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1.
Bioeng Transl Med ; 8(6): e10571, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38023726

RESUMO

Manufacture of chimeric antigen receptor (CAR)-T cells usually involves the use of viral delivery systems to achieve high transgene expression. However, it can be costly and may result in random integration of the CAR into the genome, creating several disadvantages including variation in transgene expression, functional gene silencing and potential oncogenic transformation. Here, we optimized the method of nonviral, CRISPR/Cas9 genome editing using large donor DNA delivery, knocked-in an anti-tumor single chain variable fragment (scFv) into the N-terminus of CD3ε and efficiently generated fusion protein (FP) T cells. These cells displayed FP integration within the TCR/CD3 complex, lower variability in gene expression compared to CAR-T cells and good cell expansion after transfection. CD3ε FP T cells were predominantly CD8+ effector memory T cells, and exhibited anti-tumor activity in vitro and in vivo. Dual targeting FP T cells were also generated through the incorporation of scFvs into other CD3 subunits and CD28. Compared to viral-based methods, this method serves as an alternative and versatile way of generating T cells with tumor-targeting receptors for cancer immunotherapy.

2.
Eur J Immunol ; 53(9): e2250355, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-36991561

RESUMO

The lymph node (LN) is home to resident macrophage populations that are essential for immune function and homeostasis, but key factors controlling this niche are undefined. Here, we show that fibroblastic reticular cells (FRCs) are an essential component of the LN macrophage niche. Genetic ablation of FRCs caused rapid loss of macrophages and monocytes from LNs across two in vivo models. Macrophages co-localized with FRCs in human LNs, and murine single-cell RNA-sequencing revealed that FRC subsets broadly expressed master macrophage regulator CSF1. Functional assays containing purified FRCs and monocytes showed that CSF1R signaling was sufficient to support macrophage development. These effects were conserved between mouse and human systems. These data indicate an important role for FRCs in maintaining the LN parenchymal macrophage niche.


Assuntos
Fibroblastos , Transdução de Sinais , Camundongos , Humanos , Animais , Macrófagos , Linfonodos
3.
Front Immunol ; 13: 968395, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36059451

RESUMO

Chimeric antigen receptor (CAR)-T therapy has demonstrated remarkable outcomes for B cell malignancies, however, its application for T cell lymphoma, particularly cutaneous T cell lymphoma (CTCL), has been limited. Barriers to effective CAR-T cell therapy in treating CTCL include T cell aplasia in autologous transplants, CAR-T product contamination with leukemic T cells, CAR-T fratricide (when the target antigen is present on normal T cells), and tumor heterogeneity. To address these critical challenges, innovative CAR engineering by targeting multiple antigens to strike a balance between efficacy and safety of the therapy is necessary. In this review, we discuss the current obstacles to CAR-T cell therapy and highlight potential targets in treating CTCL. Looking forward, we propose strategies to develop more powerful dual CARs that are advancing towards the clinic in CTCL therapy.


Assuntos
Linfoma Cutâneo de Células T , Receptores de Antígenos Quiméricos , Neoplasias Cutâneas , Humanos , Imunoterapia Adotiva/efeitos adversos , Linfoma Cutâneo de Células T/terapia , Receptores de Antígenos Quiméricos/genética , Neoplasias Cutâneas/terapia , Linfócitos T
4.
Transl Oncol ; 24: 101477, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35905640

RESUMO

Chimeric antigen receptor (CAR-) T cells are revolutionizing cancer treatment, as a direct result of their clinical impact on the treatment of hematological malignancies. However for solid tumors, CAR-T cell therapeutic efficacy remains limited, primarily due to the complex immunosuppressive tumor microenvironment, inefficient access to tumor cells and poor persistence of the killer cells. In this in vitro study, an injectable, gelatin-based micro-hydrogel system that can encapsulate and deliver effective CAR-T therapy is investigated. CAR-T cells targeting TAG-72, encapsulated in these microgels possessed high viability (> 87%) after 7 days, equivalent to those grown under normal expansion conditions, with retention of the T cell phenotype and functionality. Microgel recovered CAR-T cells demonstrated potent on-target cytotoxicity against human ovarian cancer in vitro and on three-dimensional tumor spheroids, by completely eliminating tumor cells. The gelatin-based micro-hydrogels have the potential to serve as carrier systems to augment CAR-T immunotherapeutic treatment of solid tumors.

