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At least 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

In Vivo Model to Test Implanted Biosensors for Blood pH

Biosensors for monitoring physiologic data continuously through telemetry are available for heart rate, respiration, and temperature but not for blood pH or ions affected by hydrogen ion concentration. A telemetric biosensor for monitoring blood pH on-line could be used to identify and manage problems in fluid and electrolyte metabolism, cardiac and respiratory function during space flight and the acid-base status of patients without the need for venipuncture in patients on Earth. Critical to the development of biosensors is a method for evaluating their performance after implantation. Mature rats, prepared with jugular, cannulas for repeated blood samples, were exposed to a gas mixture containing high levels of carbon dioxide (7%) in a closed environment to induce mild respiratory acidosis. Serial blood gas and pH measurements in venous blood were compared with electrical responses from sensors implanted in the subcutaneous tissue. Animals became slightly tachypneic after exposure to excess CO2, but remained alert and active. After 5 minutes, basal blood pH decreased from 7.404 +/- 0.013 to 7.289 +/- 0.010 (p less than 0.001)and PC02 increased from 45 +/- 6 to 65 +/- 4 mm. Hg (p les than 0.001). Thereafter pH and blood gas parameters remained stable. Implanted sensors showed a decrease in millivolts (mV) which paralleled the change in pH and averaged 5-6 mV per 0.1 unit pH. Implanted sensors remained sensitive to modest changes in tissue pH for one week. A system for inducing acidosis in rats was developed to test the in vivo performance of pH biosensors. The system provides a method which is sensitive, rapid and reproducible in the same and different animals with full recovery, for testing the performance of sensors implanted in subcutaneous tissues.

Arnaud, Sara B.↗
NASA NTRS2002

Airline Chair-rest Deconditioning: Induction of Immobilization Thromboemboli?

Air passenger miles will likely double by year 2020. The altered and restrictive environment in an airliner cabin can influence hematological homeostasis in passengers and crew. Flight-related deep various thromboemboli (DVT) have been associated with at least 577 deaths on 42 of 120 airlines from 1977 to 1984 (25 deaths/million departures), whereas many such cases go unreported. However, there are four major factors that could influence formation of possible flight-induced DVT: sleeping accomodations (via sitting immobilization), travelers' medical history (via tissue injury), cabin environmental factors (via lower partial pressure of oxygen and lower relative humidity), and the more encompassing chair-rest deconditioning (C-RD) syndrome. There is ample evidence that recent injury and surgery (especially in deconditioned hospitalized patients) facilitate thrombophlebitis and formation of DVT that may be exacerbated by the immobilization of prolonged air travel. In the healthy flying population immobilization factors associated with prolonged (> 5 hr) C-RID such as total body dehydration, hypovolemia and increased blood viscosity, and reduced various blood flow (pooling) in the legs may facilitate formation of DVT. However, data from at least four case-controlled epidemiological studies did not confirm a direct causative relationship between air travel and DART, but factors such as history of vascular thromboemboli, various insufficiency, chronic heart failure, obesity, immobile standing position, more than 3 pregnancies, infectious disease, long-distance travel, muscular trauma and violent physical effort were significantly more frequent in DVT patients than in controls. Thus, there is no clear, direct evidence yet that prolonged sitting in airliner seats, or prolonged experimental chair-rest- or bed- rest-deconditioning treatments cause deep various thromboemboli in healthy people.

Greenleaf, J. E.↗
NASA NTRS2002

A New Optical Scheme for a Polarimetric-Based Glucose Sensor

We describe a new optical scheme to perform polarimetric measurements to detect glucose concentration in the aqueous humor of a model eye. The ultimate aim is to apply this technique in designing a new instrument for measuring glucose levels in diabetic patients routinely, frequently, and non-invasively. The scheme exploits the Brewsterreflection of circularly polarized light off of the lens of the eye. Theoretically, this backreflected linearly polarized light on its way to the detector is expected to rotate its state of polarization due to the presence of glucose molecules in the aqueous humor of patients. An experimental laboratory setup based on this scheme was designed and tested by measuring a range of known concentration of glucose solutions dissolved in water.

