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Biomedical subjects

M Horvat

Publications and source records attributed to M Horvat.

At least 19 recordsLinked to original sources
PubMed1992

Preliminary study of the effects of some physical parameters on the stability of methylmercury in biological samples.

The effects of storage conditions (long-term storage of wet samples in a deep-freeze or thermal cycling), freeze-drying and gamma-irradiation at 1 and 5 Mrad on the stability of methylmercury in some biological samples were investigated. Methylmercury was determined by volatilization separation followed by gas chromatography and by ion-exchange separation of inorganic and organic species followed by measurement by cold vapour atomic absorption spectrometry (CVAAS). Total mercury was determined by CVAAS. Biological samples studied included fish and shellfish tissues, human hair and blood samples and appropriate reference materials. From the preliminary results obtained it can be concluded that fresh and dried fish muscle and fish certified reference materials show good stability with time and against temperature cycling. Shellfish and blood should not be repeatedly frozen and unfrozen otherwise possible losses of methylmercury can occur. Losses of methylmercury of up to 30% from wet mussels occurred on prolonged storage in a deep-freeze. Gamma-irradiation reduced the methylmercury content of the fish and shellfish only for hake (Merluccius merluccius). Further experiments should be carried out to confirm this and to investigate if this effect is species dependent. Apparent losses of methylmercury on freeze-drying of blood need to be reconfirmed on further samples.

Animals↗
PubMed1992

Investigation of mercury speciation in lichens.

Epiphytic lichens have long been considered to be reliable bioindicators of air pollution. In the present study only one lichen species, Hypogymnia physodes (L.) Nyl., was chosen; this species is very often used for biomonitoring in Europe. Total mercury and methylmercury were determined in lichens taken from various polluted and unpolluted locations in Slovenia, including a mercury mining area around Idrija. Additionally, total gaseous mercury in air was also determined at several sampling points.

Air Pollutants↗
PubMed1990

Romano-Ward syndrome: case report, family study and signal averaged electrocardiogram.

A family with the Romano-Ward syndrome is described. A 28-year-old woman had episodes of syncope due to self-terminating ventricular tachycardia torsades de pointes. During lidocaine treatment she developed a sustained ventricular tachycardia and cardiopulmonary resuscitation was necessary. Propranolol reduced ventricular ectopic activity, but the QTc interval remained prolonged. A "threshold" in QT duration for the generation of complex ventricular arrhythmias was observed in the patient. There were no late ventricular potentials noted in the signal averaged ECG in the patient and in members of her family.

Adult↗
PubMed1989

The mortality of childhood falls.

Falls accounted for 5.9% of the childhood deaths due to trauma in a review of the medical examiner's files in a large urban county. Falls represented the seventh leading cause of traumatic death in all children 15 years of age or younger, but the third leading cause of death in children 1 to 4 years old. The mean age of those with accidental falls was 2.3 years, which is markedly younger than that seen in hospital admission series, suggesting that infants are much more likely to die from a fall than older children. Forty-one per cent of the deaths occurred from "minor" falls such as falls from furniture or while playing; 50% were falls from a height of one story or greater; the remainder were falls down stairs. Of children falling from less than five stories, death was due to a lethal head injury in 86%. Additionally, 61.3% of the children with head injuries had mass lesions which would have required acute neurosurgical intervention. The need for an organized pediatric trauma system is demonstrated as more than one third of the children were transferred to another hospital, with more than half of these deteriorating during the delay. Of the patients with "minor" falls, 38% had parental delay in seeking medical attention, with deterioration of all. The trauma system must also incorporate the education of parents and medical personnel to the potential lethality of "minor" falls in infants and must legislate injury prevention programs.

Accidental Falls↗
PubMed1989

Paradoxical elevation of pulmonary vascular resistance after nifedipine in primary pulmonary hypertension. A case study.

The case of a 55-year-old woman with primary pulmonary hypertension is described who developed 2 hours after sublingual administration of a 10 mg capsule of nifedipine a severe rise in pulmonary arterial and right atrial pressures accompanied with dyspnoea and cyanosis. The event lasted for two hours and subsided without intervention. With repeated nifedipine intake in the form of orally administered slow-release tablets no complications occurred. The authors ascribe the marked rise in pulmonary vascular resistance to rapid reduction of plasma nifedipine concentration after sublingual administration, due to a faster drug resorption compared to oral intake. The necessity of cautious introduction of vasodilating drugs in pulmonary hypertension and of gradual dosage increase is stressed.

Administration, Oral↗
PubMed1986

A comparison of the psychological characteristics of male and female able-bodied and wheelchair athletes.

The purpose of this study was to compare selected psychological characteristics between male and female able-bodied and wheelchair athletes. All subjects completed the Profile of Mood States (POMS). Morgan (1980) has reported that based on the POMS elite able-bodied male and female athletes possess superior mental and emotional health compared to the general population. Based on this investigation, this result can now be extended to male and female wheelchair athletes.

Adaptation, Psychological↗
PubMed1985

Arrhythmias with brief, high-dose intravenous streptokinase infusion in acute myocardial infarction.

