RESUMEN

OBJECTIVE The objective of this study was to compare postoperative sagittal alignment among 3 rod constructs with different rigidity profiles. METHODS This was a dual-center retrospective cohort study involving 2 consecutive cohorts in which patients were surgically treated for adolescent idiopathic scoliosis. Lenke Type 5 curves were excluded. Patients were operated on with all-pedicle screw instrumentation using 3 different rod constructs. The first group was operated on using a hybrid construct (HC) consisting of a normal circular rod on the convex side and a beam-like rod (BR) on the concave side. The second group was operated on with a standard construct (SC) using bilateral BRs in the full length of the fusion. The third group was operated on with a modified construct (MC). The modified rods have a beam-like shape in the caudal portion, but in the cranial 2 or 3 fusion levels the rod transitions to a circular shape with a smaller anteroposterior diameter. Radiographs were analyzed preoperatively and at the first postoperative follow-up (range 1-8 weeks). The primary outcome was pre- to postoperative change in thoracic kyphosis (TK), and the secondary outcome was the ability to achieve postoperative TK within the normal range. RESULTS The HC, SC, and MC groups included 23, 70, and 46 patients, respectively. The 3 groups did not differ significantly in preoperative demographic or radiographic parameters. The mean ± standard deviation of the preoperative main curve was 60.7° ± 12.6°, and the mean of curve correction was 62.9% ± 10.4% with no significant difference among groups (p ≥ 0.680). The groups did not differ significantly in coronal balance or proximal or thoracolumbar curve correction (p ≥ 0.189). Mean postoperative TK was 23.1° ± 6.3°, 19.6° ± 7.6°, and 23.4° ± 6.9° in the HC, SC and MC groups, respectively (p = 0.013), and the mean change in TK was -3.5° ± 11.3°, -7.1° ± 11.6°, and 0.1° ± 10.9°, respectively (p = 0.005). The MC group had significantly higher postoperative TK and less loss of TK compared with the SC group (p ≤ 0.018). Postoperative TK ≤ 10° was found in 12 patients (17%) in the SC group, 1 patient (5%) in the HC group, and 1 patient (2%) in the MC group (p = 0.021). There were no differences in proximal alignment, thoracolumbar alignment, or sagittal vertical axis (p ≥ 0.249). Lumbar lordosis was 58.9° ± 11.2° in the HC group versus 52.0° ± 1.3° and 55.0° ± 11.0° and the SC and MC groups, respectively (p = 0.040). CONCLUSIONS In the 3 rod constructs with different rigidity profiles, significantly better restoration of kyphosis was achieved with the use of bilateral modified rods compared with bilateral standard rods. In the MC and HC groups, the rate of severe postoperative hypokyphosis was significantly lower than in the SC group. This is the first study to describe the clinical use of a rod with a reduced proximal diameter and show marked radiographic improvement in sagittal alignment.

Asunto(s)

Cifosis/cirugía , Tornillos Pediculares , Escoliosis/cirugía , Fusión Vertebral/métodos , Vértebras Torácicas/cirugía , Adolescente , Estudios de Cohortes , Femenino , Humanos , Masculino , Radiografía , Recuperación de la Función/fisiología , Índice de Severidad de la Enfermedad , Resultado del Tratamiento

Asunto(s)

Tecnología Biomédica/estadística & datos numéricos , Comercio/organización & administración , Personal de Salud/estadística & datos numéricos , Tecnología Biomédica/tendencias , Comercio/tendencias , Seguridad Computacional/estadística & datos numéricos , Fraude , Sector de Atención de Salud/organización & administración , Empleos en Salud/estadística & datos numéricos , Humanos , Internet/estadística & datos numéricos , Medición de Riesgo , Integración de Sistemas , Estados Unidos/epidemiología

