The aim of this study was to investigate the response of protein synthesis rate, particularly myosin heavy chain (MyHC) isoforms synthesis and the magnitude of its isoform transformation in fast-twitch plantaris muscle, to different modes of prolonged mechanical loading. Different protocols of mechanical loading were used: resistance training (RT), compensatory hypertrophy (CH) of m. plantaris after tenotomy of m. gastrocnemius and a combination of the two previous loadings (RT + CH). During the different modes of loading, plantaris muscle hypertrophy in RT group was approximately 10 %, CH approximately 40 % and CH + RT approximately 44 %. MyHC I and IID isoform synthesis rate increased in all experimental groups, as well as their relative content. MyHC IIA relative content decreased during RT and RT + CH and increased during CH. MHC IIB isoform relative content decreased in all experimental groups, but compared with CH in CH + RT MyHC IIB isoform content increased in plantaris muscle. These results demonstrate that different modes of mechanical loading resulted in the selective up- and down-regulation of MyHC isoforms in fast-twitch skeletal muscle. The synthesis rate and relative content of the two fastest isoforms of MyHC IIB and IID are regulated to different directions during mechanical loading.

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A group of slowly growing mycobacterial strains (n = 14) isolated from respiratory tract specimens was collected from 1971 to 1990 on the basis of growth characteristics and uncommon biochemical and glycolipid profiles. Growth at 25 to 45 degrees C, a negative Tween 80 hydrolysis test, a strong positive reaction in a 14-day arylsulfatase test, and susceptibility to ethambutol in combination with resistance to cycloserine were important for the initial separation. The strains had a distinctive glycolipid pattern which was unlike those of other mycobacterial species. Analyses of cellular fatty acids by gas-liquid chromatography and mycolic acids by thin-layer chromatography further characterized this homogeneous group of mycobacteria. The presence of 2-eicosanol (2-OH-20:0alc) and hexacosanoic acid (26:0) combined with the lack of 2-docosanol (2-OH-22:0alc) differentiated this group from other slowly growing mycobacteria.