The Vienna functional electrical stimulation system for restoration of walking functions in spastic paraplegia

An eight-channel stimulation system, currently intended for stimulation of lower extremities, was developed and is introduced. The major development goals were easy handling, modularity to make the system easily adaptable for other functional electrical stimulation (FES) applications, and a wide stimulation parameter range for application-specific parameter optimization. For paraplegic stepping, the system worn by the patient consists of 2 four-channel stimulation modules, a central unit holding the battery and circuitry for power management and communication control, a wireless remote control unit, and a palmtop computer as the main control and input device. A software package for Microsoft Windows supports the design and optimization of stimulation sequences in the rehabilitation center. First tests with patients familiar with FES showed smoother movements during stepping and acceptable good handling. In combination with the PC software, the required stimulation sequences could be created in a very short time.     

Threshold determinations for selective retinal pigment epithelium damage with repetitive pulsed microsecond laser systems in rabbits

BACKGROUND AND OBJECTIVE: In both clinical and animal studies, it has been shown that repetitive short laser pulses can cause selective retinal pigment epithelium damage (RPE) with sparing of photoreceptors. Our purpose was to determine the ophthalmoscopic and angiographic damage thresholds as a function of pulse durations by using different pulsed laser systems to optimize treatment modalities. MATERIALS AND METHODS: Chinchilla-breed rabbits were narcotized and placed in a special holding system. Laser lesions were applied using a commercial laser slit lamp, contact lens, and irradiation with a frequency-doubled Nd:YLF laser (wave-length: 527 nm; repetition rate: 500 Hz; number of pulses: 100; pulse duration: 5 micros, 1.7 micros, 200 ns) and an argon-ion laser (514 nm, 500 Hz, 100 pulses, 5 micros and 200 ms). In all eyes, spots with different energies were placed into the regio macularis with a diameter of 102 microm (tophat profile). After treatment, fundus photography and fluorescein angiography were performed and radiant exposure for ED50 damage determined. Speckle measurements at the fiber tips were performed to determine intensity peaks in the beam profile. RESULTS: Using the Nd:YLF laser system, the ophthalmoscopic ED50 threshold energies were 25.4 microJ (5 micros), 32 microJ (1.7 micros), and 30 microJ (200 ns). The angiographic ED50 thresholds were 13.4 microJ (5 micros), 9.2 microJ (1.7 micros), and 6.7 microJ (200 ns). With the argon laser, the angiographic threshold for 5 micros pulses was 5.5 microJ. The ophthalmoscopic threshold could not be determined because of a lack of power; however, it was > 12 microJ. For 200 ms, the ED50 radiant exposures were 20.4 mW ophthalmoscopically and 19.2 mW angiographically. Speckle factors were found to be 1.225 for the Nd:YLF and 3.180 for the argon laser. Thus, the maximal ED50 -threshold radiant exposures for the Nd:YLF were calculated to be 362 mJ/cM2 (5 micros), 478 mJ/cm2 (1.7 micros), and 438 mJ/cm2 (200 ns) ophthalmoscopically. Angiographically, the thresholds were 189 mJ/cm2 (5 micros), 143 mJ/cm2 (1.7 micros), and 97 mJ/cm2 (200 ns). For the argon laser, the maximal ED50 radiant exposure threshold was 170 mJ/cm2 angiographically. CONCLUSION: The gap between the angiographic and the ophthalmoscopic thresholds for the 200 ns regime (4.5 times above angiographic ED50) was wider than for the 1.7 micros regime (3.3 times above the angiographic ED50). This would suggest the appropriate treatment would be 200 ns pulses. However, histologies have yet to prove that nonvisible mechanical effects increase with shorter pulse durations and could reduce the "therapeutic window." When comparing the thresholds with 5 micros pulses from the argon and Nd:YLF laser, it demonstrates that intensity modulations in the beam profile must be considered.     

Quantitative determination of the dual COX-2/5-LOX inhibitor tryptanthrin in Isatis tinctoria by ESI-LC-MS

Isatis tinctoria L. is an old European and Chinese dye plant and anti-inflammatory herb from which the potent cyclooxygenase-2 and 5-lipoxygenase inhibitor tryptanthrin (1) (indolo-[2,1-b]-quinazoline-6,12-dione) was recently isolated as one of the active principles. An HPLC method for the quantitative analysis of the compound in plant material was developed. Reproducible extraction was achieved by accelerated solvent extraction (ASE). Detection by UV at 254 and 387 nm and by electrospray-MS were compared. The low tryptanthrin content in the herb and possible interferences required isocratic high-performance liquid chromatography coupled with electrospray-MS in single ion mode. More than 70 Isatis samples of different origin were analyzed. The tryptanthrin content in leaf samples varied from 0.56 to 16.74 x 10(-3) %.     