Ansari, Rafat R.↗
NASA NTRS1994

A Third Arm for the Surgeon

In laparoscopic surgery, tiny incisions are made in the patient's body and a laparoscope (an optical tube with a camera at the end) is inserted. The camera's image is projected onto two video screens, whose views guide the surgeon through the procedure. AESOP, a medical robot developed by Computer Motion, Inc. with NASA assistance, eliminates the need for a human assistant to operate the camera. The surgeon uses a foot pedal control to move the device, allowing him to use both hands during the surgery. Miscommunication is avoided; AESOP's movement is smooth and steady, and the memory vision is invaluable. Operations can be completed more quickly, and the patient spends less time under anesthesia. AESOP has been approved by the FDA.

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NASA NTRS2002

A New Cure for Medical Errors

In May 2000, senior officials of the U.S. Department of Veterans Affairs (VA) and NASA signed an agreement that would commit the two agencies to create the Patient Safety Reporting System (PSRS) to report: events or situations that could have resulted in accident, injury, or illness, but did not, either by chance or through timely intervention (close-calls); unexpected serious occurrences that involved a patient or employee's death, physical injury, or psychological injury; lessens learned; and safety ideas. The VA provided NASA with funding for the initial development of the new system, which automatically removes all personal names, facility names and locations, and other potentially identifying information before entering reports into its database. Designed to complement the VA's current internal reporting systems, the PSRS is modeled after NASA's Aviation Safety Reporting System, which was established in 1975 under a Memorandum of Agreement between the Federal Aviation Administration and NASA and began operation in 1976.

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NASA NTRS1992

Medical Training Aid

Dr. Steven S. Saliterman developed his Dynacath Critical Care Patient Simulator as a training system for medical personnel involved in critical care management and hemodynamic monitoring. The system incorporates NASA simulation technology and allows hospitals and medical manufacturers to conduct training away from the patient's bedside. Dr. Saliterman was formerly employed by Ames Research Center and Johnson Space Center.

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NASA NTRS1991

Balance Function Disorders

Researchers at the Balance Function Laboratory and Clinic at the Minneapolis (MN) Neuroscience Institute on the Abbot Northwestern Hospital Campus are using a rotational chair (technically a "sinusoidal harmonic acceleration system") originally developed by NASA to investigate vestibular (inner ear) function in weightlessness to diagnose and treat patients with balance function disorders. Manufactured by ICS Medical Corporation, Schaumberg, IL, the chair system turns a patient and monitors his or her responses to rotational stimulation.

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NASA NTRS1990

Laser Angioplasty

The principal method of dealing with coronary artery blockage is bypass surgery. A non-surgical alternative available to some patients is balloon angioplasty. For several years, medical researchers have been exploring another alternative that would help a wider circle of patients than the balloon treatment and entail less risk than bypass surgery. A research group is on the verge of an exciting development: laser angioplasty with a 'cool' type of laser, called an excimer laser, that does not damage blood vessel walls and offers non-surgical cleansing of clogged arteries with extraordinary precision. The system is the Dymer 200+ Excimer Laser Angioplasty System, developed by Advanced Intraventional Systems. Used in human clinical tests since 1987, the system is the first fully integrated 'cool' laser capable of generating the requisite laser energy and delivering the energy to target arteries. Thirteen research hospitals in the U.S. have purchased Dymer 200+ systems and used them in clinical trials in 121 peripheral and 555 coronary artery cases. The success rate in opening blocked coronary arteries is 85 percent, with fewer complications than in balloon angioplasty. Food and Drug Administration approval for the system is hoped for in the latter part of 1990. * Advanced Intraventional Systems became Spectranetics in 1994 and discontinued the product.

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NASA NTRS1990

Biofeedback for Better Vision

Biofeedtrac, Inc.'s Accommotrac Vision Trainer, invented by Dr. Joseph Trachtman, is based on vision research performed by Ames Research Center and a special optometer developed for the Ames program by Stanford Research Institute. In the United States, about 150 million people are myopes (nearsighted), who tend to overfocus when they look at distant objects causing blurry distant vision, or hyperopes (farsighted), whose vision blurs when they look at close objects because they tend to underfocus. The Accommotrac system is an optical/electronic system used by a doctor as an aid in teaching a patient how to contract and relax the ciliary body, the focusing muscle. The key is biofeedback, wherein the patient learns to control a bodily process or function he is not normally aware of. Trachtman claims a 90 percent success rate for correcting, improving or stopping focusing problems. The Vision Trainer has also proved effective in treating other eye problems such as eye oscillation, cross eyes, and lazy eye and in professional sports to improve athletes' peripheral vision and reaction time.

