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Biomedical subjects

J Hubácek

Publications and source records attributed to J Hubácek.

At least 19 recordsLinked to original sources
PubMed1994

Restriction endonucleases R.EcoKI and R.EcoR124I are probably located in different environments within the bacterial cell.

We describe the phenomenon of a transient state of R124I restriction deficiency after long-term storage of the E. coli[pCP1005] strain at 4 degrees C, or after growth of the culture in synthetic M9 medium with the nonmutagenic solvent dimethyl sulfoxide. The unusual high reversion from the R+ 124 to the R- 124 phenotype was observed only in E. coli strain transformed with the high-copy number plasmid pCP1005 carrying EcoR124I hsdR, M and S genes cloned, but not with strains carrying the natural conjugative plasmid R124. The effect of both treatments on the expression of EcoR124I phenotype in relation to the possible location of R.EcoR124I restriction endonuclease in E. coli is discussed.

Cell Membrane↗
PubMed1994

Genetic markers in hypercholesterolemic and normocholesterolemic Czech children.

The genetic background of polygenic hypercholesterolemia was studied in hypercholesterolemic children consuming a diet identical to control individuals with low cholesterol concentrations. Significantly higher frequencies of "disadvantage" alleles, usually combined with a higher LDL cholesterol, were found in hypercholesterolemic individuals when polymorphisms in apolipoprotein E, apolipoprotein B--XbaI and LDL receptor--PvuII were studied.

Apolipoproteins B↗
PubMed1994

[Cytogenetic findings in patients with primary myelodysplastic syndrome and their prognostic significance. (Analysis of results in 65 patients)].

Cytogenetic examination of 65 patients with primary MDS revealed cytogenetic changes in 39 (60%) of the patients. The most frequently affected chromosomes were chromosomes 5, 7, 11, 17 and 20. Deletion of 5q only found in 9 (23%) of the patients with chromosomal changes occurred similarly as simple chromosomal changes most frequently in the prognostically more favourable group MDS-RA. Prognostically adverse monosomy of chromosome 7 was found in 3 patients in group RAEB and RAEB-t but only as part of complex chromosomal changes. The latter were encountered most frequently in patients of groups RAEB and RAEB-t, similarly as trisomy of chromosome 8. Patients in these groups had also a significantly shorter survival time (RAEB 17.7 and RAEB-t 14.2 months) than patients in group MDS-RA (31.5 months). Evaluation of survival according to Kaplan-Meyer's curve revealed significantly longer survival of patients without cytogenetic changes. Laboratory, cytogenetic and clinical findings in four patients with CMML differed from findings of the remaining patients with MDS. This supports the view that this sub-group is rather a myoproliferative conditions than MDS. Transformation to AL was proved in 19 patients. 14 of them (74%) had a chromosomal change at the time of diagnosis.

Adolescent↗
PubMed1992

Mutation in the specificity polypeptide of the type I restriction endonuclease R.EcoK that affects subunit assembly.

We describe the isolation and characterization of a temperature-sensitive mutation within the hsdS gene of the type I restriction and modification system EcoK. This mutation appears to affect the ability of the HsdR subunit to interact with the HsdS subunit when forming an active endonuclease. We discuss the possibility that this mutant, together with another mutation described previously, may define a discontinuous domain, involved in protein-protein interactions, within the HsdS polypeptide.

Amino Acid Sequence↗
PubMed1992

Biological function of DNA methylation.

Structural and functional properties of prokaryotic DNA methyltransferases are summarized. The different aspects of the role of DNA methylation which influences DNA-protein interaction in restriction and modification of DNA and in mismatch repair, DNA replication and gene expression are discussed.

Bacteria↗
PubMed1991

Characterization of new plasmids from methylotrophic bacteria.

Several tens of methanol-utilizing bacterial strains isolated from soil were screened for the presence of plasmids. From the obligate methylotroph Methylomonas sp. strain R103a plasmid pIH36 (36 kb) was isolated and its restriction map was constructed. In pink-pigmented facultative methylotrophs (PPFM), belonging to the genus Methylobacterium four plasmids were detected: plasmids pIB200 (200 kb) and pIB14 (14 kb) in the strain R15d and plasmids pWU14 (14 kb) and pWU7 (7.8 kb) in the strain M17. Because of the small size and the presence of several unique REN sites (HindIII, EcoRI, NcoI), plasmid pWU7 was chosen for the construction of a vector for cloning in methylotrophs. Cointegrates pKWU7A and pKWU7B were formed between pWU7 and the E. coli plasmid pK19 Kmr, which were checked for conjugative transfer from E. coli into the methylotrophic host.

Anti-Bacterial Agents↗
PubMed1991

Immunomodulatory effects of laser therapy in the treatment of chronic tonsillitis.

The aim of the presented pilot study was to examine possible stimulatory effect of He-Ne laser on the immune system. Eight patients suffering from chronic tonsilitis were within 9 days subjected to three consecutive doses of laser irradiation of tonsils and several immune parameters were determined prior to the treatment, shortly after its cessation and after 4 weeks of follow-up period. Shortly after the cessation of the treatment significant increase of secretory immunoglobulin A in saliva was observed which was followed by increase of IgA serum level after 4 weeks of follow-up. The significant increase of the relative proportion of CD4+ helper T-lymphocytes observed at the end of the follow-up period led to normalization of the CD4/CD8 ratio. As the changes described correlated with clinical improvement in 7 out of 8 patients it could be assumed that beneficial effect of lasertherapy in the treatment of chronic tonsilitis is mediated by modulatory influence on the immune system, especially on protective immunity and immunoregulation.

