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Biomedical subjects

R Kurz

Publications and source records attributed to R Kurz.

At least 19 recordsLinked to original sources
PubMed1992

Paraparesis secondary to a spinal mass as the presenting feature of erythroleukaemia in a 10-month-old child.

Severe neurological impairment as the first symptom of acute leukaemia is a rather uncommon finding. We report the case of a 10-month-old infant who presented with acute paralysis of the lower extremities due to cord compression by an epidural tumour composed of malignant erythrocyte precursor cells. Diagnosis of erythroleukaemia (EL) was made by needle biopsy of the spinal epidural mass and confirmed by bone marrow aspiration. Antileukaemic treatment in combination with radiotherapy to the epidural tumour led to haematological remission and neurological recovery with disappearance of the mass lesion as demonstrated by MRI. However, haematological relapse occurred with death of the patient 7 months after diagnosis. This is the first reported case of EL presenting with paraparesis due to an epidural tumour. The clinical symptoms, results of cytogenetic and immunological studies and the clinical course are described.

Biopsy, Needle↗
PubMed1992

Electrophysiological effects of myocardial stretch and mechanical determinants of stretch-activated arrhythmias.

BACKGROUND: Although the existence of myocardial mechanoelectrical feedback is well established, the mechanism of arrhythmia induction by ventricular dilatation or stretch remains insufficiently defined. In particular, controversy exists when comparing the arrhythmogenic potential of chronic versus acute myocardial stretch. Also, assessment of cellular electrophysiological effects of myocardial stretch has been incomplete. METHODS AND RESULTS: To evaluate the electrophysiological and arrhythmogenic effects of slow versus rapid ventricular wall stretch, we developed an isolated Langendorff-perfused rabbit heart model in which left ventricular (LV) volume can be changed by a computer-controlled servopump. Cellular electrophysiological effects and premature ventricular excitations (PVEs) and their origin produced by the volume increases were assessed by a multiple-site monophasic action potential (MAP) recording system and by volume-conducted ECGs obtained by immersing the entire preparation in a saline-filled tank. Volume was increased either gradually with slow volume ramps (0.1 ml/sec) or suddenly by volume pulses of varying pulse waveforms (three different amplitudes and five different rise velocities) applied randomly 250-350 times to each of eight hearts. Gradual LV volume loading caused gradual decreases in MAP resting and action potential amplitude, whereas rapid, transient volume pulses caused transient depolarizations. Despite similar membrane potential effects of stretch, gradual volume increases rarely (11%) produced PVEs, even with large volume loads, whereas rapid volume pulses of moderate amplitudes regularly triggered PVEs (45-100% of interventions). Logistic regression analysis showed that the probability of PVE occurrence increased independently with both the amplitude and the velocity of the volume increase, with the greatest sensitivity to stretch velocity exhibited at low and intermediate pulse amplitudes. Faster volume pulse rise velocities triggered PVEs at a lower instantaneous pulse amplitude than lower rise velocities, further corroborating the dependence of stretch-activated arrhythmias on the velocity of stretch. In contrast, an increase in the basic ventricular volume had no effect on the probability of PVE occurrence during the volume pulses. The MAP recordings demonstrated spatial variability in the extent of local depolarizations and site of PVE origin; transient depolarizations occurred, and PVEs originated most often in the posterolateral region of the left ventricle. CONCLUSIONS: Membrane depolarization is caused by both gradual and rapid ventricular stretch, but PVEs are more easily elicited by rapid stretch. Regions of greater myocardial compliance that experience greater relative stretch may act as "foci" for stretch-activated arrhythmias during dynamic ventricular loading. These whole-heart data corroborate the existence of stretch-activated membrane channels in ventricular myocardium and may help explain ventricular ectopy under conditions of differential ventricular loading, as in ventricular dyskinesia, or regional muscle traction, as in mitral valve prolapse syndrome.

Animals↗
PubMed1992

Case report: acute renal failure, thrombocytopenia and nonhemolytic icterus probably caused by mefenamic acid (Parkemed)-dependent antibodies.

