Electrophoretic analysis of type I collagen from bovine Achilles tendon: comparison between the extracted raw material and the freeze-dried product.

The present study was aimed at verifying if the freeze-drying process has any effect on the polypeptide composition of the collagen extracted from bovine Achilles tendon in an acetic acid gelified form. Data from our laboratories showed that the freeze-drying process renders the collagen gel essentially insoluble; under these conditions the collagen sample can no longer be analyzed by gel electrphoresis. We found that treatment of the sample with pepsin in acid environment, followed by precipitation with ammonium sulphate yields an insoluble fraction that is susceptible of being analyzed by polyacrylamide gel electrophoresis. The The electrophoresis, run under standard conditions, shows that six major subunits, corresponding to alpha, beta and gamma polypeptides, can be revealed in the sample treated in this way. So the freeze-dried collagen exhibits a polypeptidic composition that is basically identical to that shown by the collagen gel, with regard to the fraction precipitated with ammonium sulphate. Otherwise the pattern of the enzymatic hydrolysis was investigated by measuring the hydroxyproline content, and so the collagen content using the 7.46 conversion factor from hydroxyproline to the scleroprotein collagen, in the various steps of the hydrolysis itself: the analytical results showed no differences between the freeze-dried collagen and the gelified form; this confirms that the lyophilization process does not alter the polypeptidic composition of the collagen in any way.

[Effect of ionizing radiation on the structure of the collagen fibers of human tendons]. / Vliianie ioniziruiushchei radiatsii na strukturu kollagenovykh volokon sukhozhilii cheloveka.

In studying the effect of ionizing radiation on the properties of human Achilles tendon collagen fibres, the following parameters were analyzed: hydrothermal contraction temperature, module of elasticity, the number of cross-links, free and bound water levels, acids-soluble fraction content, and ultrastructure. With radiation doses of 2-10 Gy no changes in the collagen status were noted. An increased (from 5 to 25 Gy) radiation dose caused changes in physicochemical properties which was indicative of the formation, in the connective tissue collagen, of radiation-induced intermolecular cross-links stabilizing the biopolymer structure.

Polyneuropathy with lipid deposits in Schwann cells and axonal degeneration in cerebrotendinous xanthomatosis.

The present paper is a histological, histochemical and electron microscopic study of biopsied specimens from both right and left Achilles tendon, sural nerve and gastrocnemius muscle in a case of peripheral neuropathy with decreased sensory conduction velocity within a cerebrotendinous xanthomatosis confirmed biochemically in a 29-year-old woman. The tendon specimens contained large deposits of complex, non-homogeneous lipids, distributed intra- and extracellularly. The right sural nerve specimen showed a very severe neuropathy with massive diffuse myelinated fiber loss, presence of foamy macrophages and lipid droplets in Schwann cells. Segmental de- and remyelination was noted in 17% of the teased myelinated fibers. No onion bulbs were observed. Two years later, the left sural nerve specimen revealed a mild diffuse myelinated fiber loss, a more active segmental de- and remyelination (23%) without onion bulbs, and an active regeneration. Lipid storage aspects were absent. The gastrocnemius muscle specimens exhibited slight alterations of neurogenic origin. The pathogenesis of this neuropathy is discussed.

Experimental treatment of tendon injury with heparin.

The effect of heparin on the progress of healing in the injured tendon was examined after a standard injury had been created in the Achilles tendons of New Zealand White rabbits. Half of the rabbits were then treated by the intratendinous injection of heparin. The diameters of the injured right hind and the uninjured left hind Achilles tendon and overlying skin were measured using vernier calipers before injury and at one month after injury. At this time histological analysis was carried out on all Achilles tendons and tendon dry weight, collagen concentration and DNA concentration were measured. Orientation of collagen fibres was more pronounced in treated than untreated tendons while cellularity and blood vessel density were less pronounced. Analysis by Students t-test demonstrated a statistically significant difference between treated and untreated tendons in terms of leg diameter (p less than 0.005), dry weight (p less than 0.01) and DNA concentration (p less than 0.01).

Spontaneous rupture of the Achilles tendon - a sign of hyperlipoproteinaemia (HLP) type II.

In biopsies from spontaneously ruptured Achilles tendons a serum lipid and lipoprotein analysis was performed in fifty nine patients. In nine males considerable histological signs of lipid deposition were detectable. The tendon fibers were found to be partly desintegrated. Only in these cases LDL-cholesterol values were found to exceed the normal range indicative of type II hyperlipoproteinaemia (HLP). None of the fifty remaining patients presented biochemical or clinical signs of disorders of lipid metabolism. The observations demonstrate that a spontaneous rupture of Achilles tendom may indicate a primary type II HLP.

[Polyploidisation - a phenomenon of aging? (author's transl)]. / Polyploidisierung-ein Alternsphänomen?

By means of cytophotometric determination of DNA in different cellular systems an increase in polyploidisation correlated to age could be demonstrated. The latter is well demonstrable if compensatory hyperplasia or hypertrophy occurs. It is discussed that cellular systems of older individuals can increase their DNA - content, but they are not able to carry out a caryo-and cytocinesis.

The effects of zinc on ectopic bone formation.

The effect of dietary zinc deficiency was studies in ectopic bone formation subsequent to Achilles tenotomy and also following the implantation of demineralized bone matrix in the muscle of rats. Three experiments were performed. The first was designed to investigate the relationship between zinc and calcium concentration during the formation of ectopic bone in rats fed a commercial laboratory ration, the second concerned the effects of dietary zinc deficiency on ectopic bone formation, and the third studies the subsequent effects of dietary zinc repletion on ectopic bone formation. The results indicated that, with the commercial ration, zinc increased concomitantly with calcium during ectopic bone formation in rats. Dietary zinc deficiency caused a retardation of ectopic bone formation and a significant reduction of in situ zinc and calcium concentration. Dietary zinc repletion to zinc-deficient animals restored the zinc concentration in ectopic bone to a level comparable to that of zinc-sufficient animals. Thus, these experiments present strong evidence that zinc plays an active role in bone metabolism.