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At least 739 records · Page 41Linked to original sources
PubMed2003

Giant Coster-Kronig transitions and intrinsic line shapes of the anomalous Pd M45VV Auger spectrum of Pd/Ag(100) dilute surface alloys.

The Pd M4VV and M5VV Auger spectra of the 0.1 ML Pd/Ag(100) dilute surface alloy have been measured using Auger-photoelectron coincidence spectroscopy. The M4VV spectrum indicates that Pd 3d(3/2) core holes have a Coster-Kronig decay rate that is approximately 10 times that of Pd metal. Our calculations show that this giant enhancement arises from the local electronic structure of excited Pd atoms at the surface. Anomalous features in the Auger line shape are similar to those seen in dilute bulk PdAg alloys, and these features in the M5VV and M4VV lines are in good agreement with theoretical predictions.

Journal Article↗
PubMed2001

Unusual evolutionary history of the tRNA splicing endonuclease EndA: relationship to the LAGLIDADG and PD-(D/E)XK deoxyribonucleases.

The tRNA splicing endoribonuclease EndA from Methanococcus jannaschii is a homotetramer formed via heterologous interaction between the two pairs of homodimers. Each monomer consists of two alpha/beta domains, the N-terminal domain (NTD) and the C-terminal domain (CTD) containing the RNase A-like active site. Comparison of the EndA coordinates with the publicly available protein structure database revealed the similarity of both domains to site-specific deoxyribonucleases: the NTD to the LAGLIDADG family and the CTD to the PD-(D/E)XK family. Superposition of the NTD on the catalytic domain of LAGLIDADG homing endonucleases allowed a suggestion to be made about which amino acid residues of the tRNA splicing nuclease might participate in formation of a presumptive cryptic deoxyribonuclease active site. On the other hand, the CTD and PD-(D/E)XK endonucleases, represented by restriction enzymes and a phage lambda exonuclease, were shown to share extensive similarities of the structural framework, to which entirely different active sites might be attached in two alternative locations. These findings suggest that EndA evolved from a fusion protein with at least two distinct endonuclease activities: the ribonuclease, which made it an essential "antitoxin" for the cells whose RNA genes were interrupted by introns, and the deoxyribonuclease, which provided the means for homing-like mobility. The residues of the noncatalytic CTDs from the positions corresponding to the catalytic side chains in PD-(D/E)XK deoxyribonucleases map to the surface at the opposite side to the tRNA binding site, for which no function has been implicated. Many restriction enzymes from the PD-(D/E)XK superfamily might have the potential to maintain an additional active or binding site at the face opposite the deoxyribonuclease active site, a property that can be utilized in protein engineering.

Binding Sites↗
PubMed2002

Protein stability indicates divergent evolution of PD-(D/E)XK type II restriction endonucleases.

Type II restriction endonucleases recognize 4-8 base-pair-long DNA sequences and catalyze their cleavage with remarkable specificity. Crystal structures of the PD-(DE)XK superfamily revealed a common alpha/beta core motif and similar active site. In contrast, these enzymes show little sequence similarity and use different strategies to interact with their substrate DNA. The intriguing question is whether this enzyme family could have evolved from a common origin. In our present work, protein structure stability elements were analyzed and compared in three parts of PD-(DE)XK type II restriction endonucleases: (1) core motif, (2) active-site residues, and (3) residues playing role in DNA recognition. High correlation was found between the active-site residues and those stabilization factors that contribute to preventing structural decay. DNA recognition sites were also observed to participate in stabilization centers. It indicates that recognition motifs and active sites in PD-(DE)XK type II restriction endonucleases should have been evolutionary more conserved than other parts of the structure. Based on this observation it is proposed that PD-(DE)XK type II restriction endonucleases have developed from a common ancestor with divergent evolution.

Amino Acid Motifs↗
PubMed1986

Expression of two G-6-PD genes in an XX phenotypic male.

The glucose-6-phosphate dehydrogenase (G-6-PD) gene is located on the X-chromosome. Normal males have a single gene and produce a single G-6-PD type, while normal XX females may be heterozygotes for two different G-6-PD genes. We report the case of a phenotypic male who was found to be heterozygous for two G-6-PD enzymes. Cytogenetic analysis showed that he was a 46,XX male.

Child↗
PubMed2005

Effect of heat treatment on joint properties of laser-welded Ag-Au-Cu-Pd and Co-Cr alloys.

