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Biomedical subjects

J Karczewski

Publications and source records attributed to J Karczewski.

At least 19 recordsLinked to original sources
PubMed2001

Discovery and initial structure-activity relationships of trisubstituted ureas as thrombin receptor (PAR-1) antagonists.

Thrombin is the most potent agonist of platelet activation, and its effects are predominantly mediated by platelet thrombin receptors. Therefore, antagonists of the thrombin receptor have potential utility for the treatment of thrombotic disorders. Screening of combinatorial libraries revealed 2 to be a potent antagonist of the thrombin receptor. Modifications of this structure produced 11k, which inhibits thrombin receptor stimulated secretion and aggregation of platelets.

Platelet Activation↗
PubMed2001

N-heterocyclic derivatives of 2,4-dihydroxybenzcarbothioamide as antimycotic agents.

N-heterocyclic derivatives of 2,4-dihydroxybenzcarbothioamide were synthesized from sulfinylbis(2,4-dihydroxybenzenethioyl) and commercially available heterocyclic amines. The composition and chemical structures were confirmed by IR, (1)H NMR, EI-MS, and elemental analysis. For the estimation of potential activity in vitro the MIC values against 15 strains of dermatophytes, yeasts, and molds were determined. The strongest fungistatic potency was found for N-5'-(3'-oxobenzfurylidyne)-2,4-dihydroxybenzcarbothioamide in relation to all tested dermatophyte strains with MIC = 0.48-0.98 microg/mL. On the basis of the spectroscopic data the influence of N-heterocyclic substitution on antimycotic activity is discussed.

Antifungal Agents↗
PubMed2001

[Evaluation of protein, fat and carbohydrate contents in daily dietary allowance of overweight and obese students from the Medical Academy in Białystok].

The major causes of primary obesity include dietary errors (e.g. high-fat, high-energy diets) and low physical activity. Therefore, the aim of the present study was the quantitative evaluation of daily dietary allowances of students with overweight and obesity in the Medical Academy of Białystok. Questionnaire investigations were conducted in the years 1997-1999 and included 1050 students (701 women and 349 men). Basing on BMI overweight was revealed in 22 women (3.14%) and 82 men (23.5%). Obesity was found in only 2 women (0.3%) and 4 men (1.2%). The 24-hour dietary history of the preceding day was the method used for quantitative analysis. Low physical activity and low-energy food intake (below the recommended safe norm) were the characteristic features found in the majority of students with overweight or obesity. Their daily dietary allowances showed high protein content (above the safe norm in 75% of women and 87.2% of men) and low content of carbohydrates (below the safe norm in over 70% of those examined). Fat content above the safe norm was found in approximately 55% of men with overweight and obesity, the rest consumed low-fat foods. The incidence of overweight or obesity was higher in young men than women studying in the Medical Academy of Białystok. In some of them, this may be caused by a disturbed proportion in the consumption of the major food components (protein, fat, carbohydrates).

Adult↗
PubMed2000

Molecular physiology and pathophysiology of tight junctions III. Tight junction regulation by intracellular messengers: differences in response within and between epithelia.

Tight junction permeability differs with the type of permeants, their size, and their charge. Selective changes in permeability do occur, and they illustrate the diversity in functional reactions of tight junctions. This suggests that special structures in the tight junctions are involved. More and more structural components of the tight junctions are becoming known. The divergence in behavior of native tissue and filter-grown epithelial monolayers with respect to the effects of intracellular messengers offers the possibility to relate structure and function. In addition to the tools for conventional permeability studies, probes have become available to detect changes in activation of intracellular effector proteins such as the protein kinase C isotypes, and with in situ imaging techniques the way is open for a functional approach in the study of tight junctions.

Animals↗
PubMed2000

[Content of selected bioelements in complete daily food rations of students at the Bialystok Medical Academy].

