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This research aimed to clarify the effects of exogenously applied chitosan on the physiological characteristics, antioxidant activities, and Cd accumulation of wheat (Triticum aestivum L.) seedlings under cadmium (Cd) stress and to identify the key indicators based on the partial least squares model. The wheat variety studied was Bainong207 (BN207), and Cd-stress was achieved by growing seedlings in a hydroponic culture experiment with 10 and 25 µmol·L-1 Cd2+ added to the culture solution. It was found that both Cd-stress at 10 and 25 µmol·L-1 significantly inhibited the chlorophyll content, photosynthesis, and biomass accumulation of wheat seedlings. Seedling roots became shorter and thicker, and the lateral roots decreased under Cd-stress. The Cd-stress also increased H2O2 and MDA accumulation and the degree of cell membrane lipid peroxidation and affected the activities of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD). Under Cd stress, exogenous chitosan decreased the Cd content in the aboveground and underground parts of wheat by 13.22 %-21.63 % and 7.92 %-28.32 % and reduced Cd accumulation in the aboveground and underground parts by 5.37 %-6.71 % and 1.91 %-4.09 %, respectively. Whereas exogenous chitosan application significantly reduced the content of H2O2 in roots and aboveground parts of wheat by 38.21 %-47.46 % and 45.81 %-55.73 % and MDA content by 37.65 %-48.12 % and 29.87 %-32.51 %, it increased the activities of SOD and POD in roots by 2.78 %-5.61 % and 13.81 %-18.33 %, respectively. In summary, exogenous chitosan can improve the photosynthetic characteristics and antioxidant enzyme activities of wheat seedlings under Cd stress, reduce the content and accumulation of Cd in the root and aboveground parts of wheat, and alleviate the damage of lipid peroxidation to the cell membrane. All of these results provide the basal data for the application of exogenous chitosan to alleviate Cd toxicity to wheat seedlings.
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Antioxidantes , Cadmio , Quitosano , Plantones , Triticum , Triticum/metabolismo , Triticum/efectos de los fármacos , Triticum/crecimiento & desarrollo , Cadmio/toxicidad , Cadmio/metabolismo , Quitosano/metabolismo , Quitosano/farmacología , Plantones/efectos de los fármacos , Plantones/metabolismo , Antioxidantes/metabolismo , Estrés Fisiológico/efectos de los fármacos , Superóxido Dismutasa/metabolismo , Contaminantes del Suelo/toxicidad , Contaminantes del Suelo/metabolismoRESUMEN
BACKGROUND: The clinical outcomes of chemotherapy (CT) for the treatment of metastatic triple-negative (TN) and hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC) have proven to be disappointing. The phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway, a tumor-promoting signaling cascade frequently mutated in breast cancer (BC), has been implicated in chemoresistance. In this study, our objective is to investigate the efficacy and safety of combining everolimus with chemotherapy in mBC patients exhibiting mutations in the PI3K/AKT/mTOR pathway. METHODS: We conducted a retrospective analysis to characterize the efficacy, safety, and their association with clinical and molecular characteristics of metastatic lesions in 14 patients with HER2- mBC. These patients harbored at least one altered member of the PI3K/AKT/mTOR signaling pathway and were treated with a combination of a chemotherapy agent and the mTOR inhibitor everolimus (CT+EVE). RESULTS: The majority of patients belonged to the triple-negative (TN) subtype (9/14, 64.3%), having already undergone 2 lines of chemotherapy (CT) in the metastatic setting (11, 78.6%). These patients carried altered phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and were administered a vinorelbine-containing regimen (10, 71.4%). The objective response rate (ORR) was 42.9%, with a disease control rate of 92.9%. The median progression-free survival (PFS) and overall survival (OS) were 5.9 (95% confidence interval (CI): 4.9-13.6) months and 14.3 (95% CI: 8.5-not reached (NR)) months, respectively. Patients with fewer prior treatment lines tended to exhibit longer PFS. OS, PFS, and ORR were comparable between hormone receptor-positive (HR+) and triple-negative breast cancer (TNBC) patients, but numerical improvements were noted in patients with a single PI3K pathway alteration compared to those with more than one alteration. Genomic alterations that surfaced upon progression on CT+EVE included cyclin dependent kinase 4 (CDK4) and epidermal growth factor receptor (EGFR) amplification, as well as neurofibromin 1 (NF1) mutation, suggesting potential mechanisms of acquired resistance. An analysis of adverse events indicated manageable toxicities. CONCLUSIONS: The findings of this study suggest both activity and safety for the combination of chemotherapy and the mTOR inhibitor everolimus (CT+EVE) in patients with HER2- mBC who have alterations in the PI3K pathway, particularly those who have received fewer prior chemotherapy. However, it is crucial to note that large-scale, randomized control studies are warranted to more comprehensively characterize the efficacy and safety of this combination therapy.
