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1.
Pediatr Neurol ; 155: 8-17, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38569228

RESUMO

BACKGROUND: TRAF7-related cardiac, facial, and digital anomalies with developmental delay (CAFDADD), a multisystemic neurodevelopmental disorder caused by germline missense variants in the TRAF7 gene, exhibits heterogeneous clinical presentations. METHODS: We present a detailed description of 11 new TRAF7-related CAFDADD cases, featuring eight distinct variants, including a novel one. RESULTS: Phenotypic analysis and a comprehensive review of the 58 previously reported cases outline consistent clinical presentations, emphasizing dysmorphic features, developmental delay, endocrine manifestations, and cardiac defects. In this enlarged collection, novelties include a wider range of cognitive dysfunction, with some individuals exhibiting normal development despite early psychomotor delay. Communication challenges, particularly in expressive language, are prevalent, necessitating alternative communication methods. Autistic traits, notably rigidity, are observed in the cohort. Also, worth highlighting are hearing loss, sleep disturbances, and endocrine anomalies, including growth deficiency. Cardiac defects, frequently severe, pose early-life complications. Facial features, including arched eyebrows, contribute to the distinct gestalt. A novel missense variant, p.(Arg653Leu), further underscores the complex relationship between germline TRAF7 variants and somatic changes linked to meningiomas. CONCLUSIONS: Our comprehensive analysis expands the phenotypic spectrum, emphasizing the need for oncological evaluations and proposing an evidence-based schedule for clinical management. This study contributes to a better understanding of TRAF7-related CAFDADD, offering insights for improved diagnosis, intervention, and patient care.


Assuntos
Deficiências do Desenvolvimento , Cardiopatias Congênitas , Fenótipo , Humanos , Deficiências do Desenvolvimento/genética , Masculino , Feminino , Criança , Pré-Escolar , Cardiopatias Congênitas/genética , Cardiopatias Congênitas/fisiopatologia , Lactente , Peptídeos e Proteínas Associados a Receptores de Fatores de Necrose Tumoral/genética , Mutação de Sentido Incorreto , Adolescente
2.
Pediatr Dermatol ; 2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38456245

RESUMO

Two siblings presented with straw-colored, frizzy, and wiry hair. They had no associated abnormalities and no family history of abnormal hair. Trichoscopy showed the longitudinal groove in the hair shafts, characteristic of uncombable hair syndrome. Molecular genetic analysis revealed a new pathogenic variant (c.1374dup; p. Val459ArgfsTer15) in PADI3, not previously described.

3.
Neurol Genet ; 10(2): e200138, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38544965

RESUMO

Objectives: Thymidine kinase 2 deficiency (TK2d) is a rare autosomal recessive disorder that stems from a perturbation of the mitochondrial DNA maintenance. Nucleoside treatment has recently shown promise as a disease-modifying therapy. TK2d was initially associated with rapidly progressive fatal myopathy in children featuring mitochondrial DNA depletion. Subsequently, less severe variants of the disease were described, with onset of symptoms during adolescence or adulthood and associated with the presence of multiple mtDNA deletions. These less severe phenotypes have been reported in only 15% of the approximately 120 patients described worldwide. However, some reports suggest that these juvenile and adult-onset presentations may be more common. The objective of this study was to describe the clinical phenotype in a sample of patients from Spain. Methods: This study includes 53 patients harboring biallelic TK2 pathogenic variants, compiling data retrospectively from 7 Spanish centers. We analyzed allele frequency, investigated the most recent common ancestor of core haplotypes, and used the Runs of Homozygosity approach to investigate variant coalescence. Results: Symptom onset distribution revealed that 32 patients (60%) experienced symptoms beyond 12 years of age. Approximately 30% of patients died of respiratory insufficiency, while 56% of surviving patients needed mechanical ventilation. Genetic analysis identified 16 distinct variants in TK2. Two variants, p.Lys202del and p.Thr108Met, exhibited significantly higher prevalence in the Spanish population than that reported in gnomAD database (86-fold and 13-fold, respectively). These variants are estimated to have originated approximately 16.8 generations ago for p.Thr108Met and 95.2 generations ago for p.Lys202del within the Spanish population, with the increase in frequency attributed to various forms of inbreeding. In late-onset cases, 46.9% carried the p.Lys202del variant. Discussion: The higher frequency of TK2d in Spain can be partially attributed to the increased prevalence of 2 variants and consanguinity. Notably, in 60% of the cohort, the disease was late-onset, emphasizing the potential underdiagnosis of this subgroup of patients in other regions. Raising awareness of this potentially treatable disorder is of utmost importance because early interventions can significantly affect the quality of life and survival of affected individuals.

