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L M Murphy

Publications and source records attributed to L M Murphy.

8 recordsLinked to original sources
PubMed1995

Structural and spectroscopic studies of the copper site of stellacyanin.

The structure of the copper site in oxidized and reduced Rhus vernicifera stellacyanin has been studied by X-ray absorption (XAFS) spectroscopy at different pH values. Data for the oxidized protein are consistent with the fourth ligand being an O- or N-donating ligand rather than a cysteine from the disulfide bridge. The fourth ligand is not present in the inner coordination sphere, but makes a more distant interaction 2.7 A from the copper atom. Only minor changes in the details of the Cu(II) coordination occur when the pH is varied. Direct structural information on reduced stellacyanin is provided. Upon reduction, one of the histidine ligands moves away from the copper atom by at least 0.2 A. A low-Z (O or N) scatterer is present approximately 2.4 A from the Cu(I) atom in the protein at low pH, and this ligand is lost at high pH. There is no evidence for an S-donating fourth ligand in the reduced protein. The XAFS results are presented in relation to the spectroscopic and structural information available for some methionine-121 mutants of azurin. The data reveal that there are spectroscopic similarities between stellacyanin and some of the mutant proteins, but distinct structural differences exist that preclude these proteins as suitable models for the copper site of stellacyanin.

Azurin↗
PubMed1987

Transvascular protein movement in the intact ischemic hindlimb.

Postischemic limb swelling following reperfusion may be related to microvascular changes associated with ischemia. We used lymph-to-plasma total protein concentration ratios (L/P) and lymph flow (QL) as an index of transvascular exchange in the intact dog hindlimb during steady state (C) (1 hr), ischemia (I) (6 hr), and reperfusion (R) (3 hr). Central pressures, femoral arterial and venous pressures (PA, PV) and QL were recorded every 15 min. Lymph was collected from a femoral lymphatic in the passively flexed leg (50 cycles/min). Three groups of animals were studied: GI, sham-operated (N = 5); GII, moderate ischemia (N = 7, PA = 30-45% C); and GIII, severe ischemia (N = 7, PA = 5-20% C). In GI, QL gradually increased over 10 hr without change in L/P. Moderate ischemia produced a decrease in QL, 3.55 +/- 2.02 mg/hr to 0.92 +/- 0.53 mg/hr (P less than 0.0001), and QL remained below baseline during R with no change in L/P over the 10 hr. Severe ischemia produced a similar decrease in QL, 1.91 +/- 2.05 mg/hr to 0.15 +/- 0.1 mg/hr (P less than 0.01); however, an increase to 2.56 +/- 2.14 mg/hr occurred during R. Severe ischemia increased L/P 0.42 +/- 0.08 to 0.64 +/- 0.23 (P less than 0.001) and remained elevated during R at 0.63 +/- 0.18 (P less than 0.001). An increase in the wet-to-dry weight ratio of ischemic to nonischemic muscle after reperfusion was noted only in GIII, 3.82 +/- 1.17 vs 2.60 +/- 0.45 (P less than 0.04). Severe ischemia produces changes in vascular integrity which augment protein flow. Prevention of these vascular changes may help to minimize the muscle swelling of reperfusion.

Animals↗
PubMedDate not supplied

Central venous catheter care in parenteral nutrition: a review.

Central venous catheter care in parenteral nutrition has been described in numerous publications. These descriptions include care of both short- and long-term catheters. Important aspects in the prevention of infection in central venous catheters used for parenteral nutrition have included: the method of central venous access, subcutaneous tunneling, dressing change techniques, therapeutic uses of the catheter, and catheter-intravenous tubing connection care. Methods of predicting infection and evaluating catheter sepsis have been described. The efficacy of intervention by specialized nutrition support teams in infection control related to these catheters has been demonstrated. Newer partially implantable and completely implantable venous access devices have been used for parenteral nutrition. Methods of infection control and prevention of mechanical damage of these types of catheters have been examined with various results. Care and composition of central venous catheters have been shown to have some role in thrombus formation in the central veins. The use of heparin to prevent thrombosis and catheter occlusion, and the varying degrees of success obtained, have been described. Medical treatment of the occluded catheter with urokinase may be a necessary alternative to discontinuance of that catheter. Overall consideration of research methods used to reach conclusions for catheter care should be considered in the evaluation of appropriate care in each situation.

Catheters, Indwelling↗