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1.
Hum Mutat ; 40(12): 2414-2429, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31448843

RESUMEN

PARN encodes poly(A)-specific ribonuclease. Biallelic and monoallelic PARN variants are associated with Hoyeraal-Hreidarsson syndrome/dyskeratosis congenita and idiopathic pulmonary fibrosis (IPF), respectively. The molecular features associated with incomplete penetrance of PARN-associated IPF have not been described. We report a family with a rare missense, p.Y91C, and a novel insertion, p.(I274*), PARN variant. We found PARN p.Y91C had reduced deadenylase activity and the p.(I274*) transcript was depleted. Detailed analysis of the consequences of these variants revealed that, while PARN protein was lowest in the severely affected biallelic child who had the shortest telomeres, it was also reduced in his mother with the p.(I274*) variant but telomeres at the 50th percentile. Increased adenylation of telomerase RNA, human telomerase RNA, and certain small nucleolar RNAs, and impaired ribosomal RNA maturation were observed in cells derived from the severely affected biallelic carrier, but not in the other, less affected biallelic carrier, who had less severely shortened telomeres, nor in the monoallelic carriers who were unaffected and had telomeres ranging from the 1st to the 50th percentiles. We identified hsa-miR-202-5p as a potential negative regulator of PARN. We propose one or more genetic modifiers influence the impact of PARN variants on its targets and this underlies incomplete penetrance of PARN-associated disease.


Asunto(s)
Disqueratosis Congénita/genética , Exorribonucleasas/genética , Retardo del Crecimiento Fetal/genética , Discapacidad Intelectual/genética , MicroARNs/genética , Microcefalia/genética , Mutagénesis Insercional , Mutación Missense , Adolescente , Línea Celular , Preescolar , Regulación hacia Abajo , Exorribonucleasas/metabolismo , Femenino , Humanos , Masculino , Linaje , Penetrancia , Acortamiento del Telómero
2.
Nutrients ; 10(5)2018 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-29723971

RESUMEN

Adult-type hypolactasia (ATH) is a clinical syndrome of primary lactase deficiency. A lactose-free diet is advisable to avoid the symptoms linked to the condition, but this potentially creates problems for optimal bone mineralization due to reduced calcium intake. To evaluate the effect of the lactose-free diet on the bone mineral status (BMS), we compared the phalangeal BMS of adolescents with ATH to that of peers on a normal diet. Also, we analyzed the correlations between BMS and dietary behavior, physical exercise, and calcium and vitamin D intake. A total of 102 cases and 102 healthy controls filled out a diet record and underwent phalangeal Quantitative Ultrasound (QUS). No difference in BMS was observed. The time spent on lactose-free diet (4.8 ± 3.1 years) was inversely correlated to the BMS. More than 98% of cases consumed lactose-free milk, but calcium and vitamin D intake were significantly lower. Calcium intake was correlated to physical exercise but not to BMS. Our results suggest that a lactose-free diet does not affect the phalangeal BMS of adolescents with primary lactase deficiency when their diet includes lactose-free cow’s milk. However, there is still a significantly lower calcium intake than in the population reference. The inverse correlation observed between the BMS and the time spent on a lactose-free diet suggests that a long-term follow-up is advisable.


Asunto(s)
Densidad Ósea , Dieta , Falanges de los Dedos de la Mano/química , Lactasa/deficiencia , Intolerancia a la Lactosa/dietoterapia , Lactosa/administración & dosificación , Adolescente , Animales , Índice de Masa Corporal , Peso Corporal , Calcio de la Dieta/administración & dosificación , Errores Innatos del Metabolismo de los Carbohidratos , Estudios de Casos y Controles , Registros de Dieta , Estudios de Evaluación como Asunto , Ejercicio Físico , Femenino , Falanges de los Dedos de la Mano/diagnóstico por imagen , Conductas Relacionadas con la Salud , Humanos , Masculino , Leche/química , Estado Nutricional , Ultrasonografía , Vitamina D/administración & dosificación , Adulto Joven
3.
Mol Cell Biol ; 38(12)2018 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-29581185