4.
J Clin Immunol ; 44(3): 61, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38363452

RESUMO

Human inborn errors of immunity (IEI) comprise a group of diseases resulting from molecular variants that compromise innate and adaptive immunity. Clinical features of IEI patients are dominated by susceptibility to a spectrum of infectious diseases, as well as autoimmune, autoinflammatory, allergic, and malignant phenotypes that usually appear in childhood, which is when the diagnosis is typically made. However, some IEI patients are identified in adulthood due to symptomatic delay of the disease or other reasons that prevent the request for a molecular study. The application of next-generation sequencing (NGS) as a diagnostic technique has given rise to an ever-increasing identification of IEI-monogenic causes, thus improving the diagnostic yield and facilitating the possibility of personalized treatment. This work was a retrospective study of 173 adults with IEI suspicion that were sequenced between 2005 and 2023. Sanger, targeted gene-panel, and whole exome sequencing were used for molecular diagnosis. Disease-causing variants were identified in 44 of 173 (25.43%) patients. The clinical phenotype of these 44 patients was mostly related to infection susceptibility (63.64%). An enrichment of immune dysregulation diseases was found when cohorts with molecular diagnosis were compared to those without. Immune dysregulation disorders, group 4 from the International Union of Immunological Societies Expert Committee (IUIS), were the most prevalent among these adult patients. Immune dysregulation as a new item in the Jeffrey Model Foundation warning signs for adults significantly increases the sensitivity for the identification of patients with an IEI-producing molecular defect.


Assuntos
Doenças do Sistema Imunitário , Adulto , Humanos , Estudos Retrospectivos , Doenças do Sistema Imunitário/diagnóstico , Doenças do Sistema Imunitário/genética , Imunidade Adaptativa , Sequenciamento de Nucleotídeos em Larga Escala , Pacientes
5.
Genes (Basel) ; 14(7)2023 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-37510397

RESUMO

Hereditary palmoplantar keratodermas (PPKs) are a clinically and genetically heterogeneous group of disorders characterized by excessive epidermal thickening of palms and soles. Several genes have been associated with PPK including PERP, a gene encoding a crucial component of desmosomes that has been associated with dominant and recessive keratoderma. We report a patient with recessive erythrokeratoderma (EK) in which whole exome sequencing (WES) prioritized by human phenotype ontology (HPO) terms revealed the presence of the novel variant c.153C > A in the N-terminal region the PERP gene. This variant is predicted to have a nonsense effect, p.(Cys51Ter), resulting in a premature stop codon. We demonstrated a marked reduction in gene expression in cultured skin fibroblasts obtained from the patient. Despite the PERP gene is expressed at low levels in fibroblasts, our finding supports a loss-of-function (LoF) mechanism for the identified variant, as previously suggested in recessive EK. Our study underscores the importance of integrating HPO analysis when using WES for molecular genetic diagnosis in a clinical setting, as it facilitates continuous updates regarding gene-clinical feature associations.


Assuntos
Ceratodermia Palmar e Plantar , Humanos , Ceratodermia Palmar e Plantar/genética , Fenótipo , Códon sem Sentido , Padrões de Herança , Perfilação da Expressão Gênica , Proteínas de Membrana/genética , Genes Supressores de Tumor
6.
J Allergy Clin Immunol ; 152(3): 736-747, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37277074