The aim of the study was to evaluate calcium and iron content in a daily food ration of students of Białystok Medical Academy. The analysis was correlated with the consumption of product groups being the main source of these bioelements in the diet (milk, meat and their products). The study involved 492 students (66% women and 34% men) aged 19-25 years. Quantitative analysis was carried out using the 24-hour recall method. Calcium and iron content in the diet were estimated according to Kunachowicz et al. The results were compared with the standards accepted by the Institute of Food and Nutrition in Warsaw, for people with moderate physical activity. The mean calcium content in the diet of female students was 582.9 mg, while in the diet of male students 802.2 mg. Daily diet calcium content covered 53% and 73% of the safe norm in women and men respectively, the recommended norm being 49% and 67%. Calcium content in a daily food ration of the Białystok Medical Academy students was too low, which was caused by insufficient intake of milk and its products. Mean iron intake in a daily food ration of female students was 10.1 mg/day and of male students 15 mg/day. The difference was statistically significant. Iron supply in men, s diet covered the recommended norm in 100%, while the safe norm in 136.4%. In women iron in diet covered the safe norm in 72.1% and the recommended norm in 56.1%. Differences in iron content in a daily food ration of the students examined are associated with differentiated consumption of meat and its products (high intake was noted in men studying at Białystok Medical Academy).

Adult↗
PubMed1998

Alboaggregins A and B. Structure and interaction with human platelets.

Viper venoms contain a variety of platelet binding proteins including those which bind to platelet GPIb/GPIX. Most of these proteins inhibit von Willebrand factor mediated platelet agglutination. Here we report the primary structures of unique members of this family, alboaggregins A and B, isolated from Trimeresurus albolabris, which have the ability to stimulate platelet agglutination and aggregation. Four chains of alboaggregin A and two chains of alboaggregin B share a high degree of homology and all cysteines in both alboaggregins are conserved. Both alboaggregins caused similar agglutination of fixed platelets. Alboaggregin A induced platelet aggregation and release reaction with EC50 = 10 and 30 nM, respectively, which is 20-fold lower than those for alboaggregin B. These observations suggest that the dimeric structure of alboaggregin B is sufficient to mediate its binding to GPIb and induce agglutination of platelets whereas aggregation and release reaction are significantly enhanced by tetrameric structure of alboaggregin A.

Amino Acid Sequence↗
PubMed1997

The interaction of disagregin with the platelet fibrinogen receptor, glycoprotein IIb-IIIa.

Disagregin, a 6 kDa protein isolated from salivary glands of the tick Ornithodoros Moubata, is a potent and selective inhibitor of fibrinogen dependent platelet aggregation and of the adhesion of platelets to fibrinogen (Karczewski et al. (1994) J. Biol. Chem. 269, 6702-6708). In the current study the interaction of disagregin with purified glycoprotein IIb-IIIa (GPIIb-IIIa) was examined. Biotin-labeled disagregin (b-disagregin) bound to GPIIb-IIIa immobilized on the surface of the ELISA plate. This binding was specific, dependent on divalent cations, and was blocked by the peptides fibrinogen gamma-chain fg gamma (400-411), GPIIb(296-306) and by the RGD-containing peptide, GRGDSP. Disagregin also bound to soluble GPIIb-IIIa as demonstrated in studies using the chemical crosslinker, BS3. This binding was inhibited by the peptides fg gamma (400-411) and GPIIb(296-306). In contrast to the results in the solid phase, peptide GRGDSP had no effect on the binding of b-disagregin to soluble GPIIb-IIIa. These data demonstrate that disagregin binds to GPIIb-IIIa through a mechanism distinct from that used by RGD-containing disintegrins. Further analysis of the region(s) of disagregin which bind to GPIIb-IIIa should provide useful information for molecular modeling of the fibrinogen binding site on GPIIb-IIIa and for the design of a new class of potent fibrinogen receptor antagonists.

Animals↗
PubMed1996

[Occupational-social influence in the course of cholelithiasis].

