http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Risk Factors for Adjacent Segment Disease Development after Lumbar Fusion
Sergei Masevnin,Dmitry Ptashnikov,Dmitry Michaylov,Hao Meng,Oleg Smekalenkov,Nikita Zaborovskii 대한척추외과학회 2015 Asian Spine Journal Vol.9 No.2
Study Design: Retrospective cohort study. Purpose: To identify factors which may be important in the occurrence of symptomatic adjacent segment disease (ASD) after lumbar fusion. Overview of Literature: Many reports have been published about the risk factors for ASD after lumbar fusion. Despite on the great numbers of risk factors identified for ASD development, study results have been inconsistent and there is controversy regarding which are the most important. Methods: This study evaluated 120 patients who underwent 360° fusion lumbar surgery from 2007 to 2012. We separated the population into two groups: the first group included 60 patients with long lumbar fusion (three or more levels) and the second group included 60 patients with short lumbar fusion (less than three levels). Results: In the first group, symptomatic ASD was found in 19 cases during the one year follow-up. There were 14 cases with sagittal imbalance and 5 cases at the incipient stage of disc degeneration according to the preoperative magnetic resonance imaging. At the three year follow-up, symptomatic ASD was diagnosed in 31 cases, of which 17 patients had postoperative sagittal balance disturbance. In the second group, 10 patients had ASD at the one year follow-up. Among these cases, preoperative disc degenerative changes were identified in 8 patients. Sagittal imbalance was found only in 2 cases with symptomatic ASD at the one year followup. At the three year follow-up, the number of patients with symptomatic ASD increased to 14. Among them, 13 patients had initial preoperative adjacent disc degenerative changes. Conclusions: Patients with postoperative sagittal imbalance have a statistically significant increased risk of developing symptomatic ASD due to an overloading the adjacent segments and limited compensatory capacities due to the large number of fixed mobile segments. In the case of a short fixation, preoperative degenerative changes are more important factors in the development of ASD.
Molecular Mechanisms of Primary Aldosteronism
Sergei G. Tevosian,Shawna C. Fox,Hans K. Ghayee 대한내분비학회 2019 Endocrinology and metabolism Vol.34 No.4
Primary aldosteronism (PA) results from excess production of mineralocorticoid hormone aldosterone by the adrenal cortex. It isnormally caused either by unilateral aldosterone-producing adenoma (APA) or by bilateral aldosterone excess as a result of bilateraladrenal hyperplasia. PA is the most common cause of secondary hypertension and associated morbidity and mortality. While mostcases of PA are sporadic, an important insight into this debilitating disease has been derived through investigating the familial formsof the disease that affect only a minor fraction of PA patients. The advent of gene expression profiling has shed light on the genes andintracellular signaling pathways that may play a role in the pathogenesis of these tumors. The genetic basis for several forms of familial PA has been uncovered in recent years although the list is likely to expand. Recently, the work from several laboratories provided evidence for the involvement of mammalian target of rapamycin pathway and inflammatory cytokines in APAs; however, theirmechanism of action in tumor development and pathophysiology remains to be understood.
Description of reversed yielding in thin hollow discs subject to external pressure
Sergei E. Alexandrov,Alexander R. Pirumov,Yeau-Ren Jeng 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.4
This paper presents an elastic/plastic model that neglects strain hardening during loading, but accounts for the Bauschinger effect. These mathematical features of the model represent reasonably well the actual behavior of several materials such as high strength steels. Previous attempts to describe the behavior of this kind of materials have been restricted to a class of boundary value problems in which the state of stress in the plastic region is completely controlled by the yield stress in tension or torsion. In particular, the yield stress is supposed to be constant during loading and the forward plastic strain reduces the yield stress to be used to describe reversed yielding. The new model generalizes this approach on plane stress problems assuming that the material obeys the von Mises yield criterion during loading. Then, the model is adopted to describe reversed yielding in thin hollow discs subject to external pressure.