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Biomedical subjects

R Wolk

Publications and source records attributed to R Wolk.

30 records · Page 2Linked to original sources
PubMed1998

Effects of lignocaine on dispersion of repolarisation and refractoriness in a working rabbit heart model of regional myocardial ischaemia.

The aims of this study were to establish a working rabbit heart model of regional myocardial ischaemia in which electrophysiologic parameters and arrhythmogenesis could be correlated and to explore the mechanisms underlying the antiarrhythmic activity of lignocaine. Monophasic action-potential duration (MAPD90), effective refractory period (ERP), and conduction delay were measured at three ventricular sites in isolated hearts paced at 3.3 Hz. The hearts were treated before and throughout 30 min of ischaemia and 15 min of reperfusion with a vehicle or 20 microM lignocaine. In both groups, ischaemia produced a similar shortening in MAPD90. Lignocaine decreased ERP shortening during ischaemia from -56+/-4 to -32+/-6 ms. An ischaemia-induced increase in conduction delay was greater in the lignocaine than the control group (49+/-7 vs. 11+/-2 ms). Ischaemia-induced dispersion of repolarisation was reduced by lignocaine from 66+/-4 to 32+/-7 ms, and dispersion of refractoriness was decreased from 57+/-6 to 16+/-3 ms. Lignocaine decreased inducibility of ventricular fibrillation (VF) during ischaemia from 86 to 25%. We conclude that, in this model, the antiarrhythmic activity of lignocaine during regional ischaemia is associated with an increase in ischaemia-induced conduction delay and reduced dispersion of repolarisation and refractoriness.

Action Potentials↗
PubMed1997

[Problems in the care of mentally handicapped adults in general hospitals].

The care of the mentally handicapped with their special needs and problems represents (despite written nursing theories and conceptions) a situation of stress and burden in the everyday life of a general hospital. The nursing staff organises their work with the mentally retarded often only on the basis of common sense without any specific professional knowledge. This analysis shows that a professional attitude has to deal with different phenomenon such as perception, communication, human dignity, but also with feelings of disgust when working with patients and being confronted with their problems. It is important to have basic knowledge on the mentally handicapped to understand their specific needs. This knowledge is essential in order to accept and tolerate mentally retarded people as a part of our social life.

Adult↗
PubMed1996

The incidence of asymptomatic paroxysmal atrial fibrillation in patients treated with propranolol or propafenone.

Anti-arrhythmic therapy for paroxysmal atrial fibrillation leads to complete symptomatic relief in a number of patients. The elimination of symptoms may be associated either with a complete elimination of arrhythmia or with a conversion of symptomatic atrial fibrillation into asymptomatic episodes of arrhythmia. The aim of the study was to evaluate the occurrence of asymptomatic paroxysmal atrial fibrillation in 52 patients treated with propafenone (35 drug trials) or propranolol (34 drug trials) by means of ambulatory ECG Holter monitoring. Propafenone was clinically effective (complete relief of symptoms) in 26 (74%) patients. However, in 7 cases (27%) asymptomatic episodes of arrhythmia were still recorded when awake. In patients treated with propranolol clinical symptoms were absent in 18 (53%). However, in 4 (22%) patients attacks of paroxysmal atrial fibrillation were present. The mechanism of drug-induced conversion of symptomatic episodes of atrial fibrillation into asymptomatic spells of arrhythmia was a marked shortening in duration of episodes in 7 patients (from 2215 +/- 3843 s to 16 +/- 10 s, N.S.) or by a significant slowing of ventricular response during atrial fibrillation in 4 patients (from 125 +/- 27 to 84 +/- 8 beats/min, P = 0.05). In conclusion, in a significant proportion of patients with symptomatic paroxysmal atrial fibrillation asymptomatic episodes of arrhythmia may occur while on anti-arrhythmic drug therapy. Some of these patients, particularly those with other risk factors for stroke such as advanced age or the presence of organic heart disease, may require anti-coagulant therapy or change in anti-arrhythmic treatment, and can be selected on the basis of ambulatory ECG monitoring.

Aged↗
PubMed1996

Central origin of decreased heart rate variability in patients with cardiovascular diseases.

Sympathetic activity influences the total power of the heart rate variability spectrum. Decreased heart rate variability and increased sympathetic tone have been related to poor prognosis and an increased risk of sudden cardiac death in patients with myocardial infarction, congestive heart failure or hypertension. On the basis of recent experimental data, I propose that these disease states are associated with altered spectral characteristics of the central sympathetic activity generated within rostral ventrolateral medulla neurones, which subsequently leads to decreased heart rate variability and increased systemic sympathetic tone.

Cardiovascular Diseases↗
PubMed1996

Nifedipine and captopril exert divergent effects on heart rate variability in patients with acute episodes of hypertension.

