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Biomedical subjects

N Kalderon

Publications and source records attributed to N Kalderon.

21 records · Page 2Linked to original sources

Differentiating astroglia in nervous tissue histogenesis/regeneration: studies in a model system of regenerating peripheral nerve.

The role of astroglia in nervous system histogenesis/regeneration (morphogenesis) was studied as a function of cell age. The effect of inoculated astroglia at different cell maturation stages on axonal growth was examined in a peripheral nerve regenerating model system. This model system consists of rat sciatic nerve stumps that regenerate through an empty silicone chamber (Lundborg et al.: Journal of Neuropathology and Experimental Neurology 41:412-422, 1982). Rat astroglial cell populations grown in cell culture were suspended either in a liquid (physiological solution) or in a solid (isotonic collagen gel) medium and inoculated within the silicone chamber at the time of surgery. Immature and mature cell populations, at ages corresponding to 9-69 postnatal days (P9-P69), were inoculated, and their effect on neural growth was analyzed by histological, immunocytochemical, and ultrastructural techniques, 2-6 weeks later. Astroglial cells differentially modulated the process of nerve regeneration, an effect that is a function of the cells' developmental stage. P19 astroglia and older cells inhibited the regeneration process, encapsulating the axons in a glia-limitans-like structure. Immature astrocytes (P9) did not seem to interfere with the regeneration process; nerve outgrowth in their presence resembled and was comparable to the ones obtained in the presence of inoculated Schwann cells. The differential effects of the developing astroglia were not significantly changed by the inoculation media, e.g., liquid or solid, and were already pronounced 2 weeks after neural transection. It is suggested by the results of the study that the role and function of astroglia in nervous system morphogenesis are changing with cell differentiation. Adult astrocytes seem to downregulate axonal growth; presumably, their function is to confine the neurites within designated structural and functional boundaries.

Animals↗

Aloe vera gel hindered wound healing of experimental second-degree burns: a quantitative controlled study.

In the present study, Aloe vera gel (AVG) was applied to experimental second-degree burns in guinea pigs, and its effects on epithelialization, wound contraction, newly formed granulation tissue, and regeneration of hair follicles was compared with that effected by 1% silver sulfadiazine cream (AgSD). Epithelialization (%mean +/- SEM) on postburn day 8, 16, and 24 of the AVG-treated wounds was 38.72% +/- 2.71%, 60.34% +/- 3.28%, and 92.46% +/- 2.26%, respectively, while that of the AgSD-treated burns was 53.35% +/- 2.65%, 94.84% +/- 2.65%, and 100%, respectively (P less than .001). Contraction of the AVG-wounds was significantly higher than that of the AgSD-treated burns during 24 days of the study (P less than .001). The thickness of the newly formed granulation tissue was higher in the AVG-treated wounds (P less than .001), while the hair follicles count was significantly lower (P less than .001) compared with the AgSD-treated burns. It is concluded that this preparation of Aloe vera gel hindered the healing process of the present burn wound model when compared with 1% silver sulfadiazine cream.

Administration, Cutaneous↗