Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 41
Filtrar
Más filtros











Base de datos
Intervalo de año de publicación
1.
Anaesthesia ; 77(2): 185-195, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34333761

RESUMEN

We implemented the World Health Organization surgical safety checklist at Auckland City Hospital from November 2007. We hypothesised that the checklist would reduce postoperative mortality and increase days alive and out of hospital, both measured to 90 postoperative days. We compared outcomes for cohorts who had surgery during 18-month periods before vs. after checklist implementation. We also analysed outcomes during 9 years that included these periods (July 2004-December 2013). We analysed 9475 patients in the 18-month period before the checklist and 10,589 afterwards. We analysed 57,577 patients who had surgery from 2004 to 2013. Mean number of days alive and out of hospital (95%CI) in the cohort after checklist implementation was 1.0 (0.4-1.6) days longer than in the cohort preceding implementation, p < 0.001. Ninety-day mortality was 395/9475 (4%) and 362/10,589 (3%) in the cohorts before and after checklist implementation, multivariable odds ratio (95%CI) 0.93 (0.80-1.09), p = 0.4. The cohort changes in these outcomes were indistinguishable from longer-term trends in mortality and days alive and out of hospital observed during 9 years, as determined by Bayesian changepoint analysis. Postoperative mortality to 90 days was 228/5686 (4.0%) for Maori and 2047/51,921 (3.9%) for non-Maori, multivariable odds ratio (95%CI) 0.85 (0.73-0.99), p = 0.04. Maori spent on average (95%CI) 1.1 (0.5-1.7) fewer days alive and out of hospital than non-Maori, p < 0.001. In conclusion, our patients experienced improving postoperative outcomes from 2004 to 2013, including the periods before and after implementation of the surgical checklist. Maori patients had worse outcomes than non-Maori.


Asunto(s)
Lista de Verificación/tendencias , Auditoría Médica/tendencias , Alta del Paciente/tendencias , Seguridad del Paciente , Complicaciones Posoperatorias/epidemiología , Organización Mundial de la Salud , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Lista de Verificación/métodos , Femenino , Humanos , Masculino , Auditoría Médica/métodos , Persona de Mediana Edad , Complicaciones Posoperatorias/diagnóstico , Estudios Retrospectivos , Adulto Joven
2.
Am J Transplant ; 17(3): 712-723, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27597148

RESUMEN

An unbalanced microbiome may lead to disease by creating aberrant immune responses. A recent association of cellular rejection with the development of interstitial fibrosis and tubular atrophy (IFTA) suggests the role of immune-mediated tissue injury. We hypothesized that developing IFTA correlates with altered urinary tract microbiomes (UMBs). UMBs at two serial time points, 1 and 6-8 months posttransplant, were assessed by 16S microbial ribosomal gene sequencing in 25 patients developing biopsy-proven IFTA compared to 23 transplant patients with normal biopsies and excellent function (TX) and 20 healthy nontransplant controls (HC). Streptococcus, the dominant genera in HC males, was lower in IFTA and TX males at 1 month compared to HCs. At 6-8 months, Streptococcus was further decreased in IFTA males, but normalized in TX. IFTA males and females had increases in number of genera per sample at 6-8 months. UMB composition varied substantially between individuals in all groups. Despite the wide variation in UMBs between individuals, IFTA was associated with a loss in dominant resident urinary microbes in males, and a parallel increase in nonresident, pathogenic bacteria in males and females. UMB changes may contribute to IFTA development by alteration of the host immune response.


