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1.
Bone ; 181: 117026, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38325651

RESUMO

Disuse osteoporosis is a prevalent complication among patients afflicted with rheumatoid arthritis (RA). Although reports have shown that the antirheumatic drug iguratimod (IGU) ameliorates osteoporosis in RA patients, details regarding its effects on osteocytes remain unclear. The current study examined the effects of IGU on osteocytes using a mouse model of disuse-induced osteoporosis, the pathology of which crucially involves osteocytes. A reduction in distal femur bone mass was achieved after 3 weeks of hindlimb unloading in mice, which was subsequently reversed by intraperitoneal IGU treatment (30 mg/kg; five times per week). Histology revealed that hindlimb-unloaded (HLU) mice had significantly increased osteoclast number and sclerostin-positive osteocyte rates, which were suppressed by IGU treatment. Moreover, HLU mice exhibited a significant decrease in osteocalcin-positive cells, which was attenuated by IGU treatment. In vitro, IGU suppressed the gene expression of receptor activator of NF-κB ligand (RANKL) and sclerostin in MLO-Y4 and Saos-2 cells, which inhibited osteoclast differentiation of mouse bone marrow cells in cocultures. Although IGU did not affect the nuclear translocation or transcriptional activity of NF-κB, RNA sequencing revealed that IGU downregulated the expression of early growth response protein 1 (EGR1) in osteocytes. HLU mice showed significantly increased EGR1- and tumor necrosis factor alpha (TNFα)-positive osteocyte rates, which were decreased by IGU treatment. EGR1 overexpression enhanced the gene expression of TNFα, RANKL, and sclerostin in osteocytes, which was suppressed by IGU. Contrarily, small interfering RNA-mediated suppression of EGR1 downregulated RANKL and sclerostin gene expression. These findings indicate that IGU inhibits the expression of EGR1, which may downregulate TNFα and consequently RANKL and sclerostin in osteocytes. These mechanisms suggest that IGU could potentially be used as a treatment option for disuse osteoporosis by targeting osteocytes.


Assuntos
Cromonas , Osteoporose , Sulfonamidas , Fator de Necrose Tumoral alfa , Animais , Humanos , Fator de Necrose Tumoral alfa/metabolismo , Osteócitos/metabolismo , Receptor Ativador de Fator Nuclear kappa-B/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Linhagem Celular , Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Proteína 1 de Resposta de Crescimento Precoce/farmacologia , Ligantes , Osteoclastos/metabolismo , NF-kappa B/metabolismo , Osteoporose/tratamento farmacológico , Osteoporose/metabolismo , Ligante RANK/metabolismo
2.
Osteoporos Int ; 35(5): 841-849, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38296866

RESUMO

The impact of ROMO on the width of anabolic windows and the increase in BMD was reduced in the RA group compared to the non-RA group, and this reduction was associated with correlations to RA-related factors. PURPOSE: To investigate the effects of romosozumab (ROMO) in postmenopausal osteoporosis, with and without comorbid rheumatoid arthritis (RA). METHODS: In this retrospective, case-controlled, multicenter study, 171 postmenopausal patients who did not receive oral glucocorticoid, comprising 59 in the RA group and 121 in the non-RA group, received uninterrupted ROMO treatment for 12 months. Propensity score matching was employed to ensure comparability in clinical backgrounds, resulting in 41 patients in each group. Baseline characteristics were as follows: overall (mean age, 76.3 years; T-score of lumbar spine (LS), - 3.0; 45.1% were treatment-naive for osteoporosis); RA group (anti-cyclic citrullinated peptide antibody (ACPA) positivity, 80.5%; titer, 206.2 U/ml; clinical disease activity index (CDAI), 13.6; health assessment questionnaire disability index (HAQ-DI), 0.9). Bone mineral density (BMD) and serum bone turnover markers were monitored over a 12-month period. RESULTS: The rate of increase in the bone formation marker, PINP, and the rates of decrease in the bone resorption marker, TRACP-5b, exhibited a trend toward smaller changes in the RA group compared to the non-RA group, implying a smaller anabolic window. After 12 months, the RA group displayed lower BMD increases in the LS (9.1% vs. 12.6%; P = 0.013) and total hip (2.4% vs. 4.8%; P = 0.025) compared to the non-RA group. Multiple regression analysis in the all RA group (n = 59) for the association between RA-specific factors and 12-month BMD changes revealed negative correlations between ACPA titer and LS BMD and between HAQ-DI and femoral neck BMD. CONCLUSIONS: The efficacy of ROMO may be attenuated by RA-related factors.