RESUMO

BACKGROUND: TCF3 is a transcription factor contributing to early lymphocyte differentiation. Germline monoallelic dominant negative and biallelic loss-of-function (LOF) null TCF3 mutations cause a fully penetrant severe immunodeficiency. We identified 8 individuals from 7 unrelated families with monoallelic LOF TCF3 variants presenting with immunodeficiency with incomplete clinical penetrance. OBJECTIVE: We sought to define TCF3 haploinsufficiency (HI) biology and its association with immunodeficiency. METHODS: Patient clinical data and blood samples were analyzed. Flow cytometry, Western blot analysis, plasmablast differentiation, immunoglobulin secretion, and transcriptional activity studies were conducted on individuals carrying TCF3 variants. Mice with a heterozygous Tcf3 deletion were analyzed for lymphocyte development and phenotyping. RESULTS: Individuals carrying monoallelic LOF TCF3 variants showed B-cell defects (eg, reduced total, class-switched memory, and/or plasmablasts) and reduced serum immunoglobulin levels; most but not all presented with recurrent but nonsevere infections. These TCF3 LOF variants were either not transcribed or translated, resulting in reduced wild-type TCF3 protein expression, strongly suggesting HI pathophysiology for the disease. Targeted RNA sequencing analysis of T-cell blasts from TCF3-null, dominant negative, or HI individuals clustered away from healthy donors, implying that 2 WT copies of TCF3 are needed to sustain a tightly regulated TCF3 gene-dosage effect. Murine TCF3 HI resulted in a reduction of circulating B cells but overall normal humoral immune responses. CONCLUSION: Monoallelic LOF TCF3 mutations cause a gene-dosage-dependent reduction in wild-type protein expression, B-cell defects, and a dysregulated transcriptome, resulting in immunodeficiency. Tcf3+/- mice partially recapitulate the human phenotype, underscoring the differences between TCF3 in humans and mice.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos , Haploinsuficiência , Síndromes de Imunodeficiência , Animais , Humanos , Camundongos , Linfócitos B , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Imunoglobulinas/genética , Síndromes de Imunodeficiência/genética , Linfócitos T
7.
Eur J Ophthalmol ; 33(4): NP27-NP31, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36112829

RESUMO

PURPOSE: To report two clinical cases of Alström syndrome (AS) with novel pathogenic variant of the ALMS1 gene not previously reported. CASE DESCRIPTION: Patient 1 was a 6-year-old female presenting with poor vision. Ophthalmic examination only showed a visual field (VF) with diffusely decreased sensitivity in both eyes. At age of 15, vision and ophthalmic examination remain stable. Patient 2 was a 2-year-old male with poor vision, photophobia, and nystagmus. ERG showed a severe decrease in cone and rod responses. At age of 6, his vision is lower than 0.1 (decimal scale) and VF is severely constricted. Both of them presented with dilated cardiomyopathy in their first's months of life and patient 2 developed sensorineural deafness along with follow-up. Research genetic testing revealed two loss-of-function heterozygous genetic variants in the ALMS1 gene in both patients, so the diagnosis of AS was made. CONCLUSIONS: AS is a rare disease caused by pathogenic variants of ALMS1 gene that causes ocular manifestations in almost 100% of patients. There are many genetic variants of AMLS1 described, but novel pathogenic variants can still be found. Ophthalmologists play an important role in the diagnosis, and AS should be included in the differential diagnosis when retinal dystrophy is suspected.


Assuntos
Síndrome de Alstrom , Perda Auditiva Neurossensorial , Masculino , Feminino , Humanos , Criança , Pré-Escolar , Síndrome de Alstrom/diagnóstico , Síndrome de Alstrom/genética , Proteínas de Ciclo Celular/genética , Mutação , Testes Genéticos , Perda Auditiva Neurossensorial/diagnóstico , Perda Auditiva Neurossensorial/genética
8.
J Clin Immunol ; 43(1): 165-180, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36066697

RESUMO

Somatic mutations in the ten-eleven translocation methylcytosine dioxygenase 2 gene (TET2) have been associated to hematologic malignancies. More recently, biallelic, and monoallelic germline mutations conferring susceptibility to lymphoid and myeloid cancer have been described. We report two unrelated autoimmune lymphoproliferative syndrome-like patients who presented with T-cell lymphoma associated with novel germline biallelic or monoallelic mutations in the TET2 gene. Both patients presented a history of chronic lymphoproliferation with lymphadenopathies and splenomegaly, cytopenias, and immune dysregulation. We identified the first compound heterozygous patient for TET2 mutations (P1) and the first ALPS-like patient with a monoallelic TET2 mutation (P2). P1 had the most severe form of autosomal recessive disease due to TET2 loss of function resulting in absent TET2 expression and profound increase in DNA methylation. Additionally, the immunophenotype showed some alterations in innate and adaptive immune system as inverted myeloid/plasmacytoid dendritic cells ratio, elevated terminally differentiated effector memory CD8 + T-cells re-expressing CD45RA, regulatory T-cells, and Th2 circulating follicular T-cells. Double-negative T-cells, vitamin B12, and IL-10 were elevated according to the ALPS-like suspicion. Interestingly, the healthy P1's brother carried a TET2 mutation and presented some markers of immune dysregulation. P2 showed elevated vitamin B12, hypergammaglobulinemia, and decreased HDL levels. Therefore, novel molecular defects in TET2 confirm and expand both clinical and immunological phenotype, contributing to a better knowledge of the bridge between cancer and immunity.


