Biomedical subjects

J Horák

Publications and source records attributed to J Horák.

At least 19 recordsLinked to original sources

PubMed1992

Transport of L-glutamic acid in the fission yeast Schizosaccharomyces pombe.

Transport of L-glutamic acid into the fission yeast Schizosaccharomyces pombe grown to the early stationary phase and preincubated for 60 min with 1% D-glucose is practically unidirectional and is mediated by a single uphill transport system with a KT of 170 microM and Jmax of 4.8 nmol min-1 (mg dry wt.)-1. The system proved to be rather non-specific since all the amino acids transported into the cells acted as potent competitive inhibitors. It has a pH optimum at 3.0-4.0, the accumulation ratio of L-glutamic acid is highest at a suspension density of 0.6-1.0 mg dry wt. per ml and decreases with increasing L-glutamic acid concentrations in the external medium. The system present in the cells after preincubation with D-glucose is unstable and its activity decays after washing the cells with water or after stopping the cytosolic proteinsynthesis with cycloheximide, with a half-time of 24 min in a reaction significantly retarded by phenylmethylsulfonyl fluoride, a serine proteinase inhibitor. The synthesis of the transport protein appears to be repressible by ammonium ions.

Biological Transport↗

PubMed1992

Thialysine-resistant mutants and uptake of lysine in Schizosaccharomyces pombe.

Mutants defective in lysine transport were isolated and characterized. After UV-mutagenesis colonies resistant to thialysine, a toxic analogue of lysine, were isolated and L-lysine uptake into the mutant strains was analyzed. Among the thialysine-resistant strains a group of mutants was found, where the half-saturation constant, KT, of the high-affinity transport system for lysine was higher than in the wild-type, the high-affinity transport system for basic amino acids being specifically affected. This was confirmed by a complementation test in which all the thialysine-resistant strains with a higher KT for lysine uptake belonged to one complementation group. Kinetic and genetic analysis showed that our mutants were identical with can1-1 mutants, showing that a single high-affinity system for the transport of basic amino acids exists in S. pombe.

Arginine↗

PubMed1992

Left main coronary artery stenosis.

Between 1 January, 1989, and 28 April, 1990, a total of 888 selective coronary arteriographies were performed at the Institute for Clinical and Experimental Medicine in Prague. Of that number, 58 findings were assessed as at least 50% stenosis of the left main coronary artery (LCA). Having applied exclusion criteria, 50 patients (i.e., 5.63% of all those examined) were entered into a retrospective study. They were 45 men (90.0%) and 5 women (10.0%) with significant cumulation of risk factors for IHD; more than half on them had a history of coronary event. The patients had marked symptomatology--NYHA Class III and higher angina pectoris was present in 96%, a low tolerance of exercise was found in 26 patients undergoing ergometry (average workload of 13 kJ and heart rate of 111/min); exercise testing was invariably evaluated as positive. Coronary angiography regularly revealed multiple coronary artery lesions; the right coronary artery was also involved in 90%; a collateral circulation was present in as little as 34%. The localization of coronary stenoses and the mostly preserved left ventricular mechanical function allowed operative management of IHD in 84% of cases. In the group of patients undergoing surgery, hospital mortality was 4.8%. On long-term follow-up (mean 6.2 months) of the group of patients operated on, 59.9% were free of problem, 31% had NYHA Class II angina pectoris, and there was no improvement at all in one patient only (2.4%). In the group provided conservative therapy (not operated on primarily for severe left ventricular dysfunction), one patient died of recurrent myocardial infarction and cardiogenic shock, 2 have NYHA Class IV angina pectoris, and the remaining subjects continue experiencing NYHA Class III problems.

Adult↗

PubMed1992

[Alcohol block of the celiac plexus in severe visceral pain].