Assuntos
Anticorpos Monoclonais , Artrite Reumatoide , Conservadores da Densidade Óssea , Osteoporose Pós-Menopausa , Feminino , Humanos , Idoso , Osteoporose Pós-Menopausa/complicações , Osteoporose Pós-Menopausa/tratamento farmacológico , Estudos de Casos e Controles , Estudos Retrospectivos , Densidade Óssea , Artrite Reumatoide/complicações , Artrite Reumatoide/tratamento farmacológico , Conservadores da Densidade Óssea/farmacologia , Conservadores da Densidade Óssea/uso terapêutico , Fator Reumatoide , Vértebras Lombares
3.
Sci Adv ; 10(3): eadi7203, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38241366

RESUMO

The Hayabusa2 spacecraft delivered samples of the carbonaceous asteroid Ryugu to Earth. Some of the sample particles show evidence of micrometeoroid impacts, which occurred on the asteroid surface. Among those, particles A0067 and A0094 have flat surfaces on which a large number of microcraters and impact melt splashes are observed. Two impact melt splashes and one microcrater were analyzed to unveil the nature of the objects that impacted the asteroid surface. The melt splashes consist mainly of Mg-Fe-rich glassy silicates and Fe-Ni sulfides. The microcrater trapped an impact melt consisting mainly of Mg-Fe-rich glassy silicate, Fe-Ni sulfides, and minor silica-rich glass. These impact melts show a single compositional trend indicating mixing of Ryugu surface materials and impactors having chondritic chemical compositions. The relict impactor in one of the melt splashes shows mineralogical similarity with anhydrous chondritic interplanetary dust particles having a probable cometary origin. The chondritic micrometeoroids probably impacted the Ryugu surface during its residence in a near-Earth orbit.

4.
Artigo em Inglês | MEDLINE | ID: mdl-38252703

RESUMO

This study evaluated reverse V-shaped osteotomy for ankylosing rocker-bottom foot deformity in patients with rheumatoid arthritis. We experienced 3 feet: rheumatoid rocker-bottom deformities with painful and/or infectious bony prominence towards the bottom of the foot, treated with a reverse V-shaped osteotomy in the mid-hindfoot. In all three cases, significant correction was achieved with restoration of the medial longitudinal arch, and improvement in clinical scores was confirmed. Reverse V-shaped osteotomy has the potential to be a useful and definitive procedure for ankylosing rocker-bottom deformity in patients with rheumatoid arthritis.

5.
Mod Rheumatol ; 2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38252306

RESUMO

BACKGROUND: According to the conventional postoperative procedure after total ankle arthroplasty (TAA) against end-stage osteoarthritis (OA) and rheumatoid arthritis (RA), mobilization and weight-bearing is currently started after completion of wound healing. Recently, early mobilization for dorsiflexion after TAA with modified antero-lateral approach was reported to be feasible and safe. To investigate the further possibility of expediting rehabilitation, this study evaluated the feasibility and safety of early full weight-bearing and gait exercise after cemented TAA utilizing a modified antero-lateral approach. MATERIALS AND METHODS: This retrospective, observational study investigated 23 consecutive ankles (OA: 14 ankles, RA: 9 ankles) that had received cemented TAA with a modified antero-lateral approach. These ankles were divided into three groups [1. conventional postoperative protocol: 8 ankles, 2. early dorsiflexion protocol: 7 ankles, 3. early dorsiflexion+full weight-bearing protocol: 8 ankles]. In group 3, after early dorsiflexion mobilization (day 3), full weight-bearing/gait exercise was started from 7 days after surgery (10 days after if malleolar osteotomy was added). Postoperative wound complications were observed and recorded. Number of days for hospitalization was also evaluated. Range of motion (ROM) of dorsiflexion/plantar flexion was measured. Patients also completed a self-administered foot evaluation questionnaire (SAFE-Q) and the scale of Japanese Society for Surgery of the Foot (JSSF) ankle/hindfoot score preoperatively and at final follow-up. RESULTS: No postoperative complications related to wound healing were observed even after early full weight-bearing and gait exercise. Days for hospitalization was significantly shortened in early full weight-bearing and gait exercise group (group 3) from 35-38 days to 24 days. ROM for both dorsiflexion and plantar flexion significantly increased in group 3, furthermore all indices of SAFE-Q score also showed stronger significant improvement in group 3. JSSF score improved significantly after TAA in all groups. CONCLUSION: Within this small number of cases, early full weight-bearing and gait exercise from 7 days after cemented TAA was feasible and safe with the modified antero-lateral approach. Combination of early dorsiflexion mobilization and weight-bearing/gait exercise contributed to shortening the hospitalization day, and improving ROM for both dorsiflexion and plantar flexion after surgery. Innovations in postoperative procedures for rehabilitation after TAA can be expected.

