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Biomedical subjects

W D Wagner

Publications and source records attributed to W D Wagner.

At least 55 records · Page 3Linked to original sources
PubMed1990

Macrophage secretory products selectively stimulate dermatan sulfate proteoglycan production in cultured arterial smooth muscle cells.

Arterial dermatan sulfate proteoglycan has been shown to increase with atherosclerosis progression, but factors responsible for this increase are unknown. To test the hypothesis that smooth muscle cell proteoglycan synthesis may be modified by macrophage products, pigeon arterial smooth muscle cells were exposed to the media of either cholesteryl ester-loaded pigeon peritoneal macrophages or a macrophage cell line P388D1. Proteoglycans radiolabeled with [35S]sulfate and [3H]serine were isolated from culture media and smooth muscle cells and purified following precipitation with 1-hexadecylpyridinium chloride and chromatography. Increasing concentrations of macrophage-conditioned media were associated with a dose-response increase in [35S]sulfate incorporation into secreted proteoglycans, but there was no change in cell-associated proteoglycans. Incorporation of [3H]serine into total proteoglycan core proteins was not significantly different (5.2 X 10(5) dpm and 5.5 X 10(5) disintegrations per minute (dpm) in control and conditioned media-treated cultures, respectively), but selective effects were observed on individual proteoglycan types. Twofold increases in dermatan sulfate proteoglycan and limited degradation of chondroitin sulfate proteoglycan were apparent based on core proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Immunoinhibition studies indicated that interleukin-1 was involved in the modulation of proteoglycan synthesis by macrophage-conditioned media. These data provide support for the role of macrophages in alteration of the matrix proteoglycans synthesized by smooth muscle cells and provide a mechanism to account for the reported increased dermatan sulfate/chondroitin sulfate ratios in the developing atherosclerotic lesion.

Animals↗
PubMed1989

Low density lipoprotein interaction with artery derived proteoglycan: the influence of LDL particle size and the relationship to atherosclerosis susceptibility.

An in vitro binding system was used to determine whether increases in LDL particle size and altered LDL chemical composition accompanying increased plasma cholesterol concentrations result in greater association of LDL with artery proteoglycan (PG) and whether the binding is related to atherosclerosis. LDL isolated from hypercholesterolemic atherosclerosis-susceptible White Carneau and resistant Show Racer pigeons was complexed to purified White Carneau pigeon aorta-derived high molecular weight PG under conditions whereby PG monomers were saturated. Using LDL of molecular weight greater than 5.0 x 10(6) daltons from both pigeon breeds, an inverse correlation between LDL size and the number of LDL particles bound per micrograms PG was demonstrated (r = 0.87, P less than 0.01). This relationship was attributed to the increased size of the LDL particle rather than any modification in chemical composition known to occur when LDL size increases, suggesting the major effect was attributed to steric hindrance. White Carneau pigeons with high molecular weight LDL had more severe atherosclerosis and the PG-LDL complexes contained excess cholesterol but no relationship was seen between atherosclerosis and number of LDL complexed. In animals with LDL between 3.6 x 10(6) and 4.8 x 10(6) daltons, considerable variability in PG binding was apparent, but this also was not related to LDL chemical composition. In this group of pigeons, which were all White Carneau, the positive relationship of PG-LDL binding and aorta cholesterol concentration was significant (r = 0.67, P less than 0.05). These results suggest that factors other than chemical composition (perhaps surface charge or apoprotein conformation changes) influence PG-LDL binding and that the assessment of PG-LDL binding is useful in predicting atherosclerosis in animals that do not respond to hypercholesterolemia by increasing LDL size.

Animals↗
PubMed1989

Immunolocalization of proteoglycan types in aortas of pigeons with spontaneous or diet-induced atherosclerosis.

