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D J Murphy

Publications and source records attributed to D J Murphy.

At least 145 records · Page 8Linked to original sources
PubMed1989

Spin-label ESR studies of lipid-protein interactions in thylakoid membranes.

Lipid-protein interactions in thylakoid membranes, and in the subthylakoid membrane fractions containing either photosystem 1 or photosystem 2, have been studied by using spin-labeled analogues of the thylakoid membrane lipid components, monogalactosyldiacylglycerol, phosphatidylglycerol, and phosphatidylcholine. The electron spin resonance spectra of the spin-labeled lipids all consist of two components, one corresponding to the fluid lipid environment in the membranes and the other to the motionally restricted membrane lipids interacting directly with the integral membrane proteins. Spectral subtraction has been used to quantitate the fraction of the membrane lipids in contact with the membrane proteins and to determine the selectivity between the different lipid classes for the lipid-protein interaction. The fractions of motionally restricted lipid in the thylakoid membrane are 0.36, 0.39, and 0.53, for the spin-labeled monogalactosyldiacylglycerol, phosphatidylcholine, the phosphatidylglycerol, respectively. Spin-labeled monogalactosyldiacylglycerol exhibits very little preferential interaction over phosphatidylchline, which suggests that part of the role of monogalactosyldiacylglycerol in thylakoid membranes is structural, as is the case for phosphatidylcholine in mammalian membranes. Spin-labeled phosphatidylglycerol shows a preferential interaction over the corresponding monogalactosyldiacylglycerol and phosphatidylcholine analogues, in contrast to the common behavior of this lipid in mammalian systems. This pattern of lipid selectivity is preserved in both the photosystem 1 and photosystem 2 enriched subthylakoid membrane fractions.

Chemical Phenomena↗
PubMed1989

Outcomes of cardiopulmonary resuscitation in the elderly.

STUDY OBJECTIVE: To determine the success rate of cardiopulmonary resuscitation in the elderly and to define characteristics of elderly patients for whom cardiopulmonary resuscitation is effective. DESIGN: Retrospective chart review. SETTING: Five Boston health-care institutions: two acute-care hospitals; two chronic-care hospitals; and one long-term-care institution. PATIENTS: Five hundred and three consecutive patients aged 70 and over who received cardiopulmonary resuscitation. MEASUREMENTS AND MAIN RESULTS: Of 503 patients, 112 (22%) survived initially but only 19 (3.8%) survived to hospital discharge. The poorest outcomes were for patients with unwitnessed arrests (1 of 116 survived), terminal arrhythmias such as asystole and electromechanical dissociation (1 of 237 survived), and patients with cardiopulmonary resuscitation lasting more than 15 minutes (1 of 360 survived). Only 2 (0.8%; CI, 0.0% to 2.0%) of 244 patients with out-of-hospital cardiopulmonary arrests left the hospital alive. Of 259 patients with in-hospital arrests, 17 (6.5%; CI, 3.4% to 9.6%) survived to discharge. Most survivors had ventricular arrhythmias and were resuscitated within minutes. Initial survivors with either impaired consciousness or functional impairment after the arrest had significantly worse chances of survival than patients without these impairments. CONCLUSION: Cardiopulmonary resuscitation is rarely effective for elderly patients with cardiopulmonary arrests that are either out-of-hospital, unwitnessed, or associated with asystole or electromechanical dissociation.

Age Factors↗
PubMed1989

Hydrophobic interactions via mutants of Escherichia coli dihydrofolate reductase: separation of binding and catalysis.

