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Biomedical subjects

W D Wagner

Publications and source records attributed to W D Wagner.

At least 73 records · Page 4Linked to original sources
PubMed1981

Pneumoconiosis in animals exposed to poly(vinyl chloride) dust.

Rats, guinea pigs and monkeys were exposed by inhalation (6 hr/day, 5 days/week) for up to 22 months to a 13 mg/m3 concentration of PVC dust. Autopsies on rats and guinea pigs were performed after 12 months of exposure and on monkeys after 22 months after 22 months of exposure. Lung function tests were performed on monkeys after 9, 14 and 22 months of exposure. Aggregates of alveolar macrophages containing PVC particles were found in the lungs of all animals. These aggregates were more numerous in the monkey lungs. No fibrosis or significant cellular infiltrates were present in or near these cellular aggregates. No significant effects on pulmonary function could be demonstrated in the monkeys exposed to PVC. Under the conditions of this experiment, inhaled PVC produced a benign pneumoconiosis.

Animals↗
PubMed1980

Influence of dietary fats and an oral contraceptive on plasma lipids, high density lipoproteins, gallstones, and atherosclerosis in african green monkeys.

Twenty-nine African green monkeys were fed diets for 22 months containing 0.79 mg cholesterol/kcal and 40% of calories as either safflower oil or butter with or without the addition of an estrogen- and progestin-containing oral contraceptive. Plasma cholesterol concentrations ranged from 199 to 250 mg/dl. Animals consuming the safflower oil diet had plasma cholesterol concentrations that averaged 61 mg/dl lower than those consuming butter. At least 72% of this lowering was due to a reduction in low density lipoproteins. Triglyceride concentrations were also slightly lower in animals consuming the safflower oil diet. The oral contraceptive lowered total plasma cholesterol concentrations in both diet groups by an average of 41 mg/dl with 54% of this lowering (22 mg/dl) due to a reduction in high density lipoprotein cholesterol. This effect occurred only during the 3 weeks while the contraceptive was being administered and was not apparent 1 week after stopping the drug. Animals consuming safflower oil had bile that was more lithogenic and had more gallstones than did those consuming butter. Addition of the oral contraceptive caused a slight increase in bile lithogenicity, but this increase was not statistically significant. There was no significant interaction between the oral contraceptive and either of the diets to exacerbate cholelithiasis. At the plasma cholesterol concentrations achieved only minimal amounts of atherosclerosis developed and there were no indications of differences due to diet or oral contraceptive in the extent of atherosclerosis.

Animals↗
PubMed1980

A study of atherosclerosis regression in Macaca mulatta: III. Chemical changes in arteries from animals with atherosclerosis induced for 19 months and regressed for 48 months at plasma cholesterol concentrations of 300 or 200 mg/dl.

The influence of two levels of plasma cholesterol concentration on the long-term regression of atherosclerotic plaques in rhesus monkeys (Macaca mulatta) was studied. Forty-eight young adult male rhesus monkeys were fed an atherogenic diet for 19 months, then diets designed to maintain plasma cholesterol concentrations at 280-320 mg/dl (actual 316 +/- 10 mg/dl; mean +/- SEM) of 180-220 mg/dl (actual 204 +/- 4 mg/dl). Twelve animals were killed after 19 months to evaluate the atherosclerosis produced. The remaining 36 monkeys were studied after 48 months of atherosclerosis regression. Significantly greater amounts of accumulated nonesterififed and esterified cholesterol were lost from the arteries of monkeys that underwent regression at about 200 mg/dl, in comparison with 300 mg/dl. Regression at both plasma cholesterol concentrations resulted in increased collagen and decreased elastin content in the thoracic aorta but not in the other arteries studied. After regression at 300 mg/dl there was no change (83%) in the frequency of calcification of the thoracic aorta, while at 200 mg/dl the frequency of calcification was reduced to 50%. When compared with monkeys whose athersclerotic lesions were produced in an identical manner but were regressed for only 24 months, after 48 months had increased cholesterol concenrations in the thoracic aorta and carotid artery but not the abdominal aorta of iliaco-femoral artery, regardless of the plasma cholesterol concentration. The lipid composition of the regressed plaque suggested a change in plaque lipid toward the character of extracellular deposits described physically as crystalline in nature. The physical state was influenced by the length of the regression period and the plasma cholesterol concentration during regeression. In the thoracic aorta, principally as a result of changes in elastin content, the collagen-to-elastin ratio increased between 24 and 48 months of regression. It is proposed that the differences in removal of cholesterol from the thoracic and abdominal aorta after 24 and 48 months of regression in animals at 300 mg/dl may be influenced by the rearrangement of connective tissue. On the basis of the lipid and mineral content of uncomplicated atherosclerotic plaques after 4 yers of regression, it appears that the plasma cholesterol concentration during the regression period is a signigicant factor influencing the extent of plaque regression as well as the potential for further progression.

Animals↗
PubMed1979

Aortic glycopeptide sialic acid, hexose and hexosamine in a genetically selected (WC-2) strain of atherosclerosis-susceptible pigeon.

The aortic content of glycopeptide sialic acid, hexosamine and hexose was studied in a genetically selected strain of White Carneau pigeons (WC-2) with significantly more severe atherosclerosis than randomly bred White Carneau pigeons (RBWC). Pigeons were fed an atherogenic diet for 3 months and examined to determine differences in content of glycopeptide-sugars between WC-2 and RBWC, changes with the progression of atherosclerosis and the relationship of aortic cholesterol to glycopeptide-sugar content. In animals with mainly normal aorta (cholesterol content of 0.2-0.3 mg/cm2-aorta) sialic acid was significantly lower in WC-2 pigeons. The progression of atherosclerosis was associated with increased aortic glycopeptide sialic acid (r = 0.78; p less than 0.05) in WC-2 pigeons whereas an inverse relationship was suggested in RBWC pigeons. In WC-2, but not RBWC pigeons, significant positive relationships were seen for aortic glycopeptide hexosamine and aortic cholesterol and for aortic glycopeptide hexose and aortic cholesterol. The findings implicate a possible role of aortic glycoproteins in either the initiation or modulation of atherosclerosis of the WC-2 pigeon.