The location of different proteoglycan (PG) types in the developing atherosclerotic lesion was examined by the use of monoclonal antibodies directed toward specific epitopes on distinct PG types. Sections of aorta were prepared from young White Carneau pigeons fed an atherogenic diet to induce lesions rich in lipid-laden macrophages and from older pigeons that had naturally-occurring atherosclerotic lesions. Monoclonal antibodies (MAb) 3-B-3, 9-A-2, or 2-B-6 and 5-D-4, recognizing delta Di-6S generated from chondroitin 6-sulfate (C6S) PG; delta Di-4S generated from dermatan sulfate (DS) PG and from chondroitin 4-sulfate (C4S); and sulfated poly N-acetyllactosamine sequences common to keratan sulfate (KS), respectively, were used to localize PG types by indirect immunofluorescence. In normal aorta, C6S PG was localized primarily in the media and showed a fluorescent gradient (inner media greater than outer media greater than intima greater than adventitia). In the atherosclerotic plaque, major immunoreactivity was observed using MAb 9-A-2 or 2-B-6, whereas lesser amounts were observed with 3-B-3. Patterns of immunoreactivity differed; 9-A-2 or 2-B-6 appeared to be associated with cells whereas 3-B-3 appeared to be intercellular. Although normal aorta was negative for antibody 5-D-4, recognizing KS, atherosclerotic plaques were consistently positive for this antibody. The pattern of 5-D-4 reactivity appeared to be intercellular. Except for immediately below the lesion, no reactive product using 5-D-4 was observed in the media. No major differences in distribution of PG were observed between naturally-occurring or cholesterol-induced fibrous plaques. These results indicate that both 4-sulfated PG and a previously undescribed KS glycoconjugate are major components of the atherosclerotic lesion.

Animals↗
PubMed1988

Distinct synthetic and structural characteristics of proteoglycans produced by cultured artery smooth muscle cells of atherosclerosis-susceptible pigeons.

Proteoglycan (PG) metabolism by aortic smooth muscle cell cultures derived from atherosclerosis-susceptible White Carneau (WC) and -resistant Show Racer (SR) pigeons was compared using [35S]sodium sulfate and [3H]serine or [3H]glucosamine as labeling precursors. Chondroitin sulfate (CS) PG and dermatan sulfate (DS) PG were the major PG secreted into the medium by both cell types. Total PG production, whether measured by incorporation of radiolabel into either core protein or glycosaminoglycan chains, was consistently lower in WC compared to SR cultures at several time points. This difference was due in part to lower (30-37%) PG synthesis in WC cells, but degradation of newly synthesized PG was an important contributor. A pulse-chase study indicated that of the total radiolabeled PG present at time O, only 47% was present at 24 h in WC cultures compared to 88% in SR cultures. The large CS-PG appeared to be the primary target for degradation in WC cells, and this selective processing resulted in a higher DS-PG:CS-PG ratio in these cultures. Structural studies indicated similar core protein and glycosaminoglycan chain sizes within a PG type for both cell types. PG monomer composition differed, however, by a higher sulfation of WC CS-PG compared to SR CS-PG and by a disaccharide sulfation position favoring 6-sulfation in WC PG and 4-sulfation in SR PG.

Animals↗
PubMed1988

Urinary thioether biological monitoring in the interaction between 1,2-dichloroethane and disulfiram in Sprague-Dawley rats.

The interaction between inhaled 1,2-dichloroethane (ethylene dichloride; EDC) and dietary Disulfiram (tetraethylthiuram disulfide; Antabuse; DSF) was investigated for male Sprague-Dawley rats in terms of urinary levels of thio-compounds extractable in ethyl acetate and then hydrolyzed in alkali (the classic urinary thioether assay). The assay was found to be an inadequate biological monitoring indicator for EDC or DSF exposure during the DSF/EDC interaction at exposures of 0, 153, 304 and 455 ppm EDC (7 hr/day, 5 days/week, 30 exposure days) for rats fed with AIN-76 diet fortified with 0.15% DSF. EDC inhibited the excretion of DSF-derived thio-compounds with increasing EDC concentration; the thioether content was dose-related in the absence of DSF. In situations where confounding agents generate neutral S-containing urinary metabolites without involvement of endogenous glutathione, the classic thioether assay requires supplementation by other biochemical monitoring strategies.

Administration, Inhalation↗
PubMed1987

Spontaneous and diet-aggravated atherosclerosis in White Carneau pigeons genetically selected for discordant blood pressure.