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Neoplasias de la Mama , Everolimus , Humanos , Femenino , Everolimus/uso terapéutico , Neoplasias de la Mama/patología , Proteínas Proto-Oncogénicas c-akt/uso terapéutico , Fosfatidilinositol 3-Quinasas , Estudios Retrospectivos , Receptor ErbB-2/metabolismo , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Serina-Treonina Quinasas TORRESUMEN
Nickel-catalyzed carbonylation of alkenes is a stereoselective and regioselective method for the synthesis of amide compounds. Theoretical predictions with density functional theory calculations revealed the mechanism and origin of stereoselectivity and regioselectivity for the nickel-catalyzed carbonylation of norbornene. The carbonylation reaction proceeds through oxidative addition, migration insertion of alkenes, and subsequent reduction elimination to afford cis-carbonylation product. The C-N bond activation of amides is unfavorable because the oxidative addition ability of the C-C bond is stronger than that of the C-N bond. The determining step of stereoselectivity is the migratory insertion of the strained olefin. The structural analysis shows that steroselectivity is controlled by the steric hindrance of methyl groups to olefins and substituents to IMes in ligands.
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This research aimed to clarify the mitigative effect of exogenously applied rare earth element cerium ï¼Ceï¼ on the growthï¼ zinc ï¼Znï¼ accumulationï¼ and physiological characteristics of wheat ï¼Triticum aestivum L.ï¼ seedlings under Zn stress. The wheat variety studied was Bainong307 ï¼BN307ï¼ï¼ and Zn stress was achieved by growing seedlings in a hydroponic culture experiment with 500 µmol·L-1 Zn2 + added to the culture solution. It was found that Zn stress at 500 µmol·L-1 significantly inhibited the chlorophyll contentï¼ photosynthesisï¼ and biomass accumulation of wheat seedlings. Seedling roots became shorter and thickerï¼ and the lateral roots decreased under Zn stress. The Zn stress also increased MDA accumulation and the degree of cell membrane lipid peroxidation and reduced soluble protein contents and the activities of antioxidant enzymes such as superoxide dismutase ï¼SODï¼ï¼ catalase ï¼CATï¼ï¼ and ascorbate peroxidase ï¼APXï¼. On the contraryï¼ exogenous Ce decreased the adsorption and transport of Zn by the root system and alleviated the damage of Zn stress to wheat seedlings. Specificallyï¼ the increase in chlorophyll content ï¼chlorophyll aï¼ chlorophyll bï¼ and total chlorophyllï¼ and photosynthetic parametersï¼ the enhancement of antioxidant enzymes activities and soluble protein levelsï¼ and the reduction in MDA content and the damage of lipid peroxidation to the cell membrane were all driven by exogenous Ceï¼ which ultimately led to the increase in dry matter biomass of the root system and shoot. In summaryï¼ these results provide basic data for the application of exogenous Ce to alleviate Zn toxicity to plants.
