Kung-Ying Tang Kao

Connective Tissue: I. Age and Sex Influence on Protein Composition of Rat Tissues:

Summary Tissues from tail tendon, aorta, skin, uterus, lung, muscle, heart, liver, kidney and spleen of male and female rats at 3–5 wk, 8 mo and 2 yr of age were fractionated into soluble protein, insoluble collagen and elastin. Amount of soluble collagen in the soluble protein fraction was calculated according to amount of hydroxyproline. Significant changes in these fractions with age occurred only in skin, tendon, uterus and aorta, with scleroprotein increased and non-scleroprotein decreased.

Connective tissue V. Comparison of synthesis and turnover of collagen and elastin in tissues of rat at several ages.

Summary 1. Synthesis and turnover of collagen and elastin was studied in rats of 5 weeks, 8 months and 2 years of age, respectively, by observing incorporation and removal of uniformly labeled C14-lysine. 2. Synthesis of collagen and elastin was more rapid in the tissues of young rats (5 weeks) than in those of older animals. In tendon, no detectable synthesis of IC was found at 2 years of age. 3. The uterus was the only organ examined, which showed appreciable synthesis and turnover of collagen in older animals. 4. The turnover rate of collagen in relation to other proteins was low in all animals even in those 5 weeks old. No turnover was observed in the insoluble collagen of tendon and skin at 8 months and 2 years of age, respectively.

Connective tissue. IV. Synthesis and turnover of proteins in tissues of rats.

Summary 1. The synthesis and turnover of protein in aorta, uterus, tendon and skin were studied in 5-week old rats. 2. The SA of connective tissue proteins in decreasing order of magnitude was nonscleroprotein, soluble collagen, insoluble collagen and elastin. 3. Among the tissues studied, greatest synthesis and turnover of collagen was observed in uterus. As regards synthesis, skin, aorta and tendon followed in descending order, while, for turnover, the order was skin, tendon and aorta. The authors gratefully acknowledge suggestions and advice of Dr. C. H. Treadwell and technical assistance of William Hitt, Charles Hizer and Richard Dawson.

CONNECTIVE TISSUE XII. STIMULATING EFFECTS OF ESTROGENS ON COLLAGEN SYNTHESIS IN RAT UTERINE SLICES.

Summary 1. The effect of estradiol, es-trone, estriol and progesterone on collagen and noncollagenous protein (NCP) synthesis was studied in ovariectomized and normal rats both in vivo and in vitro with the Kao uterine slice technique. Both chemical and C14-lysine determinations were made. 2. Chemical studies revealed that: (a) Of the agents used, estradiol was most effective in stimulating the synthesis of collagen and NCP in the uteri of ovariectomized rats. Estrone, estriol and progesterone were similarly effective, but to a lesser degree. Estradiol also increased the collagen and NCP of normal rats. In the dosages employed, the uteri of estradiol-treated ovariectomized rats showed a greater capacity for synthesizing collagen than did the uteri of normal control rats, (b) After ovariectomy, there was a decrease in uterine weight, total collagen and NCP and an increase in concentration of collagen and NCP. (c) Administration of estrogen to the ovariectomized rat was associated with an increase in uterine weight, and in total amount per uterus of collagen, NCP and supernatant protein (SP). Simultaneously, the concentration of collagen decreased, while that of NCP and SP increased slightly. 3. Considered in conjunction with the chemical analyses, the radioisotopic studies with C14-lysine revealed that the major effects on uterine connective tissue of estrogen injections into ovariectomized animals as determined in KUST preparations were: (a) A 400%-700% increase in specific activity of collagen and a 50% increase in specific activity of NCP; (b) A 100% increase in total counts per minute recovered in collagen and a 50-60% increase in those of NCP per incubation; (c) a 700% increase in counts per minute in collagen and 200-300% increase in NCP per uterus; (d) A much higher ratio of specific activity of hydroxlysine from the treated rat to that from the untreated rat as compared with the ratio of specific activities of lysine from the same 2 groups of animals; (e) An effective dose of estradiol for stimulation of collagen synthesis is 1 μg with a dose-response time of 16 hours. 4. It is suggested that one of the important, if not the most important, action of estrogen in uterine connective tissue is concerned with the hydroxylation of lysine. The authors gratefully acknowledge suggestions and advice of Dr. C. R. Treadwell.