A 65-year-old, previously healthy man developed acute renal failure, severe thrombocytopenia and hepatic icterus after a small dose of mefenamic acid (Parkemed). Drug-dependent antibodies reacting against platelets could be identified as the most probable cause for this acute and rapidly reversible disorder. A concomitant hemolytic reaction was not observed and accordingly no drug-dependent red cell antibodies could be demonstrated. The drug-specific antibodies were found only during the acute phase using the platelet immunofluorescence test and a solid-phase immunoassay but not with the monoclonal antibody specific immobilization of platelet antigens assay. After discontinuation of the drug the patient steadily improved and fully recovered until day 22 after admission and drug removal. The clinical course strongly suggests that drug-dependent antibodies against mefenamic acid and/or its metabolites reacting by immune complex mechanism were responsible not only for the thrombocytopenia but also for the renal and hepatic failure.

Acute Kidney Injury↗
PubMed1992

[Stress and susceptibility to infection].

The influence of various stressors upon the human immune system, was and presently is the subject of many clinically oriented as well as experimental studies. Even though it is not always clear how relevant the reported observations are in behalf to the beginning, the course and the outcome of infectious, neoplastic and autoimmune diseases, there is hardly any doubt, that stress may influence multiple aspects of the immune answer. The sensitivity of the immune system to stress factors is not merely fortuitous, but is an indirect consequence of the regulatory reciprocal influences between the immune system and the central nervous system. These interconnections seem to represent building blocks of a long-loop regulatory feedback-system, which plays an important role in the coordination of stressors and psychological influences upon the course of infections and inflammatory diseases.

Child↗
PubMed1992

[Clinical medicine versus homeopathy].

Due to the advance of alternative medicine a critical synopsis by means of the comparison between scientific medicine (clinical medicine) and homeopathy is warranted. The review of studies carried out according to current scientific criteria revealed--at best--a placebo effect of homeopathy. Until now there is no proven mechanism for the mode of action of homeopathy. Sometimes so-called "alternative medicine" prevents effective curative measures. In spite of the justified criticism concerning the technical over-estimation of classical medicine, scientific research should remain the basis of clinical work.

Child↗
PubMed1991

Carbamazepine maintenance treatment in outpatient schizophrenics.

A double-blind crossover trial was used to evaluate carbamazepine as the sole maintenance treatment of chronic, nonmanic schizophrenic outpatients whose conditions had been stabilized with the use of neuroleptics prior to study. Criteria of treatment effectiveness included the number of patients relapsing and time to relapse over a 95-day neuroleptic-free period during which either carbamazepine or placebo was administered. Relapse was determined by the concordance of psychiatric ratings and independent clinical judgements indicating significant worsening. Results for 27 patients (13 receiving carbamazepine and 14 receiving placebo) involved in the first phase of this treatment comparison were nondifferentiating. Corroborating descriptive findings in the second phase were available for 14 of these patients. There was no evidence supporting the existence of a treatment-relevant subgroup defined by episodic dyscontrol phenomena.

Adult↗
PubMed1991

Nitrogen and amino acid balance during total parenteral nutrition and continuous arteriovenous hemofiltration in critically ill anuric children.

Amino acid balance and nitrogen balance during total parenteral nutrition (TPN) and continuous arteriovenous hemofiltration (CAVH) were investigated in 11 critically ill anuric patients during the first 7 days after onset of anuria. Nitrogen intake ranged from 0.115 +/- 0.013 (SEM) g/kg/day on day 1 to 0.291 +/- 0.029 (SEM) g/kg/day on day 7. After 7 days of TPN, 9 patients had a positive cumulative protein-N balance of 287.52 +/- 68.52 (SEM) mg/kg, 2 patients had a negative balance of 781.8 and 1,103.2 mg/kg, respectively. Mean amino acid loss in ultrafiltrate was 0.159 +/- 0.008 (SEM) g/kg/day. Four patients died without recovery of renal function.

Acute Kidney Injury↗
PubMed1991

[The responsibility of medicine in adolescence].

Adolescence is a not very well defined time period between childhood and the adult age. The self esteem of an adolescent is neither that one of a child nor that one of an adult. If somatic, psychologic or psychosomatic complications or problems occur within this period, most of the adolescents disagree to be treated by a pediatrician, but they also disagree to be treated by "doctors for the elderly". Most of the complications or problems are specific for that age period; they are not well known to all medical doctors. Because of these reasons, specialists in adolescent medicine are mandatory for proper treatment. The most important problems or complications are dealing with puberty (early or delayed puberty, acne), growth, sexuality and sexual behavior, contraception, chronic disease and drugs.

Adolescent↗
PubMed1990

[Air pollution and sudden infant death in Graz 1982 to 1987].

