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D H Russell

Publications and source records attributed to D H Russell.

At least 55 records · Page 3Linked to original sources
PubMed1995

Protective effect of a 21-aminosteroid against hemorrhage-induced ischemia-reperfusion injury in the rat stomach: role of lipid peroxidation.

We investigated the role that lipid peroxidation plays in a hemorrhage-induced ischemia-reperfusion model of gastric injury. Rats were pretreated with an inhibitor of this process, a 21-aminosteroid (U-74389G, 10 mg/kg), or an appropriate control solution intravenously 15 min prior to 20 min of ischemia, followed by 20 min of reperfusion. Results indicated that U-74389G pretreatment significantly attenuated gastric damage compared with corresponding control animals (19.8 vs. 176.8 mm2, p < .001). Enaldehyde levels (picomoles/mg protein), a biochemical index of lipid peroxidation, paralleled these injury findings (12 vs 960, p < .001). Histologically, U-74389G pretreatment almost completely prevented gastric injury compared to control stomachs. Additional studies revealed that lipid peroxidation preceded the formation of gastric damage, and injury occurred predominantly during reperfusion, because animals subjected to ischemia alone without reperfusion failed to develop appreciable injury or enhanced enaldehyde formation. Further, if U-74389G was given intravenously after ischemia, but prior to reperfusion, gastric injury and enaldehyde formation were similarly attenuated. Our findings are consistent with the hypothesis that lipid peroxidation likely plays an important role in hemorrhage-induced ischemia-reperfusion injury to the stomach.

Animals↗
PubMed1994

Detection of high-mass biomolecules in Fourier transform ion cyclotron resonance mass spectrometry: theoretical and experimental investigations.

A simple modification to an ion cyclotron resonance (ICR) cell for detection of high-mass ions with large spatial and kinetic energy distributions is described. The modification consists of a copper wire positioned inside the ICR cell running parallel to the magnetic field lines. The wire acts as an ion guide to position the ions at the exact center of the ion cell. Ion trajectories are calculated using SIMION, and the predictions based on the calculations are compared with the experimental results. The results presented in this paper show that the ion-guide ICR cell can be used to detect singly charged biomolecule ions of up to 157,000 Da.

Cyclotrons↗
PubMed1994

Mass measurement accuracy of matrix-assisted laser desorbed biomolecules: a Fourier-transform ion cyclotron resonance mass spectrometry study.

The use of binary matrices and internal calibrants to improve the mass measurement accuracy in matrix-assisted laser desorption ionization (MALDI) with Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry is described. Binary matrices enhance the analyte ion yield and enable a complete MALDI-FTICR mass spectrum to be obtained from a single laser shot. The advantage of single-laser-shot data acquisition is that it eliminates line-broadening due to shot-to-shot frequency variations. It is shown that unresolved product ions, mainly due to loss of H2O and/or NH3, shift the centroid of an unresolved multi-component peak. A mass measurement accuracy of 12 ppm was obtained for the bovine insulin [M+H]+ ion using melittin as an internal calibrant.

Animals↗
PubMed1994

Gallbladder contractility in aspirin- and cholesterol-fed prairie dogs.

BACKGROUND/AIMS: Whether aspirin prevents cholesterol gallstone formation is controversial. This study aimed to investigate this issue and determine the depression of gallbladder smooth muscle contractility associated with cholesterol feeding in the prairie dog. METHODS: Prairie dogs were divided into four subgroups. Animals were fed control or 1.2% cholesterol diet and treated with placebo or aspirin for 2 weeks. The presence of crystals and stones was determined, and contractile force in response to cholecystokinin octapeptide (CCK-8) of gallbladder muscle strips was measured. RESULTS: Maximal stress of 2.66 +/- 0.23 x 10(4) N/m2 was measured in muscle strips from animals on control diet. Maximal stress was significantly lower in strips from animals on high-cholesterol diet, being 1.49 +/- 0.16 x 10(4) N/m2 with placebo and 1.62 +/- 0.23 x 10(4) N/m2 with aspirin. The difference in maximal stress between aspirin-treated and placebo-treated animals was not significant. Although none of the animals on control diet had crystals or stones, all animals on the high-cholesterol diet, whether receiving placebo or aspirin, had crystals in the bile, and more than 65% had cholesterol stones. CONCLUSIONS: Aspirin has no effect on stone formation, nor does it prevent the decrease in contractility despite a profound decrease in endogenous gallbladder prostanoid synthesis.