Connective Tissue VIII. Factors Effecting Collagen Synthesis by Sponge Biopsy Connective Tissue.

Summary The conversion of C14-proline to C14-hydroxyproline has been used as a measure of the synthesis of collagen in sponge biopsy connective tissue in vitro. Krebs-Henseleit medium, pH 7.4, under an atmosphere of 95% O2–5% CO2 created the most satisfactory conditions we have employed for collagen synthesis in vitro. Elimination of NaCl from the incubation medium gave the most striking depression of collagen synthesis. Replacement of NaCl by other chemical compounds did not restore the synthesis of collagen to the control level. An amino acid mixture, containing essential amino acids, had an inhibitory effect on collagen synthesis. Freezing and crushing destroys most of the enzyme system or systems required for collagen synthesis. The data presented are compatible with the concept that all collagen hydroxyproline is derived from proline peptide.

Connective Tissue XIII. Effect of Estradiol Benzoate upon Collagen Synthesis by Sponge Biopsy Connective Tissue.

Summary 1. The effect of estradiol benzoate upon collagen synthesis in sponge biopsy connective tissue has been studied in normal and ovariectomized rats. 2. A dose of 300 μg, twice weekly for 4 weeks, produced a decrease in sponge weight, collagen concentration and total amount of collagen. However, the radioisotopic data demonstrated a stimulating effect of estrogen on collagen synthesis, as there was an increase in the specific activity of collagen, hydroxylysine and lysine and the total counts per minute recovered per incubation. These results lead to the conclusion that estradiol stimulates the metabolism of collagen. 3. The stimulatory effect of estradiol on collagen synthesis in sponge biopsy connective tissue is more readily demonstrated in the ovariectomized than in the intact rat.

Connective tissue: XVII. Protocollagen hydroxylase of pig uterus

Abstract A highly active protocollagen hydroxylase, comparable to that from chick embryos, was found in homogenate of porcine uterus. For maximum activity, atmospheric O2, Fe2+, ascorbic acid and α-ketoglutarates are required. The uterine hydroxylase catalyzes the hydroxylation of both proline and lysine in protocollagen prepared from bone of chick embryos. The uterine tissue could be stored at −30° for several weeks without a decrease in enzymic activity.

The intermolecular cross-links in rat uterine collagen☆

Abstract With tritiated NaB3H4 reduction, the collagen cross-links in rat uterus are found to be dehydrodihydroxylysinonorleucine and dehydrohydroxylysinonorleucine. The ratio of dehydrodihydroxylysinonorleucine/dehydrohydroxylysinonorleucine is 10:1 in young rat and 4:1 in old rat. With increasing age there is an increase in the reducible cross-links. Estrogens stimulate the synthesis of these cross-links.

Silicon in Biological Material. II. Variations in Silicon Contents in Tissues of Rat at Different Ages

Summary The silicon content of several tissues of male rats, Wistar strain, 5 weeks and 30 months of age were determined by a modification of Kings method, with special caution to avoid contamination with outside sources of silicon. It is shown by the data that, with increasing age, silicon content significantly increased in kidney, brain, liver, spleen, lung and femur, and decreased in skin.

Silicon in Biological Material. I. Determinations Eliminating Silicon as a Contaminant

Summary 1. The silicon content of the tissues of man and rat were reinvestigated by a modified Kings method, in which contact with glassware was avoided. 2. All tissues studied, except bone, contained between 2-10 μg silicon /g of dried tissue. Bone contained approximately 100 μg silicon/g of dried tissue. 3. In a single balance study, 90% of the silicon in rat food was excreted in the feces; some silicon was excreted in the urine.