PURPOSE: This study investigated the effect of heat treatment on the strengths of laser-welded cast Ag-Au-Cu-Pd and Co-Cr alloys. MATERIALS AND METHODS: Cast plates of Ag-Au-Cu-Pd (Ag) and Co-Cr (Co) alloys were prepared. After polishing the surfaces to be welded, the plates were matched and butted Ag to Ag (Ag/Ag), Co to Co (Co/Co), and Ag to Co (Ag/Co) and welded using Nd:YAG laser at a pulse duration of 10 ms, spot diameter of 1 mm, and voltage of 200 V. Five specimens were prepared for each experimental condition by bilaterally welding them with five spots. The Ag/Ag, Ag/Co, and control Ag underwent two heat treatments-softening (ST) and hardening (AH). A group of as-cast specimens serving as controls was not given either heat treatment. The failure load and percent elongation were measured at a crosshead speed of 1.0 mm/min. RESULTS: The fracture resistance of Co/Co was similar to that of the control Co, while the fracture resistance of Co/Ag was significantly lower than that of both like alloy pairings for all heat-treating conditions. The control Ag had greater fracture resistance after AH and lower fracture resistance after ST. The AH treatment increased the fracture resistance, and the ST treatment decreased the fracture resistance of both Ag/Ag and Co/Ag, although not significantly. The percentage of elongation appeared to positively correlate with the fracture resistance results. CONCLUSIONS: The results obtained in this study indicated that the age-hardening heat treatment increased the weld strength between the paired Au-Ag-Cu-Pd alloys and between the Au-Ag-Cu-Pd and Co-Cr alloys.

Chromium Alloys↗
PubMed2002

Observation of X-Y chromosomal configuration in spermatocytes of infertile PD strain male rats.

PD strain male rats that carry an autosomal recessive gene, preaxial duplication (gene symbol: pd), are sterile in the homozygous condition (pd/pd) due to a spermatogenic breakdown in the process of spermatogenesis at the spermatocyte and/or spermatid stage(s), although heterozygotes (pd/+) are normal. In this study, pd/pd males were examined for the presence of abnormal association of the sex chromosomes that might lead to spermatogenic breakdown. Light and electron microscopic observations of the chromosomes at meiotic prophase and metaphase in primary spermatocytes revealed several types of abnormal X-Y association and configurations in pd/pd males. However, the incidences of the abnormal configuration were comparable to those in pd/+ males. These results suggest that abnormal X-Y chromosome association in the germ cells is not a significant cause of spermatogenic breakdown in pd/pd males.

Animals↗
PubMed2002

Defective intracellular calcium handling in monocrotaline-induced right ventricular hypertrophy: protective effect of long-term endothelin-A receptor blockade with 2-benzo[1,3]dioxol-5-yl-3-benzyl-4-(4-methoxy-phenyl-)- 4-oxobut-2-enoate-sodium (PD 155080).

We studied the effect of long-term treatment with the oral endothelin (ET) ET(A) antagonist 2-benzo[1,3]dioxol-5-yl-3-benzyl-4-(4-methoxy-phenyl-)-4-oxobut-2-enoate-sodium (PD 155080; PD) on right ventricular intracellular calcium (Ca(2+)(i)) handling and cardiac and pulmonary artery function in control rats and rats with monocrotaline (MCT)-induced right-heart hypertrophy. Rats were given an intraperitoneal injection of either saline (controls; n = 9) or MCT (50 mg/kg; n = 12), resulting in pulmonary hypertension-induced myocardial hypertrophy, or MCT followed by the daily administration of PD (50 mg/kg) for 9 weeks (n = 9). After 9 weeks, right ventricular pressure was measured, and the hearts were removed and perfused in vitro. Right ventricular function and Ca(2+)(i) transients were recorded simultaneously on a beat-to-beat basis using aequorin. Surviving animals in the MCT group (58%) developed significant hypertrophy and had 2-fold higher right ventricular pressure and a prolonged duration of isovolumic contraction that correlated with a similar prolongation of the Ca(2+)(i) transient, indicating a reduced rate of Ca(2+) sequestration in hypertrophy (P < 0.05 versus control). In the PD group, all animals survived, and right ventricular pressure, diastolic relaxation, Ca(2+) transport kinetics, and peak systolic and end-diastolic wall stress were all normalized (P > 0.05 versus control); and pulmonary artery endothelial function was partly restored (P < 0.05 versus MCT and control groups). These results demonstrate for the first time that long-term ET(A) receptor antagonism normalizes myocardial cytosolic Ca(2+) modulation, which may contribute to the antihypertrophic and cardioprotective effect of ET(A) receptor therapy in this model.