The strictly conserved residue leucine-54 of Escherichia coli dihydrofolate reductase forms part of the hydrophobic wall which binds the p-aminobenzoyl side chain of dihydrofolate. In addition to the previously reported glycine-54 mutant, isoleucine-54 and asparagine-54 substitutions have been constructed and characterized with regard to their effects on binding and catalysis. NADP+ and NADPH binding is virtually unaffected with the exception of a 15-fold decrease in NADPH dissociation from the Gly-54 mutant. The synergistic effect of NADPH on tetrahydrofolate dissociation seen in the wild-type enzyme is lost in the isoleucine-54 mutant: little acceleration is seen in tetrahydrofolate dissociation when cofactor is bound, and there is no discrimination between reduced and oxidized cofactor. The dissociation constants for dihydrofolate and methotrexate increase in the order Leu less than Ile less than Asn less than Gly, varying by a maximum factor of 1700 for dihydrofolate and 6300 for methotrexate. Despite these large changes in binding affinity, the hydride transfer rate of 950 s-1 in the wild-type enzyme is decreased by a constant factor of ca. 30 (2 kcal/mol) regardless of the mutant. Thus, the contributions of residue 54 to binding and catalysis appear to have been separated.

Binding Sites↗
PubMed1989

Synthesis of the major oil-body membrane protein in developing rapeseed (Brassica napus) embryos. Integration with storage-lipid and storage-protein synthesis and implications for the mechanism of oil-body formation.

The synthesis of the major protein and lipid storage reserves during embryogenesis in oilseed rape (Brassica napus L., cv. Mikado) has been examined by biochemical, immunological and immunocytochemical techniques. The mature seeds contained about 45% (w/w) storage oil and 25% (w/w) protein. There were three major seed protein components, i.e. about 40-50% total protein was cruciferin, 20% was napin and 20% was a 18 kDa hydrophobic polypeptide associated with the proteinaceous membrane surrounding the storage oil bodies. Embryogenesis was divided into four overlapping stages with regard to the synthesis of these storage components: (1) for the first 3 weeks after flowering, little, if any, synthesis of storage components was observed; (2) storage-oil synthesis began at about week 3, and maximal rates were from weeks 4 to 7; (3) synthesis of the soluble storage proteins cruciferin and napin started at week 6 and rates were maximal between weeks 8 and 11; (4) the final stage was the synthesis of the 19 kDa oil-body polypeptide, which started at weeks 8-10 and was at a maximal rate between weeks 10 and 12. The synthesis of the 19 kDa oil-body protein therefore occurred independently of the synthesis of the soluble seed storage proteins. This former synthesis did not occur until shortly before the insertion of the 19 kDa polypeptide into the oil-body membrane. No evidence was found, either from sucrose-density-gradient-centrifugation experiments or from immunogold-labelling studies, for its prior accumulation in the endoplasmic reticulum. Conventional and immunogold-electron-microscopic studies showed that oil bodies were synthesized in the early to middle stages of seed development without a strongly electron-dense membrane. Such a membrane was only found at later stages of seed development, concomitantly with the synthesis of the 19 kDa protein. It is proposed that, in rapeseed embryos, oil bodies are initially formed with no proteinaceous membrane. Such a membrane is formed later in development after insertion by ribosomes of the hydrophobic 19 kDa polypeptide directly into the oil bodies.

Allergens↗
PubMed1989

Pressures in the distal radioulnar joint: effect of surgical procedures used for Kienbock's disease.

Radial shortening and ulnar lengthening are two accepted surgical methods for treating Kienbock's disease. The effect of these procedures on the pressure within the distal radioulnar joint between the ulnar head and the sigmoid notch of the radius was experimentally evaluated in six fresh cadaver forearms. Radical shortening and ulnar lengthening led to increased pressure at the distal radioulnar articulation and caused shifting of the location of the center of pressure distally within the sigmoid notch. Radial displacement of the distal radial fragment at the time of radial shortening, however, decreased the peak pressures. Based on these experimental data, ulnar lengthening and radial shortening can be expected to alter the normal biomechanics of the distal radioulnar joint.

Aged↗
PubMed1989

An immunologically related family of apolipoproteins associated with triacylglycerol storage in the Cruciferae.