6.
Hypertens Res ; 47(1): 157-167, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37717115

RESUMO

Primary aldosteronism (PA) is typically managed with mineralocorticoid receptor antagonists (MRAs) barring adrenalectomy. The efficacy of esaxerenone, a nonsteroidal MRA, were explored in patients with PA. Various parameters such as the urinary albumin to creatinine ratio (UACR) and serum levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) were evaluated in 25 PA patients before and 3 and 6 months after esaxerenone treatment. Systolic and diastolic blood pressure (BP), and the estimated glomerular filtration rate decreased after treatment, while serum levels of potassium and active renin increased. Significant reductions were observed in UACR 3 and 6 months after treatment. A significant decrease in NT-proBNP was evident at 6 months but not 3 months after treatment. Correlation analysis indicated that the reductions in BP and UACR at 3 months were independent of estimated daily salt intake. Furthermore, the effect of esaxerenone treatment on lowering UACR and NT-proBNP levels was independent of BP reduction. Responders whose systolic BP decreased 6 months after esaxerenone treatment by more than 10 mmHg compared to pretreatment had higher pretreatment NT-proBNP and similar UACR before and after treatment when compared with nonresponders. Esaxerenone improved mental, physical, and social quality of life (QOL) 6 months after treatment compared to healthy controls and increased over time. No patients discontinued treatment due to severe hyperkalemia or renal dysfunction. In conclusion, esaxerenone is a safe and effective MRA for PA treatment, offering significant benefits in terms of hypertension, albuminuria, NT-proBNP levels, and QOL improvement. Esaxerenone effectively lowers BP, UACR, and serum levels of NT-proBNP independent of dietary salt intake in mild PA patients. ARC active renin concentration, DBP diastolic blood pressure, MR mineralocorticoid receptor, MRA mineralocorticoid receptor antagonist, NT-proBNP N-terminal pro-brain natriuretic peptide, PA primary aldosteronism, QOL quality of life, SBP systolic blood pressure, SF-36 Medical Outcomes Study 36-Item Short-Form Health Survey, UACR urinary albumin to creatinine ratio.


Assuntos
Hiperaldosteronismo , Peptídeo Natriurético Encefálico , Humanos , Pressão Sanguínea , Qualidade de Vida , Renina , Creatinina , Albuminas/farmacologia , Hiperaldosteronismo/tratamento farmacológico , Antagonistas de Receptores de Mineralocorticoides/uso terapêutico , Antagonistas de Receptores de Mineralocorticoides/farmacologia
7.
Sci Adv ; 9(49): eadi3789, 2023 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-38055820

RESUMO

The carbonaceous asteroid Ryugu has been explored by the Hayabusa2 spacecraft to elucidate the actual nature of hydrous asteroids. Laboratory analyses revealed that the samples from Ryugu are comparable to unheated CI carbonaceous chondrites; however, reflectance spectra of Ryugu samples and CIs do not coincide. Here, we demonstrate that Ryugu sample spectra are reproduced by heating Orgueil CI chondrite at 300°C under reducing conditions, which caused dehydration of terrestrial weathering products and reduction of iron in phyllosilicates. Terrestrial weathering of CIs accounts for the spectral differences between Ryugu sample and CIs, which is more severe than space weathering that likely explains those between asteroid Ryugu and the collected samples. Previous assignments of CI chondrite parent bodies, i.e., chemically most primitive objects in the solar system, are based on the spectra of CI chondrites. This study indicates that actual spectra of CI parent bodies are much darker and flatter at ultraviolet to visible wavelengths than the spectra of CI chondrites.