The aim of the study was to examine the relationship between the work load, evaluated by the occupational activity, and the incidence of cholelithiasis. In total 372 subjects (169 cholelithiasis patients examined using USG, and 203 controls), hospitalised in 1993 in the Department of Gastroenterology, Regional Hospital, Białystok, completed the questionnaire. Attention was also given to age, sex, permanent residence, education and physical activities after work. A moderate physical effort, both occupational and non-occupational, seemed to reduce the risk of cholelithasis.

Chi-Square Distribution↗
PubMed1995

An inhibitor from the argasid tick Ornithodoros moubata of cell adhesion to collagen.

An inhibitor of the adhesion of human platelets to collagen was identified in soluble extracts of the soft tick Ornithodoros Moubata and purified by four chromatographic steps. The isolated inhibitor, TAI (Tick Adhesion Inhibitor), is a approximately 15-kDa protein that completely blocks the adhesion of platelets to collagen-coated microtiter plates with an IC50 of 8 nM. In the same concentration range it does not inhibit collagen-induced platelet aggregation or platelet adhesion to fibrinogen and has a partial inhibitory effect on platelet adhesion to fibronectin. TAI also blocks the adhesion of human endothelial cells to collagen, thus its inhibitory effect is not limited to platelets. TAI competes for the binding to platelets of a radiolabeled monoclonal antibody against the platelet glycoprotein Ia-IIa integrin complex. Based on its selective activity and small size, TAI is a promising new molecule for exploring cell-collagen interactions.

Animals↗
PubMed1994

Disagregin is a fibrinogen receptor antagonist lacking the Arg-Gly-Asp sequence from the tick, Ornithodoros moubata.

A platelet aggregation inhibitor was identified in the salivary gland of the tick Ornithodoros moubata and isolated by gel filtration and reverse phase high pressure liquid chromatography. The purified inhibitor is a approximately 6-kDa protein, which we have named disagregin. It inhibits ADP-stimulated platelet aggregation in plasma with an IC50 = 104 +/- 17 nM. Disagregin also inhibits platelet aggregation induced by other agonists, including collagen, epinephrine, platelet-activating factor, thrombin, and the thrombin receptor peptide SFLLRNPNDKYEPF. It does not, however, affect platelet shape change induced by these agonists or thrombin-induced dense granule release. Disagregin inhibits platelet aggregation by binding to the platelet fibrinogen receptor. 125I-Disagregin forms a specific complex with both subunits of the fibrinogen receptor, glycoproteins IIb and IIIa, in the presence of a chemical cross-linker. It binds to unstimulated platelets with a Kd = 42.5 +/- 7.5 nM (23,800 +/- 1600 sites/platelet) and to ADP-stimulated platelets with Kd = 39.4 +/- 6.6 nM (24,050 +/- 1500 sites/platelet). Unlabeled disagregin and the snake venom disintegrin echistatin both compete for this binding. Disagregin also completely blocks platelet adhesion to fibrinogen while partially inhibiting platelet adhesion to fibronectin and having little effect on platelet adhesion to collagen. Disagregin had no effect on the adhesion of human umbilical cord vein endothelial cells to fibrinogen or vitronectin. These cells lack the glycoprotein IIb-IIIa complex; therefore, this result is consistent with the ability of disagregin to bind selectively to platelet glycoproteins IIb and IIIa. Sequence analysis of disagregin revealed 60 residues composing a unique protein. Unlike other fibrinogen antagonists it does not contain the Arg-Gly-Asp cell recognition sequence or a conservative substitution, and it has no structural homology with the Arg-Gly-Asp-containing snake venom disintegrins. Thus, disagregin is unique both in structure and function and may serve as a useful tool for the design of therapeutically useful antithrombotic agents.

Adenosine Diphosphate↗
PubMed1992

An inhibitor of collagen-stimulated platelet activation from the salivary glands of the Haementeria officinalis leech. II. Cloning of the cDNA and expression.