Asunto(s)
Atrofia/orina , Biomarcadores/orina , Fibrosis/orina , Rechazo de Injerto/orina , Trasplante de Riñón/efectos adversos , Túbulos Renales/patología , Enfermedades Pulmonares Intersticiales/orina , Microbiota/genética , Atrofia/etiología , Biopsia , Estudios de Casos y Controles , Femenino , Fibrosis/etiología , Estudios de Seguimiento , Tasa de Filtración Glomerular , Rechazo de Injerto/etiología , Rechazo de Injerto/patología , Supervivencia de Injerto , Humanos , Fallo Renal Crónico/complicaciones , Fallo Renal Crónico/cirugía , Pruebas de Función Renal , Túbulos Renales/metabolismo , Enfermedades Pulmonares Intersticiales/etiología , Masculino , Persona de Mediana Edad , Pronóstico , ARN Ribosómico 16S/genética , Factores de Riesgo
3.
Am J Transplant ; 16(4): 1102-12, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26603381

RESUMEN

Belatacept is a B7-specific fusion protein used to prevent allograft rejection by blocking T cell costimulation. Generally efficacious, it fails to prevent acute rejection in a sizable minority of patients. In experimental models, memory T cells mediate costimulation blockade-resistant rejection (CoBRR), but this remains undefined in humans. To explore relationships between individual patients' immune cell phenotypes and CoBRR, we studied patients receiving belatacept or conventional calcineurin inhibitor-based immunosuppression. We identified a population of CD57(+) PD1(-) CD4 T cells present prior to transplantation that correlated with CoBRR. Contrary to data recognizing CD57 as a marker of senescence on CD8 T cells, we discovered a nonsenescent, cytolytic phenotype associated with CD57 on CD4 T cells. Moreover, CD57(+) CD4 T cells expressed high levels of adhesion molecules implicated in experimental CoBRR, were CD28(-) , expressed a transcriptional phenotype broadly defining allograft rejection and were shown to be present in rejecting human kidney allografts. These data implicate CD57(+) CD4 T cells in clinical CoBRR. If prospectively validated, this characteristic could identify patients at higher risk for acute rejection on belatacept-based therapy.


Asunto(s)
Abatacept/uso terapéutico , Linfocitos T CD4-Positivos/inmunología , Antígenos CD57/metabolismo , Rechazo de Injerto/inmunología , Inmunosupresores/uso terapéutico , Trasplante de Riñón , Adulto , Aloinjertos , Resistencia a Medicamentos , Citometría de Flujo , Estudios de Seguimiento , Tasa de Filtración Glomerular , Rechazo de Injerto/prevención & control , Supervivencia de Injerto/inmunología , Humanos , Inmunohistoquímica , Memoria Inmunológica , Fallo Renal Crónico/cirugía , Pruebas de Función Renal , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Pronóstico , Factores de Riesgo
4.
Am J Transplant ; 14(3): 607-14, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24730049

RESUMEN

The CD28/cytotoxic T-lymphocyte antigen 4 (CTLA-4)blocker belatacept selectively inhibits alloreactive T cell responses but is associated with a high incidence of acute rejection following renal transplantation,which led us to investigate the etiology of belatacept­resistant graft rejection. T cells can differentiate into functionally distinct subsets of memory T cellsthat collectively enable protection against diverse classes of pathogens and can cross-react with allogeneicantigen and mediate graft rejection. T helper 17(Th17) cells are a pro-inflammatory CD4+ lineage that provides immunity to pathogens and are pathogenic in autoimmune disease. We found that T helper 1 (Th1)and Th17 memory compartments contained a similar frequency of divided cells following allogeneic stimulation.Compared to Th1 cells, Th17 memory cells expressed significantly higher levels of the coinhibitory molecule CTLA-4. Stimulation in the presence of belatacept inhibited Th1 responses but augmented Th17 cells due to greater sensitivity to coinhibition by CTLA-4. Th17 cells from renal transplant recipients were resistant to ex vivo CD28/CTLA-4 blockade with belatacept, and an elevated frequency of Th17 memory cells was associated with acute rejection during belatacept therapy. These data highlight important differences in costimulatory and coinhibitory requirements of CD4+ memory subsets, and demonstrate that the heterogeneity of pathogen-derived memory has implications for immunomodulation strategies.


