Biomedical subjects

A Jaworski

Publications and source records attributed to A Jaworski.

At least 19 recordsLinked to original sources

PubMed1992

Creatine kinase (CK) and creatine kinase isoenzyme (CK-MB) activity in serum before and after intravenous salbutamol administration of patients with bronchial asthma.

The effect of salbutamol, a selective beta 2-adrenergic agonist, on creatine kinase (CK) and creatine kinase isoenzyme (CK-MB) activity in serum of 20 asthmatic patients was investigated. Venous blood was obtained 30 min, 2 h and 4 h after 0.5 mg salbutamol intravenous injection of 0.5 mg salbutamol. Total creatine kinase activity was assayed on a Technico RA-1000 analyzer with the IFCC recommended method. CK-MB activity was determined using a centrifugal analyzer (Cobas Fera, Roche, Switzerland). Reagent kits were provided by Boehringer Mannheim (FRG). We observed no increase of CK-activity after salbutamol, and found a statistically significant increase of CK-MB activity. Serum CK-MB activity before treatment was 13 +/- 10/IU/l after 30 minutes drug, 31.8 +/- 19 IU/l after 2 h 27.2 +/- 17.79 and after 4 h 22.6 +/- 12 IU/l. We conclude that salbutamol exerts a cardiotoxic effect.

Adult↗

PubMed1991

Topoisomerase mutants and physiological conditions control supercoiling and Z-DNA formation in vivo.

The influence of topoisomerase I and gyrase mutations in Escherichia coli on the supercoiled density of recombinant plasmids and the stability of left-handed Z-DNA was investigated. The formation of Z-DNA in vivo by dC-dG sequences of different lengths was used to determine the effective plasmid supercoil densities in the mutant strains. The presence of Z-DNA in the cells was detected by linking number and EcoRI methylase inhibition assays. A change in the unrestrained superhelical tension in vivo directly effects the B- to Z-DNA transition. Alterations in the internal or external environment of the cells, such as the inactivation of gyrase or topoisomerase I, a gyrase temperature-sensitive mutant, or starvation of cells, have a dramatic influence on the topology of plasmids. Also, E. coli has significantly more superhelical strain than Klebsiella, Morganella, or Enterobacter. These studies indicate that linking deficiency and effective supercoil density are mutually independent variables of plasmid tertiary structure. A variety of factors, such as protein-DNA interactions, activity of topoisomerases, and the resulting supercoil density, contribute to the B to Z transition inside living cells.

DNA Topoisomerases, Type I↗

PubMed1991

Cell-free and cell-bound hemolytic activities of Proteus penneri determined by different Hly determinants.

A collection of 45 Proteus penneri strains was characterized with respect to their hemolytic activity and representative cell-free or only cell-bound hemolysin possessing strains were chosen for further study. Extracellular Proteus penneri hemolysin, which was investigated earlier by hybridization, reacted with monospecific antiserum against alpha-hemolysin of Escherichia coli. In this paper we also show, using the colony hybridization technique, that the alpha-hemolysin-like determinant is widely distributed among Proteus penneri strains. Because one of the strains tested, which expressed a high activity of cell-bound hemolytic factor, did not carry such a Hly determinant, the presence of a second hemolysin is postulated. We cannot demonstrate any difference in hybridization patterns of alpha- and beta-hemolytic Proteus penneri strains and accumulation of the toxin molecule inside the cells was also not observed. The existence of another control mechanism, external to the hly operon, for hemolysin gene is suggested.

Blotting, Southern↗

PubMed1990

Cytosine methylation enhances Z-DNA formation in vivo.

The influence of cytosine methylation on the supercoil-stabilized B-Z equilibrium in Escherichia coli was analyzed by two independent assays. Both the M.EcoRI inhibition assay and the linking-number assay have been used previously to establish that dC-dG segments of sufficient lengths can exist as left-handed helices in vivo. A series of dC-dG plasmid inserts with Z-form potential, ranging in length from 14 to 74 base pairs, was investigated. Complete methylation of cytosine at all HhaI sites, including the inserts, was obtained by coexpression of the HhaI methyltransferase (M.HhaI) in cells also carrying a dC-dG-containing plasmid. Both assays showed that for all lengths of dC-dG inserts, the relative amounts of B and Z helices were shifted to more Z-DNA in the presence of M.HhaI than in the absence of M.HhaI. These results indicate that cytosine methylation enhances the formation of Z-DNA helices at the superhelix density present in E. coli. The B-Z equilibrium, in combination with site-specific base methylation, may constitute a concerted mechanism for the modulation of DNA topology and DNA-protein interactions.

