elastin and Ascorbic-Acid-Deficiency

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Collagen; Connective Tissue; Elastin; Extracellular Matrix Proteins; Gene Expression; Humans; Hydroxylation; Wound Healing

Topics: 4-Hydroxyphenylpyruvate Dioxygenase; Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Carnitine; Cell Line; Chemical Phenomena; Chemistry; Collagen; Complement Activating Enzymes; Complement C1q; Dopamine beta-Hydroxylase; Elastin; Fibroblasts; Free Radicals; Humans; Hydroxylation; Mixed Function Oxygenases; Multienzyme Complexes; Nucleosides; Nutritional Requirements; Oxidation-Reduction; Oxidoreductases Acting on CH-NH Group Donors; Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase; Procollagen-Proline Dioxygenase; Pyrimidines

Topics: Animals; Arteries; Ascorbic Acid; Ascorbic Acid Deficiency; Chick Embryo; Collagen; Elastin; Guinea Pigs; Humans; Hydroxyproline; Proline; Protein Binding; Skin

Vitamin C deficiency causes morphologic changes in the endothelial and smooth muscle compartments of guinea pig blood vessels. Endothelial cells synthesize the basement membrane components, type IV collagen and laminin, and smooth muscle cells synthesize elastin in blood vessels. Therefore, we examined the possibility that vitamin C deficiency affects the expression of these proteins. Decreased expression of types I and II collagens in other tissues of vitamin C-deficient guinea pigs is associated with weight loss and the consequent induction of insulin-like growth factor binding proteins; thus we also used food deprivation to induce weight loss. Female guinea pigs received a vitamin C-free diet, supplemented orally with ascorbate. Vitamin C-deficient guinea pigs received the same diet but no ascorbate, and the food-deprived group received no food, but were supplemented with vitamin C. Concentrations of mRNAs for basement membrane components and elastin in blood vessels were measured by Northern blotting; overall basement membrane metabolism was assessed by measuring immunoreactive laminin and type IV 7S collagen in serum. Laminin mRNA in blood vessels and serum laminin concentrations were unaffected by vitamin C deficiency. Concentrations of type IV collagen and elastin mRNAs in blood vessels were not significantly affected in moderately scorbutic guinea pigs (0-7% weight loss), but with increased weight loss, type IV collagen mRNA was 57% (P < 0.05) and elastin mRNA was 3% (P < 0. 01) of normal values. In food-deprived guinea pigs, type IV collagen mRNA was 51% (P < 0.05) and elastin mRNA was 35% (P < 0.05) of normal. Serum type IV 7S collagen concentrations were 25% of normal in scorbutic guinea pigs with extensive weight loss. The lower expression of type IV collagen and elastin mRNAs in blood vessels may contribute to defects observed in blood vessels during scurvy.

Topics: Amino Acid Sequence; Animals; Ascorbic Acid Deficiency; Base Sequence; Blood Vessels; Blotting, Western; Collagen; DNA, Complementary; Elastin; Female; Guinea Pigs; Laminin; Molecular Sequence Data; RNA, Messenger; Scurvy

Since Vitamin C (ascorbate, AH2) is an important airway antioxidant and is an essential component of tissue repair, and since acute (4 hr) O3 toxicity is enhanced by AH2 deficiency, we hypothesized that longer-term O3 effects might also be increased. Female Hartley guinea pigs (260-330 g) were fed either an AH2-sufficient or an AH2-deficient diet 1 week prior to exposure, and were maintained on their respective diets during 1 week of continuous exposure to O3 (0, 0.2, 0.4, and 0.8 ppm, 23 hr/day), and during 1 week postexposure recovery in clean air. The AH2-deficient diet caused lung AH2 to drop to about 30% of control in 1 week, and to below 10% by the end of exposure and recovery. Body weight gains during exposure were decreased in the 0.8 ppm O3 group, while the AH2 deficiency began to affect body weights only during recovery. O3 caused a concentration-dependent decrease in total lung capacity, vital capacity, carbon monoxide diffusing capacity, nitrogen washout, and static compliance, while increasing forced expiratory flow rates and residual or end-expiratory volume (suggestive of pulmonary gas-trapping). The lung/body weight ratio and fixed lung displacement volume were also increased in O3-exposed animals. Lung pathology consisted of mononuclear cell and neutrophil infiltration, airway as well as alveolar epithelial cell hyperplasia, and general decrease in epithelial cell cytoplasm. Thickening of the interstitium and an apparent increase in collagen staining were seen at the terminal bronchiolar regions. Some of these effects were marginally exacerbated in AH2-deficient guinea pigs. One week postexposure to air reversed all O3-induced abnormalities, irrespective of AH2 deficiency. Whole lung hydroxyproline and desmosine were not changed at any time by either O3 or AH2 deficiency. Measurement of lung prolyl hydroxylase activity suggested that AH2 deficiency as well as O3 exposure may have increased the tissue levels of this enzyme. The lack of a significant increase in toxicity with the longer-term exposure scenario suggests that AH2 has minimal influence on other compensatory mechanisms developed over time.

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Body Weight; Collagen; Desmosine; Elastin; Female; Guinea Pigs; Hydroxyproline; Lung Diseases; Lung Volume Measurements; Organ Size; Ozone; Procollagen-Proline Dioxygenase; Respiratory Function Tests; Tissue Fixation

1. After the administration of labelled proline to guinea pigs deprived of ascorbic acid for 15 days, the dorsal skin was examined 5 days later in an attempt to detect the presence of hydroxyproline-deficient collagen (protocollagen). The extent of incorporation of proline into skin collagens indicated a severe impairment of collagen synthesis. 2. A comparison of proline and hydroxyproline specific radioactivities in diffusible peptides obtained by treatment with collagenase of either purified skin collagens or direct hot-trichloroacetic acid extracts of skin failed to indicate the presence of protocollagen. Possible reasons for this are discussed. 3. The incorporation results did not indicate an inability of normal collagen, i.e. collagen hydroxylated to the normal degree, to cross-link in scurvy. 4. Incorporation of labelled proline into aortic elastin isolated from the same animals did not indicate a decrease in elastin biosynthesis in ascorbic acid deficiency, beyond that attributable to the inanition accompanying the vitamin deficiency. The proline/hydroxyproline specific-radioactivity ratio in elastin from scorbutic guinea pigs was about 6:1 in contrast with the 1:1 ratio in control groups. It is concluded that the formation of elastin hydroxyproline was ascorbate-dependent and that a hydroxyproline-deficient elastin is formed and retained in scurvy. The formation of desmosines was unimpaired in scorbutic animals. 5. Studies with chick embryos confirmed the formation of elastin hydroxyproline from free proline. Incorporation of free hydroxyproline into elastin hydroxyproline was negligible. 6. Digestion of solubilized samples with collagenase indicated that the hydroxyproline in guinea-pig aortic elastin preparations was not derived from contamination by collagen. It is suggested that most if not all of the hydroxyproline in the guinea pig elastin preparations investigated can be considered an integral part of the elastin molecule.

Topics: Animals; Aorta; Ascorbic Acid Deficiency; Chick Embryo; Collagen; Elastin; Guinea Pigs; Hydroxyproline; Male; Microbial Collagenase; Proline; Skin; Tritium