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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Effective delivery of recombinant proteins to rod photoreceptors via lipid nanovesicles

The potential of liposomes to deliver functional proteins in retinal photoreceptors and modulate their physiological response was investigated by two experimental approaches. First, we treated isolated mouse retinas with liposomes encapsulating either recoverin, an important endogenous protein operating in visual phototransduction, or antibodies against recoverin. We then intravitrally injected in vivo liposomes encapsulating either rhodamin B or recoverin and we investigated the distribution in retina sections by confocal microscopy. The content of liposomes was found to be released in higher amount in the photoreceptor layer than in the other regions of the retina and the functional effects of the release were in line with the current model of phototransduction. Our study sets the basis for quantitative investigations aimed at assessing the potential of intraocular protein delivery via biocompatible nanovesicles, with promising implications for the treatment of retinal diseases affecting the photoreceptor layer. - Highlights: • Recombinant proteins encapsulated in nano-sized liposomes injected intravitreally reach retinal photoreceptors. • The phototransduction cascade in rods is modulated by the liposome content. • Mathematical modeling predicts the alteration of the photoresponses following liposome fusion.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

A novel expression vector for the improved solubility of recombinant scorpion venom in Escherichia coli

Recombinant scorpion anti-excitation peptide (rANEP) has previously been expressed using the pET32a system and purified via affinity chromatography. However, rANEP is expressed in BL21(DE3) cells as an inclusion body, and the affinity tag can not be removed. To overcome this problem, we used a variety of protein, DsbA, MBP, TrxA, intein, and affinity tags in fusion and co-expression to achieve soluble and functional rANEP without any affinity tag. In the pCIT-ANEP expression vector, the highest soluble expression level was approximately 90% of the total cellular proteins in E. coli, and the rANEP was cleaved by the intein protein and subsequently purified to obtain rANEP, which had the same activity as the natural ANEP. The purity of rANEP obtained using this method was over 95%, with a quantity of 5.1 mg from of purified rANEP from 1 L of culture. This method could expand the application of the soluble expression of disulfide-rich peptides in E. coli.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Recombinant human brain natriuretic peptide regulates PI3K/AKT/mTOR pathway through lncRNA EGOT to attenuate hypoxia-induced injury in H9c2 cardiomyocytes

Highlights: • rhBNP alleviated hypoxia-induced H9c2 cell injury and elevated EGOT expression. • EGOT suppression reversed the effects of rhBNP on hypoxia-induced cell injury. • EGOT positively regulated the expression of Cyclin D1. • rhBNP alleviated hypoxia-induced cell injury by PI3K/AKT/mTOR pathway. This study aimed to investigate whether recombinant human brain natriuretic peptide (rhBNP) regulated hypoxia-induced injury in H9c2 cardiomyocytes through lncRNA EGOT. H9c2 cardiomyocytes were cultured under normoxia and hypoxia (21% and 3% O{sub 2}) conditions, and whether hypoxia induced injury by assessing cell viability, apoptosis and autophagy. H9c2 cells were then treated with different doses of exogenous rhBNP (200, 600 and 900 nmol/L, respectively) and the effects of rhBNP on hypoxia-induced injury in H9c2 cells as well as the expression of EGOT were studied. In addition, the regulatory relationships between rhBNP and EGOT as well as between rhBNP and PI3K/AKT/mTOR pathway in hypoxia-treated H9c2 cells were investigated. Hypoxia significantly induced injury in H9c2 cells (inhibited cell viability and promoted cell apoptosis and autophagy) and decreased the expression of EGOT. However, administration of rhBNP alleviated hypoxia-induced injury in H9c2 cells and elevated expression of EGOT. Suppression of EGOT significantly reversed the effects of rhBNP on hypoxia-induced injury in H9c2 cells. Further studies showed that the effects of EGOT on cell viability and apoptosis were by positively regulating the expression of Cyclin D1. Moreover, rhBNP alleviated hypoxia-induced cell injury by activating PI3K/AKT/mTOR pathway in H9c2 cells. Our results reveal that rhBNP may play a protective role in attenuating hypoxia-induced injury in H9c2 cardiomyocytes via regulating lncRNA EGOT/Cyclin D1/PI3K/AKT/mTOR pathway axis. The findings will provide a new strategy for the treatment of heart failure induced by hypoxia.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Combination therapy of tumor-targeting Salmonella typhimurium A1-R and oral recombinant methioninase regresses a BRAF-V600E-negative melanoma