5.
Front Oncol ; 12: 836005, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35692780

RESUMO

Integrin-linked kinase (ILK) has been implicated as a molecular driver and mediator in both inflammation and tumorigenesis of the colon. However, a role for ILK in the tumor microenvironment (TME) and immune evasion has not been investigated. Here, we show a correlation of ILK expression with the immunosuppressive TME and cancer prognosis. We also uncover a role for ILK in the regulation of programmed death-ligand 1 (PD-L1) expression and immune cell cytotoxicity. Interrogation of web-based data-mining platforms, showed upregulation of ILK expression in tumors and adjacent-non tumor tissue of colorectal cancer (CRC) associated with poor survival and advanced stages. ILK expression was correlated with cancer-associated fibroblast (CAFs) and immunosuppressive cell infiltration including regulatory T cells (Treg) and M2 macrophages (M2) in addition to their gene markers. ILK expression was also significantly correlated with the expression of different cytokines and chemokines. ILK expression showed pronounced association with different important immune checkpoints including PD-L1. Deletion of the ILK gene in PD-L1 positive CRC cell lines using a doxycycline inducible-CRISPR/Cas9, resulted in suppression of both the basal and IFNγ-induced PD-L1 expression via downregulating NF-κB p65. This subsequently sensitized the CRC cells to NK92 immune cell cytotoxicity. These findings suggest that ILK can be used as a biomarker for prognosis and immune cell infiltration in colon cancer. Moreover, ILK could provide a therapeutic target to prevent immune evasion mediated by the expression of PD-L1.

6.
Future Sci OA ; 8(5): FSO794, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35662742

RESUMO

Aim: To evaluate safety and efficacy of low dose autologous adipose-derived mesenchymal stem cells (ADMSCs) for treatment of disc degeneration resulting in low back pain (LBP). Methods: Nine participants with chronic LBP originating from single-level lumbar disc disease underwent intradiscal injection of 10 million ADMSCs with optional repetition after 6 months. Results: No unexpected or serious adverse events were recorded. Seven (78%) of participants reported reductions in pain 12 months after treatment. Five (56%) reported increased work capacity. Three (33%) reduced analgesic medication. Improvements in EQ-5D and Oswestry disability index results were observed. MRI demonstrated no further disc degeneration and improvements to annular fissures and disc protrusions. Conclusion: This study provides initial evidence of safety and efficacy of ADMSCs for discogenic LBP.

7.
Pharmacy (Basel) ; 9(4)2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-34842820

RESUMO

Little is known about health professions students' awareness and attitudes regarding public health in the United States. Therefore, the purpose of this study was to assess medical and pharmacy students' knowledge and interest in the Healthy People initiative as well as perceptions of public health content in their curricula. An electronic survey was distributed in March 2021 in seven schools across Ohio; participation was incentivized through a USD 5 donation to the Ohio Association of Foodbanks to aid in COVID-19 relief efforts (maximum USD 1000) for each completed survey. A total of 182 medical students and 233 pharmacy students participated (12% response rate). Less than one-third of respondents reported familiarity with Healthy People and correctly identified the latest edition. However, nearly all respondents agreed public health initiatives are valuable to the American healthcare system. Almost all students expressed a desire to practice interprofessionally to attain public health goals. Both medical and pharmacy students recognized core public health topics in their curricula, and nearly 90% wanted more information. These findings indicate that the majority of medical and pharmacy students in Ohio believe public health initiatives to be important, yet knowledge gaps exist regarding Healthy People. This information can guide curricular efforts and inform future studies of health professions students.

8.
Cells ; 10(10)2021 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-34685611

RESUMO

Cellular immunotherapy is revolutionizing cancer treatment. However, autologous transplants are complex, costly, and limited by the number and quality of T cells that can be isolated from and expanded for re-infusion into each patient. This paper demonstrates a stromal support cell-free in vitro method for the differentiation of T cells from umbilical cord blood hematopoietic stem cells (HSCs). For each single HSC cell input, approximately 5 × 104 T cells were created with an initial five days of HSC expansion and subsequent T cell differentiation over 49 days. When the induced in vitro differentiated T cells were activated by cytokines and anti-CD3/CD28 beads, CD8+ T cell receptor (TCR) γδ+ T cells were preferentially generated and elicited cytotoxic function against ovarian cancer cells in vitro. This process of inducing de novo functional T cells offers a possible strategy to increase T cell yields, simplify manufacturing, and reduce costs with application potential for conversion into chimeric antigen receptor (CAR)-T cells for cancer immunotherapy and for allogeneic transplantation to restore immune competence.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Células-Tronco Hematopoéticas/imunologia , Imunoterapia , Animais , Bovinos , Diferenciação Celular , Linhagem Celular Tumoral , Proliferação de Células , Citotoxicidade Imunológica , Sangue Fetal/citologia , Humanos , Fenótipo
9.
Front Genet ; 12: 638558, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34163519