8.
Science ; 382(6677): 1411-1416, 2023 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-38127762

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) contain ≲20% of the carbon in the interstellar medium. They are potentially produced in circumstellar environments (at temperatures ≳1000 kelvin), by reactions within cold (~10 kelvin) interstellar clouds, or by processing of carbon-rich dust grains. We report isotopic properties of PAHs extracted from samples of the asteroid Ryugu and the meteorite Murchison. The doubly-13C substituted compositions (Δ2×13C values) of the PAHs naphthalene, fluoranthene, and pyrene are 9 to 51‰ higher than values expected for a stochastic distribution of isotopes. The Δ2×13C values are higher than expected if the PAHs formed in a circumstellar environment, but consistent with formation in the interstellar medium. By contrast, the PAHs phenanthrene and anthracene in Ryugu samples have Δ2×13C values consistent with formation by higher-temperature reactions.

9.
Cureus ; 15(9): e45812, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37876385

RESUMO

We present the case of a patient with rheumatoid arthritis who underwent talonavicular joint fusion using an autologous calcaneal bone graft. At the same time, the bony defect at the harvest site was supplemented with ReBOSSIS-J® [70% ß-TCP and 30% poly(L-lactide-co-glycolide)](ORTHOREBIRTH Co. Ltd., Kanagawa, Japan), a synthetic bioresorbable bone void filler for the repair of bony defects with handling characteristics similar to a cotton ball. Material resorption and new bone formation had already started one week postoperatively. Transposition to host bone trabeculae was almost completed by 26 days postoperatively. Very rapid reactive graft resorption, repair with new bone formation, and subsequently, most of the transformation to host bone trabeculae were confirmed. ReBOSSIS-J® appears feasible to contribute to early heel weight-bearing exercise after foot or ankle surgery. In addition, preventing the fracture at the harvesting site of the calcaneal bone graft can also be expected.

10.
Nat Commun ; 14(1): 6525, 2023 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-37845217

RESUMO

The sample from the near-Earth carbonaceous asteroid (162173) Ryugu is analyzed in the context of carbonaceous meteorites soluble organic matter. The analysis of soluble molecules of samples collected by the Hayabusa2 spacecraft shines light on an extremely high molecular diversity on the C-type asteroid. Sequential solvent extracts of increasing polarity of Ryugu samples are analyzed using mass spectrometry with complementary ionization methods and structural information confirmed by nuclear magnetic resonance spectroscopy. Here we show a continuum in the molecular size and polarity, and no organomagnesium molecules are detected, reflecting a low temperature and water-rich environment on the parent body approving earlier mineralogical and chemical data. High abundance of sulfidic and nitrogen rich compounds as well as high abundance of ammonium ions confirm the water processing. Polycyclic aromatic hydrocarbons are also detected in a structural continuum of carbon saturations and oxidations, implying multiple origins of the observed organic complexity, thus involving generic processes such as earlier carbonization and serpentinization with successive low temperature aqueous alteration.

11.
Nat Commun ; 14(1): 5284, 2023 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-37723151

RESUMO

Samples from the carbonaceous asteroid (162173) Ryugu provide information on the chemical evolution of organic molecules in the early solar system. Here we show the element partitioning of the major component ions by sequential extractions of salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition of the primitive asteroid. Sodium is the dominant electrolyte of the salt fraction extract. Anions and NH4+ are more abundant in the salt fraction than in the carbonate and phyllosilicate fractions, with molar concentrations in the order SO42- > Cl- > S2O32- > NO3- > NH4+. The salt fraction extracts contain anionic soluble sulfur-bearing species such as Sn-polythionic acids (n < 6), Cn-alkylsulfonates, alkylthiosulfonates, hydroxyalkylsulfonates, and hydroxyalkylthiosulfonates (n < 7). The sulfur-bearing soluble compounds may have driven the molecular evolution of prebiotic organic material transforming simple organic molecules into hydrophilic, amphiphilic, and refractory S allotropes.

