Altered excitation-contraction coupling in human chronic atrial fibrillation

This review focuses on the (mal)adaptive processes in atrial excitation-contraction coupling occurring in patients with chronic atrial fibrillation. Cellular remodeling includes shortening of the atrial action potential duration and effective refractory period, depressed intracellular Ca<sup>2+</sup> transient, and reduced myocyte contractility. Here we summarize the current knowledge of the ionic bases underlying these changes. Understanding the molecular mechanisms of excitation-contraction-coupling remodeling in the fibrillating human atria is important to identify new potential targets for AF therapy

Optimized Data Aggregation Method for Time, Privacy and Effort Reduction in Wireless Sensor Network

Wireless sensor networks (WSNs) have gained wide application in recent years, such as in intelligent transportation system, medical care, disaster rescue, structure health monitoring and so on. In these applications, since WSNs are multi-hop networks, and the sink nodes of WSNs require to gather every sensor node’s data, data aggregation is emerging as a critical function for WSNs. Reducing the latency of data aggregation attracts much research because many applications are event urgent. Data aggregation is ubiquitous in wireless sensor networks (WSNs). Much work investigates how to reduce the data aggregation latency. This paper considers the data aggregation method based on optimization of required time, maintain privacy while keeping lesser efforts by data aggregation in a wireless sensor network (WSN) and propose a method for the solution of the problem

Functional Anatomy of the Female Pelvic Floor

The anatomic structures in the female that prevent incontinence and genital organ prolapse on increases in abdominal pressure during daily activities include sphincteric and supportive systems. In the urethra, the action of the vesical neck and urethral sphincteric mechanisms maintains urethral closure pressure above bladder pressure. Decreases in the number of striated muscle fibers of the sphincter occur with age and parity. A supportive hammock under the urethra and vesical neck provides a firm backstop against which the urethra is compressed during increases in abdominal pressure to maintain urethral closure pressures above the rapidly increasing bladder pressure. This supporting layer consists of the anterior vaginal wall and the connective tissue that attaches it to the pelvic bones through the pubovaginal portion of the levator ani muscle, and the uterosacral and cardinal ligaments comprising the tendinous arch of the pelvic fascia. At rest the levator ani maintains closure of the urogenital hiatus. They are additionally recruited to maintain hiatal closure in the face of inertial loads related to visceral accelerations as well as abdominal pressurization in daily activities involving recruitment of the abdominal wall musculature and diaphragm. Vaginal birth is associated with an increased risk of levator ani defects, as well as genital organ prolapse and urinary incontinence. Computer models indicate that vaginal birth places the levator ani under tissue stretch ratios of up to 3.3 and the pudendal nerve under strains of up to 33%, respectively. Research is needed to better identify the pathomechanics of these conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72597/1/annals.1389.034.pd

TEMPERATURE INDUCED HISTOLOGICAL CHANGES IN THE FEMALE GONAD OF FRESHWATER BIVALVE, INDONAIA CAERULEUS (PRASHAD, 1918) DURING DIFFERENT SEASONS

The adult freshwater bivalve molluscs, Indonaia caeruleus (47-51 mm in shell-length) were collected and brought to laboratory from banks of Godavari river at Paithan, during different seasons. After 24 h laboratory acclimatization, they were exposed to normal water temperature of 28.5-31.0°C (served as control) during summer, 25.5-26.0°C during monsoon and 21.5-23.0°C during winter. For experimentation, the animal were exposed to the elevation of water temperature 34.0°C, 30.0'c and 27.0°C during summer, monsoon and winter respectively for 15 days. The histological study of the female gonads were made after 15 days. During different seasons, in control group the study revealed dominance of gametogenic phase during summer, developmental stages of oogonia during monsoon and maturation and release of oocytes during winter seasons. Due to elevation of temperature during different seasons, enlargement (growth) of oocytes as well as release of oocytes were observed at the expense of lipid globules and nutritive cells. The follicles of the female gonads expanded more and ovarian interfollicular connective tissue was observed to reduced, which was more pronounced at 34.0°C during summer compared to 30.0"C during monsoon and 27.0°C during winter season. However, in experimental group, normal development of oocytes were observed and they were released during monsoon and winter. More release of oocytes were observed during winter at 27.0°C. The results are discussed in the light of effect of elevation temperature on the histological structure of female gonadal tissues of bivalve mollusks, Indonaia caeruleus

Computing in Cardiology

671356

Human atrial action potential and Ca2+ model: sinus rhythm and chronic atrial fibrillation

<b>Rationale:</b> Understanding atrial fibrillation (AF) requires integrated understanding of ionic currents and Ca2+ transport in remodeled human atrium, but appropriate models are limited. <br></br> <b>Objective:</b> To study AF, we developed a new human atrial action potential (AP) model, derived from atrial experimental results and our human ventricular myocyte model. <br></br> <b>Methods and Results:</b> Atria versus ventricles have lower IK1, resulting in more depolarized resting membrane potential (≈7 mV). We used higher Ito,fast density in atrium, removed Ito,slow, and included an atrial-specific IKur. INCX and INaK densities were reduced in atrial versus ventricular myocytes according to experimental results. SERCA function was altered to reproduce human atrial myocyte Ca2+ transients. To simulate chronic AF, we reduced ICaL, Ito, IKur and SERCA, and increased IK1,IKs and INCX. We also investigated the link between Kv1.5 channelopathy, [Ca2+]i, and AF. The sinus rhythm model showed a typical human atrial AP morphology. Consistent with experiments, the model showed shorter APs and reduced AP duration shortening at increasing pacing frequencies in AF or when ICaL was partially blocked, suggesting a crucial role of Ca2+ and Na+ in this effect. This also explained blunted Ca2+ transient and rate-adaptation of [Ca2+]i and [Na+]i in chronic AF. Moreover, increasing [Na+]i and altered INaK and INCX causes rate-dependent atrial AP shortening. Blocking IKur to mimic Kv 1.5 loss-of-function increased [Ca2+]i and caused early afterdepolarizations under adrenergic stress, as observed experimentally. <br></br> <b>Conclusions:</b> Our study provides a novel tool and insights into ionic bases of atrioventricular AP differences, and shows how Na+ and Ca2+ homeostasis critically mediate abnormal repolarization in AF