Cardiac arrhythmias are described during the first 2 h after brief, high-dose, intravenous streptokinase infusion in 23 patients with evolving myocardial infarction was given. A control group consisted of 22 similar patients with acute myocardial infarction not treated with streptokinase infusion. On the basis of an early peak of creatine kinase activity successful reperfusion was achieved in 60.9% of patients. Significantly more ventricular premature complexes (P less than 0.01) and paroxysms of idioventricular rhythm (P less than 0.05) were noticed in the treated group. Premature ventricular complexes did not predict any severe ventricular arrhythmia. Accelerated idioventricular rhythm appears to be the most specific arrhythmia encountered with thrombolytic therapy of acute myocardial infarction. We propose that in routine clinical work it can be used as a bedside sign of successful reperfusion.

Adult↗
PubMed1985

Use of the State-Trait Anxiety Inventory for visually impaired athletes.

This report detailed the reliability of the State-Trait Anxiety Inventory when the test statements were presented verbally and in the traditional manner to undergraduates, 19 men and 17 women, who were physical education majors. In the standardized manner subjects read the statements silently to themselves; in the other administration statements were read aloud. The inventory then was administered twice verbally to 15 elite visually impaired women athletes. Both the state and trait subscales of this inventory are reliable if presented across or within modalities. The inventory, when presented verbally, might be appropriately used by visually impaired athletes in psychological preparation prior to competition.

Adolescent↗
PubMed1984

Electrophysiological effects of ethmozin on sinus nodal function in patients with and without sinus node dysfunction.

The electrophysiological effects of intravenously administered ethmozin (1 mg kg-1) on sinus node function were examined in 32 patients. Based on their clinical data and the results of the initial study, patients were subdivided into group A (n = 12), those with sick sinus syndrome and sinus node recovery time (SNRT) greater than 1500 ms, and group B (n = 20), those without overt sinus node dysfunction and a normal SNRT. The mean sinus cycle length did not change significantly in either group after ethmozin . SNRT was prolonged by ethmozin in group A whereas in group B the increase of SNRT was not significant. Corrected SNRT increased after ethmozin in both subgroups but with a much more pronounced increase in group A. Sinoatrial conduction time was not significantly changed in any group. The lengthening of SNRT in the majority of patients with sick sinus syndrome implies that ethmozin might prolong post-tachycardia pauses in these patients. This drug should therefore be administered cautiously to persons with signs indicative of dysfunction of the sinus node.

Adolescent↗
PubMed1983

Latent sinoatrial conduction disturbances in symptomatic patients with Wolff-Parkinson-White syndrome.

Sinoatrial conduction abnormalities were studied in fourteen patients with Wolff-Parkinson-White (WPW) syndrome and frequent attacks of supraventricular paroxysmal tachycardia. Sinoatrial conduction time (SACT), obtained by the method of constant atrial pacing, was prolonged in all but two patients. The mean value was 277 +/- 56 ms (mean +/- SD). SACT was measured in the same way in sixteen patients without signs of pre-excitation or sinoatrial disease; SACT was significantly shorter (p less than 0.001) than in the WPW group of patients. The prolongation of SACT in patients with WPW syndrome was confirmed by measuring SACT by the alternative method of programmed atrial stimulation. SACT was found to be prolonged in eight patients (mean +/- SD = 239 +/- 47 ms). Whether our results should be attributed to WPW syndrome or frequent supraventricular tachycardias--both being a characteristic feature of our patients--remains uncertain. The results of this study, however, indicate that in symptomatic patients with WPW syndrome and frequent episodes of supraventricular tachycardia, sinoatrial conduction is frequently impaired. Slackening of the sinoatrial conduction is a possible predisposing factor for initiation of tachycardias in the WPW syndrome.

Adult↗
PubMed1982

Induced concealed dissimilar atrial rhythms.

Electrophysiologic studies, including intra-atrial recordings and atrial stimulation, were performed in two patients with suspected sick sinus syndrome. Premature atrial stimuli induced atrial flutter in both patients. The arrhythmia was concealed, i.e., it was recordable only by intracavitary electrogram and invisible on surface electrocardiogram. In one case, simultaneous atrial fibrillation could be recorded in a segment of the right atrium. In this patient, the rhythm on the surface electrocardiogram changed during the study to "upper nodal" rhythm, though the atrial electrogram showed continuation of A waves at the same rate as before during sinus rhythm. It seems that atrial changes, which are frequently encountered in sick sinus syndrome, are a predisposing factor for spontaneous or inducible concealed atrial arrhythmias.

Atrial Flutter↗
PubMed1979

The relation of heart rhythm to postextrasystolic potentiation.

In 9 patients with various forms of heart rhythms and rates, all of whom had a temporary pacemaker electrode inserted, several single premature ventricular contractions (PVC) with various coupling intervals (CI) were induced. The relative systolic area of the carotid pulse curve in the postextrasystolic beat was used as an indicator of the degree of postextrasystolic potentiation (PESP). A close correlation between PESP and CI was found only in sinus rhythm patients (r = -0.85). The patients with junctional and ventricular rhythms had no PESP regardless of CI or the degree of heart failure. Compensatory pause (CP) in these patients surprisingly related (r = 0.95) to heart rate, slower rates having a shorter relative CP.

Cardiac Complexes, Premature↗