Melanoma is a recalcitrant cancer. To improve and individualize treatment for this disease, we previously developed a patient-derived orthotopic xenograft (PDOX) model for melanoma. We previously reported the individual efficacy of tumor-targeting Salmonella typhimurium A1-R (S. typhimurium A1-R) and recombinant methioninase (rMETase) for melanoma in the PDOX models of this disease. In the present study, we evaluated the efficacy of the combination of S. typhimurium A1-R with orally-administered rMETase (o-rMETase) for BRAF-V600E-negative melanoma in a PDOX model. Three weeks after implantation, 60 PDOX mouse models were randomized into six groups of 10 mice each: untreated control, temozolomide (TEM); o-rMETase; S. typhimurium A1-R; TEM + rMETase, S. typhimurium A1-R + rMETase. All treatments inhibited tumor growth compared to untreated control (TEM: p S. typhimurium A1-R: p S. typhimurium A1-R + rMETase: p S. typhimurium A1-R + o-rMETase which regressed this melanoma PDOX, thereby indicating a new paradigm for treatment of metastatic melanoma.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Statistical optimization of culture medium to produce recombinant viral protein by Escherichia coli host for diagnostic kit to detect human immunodeficiency virus (HIV) infection

The maximal production of recombinant HIV1 gp41 by E. coli was examined in optimal culture condition and medium compositions. The culture condition such as growth, initial medium pHs, IPTG concentrations, induction times, temperature (0.5 OD, 7.6, 0.75 mM, 4.6 h, 32 °C respectively), and yeast extract (7.51 g/l), tryptone (7.26 g/l), glucose (2.45 g/l), NaCl (20.40 g/l), betaine (10.41 mM) and ampicillin (71.23 μg/ml) was optimized using statistical experimental design and response surface method (RSM). One of the main popular methods to attain high cell density in fed-batch culture is by controlling the nutrient feeding, which is often necessary for high yield in protein (0.63–0.72 mg/l) and cell (1.7–2 g/l) of the desired product in four litter fermentations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Acetylation of lysine residues in the recombinant nucleoprotein and VP40 matrix protein of Zaire Ebolavirus by eukaryotic histone acetyltransferases

Acetylation of histones and other proteins plays crucial roles in transcriptional regulation, chromatin organization, and other biological processes. It has been recently reported that the nucleoprotein (NP) of influenza virus is acetylated in infected cells, and this modification contributes to the RNA polymerization activity of the virus. As the influenza virus, the Ebolavirus contains single-stranded negative-sense RNA as its viral genome, which interacts with NP and other viral proteins. In this study, we performed a series of biochemical experiments and revealed that the recombinant Ebolavirus NP and the viral matrix protein VP40, which binds with NP, were acetylated by eukaryotic histone acetyltransferases, such as P300/CREB-binding protein (P300/CBP) and P300/CBP-associated factor (PCAF), in vitro. Mass spectrometry was used to identify the lysine residues that were potential acetylation targets in NP and VP40. The identified lysine residues in NP were located in the RNA-binding cleft and the VP35-binding domain. Potentially acetylated lysine targets in VP40 were identified in the basic patch, which is necessary for constructing oligomers. These results suggest that the acetylation of these lysine residues is involved in the interactions between viral proteins.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Pressure dependent kinetic analysis of pathways to naphthalene from cyclopentadienyl recombination

