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Pure-tone thresholds and speech understanding were studied in three samples of men of different ages (31-35, 51-55 and 71-75 years). The air-conducted pure-tone thresholds were measured at 125-8,000 Hz and speech understanding by the help of interrupted and masked speech tests. The audiological measures were related to measures of other sensory functions, psychomotor speed, cognitive functions, psychic well-being, occupational and educational background and health. The results indicated a clear decrement in all audiological measures when proceeding from younger to older age groups. The results of the speech-understanding tests correlated significantly with the pure-tone thresholds both at 4,000 Hz and at the mean of three frequencies (500, 1,000, 2,000 Hz) in the speech area. The audiological measures were not associated with other sensory functions or psychic well-being but showed significant correlations with psychomotor speed and cognitive functions. The most important predictors of the auditory functions within the age groups were occupational status, noise exposure at work, cognitive capacity, education, and number of disease symptoms, which, in addition, correlated with each other.

As a part of a larger gerontological research project vibrotactile thresholds on the inner malleolus of the ankle were studied in 355 men aged 31-35, 51-55 and 71-75 years. The groups studied were random samples of men living in the town of Jyväskylä in Finland in the year 1981. The thresholds were assessed at three frequencies: 50 Hz, 100 Hz and 250 Hz. The thresholds were associated with age at all frequencies, the means of the threshold values being significantly higher in the older age groups. Within the age groups the thresholds correlated positively with height. In addition, reaction and movement time, leg extension velocity, and postural sway were associated with the thresholds. Neither general health status nor occupational or educational background, or living habits had significant influence on the thresholds within the age groups. The results suggest that the elevation of vibrotactile thresholds is an inherent manifestation of aging in the nervous system. In addition to age, the height of the respondents is among the factors that should be taken into account when interindividual comparisons are made, if the measurement is on distal parts of the body.

Tests of psychomotor and motor speed at different levels of complexity were studied in random samples of men aged 31 to 35, 51 to 55, and 71 to 75 yr. The study was performed as a part of a larger research project on health and functional aging. Analyses indicated significantly slower responses among older men at all levels of test complexity (maximal knee extension velocity, tapping rate, simple and choice reaction and movement times). There were marked differences both between the youngest and the middle-aged groups and between the middle-aged and the oldest groups. Within the age groups high psychomotor and motor speed were associated with a favourable functioning of certain senses (vibration sensitivity and postural balance), with a high isometric muscular force, and with a high directly assessed aerobic capacity. The most important covariants of the speed functions within the age groups were, however, cognitive performance, length of education, and perceived health.

We investigated the metabolic route by which a lignin tetramer-degrading mixed bacterial culture degraded two tetrameric lignin model compounds containing beta-O-4 and 5-5 biphenyl structures. The alpha-hydroxyl groups in the propane chain of both phenolic and nonphenolic tetramers were first oxidized symmetrically in two successive steps to give monoketones and diketones. These ketone metabolites were decomposed through C(alpha)(=O)-C(beta) cleavage, forming trimeric carboxyl acids which were further metabolized through another C(alpha)(=O)-C(beta) cleavage. Dehydrodiveratric acid, which resulted from the cleavage of the carbon bonds of the nonphenol tetramer, was demethylated twice. Four metabolites of the phenolic tetramer were purified and identified. All of these were stable compounds in sterile mineral medium, but were readily degraded by lignin tetramer-degrading bacteria along the same pathway as the phenol tetramer. No monoaromatic metabolites accumulated. All metabolites were identified by mass and proton magnetic resonance spectrometry. The metabolic route by which the mixed bacterial culture degraded tetrameric lignin model compounds was different from the route of the main ligninase-catalyzed C(alpha)-C(beta) cleavage by Phanerochaete chrysosporium.

A case of thrombotic thrombocytopenic purpura (TTP) in a human immunodeficiency virus (HIV)-seropositive homosexual man is reported. The patient improved after corticosteroid and plasma exchange therapy was instituted. The case demonstrated most of the classic features of TTP, including histologic evidence of fibrin thrombi in small blood vessels. Atypical features included reduced number of megakaryocytes in the bone marrow and only partial resolution of thrombocytopenia after therapy was begun. An autoimmune thrombocytopenia has been well-characterized in HIV-antibody-seropositive homosexual men. Physicians caring for HIV-seropositive persons should also be aware of a possible association with TTP.