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Biomedical subjects

J Krajewski

Publications and source records attributed to J Krajewski.

At least 19 recordsLinked to original sources
PubMed2000

Attitudes of high school students toward individuals with mental retardation.

The attitudes of 144 high school students toward individuals who have mental retardation were examined using the Mental Retardation Attitude Inventory-Revised (Antonak & Harth, 1994). The inventory is divided into four subscales consisting of statements regarding integration-segregation, private rights, social distance, and subtle derogatory beliefs. Each subscale was assessed along with gender, frequency of contact with individuals who have mental retardation, and prior knowledge about mental retardation. Results indicate that gender and frequency of contact does influence attitudes. These results are significant because these high school students either are or will soon become adults and impact the community with their attitudes.

Adolescent↗
PubMed1998

Patterns of cleavages induced by lead ions in defined RNA secondary structure motifs.

We have characterized the susceptibility of various RNA bulges, loops and other single-stranded sequences to hydrolysis promoted by Pb2+. The reactivity of bulges depends primarily on the structural context of the flanking base-pairs and the effect of nucleotide present at the 5' side of the bulge is particularly strong. The efficiency of stacking interactions between the bulged residue and its neighbors seems to determine cleavage specificity and efficiency. Hydrolysis of two- and three-nucleotide bulges depends only slightly on their nucleotide composition. In the case of terminal loops, the efficiency of their hydrolysis usually increases with the loop size and strongly depends on its nucleotide composition. Stable tetraloops UUCG, CUUG and GCAA are resistant to hydrolysis, while in some other loops of the GNRA family a single, weak cleavage occurs, suggesting the existence of structural subclasses within the family. A very efficient, specific hydrolysis of a phosphodiester bond in the single-stranded region adjacent to the stem in oligomer 12 resembles highly specific cleavages of some tRNA molecules. The reaction occurs in the presence of Pb2+, but not in the presence of several other metal ions. The Pb(2+)-cleavable RNA domain may be considered another example of leadzyme. The results of Pb(2+)-induced hydrolysis in model RNA oligomers should be useful in interpretation of cleavage patterns of much larger, naturally occurring RNA molecules.

Base Sequence↗
PubMed1995

Mutations of Arabidopsis thaliana pre-tRNA(Tyr) affecting pseudouridylation of U35.

The structural and sequence requirements for the biosynthesis of tRNA(Tyr) pseudouridine (psi 35) have been studied. Nucleotide substitution at the 32nd position slightly reduced modification efficiency in the case of transition (C32 to U32) while transversion (C32 to G32) had no effect on the modification process in wheat germ extract. Insertion of one nucleotide into the anticodon stem caused a 2-fold reduction of modification efficiency. Mutants with a partially deleted 12 nt long intron of pre-tRNA(Tyr) exhibited different effects: deletion of 5 nt (7 nt long intron) gave only a reduction in pseudouridylation while deletion of 7 nt (5 nt long intron) almost completely abolished the reaction. The generated mini-substrate consisting of pre-tRNA(Tyr) anticodon stem and intron sequence was partially modified which proved that the crucial elements for recognition of psi 35 introduction had to present in this construct.

Arabidopsis↗
PubMed1995

Defining biologic width in crown lengthening.

Clinicians must be very careful when making clinical evaluations of the need for crown lengthening procedures and margin placement and subsequent determinations about the dento-gingival junction and biologic width. Clinicians have tried to standardize a biologic phenomenon and assign the same standard to all patients regardless of the circumstances.

Adult↗
PubMed1994

Standardization of HeLa cells preparations as the source of snRNA's for preliminary study on the effectors of pre-mRNA splicing.

Physical, chemical and biological parameters of HeLa cell cultures, which ensure obtaining standard nuclear material to be used as a source of snRNP and snRNA, have been determined. The secondary structure of U1 snRNA as the result of the conformational studies performed using S1 nuclease, A and T1 ribonuclease and Pb(II) ions, and reproducibility of the results obtained after 6-48 h exposure of the cells to actinomycin D at high concentration permit to accept the proposed method of standardization as satisfactory for investigation into snRNP and snRNA.

Base Sequence↗
PubMed1992

Rapid separation of tyrosine-specific tRNA from white lupin.

During isolation of total ribonucleic acids from white lupin (Lupinus albus) and their subsequent separation by 10% polyacrylamide gel electrophoresis, a fast migrating RNA band is very well separated. The nucleotide sequence analysis of 76 nucleotide long sequence with many modified nucleosides was found to be identical with that of tyrosine specific tRNA of yellow lupin seeds (Lupinus luteus) and wheat germ (Triticum aestivum). Also this tRNA(Tyr) is identical with plant amber suppressor tRNA. The presented approach offers a very rapid method of purification of plant tRNA with UAG suppressor activity.

Base Sequence↗
PubMed1992

[Principles of establishing the registries of chemical substances in the United States and Europe].

The paper presents the principles of building up the inventories of chemical substances in the USA, the countries belonging to European Economic Community (EEC) and Austria. In all countries, the appropriate legal regulations putting the manufacturers and importers of chemicals under obligation to provide some strictly determined information underlie the decision to build up these inventories. The data provided usually inform of: manufacturer's name and address, chemical substance identity, production volume and ways of distribution. The paper presents also the criteria of selection of substances to be placed in the inventory, organizational scheme of building up the inventory and the ways of exacting the respective regulations. The inventories of chemical substances issued in the USA and Austria may serve as banks of information on the place, kind and quantity of chemical substances on the territory of the whole country. Based on these data a map of chemical hazards zones may be prepared which may adversely affect either human health or environment. The inventory of EEC countries may serve only as lists of chemicals occurring in the common market.

Austria↗
PubMed1985

Chromosome studies in 3665 consecutive newborn children.

Results of chromosomal studies done on 3665 newborn children from central Poland have been described. As against a global incidence of 1:1022 for trisomy G and 1:1308 for the balanced translocation D/D in infants, the respective figures for the Polish infants were, 1:610 and 1:1221. Likewise, against the global incidence of 1:823 for the karyotype 47, XXY and of 1:1072 for the karyotype 47, XYY in infants, the respective incidence in the Polish infants was 1:626 and 1:939. The study has demonstrated also that the frequency of occurrence of the different widths of the C-bands had a distribution close to normal. The authors have noted that the children with chromosomal abnormalities were more frequently not as well developed at birth as were children with normal karyotypes.

Adult↗
PubMed1983

2,3-diphosphoglycerate concentration in the red blood cells of anaemic pregnant women in various periods of pregnancy.

The purpose of this study was to examine the intraerythrocytic 2,3-diphosphoglycerate (2,3-DPG) concentration in anaemic (haemoglobin concentration below 10.5 g/100 ml blood) and in normal pregnant women (haemoglobin concentration above 12.5 g/100 ml blood). The authors showed that the 2,3-DPG concentration increased systematically between the 16th and 42nd weeks of pregnancy, both in the control group and in pregnant women with anaemia. However, in the group of anaemic pregnant women the 2,3-DPG concentration was higher in each stage of pregnancy.

Adult↗