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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Noninvasive assessment of left atrial maximum dP/dt by a combination of transmitral and pulmonary venous flow

OBJECTIVES: The study assessed whether hemodynamic parameters of left atrial (LA) systolic function could be estimated noninvasively using Doppler echocardiography. BACKGROUND: Left atrial systolic function is an important aspect of cardiac function. Doppler echocardiography can measure changes in LA volume, but has not been shown to relate to hemodynamic parameters such as the maximal value of the first derivative of the pressure (LA dP/dt(max)). METHODS: Eighteen patients in sinus rhythm were studied immediately before and after open heart surgery using simultaneous LA pressure measurements and intraoperative transesophageal echocardiography. Left atrial pressure was measured with a micromanometer catheter, and LA dP/dt(max) during atrial contraction was obtained. Transmitral and pulmonary venous flow were recorded by pulsed Doppler echocardiography. Peak velocity, and mean acceleration and deceleration, and the time-velocity integral of each flow during atrial contraction was measured. The initial eight patients served as the study group to derive a multilinear regression equation to estimate LA dP/dt(max) from Doppler parameters, and the latter 10 patients served as the test group to validate the equation. A previously validated numeric model was used to confirm these results. RESULTS: In the study group, LA dP/dt(max) showed a linear relation with LA pressure before atrial contraction (r = 0.80, p < 0.005), confirming the presence of the Frank-Starling mechanism in the LA. Among transmitral flow parameters, mean acceleration showed the strongest correlation with LA dP/dt(max) (r = 0.78, p < 0.001). Among pulmonary venous flow parameters, no single parameter was sufficient to estimate LA dP/dt(max) with an r2 > 0.30. By stepwise and multiple linear regression analysis, LA dP/dt(max) was best described as follows: LA dP/dt(max) = 0.1 M-AC +/- 1.8 P-V - 4.1; r = 0.88, p < 0.0001, where M-AC is the mean acceleration of transmitral flow and P-V is the peak velocity of pulmonary venous flow during atrial contraction. This equation was tested in the latter 10 patients of the test group. Predicted and measured LA dP/dt(max) correlated well (r = 0.90, p < 0.0001). Numerical simulation verified that this relationship held across a wide range of atrial elastance, ventricular relaxation and systolic function, with LA dP/dt(max) predicted by the above equation with r = 0.94. CONCLUSIONS: A combination of transmitral and pulmonary venous flow parameters can provide a hemodynamic assessment of LA systolic function.

NASA Discipline Cardiopulmonary↗
NASA NTRS1999

The value of assessing pulmonary venous flow velocity for predicting severity of mitral regurgitation: A quantitative assessment integrating left ventricular function

Although alteration in pulmonary venous flow has been reported to relate to mitral regurgitant severity, it is also known to vary with left ventricular (LV) systolic and diastolic dysfunction. There are few data relating pulmonary venous flow to quantitative indexes of mitral regurgitation (MR). The object of this study was to assess quantitatively the accuracy of pulmonary venous flow for predicting MR severity by using transesophageal echocardiographic measurement in patients with variable LV dysfunction. This study consisted of 73 patients undergoing heart surgery with mild to severe MR. Regurgitant orifice area (ROA), regurgitant stroke volume (RSV), and regurgitant fraction (RF) were obtained by quantitative transesophageal echocardiography and proximal isovelocity surface area. Both left and right upper pulmonary venous flow velocities were recorded and their patterns classified by the ratio of systolic to diastolic velocity: normal (>/=1), blunted (<1), and systolic reversal (<0). Twenty-three percent of patients had discordant patterns between the left and right veins. When the most abnormal patterns either in the left or right vein were used for analysis, the ratio of peak systolic to diastolic flow velocity was negatively correlated with ROA (r = -0.74, P <.001), RSV (r = -0.70, P <.001), and RF (r = -0.66, P <.001) calculated by the Doppler thermodilution method; values were r = -0.70, r = -0.67, and r = -0.57, respectively (all P <.001), for indexes calculated by the proximal isovelocity surface area method. The sensitivity, specificity, and predictive values of the reversed pulmonary venous flow pattern for detecting a large ROA (>0.3 cm(2)) were 69%, 98%, and 97%, respectively. The sensitivity, specificity, and predictive values of the normal pulmonary venous flow pattern for detecting a small ROA (<0.3 cm(2)) were 60%, 96%, and 94%, respectively. However, the blunted pattern had low sensitivity (22%), specificity (61%), and predictive values (30%) for detecting ROA of greater than 0.3 cm(2) with significant overlap with the reversed and normal patterns. Among patients with the blunted pattern, the correlation between the systolic to diastolic velocity ratio was worse in those with LV dysfunction (ejection fraction <50%, r = 0.23, P >.05) than in those with normal LV function (r = -0.57, P <.05). Stepwise linear regression analysis showed that the peak systolic to diastolic velocity ratio was independently correlated with RF (P <.001) and effective stroke volume (P <.01), with a multiple correlation coefficient of 0.71 (P <.001). In conclusion, reversed pulmonary venous flow in systole is a highly specific and reliable marker of moderately severe or severe MR with an ROA greater than 0.3 cm(2), whereas the normal pattern accurately predicts mild to moderate MR. Blunted pulmonary venous flow can be seen in all grades of MR with low predictive value for severity of MR, especially in the presence of LV dysfunction. The blunted pulmonary venous flow pattern must therefore be interpreted cautiously in clinical practice as a marker for severity of MR.

