Search PubMed⌕ Search

Biomedical subjects

M Zalewski

Publications and source records attributed to M Zalewski.

At least 19 recordsLinked to original sources

Induction of glutathione S-transferase and glutathione by toxic compounds and elicitors in reed canary grass.

Treatment of read canary grass leaves with phenol, 4-chlorophenol, naphthalic anhydride and phenylethylisothiocyanate increased glutathione S-transferase activity by 1.4-2.4-fold (control 17 U g(-1) DW). Benzothiadiazole, beta-aminobutyric acid and salicylic acid increased activity by 1.3-1.8-fold. Total glutathione pool was increased by the toxic compounds by 1.2-2-fold and by the elicitors 1.4-1.6-fold (control 593 nmol g(-1) DW). Unlike the other compounds, benzothiadiazole and salicylic acid did not decrease the redox state. Benzothiadiazole acted synergistically with chlorophenol on glutathione S-transferase and glutathione levels and counteracted the decrease in redox state caused by the xenobiotic. Reed canary grass thus has a strong potential to neutralize toxic compounds, which may be further enhanced by elicitors.

Aminobutyrates↗

The influence of caesium-137 distribution in Poland's north-eastern ecosystem on effective dose 10 years after the Chernobyl disaster.

A comparison is presented of particular methods of exposure in the first year after the Chernobyl disaster and ten years later. This comparison shows that the population exposure due to the presence of radiocaesium in the environment results from the presence of caesium contained in the soil, which provides 68% of the dose (as compared to 32% in 1987) while the influence of diet has been reduced to 32% (from 68%). The exposure from caesium-137 contained in the air has dropped from 14% to 0. The effective dose from caesium has been 50 times smaller than that from environmental sources of the natural radiation estimated for the region under study to be 1.61 mSv x y(-1).

Accidents↗

Apoptotic effect of cyanobacterial extract on rat hepatocytes and human lymphocytes.

Toxic cyanobacterial blooms are an increasing problem in Poland. The production of cyanobacterial toxins and their presence in drinking and recreational waters represent a growing danger to human and animal health. This is connected with the increase of cyanobacterial biomass caused by excessive eutrophication of the water ecosystem. There is evidence that cyanobacterial hepatotoxins can act as a potent promoter of primary liver cancer. The apoptotic effect of microcystins in Polish cyanobacterial bloom samples on rat hepatocytes and human lymphocytes was observed using light and fluorescence microscopy, flow cytometry, and electrophoretic analysis. The incubation time needed to observe the first morphological apoptotic changes in hepatocytes was approximately 30 min; however, the characteristic biochemical changes in DNA were not observed even after 120 min. In lymphocyte cultures the morphological changes characteristic for apoptosis were observed after 24 h of incubation and a 48-h incubation was found to be optimal for analysis of internucleosomal DNA fragmentation, which is one of the main biochemical hallmarks of programmed cell death. These cells are an easily isolated and inexpensive material for medical diagnostics. Therefore the apoptotic changes, together with the clastogenic effect seen in lymphocyte cultures, are proposed as a future analytical method for these toxins.

Animals↗

Tests for the toxicity assessment of cyanobacterial bloom samples.

Cyanobacterial (blue-green algal) blooms are one of the common consequences of the increasing eutrophication of surface waters. The production of cyanobacterial toxins and their presence in drinking and recreational waters represents a growing danger to human and animal health. Due to a lack of toxin standards and to resource limitations on the wide-scale use of analytical methods (e.g., high-performance liquid chromatography, enzyme-linked immunosorbent assay (ELISA)) in cyanobacterial toxin monitoring, it is necessary to assess and to develop additional methods for their detection and estimation. Microbiotests using invertebrates offer a possible approach for the inexpensive and straightforward detection and assessment of cyanobacterial bloom toxicity. Three microbiotests with: Thamnocephalus platyurus, Daphnia magna, and Spirostomum ambiguum were examined with bloom samples containing hepatotoxic microcystin-LR and up to five additional microcystin variants. Two kinds of cyanobacterial bloom sample preparations were tested: crude extracts (CE) and purified extracts (PE). The highest toxicity was found when CE was used for microbiotests. The sensitivity of microorganisms decreased from S. ambiguum to T. platyurus and to D. magna. A statistically significant correlation was found between microcystin concentration and T. platyurus biotest, and between mouse bioassay and S. ambiguum results. Addition of Me2SO (1%, v/v) is a possible method to increase the sensitivity of the microorganisms for microcystin-LR.

Animals↗

Study of 222Rn concentrations in drinking water in the north-eastern hydroregions of Poland.