Animals↗
PubMed1978

Risk factors in pigeons genetically selected for increased atherosclerosis susceptibility.

A strain of genetically selected White Carneau pigeons (WC-2) with increased atherosclerosis at similar plasma cholesterol concentrations as randomly bred (RBWC) pigeons was studied to evaluate the commonly known risk factors for atherosclerosis. Indicators for the presence of hypertension, diabetes mellitus, "stress", hyperuricemia and hypothyroidism were determined. In pigeons fed the atherogenic diet, major differences in atherosclerosis were seen between WC-2 and RBWC. WC-2 pigeons had more aortic surface covered with plaque and greater concentrations of aortic nonesterified cholesterol, esterified cholesterol, uronic acid, and hydroxyproline, as well as a greater prevalence and severity of coronary artery atherosclerosis. For WC-2 and RBWC pigeons we found similar levels of hypercholesterolemia, mean blood pressure, plasma triglyceride and glucose concentrations. In addition, several other physiological variables such as plasma uric acid, calcium and phosphorus concentrations, adrenal and thyroid weights which have been implicated in the pathogenesis of atherosclerosis were similar. The findings indicate that the differences in extent and severity of atherosclerosis between WC-2 and RBWC cannot be explained by differences in the risk factors studied. Possible genetic regulation of atherosclerosis by mechanisms operable in the arterial wall of WC-2 pigeons is suggested.

Animals↗
PubMed1978

Aortic pulse wave velocity, elasticity, and composition in a nonhuman primate model of atherosclerosis.

Aortic pulse wave velocity was determined in Macaca fascicularis monkeys fed either atherogenic or control diets for 36 months. The foot-to-foot velocity and apparent phase velocities of the second through seventh Fourier harmonics at a given diastolic pressure in the atherosclerotic monkeys were 1.5 to 2.0 times the values for the control animals. More than 80% of the aortic intimal surface of the atherosclerotic monkeys was covered with fibrous or fatty plaque, which approximately doubled wall thickness and wall thickness to radius ratio. Angiochemical evaluations showed no difference in collagen or elastin concentration (as a fraction of lipid and mineral-free dried aorta), but the atherosclerotic aortas were 1.5 to 2.0 times that of control in collagen and elastin content (defined as the absolute quantity beneath a square centimeter of intimal surface). Total cholesterol and calcium concentrations in the atherosclerotic aortas were more than 10 times the values for the control aortas. The static circumferential distensibility of the excised atherosclerotic aortas was significantly less than control, but there was no difference in incremental (Young's) modulus of elasticity. The in vitro pressure-strain elastic modulus of the atherosclerotic aortas was more than twice that of control, which was predicted from the enhanced wave velocity. The significantly increased stiffness of the atherosclerotic arteries appeared to be due mainly to the increased wall thickness caused by the atherosclerotic plaques rather than to material changes described by Young's modulus. Extensive medial damage, however, also was present and could have had a major influence on stiffness. Atherosclerosis therefore can result in increased aortic stiffening, detectable by pulse wave velocity, even if there is no change in the overall Young's modulus of elasticity.

Animals↗
PubMed1978

Aortic total glycosaminoglycan and dermatan sulfate changes in atherosclerotic rhesus monkeys.

The composition and content of aortic glycosaminoglycans were studied in groups of rhesus monkeys fed control or atherogenic diets for 9 or 19 months. Aortic uronic acid content was significantly increased in both groups of monkeys with atherosclerosis. The major glycosaminoglycan in both control and atherosclerotic aortas was chondroitin sulfate with lesser amounts of heparan sulfate, dermatan sulfate, and hyaluronic acid. Dermatan sulfate was the only glycosaminoglycan to show a statistically significant elevation (65 to 87 per cent) in animals fed the atherogenic diet. This increase was positively correlated with the increased accumulation of aortic cholesterol (r = 0.4709, p less than 0.05). The results indicate that dermatan sulfate may be the major glycosaminoglycan involved during the early events of atherogenesis perhaps through retention of lipoprotein in the atherosclerotic artery.

Animals↗
PubMed1977

Large scale production of White Carneaux pigeons with reliable pedigrees: reproductive characteristics and parent-offspring identification.

The loft-breeding method was used for the production of 439 White Carneaux pigeons with reliable pedigrees. During the 1-year study, annual productivity averaged 10.5 offspring per parental pair, with a mean of 1.5 offspring per clutch. Early mortality was 13%; most deaths occurred during the first 10 days of age. Eighty-six percent of the clutches contained two eggs, 54% of which hatched. Only 23% of the single-egg clutches hatched. A majority of breeding pairs in the colony made alternate use of two adjacent nests. A seasonal variation was observed in the time intervals between successive clutches; the shortest intervals (37 days) occurred from March through July, while the longest intervals (119 days) occurred in midwinter. A regular daily pattern of parental nest hovering was seen: males incubated eggs and hovered newly hatched birds from 1000 until late afternoon, while females occupied the nests the remainder of the time. The loft-breeding method required frequent observations and accurate record keeping but, compared to individual mating of caged pairs, it had the advantages of lower cost and reduced management problems. The large outdoor lofts allowed the pigeons exercise, group social interactions, and exposure to natural environmental conditions.

Animals↗