PubMed Health⌕ Search

Biomedical subjects

P E Butler

Publications and source records attributed to P E Butler.

15 recordsLinked to original sources
PubMed1991

Improved wound healing with a modified electrosurgical electrode.

Previous studies comparing standard electrosurgical (ES) electrode and steel scalpel (SS) wound healing have reported poor initial tensile strength, a delay in reaching maximum tensile strength and an increased inflammatory response in the ES wounds. The hypothesis that a smaller needle (modified) electrode would give better wound healing than a standard electrode was tested. Using histology as a parameter of wound healing, incisions created by a modified electrode, a standard electrode and a steel scalpel were compared. Sixty Sha Sha mice were divided into 10 groups. Standardised dorsal skin incisions were made using steel scalpel, standard and modified electrosurgical cutting electrodes. Mice were sacrificed on days 0, 1, 2, 3, 5, 7, 9, 14, 28 and 42. The incised skin was processed for standard and immunohistochemical staining. The standard ES wound had significantly higher numbers of polymorphonuclear leukocytes in comparison to the SS and modified ES wounds (p less than or equal to 0.01). However, macrophage numbers were found to be significantly lower in the ES wounds when compared to the SS wounds on days two and five (p less than or equal to 0.05). The fibroblast response was delayed by up to two days in the ES wounds when compared to the SS wounds. Epithelialisation was completed by day two in the SS and modified ES groups but was only complete by day three in the standard ES group (p less than or equal to 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Regulation of a membrane-bound proteinase in mammalian cells.

Cellular proteolytic enzymes are regulated by multiple mechanisms that affect gene expression, enzyme concentration, and enzyme activity. The expression of the membrane-bound metallo-endopeptidase, meprin, in different mammalian species, strains, tissues and cell types is highly variable. Meprin is exclusively localized to the plasma membrane, and this determines the types of substrates the enzyme will encounter and the microenvironment for activity. Recent studies have revealed an inactive form of a meprin-like proteinase that can be activated in vitro by proteases, and this raises the possibility of regulation of enzyme activity at the cell surface in response to environmental stimuli. In this chapter, the current knowledge about meprin, and the meprin-like inactive forms in mouse kidney is discussed.

Animals↗
PubMed1988

A latent proteinase in mouse kidney membranes. Characterization and relationship to meprin.

Inbred mice can be phenotypically divided into two groups: those that contain high levels of a kidney metallo-endopeptidase activity (meprin-a) and those with low meprin-a activity. In studies to investigate the molecular basis for the heterogeneity in the expression of this proteinase activity, we found a latent metallo-proteinase activity associated with kidney membranes of C3H/HeJ mice, a low activity strain. The latent proteinase was activated by treatment of kidney brush border membranes with trypsin and was purified from solubilized C3H kidney membranes. Purified preparations of the C3H latent proteinase (referred to as meprin-b) contained three major proteins of subunit molecular weights 90,000, 140,000, and 160,000. In the absence of reducing agents, four 90,000-Da subunits are covalently linked by S-S bridges. The two higher molecular mass proteins are not covalently linked to each other or to the 90,000-Da subunits. However, cross-linking and affinity chromatography studies indicated that the proteins in the meprin-b preparation were tightly associated. By contrast, purified meprin-a contains only 85,000-Da subunit proteins linked by S-S bridges to form a tetramer. Endoglycosidase F treatment decreased the mass of the 90,000-Da meprin-b subunit and the 85,000-Da meprin-a subunit to polypeptides of 65,000-70,000 Da. The 90,000- and 85,000-Da subunits are immunologically similar, in that polyclonal antibodies prepared against one of the subunits cross-react with the other. The substrate specificities and inhibitor profiles of purified preparations of meprin-a and meprin-b are also similar. These data are consistent with the proposition that meprin-b is a polymorphic form of meprin-a that is incompletely processed in vivo.

Amino Acids, Sulfur↗
PubMed1987

Characterization of meprin, a membrane-bound metalloendopeptidase from mouse kidney.

Meprin is an intrinsic protein of the brush border, a specialized plasma membrane, of the mouse kidney. It is a metalloendopeptidase that contains 1 mol of zinc and 3 mol of calcium per mol of the 85,000-Mr subunit. The enzyme is isolated, and active, as a tetramer. The behaviour of the enzyme on SDS/polyacrylamide gels in the presence and absence of beta-mercaptoethanol indicates that the subunits are of the same Mr (approx. 85,000) and held together by intersubunit S--S bridges. Eight S-carboxymethyl-L-cysteine residues were detected after reduction of the enzyme with beta-mercaptoethanol and carboxymethylation with iodoacetate. The enzyme is a glycoprotein and contains approx. 18% carbohydrate. Most of the carbohydrate is removed by endoglycosidase F, indicating that the sugar residues are N-linked. The isoelectric point of the enzyme is between pH 4 and 5, and the purified protein yields a pattern of evenly spaced bands in this range on isoelectric focusing. The peptide-bond specificity of the enzyme has been determined by using the oxidized B-chain of insulin as substrate. In all, 15 peptide degradation products were separated by h.p.l.c. and analysed for their amino acid content and N-terminal amino acid residue. The prevalent peptide-bond cleavages were between Gly20 and Glu21, Phe24 and Phe25 and between Phe25 and Tyr26. Other sites of cleavage were Leu6-Cysteic acid7, Ala14-Leu15, His10-Leu11, Leu17-Val18, Gly8-Ser9, Leu15-Tyr16, His5-Leu6. These results indicate that meprin has a preference for peptide bonds that are flanked by hydrophobic or neutral amino acid residues, but hydrolysis is not limited to these bonds. The ability of meprin to hydrolyse peptide bonds between small neutral and negatively charged amino acid residues distinguishes it from several other metalloendopeptidases.

