Modulation of follistatin and myostatin propeptide by anabolic steroids and gender.

The purpose of this pilot study was to investigate the impact of training, anabolic steroids and endogenous hormones on myostatin-interacting proteins in order to identify manipulations of myostatin signalling. To identify whether analysis of the myostatin interacting proteins follistatin and myostatin propeptide is suitable to detect the abuse of anabolic steroids, their serum concentrations were monitored in untrained males, bodybuilders using anabolic steroids and natural bodybuilders. In addition, we analysed follistatin and myostatin propeptide serum proteins in females during menstrual cycle. Our results showed increased follistatin concentrations in response to anabolic steroids. Furthermore, variations of sex steroid levels during the menstrual cycle had no impact on the expression of follistatin and myostatin propetide. In addition, we identified gender differences in the basal expression of the investigated proteins. In general, follistatin and myostatin propeptide concentrations were relatively stable within the same individual both in males and females. In conclusion, the current findings provide an insight into gender differences in myostatin-interacting proteins and their regulation in response to anabolic steroids and endogenous hormones. Therefore our data provide new aspects for the development of doping prevention strategies.

Structural and functional implications of age-related abnormal modifications in collagen II from intervertebral disc.

Collagen II was isolated from annulus fibrosus of human donors, and the degree of enzymatic glycosylation and the extent of nonenzymatic modification was determined as a function of age. While enzymatic glycosylation did not alter with age, the fluorescence as a measure of nonenzymatic modification increased, in particular in those fractions containing highly cross-linked collagen molecules. The age-dependent increase of fluorescence was associated with a lower thermal stability of collagen II, being lowest (Tm = 36.9 degrees C instead of 42.1 degrees C) in a fraction of collagen II molecules isolated from tissue of a 69-year-old donor. In addition, collagen II from elderly donors showed an impaired propensity to form fibrils, using an in vitro assay, as evidenced by the facts that (1) more collagen molecules remained in solution and were not assembled into fibrils, and (2) the relative turbidity caused by the aggregates progressively decreased as the age of the donors increased. As seen on electron micrographs, these fibrillar aggregates were less densely packed and intermingled with precipitates such as unbanded filaments or discontinuous fibrils with split and frayed regions. It can be hypothesized that functional impairment of the intervertebral disc with aging may be caused in part by molecular alterations as are described here for collagen II obtained from aged donors.

In vitro formation and aggregation of heterotypic collagen I and III fibrils.

In vitro fibrillogenesis of solutions containing pepsin digested and acid soluble collagens I and III from human and bovine skin were investigated by turbidity-time measurements, dark-field and electron microscopy. The maximum turbidity of these solutions exhibited inversely proportional dependence on the collagen III content. Self-assembly was accelerated by collagen III. As a measure of mass per unit length, the maximum turbidity shows a mean decrease of 88% when comparing the absorbance at 313 nm for 0% and 50% collagen III in a composite solution of acid extracted collagen. In contrast to these findings, the diameter of fibrils from acid extracted fetal calf skin with 50% collagen III, determined from electron micrographs, was only 23% smaller than for pure collagen I. Correspondence with investigations on in vitro fibrillogenesis with dark-field microscopy and electron microscopy, this phenomenon apparently derives from the bundling of fibrils. This may be interpreted to mean that bundling of fibrils is already suppressed at low collagen III concentrations. A comparison of acid and pepsin extracted fetal calf skin yielded similar behaviour of collagen I and III mixtures, even though the pepsin extract displayed a turbidity reduction that was about 25% less than the acid extract. For pepsin digested collagen from human and bovine skin, differences were found for maximum turbidity and the ability to form bundles decreasing with the biological age of the donor.

Collagen II from articular cartilage and annulus fibrosus. Structural and functional implication of tissue specific posttranslational modifications of collagen molecules.

Collagen II was isolated and characterized from hyaline cartilage (articular cartilage) and fibro-cartilage (annulus fibrosus). Collagen II from the latter tissue has a substantially higher degree of hydroxylation and glycosylation than that isolated from articular cartilage. The higher degree of posttranslational modification was associated with a slower electrophoretic mobility, a greater resistance to mammalian collagenase digestion and a higher thermal stability. An increase of glycosylation accelerates the initial steps in fibril formation of collagen molecules but slows down the following lateral growth. The newly formed aggregates of collagen II from annulus fibrosus consisted of fibrils with a smaller diameter.

Comparative study on the thermostability of collagen I of skin and bone: influence of posttranslational hydroxylation of prolyl and lysyl residues.

Pepsin-solubilized collagen I from skin and bone was analyzed with regard to its thermal stability as a triple helical molecule in solution and after in vitro fibril formation. Collagen I from human control bone was compared with samples showing deficiencies or surplus in the degree of hydroxylation of lysine. The helix to coil transitions were studied by circular-dichroism measurements and limited trypsin digestion. Melting of fibrils from standardized in vitro self-assembly was investigated turbidimetrically. Human control bone collagen I has a maximum transition rate (Tm) at 43.3 degrees C in 0.05% acetic acid. This is 1.9 degrees C above control skin (Tm = 41.4 degrees C), most likely, due to a higher degree of prolyl hydroxylation--0.48 in bone vs. 0.41 in skin collagen I. Lysyl overhydroxylation of human and mouse bone collagen I appears to reduce the Tm slightly (approximately 1 degree C). Underhydroxylated bone collagen has a Tm which is 2 degrees C below control. Melting temperatures of in vitro formed fibrils are an indication for higher thermostability in parallel with an increase of lysyl hydroxylation. Accordingly, the melting temperature of such fibrils from human control skin, 49.3 degrees C, exceeds control bone by 1.4 degrees C. The degree of lysyl hydroxylation in these samples is 0.14 and 0.10, respectively. Further underhydroxylation (0.06) reduced it down to 45.4 degrees C, while extensive overhydroxylation did not continue to increase the thermal stability of fibrils.

[Iritis and optic nerve meningitis--initial symptoms of latent syphilis]. / Iritis und Opticus-Meningitis--Erstsymptome einer Lues latens.

A 19-year-old woman presented in the latent phase of secondary syphilis with chronic bilateral anterior uveitis and a slightly elevated optic disk with indistinct margins in the left eye; this was interpreted as a meningitis of the optic nerve. Serologic examination revealed the syphilitic infection, which had not previously been apparent. The symptoms resolved completely after specific therapy.