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Z Horák

Publications and source records attributed to Z Horák.

At least 19 recordsLinked to original sources
PubMed2006

[Method for assessment of distribution of UHMWPE wear particles in periprosthetic tissues in total hip arthroplasty].

PURPOSE OF THE STUDY: Aseptic loosening of implants is the main complication affecting the longevity of joint prostheses. The highest proportion of loosening occurs due to osteolysis produced by the presence of ultra-high molecular weight polyethylene (UHMWPE) wear particles smaller than 1 microm. These can be identified by microscopic, spectroscopic or light-scattering methods. Here we describe our method for counting wear particles, based on the principle of light scattering. MATERIAL AND METHODS: Between 2002 and 2004, we collected samples of polyethylene granuloma in 19 patients who underwent revision total hip arthroplasty (THA) for aseptic loosening. The samples were obtained from strictly defined areas corresponding to the radiographic presentation of periprosthetic zones describes by Gruen and DeLee in THA. The frozen samples were lyophilized and subjected to delipidation and hydrolyzation procedures in 65 % HNO3. The top part of solution containing wear particles was blended with isopropanol, and the mixture was filtered through a 10-microm polycarbon membrane. Subsequently, the filtrate was filtered through a 0.1-microm membrane. Membranes with trapped particles, 0.1 to 1.0 microm in size, were sent for particle characterization and quantification. The number of wear particles was measured by the method based on light scattering with calibration (LSC), using a Beckman Coulter LS230 analyzer that can express particle size distribution in a given volume in percent. The method was based on the fact that each particle reflects rays that can be measured. The medium measured contained an unknown number of UHMWPE particles and a known number of calibration glass beads varying in size. The number of UHMWPE particles was calculated from the known number of calibration beads. RESULTS: Because the collected samples were also used to develop the method, comprehensive data was obtained in six patients only. Particle distribution recorded in the periprosthetic zones in THA varied greatly; up to a five-fold difference in particle concentration was observed between the zones. In five of the six patients, the highest particle concentration was found in zone III. DISCUSSION: Seeking a method that would be exact, quick and cheap and would eliminate particle aggregation remains the subject of study for researchers cooperating with clinical practice. At present methods based on weighing isolated particles are used most frequently. We developed the LSC method that, for quantification, utilizes the ability of particles to disperse light, and allows us to calculate the real numbers of UHMWPE wear particles in a medium containing a known number of calibration particles. Although this is an indirect method, it gives more accurate results than the direct weighing of particles. The advantages of the LSC method involve less demand on sample purity, greater speed and low limits of detection. The method is useful for statistical evaluation of a larger number of samples. The variation in particle distribution in THA found in this study is in agreement with the relevant literature data; it is also in agreement with our assumptions and clinical findings. CONCLUSIONS: The authors developed an original method for assessment of UHMWPE wear particles in tissue samples, which is quicker than the methods so far used. In the periprosthetic tissues studied, particles about 1 microm in size were detected; their numbers (about 1010 particles per gram dry tissue) are in agreement with the literature data. The distribution of particles in periprosthetic zones in THA was uneven. The highest number of particles was found in the neighboring zone III and zone 7, as described by Gruen and DeLee. Key words: wear, polyethylene, total hip arthroplasty, light scattering, aseptic loosening, wear particles.

Arthroplasty, Replacement, Hip↗
PubMed2004

New fast method for determination of number of UHMWPE wear particles.

Ultra-high molecular weight polyethylene (UHMWPE) wear particles are the major cause of total joint replacement (TJR) failures because the wear particles, released from TJR's, cause bone loosening. To simplify the study of the relationship between numbers of particles at various locations around TJR's and extent of bone loosening at these locations, the authors of this work tried to develop a new method for easy and fast determination of number of wear particles. The method, called LSC (Light Scattering with Calibration spheres), is based on light scattering of a suspension of wear particles and calibration spheres, and yields relative numbers of particles. A modified LSC method, called LSCm, requires one additional experiment, a gravimetric analysis of a mixture of all studied samples, to determine absolute numbers of wear particles. LSC and LSCm methods are easy and fast, which make them suitable for processing and comparing high number of samples.