The authors present their own experience with percutaneous alcohol block of the coeliac plexus. Between April 1988 and December 1991 they used it in 22 patients. Except one patient the others suffered from severe pain of abdominal organs associated with carcinoma of the pancreas. The first four operations were made using angiography, the remainder under CT control. During evaluation of results two weeks after the intervention complete regression of pain was recorded in six patients. A partial effect was achieved in 11 patients, and the intervention failed in five patients. The intervention was repeated in four patients. The authors emphasize that the procedure is relatively simple and safe, and if successful, makes it possible to reduce or even eliminate opiates. It improves the quality of the remaining life of the patient.

Aged↗

PubMed1992

[The effect of mechanical support of the heart on the extent of experimental myocardial necrosis. I].

The authors investigated the influence of mechanical cardiac support with a non-pulsating blood flow on the size of an ischaemic after ligature of the descendent branch of the left coronary artery in the dog. As compared with a control group of experimental animals where mechanical cardiac support was not used, the size of the necrotic focus of the heart muscle diminished by 50% (p less than 0.01). In some of the experimental animals the size of the necrotic focus did not change despite the use of a mechanical cardiac support. Analysis of haemodynamic parameters (assessed and calculated) revealed that for the fate of the necrotic focus of the myocardium the degree of relief (decompression) of the left ventricle is decisive. In complete relief the necrosis diminishes in size.

Animals↗

PubMed1992

[Endomyocardial biopsy].

The authors present ten years' experience with endomyocardiac biopsy of the heart (EMB) using the percutaneous, endovasal catheterization needle technique. EMB was performed in 314 patients, a total of 1362 biopsies, and for evaluation 5564 specimens of cardiac tissue were taken. Based on this experience the authors emphasize methodical principles which make expedient, rapid and safe collection of cardiac tissue specimens possible. They also mention the main indication criteria for endomyocardial biopsy. Endomyocardial biopsy is a valuable clinical examination method which, no doubt, holds its place in the series of diagnostic methods of modern cardiological catheterization departments.

Biopsy, Needle↗

PubMed1991

Protein transport and compartmentation in yeast.

Many newly synthesized proteins must be translocated across one or more membranes to reach their destination in the individual organelles or membrane systems. Translocation, mostly requiring an energy source, a signal on the protein itself, loose conformation of the protein and the presence of cytosolic and/or membrane receptor-like proteins, is often accompanied by covalent modifications of transported proteins. In this review I discuss these aspects of protein transport via the classical secretory pathway and/or special translocation mechanisms in the unicellular eukaryotic organism Saccharomyces cerevisiae.

Amino Acid Sequence↗

PubMed1991

[Infantile cortical hyperostosis (the Caffey-Silvermann syndrome)].

In 1984-1989 at the First Paediatric Clinic of the Motol Faculty Hospital six patients with the diagnosis of infantile cortical hyperostosis (Caffey-Silvermann syndrome) were hospitalized. Non-familial concurrence of the disease was involved. All children developed the disease before the age of 4.5 months, four before the age of three months. Among the six patients was only one girl. As to pathological findings there was a markedly elevated FW in 5/6, leucocytosis in 5/6, thrombocytosis in 3/4, eosinophilia in 3/6, elevated alkaline phosphatases in 2/6. The affection was four times on the mandible, once in the area of the hip joints and in one instance it was multifocal. The authors present one detailed case-history with extreme affection of the clavicle which was originally taken for a bone tumour.

Female↗

PubMed1991

[The Camurati-Engelmann syndrome (progressive diaphyseal dysplasia)].

The presented case-history demonstrates an infant with a rare bone disease with a very serious prognosis. Based on X-ray findings on the skeleton (sclerosis of the diaphyses of long bones, ribs, vertebrae and in particular the base and vault of the skull), the diagnosis of morbus Camurati-Engelmann--progressive diaphyseal dysplasia was established. With regard to the striking progression of the process in the cranial area and the progressing stigmatization of the patient's face, the authors consider also a more recent diagnostic unit--craniodiaphyseal dysplazia. With advancing sclerotization of the skull the most serious complications are compression of the cranial nerves which can be resolved in the final stage only by surgery. From a brief review of the literature: the aetiology of the disease is not known, the therapeutic effect of prednisone or calcitonin is small.