The major apolipoproteins associated with oil-storage bodies have been isolated from the mature seeds of six different species of the family Cruciferae. The apolipoproteins were all of molecular mass 19-20 kDa. They were highly abundant in mature seed tissue, accounting for up to 20% total seed proteins, and were localized exclusively on the membranes of oil-storage bodies. Antibodies were raised in rabbits and mice against the six purified apolipoproteins. In each case, the antibodies specifically recognized 19-20 kDa polypeptides on immunoblots of total seed proteins from 15 different species of the Cruciferae. The extent of the immunological cross-reactivity among the six purified seed apolipoproteins of the Cruciferae was investigated quantitatively using enzyme-linked immunosorbent assay. Very high levels of cross-reactivity were obtained, in contrast to a complete lack of cross-reactivity observed when the major seed apolipoprotein of a non-crucifer, Glycine max, was assayed. Peptide mapping studies showed that the different crucifer seed apolipoproteins gave rise to similar proteolytic cleavage products following treatment with Staphylococcus aureus V8 protease, Lysobacter enzymogenes Lys-C endoprotease, and trypsin. The patterns of immunogenic proteolytic cleavage products of the different apolipoproteins were also similar. We propose that there is a family of abundant 19-20 kDa apolipoproteins in mature seeds of oil-bearing Cruciferae. These apolipoproteins are all major components of the membranes of oil-storage bodies. The apolipoproteins are therefore very closely related with respect to their structure, function, and immunological properties.

Antibodies↗
PubMed1989

Inhibition of Neutral Lipase from Castor Bean Lipid Bodies by Coenzyme A (CoA) and Oleoyl-CoA.

The neutral lipase (EC 3.1.1.3) in lipid body membranes isolated from the endosperm of 4 day old castor (Ricinus communis L.) seedlings catalyzes the hydrolysis of [(14)C]trioleoylglycerol, releasing [(14)C]oleic acid for up to 4 hours. However, the addition of Mg-ATP and coenzyme A (CoA), which are present in the cytoplasm of plant cells, caused a progressive inhibition of the neutral lipase such that after 15 minutes, release of [(14)C]oleic acid was almost undetectable. A fatty acyl CoA synthetase was found in the lipid body membrane which converts [(14)C]oleic acid produced from the lipase reaction to [(14)C]oleoyl-CoA under these conditions. The concentration of free oleoyl-CoA in the reaction mixture when the lipase was inhibited by 50% was calculated to be about 21 micromolar. It was found that a mixture of exogenously added oleoyl-CoA and CoA was most effective in causing lipase inhibition. Little inhibition of lipase was detected in the presence of CoA alone. It is possible that this effect is important In vivo in coordinating lipase activity with fatty acid oxidation.

Journal Article↗
PubMed1988

Characterization of lipases from the lipid bodies and microsomal membranes of erucic acid-free oilseed-rape (Brassica napus) cotyledons.

Lipase (triacylglycerol lipase, EC 3.1.1.3) activities have been reported previously in the lipid body and microsomal membranes of oilseed-rape (Brassica napus cv. Andor) seedlings, but conflicting data made it unclear whether there was one lipase in the lipid bodies, with the microsomal activity being attributable to fragments of lipid-body membrane, or if there were two separate lipase activities. In the present study, simultaneous characterization of the lipases under identical conditions showed they differed substantially in their pH-activity curves, kinetics and substrate specificities. (1) The kinetics of the microsomal lipase showed that the rate of lipolysis reached a plateau at concentrations above 5 mM, whereas the lipid-body lipase showed a linear increase in activity with substrate concentration up to 20 mM. (2) The pH optimum of the microsomal lipase was 7.5, whereas that of the lipid-body lipase was 9.0. The microsomal lipase was greatly inhibited at higher pH values, whereas the lipid-body lipase was much less affected. (3) Activity of the microsomal lipase was greatly diminished when substrates with longer chain length were used, and enhanced 4-fold if the substrates contained a single double bond. The lipid-body lipase was relatively unaffected by the type of fatty acid in the triacylglycerol. (4) SDS/polyacrylamide-gel electrophoresis showed little or no cross-contamination of the lipid-body and microsomal fractions. (5) The microsomal lipase activity comprised 75-80% of the total extracted.

Brassica↗
PubMed1988

Balloon valvuloplasty for pulmonic valve stenosis--two-year follow-up: hemodynamic and Doppler evaluation.