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NASA NTRS1986

Scalp Cooler

Composite Consulation Concepts, Inc.'s Chemo-cooler, a scalp cooling system based on NASA space suit technology, prevents hair loss in patients undergoing chemotherapy. A head covering is placed over plastic tubing through which cold water is circulated from a cylinder. A controller monitors time and temperature. With chemo-cooler, 63% of patients lost almost no hair; 9% suffered only moderate hair loss. The technique was commercialized by an ex-NASA employee.

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NASA NTRS1984

Ingestible Toothpaste

Developed by Dr. Ira L. Shannon, dental consultant to Johnson Space Center associates with Oral Disease Research Lab of Virginia Hospital in Houston, TX. Toothpaste is foamless and can be swallowed after use, making it practical for zero-gravity environment of space. Also has applications with certain patients who are bedridden, wheelchair confined or patients with oral facial paralysis whose ability to expectorate is limited. Also useful as a first toothpaste for children. This product is no longer commercially available.

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NASA NTRS1981

Space Derived Health Aids (Cardiac Pacemaker)

St. Jude Medical's Cardiac Rhythm Management Division's (formerly known as Pacesetter Systems, Inc.) pacer is a rechargeable cardiac pacemaker that eliminates the recurring need for surgery to implant a new battery. The Programalith is an advanced cardiac pacing system which permits a physician to reprogram a patient's implanted pacemaker without surgery. System consists of a pacemaker, together with a physician's console containing the programmer and a data printer. Signals are transmitted by wireless telemetry. Two-way communications, originating from spacecraft electrical power systems technology, allows physician to interrogate the pacemaker as to the status of the heart, then to fine tune the device to best suit the patient's needs.

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NASA NTRS2003

Striding Towards Better Physical Therapy

This paper presents a discussion on a new rehabilitative device that promises to improve physical therapy for patients working to regain the ability to walk after facing traumatic injuries or a degenerative illness. Produced by Enduro Medical Technology, of East Hartford, Connecticut, the Secure Ambulation Module (S.A.M.) creates a stable and secure environment for patients as they stand during ambulation therapy.

Source record↗
NASA NTRS2003

Pulsed Phase Lock Loop Device for Monitoring Intracranial Pressure During Space Flight

We have developed an ultrasonic device to monitor ICP waveforms non-invasively from cranial diameter oscillations using a NASA-developed pulsed phase lock loop (PPLL) technique. The purpose of this study was to attempt to validate the PPLL device for reliable recordings of ICP waveforms and analysis of ICP dynamics in vivo. METHODS: PPLL outputs were recorded in patients during invasive ICP monitoring at UCSD Medical Center (n=10). RESULTS: An averaged linear regression coefficient between ICP and PPLL waveform data during one cardiac cycle in all patients is 0.88 +/- 0.02 (mean +/- SE). Coherence function analysis indicated that ICP and PPLL waveforms have high correlation in the lst, 2nd, and 3rd harmonic waves associated with a cardiac cycle. CONCLUSIONS: PPLL outputs represent ICP waveforms in both frequency and time domains. PPLL technology enables in vivo evaluation of ICP dynamics non-invasively, and can acquire continuous ICP waveforms during spaceflight because of compactness and non-invasive nature.

Ueno, Toshiaki↗
NASA NTRS2004

New optical scheme for a polarimetric-based glucose sensor

A new optical scheme to detect glucose concentration in the aqueous humor of the eye is presented. The ultimate aim is to apply this technique in designing a new instrument for, routinely and frequently, noninvasively monitoring blood glucose levels in diabetic patients without contact (no index matching) between the eye and the instrument. The optical scheme exploits the Brewster reflection of circularly polarized light off of the lens of the eye. Theoretically, this reflected linearly polarized light on its way to the detector is expected to rotate its state of polarization, owing to the presence of glucose molecules in the aqueous humor of a patient's eye. An experimental laboratory setup based on this scheme was designed and tested by measuring a range of known concentrations of glucose solutions dissolved in water. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