Arylomycins A and B,new biaryl-bridged lipopeptide antibiotics produced by Streptomyces sp. Tü 6075. I. Taxonomy,fermentation, isolation and biological activities

New lipopeptide antibiotics, colourless arylomycins A series and yellow arylomycins B series were detected in the culture filtrate and mycelium extracts of Streptomyces sp. Tü 6075 by HPLC-diode-array and HPLC-electrospray-mass-spectrometry screening. Arylomycins are a family of lipohexapeptide antibiotics, which represent the first examples of biaryl-bridged lipopeptides. They show antibiotic activities against Gram-positive bacteria.     

Brain diffusion after single seizures

PURPOSE: Diffusion-weighted magnetic resonance imaging (DWI) after focal status epilepticus has demonstrated focal alterations of the apparent diffusion coefficient (ADC) in the epileptogenic zone. We hypothesized that localized dynamic alterations of brain diffusion during the immediate postictal state will be detectable by serial DWI and correlate with the epileptogenic zone. METHODS: Nine adult patients (four men, five women) with medically intractable epilepsy were prospectively examined with a total of 25 DWI scans taken 2-210 min after a seizure. RESULTS: The interictal ADC was significantly (p < 0.05) elevated in the ictogenic hippocampus in all patients with temporal lobe epilepsy. The following postictal changes of the ADC were seen: (a) decreases by maximally 25-31%, which were most pronounced in the epileptogenic zone (n = 2); (b) generalized ADC changes after generalized seizures (n = 1) or prolonged complex partial seizures (n = 2); (c) no major changes after short-lived seizures or if the time to first DWI scan was >15 min or both (n = 3); and (d) widespread bilateral ADC increases after a flumazenil-induced seizure (n = 1). CONCLUSIONS: ADC changes seen during serial postictal DWI are complex and appear to reflect origin and spread of the preceding seizure. A delineation of the epileptogenic zone appears to be possible only in complex-partial seizures of >60 s duration that do not secondarily generalize.     

Decremental Pulmonary Venous Pulse Propagation: Impact for Catheter Ablation in Focal Atrial Fibrillation

Background: Electrical isolation of pulmonary veins (PV's) is crucial to achieve success in catheter ablation for trigger elimination in focal atrial fibrillation (AF). To guide ostial PV radiofrequency (RF) delivery, it is necessary to identify the electrical breakthrough (EBT) between PV and left atrium. For this purpose, coronary sinus (CS) fixed rate pacing is commonly used. This study evaluated, whether CS extrastimulus pacing is superior in identifying the EBT area as compared to fixed rate pacing. Methods: In 9 patients (51 ± 10 years) undergoing a left sided electrophysiological study for AF ablation, 25 PV's (10 right and 15 left-sided PV's) were mapped using a 4 French fixed-wire catheter with eight 6 mm coiled Platinum electrodes in a distal looped configuration (Revelation Helix, Cardima Inc.). For mapping and ablation the electrode loop was positioned in the PV ostium rectangular to the longitudinal PV axis. EBT area was identified as those electrodes indicating the earliest PV signals during CS pacing. We measured number of EBT electrodes and time between EBT and the latest activated bipoles at the electrode loop during fixed rate and extrastimulus pacing. The reduction of two or more EBT electrodes was defined as a significant benefit in EBT identification. Results: In 22 of 25 PV's mapped PV potentials could be observed. Performing fixed rate pacing the EBT area was identified in a mean of 4.2 ± 1 electrodes, whereas using extrastimulus pacing, EBT area could be significantly reduced to 2.3 ± 0.8 electrodes. The time between EBT and latest electrode activated increased from 14 ± 7 ms to 22 ± 10 ms indicating an intrapulmonary conduction delay during extrastimulus pacing. In 13 of 22 PV's mapped (59%), extrastimulus pacing was beneficial in the identification of the EBT, as the primary target for RF delivery. Conclusions: CS extrastimulus pacing induces intra-PV decremental conduction properties allowing one to identify a more localised and smaller EBT area as the primary target for RF delivery. Performing PV ablation to treat focal AF, extrastimulus maneouvers allow to unmask the true EBT and thus may help to limit intrapulmonary RF delivery.