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Biomedical subjects

B J Karas

Publications and source records attributed to B J Karas.

10 recordsLinked to original sources
PubMed2000

Exercise-induced neurocardiogenic syncope: clinical data, pathophysiological aspects, and potential role of tilt table testing.

The evaluation of syncope occurring during exercise or occurring spontaneously in highly trained individuals presents a unique diagnostic challenge. It is of critical importance to exclude potential life-threatening disorders such as hypertrophic cardiomyopathy, long QT syndrome, right ventricular dysplasia, anomalous coronary artery distribution, valvular heart disease, myocarditis, or exercise-induced arrhythmia. This review is not directed towards identifying, treating, or determining athletic eligibility of individuals with such disorders. Rather, we endeavour to discuss the pathophysiology of exercise-induced neurocardiogenic syncope and to address the role of head upright tilt testing in evaluating syncope in athletic individuals in whom proper evaluation has excluded the presence of ischaemic heart disease or primary structural or electrical heart disease.

Electrocardiography↗
PubMed1998

Reentrant tachycardias. A look at where treatment stands today.

Cardiac dysfunction is not limited to the elderly. In fact, the forms of tachycardia discussed in this article usually begin before age 40. The authors summarize the mechanisms involved and the findings on electrocardiography that help identify the type of dysrhythmia in patients presenting with palpitations and other signs of possible cardiac disease. In addition, they describe the procedure that has revolutionized treatment for reentrant tachycardia: closed-chest radiofrequency catheter ablation.

Anti-Arrhythmia Agents↗
PubMed1993

Heparinization of biological vascular graft reduces fibrin deposition.

An alternative graft is needed for coronary bypass operations in patients lacking suitable autologous vessels. We therefore studied Denaflex, a biologic graft, in a dog ex-vivo shunt model to determine whether heparin treatment makes this graft less thrombogenic. Comparison was also made to Bioflow, a nonheparinized biologic graft. Fibrinogen deposition during high flow (593 +/- 202 ml/min) decreased from 672 +/- 467 ng/mm2 in nonheparinized Denaflex grafts to 448 +/- 298 ng/mm2 (p < 0.05) in heparinized Denaflex grafts. At low flow (117 +/- 13 ml/min), heparinization of Denaflex grafts similarly decreased fibrinogen deposition from 1102 +/- 601 ng/mm2 to 703 +/- 405 ng/mm2 (p < 0.05). At both flow rates fibrinogen deposition in Bioflow grafts was less than in nonheparinized Denaflex, but was similar to heparinized Denaflex grafts. Platelet deposition was not influenced by heparinization of Denaflex grafts and was similar among Denaflex and Bioflow preparations. Whether Denaflex performs acceptably in vivo as a xenograft requires extensive study.

Animals↗
PubMed1983

Twice-daily dosing of valproate with divalproex.

Equivalent doses of enteric-coated divalproex were substituted for valproic acid in 15 epileptic patients who were on a three- or four-times-a-day dosing schedule. After 2 wk the dosing regimen was changed to twice-daily divalproex dosing, and plasma levels were determined during the 12-hr period after the morning dose. Peak absorption was reached at 4 hr; extended plateaus were noted thereafter. The mean fluctuation between low and high plasma values for the group was 46%, with a decrease of less than 50% of peak levels in 9 of the 15 patients at a sampling time just before the second dose. Breakthrough seizures did not occur as a result of twice-daily dosing.

Absorption↗
PubMed1983

Treatment of valproate tremors.

Chronic valproate therapy induces symptomatic tremor in about 10% of patients. We studied the effects of propranolol, amantadine, diphenhydramine, benztropine, and cyproheptadine on these tremors in 19 patients by using serial accelerometric recordings. Propranolol was clearly the most therapeutic. Amantadine was moderately effective, but cyproheptadine, diphenhydramine, and benztropine gave little or no relief.

Amantadine↗
PubMed1983

Comparison of valproic acid and phenytoin in newly diagnosed tonic-clonic seizures.

Sixty-one newly diagnosed epileptic patients with generalized tonic-clonic, clonic, or tonic seizures were randomly allocated to treatment with valproate (VPA) and phenytoin (PHT). After 6 months, both drugs had been effective in preventing recurrence of seizures. Seventy-three percent of patients receiving VPA and 47% of patients receiving PHT had no recurrences. Side effects of either drug were mild. Laboratory abnormalities were similar for both drugs. Except for one PHT patient with toxic hepatitis, therapy was not discontinued.

Adolescent↗
PubMed1983

Gastrointestinal tolerance of divalproex sodium.

Divalproex sodium (DS), a new enteric-coated preparation of valproate, was administered to 27 patients who had not tolerated valproate because of gastrointestinal symptoms. Twenty-three (85%) tolerated DS and continued therapy. Of 34 patients previously naive to valproate, DS therapy was discontinued in only 4 patients (12%) because of gastrointestinal intolerance. Enteric-coated DS tablets had fewer gastrointestinal effects than VA capsules. Although the absorption of DS was delayed, the bioavailability of VA capsules and DS tablets was equivalent. After oral doses, peak plasma levels occurred within 1 hour with VA and at 3 hours with DS. Seven patients were maintained on a twice-daily schedule of DS.

Adolescent↗
PubMed1982

Valproate tremors.

We made accelerometric recordings of the tremor induced by valproic acid. The tremor was similar to essential tremor and appeared within a month of starting therapy. It was present at rest and exacerbated by action or antigravity positioning. There was no close correlation of tremor severity and plasma valproate level, but the tremor usually appeared at dosages greater than 750 mg per day. This tremor has appeared in 20 of 25 patients recently studied. In some patients the tremor is markedly active; however, others note only minimal tremor activity.

Adolescent↗