12.
Mod Rheumatol Case Rep ; 8(1): 210-214, 2023 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-37542432

RESUMO

We present a case of a patient who underwent a modified scarf osteotomy and tumour excision based on a preoperative diagnosis of hallux valgus deformity and accompanying bursitis. Subsequent histopathological examination revealed that the tumour was an angioleiomyoma. While tumours around the first metatarsophalangeal (MTP) joint are typically associated with gouty nodules, infections, or swollen bursa (bursitis) in patients with hallux valgus deformity, the occurrence of soft tissue tumours in this area is rare. Moreover, angioleiomyoma is an even rarer form of soft tissue tumour and is seldom suspected prior to resection. To our knowledge, there have been no reports of angioleiomyoma arising in the first MTP joint. However, it is important to consider the possibility of an atypical tumour in cases where soft tissue masses are present, even in patients with hallux valgus deformity, and to perform at least imaging tests such as ultrasound and magnetic resonance imaging before surgery. This prospect should always be kept in mind.


Assuntos
Angiomioma , Bursite , Hallux Valgus , Articulação Metatarsofalângica , Humanos , Hallux Valgus/diagnóstico , Hallux Valgus/etiologia , Hallux Valgus/cirurgia , Angiomioma/complicações , Radiografia , Articulação Metatarsofalângica/cirurgia , Bursite/complicações
13.
Sci Rep ; 13(1): 14096, 2023 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-37644091

RESUMO

In the samples collected from the asteroid Ryugu, magnetite displays natural remanent magnetization due to nebular magnetic field, whereas contemporaneously grown iron sulfide does not display stable remanent magnetization. To clarify this counterintuitive feature, we observed their nanoscale magnetic domain structures using electron holography and found that framboidal magnetites have an external magnetic field of 300 A m-1, similar to the bulk value, and its magnetic stability was enhanced by interactions with neighboring magnetites, permitting a disk magnetic field to be recorded. Micrometer-sized pyrrhotite showed a multidomain magnetic structure that was unable to retain natural remanent magnetization over a long time due to short relaxation time of magnetic-domain-wall movement, whereas submicron-sized sulfides formed a nonmagnetic phase. These results show that both magnetite and sulfide could have formed simultaneously during the aqueous alteration in the parent body of the asteroid Ryugu.

14.
Cureus ; 15(6): e40441, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37456439

RESUMO

Exposure of the tibialis anterior (TA) tendon with wound dehiscence after total ankle arthroplasty (TAA) with the anterior approach is a problematic complication, especially in rheumatoid arthritis (RA) patients. Once the TA tendon is exposed, the duration of wound healing is prolonged, and it could be a risk factor for deep infection. Thus, early resection of the TA tendon was evaluated for tendon exposure with wound dehiscence after TAA in RA patients. In this case report, three rheumatoid ankles that showed wound dehiscence with exposure of the TA tendon after TAA with the anterior approach are presented. Early resection of the TA tendon and debridement under local anesthesia were performed within two days after wound dehiscence. In all cases, wound healing was completed within two weeks after the treatment. Drop foot was not seen in any patients, and there was no difference between the pre and postoperative (1 year after TAA) range of dorsiflexion. Muscle strength for ankle dorsiflexion was also maintained. In conclusion, early resection of the TA tendon appears to be a useful option for undesirable tendon exposure with wound dehiscence to prevent deep infection and prolonged wound healing after total ankle arthroplasty in RA patients.

