Age-related changes in rat muscle collagen

Age-related studies of collagen in slow, fast and cardiac muscle of the rat indicate that different fractions of collagen as well as total collagen content vary with age and type of muscle. The total collagen level increases by 30% in slow, 40% in fast and 50% in cardiac muscle as age advances from 5 to 25 months. Collagen of the muscles of old animals is less susceptible to the collagen-degrading enzyme when compared to the young, and the activity of the enzyme decreases significantly with age. The decrease in (1) the solubility of collagen; (2) the amount of hydroxyproline released at 65 degrees C, and (3) the increase in the resistance of collagen to the degrading enzyme seen with aging, indicates that the stability of collagen increases in these muscles with aging.

The occurrence and treatment of false positive reactions in enzyme-linked immunosorbent assays (ELISA) for the presence of fungal antigens in clinical samples

Non-specific positive reactions have been revealed in enzyme-linked immunosorbent assays (ELISA) of sera for the presence of fungal antigen. These false positives were recognized by their occurrence in tests for both Candida albicans and Aspergillus fumigatus antigens and by their response to dithiothreitol, combined with their reaction with non-immune rabbit globulin. A scheme is proposed which differentiates between true and false positive reactions. Use of fractionated anti-fungal globulin in conjugates reduced the incidence of false positive results in sera from hospitalized patients and eliminated them from sera of healthy subjects. The test scheme was applied to two panels of sera containing samples from patients with (a) invasive candidosis and (b) invasive aspergillosis. The relevance of ELISA tests for the detection of fungal antigen in human serum is discussed.

Age related changes in muscle protein degradation

In vitro autolytic degradation of sarcoplasmic proteins in red, white and cardiac muscles increases with advance in age and with increase in temperature, the rate varying with age. Higher activity is seen in the alkaline range in all age groups. Ca2+ activated proteolytic activity also increases with advance in age.

Collagen in aging muscles

The salt, acid and insoluble collagen fractions were estimated in red, white and cardiac muscles of 10-, 15- and 20-month-old albino rats. The total collagen level with reference to total proteins is more in red than in white and cardiac muscle. Accumulation of more of insoluble collagen and decrease in salt extractable collagen is seen in all three muscles with aging.