Calorimetry, Differential Scanning↗
PubMed2003

[Polyethylene disease].

PURPOSE OF THE STUDY: The experience obtained during revision surgery and findings of polyethylene granulomas in surrounding tissues of replacement as well as marked differences in the viability of implants resulted in the study of polyethylene disease and its basic mechanisms producing the development of osteoaggressive granulomas. We investigated the morphology of particles and their number in tissues surrounding the implant. The aim of our study was to develop a method for the detection of polyethylene particles in tissues, to identify different types of wear and to assess factors that may influence the viability of joint arthroplasty in general. MATERIAL: Every revizion of joint arthroplasty performed during the last five years was evaluated in terms of the presence of polyethylene granules and the viability state of articular polyethylene inserts. A total of 55 samples were taken from tissues around loosened endoprostheses. The location of each sample was exactly determined. METHOD: A technique was developed to identify wear particles and to visualize them after all organic structures of a polyethylene granuloma were dissolved with nitrogenic acid. RESULTS: The viability of articular polyethylene implants showed extreme differences in relation to different periods of manufacture and probably also to different methods of sterilization. Articular inserts sterilized with formaldehyde (the method used at the beginning of arthroplasty in our country) showed the highest viability and the lowest wear. The polyethylene particles present in tissues surrounding the implant were characterized in terms of morphology and size. DISCUSSION: The comparison of literature data and our results has revealed that there are many unknown facts about the quality and structure of polyethylene. The method of sterilization also appears to play a role. Because the issue is complex, we were not able to identify all factors leading, in some cases, to an early and unexpected failure of the implant and we consider further investigation to be necessary. CONCLUSIONS: Polyethylene disease is an important factor limiting the viability of joint arthroplasty. It results from a complex interaction of polyethylene particles arising by wear with surrounding tissues. The particles, less than 0.5 micron in size, are phagocytized by macrophages and, by complex mechanism of expression of inflammation mediators, they result in the inhibition of osteogenesis and activation of osteoclastic processes. The previous methods of sterilization with formaldehyde vapors apparently reduced wear influenced the resistance of polyethylene to wear to a lesser degree. A method was developed to detect these particles and to characterize their morphology in the tissues of a polyethylene granuloma.

Foreign-Body Reaction↗
PubMed2001

The validation of Kayzero-assisted NAA in Budapest, Rez, and Ljubljana via the analysis of three BCR certified reference materials.

After installation and calibration of k0-assisted NAA in three Central European research institutes (AEKI-Budapest, NPI-Rez, and IJS, Ljubljana), its validation was established via the analysis of three BCR certified reference materials. The matrices of choice were: CRM 277 estuarine sediment, CRM 038 coal fly ash from pulverized coal, and CRM 101 spruce needles. For some elements, e.g. Zn, Cd, and Hg, the analyses were not only performed instrumentally (INAA), but also in the radiochemical mode (RNAA). The work was performed in the framework of a European Copernicus Project.

Carbon↗
PubMed2001

Installation and calibration of Kayzero-assisted NAA in three Central European countries via a Copernicus project.

An account is given of the installation and calibration of k0-based NAA--assisted by the DSM Kayzero/Solcoi software package--at the KFKI-AEKI, Budapest, the NPI, Rez and the IJS, Ljubljana. Not only the calibration of the Ge-detectors and the irradiation facilities are discussed, but also other important topics such as gamma-spectrometric hard- and software, QC/QA of the IRMM-530 Al-Au flux monitor and the upgrade of the Kayzero/Solcoi code. The work was performed in the framework of a European Copernicus JRP, coordinated by the Laboratory of Analytical Chemistry, Gent, with DSM Research, Geleen, as the industrial partner.

Journal Article↗
PubMed1997

[Thallium perfusion scintigraphy and bicycle ergometry in the diagnosis of ischemic heart disease. Comparison with coronarography findings].

