotrexate, plus 5-fluorouracil [5-FU]). Seventy-five patients were entered onto this behavioral immunology protocol at the time of data analysis. We reported in an earlier publication that NK activity was an important predictor of patient baseline prognosis relevant to nodal status. In that study, by using multiple regression analyses, 51% of the baseline NK activity variance could be accounted for by entering three distress indicators into the equation (patient "adjustment," lack of social support, and fatigue/depression symptoms). On reassessment of NK activity after 3 months, it was found that NK activity was not affected by the interim administration of chemotherapy and/or radiotherapy. However, consistent with our earlier findings, NK activity levels remained markedly lower in patients with positive nodes than in patients with negative nodes (at 60 to 1 effector to target cell [E:T] ratio, mean of 18% lytic activity v mean of 31% lytic activity [t = 1.87, P less than .05]). Even though average levels of NK activity were lower for patients with more tumor burden, there was still a substantial range of NK activity levels within the node positive patient group, as well as within the patient group as a whole. We hypothesized that differences in levels of NK activity could be predicted on the basis of baseline distress factors found to be significant in our earlier report. In fact, we found that we could account for 30% of NK activity level variance at 3 months follow-up on the basis of baseline NK activity, fatigue/depression, and lack of social support. Therefore, although neither radiation nor chemotherapy appeared to affect NK activity, tumor burden was again clearly associated with NK activity levels, and a significant amount of baseline and 3-month NK activity could be predicted on the basis of CNS-mediated effects. At the least, such factors provide a psychological marker of host biological status.
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PMID:Correlation of stress factors with sustained depression of natural killer cell activity and predicted prognosis in patients with breast cancer. 354 12


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