Assuntos
Síndrome Linfoproliferativa Autoimune , Dioxigenases , Neoplasias Hematológicas , Masculino , Humanos , Síndrome Linfoproliferativa Autoimune/diagnóstico , Síndrome Linfoproliferativa Autoimune/genética , Mutação em Linhagem Germinativa , Neoplasias Hematológicas/diagnóstico , Neoplasias Hematológicas/genética , Mutação/genética , Fenótipo , Vitamina B 12 , Proteínas de Ligação a DNA/genética , Dioxigenases/genética
9.
Nat Commun ; 13(1): 5695, 2022 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-36171189

RESUMO

The human insulin receptor signalling system plays a critical role in glucose homeostasis. Insulin binding brings about extensive conformational change in the receptor extracellular region that in turn effects trans-activation of the intracellular tyrosine kinase domains and downstream signalling. Of particular therapeutic interest is whether insulin receptor signalling can be replicated by molecules other than insulin. Here, we present single-particle cryoEM structures that show how a 33-mer polypeptide unrelated to insulin can cross-link two sites on the receptor surface and direct the receptor into a signalling-active conformation. The 33-mer polypeptide engages the receptor by two helical binding motifs that are each potentially mimicable by small molecules. The resultant conformation of the receptor is distinct from-but related to-those in extant three-dimensional structures of the insulin-complexed receptor. Our findings thus illuminate unexplored pathways for controlling the signalling of the insulin receptor as well as opportunities for development of insulin mimetics.


Assuntos
Insulina , Receptor de Insulina , Glucose/metabolismo , Humanos , Insulina/metabolismo , Fosforilação , Receptor de Insulina/metabolismo , Transdução de Sinais
11.
Rev. colomb. cardiol ; 28(5): 404-409, sep.-oct. 2021.
Artigo em Espanhol | LILACS, COLNAL | ID: biblio-1357206

RESUMO

Resumen Introducción: La enfermedad cardiovascular en mujeres ha sido un apartado con diversas investigaciones que han intentado llegar a los factores de riesgo más determinantes o las vías moleculares más específicas para explicar el riesgo aumentado que poseen las mujeres respecto a los hombres. Objetivo: Dar una visión global de esta situación al lector, involucrando especialmente aquella población de mujeres que padece diabetes mellitus tipo 2, cuya condición es un factor de riesgo independiente para el desarrollo de enfermedad cardiovascular, de gran costo y morbimortalidad mundiales. Métodos: Se realizó una búsqueda en PubMed y Google Scholar con términos MeSH y términos comunes y se obtuvieron algunas referencias cruzadas a criterio de los autores. Conclusiones: Es necesario implementar en la práctica médica diaria un contexto específico de prevención de riesgo cardiovascular mediante programas de educación continuada o por medio de las entidades prestadoras de servicios de salud para evitar la progresión de enfermedad cardiovascular en las mujeres diabéticas antes de llegar a desenlaces mayores y potencialmente fatales.


Abstract Introduction: Cardiovascular disease in woman has been an issue with plenty of investigations towards the finding of the most determinant risk factors o the specific molecular paths to explain the increased risk in women compared to men. Objective: To give to the reader a global vision of this situation, involving specially the type 2 diabetes mellitus woman population, whose condition is an independent risk factor to the development of the cardiovascular disease with great cost and morbidity and mortality worldwide. Methods: A PUBMED and Google Scholar search was performed with MeSH and common terms and were obtained some cross-references at the discretion of the authors. Conclusions: It is necessary to implement a specific context of cardiovascular risk prevention in daily medical practice through continuing education programs or through health service providers to prevent the progression of cardiovascular disease in diabetic women before reaching major outcomes and potentially fatal.


Assuntos
Humanos , Feminino , Diabetes Mellitus/epidemiologia , Fatores de Risco de Doenças Cardíacas , Doenças Cardiovasculares/prevenção & controle , Complicações do Diabetes/prevenção & controle , Diabetes Mellitus Tipo 2/epidemiologia
12.
Neurogenetics ; 22(4): 343-346, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34296368

RESUMO

Allan-Herndon-Dudley is an X-linked recessive syndrome caused by pathogenic variants in the SLC16A2 gene. Clinical manifestations are a consequence of impaired thyroid metabolism and aberrant transport of thyroid hormones to the brain. Carrier females are generally asymptomatic and may show subtle symptoms of the disease. We describe a female with a complete Allan-Herndon-Dudley phenotype, carrying a de novo 543-kb deletion of the X chromosome. The deletion encompasses exon 1 of the SLC16A2 gene and JPX and FTX genes; it is known that the latter two genes participate in the X-inactivation process upregulating XIST gene expression. Subsequent studies in the patient demonstrated the preferential expression of the X chromosome with the JPX and FTX deletion.


