Noninvasive Optical Quantification of Absolute Blood Flow, Blood Oxygenation, and Oxygen Consumption Rate in Exercising Skeletal Muscle

This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (V̇O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and V̇O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (rV̇O2). The rBF and rV̇O2 signals were calibrated with absolute baseline BF and V̇O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology

Hybrid Nanostructured Textile Bioelectrode for Unobtrusive Health Monitoring

Coronary heart disease, cardiovascular diseases and strokes are the leading causes of mortality in United States of America. Timely point-of-care health diagnostics and therapeutics for person suffering from these diseases can save thousands of lives. However, lack of accessible minimally intrusive health monitoring systems makes timely diagnosis difficult and sometimes impossible. To remedy this problem, a textile based nano-bio-sensor was developed and evaluated in this research. The sensor was made of novel array of vertically standing nanostructures that are conductive nano-fibers projecting from a conductive fabric. These sensor electrodes were tested for the quality of electrical contact that they made with the skin based on the fundamental skin impedance model and electromagnetic theory. The hybrid nanostructured dry electrodes provided large surface area and better contact with skin that improved electrode sensitivity and reduced the effect of changing skin properties, which are the problems usually faced by conventional dry textile electrodes. The dry electrodes can only register strong physiological signals because of high background noise levels, thus limiting the use of existing dry electrodes to heart rate measurement and respiration. Therefore, dry electrode systems cannot be used for recording complete ECG waveform, EEG or measurement of bioimpedance. Because of their improved sensitivity these hybrid nanostructured dry electrodes can be applied to measurement of ECG and bioimpedance with very low baseline noise. These textile based electrodes can be seamlessly integrated into garments of daily use such as vests and bra. In combination with embedded wireless network device that can communicate with smart phone, laptop or GPRS, they can function as wearable wireless health diagnostic systems

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 125

This special bibliography lists 323 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1974

Aerospace medicine and biology: A cumulative index to a continuing bibliography (supplement 384)

This publication is a cumulative index to the abstracts contained in Supplements 372 through 383 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes seven indexes: subject, personal author, corporate source, foreign technology, contract number, report number, and accession number

The relationship between pro-inflammatory cytokines, prostaglandins, and fetal hypothalamic-pituitary-adrenal axis activation in mares with infective pre-term delivery

Ascending placentitis is a significant cause of abortions, stillbirths, and perinatal loss in horses. A technique for laparoscopic-guided catheterization of the allantoic space was developed and utilized in an experimental model of streptococcal infective pre-term delivery in pony mares. Mares received either 1 x 107 CFU live S. zooepidemicus (n=3), 5.1 x 108 CFU live S. zooepidemicus (n=1), 1 x 107 heat-killed S. zooepidemicus (n=3), 1 mL sterile PBS (n=3). Sham control mares did not receive a transcervical inoculation (n=3). One mare not instrumented with an allantoic catheter received 5.1 x 108 CFU live S. zooepidemicus. Mares with spontaneous abortion had significantly increased CTUP compared to mares in which delivery was induced. There was not a significant effect of infection within the allantoic space on CTUP. Intrauterine infection increased the expression of IL-1â, IL-18, IL-15, and IFN-ã in a site-dependant manner. Spontaneous abortion also increased the expression of IL-1â, IL-18, IFN-ã, and iNOS in a site dependant manner. Soluble TNF-á was detected in only a few samples of fetal fluids. The concentrations of PGE2 and PGF2á in fetal fluids were increased within 24 h of delivery in mares with spontaneous abortion or intrauterine infection. Increased cortisol concentrations were observed in fetal fluid in some mares with infection or with histologic inflammation of the chorioallantois. None of the fetal fluids from mares induced to deliver or without inflammation of the chorioallantois had increased cortisol concentrations. This data suggests that the equine fetal adrenal gland less than 295 d may be capable of response to stimuli. Based on these findings, the following sequence of events leading from intrauterine infection to infective pre-term delivery is proposed. Following infection of the chorioallantois, IL-1â, IL-18, IL-15, and IFN-ã are upregulated in a site-dependant manner. IL-1â causes increased PGHS-2 (COX-2) expression, resulting in increased PGE2 and PGF2á production, and ultimately labor. IL-1â may also accelerate fetal hypothalamic-pituitary-adrenal axis (HPAA) activation, thereby promoting precocious in utero fetal maturation. The eventual outcome of pre-term labor, i.e., neonatal survivability, will depend on the degree of HPAA activation at the onset of labor

Aerospace medicine and biology: A cumulative index to a continuing bibliography (supplement 371)

This publication is a cumulative index to the abstracts contained in Supplements 359 through 370 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes seven indexes: subject, personal author, corporate source, foreign technology, contract number, report number, and accession number

A Clinician's Contribution to Biomedical Engineering in Experimental Echocardiography

The research of this thesis has been focused on the biomedical engineering aspects of new techniques of echocardiography. In close collaboration with the engineers of the Experimental Echocardiography Department of the Thoraxcentre, Erasmus University, Rotterdam, new methods to measure coronary blood flow and arterial wall elasticity with intravascular ultrasound (IVUS) have been developed. We have also investigated the clinical application of these measurements and have tried to improve traditional techniques based on intracoronary Doppler wires. In another field, we have developed a method to determine the radiation dose delivered in the wall of coronary arteries treated with brachytherapy. in collaboration with the Emory University, Atlanta, GA. This method utilizes 3-dimensional IVUS reconstruction combined with radiotherapy treatment planning. Finally, the tools developed for the recording of the signals of intracoronary Doppler wires have been adapted, during a stay at the Cleveland Clinic Foundation, OK for the study of left ventricular mechanics and the compliance of the large arteries. This has been achieved by simultaneous acquisition of non-invasive pressure (with tonometry) and flow (with transthoracic Doppler echocardiography) signals. The fruits of an old and close collaboration with the Institute Biomedical Technology of the Ghent University can also be found in different chapters. This work is subdivided in five major parts, and a detailed introductory chapter precedes each one