Chloramphenicol↗

PubMed1989

Tetracycline promoter mutations decrease non-B DNA structural transitions, negative linking differences and deletions in recombinant plasmids in Escherichia coli.

The ability to clone a variety of sequences with varying capabilities of adopting non-B structures (left-handed Z-DNA, cruciforms or triplexes) into three loci of pBR322 was investigated. In general, the inserts were stable (non-deleted) in the EcoRI site (an untranslated region) of pBR322. However, sequences most likely to adopt left-handed Z-DNA or triplexes in vivo suffered deletions when cloned into the BamHI site, which is located in the tetracycline resistance structural gene (tet). Conversely, when the promoter for the tet gene was altered by filling-in the unique HindIII or ClaI sites, the inserts in the BamHI site were not deleted. Concomitantly, the negative linking differences of the plasmids were reduced. Also, inserts with a high potential to adopt Z-DNA conformations were substantially deleted in the PvuII site of pBR322 (near the replication origin and the copy number control region), but were less deleted if the tet promoter was insertion-mutated. The deletion phenomena are due to the capacity of these sequences to adopt left-handed Z-DNA or triplexes in vivo since shorter inserts, less prone to form non-B DNA structures, or random sequences, did not exhibit this behavior. Sequences with the potential to adopt cruciforms were stable in all sites under all conditions. These results reveal a complex interrelationship between insert deletions (apparently the result of genetic recombination), negative supercoiling, and the formation of non-B DNA structures in living Escherichia coli cells.

Chromosome Deletion↗

PubMed1988

In vivo existence of left-handed DNA.

A genetic-biochemical assay has been developed to investigate the in vivo existence and consequences of unusual DNA structures. Left-handed DNA was shown to exist in living Escherichia coli. The EcoRI methyltransferase gene (temperature-sensitive) was cloned to serve as a probe for perturbed GAATTC sites in vivo. This plasmid was cotransformed with different plasmids containing inserts that had varying capacities to form left-handed helices or cruciforms with a target EcoRI site in the center or at the ends of the inserts. Inhibition of methylation in vivo was found for the stable inserts with the longest left-handed helices. In vitro methylation with the purified M.EcoRI enzyme agreed with the in vivo results.

Bacterial Proteins↗

PubMed1988

Boerhaave's syndrome. Computed tomographic findings and diagnostic considerations.

Boerhaave's syndrome, or spontaneous rupture of the esophagus, may present with atypical chest pain mimicking an acute thoracic aortic dissection. We describe such a case and discuss the utility of a thoracic computed tomographic scan in arriving at a prompt diagnosis. The importance of early diagnosis is reviewed with particular attention to these roentgenographic findings.

Aortic Dissection↗

PubMed1988

The B- to Z-DNA equilibrium in vivo is perturbed by biological processes.

Right-handed B and left-handed Z conformations coexist in equilibrium in portions of plasmids in Escherichia coli. The equilibria are influenced by the length of the sequences that undergo the structural transitions and are perturbed by biological processes. The composite results of three types of determinations indicate a supercoil density of -0.025 in vivo. The coexistence of alternative DNA conformations in living cells implies the potential of these structures or their transitions for important functions in genetic regulatory processes.

DNA↗

PubMed1988

Utility of immediate postlobectomy fiberoptic bronchoscopy in preventing atelectasis.

In a prospective randomized trial, we examined the value of routine postlobectomy fiberoptic bronchoscopy (FOB) in preventing postoperative atelectasis. Twenty patients who underwent lobectomy were randomly assigned to either chest physical therapy alone (group 1) or immediate bronchoscopy (group 2). Both group 1 and group 2 were placed on a standard physical therapy regimen consisting of aerosol bronchodilator therapy, chest percussion, and incentive spirometry. It was concluded that routine postlobectomy bronchoscopy offers no advantage over the usual physical therapy measures in preventing the development of postoperative atelectasis.

Administration, Inhalation↗

PubMed1987

Left-handed DNA in vivo.

Left-handed DNA is shown to exist and elicit a biological response in Escherichia coli. A plasmid encoding the gene for a temperature-sensitive Eco RI methylase (MEco RI) was cotransformed with different plasmids containing inserts that had varying capacities to form left-handed helices or cruciforms with a target Eco RI site in the center or at the ends of the inserts. Inhibition of methylation in vivo was found for the stable inserts with the longest left-handed (presumably Z) helices. In vitro methylation with the purified MEco RI agreed with the results in vivo. Supercoil-induced changes in the structure of the primary helix in vitro provided confirmation that left-handed helices were responsible for this behavior. The presence in vivo of left-handed inserts elicits specific deletions and plasmid incompatibilities in certain instances.

Cloning, Molecular↗

PubMed1979