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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Chronic recording of regenerating VIIIth nerve axons with a sieve electrode

A micromachined silicon substrate sieve electrode was implanted within transected toadfish (Opsanus tau) otolith nerves. High fidelity, single unit neural activity was recorded from seven alert and unrestrained fish 30 to 60 days after implantation. Fibrous coatings of genetically engineered bioactive protein polymers and nerve guide tubes increased the number of axons regenerating through the electrode pores when compared with controls. Sieve electrodes have potential as permanent interfaces to the nervous system and to bridge missing connections between severed or damaged nerves and muscles. Recorded impulses might also be amplified and used to control prosthetic devices.

NASA Discipline Neuroscience↗
NASA NTRS1990

The vestibular nerve of the chinchilla. III. Peripheral innervation patterns in the utricular macula

1. Nerve fibers supplying the utricular macula of the chinchilla were labeled by extracellular injection of horseradish peroxidase into the vestibular nerve. The peripheral terminations of individual fibers were reconstructed and related to the regions of the end organ they innervated and to the sizes of their parent axons. 2. The macula is divided into medial and lateral parts by the striola, a narrow zone that runs for almost the entire length of the sensory epithelium. The striola can be distinguished from the extrastriolar regions to either side of it by the wider spacing of its hair cells. Calyx endings in the striola have especially thick walls, and, unlike similar endings in the extrastriola, many of them innervate more than one hair cell. The striola occupies 10% of the sensory epithelium; the lateral extrastriola, 50%; and the medial extrastriola, 40%. 3. The utricular nerve penetrates the bony labyrinth anterior to the end organ. Axons reaching the anterior part of the sensory epithelium run directly through the connective tissue stroma. Those supplying more posterior regions first enter a fiber layer located at the bottom of the stroma. Approximately one-third of the axons bifurcate below the epithelium, usually within 5-20 microns of the basement membrane. Bifurcations are more common in fibers destined for the extrastriola than for the striola. 4. Both calyx and bouton endings were labeled. Calyces can be simple or complex. Simple calyces innervate individual hair cells, whereas complex calyces supply 2-4 adjacent hair cells. Complex endings are more heavily concentrated in the striola than in the extrastriola. Simple calyces and boutons are found in all parts of the epithelium. Calyces emerge from the parent axon or one of its thick branches. Boutons, whether en passant or terminal, are located on thin collaterals. 5. Fibers can be classified into calyx, bouton, or dimorphic categories. The first type only has calyx endings; the second, only bouton endings; and the third, both kinds of endings. Calyx units make up 6% of the labeled fibers, bouton units less than 2%, and dimorphic units greater than 92%. The three fiber types differ in the macular zones they supply and in the diameters of their parent axons. Calyx units were restricted to the striola. The few bouton units were found in the extrastriola.(ABSTRACT TRUNCATED AT 400 WORDS).

NASA Discipline Neuroscience↗
DOE OSTI2019

Comparative efficacy of valnoctamide and sec ‐butylpropylacetamide ( SPD ) in terminating nerve agent–induced seizures in pediatric rats

