Inducing activity of cephalosporins for beta-lactamases in two characterized staphylococcal strains.
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Anti-Bacterial Agents↗
Biomedical subjects
A Tar
Publications and source records attributed to A Tar.
Experience with neonatal screening for congenital hypothyroidism in Hungary.
The experience obtained in one of two Hungarian screening centers for congenital hypothyroidism (CH) is reported which is based on the examinations of dried blood samples tested with the aid of TSH-RIA developed in this laboratory. During the past six years (1982-88) and CH was diagnosed in 54 cases out of a total of 306,265 newborns (prevalence: 1:5470). The recall rate because of increased TSH values was 0.28-0.29% within the last two years. The triple of this had to repeat for technical reasons (imperfect samples, borderline results). Within the last year the treatment of diagnosed infants with L-thyroxine was started at the average age of 13 days. The history of three missed cases is briefly reported. Four out of 54 patients (7.4%) died in infancy. Since the pituitary sensitivity for TSH suppression by replacement doses of L-thyroxine appeared to be decreased in several cases, the control of free thyroxine levels is preferred to avoid the clinical hypo- or hyperthyroidism. The shortening of the present three days TSH RIA method, the extension of systematic examination of TSH binding antibodies and psychological studies are in progress.
Congenital Hypothyroidism↗
Modified general affinity adsorbent for large-scale purification of penicillinases.
N-Acetyl-D-(-)-penicillamine as a stable second-generation biospecific affinity ligand has previously been suggested for purification of Bacillus cereus 569/H beta-lactamase I. A complex spacer arm is coupled with the matrix by using epichlorohydrin and phloroglucinol doubly activated with divinyl sulphone in the meta position. Coupling of D-(-)-penicillamine ligand resulted in an active affigel. However, we found that two affinity ligands in close proximity prevents simultaneous binding of two penicillinase molecules, therefore one ligand is superfluous. Our results show that: (1) shortening the spacer arm by direct activation of the matrix with divinyl sulphone is satisfactory to produce the affinity material with N-acetyl-D-(-)-penicillamine; (2) incorporation of 15 mumol of N-acetyl-D-(-)-penicillamine per ml of wet Sepharose 4B satisfies the maximum binding capacity requirements of the affigel (about half of the originally incorporated amount of ligand); (3) our simplified affinity adsorbent is generally applicable for large-scale purification of penicillinases to homogeneity from various bacterial sources by the convenient batch method without prior concentration of these enzymes; (4) reacetylation for four/five times can regenerate the original binding capacity of the affigel.
Bacteria↗
Control of thyroglobulin secretion in patients with ectopic thyroid gland.
Serum thyroglobulin (Tg) measurements were performed in 17 children with congenital hypothyroidism due to an ectopic thyroid gland before therapy and during follow-up. Data were analysed in four periods according to duration of therapy and compared to results obtained in a group of 51 normal children aged 1 month to 6 yr. At diagnosis serum Tg was higher than the mean normal value measured at a similar age. We observed a rapid and parallel decrease of both Tg and thyroid-stimulating hormone during the early weeks of therapy. However, Tg was always detectable in the serum of treated (euthyroid) patients. After 34 months of therapy serum Tg was 11.4 +/- 1 ng/ml, a value significantly different (p less than 0.001) from that obtained in normal controls of similar age (23.5 +/- 3 ng/ml). In nine treated children aged more than 2 yr, thyroid-stimulating hormone and Tg were increased after a brief period of decreased L-thyroxine dosage. These data indicate that ectopic thyroid tissue does not involute during thyroxine therapy and, in response to elevations of serum thyroid-stimulating hormone, can be stimulated to secrete Tg.
Child↗
Use of chromatofocusing for separation of beta-lactamases. VIII. Analytical chromatofocusing of chromosomal cephalosporinases from four Klebsiella strains.
Although still there are Klebsiella strains which do not harbour plasmids and produce constitutive chromosomal beta-lactamases, recently clinical isolates were found in ever increasing numbers carrying mainly TEM-, CARB- and OXA type R-factors. We selected four chromosomal cephalosporinase producing Klebsiella strains to study the pI values of the enzymes and their simultaneous separability from accompanying proteins by chromatofocusing techniques. We compared pI values of the pure and the crude preparations: K. pneumoniae K1 SC 10436: pIpure = 6.4, pIcrude = 6.42; K. aerogenes K1 1082 E: pIpure = 6.5, pIcrude = 6.5; K. oxytoca 1082 E: pIpure = 6.42, pIcrude = 6.4; K. oxytoca 20: pIpure = 7.62, pIcrude = 7.6. Excellent agreement of the pI values among each other, but occasional differences with those obtained by analytical isoelectrofocusing are attributed to methodological diversities and to the presence of satellite enzymes, known to exist in Klebsiella.
Bacterial Proteins↗
Use of chromatofocusing for separation of beta-lactamases. VII. Analytical and medium scale preparative chromatofocusing of the constitutive chromosomal cephalosporinase P99 from Enterobacter cloacae.
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Cephalosporinase↗
Determination of zearalenone content in cereals and feedstuffs by immunoaffinity column coupled with liquid chromatography.
The zearalenone content of maize, wheat, barley, swine feed, and poultry feed samples was determined by immunoaffinity column cleanup followed by liquid chromatography (IAC-LC). Samples were extracted in methanol-water (8 + 2, v/v) solution. The filtered extract was diluted with distilled water and applied to immunoaffinity columns. Zearalenone was eluted with methanol, dried by evaporation, and dissolved in acetonitrile-water (3 + 7, v/v). Zearalenone was separated by isocratic elution of acetonitrile-water (50 + 50, v/v) on reversed-phase C18 column. The quantitative analysis was performed by fluorescence detector and confirmation was based on the UV spectrum obtained by a diode array detector. The mean recovery rate of zearalenone was 82-97% (RSD, 1.4-4.1%) on the original (single-use) immunoaffinity columns. The limit of detection of zearalenone by fluorescence was 10 ng/g at a signal-to-noise ratio of 10:1 and 30 ng/g by spectral confirmation in UV. A good correlation was found (R2 = 0.89) between the results obtained by IAC-LC and by the official AOAC-LC method. The specificity of the method was increased by using fluorescence detection in parallel with UV detection. This method was applicable to the determination of zearalenone content in cereals and other kinds of feedstuffs. Reusability of immunoaffinity columns was examined by washing with water after sample elution and allowing columns to stand for 24 h at room temperature. The zearalenone recovery rate of the regenerated columns varied between 79 and 95% (RSD, 3.2-6.3%). Columns can be regenerated at least 3 times without altering their performance and without affecting the results of repeated determinations.
Animal Feed↗