Regeneration of adult rat sensory and motor neuron axons through chimeric peroneal nerve grafts containing donor Schwann cells engineered to express different neurotrophic factors.

Large peripheral nerve (PN) defects require bridging substrates to restore tissue continuity and permit the regrowth of sensory and motor axons. We previously showed that cell-free PN segments repopulated ex vivo with Schwann cells (SCs) transduced with lentiviral vectors (LV) to express different growth factors (BDNF, CNTF or NT-3) supported the regeneration of axons across a 1 cm peroneal nerve defect (Godinho et al., 2013). Graft morphology, the number of regrown axons, the ratio of myelinated to unmyelinated axons, and hindlimb locomotor function differed depending on the growth factor engineered into SCs. Here we extend these observations, adding more LVs (expressing GDNF or NGF) and characterising regenerating sensory and motor neurons after injection of the retrograde tracer Fluorogold (FG) into peroneal nerve distal to grafts, 10 weeks after surgery. Counts were also made in rats with intact nerves and in animals receiving autografts, acellular grafts, or grafts containing LV-GFP transduced SCs. Counts and analysis of FG positive (+) DRG neurons were made from lumbar (L5) ganglia. Graft groups contained fewer labeled sensory neurons than non-operated controls, but this decrease was only significant in the LV-GDNF group. These grafts had a complex fascicular morphology that may have resulted in axon trapping. The proportion of FG+ sensory neurons immunopositive for calcitonin-gene related peptide (CGRP) varied between groups, there being a significantly higher percentage in autografts and most neurotrophic factor groups compared to the LV-CNTF, LV-GFP and acellular groups. Furthermore, the proportion of regenerating isolectin B4+ neurons was significantly greater in the LV-NT-3 group compared to other groups, including autografts and non-lesion controls. Immunohistochemical analysis of longitudinal graft sections revealed that all grafts contained a reduced number of choline acetyltransferase (ChAT) positive axons, but this decrease was significant only in the GDNF and NT-3 graft groups. We also assessed the number and phenotype of regrowing lumbar FG+ motor neurons in non-lesioned animals, and in rats with autografts, acellular grafts, or in grafts containing SCs expressing GFP, CNTF, NGF or NT-3. The overall number of FG+ motor neurons per section was similar in all groups; however in tissue immunostained for NeuN (expressed in α- but not γ-motor neurons) the proportion of NeuN negative FG+ neurons ranged from about 40-50% in all groups except the NT-3 group, where the percentage was 82%, significantly more than the SC-GFP group. Immunostaining for the vesicular glutamate transporter VGLUT-1 revealed occasional proprioceptive terminals in 'contact' with regenerating FG+ α-motor neurons in PN grafted animals, the acellular group having the lowest counts. In sum, while all graft types supported sensory and motor axon regrowth, there appeared to be axon trapping in SC-GDNF grafts, and data from the SC-NT-3 group revealed greater regeneration of sensory CGRP+ and IB4+ neurons, preferential regeneration of γ-motor neurons and perhaps partial restoration of monosynaptic sensorimotor relays.

Immunohistochemical, ultrastructural and functional analysis of axonal regeneration through peripheral nerve grafts containing Schwann cells expressing BDNF, CNTF or NT3.

We used morphological, immunohistochemical and functional assessments to determine the impact of genetically-modified peripheral nerve (PN) grafts on axonal regeneration after injury. Grafts were assembled from acellular nerve sheaths repopulated ex vivo with Schwann cells (SCs) modified to express brain-derived neurotrophic factor (BDNF), a secretable form of ciliary neurotrophic factor (CNTF), or neurotrophin-3 (NT3). Grafts were used to repair unilateral 1 cm defects in rat peroneal nerves and 10 weeks later outcomes were compared to normal nerves and various controls: autografts, acellular grafts and grafts with unmodified SCs. The number of regenerated ßIII-Tubulin positive axons was similar in all grafts with the exception of CNTF, which contained the fewest immunostained axons. There were significantly lower fiber counts in acellular, untransduced SC and NT3 groups using a PanNF antibody, suggesting a paucity of large caliber axons. In addition, NT3 grafts contained the greatest number of sensory fibres, identified with either IB4 or CGRP markers. Examination of semi- and ultra-thin sections revealed heterogeneous graft morphologies, particularly in BDNF and NT3 grafts in which the fascicular organization was pronounced. Unmyelinated axons were loosely organized in numerous Remak bundles in NT3 grafts, while the BDNF graft group displayed the lowest ratio of umyelinated to myelinated axons. Gait analysis revealed that stance width was increased in rats with CNTF and NT3 grafts, and step length involving the injured left hindlimb was significantly greater in NT3 grafted rats, suggesting enhanced sensory sensitivity in these animals. In summary, the selective expression of BDNF, CNTF or NT3 by genetically modified SCs had differential effects on PN graft morphology, the number and type of regenerating axons, myelination, and locomotor function.