Camurati-Engelmann Syndrome↗

PubMed1990

[Arteriovenous fistula complicating central venous catheterization].

Iatrogenic fistulae are sporadic but potentially serious complications of catheterization of central veins. The authors present the case-history of a 57-year-old patient with chronic renal failure where after 19 months following temporary insertion of a central venous catheter into the subclavian vein on the right from and infraclavicular approach a continual murmur was recorded in the right subclavicular area, along with increasing manifestations of left-sided cardiac insufficiency. Using digital subtraction angiography, the authors diagnosed an arteriovenous fistula between the internal thoracic artery and the right brachiocephalic vein. The described case draws attention to a rare complication of catheterization of the central veins and its possible haemodynamic sequelae.

Arteriovenous Fistula↗

PubMed1990

Phenylmethylsulfonyl fluoride protects L-lysine transport in Schizosaccharomyces pombe against inactivation by ammonium ions.

Ammonium ions inactivate the basic amino acid transport system in Schizosaccharomyces pombe in an irreversible manner. The inactivation is accompanied by a 4-fold decrease of KT of L-lysine transport, leaving its Jmax unchanged; phenylmethylsulfonyl fluoride protects the system against inactivation. In contrast, two basic amino acid transport systems in a gap1 mutant of Saccharomyces cerevisiae are influenced by NH4+ ions in such a way that only the Jmax decreases while the KT of L-lysine transport is unchanged. Phenylmethylsulfonyl fluoride does not act here as a protective agent.

Ammonia↗

PubMed1990

[Intra-arterial chemotherapy in inoperable and recurrent rectal tumors].

Intraarterial chemotherapy was used to affect inoperable or relapsing tumors of the rectum or rectosigmoid. Seldinger's approach was used to catheterize both internal iliac arteries and recently also the inferior mesenteric artery in the second stage. Of the cytostatics mitomycin C 2 x 10 mg/2 h and fluorouracil 2 x 500 mg/24 h were administered over four days. No skin damage was observed in the region supplied by the branches of the catheterized arteries as simultaneously hydrocortisone was administered intraarterially in doses of 2 x 50 mg/24 h in the first two days and 2 x 25 mg/24 h in the remaining two days. No adverse effects of the treatment were recorded. Of the nine patients over 50% regression was achieved in 3 cases established by CT, stabilization of the process in 2 cases, and in 4 cases objectivization failed. Remission of symptoms and improvement of performance was observed in 8 patients, in 1 patient the method failed to be effective. Intraarterial chemotherapy of the pelvic region is considered suitable also for preoperative cytoreduction.

Aged↗

PubMed1990

[Possibilities of diagnostic imaging in nephroblastomatosis].

Nephroblastomatosis means persisting embryonic, undifferentiated cells of renal blastoma which may give rise to a nephroblastoma. The foci of nephroblastomatosis create intrarenal nodi or a subcapsular border. The present scanning methods make it possible to correctly differentiate nephroblastomatosis in most cases and to differentiate it from most lesions previously hard to recognize from each other, while CT and arteriography represent the most sensitive methods. The main problem of differential diagnosis is still to differentiate nephroblastomatosis from nephroblastoma. For solving this problem it is frequently necessary to use more diagnostic methods including invasive arteriography and biopsy. It is the only way to prevent damage of the child by incorrect and most by too radical therapy. For the danger of the development of nephroblastoma even after regression of nephroblastomatosis in the X-ray picture a long-term observation is necessary, the ultrasound examination being the method of choice.

Angiography↗

PubMed1990

Right ventricle in patients after orthotopic heart transplantation.