This paper presents the results of radon concentration measurements in the drinking water from the municipal water supply system and private wells located in the north-eastern part of Poland. The measurements were carried out on 643 samples using a liquid scintillation method. The mean value was found to be 5262 Bq m-3 with a maximum of 38347 Bq m-3. The samples were obtained from different water-bearing levels, i.e. surface water, deep borehole water and well water and have respective mean values of 3398, 5178 and 6155 Bq m-3. In 57 water samples, a guideline maximum level of 11,000 Bq m-3 was found to be exceeded. The observed radon concentration in water can contribute to a 2% increase in indoor radon concentration.

Air Pollution, Indoor↗

Indoor radon concentrations in Poland as determined in short-term (two-day) measurements.

The aim of the present work was to obtain a pattern of 222Rn concentration distributions in typical buildings in Poland. In the investigations, the environmental passive detectors of the PICO-RAD type were used. The study encompassed buildings that were typical for Poland. The distribution of airborne 222Rn concentrations indoors is of a log-normal type. A total 1171 detectors were measured. Measurements were made in 319 basements, the remaining 852 measurements were carried out in the inhabited part of the houses. The radon concentrations in the basements in Bq x m(-3) ranged from 6 to 1300 with the arithmetic mean AM = 60, geometric mean GM = 30 and median M = 28, whereas those in the inhabited parts of the house (above the ground level) were: AM = 25, GM = 17 and M = 16 with the highest record value of 420.

Air Pollutants, Radioactive↗

Apoptotic effect of cyanobacterial blooms collected from Polish water reservoirs.

Recently in many countries, including Poland, the problem of toxicity of cyanobacterial blooms has been of great importance. In many cases it is connected with the increase of microcystins (MCYSTs) concentration in fresh water. This problem is caused by excessive eutrophication of drinking and recreational water bodies. In humans, the most frequent symptoms of the MCYST effect are: cutaneous rash, fever, vomiting, diarrhoea, gastroenteritis and acute damage of the liver. The aim of this work was to estimate apoptotic effects of five different cyanobacterial hepatotoxic extracts containing MC-LR and other variants of MCYSTs (MC-RR, MC-YR, and MC-WR). These effects were analysed in rat hepatocytes--primary target of cyanobacterial hepatotoxins. Morphological changes in hepatocytes were examined by means of fluorescence and differential interference contrast microscopy with the DNA-specific dye, Hoechst 33342. The hepatocytes were treated with each cyanobacterial extracts containing MC-LR in the range between 100 nM-2000 nM for 30 min, 60 min and 120 min. The first characteristic apoptotic changes: shrinking and budding of cells were seen after 30 min, MC-LR = 100 nM. During the next 30 min the percentage of apoptotic cells increased by over 50%, MC-LR at concentrations ranging from 100 to 250 nM (the value dependent on a bloom sample). Highly condensed chromatin and apoptotic bodies were observed in 85-90% of hepatocytes after 120 min of treatment with MC-LR in concentration of 1000 nM. The apoptotic changes in rat hepatocytes confirm the high cytotoxic potential of cyanobacterial bloom samples collected during different months and years from reservoirs of drinking and recreational water in central Poland.

Apoptosis↗

[The measurement of radon in kindergarten and infant nursery buildings in East-North Poland].

The measurements of radon concentration in 58 buildings of day nursery schools and kindergartens were performed in the six province of the East North Poland. The measurements of indoor radon were performed by means of a charcoal canister (Pico-Rad). The concentration ranged from 4.5 to 320 Bq/m3 and have arthimetic average 24.5 Bq/m3, geometric average 15.7 Bq/m3, median 15 Bq/m3. The highest average values were observed in Suwałki Province and Olsztyn Province. The results of all these measurements do not exceeded the limit of the Polish law.

Child Day Care Centers↗

Comparison of the deployment and healing of thin-walled expanded PTFE stented grafts and covered stents.