RESUMO

Integrin-linked kinase (ILK) has been implicated as a molecular driver and mediator in both inflammation and tumorigenesis of the colon. ILK functions as an adaptor and mediator protein linking the extracellular matrix with downstream signaling pathways. ILK is broadly expressed in many human tissues and cells. It is also overexpressed in many cancers, including colorectal cancer (CRC). Inflammation, as evidenced by inflammatory bowel disease (IBD), is one of the highest risk factors for initiating CRC. This has led to the hypothesis that targeting ILK therapeutically could have potential in CRC, as it regulates different cellular processes associated with CRC development and progression as well as inflammation in the colon. A number of studies have indicated an ILK function in senescence, a cellular process that arrests the cell cycle while maintaining active metabolism and transcription. Senescent cells produce different secretions collectively known as the senescence-associated secretory phenotype (SASP). The SASP secretions influence infiltration of different immune cells, either positively for clearing senescent cells or negatively for promoting tumor growth, reflecting the dual role of senescence in cancer. However, a role for ILK in senescence and immunity in CRC remains to be determined. In this review, we discuss the possible role for ILK in senescence and immunity, paying particular attention to the relevance of ILK in CRC. We also examine how activating Toll-like receptors (TLRs) and their agonists in CRC could trigger immune responses against cancer, as a combination therapy with ILK inhibition.

10.
Cells ; 10(5)2021 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-33946954

RESUMO

Natural killer (NK) cells are potent innate immune system effector lymphocytes armed with multiple mechanisms for killing cancer cells. Given the dynamic roles of NK cells in tumor surveillance, they are fast becoming a next-generation tool for adoptive immunotherapy. Many strategies are being employed to increase their number and improve their ability to overcome cancer resistance and the immunosuppressive tumor microenvironment. These include the use of cytokines and synthetic compounds to bolster propagation and killing capacity, targeting immune-function checkpoints, addition of chimeric antigen receptors (CARs) to provide cancer specificity and genetic ablation of inhibitory molecules. The next generation of NK cell products will ideally be readily available as an "off-the-shelf" product and stem cell derived to enable potentially unlimited supply. However, several considerations regarding NK cell source, genetic modification and scale up first need addressing. Understanding NK cell biology and interaction within specific tumor contexts will help identify necessary NK cell modifications and relevant choice of NK cell source. Further enhancement of manufacturing processes will allow for off-the-shelf NK cell immunotherapies to become key components of multifaceted therapeutic strategies for cancer.


Assuntos
Imunoterapia/métodos , Células Matadoras Naturais/imunologia , Neoplasias/terapia , Animais , Humanos , Neoplasias/imunologia
11.
Mol Ther Oncolytics ; 20: 325-341, 2021 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33614914

RESUMO

Chimeric antigen receptor (CAR) T cells have revolutionized blood cancer immunotherapy; however, their efficacy against solid tumors has been limited. A common mechanism of tumor escape from single target therapies is downregulation or mutational loss of the nominal epitope. Targeting multiple antigens may thus improve the effectiveness of CAR immunotherapies. We generated dual CAR-T cells targeting two tumor antigens: TAG-72 (tumor-associated glycoprotein 72) and CD47. TAG-72 is a pan-adenocarcinoma oncofetal antigen, highly expressed in ovarian cancers, with increased expression linked to disease progression. CD47 is ubiquitously overexpressed in multiple tumor types, including ovarian cancer; it is a macrophage "don't eat me" signal. However, CD47 is also expressed on many normal cells. To avoid this component of the dual CAR-T cells killing healthy tissue, we designed a truncated CD47 CAR devoid of intracellular signaling domains. The CD47 CAR facilitates binding to CD47+ cells, increasing the prospect of TAG-72+ cell elimination via the TAG-72 CAR. Furthermore, we could reduce the damage to normal tissue by monomerizing the CD47 CAR. Our results indicate that the co-expression of the TAG-72 CAR and the CD47-truncated monomer CAR on T cells could be an effective, dual CAR-T cell strategy for ovarian cancer, also applicable to other adenocarcinomas.

