Glial cell line-derived neurotrophic factor is a key neurotrophin in the postnatal enteric nervous system.

BACKGROUND: The enteric nervous system (ENS) continues its structural and functional growth after birth, with formation of ganglia and the innervation of growing smooth muscle. However, little is known about factors in the postnatal intestine that influence these processes. METHODS: We examined the presence and potential role of glial cell line-derived nerve growth factor (GDNF) in the rat postnatal ENS using neonatal tissue, primary co-cultures of the myenteric plexus, smooth muscle, and glial cells as well as cell lines of smooth muscle or glial cells. KEY RESULTS: Western blot analysis showed that GDNF and its co-receptors rearranged during transfection (RET) and GDNF family receptor alpha-1 were expressed in the muscle layer of the neonatal and adult rat intestine. Immunohistochemistry localized the receptors for GDNF to myenteric neurons, while GDNF was localized to smooth muscle cells. In a co-culture model, GDNF but not nerve growth factor, brain derived neurotrophic factor or neurotrophin-3 significantly increased neuronal survival and more than doubled the numbers of neurites in vitro. RT-PCR, qPCR, Western blotting, ELISA, and immunocytochemistry as well as bioassays of neuronal survival and of RET phosphorylation all identified intestinal smooth muscle as the source of GDNF in vitro. GDNF also induced morphological changes in the structure and organization of neurons and axons, causing marked aggregation of neuronal cell bodies and collinear development of axons. As well, GDNF (50-150 ng mL(-1)) significantly increased [(3)H]-choline uptake and stimulated [(3)H]-acetylcholine release. CONCLUSIONS & INFERENCES: We conclude that GDNF derived from intestinal smooth muscle cells is a key factor influencing the structural and functional development of postnatal myenteric neurons.

Assessing recovery in middle cerebral artery stroke using functional MRI.

PRIMARY OBJECTIVE: To understand the temporal evolution of brain reorganization during recovery from stroke. RESEARCH DESIGN: A patient who suffered left middle cerebral artery stroke 9 months earlier was studied on three occasions, approximately 1 month apart. METHODS AND PROCEDURES: Brain activation was studied using functional Magnetic Resonance Imaging (fMRI). During each session, the patient performed a finger-to-thumb opposition task, which involved one bimanual and two unimanual conditions. Each condition consisted of overt movement of fingers and imagery of the same task. RESULTS: With recovery, greater recruitment was observed of the affected primary motor cortex (M1) and a decrease in activation of the unaffected M1 and supplementary motor area. In addition, the widespread activation of brain areas seen during the initial session changed to a more focused pattern of activation as the patient recovered. Imagery tasks resulted in similar brain activity as overt execution pointing to imagery as a potential tool for rehabilitation.

Evaluation of the sharpness of concentric needle electrodes by a penetration test.

This paper deals with a method to evaluate the sharpness of the concentric needle electrode (CNE) and the consistency of sharpness on repeated penetration. An aluminum foil of standard thickness and properties was used as the penetration medium. A load profile was obtained as a function of time, and has been correlated with the shape and quality of grinding of the tip of the CNE. This load profile can be used as a quality evaluation method. This method is utilized for the assessment of the impairment of the needle tip on repeated penetration and hence for comparison of different needle electrode models.

Left atrial femoral bypass and cerebrospinal fluid drainage decreases neurologic complications in repair of descending and thoracoabdominal aortic aneurysms.

This study was undertaken to evaluate the role of cerebrospinal fluid (CSF) drainage and left atrial to femoral artery (LAFA) bypass in preventing postoperative neurologic complications for patients who had undergone descending and thoracoabdominal aortic aneurysm (TAAA) repair. LAFA bypass and CSF drainage were used as adjuncts in the treatment of 8 patients with descending and 13 patients with TAAAs (December 1999 to March 2000). LAFA bypass was established with the use of a centrifugal Biomedicus pump. Distal flows were maintained between 1.5 and 2.5 L/min during the procedures. Mean LAFA bypass time was 40 (range, 21 to 60 min). The CSF pressure was kept below 10-12 mmHg during the operations and for the first 72 hr postoperatively. All patients received heparin (1 mg/kg), which was reversed at the completion of the procedure. Passive hypothermia (rectal temperature: 32 degrees-34 degrees C) was used in all cases. All patent T8-L1 intercostal arteries were reattached to the graft. There were 13 men and 8 women. The median age was 56 years (range, 49 to 78). Chronic aortic dissection was the cause of the aneurysm in 9 patients (43%), trauma in 1 patient (5%), and medial degeneration in 11 patients (52%). There were four type I (19%), four type II (19%), and five type III (24%) TAAA. In eight patients (38%) the entire descending thoracic aorta was aneurysmal. Our results showed that the use of CSF drainage and LAFA bypass prevents paraplegia/paraparesis after repair of thoracoabdominal and descending thoracic aneurysms.