Asunto(s)
Antígeno CTLA-4/antagonistas & inhibidores , Resistencia a Medicamentos/inmunología , Rechazo de Injerto/inmunología , Inmunoconjugados/farmacología , Inmunosupresores/farmacología , Trasplante de Riñón , Células Th17/inmunología , Abatacept , Antígenos CD/metabolismo , Antígeno CTLA-4/inmunología , Antígeno CTLA-4/metabolismo , Células Cultivadas , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Memoria Inmunológica/inmunología , Enfermedades Renales/inmunología , Enfermedades Renales/terapia , Activación de Linfocitos , Masculino , Persona de Mediana Edad , Pronóstico , Células Th17/metabolismo
5.
Am J Transplant ; 14(5): 1142-51, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24684552

RESUMEN

Kidney transplantation remains limited by toxicities of calcineurin inhibitors (CNIs) and steroids. Belatacept is a less toxic CNI alternative, but existing regimens rely on steroids and have higher rejection rates. Experimentally, donor bone marrow and sirolimus promote belatacept's efficacy. To investigate a belatacept-based regimen without CNIs or steroids, we transplanted recipients of live donor kidneys using alemtuzumab induction, monthly belatacept and daily sirolimus. Patients were randomized 1:1 to receive unfractionated donor bone marrow. After 1 year, patients were allowed to wean from sirolimus. Patients were followed clinically and with surveillance biopsies. Twenty patients were transplanted, all successfully. Mean creatinine (estimated GFR) was 1.10 ± 0.07 mg/dL (89 ± 3.56 mL/min) and 1.13 ± 0.07 mg/dL (and 88 ± 3.48 mL/min) at 12 and 36 months, respectively. Excellent results were achieved irrespective of bone marrow infusion. Ten patients elected oral immunosuppressant weaning, seven of whom were maintained rejection-free on monotherapy belatacept. Those failing to wean were successfully maintained on belatacept-based regimens supplemented by oral immunosuppression. Seven patients declined immunosuppressant weaning and three patients were denied weaning for associated medical conditions; all remained rejection-free. Belatacept and sirolimus effectively prevent kidney allograft rejection without CNIs or steroids when used following alemtuzumab induction. Selected, immunologically low-risk patients can be maintained solely on once monthly intravenous belatacept.


Asunto(s)
Corticoesteroides/uso terapéutico , Inhibidores de la Calcineurina/uso terapéutico , Rechazo de Injerto/prevención & control , Inmunoconjugados/uso terapéutico , Inmunosupresores/uso terapéutico , Fallo Renal Crónico/cirugía , Trasplante de Riñón , Abatacept , Adulto , Anciano , Manejo de la Enfermedad , Femenino , Citometría de Flujo , Estudios de Seguimiento , Supervivencia de Injerto/efectos de los fármacos , Humanos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/prevención & control , Pronóstico , Sirolimus/uso terapéutico , Adulto Joven
6.
Am J Transplant ; 14(2): 319-32, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24472192

RESUMEN

Tacrolimus impairs allo- and viral-specific T cell responses. Belatacept, a costimulation-based alternative to tacrolimus, has emerged with a paradoxical picture of less complete control of alloimmunity with concomitant impaired viral immunity limited to viral-naïve patients. To reconcile these signatures, bulk population and purified memory and naïve lymphocytes from cytomegalovirus (CMV)-seropositive (n=10) and CMV-seronegative (n=10) volunteers were studied using flow cytometry, interrogating proliferation (carboxyfluorescein succinimidyl ester dilution) and function (intracellular cytokine staining) in response to alloantigens or CMV-pp-65 peptides. As anticipated, T cells from CMV-experienced, but not naïve, individuals responded to pp-65 with a small percentage of their repertoire (<2.5%) consisting predominantly of mature, polyfunctional (expressing interferon gamma, tumor necrosis factor alpha and IL-2) T effector memory cells. Both CMV naïve and experienced individuals responded similarly to alloantigen with a substantially larger percentage of the repertoire (up to 48.2%) containing proportionately fewer polyfunctional cells. Tacrolimus completely inhibited responses of CMV- and allo-specific T cells regardless of their maturation. However, belatacept's effects were decreasingly evident in increasingly matured cells, with minimal effect on viral-specific triple cytokine producers and CD28-negative allo-specific cells. These data indicate that belatacept's immunosuppressive effect, unlike tacrolimus's, wanes on progressively developed effector responses, and may explain the observed clinical effects of belatacept.


