Reduced sensory neuron regeneration by C57BL/6J mice

The tube repair method was used to study peripheral nerve regeneration in five different inbred mouse strains. The sciatic nerve of male adult mice of the C57BL/6J,DBA/1J, C3H/HeJ, BALB/cJ and A/J strains (N=3) was cut and both proximal and distal nerve stumps were inserted into a polyethylene tube leaving a 4-mm nerve gap. After 6 weeks the tubes containing the regenerated nerve cables were processed for total myelinated axon counts. C57BL/6J mice regenerated significantly fewer myelinated axons (1024 + or - 178, mean + or - SEM) compared to the BALB/cJ (1618+ or - 64), a/j (1788 + OR - 95), dba/1j(2168 + OR - 296) OR c3h/hEj (3468 + OR - 36) strains. Horseradish peroxidase was applied 3 mm distal to be tube 4 and 40 weeks after tube implantation to further characterize the reduced regenerative response of C57BL/6J mice. Labeled sensory and somatic motor neurons were counted in the spinal cord and L4,5,6 dorsal root ganglia (DRG), respectively. Sciatic nerves from four intact C57BL/6J mice were processed in the same fashion and used as normal controls. No significant difference in the number of motor neurons was detected between the experimental (4 weeks = 663 + or - 13) animals. However, there were fewer labeled neurons in the DRG of the operated group (4 weeks = 1163 + or - 167; 40 weeks = 2574 + or - 104) compared to the control group (4211 + or - 96). These results indicated that sensory neurons are responsible for the diminished regenerative response in C57BL/6J mice after peripheral nerve transection. Neurotrophic factors may be implicated in the reduced response, although no systematic study has been done to quantify either trophic factors or their receptor synthesis in different mouse strains during Wallerian degeneration. Diminished peripheral nerve fiber regeneration makes the C57BL/6J mouse strain an ideal experimental model to evaluate the effects of exogenous substances on nerve repair

Local addition of monosialoganglioside GM1 stimulates peripheral axon regeneration in vivo

Tubulization repair technique is a useful model to study peripheral nerve regeneration by offering quantifiable parameters to assess the possible effect of exogenously applied substances on nerve repair. In the present study we demonstrated that locally administered GM1 inside a tubular prosthesis at the time of implantation can significantly improve the repair process. The sciatic nerve of 8 male C57BL/6J mice, approximately 3 months old at the time of surgery and divided into two groups of 4 animals each, was transected and the proximal and distal nerve stumps were sutured into a polyethylene tube (PT), 0.76 mm internal diameter (ID), to bridge a nerve gap of 4 mm. The tubes contained 2 microliters of collagen type I (2.4 mg/ml) alone or in combination (1:1 volume ratio) with monosialoganglioside GM1 (10 mg/ml in the final solution). Four additional animals received a PT with 1.14 mm ID filled with 5.5 microliters of collagen/GM1 (at the same ratio and final concentration as above). After 6 weeks the PT with the regenerating nerve cables were processed for total myelinated axon counts with a computer-controlled system. GM1 significantly increased peripheral axon regeneration (3427 +/- 64 myelinated axons for the 0.76-mm PT and 3623 +/- 270 for the 1.14-mm PT, mean +/- SEM) compared to the group receiving collagen alone (2516 +/- 156) and this effect did not depend on tube diameter. This action is possibly due to a stimulating effect of GM1 on neurite outgrowth and sprouting

Tétano / Tetanus

Os autores apresentam etiologia, sintomas, diagnósticos, diagnóstico diferencial e tratamento do tétano, e chamam a atençäo para os dados laboratoriais, terapêuticos e o prognóstico da doença.

Effect of caffeine administration on latent learning ability of male rats in a simple maze task

The proximal and distal stumps of severed mouse sciatic nerves were inserted into opposite ends of polyethylene tubes. The tubes were implanted either empty ofr filled with collagen alone or in combination with interleukin-1 (IL1). Six weeks later, neurons in the L3-L5 dorsal root ganglia were back-filled with HRP. The number of HRP reactive sensory neurons detected in the IL1-treated animals was significantly greater than that seen in the other experimental groups. Thus, exogenous IL1 may partially mimic the effects obtained with in vivo administration of nerve growth factor in protecting sensory neurons from lesion-induced death

Exogenous ganglioside stimulation of axonal regeneration after new transection and entubulation repair

Adult male mice received sciatic nerve transection at the midthigh level and both nerve stumps were sutured into a polythylene tube (PT) to bridge a nerve gap of 4 mm. The tubes were implanted either empty, or filled with collagen alone or in combination with gangliosides (GM1, GD1a, GD1b, anhd GT1b). Following a survival time of 6 weeks, the PT with the regenerating nerve cables were processed for plastic embedding, and morphometric measurements were made on myelinated and unmyelinated axons. The data suggest that local application of exogenous gangliosides causes a stimulation of axonal sprouting in vivo with no effefct on the rate of axonal maturation

Addition of nerve growth factor to the interior of a tubular prosthesis increases sensory neuron regeneration in vivo

The sciatic nerve of adult mice was transected and the proximal and distal nerve stumps were sutured into a polyethylene tube. The tubes were implanted either umpty, or the lumen was filled with pure collagen or a mixture of collagen/nerve trowth factor (NGF). Six weeks later, cells in the L3-L5 dorsal root ganglia (DRG) were retrogradely filled with horseradish perocidase (HRP). The data demonstrate that the addition of NGF to the interior of the tubular prosthesis can significantly increase the regeneration rate of sensory neurons

Morphometric relationships between satellite and nerve cells in the sensory lumbar ganglia of the domestic fowl in different pre-and post-hatching stages

Foi feito um estudo combinado a microscopia óptica e eletrônica em embriöes de 10 a 18 dias e em espécimens de 8, 35, 61, e 120 dias após a eclosäo de galo doméstico. O volume nuclear da célula nervosa, praticamente näo varia após o 18ª dia de incubaçäo enquanto que, considerável aumento do mesmo volume para células satélites foi observado. O volume citoplasmático varia intensa e progressivanebte para ambos os tipos de células, sendo menor para célula nervosa. Há relativa proporcionalidade de aumento de volume para ambos os tipos de células, sendo contudo, mais intenso para células satélites. Säo feitas consideraçöes de ordem morfofuncional