Muscle and reflex changes with varying joint angle in hemiparetic stroke

<p>Abstract</p> <p>Background</p> <p>Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint.</p> <p>Methods</p> <p>Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM). Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls.</p> <p>Results</p> <p>Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position.</p> <p>Conclusion</p> <p>In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated.</p> <p>Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects, suggesting that the non-paretic limb may not be a suitable control for studying neuromuscular properties of the ankle joint.</p> <p>Our findings will help elucidate the origins of the neuromuscular abnormalities associated with stroke-induced spasticity.</p

Treatment of postmenopausal osteoporosis with continuous daily oral alendronate in comparison with either placebo or intranasal salmon calcitonin

Alendronate sodium (ALN) is a potent amino bisphosphonate which specifically inhibits osteoclastic bone resorption and has been found to reverse bone loss in several animal models. To determine if daily oral ALN treatment could prevent or reverse bone loss in osteoporotic postmenopausal women, and to compare ALN to intranasal salmon calcitonin (CT), a 2-year, double-masked, randomized, placebo-controlled study was initiated at 9 clinical centers in Italy. Two hundred and eighty six postmenopausal women (age 48-76) with spinal bone mineral density (BMD) > or = 2 SD below adult mean peak, with or without vertebral crush fractures, were randomized to one of four treatment arms: ALN 10 mg daily, ALN 20 mg daily or matching placebo (these groups all double-masked), or CT 100 IU daily (open label) for 2 years. All patients received supplemental calcium (as carbonate) 500 mg daily. Bone mass was measured by dual-energy X-ray absorptiometry of the PA lumbar spine (LS) and proximal femur (femoral neck and trochanter) at 6-month intervals. Subject safety was measured through sequential clinical and laboratory evaluation. A planned 1-year interim analysis of this ongoing study was performed centrally in a manner that maintains the double-mask for all subjects receiving oral study drug. Relative to PBO, ALN at either 10 mg or 20 mg daily increased LS BMD by 4.7% and 6.1%, respectively; each increased femoral neck BMD by 3.1% and increased trochanter BMD by 3.3% and 3.8% respectively. In contrast, CT failed to significantly increase BMD of either the spine, femoral neck or trochanter, either relative to baseline or to PBO.(ABSTRACT TRUNCATED AT 250 WORDS

Adrenal response of male rats exposed to prenatal stress and early postnatal stimulation

Stress in pregnant rats caused by chronic immobilization alters the pattern of secretion of corticosterone and modifies the hypothalamic-pituitary-adrenal axis (HPA) of the fetus. Early postnatal handling, however, may reverse the effects of increased secretion of corticosterone. We investigated the effects of prenatal stress and postnatal handling on the activity of the HPA axis of male offspring of stressed female rats. Male 90-day-old rats from four groups were investigated: prenatally stressed animals without postnatal handling, prenatally stressed animals with postnatal handling, unstressed control animals with postnatal handling, and unstressed control animals without postnatal handling. After sacrifice, the adrenal glands were weighed to determine the adrenal-somatic index. Apoptosis was evaluated by TUNEL assay and active caspase-3 expression. We found that the adrenal gland cortex:medulla ratio increased in animals with prenatal stress and that eventually the stress caused apoptosis. Handling newborns to simulate maternal activity ameliorated some of the negative effects of prenatal stress.Fil: Liaudat, Ana Cecilia. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodríguez, N.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Chen, S.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Romanini, María Cristina. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vivas, A.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Rolando, A.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Gauna, H.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Mayer, N.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; Argentin

Efeitos de duas técnicas de incentivo respiratório na mobilidade toracoabdominal após cirurgia abdominal alta Effects of two respiratory incentive techniques on chest wall mobility after upper abdominal surgery

A cirurgia abdominal alta está associada a um risco elevado de complicações pulmonares que podem ser reduzidas pelo uso criterioso de manobras terapêuticas visando a expansão pulmonar. O objetivo foi comparar duas técnicas de incentivo respiratório na recuperação da dinâmica toracoabdominal em pacientes submetidos à cirurgia abdominal alta. O grupo de estudo experimental foi constituído por 16 pacientes internados na Clínica Cirúrgica do Hospital Universitário de Santa Maria distribuídos aleatoriamente em dois grupos: o grupo 1 foi constituído por dez pacientes que usaram o dispositivo Voldyne e o grupo 2, por seis pacientes submetidos ao padrão ventilatório com inspiração fracionada em três tempos. A expansibilidade toracoabdominal foi avaliada por cirtometria antes da cirurgia e no 1º, 3º¸ e 5º dias do pós-operatório (PO). Observou-se redução significativa dos valores de cirtometria no 1º PO que, gradualmente, foram sendo recuperados, não mais havendo diferença significativa no 5o PO em relação aos valores pré-operatórios em ambos os grupos. O grupo 1 obteve significativamente melhores índices de recuperação da mobilidade toracoabdominal do que o grupo 2. Também o tempo de recuperação do grupo 1 atingiu médias mais elevadas durante todo o período de PO investigado. Embora ambas as técnicas utilizadas fossem efetivas, o incentivo inspiratório por meio do Voldyne mostrou melhores resultados na recuperação da expansibilidade pulmonar após cirurgia abdominal alta.<br>Upper abdominal surgery is associated to increased risk of pulmonary complications, which may be lessened by judicious use of therapeutic maneuvers aimed at lung expansion. The purpose here was to compare two respiratory incentive techniques on recovery of thoracic-abdominal dynamics in patients having undergone upper abdominal surgery. Sixteen patients in such condition were randomly divided into group 1 (n=10), who did respiratory training with the Voldyne device, and group 2 (n=6), submitted to a split-inspiration pattern training. Chest wall expansion was rated by measuring thorax circumferences before surgery and on the 1st, 3rd, and 5th post-operative (PO) days. In both groups a significant decrease was found in circumference values on the 1st PO day, which gradually recovered, until on the 5th PO day no significant differences were found as compared to pre-operative measures. Group 1 showed significantly better thoracic-abdominal expansion rates than group 2's, as well as higher recovery time rates all through. Though both breathing techniques used were effective, inspiratory incentive using the Voldyne device showed better results in recovering chest mobility after upper abdominal surgery

Clinical genetic testing for familial melanoma in Italy: A cooperative study

Background: The Italian Society of Human Genetics'(SIGU) recommendations on genetic counseling and testing for hereditary melanoma state that clinical genetic testing can be offered to Italian melanoma families with at least two affected members. Objective: In the framework of a cooperative study, we sought to establish the frequency of cyclin-dependent kinase inhibitor 2,4 mutations in melanoma families that underwent clinical genetic Counseling and testing in accordance with die SIGU recommendations at 9 centers in different Italian regions. Methods: inhibitor 2A testing was conducted by direct sequencing and multiplex ligation-dependent probe amplification analysis in melanoma families with at least two affected members. Results: A total of 33% (68/204) of the families harbored cyclin-dependent kinase inhibitor 2A Mutations. In the 145 families with two affected members the mutation frequency was 25%. Three novel mutations, L94P, A86T, and c.407dupG, were identified among the cases and not in 200 controls. Limitations: We were unable to perform separate analyses for individual centers, as in some cases the number of families was too small. Conclusions: The availability of clinical genetic testing for melanoma to families with just two affected members in the same branch is justified in Italy in terms of the likelihood of identifying a mutation. (J Am Acad Dermatol 20001:775-82.