Asunto(s)
Infecciones por Citomegalovirus/inmunología , Inmunoconjugados/farmacología , Memoria Inmunológica/inmunología , Inmunosupresores/farmacología , Activación de Linfocitos/inmunología , Linfocitos T/inmunología , Tacrolimus/farmacología , Abatacept , Estudios de Casos y Controles , Citomegalovirus/inmunología , Infecciones por Citomegalovirus/tratamiento farmacológico , Infecciones por Citomegalovirus/virología , Citometría de Flujo , Humanos , Tolerancia Inmunológica/efectos de los fármacos , Tolerancia Inmunológica/inmunología , Memoria Inmunológica/efectos de los fármacos , Interferón gamma/metabolismo , Isoantígenos/inmunología , Activación de Linfocitos/efectos de los fármacos , Fragmentos de Péptidos/inmunología , Fosfoproteínas/inmunología , Linfocitos T/citología , Linfocitos T/efectos de los fármacos , Linfocitos T/virología , Proteínas de la Matriz Viral/inmunología
7.
Am J Transplant ; 11(10): 2228-34, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21812928

RESUMEN

Renal transplant recipients require periodic surveillance for immune-based complications such as rejection and infection. Noninvasive monitoring methods are preferred, particularly for children, for whom invasive testing is problematic. We performed a cross-sectional analysis of adult and pediatric transplant recipients to determine whether a urine-based chemokine assay could noninvasively identify patients with rejection among other common clinical diagnoses. Urine was collected from 110 adults and 46 children with defined clinical conditions: healthy volunteers, stable renal transplant recipients, and recipients with clinical or subclinical acute rejection (AR) or BK infection (BKI), calcineurin inhibitor (CNI) toxicity or interstitial fibrosis (IFTA). Urine was analyzed using a solid-phase bead-array assay for the interferon gamma-induced chemokines CXCL9 and CXCL10. We found that urine CXCL9 and CXCL10 were markedly elevated in adults and children experiencing either AR or BKI (p = 0.0002), but not in stable allograft recipients or recipients with CNI toxicity or IFTA. The sensitivity and specificity of these chemokine assays exceeded that of serum creatinine. Neither chemokine distinguished between AR and BKI. These data show that urine chemokine monitoring identifies patients with renal allograft inflammation. This assay may be useful for noninvasively distinguishing those allograft recipients requiring more intensive surveillance from those with benign clinical courses.


Asunto(s)
Virus BK/aislamiento & purificación , Biomarcadores/orina , Quimiocina CXCL10/orina , Quimiocina CXCL9/orina , Rechazo de Injerto/orina , Trasplante de Riñón , Infecciones por Polyomavirus/orina , Estudios de Casos y Controles , Femenino , Humanos , Inmunosupresores/administración & dosificación , Masculino , Trasplante Homólogo
8.
New Phytol ; 183(3): 764-775, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19549131

RESUMEN

The tropical intertidal ecosystem is defined by trees - mangroves - which are adapted to an extreme and extremely variable environment. The genetic basis underlying these adaptations is, however, virtually unknown. Based on advances in pyrosequencing, we present here the first transcriptome analysis for plants for which no prior genomic information was available. We selected the mangroves Rhizophora mangle (Rhizophoraceae) and Heritiera littoralis (Malvaceae) as ecologically important extremophiles employing markedly different physiological and life-history strategies for survival and dominance in this extreme environment. For maximal representation of conditional transcripts, mRNA was obtained from a variety of developmental stages, tissues types, and habitats. For each species, a normalized cDNA library of pooled mRNAs was analysed using GSFLX pyrosequencing. A total of 537,635 sequences were assembled de novo and annotated as > 13,000 distinct gene models for each species. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology annotations highlighted remarkable similarities in the mangrove transcriptome profiles, which differed substantially from the model plants Arabidopsis and Populus. Similarities in the two species suggest a unique mangrove lifestyle overarching the effects of transcriptome size, habitat, tissue type, developmental stage, and biogeographic and phylogenetic differences between them.