Assuntos
Deficiência Intelectual Ligada ao Cromossomo X/genética , Deficiência Intelectual Ligada ao Cromossomo X/patologia , Hipotonia Muscular/genética , Hipotonia Muscular/patologia , Atrofia Muscular/genética , Atrofia Muscular/patologia , Mutação/genética , Inativação do Cromossomo X/genética , Encéfalo/patologia , Criança , Feminino , Humanos , Deficiência Intelectual Ligada ao Cromossomo X/diagnóstico , Transportadores de Ácidos Monocarboxílicos/genética , Hipotonia Muscular/diagnóstico , Atrofia Muscular/diagnóstico , Fenótipo , Simportadores/genética
13.
Sci Total Environ ; 749: 141621, 2020 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-32822915

RESUMO

Lockdown measures led to air pollution decrease in several countries around the world such as China and India, whereas other regions experimented an increase in pollutant concentrations. Northern South America (NSA) was one of those areas where pollution changed during lockdown due to high fire activity. This study aims to analyze, for the first time in NSA, the behavior of selected criteria air pollutants during the implementation of the SARS-CoV-2 lockdown in two high populated cities of the region: Bogotá and Medellín in Colombia. A set of tools including surface measurements, as well as satellite and modeled data were used. 24-hour average concentrations of PM10, PM2.5, and NO2 were collected from air quality stations for the lockdown period ranging from February 21 to June 30, 2020. The Copernicus Atmosphere Monitoring Service (CAMS) was used to analyze the fire flux OC as a biomass burning (BB) indicator, and tropospheric NO2 concentrations were retrieved from TROPOMI. The HYSPLIT model was used to analyze back trajectories and fire data were obtained from MODIS sensor measurements. Our analysis shows short-term background NO2, PM10, and PM2.5 concentration reductions of 60%, 44%, and 40%, respectively, for the strict lockdown; and 62%, 58%, and 69% for the relaxed lockdown. Corresponding long-term reductions were of 50%, 32%, and 9% for the strict lockdown; and 37%, 29%, and 19% for the relaxed lockdown. Regional BB increased PM2.5 concentrations by 20 µg/m3 during the strict lockdown, and the Saharan dust event increased PM10 concentrations up to 168 µg/m3 in Bogotá, and 104 µg/m3 in Medellín, bringing an additional risk of morbidity and mortality for population. Regional BB has several causes that need to be properly managed to benefit local air quality improvement plans. Future cleaner transport policies equivalent to reduced lockdown mobility could bring pollution close to WHO guidelines.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , COVID-19 , África do Norte , Poluentes Atmosféricos/análise , Poluição do Ar/análise , China , Cidades , Colômbia , Controle de Doenças Transmissíveis , Monitoramento Ambiental , Humanos , Índia , América do Norte , Material Particulado/análise , SARS-CoV-2 , América do Sul
14.
ACS Chem Biol ; 11(11): 3154-3164, 2016 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-27627661

RESUMO

To evaluate its potential as a ligand discovery tool, we compare a newly developed 1D protein-observed fluorine NMR (PrOF NMR) screening method with the well-characterized ligand-observed 1H CPMG NMR screen. We selected the first bromodomain of Brd4 as a model system to benchmark PrOF NMR because of the high ligandability of Brd4 and the need for small molecule inhibitors of related epigenetic regulatory proteins. We compare the two methods' hit sensitivity, triaging ability, experiment speed, material consumption, and the potential for false positives and negatives. To this end, we screened 930 fragment molecules against Brd4 in mixtures of five and followed up these studies with mixture deconvolution and affinity characterization of the top hits. In selected examples, we also compare the environmental responsiveness of the 19F chemical shift to 1H in 1D-protein observed 1H NMR experiments. To address concerns of perturbations from fluorine incorporation, ligand binding trends and affinities were verified via thermal shift assays and isothermal titration calorimetry. We conclude that for the protein understudy here, PrOF NMR and 1H CPMG have similar sensitivity, with both being effective tools for ligand discovery. In cases where an unlabeled protein can be used, 1D protein-observed 1H NMR may also be effective; however, the 19F chemical shift remains significantly more responsive.