Cyclopentadiene (CPD) and cyclopentadienyl radical (CPDyl) reactions are known to provide fast routes to naphthalene and other polycyclic aromatic hydrocarbon (PAH) precursors in many systems. In this work, we combine literature quantum chemical pathways for the CPDyl + CPDyl recombination reaction and provide pressure dependent rate coefficient calculations and analysis. Here we find that the simplified 1-step global reaction leading to naphthalene and two H atoms used in many kinetic models is not an adequate description of this chemistry at conditions of relevance to pyrolysis and steam cracking. The C 10 H 10 species is observed to live long enough to undergo H abstraction reactions to enter the C 10 H 9 potential energy surface (PES). Rate coefficient expressions as functions of T and P are reported in CHEMKIN format for future use in kinetic modeling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Kinetic isotope effects for dissociative recombination of tritiated ketenyl ion ( 3 HCCO + ): A surface-hopping ab initio molecular dynamics study

Dissociative recombination (DR) reactions are important when modeling charged species in the presence of free electrons. While experimental measurements of DR reaction rates are challenging, surface hopping ab initio molecular dynamics (SH-AIMD) simulations provide an attractive alternative. SH-AIMD is especially well-suited for estimating branching ratios, i.e., the relative rates of competing production channels, for DR reactions. Although the radiolysis of diatomic tritium has been studied experimentally, previous attempts to model these systems have failed to account for isotope effects in DR reactions. Previous SH-AIMD studies have also not investigated tritium isotope effects for the branching ratios of DR reactions. In this study, we compute the DR branching ratios of the protiated and tritiated ketenyl ion. Comparison with literature values for the protiated branching ratios provides confidence in the reliability of our SH-AIMD results. Our simulations predict a significant increase of the HC + CO branching ratio for the tritiated system.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Combining Heavy Ion Radiation and Artificial MicroRNAs to Target the Homologous Recombination Repair Gene Efficiently Kills Human Tumor Cells

Purpose: Previously, we demonstrated that heavy ions kill more cells at the same dose than X-rays because DNA-clustered lesions produced by heavy ions affect nonhomologous end-joining (NHEJ) repair but not homologous recombination repair (HRR). We have also shown that our designed artificial microRNAs (amiRs) could efficiently target XRCC4 (an essential factor for NHEJ) or XRCC2 (an essential factor for HRR) and sensitize human tumor cells to X-rays. Based on these data, we were interested in testing the hypothesis that combining heavy ions and amiRs to target HRR but not NHEJ should more efficiently kill human tumor cells. Methods and Materials: Human tumor cell lines (U87MG, a brain tumor cell line, and A549, a lung cancer cell line) and their counterparts, overexpressed with amiR to target XRCC2, XRCC4 or both, were used in this study. Survival sensitivities were examined using a clonogenic assay after these cells were exposed to X-rays or heavy ions. In addition, these cell lines were subcutaneously injected into nude mice to form xenografts and the tumor size was compared after the tumor areas were exposed to X-rays or heavy ions. Results: Although targeting either XRCC4 (NHEJ factor) or XRCC2 (HRR factor) sensitized the human tumor cells to X-rays, in vitro and the xenograft animal model, targeting only XRCC2 but not XRCC4 sensitized the human tumor cells to heavy ions in vitro and in the xenograft animal model. Conclusions: Combining heavy ions with targeting the HRR pathway, but not the NHEJ pathway, could significantly improve the efficiency of tumor cell death.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Effect of Recombinant Human Deoxyribonuclease on Oropharyngeal Secretions in Patients With Head-and-Neck Cancers Treated With Radiochemotherapy

