Aging effects on electrical and hemodynamic responses in the sensorimotor network during unilateral proximal upper limb functional tasks.

Healthy aging leads to poorer performance in upper limb (UL) daily living movements. Understanding the neural correlates linked with UL functional movements may help to better understand how healthy aging affects motor control. Two non-invasive neuroimaging methods allow for monitoring the movement-related brain activity: functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG), respectively based on the hemodynamic response and electrical activity of brain regions. Coupled, they provide a better spatiotemporal mapping. The aim of this study was to evaluate the effect of healthy aging on the bilateral sensorimotor (SM1) activation patterns of functional proximal UL movements. Twenty-one young and 21 old healthy participants realized two unilateral proximal UL movements during: i) a paced reaching target task and ii) a circular steering task to capture the speed-accuracy trade-off. Combined fNIRS-EEG system was synchronised with movement capture system to record SM1 activation while moving. The circular steering task performance was significantly lower for the older group. The rate of increase in hemodynamic response was longer in the older group with no difference on the amplitude of fNIRS signal for the two tasks. The EEG results showed aging related reduction of the alpha-beta rhythms synchronisation but no desynchronisation modification. In conclusion, this study uncovers the age-related changes in brain electrical and hemodynamic response patterns in the bilateral sensorimotor network during two functional proximal UL movements using two complementary neuroimaging methods. This opens up the possibility to utilise combined fNIRS-EEG for monitoring the movement-related neuroplasticity in clinical practice.

Testicular prostheses in children: Is earlier better?

INTRODUCTION: The absence of a testis occurs for various reasons in children, but testicular prosthesis implantation in children is uncommon. The optimal time for prosthesis placement is still unclear, and its complication rate has been poorly studied in children. OBJECTIVE: The aim of this study was to determine the risk factors of complications in cases of testicular prosthesis implantation in children. STUDY DESIGN: A monocentric, retrospective review was performed of children implanted with a testicular prosthesis between 2008 and 2014. All implantations were performed through an inguinal incision with a standardized procedure. Children were divided into two groups depending on the interval after orchiectomy: (A) early implantation (delay between surgeries <1 year); and (B) delayed surgeries (delay ≥1 year). Statistical analysis was performed with Student and Fisher tests. RESULTS: Twenty-six patients (A, 15; B, 11) had a total of 38 testicular prostheses placements. Mean follow-up was 36.2 months. First surgery was performed at the mean age of 11.8 years (range 0-17.9) (A, 14.1; B, 8.1; P = 0.01) and testicular prosthesis implantation at the mean age of 14.7 years (range 9-18) (A, 14.3; B, 14.6) with a mean delay of 36.1 months (A, 1.3; B, 80.3). Indications were mainly spermatic cord torsion (27%), bilateral anorchia (27%), and testicular atrophy after cryptorchidism surgery (19.2%). Complications (10.5%) included two cases of extrusion, one infection and one migration. Patient 1 had a history of acute lymphoblastic leukemia with testicle relapse 2 years after induction therapy. High-dose chemotherapy, total body irradiation and bilateral orchiectomies were performed, and bilateral prostheses were implanted 12 years after the end of chemotherapy. Complications happened 85 days after surgery. Patient 2 was followed-up for a proximal hypospadias. The tunica vaginalis flap, which was used during a redo urethroplasty, lead to testicular atrophy. Thirteen years after the last penile surgery, a testicular prosthesis was placed through an inguinal incision, and extrusion occurred 203 days after surgery. Bacterial cultures of the prostheses were sterile and histological review showed no sign of granuloma or graft rejection. The complication rate was significantly higher if the delay between the two surgeries exceeded 1 year (P = 0.01). Indications of orchiectomy, prior scrotal incision, and prosthesis size were not risk factors. CONCLUSIONS: Testicular prosthesis implantation was relatively safe in a pediatric cohort. The complication rate was significantly higher if the delay between the orchiectomy and the prosthetic placement exceeded 1 year. These results suggest that reducing the delay between orchiectomy and prosthesis implantation may lead to fewer complications.

Safety and efficacy of one-stage total laparoscopic treatment of common bile duct stones in children.

BACKGROUND: The purpose of this study is to confirm the effectiveness of total laparoscopic treatment of common bile duct (CBD) stones in children. METHODS: All children who were treated in our department for cholelithiasis were reviewed from 1996 to 2013. Data collection focused on children with CBD stones, including age, sex, symptoms at diagnosis, hepatic and pancreatic blood tests results, US scan results, etiology, detailed surgical technique, operative time, length of hospital stay, complications, and stone-free status or not, at last follow-up. RESULTS: 551 children were treated for cholelithiasis and had undergone laparoscopic cholecystectomy. Among those, 36 children (6.5%) presented with CBD stones with a mean age at symptom onset of 10.4 years (min-max: 4 months-18 years). A majority of the patients presented with hemolytic disease (61%). In 55% of the cases, cholangiography alone or simple serum saline flush of the biliary tree was sufficient to obtain a stone-free CBD. Additional maneuvers with Dormia basket or Fogarty catheter led to 72% of success rate. In 9 cases (25%) of failure of the procedure, 6 patients underwent endoscopic retrograde cholangiopancreatography (ERCP) with endoscopic sphincterotomy (ES), 1 patient was re-operated at day1 for hemorrhage, and 2 patients were followed by US scan with spontaneous evacuation of CBD stones. Mean follow-up was of 2 years (min-max: 1 month-5 years). All patients were stone free at last clinical and radiological evaluation. CONCLUSION: A one-stage total laparoscopic treatment of common bile duct stones in children is a safe, feasible, reproducible, and efficient procedure in 72% of the cases. This rate could be upgraded by a combination of laparoscopic and endoscopic technique during the same anesthesia and preserving Oddi sphincter function. These minimal invasive techniques still need to be developed in children.

