Src family kinases are required for limb trajectory selection by spinal motor axons

Signal relay by guidance receptors at the axonal growth cone is a process essential for the assembly of a functional nervous system. We investigated the in vivo function of Src family kinases (SFKs) as growth cone guidance signaling intermediates in the context of spinal lateral motor column (LMC) motor axon projection toward the ventral or dorsal limb mesenchyme. Using in situ mRNA detection we determined that Src and Fyn are expressed in LMC motor neurons of chick and mouse embryos at the time of limb trajectory selection. Inhibition of SFK activity by C-terminal Src kinase (Csk) overexpression in chickLMCaxons using in ovo electroporation resulted inLMC axons selecting the inappropriate dorsoventral trajectory within the limb mesenchyme, with medial LMC axon projecting into the dorsal and ventral limb nerve with apparently random incidence. We also detected LMC axon trajectory choice errors in Src mutant mice demonstrating a nonredundant role for Src in motor axon guidance in agreement with gain and loss of Src function in chickLMCneurons which led to the redirection ofLMCaxons. Finally, Csk-mediated SFK inhibition attenuated the retargeting ofLMCaxons caused by EphA or EphB over-expression, implying the participation of SFKs in Eph-mediated LMC motor axon guidance. In summary, our findings demonstrate that SFKs are essential for motor axon guidance and suggest that they play an important role in relaying ephrin:Eph signals that mediate the selection of motor axon trajectory in the limb.This work was supported by a grant from the Canadian Institutes of Health Research (Institute of Genetics and Institute of Neurosciences, Mental Health, and Addiction) to A.K. (MOP-77556 and IG-74068)

Foxp1 and lhx1 coordinate motor neuron migration with axon trajectory choice by gating Reelin signalling.

Topographic neuronal maps arise as a consequence of axon trajectory choice correlated with the localisation of neuronal soma, but the identity of the pathways coordinating these processes is unknown. We addressed this question in the context of the myotopic map formed by limb muscles innervated by spinal lateral motor column (LMC) motor axons where the Eph receptor signals specifying growth cone trajectory are restricted by Foxp1 and Lhx1 transcription factors. We show that the localisation of LMC neuron cell bodies can be dissociated from axon trajectory choice by either the loss or gain of function of the Reelin signalling pathway. The response of LMC motor neurons to Reelin is gated by Foxp1- and Lhx1-mediated regulation of expression of the critical Reelin signalling intermediate Dab1. Together, these observations point to identical transcription factors that control motor axon guidance and soma migration and reveal the molecular hierarchy of myotopic organisation

The incidence of symptomatic venous thromboembolism following hip fractures with or without surgery in Taiwan

AbstractBackgroundInformation on the incidence of venous thromboembolism (VTE) following hip fractures in Asia is rare. This study will investigate the epidemiology of symptomatic VTE in Taiwanese patients experiencing hip fractures.Methods and resultsWe used Taiwan's National Health Insurance Research Database to retrospectively identify patients (≧45years) who experienced hip fractures from 1998 to 2007 and were followed up for 3months after the discharge. Logistic regression analysis determined the independent risk factors of symptomatic VTE after the fractures. We identified 134,034 patients (mean age: 76.2±9.7years; female: 57.8%) who experienced hip fractures, 83.2% of whom underwent hip surgery. The overall pharmacological thromboprophylaxis rate was 2.7%. The mean length of stay was 11.3±7.9days. The 3-month cumulative incidence of symptomatic VTE was 77 events per 10,000 persons. Multivariate analysis showed that previous DVT, previous PE, varicose veins, cancer, heart failure, renal insufficiency, and older age were independent risk factors of developing VTE.ConclusionsThe incidence of symptomatic VTE after hip fractures is low in Taiwan. Patients rarely received pharmacological thromboprophylaxis following hip fractures. Universal thromboprophylaxis for patients experiencing hip fractures was not necessary in Taiwan, but it should be considered in high-risk populations

EIT of the Human Body with Optimal Current Patterns and Skin-Electrode Impedance Compensation

Following the lead of the EIT research group at Rensselaer Polytechnic Institute, we have designed and implemented a system comprising 32 independent current sources, in which it is possible to apply current patterns optimizing distinguishability. One potential technical problem is that we are measuring voltages on current-carrying electrodes, giving some sensitivity to time varying skinelectrode impedances. We demonstrate here an algorithm to estimate simultaneously changes in the medium and timevarying skin-electrode impedances

A High Precision Parallel Current Drive Experimental EIT System

Our parallel current drive EIT architecture can simultaneously drive 32 independent high impedance current sources and measure 32 independent precision voltage channels. Coherent modulation and demodulation is digitally implemented using field programmable gate arrays. High accuracy and precision is achieved using custom analog circuits containing modified Howland current sources coupled to negative impedance converters

Multi-channel EIT for layer-based hydration monitoring

Accurate monitoring of hydration level in patients remains a major challenge for hemodialysis therapy. Using a prototype EIT system with simultaneous multi-channel current excitation, we demonstrated the capability to detect a difference of 35ml daily fluid change in human subjects who wear compression sock only on one leg. The prototype system has the potential to be used in clinical settings with hydration monitoring needs

The mPEG-PCL Copolymer for Selective Fermentation of Staphylococcus lugdunensis Against Candida parapsilosis in the Human Microbiome.