Summary Objectives Children and adults are likely to be among the casualties in a civilian nerve agent exposure. This study evaluated the efficacy of valnoctamide (racemic‐VCD), sec ‐butylpropylacetamide (racemic‐SPD), and phenobarbital for stopping nerve agent seizures in both immature and adult rats. Methods Female and male postnatal day ( PND ) 21, 28, and 70 (adult) rats, previously implanted with electroencephalography (EEG) electrodes were exposed to seizure‐inducing doses of the nerve agents sarin or VX and EEG was recorded continuously. Five minutes after seizure onset, animals were treated with SPD , VCD, or phenobarbital. The up‐down method was used over successive animals to determine the anticonvulsant median effective dose (ED 50 ) of the drugs. Results SPD‐ED 50 values in the VX model were the following: PND 21, 53 mg/kg (male) and 48 mg/kg (female); PND 28, 108 mg/kg (male) and 43 mg/kg (female); and PND 70, 101 mg/kg (male) and 40 mg/kg (female). SPD ‐ ED 50 values in the sarin model were the following: PND 21, 44 mg/kg (male) and 28 mg/kg (female); PND 28, 79 mg/kg (male) and 34 mg/kg (female); and PND 70, 53 mg/kg (male) and 53 mg/kg (female). VCD ‐ ED 50 values in the VX model were the following: PND 21, 34 mg/kg (male) and 43 mg/kg (female); PND 28, 165 mg/kg (male) and 59 mg/kg (female); and PND 70, 87 mg/kg (male) and 91 mg/kg (female). VCD ‐ ED 50 values in the sarin model were the following: PND 21, 45 mg/kg (male), 48 mg/kg (female); PND 28, 152 mg/kg (male) 79 mg/kg (female); and PND 70, 97 mg/kg (male) 79 mg/kg (female). Phenobarbital‐ ED 50 values in the VX model were the following: PND 21, 43 mg/kg (male) and 18 mg/kg (female); PND 28, 48 mg/kg (male) and 97 mg/kg (female). Phenobarbital‐ ED 50 values in the sarin model were the following: PND 21, 32 mg/kg (male) and 32 mg/kg (female); PND 28, 58 mg/kg (male) and 97 mg/kg (female); and PND 70, 65 mg/kg (female). Significance SPD and VCD demonstrated anticonvulsant activity in both immature and adult rats in the sarin‐ and VX ‐induced status epilepticus models. Phenobarbital was effective in immature rats, whereas in adult rats, higher doses were required that were accompanied by toxicity. Overall, significantly less drug was required to stop seizures in PND 21 animals than in the older animals, and overall, males required higher amounts of drug than females.

Haines, Kari M.↗
DOE OSTI2020

SEDONA: SpEctroscopic Detection of Nerve Agents

Los Alamos National Laboratory developed the only portable screener to accurately detect the chemical nerve agents, providing results in seconds. Current airport detection system cannot scan for the threat of organophosphorus nerve agents and insecticides. Small quantities of these toxic chemicals can very quickly cause widespread exposure and severe symptoms. SEDONA screens through an unopened bottle using the principles of nuclear magnetic resonance spectroscopy. The system could be deployed and operated with minimal training. SEDONA dramatically reduces the likelihood of a successful nerve agent attack at airports, government buildings, embassies, sporting events, concerts, and political rallies.

47 OTHER INSTRUMENTATION↗
NASA NTRS1984

Changes in the cholinergic system of rat sciatic nerve and skeletal muscle following suspension induced disuse

Muscle disused induced changes in the cholinergic system of sciatic nerve, slow twitch soleus (SOL) and fast twitch extensor digitorum longus (EDL) muscle were studied in rats. Rats with hindlimbs suspended for 2 to 3 weeks showed marked elevation in the activity of choline acetyltransferase (ChAT) in sciatic nerve (38%), in SOL (108%) and in EDL (67%). Acetylcholinesterase (AChE) activity in SOL increased by 163% without changing the molecular forms pattern of 4S, 10S, 12S, and 16S. No significant changes in activity and molecular forms pattern of AChE were seen in EDL or in AChE activity of sciatic nerve. Nicotinic receptor binding of 3H-acetylcholine was increased in both muscles. When measured after 3 weeks of hindlimb suspension the normal distribution of type 1 fibers in SOL was reduced and a corresponding increase in type IIa and IIb fibers is seen. In EDL no significant change in fiber proportion is observed. Muscle activity, such as loadbearing, appears to have a greater controlling influence on the characteristics of the slow twitch SOL muscle than upon the fast twitch EDL muscle.

