Error Bounds for Dynamical Spectral Estimation.

Dynamical spectral estimation is a well-established numerical approach for estimating eigenvalues and eigenfunctions of the Markov transition operator from trajectory data. Although the approach has been widely applied in biomolecular simulations, its error properties remain poorly understood. Here we analyze the error of a dynamical spectral estimation method called "the variational approach to conformational dynamics" (VAC).

The community FabLab platform: applications and implications in biomedical engineering.

Skill development in science, technology, engineering and math (STEM) education present one of the most formidable challenges of modern society. The Community FabLab platform presents a viable solution. Each FabLab contains a suite of modern computer numerical control (CNC) equipment, electronics and computing hardware and design, programming, computer aided design (CAD) and computer aided machining (CAM) software.

STEM promotion through museum exhibits on cardiac monitoring & cardiac rhythm management.

Formal education in science, technology, engineering and math (STEM) does not successfully engage all of the students who have potential to become skilled in STEM activities and careers. Museum exhibits may be able to reach and engage a broader range of the public. STEM Exhibits that are both understandable and capture the imagination of viewers may contribute toward increased interest in STEM activities.

Detection of respiration in central venous pressure using state machine.

Reliable information from patient monitors enhances treatment for critically ill patients. Redundant sources for information would aid identification of faulty sensors and leads, and improve presentation of physiological data. Respiratory information can be obtained from several sources, including airway pressure and central venous pressure (CVP).

Historical development of heat stroke prevention device in the military.

Understanding of core body temperature, heat stress and heat stroke developed progressively over the centuries. Soldiers involved in military operations have a higher risk to develop heat stroke, and to not survive following the onset. This paper follows the evolving understanding of heat stroke and development of counter measures.

Correlation of respiratory activity of contralateral diaphragm muscles for evaluation of recovery following hemiparesis.

Respiration is impaired by disruption of the central drive for inspiration to the diaphragm muscle (DIAm). Some function may recover involving nerve regeneration, reinnervation or neuroplasticity. A research animal model involves inducing hemiparesis of the DIAm and monitoring any recovery under different conditions.

Microelectrical sensors as emerging platforms for protein biomarker detection in point-of-care diagnostics.

Current methods used to measure protein expression on microarrays, such as labeled fluorescent imaging, are not well suited for real-time, diagnostic measurements at the point of care. Studies have shown that microelectrical sensors utilizing silica nanowire, impedimetric, surface acoustic wave, magnetic nanoparticle and microantenna technologies have the potential to impact disease diagnosis by offering sensing characteristics that rival conventional sensing techniques. Their ability to transduce protein binding events into electrical signals may prove essential for the development of next-generation point-of-care devices for molecular diagnostics, where they could be easily integrated with microarray, microfluidic and telemetry technologies.

Cardiac cells implanted into a cylindrical, vascularized chamber in vivo: pressure generation and morphology.

We have previously described a model to implant dissociated cells into a cylindrical, vascularized bed in vivo to promote the formation of functional cardiac muscle constructs. We now investigate the cellular organization and the ability of the constructs to generate intra-luminal pressure. Primary cardiac cells were isolated from hearts of 2-3 day old rats, suspended in fibrin gel and inserted into the lumen of silicone tubing.

Methodology for the formation of functional, cell-based cardiac pressure generation constructs in vitro.

We have previously described a model to engineer three-dimensional (3-D) heart muscle in vitro. In the current study, we extend our model of 3-D heart muscle to engineer a functional cell-based cardiac pressure generating construct (CPGC). Tubular constructs were fabricated utilizing a phase separation method with chitosan as the scaffolding material.

Electrical stimulation prior to delayed reinnervation does not enhance recovery in muscles of rats.

Purpose: Prolonged denervation of skeletal muscles results in atrophy and poor recovery of motor function following delayed reinnervation. Electrical stimulation reduces denervation atrophy. We hypothesized that electrical stimulation of denervated extensor digitorum longus (EDL) muscles during a prolonged period between nerve axotomy and opportunity for reinnervation by motoneurons after nerve-repair would enhance the recovery of muscle mass, force and motor-function.

EMG-based detection of inspiration in the rat diaphragm muscle.

An algorithm to detect the timing of each breath from an electromyogram (EMG) signal was developed. The algorithm has low computation cost and would be suitable for applications of implantable diaphragm pacing devices or as a trigger for each breath generated by a mechanical ventilator. The algorithm was implemented both in a Lab View program on a desktop computer and in a C program on a microcontroller chip, and was tested on the EMG signal from the left diaphragm muscle of an anesthetized rat via implanted electrodes.

Excitability of skeletal muscle during development, denervation, and tissue culture.