In 76 patients (66 men and 10 women, age 20-71 years) with stable angina pectoris planar thallium myocardial perfusion scintigraphy, bicycle ergometry and coronary angiography were performed. Thallium scintigraphy was highly sensitive (97%) for detection of ischaemic heart disease, the sensitivity of ergometry was 75%. When comparing patients with affected 1, 2 and 3 coronary arteries perfusion scintigraphy had a sensitivity of 100%, 90% and 100% resp., while bicycle ergometry 62%, 90% and 82% resp. The specificity of perfusion scintigraphy was low (47%), compared with ergometry (60%). The finding of s reversible perfusion defect during scintigraphy indicated significant affection of coronary arteries. The scintigraphic finding of diffuse myocardial ischaemic affection was not significant for assessment of the severity of the coronary artery disease.

Adult↗
PubMed1990

[Monitoring the course of non-A, non-B viral hepatitis in patients with chronic renal insufficiency].

A group of 35 patients with viral hepatitis non-A, non-B included in a chronic dialyzation programme was compared with a comparable group of 40 patients with viral hepatitis non-A, non-B. The mean period since the chronic dialyzation programme was started after the development of viral hepatitis non-A, non-B was 10 months. The mean period of hospitalization in the investigated group was 21 days and was practically identical (22 days) as in the control group. 45.7% of the patients in the chronic dialyzation programme were at the time when the diagnosis was established or in its course quite free from complaints. In 54.3% there were mild complaints. In the control group the number of patients with complaints was much higher (80%). In 82.9% patients included in the chronic dialyzation programme the viral non-A, non-B hepatitis was anicteric. In the control group an icteric course was recorded twice as frequently (37.5%). The authors compared also the means of maximal values of biochemical examinations. Attention was drawn to the fact that among patients in the chronic dialyzation programme there was not a single case of viral hepatitis A.

Hepatitis C↗
PubMed1990

[Clinical problems in non-A, non-B viral hepatitis. II. Clinical picture of non-A, non-B viral hepatitis in the acute stage].

Comparison of large groups of patients with acute viral hepatitis A (HA), B (HB) and non-A, non-B (HNANB) revealed that the highest percentage of anicteric forms is found in HA (44.8%) followed by HNANB (27.3%) and the lowest percentage in HB (23.6%). Investigation of mean values of biochemical functional liver tests showed that 1. the highest mean values of bilirubinaemia, ALT and AST were recorded in HB. The differences are statistically significantly higher (p less than 0.01) than in the two remaining types. 2. The difference between the cholesterol serum level, GMT and ALP in HB and HNANB on the one hand and HA on the other hand was at the same level of significance. 3. The transaminase activity is only slightly higher in HA than in HNANB, the differences are not significant (p greater than 0.05). 4. The cholestatic features are more marked in HNANB than in HA. The differences are also significant (p less than 0.01). In the clinical picture in acute HNANB symptoms of influenza predominated (53.33%), followed by digestive complaints (47.5%) and the percentage of articular complaints was lowest (24.17%). Analysis of 24 cases of fulminant forms of viral hepatitis revealed that this course was most frequent in HB (50%), followed by HNANB (41.7%) and least frequent in HA (8.3%).

Acute Disease↗
PubMed1990

[Clinical problems in non-A, non-B viral hepatitis. III. The course of non-A, non-B viral hepatitis in the chronic stages].

Investigation of a group of 231 patients with viral hepatitis non-A, non-B (HNANB) revealed that the majority of cases is of the parenteral type (60.17%) and the remainder was without parenteral procedures. The course of HNANB was icteric in the majority (72.55%). On check-up examination one year after the onset of the acute stage the pathological clinical and laboratory finding, i.e. chronic liver disease still persisted in 31.6%. A follow-up of the patients in the course of six years revealed that the ratio of serious sequelae (chronic active hepatitis and cirrhosis of the liver) is significant and increases with time and thus already after two years these serious diagnoses predominate over the number of patients with chronic persistent hepatitis. The chi2 test revealed that there is no sexual difference as regards the development of the chronic stage of HNANB, that the chronic stage develops in both basic types of HNANB (in the parenteral and the epidemic type) but it is significantly more frequent in the parenteral type. The development of the chronic stage is equally frequent after icteric and anicteric forms. In patients who recovered completely within one year (68.39%) the convalescence was protracted and normalization of the clinical and biochemical finding occurred later than in patients with viral hepatitis A and B, hospitalized during the same period.

