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Biomedical subjects

R B Rucker

Publications and source records attributed to R B Rucker.

At least 73 records · Page 4Linked to original sources
PubMed1983

Variation of elastin fluorescence with method of preparation: determination of the major fluorophore of fibrillar elastin.

The variation of fluorescence of two fibrillar elastins as a result of preparation methods was studied and the major common fluorophore was identified. Dilution of acid-hydrolyzed bovine ligament elastin 1:2500 (g:ml) overcame inner filter effects (IFE) to reveal fluorescence excitation and emission maxima of 330/408 nm. An IFE effect observed in elastase-solubilized elastin was unresponsive to dilution. Elastase-solubilized elastin had maximal fluorescence at 338/410 nm (pH 2.3) and 325/394 nm (pH 7.4), and the fluorescence intensity was 35-40% of that of the acid-hydrolyzed elastin. Changes in fluorescence that occurred when an acid hydrolysate was evaporated to dryness were prevented by evaporation to a volume not less than 15 ml. As a result, there was an almost two-fold increase in the yield of a fluorophore with spectral maxima near 340/400 nm. Chick aorta elastin purified by enzymatic methods also contained substantial amounts of this fluorophore. It is concluded that the compound with fluorescence of 340/400 nm is the major common fluorophore of postnatal fibrillar elastins.

Animals↗
PubMed1983

Interactions of ascorbic acid supplementation and bleomycin instillation on murine lung connective tissue metabolism.

The effects of ascorbic acid supplementation on the pulmonary toxicity induced by bleomycin were examined. Swiss-Webster mice were fed an ascorbate-free diet supplemented with ascorbic acid at 0%, 0.2%, or 1.0% of the diet for 2 weeks. Bleomycin (0.15 units) was instilled intratracheally and the mice were killed 1 week later. Bleomycin caused pulmonary inflammation and edema as noted by the increases in lung wet weight and lung wet-weight-to-dry-weight ratios. The activity of prolyl hydroxylase was increased 1.4-fold to 1.6-fold in response to bleomycin, but only minor increases were observed in the collagen and elastin content of the lung. Prior dietary ascorbic acid supplementation did not reverse the effects induced by bleomycin. Interestingly, each dietary level of supplemental ascorbic acid resulted in a slight increase in the elastin and collagen content of the lung in comparison with lungs from mice consuming no ascorbic acid in their diet. The data suggest that high levels of ascorbic acid supplementation may aggravate the response to bleomycin.

Animals↗
PubMed1983

Experimental diabetes and platelet aggregation in the rat.

Alloxan-induced diabetes and platelet aggregation were studied in male Sprague-Dawley rats. Platelets from diabetic rats receiving insulin (one unit protamine-zinc insulin/100 g BW) were consistently more responsive to aggregating agents (ADP, thrombin) than platelets from control rats (with or without insulin administration). Also, serotonin release from platelets was consistently greater in diabetic compared to control rats following thrombin-stimulated platelet aggregation.

Adenosine Diphosphate↗
PubMed1982

Role of copper in collagen cross-linking and its influence on selected mechanical properties of chick bone and tendon.

Day-old White Leghorn cockerels were fed skim-milk-based diets containing 0, 2, 4, 8, or 16 ppm added copper as CuSO4 for 21 days. Lysyl oxidase was extracted from bone and tendon. The recovery of activity from the extracts was linearly correlated with dietary copper (r greater than 0.90). Tests of the mechanical properties of tendon and bone indicated that tendon viscoelasticity (as measured by stress--relaxation) may not be significantly influenced by copper, whereas the ultimate torsional strength of bone is markedly decreased when the dietary copper level is below 1 ppm. Furthermore the torsional fracture characteristics of bone from copper-deficient birds demonstrated a lack of plastic deformation prior to failure that was normally seen in bone from control birds. The change in the mechanical properties of bone from copper-deficient birds appeared to be related to a decrease in the amounts of dihydroxylysinonorleucine and other lysine-derived cross-linking amino acids in bone collagen. The data indicate that the requirement for optimal growth of chicks fed skim-milk-based diets is 6--8 ppm copper, however, the requirement for normal cross-link formation in bone is less than 2 ppm copper.

Amino Acid Oxidoreductases↗
PubMed1982

Dietary cadmium, zinc and copper: effects on chick lung morphology and elastin cross-linking.

