Ectopic development of skeletal muscle induced by subcutaneous transplant of rat satellite cells

The present study analyzes the ectopic development of the rat skeletal muscle originated from transplanted satellite cells. Satellite cells (10(6) cells) obtained from hindlimb muscles of newborn female 2BAW Wistar rats were injected subcutaneously into the dorsal area of adult male rats. After 3, 7, and 14 days, the transplanted tissues (N = 4-5) were processed for histochemical analysis of peripheral nerves, inactive X-chromosome and acetylcholinesterase. Nicotinic acetylcholine receptors (nAChRs) were also labeled with tetramethylrhodamine-labeled alpha-bungarotoxin. The development of ectopic muscles was successful in 86 percent of the implantation sites. By day 3, the transplanted cells were organized as multinucleated fibers containing multiple clusters of nAChRs (N = 2-4), resembling those from non-innervated cultured skeletal muscle fibers. After 7 days, the transplanted cells appeared as a highly vascularized tissue formed by bundles of fibers containing peripheral nuclei. The presence of X chromatin body indicated that subcutaneously developed fibers originated from female donor satellite cells. Differently from the extensor digitorum longus muscle of adult male rat (87.9 ± 1.0 æm; N = 213), the diameter of ectopic fibers (59.1 æm; N = 213) did not obey a Gaussian distribution and had a higher coefficient of variation. After 7 and 14 days, the organization of the nAChR clusters was similar to that of clusters from adult innervated extensor digitorum longus muscle. These findings indicate the histocompatibility of rats from 2BAW colony and that satellite cells transplanted into the subcutaneous space of adult animals are able to develop and fuse to form differentiated skeletal muscle fibers.

Comparison of the efficacy of biodegradable and non-biodegradable scintillation liquids on the counting of tritium- and [14C]-labeled compounds

The widespread use of H and 14C in research has generated a large volume of waste mixed with scintillation liquid, requiring an effective control and appropriate storage of liquid radioactive waste. In the present study, we compared the efficacy of three commercially available scintillation liquids, Optiphase HiSafe 3, Ultima-GoldÕ AB (biodegradable) and Insta-Gel-XF (non-biodegradable), in terms of [14C]-glucose and [ H]-thymidine counting efficiency. We also analyzed the effect of the relative amount of water (1.6 to 50 percent), radioisotope concentration (0.1 to 100 nCi/ml), pH (2 to 10) and color of the solutions (samples containing 0.1 to 1.0 mg/ml of Trypan blue) on the counting efficiency in the presence of these scintillation liquids. There were few significant differences in the efficiency of 14C and H counting obtained with biodegradable or non-biodegradable scintillation liquids. However, there was an 83 and 94 percent reduction in the efficiency of 14C and H counting, respectively, in samples colored with 1 mg/ml Trypan blue, but not with 0.1 mg/ml, independent of the scintillation liquid used. Considering the low cost of biodegradable scintillation cocktails and their efficacy, these results show that traditional hazardous scintillation fluids may be replaced with the new safe biodegradable fluids without impairment of H and 14C counting efficiency. The use of biodegradable scintillation cocktails minimizes both human and environmental exposure to hazardous solvents. In addition, some biodegradable scintillation liquids can be 40 percent less expensive than the traditional hazardous cocktails.

Globular and asymmetric forms of acetylcholinesterase in the rat levator ani muscle

The endplate (+EP) and non-endplate (-EP) distribution of molecular formas of acetylcholinesterase (AChE) was compared in the dimorphic levator ani and disphragm muscles from adult male rats. Enzyme activity was measured by the thicholine method and AchE forms were separated on the basis of solubility in sodium phosphate buffer of different ionic strenght. For the dimorphic levator ani muscle, total AchE activity was 342.6 ñ 18.9 nmol ASCh hydrolyzed min-1 muscle-1, 90% of which was globular and predominated in the-EP region (78%). The asymmetric forms were almost exclusively detected in the +EP region (9%). In diaphragm muscler, total AChE activity was 176.7 ñ 11.0 units; 66% was mainly globular and located in the-EP region (56%); the asymmetric forms (34%) were either in -EP (11%) or + EP (23%) regions. Thus, a greater proportion of globular form was presented in the dimorphic levator ani muscle than in diaphragm muscle. In view of the control exerted by testosterone on dimorphic muscles, its is suggested that the grater synthesis of the globular form in the levator ani occurs under the trophic influence of testosterone