Reliability of center of pressure measures of postural stability in healthy older adults: effects of postural task difficulty and cognitive load

Postural instability is a major risk factor of falling in the elderly. It is well documented that postural control may decline while performing a concurrent cognitive task and this effect increases with age. Despite the extensive use of dual tasking in balance assessment protocols, a lack of sufficient reliability information is evident. This study determines the reliability of the postural stability measures in older adults, assessed under single and dual-task conditions and different levels of postural difficulty. Sixteen older adults completed quiet stance postural measurements at three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed), with or without performing a concurrent backward counting task, in two sessions 1 week apart. Force plate data was used to calculate center of pressure (COP) parameters including mean velocity, phase plane portrait, area (95% confidence ellipse), standard deviation (SD) of amplitude, and SD of velocity. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), coefficient of variation (CV), and minimal metrically detectable change (MMDC) were calculated for each COP measure in all test conditions. Mean velocity, total phase plane, phase plane in ML direction, and SD of velocity in ML direction were the most reliable COP measures across all test conditions. ICC values were consistently higher in ML direction compared with AP direction. In general, velocity-related COP measures in ML direction showed to be highly reliable. Further research may explore the predictive and evaluative value of these COP parameters.     

Organizational justice at school and its associations with pupils' psychosocial school environment, health, and wellbeing

It has been shown that the psychosocial environment perceived by school staff is associated with children’s academic performance and wellbeing. In this study we examined the associations between organizational justice (procedural and relational justice) as reported by school staff and pupils’ perceptions of their school environment, health problems, academic performance, and absenteeism. We combined data from two surveys: for the staff (the Finnish Public Sector Study, n = 1946) and pupils (the Finnish school health promotion survey, n = 11,781 boys and 12,842 girls) of 136 secondary schools, collected during 2004–2005. Multilevel cumulative logistic regression analyses showed that after adjustment for potential individual and school-level confounding factors, low procedural justice was associated with pupils’ dissatisfaction with school-going. Low relational justice was associated with a 1.30 times higher risk of poor academic performance, 1.15 times higher risk of psychosomatic symptoms and 1.13 times higher risk of depressive symptoms among pupils. Both organizational justice components were associated with truancy. We concluded that staff perceptions of organizational justice at school are associated with pupils’ reports of their psychosocial school environment, health, performance, and absenteeism due to truancy. Improving managerial and decision making procedures among school personnel may be an important factor for protecting pupils’ academic performance and wellbeing.     

Aneurysmal bone cyst,a study of ultrastructure and malignant transformation

Summary Four cases of aneurysmal bone cyst, of which one became malignant 7 years after irradiation, were studied by electron microscopy. The aneurysmal bone cyst was composed of four different types of stromal cells — fibroblasts, myofibroblasts, osteoblasts, and histiocytes — and osteo-clastlike multinucleated giant cells. The surface of blood spaces was devoid of specialized endothelium, which may explain the presence of large quantities of extravasated erythrocytes. Some histiocytes contained siderosomes. The malignant lesion consisted of two main types of stromal cells, of which one had electron lucent and the other electron dense cytoplasm. The stromal cells produced osteoid and the tumour was regarded as an osteosarcoma. The multinucleated giant cells resembled those observed in aneurysmal bone cysts, but the nuclei seemed to be more often spherical. It is concluded that irradiation of the aneurysmal bone cyst may cause sarcomatous transformation in a cell capable of producing osteoid.     

A human follicular lymphoma B cell line hypermutates its functional immunoglobulin genes in vitro

The functional immunoglobulin (Ig) genes of B lymphocytes undergo somatic mutations during immune responses. These mutations modify the antigen binding site of the immunoglobulins, thereby enhancing the average affinity of the antibodies produced. The molecular mechanism underlying these B cell hypermutations remains unresolved, partly because it is difficult to grow normal B cells in long-term cell cultures and because there is no suitable transformed or malignant B cell line which generates mutations in its immunoglobulin genes in vitro. Here, we show that the recently established follicular lymphoma line HF-1.3.4 generates somatic hypermutations in vitro at a high frequency of 0.7 × 10^?6 mutations per base pair per generation in standard cell cultures (RPMI 1640 + 5% fetal calf serum). This shows for the first time that B cell hypermutation can occur without T cells or T cell factors. The mutation frequency increased approximately tenfold to 1 × 10^?5 mutations/base pair/generation with B cell-specific growth factors (interleukins ?2 and ?4 and three antibodies stimulatory to HF-1.3.4 cells). This HF-1.3.4 lymphoma line may help to elucidate the molecular mechanism of Ig gene hypermutation.     