Gupta, R. C.↗
NASA NTRS1988

Identifying motor and sensory myelinated axons in rabbit peripheral nerves by histochemical staining for carbonic anhydrase and cholinesterase activities

Carbonic anhydrase (CA) and cholinesterase (CE) histochemical staining of rabbit spinal nerve roots and dorsal root ganglia demonstrated that among the reactive myeliated axons, with minor exceptions, sensory axons were CA positive and CE negative whereas motor axons were CA negative and CE positive. The high specificity was achieved by adjusting reaction conditions to stain subpopulations of myelinated axons selectively while leaving 50 percent or so unstained. Fixation with glutaraldehyde appeared necessary for achieving selectivity. Following sciatic nerve transection, the reciprocal staining pattern persisted in damaged axons and their regenerating processes which formed neuromas within the proximal nerve stump. Within the neuromas, CA-stained sensory processes were elaborated earlier and in greater numbers than CE-stained regenerating motor processes. The present results indicate that histochemical axon typing can be exploited to reveal heterogeneous responses of motor and sensory axons to injury.

Riley, Danny A.↗
NASA NTRS1988

A precision mechanical nerve stimulator

An electromechanical device, used to apply and monitor stimulating pulses to a mammalian motor nerve, has been successfully developed at NASA Langley Research Center. Two existing force transducers, a flight skin friction balance and a miniature skin friction balance which were designed for making aerodynamic drag measurements, were modified and incorporated to form this precision instrument. The nerve stimulator is a type one servomechanism capable of applying and monitoring stimulating pulses of 0 to 10 grams with a precision of better than +/- 0.05 grams. Additionally, the device can be independently used to apply stimulating pulses by displacing the nerve from 0 to 0.25 mm with a precision of better than +/- 0.001 mm while measuring the level of the load applied.

Tcheng, Ping↗
NASA NTRS1994

Peripheral innervation patterns of vestibular nerve afferents in the bullfrog utriculus

Vestibular nerve afferents innervating the bullfrog utriculus differ in their response dynamics and sensitivity to natural stimulation. They also supply hair cells that differ markedly in hair bundle morphology. To examine the peripheral innervation patterns of individual utricular afferents more closely, afferent fibers were labeled by the extracellular injection of horseradish peroxidase (HRP) into the vestibular nerve after sectioning the vestibular nerve medial to Scarpa's ganglion to allow the degeneration of sympathetic and efferent fibers. The peripheral arborizations of individual afferents were then correlated with the diameters of their parent axons, the regions of the macula they innervate, and the number and type of hair cells they supply. The utriculus is divided by the striola, a narrow zone of distinctive morphology, into media and lateral parts. Utiricular afferents were classified as striolar or extrastriolar according to the epithelial entrance of their parent axons and the location of their terminal fields. In general, striolar afferents had thicker parent axons, fewer subepithelial bifurcations, larger terminal fields, and more synaptic endings than afferents in extrstriolar regions. Afferents in a juxtastriolar zone, immediately adjacent to the medial striola, had innervation patterns transitional between those in the striola and more peripheral parts of the medial extrastriola. moast afferents innervated only a single macular zone. The terminal fields of striolar afferents, with the notable exception of a few afferents with thin parent axons, were generally confined to one side of the striola. Hair cells in the bullfrog utriculus have perviously been classified into four types based on hair bundle morphology. Afferents in the extrastriolar and juxtastriolar zones largely or exclusively innervated Type B hair cells, the predominant hair cell type in the utricular macula. Striolar afferents supplied a mixture of four hair cell types, but largely contacted Type B and Type C hair cells, particularly on the outer rows of the medial striola. Afferents supplying more central striolar regions innervated fewer Type B and larger numbers of Type E and Type F hair cells. Striolar afferents with thin parent axons largely supplied Type E hair cells with bulbed kniocilia in the innermost striolar rows.