12.
Lancet Planet Health ; 5(2): e84-e92, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33581070

RESUMO

BACKGROUND: Climate change threatens to undermine the past 50 years of gains in public health. In response, the National Health Service (NHS) in England has been working since 2008 to quantify and reduce its carbon footprint. This Article presents the latest update to its greenhouse gas accounting, identifying interventions for mitigation efforts and describing an approach applicable to other health systems across the world. METHODS: A hybrid model was used to quantify emissions within Scopes 1, 2, and 3 of the Greenhouse Gas Protocol, as well as patient and visitor travel emissions, from 1990 to 2019. This approach complements the broad coverage of top-down economic modelling with the high accuracy of bottom-up data wherever available. Available data were backcasted or forecasted to cover all years. To enable the identification of measures to reduce carbon emissions, results were disaggregated by organisation type. FINDINGS: In 2019, the health service's emissions totalled 25 megatonnes of carbon dioxide equivalent, a reduction of 26% since 1990, and a decrease of 64% in the emissions per inpatient finished admission episode. Of the 2019 footprint, 62% came from the supply chain, 24% from the direct delivery of care, 10% from staff commute and patient and visitor travel, and 4% from private health and care services commissioned by the NHS. INTERPRETATION: This work represents the longest and most comprehensive accounting of national health-care emissions globally, and underscores the importance of incorporating bottom-up data to improve the accuracy of top-down modelling and enabling detailed monitoring of progress as health systems act to reduce emissions. FUNDING: Wellcome Trust.


Assuntos
Pegada de Carbono/estatística & dados numéricos , Mudança Climática , Medicina Estatal/estatística & dados numéricos , Dióxido de Carbono/análise , Atenção à Saúde , Inglaterra , Gases de Efeito Estufa/análise , Setor de Assistência à Saúde , Humanos , Meios de Transporte
13.
Astrobiology ; 20(8): 964-976, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32783564

RESUMO

Measurements of the isotopic abundances in meteoritic amino acids have found enhancements of 2H/H, 15N/14N, and 13C/12C in the amino acids in the meteorites studied. We show that they are consistent with the processing of the constituents of the meteorites by electron antineutrinos that would be expected from a core-collapse supernova or neutron-star merger. Using theoretical electron antineutrino cross-sections, we are able to predict these isotopic ratio variations depending on the time-integrated antineutrino flux at the site where the amino acids were processed.


Assuntos
Aminoácidos/química , Elétrons , Evolução Química , Meio Ambiente Extraterreno/química , Meteoroides , Aminoácidos/isolamento & purificação , Estereoisomerismo
14.
BMC Med Inform Decis Mak ; 19(1): 105, 2019 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-31146731

RESUMO

BACKGROUND: Home monitoring of urine protein is a critical component of disease management in childhood nephrotic syndrome. We describe the development of a novel mobile application, UrApp - Nephrotic Syndrome Manager, to aid disease monitoring. METHODS: UrApp was iteratively developed by a panel of two pediatric nephrologists and three research engineers from May 2017 to October 2018 for Apple iPhones. App features were devised by this expert panel to support urine monitoring and other home care tasks. Each feature and user-app interface element was systematically reviewed by the panel and iteratively redesigned to remove anticipated use issues. The app prototype was then refined based on two rounds of usability testing and semi-structured user interviews with a total of 20 caregivers and adolescent patients. The analytic function of UrApp in providing a camera read of the urine test strip was compared to a standard urinalysis machine using 88 patient urine samples and three iPhones, model versions 6S and 7. Exact agreement and weighted kappa were calculated between the UrApp and urinalysis machine reads. RESULTS: The final UrApp features include: camera read of a urine test strip; analysis of urine protein trends and alerts for new disease relapse/remission; transmission of urine protein results to providers; education materials; and medication reminders. During the second round of UrApp usability testing, all users were able to perform each of the functions without error and all perceived UrApp to be helpful and indicated that they would use UrApp. UrApp camera results had 97% exact agreement and an overall weighted kappa value of 0.91 (95% CI, 0.85-0.97) compared with standard urinalysis machine interpretation. CONCLUSIONS: UrApp was specifically designed to support patients and families living with nephrotic syndrome by supporting disease monitoring and home management tasks. The technically innovative feature that makes this possible is the use of a smartphone camera to read the urine test strip. This novel tool has the potential to improve disease monitoring and reduce management burden.