Assuntos
Flúor/química , Espectroscopia de Ressonância Magnética/métodos , Ligantes
15.
Carbohydr Res ; 433: 36-40, 2016 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-27434833

RESUMO

NOE-based analysis of the disaccharide ß-Gal-(1 â†’ 3)-ß-Glc-OMe (1), especially a diagnostic Gal1-Glc4 NOE detected in a HSQC-NOESY spectrum, reveals the existence of the anti-ψ conformer in aqueous solution in addition to the major syn conformer. This result provides experimental proof of conformational flexibility around the aglyconic bond of ß-(1 â†’ 3) disaccharides, in contrast to previous studies that suggested that the flexibility around this linkage was restricted to the syn conformational region.


Assuntos
Dissacarídeos/química , Configuração de Carboidratos , Espectroscopia de Ressonância Magnética , Modelos Moleculares
16.
J Org Chem ; 80(8): 3914-20, 2015 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-25803271

RESUMO

NMR studies in conjunction with ab initio calculations revealed unexpected conformational behavior of N-cyclopropylacetamide (1). This secondary amide displays 16-19% E-rotamer (cis) around the carbonyl-nitrogen bond in apolar solvents, in contrast to other aliphatic secondary acetamides in which significant E-rotamer populations are rare due to steric contacts between the substituents on the amide bond. In addition, 1 adopts an ortho conformation around the N-cPr bond instead of the anti conformation generally preferred by secondary acetamides. This distinct conformational behavior was also observed for other secondary N-cyclopropyl amides.

17.
J Org Chem ; 78(24): 12844-7, 2013 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-24195699

RESUMO

A novel methodology based on 1D- and 2D-TOCSY experiments is described for a quick and accurate measurement of proton-fluorine coupling constants in fluorinated organic compounds. The magnitude of the (1)H-(19)F coupling was measured from the displacement between the relayed peaks associated with the α or ß spin state of the fluorine, and its relative sign was derived from the sense of the displacement.


Assuntos
Flúor/química , Hidrocarbonetos Fluorados/química , Espectroscopia de Ressonância Magnética/métodos , Estrutura Molecular , Prótons
18.
Org Biomol Chem ; 11(27): 4473-8, 2013 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-23715525

RESUMO

A user-friendly 2D NMR approach denoted as CLIP-HSQMBC is proposed for the very easy, direct and accurate measurement of long-range proton-carbon coupling constants in organic molecules and natural products. The J value can be extracted directly from the analysis of resolved in-phase (1)H multiplets that show an additional splitting arising from the proton-carbon coupling. In cases of unresolved peaks, a simple fitting analysis using the internal satellite lines as a reference is performed. Addition of a spin-lock period results in a CLIP-HSQMBC-TOCSY experiment that is suitable for the measurement of very small coupling values or to observe correlations from overlapped resonances.


Assuntos
Carbono/química , Espectroscopia de Ressonância Magnética/métodos , Prótons , Convulsivantes/química , Estricnina/química
19.
Magn Reson Chem ; 49(8): 502-7, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21751246

RESUMO

The SELective INverse detection of carbon-proton CORrelation pulse sequence that yields a 1D spectrum of a proton directly bonded to a selected carbon resonance has been converted into a proton and carbon double-selective variant that provides a (1)H spectrum of a selected proton that is long-range coupled to a specific carbon resonance. The resulting 1D proton multiplet exhibits a pure absorptive in-phase lineshape for precise measurement of specific long-range proton-carbon coupling constants in small organic molecules at natural abundance.

20.
Curr Top Med Chem ; 11(1): 74-92, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-20809890

RESUMO

In situ structural characterization of organic compounds attached to solid supports can be achieved by high-resolution magic angle spinning NMR (HRMAS NMR), a technique that provides solution-like spectra for resin-bound molecules. This review outlines the principles of the technique, the influence of the solid support on data quality, and NMR experiments that are useful for obtaining valuable information. The review describes, with multiple examples mainly from the last 7 years, how HRMAS NMR has been applied to monitor solid-phase reactions, elucidate reaction products and quantify compound loading on a solid support. Other applications, such as conformational analysis of immobilized compounds and investigation of molecular interactions with compounds in solution, are also discussed.


Assuntos
Espectroscopia de Ressonância Magnética/métodos , Compostos Orgânicos/análise , Catálise , Compostos Orgânicos/química , Estereoisomerismo
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