Pancreatic resections for solid or cystic pancreatic masses in children.

OBJECTIVES: The aim of the study was to assess the diagnosis and management of solid pancreatic neoplasm in children and the type of surgical treatment, focusing on short- and long-term outcomes. METHODS: We retrospectively reviewed the charts of all children who had undergone pancreatic resection for suspicion of pancreatic tumor in Kremlin Bicêtre Hospital, Paris, between 1986 and 2008. We studied the symptoms at diagnosis, the type of surgery, and the short- and long-term morbidity and mortality. RESULTS: Of 18 patients identified, there were 7 pseudopapillary tumors, 3 neuroblastomas, 2 rhabdomyosarcomas, 1 acinar cell carcinoma, 1 endocrine cell carcinoma, 1 renal angiomyolipoma, and 3 pancreatic cysts. Symptoms at diagnosis were abdominal trauma, abdominal mass, and jaundice. Operative procedures were duodenopancreatectomy (11), mid-pancreatic resections (2), splenopancreatectomy (2), distal pancreatectomy (1), and tumorectomy (2). There were no deaths related to surgery. The postoperative morbidity rate was 45%, including 2 cases of fistula (11%) occurring after a mid-pancreatic resection and a pancreaticoduodenectomy. The median follow-up was 4.2 years (range 2-11). There was no diabetes mellitus, but there was 1 case of fat diet intolerance requiring pancreatic enzyme substitution. All of the children had a growth curve within normal limits. CONCLUSIONS: In this experience, pancreatic resections have proven to be a safe and efficient procedure, with low long-term morbidity, for the treatment of tumoral and selected nontumoral pancreatic masses.

Cable properties of dendrites in hippocampal neurons of the rat mapped by a voltage-sensitive dye.

Dendrites of pyramidal neurons from embryonic rat hippocampus are investigated in culture using a voltage-sensitive fluorescent dye. The electrical response to somatic stimulation is observed as a time-resolved map with a resolution of 0.9 microm at a time constant of 0.4 ms without signal averaging. The data are interpreted in terms of a tapering cable with Hodgkin-Huxley parametrization. The spread of short hyperpolarizing transients is damped by capacitive shunting. The invasion of an action potential is boosted by voltage-gated conductances of a low density. No irregularity is observed at a bifurcation. The passive cable parameters of internal resistance and membrane resistance at resting voltage are Ri = 300 omega cm and Rm = 40 (k)omega cm2 respectively, at a maximum sodium conductance of approximately 4.4 mS/cm2. The electrotonic length constant and the dynamic length constant at 1 kHz are 580 and 90 microm respectively. These results are compatible with electrophysiological data of dendrites in slices of adult hippocampus and with optical data of narrow processes of leech neurons in culture. The functional implications of boosting an action potential by voltage-gated channels of low density are considered.

Cable properties of a straight neurite of a leech neuron probed by a voltage-sensitive dye.

We measured a time-resolved map of electrical activity in a thin straight neurite (1.5 microns thick, 500 microns long) at a resolution of 8 microns and 0.4 ms. The neurite was obtained by guided outgrowth of an identified neuron of the leech on lanes of extracellular matrix protein. The electrical signals were detected by a fluorescent voltage-sensitive dye. We observed the voltage that was caused by an action potential elicited at the soma and by a Gaussian hyperpolarization induced at the soma, respectively. We compared the data with numerical solutions of the cable equation using the Hodgkin-Huxley parametrization. We could attribute the experimental results of depolarization and of hyperpolarization to the propagation of an action potential along an "active" cable and to the spread along a "passive" cable, respectively, if we assigned rather high specific resistances to the cytoplasm (RI = 250 omega.cm) and to the membrane (RM = 22 k omega.cm2). This assignment explained the slow velocity of 150 microns/ms of a pulse by active propagation and the limited range of 200 microns of a pulse by passive spread.

Voltage-sensitive fluorescence of amphiphilic hemicyanine dyes in neuron membrane.

Fluorescent amphiphilic hemicyanine dyes were adsorbed to the plasma membrane of isolated Retzius neurons of the leech. Voltage steps were applied to the neuron by the patch-clamp technique in whole-cell configuration. The change of fluorescence was observed as induced by the voltage jump. The relative changes of the excitation spectrum and of the emission spectrum of fluorescence were recorded. The complete set of spectral data for each dye was fitted by five parameters: shifts of the emission and the excitation spectrum, a change of fluorescence quantum yield and changes of the widths of the excitation and of the emission spectrum. The only common feature for all dyes was a blue-shift of the excitation spectrum and a drop of the yield when the neuron was stained from the outside and a positive voltage was applied to the inside. With respect to the shift of the emission spectrum and the changes of width qualitatively different results were obtained for different dyes. It is not attempted to assign a physical mechanism--probably a superposition of several mechanisms--of voltage-sensitivity.