RESUMEN

Organic dry bean production systems have received increasing interest in many regions of the US, including Minnesota. Thus, improving biological N2 fixation would be highly beneficial for organic crop production. To date, only limited work has been done to select efficient N2-fixing rhizobia for organic dry bean production. In this study, soil samples from 25 organic fields in Minnesota, with a previous cropping history of dry beans, soybeans or both, were collected during May to July 2012. Genetic diversity of indigenous dry bean-rhizobia (511 isolates) was determined by using horizontal, fluorophore-enhanced, repetitive, extragenic, and palindromic-PCR (HFERP) DNA fingerprinting and isolates were classified as belonging to 58 different genotypes. The more abundant rhizobia isolated from bean nodules comprised 35.6% of the population. None of the isolates were identical to commonly-used commercial strains used in the U.S., including Rhizobium tropici CIAT899. Seventeen predominant genotypes were shown to represent two main species, Rhizobium leguminosarum bv. phaseoli (67.1%) and Rhizobium etli (30.2%). One of the indigenous strains, orgK9, displayed efficient N2-fixation and competitive ability relative to the commercial strains tested. The lack of large numbers of indigenous dry bean-rhizobia at most study sites will be useful to avoid competition problems between inoculant strains and indigenous rhizobia. This will allow inoculation with highly effective N2-fixing rhizobia, thus resulting in improved crop productivity. Our results highlight the existence of site-specific rhizobial genotypes in different organic fields and identify strains that may prove useful as novel inoculants for organic dry bean production systems.

Asunto(s)

ADN Bacteriano/genética , Agricultura Orgánica , Phaseolus/microbiología , Rhizobium/genética , Variación Genética/genética , Fijación del Nitrógeno , Microbiología del Suelo

RESUMEN

In this study we examined the influence of silver nanoparticles (SNP) on the bacterial community and microbial processes in two soils from Thailand, a Ayutthaya (Ay) and Kamphaengsaen soil series (Ks). Results of this analysis revealed that SNP did not affect to pH, electrical conductivity, cation exchange capacity, and organic matter in both the Ay and Ks series. Automated ribosomal intergenic spacer analysis (ARISA) analysis profiles showed that bacterial community decreased with increasing SNP concentration. Pearson's correlation coefficient and multidimensional scaling analyses indicated that the effects of SNP on the bacterial community structure depended more on soil types than SNP application rates and incubation periods. Additionally, the results showed that SNP application rates affected on amount of CO2 emissions, while SNP application rates had no effect on N mineralization in both soil types. This study is the first investigation of the effects of SNP on bacterial community using ARISA analysis. Our results might be useful to evaluate the risk associated with the applications of SNP for consumer products and agricultural practices.

Asunto(s)

Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Nanopartículas del Metal/química , Plata/química , Antibacterianos/química , Microbiología del Suelo

RESUMEN

The bacterial pathogens Shigella, Salmonella, Campylobacter, and shiga toxin-producing E. coli (STEC) were recently found to be associated with Cladophora growing in southern Lake Michigan. Preliminary results indicated that the Salmonella strains associated with Cladophora were genetically identical to each other. However, because of the small sample size (n=37 isolates) and a lack of information on spatial-temporal relationships, the nature of the association between Cladophora and Salmonella remained speculative. In this study, we investigated the population structure and genetic relatedness of a large number of Cladophora-borne Salmonella isolates from Lake Michigan (n=133), as well as those isolated from stream and lake water (n=31), aquatic plants (n=8), and beach sands and sediments (n=8) from adjacent watersheds. Salmonella isolates were collected during 2005-2007 between May and August from Lake Michigan beachsheds in Wisconsin, Illinois, and Indiana. The genetic relatedness of Salmonella isolates was examined by using the horizontal, fluorophore-enhanced rep-PCR (HFERP) DNA fingerprinting technique. While the Salmonella isolates associated with Cladophora exhibited a high degree of genetic relatedness (>or=92% similarity), the isolates were not all genetically identical. Spatial and temporal relationships were evident in the populations examined, with tight clustering of the isolates both by year and location. These findings suggest that the relationship between Salmonella and Cladophora is likely casual and is related to input sources (e.g. wastewater, runoff, birds) and the predominant Salmonella genotype surviving in the environment during a given season. Our studies indicate that Cladophora is likely an important reservoir for Salmonella and other enteric bacterial pathogens in Lake Michigan beachsheds, which in turn may influence nearshore water quality.