Chronic Disease↗
PubMed1990

[Clinical problems in non-A, non-B viral hepatitis. I. Diagnosis of non-A, non-B viral hepatitis and its role in the occurrence of acute viral hepatitis in the Czechoslovak population].

Using RIA and ELISA methods the authors examined HBsAg, anti-HBc IgM and anti-HAV IgM antibodies in 830 adult patients and 101 children with acute viral hepatitis from the catchment area of the South Moravian region. In these groups also the most frequent hepatotropic infectious agent as the possible cause of hepatitis was examined. It was revealed that in adults viral hepatitis A accounted for 22%, viral hepatitis B for 48.5%, viral hepatitis non-A, non-B for 28.8% of the group. The percentage distribution of viral hepatitis in children is different: hepatitis A predominates (65%), hepatitis B is less frequent (22%) and viral hepatitis non-A, non-B is least frequent (13%). It was demonstrated that viral hepatitis non-A, non-B is under our conditions a very frequent disease, it accounts for one quarter of all cases of viral hepatitis and if we take into account that non-A, non-B hepatitis has frequently permanent serious sequelae, then proper attention must be paid to this disease. The authors demonstrate that differentiation of types of viral hepatitis by routine methods is possible which leads to a substantially more accurate differentiation of hepatitis.

Acute Disease↗
PubMed1986

Water-borne Mycobacterium xenopi--a possible cause of pulmonary mycobacteriosis in man.

In the years 1980-1983 M. xenopi was isolated from the sputum of 37 persons, 30 of them living in the agglomeration of the regional town in the region of Northern Bohemia with 1,175,000 inhabitants. Only 7 of these 30 had manifestation of pulmonary disease. M. xenopi was found repeatedly in the sputum in 5 patients out of 7 affected and in 2 out of 23 persons who showed no signs of a disease. The prevalence was in males between the age of 52-67 years. All of them suffered from other diseases, as chronic bronchitis, TB healed after lobectomy, lung cancer, fibrotic lung lesions, diabetes mellitus, gastric ulcer healed by resection, chronic alcoholism. Investigations were made for detection of the source of infection. Bacteriological examinations of cold and warm tap water in flats of 9 persons with M. xenopi in their sputa were carried out, as well as cold and warm tap water from flats of 2 healthy persons. M. xenopi was found in tap water of 5 persons with M. xenopi in their sputum and in one of the two healthy persons. In the water of one household we found M. kansasii. We came to the conclusion, that transmission carried out in susceptible persons is most probably due to aerosol during washing and showering with water, containing these mycobacteria.

Aged↗
PubMed1984

[Tuberculosis following mycobacteriosis. Apropos of 2 cases].

Case reports on two men are presented, one suffering from a super-infection of Mycobacterium tuberculosis, the other from Mycobacterium avium after recurrent mycobacterial infections. Both patients have died; one 15 years after first suffering from a M. kansasii infection (decompensated cor pulmonale) and the other 13 years after a M. avium infection (superinfection due to M. bovis). Both patients had chemotherapy followed by a pulmonary excision. The authors suggest protecting patients suffering from mycobacterial infections in order to avoid contamination by obligatory pathogenic mycobacteria, particularly during the period following cure. Indeed during this period the chemo-prophylactic action of the anti-tuberculous drugs given cannot play a part.

Humans↗
PubMed1983

Phosphate transport system in paracoccus denitrificans.

Pi uptake in cells or spheroplasts of Paracoccus denitrificans is biphasic; only the first rapid phase represents net Pi transport. The second phase is limited by the rate of Pi utilization inside the cell, i.e., mainly by its esterification, and as such it was inhibited by DCCD. The Pi/dicarboxylate antiporter does not seem to be operative, and its inhibitor n-butylmalonate did not exert specific inhibition. Pi transport is inhibited by SH reagents; the most potent inhibitor is PCMB, and mersalyl is much less effective. However, neither inhibitor affects efflux of accumulated Pi. The gradient of potassium ions may be involved in the Pi uptake, which is lowered in the presence of valinomycin. FCCP alone does not release accumulated Pi from spheroplasts unless they are preincubated with SCN-. The results indicate that Pi enters the cell by symport with protons.

Biological Transport↗