Hand Grip-EMG Muscle Response

One of the most important factors in hand-arm system research is the information about hand grip force and pressing force on a tool handle. This article focuses on an alternative method to measure grip force. For grip force, one of the most popular solutions is a special handle with force sensors. However, when we want to use it with regular hand tool like e.g. a drill, it seems to be uncomfortable because we must interfere in handle construction. A solution proposed in this article is based on technique for evaluating and recording the electrical activity produced by muscles, electromyography (EMG). It has been assumed that EMG signal will be proportional to muscle tension responsible for palm grip. This solution have one significant advantage when comparing to special handle. It can be used with regular tool without interfering in the handle. Measurement presented in this article have been carried out with use of surface electromyography (sEMG). It is not invasive method which enables to measure EMG signal through placing stickers with electrodes directly on a skin

The Effect of Plate Discretization on Accuracy of the Sound Radiation Efficiency Measurements

This paper deals with the problem of the effect of discretization level and certain other parameters characterizing the measurement setup on accuracy of the process of determination of the sound radiation efficiency by means of the Discrete Calculation Method (DCM) described by Hashimoto (2001). The idea behind DCM consists in virtual division of an examined sound radiating structure into rectangular elements each of which is further assumed to contribute to the total radiation effect in the same way as a rigid circular piston having the surface area equal to this of the corresponding virtual element and vibrating in an infinite rigid baffle. The advantage of the method over conventional sound radiation efficiency measurement techniques consists in the fact that instead of acoustic pressure values, source (plate) vibration velocity amplitude values are measured in a selected number of regularly distributed points. In many cases, this allows to determine the sound radiation efficiency with sufficient accuracy, especially for the low frequency regime. The key part of the paper is an analysis of the effect of discretization level (i.e. the choice of the number of points at which vibration amplitude measurements are to be taken with the use of accelerometers) on results obtained with the use of the method and their accuracy. The problem of determining an optimum level of discretization for given excitation frequency range is a very important issue as the labor intensity (time-consuming aspect) of the method is one of its main flaws. As far as the technical aspect of the method is concerned, two different geometrical configurations of the measurement setup were tested

Brief communication: radiographic contrast infusion and catecholamine release in patients with pheochromocytoma.

Contains fulltext : 80765timmers.pdf (publisher's version ) (Closed access)BACKGROUND: Contrast-enhanced computed tomography (CT) is useful for localizing pheochromocytoma. However, in patients with suspected pheochromocytoma, CT is often canceled or not performed because of the strong belief that intravenous contrast may induce hypertensive crisis. OBJECTIVE: To examine whether intravenous low-osmolar contrast administration during CT induces catecholamine release that increases blood pressure or heart rate. DESIGN: Prospective study. SETTING: Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland. PARTICIPANTS: 22 patients with pheochromocytoma (15 nonadrenal and 7 adrenal) and 8 unmatched control participants without pheochromocytoma. MEASUREMENTS: Plasma catecholamine levels, blood pressure, and heart rate. RESULTS: Plasma catecholamine levels within and between groups did not significantly differ before and after intravenous administration of low-osmolar CT contrast. Patients with pheochromocytoma experienced a clinically and statistically significant increase in diastolic blood pressure that was not accompanied by corresponding increases in plasma catecholamine levels. The difference became non-statistically significant after adjustment for use of alpha- and beta-blockers. Limitation: The study lacked a placebo group, and the sample was relatively small. CONCLUSION: Intravenous low-osmolar contrast-enhanced CT can safely be used in patients with pheochromocytoma who are not receiving alpha- or beta-blockers. Funding: Eunice Kennedy Shriver National Institute of Child Health and Development, National Institutes of Health

Clinical presentations, biochemical phenotypes, and genotype-phenotype correlations in patients with succinate dehydrogenase subunit B-associated pheochromocytomas and paragangliomas.

CONTEXT: Mutations of the gene encoding succinate dehydrogenase subunit B (SDHB) predispose to malignant paraganglioma (PGL). Recognition of the SDHB phenotype in apparently sporadic PGL directs appropriate treatment and family screening. OBJECTIVE: The objective of the study was to assess mutation-specific clinical and biochemical characteristics of SDHB-related PGL. DESIGN: The study design was retrospective descriptive. Patients: Patients included 29 patients (16 males) with SDHB-related abdominal or thoracic PGL. INTERVENTION: There was no intervention. MAIN OUTCOME MEASURES: Clinical presentations, plasma and urine concentrations of catecholamines and O-methylated metabolites, and genotype-phenotype correlations were measured. RESULTS: Mean +/- sd age at diagnosis was 33.7 +/- 15.7 yr. Tumor-related pain was among the presenting symptoms in 54% of patients and was the sole symptom in 14%. Seventy-six percent had hypertension, and 90% lacked a family history of PGL. All primary tumors but one originated from extraadrenal locations. Mean +/- sd tumor size was 7.8 +/- 3.7 cm. In this referral-based study, 28% presented with metastatic disease and all but one eventually developed metastases after 2.7 +/- 4.1 yr. Ten percent had additional head and neck PGLs. The biochemical phenotype was consistent with hypersecretion of both norepinephrine and dopamine in 46%, norepinephrine only in 41%, and dopamine only in 3%. Ten percent had normal catecholamine (metabolite) levels, consistent with biochemically silent PGL. No obvious genotype-phenotype correlations were identified. CONCLUSIONS: SDHB-related PGL often presents as apparently sporadic PGL with symptoms related to tumor mass effect rather than to catecholamine excess. The predominant biochemical phenotype consists of hypersecretion of norepinephrine and/or dopamine, whereas 10% of tumors are biochemically silent. The clinical expression of these tumors cannot be predicted by the genotype

Superiority of fluorodeoxyglucose positron emission tomography to other functional imaging techniques in the evaluation of metastatic SDHB-associated pheochromocytoma and paraganglioma.

