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Biomedical subjects

L Katona

Publications and source records attributed to L Katona.

7 recordsLinked to original sources
PubMed1998

Pathogenesis of Lyme neuroborreliosis in the rhesus monkey: the early disseminated and chronic phases of disease in the peripheral nervous system.

The histopathologic and immunohistochemical features of early and late neuroborreliosis of the peripheral nervous system were investigated in rhesus macaques infected with the JD1 strain of Borrelia burgdorferi. Infection was proven by culture or polymerase chain reaction analysis of skin biopsies and indirectly by Western blot analysis. Three months after infection, neuritis involving multiple nerves was the most consistent neurologic manifestation. Both macrophages and B lymphocytes but not T lymphocytes were present in the cellular infiltrates. Axonal structures surrounding infiltrates had changes consisting of demyelination and axonal phagocytosis. Some of the Schwann cells in lesions stained with anti-nitrotyrosine and anti-tumor necrosis factor-alpha antibodies. B. burgdorferi, or antigens thereof, were visualized immunohistochemically within macrophages. Forty-six months after infection, the most common changes were regenerative, whereas neuritis was infrequent. Aberrant axonal regeneration, irregularly sized myelinated fibers, and fibrosis were frequently observed. Possible mechanisms to explain the appearance and subsidence of Lyme neuritis are discussed.

Animals↗
PubMed1990

Comparison of in vitro and in vivo activities associated with the G6PD allozyme polymorphism in Drosophila melanogaster.

Earlier studies of the A and B allozymes at the G6pd locus show a differential ability of the genotypes to suppress the loss of viability associated with a low activity 6-phosphogluconate dehydrogenase mutation, 6Pgdlo1. This observation indicates a relatively lower activity for the A allozyme genotype, but it is not known if this level of suppression required a large difference in in vivo activity. To clarify this difference an analysis of the biochemical properties of the purified allozymes was carried out, as well as an analysis of the activity level associated with an original low activity P element-derived allele which had partially reverted and lost its suppression ability. G6PD activity and protein level were studied in 47 X chromosome lines from North America. The A genotype averages a 9% lower Vmax. From analysis of the correlation between G6PD activity and protein level it remains unclear whether the allozyme Vmax difference results from dissimilarity in protein level or kcat. At 25 degrees and physiological pH, comparative studies of the steady-state kinetics show the two purified allozyme variants differ significantly in their KM values for glucose-6-phosphate and NADP, and the K1 for NADPH. In aggregate these parameters predict the A genotype possesses a 20% lower in vitro catalytic efficiency. A partial revertant of a P element-derived low activity B variant, was shown to lose the ability to suppress 6Pgdlo1 low viability after acquiring only 60% of normal B activity. This last comparison shows the A genotype activity must be reduced in vivo by at least 40%.

Analysis of Variance↗
PubMed1976

[Directives of the struggle against smoking in Hungary (author's transl)].

Smoking is not only noxious to the smoker but molestates the non-smoker, too. Though a general renunciation is not attainable our efforts should be directed to the following aims: 1. To discourage juveniles from smoking as much as possible. 2. To minimize the danger of passive smoking for non-smokers. 3. Influencing the patients by the doctors to minimize the nicotine-dependence.

Adolescent↗
PubMed1975

Effects of various protein-modifying agents and the aminonucleoside of puromycin on dithioerythritol-reducible disulfide in glomerular basement membrane.

Comparative study of dithioerythritol-reducible (DTE) disulfide bonds in glomerular basement membranes (GBM) isolated from normal rats and from similar groups of rats treated with the nephrosis-producing aminonucleoside of puromycin emphasize not only the importance of such linkages in the interaction and structural organization of the macromolecular GBM collagen-glycoprotein matrix but also suggest a modality by which GBM semi-permeability might be engendered. Although DTE-reducible disulfide is significantly reduced in GBM of rats as early as the fourth day after administration of a nephrosis-producing dose of the aminonucleoside it has not been possible to demonstrate an unequivocal in vitro or direct effect of the drug on DTE-reducible disulfide in normal GBM. Several-fold increases in DTE-reducible disulfide in GBM subjected to the denaturing action of guanidine-HCl or the proteolytic action of pronase indicates that most of the disulfide lies buried in the GBM. Location of disulfide crosslinks in the innermost regions or core of the GBM might be expected to not only stabilize the membrane but also to protect the GBM from a considerable array of disulfide cleaving (reductases) within the kidney cortex.

Animals↗
PubMed1973

Galactosylserine in extensin.

Cell walls obtained from tomato suspension cultures were treated at pH1 for 1h at 100 degrees C to remove arabinose oligosaccharide substituents from the hydroxyproline residues of extensin. Tryptic attack of these acid-stripped walls yielded glycopeptides containing galactose. When one of these glycopeptides (designated S(2)A(6); sequence NH(2)-Ser-Hyp-Hyp-Hyp-Hyp-Ser-Hyp-Lys-CO(2)H) was treated with (a) NaOH-NaBH(4) or (b) NaOH-Na(2)SO(3) some of the serine was converted into (a) alanine or (b) cysteic acid, and the peptide lost galactose. Maleylation or 3-carboxypropionylation of N-terminal serine was necessary for conversion of this residue and for complete loss of galactose. These results indicate that a single galactose residue is attached O-glycosidically to each of the two serine residues. Hydrazinolysis of peptide S(2)A(6) or of isolated cell walls also led to destruction of serine. In control experiments non-glycosylated serine was not destroyed during hydrazinolysis. Thus the galactosylserine linkage is sensitive to N(2)H(4).

Amino Acid Sequence↗