Baird, Richard A.↗
NASA NTRS1994

Secretion of Growth Hormone in Response to Muscle Sensory Nerve Stimulation

Growth hormone (GH) secretion is stimulated by aerobic and resistive exercise and inhibited by exposure to actual or simulated (bedrest, hindlimb suspension) microgravity. Moreover, hypothalamic growth hormone-releasing factor (GRF) and preproGRF mRNA are markedly decreased in spaceflight rats. These observations suggest that reduced sensory input from inactive muscles may contribute to the reduced secretion of GH seen in "0 G". Thus, the aim of this study was to determine the effect of muscle sensory nerve stimulation on secretion of GH. Fed male Wistar rats (304 +/- 23 g) were anesthetized (pentobarbital) and the right peroneal (Pe), tibial (T), and sural (S) nerves were cut. Electrical stimulation of the distal (D) or proximal (P) ends of the nerves was implemented for 15 min. to mimic the EMG activity patterns of ankle extensor muscles of a rat walking 1.5 mph. The rats were bled by cardiac puncture and their anterior pituitaries collected. Pituitary and plasma bioactive (BGH) and immunoactive (IGH) GH were measured by bioassay and RIA.

Grindeland, Richard E.↗
NASA NTRS2002

Attenuated sympathetic nerve responses after 24 hours of bed rest

Bed rest reduces orthostatic tolerance. Despite decades of study, the cause of this phenomenon remains unclear. In this report we examined hemodynamic and sympathetic nerve responses to graded lower body negative pressure (LBNP) before and after 24 h of bed rest. LBNP allows for baroreceptor disengagement in a graded fashion. We measured heart rate (HR), cardiac output (HR x stroke volume obtained by echo Doppler), and muscle sympathetic nerve activity (MSNA) during a progressive and graded LBNP paradigm. Negative pressure was increased by 10 mmHg every 3 min until presyncope or completion of -60 mmHg. After bed rest, LBNP tolerance was reduced in 11 of 13 subjects (P <.023), HR was greater (P <.002), cardiac output was unchanged, and the ability to augment MSNA at high levels of LBNP was reduced (rate of rise for 30- to 60-mmHg LBNP before bed rest 0.073 bursts x min(-1) x mmHg(-1); after bed rest 0.035 bursts x min(-1) x mmHg(-1); P < 0.016). These findings suggest that 24 h of bed rest reduces sympathetic nerve responses to LBNP.

NASA Discipline Neuroscience↗
NASA NTRS2001

Carotid baroreflex regulation of sympathetic nerve activity during dynamic exercise in humans

We sought to determine whether carotid baroreflex (CBR) control of muscle sympathetic nerve activity (MSNA) was altered during dynamic exercise. In five men and three women, 23.8 +/- 0.7 (SE) yr of age, CBR function was evaluated at rest and during 20 min of arm cycling at 50% peak O(2) uptake using 5-s periods of neck pressure and neck suction. From rest to steady-state arm cycling, mean arterial pressure (MAP) was significantly increased from 90.0 +/- 2.7 to 118.7 +/- 3.6 mmHg and MSNA burst frequency (microneurography at the peroneal nerve) was elevated by 51 +/- 14% (P < 0.01). However, despite the marked increases in MAP and MSNA during exercise, CBR-Delta%MSNA responses elicited by the application of various levels of neck pressure and neck suction ranging from +45 to -80 Torr were not significantly different from those at rest. Furthermore, estimated baroreflex sensitivity for the control of MSNA at rest was the same as during exercise (P = 0.74) across the range of neck chamber pressures. Thus CBR control of sympathetic nerve activity appears to be preserved during moderate-intensity dynamic exercise.