15.
J Orthop Sci ; 2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-37263899

RESUMO

BACKGROUND: According to the conventional postoperative procedure after total ankle arthroplasty (TAA), mobilization is currently started after completion of wound healing. To investigate the possibility of expediting rehabilitation, this study evaluated the feasibility and safety of early mobilization of dorsiflexion after cemented TAA utilizing a modified antero-lateral approach. MATERIALS AND METHODS: This retrospective, observational study investigated 14 consecutive ankles that had received cemented TAA. Mobilization of dorsiflexion was started from 3 days after surgery. Postoperative wound complications including blister formation, eschar formation, wound dehiscence, peri-incisional decreased sensation were observed and recorded. Range of motion (ROM) of dorsiflexion/plantar flexion was measured. Patients also completed a self-administered foot evaluation questionnaire (SAFE-Q) and the scale of Japanese Society for Surgery of the Foot (JSSF) ankle/hindfoot score preoperatively and at final follow-up. RESULTS: No postoperative complications related to wound healing were observed. ROM for dorsiflexion, SAFE-Q score, and JSSF score improved significantly after TAA. CONCLUSION: Within this small number of cases, early mobilization of dorsiflexion from 3 days after cemented TAA was feasible and safe with the modified antero-lateral approach. Innovations in postoperative procedures for rehabilitation after TAA can be expected.

16.
Nat Commun ; 14(1): 1292, 2023 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-36944653

RESUMO

The pristine sample from the near-Earth carbonaceous asteroid (162173) Ryugu collected by the Hayabusa2 spacecraft enabled us to analyze the pristine extraterrestrial material without uncontrolled exposure to the Earth's atmosphere and biosphere. The initial analysis team for the soluble organic matter reported the detection of wide variety of organic molecules including racemic amino acids in the Ryugu samples. Here we report the detection of uracil, one of the four nucleobases in ribonucleic acid, in aqueous extracts from Ryugu samples. In addition, nicotinic acid (niacin, a B3 vitamer), its derivatives, and imidazoles were detected in search for nitrogen heterocyclic molecules. The observed difference in the concentration of uracil between A0106 and C0107 may be related to the possible differences in the degree of alteration induced by energetic particles such as ultraviolet photons and cosmic rays. The present study strongly suggests that such molecules of prebiotic interest commonly formed in carbonaceous asteroids including Ryugu and were delivered to the early Earth.

17.
Nat Commun ; 14(1): 532, 2023 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-36797235

RESUMO

Chondrule-like objects and Ca-Al-rich inclusions (CAIs) are discovered in the retuned samples from asteroid Ryugu. Here we report results of oxygen isotope, mineralogical, and compositional analysis of the chondrule-like objects and CAIs. Three chondrule-like objects dominated by Mg-rich olivine are 16O-rich and -poor with Δ17O (=δ17O - 0.52 × Î´18O) values of ~ -23‰ and ~ -3‰, resembling what has been proposed as early generations of chondrules. The 16O-rich objects are likely to be melted amoeboid olivine aggregates that escaped from incorporation into 16O-poor chondrule precursor dust. Two CAIs composed of refractory minerals are 16O-rich with Δ17O of ~ -23‰ and possibly as old as the oldest CAIs. The discovered objects (<30 µm) are as small as those from comets, suggesting radial transport favoring smaller objects from the inner solar nebula to the formation location of the Ryugu original parent body, which is farther from the Sun and scarce in chondrules. The transported objects may have been mostly destroyed during aqueous alteration in the Ryugu parent body.

18.
Science ; 379(6634): eabn9057, 2023 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-36821663

RESUMO

Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugu's parent body.

19.
Science ; 379(6634): eabn9033, 2023 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-36821691

RESUMO

The Hayabusa2 spacecraft collected samples from the surface of the carbonaceous near-Earth asteroid (162173) Ryugu and brought them to Earth. The samples were expected to contain organic molecules, which record processes that occurred in the early Solar System. We analyzed organic molecules extracted from the Ryugu surface samples. We identified a variety of molecules containing the atoms CHNOS, formed by methylation, hydration, hydroxylation, and sulfurization reactions. Amino acids, aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-heterocyclic compounds were detected, which had properties consistent with an abiotic origin. These compounds likely arose from an aqueous reaction on Ryugu's parent body and are similar to the organics in Ivuna-type meteorites. These molecules can survive on the surfaces of asteroids and be transported throughout the Solar System.

20.
Nat Astron ; 7(2): 170-181, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36845884

RESUMO

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (-OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.

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