One-to-one neuron–electrode interfacing

The question of neuronal network development and organization is a principle one, which is closely related to aspects of neuronal and network form-function interactions. In-vitro two-dimensional neuronal cultures have proved to be an attractive and successful model for the study of these questions. Research is constraint however by the search for techniques aimed at culturing stable networks, whose electrical activity can be reliably and consistently monitored. A simple approach to form small interconnected neuronal circuits while achieving one-to-one neuron–electrode interfacing is presented. Locust neurons were cultured on a novel bio-chip consisting of carbon-nanotube multi-electrode-arrays. The cells self-organized to position themselves in close proximity to the bio-chip electrodes. The organization of the cells on the electrodes was analyzed using time lapse microscopy, fluorescence imaging and scanning electron microscopy. Electrical recordings from well identified cells is presented and discussed. The unique properties of the bio-chip and the specific neuron–nanotube interactions, together with the use of relatively large insect ganglion cells, allowed long-term stabilization (as long as 10 days) of predefined neural network topology as well as high fidelity electrical recording of individual neuron firing. This novel preparation opens ample opportunity for future investigation into key neurobiological questions and principles.     

Local changes in the redox potential in the rabbit cerebral cortex accompanying the acquisition of a conditioned defensive reflex

The oxidative-reductive (redox) potential (E) of brain tissue depends on the ratio of the speeds of processes occurring in the glycolysis (the evolutionarily ancient energy compartment operating without oxygen) and oxidative metabolism (evolutionarily younger and energetically more efficient) compartments. E in the cortex was recorded using implanted platinum electrodes. A conditioned defensive reflex (CDR) was developed by combination of a light and electrocutaneous stimulation (ECS) of the ear. The results showed that after a series of combinations of the light and the ECS, the light started to elicit a change in E. By 200 combinations, the brain developed both increases and decreases in E during combinations. As the number of combinations increased, increases in E were gradually replaced by decreases. We believe that this dynamic of the balance of the major sources of brain energy supply suggests that formation of the CDR may involve a significant role for subcellular structures receiving energy from oxidative metabolism formed at the relatively young evolutionary level, while the major source of energy for brain function during performance of the acquired CDR is the older evolutionary compartment — glycolysis. __________ Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 92, No. 3, pp. 273–283, March, 2006.     

Model-based ankle joint angle tracing by cuff electrode recordings of peroneal and tibial nerves

The main goal of the present study was to estimate the ankle joint angle from the peroneal and tibial electroneurography (ENG) recordings. Two single-channel cuff electrodes for recording ENG were placed on the proximal part of rabbit peroneal and tibial nerves respectively and static positioning and ramp-and-hold stretches were performed to characterize the static and dynamic ENG responses. An ENG model, consisting of static and dynamic parts, was constructed to relate ENG to ankle angle trajectory and an inverse ENG model was derived to predict ankle angle. The results showed that the new model could accurately estimate large-range ankle angles during and after ramp-and-hold movements. Our study provides a basis for implementing joint angle tracing without using artificial angle sensors.     

A Fractally Coated, 1.3 mm2 High Impedance Pacing Electrode

Minimizing the geometric surface area of pacing electrodes increases impedance and reduces the current drain during stimulation, provided that voltage (pulse-width) thresholds remain unchanged. This may be feasible by coating the electrode surface to increase the capacity of the electrode tissue interface and to diminish polarization. Ten unipolar, tined leads with a surface area of 1.3 mm² and a “fractal” coating of Iridium (Biotronik SD-V137) were implanted in the ventricle, and electrogram amplitude (unfiltered), slew-rate, pacing threshold (0.5 ms), and impedance (2.5 V; 0.5 ms) were measured by the 5311 PSA (Medtronic). On days 0, 2, 5, 10, 28, 90, 180, 360 postimplant, sensing threshold (up to 7.0 mV, measuring range 1–14 mV on day 360 only) and the strength duration curve (0.5–4.0 V; 0.03–1.5 ms; steps: 0.5 V; 0.01 ms, respectively) were determined, the minimum charge delivered per pulse (charge threshold), and the impedance were taken from pacemaker telemetry (Intermedics 294–03). Data were compared with those of an earlier series of 20 unipolar, tined TIR-leads (Biotronik) with a surface area of 10 mm² and a “fractal” coating of titanium nitride. With the model SD-V137 versus TIR, intraoperative electrogram amplitudes were 15.1 ± 6.1 versus 14.4 ± 3.9 mV(NS), slew rates 3.45 ± 1.57 versus 1.94 ± 1.06 V/s (P < 0. 05), pacing thresholds 0.16 ± 0.05 versus 0.52 ± 0.15 V (P < 0.01) and impedance measurements 1,136 ±175 versus 441 ± 73 Ω (P < 0.0001), respectively. During follow-up, sensing thresholds were the same with both leads. Differences in pulse width thresholds lost its significance on day 28 but resumed on day 360 (SD-V137: 0.08 ± 0.04 ms; TIR: 0.16 ± 0.06 ms at 2.5 V; P < 0.01). With an electrode surface of 1.3 mm², charge per pulse and impedance consistently differed from control, beingO.15 ± 0.15 versus 0. 66 ± 0. 20 μC (P < 0.001) and 1,344 ± 376 versus 538 ± 79 Ω, respectively, one year after implantation (P < 0.0001). In summary, “fractally” coated small surface electrodes do not compromise sensing; by more than doubling impedance against controls they offer pacing thresholds (mainly in terms of charge) that are significantly lower than with the reference electrode.     