Salivary glands of the leech Haementeria officinalis contain a protein, leech antiplatelet protein (LAPP), that specifically blocks collagen-mediated platelet aggregation (Connolly, T. M., Jacobs, J. W., and Condra, C. (1992) J. Biol. Chem. 267, 6893-6898). Degenerate oligonucleotides whose sequences were derived from two short peptides from V8 digests of the native LAPP were used as primers to generate a polymerase chain reaction (PCR) product which contains the cDNA region coding for the sequence between these two peptides. Using this PCR product as a hybridization probe, phage containing cDNA clones were isolated containing the entire deduced amino acid sequence for LAPP. Computer analysis of the amino acid sequence predicts a peptidase cleavage site between a 21-residue pre-peptide and a mature protein of 126 amino acids. A DNA insert to express the predicted mature LAPP protein was generated by PCR amplification using phage-derived cDNA clones as a substrate. This insert encoded a fusion protein with the leader sequence of the yeast alpha mating factor and the mature LAPP cDNA. These PCR products were cloned into the yeast expression vector pKH4 alpha 2. A KEX 2 Lys-Arg endopeptidase cleavage site was placed NH2-terminal to the predicted mature protein. This vector transfected into the yeast Saccharomyces cerevisiae directs expression of a secreted mature protein at levels up to 200 mg of LAPP/liter of culture medium. The recombinant protein was comparable to native LAPP in its electrophoretic mobility, its reactivity with anti-LAPP antisera, and its biological activity including inhibition of collagen-stimulated platelet aggregation and the adhesion of platelets to collagen. Availability of significant quantities of recombinant LAPP opens the way to further biochemical structure/function studies and to studies on the effects of an inhibitor of collagen-stimulated platelet aggregation in vivo.

Amino Acid Sequence↗
PubMed1991

[Magnesium and heavy metals].

Literature data on mutual correlation of magnesium and heavy metals in the body are reviewed. The effects of synergistic and antagonistic type have been found. Metals are divided into two groups: elements with toxic effect (e.g. Pb) and bioelements (e. g. Zn) which serve as an example in the discussion of biological role of magnesium.

Cadmium↗
PubMed1989

The interaction of thrombospondin with platelet glycoprotein GPIIb-IIIa.

The interaction of human platelet thrombospondin (TSP) with human platelet glycoproteins GPIIb-IIIa was studied using a solid-phase binding assay. Polystyrene test tubes were coated with TSP, and 125I-labeled GPIIb-IIIa was added, allowed to bind, and the bound radioactivity was measured. After 90 min, the binding became time independent, and in most experiments, more than 10% of the exogenously added radioactivity was bound to the tube. Analysis of the bound radioactivity by polyacrylamide gel electrophoresis and autoradiography indicated that it was from labeled GPIIb-IIIa. Several lines of evidence indicate that the binding of GPIIb-IIIa to TSP was specific. (a) TSP immobilized on plastic or Sepharose bound 3-10-fold more GPIIb-IIIa than immobilized bovine serum albumin. (b) Addition of unlabeled excess GPIIb-IIIa reversed the binding of 125I-labeled GPIIb-IIIa to immobilized TSP. (c) Addition of EDTA inhibited the binding of GPIIb-IIIa to TSP by more than 90%, whereas addition of 1 mM CaCl2 and 1 mM MgCl2 potentiated the binding by more than 100%. (d) Monoclonal antibodies against TSP and GPIIb-IIIa inhibited the binding by 30-70% as compared with control and polyclonal anti-fibrinogen anti-serum. (e) A plot of GPIIb-IIIa bound versus GPIIb-IIIa added was best described as a rectangular hyperbola by regression analysis with half-saturation at 60 ng/ml GPIIb-IIIa. Similar results were obtained when labeled TSP was added to tubes coated with GPIIb-IIIa. These results show that TSP and GPIIb-IIIa can specifically interact in vitro and suggest that GPIIb-IIIa may function as a platelet TSP receptor during platelet aggregation.

Calcium↗
PubMed1989

The GPIIB-IIIa-like complex may function as a human melanoma cell adhesion receptor for thrombospondin.