Non-NASA Center↗
NASA NTRS1998

Attenuated baroreflex control of sympathetic nerve activity after cardiovascular deconditioning in rats

The effect of cardiovascular deconditioning on baroreflex control of the sympathetic nervous system was evaluated after 14 days of hindlimb unloading (HU) or the control condition. Rats were chronically instrumented with catheters and sympathetic nerve recording electrodes for measurement of mean arterial pressure (MAP) and heart rate (HR) and recording of lumbar (LSNA) or renal (RSNA) sympathetic nerve activity. Experiments were conducted 24 h after surgery, with the animals in a normal posture. Baroreflex function was assessed using a logistic function that related HR and LSNA or RSNA to MAP during infusion of phenylephrine and nitroprusside. Baroreflex influence on HR was not affected by HU. Maximum baroreflex-elicited LSNA was significantly reduced in HU rats (204 +/- 11.9 vs. 342 +/- 30.6% baseline LSNA), as was maximum reflex gain (-4.0 +/- 0.6 vs. -7.8 +/- 1.3 %LSNA/mmHg). Maximum baroreflex-elicited RSNA (259 +/- 10.8 vs. 453 +/- 28.0% baseline RSNA), minimum baroreflex-elicited RSNA (-2 +/- 2.8 vs. 13 +/- 4.5% baseline RSNA), and maximum gain (-5.8 +/- 0.5 vs. -13.6 +/- 3.1 %RSNA/mmHg) were significantly decreased in HU rats. Results demonstrate that baroreflex modulation of sympathetic nervous system activity is attenuated after cardiovascular deconditioning in rodents. Data suggest that alterations in the arterial baroreflex may contribute to orthostatic intolerance after a period of bedrest or spaceflight in humans.

NASA Discipline Cardiopulmonary↗
NASA NTRS1998

Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations

We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P < 0.05). Respiratory frequency R-R interval spectral power (used as an index of respiratory sinus arrhythmia) declined dramatically with sedation and muscle paralysis (P < 0.05), but was greater during conventional mechanical, than high frequency jet ventilation (P < 0.05). These results suggest that although phasic inputs from pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

Clinical Trial↗
NASA NTRS1997

Effects of growth hormone and low dose estrogen on bone growth and turnover in long bones of hypophysectomized rats