A quantitative understanding of the bulk excitability of skeletal muscle tissues is important for the design of muscle tissue bioreactor systems, implantable muscle stimulators, and other systems where electrical pulses are employed to elicit contractions in muscle tissue both in vitro and in vivo. The purpose of the present study is to systematically compare the excitability of mammalian (rat) skeletal muscle under a range of conditions (including neonatal development, denervation, and chronic in vivo stimulation of denervated muscle) and of self-organized muscle tissue constructs engineered in vitro from both primary cells and cell lines. Excitability is represented by rheobase (R(50), units = V/mm) and chronaxie (C(50), units = microseconds) values, with lower values for each indicating greater excitability.

Neurotization improves contractile forces of tissue-engineered skeletal muscle.

Engineered functional skeletal muscle would be beneficial in reconstructive surgery. Our previous work successfully generated 3-dimensional vascularized skeletal muscle in vivo. Because neural signals direct muscle maturation, we hypothesized that neurotization of these constructs would increase their contractile force.

Tissue-engineered axially vascularized contractile skeletal muscle.

Background: As tissue-engineered muscle constructs increase in scale, their size is limited by the need for a vascular supply. In this work, the authors demonstrate a method of producing three-dimensional contractile skeletal muscles in vivo by incorporating an axial vascular pedicle.

Methods: Primary myoblast cultures were generated from adult F344 rat soleus muscle.

Electrical stimulation of denervated muscles of rats maintains mass and force, but not recovery following grafting.

Purpose: Denervated skeletal muscles lack contractile activity and subsequently lose mass and force generation. Prolonged periods of denervation prior to nerve-implant grafting limit the recovery of mass and force. We hypothesized that electrical stimulation during a period of denervation that maintains mass and force above the levels of denervated muscles enhances the recovery of mass and force following nerve-implant grafting.

Tissue engineering of recellularized small-diameter vascular grafts.

A tissue-engineered small-diameter arterial graft would be of benefit to patients requiring vascular reconstructive procedures. Our objective was to produce a tissue-engineered vascular graft with a high patency rate that could withstand arterial pressures. Rat arteries were acellularized with a series of detergent solutions, recellularized by incubation with a primary culture of endothelial cells, and implanted as interposition grafts in the common femoral artery.

Electrical stimulation attenuates denervation and age-related atrophy in extensor digitorum longus muscles of old rats.

Skeletal muscles of old rats and elderly humans lose muscle mass and maximum force. Denervation is a major cause of age-related muscle atrophy and weakness, because denervated fibers do not contract, and undergo atrophy. At any age, surgical denervation causes even more dramatic muscle atrophy and loss in force than aging does.

Distribution of rest periods between electrically generated contractions in denervated muscles of rats.

Stimulation protocols for denervated muscles distribute the generated contractions either within treatment sessions followed by hours of rest, or repeated 24 h per day with each contraction followed by a constant interval of rest. Our purpose was to directly compare the effects of the same number of identically generated contractions having different temporal daily distributions. For 5 weeks in denervated extensor digitorum longus muscles of rats, between 100 and 800 contractions were generated daily, distributed either within worksets that alternated periods of activity and rest, or separated by constant intervals of rest.

Comparison of gene expression of 2-mo denervated, 2-mo stimulated-denervated, and control rat skeletal muscles.

Loss of innervation in skeletal muscles leads to degeneration, atrophy, and loss of force. These dramatic changes are reflected in modifications of the mRNA expression of a large number of genes. Our goal was to clarify the broad spectrum of molecular events associated with long-term denervation of skeletal muscles.

Number of contractions to maintain mass and force of a denervated rat muscle.

Within 5 weeks, denervated extensor digitorum longus (EDL) muscles of rats lose 66% of mass, 91% of force, and 76% of fiber cross-sectional area (CSA). We previously determined the parameters of electrical stimulation for denervated rat EDL muscles to generate tetanic contractions sufficient to maintain mass and force close to control values. Using these parameters, we tested the hypothesis that a range exists for number of contractions per day, below and above which values for mass, maximum force, and fiber CSA are lower than values for innervated control muscles.

An implantable device for stimulation of denervated muscles in rats.

The purposes of the present study were (1) to develop an implantable device capable of being pre-programmed to generate a protocol of chronic contractions in denervated hind-limb muscles of rats, and (2) to verify the design by implanting the stimulators for five weeks in rats to identify a protocol of stimulation that maintains muscle mass and maximum force in stimulated-denervated extensor digitorum longus (EDL) muscles. This implantable stimulator system did not hinder animal movement or hygiene, and enabled the animals to be housed in regular animal facilities, since neither external equipment nor an externally generated magnetic field was required. The pre-programmable microcontroller allows detailed basic research into the cellular and tissue response to different stimulation protocols.

Environmental versus social factors as determinants of growth in nestlings of a communally breeding bird.

Nestlings of the communally breeding Greycrowned Babbler (Pomatostomus temporalis) were studied to discover if supplemental feeding by auxiliary birds at nests enhanced their growth. Growth of wing, bill, tarsus and weight was measured. Growth curves were fitted by computer using a commercial program (MLAB).