脑瘫痉挛解除后足畸形的变化

痉挛型脑瘫58例行L_2—S_1节段的选择性脊神经后根切断术,术后患者的下肢痉挛均巳解除.通过术前术后足畸形的对比,发现SPR术能使多数痉挛所致足畸形在术后得以完全矫正,并减轻痉挛与软组织挛缩同时存在的足畸形的严重程度,预防软组织挛缩,避免足畸形加重,而对跟骨畸形影响较小.本组病例中扁平外翻足畸形多见,在治疗中是一个值得重视的问题.     

Preliminary Studies on a New Steroid Eluting Epicardial Electrode

Acute and chronic canine atrial and ventricular thresholds and sensing were compared for a steroid eluting epicardial plaque electrode, a similar steroid free plaque electrode and two standard leads. The steroid eluting electrode had low, stable thresbolds in atrium and ventricle compared to the steroid free plaque and standard leads. This new electrode also provided improved atrial sensing. Thus, the concept of a steroid eluting epicardial electrode shows promise for further evaluation.     

Optimal Multifield Functional Electrical Stimulation Parameters for the “Turn on the Light” Task and Related Upper Limb Kinematics Repeatability in Poststroke Subjects

ObjectiveTo characterize the optimal functional electrical stimulation (FES) parameters that assist the turn on the light task (TOTL) on poststroke participants and to analyze the related upper limb (UL) kinematics repeatability.DesignCross-sectional study.SettingHuman movement research center.ParticipantsPoststroke individuals (N=11) with history of a single unilateral stroke that resulted in a motor control dysfunction of the contralesional UL.InterventionsFES based on surface multifield technology applied to the contralesional wrist and finger extensors during the TOTL.Main Outcome MeasuresFES outcome metrics (virtual electrodes, stimulation duration, intensity) and kinematic metrics (end-point kinematics [absolute and relative duration, mean and peak velocities, relative instant of peak velocity, index of curvature, number of movement units] and joint kinematics [shoulder, elbow, wrist end position and range of movement]). Outcome measures were assessed 2 times with a 72-hour maximum time interval.ConclusionIt was possible to establish reliable FES parameters that assisted the TOTL on poststroke participants. These stimulation parameters led to high to very high repeatability in terms of UL kinematics for most of the cases.     

The effect of ipratropium bromide on intraocular pressure in patients with chronic obstructive pulmonary disease: an open-label study

Background: After smoking cessation, bronchodilation with anticholinergics and beta₂-agonists is the keystone of pharmacologic therapy for symptomatic chronic obstructive pulmonary disease (COPD). For patients who fail to get relief from a drug delivered via a metered-dose inhaler (MDI) plus spacer, or for acute exacerbations in patients who are unable to use an MDI, a nebulized solution (NS) usually is preferred. Although ipratropium bromide (IB) has a low incidence of adverse events, anticholinergic drugs are known to produce side effects such as urinary retention, constipation, drying of secretions, and precipitation of glaucoma.Objective: In this open-label study, we aimed to assess the acute effects of IB on intraocular pressure (IOP) and tolerability of administration of IB by MDI and NS in patients with COPD and baseline values of IOP that were within normal limits.Methods: Eligible patients were aged >40 years and had a cigarette smoking history of >20 pack-years (ie, packs/d × years of smoking), a clinical history of COPD, and a ratio of forced expiratory volume in 1 second to slow vital capacity (FEV₁/VC) <89% predicted value. After baseline pulmonary function testing (PFT), IOP measurements by Goldmann applanation tonometry were performed. PFT measurements were repeated at 15 and 120 minutes after drug inhalation, and IOP measurements were repeated 120 minutes after drug inhalation. Doses were administered on 3 consecutive mornings: placebo on day 1, MDI IB 40 μg on day 2, and NS IB 250 μg on day 3.Results: Measurements are expressed as mean ± SD. Twenty-one stable patients with COPD (all men; mean age, 60.95 ± 7.90 years; mean smoking history, 47.24 ± 17.62 pack-years) were selected from a university hospital outpatient population. On MDI and NS test days (days 2 and 3), respectively, mean baseline FEV₁ measurements were 1.30 ± 0.62 L (42.74% ± 20.11% predicted value) and 1.23 ± 0.58 L (41.16% ± 18.51% predicted value); mean baseline IOPs for the MDI group were 14.24 ± 2.61 mm Hg and 14.00 ± 2.51 mm Hg (right and left eyes, respectively) and for the NS group were 14.57 ± 2.52 mm Hg and 14.00 ± 2.63 mm Hg (right and left eyes, respectively). Although improvements in forced VC, FEV₁, and maximal mid-expiratory flow rate were significant at 15 and 120 minutes for both delivery methods (P < 0.01 for both delivery methods at both times), no significant increase in IOP was found.Conclusion: The single-dose administration of MDI and NS formulations of IB at doses producing bronchodilation had no significant effect on IOP in this study population.     

