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BACKGROUND: Hispanics comprise the most rapidly growing demographic in the US, but little is known about the cardiometabolic risk factors in Hispanic children. This study examined the association of high waist circumference (WC) and elevated blood pressure by race/ethnicity in a cohort of 9 to 13 year olds in New Haven, CT (n = 824). METHODS: WC, overweight status and blood pressure were measured in 2009, with follow-up in 2011. RESULTS: Logistic regression revealed that Hispanic children had increased likelihood of elevated blood pressure at follow-up. High baseline WC was associated with increased likelihood of elevated blood pressure for non-Hispanic White but not Hispanic or non-Hispanic Black pre-adolescents, controlling for baseline age, gender, overweight, and blood pressure. CONCLUSION: Potential racial/ethnic differences in the association between high WC and elevated blood pressure may impact identification of children at risk for elevated blood pressure, especially among Hispanics.
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Negro o Afroamericano/estadística & datos numéricos , Presión Sanguínea , Hispánicos o Latinos/estadística & datos numéricos , Circunferencia de la Cintura , Población Blanca/estadística & datos numéricos , Adolescente , Biomarcadores/sangre , Índice de Masa Corporal , Niño , Femenino , Estudios de Seguimiento , Humanos , Modelos Logísticos , Estudios Longitudinales , Masculino , Factores de RiesgoRESUMEN
BACKGROUND: Although body mass index (BMI) and waist circumference (WC) are correlated, the relationship between WC and BMI may have changed over time. OBJECTIVES: To describe temporal trends in BMI and WC distributions and quantify the increase in WC at a given BMI over time. SUBJECTS/METHODS: Data on adults aged 20-59 years from two waves (1993 and 2009) of the China Health and Nutrition Survey were used in a pooled cross-sectional analysis. Quantile regression examined age-adjusted temporal trends in the distributions of BMI and WC. Linear regression examined changes in mean WC over time, adjusting for BMI, age at survey and survey year. All models were stratified by gender. RESULTS: There was a significant increase in BMI and WC over time, particularly at the 95th quantile: on average, men had 2.8 kg m(-2) (95% confidence interval (CI): 2.4, 3.3) and women 1.5 kg m(-)(2) (95% CI: 1.1, 2.0) higher BMI in 2009 compared with their counterparts in 1993. WC increased by 9.0 cm (95% CI: 7.5, 10.1) and 5.0 cm (95% CI: 3.4, 6.6) for men and women, respectively. On average, men and women had a 3.2 cm (95% CI: 2.8, 3.7) and 2.1 cm (95% CI: 1.7, 2.5) higher WC in 2009 compared with their counterparts in 1993, holding BMI and age constant. WC adjusted for BMI increased to a larger extent among obese versus lean individuals and among younger versus older women. CONCLUSIONS: For both genders, BMI and WC increased significantly over time, with particularly greatest increase in magnitude in the upper tail of the BMI and WC distributions. Furthermore, WC at equivalent BMIs was higher in 2009, compared with their counterparts in 1993. Our findings suggest that even if BMI remained constant from 1993 to 2009, adults in 2009 might be at increased cardiometabolic risk as a result of their higher WC.
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Pueblo Asiatico/estadística & datos numéricos , Enfermedades Cardiovasculares/epidemiología , Diabetes Mellitus Tipo 2/epidemiología , Síndrome Metabólico/epidemiología , Obesidad Abdominal/epidemiología , Circunferencia de la Cintura , Adulto , Distribución de la Grasa Corporal , Índice de Masa Corporal , Enfermedades Cardiovasculares/sangre , Enfermedades Cardiovasculares/prevención & control , China/epidemiología , Estudios Transversales , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/prevención & control , Femenino , Humanos , Estilo de Vida , Masculino , Síndrome Metabólico/sangre , Síndrome Metabólico/prevención & control , Persona de Mediana Edad , Encuestas Nutricionales , Obesidad Abdominal/sangre , Obesidad Abdominal/prevención & control , Prevalencia , Estudios Prospectivos , Factores de Riesgo , Factores de TiempoAsunto(s)
Actividades Cotidianas , Dieta Mediterránea , Conducta Alimentaria , Estado de Salud , Salud , Calidad de Vida , Femenino , Humanos , MasculinoRESUMEN
An integrated arrayed-waveguide grating fabricated in silicon-oxynitride technology is applied to Raman spectroscopy. After its validation by reproducing the well-known spectrum of cyclohexane, polarized Raman spectra are measured of extracted human teeth containing localized initial carious lesions. Excellent agreement is obtained between the spectra of healthy and carious tooth enamel measured with our integrated device and spectra recorded using a conventional Raman spectrometer. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers, e.g. for the detection of dental caries at an early stage.