RESUMEN

TIN2 is central to the shelterin complex, linking the telomeric proteins TRF1 and TRF2 with TPP1/POT1. Mutations in TINF2, which encodes TIN2, that are found in dyskeratosis congenita (DC) result in very short telomeres and cluster in a region shared by the two TIN2 isoforms, TIN2S (short) and TIN2L (long). Here we show that TIN2L, but not TIN2S, is phosphorylated. TRF2 interacts more with TIN2L than TIN2S, and both the DC cluster and phosphorylation promote this enhanced interaction. The binding of TIN2L, but not TIN2S, is affected by TRF2-F120, which is also required for TRF2's interaction with end processing factors such as Apollo. Conversely, TRF1 interacts more with TIN2S than with TIN2L. A DC-associated mutation further reduces TIN2L-TRF1, but not TIN2S-TRF1, interaction. Cells overexpressing TIN2L or phosphomimetic TIN2L are permissive to telomere elongation, whereas cells overexpressing TIN2S or phosphodead TIN2L are not. Telomere lengths are unchanged in cell lines in which TIN2L expression has been eliminated by clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated mutation. These results indicate that TIN2 isoforms are biochemically and functionally distinguishable and that shelterin composition could be fundamentally altered in patients with TINF2 mutations.


Asunto(s)
Proteínas de Unión a Telómeros/genética , Proteínas de Unión a Telómeros/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Sistemas CRISPR-Cas/genética , Línea Celular , Disqueratosis Congénita/genética , Humanos , Mutación/genética , Fosforilación , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Complejo Shelterina , Telómero/metabolismo
4.
Hemoglobin ; 41(4-6): 254-259, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29226737

RESUMEN

Pseudoxanthoma elasticum-like (PXL) condition is one of the complications faced by patients with ß-thalassemia major (ß-TM). Histopathological features include abnormal, mineralized and fragmented elastic fibers in skin, eyes and arterial blood vessels (elastorrhexia). The pathogenesis of PXL lesions in ß-TM is not yet completely understood. This study was aimed at analyzing a possible implication of α-Klotho in the clinical manifestation of PXL in patients with ß-TM (30 with and 78 without PXL). A significant correlation was observed between Klotho, parathyroid hormone (PTH) and serum calcium (Ca). Our analysis seems to indicate α-Klotho and PTH as factors that can affect the development of PXL.


Asunto(s)
Calcio/sangre , Glucuronidasa/sangre , Hormona Paratiroidea/sangre , Seudoxantoma Elástico/sangre , Talasemia beta/sangre , Adulto , Femenino , Humanos , Proteínas Klotho , Masculino , Persona de Mediana Edad , Seudoxantoma Elástico/etiología , Talasemia beta/complicaciones
5.
Pediatr Neurol ; 71: 14-17, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28449983

RESUMEN

BACKGROUND: Full-term neonates may have asymptomatic cranial injuries at birth and head ultrasound screening could be useful for early diagnosis. The aim of this study was to assess the prevalence and type of intracranial abnormalities and the usefulness of head ultrasound screening in these infants. METHODS: Head ultrasound screening was performed on all full-term neonates (gestational age between 37 and 42 weeks), born at Sant'Anna University Hospital of Ferrara, Italy, from June 1, 2008 through May 31, 2013. Ultrasound findings were categorized into three groups: normal, minor, and major anomalies. RESULTS: All full-term neonates (6771) born at our hospital underwent head ultrasound screening. One hundred fourteen of 6771 (1.7%) presented ultrasound abnormalities, whereas 6657 were normal or exhibited insignificant findings. In 101 of 114 (88.6%), abnormalities were minor, and only 13 infants had major abnormalities (0.19% of all full-term newborns). All neonates with major abnormalities presented with either microcephaly or abnormal neurological evaluations. Only one individual with major abnormalities was detected exclusively by ultrasound. CONCLUSIONS: The number of significant anomalies detected by head ultrasound screening in asymptomatic full-term neonates born during the study period was low. Therefore, there is no indication for routine general head ultrasound screening in these patients. However, even if low, in neonates who have neurological abnormalities, risk factors or suspected brain malformations, head ultrasound screening may play an important role in the early diagnosis of intracranial anomalies.