Many human skin diseases, such as seborrheic dermatitis, potentially occur due to the over-growth of fungi. It remains a challenge to develop fungicides with a lower risk of generating resistant fungi and non-specifically killing commensal microbes. Our probiotic approaches using a selective fermentation initiator of skin commensal bacteria, fermentation metabolites or their derivatives provide novel therapeutics to rein in the over-growth of fungi. Staphylococcus lugdunensis (S. lugdunensis) bacteria and Candida parapsilosis (C. parapsilosis) fungi coexist in the scalp microbiome. S. lugdunensis interfered with the growth of C. parapsilosis via fermentation. A methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) (mPEG-PCL) copolymer functioned as a selective fermentation initiator of S. lugdunensis, selectively triggering the S. lugdunensis fermentation to produce acetic and isovaleric acids. The acetic acid and its pro-drug diethyleneglycol diacetate (Ac-DEG-Ac) effectively suppressed the growth of C. parapsilosis in vitro and impeded the fungal expansion in the human dandruff. We demonstrate for the first time that S. lugdunensis is a skin probiotic bacterium that can exploit mPEG-PCL to yield fungicidal short-chain fatty acids (SCFAs). The concept of bacterial fermentation as a part of skin immunity to re-balance the dysbiotic microbiome warrants a novel avenue for studying the probiotic function of the skin microbiome in promoting health

Myocardium-derived conditioned medium improves left ventricular function in rodent acute myocardial infarction

<p>Abstract</p> <p>Background</p> <p>We investigated whether myocardium-derived conditioned medium (MDCM) is effective in preserving left ventricular (LV) function in a rat acute myocardial infarction (AMI) model.</p> <p>Methods</p> <p>Adult male Sprague-Dawley (SD) rats (n = 36) randomized to receive either left coronary artery ligation (AMI induction) or thoracotomy only (sham procedure) were grouped as follows (n = 6 per group): Group I, II, and III were sham-controls treated by fresh medium, normal rat MDCM, and infarct-related MDCM, respectively. Group IV, V, and VI were AMI rats treated by fresh medium, normal MDCM, and infarct-related MDCM, respectively. Either 75 μL MDCM or fresh medium was administered into infarct myocardium, followed by intravenous injection (3 mL) at postoperative 1, 12, and 24 h.</p> <p>Results</p> <p>In vitro studies showed higher phosphorylated MMP-2 and MMP-9, but lower α-smooth muscle actin and collagen expressions in neonatal cardiac fibroblasts treated with MDCM compared with those in the cardiac fibroblasts treated with fresh medium (all p < 0.05). Sirius-red staining showed larger collagen deposition area in LV myocardium in Group IV than in other groups (all p < 0.05). Stromal cell-derived factor-1α and CXCR4 protein expressions were higher in Group VI than in other groups (all p < 0.05). The number of von Willebrand factor- and BrdU-positive cells and small vessels in LV myocardium as well as 90-day LV ejection fraction were higher, whereas oxidative stress was lower in Group VI than in Group IV and Group V (all p < 0.05).</p> <p>Conclusion</p> <p>MDCM therapy reduced cardiac fibrosis and oxidative stress, enhanced angiogenesis, and preserved 90-day LV function in a rat AMI model.</p

Early combined treatment with sildenafil and adipose-derived mesenchymal stem cells preserves heart function in rat dilated cardiomyopathy

<p>Abstract</p> <p>Background</p> <p>We investigated whether early combined autologous adipose-derived mesenchymal stem cell (ADMSC) and sildenafil therapy offers an additive benefit in preserving heart function in rat dilated cardiomyopathy (DCM).</p> <p>Methods</p> <p>Adult Lewis rats (n = 8 per group) were divided into group 1 (normal control), group 2 (saline-treated DCM rats), group 3 [2.0 × 10⁶ADMSC implanted into left ventricular (LV) myocardium of DCM rats], group 4 (DCM rats with sildenafil 30 mg/kg/day, orally), and group 5 (DCM rats with combined ADMSC-sildenafil). Treatment was started 1 week after DCM induction and the rats were sacrificed on day 90.</p> <p>Results</p> <p>The results showed that mitochondrial protein expressions of connexin43 and cytochrome-C were lowest in group 2, and lower in groups 3 and 4 than in group 5 (p < 0.002). Conversely, oxidative index was highest in group 2, and also higher in groups 3 and 4 than in group 5 (p < 0.0003). The mRNA expressions of interleukin (IL)-10, Gro/IL-8, endothelial nitric oxide synthase, and Bcl-2 were lowest in group 2, and lower in groups 3 and 4 compared with group 5 (p < 0.0001). The mRNA expressions of matrix metalloproteinase-9, Bax, caspase 3, and stromal-cell derived factor-1α were highest in group 2, and higher in groups 3 and 4 than in group 5 (p < 0.0004). Apoptosis and fibrosis in LV myocardium were most prominent in group 2 and higher in groups 3 and 4 than in group 5, whereas angiogenesis and LV ejection fraction were lowest in group 2 and lower in groups 3 and 4 than in group 5 (p < 0.003).</p> <p>Conclusion</p> <p>Early combined ADMSC/sildenafil is superior to either treatment alone in preserving LV function.</p