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Espectrometría Raman/instrumentación , Caries Dental/diagnóstico , Caries Dental/metabolismo , Esmalte Dental/química , Humanos , Fenómenos ÓpticosRESUMEN
The 'gold standard' vaccine against Marek's disease in poultry is the CVI988/Rispens virus, which is not easily distinguishable, antigenically or genetically, from virulent Marek's disease herpesvirus. Accurate differential measurement of the CVI988 vaccine and virulent viruses is important to investigate mechanisms of vaccinal protection. Minimal sequence differences between CVI988 and virulent MDV strains restrict the application of molecular diagnostic methods such as real-time PCR to distinguish between these viruses. The use of bacterial-artificial-chromosome (BAC) cloned CVI988 virus, which carries the BAC vector sequences in place of the U(s)2 gene, allows its differential quantification from virulent strains using real-time PCR assays that target the BAC vector sequence and the U(S)2 gene respectively. These novel assays allowed investigation of replication of both serotype-1 vaccine virus (cloned CVI988) and challenge virus (RB-1B strain) in tissues of individual chickens in an experimental vaccination-challenge model of Marek's disease.
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ADN Viral/análisis , Mardivirus/genética , Vacunas contra la Enfermedad de Marek/genética , Enfermedad de Marek/virología , Reacción en Cadena de la Polimerasa/veterinaria , Enfermedades de las Aves de Corral/virología , Animales , Pollos , Mardivirus/inmunología , Enfermedad de Marek/inmunología , Vacunas contra la Enfermedad de Marek/inmunología , Enfermedades de las Aves de Corral/inmunologíaRESUMEN
Explantation of failed dental implants has traditionally been performed by mechanical bone removal techniques. The advent of intraoral laser surgery has seen increasing numbers of applications in oral implantology. The technique demonstrates safe and efficient explantation of a failed dental implant using Er,Cr:YSGG laser. Laser assisted explantation of dental implants is a minimally invasive technique providing an alternative to conventional mechanical explantation techniques.
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Implantes Dentales , Fracaso de la Restauración Dental , Terapia por Láser , Láseres de Estado Sólido/uso terapéutico , Pérdida de Hueso Alveolar/etiología , Coronas , Pilares Dentales , Remoción de Dispositivos , Femenino , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Procedimientos Quirúrgicos Mínimamente Invasivos , Periodontitis/etiologíaRESUMEN
A widely used vaccine against Marek's disease (MD) in poultry is the virus SB-1, which is antigenically-related to the causative agent, Marek's disease herpesvirus. We recently cloned the SB-1 genome as an infectious bacterial artificial chromosome, BAC, (pSB-1). The protective efficacies and replication kinetics of pSB-1 and the parent strain (SB-1) were compared in an experimental model of MD induced by a virulent strain, RB-1B. Although vaccine virus replication and shedding was lower for pSB-1 than for SB-1, both vaccines reduced replication and shedding of RB-1B, and were equally effective in protecting chickens against MD. With the cloning of pSB-1, we have now generated full length genomic clones of MD vaccine virus strains belonging to each of the three serotypes. Vaccine viruses derived from each of these clones demonstrated protective efficacies at levels similar to those produced by the respective parent viruses, demonstrating their suitability to be used as vaccine candidates.
