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Z Dobrowolski

Publications and source records attributed to Z Dobrowolski.

At least 19 recordsLinked to original sources
PubMed1993

[Modern methods of early diagnosis and treatment of ectopic-oviduct pregnancy].

Medical documentation of 80 women operated on because of ectopic pregnancy between the years 1991-1992 was analyzed. Methods of early diagnosis and ways of surgical approaches were discussed. Authors of this article give priority to controlling beta sub-unit HCG acc. to Romero, to ultrasonographic vaginal probe examination and to diagnostic laparoscopy. Early surgical intervention increases the chances to maintain woman's fertility. All procedures on women with ectopic--oviduct pregnancy should be sparing, depending on the ward equipment and personnel training and should be performed by the means of operative laparoscopy method.

Adult↗
PubMed1991

Analysis of the regulatory and structural defects of troponin C central helix mutants.

Five deletion mutants of the D/E linker region of the troponin C central helix were tested for conformational and functional differences from wild-type troponin C. The mutants were in the region 87KEDAKGKSEEE97: dEDA, dKG, dKGK, dKEDAKGK, and dSEEE, designed to change the length of the central helix and the orientation of the Ca(2+)-binding domains relative to each other [Dobrowolski, Z., Xu, G.-Q., & Hitchcock-DeGregori, S.E. (1991) J. Biol. Chem. 266, 5703-5710]. Previous work showed that all mutants except dSEEE are partially defective in one part of the Ca2+ switch or the other. All mutants undergo Ca(2+)-dependent conformational changes as detected by changes in electrophoretic mobility, alpha-helix content, and hydrophobic exposure. Deletions of the central helix do not extensively alter the thermal stability of troponin C, as determined by temperature-dependent loss of alpha-helix. There are differences among the mutants that do not correlate with function. All troponin C mutants show Ca(2+)-dependent interaction with troponin I and T in polyacrylamide gels. Troponin I-troponin C interaction was also analyzed by Ca(2+)-dependent increase in the monomer/excimer ratio of tropinin I and relief of inhibition of the actomyosin S1 ATPase. While all mutants retain basic function, dKGK, dKEDAKGK, and dEDA have altered interaction with troponin I in the absence of Ca2+. dSEEE differs in conformation from wild type, but it is normal in functional assays. This conserved region of the D/E linker is not required for interaction with troponin I in the presence or absence of urea.

Amino Acid Sequence↗
PubMed1991

Modified calcium-dependent regulatory function of troponin C central helix mutants.

Mutations have been made in the exposed region of the avian troponin C central helix, the D/E linker, which change its length and the orientation of the Ca2(+)-binding domains relative to each other. The region 87Glu-Asp-Ala-Lys-Gly-Lys-Ser-Glu-Glu-Glu97 has been altered in five deletion (d) mutants: dEDA, dKG, dKGK, dSEEE, and dKEDAKGK. The recombinant troponin Cs were expressed in Escherichia coli, purified, and assayed for function. All mutants retained basic troponin C function. They all bound Ca2+ to the low and high affinity sites, and they all were able to confer Ca2+ sensitivity on the regulated actomyosin ATPase. However, the regulatory function of all mutants except dSEEE was defective in one part of the Ca2+ switch or the other. In certain conditions dKGK and dKEDAKGK failed to inhibit fully whereas dEDA and dKG failed to activate the regulated actomyosin ATPase fully. The following general conclusions have been made. (a) The length of the D/E linker per se (assuming the linker is helical) and the orientation of the two Ca2(+)-binding domains relative to each other are not crucial for regulation. (b) The conserved charge cluster 95Glu-Glu-Glu97, in a region of troponin C known to bind to troponin I and postulated to be required for regulation, appears to be unimportant for function. (c) Deletion of 88Glu-Asp-Ala90 resulted in a troponin C that could not activate the actomyosin (or S1) ATPase over the level of actomyosin alone, thus defining a role for troponin C in this aspect of thin filament regulation. The results have been interpreted in terms of the crystallographic structure of troponin C and related to results with analogous calmodulin mutants.

Amino Acid Sequence↗
PubMed1989

The assembly of the rod portion of brain myosin.

Electron microscopy was used to study the structural arrangement of the rod portion of brain myosin under various experimental conditions. At low ionic strength the rod formed spindle-like filaments with continuous 14 nm periodicity. In the presence of KCNS and a high concentration of CaCl2 brain myosin and its rod precipitated in a form of segments displaying both bipolar and unipolar arrangement characteristic of the myosin filaments. Limited proteolytic digestion of the rod with chymotrypsin generated several fragments of molecular masses in the range of 84 kDa to 30 kDa. The 74 kDa fragment appeared to be the shortest one which preserves the ability to form filaments.

