Ultrasound imaging of chitosan nerve conduits that bridge sciatic nerve defects in rats

The repair of peripheral nerve injuries with autologous nerve remains the gold standard （Wang et al., 2005; Yao et al., 2010; Deal et al., 2012; Kriebel et al., 2014; Liu et al., 2014; Tamaki et al., 2014; Yu et al., 2014; Zhu and Lou, 2014）. With advances in tissue engineering and biomaterials, tissue-engineered nerve conduits with various biomaterials and structures, such as collagen and chitosan nerve conduits, have already been used in the clinic as alternatives to autologous nerve in the repair of peripheral nerve injury （Wang et al., 2012; Svizenska et al., 2013; Eppenberger et al., 2014; Gu et al., 2014; Koudehi et al., 2014; MoyaDiaz et al., 2014; Novajra et al., 2014; Okamoto et al., 2014; Shea et al., 2014; Singh et al., 2014; Tamaki et al., 2014; Yu et al., 2014）. Therefore, new simple and effective methods

Anatomical peculiarities of sensory tracts of the wrist median nerve pedicled with nutrient vessels transferring to bridge wrist ulnar nerve defect

BACKGROUND： Translocation or transplantation of nerve stem has good effect; however, nervous function of donator is completely lost. If some nerve stem is damaged, sensory tracts are intercepted from the near nerve stem by nutrient vessels to regard as neural graft for transferring and bridging which may repair injured nerve and decrease neural functional loss of donator. OBJECTIVE： To observe anatomical peculiarities on sensory tracts of wrist median nerve pedicled with nutrient vessels transferring to bridge wrist ulnar nerve defect, and to investigate its feasibility. DESIGN：Duplicated and measured design.SETTING ： Anatomy Department of Medical College affiliated to Nanhua University.MATERIALS： A total of 14 samples of upper limbs were selected from adult unnamed corpse and volunteers.METHODS： The experiment was completed at the Clinical Application Anatomy Laboratory of Medical College affiliated to Nanhua University from September to November 2005. Samples were perfused with red emulsion through artery to observe length, fibrous bands and blood supply of median nerve and ulnar nerve at wrist. Boundary of median nerve at wrist ranged from superficial site between flexor carpi radialis and palmaris Iongus to branch of common palmar digital nerves. Ulnar nerve at wrist ranged from branch of back of the hand to site of common palmar digital nerves. Proximal boundary of the two nerves was crossed from 1/8 to 2/8 region of forearm. Samples of upper limbs from 1 case were selected to simulate operation on sensory tracts of wrist median nerve pedicled with nutrient vessels transferring to bridge wrist ulnar nerve. MAIN OUTCOME MEASURES： Anatomical peculiarities on sensory tracts of wrist median nerve pedicled with nutrient vessels transferring to bridge wrist ulnar nerve defect. RESULTS： ① The length of wrist median nerves was 7.8 （7.5-8.1） cm. There were 19 to 27 nerve tracts in it and the majority belonged to sensory tracts on the ulnar side, in which non-damaged separated length was about 10.0 cm to 14.0 cm. The third, second and first tracts of cutaneous branches at digital interspace and radialis of thumb arrayed from ulnaris to radialis by turns, and numbers of bands were 6.9, 7.4 and 7.2, respectively. The bands in total were 21.6. Cutaneous branches of palm entered from lateral margin of radialis and were completely separated at wrist. Two-thirds of ulnaris at nerve stem, i.e. the third, second and first tracts of cutaneous branches at digital interspace, were separated, which had little effect on sensation in distribution of median nerve. ② Its nutrient vessels originated from radial arteries about 6.2 （6.1-6.6） cm above radial styloid process were 1.2 （1.1-1.4） mm in outer diameter. The length was 5.7 （5.1-6.1） cm.③ The length of wrist ulnar nerve were 9.4 （8.9-9.7） cm and the number of nervous tract were 14 to 19, in which sensory tracts on the anterior external side were approximately equal to motor and mixed tracts on the posterior internal side in quantity. Sensory tracts were located at radialis of palm and motor tracts were located at ulnaris of back. CONCLUSION ：① Character and position of median nerve fibre bundle are clear, and length of non-damage separation of sensory tracts is coincidence with the request of transferring to bridge. ② Summation of the third, second and first tracts of cutaneous branches at digital interspace may be satisfactory to bridge of ulnar nerve at wrist （14-19 bands）. ③ This technique has little effect on sensation in distribution of median nerve. Nutrient artery of median nerve locates constantly; journey table is superficial and is easily to find out; caliber of arterial canal is thick; blood supply is plentiful; length of pedicel is suitable for translocation. The sensery tracts of wrist median nerve pedicled with nutrient vessels can be applied as nervous grafts to join injured gap in wrist ulnar nerve.

The progress in optic nerve regeneration, where are we?

Optic nerve regeneration is an important area of research. It can be used to treat patients suffering from optic neuropathy and provides insights into the treatment of numerous neurodegenerative diseases. There are many hurdles impeding optic regeneration in mammals. The mammalian central nervous system is non-permissive to regeneration and intrinsically lacks the capacity for axonal regrowth. Any axonal injury also triggers a vicious cycle of apoptosis. Understanding these hurdles provides us with a rough framework to appreciate the essential steps to bring about optic nerve regeneration： enhancing neuronal survival, axon regeneration, remyelination and establishing functional synapses to the original neuronal targets. In this review article, we will go through current potential treatments for optic nerve regeneration, which includes neurotrophic factor provision, inflammatory stimulation, growth inhibition suppression, intracellular signaling modification and modeling of bridging substrates.