Non-NASA Center↗
NASA NTRSDate not supplied

Comparison of Multispectral Imaging and Traditional Fundoscopy in the Detection of Terrestrial Retinal and Optic Nerve Pathologies like those Encountered During and/or Immediately Following Long-Duration Spaceflight

INTRODUCTION: The purpose of this investigation was to evaluate if MultiColor Imaging (MCI) can replace color fundus photography (CFP) as a diagnostic screening tool during spaceflight. MCI significantly reduces crew time (approx. 115 minutes/session, 36 hours/year) by eliminating nominal on-orbit fundoscopy sessions, while also providing the option to capture a larger field of view (55 vs. 35). METHODS: A comprehensive PubMed literature search was conducted using the following key words: multicolor, multispectral, imaging, retina, choroid, optic nerve, optic disc, and papilledema. Publications were filtered based on optic nerve and chorioretinal pathologies matching those seen during or immediately after spaceflight: optic disc edema (ODE), cotton wool spots (CWS), retinal hemorrhage, pigment epithelial detachment (PED), and serous chorioretinopathy (SCR). In a separate effort, 44 multicolor images (30 abnormal) of terrestrial patients were graded and compared to corresponding color fundus images acquired at the Doheny Eye Centers and UCLA. RESULTS: The search identified 340 articles; 9 describing MCI in relevant pathologies, 6 comparing MCI to CFP. MCI is superior in detecting CWS (1 paper), PED (2 papers), retinal hemorrhages (2 papers), and choroidal folds (1 paper), and can better delineate extent or boundaries of subretinal fluid and identify areas of RPE damage in SCR (2 papers). On MCI, ODE was described as a hyperreflective ring with a green shift and indistinct disc margins, with equaldetectability as using CFP (3 papers). Grading at Doheny Eye Institute confirmed these findings. DISCUSSION: MCI can effectively detect all retinal and optic nerve findings detectable by CFP during and immediately post-spaceflight and represents a suitable replacement as an on-orbit diagnostic screening tool. Additionally, by eliminating the nominal on-orbit fundoscopy sessions, dozens of crew hours are spared per year by utilizing MCI.

Jorge Nagel↗
NASA NTRS2022

Changes in Optic Nerve Head and Retinal Morphology During Spaceflight and Acute Fluid Shift Reversal

Importance: Countermeasures that reverse the headward fluid shift experienced in weightlessness have the potential to mitigate spaceflight-associated neuro-ocular syndrome. This study investigated whether use of the countermeasure lower-body negative pressure during spaceflight was associated with changes in ocular structure. Objective: To determine whether changes to the optic nerve head and retina during spaceflight can be mitigated by brief in-flight application of 25-mm Hg lower-body negative pressure. Design, Setting, and Participants: In the National Aeronautics and Space Administration’s “Fluid Shifts Study,” a prospective cohort study, optical coherence tomography scans of the optic nerve head and macula were obtained from US and international crew members before flight, in-flight, and up to 180 days after return to Earth. In-flight scans were obtained both under normal weightless conditions and 10 to 20 minutes into lower-body negative pressure exposure. Preflight and postflight data were collected in the seated, supine, and head-down tilt postures. Crew members completed 6- to 12-month missions that took place on the International Space Station. Data were analyzed from 2016 to 2021. Interventions or Exposures: Spaceflight and lower-body negative pressure. Main Outcomes and Measures: Changes in minimum rim width, optic cup volume, Bruch membrane opening height, peripapillary total retinal thickness, and macular thickness. Results: Mean (SD) flight duration for the 14 crew members (mean [SD] age, 45 [6] years; 11 male crew members [79%]) was 214 (72) days. Ocular changes on flight day 150, as compared with preflight seated, included an increase in minimum rim width (33.8 μm; 95% CI, 27.9-39.7 μm; P < .001), decrease in cup volume (0.038 mm^3; 95% CI, 0.030-0.046 mm^3; P < .001), posterior displacement of Bruch membrane opening (−9.0 μm; 95% CI, −15.7 to −2.2 μm; P = .009), and decrease in macular thickness (fovea to 500 μm, 5.1 μm; 95% CI, 3.5-6.8 μm; P < .001). Brief exposure to lower-body negative pressure did not affect these parameters. Conclusions and Relevance: Results of this cohort study suggest that peripapillary tissue thickening, decreased cup volume, and mild central macular thinning were associated with long-duration spaceflight. Acute exposure to 25-mm Hg lower-body negative pressure did not alter optic nerve head or retinal morphology, suggesting that longer durations of a fluid shift reversal may be needed to mitigate spaceflight-induced changes and/or other factors are involved.