Assuntos
Aplicações da Informática Médica , Aplicativos Móveis , Monitorização Fisiológica/métodos , Síndrome Nefrótica/urina , Urinálise/métodos , Adolescente , Humanos , Processamento de Imagem Assistida por Computador , Monitorização Fisiológica/instrumentação , Proteínas , Smartphone , Urinálise/instrumentação , Urina/química
15.
Cell Stem Cell ; 24(4): 508-510, 2019 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-30951658

RESUMO

In this issue of Cell Stem Cell, Xu et al. (2019) demonstrate that editing iPSCs' major histocompatibility antigens may potentially provide a small set of universally compatible stem cell lines for therapies. However, these modifications may result in patient minor histocompatibility responses and deficiencies in their T cell response repertoire to infection and cancer.


Assuntos
Células-Tronco Pluripotentes Induzidas , Células-Tronco Pluripotentes , Sistemas CRISPR-Cas , Linhagem Celular , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Humanos
16.
Regen Med ; 14(3): 213-230, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30762487

RESUMO

Aim: To evaluate the efficacy of autologous adipose-derived mesenchymal stem cell (ADMSC) therapy on pain, function and disease modification in knee osteoarthritis. Methods: 30 participants with symptomatic knee osteoarthritis were randomized into three groups. Two treatment groups received intra-articular ADMSC therapy consisting of either a single injection (100 × 106 ADMSCs) or two injections (100 × 106 ADMSCs at baseline and 6 months). The third group served as control and continued conservative management. Results: No serious adverse events were observed. Both treatment groups receiving ADMSCs showed clinically significant pain and functional improvement at completion of follow-up at 12 months. Radiological analysis using the Magnetic Resonance Imaging Osteoarthritis Knee Score indicated modification of disease progression. Conclusion: Autologous ADMSC therapy appears to be a safe and effective therapy for knee osteoarthritis and may have the potential to prevent disease progression. Trial registration number: ACTRN12614000814673.


Assuntos
Tecido Adiposo/citologia , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/citologia , Osteoartrite do Joelho/terapia , Feminino , Humanos , Injeções Intra-Articulares , Masculino , Pessoa de Meia-Idade , Transplante Autólogo , Resultado do Tratamento
17.
Stem Cells Transl Med ; 7(11): 792-805, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30272835

RESUMO

Cell transplantation holds considerable promise for end-stage liver diseases but identifying a suitable, transplantable cell type has been problematic. Here, we describe a novel type of mesenchymal stem cells (MSCs) from human adipose tissue. These cells are different from previously reported MSCs, they are in the euchromatin state with epigenetic multipotency, and express pluripotent markers MYC, KLF4, and GMNN. Most of the genes associated with germ layer specification are modified by H3K4me3 or co-modified by H3K4me3 and H3K27me3. We named this new type of MSCs as adult multipotent adipose-derived stem cells (M-ADSCs). Using a four-step nonviral system, M-ADSCs can be efficiently Induced into hepatocyte like cells with expression of hepatocyte markers, drug metabolizing enzymes and transporters, and the other basic functional properties including albumin (ALB) secretion, glycogen storage, detoxification, low-density lipoprotein intake, and lipids accumulation. In vivo both M-ADSCs-derived hepatoblasts and hepatocytes could form vascularized liver-like tissue, secrete ALB and express metabolic enzymes. Single-cell RNA-seq was used to investigate the important stages in this conversion. M-ADSCs could be converted to a functionally multipotent state during the preinduction stage without undergoing reprogramming process. Our findings provide important insights into mechanisms underlying cell development and conversion. Stem Cells Translational Medicine 2018;7:792-805.


