Biomedical subjects

K C Pugh

Publications and source records attributed to K C Pugh.

5 recordsLinked to original sources

PubMed1998

Reliability issues with the Synthetic Sentence Identification test.

This investigation examined the reliability of the Synthetic Sentence Identification (SSI) test. An adaptive procedure was used to assess speech recognition thresholds (SRTs) for the SSI lists over two separate test sessions. The commercially available Davy Crockett passage and a multitalker babble were used as competition. Subjects consisted of 20 adults with normal hearing sensitivity. Results indicated (1) significantly higher SRTs with the multitalker babble, (2) significant differences in SRTs among SSI lists when using the Davy Crockett competition, (3) no significant learning/practice or fatigue effects across trials in either noise condition, and (4) high test-retest reliability across test sessions. Clinical implications of these data are considered.

Adolescent↗

PubMed1993

Synthesis and stability of 3-nitro-2-pyridinesulfenyl chloride (NpysCl).

3-Nitro-2-pyridinesulfenyl chloride (NpysCl) is the starting material for the synthesis of N-, O- and S-Npys-protected amino acids. Two efficient, novel synthetic routes to NpysCl are described. The stability of NpysCl was determined in a variety of solvents, with and without base, to determine the most suitable solvent and base for the synthesis of N-Npys amino acids. The syntheses of Npys-Ala and Boc-Lys(Npys) tert-butylammonium salt are also described.

Alanine↗

PubMed1991

Proton, calcium, and magnesium binding by peptides containing gamma-carboxyglutamic acid.

gamma-Carboxyglutamic acid (Gla) is believed to bind Ca [II] ions and Mg [II] ions in prothrombin and other coagulation proteins. Binding constants for H+, Ca [II] ions, and Mg [II] ions to Gla-containing peptides are determined using pH and ion selective electrode titrations. The binding constants for peptides containing a single Gla residue are similar to the constants for malonic acid. Peptides containing two Gla residues in sequence (di-Gla peptides) bind Ca [II] ions and Mg [II] ions more strongly. KMgL for the di-Gla peptides is similar to the site-binding constant for Ca [II] ions in denatured BF1. These di-Gla peptides may be useful analogs for metal binding by the disordered Gla domain in BF1.

1-Carboxyglutamic Acid↗

PubMed1990

Synthesis and characterization of 1,1,4,4-butanetetracarboxylic acid. A di-gamma-carboxyglutamic acid (GlaGla) analogue.

1,1,4,4-Butanetetracarboxylic acid (BTCA) is evaluated as an analogue for the metal binding site in dipeptides of gamma-carboxyglutamic acid (Gla). Molecular modeling suggests that the four carboxylic acid groups in BTCA can assume a similar conformation to the four gamma-carboxylic acid groups in GlaGla and thus provides the impetus for the synthesis and metal binding determinations. BTCA is synthesized via the tert.-butyl ester and characterized via NMR, mass spectroscopy, and elemental composition. Equilibrium binding constants with protons, Ca(II) and Mg(II) are determined via pH and Ca(II) ion-selective electrode titrations and are found to be similar to those for GlaGla peptides with blocked termini.

Binding Sites↗

PubMedDate not supplied

Effects of resin swelling and substitution on solid phase synthesis.

Resins sold by several companies were examined for swelling, uniformity of beads, and substitution in the case of resins sold with the first amino acid attached. Effects of resin swelling, uniformity, and substitution on the solid phase synthesis of long, structured and/or branched peptides were evaluated.

Amino Acid Sequence↗