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Herpesvirus Gallináceo 2/patogenicidad , Vacunas contra la Enfermedad de Marek/inmunología , Enfermedad de Marek/prevención & control , Vacunas de ADN/inmunología , Replicación Viral/fisiología , Esparcimiento de Virus/fisiología , Animales , Pollos , Cromosomas Artificiales Bacterianos , Clonación Molecular , ADN Recombinante , ADN Viral/genética , Enfermedad de Marek/virología , VirulenciaRESUMEN
Abstract Natural infection with Marek's disease virus occurs through the respiratory mucosa after chickens inhale dander shed from infected chickens. The early events in the lung following exposure to the feather and squamous epithelial cell debris containing the viral particles remain unclear. In order to elucidate the virological and immunological consequences of MDV infection for the respiratory tract, chickens were infected by intratracheal administration of infective dander. Differences between susceptible and resistant chickens were immediately apparent, with delayed viral replication and earlier onset of interferon (IFN)-gamma production in the latter. CD4(+) and CD8(+) T cells surrounded infected cells in the lung. Although viral replication was evident in macrophages, pulmonary B cells were the main target cell type in susceptible chickens following intratracheal infection with MDV. In accordance, depletion of B cells curtailed viremia and substantially affected pathogenesis in susceptible chickens. Together the data described here demonstrate the role of pulmonary B cells as the primary and predominant target cells and their importance for MDV pathogenesis.
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Linfocitos B/virología , Pollos/virología , Herpesvirus Gallináceo 2/fisiología , Pulmón/virología , Enfermedad de Marek/virología , Replicación Viral , Animales , Bolsa de Fabricio/inmunología , Pollos/inmunología , Citocinas/biosíntesis , Citocinas/genética , ADN Viral/análisis , Relación Dosis-Respuesta Inmunológica , Plumas/virología , Femenino , Predisposición Genética a la Enfermedad , Herpesvirus Gallináceo 2/aislamiento & purificación , Insuflación , Pulmón/inmunología , Pulmón/patología , Depleción Linfocítica , Subgrupos Linfocitarios/inmunología , Enfermedad de Marek/inmunología , Enfermedad de Marek/patología , Piel/virología , Bazo/inmunología , Bazo/patología , Bazo/virología , Linfocitos T/inmunología , Factores de Tiempo , Tráquea , Carga ViralRESUMEN
BACKGROUND: This study evaluates surgical outcomes and survival rates of implants placed in a multidisciplinary implant teaching programme. METHODS: A retrospective review of all implant surgery performed over a 6-year period by accredited oral and maxillofacial surgery trainees at the Royal Dental Hospital of Melbourne was undertaken. Patients were reviewed for a minimum of 6 months post-implant placement. Implant survival was defined as those implants which were not removed, were clinically integrated as assessed by torque testing and in an appropriate position to receive a subsequent prosthesis. Kaplan-Meier analysis was used to assess overall survival and univariate factors affecting survival. Multivariate analysis used Cox proportional hazards models. RESULTS: Over 6 years, 127 patients were treated. Follow-up data were present for 105 patients with 236 implants placed. Survival of implants at 1 and 5 years was 94 per cent and 92.8 per cent, respectively. The only univariate and multivariate factor which affected implant survival was perioperative bone grafting. All failed implants were single stage. Other factors such as patient age, smoking status, implant site, anaesthetic type, immediate or delayed placement, implant length and diameter, and medical comorbidities did not significantly affect implant survival. CONCLUSIONS: A satisfactory implant survival rate was found in a tertiary teaching centre. Perioperative bone grafting significantly increased the risk of implant failure.