We correlated the incidence of the sudden infant death syndrome (SIDS) and the degree of air pollution in each district of Graz over a time period of five years. The degree of air pollution was derived from a mapping of epiphytical lichen vegetation by Grill et al. (1988). We found an increased incidence of SIDS in districts with poor air quality. Although this result is not statistically significant a possible increase in SIDS risk because of air pollution cannot be excluded. Some pathophysiological explanations are discussed.

Air Pollution↗
PubMed1990

Neurological status, sleep apnea frequency and blood oxygenation in six weeks old infants.

A study was carried out to investigate the correlation between sleep apnea frequency, blood oxygenation and neurological condition in 21 infants at six weeks of age with inconspicuous medical history. Polygraphic recordings of respiratory behaviour and transcutaneous blood gas monitoring lasted for at least five hours. To quantify the results of the neurological examination we established a neurological optimality score (NOS). We found statistically significant correlations between several indexes of apneas and indexes of blood oxygenation and NOS. Thus, a reduced NOS was strongly correlated with higher apnea frequencies and with pronounced drops of transcutaneous PO2-values. In addition all but one infant who were diagnosed as having a sleep apnea syndrome showed a greater than ten percent reduction of NOS. Some pathophysiological considerations to explain our findings are put forward and the possible role of the neuromodulator adenosine is emphasized.

Humans↗
PubMed1990

Successful treatment of hemodialysis-related porphyria cutanea tarda with deferoxamine.

End-stage renal failure and long-term hemodialysis treatment promote the development of genetically conditioned porphyria cutanea tarda (PCT). The clinical manifestation is triggered off by unknown factors coexisting with renal insufficiency and hemodialysis. Iron overload is often associated with the disease and is thought to play a key role in its pathogenesis. Iron removal by deferoxamine infusions is regarded as the treatment of choice for patients who cannot undergo repeated phlebotomy procedures and has been successfully used in patients with normal renal function. We report a case of hemodialysis-related PCT and iron overload in whom repeated venesections were contraindicated on account of severe anemia and treatment with deferoxamine led to a striking improvement of symptoms.

Deferoxamine↗
PubMed1990

Factors involved in the pathogenesis of unexpected near miss events of infants (ALTE).

Near miss events or apparent life threatening events (ALTE) are considered preliminary stages of sudden infant death syndrome (SIDS). The current definition of near miss SIDS postulates that such an event happens unexpectedly and that no life threatening cause of disease can be detected. However in 32 of 34 observations of ALTE pathological changes actually could be identified by through investigations: 11 central nervous diseases, 10 respiratory tract disturbances, 5 metabolic abnormalities, 5 disturbances of the digestive tract and 1 cardiac disease. There were 22 morphologically manifested causes as opposed to 10 functional failures mainly respiratory control and oesophageal disturbances. Irrespective of the main diagnosis sleep apnea syndrome (SAS) could be detected in 17 of 28 infants combined with bradycardia in 5 cases, and oesophageal disturbances in 16 of 17 infants. Four babies later died, two of them suffered from carnitine deficiency and one from organic acidopathy. It is our conclusion that numerous, even banal causes of disease are able to trigger ALTE if there is a coincidence with phases of increased instability of vital regulatory mechanisms of autonomous centres in infants.

Brain Diseases↗
PubMed1989

[Stress adapted parenteral amino acid substitution in operated premature and newborn infants].

Parenteral nutrition contributes considerably to the survival of operated newborns. The postoperative period, however, gives rise to special metabolic problems. Commercially available L-amino acid (L-AA) solutions may lead to imbalances in the postoperative period. We used a preparation containing all essential and non essential L-AA, which should take the stress metabolism into account. Twenty newborn infants were treated with a standardized parenteral nutrition regime after major surgery. Two comparable groups were formed; the first (A) receiving up to 2 g L-AA/kg/day and the second (B) 1.5 g L-AA/kg/day at the most. On the seventh postoperative day group B was loaded with 1 g L-AA/kg within 6 h corresponding to the transfer rate in healthy newborn infants calculated by Bürger and Wolf. Plasma L-AA were checked on the seventh day before and after loading. The serum L-AA showed almost normal values in group A, however, several values were found to be too low in group B (proline, alanine, cystine, leucine). After the L-AA load some increased above normal levels (threonine, glycine, lysine, histidine). With reference to these results a daily application of 1.5-2.0 g of L-AA/kg can be recommended for critically ill newborns in the early postoperative period.

Amino Acids↗