A novel hybrid 3D endoscope zooming and repositioning system: Design and feasibility study.

BACKGROUND: Manipulation of the endoscope during minimally invasive surgery is a major source of inconvenience and discomfort. This report elucidates the architecture of a novel one-hand controlled endoscope positioning device and presents a practicability evaluation. METHODS AND MATERIALS: Setup time and total surgery time, number and duration of the manipulations, side effects of three-dimensional (3D) imaging, and ergonomic complaints were assessed by three surgeons during cadaveric and in vivo porcine trials. RESULTS: Setup was accomplished in an average (SD) of 230 (120) seconds. The manipulation time was 3.87 (1.77) seconds for angular movements and 0.83 (0.24) seconds for zooming, with an average (SD) of 30.5 (16.3) manipulations per procedure. No side effects of 3D imaging or ergonomic complaints were reported. CONCLUSIONS: The integration of an active zoom into a passive endoscope holder delivers a convenient synergy between a human and a machine-controlled holding device. It is shown to be safe, simple, and intuitive to use and allows unrestrained autonomic control of the endoscope by the surgeon.

A novel design for steerable instruments based on laser-cut nitinol.

OBJECTIVE: Omnidirectional articulated instruments enhance dexterity. In neurosurgery, for example, the simultaneous use of 2 instruments through the same endoscopic shaft remains a difficult feat. It is, however, very challenging to manufacture steerable instruments of the requisite small diameter. We present a new technique to produce such instruments by means of laser cutting. Only 3 coaxial tubes are used. The middle tube has a cutting pattern that allows the steering forces to be transmitted from the proximal to the distal end. In this way the steering part is concealed in the wall of the tube. Large diameter articulated instruments such as for laparoscopy might benefit from the excellent tip stability provided by the same economical technology. METHOD: Coaxial nitinol tubes are laser-cut with a Rofin Stent Cutter in a specific pattern. The 3 tubes are assembled by sliding them over one another, forming a single composite tube. In a surgical simulator, the neurosurgical microinstruments and laparoscopic needle drivers were evaluated on surgical convenience. RESULTS: Simultaneous use of 2 neurosurgical instruments (1.5 mm diameter) through the same endoscopic shaft proved to be very intuitive. The tip of the steerable laparoscopic instruments (10 mm diameter) could resist a lateral force of more than 20 N. The angle of motion for either instrument was at least 70° in any direction. CONCLUSIONS: A new design for steerable endoscopic instruments is presented. It allows the construction in a range from microinstruments to 10-mm laparoscopic devices with excellent tip stability.

In situ bipolar electroporation for localized cell loading with reporter dyes and investigating gap junctional coupling.

Electroporation is generally used to transfect cells in suspension, but the technique can also be applied to load a defined zone of adherent cells with substances that normally do not permeate the plasma membrane. In this case a pulsed high-frequency oscillating electric field is applied over a small two-wire electrode positioned close to the cells. We compared unipolar with bipolar electroporation pulse protocols and found that the latter were ideally suited to efficiently load a narrow longitudinal strip of cells in monolayer cultures. We further explored this property to determine whether electroporation loading was useful to investigate the extent of dye spread between cells coupled by gap junctions, using wild-type and stably transfected C6 glioma cells expressing connexin 32 or 43. Our investigations show that the spatial spread of electroporation-loaded 6-carboxyfluorescein, as quantified by the standard deviation of Gaussian dye spread or the spatial constant of exponential dye spread, was a reliable approach to investigate the degree of cell-cell coupling. The spread of reporter dye between coupled cells was significantly larger with electroporation loading than with scrape loading, a widely used method for dye-coupling studies. We conclude that electroporation loading and dye transfer is a robust technique to investigate gap-junctional coupling that combines minimal cell damage with accurate probing of the degree of cell-cell communication.

High frequency deep brain stimulation in the hippocampus modifies seizure characteristics in kindled rats.