Asunto(s)
Perfilación de la Expresión Génica , Rhizophoraceae/genética , Mapeo Contig , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , ARN Mensajero/genética , ARN Mensajero/metabolismo , Análisis de Secuencia de ADN
9.
Anaesthesia ; 63(12): 1349-57, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19032305

RESUMEN

SUMMARY: It is notoriously difficult to obtain evidence from clinical randomised controlled trials for safety innovations in healthcare. We have developed a research design using simulation for the evaluation of safety initiatives in anaesthesia. We used a standard and a modified scenario in a human-patient simulator, involving a potentially life-threatening problem requiring prompt attention--either a cardiac arrest or a failure in oxygen supply. The modified scenarios involved distractions such as loud music, a demanding and uncooperative surgeon, telephone calls and frequent questions from a medical student. Twenty anaesthetics were administered by 10 anaesthetists. A mean (SD) of 11.3 (2.8) errors per anaesthetic were identified in the oxygen failure scenarios, compared with 8.0 (3.4) in the cardiac arrest scenarios (ANOVA: p = 0.04). The difference between the combined standard scenarios and the combined modified scenarios was not significant. The mean rate of errors overall was 9.7 per simulation, with a pooled SD of 4.46, so in future studies 21 subjects would provide 80% statistical power to show a reduction in error rate of 30% from baseline with p

Asunto(s)
Anestesia/normas , Simulación por Computador , Administración de la Seguridad/métodos , Adulto , Anciano , Anestesia/efectos adversos , Anestesiología/instrumentación , Competencia Clínica , Falla de Equipo , Femenino , Paro Cardíaco/terapia , Humanos , Masculino , Errores Médicos/prevención & control , Nueva Zelanda , Terapia por Inhalación de Oxígeno/instrumentación , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Proyectos de Investigación
10.
J Nat Prod ; 71(2): 285-8, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18211006

RESUMEN

We report the determination of the absolute configuration (AC) of the iridoid natural product oruwacin by comparison of the optical rotations, [alpha] D, of its two enantiomers, calculated using time-dependent density functional theory (TDDFT), to the experimental [alpha] D value, +193. Conformational analysis of oruwacin using density functional theory (DFT) identifies eight conformations which are significantly populated at room temperature. [alpha] D values of these eight conformations are calculated using TDDFT at the B3LYP/aug-cc-pVDZ//B3LYP/6-31G* level, leading to the conformationally averaged [alpha] D values of -193 for the (1 R,5 S,8 S,9 S,10 S)-enantiomer and +193 for the (1 S,5 R,8 R,9 R,10 R)-enantiomer. Comparison of the calculated [alpha] D values to the value of the natural product proves that naturally occurring oruwacin has the AC 1 S,5 R,8 R,9 R,10 R. This AC is opposite to that assigned by Adesogan by comparison of the [alpha] D of oruwacin to that of the iridoid plumericin. Our results show that the assignment of the AC of a natural product by comparison of its [alpha] D to that of a chemically related molecule can be unreliable and should not be assumed to be definitive.