Acute changes of heart rate variability (HRV) depict alterations in autonomic influences on cardiovascular system and often precede ventricular arrhythmias. The aim of the study was to assess effects of sublingual 10 mg nifedipine (n = 15) or 25 mg captopril (n = 13) on HRV in consecutive patients admitted to hospital due to severe hypertension. HRV was calculated on-line from 300 cardiac cycles before and 60-90 min after drug administration. At baseline systolic blood pressure (SBP) was > 190 mm Hg and/or diastolic blood pressure (DBP) > 110 mm Hg. Both agents caused similar reduction of blood pressure (BP). Nifedipine reduced variance (-63 +/- 6%; P < 0.0001) and high-frequency (HF) component (-72 +/- 8%; P < 0.0001), and increased both LF/HF ratio (+870 +/- 336%; P < 0.02) and heart rate (+14 +/- 3%; P < 0.0001). Captopril exerted different effects: variance and HF component increased by +176 +/- 55%; (P < 0.007) and +126 +/- 44% (P < 0.015), respectively. LF/HF (low/high frequency) ratio decreased (-44 +/- 19%; P < 0.04) together with heart rate (-4 +/- 1%; < 0.009). It is concluded that captopril, in contrast to nifedipine, increases HRV and decreases LF/HF ratio and therefore is a better choice in hypertensive patients who might be prone to dangerous arrhythmias.

Acute Disease↗
PubMed1993

Micronutrition in dialysis.

A variety of dialysis methods are currently used in the treatment of renal failure. Nutrition support modalities are also frequently used for patients with renal failure who are malnourished or at risk of becoming malnourished. The effects of various dialysis methods on certain micronutrient levels and needs have generally not been extensively studied, however, this article reviews information that has been published regarding carnitine, water soluble vitamin, fat soluble vitamin, and trace element levels during dialysis. Recommendations for provision of micronutrients during dialysis are provided.

Carnitine↗
PubMed1986

Parenteral nutrition in obstetrics and gynecology.

Parenteral nutrition is required to maintain and restore an anabolic state when oral or enteral routes are not feasible. Despite 16 years of parenteral nutrition availability, reports about parenteral therapy in gynecologic patients or during pregnancy have not been published until relatively recently. Most information is anecdotal but suggests that this mode of therapy is safe, effective, and occasionally life-saving. Parenteral nutrition is used most commonly in women with gynecologic malignancies who are unable to obtain adequate nourishment either during or after surgery, radiation, or chemotherapy. Parenteral alimentation during pregnancy has been used mostly to provide adequate nutrition for those who suffer from prolonged hyperemesis or when there is difficulty in absorption of adequate nutrients. The proper selection and administration of dextrose, fat, protein, vitamins, trace elements, and electrolytes for pregnant women has been associated with apparent favorable perinatal outcomes. Preterm deliveries and intrauterine fetal growth retardation are relatively common and relate to the preexisting or a coexisting medical or obstetric complication. Nutritional assessment before therapy should include a detailed diet history and establishment of baseline clinical and laboratory parameters. Oral or enteral feedings should be attempted beforehand if possible to conserve high costs and potential complications. Parenteral requirements are extrapolated from recommended daily allowances for oral intake, allowing for adjustments in variable absorption. Standardized formulations and fat emulsions are available at pharmacies in many hospitals, making ordering of complex solutions easier, more efficient, and cost effective. Metabolic and septic complications occur infrequently with close monitoring. Few women require intravenous therapy for very long, and home parenteral nutrition is rarely necessary.

Adolescent↗
PubMed1975

Epilesional scarification. Preliminary report of a new approach to local immunotherapy with BCG.

Because of the serious toxicity of intralesionally injected BCG, including high fever, local ulceration, chronic drainage, and disseminated BCG disease, 13 patients received local BCG immunotherapy by the new approach of epilesional scarification. Three patients had complete responses, four had partial responses, and six had no response. Toxic reactions were minimal compared to those reported for intralesionally given BCG.

Adult↗
PubMedDate not supplied

Stability of imipenem and cilastatin sodium in total parenteral nutrient solution.

The chemical stability and compatibility of imipenem-cilastatin sodium (Primaxin) in two different total parenteral nutrient (TPN) solutions was determined. TPN solutions consisted of 4.25% and 5% amino acids with 25% and 35% dextrose, respectively. Imipenem-cilastatin sodium was constituted with 10 ml of sterile water and admixed with 90 ml of TPN solution for a final concentration of 5 mg/ml of each drug. The final solutions were assayed at times 0 (immediately after admixture), 15 min, 30 min, 1, 4, 8, and 24 hr by a stability-indicating high-performance liquid chromatographic assay. Concurrently, test TPN solutions were monitored for pH changes, color changes, and precipitate formation. The potential effect of imipenem-cilastatin sodium on the stability of amino acids and other TPN additives was not evaluated. Imipenem and cilastatin sodium was stable (greater than or equal to 90% recovered) in each TPN solution at 15 min. A significant (greater than or equal to 10%) and steady decrease of imipenem recovery occurred at subsequent sampling times. Cilastatin appeared more stable than imipenem in both TPN solutions. A physical color change from colorless to dark orange appeared in each TPN solution over the 24-hr study period. Imipenem-cilastatin sodium is stable for 15 min in the TPN solutions studied; however, until the stability of the amino acids can be determined, the antibiotic should be administered through a separate line or Y-site while the TPN infusion is interrupted.

Anti-Bacterial Agents↗