Asunto(s)
Cabeza/diagnóstico por imagen , Tamizaje Neonatal , Ultrasonografía , Femenino , Cabeza/anomalías , Humanos , Recién Nacido , Masculino , Tamizaje Neonatal/métodos , Estudios Retrospectivos
6.
Blood Cells Mol Dis ; 62: 32-37, 2016 11.
Artículo en Inglés | MEDLINE | ID: mdl-27838552

RESUMEN

High levels of fetal hemoglobin (HbF) reduce sickle cell anemia (SCA) morbidity and mortality. HbF levels vary considerably and there is a strong genetic component that influences HbF production. Genetic polymorphisms at three quantitative trait loci (QTL): Xmn1-HBG2, HMIP-2 and BCL11A, have been shown to influence HbF levels and disease severity in SCA. Hydroxyurea (HU) is a drug that increases HbF. We investigated the influence of single nucleotide polymorphisms (SNPs) at the Xmn1-HBG2 (rs7482144); BCL11A (rs1427407, rs4671393 and rs11886868); and HMIP-2 (rs9399137 and rs9402686) loci on baseline and HU-induced HbF levels in 111 HbSS patients. We found that both BCL11A and HMIP-2 were associated with increased endogenous levels of HbF. Interestingly, we also found that BCL11A was associated with higher induction of HbF with HU. This effect was independent of the effect of BCL11A on baseline HbF levels. Additional studies will be needed to validate these findings and explain the ample inter-individual variations in HbF levels at baseline and HU-induced in patients with SCA.


Asunto(s)
Proteínas Portadoras/genética , Hemoglobina Fetal/análisis , Hidroxiurea/farmacología , Metaloendopeptidasas/genética , Proteínas Nucleares/genética , Polimorfismo de Nucleótido Simple/fisiología , Adolescente , Adulto , Anemia de Células Falciformes/sangre , Anemia de Células Falciformes/genética , Brasil , Niño , Preescolar , Femenino , Hemoglobina Fetal/efectos de los fármacos , Humanos , Masculino , Persona de Mediana Edad , Proteínas Represoras , Adulto Joven
7.
PLoS One ; 11(3): e0151292, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26986948

RESUMEN

Different genes are associated with categorical classifications of asthma severity. However, continuous outcomes should be used to catch the heterogeneity of asthma phenotypes and to increase the power in association studies. Accordingly, the aim of this study was to evaluate the association between single nucleotide polymorphisms (SNPs) in candidate gene regions and continuous measures of asthma severity, in adult patients from the general population. In the Gene Environment Interactions in Respiratory Diseases (GEIRD) study (www.geird.org), 326 subjects (aged 20-64) with ever asthma were identified from the general population in Verona (Italy) between 2007 and 2010. A panel of 236 SNPs tagging 51 candidate gene regions (including one or more genes) was analysed. A symptom and treatment score (STS) and pre-bronchodilator FEV1% predicted were used as continuous measures of asthma severity. The association of each SNP with STS and FEV1% predicted was tested by fitting quasi-gamma and linear regression models, respectively, with gender, body mass index and smoking habits as potential confounders. The Simes multiple-test procedure was used for controlling the false discovery rate (FDR). SNP rs848 in the IL13 gene region (IL5/RAD50/IL13/IL4) was associated with STS (TG/GG vs TT genotype: uncorrected p-value = 0.00006, FDR-corrected p-value = 0.04), whereas rs20541 in the same gene region, in linkage disequilibrium with rs848 (r(2) = 0.94) in our sample, did not reach the statistical significance after adjusting for multiple testing (TC/CC vs TT: uncorrected p-value = 0.0003, FDR-corrected p-value = 0.09). Polymorphisms in other gene regions showed a non-significant moderate association with STS (IL12B, TNS1) or lung function (SERPINE2, GATA3, IL5, NPNT, FAM13A) only. After adjusting for multiple testing and potential confounders, SNP rs848 in the IL13 gene region is significantly associated with a continuous measure of symptom severity in adult subjects with ever asthma.


Asunto(s)
Asma/genética , Predisposición Genética a la Enfermedad/genética , Interleucina-13/genética , Polimorfismo de Nucleótido Simple , Adulto , Asma/patología , Asma/fisiopatología , Femenino , Frecuencia de los Genes , Genotipo , Humanos , Desequilibrio de Ligamiento , Masculino , Persona de Mediana Edad , Pruebas de Función Respiratoria/métodos , Índice de Severidad de la Enfermedad , Adulto Joven
8.
Blood Cells Mol Dis ; 55(4): 396-401, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26460265

RESUMEN

Aim of this study was to compare plasma levels of the secreted protein Klotho in ß-thalassemia major patients and in healthy controls. Also, we examined the existence of correlations between the protein level and osteoporosis, poor muscle strength and fractures. A total of 106 patients with ß-thalassemia major and 95 healthy blood donors were enrolled. Klotho level in plasma was measured by mean of an ELISA test and the hand-grip strength using a dynamometer. Intact parathyroid hormone (PTH), 25-hydroxy vitamin D (Vitamin D), serum calcium (Ca), phosphate (P), total alkaline phosphatase (ALP), ferritin, creatinine were measured by standard clinical techniques. DXA was used to measure bone mineral density (BMD) at the lumbar spine (L2-L4), femoral neck and total hip. We found that the Klotho protein concentration was lower in the blood of patients with ß-thalassemia major than in healthy controls, and it was directly correlated to the hand-grip strength. In ß-thalassemia major patients, the secreted Klotho was lower than in healthy controls. The preliminary investigation into the correlation between markers of osteo- and sarcopenia and Klotho demonstrated a decreased Klotho concentration in ß-TM patients and a higher probability of having had fragility fractures.