Purpose: The current study examined the effect of recombinant human deoxyribonuclease (rhDNase) on quality of life (QOL) measures, clinical improvement, and DNA content of thick oropharyngeal secretions (OPS) in patients with head-and-neck (H and N) cancers. Methods and Materials: Thirty-six patients with local-regional advanced H and N cancer receiving chemoradiationtherapy (CRT) were randomized to receive either placebo or rhDNase. Endpoints included MD Anderson Symptom Inventory-Head and Neck (MDASI-HN) and Functional Assessment of Cancer Therapy–Head and Neck (FACT-NH) scores, along with clinical assessment and DNA concentration of OPS. Results: There were no statistically significant differences in patients' QOL outcomes over the study period. Both groups showed an increase in symptom and interference scores, although patients in the rhDNase group showed a greater decline in both scores during the 3 months posttreatment. Similarly, both groups showed a decline in physical and functional well being but recovered in the 3 months posttreatment follow-up, with the rhDNase group exhibiting speedier recovery. Patients in the rhDNase group exhibited significant clinical improvement in OPS, blindly assessed by a physician, compared with the placebo group (67% vs 27%, respectively; P=.046). The rhDNase group showed no change in OPS-DNA concentration, although the placebo group showed a significant increase in DNA concentration during the drug trial (P=.045). There was no differences in acute toxicities between the 2 groups. Conclusions: Our preliminary data suggest that rhDNase did not significantly improve study primary endpoints of QOL measures compared with the placebo group. However, there was a significant improvement in secondary endpoints of clinically assessed OPS and DNA concentration compared with placebo in H and N cancer patients treated with CRT. Further investigation in larger numbers of patients is warranted.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

Silicon nanocluster anion-argon cation recombination via hybrid continuum-molecular dynamics calculations

Prediction of the charge distribution on particles in an aerosol is critical not only in electrical mobility based characterization methods, but also in understanding the role that charging plays in particle growth in gas phase synthesis reactors. The latter is particularly important in non-thermal plasma synthesis reactors, wherein nanoclusters form and grow from vapor phase precursors in a high electron and high ion density environment. In plasmas, because free electrons are much less massive and much more mobile than positive gas ions, nanocluster charge distributions are biased negative. Furthermore, neutral or even positively charged nanoclusters may exist, depending on the rate of nanocluster-gas ion recombination, and nanocluster-nanocluster collisions may greatly contribute to nanocluster growth if not Coulombically suppressed.

42 ENGINEERING↗
DOE OSTI2022

Recombinant FimH Adhesin Demonstrates How the Allosteric Catch Bond Mechanism Can Support Fast and Strong Bacterial Attachment in the Absence of Shear

The FimH protein of Escherichia coli is a model two-domain adhesin that is able to mediate an allosteric catch bond mechanism of bacterial cell attachment, where the mannose-binding lectin domain switches from an ‘inactive’ conformation with fast binding to mannose to an ‘active’ conformation with slow detachment from mannose. Because mechanical tensile force favors separation of the domains and, thus, FimH activation, it has been thought that the catch bonds can only be manifested in a fluidic shear-dependent mode of adhesion. Here, we used recombinant FimH variants with a weakened inter-domain interaction and show that a fast and sustained allosteric activation of FimH can also occur under static, non-shear conditions. Moreover, it appears that lectin domain conformational activation happens intrinsically at a constant rate, independently from its ability to interact with the pilin domain or mannose. However, the latter two factors control the rate of FimH deactivation. Thus, the allosteric catch bond mechanism can be a much broader phenomenon involved in both fast and strong cell-pathogen attachments under a broad range of hydrodynamic conditions. In conclusion, this concept that allostery can enable more effective receptor-ligand interactions is fundamentally different from the conventional wisdom that allostery provides a mechanism to turn binding off under specific conditions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

Reducing Non-Radiative Recombination in Perovskite Solar Cells with a SiO2-Graphene Oxide Buried Interface Layer