Animals↗
PubMed1988

Comparison of Ca2+-dependent effects of caldesmon-tropomyosin-calmodulin and troponin-tropomyosin complexes on the structure of F-actin in ghost fibers and its interaction with myosin heads.

Comparison of two types of Ca2+-regulated thin filament, reconstructed in ghost fibers by incorporating either caldesmon-gizzard tropomyosin-calmodulin or skeletal muscle troponin-tropomyosin complex, was performed by polarized microphotometry. The changes in actin structure under the influence of these regulatory complexes, as well as those upon the binding of the myosin heads, were followed by measurements of F-actin intrinsic tryptophan fluorescence and the fluorescence of phalloidin-rhodamine complex attached to F-actin. The results show that in the presence of smooth muscle tropomyosin and calmodulin, caldesmon causes Ca2+-dependent alterations of actin conformation and flexibility similar to those induced by skeletal muscle troponin-tropomyosin complex. In both cases, transferring of the fiber from '-Ca2+' to '+Ca2+' solution increases the number of turned-on actin monomers. However, whereas troponin in the absence of Ca2+ potentiates the effect of skeletal muscle tropomyosin, caldesmon-calmodulin complex inhibits the effect of smooth muscle tropomyosin. This difference seems to be due to the qualitatively different alterations in the structure and flexibility of F-actin in ghost fibers evoked by smooth and skeletal muscle tropomyosins. Troponin can bind to F-actin-smooth muscle tropomyosin-caldesmon complex and, in the presence of Ca2+, release the restraint by caldesmon for S-1-induced alterations of conformation, and reduce that for flexibility of actin in ghost fibers. This effect seems to be related to the abolishment by troponin of the potentiating effect of tropomyosin on caldesmon-induced inhibition of actomyosin ATPase activity.

Actins↗
PubMed1988

Sex differences in regulation of contact sensitivity reaction in mice. 1. Influence of sex on the generation of contrasuppressor and afferent suppressor cells.

It is well known that humoral and cell-mediated immune responses are better in females than in males. Females also develop autoimmunity more easily than males. Contact sensitivity, one of the forms of cell-mediated immunity, is controlled at the afferent and efferent phases by complex interactions of regulatory T cells. Our present experiments indicate that T suppressor afferent (Ts-aff) and T contrasuppressor cells (Tcs) are generated in the mouse in a sex-dependent fashion. These two types of regulatory cells are induced by antigen-antibody complexes containing various immunoglobulin isotypes. Females require fewer antigen (Ag)-IgG1 complexes to produce Tcs cells, but more Tcs cells after antigenic stimulation in females tips the balance toward better immune responsiveness. It remains to be established whether the peculiarities in generation of regulatory cells in female mice are relevant to the pathogenesis of autoimmune diseases which predominantly affect females.

Animals↗
PubMed1988

[Tropomyosin and myosin subfragment 1 induce in thin muscle fiber filaments differing conformational changes in the C-terminal portion of the polypeptide chain of actin].

Muscle fibres, free of myosin, troponin and tropomyosin, containing thin filaments reconstructed from G-actin and modified by fluorescent label 1,5-IAEDANS were used for polarized microfluorimetric studies of the effect of tropomyosin (TM) from smooth muscles, and of subfragment 1 (S1) from skeletal muscles on the structural state of F-actin. TM and S1 were shown to initiate different changes in polarized fluorescence of 1,5-IAEDANS of F-actin: TM increases, whereas S1 decreases fluorescent anisotropy. It was suggested that the structural state of F-actin may differ in the C-terminal of polypeptide chain of actin.

Actin Cytoskeleton↗
PubMed1986

Interaction of tropomyosin with myelin basic protein and its effect on the ATPase activity of actomyosin.

Myelin basic protein (MBP) binds to both skeletal muscle and brain tropomyosin resulting in the formation of paracrystalline tactoids in the absence of divalent cations and at neutral pH. Both types of tropomyosin reduce the inhibition of the ATPase activity of actomyosin caused by MBP. On the other hand, MBP alters the effect of both brain and skeletal muscle tropomyosins on the actomyosin ATPase, even though MBP and tropomyosin bind independently to actin. We conclude that MBP cannot substitute for troponin I in the regulation of the action of tropomyosin on actin.