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Trasplante Óseo/efectos adversos , Implantación Dental Endoósea , Implantación Dental/educación , Estudiantes de Odontología , Cirugía Bucal/educación , Adolescente , Adulto , Anciano , Pérdida de Hueso Alveolar/diagnóstico por imagen , Competencia Clínica , Auditoría Odontológica , Implantación Dental Endoósea/métodos , Implantes Dentales , Diseño de Prótesis Dental , Fracaso de la Restauración Dental , Femenino , Hospitales de Enseñanza , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Radiografía , Estudios Retrospectivos , Factores de Riesgo , Resultado del Tratamiento , Adulto JovenRESUMEN
The use of a sampling technique is described for the identification of metals from inorganic pigments in paint. The sampling technique involves gently contacting a cotton swab with the painted surface to physically remove a minute quantity ( approximately 1-2mug) of pigment. The amount of material removed from the painted surface is invisible to the unaided eye and does not cause any visible effect to the painted surface. The cotton swab was then placed in a 1.5ml polystyrene beaker containing HNO(3) to extract pigment metals prior to analysis using graphite furnace atomic absorption spectrometry (GFAAS). GFAAS is well suited for identifying pigment metals since it requires small samples and many pigments consist of main group elements (e.g. Al) as well as transition metals (e.g. Zn, Fe and Cd). Using Cd (cadmium red) as the test element, the reproducibility of sampling a paint surface with the cotton swab was approximately 13% in either a water or oil medium. To test the feasibility of cotton sampling for pigment identification, samples were obtained from paintings (watercolour and oil) of a local collection. Raman spectra provided complementary information to the GFAAS, which together are essential for positive identification of some pigments. For example, GFAAS indicated the presence of Cu, but the Raman spectra positively identified the modern copper pigment phthalocyanine green (Cu(C(32)Cl(16)N(8)). Both Raman spectroscopy and GFAAS were useful for identifying ZnO as a white pigment.
RESUMEN
Rapid identification of microbial pathogens reduces infection-related morbidity and mortality of hospitalized patients. Raman spectra and Fourier transform infrared (IR) spectra constitute highly specific spectroscopic fingerprints of microorganisms by which they can be identified. Little biomass is required, so that spectra of microcolonies can be obtained. A prospective clinical study was carried out in which the causative pathogens of bloodstream infections in hospitalized patients were identified. Reference libraries of Raman and IR spectra of bacterial and yeast pathogens highly prevalent in bloodstream infections were created. They were used to develop identification models based on linear discriminant analysis and artificial neural networks. These models were tested by carrying out vibrational spectroscopic identification in parallel with routine diagnostic phenotypic identification. Whereas routine identification has a typical turnaround time of 1 to 2 days, Raman and IR spectra of microcolonies were collected 6 to 8 h after microbial growth was detected by an automated blood culture system. One hundred fifteen samples were analyzed by Raman spectroscopy, of which 109 contained bacteria and 6 contained yeasts. One hundred twenty-one samples were analyzed by IR spectroscopy. Of these, 114 yielded bacteria and 7 were positive for yeasts. High identification accuracy was achieved in both the Raman (92.2%, 106 of 115) and IR (98.3%, 119 of 121) studies. Vibrational spectroscopic techniques enable simple, rapid, and accurate microbial identification. These advantages can be easily transferred to other applications in diagnostic microbiology, e.g., to accelerate identification of fastidious microorganisms.
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Bacterias/aislamiento & purificación , Sangre/microbiología , Hongos/aislamiento & purificación , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Espectrometría Raman/métodos , Bases de Datos Factuales , Humanos , Estudios ProspectivosRESUMEN
In the recent years, vibrational spectroscopies (infrared and Raman spectroscopy) have been developed for all sorts of analyses in microbiology. Important features of these methods are the relative ease with which measurements can be performed. Furthermore, in order to obtain infrared or Raman spectra, there is only a limited amount of sample handling involved without the need for expensive chemicals, labels or dyes. Here, we review the potential application of vibrational spectroscopies for the use in medical microbiology. After describing some of the basics of the techniques, considerations on reproducibility and standardisation are presented. Finally, the use of infrared and Raman spectroscopy for the (rapid) identification of medically relevant microorganisms is discussed. It can be concluded that vibrational spectroscopies show high potential as novel methods in medical microbiology.