White Carneau pigeons, prone to atherosclerosis, were selectively bred for either high (HBP) or low (LBP) blood pressure to study blood pressure-atherosclerosis interaction. Sixty-four HBP and 45 LBP pigeons, of both sexes and 16-30 months of age, were used to evaluate spontaneous atherosclerosis and the response to a moderately atherogenic diet. At 0 time, HBP pigeons had a greater percentage of aortic intima covered with fatty streaks and a lesser involvement with raised plaque. After 4 and 6 months of dietary treatment, the HBP pigeons with plasma cholesterol concentrations elevated only 22 and 8% above basal level responded with greater increases in the extent and severity of raised plaque whereas LBP pigeons changed little. On the average, medial thickness and medial areas of the atherosclerosis-free proximal aorta were greater in HBP compared to LBP at all times. Lower compliance of the aorta in the HBP line at 6 months (0.49 +/- 0.027 microliter/mm Hg/cm thoracic aorta) compared to LBP (0.57 +/- 0.036) suggested stiffer arterial walls in the HBP line. The findings suggest that HBP pigeons selected for increased blood pressure are more responsive to moderate hypercholesterolemia acting as a stimulus for atherosclerosis progression. The HBP pigeon line is therefore a useful animal model in which to investigate genetically derived hypertension-atherosclerosis interactions.

Animals↗
PubMed1987

Artery wall derived proteoglycan-plasma lipoprotein interaction: lipoprotein binding properties of extracted proteoglycans.

Artery proteoglycan-lipoprotein binding characteristics were determined using intact, high molecular weight chondroitin sulfate proteoglycans (CS-PG) isolated from grossly appearing normal aortas of atherosclerosis susceptible WC-2 pigeons and plasma lipoproteins from normolipemic, randomly bred White Carneau pigeons. Optimum formation of particulate proteoglycan-lipoprotein complexes occurred in 5 mM Tris, 6 mM KCl, 4 mM CaCl2, 1 mM MgSO4, pH 7.2. The binding of CS-PG was specific for low density lipoprotein (LDL) and not high density lipoprotein (HDL). The relative importance of the intact monomeric structure of the PG was suggested in studies where glycosaminoglycan chains isolated from the PG monomer possessed less than 1% of the binding reactivity of the intact PG. The core protein prepared from the CS-PG monomer formed no measurable particulate complex.

Animals↗
PubMed1987

Lipoprotein interaction with artery wall derived proteoglycan: comparisons between atherosclerosis-susceptible WC-2 and resistant Show Racer pigeons.

The binding of intact, high molecular weight, aortic proteoglycan (PG) isolated from grossly normal appearing aortas of atherosclerosis-susceptible White Carneau pigeons (WC-2) and -resistant Show Racer pigeons (SR) to homologous and heterologous serum lipoproteins from both normolipemic and hyperlipemic pigeons was examined. In vitro binding studies were done using a mixture of purified chondroitin sulfate PG and dermatan sulfate PG monomers to simulate an in situ composition. For each animal, a binding potential or reactivity number was calculated and corresponded to the shape and slope of the PG-LDL binding curve, where higher values indicated greater reactivity. For WC-2 normal sera, mean values were 0.97 and 0.95 using WC-2 and SR PG respectively, compared to SR normal sera (equivalent total plasma cholesterol) where values were 0.80 and 0.82. Corresponding mean reactivity values for hyperlipemic sera (diluted to a cholesterol concentration of 300 mg/dl) were 0.95, 1.00, 0.73, and 0.79. The results suggest that LDL from both normolipemic and hyperlipemic atherosclerosis-susceptible WC-2 pigeons is more reactive in complexing to artery wall derived PG than LDL from SR pigeons, regardless of PG source.

Animals↗
PubMed1986

Inhalation pharmacokinetics of 1,2-dichloroethane after different dietary pretreatments of male Sprague-Dawley rats.