Perovskite solar cells (PSCs) have emerged as a transformative photovoltaic technology. However, the device performance of inverted PSCs is dramatically limited by surface defects and the underlying film morphology of metal halide perovskite (MHP) thin film. Herein, we report a novel buried interface layer consisting of SiO2 nanoparticles (NPs) chemically bonded to graphene oxide (GO), deposited atop a hydrophobic hole extraction layer (HEL) to address this limitation. The SiO2 NPs serve as insoluble scaffolds that immobilize GO sheets on the hydrophobic HEL surface, enabling the formation of homogeneous MHP thin films. Meanwhile, the GO functional groups interact with surface-uncoordinated Pb2+, suppressing interfacial defects and guiding crystal grain growth of the resultant MHP thin films. This synergistic effect suppresses non-radiative charge recombination and enhances charge extraction efficiency. As a result, a 26.07% efficiency with significantly suppressed photocurrent hysteresis is observed from PSCs incorporating the SiO2-GO buried interface layer. Moreover, the above PSCs maintain 92% of their initial PCE after 1800 h of continuous operation at the maximum power point under AM 1.5 G (100 mW/cm2) illumination at 25 degrees C in air with 50-60% relative humidity. These results demonstrate that we have developed a facile and effective way to realize high-performance inverted PSCs.

14 SOLAR ENERGY↗
DOE OSTI2014

Recombinant human tripeptidyl peptidase-1 infusion to the monkey CNS: Safety, pharmacokinetics, and distribution

CLN2 disease is caused by deficiency in tripeptidyl peptidase-1 (TPP1), leading to neurodegeneration and death. The safety, pharmacokinetics (PK), and CNS distribution of recombinant human TPP1 (rhTPP1) were characterized following a single intracerebroventricular (ICV) or intrathecal-lumbar (IT-L) infusion to cynomolgus monkeys. Animals received 0, 5, 14, or 20 mg rhTPP1, ICV, or 14 mg IT-L, in artificial cerebrospinal fluid (aCSF) vehicle. Plasma and CSF were collected for PK analysis. Necropsies occurred at 3, 7, and 14 days post-infusion. CNS tissues were sampled for rhTPP1 distribution. TPP1 infusion was well tolerated and without effect on clinical observations or ECG. A mild increase in CSF white blood cells (WBCs) was detected transiently after ICV infusion. Isolated histological changes related to catheter placement and infusion were observed in ICV treated animals, including vehicle controls. The CSF and plasma exposure profiles were equivalent between animals that received an ICV or IT-L infusion. TPP1 levels peaked at the end of infusion, at which point the enzyme was present in plasma at 0.3% to 0.5% of CSF levels. TPP1 was detected in brain tissues with half-lives of 3–14 days. CNS distribution between ICV and IT-L administration was similar, although ICV resulted in distribution to deep brain structures including the thalamus, midbrain, and striatum. Direct CNS infusion of rhTPP1 was well tolerated with no drug related safety findings. The favorable nonclinical profile of ICV rhTPP1 supports the treatment of CLN2 by direct administration to the CNS. - Highlights: • TPP1 enzyme replacement therapy to the CNS is in development for CLN2 disease. • Toxicology, pharmacokinetics, and CNS distribution were assessed in monkeys. • TPP1 infusion directly to the brain did not result in any safety concerns. • A positive pharmacokinetic and distribution profile resulted from TPP1 infusion. • This study demonstrates the feasibility of ICV administered rhTPP1 to treat CLN2.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Protection of non-human primates against rabies with an adenovirus recombinant vaccine

Rabies remains a major neglected global zoonosis. New vaccine strategies are needed for human rabies prophylaxis. A single intramuscular immunization with a moderate dose of an experimental chimpanzee adenovirus (Ad) vector serotype SAd-V24, also termed AdC68, expressing the rabies virus glycoprotein, resulted in sustained titers of rabies virus neutralizing antibodies and protection against a lethal rabies virus challenge infection in a non-human primate model. Taken together, these data demonstrate the safety, immunogenicity, and efficacy of the recombinant Ad-rabies vector for further consideration in human clinical trials. - Highlights: • Pre-exposure vaccination with vaccine based on a chimpanzee derived adenovirus protects against rabies. • Protection is sustained. • Protection is achieved with single low-dose of vaccine given intramuscularly. • Protection is not affected by pre-existing antibodies to common human serotypes of adenovirus.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

A Sendai virus recombinant vaccine expressing a gene for truncated human metapneumovirus (hMPV) fusion protein protects cotton rats from hMPV challenge