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Cerio , Zinc , Zinc/metabolismo , Antioxidantes/metabolismo , Plantones , Triticum , Cerio/metabolismo , Cerio/farmacología , Clorofila A , Superóxido Dismutasa/metabolismo , Clorofila , Estrés OxidativoRESUMEN
BACKGROUND: Type 2 diabetes (T2D) is associated with an increased risk of dementia and early features may become evident even in mid-life. Characterizing these early features comprehensively requires multiple measurement modalities and careful selection of participants with and without T2D. OBJECTIVE: We conducted a cross-sectional multimodal imaging study of T2D-discordant twins in late mid-life to provide insights into underlying mechanisms. METHODS: Measurements included computerized cognitive battery, brain MRI (including arterial spin labelling, diffusion tensor, resting state functional), fluorodeoxyglucose (FDG)-PET, and retinal optical coherence tomography. RESULTS: There were 23 pairs, mean age 63.7 (±6.1) years. In global analyses, T2D was associated with poorer attention (ß=â-0.45, p <0.001) and with reduced FDG uptake (ß=â-5.04, pâ=â0.02), but not with cortical thickness (pâ=â0.71), total brain volume (pâ=â0.51), fractional anisotropy (pâ=â0.15), mean diffusivity (pâ=â0.34), or resting state activity (pâ=â0.4). Higher FDG uptake was associated with better attention (ß=â3.19, pâ=â0.01) but not with other cognitive domains. In regional analyses, T2D was associated with lower accumbens volume (ß=â-44, pâ=â0.0004) which was in turn associated with poorer attention. CONCLUSION: T2D-related brain dysfunction in mid-life manifests as attentional loss accompanied by evidence of subtle neurodegeneration and global reduction in cerebral metabolism, in the absence of overt cerebrovascular disease.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Diabetes Mellitus Tipo 2 , Humanos , Enfermedad de Alzheimer/metabolismo , Diabetes Mellitus Tipo 2/complicaciones , Fluorodesoxiglucosa F18/metabolismo , Estudios Transversales , Encéfalo/diagnóstico por imagen , Encéfalo/metabolismo , Imagen por Resonancia Magnética , Tomografía de Emisión de Positrones/métodos , Perfusión , Biomarcadores/metabolismo , Disfunción Cognitiva/metabolismoRESUMEN
A series of cyclometalated C,N-chelate half-sandwich ruthenium complexes based on N-heterocyclic ligands were prepared through a simple route with good yields. These air- and moisture-stable cyclometalated ruthenium complexes showed excellent catalytic efficiency in phenoxy carbonylation of aryl halides with phenyl formate derivatives as a CO source and phenol as a coupling partner under air. Ester products were obtained with high yields at room temperature and without the need for an inert atmosphere. The excellent catalytic activity, broad substrate range, and mild reaction conditions made this catalytic system potential for industrial production. In addition, DFT study has been carried out to elaborate the possible mechanism of this Ru-catalyzed reaction.
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The Ni-catalyzed alkylboration of endocyclic olefins is a stereo- and regioselective approach for the synthesis of boron-containing compounds. We report a detailed density functional theory (DFT) study to elucidate the mechanism and origins of the stereo-, chemo-, and regioselectivity of alkylboration of endocyclic olefins enabled by nickel catalysis. The alkylboration proceeds via the migratory insertion of alkenes, ß-H elimination of the Ni(II) complex, subsequent migratory insertion leading to a new Ni(II) complex, combined with an alkyl radical, and reductive eliminations. The electronic effects of the endocyclic olefins synergistically control the regioselectivity toward the C1- and C2-position boration. In C1-position boration, a more electron-deficient carbon atom tends to combine with an electron-rich -Bpin group and leads to C1-position boration products. The stereoselectivity is influenced by the solvent effect, and the interaction between the substrate and Ni-catalyzed groups, the low-polarity solvent 1,4-dioxane, and a favorable steric hindrance effect result in the cis-alkylboration product. Chemoselectivity toward 1,3-alkylboration results from the steric hindrance effects of the -Bpin group.
