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Biomedical subjects

L E Kay

Publications and source records attributed to L E Kay.

114 records · Page 7Linked to original sources
PubMed1987

Specific peroxidase isoenzymes are correlated with organogenesis.

We have examined isoperoxidase patterns obtained from buffer-, salt-, and enzyme-extractable fractions and correlated them with histological changes in tobacco (Nicotiana tabacum L., cv Wisc. 38) ;epidermal' explants induced to produce either callus, vegetative buds, or floral buds. By utilizing a combination of extraction and electrophoretic procedures different from any hitherto used for this kind of investigation, we were able to resolve 47 isoperoxidases distributed between the three types of fractions. The majority of these isoperoxidases were common to all explants regardless of their developmental fate. Correspondingly, a number of histological changes were observed in all explants (e.g. the initiation of cell division by day 2, lignin deposition by day 4, and the formation of clustered tracheary elements by day 8). We have made correlations between 25 isoperoxidases and specific developmental events based on the time when certain isoperoxidases were detected relative to observed histological changes: 3 were correlated with desuppressed/sustained cell division, 3 to 6 with lignification/tracheary element maturation, 7 with callus formation, 1 with localized suppression of growth, 3 with determinate axial organization, 4 with leaf development, and 1 with stamen development. These results suggest that a continued investigation using this system could lead to a better understanding of the role of specific isoperoxidases in different developmental processes.

Journal Article↗
PubMed1986

1H NMR spectroscopic studies of calcium-binding proteins. 1. Stepwise proteolysis of the C-terminal alpha-helix of a helix-loop-helix metal-binding domain.

A series of modified parvalbumins, differing only in length of alpha-helix F at the C-terminus, was prepared by carboxypeptidase-mediated digestions of the beta-lineage parvalbumin (pI = 4.25) from carp (N; 108 residues). Removal of Ala-108 to form the N-1 derivative (des-Ala108,Lys107-parvalbumin) only slightly alters the protein's ability to chelate Ca(II) or lanthanides(III). Analysis of the kinetics of their Yb(III) off-rates by optical stopped-flow techniques, determination of their Lu(III)-binding constants by high-resolution 1H NMR methods, and inspection of their solution structures by Yb(III)-shifted 1H NMR techniques indicate N-1 and N-2 are very similar to N (0.1-0.2 M KCl; pH 6-7; 23-55 degrees C). However, removal of the next one or two residues, Val-106 or Val-106/Leu-105, to generate the N-3 and N-4 derivatives severely alters the metal ion binding characteristics of the protein. Although two Yb(III) off-rates are observed for N-3, both are faster than that for the unmodified protein: kCD by a factor of 2 and kEF by a factor of 2200. Removal of Ala-104 and Ala-104/Thr-103 to give a mixture of N-5 and N-6 derivatives eliminates the slow-release site altogether, the single observable koff being 20-30 times faster than release of Yb(III) from the CD site of native parvalbumin. Removal of the C-terminal alpha-helix by digestion through Phe-102 to give N-7 destabilizes the entire protein structure as judged both by the random-coil appearance of its 1H NMR spectrum and by its aberrant kinetics. Although one abnormally fast koff is still observed at micromolar concentrations, Ln(III) chelation tends to precipitate N-7 at higher parvalbumin concentrations (1-3 mM). In contrast to the critical instability of the N-3 through N-7 derivatives, the remarkable stability of the N-1 and N-2 forms of carp parvalbumin may be attributed to the maintainance of two key structural features: an ion pair bond between the negatively charged C-terminal carboxyl function and the protonated epsilon-NH3+ of Lys-27 and hydrophobic interactions of the inner side of helix F with residues in the protein's core.

Animals↗
PubMed1985

Nuclear magnetic resonance determination of metal-proton distances in a synthetic calcium binding site of rabbit skeletal troponin C.

The binding of gadolinium to a synthetic peptide of 13 amino acid residues representing the calcium binding loop of site 3 of rabbit skeletal troponin C [AcSTnC(103-115)amide] has been studied by using proton nuclear magnetic resonance (1H NMR) spectroscopy. In particular, the proton line broadening and enhanced spin-lattice relaxation have been used to determine proton-metal ion distances for several assigned nuclei in the peptide-metal ion complex. These distances have been used in conjunction with other constraints and a distance algorithm procedure to demonstrate that the structure of the peptide-metal complex as shown by 1H NMR is consistent with the structure of the EF calcium binding loop in the X-ray structure of parvalbumin but that the available 1H NMR distances do not uniquely define the solution structure.

Animals↗
PubMedDate not supplied

Accuracy of blood pressure measurement in the family practice center.

BACKGROUND: Equipment, physiologic, and technique factors can influence the accuracy of blood pressure measurement. The current study was designed to isolate certain technique factors and then assess the accuracy of nursing personnel measurements of blood pressure in three residency family practice centers. METHODS: An experienced registered nurse was trained in applying the American Heart Association recommendations for determining blood pressure by sphygmomanometry; three 1.5-hour practice sessions demonstrated her accuracy. Nine full days were then spent in the family practice centers rechecking as many staff blood pressure readings as possible while controlling for confounding variables. RESULTS: The following findings were significant: (1) the average absolute differences between control and study nurse systolic and diastolic blood pressure readings were 6.2 mmHg and 4.7 mmHg, respectively; (2) a unidirectional error of 3.8 mmHg in the measurement of diastolic blood pressure was found in one center, possibly because less care was taken with afternoon measurements; (3) variability in systolic blood pressure readings was higher in all three centers (+/- 8.5 mmHg) than attained during the training sessions for the control nurse (+/- 5.8 mmHg); (4) the average errors attributable to technique factors studied that were potentially correctable by training were only 1.8 mmHg for systolic and 0.7 mmHg for diastolic pressures. CONCLUSIONS: The degree of inaccuracy in ambulatory nursing blood pressure readings attributable to errors in technique is quantified by this study. Training can reduce, but not abolish, this inaccuracy. Careful attention to proper blood pressure measurement technique and such variables as equipment calibration is essential for both nursing and physician observers. Taking multiple blood pressure measurements before making clinical decisions can limit the effect of these inaccuracies.

Adult↗