Animals↗
PubMed1994

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of paclitaxel and related taxanes.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been demonstrated for the analysis of Taxus brevifolia extracts. The detection limit for the taxanes contained therein is estimated at 1 pmol using the matrix 4-nitroaniline at a matrix-to-analyte molar ratio of 100:1. Acquisition and calibration of the mass spectral data requires less than 5 min. The [M+H]+, [M+Na]+, and [M+K]+ ions provide mol wt confirmation and structurally significant fragment ions indicative of the various substituent groups located on the diterpene skeleton are formed.

Bridged Bicyclo Compounds↗
PubMed1993

Reproducibility and quantitation of matrix-assisted laser desorption ionization mass spectrometry: effects of nitrocellulose on peptide ion yields.

We have observed that using nitrocellulose in sample preparation for matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometry increases the yield of peptide [M+H]+ ions. Addition of nitrocellulose also provides improvement in sample-to-sample reproducibility of MALDI ion yield and improves the precision of peptide quantitation. Mass spectrometry and optical microscopy results suggest that the nitrocellulose modifies the crystallization of matrix/analyte solution to allow more even coverage over the sample surface.

Amino Acid Sequence↗
PubMed1993

Reversibility of pancreatitis after temporary pancreaticobiliary duct obstruction in rats.

Pancreaticobiliary duct (PBD) obstruction in rats is associated with hyperamylasemia, hyperlipasemia, pancreatic edema, inflammation, and subcellular enzyme redistribution in < 24 h. The purpose of our study was to investigate whether these changes are reversible. A catheter was placed in the distal PBD and tunneled subcutaneously to the nape of the neck where flow could be controlled. The distal end was secured into the duodenum. Animals were divided into five groups: Group I, free flow for 48 h; Group II, catheter obstruction for 24 h; Group III, obstruction for 48 h; Group IV, obstruction for 24 h followed by free flow for 24 h; Group V, obstruction for 24 h followed by free flow for 48 h. After killing, amylase and lipase were measured, pancreatic water content was determined, and morphologic damage was graded blindly for edema, inflammation, acinar dilatation, and cell injury. Both groups with temporary obstruction showed less morphologic damage than groups studied directly after obstruction. Pancreatic water content was lower after reversal than after a 48-h obstruction. Serum amylase and lipase peaked after 24-h obstruction and then dropped with either treatment. We conclude that continuous obstruction causes progressive pancreatic damage, whereas releasing the obstruction results in reversal of early structural and functional changes.

Acute Disease↗
PubMed1993

Gastric damage caused by acidified ethanol: role of molecular HCl.

This study was undertaken to test the hypothesis that an increase in the concentration of molecular HCl in ethanolic solutions is at least partly responsible for the severity of damage seen with acidified ethanol. To accomplish this goal, we studied the synergistic relationship of HCl and ethanol by holding ethanol constant at 50% (vol/vol) and varying the acid concentration. In another experiment, acid concentration was held constant at 150 mM HCl, and the percentage of ethanol was varied. Our hypothesis was also tested by substituting sulfate for chloride to form H2SO4, a nonpermeant molecular acid. Results of our studies clearly showed that substitution of sulfate for chloride greatly reduced gastric damage, supporting the hypothesis that diffusion of molecular HCl is contributing to the damage by acidifying cells. In all cases, acidified ethanol solutions using HCl were more damaging than the individual components alone, and the severity of the damage caused by 50% ethanol was noted to be dependent on the concentration of HCl. We therefore conclude that the severity of acidified ethanol damage is dependent on cellular acidification caused by diffusion of molecular HCl.

Animals↗
PubMed1993

Reevaluation of the linkage between acute hemorrhagic shock and bacterial translocation in the rat.