Aequorin↗
PubMed2006

Solvent-free oxidation of primary alcohols to aldehydes using Au-Pd/TiO2 catalysts.

The oxidation of alcohols to aldehydes with O2 in place of stoichiometric oxygen donors is a crucial process for the synthesis of fine chemicals. However, the catalysts that have been identified so far are relatively inactive with primary alkyl alcohols. We showed that Au/Pd-TiO2 catalysts give very high turnover frequencies (up to 270,000 turnovers per hour) for the oxidation of alcohols, including primary alkyl alcohols. The addition of Au to Pd nanocrystals improved the overall selectivity and, using scanning transmission electron microscopy combined with x-ray photoelectron spectroscopy, we showed that the Au-Pd nanocrystals were made up of a Au-rich core with a Pd-rich shell, indicating that the Au electronically influences the catalytic properties of Pd.

Journal Article↗
PubMed1992

Comparative in vitro activity of PD 127391, a new fluoroquinolone agent, against susceptible and resistant clinical isolates of gram-positive cocci.

We examined the in vitro activity of PD 127391, an investigational fluoroquinolone antibacterial agent, against staphylococci (including methicillin-resistant Staphylococcus aureus), enterococci (including beta-lactamase-producing and highly gentamicin-resistant isolates), and streptococci. The compound was active against all organisms tested and compared favorably with antimicrobial agents routinely used to treat infections with these organisms. On the basis of MICs for 90% of the strains tested, PD 127391 was 32-fold more active against all staphylococci, 16-fold more active against methicillin-resistant S. aureus, 8-fold more active against all streptococci, and 4-fold more active against all enterococci than ciprofloxacin. PD 127391 was shown to be more active than sparfloxacin, which in turn was shown to be more active than ciprofloxacin, against these gram-positive cocci. PD 127391 shows promise for the treatment of infections with gram-positive cocci, including organisms which are resistant to other commonly used antimicrobial agents.

Anti-Infective Agents↗
PubMed1980

alpha-Thalassaemia and hyperbilirubinaemia in G-6-PD-deficient newborns.

53 newborn infants with both G-6-PD deficiency (29 male hemizygotes and 24 female heterozygotes) and alpha-thalassaemia, and 120 newborn infants with only the enzymatic defect (60 male hemizygotes and 60 female heterozygotes) were studied. 12 of those with both G-6-PD deficiency and alpha=thalassaemia, and 32 of those with only G-6-PD deficiency showed hyperbilirubinaemia. alpha-Thalassaemia does not seem to be implicated in the development of hyperbilirubinaemia in G-6-PD-deficient newborns.

Female↗
PubMed1995

Insulin-mediated changes in PD and glucose uptake after correction of acidosis in humans with CRF.

To test the hypothesis that acidosis contributes to the insulin resistance of chronic renal failure (CRF) and impairs the action of insulin to decrease protein degradation, eight CRF patients were studied using the combined L-[1-13C]leucine-euglycemic clamp technique before (acid) and after (NaHCO3) 4 wk treatment with NaHCO3 (pH: acid 7.29 +/- 0.01 vs. NaHCO3 7.36 +/- 0.01, P < 0.001). Protein degradation (PD) was estimated sequentially from the kinetics of a primed continuous infusion of L-[1-13C]leucine in the basal state and during a hyperinsulinemic euglycemic clamp. Insulin sensitivity was measured during the clamp. The correction of acidosis significantly increased the glucose infusion rate necessary to maintain euglycemia (acid 6.44 +/- 0.89 vs. bicarbonate 7.38 +/- 0.90 mg.kg-1.min-1, P < 0.01) and significantly decreased PD in the basal state (acid 126.4 +/- 8.1 vs. bicarbonate 100.1 +/- 6.9 mumol.kg-1.h-1, P < 0.001). Hyperinsulinemia decreased PD in both studies (acid basal 126.4 +/- 8.1 vs. clamp 96.5 +/- 7.7, P < 0.001; bicarbonate basal 100.1 +/- 6.9 vs. clamp 88.2 +/- 5.5 mumol.kg-1.h-1, P = 0.06), its effect being unaltered by acidosis, with a reduction of 24% before and 12% after the correction of acidosis. In conclusion, acidosis contributes to the insulin resistance of CRF but does not affect the action of insulin on PD.