The purpose of this investigation was to evaluate the efficacy, technique, and follow-up results of balloon dilation angioplasty for valvular pulmonary stenosis. Percutaneous dilation was performed on 63 patients with pulmonary stenosis (ages 3 months to 76 years, mean = 4.3 years). In 43 patients, a single balloon was used; in 20 patients two balloons were used simultaneously. The pressure gradient across the pulmonary valve was determined with right ventricular and main pulmonary artery catheters. Pressure gradients simultaneously were estimated by continuous wave Doppler (CWD) during catheterization. The peak systolic ejection gradient was obtained by both techniques both pre- and postangioplasty. There was excellent linear correlation between the simultaneous catheter pressure gradient and the pressure gradient estimated by Doppler (r = 0.99). Follow-up pressure gradient estimations by Doppler echocardiogram were obtained in 30 patients between 6 months and 30 months postcatheterization (mean = 13 months). The mean preangioplasty gradient of 64 mm Hg (range 30-160 mm Hg) was reduced to 22 mm Hg (range 2-31 mm Hg). A significant reduction of transvalvular gradient (52-95%, mean 68%) occurred in each patient. A linear correlation was found between the predilation gradient and the pressure gradient drop (r = 0.92). Mean follow-up gradient by Doppler was 20 mm Hg (range 0-31 mm Hg), and there was no significant difference between these gradients and the postdilation gradient. No important complications were noted. These data confirm that balloon dilation angioplasty for valvular pulmonary stenosis is safe and effective, and suggest that stenosis does not recur.

Adolescent↗
PubMed1988

Continuous wave Doppler cardiac output: use in pediatric patients receiving inotropic support.

Doppler estimates of cardiac output have been shown to correlate closely with invasive measurement of cardiac output in hemodynamically stable adults and children. However, this method has not been validated in hemodynamically unstable pediatric patients. To assess the accuracy of continuous wave Doppler echocardiography in pediatric patients with unstable hemodynamics, we performed 27 simultaneous Doppler and thermodilution comparisons in 12 pediatric patients receiving inotropic support and afterload-reducing agents. Doppler cardiac output was calculated using aortic diameter measured from long-axis two-dimensional echocardiograms at three different sites: the aortic valve anulus, the aortic root at the sinuses of Valsalva, and the ascending aorta. For all measurements, there was a close correlation between Doppler and thermodilution techniques. However the site of measurement of aortic diameter had a significant impact on the strength on the correlation and the variability between Doppler and thermodilution. The best correlation and least variability were obtained using the aortic valve anulus diameter (r = 0.94). On serial determinations, percent change in Doppler stroke volume correlated well with thermodilution stroke volume (r = 0.87) and was useful in detecting both direction and magnitude of change in thermodilution stroke volume. Despite the administration of positive inotropic and afterload-reducing agents, Doppler cardiac output is a useful method for estimating cardiac output in hemodynamically unstable pediatric patients.

Adolescent↗
PubMed1988

A highly active soluble diacylglycerol synthesizing system from developing rapeseed, Brassica napus L.

The subcellular distribution of the enzymes of triacylglycerol biosynthesis has been studied in developing oilseed rape. All in vitro enzymatic activities from oleoyl-CoA to triacylglycerol were sufficient to account for the known rate of oleate deposition in triacylglycerol in vivo. The enzymatic activities from oleoyl-CoA to diacylglycerol preferentially were localized in a 150,000 g supernatant fraction, while the diacylglycerol acyl-transferase mostly was associated with the microsomal (20,000 g pellet and 150,000 g pellet) and oil-body fractions. The soluble (150,000 g supernatant) fraction rapidly incorporated oleate from [1-14C]oleoyl-CoA into diacylglycerol with rates of 40 nm min-1 g-1 FW at 20 microM oleoyl-CoA. The pH optimum was 7.5-9.0, and normal saturation kinetics were seen with oleoyl-CoA; the S0.5 was about 32 microM. Exogenous acyl acceptors, such as glycerol 3-phosphate, lysophosphatidic acid and lysophosphatidyl-choline stimulated oleate incorporation into diacylglycerol. The detergents Triton X-100 and sodium cholate inhibited diacylglycerol formation at concentrations in the region of their critical micellar concentration, while n-octyl-beta, D-glyco-pyranoside had no effect, even at high concentration. The significance of these findings for the mechanism of oil-body formation in developing oilseeds is discussed.