Evaluation Studies↗
NASA NTRS2003

Nitric oxide in microgravity-induced orthostatic intolerance: relevance to spinal cord injury

Prolonged exposure to microgravity results in cardiovascular deconditioning which is marked by orthostatic intolerance in the returning astronauts and recovering bed-ridden patients. Recent studies conducted in our laboratories at University of California, Irvine have revealed marked elevation of nitric oxide (NO) production in the kidney, heart, brain, and systemic arteries coupled with significant reduction of NO production in the cerebral arteries of microgravity-adapted animals. We have further demonstrated that the observed alteration of NO metabolism is primarily responsible for the associated cardiovascular deconditioning. Recovery from acute spinal cord injury (SCI) is frequently complicated by orthostatic intolerance that is due to the combined effects of the disruption of efferent sympathetic pathway and cardiovascular deconditioning occasioned by prolonged confinement to bed. In this presentation, I will review the nature of altered NO metabolism and its role in the pathogenesis of microgravity-induced cardiovascular deconditioning. The possible relevance of the new findings to orthostatic intolerance in patients with acute SCI and its potential therapeutic implications will be discussed.

Review↗
NASA NTRS2003

Lysine hydroxylation of collagen in a fibroblast cell culture system

The lysine (Lys) hydroxylation pattern of type I collagen produced by human fibroblasts in culture was analyzed and compared. Fibroblasts were cultured from normal human skin (NSF), keloid (KDF), fetal skin (FDF), and skin tissues of Ehlers-Danlos syndrome type VIA and VIB patients (EDS-VIA and -VIB). The type I collagen alpha chains with or without non-helical telopeptides were purified from the insoluble matrix and analyzed. In comparison with NSFs, KDF and FDF showed significantly higher Lys hydroxylation, particularly in the telopeptide domains of both alpha chains. Both EDS-VIA and -VIB showed markedly lower Lys hydroxylation in the helical domains of both alpha chains whereas that in the telopeptides was comparable with those of NSFs. A similar profile was observed in the tissue sample of the EDS-VIB patient. These results demonstrate that the Lys hydroxylation pattern is domain-specific within the collagen molecule and that this method is useful to characterize the cell phenotypes in normal/pathological connective tissues.

NASA Discipline Cell Biology↗
NASA NTRS2003

Real-time three-dimensional color doppler evaluation of the flow convergence zone for quantification of mitral regurgitation: Validation experimental animal study and initial clinical experience

BACKGROUND: Pitfalls of the flow convergence (FC) method, including 2-dimensional imaging of the 3-dimensional (3D) geometry of the FC surface, can lead to erroneous quantification of mitral regurgitation (MR). This limitation may be mitigated by the use of real-time 3D color Doppler echocardiography (CE). Our objective was to validate a real-time 3D navigation method for MR quantification. METHODS: In 12 sheep with surgically induced chronic MR, 37 different hemodynamic conditions were studied with real-time 3DCE. Using real-time 3D navigation, the radius of the largest hemispherical FC zone was located and measured. MR volume was quantified according to the FC method after observing the shape of FC in 3D space. Aortic and mitral electromagnetic flow probes and meters were balanced against each other to determine reference MR volume. As an initial clinical application study, 22 patients with chronic MR were also studied with this real-time 3DCE-FC method. Left ventricular (LV) outflow tract automated cardiac flow measurement (Toshiba Corp, Tokyo, Japan) and real-time 3D LV stroke volume were used to quantify the reference MR volume (MR volume = 3DLV stroke volume - automated cardiac flow measurement). RESULTS: In the sheep model, a good correlation and agreement was seen between MR volume by real-time 3DCE and electromagnetic (y = 0.77x + 1.48, r = 0.87, P <.001, delta = -0.91 +/- 2.65 mL). In patients, real-time 3DCE-derived MR volume also showed a good correlation and agreement with the reference method (y = 0.89x - 0.38, r = 0.93, P <.001, delta = -4.8 +/- 7.6 mL). CONCLUSIONS: real-time 3DCE can capture the entire FC image, permitting geometrical recognition of the FC zone geometry and reliable MR quantification.

Validation Studies↗