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Técnicas de Tipificación Bacteriana , Candida/clasificación , Bacterias Gramnegativas/clasificación , Bacterias Grampositivas/clasificación , Técnicas de Tipificación Micológica , Infecciones Bacterianas/microbiología , Candidiasis/microbiología , Humanos , Espectrofotometría Infrarroja/métodos , Espectrometría Raman/métodosRESUMEN
Raman spectroscopy has recently been applied ex vivo and in vivo to address various biomedical issues such as the early detection of cancers, monitoring of the effect of various agents on the skin, determination of atherosclerotic plaque composition, and rapid identification of pathogenic microorganisms. This leap in the number of applications and the number of groups active in this field has been facilitated by several technological advancements in lasers, CCD detectors, and fiber-optic probes. However, most of the studies are still at the proof of concept stage. We present a discussion on the status of the field today, as well as the problems and issues that still need to be resolved to bring this technology to hospital settings (i.e., the medical laboratory, surgical suites, or clinics). Taken from the viewpoint of clinicians and medical analysts, the potential of Raman spectroscopic techniques as new tools for biomedical applications is discussed and a path is proposed for the clinical implementation of these techniques.
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Espectrometría Raman/métodos , Arteriosclerosis/diagnóstico , Bacteriemia/diagnóstico , Ensayos Clínicos como Asunto , Humanos , Lesiones Precancerosas/diagnóstico , Piel/química , Enfermedades Cutáneas Bacterianas/diagnóstico , Neoplasias Cutáneas/diagnósticoRESUMEN
Candida species are important nosocomial pathogens associated with high mortality rates. Rapid detection and identification of Candida species can guide a clinician at an early stage to prescribe antifungal drugs or to adjust empirical therapy when resistant species are isolated. Confocal Raman microspectroscopy is highly suitable for the rapid identification of Candida species, since Raman spectra can be directly obtained from microcolonies on a solid culture medium after only 6 h of culturing. In this study, we have used a set of 42 Candida strains comprising five species that are frequently encountered in clinical microbiology to test the feasibility of the technique for the rapid identification of Candida species. The procedure was started either from a culture on Sabouraud medium or from a positive vial of an automated blood culture system. Prior to Raman measurements, strains were subcultured on Sabouraud medium for 6 h to form microcolonies. Using multivariate statistical analyses, a high prediction accuracy (97 to 100%) was obtained with the Raman method. Identification with Raman microspectroscopy may therefore be significantly faster than identification with commercial identification systems that allow various species to be identified and that often require 24 to 48 h before a reliable identification is obtained. We conclude that confocal Raman microspectroscopy offers a rapid, accurate, and easy-to-use alternative for the identification of clinically relevant Candida species.
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Técnicas de Tipificación Bacteriana , Candida/clasificación , Candida/crecimiento & desarrollo , Algoritmos , Candidiasis/microbiología , Medios de Cultivo , Humanos , Microscopía Confocal , Espectrometría RamanRESUMEN
BACKGROUND: Current literature suggests that blunt carotid injuries (BCIs) and vertebral artery injuries (BVIs) are more common than once appreciated. Screening criteria have been suggested, but only one previous study has attempted to identify factors that predict the presence of BCI/BVI. This current study was conducted for two reasons. First, we wanted to determine the incidence of BCI/BVI in our institution. Second, we wanted to determine the incidence of abnormal four-vessel cerebral angiograms ordered for injuries and signs believed to be associated with BCI/BVI and thus to determine whether the screening protocol developed was appropriate. METHODS: From August 1998, we used liberalized screening criteria for patients who were prospectively identified and suspected to be at high risk for BCI/BVI if any of the following were present: anisocoria, unexplained mono-/hemiparesis, unexplained neurologic exam, basilar skull fracture through or near the carotid canal, fracture through the foramen transversarium, cerebrovascular accident or transient ischemic attack, massive epistaxis, severe flexion or extension cervical spine fracture, massive facial fractures, or neck hematoma. Four-vessel cerebral angiograms were used for screening for BCI/BVI. RESULTS: Over the 18-month study period, 48 patients were angiographically screened, with 21 patients (44%) being identified as having a total of 19 BCIs and 10 BVIs. Nine patients had unilateral carotid artery injuries and three patients had bilateral carotid artery injuries. Vertebral artery injuries were unilateral in six patients. One patient had bilateral carotid artery injuries and a unilateral vertebral artery injury. One patient had a unilateral carotid artery injury and a unilateral vertebral artery injury, and one patient had a unilateral carotid artery injury and bilateral vertebral artery injuries. During the same study period, 2,331 trauma patients were admitted, with 1,941 (83%) secondary to blunt trauma. The overall incidence of BCI/BVI was 1.1%. The frequency of abnormal angiograms ordered for cerebrovascular accident or transient ischemic attack, massive epistaxis, or severe cervical spine fractures was 100%. The frequency of abnormal angiograms ordered for the other indications was as follows: fracture through foramen transversarium, 60%; unexplained mono- or hemiparesis, 44%; basilar skull fracture, 42%; unexplained neurologic examination, 38%; anisocoria, 33%; and severe facial fractures, 0%. CONCLUSION: The liberalized screening criteria used in this study were appropriate to identify patients with BCI/BVI. This study suggests BCI/BVI to be more common than previously believed and justifies that screening should be liberalized.