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Sharing in embryology and function between the eye and brain has led to interest in whether assessments of the eye reflect brain changes seen in neurodegeneration. We aimed to examine the associations between measures of retinal layer thickness using optical coherence tomography (OCT) and multimodal measures of brain structure and function. Using a convenient sample of twins discordant for type 2 diabetes, we performed cognitive testing, structural brain MRI (tissue volumetry), diffusion tensor imaging (white matter microstructure), and arterial spin labelling (cerebral blood flow). OCT images were recorded and retinal thickness maps generated. We used mixed level modelling to examine the relationship between retinal layer thicknesses and brain measures. We enrolled 35 people (18 pairs, mean age 63.8 years, 63% female). Ganglion cell layer thickness was positively associated with memory, speed, gray matter volume, and altered mean diffusivity. Ganglion cell layer thickness was strongly positively associated with regional cerebral blood flow. We found only a limited number of associations between other retinal layer thickness and measures of brain structure or function. Ganglion cell layer thickness showed consistent associations with a range of brain measures suggesting it may have utility as a marker for future dementia risk.
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Diabetes Mellitus Tipo 2 , Tomografía de Coherencia Óptica , Cognición , Imagen de Difusión Tensora , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neuroimagen , Retina/diagnóstico por imagen , Tomografía de Coherencia Óptica/métodosRESUMEN
IMPORTANCE: Quantifying severity of complications in rhegmatogenous retinal detachment (RRD) surgical trials is needed. A consensus classification system will help surgeons to more effectively compare harms of different surgical techniques. OBJECTIVE: To develop a new consensus-based classification to quantify severity of complications of RRD surgery. DESIGN, SETTING, AND PARTICIPANTS: A comprehensive list of complications was developed followed by a Delphi consensus survey of international vitreoretinal surgeons. The survey was conducted in 17 countries in mainland Europe, the United Kingdom, the United States, Asia, South Africa, and Australia. Seventy vitreoretinal surgeons were invited to take part in the Delphi survey; 45 agreed to participate. Participants were selected through boards/members lists of retinal societies. Data were analyzed between April 2019 and August 2019. MAIN OUTCOMES AND MEASURES: Consensus-derived classification of complications of RRD surgery, according to their severity. RESULTS: Forty-three of 45 vitreoretinal surgeons who agreed to participate in the Delphi survey completed round 1 (96%); all but 1 (98%) completed round 2. Consensus was reached for 96% of the 84 complications assessed. Examples of complications classified as least severe (graded 1) included subconjunctival hemorrhage and chemosis while those classified as most severe included endophthalmitis and sympathetic ophthalmia (graded 9) and phthisis (graded 10). CONCLUSIONS AND RELEVANCE: We propose a new classification for quantifying severity of surgical complications based on an international consensus of vitreoretinal surgeons to quantify harm and improve the reporting of complications of RRD surgery.
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Oftalmólogos , Desprendimiento de Retina , Humanos , Retina , Desprendimiento de Retina/etiología , Desprendimiento de Retina/cirugía , Estudios Retrospectivos , Reino Unido , Vitrectomía/métodosRESUMEN
IMPORTANCE: Knowledge on the frequency and severity of complications in surgical trials for rhegmatogenous retinal detachment (RRD) is essential to determine whether surgical procedures are developed and compared adequately, taking into account not only efficacy but also harms. OBJECTIVE: To review standards of reporting of complications in recent randomized clinical trials of RRD surgery. EVIDENCE REVIEW: This systematic review included randomized clinical trials on RRD surgery published between January 2008 and January 2021 in Embase, MEDLINE, and Web of Science Core Collection databases. Titles, abstracts, and full-text articles retrieved were reviewed for eligibility by 2 independent authors. Eligible studies were evaluated against checklist items from the Consolidated Standards of Reporting Trials Extension for Harms criteria by 2 independent authors, and discrepancies were resolved by discussion with a third author. FINDINGS: Fifty studies were included. The median number of checklist items fulfilled was 8 (range, 0-15), of a possible total of 18. Frequently reported items were discussions balanced with regard to efficacy and adverse events (42 studies [84%]) and inclusions of harm-associated timing of data collection (41 studies [82%]). The least frequently reported items were distinctions between expected and unexpected adverse events (1 study [2%]) and mentions of the use of a validated instrument to report adverse event severity (4 studies [8%]). Frequency of complications was commonly reported (29 studies [58%]) in contrast with complication severity (10 studies [20%]). CONCLUSIONS AND RELEVANCE: This review suggests that severity of complications of RRD surgery has been infrequently quantified and reported in randomized clinical trials and potentially represents an important area of improvement in future RRD surgical trials.