This study evaluated the deployment and short-term healing of thin-walled expanded polytetrafluoroethylene (ePTFE) stented grafts and covered stents as endoluminal prostheses in normal canine aortas and in an abdominal aortic aneurysm (AAA) model. Stented grafts consisted of a 7 cm length of 3 mm internal diameter ePTFE graft (Impra, Inc., Tempe, Ariz.) with two P-188 Palmaz stents (Johnson & Johnson Interventional Systems, Warren, N.J.) deployed along the inner surface of the ends of the graft to secure the prosthesis to the arterial wall. Covered stents were fabricated by placing a 3.7 cm length of 3 mm internal diameter thin-walled ePTFE graft over a P-394 Palmaz stent. Four covered stents and four stented graft prostheses (two of each prototype in the normal canine aorta and AAA model) were implanted in eight animals. One prosthesis of each type in each model was removed at 30 days and one at 60 days. Prior to removal, prostheses were evaluated by CT scan, arteriography, and intravascular ultrasound imaging with values compared to those obtained when the prostheses were deployed. Gross inspection and microscopic evaluation were performed at scheduled explantation. In general, the stented grafts were more difficult to accurately deploy. Healing and maintenance of long-term patency without significant luminal obstruction or occlusion occurred in only one 30-day sample in a normal canine aorta. The 30-day stented graft specimen that had been implanted in an AAA and required the addition of a covered stent to seal a maldeployment of the distal segment was also patent. The 60-day stented graft in the normal canine aorta was occluded with narrowing of the graft between the stents. The 60-day stented graft in the AAA was patent with one central fold and thrombus occupying approximately 20% to 30% of the lumen at this site. In contrast, the covered stent devices were less difficult to accurately deploy. All of the covered stent devices were patent with well-incorporated surfaces. Deployment of covered stents was more accurate and less complicated compared to stented grafts. All patent endoluminal prostheses and stent surfaces were well incorporated into aortic tissues. Problems with graft narrowing, folding, and subsequent thrombosis occurred in the unstented segments of the stented grafts. These preliminary findings support the further development and use of completely supported (stented) devices as endoluminal prostheses.

Angioplasty, Balloon↗

Evaluation of a modular endovascular bifurcation prosthesis in a canine aortic aneurysm model.

PURPOSE: The study evaluated the deployment and healing of a novel self-expanding modular bifurcation endovascular prosthesis in a canine abdominal aortic aneurysm model. The endoluminal prosthesis consists of self-expanding nitinol stents lined by a synthetic prosthesis. One component of the device is a bifurcated body with a 12- to 14-mm diameter aortic segment and an integral 7- to 8-mm diameter iliac limb. The bifurcated body also has a stent-reinforced opening (pant-leg) for subsequent insertion of a contralateral 7- to 8-mm diameter iliac limb component. METHODS: Seventeen bifurcated prosthesis were placed; 7 were inserted through the left common carotid artery and 10 from the femoral arteries. With either route of access the 16F or 17F aortoiliac limb and the 13F iliac limb delivery catheters enabled easy passage and secure positioning of the bifurcated prostheses. Predeployment and postdeployment inspection of the dimensions and continuity of the aortoiliac prosthetic components were evaluated by cinefluoroscopy and intravascular ultrasonography (IVUS). RESULTS: After deployment was done, interval patency was assessed with angiography, IVUS, and contrast-enhanced computed tomography with the prostheses removed for analysis at 1 week (n = 4), 1 month (n = 3), 3 months (n = 4), and 6 months (n = 6). Five of the first seven implanted prostheses had occlusion of segments of the device. In two dogs the bifurcated body and both legs were occluded. In the other three the nonoccluded leg and bifurcation body were fully patent. In the first seven animals IVUS at implantation showed compression of an iliac leg by the orifice of the contralateral iliac component. After concentric fixation of the flow divider was performed, only one additional iliac limb occlusion occurred in the next 10 animals. Cinefluoroscopy, computed tomography, IVUS imaging, and histologic analysis of retrieved specimens demonstrated healing of the aortoiliac prostheses without evidence of perigraft leaks. CONCLUSIONS: This feasibility study demonstrates the ability to deploy and maintain acceptable patency of a self-expanding endoluminal, modular bifurcation prosthesis in a canine aortic model. Clinical evaluation of the device is planned for the near future.

Alloys↗

Preliminary clinical outcome and imaging criterion for endovascular prosthesis development in high-risk patients who have aortoiliac and traumatic arterial lesions.