Asunto(s)
Glucuronidasa/sangre , Fuerza Muscular , Osteoporosis/sangre , Talasemia beta/sangre , Talasemia beta/fisiopatología , Adulto , Biomarcadores , Densidad Ósea , Huesos/metabolismo , Huesos/patología , Estudios de Casos y Controles , Femenino , Fuerza de la Mano , Humanos , Proteínas Klotho , Masculino , Persona de Mediana Edad , Osteoporosis/etiología , Fracturas Osteoporóticas/etiología , Talasemia beta/complicaciones
9.
Expert Rev Hematol ; 8(6): 851-62, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26470003

RESUMEN

Patients with thalassemia major suffer from many complications, but in the last two decades their lives have improved both in length and quality. We report herein the most common complications and the recent advances that have changed the course of this disease. Also, we report in detail some of the new therapeutic strategies already introduced in practice and briefly some that are still being developed.


Asunto(s)
Talasemia/complicaciones , Talasemia/terapia , Humanos , Talasemia/patología
10.
Pediatr Neurol ; 51(6): 790-4, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25456299

RESUMEN

BACKGROUND: Cranial ultrasonography is a useful tool to detect intracranial lesions in premature neonates at risk. Our primary aim was to determine the number of patients with abnormal cranial ultrasonography. Secondary aims were to evaluate the usefulness of universal cranial ultrasonography screening in moderately preterm infants. METHODS: All infants born from 2007 to 2012 at the University Hospital of Ferrara (Italy), with gestational age of 33-36 weeks, were included in the study. Cranial ultrasonography findings were retrospectively classified into nonsignificant and significant. RESULTS: All the 724 babies born were screened. Intracranial lesions were in 13% of neonates (3.7% at 36 weeks to 27.1% at 33 weeks of gestational age). Babies born at 33-34 weeks of gestational age were four times more likely to have an abnormal cranial ultrasonography than those at 35-36 weeks. Statistical analysis revealed no association between cranial ultrasonography abnormalities and being small for gestational age or mode of delivery. A significant association was present between the presence of head circumference less than the third percentile, the need for ventilation or surfactant, low Apgar index at fifth minute, and neurological abnormalities. The presence of at least one considered risk factor increases the probability of cranial ultrasonography abnormalities twice in infants born at 33-34 weeks and 15 times in born at 35-36 weeks. CONCLUSIONS: A considerable number of infants born between 33 and 36 weeks have cranial ultrasonography abnormalities. We suggest that screening should be performed or at least that a uniform protocol should be developed for the early detection of all significant cranial ultrasonography abnormalities.


Asunto(s)
Hemorragia Cerebral/diagnóstico por imagen , Enfermedades del Prematuro/diagnóstico por imagen , Leucomalacia Periventricular/diagnóstico por imagen , Tamizaje Neonatal/métodos , Hemorragia Cerebral/epidemiología , Femenino , Edad Gestacional , Humanos , Recién Nacido , Recien Nacido Prematuro , Enfermedades del Prematuro/epidemiología , Italia/epidemiología , Leucomalacia Periventricular/epidemiología , Masculino , Estudios Retrospectivos , Cráneo/diagnóstico por imagen , Ultrasonografía
11.
Inflamm Res ; 63(10): 851-8, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25095741