Acidosis↗
PubMed1993

Central administration of PD 123319 or EXP-3174 inhibits effects of angiotensin II.

Cardiovascular responses to intracerebroventricular angiotensin II (ANG II) were measured in conscious rats, chronically instrumented for the measurement of regional hemodynamics, over 4 consecutive days in the absence and presence of either the AT2 receptor antagonist, PD 123319 (experiment 1), or the AT1 receptor antagonist, EXP-3174 (experiment 2). Intracerebroventricular ANG II had pressor and bradycardic effects, which were associated with marked mesenteric and hindquarters vasoconstriction, and a small transient renal vasoconstriction. Both PD 123319 and EXP-3174, given intracerebroventricularly, abolished the cardiovascular response to intracerebroventricular ANG II, although the profiles of activity of the compounds were different. PD 123319 caused a slowly developing, but remarkably prolonged (1-2 days) inhibition of the effects of ANG II, whereas EXP-3174 caused an immediate inhibition of the effects of ANG II, although responses to ANG II had returned to control levels by the following day. These data suggest that the hemodynamic effects of ANG II may involve concurrent, and interdependent, activation of AT1 and AT2 receptors or that PD 123319 undergoes a unique biotransformation in the brain to some product(s) with AT1 receptor antagonist activity.

Angiotensin II↗
PubMed1977

Origin of electrical PD's in hamster thin ascending limbs of Henle's loop.

Microelectrodes with 2-micronm-tip diameters arranged to record differentially between this ascending limbs (ALH) and ascending vasa recta (AVR), gave values of 1.95 +/- 0.17 mV, ALH positive, in hydropenia with mineral oil bathing the kidney. Average values remained in the range of 1-2 mV when the ALH and AVR values were obtained sequentially, when the kidney was bathed in Ringer solution, when 5-8 Momega Ling-Gerard microelectrodes were used in the ALH, or when the hamsters were in saline diuresis. These results contradict reports of earlier studies with high impedance Ling-Gerard electrodes that the PD was -9 mV, ALH negative. Perfusion of ALH in saline diuresis with solutions of various compositions provided estimates of ionic transport numbers: tNa+ = 0.33 +/- 0.01, tK+ = 0.00 +/- 0.02, tC1- = 0.67 +/- 0.02. When the perfusion solution was designed to have the same Na+, K+, and C1- concentrations as AVR plasma, the PD was 1.36 +/- .20 mV; when ouabain or furosemide were included (10(-5) M), the PD declined 1.35 +/- 0.21 mV and 1.41 +/- 0.28 mV, respectively. The results suggest that active C1- transport is mainly responsible for the PD, but that diffusion potentials can contribute.

Animals↗
PubMed2006

Transplantation outcome in patients on PD and HD.

In the past, peritoneal dialysis (PD) has been considered a second choice dialysis modality for many aspects and that negative attitude has been extended also to possible negative effects on renal transplantation. In the last years, many papers have faced the question whether PD could attain similar results in renal transplantation as hemodialysis and there is sufficient evidence to answer that question. On the short time after transplantation, patients coming PD have lower prevalence of delayed graft function than hemodialysis patients, but higher prevalence of renal vascular thrombosis, above all in children. Incidence of acute graft rejection is not different between the two dialysis modalities. The long-term outcome of renal transplantation is similar in patients coming from either PD or hemodialysis.

Delayed Graft Function↗
PubMed1997

Effect of PD 123319, an AT-2 antagonist, on renal function of the anesthetized dog: comparison with EXP 3174, an AT-1 blocker.