Assuntos
Geminina/metabolismo , Hepatócitos/metabolismo , Fatores de Transcrição Kruppel-Like/metabolismo , Células-Tronco Mesenquimais/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Tecido Adiposo/citologia , Animais , Biomarcadores/metabolismo , Diferenciação Celular , Geminina/genética , Fator 4 Nuclear de Hepatócito/genética , Fator 4 Nuclear de Hepatócito/metabolismo , Hepatócitos/citologia , Humanos , Fator 4 Semelhante a Kruppel , Fatores de Transcrição Kruppel-Like/genética , Fígado/metabolismo , Células-Tronco Mesenquimais/citologia , Camundongos , Camundongos Nus , Proteínas Proto-Oncogênicas c-myc/genética , RNA/química , RNA/isolamento & purificação , RNA/metabolismo , Análise de Sequência de RNA , Análise de Célula Única , Transcriptoma , alfa-Fetoproteínas/genética , alfa-Fetoproteínas/metabolismo
18.
Stem Cells Int ; 2018: 7309201, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30050578

RESUMO

Osteoarthritis is a common condition that causes joint pain and stiffness that affects both humans and dogs. In Australia, allogeneic canine adipose-derived mesenchymal stem cells for therapy have been commercially available since 2010. In this report, we describe the outcome of the treatment of two hundred and three dogs diagnosed with degenerative arthritis with severe chronic pain in joints causing lameness at walk, reduced mobility, and functional disability. Posttreatment assessment data after 10 weeks revealed significant improvement (p < 0.007) of the symptoms: pain reduction, improvement of mobility, and increased daily activity as measured as quality of life score. Ninety percent of young dogs (<9 years) showed excellent improvement in pain and mobility and were able to run and resume normal activity. Sixty percent of older dogs showed good improvement. However, 12% of dogs did not exhibit any change in symptoms; one dog showed worsening of the symptoms. This report provides the support for the safety and efficacies of allogeneic adipose-derived mesenchymal stem cells in a regenerative therapeutic veterinary model.

19.
Sci Rep ; 8(1): 8833, 2018 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-29891867

RESUMO

Magnetochiral phenomena may be responsible for the selection of chiral states of biomolecules in meteoric environments. For example, the Supernova Amino Acid Processing (SNAAP) Model was proposed previously as a possible mode of magnetochiral selection of amino acids by way of the weak interaction in strong magnetic fields. In earlier work, this model was shown to produce an enantiomeric excess (ee) as high as 0.014% for alanine. In this paper we present the results of molecular quantum chemistry calculations from which ees are determined for the α-amino acids plus isovaline and norvaline, which were found to have positive ees in meteorites. Calculations are performed for both isolated and aqueous states. In some cases, the aqueous state was found to produce larger ees reaching values as high as a few percent under plausible conditions.


Assuntos
Aminoácidos/química , Evolução Química , Meio Ambiente Extraterreno , Meteoroides , Origem da Vida , Estereoisomerismo , Campos Magnéticos , Modelos Teóricos
20.
Astrobiology ; 18(2): 190-206, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29160728

RESUMO

Previous work has suggested that the chirality of the amino acids could be established in the magnetic field of a nascent neutron star from a core-collapse supernova or massive collapsar. The magnetic field would orient the 14N nuclei, and the alignment of its nuclear spin with respect to those of the electron antineutrinos emitted from the collapsing star would determine the probability of destruction of the 14N nuclei by interactions with the antineutrinos. Subsequent work estimated the bulk polarization of the 14N nuclei in large rotating meteoroids in such an environment. The present work adds a crucial piece of this model by describing the details by which the selective 14N nuclear destruction would produce molecular chiral selectivity. The effects of the neutrino-induced interactions on the 14N nuclei bound in amino acids polarized in strong magnetic fields are studied. It is shown that electric fields in the reference frame of the nuclei modify the magnetic field at the nucleus, creating nuclear magnetizations that are asymmetric in chirality. The antineutrino cross sections depend on this magnetization, creating a selective destructive effect. The environmental conditions and sites in which such a selection mechanism could occur are discussed. Selective destruction of D-enantiomers results in enantiomeric excesses which may be sufficient to drive subsequent autocatalysis necessary to produce the few-percent enantiomeric excesses found in meteorites and subsequent homochirality. Molecular quantum chemical calculations were performed for alanine, and the chirality-dependent effects studied were included. A preference for left-handed molecules was found, and enantiomeric excesses as high as 0.02% were estimated for molecules in the electromagnetic conditions expected from a core-collapse supernova. Key Words: Amino acids-Supernovae-Antineutrinos-Enantiomeric excess-Chirality. Astrobiology 18, 190-206.


Assuntos
Aminoácidos/química , Eletricidade , Evolução Química , Meio Ambiente Extraterreno/química , Campos Magnéticos , Partículas Elementares , Meteoroides , Modelos Químicos , Nitrogênio/química , Estereoisomerismo
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