RESUMEN

OBJECTIVES AND DESIGN: Inflammation has a prominent role in the development of atherosclerosis. Type 2 diabetes could contribute to atherosclerosis development by promoting inflammation. This status might accelerate changes in intrinsic vascular wall cells and favor plaque formation. Cyclooxygenase 2 (COX-2) is highly expressed in atherosclerotic plaques. COX-2 gene expression is promoted through activation of toll-like receptor 4 (TLR4) and pro-inflammatory cytokine interleukin 1ß (IL1-ß). Aim of this study is to investigate whether expression profiles of pro-inflammatory genes such as COX-2, TLR4 and IL1-ß in atherosclerotic plaques are altered in type 2 diabetes (T2D). METHODS: Total RNA was isolated from plaques of atherosclerotic patients and expression of COX-2, TLR4, IL1-ß analyzed using real-time PCR. Histological analysis was performed on sections of the plaque to establish the degree of instability. RESULTS: Statistically significant differences in mRNA expression of COX-2 and IL1-ß were found in plaques of T2D compared with non-T2D patients. A multi-variable linear regression model suggests that COX-2 mRNA expression is affected by T2D pathology and IL1-ß mRNA expression in atherosclerotic plaques. CONCLUSIONS: Our results support the hypothesis that T2D pathology contributes in vivo to increase the inflammatory process associated with the atherosclerotic plaque formation, as shown by an increment of COX-2 and IL1-ß mRNA expression.


Asunto(s)
Ciclooxigenasa 2/genética , Diabetes Mellitus Tipo 2/genética , Interleucina-1beta/genética , Placa Aterosclerótica/genética , Receptor Toll-Like 4/genética , Anciano , Anciano de 80 o más Años , Femenino , Expresión Génica , Humanos , Masculino , Persona de Mediana Edad , ARN Mensajero/metabolismo
12.
J Chem Phys ; 137(2): 024310, 2012 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-22803539

RESUMEN

Supported by accurate quantum-chemical calculations, the rotational spectra of the mono- and bi-deuterated species of fluoroiodomethane, CHDFI and CD(2)FI, as well as of the (13)C-containing species, (13)CH(2)FI, were recorded for the first time. Three different spectrometers were employed, a Fourier-transform microwave spectrometer, a millimeter/submillimter-wave spectrometer, and a THz spectrometer, thus allowing to record a huge portion of the rotational spectrum, from 5 GHz up to 1.05 THz, and to accurately determine the ground-state rotational and centrifugal-distortion constants. Sub-Doppler measurements allowed to resolve the hyperfine structure of the rotational spectrum and to determine the complete iodine quadrupole-coupling tensor as well as the diagonal elements of the iodine spin-rotation tensor. The present investigation of rare isotopic species of CH(2)FI together with the results previously obtained for the main isotopologue [C. Puzzarini, G. Cazzoli, J. C. López, J. L. Alonso, A. Baldacci, A. Baldan, S. Stopkowicz, L. Cheng, and J. Gauss, J. Chem. Phys. 134, 174312 (2011); G. Cazzoli, A. Baldacci, A. Baldan, and C. Puzzarini, Mol. Phys. 109, 2245 (2011)] enabled us to derive a semi-experimental equilibrium structure for fluoroiodomethane by means of a least-squares fit procedure using the available experimental ground-state rotational constants together with computed vibrational corrections. Problems related to the missing isotopic substitution of fluorine and iodine were overcome thanks to the availability of an accurate theoretical equilibrium geometry (computed at the coupled-cluster singles and doubles level augmented by a perturbative treatment of triple excitations).

13.
J Chem Phys ; 134(17): 174312, 2011 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-21548692

RESUMEN

Guided by theoretical predictions, the rotational spectrum of fluoroiodomethane, CH(2)FI, has been recorded and assigned. Accurate values are reported for the ground-state rotational constants, all quartic, sextic, and two octic centrifugal-distortion constants. The hyperfine structure of the rotational spectrum was thoroughly investigated using a Fourier-transform microwave spectrometer and the Lamb-dip technique in the millimeter-/submillimeter-wave region, thus allowing the accurate determination of the complete iodine quadrupole-coupling tensor and of the diagonal elements of the iodine spin-rotation tensor. Relativistic effects turned out to be essential for the accurate theoretical prediction of the dipole moment and quadrupole-coupling constants and were accounted for by direct perturbation theory and a spin-free four-component treatment based on the Dirac-Coulomb Hamiltonian. The relativistic corrections to the dipole moment amount to up to 34% and to the iodine quadrupole-coupling tensor to about 15-16% of the total values.