Day-old White Leghorn cockerels were divided into seven dietary groups and fed one of the following diets: 1) a casein-based basal diet; 2) a casein-based diet supplemented with 10 mg/kg cadmium, 3) 100 mg/kg cadmium, 4) or 800 mg/kg zinc; 5) a casein-based diet pair-fed to the 100 mg/kg Cd group; 6) a spray-dried nonfat milk-based diet with no added copper, or 7) a spray-dried nonfat milk-based diet supplemented with 5 mg/kg copper. At termination (5 weeks), the birds were killed, and the effects of the diets on selected features of lung composition and morphology were assessed. Body weights were reduced in the 100 mg/kg Cd, pair-fed, and Cu-deficient groups when compared to their controls (casein-based or milk-based copper-supplemented diets). There were no differences in lung weights (expressed relative to metabolic body size) among the groups, although copper deficiency did result in a slight decrease in the dry to wet weight ratio of lung. Lung elastin content and the desmosine content in elastin were significantly lower in the Cu-deficient group and tended to be lower in the group fed 800 ppm Zn. Significant alterations (enlargement of the tertiary bronchial lumen) in morphology were also observed in lungs from both the 100 mg/kg Cd and Cu-deficient groups. Alteration in lung morphology observed in the 100 mg/kg Cd group could not be explained by changes in the elastin content of lung.

Animals↗
PubMed1982

Developmental changes in composition of cats milk: trace elements, minerals, protein, carbohydrate and fat.

The concentrations of iron, copper, zinc, manganese, calcium, magnesium, protein, carbohydrate and fat were analyzed in cats' milk during the course of lactation. Cats' milk is different from most species in that the concentrations of iron, copper, zinc and manganese are lower during the first 2 days of lactation than on days 3-7. After the initial rise in the concentration of these elements, the concentration of iron decreased from 5.9 micrograms/ml to 3.0 micrograms/ml, with most of the decrease occurring between days 8 and 21. Copper concentration declined from 1.6 micrograms/ml to 0.8 microgram/ml, with most of the change occurring between days 8 and 28. Concentration of manganese increased during lactation, from 0.14 microgram/ml of 0.39 microgram/ml. Calcium concentration increased rapidly during the first 3 weeks from 550 micrograms/ml to 1500 micrograms/ml, with little change thereafter. The magnesium concentration (congruent to 100 micrograms/ml) and zinc concentration (congruent 6 micrograms/ml) were not affected by stage of lactation. Protein increased during lactation from 4% to 7%, and fat from 3% to 5%, whereas carbohydrate concentration (congruent 4%) did not change significantly. These data demonstrate that the nutrient intake of the kitten changes markedly during the early neonatal period and that these changes should be taken into account in evaluating studies of suckling cats.

Animals↗
PubMed1981

Elastin metabolism in rodent lung.

Data from the in vivo incorporation of [3H]valine into fractions of elastin obtained from rat or mouse lung suggest that postnatal lung elastin synthesis occurs predominantly in the first 1 to 2 weeks of life. Very little [3H]valine was incorporated into lung elastin obtained from adult animals. When lung elastin from neonatal mice was radiochemically labelled with [14C]lysine as a single pulse, it was observed that the specific activity of the elastin expressed as the total dpm values as 14C per mg was not significantly altered over a 6 month period. Elastin appears to turn over very slowly in mouse lung with half-life best estimated in years.

Animals↗
PubMed1980

Aorta elastin turnover in normal and hypercholesterolemic Japanese quail.

The turnover and degradation of mature elastin from the aortae of Japanese quail were estimated following injection with L-[U-14C]lysine by measuring the changes in specific activity of L-[U-14C]lysine and 14C-labelled desmosine and isodesmosine (crosslinking amino acids derived from lysyl residues) in elastin over a 39-week period. Only 5% of the variation in radioactivity could be attributed to changes in time. Therefore, it was concluded that the best estimates of mature elastin turnover are only quantifiable in years. Dietary cholesterol in amounts sufficient to induce plaque formatioin and fragmentation of the elastic lamina in the aorta did not significantly influence turnover time. It would appear that once the total pool of elastin in aorta is stabilized as mature fibers it is not subject to proteolysis or resynthesis of sufficient magnitude to result in measurable turnover.

Animals↗
PubMed1979

Partial characterization of a tropoelastin precursor isolated from chick aorta.

Evidence is presented that indicates tropoelastin is derived from a soluble elastin with a molecular weight of 95000. Tropoelastin and its proposed precursor were isolated from the aortas of copper-deficient chicks. Although it is doubtful that the proposed precursor is an initial product of elastin translation, i.e., a proelastin, it is proposed to be at least a truncated form of proelastin that is converted to tropoelastin. The key to its isolation was the presence of alpha 1-antitrypsin at each step in the purification procedure. The first 11 amino acid residues at the NH2 terminal of the proposed tropoelastin precursor (GGVPGVAVPGGV) are the same as those for tropoelastin. Its amino acid composition is similar to that of tropoelastin, except for higher amounts of acidic amino acid residues. Further, the proposed precursor contains a limited number of aldehydic functions, presumably in the form of peptidyl allysine. This was taken as an indication that the proposed precursor serves as a substract for lysyl oxidase. Under the conditions used for the isolation, the precursor appeared to be in higher concentrations than tropoelastin in aorta extracts from copper-deficient chicks.

Amino Acid Sequence↗