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INTRODUCTION/BACKGROUND: The purpose of this study was to compare the grip strength values obtained under 4 postures, and to identify the position providing the maximum grip strength value. We also explored the effects of different body positions on grip strength measurements and the significance of the selection of measurement position for guiding the screening and diagnosis of sarcopenia. METHODOLOGY: A total of 764 people (409 males and 355 females) participated in this study. Grip strength was measured in 4 positions: (1) standing with the elbow fully extended; (2) standing with arms raised; (3) sitting with the elbow flexed 90°; and (4) sitting with the elbow extended. Multiple linear regression model was used to compare the grip strength measurements obtained from these 4 positions by each hand when considering the influence of age, gender, body mass index, and other factors. RESULTS: Both male and female grip strength values in the standing position with the elbow fully extended were significantly greater than those in other positions. In addition, the grip strength measured by standing posture was generally greater than measured by sitting posture. In contrast, grip strength values in the 2 sitting positions did not differ significantly. The grip strength of men was generally greater than that of women. CONCLUSIONS: The findings reveal that grip strength measured while standing with the elbow fully extended is greater than that measured while sitting, which is the posture currently recommended in clinical practice. Clinicians and researchers should choose the appropriate and optimal postures to measure grip strength.
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Mano , Postura , Índice de Masa Corporal , Codo , Femenino , Fuerza de la Mano , Humanos , MasculinoRESUMEN
Rhodium-catalyzed alkenylation of allylbenzene derivatives via C-C bond activation provides an unprecedented access to alkenylation products with remarkable regioselectivities. Using DFT calculations, we elucidate the reaction mechanism and the origins of the regioselectivity.
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OBJECTIVE: To explore the effect of bone morphogenetic protein 4(BMP4) on the cell cycle and apoptosis of hemaropoictic stem and progenitor cells (HSPC) in conditions of 5-fluorouracil (5-FU)-inducing bone marrow suppression and stress hemogenesis, and its possible mechanism. METHODS: The C57BL transgenic mice with BMP4 overexpression were established and were enrolled in transgenic group (BMP4 group), at the same time the wild type mice matching in age, sex and body weight were selected and were enrolled in control group (WT group). The bone marrow suppression was induced by injection with 5-FU in dose of 150 mg/kg, then the nucleated cells were isolated from bone marrow. After the HSPCs were markered with C-kit/sca-1 fluorescent antibodies, the changes of cell cycle and apoptosis of HSPC were detected by Aunexin V/PI and Ki67/DAPI double staining; the cell cycle-essociated hemotopoietic regulatory factors were detected by RT-qPCR. RESULTS: Under physiologic status, there were no significant differences in cell cycle and apoptotic rate of HSPC between WT group and BMP-4 group. After the bone marrow was suppressed, the ratio of HSPC at G0 phase in BMP4 group significantly decreased(Pï¼0.05); the apoptosis rate of HSPC significantly increased(Pï¼0.05); the mRNA expression levels of hypoxia-inducing factor Hif-1α and chemotactic factor CXCL12 in stroma of BMP4 group were down-regulated significanfly(Pï¼0.05). CONCLUSION: Under non-physiologic conditions such as stress hemogenesis or bone marrow suppression, the up-regulation of BMP4 can promote HSPC into cell cycle and apoptosis of HSPC, moreover, the BMP4 may play a regulatory role for cell cycle of HSPC through direct or indirect down-regulation of Hif-1α and CXCL-12 expressions.
