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Biomedical subjects

J Horký

Publications and source records attributed to J Horký.

At least 19 recordsLinked to original sources
PubMed2001

Low-power water suppression by hyperbolic secant pulses with controlled offsets and delays (WASHCODE).

A class of chemical-shift-selective (CHESS) water suppression (WS) schemes is presented in which the characteristic frequency-domain excitation profiles of "adiabatic" full-passage (AFP) RF pulses are utilized for frequency-selective excitation of the water resonance. In the proposed WS schemes, dubbed WASHCODE, hyperbolic secant (HS) pulses were used as the AFP pulses. Besides the high immunity of WS efficiency toward B(1) inhomogeneity, these sequences also exhibit extraordinary insensitivity to the dispersion of the water T(1) relaxation times. The actual performance of the proposed WS schemes was achieved in particular by optimizing the frequency offsets of WS HS pulses and the time intervals between them. To reduce the RF power requirements of these WS sequences for in vivo applications, HS pulses with the minimum possible frequency bandwidths were employed, which also substantially reduced the adverse effects on the observed proton MR spectra. The proposed WS schemes were evaluated by simulations based on the Bloch equations. Several WS sequences which looked particularly promising were verified experimentally on the human brain on a 3 T MR scanner using very short echo-time STEAM for volume selection and a standard single-loop surface coil for both signal transmission and reception. Routinely, water-suppression factors ranging from 2000 to 4000 were achieved in vivo without additional adjustment of parameters for individual subjects and without violating legal safety limits.

Brain↗
PubMed1990

Bilirubin and bile acids removal by haemoperfusion through synthetic resin "Persorb".

A new type of styrene-divinylbenzene copolymer coated with polyhema was tested for biocompatibility and ability to remove bile acid, bilirubin, phenols and cholesterol in dogs with surgically induced biliary obstruction. After 4-hr hemoperfusion through a polypropylene column containing 325 g of resin, performed 7-10 days after the ligature of the cystic and common bile duct, the serum levels of bile acids, bilirubin, phenols and cholesterol decreased by 60.9 +/- 30.3% (p less than 0.001), 34.8 +/- 12.2% (p less than 0.001), 19.4 +/- 15.6% (p less than 0.001) and 15.3 +/- 4.2% (p less than 0.05), respectively. The procedure was well tolerated, no bleeding or other adverse reactions occurred. The average platelet count decreased by 19.4 +/- 15.6% (p less than 0.05). Hemoperfusion through the Czechoslovak resin coated with polyhema is safe and efficient for removal of bile acids and other protein-bound and lipid-soluble substances which accumulate in cholestatic syndromes and hepatic failure. Thus, it may play an important role in the treatment of such events as a method of artificial liver support.

Animals↗
PubMed1989

[A prospective prognostic study of liver cirrhosis].

The authors conducted a prospective, longitudinal, multicentre study in patients with liver cirrhosis; a total of 192 patients were on follow-up, of this number 125 died during the study. Mean age, 56 years, was markedly more advanced in the dead; men prevailed among the patients. Duration of complaints and the interval since the diagnosis had been established was shorter in the dead than in those alive; a positive HBs antigen was likewise more often present in the former. Clinical and laboratory parameters in this group were assessed with a view to the differences between the dead and those alive and with a view to the time course of changes in these differences. Multifactorial discriminative analysis of these data for various intervals before death was also performed. The most pronounced differences were noted in clinical manifestations and laboratory signs of hepatic insufficiency, especially in the presence and degree of ascites, jaundice, encephalopathy, and in the values of bilirubin, Quick' test and blood albumin levels; thus the degree of liver insufficiency appears to be the most important prognostic marker in patients with liver cirrhosis. Moreover, a significant increase in urea and leucocyte levels was found in the terminal stages of the disease. Ascites, encephalopathy and a progressive increase in serum bilirubin levels seem to be the best markers for discriminative analysis of prognosis for the last six months of life. Results of this study, while confirming some findings by other authors, offer also new insights into the whole issue.

Female↗
PubMed1989

[Heart catheterization: experience with 1000 examinations].

Catheterization of the right and left heart by the percutaneous technique, incl. Rashkind's septostomy, was performed in 1000 patients with body weights from 2 kg and above between 1977 and 1984. The technique of the examination is described. The patients belonged to the following age groups: 1st day to one year--28%, 1-5 years--28.6%, 6-15 years--31.9%, above 15 years--11.5%. The authors recommend to reduce the incidence of complications by continuous monitoring of the blood pressure during catheterization by means of an arterial catheter. As to complications, they recorded three deaths within 24 hours after catheterization: 2 infants and one adult patient, i.e. a mortality rate of 0.3% as compared with 1.5-3% reported in the literature. As to serious dysrhythmias, there was once ventricular tachycardia and one ventricular fibrillation. In two patients during angiocardiography the contrast substance was injected into the myocardium. Cardiac tamponade was described twice. In one infant on the second day after catheterization a thrombus was removed from the femoral artery. A computer proved useful for the calculation of haemodynamic data.

Adolescent↗
PubMed1987

Depression in spontaneous cell-mediated cytotoxicity occurs during hemodialysis.

NK activity against K 562 target cells and the percentage of HNK-1+ lymphocytes in peripheral blood were evaluated in 24 patients on maintenance hemodialysis prior to and during post hemodialysis session. No difference was found in the NK activity of these patients before hemodialysis and normal subjects. On the other hand patients had a decreased number of HNK-1+ cells. During hemodialysis, the NK activity as well as the HNK-1+ cell count decreased. No correlation was found between these parameters and either the cause of end-stage renal disease or the duration of dialysis treatment. In addition no correlation was observed between NK activity and the number of HNK-1+ cells.

Adult↗
PubMed1986

Manifestation of radiation injury of human lymphocytes using PHA mitogenic stimulation in different culture systems.

The proliferative response of human lymphocytes to PHA in vitro is affected by X-irradiation. Dose-related changes of mitogenic stimulation of irradiated lymphocytes were compared in two culture systems--cultivation of separated lymphocytes and cultivation of whole blood. In whole blood cultures, the proliferative activity of stimulated lymphocytes was markedly and reproducibly depressed by irradiation. The values of mitogenic response within a dose range from 0 to 2.5 Gy could be fitted with high correlation by an exponential curve. In a modified test where the mitogenic stimulus was given after 24 h delay, depression of the response was even more pronounced. Radiosensitivity of human lymphocytes as determined by means of mitogenic stimulation in whole blood cultures appears to be a characteristic individual feature. The mean D37 value of the radiation-induced depression of mitogenic response in a group of 20 healthy donors was 2.5 Gy in the standard test and 2.0 Gy in the test with a delayed mitogenic stimulus. In contrast, the data obtained from separated lymphocyte cultures were characterized by a high degree of the test-to-test variability and by much lower radiosensitivity. The possible mechanisms of these distinctive manifestations of the same primary radiation injury are discussed.

Adult↗