Development of new reference materials for the determination of cadmium, chromium, mercury and lead in polycarbonate.

Reference materials for quantitative determination of Cd, Cr, Hg and Pb in polycarbonate were developed. Reference materials with two concentration level of elements were prepared by adding appropriate amounts of chemicals to a blank polycarbonate base material. It was shown that ten bottles with triplicate analysis are enough to demonstrate the homogeneity of these candidate reference materials. The statistical results also showed no significant trends in both short-term stability test for four weeks and long-term stability test for twelve months. The certification of the four elements was carried out by isotope-dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) with microwave-assisted digestion. Certification of candidate reference materials in a single laboratory was confirmed with interlaboratory comparison participated by a certain number of well-recognized testing laboratories in Korea. The certified values and expanded uncertainties (k=2) for the candidate reference material with low level and the one with high level were (51.7±2.1)mgkg(-1) Cd, (103.8±2.9)mgkg(-1) Cd, (98.8±4.5)mgkg(-1) Cr, (1004±49.8)mgkg(-1) Cr, (107.4±4.6)mgkg(-1) Hg, (1133±50.7)mgkg(-1) Hg, (94.8±3.7)mgkg(-1) Pb and (988.4±53.6)mgkg(-1) Pb, respectively. The reference materials developed in this study demonstrated their suitability for the quality assurance in Cd, Cr, Hg and Pb analysis for the implementation of RoHS Directive.

Femoral lateral bowing and varus condylar orientation are prevalent and affect axial alignment of TKA in Koreans.

BACKGROUND: Coronal alignment is considered key to the function and longevity of a TKA. However, most studies do not consider femoral and tibial anatomical features such as lateral femoral bowing and the effects of these features and subsequent alignment on function after TKA are unclear. QUESTIONS/PURPOSES: We therefore determined (1) the prevalence of lateral femoral bowing, varus femoral condylar orientation, and severe tibia plateau inclination in female Koreans undergoing TKA; (2) whether postoperative alignments are affected by these anatomical features and improved by the use of navigation; and (3) whether postoperative coronal alignments are associated with function. METHODS: We measured alignment in 367 knees that underwent TKA and 60 sex- and age-matched normal knees (control group). We determined patterns and degrees of femoral bowing angle, femoral condylar orientation, and tibial plateau inclination on preoperative full-limb radiographs. Postoperatively, coronal alignment of limbs and of femoral and tibial components was measured. We compared American Knee Society scores, WOMAC scores, and SF-36 scores in aligned knees and outliers (beyond ± 3° or ± 2°) at 1 year. RESULTS: The prevalence of lateral femoral bowing was 88% in the TKA group and 77% in the control group. Mean femoral condylar orientation angle was varus 2.6° in the TKA group and valgus 1.1° in the control group, and mean tibial plateau inclination was varus 8.3° in the TKA group and varus 5.4° in the control group. Femoral lateral bowing and varus femoral condylar orientation were associated with postoperative alignments. Several clinical outcome scales were inferior in the outliers in mechanical tibiofemoral angle, anatomical tibiofemoral angle, and tibial coronal alignment but not in femoral coronal alignment outliers. CONCLUSIONS: Lateral femoral bowing, varus condylar orientation, and severe varus inclination of the tibia plateau should be considered when performing TKA in Korean patients or patients with otherwise similar anatomical features.

Comparisons of femoral tunnel position and length in anterior cruciate ligament reconstruction: modified transtibial versus anteromedial portal techniques.