The purpose of this study was to determine whether a heterodimeric complex immunologically related to the fibrinogen receptor could function as a thrombospondin (TSP) receptor in TSP-mediated cell-substratum adhesion of human melanoma cells. We found that polyclonal antibodies to the platelet GPIIb-IIIa complex, GPIIIa, and the human vitronectin receptor inhibited TSP-mediated cell adhesion by 63-68%. Immunoprecipitation of detergent extracts of 125I-surface-labeled melanoma cells using either anti-human platelet GPIIb-IIIa or anti-human vitronectin receptor antibody revealed the presence of a single heterodimeric complex, suggesting that both antisera recognize the same integrin receptor, GPIIb-IIIa-like antigen. Adhesion of cells to TSP is likely mediated through a region of the TSP molecule containing the arginine-glycine-aspartic (RGD) peptide sequence, since cell attachment to TSP was inhibited 50-66% in the presence of peptides containing RGD. These results strongly suggest that a GPIIb-IIIa-like/vitronectin receptor can serve as a cell binding site for TSP in mediating cell-substratum adhesion.

Antibodies, Monoclonal↗
PubMed1988

Role of IIb-IIIa-like glycoproteins in cell-substratum adhesion of human melanoma cells.

The platelet fibrinogen receptor, glycoprotein complex IIb-IIIa, was isolated from human platelets by lectin and monoclonal antibody affinity chromatography and a polyclonal antiserum (anti-IIb-IIIa) was generated and used to probe for the presence and function of IIb-IIIa-like molecules in two adherent human cell lines. Both C32 melanoma cells and WI38 fibroblasts expressed a IIb-IIIa-like complex on their surface as indicated by immunoprecipitation of detergent extracts of surface radiolabeled cells. When added to cells plated in medium containing 10% serum, the anti-IIb-IIIa antiserum perturbed the adhesion of C32 melanoma cells, but not of WI38 fibroblasts. In a serum-free system, anti-IIb-IIIa antibodies inhibited attachment and spreading of C32 cells to fibrinogen, vitronectin, and fibronectin adsorbed to glass. Anti-IIb-IIIa had no effect on the attachment and spreading of WI38 cells to the extracellular matrix proteins, however. Thus, the IIb-IIIa-like complex appears to play a predominant role in cell-substratum adhesion of C32 cells, but not WI38 cells, and may result from the fact that, on a protein basis, the C32 melanoma cells express approximately 3 times more complex on their surface than do WI38 fibroblasts. The results suggest that the relative abundance of a particular adhesion receptor on the cell surface may govern its importance to cell-substratum adhesion.

Cell Adhesion↗
PubMed1987

Thrombospondin promotes cell-substratum adhesion.

The physiological role of the platelet-secreted protein thrombospondin (TSP) is poorly understood, although it has been postulated to be involved in platelet aggregation and cellular adhesion. In this report, TSP isolated from human platelets was found to promote, in vitro, the cell-substratum adhesion of a variety of cells, including platelets, melanoma cells, muscle cells, endothelial cells, fibroblasts, and epithelial cells. The adhesion-promoting activity of TSP was species independent, specific, and not due to contamination by fibronectin, vitronectin, laminin, or platelet factor 4. The cell surface receptor for TSP is protein in nature and appears distinct from that for fibronectin.

Animals↗
PubMed1986

Fibronectin potentiates actin polymerization in thrombin-activated platelets.

The effect of fibronectin on the polymerization state of actin was studied. Triton X-100-insoluble cytoskeleton was prepared from thrombin-activated platelets, and the conversion of G-actin into F-actin was monitored by an assay involving DNase I inhibition by G-actin. It was found that fibronectin bound to membrane receptors decreased the level of platelet G-actin. This observation suggests that in the presence of fibronectin a larger amount of F-actin becomes incorporated into the Triton X-100-insoluble cytoskeleton. At the same molar concentration, fibrinogen only slightly increased actin polymerization, whereas bovine serum albumin at a much higher concentration caused a small inhibition of actin immobilization. Our data show that fibronectin, through interaction with the platelet actomyosin fibrillar system, facilitates actin polymerization into the cytoskeleton.

Actins↗