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Células Madre Hematopoyéticas , Animales , Antineoplásicos , Apoptosis , Proteína Morfogenética Ósea 4 , Ciclo Celular , Ratones , Ratones Endogámicos C57BLRESUMEN
The Ni-catalyzed Suzuki-Miyaura coupling of N-tert-butoxycarbonyl (N-Boc)-protected amides provides a versatile strategy for the construction of C-C bonds. In this study, density functional theory (DFT) methods have been used to elucidate the mechanism of this reaction, with particular emphasis on the roles of N-Boc, K3 PO4 and H2 O. Our results corroborated those of previous reports, indicating that the overall catalytic cycle consists of three steps, including oxidative addition, transmetalation, and reductive elimination. Three of the possible transmetalation mechanisms were examined to interpret the effects of K3 PO4 and H2 O. According to the most feasible of these transmetalation mechanisms, K3 PO4 (acting as a Lewis base) would initially interact with the Lewis acid PhBpin to give a K3 PO4 -PhBpin complex, which would readily undergo a hydrogen transfer step with H2 O. The H transfer in the transmetalation step was determined to be the rate-determining step. Notably, the theoretical results showed good agreement with the experimental data.
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Cu-catalyzed alkylboration of alkenes with bis(pinacolato)diboron ((Bpin)2 ) and alkyl halides provides a ligand-controlled regioselectivity-switchable method for the construction of complex boron-containing compounds. Here, we employed DFT methods to elucidate the mechanistic details of this reaction and the origin of the different regioselectivity induced by Xantphos and Cy-Xantphos. The calculation results reveal that the catalytic cycle mainly proceeds through the migratory insertion of alkenes on Cu-Bpin complex, the oxidative addition of alkyl halides, and the reductive elimination of a C-C bond. Meanwhile, the rate- determining step is the oxidative addition of alkyl halides and the regioselectivity-determining step is the migratory insertion of alkenes. The bulky cyclohexyl group of Cy-Xantphos facilitates the approach of the substituents of alkenes to Bpin in the migratory insertion step and thus leads to the Markovnikov products. The less bulky phenyl group on Xantphos prefers keeping the substituents of alkenes away from the Bpin moiety in the migratory insertion step and thus results in anti-Markovnikov products.
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A novel copper-catalyzed regiodivergent alkylboration of alkenes with bis(pinacolato)diboron and alkyl halides has been developed. The regioselectivity of the alkylboration was controlled by subtle differences in the ligand structure. The reaction thus enables the practical, regiodivergent synthesis of two different alkyl boronic esters with complex structures from a single alkene.
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Alquenos/química , Compuestos de Boro/síntesis química , Cobre/química , Compuestos Organometálicos/química , Compuestos de Boro/química , Catálisis , Ligandos , Estructura Molecular , EstereoisomerismoRESUMEN
The Ni-catalyzed C(sp(2))-H/C(sp(3))-H coupling of benzamides with toluene derivatives was recently successfully achieved with mild oxidant iC3F7I. Herein, we employ density functional theory (DFT) methods to resolve the mechanistic controversies. Two previously proposed mechanisms are excluded, and our proposed mechanism involving iodine-atom transfer (IAT) between iC3F7I and the Ni(II) intermediate was found to be more feasible. With this mechanism, the presence of a carbon radical is consistent with the experimental observation that (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) completely quenches the reaction. Meanwhile, the hydrogen-atom abstraction of toluene is irreversible and the activation of the C(sp(2))-H bond of benzamides is reversible. Both of these conclusions are in good agreement with Chatani's deuterium-labeling experiments.