The effect of the pretreatment of male Sprague-Dawley rats with phenobarbital (PB), butylated hydroxyanisole (BHA) and disulfiram (DSF) on the inhalation kinetics of 1,2-dichloroethane [ethylene dichloride (EDC)] was studied by the gas uptake method. A closed recirculating system was constructed and characterized. The rate curves in all the pretreatment regimens showed saturable dependence on EDC concentration. These saturable dependencies (Michaelis-Menten) appeared to be associated with enzymatic metabolism. In general, a two-compartment, steady-state pharmacokinetic model described the uptake data. Data were transformed by Hanes plots to calculate the inhalational Km, the ambient EDC concentration at which uptake proceeded at half maximum rate, and Vmax, the maximum rate of uptake (i.e., maximum rate of metabolism). Although PB and BHA pretreatments did not affect the Km of EDC, PB pretreatment increased the Vmax while DSF pretreatment decreased both the Km and Vmax.

Administration, Inhalation↗
PubMed1986

Plasma low density lipoprotein accumulation in aortas of hypercholesterolemic swine correlates with modifications in aortic glycosaminoglycan composition.

Arterial wall sulfated glycosaminoglycans (GAG) of matrix proteoglycans have been implicated in the retention of plasma low density lipoproteins in the early stages of atherosclerosis. We have studied modifications in porcine aortic GAG composition after 4 and 11 weeks of diet-induced hypercholesterolemia. After these time intervals no grossly visible atherosclerotic lesions were discerned. GAG changes were correlated with tissue LDL accumulation estimated by quantification of immunochemically-identifiable apolipoprotein B (apoB). Values of apoB ranged from less than 10 to 250 ng/mg wet weight of aorta, and correlated significantly with tissue total cholesterol contents. Although total GAG concentrations did not differ between a normolipemic control and the two diet groups, apoB showed a significantly positive correlation with the percent of total GAG that was chondroitin sulfate and a significantly negative correlation with the percent of total GAG that was dermatan sulfate. Total tissue cholesterol likewise demonstrated similar correlations with GAG. Since areas of the aorta were chosen that were devoid of intimal thickening, these metabolic changes may occur in the inner part of the arterial tunica media. The results suggest that the accumulation of plasma LDL in the arterial wall following hypercholesterolemia may induce alterations in arterial GAG composition, presumably by affecting GAG synthesis by medial smooth muscle cells.

Animals↗
PubMed1986

Interaction between 1,2-dichloroethane and tetraethylthiuram disulfide (disulfiram). II. Hepatotoxic manifestations with possible mechanism of action.

The synergistic hepatotoxicity of dietary disulfiram (DSF) with 1,2-dichloroethane (DCE) subchronically administered by inhalation at three concentration levels (150, 300, and 450 ppm) was studied. The criteria for hepatotoxicity were treatment-related increases in serum activities of sorbitol dehydrogenase, 5'-nucleotidase, and alkaline phosphatase, and in liver-to-body weight ratios. DSF alone did not elicit these responses while DCE at the highest concentration level increased liver-to-body weight ratios and the activity of 5'-nucleotidase. Exposure to DSF alone decreased cytochrome P450 levels, but in combination with DCE, the decrement of cytochrome P450 was additive in a DCE concentration-dependent manner. However, depression of cytochrome P450 by DCE alone was not concentration dependent. Although DSF and DSF/DCE combination increased the activity of glutathione S-transferases (GSTs), both DSF and DCE singly and in combination increased the tissue levels of reduced glutathione (GSH). Evidence is presented showing that the potentiation of the hepatotoxicity of DCE observed in the presence of DSF may be due to an inhibition of microsomal mixed-function oxidase-mediated metabolism of DCE and to a compensatory increase in DCE metabolism to reactive metabolites generated by GST-mediated conjugation of DCE with GSH.

Animals↗
PubMed1986

Interaction between 1,2-dichloroethane and disulfiram. I. Toxicologic effects.