Asunto(s)
Productos Biológicos/química , Iridoides/química , Estructura Molecular , Morinda/química , Hojas de la Planta/química , Estereoisomerismo
11.
Anaesthesia ; 62(11): 1114-20, 2007 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-17924891

RESUMEN

In a prospective, observational trial, we investigated the influence of time of day on the duration of neuromuscular blockade (NMB) elicited by rocuronium. Forty-nine patients scheduled for surgery between 08:00 and 02:00 were enrolled after giving written informed consent. Time to neuromuscular recovery was measured following three doses: (1) a fat-free-mass (FFM) related induction dose (0.6 mg x kg(-1): n = 47); (2) a maintenance dose (20% of the induction dose: n = 42); and (3) a standard 10-mg dose (n = 35). The extent of NMB was dependent on the time of administration (p = 0.038 General Linear Model Analysis). The maximum effect of 50 min (95% CI 41-59 min) was elicited between 08:00 and 11:00 and the minimum duration of 29 min (95% CI 23-35 min) between 14:00 and 17:00 (p = 0.005). A similar pattern was observed for the maintenance dose. The duration of action of rocuronium is influenced by time of day and this effect is of potential clinical significance and practical relevance to research.


Asunto(s)
Androstanoles/farmacología , Ritmo Circadiano/fisiología , Unión Neuromuscular/efectos de los fármacos , Fármacos Neuromusculares no Despolarizantes/farmacología , Adulto , Anciano , Androstanoles/administración & dosificación , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Masculino , Persona de Mediana Edad , Bloqueo Neuromuscular , Unión Neuromuscular/fisiología , Fármacos Neuromusculares no Despolarizantes/administración & dosificación , Estudios Prospectivos , Rocuronio , Factores de Tiempo
12.
Poult Sci ; 85(11): 1907-11, 2006 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-17032822

RESUMEN

Cytokines are secreted proteins involved with cell recruitment and regulation of both innate and adaptive immune responses. They are essential for an effective host immune response to pathogens. The objective of this study was to determine the effect of Salmonella enterica serovar Enteritidis (S. Enteritidis) exposure and genetic line on cytokine mRNA expression level of cultured chicken peripheral blood mononuclear cells (PBMC). Interleukin-2, interleukin-6 (IL-6), CXCLi2, and transforming growth factor-beta4 (TGF-B4) messenger ribonucleic acid expression was measured by quantitative reverse transcription-PCR assays in PBMC from 3 chicken lines (broiler, Leghorn, Fayoumi) after in vitro exposure to S. Enteritidis. The PBMC were isolated from uninfected birds and cultured overnight. The next day, live pathogenic S. Enteritidis was added to half of the cultures. All cultures were harvested after 2 or 4 h of exposure. Exposure to S. Enteritidis downregulated IL-6, CXCLi2, and TGF-beta4 but not interleukin-2 mRNA expression. No significant genetic line or exposure time effects were detected. These findings demonstrate that exposure of chicken PBMC to S. Enteritidis can induce a rapid change in both proinflammatory (IL-6, CXCLi2) and antiinflammatory (TGF-beta4) cytokine gene expression.


Asunto(s)
Pollos , Citocinas/biosíntesis , Leucocitos Mononucleares/inmunología , ARN Mensajero/metabolismo , Salmonella enteritidis , Animales , Regulación de la Expresión Génica , Interleucina-2/biosíntesis , Interleucina-6/biosíntesis , Leucocitos Mononucleares/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/veterinaria , Salmonella enteritidis/patogenicidad , Factor de Crecimiento Transformador beta/biosíntesis
13.
J Org Chem ; 70(10): 3903-13, 2005 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-15876078

RESUMEN

[reaction: see text] The Baeyer-Villiger oxidation of (+)-(1R,5S)-bicyclo[3.3.1]nonane-2,7-dione, 1, can lead to four keto-lactone products, 2a-d. A single isomer is obtained experimentally. We have used IR and VCD spectroscopies to identify the structure of this product. DFT calculations of the IR and VCD spectra of 2a-d show unambiguously that the experimental product is (+)-(1R,6R)-2a, and not the expected product 2b. NMR studies, including comparison of DFT and experimental 1H and 13C spectra, support this conclusion. This work provides the first example of the use of VCD spectroscopy to discriminate between structural isomers of a chiral molecule. The specific rotation of (+)-(1R,6R)-2a, predicted using TDDFT methods, is negative demonstrating that absolute configurations determined from TDDFT calculations of specific rotations are not 100% reliable.