Amino Acids↗
PubMed1986

Metalloendopeptidases of the mouse kidney brush border: meprin and endopeptidase-24.11.

Two metalloendopeptidases, meprin and endopeptidase-24.11 ("24.11"), were isolated from mouse kidney membranes, and their structural and catalytic properties were investigated. The enzymes both cross-react with antibodies prepared in rabbits against purified preparations of meprin; thus they share some immunologic determinants. Meprin and 24.11 have similar subunit molecular weights of 85 000 and 90 000, respectively, as demonstrated after sodium dodecyl sulfate polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol. However, under non-reducing conditions, meprin migrates as an oligomer while 24.11 remains monomeric. This and other data indicate that meprin subunits are linked by disulfide bridges, whereas endopeptidase-24.11 subunits are not covalently linked. Both endopeptidases hydrolyze insulin B chain and are totally inhibited by EDTA and o-phenanthroline. The activity of 24.11 against insulin B chain was totally inhibited by low concentrations of phosphoramidon (less than 2 nM), whereas meprin was not inhibited by concentrations of this inhibitor as high as 20 microM. Large proteins are not substrates for endopeptidase-24.11, while meprin degrades proteins such as azocasein rapidly (apparent Km = 0.65 mg/ml). Meprin appears to require an extended polypeptide chain in substrates while 24.11 prefers smaller peptides as substrates. Both endopeptidases have a preference for peptide bonds that contain hydrophobic amino acids. With the octapeptide angiotensin II as substrate, both enzymes hydrolyze the central Tyr-Ile bond; 24.11 also cleaves at Arg-Val and Ile-His. The two endopeptidases show many similarities immunologically, structurally and catalytically, however, they display distinct characteristics which may be physiologically important.

Angiotensin II↗
PubMed1985

The turnover of skeletal muscle glycogen phosphorylase studied using the cofactor, pyridoxal phosphate, as a specific label.

The turnover of glycogen phosphorylase has been measured using the cofactor, pyridoxal phosphate, as a label specific for this enzyme in skeletal muscle. Radiolabelled pyridoxine administered in vivo is incorporated into a protein-bound fraction in skeletal muscle, shown by several criteria to be equivalent to glycogen phosphorylase. This pool of radiolabel disappears slowly with a half-life of 11.9 days, taken to be a good estimate of the intracellular half-life of the enzyme. The use of the cofactor in this fashion minimises overestimation of half-life that results from reincorporation of the label. Further, premature dissociation of the cofactor from native enzyme, which would lead to underestimation of half-life, is unlikely. At the level of sensitivity given by this method there was little evidence for the appearance of pyridoxal phosphate-labelled degradation intermediates of the enzyme.

Animals↗
PubMed1985

Accelerated degradation of glycogen phosphorylase in denervated and dystrophic mouse skeletal muscle.

Pyridoxal phosphate, the cofactor of glycogen phosphorylase, fulfils the criteria needed of a turnover label for this enzyme. The decay of protein-bound label following administration of [3H]pyridoxine is a good index of the rate of degradation of the enzyme in vivo. This method has been applied to the study of catabolism of the enzyme in normal, denervated and dystrophic mouse skeletal muscle. In both of the pathological conditions the enzyme is degraded more rapidly than normal.

Animals↗
PubMed1985

Nurses' uniform: an investigation of mobility.

An investigation of the mobility of nurses under three clothing conditions is reported. The need for such a study has arisen as a result of the concern over a possible mismatch between mobility and patient handling requirements. Thirty-seven nurses participated under two of the clothing conditions ('National' dress uniform, Trouser/tunic combination). In addition, ten of these nurses volunteered to provide control data by being measured in a leotard or a swimming costume. Eleven static and sixteen dynamic anthropometric measures were considered. Each nurse was asked to complete a short questionnaire, relating to her subjective attitudes to the uniform and to her own physical state at the time of measurement. Whilst both uniforms imposed restrictions on the shoulder girdle and trunk of up to 10%, the area of greatest concern was the mobility of the hip joint. Hip flexion was reduced by 26% in the dress uniform. The implications of these findings for patient handling procedures are discussed, as are those of the relationship between the environment and the material. Uniform and the nursing image is also considered.

Adult↗