Inhalation and intraperitoneal (ip) studies with 1,2-dichloroethane (1,2-DCE) using Sprague-Dawley rats fed 0.15% disulfiram (tetraethylthiuram disulfide; Antabuse; DSF) in AIN-76 diet [approx. (79 +/- 11) mg DSF/kg body wt/day] resulted in the observation of a toxic interaction relative to either agent alone. The combination treatment caused testicular atrophy and histopathology in the liver and testes at 1,2-DCE inhalation concentrations greater than 300 ppm (an estimated dose of 194 mg/kg body wt/day) administered 5 days/week for 30 days or at ip doses of 150 mg 1,2-DCE/kg body wt/day over 30 days, 7 days/week. DSF lowered the 1,2-DCE dose at which liver enlargement, decreased liver/body weight ratios, and decreased body weight gains appeared relative to exposure to the 1,2-DCE alone. For the ip study, a decrease in spleen weight also occurred. Testicular atrophy and liver pathology had previously been observed in rats exposed to 20 ppm of ethylene dibromide (EDB) and fed 0.05% DSF in rat chow diet; EDB or DSF alone did not elicit testicular atrophy. These toxic effects indicate that 1,2-DCE may interact with DSF as does EDB, but at a much higher dose.

Aerosols↗
PubMed1983

Biochemical characteristics of dissociatively isolated aortic proteoglycans and their binding capacity to hyaluronic acid.

Proteoglycans were extracted from pigeon aortas with 4.0 M guanidine hydrochloride containing protease inhibitors to characterize the proteoglycan (PG) types, to examine and define their association with hyaluronic acid, and to compare pigeon aortic PG with human aortic PG isolated and characterized under similar conditions. Following chromatography of guanidine hydrochloride extracts on Sepharose CL-4B under dissociative conditions, two populations of PG were isolated. PG I, eluting at the column void volume, contained predominantly (83.2%) chondroitin sulfate whereas PG II, eluting at a Kav of 0.40, contained predominantly dermatan sulfate (54.7%). Following centrifugation, 76 and 63% of PG I and PG II, respectively, were located in the bottom two-fifths (p greater than 1.43 g/ml) of a CsCl gradient. Only PG I, predominantly chondroitin sulfate, was effective in associating with hyaluronic acid to form high molecular weight aggregates. The specific association was illustrated by removing endogenous arterial hyaluronic acid remaining in the preparation and demonstrating increasing formation of aggregate with increasing addition of human umbilical cord high molecular weight hyaluronic acid. The results of the study illustrate that artery PG of the pigeon are similar in distribution to those described for the human aorta and contain at least three types of PG, a chondroitin sulfate PG, a dermatan sulfate PG, and a polydisperse heparan sulfate PG. The chondroitin sulfate PG but not the dermatan sulfate PG are capable of forming high molecular weight aggregates with hyaluronic acid.

Animals↗
PubMed1983

Glycosaminoglycans: their distribution and potential vasoactive action in the nonpregnant and pregnant ovine uterus.

The effects of direct uterine artery infusions of glucosamine-hydrochloric acid, dextrose, and mannitol were evaluated in ewes that had undergone oophorectomy. Glucosamine-hydrochloric acid caused a prompt dose-related increase in uterine blood flow which approximated uterine blood flow rates induced by estradiol. Infusions of dextrose caused similar but transient vasodilatation, whereas infusions of mannitol had no effect. The glycosaminoglycans content of endometrium, myometrium, and caruncles/cotyledons (placentomes) was measured in nonpregnant and early pregnant ewes between 19 and 45 days' gestation. In endometrium and myometrium, total hexosamine levels were similar in nonpregnant and pregnant ewes. In the placentomes, total hexosamine levels increased steadily after 20 to 25 days' gestation. The hyaluronic acid fraction of total glycosaminoglycans hexosamine increased similarly and paralleled the total hexosamine levels. Galactosamine levels were unchanged in all tissues. It is postulated that a function of Wharton's jelly may be to provide the mechanism for shunting of uterine blood flow to the ovine placentomes.

Animals↗
PubMed1983

Phytoestrogen from Pinus ponderosa assayed by competitive binding with 17beta-estradiol to mouse uterine cytosol.