Localized myxedema of the foot associated with trauma and surgery.

Localized extratibial myxedema is a rare presentation of thyroid disease that manifests with varied symptoms. Previous surgical or radioiodine treatment of hyperthyroidism is linked to the development of localized myxedema, as is prior trauma or surgery. We present the first known case of localized foot myxedema on a background of Graves disease following a traumatic and surgical precipitant and compare and discuss similar cases found in a literature review.

Closed digital artery injury.

Closed digital artery injury with secondary acute ischemia is a rare phenomenon. The most common injury pattern involves a crush mechanism with a resultant transverse fracture in proximity to the interphalangeal joints. Secondary acute ischemia requires urgent surgical exploration with digital arterial repair to avoid necrosis and associated decreased hand function. One should exercise an air of caution when examining significant closed trauma; neurovascular normality should be established by an adequately trained physician. We present a case of closed digital artery injury with secondary acute ischemia and a review of current literature.

Suboptimal preventive practices in patients with carotid and peripheral vascular occlusive disease in a tertiary referral setting.

BACKGROUND: Effective strategies for the prevention of adverse vascular events in patients with atherosclerotic vascular disease include smoking cessation, platelet inhibition, antihypertensives, hypoglycaemic and cholesterol lowering agents. The current literature suggests that these practices are suboptimal in patients with peripheral vascular disease (PVD). This study aims to examine and compare the use of preventive therapy in patients admitted for interventions related to peripheral and carotid atherosclerotic occlusive disease. METHODS: All inpatients undergoing diagnostic or therapeutic procedures for occlusive disease of the lower limb and carotid artery at Royal Perth Hospital, Western Australia, between January 2000 and December 2000 were included in the study. Their medical charts were reviewed to measure the prevalence of the use of antithrombotic, antihypertensive and cholesterol-lowering therapies. RESULTS: Medical charts of 256 patients (97%) were reviewed during the study period. Carotid related procedures accounted for 26% of the sample. Overall, 80% were prescribed antithrombotic (antiplatelet or anticoagulation) therapy at the time of discharge. In the carotid group, 97% were on some form of antithrombotic therapy as opposed to 75% in the PVD group. Antihypertensive and cholesterol lowering therapies were used in 82% and 63%, respectively, of the carotid group vs 68% and 36% in the PVD group. Rates of preventive practices were lowest in the subgroup of PVD patients without a history of coronary or cerebrovascular disease. CONCLUSIONS: Preventive therapies are under utilized in patients with PVD. Effective strategies need to be developed to encourage the use of these adjunctive therapies in the long-term management of vascular patients.

Deep circumflex iliac artery as a cause of type II endoleak.

PURPOSE: To report a collateral pathway involving the deep circumflex iliac artery causing a type II endoleak following endoluminal exclusion of an abdominal aortic aneurysm (AAA). CASE REPORT: A 75-year-old man was investigated for a persistent type II endoleak 2 years after endovascular AAA repair with a Zenith Trifab stent-graft. Angiography revealed contrast in the sac from a lumbar artery fed via a collateral of the deep circumflex iliac artery. The lumbar artery was embolized with coils, but an endoleak persisted and is being followed. CONCLUSIONS: This collateral pathway is easily missed during angiography for endoleaks and should be considered where an endoleak is suspected but cannot be found.

Spontaneous common iliac artery dissection after exercise.

PURPOSE: To review the clinical features and management of spontaneous iliac dissections. CASE REPORT: A healthy 60-year-old competitive cyclist presented with acute onset of short-distance claudication following vigorous exercise. Angiography showed a dissection flap extending from the right common iliac artery to the external iliac artery. An uncovered stent was placed across the proximal entry site but did not obliterate the false lumen; open surgical intervention was required. CONCLUSIONS: Spontaneous dissection of the iliac artery is a rare but important condition to suspect in high performance athletes complaining of leg pain following exercise.