Image analysis of collagen-associated mineral distribution in cryogenically prepared turkey leg tendons

Summary This study is concerned with the cryogenic preservation of intrafibrillar apatite distribution in type I collagen of turkey leg tendons. Cryogenic specimen preparations by the rapid freezing of nonfixed and noncryoprotected leg tendons were performed by two different protocols: (1) low temperature substitution, fixation and staining followed by low temperature embedment; (2) frozen hydrated and air-dried cryosections were examined with the electron microscope at −165°C and normal operating temperatures, respectively. These protocols revealed the axial periodicity for mineralized collagen to have a 65–69 nm range with a mean value of 67 nm as determined by point-to-point measurements. Mineral distributions and specific apatite visualization were examined by electron microscopic imaging in bright field and selected-area dark field, respectively. Fourier filtered images and image subtraction were used to separate the axial repeating and nonrepeating intrafibrillar mineral domains of collagen. The removal of these axial repeats revealed an underlying and integrated mineral distribution, demonstrating that apatite is not confined to axial periodicities such as those of the gap zone.     

The Electrocardiographic Manifestation of Combined AV Nodal Wenckebach Periodicity and Reentry

Presented are three patients with Wenckebach type second degree AV block that was complicated with AV nodal reentry producing different arrhythmias. The common presentation of manifest AV nodal reentry is an incomplete Wenckebach periodicity, whereby the retrograde impulse interrupts the Wenckebach cycle; rarely, the retrograde impulse initiates an AV junctional reentrant tachycardia. The documentation of concealed AV nodal reentry is more difficult and should be considered if there is a sudden increase of the PR interval in the Wenckebach cycle.     

《内经》中生命运动周期性的研究

《内经》从多方面论述了生命运动的周期性,包括日周期、十日周期、月周期、年周期等,笔者以气血、脏腑、色脉为纲对其进行总结,阐述生命运动周期性对人体的影响,凸显生命运动周期的重要性,并提出顺应自然、协调周期的养生、治疗原则。     

Periodicity and prediction of mania onsets in biopolar I affective disorders

Abstract In studying the periodicity of mania onsets, cycle-oriented diagrams were made of the clinical course from 257 manic episodes analyzed retrospectively in 34 bipolar I manic-depressive patients for a period of about 5 years. Using these diagrams, the frequent period of mania onsets located in one-quarter of the follow-up period was pre-estimated, and the accordance ratio during a 25 month follow-up period was analyzed. The accordance ratio in all subjects was 39% (11/28) for the first episode and 35% (7/20) for the second episode. These ratios were not significantly different from the expected level (25%). The number of subjects was limited to 11 patients (10 rapid and 1 non-rapid cyclers) whose number of episodes used for the determination of the index cycle was eight or more. The accordance ratio was 64% (7/11) and 60% (6/10) for the first and second episodes, respectively. Their levels were significantly higher than those expected. Periodicity of mania onsets existed at least in rapid cyclers with abundant past data.     

生理信号时问序列周期性和平稳性对近似熵和样本熵算法的影响分析

目的提高近似熵和样本熵算法在评价生理信号时间序列非线性复杂度应用中的精度。方法首先生成生理信号时间序列数据库,通过对周期序列和叠加有周期成分的非线性序列的分析,研究序列周期性对熵测度算法的影响,并通过对心率变异性（hear trat evariability,HRV）序列在去除非平稳趋势前后的对比分析,研究序列平稳性对熵测度算法的影响。结果在序列长度范围内,不同重复频率的周期序列熵测度不同,不同比重的周期成分叠加到非线性序列中引起序列熵测度的变化也不同。生理信号时间序列中大都存在非平稳成分,而非平稳成分会降低序列的复杂度,因此进行熵测度计算前首先要去除非平稳成分。结论周期性和非平稳成分显著影响生理信号时间序列的熵测度算法。     

Peculiar lifespan changes of periodic leg movements during sleep in restless legs syndrome

The objective of this observational cohort study was to analyse the age‐related changes of periodic leg movements during sleep using the newest international scoring rules, to expand past analyses, including patients in the paediatric age range, and also to analyse the changes of short‐interval and isolated leg movements during sleep throughout the lifespan. One hundred and sixty‐five patients (84 women) with restless legs syndrome were recruited in the following age groups: 16 preschoolers (≤5 years of age), 29 school‐age children (6–12 years), 19 adolescents (13–17 years), 17 young adults (19–40 years), 47 adults (41–60 years) and 37 seniors (>60 years). Total, periodic, short‐interval and isolated leg movements during sleep and periodicity indexes were obtained by polysomnography. The total index showed (quartic polynomial interpolation) a decrease before 10 years, followed by a steady increase up to 30 years, a relatively stable period until 60 years, and a final increase up to 80 years. This course was almost entirely due to changes in periodic movements. Isolated movements did not change significantly and short‐interval movements showed only an increase in seniors. Our study indicates that, in restless legs syndrome, the total index shows a peculiar and unique course throughout the lifespan, mainly due to periodic movements. These age‐related changes may mirror developmental changes in network complexity known to occur in dopaminergic circuits. These data further confirm the need to better assess the periodicity of leg movements in sleep during the human development period, in order to obtain clinically useful information.     

AV nodal dual pathway electrophysiology and Wenckebach periodicity

Dual Pathways and Wenckebach Periodicity. Introduction: The precise mechanism(s) governing the phenomenon of AV nodal Wenckebach periodicity is not fully elucidated. Currently 2 hypotheses, the decremental conduction and the Rosenbluethian step‐delay, are most frequently used. We have provided new evidence that, in addition, dual pathway (DPW) electrophysiology is directly involved in the manifestation of AV nodal Wenckebach phenomenon. Methods and Results: AV nodal cellular action potentials (APs) were recorded from 6 rabbit AV node preparations during standard A1A2 and incremental pacing protocols. His electrogram alternans, a validated index of DPW electrophysiology, was used to monitor fast (FP) and slow (SP) pathway conduction. The data were collected in intact AV nodes, as well as after SP ablation. In all studied hearts the Wenckebach cycle started with FP propagation, followed by transition to SP until its ultimate block. During this process complex cellular APs were observed, with decremental foot formations reflecting the fading FP and second depolarizations produced by the SP. In addition, the AV node cells exhibited a progressive loss in maximal diastolic membrane potential (MDP) due to incomplete repolarization. The pause created with the blocked Wenckebach beat was associated with restoration of MDP and reinitiation of the conduction cycle via the FP wavefront. Conclusion: DPW electrophysiology is dynamically involved in the development of AV nodal Wenckebach periodicity. In the intact AV node, the cycle starts with FP that is progressively weakened and then replaced by SP propagation, until block occurs. AV nodal SP modification did not eliminate Wenckebach periodicity but strongly affected its paradigm. (J Cardiovasc Electrophysiol, Vol. pp.1‐7)     

Acidic pH Is Required for the Multilamellar Assembly of Skin Barrier Lipids In Vitro

1. Download : Download high-res image (183KB)
2. Download : Download full-size image