Contains fulltext : 53007.pdf (publisher's version ) (Closed access)PURPOSE: Germline mutations of the gene encoding subunit B of the mitochondrial enzyme succinate dehydrogenase (SDHB) predispose to malignant paraganglioma (PGL). Timely and accurate localization of these aggressive tumors is critical for guiding optimal treatment. Our aim is to evaluate the performance of functional imaging modalities in the detection of metastatic lesions of SDHB-associated PGL. PATIENTS AND METHODS: Sensitivities for the detection of metastases were compared between [18F]fluorodopamine ([18F]FDA) and [18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET), iodine-123- (123I) and iodine-131 (131I) -metaiodobenzylguanidine (MIBG), 111In-pentetreotide, and Tc-99m-methylene diphosphonate bone scintigraphy in 30 patients with SDHB-associated PGL. Computed tomography (CT) and magnetic resonance imaging (MRI) served as standards of reference. RESULTS: Twenty-nine of 30 patients had metastatic lesions. In two patients, obvious metastatic lesions on functional imaging were missed by CT and MRI. Sensitivity according to patient/body region was 80%/65% for 123I-MIBG and 88%/70% for [18F]FDA-PET. False-negative results on 123I-MIBG scintigraphy and/or [18F]FDA-PET were not predicted by genotype or biochemical phenotype. [18F]FDG-PET yielded a by patient/by body region sensitivity of 100%/97%. At least 90% of regions that were false negative on 123I-MIBG scintigraphy or [18F]FDA-PET were detected by [18F]FDG-PET. In two patients, 111In-pentetreotide scintigraphy detected liver lesions that were negative on other functional imaging modalities. Sensitivities were similar before and after chemotherapy or 131I-MIBG treatment, except for a trend toward lower post- (60%/41%) versus pretreatment (80%/65%) sensitivity of 123I-MIBG scintigraphy. CONCLUSION: With a sensitivity approaching 100%, [18F]FDG-PET is the preferred functional imaging modality for staging and treatment monitoring of SDHB-related metastatic PGL

Penetrance and clinical consequences of a gross SDHB deletion in a large family.

Mutations in the gene encoding subunit B of the mitochondrial enzyme succinate dehydrogenase (SDHB) are inherited in an autosomal dominant manner and are associated with hereditary paraganglioma (PGL) and pheochromocytoma. The phenotype of patients with SDHB point mutations has been previously described. However, the phenotype and penetrance of gross SDHB deletions have not been well characterized as they are rarely described. The objective was to describe the phenotype and estimate the penetrance of an exon 1 large SDHB deletion in one kindred. A retrospective and prospective study of 41 relatives across five generations was carried out. The main outcome measures were genetic testing, clinical presentations, plasma catecholamines and their O-methylated metabolites. Of the 41 mutation carriers identified, 11 were diagnosed with PGL, 12 were found to be healthy carriers after evaluation, and 18 were reportedly healthy based on family history accounts. The penetrance of PGL related to the exon 1 large SDHB deletion in this family was estimated to be 35% by age 40. Variable expressivity of the phenotype associated with a large exon 1 SDHB deletion was observed, including low penetrance, diverse primary PGL tumor locations, and malignant potential

Role of positron emission tomography and bone scintigraphy in the evaluation of bone involvement in metastatic pheochromocytoma and paraganglioma: specific implications for succinate dehydrogenase enzyme subunit B gene mutations.

Contains fulltext : 71093timmers.pdf (publisher's version ) (Closed access)We performed a retrospective analysis of 71 subjects with metastatic pheochromocytoma and paraganglioma (30 subjects with mutation of succinate dehydrogenase enzyme subunit B (SDHB) gene and 41 subjects without SDHB mutation). Sixty-nine percent presented with bone metastases (SDHB +/-: 77% vs 63%), 39% with liver metastases (SDHB +/-: 27% vs 47%), and 32% with lung metastases (SDHB +/-: 37% vs 29%). The most common sites of bone involvement were thoracic spine (80%; SDHB+/-: 83% vs 77%), lumbar spine (78%; SDHB +/-: 78% vs 75%), and pelvic and sacral bones (78%; SDHB +/-: 91% vs 65%, P=0.04). Subjects with SDHB mutation also showed significantly higher involvement of long bones (SDHB +/-: 78% vs 30%, P=0.007) than those without the mutation. The best overall sensitivity in detecting bone metastases demonstrated positron emission tomography (PET) with 6-[(18)F]-fluorodopamine ([(18)F]-FDA; 90%), followed by bone scintigraphy (82%), computed tomography or magnetic resonance imaging (CT/MRI; 78%), 2-[(18)F]-fluoro-2-deoxy-d-glucose ([(18)F]-FDG) PET (76%), and scintigraphy with [(123/131)I]-metaiodobenzylguanidine (71%). In subjects with SDHB mutation, imaging modalities with best sensitivities for detecting bone metastases were CT/MRI (96%), bone scintigraphy (95%), and [(18)F]-FDG PET (92%). In subjects without SDHB mutations, the modality with the best sensitivity for bone metastases was [(18)F]-FDA PET (100%). In conclusion, bone scintigraphy should be used in the staging of patients with malignant pheochromocytoma and paraganglioma, particularly in patients with SDHB mutations. As for PET imaging, [(18)F]-FDG PET is highly recommended in SDHB mutation patients, whereas [(18)F]-FDA PET is recommended in patients without the mutation