Laura P. Pardon↗
DOE OSTI2017

Metal organic frameworks for the catalytic detoxification of chemical warfare nerve agents

A method of using a metal organic framework (MOF) comprising a metal ion and an at least bidendate organic ligand to catalytically detoxify chemical warfare nerve agents including exposing the metal-organic-framework (MOF) to the chemical warfare nerve agent and catalytically decomposing the nerve agent with the MOF.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Accumulation of sorbitol in the sciatic nerve modulates circadian properties of diabetes-induced neuropathic pain hypersensitivity in a diabetic mouse model

Highlights: • K{sub d} values of Se(IV) sorption on Grimsel granodiorite and main minerals. • Relationship between K{sub d} values and SSA. • Surface complexation modelling of Se(IV) on biotite. • Sorption site density calculated by molecular modelling. The intensity of pain in diabetic neuropathy varies in a circadian time-dependent manner. It is well known that diabetes has two distinct types, which are differentiated based on the cause of the disease. Previous studies have yet to compare the circadian properties of the pain intensity of diabetic neuropathy between type I and type II diabetes. In this study, we demonstrated that the pain intensity of diabetic peripheral neuropathy in a db/db mouse model of type II diabetes showed a significant diurnal oscillation, but such time-dependent oscillation was not detected in a streptozotocin (STZ)-induced type I diabetic mouse model. The polyol pathway-induced accumulation of sorbitol in peripheral nerve cells suppresses Na{sup +}/K{sup +}-ATPase activity, which is associated with the intensity of pain in diabetic neuropathy. In db/db mice, this accumulation of sorbitol in peripheral nerve cells showed significant diurnal oscillation. In addition, pain intensity and Na{sup +}/K{sup +}-ATPase activity were decreased at the peak time of sorbitol accumulation in these mice. Although STZ-induced diabetic mice also showed sorbitol accumulation and Na{sup +}/K{sup +}-ATPase dysfunction, these measures did not oscillate in a time-dependent manner. These findings reveal differences in the circadian properties of pain hypersensitivity in mouse models of type I and type II diabetes, and also provide ideas for developing novel approaches to the management of diabetic neuropathy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Intravesical ATP instillation induces urinary frequency because of activation of bladder afferent nerves without inflammatory changes in mice: A promising model for overactive bladder

Highlights: • Intravesical ATP instillation induces urinary frequency. • Intravesical ATP instillation activates bladder afferent nerves. • Intravesical ATP instillation do not induce bladder inflammatory changes. • ATP in the bladder lumen is involved in enhancement of the micturition reflex. • Our mouse model of ATP-induced urinary frequency is a promising model of OAB. ATP in the suburothelial layer is released from the bladder urothelium by mechanical stimuli. ATP directly activates purinergic receptors that are expressed on primary bladder afferent neurons and induces the micturition reflex. Although ATP is also released to the bladder lumen from the bladder urothelium, the role of ATP in the bladder lumen is unknown. Recently, clinical studies have reported that urinary ATP levels are much higher in patients with an overactive bladder than healthy controls. These results suggest that ATP in the bladder lumen is also involved in the micturition reflex. In this study, we performed intravesical ATP instillation in the mouse bladder. We evaluated urinary function with novel reliable methods using improved cystometry and ultrasonography, which we previously established. We found that intravesical ATP instillation induced urinary frequency because of activation of bladder afferent nerves without inflammatory changes in the bladder or an increase in post-void residual urine. These results suggest that not only ATP in the suburothelial layer, but also ATP in the bladder lumen, are involved in enhancement of the micturition reflex.

60 APPLIED LIFE SCIENCES↗