Insulin receptors and membrane transport in muscle

Summary The AA. report a group ofin vitro experiments relative to the direct inhibition of the insulin effect on the transport of 3-o-methyl glucose and L-proline in rat diaphragm muscle by a reagent specific for tryptophan in a neutral solution, the 2-hydroxy-5-nitrobenzyl bromide. Evidence for the presence of tryptophan at an insulin receptor site in the plasma membrane is given.

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Zusammenfassung Die AA. berichten ueber eine Serie vonin vitro Untersuchungen betr. die direkte Hemmung des Insulineffektes auf den aktiven Transport der 3-o-methyl-Glukose und des l-Prolins beim Rattenzwerchfell mittels eines spezifischen Reagenz' fuer das Tryptophan in neutraler Loesung, des 2-hydroxy-5-nitrobenzil-bromid. Somit ist die Gegenwart von Tryptophan in einem Insulinrezeptor der Plasmamembran bewiesen.

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Resumen Los AA. describen un grupo de experimentosin vitro concernientes a la inhibición directa del efecto de la insulina en el transporte activo de la 3-0-metil glucosa y de la l-prolina en el diafragma de rata por parte de un reactivo específico para el triptófano en solución neutra, el 2-hidroxi-5-nitrobenzil bromuro. De esta manera se comprueba la presencia de triptófano en un receptor insulínico de la membrana plasmática.

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Resume Les AA. rapportent un groupe d'épreuvesin vitro au sujet de l'inhibition directe de l'effet de l'insuline sur le transport actif des 3-o-metil glucose et de la l-proline dans le diaphragme de rat par un réactif spécifique pour le triptophane en solution neutre, le 2-idrossi-5-nitrobenzil bromure. On prouve ainsi la présence de triptophane dans un récepteur insulinique de la membrane plasmatique.

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Riassunto Gli AA. riferiscono un gruppo di esperimentiin vitro riguardanti l'inibizione diretta dell'effetto dell'insulina sul trasporto attivo del 3-o-metil glucosio e della l-prolina nel diaframma di ratto da parte di un reagente specifico per il triptofano in soluzione neutra, il 2-idrossi-5-nitrobenzil bromuro. Viene così provata la presenza di triptofano in un recettore insulinico della membrana plasmatica.

     

Low Direct Cytotoxicity and Cytoprotective Effects of Nitric Oxide Releasing Indomethacin

Nitric oxide (NO) releasing non-steroidal anti-inflammatory drugs (NSAIDs) have shown a marked reduction of gastrointestinal side effects and we here examined the cytotoxicity of NCX 530 (NO-indomethacin). Under conditions where indomethacin clearly induced both necrosis and apoptosis, NCX 530 induced neither. NCX 530 protected cells from celecoxib-induced necrosis and apoptosis. NCX 530 partially suppressed celecoxib-dependent membrane permeabilization and an inhibitor for guanylate cyclase suppressed the cytoprotective effect of NCX 530 against celecoxib. In vivo, NCX 530 alone produced fewer gastric lesions in rats than did indomethacin. A combination of the oral administration of celecoxib together with the intraperitoneal administration of indomethacin, but not of NCX 530, clearly resulted in the production of gastric lesions. The low direct cytotoxicity and the cytoprotective effect of NCX 530 observed in vitro may also act in vivo, thus ensuring that NCX 530 is safe for use on the gastric mucosa.