Anodal block in F-wave studies Kirshblum, Steven; Cai, Peiti; Johnston, Mark V. ...
Archives of physical medicine and rehabilitation,
09/1998, Letnik:
79, Številka:
9
Journal Article, Conference Proceeding
Recenzirano
Objective: To determine whether F-wave results differ with the anode proximal or distal to the cathode, ie, if clinical anodal block exists.
Design: Prospective study of 30 healthy volunteers ...undergoing nerve conduction and F-wave studies in one median nerve. A needle cathode electrode was used with a surface anode placed alternately proximal and distal to the cathode. The same electromyographer performed all studies with a Dantec Counterpoint machine.
Results: F-wave latencies were essentially unaffected by distal versus proximal positioning. Minimum, maximum, and mean F-wave latencies correlated extremely highly (
r = .973
to .988). For both F-wave and M-response latencies and amplitudes, differences between mean values obtained using the two methods were extremely small and were neither clinically nor statistically significant. The frequency of elicitation of F-waves may (
p < .05) have been slightly (3.5%) lower when the anode was in the distal position.
Conclusion: Anodal block is not seen in F-wave studies when using needle electrode stimulations. Reversing the stimulator does not seem to be required. Further study with surface stimulating electrodes is underway to confirm results.
Electrical energy is ubiquitous in the modern world, and in order to continue pushing boundaries on consumer wearables, electric vehicles, and grid storage, secondary lithium-based rechargeable ...batteries need to be enhanced. The performance of binary electrolytes is governed by the electrolyte thermodynamic factor and three transport properties: conductivity, salt diffusion coefficient, and transference number. Rigorous methods for measuring conductivity and the salt diffusion coefficient are well established in literature. NMR and the steady-state current method are often used to measure the transference number, but are predicated on the dilute solution assumption and do not fully consider the non-ideality of the electrolyte. Within this work, we elucidate a complete set of lithium-ion transport properties for mixtures of dimethyl carbonate terminated perfluorinated tetraethylene ether and lithium bis(fluorosulfonyl)imide (LiFSI). The steady-state current transference number is positive across all concentrations and decreases with salt concentration, while the NMR transference number is approximately 0.5 everywhere. In contrast, we find that the transference number using Newman’s concentrated solution theory is negative across all concentrations. We show that Newman’s concentrated solution theory allows for accurate potential and limiting current modeling of lithium half cells whereas the steady-state current transference number severely over-estimates the electrolyte’s limiting current. The disparity between the dilute solution theory measurements and that of Newman’s concentrated solution theory approach indicates the dominance of ion clustering.
Figure 1
A 47-year-old woman known to have retinitis pigmentosa (RP) developed macular holes in each eye. Examination and fluorescein angiography demonstrated a partial thickness macular hole in the right eye ...and a full thickness one in the left eye. It was concluded that macular hole formation can occur in patients with RP, but the exact cause of macular hole development in these patients is uncertain.
Ophthalmic Surg Lasers 2002;33:152-154
A study of fatty-acid ratios in French fries has proved to be an excellent choice for an entry-level research class. This research develops reasoning skills and involves the subject of breast cancer, ...a major concern of American society. Analysis of tumor samples removed from women with breast cancer revealed high ratios of linoleic to linolenic acid, suggesting a link between the accelerated growth of breast tumors and the combination of these two fatty acids. When the ratio of linoleic to linolenic acid was approximately 9 to 1, accelerated growth was observed. Since these fatty acids are found in cooking oils, Wichita Collegiate students, under the guidance of their chemistry teacher, decided that an investigation of the ratios of these two fatty acids should be conducted. A research class was structured using a gas chromatograph for the analysis. Separation of linoleic from linolenic acid was successfully accomplished. The students experienced inductive experimental research chemistry as it applies to everyday life. The structure of this research class can serve as a model for high school and undergraduate college research curricula.
Regional myocardial echo contrast appearance-disappearance after intracoronary contrast agent injection was examined with computerized two-dimensional contrast echocardiography in eight open chest ...dogs during successive variation of the coronary blood supply. A new sonication method applied to dextrose 50% produced an echo contrast agent with a microbubble size of 12 ± 6 μ (mean ± standard deviation), and 1 cc of this agent was injected into a coronary artery during the echocar-diographic study of the left ventricle. Left anterior descending or circumflex coronary artery flow, measured by electromagnetic flowmeter, was successively reduced up to 90% with an extravascular hydraulic occluder, or else increased 40 to 60% through intravenous dipyridamole infusion (7 to 10 μg/kg per min). The corresponding myocardial echo time-intensity curves were analyzed for each of 12 segments of a midventricular short-axis cross section.
Several potential indexes of myocardial perfusion were derived: peak echo contrast intensity, time from echo contrast appearance to peak intensity, half-life of echo contrast decay phase (T½ and total duration of contrast appearance-disappearance. Except for peak intensity, all of these indexes provided significant (p < 0.05) differentiation between control coronary flow (66 ± 17 nil/min) and greater than 50% flow reductions (26 ± 6 nil/min) or hyperemia (115 ± 17 ml/min). Half-life values were 5.2 ± 0.3 seconds for the control state, 9 ± 2 seconds for the reduced coronary flow and 2 ± 2 seconds for dipyridamole hyperemia. Compared with an echo contrast-delineated circumferential extent of 5.6 ±1.4 myocardial segments subserved from the site of the coronary occluder, greater than 50% flow reduction significantly decreased contrast disappearance T½ in 3.7 ± 1.7 segments versus decreased systolic wall thickening in 6.6 ±1.4 segments. T½ for the central ischemic zone correlated moderately with coronary flow (r = 0.56, p < 0.05).
It is concluded that myocardial contrast two-dimensional echocardiography, using small microbubbles as the agent, can identify a primary perfusion defect and may permit characterization of myocardial blood supply.
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