14.
Chirality ; 17 Suppl: S52-64, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15747317

RESUMEN

The absolute configuration (AC) of a chiral molecule can be determined via calculation of its specific rotation. Currently, the latter is most accurately carried out using the TDDFT/GIAO methodology. Here we examine the reliability of this methodology in determining ACs of molecules with small specific rotations. We report TDDFT/GIAO B3LYP/aug-cc-pVDZ//B3LYP/6-31G* calculations of the sodium D line specific rotations, [alpha]D, of 65 conformationally rigid chiral molecules whose experimental [alpha]D values are small (<100). The RMS deviations, sigma, of calculated and experimental [alpha]D values is 28.9. The distribution of deviations is approximately Gaussian, i.e., random. For eight molecules, more than 10% of the set, the sign of the predicted [alpha]D is incorrect. In determining an AC of a rigid molecule from [alpha]D with 95% confidence, the calculated [alpha]D value must lie within +/-2sigma of the experimental [alpha]D for one, but not both, of the possible ACs. For the 65 molecules of this study +/-2sigma is 57.8. For conformationally flexible molecules, the error bar is +/- >57.8.

15.
J Org Chem ; 69(25): 8709-17, 2004 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-15575747

RESUMEN

The recently developed Gauge-Invariant (Including) Atomic Orbital (GIAO) based Time-Dependent Density Functional Theory (TDDFT) methodology for the calculation of transparent spectral region optical rotations of chiral molecules provides a new approach to the determination of absolute configurations. Here, we discuss the application of the TDDFT/GIAO methodology to chiral alkanes. We report B3LYP/aug-cc-pVDZ calculations of the specific rotations of the 22 chiral alkanes, 2-23, of well-established Absolute Configuration. The average absolute deviation of calculated and experimental [alpha](D) values for molecules 2-22 is 24.8. In two of the molecules 2-23, trans-pinane, 10, and endo-isocamphane, 13, the sign of [alpha](D) is incorrectly predicted. Our results demonstrate that absolute configurations of alkanes can be reliably assigned by using B3LYP/aug-cc-pVDZ TDDFT/GIAO calculations if, but only if, [alpha](D) is significantly greater than 25. In the case of (-)-anti-trans-anti-trans-anti-trans-perhydrotriphenylene, 1, [alpha](D) is -93 and TDDFT/GIAO calculations reliably lead to the absolute configuration R(-).

16.
Poult Sci ; 83(6): 911-6, 2004 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15206617

RESUMEN

To determine the role of genetics in baseline lymphocyte parameters, several distinct lines of chickens were examined for differences in peripheral blood leukocyte (PBL) populations. Four highly inbred chicken lines (MHC congenic Fayoumi lines M15.2 and M5.1, and MHC congenic Leghorn lines G-B1 and G-B2), two advanced intercrosses [F5 (Broiler x G-B2) and F5 (Broiler x M15.2)], and an outbred population of broilers were used. Leukocytes isolated from healthy adult birds were labeled with monoclonal antibodies: chCD3, chCD4, chCD8, chBu-1, and hCD14. Flow cytometry was used to determine the total percentage of positively labeled cells for each surface marker in a sample, as well as the mean fluorescent intensity, or surface marker density, of a labeled subset. Significant line differences for percentage positive CD3 T cells and the ratio of B cells:T cells (represented by the Bu-1:CD3 ratio) were found. The effect of line was also significant for CD3 and CD8 T cell receptor density. Effects of sex and MHC on PBL cell surface marker expression were not significant in the lines examined. This study demonstrates the effect of genetic line on resting leukocyte composition of peripheral blood in the chicken lines examined. Observed PBL differences add to our growing knowledge of the varied roles that immune system status (defined by specific cell populations) and genetic background have in determining susceptibility and disease progression in chickens.