The present study was undertaken to determine the conditions under which acute periods of hemorrhagic shock induce bacterial translocation. Rats (at least six per group) were anesthetized intraperitoneally with the barbiturate, pentobarbital (50 or 65 mg/kg), or the inhalation anesthetic methoxyflurane. Following anesthesia, the femoral artery was catheterized, from which blood was withdrawn to maintain a mean arterial blood pressure of 30 mmHg for 30, 60, or 90 min, followed by reinfusion of shed blood. Instrumented, but nonshocked animals served as controls. Rats were sacrificed at 0, 2, or 24 hr postshock, and quantitative bacterial cultures of the mesenteric lymph node complex (MLN), liver, and spleen were made. Within groups, the effects of heparinization were also determined. In pentobarbital-treated animals, regardless of the extent of heparinization, consistent translocation to both MLN and distant organs occurred when shock was prolonged for 90 min, and assessment of translocation was made 24 hr after reinfusion of shed blood. Furthermore, a mortality rate of approximately 30% was found in rats subjected to this protocol. The magnitude of translocation was less consistent, and did not differ from that in sham shock controls, under other conditions of shock and evaluation. In rats anesthetized with methoxyflurane, no mortality occurred, and no statistical significance between the incidence or degree of translocation in shocked animals vs. sham shock controls could be demonstrated, regardless of the shock protocol. In additional studies, effects of these anesthetics on intestinal morphology and superior mesenteric arterial (SMA) flow in the context of hemorrhagic shock were assessed.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1992

Laser desorption studies of high mass biomolecules in Fourier-transform ion cyclotron resonance mass spectrometry.

Matrix-assisted laser desorption ionization is used to obtain Fourier-transform ion cyclotron resonance mass spectra of model peptides (e.g., gramicidin S, angiotensin I, renin substrate, melittin, and bovine insulin). Matrix-assisted laser desorption ionization yields ions having appreciable kinetic energies. Two methods for trapping the high kinetic energy ions are described: (i) the ion signal for [M+H]+ ions is shown to increase with increasing trapping voltages, and (ii) collisional relaxation is used for the detection of [M+H]+ ions of bovine insulin.

Angiotensin I↗
PubMed1992

Mass spectrometry.

Explore the source record for details and available documents.

Carbohydrates↗
PubMed1991

Prolactin-provoked alterations of cytosolic, membrane, and nuclear protein kinase C following partial hepatectomy.

The adenohypophyseal polypeptide hormone prolactin is a potent liver mitogen, stimulating cell cycle progression, an effect that appears coupled to increasing protein kinase C activity in membrane and nuclear fractions. Here, we examine whether hepatocyte proliferation, stimulated by partial hepatectomy, is associated with altered serum prolactin or protein kinase C activation. Within 5-15 min of liver resection, serum prolactin concentrations elevate significantly. Protein kinase C activity in hepatic cytosol decreases significantly, and membrane and nuclear PKC activity increase by 30 min. Hypophysectomy prior to partial hepatectomy abrogates any effect of liver resection on protein kinase C activation in the hepatic remnant. Based upon these data, it is suggested that the rapid increase in serum prolactin seen after partial hepatectomy may be linked to protein kinase C activation, which in turn stimulates the hepatic proliferative response that is essential for hepatic regeneration.

Animals↗
PubMed1991

Triphasic response of prostacyclin production in rabbit thoracic aorta in early atherosclerosis.

Atherosclerosis was induced in male rabbits by administration of a 2% cholesterol diet for up to 18 weeks. The animals were assessed for aortic microsomal prostanoid synthesis, morphologic assessment and serum cholesterol levels. Serum levels of cholesterol increased from control values of 84 +/- 9 ng/dl to 1632 +/- 227 ng/dl at 2 weeks (20-fold increase), and 4859 +/- 829 ng/dl at 9 weeks (57-fold increase). Aortic microsomal prostacyclin synthesis fell significantly at 2 weeks of cholesterol feeding which predated the morphologic appearance of atherosclerotic plaque in the 7 week group. Aortic microsomal PGI2 synthesis significantly increased by 7 weeks and did not fall until the 18 week group when a highly significant increase in aortic plaque developed. These findings suggest a triphasic response of aortic PGI2 synthesis with the development of early atherosclerosis. Phase one is a fall in aortic PGI2 synthesis which predates the appearance of plaque. In phase 2, a significant rise in aortic PGI2 with the appearance of plaque could represent compensation of aortic endothelium to prevent further plaque development. In phase 3, decreased aortic PGI2 could indicate replacement of normal endothelium by atherosclerotic plaque.

Animals↗
PubMed1991

Identification and characterization of a prolactin-like polypeptide synthesized by mitogen-stimulated murine lymphocytes.