Human metapneumovirus (hMPV) infections pose a serious health risk to young children, particularly in cases of premature birth. No licensed vaccine exists and there is no standard treatment for hMPV infections apart from supportive hospital care. We describe the production of a Sendai virus (SeV) recombinant that carries a gene for a truncated hMPV fusion (F) protein (SeV-MPV-Ft). The vaccine induces binding and neutralizing antibody responses toward hMPV and protection against challenge with hMPV in a cotton rat system. Results encourage advanced development of SeV-MPV-Ft to prevent the morbidity and mortality caused by hMPV infections in young children. - Highlights: • A Sendai virus-based human metapneumovirus (hMPV) vaccine is being developed. • SeV-MPV-Ft carries a gene for a truncated metapneumovirus fusion protein. • The intranasal vaccine induces hMPV-specific binding antibodies in cotton rats. • The vaccine induces hMPV-specific neutralizing antibodies in cotton rats. • A single immunization protects against hMPV challenge in vivo.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Uniformly 15N-Labeled Recombinant Ricin A-chain as an Internal Retention Time Standard for Increased Confidence in Forensic Identification of Ricin by Untargeted Nanoflow Liquid Chromatography-Tandem Mass Spectrometry

Ricin, a toxic protein from the castor plant, is of forensic and biosecurity interest because of its high toxicity and common occurrence in crimes and attempted crimes. Qualitative methods to detect ricin are therefore needed. Untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics methods are well-suited because of their high speci-ficity. Specificity in LC-MS/MS comes from both the LC and MS components. However, modern untargeted proteomics methods often use nanoflow LC, which has less reproducible retention times than standard-flow LC, making it challenging to use retention time as a point of identification in a forensic assay. We address this challenge by using retention times rela-tive to a standard, namely uniformly 15N–labeled ricin A-chain produced recombinantly in a bacterial expression system. This material, added as an internal standard prior to trypsin digestion, produces a stable isotope labeled standard for every ricin tryptic peptide in the sample. We show that the MS signals for 15N and natural isotopic abundance ricin peptides are distinct, with mass shifts that correspond to the numbers of nitrogen atoms in each peptide or fragment. We also show that, as expected, labeled and unlabeled peptides coelute, with relative retention time differences of less than 0.2%.

ricin, mass spectrometry, isotope, nitrogen-15, re↗
DOE OSTI2026

Rate constants and third-body collision efficiencies for recombination of Na with OH and O2: Implications for flame inhibition by alkali salts

Flame inhibition by alkali metals has implications for solid fuel combustion, fire safety, and a number of industrial processes. While the mechanism of inhibition is fairly well understood, details related to thermodynamic properties and rate constants are still in question. In the present work, the recombination of Na with OH (R5) and O2 (R7), respectively, was characterized theoretically, and the implications for modeling laminar premixed hydrogen flames doped with sodium species were examined. Third-body collision efficiencies and low-pressure-limit rate constants were obtained using newly fitted ab initio-based potential energy surfaces, classical trajectories, and one-dimensional master equation calculations. The results are consistent with available experimental results and aid in the present modeling study by providing rate information for bath gases and conditions that remain unexplored experimentally. Chemical kinetic modeling of relative Na and absolute H and OH profiles in H2-fueled laminar, premixed flames doped with a sodium salt shows that the most important radical removal cycle is the sequence Na + OH (+M) → NaOH (+M) (R5), NaOH + H → Na + H2O (R12), even under oxidizing conditions. A secondary cycle, Na + O2 (+M) ⇄ NaO2 (+M) (R7), NaO2 + OH → NaOH + O2 (R14), is less important due to the low thermal stability of NaO2. In most flames, reaction R7 is partially equilibrated, and reaction R14 becomes rate-limiting for the second cycle. The flame analysis supports a lower value of k14 than indicated by recent work on KO2 + OH, but more work is required to confirm this.

Jasper, Ahren W.↗