Ponderosa pine needle extracts contained a phytoestrogen that competed with 17beta-estradiol for specific binding to mouse uterine cytosol. Phytoestrogen was separated from the initial aqueous extract by acetone fractionation and eluted from a polyvinylpyrrolidone column with 90% methanol. Forty microg/ml was determined as the concentration of most purified phytoestrogen displacing 50% of 17beta-estradiol (15 pg/ml) from the estrogen specific binding sites of the mouse uterine cytosol. Intraperitoneal administration of 200 microg (0.3 g needle equivalents) of the phytoestrogen was equal in activity to 10 ng of 17beta-estradiol in a 24 hour uterine growth assay in immature mice. The phytoestrogen was retained in dialysis tubing with a 14,000 molecular weight cutoff and displayed an ultraviolet absorbance maximum at 208 nm, void of any phenolic chromophores. Phytoestrogen was being evaluated as a contributory factor in Ponderosa pine needle-induced abortion observed in range cattle.

Journal Article↗
PubMed1982

High molecular weight proteoglycans biosynthesized in culture by pigeon aortas.

The properties of aortic proteoglycans synthesized in vitro were examined to demonstrate synthesis of intact proteoglycans by aortic tissue in culture and to compare labeling and synthetic rates of two different populations of proteoglycan. Following 3, 6, or 9 h of incubation in medium containing [35S]sodium sulfate and [3H]serine, the tissue was extracted with 4.0 M guanidine hydrochloride containing protease inhibitors. Extracts were chromatographed on Sepharose CL-4B and subjected to buoyant density centrifugation under dissociative conditions. Radioactive precursors were incorporated into two major populations of aortic proteoglycan, one of high molecular weight eluting near the void volume of Sepharose CL-4B (Proteoglycan I) and one of lower molecular weight (Proteoglycan II) having a Kav of 0.40-0.44. The radioactively labeled proteoglycans were localized at densities 1.50-1.56 g/ml (Preparation 1) and 1.43-1.49 g/ml (Preparation 2) following CsCl buoyant density centrifugation. Both proteoglycan populations had increased incorporation of 35S and 3H over time. At all times the lower molecular weight proteoglycan had a higher specific activity (dpm 35S and 3H/micrograms hexuronic acid). At 3, 6, and 9 h, the specific activity of Proteoglycan II was 8.2-, 6.7- and 3.0-fold higher than Proteoglycan I using 35S and 13.0-, 8.1- and 2.7-fold higher using 3H, suggesting different synthetic rates for the two proteoglycans. The results illustrate synthesis of intact proteoglycans during short-term artery culture. The proteoglycan types have size and buoyant density characteristics as described for artery, but based upon changes in specific activity ratios, the two proteoglycan populations differ in rates of synthesis.

Animals↗
PubMed1981

Isolation and preliminary characterization of proteoglycans dissociatively extracted from human aorta.

Aortic proteoglycans (PG) were isolated from human aorta intima-media preparations with 4 M guanidine hydrochloride in the presence of protease inhibitors. The extracted PG mixture comprised 67% of the total aortic PG and was composed of 65% chondroitin sulfate, 22% dermatan sulfate, 8% heparan sulfate, and 4% hyaluronate. Attempts at isolation and purification of PG monomers using isopycnic CsCl gradient centrifugation under associative and dissociative conditions resulted in appreciable loss of PG through associations with co-extracted aortic proteins. The addition of a gel chromatographic step on Sepharose CL-4B under dissociative conditions resulted in separation of PG from the majority of co-extracted proteins. In addition, the procedure resulted in a separation of the PG into a population (PG-I) eluting near the column V0 and one (PG-II) included with a Kav of 0.38. Hyaluronic acid co-eluted with PG-I. The major glycosaminoglycan in PG-I was chondroitin sulfate, (85 to 95%). No dermatan sulfate was detected in PG-I, but this glycosaminoglycan was the predominant glycosaminoglycan in PG-II (50 to 70%). Heparan sulfate was present in small amounts in both PG-I and PG-II. Data presented support the proposal of at least three species of PG monomers in the aortic wall. Chromatographic studies under dissociative and associative conditions indicated that PG comprising PG-I but not PG-II were capable of associations with hyaluronic acid.

Adult↗