PURPOSE: This experimental animal study evaluates the effect of high frequency deep brain stimulation (HFS DBS) on seizures in the Alternate Day Rapid Kindling model for temporal lobe epilepsy (TLE). The target for HFS is the hippocampus, as this structure is often presumed to be the seizure focus in human TLE. METHODS: Rats (n = 12) were fully kindled in the hippocampus according to the Alternate Day Rapid Kindling protocol. Characteristics of the evoked afterdischarges (AD) were determined in the baseline period using AD threshold, AD latency, and AD duration as parameters. Rats were divided into a treated group (n = 7) that received 130 Hz HFS for 1 week, and a control group (n = 5) that did not receive HFS. Rats were retested in the following week. After 1 additional week of rest, the HFS group was continuously stimulated again for 1 week, during which AD evoked by kindling stimuli were characterized again. RESULTS: HFS had a direct effect on evoked AD: during HFS, it increased AD threshold to 203 +/- 13% of controls (p < 0.01) and increased AD latency to 191 +/- 19% (p < 0.05). It decreased AD duration to 71 +/- 9% (p < 0.05) of controls. The effect outlasted the HFS stimulation as in the week following HFS similar differences, but smaller in size, could still be established. CONCLUSION: Continuous HFS (130 Hz) in the hippocampus of epileptic rats modulates the characteristics of evoked AD in a way that reflects a reduction in excitability of the target region.

Technical note: the design of a stereotactic frame for direct MRI-anatomical correlation of the brachial plexus.

The purpose of this study was to identify optimal magnetic resonance imaging (MRI) conditions to visualize discrete alterations of brachial plexus components, as part of a biomechanical study of minor nerve compression syndromes. A method was developed allowing direct comparison between the MRI image and the subsequently obtained matching anatomic section of the same specimen. We designed a stereotactic frame to obtain the precise orientation of the MRI plane with reference to the specimen and adapted a vertical band saw for multiplanar sectioning of cadaveric specimens. Two cadaveric upper quadrants were examined by MRI (TR 450 ms, TE 13 ms, pixel matrix 512 x 512 and FOV 23-26 cm) and anatomical slices were produced. One specimen was sectioned axially, while the second specimen was sectioned in an oblique plane corresponding to the natural longitudinal axis of the upper part of the brachial plexus. MR images and the corresponding slices exhibited a strong correlation. This correlation was checked by using vitamin A pearls as landmarks. MR images revealed more detail after the correlating anatomical slices were analyzed. The present study shows that the method is suited for direct MRI-anatomic comparison of the brachial plexus and is also proposed for application to other topographical regions.

Method to measure force required to remove Pediculus humanus capitis (Phthiraptera: Pediculidae) eggs from human hair.

Head lice are very common and mainly affect children between 3 and 12 yr old. Little is known about the way nits, the eggs of the head louse, are attached to the hair. In this report, an objective measurement procedure for the ease with which nits can be removed is presented. The first peak force, associated with the start of nit movement, and the average and maximal force during the sliding of the nit were measured. The three force variables correlated with the length of the cylinder by which the nit was attached to the hair. A negative correlation was found between the maximum force exerted and the distance of the nit from the scalp. The method described in this report can be used to determine the in vitro efficacy of various products to remove nits.

Electroporation loading and photoactivation of caged InsP3: tools to investigate the relation between cellular ATP release in response to intracellular InsP3 elevation.

Photolytic liberation of InsP(3) in single cells triggers cell-to-cell propagating calcium changes that are communicated by a gap junctional and a paracrine purinergic pathway involving InsP(3)-triggered ATP release. We investigated the relation between the InsP(3) stimulus and the resulting ATP release in ECV304 cells using UV photolysis of caged compounds and bioluminescent ATP measurements. Careful consideration of all steps, starting from caged InsP(3) loading into the cells by electroporation, up to photoliberation upon UV exposure, allowed to derive a dose-response relation that revealed a first part with a flattening ATP release response in the below 10microM InsP(3) concentration range and a second phase of steeply increasing ATP release in response to above 10microM InsP(3) stimulation. ATP release triggered by below 10microM InsP(3) concentrations attained a level in the order of 30% above baseline ATP release, while the steeply increasing response to high InsP(3) concentrations attained values in the order of 150% above baseline. Our data indicate the involvement of low affinity InsP(3) receptor sites in the pathway leading to triggered ATP release, with activation of these receptors causing the release of 1-2% of the total cellular ATP pool.