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1.
Biomechanical comparison of stimulated and nonstimulated skeletal muscle pulled to failure 总被引:1,自引:0,他引:1
W E Garrett M R Safran A V Seaber R R Glisson B M Ribbeck 《The American journal of sports medicine》1987,15(5):448-454
We compared the biomechanical properties of passive and stimulated muscle rapidly lengthened to failure in an experimental animal model. The mechanical parameters compared were force to tear, change in length to tear, site of failure, and energy absorbed by the muscle-tendon unit before failure. Paired comparisons were made between 1) muscles stimulated at 64 Hz (tetanic stimulation) and passive (no stimulation) muscles, 2) muscles stimulated at 16 Hz (wave-summated stimulation) and passive muscles, and 3) muscles stimulated at 64 Hz and at 16 Hz. Both tetanically stimulated and wave-summation contracted muscles required a greater force to tear (at 64 Hz, 12.86 N more, P less than 0.0004; and at 16 Hz, 17.79 N more, P less than 0.003) than their nonstimulated controls, while there was no statistical difference in failure force between muscles stimulated at 16 Hz and 64 Hz. The energy absorbed was statistically greater for the stimulated muscles than for the passive muscles in Groups 1 and 2 (at 64 Hz, 100% more, P less than 0.0003; and 16 Hz, 88% more, P less than 0.0002). In Group 3, the tetanically contracted muscle-tendon units absorbed 18% more energy than the wave-summated stimulated muscles (P less than 0.01). All muscles tore at the distal musculotendinous junction, and there was no difference in the length increase at tear between muscles in each group. These findings may lead to enhanced understanding of the mechanism and physiology of muscle strain injuries. 相似文献
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J A Garrett J L Stewart 《Asia-Pacific journal of public health / Asia-Pacific Academic Consortium for Public Health》1989,3(3):213-218
In less than two decades, there has been a dramatic reduction in the prevalence of otitis media and perforations among Guam's school-aged children. In addition, hearing loss due to chronic middle ear disease as a cause of disqualification from military service has dropped from a first rank order cause to next-to-last. However, there has been no reduction in the prevalence of otitis media in the preschool population. The reduction in chronic ear disease is the result of improved access to primary care, intensive hearing screening, wide availability of audiologic diagnostic and follow-up services, and comprehensive otologic care. It is essential that these services continue to be available to Guam's children to avoid a reversal of these dramatic gains. Attention must now focus on how to achieve similar gains for Micronesian children who remain restricted in their access to these resources. 相似文献
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Kelly Garrett Allison Butler Wayne R Cohen 《The journal of maternal-fetal & neonatal medicine》2005,17(1):49-53
OBJECTIVE: To characterize dysfunctional labors that lead to cesarean delivery in the second stage and to assess the accuracy of diagnoses of abnormal fetal descent. METHODS: Thirty-one patients delivered by cesarean during the second stage because of abnormal labor or presumed cephalopelvic disproportion were studied and compared to 62 control cesarean cases delivered for the same indications in the first stage. The clinical diagnosis of dysfunctional labor that led to the cesarean was compared to the diagnosis made by retrospective analysis of the labor curves. RESULTS: Cases did not differ from controls delivered in the first stage in maternal age, race, parity, gestational age, weight gain, or the frequency of associated medical complications. The newborns were not significantly different in birth weight,ponderal index, sex, or the incidence of low Apgar scores. Among study patients, 94% had a second stage labor dysfunction determined by graphic labor analysis, predominantly arrest of descent (69%) and failure of descent (28%). In 79% of cases a dysfunctional first stage preceded the abnormal second stage. Among these first stage labor abnormalities, 68% were not recognized during the labor. CONCLUSION: Characteristics of patients delivered by cesarean during the second stage were similar to those delivered before full cervical dilatation. Second stage labor abnormalities were usually preceded by an abnormal first stage. There was considerable inaccuracy in the diagnosis of second stage labor dysfunction. 相似文献
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Many people die in emergency departments (EDs) across the United States from sudden illnesses or injuries, an exacerbation of a chronic disease, or a terminal illness. Frequently, patients and families come to the ED seeking lifesaving or life-prolonging treatment. In addition, the ED is a place of transition-patients usually are transferred to an inpatient unit, transferred to another hospital, or discharged home. Rarely are patients supposed to remain in the ED. Currently, there is an increasing amount of literature related to end-of-life care. However, these end-of-life care models are based on chronic disease trajectories and have difficulty accommodating sudden-death trajectories common in the ED. There is very little information about end-of-life care in the ED. This article explores ED culture and characteristics, and examines the applicability of current end-of-life care models. 相似文献
9.
Background - A case of primary thyroid T cell lymphoma leading to lethal tracheal perforation during chemotherapy is described. 相似文献
10.
Changes in regional ventilation and perfusion of the lung after endoscopic laser treatment. 总被引:4,自引:2,他引:2
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To determine whether endoscopic laser treatment improves both ventilation and perfusion in patients with advanced lung cancer, krypton-81m ventilation and technetium-99m labelled macro-aggregate perfusion scanning was performed immediately before and two or four days after treatment in a consecutive series of 28 patients. Twelve patients had not received any other treatment before laser therapy and 16 had undergone previous treatments that included radiotherapy. Ventilation and perfusion were quantified by expressing the number of counts in the affected lung as a percentage of the total counts. Ventilation and perfusion improved after laser treatment in 23 patients (82%). The mean ventilation score in the affected lung rose by 50% (p less than 0.001) and the mean perfusion score rose by 24% (p less than 0.001). Incremental changes in ventilation and perfusion scores were positively correlated (r = 0.80). Mean spirometric values, six minute walking distance, the Karnofsky performance index, and breathlessness and wellbeing scores also improved significantly. Patients with main bronchial obstruction who had had no radiotherapy showed the most striking improvements. It is concluded that the removal of intraluminal tumour from the bronchial tree leads to matched improvements in ventilation and perfusion in most patients and that this is associated with valuable improvement in symptoms. 相似文献