14.
J Phys Chem A ; 115(4): 453-9, 2011 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-21174444

RESUMEN

A combined microwave, infrared, and computational investigation of CHBrF(2) is reported. For the vibrational ground state, measurements in the millimeter- and sub-millimeter-wave regions for CH(79)BrF(2) and CH(81)BrF(2) provided rotational and centrifugal-distortion constants up to the sextic terms as well as the hyperfine parameters (quadrupole-coupling and spin-rotation interaction constants) of the bromine nucleus. The determination of the latter was made possible by recording of spectra at sub-Doppler resolution, achieved by means of the Lamb-dip technique, and supporting the spectra analysis by high-level quantum chemical calculations at the coupled-cluster level. In this context, the importance of relativistic effects, which are of the order of 6.5% and included in the present work using second-order direct perturbation theory, needs to be emphasized for accurate predictions of the bromine quadrupole-coupling constants. The infrared measurements focused on the ν(4) fundamental band of CH(79)BrF(2). Fourier transform investigations using a synchrotron radiation source provided the necessary resolution for the observation and analysis of the rotational structure. The spectroscopic parameters of the v(4) = 1 state were found to be close to those of the vibrational ground state, indicating that the ν(4) band is essentially unaffected by perturbations.

15.
J Chem Phys ; 133(4): 044310, 2010 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-20687653

RESUMEN

The gas-phase infrared spectra of bromodifluoromethane, CHBrF(2), have been examined at medium resolution in the range of 200-9500 cm(-1). The assignment of the absorptions in terms of fundamental, overtone, combination, and hot bands, assisted by quantum chemical calculations is consistent all over the region investigated. Accurate values of integrated band intensities have also been determined for the first time in the range of 500-6000 cm(-1). Structural and molecular spectroscopic properties have been calculated at high level of theory. The coupled cluster CCSD(T) method in conjunction with a hierarchical series of correlation consistent basis sets has been employed and extrapolation to complete basis set has been considered for the equilibrium geometry. Vibrational analysis based on the second order perturbation theory has been carried out with the ab initio anharmonic force constants calculated using the second order Moller-Plesset perturbation as well as coupled cluster [CCSD(T)] theory. A good agreement between the computed and the experimental data also including the integrated infrared band intensities has been obtained.

16.
J Phys Chem A ; 113(21): 6083-90, 2009 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-19413353

RESUMEN

The gas-phase infrared spectrum of monodeuteromethyl bromide, CH2DBr, has been examined at medium resolution in the range 400-10000 cm(-1), leading to the identification of 70 vibrational transitions. The assignment of the absorptions in terms of fundamentals, overtones, combinations, and hot bands, assisted by quantum chemical calculations, is consistent all over the region investigated. The (79/81)Br isotopic splitting for the lowest fundamental nu6 and the value for the v8 = 1 level have been now precisely determined. Anharmonic resonances are very marginal for all fundamentals and the Coriolis interaction effects are clearly evident in the nu4/nu8 band system, in the nu2 and nu7 fundamentals. Spectroscopic parameters, obtained from the analysis of partially resolved rotational structure, have been derived in the symmetric tops limit approximation. High-quality ab initio calculations have been performed, and harmonic and anharmonic force fields have been predicted from coupled cluster CCSD(T) calculations employing the cc-pVTZ basis set. A good agreement between computed and experimental data, also including the C-H stretching overtones at 6000 and 9000 cm(-1), has been obtained.

17.
J Chem Phys ; 127(16): 164302, 2007 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-17979333

RESUMEN

Guided by theoretical predictions, the rotational spectra of the mono- and bideuterated species of bromofluoromethane, CDH(79)BrF, CDH(81)BrF, CD(2) (79)BrF, and CD(2) (81)BrF, have been recorded for the first time. Assignment of a few hundred rotational transitions led to the accurate determination of the ground-state rotational constants, all of the quartic and most of the sextic centrifugal distortion constants, as well as the full bromine quadrupole-coupling tensor for both (79)Br and (81)Br, in good agreement with corresponding theoretical predictions based on high-level coupled-cluster calculations. The rotational spectra of the (13)C containing species (13)CH(2) (79)BrF and (13)CH(2) (81)BrF have been observed in natural abundance and have been assigned, thus allowing the determination of the rotational and centrifugal distortion constants as well as the bromine quadrupole-coupling tensor. Furthermore, empirical equilibrium structures have been obtained within a least-squares fit procedure using the available experimental ground-state rotational constants for various isotopic species. Vibrational effects have been accounted for in the analysis using vibration-rotation interaction constants derived from anharmonic force fields computed at the second-order Moller-Plesset perturbation theory as well as coupled-cluster (CC) levels. The empirical equilibrium geometries obtained in this way agree well with the corresponding theoretical predictions obtained from CC calculations [at the CCSD(T) level] after extrapolation to the complete basis set limit and inclusion of core-valence correlation corrections and relativistic effects.

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