Notes on a modification of the Neuman and Logan method for the determination of the hydroxyproline

Effect of ascorbic acid on guinea pig skin collagen synthesis. I. Total collagen

A deficiency of ascorbic acid caused a decreased uptake of 3H-proline into guinea pig skin collagen and a further decrease in the 3HO-proline formation; inanition from pair-feeding was not a contributing factor. An anemia developed in the completely deficient animals which was prevented with low levels of ascorbic acid in another group.

The effect of chondroitin sulphate-protein on the formation of collagen fibrils in vitro

1. It was found that the precipitation of collagen fibrils at 37 degrees from mixtures of chondroitin sulphate-protein and tropocollagen at physiological ionic strength and pH takes place in two distinct phases. The first occurs immediately on mixing either at 4 degrees or at 37 degrees , and the second occurs only at 37 degrees and after a lag phase whose magnitude depends on the proportions of components. 2. When the second stage of precipitation was inhibited by mixing the reactants at 4 degrees , the initial precipitate was found to contain ;native-type' collagen fibrils and chondroitin sulphate-protein. 3. On the basis of kinetic experiments it was concluded that aggregates of chondroitin sulphate-protein and tropocollagen form instantaneously and that these act as sites for the second stage of precipitation of fibrils. 4. The gels that result after continued incubation at 37 degrees are fibrous in appearance if formed in the presence of the initial precipitate of chondroitin sulphate-protein and tropocollagen. 5. On the basis of these experiments in vitro the authors propose a sequence of events for collagen fibrogenesis in vivo.

Effects of chondroitin sulphates on mineralization in vitro

1. Soluble sodium chondroitin sulphate, from bovine ribs or puppy epiphyseal plate, at a concentration 80mm in terms of glucuronate, decreased the amounts of calcium and phosphate precipitated from a solution 6.9mm in phosphate and 6.9 or 13.8mm in calcium, buffered in the pH range 6.6-8.2 with 20-25mm-collidine and 5-20mn-hydrochloric acid when incubated for 2hr. at 30 degrees , and for 0.25-24hr. when buffered at pH7.0. 2. An insoluble fraction of puppy epiphyseal plate, containing chondroitin sulphate and collagen, was found to have the same effect at lower concentrations of chondroitin sulphate and a higher calcium/chondroitin sulphate glucuronate ratio, but the formation of calcium phosphate from calcium bound to this material appeared to proceed more rapidly than from calcium in solution, when both were present in the same system. 3. The implications of these results are discussed in relation to the calcium/chondroitin sulphate glucuronate ratios found in different parts of non-calcifying and calcifying cartilage in vivo and to the calcium and phosphate gradients between blood and calcified tissue.

The protein coating of asbestos bodies

1. Asbestos bodies were isolated from human lungs and the amino acid composition of the protein content was determined. 2. The hydroxyproline, glycine, leucine and phenylalanine values indicate that the protein in the coating cannot be principally collagen. 3. Albumin can be adsorbed on chrysotile asbestos as a monolayer but more than a monolayer is adsorbed if iron is also adsorbed. 4. Ferritin is adsorbed on chrysotile to give a thick layer. 5. The amino acid composition and adsorption studies are discussed in the light of the suggestions that the protein coating of asbestos is collagen (Beattie, 1961) or ferritin (Davis, 1964).

Adaptation of the rat to a low-protein diet: the effect of a reduced protein intake on the pattern of incorporation of L-[14C] lysine

1. Rats were chronically depleted of protein by being kept on a 6% casein diet for 5–8 weeks. Control rats were fed on a normal diet. Both groups were injected intraperitoneally with L-[U-14C]lysine. Some rats from each group were then put on a protein-free diet to produce acute depletion. The animals were killed 3 days after the injection. 2. The organs and tissues were analysed for total nitrogen and radioactivity. Free lysine, total amino N and specific activity of free lysine were measured in muscle, liver and serum. The total muscle mass of the animals was determined. Samples of muscle and skin were fractionated and the sp. ac. of the fractions was measured. 3. The main loss of N in acute depletion was found in the viscera and carcass residue; the percentage of total body N contributed by muscle was increased in protein-depleted rats. 4. The depleted rats retained relatively more radioactivity in the internal organs and less in the carcass than normal rats. 5. The ratio of the sp. ac. in protein-bound lysine to the sp. ac. of free lysine showed that protein synthesis was reduced in the muscle of the protein-depleted rats, although there was no decrease in the amount or sp. ac. of free lysine even in severe depletion. 6. Sarcoplasmic and fibrillar proteins of muscle were equally affected by protein depletion, but there was some indication of a preferential decrease in protein synthesis in one of the skin fractions. 7. The results for muscle protein are compared with those given in the literature for liver proteins. It is suggested that the rat adapts to a low-protein intake by an alteration in the pattern of protein synthesis.

The effects of prepubertal ovariectomy on connective tissue generation

Polyvinyl sponges were implanted subcutaneously in 84-day-old female rats and in prepubertally ovariectomized rats of the same age. Animals from both groups were killed 72 ± 1 hours later. The mean hexosamine concentrations in sponge tissue were, in the intact animals and ovariectomized rats respectively, 340 ± 28 and 258 ± 19 μg hexosamine per 100 mg dry lipid-free tissue. The confidence intervals were derived from the Student's t test (5%). Prepubertal ovariectomy decreases the hexosamine concentration of the sponge tissue during the early stages of connective tissue generation in young adult rats and may have a similar effect on serum hexosamine. The mean hydroxyproline concentrations in the sponge tissue of the remaining animals, which were killed 10 days after implantation, were 1027 ± 77 and 777 ± 130 μg hydroxyproline per 100 mg dry lipid-free tissue for the ovariectomized and intact animals respectively (5% confidence interval). Prepubertal ovariectomy increases the rate of connective tissue generation in young adult rats. The ovariectomized rats were heavier at death than the intact animals and no apparent histologic differences were noted in the sponge tissue recovered from the two groups.

Role of oxygen fixation in hydroxyproline biosynthesis by etiolated seedlings

Etiolated maize and soybean seedlings were grown for several days in atmospheres enriched with O(18). Hydroxyproline subsequently isolated from the seedlings by column and thin-layer chromatography was labeled with excess O(18), but proline was not. Control experiments in which seedlings were grown in H(2)O(18) and unlabeled atmospheres demonstrated that neither proline nor hydroxyproline was labeled with excess O(18). It was concluded that oxygen fixation is an essential feature of hydroxyproline biosynthesis in these seedlings, and that the hydroxyl oxygen atom in hydroxyproline is derived from molecular oxygen and not from water; similar results have been reported previously for sycamore cell suspensions.

Isolation of a protective gamma-globulin fraction interfering with the zinc sulphate turbidity test

The serum of a case of hyperglobulinaemia with negative thymol and zinc sulphate turbidity reactions was studied. The serum when added to pathological sera with high turbidity values brought about a marked reduction in the original turbidity values. Also, the serum did not give the usual copper proteinate precipitate when added to copper sulphate solutions. The anomalous protein fraction responsible for the above properties was isolated from the gamma globulins by precipitation at 28% saturation with ammonium sulphate. It was found to be neither a macroglobulin (Waldenstrom's), a cryoglobulin, nor a collagen protein. Its occurrence in the very gamma globulin fraction which is responsible for many of the turbidity reactions is of great significance in the interpretation of these tests. It is suggested that the normal turbidity and flocculation reactions reported in some cases of multiple myelomatosis might be due to some such anomalous proteins.