Adult↗
PubMed1991

Bleeding to the adrenal gland as a terminal manifestation of acute leukaemia.

The authors refer about an unusual localization of haemorrhage to the adrenal glands, observed in two patients with acute leukaemia similar to the picture of Waterhouse-Friderichsen's syndrome. This complication causing serious and dramatic effects should be taken into differential diagnostic consideration. Literature data and own results are given in order to review the general characteristics of bleeding in acute leukaemia.

Acute Disease↗
PubMed1990

A mutation that converts serine340 of the HsdSK polypeptide to phenylalanine and its effects on restriction and modification in Escherichia coli K-12.

A hybrid hsdS gene, encoding the HsdSts + d polypeptide, was constructed by joining the proximal region of the wild-type (wt) hsdS sequence with the distal region of the hsdSts + d sequence, at the hsdS BglII site. The hybrid hsdS-Sts + d gene exerts a trans-dominant effect on restriction and modification, which points to the location of the temperature-sensitive (ts) trans-dominant (+ d) mutation in the gene hsdSts + d distal region. Sequencing of the region downstream from the HindIII target in the Escherichia coli K-12 hsdSts + d mutant was carried out. It is identical to the wt hsdS sequence (GenBank/EMBL accession number ECHSDK LV00288), except for a single base-pair transition C1245----T. The results obtained support the idea that the trans-dominant effect of the ts mutation described earlier is related to the single base-pair transition in the nonhomologous region of the hsdSts + d sequence.

Amino Acid Sequence↗
PubMed1990

An efficient method for isolation of plasmid DNA from methylotrophic bacteria.

A method, suitable for the isolation of closed circular plasmid DNA from methylotrophic bacteria is described. Improvement of cell lysis was achieved by butanol extraction of cells before application of the lytic agent. Using this method, cryptic plasmids of 7.8, 14, 36 and 200 kb were purified from soil-isolated methylotrophs.

DNA, Bacterial↗
PubMed1990

[Practical output of the results of computerized EEG frequency analysis].

For the practical application of EEG frequency analysis it is necessary to ensure an output of results which contains only clinically relevant data. The article describes a new solution where, based on adequate statistical evaluation of parameters of frequency spectra, only important facts are topographically visualized. Marked reduction of data thus makes it possible to concentrate useful information. Contrary to hitheric common "mapping" of electric activity of the brain, it is thus easier to detect pathological changes in the EEG frequency spectra.

Electroencephalography↗
PubMed1989

The location of a temperature-sensitive trans-dominant mutation and its effect on restriction and modification in Escherichia coli K12.

An Escherichia coli K12 chromosomal EcoRI-BamHI fragment containing a mutant hsdS locus was cloned into plasmid pBR322. The mcrB gene, closely linked to hsdS, was used for selection of clones with the inserted fragment using T4 alpha gt57 beta gt14 and lambda vir. PvuII phages; the phage DNAs contain methylated cytosines and hence can be used to demonstrate McrB restriction. For the efficient expression of the hsdS gene, a BglII fragment of phage lambda carrying the pR promoter was inserted into the BamHI site of the hybrid plasmid. Under these conditions a trans-dominant effect of the hsdXts+d mutation on restriction and modification was detected. Inactivation of the hsdS gene by the insertion of the lambda phage BglII fragment into the BglII site within this gene resulted in the disappearance of the trans-dominant effect. When the cloned BamHI-EcoRI fragment was shortened by HpaI and EcoRI restriction enzymes, the trans-dominant effect was fully expressed. The results indicate that the Xts+d mutation is located in the hsdS gene. The effect of gene dosage of the HsdS subunit on the expression of Xts+d mutation was studied. The results of complementation experiments, using F'-merodiploids or plasmid pBR322 with an inserted Xts+d mutation, support the idea that the HsdSts+d product competes with the wild-type HsdS product, and has a quantitatively different effect on restriction and modification.

Cloning, Molecular↗
PubMed1989

Relationship between the development of lymphatic and glandular tissue in the larynx.

A total of 144 human larynxes, both from the prenatal period and from subjects aged from birth to 95 years, were used for the study of the relationship between the development of glandular tissue and the localization of future laryngeal tonsils. The results of our study are represented graphically. It has been found out that at the sites of future tonsils glands make earlier appearance than at the sites of other glandular groups in the larynx. This interrelationship of lymphatic and glandular tissue has not only morphological but also clinical and immunological importance.

Aging↗
PubMed1988

Plasmid pIMI38--the pBR322 derivative with increased stability in E. coli cells.

Plasmid pIM138 which had been characterized by the higher resistance of its DNA replication to the action of clorobiocin in comparison with the progenitor plasmid, was tested for its stability in host cells in the absence of the antibiotic. Growing without selective pressure, pIM138 was better maintained in cells than pBR322. The stability in the presence and in the absence of clorobiocin can be unanimously assigned to the plasmid itself, but some influence of host cells cannot be excluded.

Base Sequence↗