Development of Conductive Boron-Doped Diamond Electrode: A microscopic,Spectroscopic, and Voltammetric Study

Building on diamond characteristics such as hardness, chemical inertness and low electron emission threshold voltage, the current microscopic, spectroscopic and voltammetric investigations are directed towards improving the properties of electrode coating materials for their future use in clinical studies of deep brain stimulation via fast-scan cyclic voltammetry (FSCV). In this study we combine the capabilities of confocal Raman mapping in providing detailed and accurate analysis of local distributions of material constituents in a series of boron-doped polycrystalline diamond films grown by chemical vapor deposition, with information from the more conventional techniques of scanning electron microscopy (SEM) and infrared absorption spectroscopy. Although SEM images show a uniform distribution of film crystallites, they have the limitation of being unable to differentiate the distribution of boron in the diamond. Values of 10¹⁸–10²¹ atoms/cm³ of boron content have been estimated from the absorption coefficient of the 1290 cm⁻¹ infrared absorption band and from the 500 cm⁻¹ Raman vibration. The observed accumulation of boron atoms and carbon sp² impurities at the grain boundaries suggests that very high doping levels do not necessarily contribute to improvement of the material’s conductivity, corroborating with voltammetric data. FSCV results also indicate an enhanced stability of analyte detection.     

Response to pretransplant hypomethylating agents influences the outcome of allogeneic hematopoietic stem cell transplantation in adults with myelodysplastic syndromes

This study describes a retrospective analysis on the transplant outcome of 56 consecutive patients with myelodysplastic syndrome (MDS) according to their response to hypomethylating agents (HMA). While 2‐yr disease‐free survival (DFS) of patients who transformed to acute myeloid leukemia (n = 12) was 25%, that of the remaining patients with MDS according to response to HMA was 73.1%, 68.1%, 50.0%, and 20.8% in G‐COR (group of continuous response, n = 19), G‐NoC (group of no change, n = 15), G‐LOR (group of loss of response, n = 6), and G‐DP (group of disease progression, n = 4), respectively. When dichotomized as G‐COR/G‐NoC versus G‐LOR/G‐DP, significantly different 2‐yr DFS (71.0% vs. 33.3%; P = 0.004) and relapse (14.1% vs. 46.7%; P = 0.016) were demonstrated. On multivariate analysis, G‐LOR/G‐DP [hazard ratio (HR), 3.91; P = 0.008] and poor karyotype at transplantation (HR, 2.69; P = 0.017) were the significant predictors for poor DFS, as G‐LOR/G‐DP was for relapse (HR, 6.28; P = 0.011). DFS was significantly poor in patients with any of the two predictors in all MDS (81.5% vs. 34.9%; P = 0.001) or higher‐risk MDS (HrMDS) at the time of HMA (80.7% vs. 29.2%; P = 0.005). G‐COR showed a trend of better DFS compared with G‐NoC among HrMDS (74.6% vs. 36.5%; P = 0.090). These results implicate the significance of response to HMA on hematopoietic stem cell transplantation (HSCT) outcomes and support the need for future study to verify the suggested strategy of proceeding to transplantation before LOR or DP, especially for HrMDS.     

The safety of spinal pedicle screws in children ages 1 to 12

Background contextPedicle screws have shown to be a safe and effective method of spinal fixation, offering superior multiplanar correction compared with hooks or sublaminar wires in selected situations. Though only food and drug administration (FDA) approved in the adolescent population, they are commonly used in an off-label manner in the preadolescent population.PurposeTo determine if the complication rate of the off-label use of pedicle screws for spinal fixation in the preadolescent 0- to 12-year-old population is comparable with the complication rate in the FDA-approved 13- to 18-year-old population.Study design/settingRetrospective medical record and radiograph review.Patient sampleA total of 726 pediatric patients who underwent a spinal fusion procedure at a single tertiary institution between January 2003 and December 2008 were reviewed.Outcome measuresIncidence of instrumentation failure, infection, neurological complication, and total complications.MethodsThe study population was divided into two groups based on age: the younger group included 0- to 12-year olds and the older group included 13- to 18-year olds at the time of surgery. Groups were further subdivided based on diagnosis: “A,” neuromuscular scoliosis; “B,” idiopathic scoliosis, and “C,” other spinal deformities. Rates of neurovascular complications, infections, and instrumentation complications were compared statistically between the younger and the older groups. Only patients with greater than or equal to 1-year follow-up and greater than or equal to 2-year follow-up were included in the calculations for infection and instrumentation complication rates, respectively.ResultsThere were 206 patients (33% males, 67% females) in the younger group (0 to 12 years) and 520 (41% males, 59% females) in the older group (13 to 18 years). Overall, younger group had a 13.6% complication rate compared with 16.9% in the older group. Younger subjects showed a 13.4% complication rate because of instrumentation-related complications, 0.5% for neurovascular complications, and an infection rate of 9.2%. The older group showed a 15.4% complication rate because of instrumentation-related complications, 1.92% for neurovascular complications, and an infection rate of 11.0%. Complication rates were statistically insignificant between the two groups. Other complications in the younger group included one patient with aspiration pneumonia, two with ileus, and one with pulmonary and other complications in the older group included one patient with aspiration pneumonia, two with ileus, three with superior mesenteric artery syndrome, and three with wound dehiscence.ConclusionsThe complication rates in the young pediatric population associated with the off-label use of pedicle screws for spinal fusions are not statistically different from the complication rates associated with the FDA-approved adolescent population.