Calculation of extracellular potentials produced by an inclined muscle fibre at a rectangular plate electrode

Generally the anatomy of muscles is rather complex, and the fibres have various inclination angles within the muscles. We suggest a fast and reliable way to calculate extracellular potentials produced at a point or rectangular plate electrode by a muscle fibre of finite length with an arbitrary inclination. A muscle fibre was considered to be a linear timeshift-invariant system of potential generation. Then, similar to the fibre without inclination, the extracellular potential produced by an inclined fibre was represented as the output signal of the system; it was calculated as the convolution of the input signal and impulse response. Irrespective of the inclination, the input signal of the system was the first temporal derivative of the intracellular action potential. The impulse response of the system differed for the fibres with inclination. This required a new method of analytical integration over the rectangular electrode area. The approach provides a chance to simulate and analyze motor unit potentials or F-, H- or M-responses produced by muscles of complicated anatomy (circum-pennate or complex pennate type) at electrodes of actual size and location in normals and patients with neuro-muscular disorders.     

Anatomical basis for pressure on the common peroneal nerve

An attempt was made to explain the anatomical basis for the pressure on the common peroneal nerve which may lead to loss of sensation and "foot drop". By using available cadavers during routine dissections, it was observed that the attachments of the peroneus longus muscle on the head of the fibula are, in most cases, tendinous, and blended with the crural fascia and lateral (fibular) ligament, thereby, forming an inelastic band arching over the common peroneal nerve. In some other cases, the reflected fibres of the biceps femoris tendon, anterior tibiofibular ligament and iliotibial tract constituted a fibrous bridge over the nerve. The least occurrence was that of the nerve piercing the thick and inelastic anterior crural septum.     

Influence of measurement inaccuracies on determination of left ventricular mass by M mode echocardiography.

OBJECTIVE: To determine to what extent inaccuracies in measuring the end diastolic diameter of the left ventricle, the interventricular septum, and the posterior wall, by M mode echocardiography influence the left ventricular mass calculated by the Devereux's formula. DESIGN: Mathematical model. RESULTS: Relatively small measurement inaccuracies such as 5%, which are known to be inherent in the echocardiographic method, will result in "changes" of left ventricular mass in the range of 8% to 15%. This is equivalent to expected changes in left ventricular mass seen during treatment. CONCLUSIONS: The use of Devereux's formula to calculate left ventricular mass is limited by measurement inaccuracies in individual patients.     

Computed tomography diagnosis of tracheobronchopathia osteochondroplastica

Tracheobronchopathia osteochondroplastica (TO) is a rare benign disease characterized by the presence of osseous and cartilaginous submucosal nodules projecting into the tracheobronchial tree. Most cases are asymptomatic and discovered incidentally at post‐mortem. We identified a case of TO on thoracic spiral CT and confirmed the diagnosis on bronchoscopy. This article reviews the imaging characteristics of TO, and shows the 3‐D virtual bronchoscopic and multiplanar reconstruction appearances of TO.     

Diagnosis of pulmonary embolism: Ventilation perfusion scintigraphy versus helical computed tomography pulmonary angiography

The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses.     

Longitudinal variations of characteristic frequencies of skeletal muscle fibre potentials detected by a bipolar electrode or multi-electrode

We aimed to reveal reasons for longitudinal variations of characteristic frequencies of electromyographic signals detected by surface longitudinal multi-electrodes. Since the terminal phases were reduced in bipolar recordings, wetested whether the frequency variations reflected the effects of the excitation origin and extinction as in monopolar recordings. A precise and fast convolution method to calculate the signals detected by a multielectrode was suggested. The contribution of different electrode poles was introduced in the impulse response. When a longitudinal multi-electrode with an even number of poles was positioned above the end-plate of asymmetrical fibres, the signal mainly reflected the processes of the excitation extinction. This increased the signal mean and median frequencies. Although the effects of origin and extinction of the excitation were significantly reduced in the spatially filtered signals, the frequency variations along the fibre reflected these intrinsic features of any skeletal muscle fibre of finite length.     

An Epizootiological Report of the Re‐emergence and Spread of a Lineage of Virulent Newcastle Disease Virus into Eastern Europe

A number of contemporary outbreaks of Newcastle disease (ND) in Israel, Turkey, Georgia and Bulgaria have all been caused by a very similar viruses related to lineage 5a (genotype VIIa). Comparison with published ND virus (NDV) sequences suggests that this virus strain originated in South‐East Asia and on introduction has circulated widely in backyard poultry in the Middle East and into Eastern Europe. An intracerebral pathogenicity index of 1.9 was obtained for a representative isolate from Bulgaria. In addition, the International Reference Laboratory for ND has characterized a molecular epidemiologically linked virus that has been reported to have caused disease in well‐vaccinated broiler chickens in Pakistan. In the 1990s, another strain from the 5a lineage NDV was introduced into Europe and spread across the continent causing numerous outbreaks up to 1999. Despite improved controls, including good diagnostic tests and widespread vaccination, in commercial poultry, the novel circulating NDV strains described here have been established widely in the region and represent an increased risk for similar disease outbreak events to reoccur within the EU.