Regional differences in responsiveness of adult CNS axons to grafts of cells expressing human neurotrophin 3.

Neurotrophin 3 (NT3) belongs to the neurotrophin family, which also includes nerve growth factor, brain-derived neurotrophic factor, and neurotrophin 4/5. NT3 mRNA is widely expressed in the rodent nervous system, but the physiological function of the native protein is still unclear. Genetically modified cell lines that produce physiological amounts of NT3 can provide a useful tool in the elucidation of the NT3 effects in the adult central nervous system (CNS). Genetically modified rat primary skin fibroblasts expressing and secreting human NT3 (hNT3) were prepared and characterized. In vitro, cell lines derived from different retroviral constructs expressed hNT3 mRNA, as determined by PCR and RNA blot analysis. Secretion of biologically active hNT3 was confirmed by specific elicitation of neurite outgrowth from cultured chick primary sympathetic and sensory neurons and from rat fetal locus coeruleus neurons in the presence of hNT3-producing cell conditioned media. In vivo, implanted fibroblasts survived well up to the maximal experimental time points of 6 weeks (brain) and 4 weeks (spinal cord) and continued to express hNT3 mRNA in vivo. As early as 2 weeks postgrafting, specific sprouting of host sensory neurites in response to hNT3-producing grafts was observed in the spinal cord. In contrast, hNT3-producing cerebral grafts did not induce a sprouting response different from that observed with control grafts. These findings establish the existence of a regionally different responsiveness of the CNS axons to local hNT3 overexpression.

New stereotactic technique for percutaneous thermocoagulation upper thoracic ganglionectomy in cases of palmar hyperhidrosis.

To perform unilateral or bilateral upper thoracic ganglionectomy, we established a three-dimensional system of coordinates for T2 and T3 ganglia. For this purpose, the spatial relations were represented by drawings obtained from 50 Chinese cadavers. A simple stereotactic frame was constructed as an aid in performing the procedure. Then, according to the established three-dimensional system of coordinates, percutaneous thermocoagulation of both T2 and T3 ganglia was performed on 10 patients (20 sides) with palmar hyperhidrosis, under local anesthesia and fluoroscopic guidance at the posteroanterior projection. Excellent relief of abnormal sweating in 19 of the 20 hands was achieved. Partial relief was obtained in the remaining hand. No complication was observed in our patients. The technique has been proved to be safe, effective, and simpler than other methods now in use.