Brassica↗
PubMed1988

Surgery without angiography for neonates with aortic arch obstruction.

Traditional diagnostic assessment of the neonate and infant with congenital abnormalities of the aorta causing left ventricular outflow tract obstruction has required catheterization and angiography. However, these patients frequently present critically ill and invasive diagnostic procedures may be associated with significant risks. Two-dimensional echocardiography has been used for aiding diagnosis of aortic arch abnormalities, but there has been little information concerning its use as the definitive imaging technique for preoperative assessment. We reviewed neonates who required urgent surgery for congenital obstruction of the aorta. The diagnosis was made using two-dimensional echocardiographic imaging and Doppler techniques for hemodynamic assessment in lieu of catheterization and angiography in all. Anatomic detail provided by the noninvasive approach was both sensitive and specific in guiding surgery in all but one case. We conclude that echocardiography eliminates the need for invasive preoperative diagnostic procedures in selected neonates with congenital aortic arch obstruction.

Aorta, Thoracic↗
PubMed1988

Results of balloon valvuloplasty in typical and dysplastic pulmonary valve stenosis: Doppler echocardiographic follow-up.

To assess the usefulness of balloon valvuloplasty in patients with a dysplastic pulmonary valve, the files of 36 patients (aged 1 day to 18.5 years) who had two-dimensional echocardiography before and continuous wave Doppler echocardiography late after balloon valvuloplasty (balloon diameter greater than or equal to 20% anulus diameter) were reviewed. Results of relief of pulmonary stenosis were graded by catheter gradient in the catheterization laboratory and compared with Doppler echocardiographic findings at follow-up. There were 32 patients with typical pulmonary stenosis and 4 with a dysplastic valve. In the 32 patients with typical pulmonary stenosis, transvalvular gradient changed from a mean of 67 +/- 32 to 20 +/- 20 mm Hg (p less than 0.0001, mean reduction 72.6%). The gradients at follow-up by Doppler echocardiography averaged 20 mm Hg including 15 that increased, 3 that were unchanged and 14 that decreased. Only 3 (9%) of 32 patients had a gradient greater than 25 mm Hg at follow-up and only one gradient was greater than 35 mm Hg. All four patients with a dysplastic valve had a gradient that decreased with valvuloplasty from a mean of 85 +/- 33 to 33 +/- 20 mm Hg (p less than 0.05); gradient reduction in this group ranged from 40 to 85% (mean 57.5%). The gradient at follow-up increased in three of these four patients and decreased in one (the only late gradient less than 25 mm Hg). Late gradient was less than 35 mm Hg in two of the four patients and was reduced by 43 and 57%, respectively, in the other two.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Partial excision of the triangular fibrocartilage complex.

A cadaver model was used to evaluate the effect of partial excision of the triangular fibrocartilage complex (TFCC) on ulnar wrist kinetics. Excision of less than two thirds of the horizontal portion of the TFCC was found to have no statistical effect experimentally on forearm axial load transmission. This data supports, from a biomechanical standpoint, partial excision of the central portion of the TFCC--a procedure advocated clinically by some for treatment of a central TFCC perforation.

Biomechanical Phenomena↗
PubMed1988

Prostate localization for the treatment planning of prostate cancer: a comparison of two techniques.

Two methods for localizing prostatic tissue for radiotherapy treatment planning are compared. The first method, using placement of gold "seed" in the urogenital diaphragm, is shown by CT scanning to accurately mark the prostatic apex. The other technique, in use at the Cross Cancer Institute for the past 18 months, employs a more rapid, less invasive method of retrograde contrast instillation. Both techniques yield equally precise localization of the prostate for subsequent treatment planning.

Gold↗