Dental amalgam and multiple sclerosis: a systematic review and meta-analysis

OBJECTIVES: Amalgam restorations have long been controversial due to their mercury content. Allegations that the mercury may be linked to nervous disorders such as Alzheimer's, chronic fatigue syndrome, and multiple sclerosis (MS) have fueled the calls for the removal of amalgam restorations from dentists' armamentarium. To explore and quantify the association between amalgam restorations and MS we have conducted a systematic review and meta-analysis of the literature. METHODS: A systematic search in Medline (from 1966 to April 2006), EMBASE (2006, Week 16), and the Cochrane library (Issue 2, 2006) for English-language articles meeting specific definitions of MS and amalgam exposure was conducted. Studies were also identified using the references of retrieved articles. Studies were independently reviewed by two authors and disagreements were resolved by consensus. Studies were selected based on an a priori of defined criteria. Odds ratios (ORs) or relative risks were pooled using the random effects model. Heterogeneity was assessed using Q statistics. RESULTS: The pooled OR for the risk of MS among amalgam users was consistent, with a slight, nonstatistically significant increase between amalgam use and risk of MS. CONCLUSION: Future studies that take into consideration the amalgam restoration size and surface area along with the duration of exposure are needed in order to definitively rule out any link between amalgam and MS.     

Comparative genomic hybridization analysis of chromosomal changes occurring during development of acquired resistance to cisplatin in human ovarian carcinoma cells

The genetic changes underlying the development of resistance to the platinum-containing drugs are poorly defined. We analyzed six resistant cell lines using comparative genomic hybridization (CGH) in order to screen and identify possible genetic changes in common. We compared parental 2008 and A2780 human ovarian cancer cells to sublines selected for resistance to cisplatin (DDP) (2008/C8, 2008/C13*5.25, 2008/A, A2780/CP); we also compared 2008 cells to sublines selected for resistance to antimonite (2008/H) and arsenite (2008/I) which demonstrated cross-resistance to DDP. DNA samples from the resistant cell lines were hybridized against DNA from the parental cells rather than from normal human cells to permit detection of only those changes associated with the development of resistance. The DNA sequence copy number changes were surprisingly numerous in the DDP, antimony, and arsenite-resistant variants of the 2008 cell line and most of the chromosomes were affected. On the other hand, in the A2780/CP subline only a few changes were found and these were limited to just four chromosomes. The most common findings among the DDP-resistant cell lines were gains of material from chromosomes or chromosome arms 2q (5 out of 6 lines), 4 (4/6), 6q (5/6), and 8q (4/6). Deletions were observed on chromosomes or chromosome arms 2p (4/6), X (4/6), 7p (5/6), 11p (4/6), and 13 (4/6). The most frequently involved chromosomal regions, affected in the majority of cell lines, were: gain of 2q14.1–q33, 4p15.2–p13, 4q22–q25, 4q31.1–q34, 6q13–q16, 8q12–q21.2, and loss of Xp22.2–q21, 7p21–p14, 11cen-p14 in sublines of 2008, and loss of 2pter-p22 and 13q21 in sublines of 2008 and A2780. The results suggest that the acquired resistance and cross-resistance to DDP in these cell lines was associated with substantial genomic instability, quite unlike the changes observed in association with the development of resistance to drugs participating in the multidrug resistance phenotype. Genes Chromosom. Cancer 18:286–291, 1997. © 1997 Wiley-Liss, Inc.     

Frequent loss of the 11q14-24 region in chronic lymphocytic leukemia: A study by comparative genomic hybridization

The genetic basis and molecular pathogenesis of chronic lymphocytic leukemia (CLL) and the molecular mechanisms responsible for its progression remain poorly understood. Here, karyotyping techniques specifically optimized for CLL, comparative genomic hybridization (CGH), and fluorescence in situ hybridization were used to search for CLL-specific genetic aberrations. CGH and karyotyping both revealed copy number changes in 12 of the 25 CLL cases (48%) analyzed. Loss at 11q emerged as the most common aberration (6 cases), followed by a gain of chromosome 12 (4) and loss at 13q (3). Concordance between CGH and G-banding was found in 23 of the 25 cases (92%), which is more than reported in a recent similar CGH study of CLL. Owing to the basic differences in G-banding and CGH, however, their simultaneous clinical application is recommended. The frequent loss of 11q14-24 suggests that this chromosomal region deserves further attention as a candidate locus involved in the pathogenesis of CLL. Genes Chromosom. Cancer 19:286–290, 1997. © 1997 Wiley-Liss, Inc.