Pituitary hormones are recognized as critical to longitudinal growth, but their role in the radial growth of bone and in maintaining cancellous bone balance are less clear. This investigation examines the histomorphometric effects of hypophysectomy (Hx) and ovariectomy (OVX) and the subsequent replacement of growth hormone (GH) and estrogen (E), in order to determine the effects and possible interactions between these two hormones on cortical and cancellous bone growth and turnover. The replacement of estrogen is of interest since Hx results in both pituitary and gonadal hormone insufficiencies, with the latter being caused by the Hx-associated reduction in follicle stimulating hormone (FSH). All hypophysectomized animals received daily supplements of hydrocortisone (500 microg/kg) and L-thyroxine (10 microg/kg), whereas intact animals received daily saline injections. One week following surgery, hypophysectomized animals received either daily injections of low-dose 17 beta-estradiol (4.8 microg/kg s.c.), 3 X/d recombinant human GH (2 U/kg s.c.), both, or saline for a period of two weeks. Flurochromes were administered at weekly intervals to label bone matrix undergoing mineralization. Whereas Hx resulted in reductions in body weight, uterine weight, and tibial length, OVX significantly increased body weight and tibial length, while reducing uterine weight. The combination of OVX and Hx resulted in values similar to Hx alone. Treatment with GH normalized body weight and bone length, while not affecting uterine weight in hypophysectomized animals. Estrogen increased uterine weight, while not impacting longitudinal bone growth and reduced body weight. Hypophysectomy diminished tibial cortical bone area through reductions in both mineral appositional rate (MAR) and bone formation rate (BFR). While E had no effect, GH increased both MAR and BFR, though not to sham-operated (control) levels. Hypophysectomy reduced proximal tibial trabecular number and cancellous bone area, and increased trabecular separation. Both GH and E reduced cancellous osteopenia, although employing different mechanisms. GH reduced the decrease in trabecular thickness, whereas E reduced the decrease in trabecular number and the increase in trabecular separation. Hypophysectomy reduced both Tb.MAR and Tb.BFR while treatment with GH enhanced them. This investigation has shown that Hx and GH have a dramatic impact on selected static and dynamic indices of rat cortical and cancellous histomorphometry. Furthermore, the mechanisms of action of GH and E differ, and suggest that some of the skeletal changes associated with Hx are caused by deficiencies in estrogen as well as deficiencies in growth hormone.

NASA Discipline Regulatory Physiology↗
NASA NTRS1996

Protein phosphatase 2A in stretch-induced endothelial cell proliferation

We previously proposed that activation of protein kinase C is a key mechanism for control of cell growth enhanced by cyclic strain [Rosales and Sumpio (1992): Surgery 112:459-466]. Here we examined protein phosphatase 1 and 2A activity in bovine aortic endothelial cells exposed to cyclic stain. Protein phosphatase 2A activity in the cytosol was decreased by 36.1% in response to cyclic strain for 60 min, whereas the activity in the membrane did not change. Treatment with low concentration (0.1 nM) of okadaic acid enhanced proliferation of both static and stretched endothelial cells in 10% fetal bovine serum. These data suggest that protein phosphatase 2A acts as a growth suppressor and cyclic strain may enhance cellular proliferation by inhibiting protein phosphatase 2A as well as stimulating protein kinase C.

NASA Discipline Cell Biology↗
NASA NTRS1996

Skeletal response to corticosteroid deficiency and excess in growing male rats

The study was designed to investigate bone histomorphometric changes induced by corticosteroid deficiency and supplementation at different dose levels in the rat skeleton. Male rats were adrenalectomized (ADX) or sham-operated and divided into six groups. At 2 days after surgery, sham-operated control rats (CON + PLA) and one group of ADX rats (ADX + PLA) were implanted subcutaneously (s.c.) with placebo pellets. ADX rats in the remaining four groups (ADX + C25, ADX + C50, ADX + C100, and ADX + C300) were implanted sc with corticosterone pellets designed to release 25, 50, 100, or 300 mg of the hormone over a 60 day period. Each ADX rat was also implanted sc with an aldosterone pellet (2.5 mg) similarly designed to release its contents over the same time period. All rats were killed at 3 weeks after implantation of pellets. Terminal blood samples were collected for serum biochemistry and the proximal tibial metaphyses (PTM), tibial diaphyses, and first lumbar vertebrae (LV) were processed undecalcified for quantitative bone histomorphometry. A dose-dependent increase in serum corticosterone concentration was observed in ADX rats implanted with hormone pellets. In comparison to CON + PLA rats, ADX + PLA rats had lower cancellous bone volume associated with a stimulation in longitudinal bone growth, an increase in mineral apposition rate, and a trend for increased osteoclast and osteoblast surfaces in PTM. In contrast, cancellous bone of ADX + C25 rats was preserved at nearly the CON + PLA level. However, the higher doses of corticosterone increased cancellous bone mass, but decreased longitudinal bone growth and all indices of bone resorption and formation in a dose-dependent manner in PTM. Similar cancellous bone changes were observed in the LV of corticosterone-treated rats, with the exception of a lack of an hormonal effect on cancellous bone mass. In the tibial diaphysis, corticosterone inhibited periosteal bone formation in a dose-dependent manner, but did not affect cortical bone mass. The results indicate that corticosteroid deficiency induces cancellous osteopenia, whereas supplementation with a near physiologic dose of the hormone prevents this bone loss in ADX rats. Furthermore, corticosteroid excess inhibits bone growth and bone turnover in a dose-dependent manner, but does not induce cancellous osteopenia in growing male rats.