Actomyosin↗
PubMed1986

Ca2+-calmodulin-dependent polymerization of actin by myelin basic protein.

The interaction between myelin basic protein (MBP) and G-actin was studied under nonpolymerizing conditions, i.e.,2mM HEPES, pH 7.5, 0.1 mM CaCl2 and 0.2 mM ATP. Fluorescence studies using pyrenyl-actin and the measurements of ATP hydrolysis rate show that MBP induces changes in the structure of the actin monomer similar to those occurring during polymerization by salt. Electron microscope observations of the MBP-G-actin complex reveal the presence of filamentous structures which appear as separate filaments or as bundles of filaments in lateral association. These filaments are polar as visualized by attachment of heavy meromyosin. The biochemical data together with electron microscope observations suggest that the binding of MBP to G-actin under non-polymerizing conditions induces an interaction between actin monomers leading to the formation of filamentous structures which may be similar to F-actin filaments. The effects of MBP on G-actin can be reversed by calmodulin in the presence of Ca2+.

Actin Cytoskeleton↗
PubMed1984

1H NMR studies of calmodulin. Resonance assignments by use of tryptic fragments.

Two tryptic fragments of the Ca2+ -binding protein calmodulin have been studied by high-resolution 1H NMR. TR1C (residues 1 - 77) spans the first two domains of the protein and TR2C (residues 78 - 148) spans the second two domains. The spectra indicate that each of the two-domain peptides assumes a conformation which is very close to that in the native protein. This characteristic holds both in the presence and in the absence of Ca2+ ions. Therefore, the resonance assignments obtained for the relatively simpler fragment spectra can be used to assign the spectrum of whole calmodulin. Analysis of the chemical shift patterns and nuclear Overhauser enhancement effects of several assigned resonances indicates that each half of calmodulin can be modelled after the two EF-hand Ca2+-binding proteins for which crystal structures are available, namely parvalbumin and intestinal Ca2+-binding protein.

Animals↗
PubMed1984

Ca2+-calmodulin-dependent regulation of F-actin-myelin basic protein interaction.

Myelin basic proteins (MBP) interacts with F-actin resulting in the precipitation of a complex of both proteins. Electron microscope observations of this complex reveal the presence of ordered bundles of F-actin filaments similar to those obtained from F-actin and troponin I. In addition to the bundles, there also appear short fragments of F-actin filaments. In the presence of Ca2+ calmodulin causes a release of MBP from its complex with F-actin, accompanied by dissociation of F-actin bundles into separate filaments. Parallel to the binding of MBP to F-actin the ATPase activity of actomyosin is progressively reduced. This inhibition is reversed by calmodulin but only in the presence of Ca2+. Studies of the binding of S-1 to F-actin and to the F-actin-MBP complex indicate that the interaction sites for MBP and S-1 on the actin molecule are different.

Actins↗
PubMed1984

Suppression of xenogeneic local graft versus host reaction by rat fetal spleen cells.

Xenogeneic local graft versus host reaction was induced by the injection of 5 X 10(7) adult rat spleen cells under the capsule of cyclophosphamide-treated adult mice. A significant decrease in the reaction, measured by the kidney enlargement index, was obtained by adding to the reacting cells 5-20% of fetal rat spleen cells. Fetal rat thymocytes of fetal mouse splenocytes were not found to be inhibitory. The suppressive activity of rat spleen cells waned completely on day 3 of the postnatal life.

Animals↗
PubMed1982

Long-term results of surgical treatment of post-traumatic posterior urethral strictures by Solovov's method.

The long-term results of surgery for post-traumatic strictures of the posterior urethra by means of surgical invagination are presented. The most frequent complications and their management are discussed. Convalescence was uneventful in 47.76 per cent of the patients. Analysis of particular parameters, such as the width of the urinary stream, ability of retain the urine and urethrographic evaluation, revealed good results in 83.5, 67.15 and 76.11 per cent of the patients, respectively. The method of invagination as modified by Michalowski and Modelski is one of the most efficient for posterior urethral stricture repair.

Adolescent↗
PubMed1980

Familial hypospadias in three generations.

Retroglandular hypospadias has been observed in five males in three generations of the same family. Cytogenetic studies of peripheral blood lymphocytes and buccal smears revealed in all investigated patients normal karyotypes 46,XY with elongation of the long arm of chromosome Y (Yq+).

Child↗