Eighteen patients were examined by echocardiography one month before, and one month after orthotopic heart transplantation (OHT). The right-heart echocardiographic parameters were compared with pulmonary haemodynamics. All recipients showed increased mean pulmonary artery pressure (PAP) (42 +/- 8 mmHg) and pulmonary vascular resistance 3.0 +/- 1.3 u.) before OHT. The causes of the pulmonary hypertension, and indications for OHT, were the end stage of dilated cardiomyopathy (n = 8), ischaemic heart disease (n = 9) and aortic valve disease (n = 1). After transplantation, the donor's right ventricle dilates due to the recipient's elevated pulmonary vascular resistance. The right ventricular dimension after OHT was greater than 30 mm in 1/3 of patients. The right ventricular diastolic dimension correlates statistically significantly with mean PAP of the recipient before the procedure. Right ventricular dilatation is accompanied by a mild degree of tricuspid insufficiency (in 89% of cases), as documented by Doppler examination. Neither the degree of right ventricular dilatation, nor the degree of tricuspid insufficiency show a tendency to progression during follow-up.

Adult↗

PubMed1990

[Endomyocardial biopsy and acute rejection in heart transplantation].

Nearly 6-year experience with EMB in patients with transplanted heart concerned especially problems of acute rejection. EMB proved to be a sensitive and for the time being unique method for the detection of acute rejection in patients treated by Cyclosporine immunosuppression. EMB were also criterion of correctness of immunosuppression because they reflected changes in treatment.

Acute Disease↗

PubMed1989

[Ultrasonic examination of the epigastrium in persons with Gilbert's syndrome].

In 29 subjects with Gilbert's syndrome during ultrasonographic examination of the epigastrium in real time a significantly larger anteroposterior dimension of the right liver lobe (by cca 11%] was found. In the other investigated dimensions no significant deviations were found, not even a significantly higher echogeneity of the liver parenchyma. In two instances multiple cholecystolithiasis was detected. Sonography, a non-invasive method with a high yield, is an important link in the examination programme of subjects with Gilbert's syndrome.

Abdomen↗

PubMed1989

Transport of L-lysine in the fission yeast Schizosaccharomyces pombe.

Systems of L-lysine transport in Schizosaccharomyces pombe are not constitutive, as at no phase of growth in a rich medium is lysine taken up. Transport activity appears only after preincubation of harvested cells with glucose or another suitable source of energy. If cycloheximide is added during this preincubation no transport systems are synthesized. After removal of glucose, the activity of the transport system decays with a half-time of 13 min. The transport of L-lysine into S. pombe cells from the stationary phase of growth preincubated for 60 min with 1% D-glucose is mediated by at least two systems, the high-affinity one with a Kt of 26 mumol/l and Jmax of 4.95 nmol/min per mg dry wt., the low-affinity one with a KT of 1.1 mmol/l and Jmax of 11.8 nmol/min per mg dry wt. The transport of lysine mediated by these two systems proceeds uphill. The high-affinity system has a pH optimum at 4.0-4.2, the accumulation ratio is highest at a cell density 2-5 mg dry wt. per ml and decreases with increasing lysine concentrations. Lysine accumulated by this system does not exit from cells. The only potent competitive inhibitors are L-arginine, L-histidine and D-lysine. The other amino acids tested do not behave as competitive inhibitors. Of the various metabolic inhibitors tested, the most potent were proton conductors and antimycin A.

Biological Transport, Active↗

PubMed1989

Diagnostic haemoperfusion.

Haemoperfusion and standard blood culture techniques were compared in the recovery of pathogenic Escherichia coli and Staphylococcus aureus strains circulating in the blood of rabbits with experimental bacteriaemia. On the average, diagnostic haemoperfusion gave positive isolations in 93.3%, blood cultures in 51.7%. This difference in favour of haemoperfusion tended to increase with the decreasing intensity of bacteriaemia. Clinically, haemoperfusion helped to establish correct diagnosis in a 46-year-old female patient with diabetic nephropathy and absceding staphylococcal pyelonephritis, whose blood and urine cultures were repeatedly negative. In this patient the authors succeeded in isolating the cause of septicaemia with the aid of the Czechoslovak haemoperfusion column Hemasorb 400 C. This study implies that diagnostic haemoperfusion used for the isolation of pathogens from blood is more reliable and less time-consuming than routine culture techniques.

Animals↗