Asunto(s)

Chlorophyta/microbiología , Agua Dulce/microbiología , Salmonella/aislamiento & purificación , Estaciones del Año , Abastecimiento de Agua , Geografía , Michigan , Filogenia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Salmonella/genética , Factores de Tiempo

RESUMEN

Four hundred and thirteen oxytetracycline-resistant bacteria were recovered from six freshwater giant prawn farms with a history of oxytetracycline use. Most oxytetracyclineresistant isolates were Gram-negative bacteria. Six groups of oxytetracycline-resistant bacteria were classified using cluster analysis based on a comparison of levels of oxytetracycline resistance. Complex fingerprint patterns were obtained for 71 isolates studied. In general, the band patterns of isolates from different ponds were very similar, and the data indicated that the isolates were closely related. The exploration for crossresistance found that most of the 71 oxytetracycline-resistant isolates were also resistant to tetracycline and chlortetracycline, but had a relatively low resistance to doxycycline. Many isolates showed higher chlortetracycline resistance than oxytetracycline resistance. Additionally, the oxytetracyclineresistant isolates were examined for the presence of tetracycline resistance (tet) genes. Fifty percent of the isolates carried one of the 14 known tet genes examined. The most common determinants were TetA and TetD. However, TetB, TetC, TetE, TetK, TetL, and TetM were also found with various frequencies.

Asunto(s)

Bacterias/clasificación , Bacterias/genética , Oxitetraciclina/farmacología , Palaemonidae/microbiología , Resistencia a la Tetraciclina , Animales , Acuicultura , Bacterias/efectos de los fármacos , Bacterias/aislamiento & purificación , Proteínas Bacterianas/genética , Dermatoglifia del ADN , Farmacorresistencia Bacteriana Múltiple , Sedimentos Geológicos/microbiología , Pruebas de Sensibilidad Microbiana , Oxitetraciclina/análogos & derivados , Microbiología del Suelo , Microbiología del Agua

RESUMEN

A single nucleotide polymorphism between Escherichia coli strains K12 and B is known to alter the mechanism by which the arginine repressor regulates arginine biosynthesis, from a regulated system in E. coli K12 to a deregulated system in E. coli B. Laboratory experiments have demonstrated that the different regulatory strategies are selectively favored under different environmental conditions. In this study we analyzed 537 E. coli strains and show that the argR allele in E. coli B, which causes deregulation, is rare in isolates obtained from natural sources. Moreover, sequence analysis of 85 strains shows no evidence of selection at the arginine repressor locus. This illustrates that analysis of sequence data is insufficient to detect selection of uncommon alleles in rare environments.

Asunto(s)

Arginina/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Heces/microbiología , Genes Bacterianos , Proteínas Represoras/genética , Alelos , Animales , Animales Domésticos/microbiología , Animales Salvajes/microbiología , Arginina/biosíntesis , Secuencia de Bases , Codón de Terminación , Escherichia coli/aislamiento & purificación , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/aislamiento & purificación , Frecuencia de los Genes , Variación Genética , Haplotipos , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Polimorfismo Genético , Conformación Proteica , Estructura Terciaria de Proteína , Proteínas Represoras/química , Proteínas Represoras/aislamiento & purificación , Análisis de Secuencia de Proteína

RESUMEN

STUDY DESIGN: A retrospective consecutive case series, radiographic analysis, outcomes analysis, and report on complications. OBJECTIVES: To evaluate the radiographic and functional outcomes of a reconstructive realignment procedure for fixed sagittal imbalance and discuss the complications. SUMMARY OF BACKGROUND DATA: We describe a modification of an existing technique permitting greater single-level correction for which no reports exist in the peer-reviewed literature. METHODS: Twenty-four patients were eligible for 2-year minimum follow-up (average, 4.0 years). Etiologies included iatrogenic (n = 17), post-traumatic (n = 3), ankylosing spondylitis (n = 2), degenerative (n = 1), and congenital (n = 1). Patients were evaluated by standardized upright radiographs, chart review, and National Spine Network questionnaire. RESULTS: Seventeen patients had undergone 17 previous procedures. Seven of 24 patients required augmentation with anterior structural grafting. The majority of osteotomies were performed at L3 (15); others included L2 (6), L4 (2), and L5 (1). Lumbar lordosis before surgery averaged 13 degrees (range, 55 degrees to -65 degrees) and improved to 53 degrees (range, 20 degrees to 99 degrees), an average correction of 40%. The sagittal vertical axis measured from C7-S1 demonstrated a preoperative sagittal decompensation averaging 11.4 cm (range, 5.5-23 cm) with correction to 2.4 cm (-9.0 cm or 79% average correction). Coronal balance did not change significantly. There were 17 complications in 14 patients. Nine patients required additional surgery at latest follow-up. CONCLUSIONS: Transpedicular wedge resection osteotomy procedure is a very effective technique to correct fixed sagittal imbalance and provide biomechanical stability. The high complication rate mandates a careful assessment of the risk/benefit ratio before undertaking what is a major reconstructive procedure. Most patients are satisfied, particularly when sagittal balance is achieved.

Asunto(s)

Lordosis/cirugía , Vértebras Lumbares/cirugía , Osteotomía/métodos , Adulto , Anciano , Femenino , Humanos , Complicaciones Intraoperatorias , Lordosis/diagnóstico por imagen , Lordosis/patología , Masculino , Persona de Mediana Edad , Osteotomía/efectos adversos , Satisfacción del Paciente , Complicaciones Posoperatorias , Calidad de Vida , Radiografía , Estudios Retrospectivos , Encuestas y Cuestionarios , Resultado del Tratamiento

RESUMEN

A horizontal, fluorophore-enhanced, repetitive extragenic palindromic-PCR (rep-PCR) DNA fingerprinting technique (HFERP) was developed and evaluated as a means to differentiate human from animal sources of Escherichia coli. Box A1R primers and PCR were used to generate 2,466 rep-PCR and 1,531 HFERP DNA fingerprints from E. coli strains isolated from fecal material from known human and 12 animal sources: dogs, cats, horses, deer, geese, ducks, chickens, turkeys, cows, pigs, goats, and sheep. HFERP DNA fingerprinting reduced within-gel grouping of DNA fingerprints and improved alignment of DNA fingerprints between gels, relative to that achieved using rep-PCR DNA fingerprinting. Jackknife analysis of the complete rep-PCR DNA fingerprint library, done using Pearson's product-moment correlation coefficient, indicated that animal and human isolates were assigned to the correct source groups with an 82.2% average rate of correct classification. However, when only unique isolates were examined, isolates from a single animal having a unique DNA fingerprint, Jackknife analysis showed that isolates were assigned to the correct source groups with a 60.5% average rate of correct classification. The percentages of correctly classified isolates were about 15 and 17% greater for rep-PCR and HFERP, respectively, when analyses were done using the curve-based Pearson's product-moment correlation coefficient, rather than the band-based Jaccard algorithm. Rarefaction analysis indicated that, despite the relatively large size of the known-source database, genetic diversity in E. coli was very great and is most likely accounting for our inability to correctly classify many environmental E. coli isolates. Our data indicate that removal of duplicate genotypes within DNA fingerprint libraries, increased database size, proper methods of statistical analysis, and correct alignment of band data within and between gels improve the accuracy of microbial source tracking methods.

Asunto(s)

Escherichia coli/clasificación , Escherichia coli/aislamiento & purificación , Heces/microbiología , Variación Genética , Reacción en Cadena de la Polimerasa/métodos , Contaminación del Agua , Animales , Gatos , Bovinos , Dermatoglifia del ADN/métodos , Perros , Escherichia coli/genética , Infecciones por Escherichia coli/microbiología , Biblioteca de Genes , Genotipo , Humanos , Procesamiento de Imagen Asistido por Computador , Secuencias Repetitivas de Ácidos Nucleicos/genética , Tamaño de la Muestra