Previously, we have reported that concanavalin A (Con A)-stimulated murine splenocytes synthesize and secrete into the medium a substance with prolactin (PRL)-like properties. Western blot analysis of the culture medium of Con A-stimulated murine splenocytes identified a PRL-like polypeptide (Ly-PLP) with an apparent molecular weight (Mr) of 46 kd. Rabbit anti-rat PRL antibody (S-9, NIDDK) was used for immunostaining. Specificity was proved by the absence of a band in properly preabsorbed primary and secondary antibodies. Electroeluted Ly-PLP enhanced the mitogenic response of lymphocytes to Con A. In situ hybridization analysis of dispersed lymphocyte smears demonstrated the presence of an mRNA that hybridized with a rat PRL cDNA probe. The size of the mRNA species was 1.4 kb on Northern blot analysis. Two-dimensional peptide map analysis of pituitary PRL and Ly-PLP showed three peptides with identical migration characteristics. Western blot analysis of lymphocyte culture medium following Con-A-affinity column treatment provided evidence that the Ly-PLP was a non-glycoprotein. Therefore, we conclude that Ly-PLP represents a structural variant of pituitary-PRL (Pit-PRL), and provide evidence to strongly suggest that it is a novel lymphokine.

Animals↗
PubMed1990

Vasoactive intestinal peptide (VIP) activation of nuclear protein kinase C in purified nuclei of rat splenocytes.

We have examined the actions of vasoactive intestinal peptide (VIP) and certain other known immune modulators on a nuclear pool(s) of protein kinase C (PKC) in isolated rat splenocyte nuclei. Rat splenocyte nuclei pure by enzymatic and electron microscope criteria demonstrated a time- and concentration-dependent activation of nuclear PKC (nPKC) by VIP. A biphasic pattern of three bell-shaped curves was observed with peak phosphorylation at 10(-15), 10(-9) and 10(-6)M VIP. The phosphorylation of endogenous nuclear substrates was characterized as a PKC-mediated event by use of three known PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), sphingosine, and staurosporine, which produced similar phosphate incorporation measurements. Also, this activity was blocked with the addition of a monoclonal antibody to PKC. Inhibitors of the ability of VIP to activate nPKC included somatostatin, 8-bromo-cAMP, peripheral benzodiazepine receptor modulators, and the PKC inhibitors, sphingosine and staurosporine. These data have direct relevance to our knowledge of cell-mediated immunity.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1990

Prolactin and known modulators of rat splenocytes activate nuclear protein kinase C.

Prolactin (PRL) and other trophic factors rapidly activate a nuclear pool(s) of protein kinase C (nPKC) in purified splenocyte nuclei. The PRL also enhanced [2-3H]glycerol incorporation into nuclear mono- and triacylglycerol. An assay was devised which not only probed the ability of the hormone to activate protein kinase C (PKC) but also demonstrated the presence of nuclear substrates. Using this methodology, a biphasic concentration-response curve to PRL was observed. Heterologous species of PRL and various growth factors also activated nPKC. The PRL-induced nPKC stimulation was antagonized by various immunomodulators, G protein-coupling inhibitors, PKC inhibitors, a calmodulin inhibitor, and a peripheral benzodiazepine agonist and antagonist. A monoclonal antibody to PKC, anti-rat PRL antiserum and a monoclonal anti-rat PRL receptor antibody antagonized PRL-induced PKC-dependent nuclear phosphorylation, further implicating nPKC and a PRL receptor-mediated activation process. Nuclear PKC may be a major target for trophic regulation in response to both positive and negative growth signals.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

The HIV protein, GP120, activates nuclear protein kinase C in nuclei from lymphocytes and brain.

Nuclear pool(s) of protein kinase C (PKC) may be a common target for hormones and growth factors which affect the trophic state of cells. The data presented demonstrate a time and dose-dependent activation of nuclear PKC by the HIV coat protein, gp120, in isolated nuclei from rat spleen and hippocampus. This gp120-stimulated PKC response was blocked by specific PKC inhibitors, a monoclonal antibody to PKC, and a monoclonal antibody directed against the murine T4 analog, L3T4. It is suggested that the gp120 interaction with the nuclear trophic factor-PKC system may impair normal gene expression, and thus result in the clinical symptoms associated in AIDS infection.

Alkaloids↗