Immunohistochemical study of fetal stem/progenitor cells from human brain transplanted into traumatized spinal cord of adult rats.

Neural stem/progenitor cells from human fetal brain were grown in a tissue culture and transplanted into traumatized spinal cord of adult rats. The behavior and differentiation of transplanted cells were studied morphologically by means of histological and immunohistochemical methods and confocal microscopy. Human neural stem/progenitor cells were viable for not less than 3 months. They migrated and differentiated into neurons and glia in the traumatized spinal cord of adult rats.

Xenotransplantation of stem/progenitor cells from human fetal brain to adult rats with spinal trauma.

In vitro grown neural stem cells from human fetal brain were transplanted to adult rats with spinal trauma. The spinal cord was examined morphologically using histological and immunohistochemical methods on days 5, 15, 30, and 110. Human neural stem/progenitor cells were viable, migrated, and differentiated into neurons and glia in the traumatized spinal cord in adult rats.

The effects of glycerol and urea on the ultrastructure and contractility of fast and slow rat skeletal muscles.

The influence of the influx and efflux of glycerol and urea (400 mmol/l) on the amplitude of isometric twitches and the ultrastructure of isolated fast (EDL) and slow (SOL) muscles of young rats was studied. The influx of non-electrolytes was accompanied by a temporary decrease in the twitch tension. The removal of non-electrolytes resulted in a stable reduction of twitches. Both effects were less pronounced in glycerol experiments on slow muscles. The inhibition of twitches after the removal of non-electrolytes was associated with selective alterations of the T-system: swelling, vacuolation, and lysis of T-tubules. Quantitative analysis of the T-system showed that the extent of these changes may vary for different fibres, and the intensity of morphological alteration of the T-system generally correlated with the degree of twitch inhibition. Reloading of muscles with non-electrolytes tended to improve the T-system structure in some fibres and led to a partial restoration of the amplitude of twitches.

Inhibition of caffeine contractures of slow rat muscles by urea and its derivatives.

Contractures induced by rapid cooling of rat soleus muscles in the presence of low concentrations of caffeine (2-3 mmol.l-1) have been studied. Urea, methylurea and 1,3-dimethylurea inhibit reversibly these contractures as well as caffeine contractures (20 mmol.l-1, 30 degrees C) but do not affect twitches. This finding leads support to the idea of the existence of different mechanisms activating contraction in response to caffeine action or deplorization.

[Effect of low-molecular nonelectrolytes on caffeine skeletal muscle contracture in the rat]. / Vliianie nizkomolekuliarnykh neélektrolitov na kofeinovuiu kontrakturu skeletnykh myshts krysy.

Contractures induced in rat fast (EDL) and slow (SOL) skeletal muscles by 0.03--3 mM of caffeine in conjunction with rapid cooling of muscle from 30 to 0 degrees C (rapid cooling contructures, RCC) were studied. Uprising speed and tension of RCC were dependent on caffeine concentration and cooling gradient. The minimal necessary temperature, below which contractures still developed, was +6 degrees. The initial temperature did not play any important role. Optimal conditions for RCC (when its tension reached 80--200% of twitch) were: cooling from 30 to 0 degrees, and concentrations of caffeine being 5 mM for SOL, and 6--7 mM for EDL. Disruption of T tubules caused by the removal of glycerol and urea (400--600 mM) from muscle fibers did not influence the RCC tension. During the first hour of the removal, relaxation rate of RCC was lowered. In the presence of 400 mM of urea and 600 mM of 1.3-dimethylurea (the latter did not disrupt the T-system), RCC was depressed by 90%, and the rate of tension development was greatly lowered, while twitches remained unchanged. This effects could be reversed during non-electrolyte removal. This may suggest that Ca2+ release is inhibited selectively by urea and by dimethylurea.

[Effect of glycerin and urea on rat skeletal muscle twitches]. / Vliianie glitserina i mocheviny na odinochnye sokrashcheniia skeletnykh myshts krysy.

The dynamics of changes in the amplitude of isometric twitches of isolated EDL and SOL muscles of young rats influenced by low molecular non-electrolytes has been studied. Incubation of EDL in hypertonic glycerol or urea solution (400 mM) leads to a 80 and 60% decrease of twitches, respectively, within 15 minutes. During the following 1--2 hours the twitches restore the initial level or exceed it by 60% (urea). Removal of glycerol or urea causes a stable reduce of contraction up to 5--10% within 1 hour. Reincubation in these non-electrolytes increases twitches 3--4 fold during 1.5--2 hours. Alterations of SOL twitches in urea are the same as of EDL, while glycerol even in concentration of 600 mM produces only small changes. This appears to be determined by a higher permeability of slow muscle fibers to glycerol as compared to EDL. It is suggested that the decrease of twitches and their restore in non-electrolyte solution are determined by the hypertonic effect of the latter while reduction of twitches during non-electrolyte removal is caused by alteration of T-system.