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Traumatismos de las Arterias Carótidas/epidemiología , Tamizaje Masivo , Arteria Vertebral/lesiones , Heridas no Penetrantes/epidemiología , Adolescente , Adulto , Traumatismos de las Arterias Carótidas/diagnóstico , Angiografía Cerebral , Estudios Transversales , Femenino , Heparina/administración & dosificación , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Pronóstico , Factores de Riesgo , Resultado del Tratamiento , Heridas no Penetrantes/diagnósticoRESUMEN
Fourier transform infrared and Raman microspectroscopy are currently being developed as new methods for the rapid identification of clinically relevant microorganisms. These methods involve measuring spectra from microcolonies which have been cultured for as little as 6 h, followed by the nonsubjective identification of microorganisms through the use of multivariate statistical analyses. To examine the biological heterogeneity of microorganism growth which is reflected in the spectra, measurements were acquired from various positions within (micro)colonies cultured for 6, 12, and 24 h. The studies reveal that there is little spectral variance in 6-h microcolonies. In contrast, the 12- and 24-h cultures exhibited a significant amount of heterogeneity. Hierarchical cluster analysis of the spectra from the various positions and depths reveals the presence of different layers in the colonies. Further analysis indicates that spectra acquired from the surface of the colonies exhibit higher levels of glycogen than do the deeper layers of the colony. Additionally, the spectra from the deeper layers present with higher RNA levels than the surface layers. Therefore, the 6-h colonies with their limited heterogeneity are more suitable for inclusion in a spectral database to be used for classification purposes. These results also demonstrate that vibrational spectroscopic techniques can be useful tools for studying the nature of colony development and biofilm formation.
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Candida albicans/crecimiento & desarrollo , Escherichia coli/crecimiento & desarrollo , Staphylococcus aureus/crecimiento & desarrollo , Candida albicans/clasificación , Medios de Cultivo , Escherichia coli/clasificación , Humanos , Técnicas Microbiológicas , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Espectrometría Raman/métodos , Staphylococcus aureus/clasificaciónRESUMEN
Rapid and accurate identification of enterococci at the species level is an essential task in clinical microbiology since these organisms have emerged as one of the leading causes of nosocomial infections worldwide. Vibrational spectroscopic techniques (infrared [IR] and Raman) could provide potential alternatives to conventional typing methods, because they are fast, easy to perform, and economical. We present a comparative study using phenotypic, genotypic, and vibrational spectroscopic techniques for typing a collection of 18 Enterococcus strains comprising six different species. Classification of the bacteria by Fourier transform (FT)-IR spectroscopy in combination with hierarchical cluster analysis revealed discrepancies for certain strains when compared with results obtained from automated phenotypic systems, such as API and MicroScan. Further diagnostic evaluation using genotypic methods-i.e., PCR of the species-specific ligase and glycopeptide resistance genes, which is limited to the identification of only four Enterococcus species and 16S RNA sequencing, the "gold standard" for identification of enterococci-confirmed the results obtained by the FT-IR classification. These results were later reproduced by three different laboratories, using confocal Raman microspectroscopy, FT-IR attenuated total reflectance spectroscopy, and FT-IR microspectroscopy, demonstrating the discriminative capacity and the reproducibility of the technique. It is concluded that vibrational spectroscopic techniques have great potential as routine methods in clinical microbiology.