Non-NASA Center↗
NASA NTRS1995

Preservation of auditory and vestibular function after surgical removal of bilateral vestibular schwannomas in a patient with neurofibromatosis type 2

The outcome of acoustic neuroma (vestibular schwannoma) surgery continues to improve rapidly. Advances can be attributed to several fields, but the most important contributions have arisen from the identification of the genes responsible for the dominant inheritance of neurofibromatosis types 1 (NF1) and 2 (NF2) and the development of magnetic resonance imaging with gadolinium enhancement for the early anatomic confirmation of the pathognomonic, bilateral vestibular schwannomas in NF2. These advances enable early diagnosis and treatment when the tumors are small in virtually all subjects at risk for NF2. The authors suggest that advising young NF2 patients to wait until complications develop, especially hearing loss, before diagnosing and operating for bilateral eighth nerve schwannomas may not always be in the best interest of the patient. To the authors' knowledge, this is the first reported case of preservation of both auditory and vestibular function in a patient after bilateral vestibular schwannoma excision.

Case Reports↗
NASA NTRS1992

The effect of in situ freezing on rabbit patellar tendon. A histologic, biochemical, and biomechanical analysis

Cell necrosis has been well documented as one of the many changes that occur in autogenous tendon when it is used to reconstruct the anterior cruciate ligament. The purpose of this experiment was to isolate cell necrosis as a variable and study its effect on the patellar tendon. To accomplish this, both knees of 25 New Zealand White rabbits were operated on. In one knee, a 5-mm wide band of patellar tendon was subjected to two rapid freeze-thaw cycles, while the other knee underwent sham surgery. Histologic evaluation showed a zone of necrosis at 2 and 4 weeks with cellular repopulation complete at 8 weeks. patellar tendon cross-sectional area was 0.118 cm2 at 8 weeks for the frozen specimens compared to 0.102 cm2 for the sham-operated controls. This difference was significant at the P = 0.025 level. Mechanical testing at 4 and 8 weeks revealed no significant changes in tendon length, maximum load, or stiffness. The collagen content was also unchanged at both 4 and 8 weeks.

Non-NASA Center↗
NASA NTRS1992

Pulmonary hypoxic vasoconstriction: how strong? How fast?

We have developed a minimally invasive technique for studying regional blood flow in conscious sheep, bypassing the complications of open-chest surgery, flow probes and tracer infusion. We quantitate regional perfusion continuously on the basis of regional clearance of methane (methane is produced in the sheep rumen, enters the circulation and is eliminated nearly completely (greater than 95%) in the lung). Tracheal intubation with a dual-lumen catheter isolates the gas exchange of the right apical lobe (RAL; less than 15% of the lung) from that of the remainder of the lung, which serves as a control (CL). We measure RAL and CL methane elimination by entraining expirates in constant flows, sampled continuously for methane. Results obtained with this technique and from regional oxygen uptake are in excellent agreement. We have found that hypoxic vasoconstriction is far more potent and stable during eucapnic hypoxia than during hypocapnic hypoxia. The time course of the vasoconstriction suggests that many of the data in the literature may have been obtained prior to steady state.

NASA Discipline Regulatory Physiology↗
NASA NTRS1989

Effect of physical exercise prelabyrinthectomy on locomotor balance compensation in the squirrel monkey

This study examines the effectiveness of physical exercise, during a prepathology state, on locomotor balance compensation after subsequent unilateral labyrinthectomy in squirrel monkeys. An experimental group underwent 3 hr. of daily running exercise on a treadmill for 3 mo. prior to the surgery, whereas a control group was not exercised. Postoperatively, the locomotor balance function of both groups was tested for 3 mo. There was no significant difference in gait deviation counts in the acute phase of compensation. However, in the chronic compensation maintenance phase, the number of gait deviation counts was fewer in the exercise group, which showed significantly better performance stability.