PURPOSE: This report reviews our preliminary experience of prospective treatment of arterial lesions with endoluminal grafts in a Food and Drug Administration (FDA)-approved, investigator-sponsored Investigation Device Exemptions study. The utility and accuracy of various imaging methods, including angiography, cinefluoroscopy, computed tomography (CT), intravascular ultrasonography (IVUS), and duplex scanning, in performing the procedures was also assessed. METHODS: Thirty-one patients were evaluated; 17 patients were treated, including 11 with abdominal aortic aneurysms, one with an aortic occlusive lesion, two with iliac artery aneurysms, and three with traumatic arteriovenous fistulas. Twelve of the 14 patients who had aorta and iliac artery lesions were high-risk. The mean follow-up of patients treated was 9 months (range, 6 to 15 months). RESULTS: Aortoaortic endoluminal interposition procedures were not successful for treating abdominal aortic aneurysms early in the study (n = 3). Aortoiliac endoluminal bypass, contralateral iliac artery occlusion, and femorofemoral bypass procedures were successful in seven of eight subsequent cases (88%), with no incidence of endoleaks at either the proximal or distal fixation sites using the deployment methods described in this report. The 30-day operative mortality rate on follow-up evaluations for patients who underwent aortoiliac procedures was 14% (two of 14). Other major complications included transient renal failure in three patients that required short-term (two to eight times) dialysis, one arterial perforation and one dissection, and one prolonged intubation. No myocardial infarctions or strokes occurred. After major complications or identification of limitations in the study, the protocol was modified with the approval of the FDA to help avoid the recurrence of the same problems. There were no deaths or complications in the trauma cases. CONCLUSIONS: Contrast-enhanced CT (axial images and spiral reconstructions) was the most accurate method to determine candidacy for aortoiliac procedures and to choose the site for deployment of the devices. Angiographic scans were misleading in several patients regarding the critical determinants of patient candidacy and device deployment, particularly regarding the presence of a distal aortic neck. Cinefluoroscopy was used in all patient and was particularly useful for determining the continuity of vascular structures and the anatomy of branch arteries and for enabling precise positioning of stent devices. Determination of fixation sites and assessing dimensional information by cinefluoroscopy and angiography were limited by inaccuracies produced by image magnification, parallax, and uniplanar views. IVUS was used to determine the morphologic features of vascular structures (i.e., calcium, thrombus), to perform real-time observation of the expansion of devices, and to assure firm fixation of balloon-expanded stents before the procedures were completed. Duplex scanning was very helpful in assessing and identifying precisely the location of arteriovenous fistulas before intervention and provided assessment at follow-up intervals. Three-dimensional reconstruction imaging technologies such as spiral CT were particularly helpful for assessing the morphologic features of vascular anatomy before the intervention and at follow-up intervals, whereas 3-D IVUS provided a similar real-time perspective during the procedure.

Aged↗

[Circadian variation of the unstable phase in coronary disease].

To examine a circadian variation of symptom onset of acute myocardial infarction and unstable angina two years register of possible all acute coronary events in a population of Podhale was performed. The time of onset of acute coronary events was determined on the basis of patient self-report. One criterion for exclusion in the study was inability to establish reliable time of onset of acute symptoms. The study group comprised 366 patients aged 61 years, range 29-89 years, men 212, mean age 59, women 154, mean age 64. The distribution of symptom onset within 24 time intervals tested for uniformity by a chi-square test for goodness of fit shows significant (p < 0.01) morning peak between 7:00-9:00 A.M. in whole group and in a subgroup of AMI. No significant evening peak (17:00-18:00 P.M.) was also found in subgroup of AMI.

Adult↗

Conformational analysis of the Campylobacter jejuni porin.

The major outer membrane protein (MOMP) of Campylobacter jejuni was purified to homogeneity by selective solubilization and fast protein liquid chromatography. The amino acid composition of the MOMP indicates the presence of cysteine residues. The amino-terminal sequence, determined over 31 residues, shows no significant homology with any other porin from gram-negative bacteria except in a discrete region. Immunocross-reactivity between Escherichia coli OmpC and the MOMP was analyzed, and a common antigenic site between these two porins was identified with an anti-peptide antibody. From circular dichroism and immunological investigations, the existence of a stable folded monomer, containing a high level of beta-sheet secondary structure, is evident. Conformational analyses show the presence of a native trimeric state generated by association of the three folded monomers; the stability of this trimer is reduced compared with that of E. coli porins. This study clearly reveals that the C. jejuni MOMP is related to the family of trimeric bacterial porins.

Amino Acid Sequence↗

Laparoscopic gastrojejunostomy technique: case report.

We present a case report of laparoscopic gastrojejunostomy in a patient with gastric outlet obstruction from unresectable cancer. We performed an intracorporeal gastrojejunostomy in a side-to-side fashion. The patient had no morbidity and minimal hospital stay.

Adenocarcinoma↗

Natural radioactivity of building components and materials used in Białystok province.

The paper presents the results of the measurements of natural radioactivity of building components and materials used in the North-East part of Poland performed by the Department of Biophysics, Medical Academy of Białystok. The natural radioactivity (40K, 224Ra and 232Th) of 133 samples was measured and the qualifying coefficients f1 and f2 were calculated. All measured samples of different materials had radioactivity level below legally accepted value. The lowest values of f1 and f2 were observed in prefabricated building materials; and they were lower then in traditional red brick. Only one sample of furnace slag had increased value of natural radioactivity, which was higher than legally permitted level.

Environmental Exposure↗