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Biomedical subjects

C Sander

Publications and source records attributed to C Sander.

At least 217 records · Page 12Linked to original sources
PubMed1982

The ten helical twist angles of B-DNA.

On the assumption that the twist angles between adjacent base-pairs in the DNA molecule are additive a linear system of 40 equations was derived from experimental measurements of the total twist angles for different pieces of DNA of known sequences. This system of equations is found to be statistically consistent providing a solution for all ten possible twist angles of B-DNA by a least squares fitting procedure. Four of the calculated twist angles were not known before (tau AC, tau AG, tau CA, tau TA). The other six twist angles calculated are very close to the experimentally measured ones (tau AA, tau AT, tau CC, tau OG, tau GA, tau GC). The data used were obtained by the electrophoretic band-shift method (1-3), crystallography (4) and nuclease digestion of DNA adsorbed to mica or Ca-phosphate surface (5,6). The validity of the principle of additivity of the twist angles implies that the angle between any particular two base-pairs is a function of only these base-pairs, independent of nearest neighbours.

DNA↗
PubMed1982

Nurses' perceptions of pediatric nursing functions.

The purpose of this study was to describe nurses' perceptions of the importance of pediatric nursing functions and to determine if there were differences in perceptions of nurses in managerial, clinical, and teaching positions. Subjects were 125 pediatric nurses in managerial, clinical, and teaching positions. Respondents were asked to rate the importance of 43 nursing functions on a 9-point scale ranging from highly important to not at all important. Mean ratings of pediatric nursing functions were determined and one-way analyses of variance performed. The five nursing functions perceived to be most important were, in order of ranking: (a) providing emotional support of children, (b) recognizing significant physical deviations, (c) implementing nursing interventions, (d) preparing children psychologically for procedures and surgery, and (e) identifying nursing problems. Significant differences were found between groups in perceptions of the importance of 23 nursing functions, mainly in the areas of psychosocial care, teaching, and nursing process. Most differences were between the teaching and managerial groups or between teaching and the managerial and clinical groups combined. Differences in perceptions of the importance of a number of nursing functions, though not great, suggest a need for more dialogue between managers, teachers, and clinicians.

Analysis of Variance↗
PubMed1979

L-Phenylalanine ammonia-lyase and pisatin induction by 5-bromodeoxyuridine in Pisum sativum.

The substitution of the base analogue 5-bromodeoxyuridine (BrdU) for thymidine in the DNA of pea pods (Pisum sativum) induces or enhances the level of phenylalanine ammonia-lyase (PAL) and also induces the phytoalexin, pisatin, a product of the same metabolic pathway. Cordycepin, a polyadenylate inhibitor at the RNA level, is a potent inhibitor of pisatin synthesis. Kinetic studies on the inhibition of the PAL-pisatin production by hydroxyurea indicate that BrdU must be incorporated into DNA before any induction takes place. 5-Iododeoxyuridine is also an inducer while 5-fluorodeoxyuridine is ineffective when applied alone. BrdU is incorporated into the DNA of pea cells and the nuclei undergoes condensation just prior to the detection of the induced responses.

Ammonia-Lyases↗
PubMed1979

Degeneracy of the information contained in amino acid sequences: evidence from overlaid genes.

The observed gene overlays in the viruses phi X174 and SV40 show a surprising economy of information storage; two different amino acid sequences are read in different frames from the same stretch of DNA. This phenomenon appears contradictory in that the information in the two overlaid amino acid sequences is strongly interdependent, yet each of the two proteins has evolved to its own well-defined function. The contradiction can be resolved by assuming sufficiently large degeneracy of the information contents of amino acid sequences with respect to function. Such a degeneracy is familiar from homologous proteins where a given biological function is implemented by many different amino acid sequences. It is shown that the very existence of viral overlays allows to derive a lower limit for the magnitude of this degeneracy: The degeneracy is equal to, or greater than fourfold; on the average, at each position of the chain a choice of 1 out of 5 or less amino acids, and not a choice of 1 out of 20 is neccessary for constructing a protein with a specified function. In addition, the strong dependence of overlay probabilities on chain length allows the definition of a maximal length of overlays; in bacterial viruses overlay regions should be shorter than about 150 residues.

Amino Acid Sequence↗
PubMed1978

Mutagenic and chromosome-breaking effects of azide in barley and human leukocytes.

Azide (10-3 M, solution buffered at pH 3) is more effective in inducing mutations in embryonic shoots of seeds germinated between 8 and 16 h than in non-germinated seeds and in seeds germinated between 0 and 8 h and 16 to 28 h. This peak of chlorophyll-deficient seedling mutation frequency coincides with maximum frequencies of seeding lethals and DNA replication in the cells of the embryonic shoot. The mutation data suggest azide may only act on replicating DNA. Azide induced no chromosome-aberration frequencies significantly above controls in (1) embryonic shoots of barley seeds germinated for 8--12 h, (2) microspores of barley and (3) human leukocytes. It appears to be a point-mutation mutagen.

Azides↗