Non-NASA Center↗
NASA NTRS2004

Spinoff 2004

The Innovative Partnerships Program of NASA s Exploration Systems Mission Directorate was established to guarantee the transfer of the Space Program s technical advances. Brimming with examples of technologies that have led to significant improvements in quality of life, NASA s technology transfer program has been the conduit for these achievements. The program excels by maintaining established relationships with commercial industries that include and extend beyond the aerospace sector. Spinoff 2004 highlights the diverse benefits that have grown from NASA s partnerships with U.S. companies. These products span the many disciplines of our society. Included among this year s achievements are a natural, low-calorie sugar that is safe for diabetics and contact lenses that offer the benefits of a laser-corrective eye procedure without the need for surgery. This issue also showcases some of the many research and development activities being conducted by NASA s field centers. These activities continue to fuel the Agency s missions, which collectively contribute to making the Vision for Space Exploration a reality. NASA is focusing on identifying common research interests with industry, enabling both parties to leverage their research and produce a technology that will help both the Agency and the private commercial venture. These dual-use joint ventures support the development of new exploration strategies, vehicles, and technologies, while continuing to bring space technologies back down to Earth.

Source record↗
NASA NTRS2004

A Look from the Inside

NASA's Hubble Space Telescope has given the world amazing images of the distant stars, planets, and galaxies. The cutting-edge imaging technology that enhances the Hubble images also extends its benefits to life here on Earth, from deciphering previously unreadable portions of the Dead Sea Scrolls to improving digital mammographies for advanced cancer detection. This imaging technology is now helping physicians to perform micro-invasive arthroscopic surgery, which is the visual examination of an interior joint such as the knee. In 1997, NASA's Glenn Research Center signed a Space Act Agreement with Micro Medical Devices, Inc. (MMD), a medical device engineering company that licenses miniature surgical devices. At that time, MMD was in the process of developing a new micro-endoscope. This tool enables surgeons to view what is happening inside the body on a screen, eliminating the need for a more invasive diagnostic procedure. The images from the micro-endoscope needed to be extremely clear, a challenge with the tool s small size. The images also needed to be viewed in real time to allow surgeons to see what was happening in the body at that very moment. MMD established Clear Image Technology, LLC, of Elyria, Ohio, to commercialize the miniature endoscope. Clear Image Technology then partnered with Arthrotek, Inc., a sports medicine subsidiary of Biomet, Inc., to introduce the tool to the commercial market as the InnerVue[TM] Diagnostic Scope System. The InnerVue system is designed for use in a diagnostic environment, such as an office or outpatient service, to evaluate conditions within a joint. While the InnerVue scope is primarily being applied to the knee and shoulder, other small joints such as the wrist, elbow, and ankle are being investigated. A physician can use the system alone or in conjunction with magnetic resonance imaging (MRI) to determine the next treatment step for each patient. The procedure can be more accurate than MRI, particularly with diagnosing cartilage and articular surface damage and assessing arthritis severity.

Source record↗
NASA NTRS2004

Airline chair-rest deconditioning: induction of immobilisation thromboemboli?

Air passenger miles will likely double by year 2020. The altered and restrictive environment in an airliner cabin can influence haematological homeostasis in passengers and crew. Flight-related deep venous 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 accommodations (via sitting immobilisation); travellers' 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 hospitalised patients) facilitate thrombophlebitis and formation of DVT that may be exacerbated by the immobilisation of prolonged air travel.In the healthy flying population, immobilisation factors associated with prolonged (>5 hours) C-RD such as total body dehydration, hypovolaemia and increased blood viscosity, and reduced venous 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 DVT, but factors such as a history of vascular thromboemboli, venous insufficiency, chronic heart failure, obesity, immobile standing position, more than three 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 DVT in healthy people.

Review, Tutorial↗
NASA NTRS2004

Strategies for Small Volume Resuscitation: Hyperosmotic-Hyperoncotic Solutions, Hemoglobin Based Oxygen Carriers and Closed-Loop Resuscitation