In anaesthetized dogs fed a diet delivering 3.5 mmol NaCl/kg/day, PD 123319 - an angiotensin (AT) II (Ang II) antagonist preferentially bound to AT-2 receptors - was infused into the renal artery for 20 min at 10 microg/kg/min, the lowest effective dose (group 1 dogs). In group 2 dogs, EXP 3174 (30 microg/kg/min) - an AT-1 blocker - was coinfused while, in group 3, EXP 3174 was infused alone. In all groups, during and immediately after infusion, increased sodium, water, and urea excretions from the infused but not from the contralateral kidney were seen. This increase was the same in all groups throughout the infusion; however, in groups infused with EXP 3174, it persisted even after the infusion had been discontinued. Thus, the total amounts of sodium and water excreted during the whole experiment were higher when EXP 3174 was present in the infusion solution than after PD 123319 alone. Moreover, an increase in glomerular filtration rate (creatinine clearance) and renal blood flow (electromagnetic flowmeter) was seen during the infusion period in groups receiving EXP 3174, but not PD 123319. Although it is possible to assume that blockade of AT-1 receptors only is responsible for the changes in excretion rates as PD 123319 is known to interact with these receptors at high concentrations, it is difficult to explain why it does not react with the same receptors responsible for changes in glomerular filtration rate and renal blood flow. An alternative explanation assumes that the excretory changes are due to blockade of both AT-1 and AT-2 receptors; the identity in effect and the absence of additivity of both antagonists could be explained by the existence of a final common pathway leading to the inhibition of the Ang II effect. This pathway could be reached either from AT-1 or AT-2 receptors.

Angiotensin Receptor Antagonists↗
PubMed1976

Glucose-6-phosphate dehydrogenase Ferrara. A new variant of g-6-PD identified in Northern Italy.

A new variant of glucose-6-phosphate dehydrogenase (G-6-PD) has been discovered in Northern Italy, in the district of Ferrara. This variant is characterized by high decrease of red blood cell enzyme activity (less than 5% of normal), high affinity for G-6-P and NADP, increased utilization of deamino-NADP and 2-deoxy-G-6-P, and faster electrophoretic mobility in the buffer systems commonly used for the classification of the G-6-PD variants. The new G-6-PD type was never associated with clinical manifestations in any cases except neonatal jaundice in some of the newborns with this enzyme deficiency. The frequency of the new variant in the Ferrara district indicates that it has probably appeared in this area by mutation some centuries ago. It is suggested that this variant should be named G-6-PD Ferrara.

Electrophoresis, Starch Gel↗
PubMed2001

Failure of a novel balloon-expandable gamma-emitting ((103)Pd) stent to prevent edge effects.

BACKGROUND: Balloon-expandable beta-particle-emitting ((32)P) stents inhibit within-stent neointimal hyperplasia but induce lumen narrowing beyond the stent margins, ie, the so-called "edge effects." METHODS AND RESULTS: We prospectively investigated the performance of novel stents impregnated with the gamma-emitting isotope (103)Pd, designed to reduce edge effects, in 24 rabbits. The stents had a length of 18 mm and were mounted on 20-mm-long delivery balloons for deployment. Angiograms were obtained immediately and 1 month after direct implantation of control and 1-, 2-, and 4-mCi (103)Pd stents into the iliac arteries without predilatation or postdilatation. Late lumen loss was measured with quantitative angiography. Neointimal hyperplasia and vascular remodeling were evaluated by histomorphometry. Late lumen loss was inhibited within (103)Pd stents (control 0.18 mm, 1 mCi 0.08 mm, 2 mCi 0.05 mm, and 4 mCi -0.03 mm, P<0.05 all activities versus control). Conversely, late lumen loss occurred at the edges of (103)Pd stents, correlating with areas of high balloon/artery ratios and vessel overstretch injury. Edge effects were primarily due to neointimal hyperplasia but were also caused by negative vessel remodeling at high stent activities. CONCLUSIONS: Edge effects after implantation of radioisotope stents can occur independently of the isotope chosen for stent impregnation.

Angiography↗
PubMed1986

The relationship between hardness and structure of Pd-Cu-Ga alloys.

Most Pd-Cu-Ga alloys on the market have a yield strength of the order of 1000 MPa, which is too high for an adequate adjustment of the margins of a crown and may promote wear of an opposing natural tooth. In the present work, the structure of a commercial Pd-10 wt% Cu-9 wt% Ga alloy has been shown by means of TEM to consist of thin (5-25 nm) laths with two ordered fct phases with the composition Pd3GaxCu1-x. The c/a ratios in these fct phases are, alternatingly, greater than 1 and less than 1. The transformation of an fcc structure by short atomic movements into the fct structures occurs rapidly below 500 degrees C, as judged by thermal expansion measurements. Such fct structures are likely to provide substantial resistance to dislocation movement and thus a high yield stress and hardness. By adding 6 wt% Ag to the Pd-Cu-Ga alloy and reducing the Ga and Cu content correspondingly, a predominantly fcc structure occurred with nearly no fct laths. At the same time, the hardness was reduced to approximately half the value for the initial Pd-Cu-Ga alloy.

Chemical Phenomena↗