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Técnicas de Tipificación Bacteriana , Enterococcus/clasificación , ADN Bacteriano/análisis , ADN Bacteriano/genética , Enterococcus/genética , Genotipo , Humanos , Fenotipo , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Espectrometría RamanRESUMEN
For the reconstructive plastic surgeon, knowledge of the molecular biology underlying membranous fracture healing is becoming increasingly vital. Understanding the complex patterns of gene expression manifested during the course of membranous fracture repair will be crucial to designing therapies that augment poor fracture healing or that expedite normal osseous repair by strategic manipulation of the normal course of gene expression. In the current study, we present a rat model of membranous bone repair. This model has great utility because of its technical simplicity, reproducibility, and relatively low cost. Furthermore, it is a powerful tool for analysis of the molecular regulation of membranous bone repair by immunolocalization and/or in situ hybridization techniques. In this study, an osteotomy was made within the caudal half of the hemimandible, thus producing a stable bone defect without the need for external or internal fixation. The healing process was then catalogued histologically in 28 Sprague-Dawley rats that were serially killed at 1, 2, 3, 4, 5, 6, and 8 weeks after operation. Furthermore, using this novel model, we analyzed, within the context of membranous bone healing, the temporal and spatial expression patterns of several members of the bone morphogenetic protein (BMP) family, known to be critical regulators of cells of osteoblast lineage. Our data suggest that BMP-2/-4 and BMP-7, also known as osteogenic protein-1 (OP-1), are expressed by osteoblasts, osteoclasts, and other more primitive mesenchymal cells within the fracture callus during the early stages of membranous fracture healing. These proteins continue to be expressed during the process of bone remodeling, albeit less prominently. The return of BMP-2/-4 and OP-1 immunostaining to baseline intensity coincides with the histological appearance of mature lamellar bone. Taken together, these data underscore the potentially important regulatory role played by the bone morphogenetic proteins in the process of membranous bone repair.
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Proteínas Morfogenéticas Óseas/metabolismo , Modelos Animales de Enfermedad , Curación de Fractura , Fracturas Craneales/metabolismo , Factor de Crecimiento Transformador beta , Animales , Proteína Morfogenética Ósea 2 , Proteína Morfogenética Ósea 4 , Proteína Morfogenética Ósea 7 , Proteínas Morfogenéticas Óseas/análisis , Curación de Fractura/fisiología , Inmunohistoquímica , Masculino , Mandíbula/química , Mandíbula/patología , Mandíbula/cirugía , Osteotomía , Ratas , Ratas Sprague-Dawley , Fracturas Craneales/patologíaRESUMEN
Angiogenesis, the formation of new blood vessels, is crucial to the process of fracture healing. Vascular disruption after osseous injury results in an acidic, hypoxic wound environment. We have previously shown that osteoblasts can produce vascular endothelial growth factor (VEGF) in response to a variety of stimuli. In this study we examined pH and lactate concentration, two components of the putative fracture extracellular microenvironment, and determined their relative contribution to regulation of rat calvarial osteoblast VEGF production under both normoxic and hypoxic conditions. Our results demonstrate that pH and lactate concentration do independently affect osteoblast VEGF mRNA and protein production. Acidic pH (7.0) significantly decreased VEGF production, under normoxic and hypoxic conditions (P < 0.05), compared with neutral pH (7.4). This decrease was primarily transcriptionally regulated, because the rate of VEGF mRNA degradation was unchanged at pH 7.0 vs. 7.4. Similarly, an elevated lactate concentration (22 mM) also depressed osteoblast elaboration of VEGF at both neutral and acidic pH (P < 0.001). Furthermore, the effects of increasing acidity and elevated lactate appeared to be additive.