Introduction: Logistic constraints on combat casualty care preclude traditional resuscitation strategies which can require volumes and weights 3 fold or greater than hemorrhaged volume. We present a review of quantitative analyses of clinical and animal data on small volume strategies using 1) hypertonic-hyperosmotic solutions (HHS); 2) hemoglobin based oxygen carriers (HBOCs) and 3) closed-loop infusion regimens.Methods and Results: Literature searches and recent queries to industry and academic researchers have allowed us to evaluate the record of 81 human HHS studies (12 trauma trials), 19 human HBOCs studies (3trauma trials) and two clinical studies of closed-loop resuscitation.There are several hundreds animal studies and at least 82 clinical trials and reports evaluating small volume7.2%-7.5% hypertonic saline (HS) most often combined with colloids, e.g., dextran (HSD) or hetastarch(HSS). HSD and HSS data has been published for 1,108 and 392 patients, respectively. Human studies have documented volume sparing and hemodynamic improvements. Meta-analyses suggest improved survival for hypotensive trauma patients treated with HSD with significant reductions in mortality found for patients with blood pressure < 70 mmHg, head trauma, and penetrating injury requiring surgery. HSD and HSS have received regulatory approval in 14 and 3 countries, respectively, with 81,000+ units sold. The primary reported use was head injury and trauma resuscitation. Complications and reported adverse events are surprisingly rare and not significantly different from other solutions.HBOCs are potent volume expanders in addition to oxygen carriers with volume expansion greater than standard colloids. Several investigators have evaluated small volume hyperoncotic HBOCs or HS-HBOC formulations for hypotensive and normotensive resuscitation in animals. A consistent finding in resuscitation with HBOCs is depressed cardiac output. There is some evidence that HBOCs more efficiently unload oxygen from plasma hemoglobin as well as facilitate RBC unloading. We analyzed one volunteer study, 15 intraoperative trials, and 3 trauma studies using HBOCs. Perioperative studies generally suggest ability to deliver oxygen, but one trauma trial using HBOCs (HemAssist) for treatment of trauma resulted in a dramatic increase in mortality, while an intraoperative trauma study using Polyheme demonstrated reductions in blood use and lower mortality compared to historic controls of patients refusing blood. Transfusion reductions with HBOC use have been modest. Two HBOCs (Hemopure and Polyheme) are now in new or planned large-scale multicenter prehospital trials of trauma treatment. A new implementation of small volume resuscitation is closed-loop resuscitation (CLR), which employs microprocessors to titrate just enough fluid to reach a physiologic target . Animal studies suggest less risk of rebleeding in uncontrolled hemorrhage and a reduction in fluid needs with CLR. The first clinical application of CLR was treatment of burn shock and the US Army. Conclusions: Independently sponsored civilian trauma trials and clinical evaluations in operational combat conditions of different small volume strategies are warranted.

Kramer, George C.↗
NASA NTRS2004

Photo-Curing: UV Radiation curing of polymers

The Polymers Branch of the Materials Division is dedicated to the development of high-performance for a variety of applications. Areas of significant interest include high- temperature polymers, low density, and high strength insulating materials, conductive polymers, and high density polymer electrolytes. This summer our group is working diligently on a photo-curing project. There is interest in the medical community feel the need for a new and improved balloon that will be used for angioplasty (a form of heart surgery). This product should maintain flexibility but add many other properties. Like possibly further processability and resistance to infection. Our group intends on coming up with this product by using photo-enolization (or simply, photo-curing) by Diels-Alder trapping. The main objective was to synthesize a series of new polymers by Diels-Alder cycloaddition of photoenols with more elastomeric properties. Our group was responsible for performing the proper photo-curing techniques of the polymers with diacrylates and bismaleimides, synthesizing novel monomers, and evaluating experimental results. We attempted to use a diacrylate to synthesize the polymer because of previous research done within the Polymers Branch here at NASA. Most acrylates are commercially available, have more elastometric properties than a typical rigid aromatic structure has and they contain ethylene oxides in the middle of their structure that create extensive flexibility. The problem we encountered with the acrylates is that they photo chemically and thermally self polymerize and create diradicals at low temperatures; these constraints caused a lot of unnecessary side reactions. We want to promote solely, diketone polymerization because this type of polymerization has the ability to cause very elastic polymers. We chose to direct our attention towards the usage of maleimides because they are known for eliminating these unnecessary side reactions.

Inman, Christina A.↗
NASA NTRS2001

Epicenter location by analysis for interictal spikes

The MEG recording is a quick and painless process that requires no surgery. This approach has the potential to save time, reduce patient discomfort, and eliminates a painful and potentially dangerous surgical step in the treatment procedure.

epilepsy MEG interictal spikes artificial neural n↗
NASA NTRS1997

Robot Assisted Microsurgery Development at JPL

A team of engineers at JPL, working in collaboration with MicroDexterity Systems, Inc., and Dr. Steve Charles, recently developed a telerobotic workstation to assist microsurgeons perform surgery.

Microsurgery JPL telerobotic MicroDexterity System↗