PURPOSE: We aimed to compare the modified transtibial and anteromedial (AM) portal techniques of anterior cruciate ligament reconstruction with respect to femoral tunnel position and length, as well as to identify factors associated with tunnel length. METHODS: After exclusions, 105 primary anterior cruciate ligament reconstructions (55 in transtibial group and 50 in AM portal group) were studied. Femoral tunnel positions were assessed on postoperative tunnel-view radiographs, and tunnel lengths were measured during surgery. Differences between femoral tunnel positions in the coronal plane and lengths in these 2 groups were examined, and factors associated with tunnel lengths were investigated. RESULTS: The AM portal group had a significantly more oblique femoral tunnel position than the transtibial group. However, femoral tunnels in the AM portal group were substantially shorter than tunnels in the transtibial group (34.2 v 43.3 mm, P < .001); the proportions of knees with femoral tunnels measuring less than 30 mm in the AM portal and transtibial groups were 26% and only 2%, respectively. In addition, a more oblique femoral tunnel position and a shorter distal femur mediolateral width were found to be significantly associated with a shorter femoral tunnel. CONCLUSIONS: This study shows that the AM portal technique can achieve a more oblique femoral tunnel position but that resultant tunnels are substantially shorter than tunnels produced by the modified transtibial technique.

Life expectancy after lumbar spine surgery: one- to eleven-year follow-up of 1015 patients.

STUDY DESIGN: Retrospective study. OBJECTIVES: To investigate the 10-year survival of a large number of elderly patients who underwent spine surgery for lumbar spinal stenosis, and to identify significant risk factors and compare them with age- and gender-matched controls from the general population. SUMMARY OF BACKGROUND DATA: There have been many studies on treatment options and surgical outcomes for lumbar spinal stenosis. However, survival outcomes after lumbar spinal stenosis surgery have not previously been studied. Because these operations are usually performed for elderly patients, we consider patient survival or life expectancy to be a significant outcome measure. METHODS: Between January 1997 and June 2006, patients underwent spine surgery for lumbar spinal stenosis. The date of death was verified using records from the National Health Insurance Corporation. Cumulative 10-year survival was calculated using the Kaplan-Meier method, and the survival of patients who had undergone spine surgery was compared to that of age- and sex-matched members of the general population. A Cox multivariate regression analysis was used in order to compare the survival rates for different covariates. RESULTS: Using Kaplan-Meier curves, the overall 10-year survival was 87.8% in patients 60 to 70 years old at surgery, and 83.8% in patients 70 to 85 years old at surgery. The 10-year survival rate of female patients and patients who underwent fusion surgery were higher than those of male patients and patients with nonfusion surgery. Compared to the adjusted corresponding portion in general population, the standardized mortality ratios were 0.21, 0.53, and 0.45 in patients aged 50 to 59, 60 to 69, and 70 to 85, respectively. CONCLUSION: Elderly patients who underwent spine surgery for spinal stenosis had reduced mortality compared to the corresponding portion of the general population. Therefore, surgery for spinal stenosis is a justifiable procedure even in elderly patients.

Differences in EEG between gifted and average students: neural complexity and functional cluster analysis.

The main aim of the present study was to assess the differences in EEG between gifted and average students. Another aim of the present study was to investigate which brain areas are related to a Rey-Osterrieth complex figure (ROCF) memorizing using a functional cluster (FC) analysis and how the complexity of cortical activities changes in both gifted and average students. The EEG was recorded from 16 electrodes in both 18 right-handed healthy gifted and age-matched average students before and during ROCF memorizing. FC was estimated to characterize the joint interactions among many brain regions and neural complexity. The study assessed the visuo-spatial memory abilities through examining EEG profiles using the measure of FC, and planning and executive function using recall score. The gifted students made a significantly high score compared to the average students during ROCF memorizing. Both groups showed very different FC patterns. ROCF memorizing is related to the visual mental process, thus simultaneous neuronal activities appears on the right central, temporal, occipital, and bilateral prefrontal regions. One of the notable characteristics of gifted students' FC map is the dominance of the right hemisphere compared with that of average students, and it is accordance with the characteristics of gifted brain.

Acquired tolerance to temperature extremes.

Acquired tolerance to temperature stresses is a major protective mechanism. Recent advances have revealed key components of stress signal transduction pathways that trigger enhanced tolerance, and several determinants of acquired tolerance have been identified. Although high and low temperature stresses impose different metabolic and physical challenges, acquired tolerance appears to involve general as well as stress-specific components. Transcriptome studies and other genomic-scale approaches have accelerated the pace of gene discovery, and will be invaluable in efforts to integrate all the different protective and repair mechanisms that function in concert to confer acquired tolerance.