Asunto(s)
Antígenos de Superficie/análisis , Pollos/sangre , Pollos/genética , Leucocitos Mononucleares/inmunología , Animales , Anticuerpos Monoclonales , Complejo CD3/análisis , Antígenos CD4/análisis , Antígenos CD8/análisis , Cruzamientos Genéticos , Citometría de Flujo , Endogamia , Recuento de Leucocitos , Receptores de Lipopolisacáridos/análisis
17.
J Am Chem Soc ; 126(24): 7514-21, 2004 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-15198598

RESUMEN

The technique of time-dependent density functional theory (TDDFT) has very recently been applied to the calculation of both transparent spectral region optical rotations and electronic circular dichroism (CD). Here, we report the concerted application of the new methodologies to the determination of the absolute configuration (AC) of [3(2)](1,4)barrelenophanedicarbonitrile, 1, the first optically active barrelenophane. 1 is conformationally flexible: the two three-carbon bridges of 1 can each exhibit two conformations, leading to three inequivalent conformations of 1: a, b, and c. Conformational structures and energies are predicted using DFT at the B3LYP/6-31G level. Comparison of the calculated structures to structures obtained via X-ray crystallography of (+)-1 shows that (remarkably) all three conformations a-c are simultaneously present in crystalline (+)-1. The sodium D line specific rotations, [alpha](D), and CD spectra of a-c are calculated using TDDFT at the B3LYP/aug-cc-pVDZ level. Comparison of the conformationally averaged specific rotation and CD spectrum to the experimental data of Matsuda-Sentou and Shinmyozu leads to the AC 9S,12S(+)/9R,12R(-). The same AC is obtained both from [alpha](D) and from the CD, strongly supporting its reliability.

18.
J Org Chem ; 69(6): 1948-58, 2004 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-15058939

RESUMEN

The concerted use of ab initio time-dependent density functional theory (TDDFT) calculations of transparent spectral region optical rotation and of circular dichroism has recently become practicable, permitting the concerted use of transparent spectral region optical rotation and circular dichroism in determining the absolute configurations of chiral molecules. Here, we report concerted TDDFT calculations of the transparent spectral region specific rotations and of the circular dichroism spectra originating in n --> pi C=O group excitations of four bicyclo[3.3.1]nonane diones, 1-4. Comparison to experiment yields absolute configurations for 1-4. For each dione, specific rotations and circular dichroism spectra give identical absolute configurations. Our results are consistent with previous work, with the exception of the Octant Rule-derived absolute configuration of the 2,9-dione.

19.
Chirality ; 15 Suppl: S57-64, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12884375

RESUMEN

Ab initio Density Functional Theory (DFT) calculations of transparent spectral region, discrete frequency specific rotations were used to assign the absolute configurations (ACs) of: 1, 2H-naphtho[1,8-bc]thiophene 1-oxide; 2, m-F-phenyl glycidic acid methyl ester; 3, o-Br-phenyl glycidic acid methyl ester; 4, p-CH(3)-phenyl glycidic acid methyl ester; 5, 2-(1-hydroxyethyl)-chromen-4-one; and 6, 6-Br-2-(1-hydroxyethyl)-chromen-4-one. The ACs of 5 and 6 were previously determined via X-ray crystallography to be: 5, R(-)/S(+); 6, R(+)/S(-). The ACs obtained using [alpha](D) are the same for both 5 and 6: R(+)/S(-). We conclude that the previously reported AC of 5 is incorrect.

20.
Org Lett ; 4(26): 4595-8, 2002 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-12489938

RESUMEN

[structure: see text] We report the first determinations of the absolute configurations (ACs) of chiral molecules using discrete frequency, transparent spectral region optical rotations calculated using density functional theory (DFT). The ACs of 2H-naphtho[1,8-bc]thiophene 1-oxide (3), naphtho[1,8-cd]-1,2-dithiole 1-oxide (4), and 9-phenanthryl methyl sulfoxide (5) are determined by comparison of their specific rotations to values calculated via the time-dependent DFT/gauge-invariant atomic orbital (TDDFT/GIAO) methodology using the B3LYP functional and the aug-cc-pVDZ basis set.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA