Nanowire sensors monitor bacterial growth kinetics and response to antibiotics.

Miniaturized and cost-efficient methods aiming at high throughput analysis of microbes are of great importance for the surveillance and control of infectious diseases and the related issue of antimicrobial resistance. Here we demonstrate a miniature nanosensor based on a honeycomb-patterned silicon nanowire field effect transistor (FET) capable of detection of bacterial growth and antibiotic response in microbiologically relevant nutrient media. We determine the growth kinetics and metabolic state of Escherichia coli cells in undiluted media via the quantification of changes in the source-drain current caused by varying pH values. Furthermore, by measuring the time dependent profile of pH change for bacterial cultures treated with antibiotics, we demonstrate for the first time the possibility of electrically distinguishing between bacteriostatic and bactericidal drug effects. We believe that the use of such nanoscopic FET devices enables addressing parameters that are not easily accessible by conventional optical methods in a label-free format, i.e. monitoring of microbial metabolic activity or stress response.

Retinal vessel structure measurement using spectral-domain optical coherence tomography.

PURPOSE: To assess the reliability and validity of spectral-domain optical coherence tomography (SD-OCT) measurements of retinal vessel lumen diameters and wall thicknesses. METHODS: SD-OCT was used to characterize the circular region around the optic disc of 40 eyes (20 subjects). The inner and outer sides (vitreal and choroidal sides) of the vessel wall and the luminal diameter were measured using intensity graphs. RESULTS: Mean arterial and venous luminal diameters were 95.1±16.1 and 132.6±17.8 µm, respectively. The wall thicknesses of inner and outer sides of the artery were 23.9±4.9 and 21.2±3.5 µm, respectively. The wall thicknesses of the inner and outer sides of the vein were 20.7±4.2 and 16.3±4.3 µm, respectively. There were significant differences between the inner and outer wall thicknesses in both the artery and vein (P<0.01). Intra- and interobserver intraclass correlation coefficients (ICCs) for lumen measurements were >0.95, and for wall thicknesses were >0.85, except for the outer wall thickness measurements. The mean value of outer and inner wall thicknesses showed good reproducibility, with ICCs of >0.85. CONCLUSION: Intensity graph-assisted measurements using SD-OCT provided more objective information in finding boundaries of vessels. Luminal diameters and wall thicknesses obtained with OCT showed good overall reproducibility, with inner wall thicknesses being thicker, and with better reproducibility compared with outer wall thicknesses, where ICC values were the lowest among the inner wall thicknesses, mean thicknesses of inner and outer walls, and luminal diameters. When using SD-OCT measurements, caution is therefore advised when using only the outer wall as representative of the wall thicknesses.

The Added Prognostic Value of Preoperative Dynamic Contrast-Enhanced MRI Histogram Analysis in Patients with Glioblastoma: Analysis of Overall and Progression-Free Survival.

BACKGROUND AND PURPOSE: The prognostic value of dynamic contrast-enhanced MR imaging in patients with glioblastoma is controversial. We investigated the added prognostic value of dynamic contrast-enhanced MR imaging to clinical parameters and molecular biomarkers in patients with glioblastoma by using histogram analysis. MATERIALS AND METHODS: This retrospective study consisted of 61 patients who underwent preoperative dynamic contrast-enhanced MR imaging for glioblastoma. The histogram parameters of dynamic contrast-enhanced MR imaging, including volume transfer constant, extravascular extracellular volume fraction, and plasma volume fraction, were calculated from entire enhancing tumors. Univariate analyses for overall survival and progression-free survival were performed with preoperative clinical and dynamic contrast-enhanced MR imaging parameters and postoperative molecular biomarkers. Multivariate Cox regression was performed to build pre- and postoperative models for overall survival and progression-free survival. The performance of models was assessed by calculating the Harrell concordance index. RESULTS: In univariate analysis, patients with higher volume transfer constant and extravascular extracellular volume fraction values showed worse overall survival and progression-free survival, whereas plasma volume fraction showed no significant correlation. In multivariate analyses for overall survival, the fifth percentile value of volume transfer constant and kurtosis of extravascular extracellular volume fraction were independently prognostic in the preoperative model, and kurtosis of volume transfer constant and extravascular extracellular volume fraction were independently prognostic in the postoperative model. For progression-free survival, independent prognostic factors were minimum and fifth percentile values of volume transfer constant and kurtosis of extravascular extracellular volume fraction in the preoperative model and kurtosis of extravascular extracellular volume fraction in the postoperative model. The performance of preoperative models for progression-free survival was significantly improved when minimum or fifth percentile values of volume transfer constant and kurtosis of extravascular extracellular volume fraction were added. CONCLUSIONS: Higher volume transfer constant and extravascular extracellular volume fraction values are associated with worse prognosis, and dynamic contrast-enhanced MR imaging may have added prognostic value in combination with preoperative clinical parameters, especially in predicting progression-free survival.

Clinical characteristics of responders to intravitreal bevacizumab in central serous chorioretinopathy patients.

PURPOSE: To investigate factors associated with good response to intravitreal bevacizumab (IVB) in central serous chorioretinopathy (CSC) patients. METHODS: We retrospectively reviewed 42 eyes of CSC patients of symptom duration more than 3 months who received a single or multiple successive IVBs on an as-needed basis (0.05 ml, 1.25 mg). High responders (HRs) were defined as complete resolution of subretinal fluid (SRF) on spectral domain optical coherence tomography (SD-OCT). Moderate responders (MRs) were defined as SRF resolution of 50-99% of pretreatment volume and poor responders (PRs) as SRF resolution <50%. Clinical, SD-OCT, fluorescein, and indocyanine green angiography findings were analyzed to find factors associated with HR. Descriptive statistics for all demographic and clinical variables were calculated, and comparisons were made using Wilcoxon's matched-pairs signed-rank test, the Mann-Whitney U-test for means with continuous data, Pearson's χ(2) test, and Fisher's exact test for categorical data. RESULTS: The mean number of IVB was 1.9. At postoperative 1 month, there were 10 (24%) HRs, 18 (43%) MRs, and 14 (33%) PRs. At the last follow-up (the mean 8.6 months), there were 25 HRs (60%), 9 MRs (21%), and 8 PRs (19%). Thicker subfoveal choroid (P=0.036), smaller lesion diameter (P=0.019), and better baseline best-corrected visual acuity (P=0.002) predicted HRs at postoperative 1 month. HR at the last follow-up was associated with classic pattern fluorescein angiography finding. CONCLUSIONS: Suboptimal effects of IVB on persistent CSC suggest primary IVB on selective cases with better vision, smaller lesion, and thicker choroid at baseline.

Discrimination of Tumorous Intracerebral Hemorrhage from Benign Causes Using CT Densitometry.

BACKGROUND AND PURPOSE: Differentiation of tumorous intracerebral hemorrhage from benign etiology is critical in initial treatment plan and prognosis. Our aim was to investigate the diagnostic value of CT densitometry to discriminate tumorous and nontumorous causes of acute intracerebral hemorrhage. MATERIALS AND METHODS: This retrospective study included 110 patients with acute intracerebral hemorrhage classified into 5 groups: primary intracerebral hemorrhage without (group 1) or with antithrombotics (group 2) and secondary intracerebral hemorrhage with vascular malformation (group 3), brain metastases (group 4), or primary brain tumors (group 5). The 5 groups were dichotomized into tumorous (groups 4 and 5) and nontumorous intracerebral hemorrhage (groups 1-3). Histogram parameters of hematoma attenuation on nonenhanced CT were compared among the groups and between tumorous and nontumorous intracerebral hemorrhages. With receiver operating characteristic analysis, optimal cutoffs and area under the curve were calculated for discriminating tumorous and nontumorous intracerebral hemorrhages. RESULTS: Histogram analysis of acute intracerebral hemorrhage attenuation showed that group 1 had higher mean, 5th, 25th, 50th, and 75th percentile values than groups 4 and 5 and higher minimum and 5th percentile values than group 2. Group 3 had higher 5th percentile values than groups 4 and 5. After dichotomization, all histogram parameters except maximum and kurtosis were different between tumorous and nontumorous intracerebral hemorrhages, with tumors having lower cumulative histogram parameters and positive skewness. In receiver operating characteristic analysis, 5th and 25th percentile values showed the highest diagnostic performance for discriminating tumorous and nontumorous intracerebral hemorrhages, with 0.81 area under the curve, cutoffs of 34 HU and 44 HU, sensitivities of 65.6% and 70.0%, and specificities of 85.0% and 80.0%, respectively. CONCLUSIONS: CT densitometry of intracerebral hemorrhage on nonenhanced CT might be useful for discriminating tumorous and nontumorous causes of acute intracerebral hemorrhage.

Oblique wedge osteotomy for correction of asymmetric pectus excavatum in young children.

The procedure modified by Ravitch is usually used to correct pectus excavatum. Young children with asymmetric sternal depression need more modification of the procedure to maintain the sternum in the elevated flat position. In this report we describe a modification of the sternal elevation procedure, including an oblique wedge osteotomy through the anterior table, to correct the asymmetric sternal depression in young children.