New correction algorithms for multiple comparisons in case–control multilocus association studies based on haplotypes and diplotype configurations

The multiple comparison problem arises in population-based studies when the association between phenotypes and multilocus genotypes is examined. Although Bonferroni’s correction is often used to cope with such a problem, it may yield too conservative conclusions because all of the tests are assumed to be independent. We have developed new correction algorithms for the test of independence between phenotypes and multilocus genotypes at loci in linkage disequilibrium. In one of the algorithms, the exact type I error rate is calculated for the independency test. We found that such exact probabilities can be calculated using a 128 CPU PC cluster if the numbers of cases and controls are not more than 50. As an alternative method, we developed algorithms to calculate asymptotically the type I error rates using a Markov-chain Monte Carlo sampler that provided a good approximation to values calculated by the exact method. When the new algorithms were applied to both simulation and real data, the real overall type I error rates for the loci in linkage disequilibrium were from one-third to half as high as those obtained by Bonferroni’s correction. These algorithms are likely to be useful for multilocus association studies for data obtained by case–control and cohort studies.     

Alterations of cellular redox state during NNK-induced malignant transformation and resistance to radiation

Cancer cells often exhibit increased reactive oxygen species generation and altered redox regulation. The current study was conducted to investigate the biochemical and molecular events associated with redox alterations during chemical-induced malignant transformation and to evaluate their potential roles in radiation sensitivity. Immortalized nonmalignant human bronchial epithelial cells were exposed to the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and a clone of cells exhibiting malignant behaviors was isolated and characterized. This clone initially exhibited an increase in cellular superoxide that eventually decreased after a long-term culture in vitro, associated with altered expression of antioxidant molecules, including an increase in thioredoxin-1 and manganese superoxide dismutase, and a decrease in glutathione peroxidase-1. These cells also showed a significant decrease in sensitivity to ionizing radiation, as demonstrated by less cell death in acute apoptosis analyses and long-term cell proliferation assays. Using biochemical redox modulation and siRNA approach, we showed that the increase in thioredoxin-1 played a significant role in conferring resistance to IR. Although there was a substantial increase in cellular glutathione, inhibition of glutathione synthesis did not increase IR sensitivity. Our study showed complex redox alterations during NNK-induced malignant transformation, and identified Trx-1 as a radiosensitivity modulator.     

Are CD8+CD122+ cells regulatory T cells or memory T cells?

We identified CD8(+)CD122(+) regulatory T cells in the mouse. Some immunologists consider CD8(+)CD122(+) cells to be memory T cells despite our report of their regulatory function. Here, we propose a dual phenotype of these cells. Murine CD8(+)CD122(+) T cells demonstrate both memory and regulatory features in their functional profiles. Human CD8(+)CXCR3(+) T cells, which are thought to be the human counterpart of murine CD8(+)CD122(+) regulatory T cells, do not match human central memory T cells of the CD8(+)CD45RA(-)CCR7(+) phenotype. Thus, we must consider human CD8(+) regulatory T cells and murine CD8(+) regulatory T cells separately. Of human CD8(+) regulatory T cells, CD8(+)CXCR3(+) regulatory T cells can be divided into further subsets and we may be able to distinguish memory T cells and regulatory T cells. Of murine CD8(+)CD122(+) regulatory T cells, it seems to be impossible to divide CD8(+)CD122(+)CD44(+)CD62L(+) regulatory T cells into further subsets at present, indicating that this single population of cells has activities of both regulatory T cells and memory T cells.     

CD26/dipeptidyl peptidase IV regulates prostate cancer metastasis by degrading SDF-1/CXCL12

Stromal derived factor-1 (SDF-1 or CXCL12) expressed by osteoblasts and endothelial cells, and its receptors CXCR4 and CXCR7/RDC1 are key molecular determinants in prostate cancer (PCa) metastasis. What drives PCa cells into the extravascular marrow space(s) once they make contact with the blood vessel endothelium, however remains unclear. Here, we evaluated whether degradation of CXCL12 facilitates PCa cell entry into the marrow cavity by locally lowering CXCL12 levels intravascularly. To explore this possibility, co-cultured conditioned media from PCa cells and endothelial cells were evaluated for their ability to degrade biotinylated CXCL12 (bCXCL12). Co-culture of PCa cells/endothelial cells resulted in greater digestion of CXCL12 than was achieved by either cell type alone, and this activity regulated invasion in vitro. The ability to degrade CXCL12 was not however observed in PCa and osteoblasts co-cultures. Fractionation and inhibitor studies suggested that the activity was CD26/dipeptidyl peptidase IV (DPPIV) and possibly other cysteine/serine proteases. By inhibiting CD26/DPPIV, invasion and metastasis of PCa cell lines were enhanced in in vitro and in vivo metastasis assays. Together, these data suggest that the degradation of CXCL12 by CD26/DPPIV may be involved in the metastatic cascades of PCa, and suggests that inhibition of CD26/DPPIV may be a trigger of PCa metastasis. Yan-Xi Sun and Elisabeth A. Pedersen contributed equally to this work.     

Reduced expression of glyoxalase-1 mRNA in mood disorder patients

Glyoxalase-1 (Glo1) is an antioxidant enzyme which detoxifies alpha-ketoaldehydes to prevent the accumulation of pro-oxidant compounds, such as methylglyoxal, in all cell types. Glo1 has been suggested to be involved in anxiety disorders, autism, and Alzheimer's disease. Mood disorders have a high rate of comorbidity with anxiety disorders although, to date, little is known of the involvement of Glo1 in the pathophysiology of these conditions. In the present study, we examined the expression levels of Glo1 mRNA in peripheral white blood cells of mood disorder patients to understand the role of Glo1 in mood disorders. Quantitative real-time polymerase chain reaction experiments revealed that reduced expression of Glo1 mRNA was observed in major depressive and bipolar disorder patients in a current depressive state, as compared with healthy control subjects. In contrast, the expression of Glo1 mRNA in major depressive and bipolar patients, in a remissive state, showed no significant alteration when compared with healthy control subjects. These results suggest that the aberrant expression of Glo1 might be involved in the pathophysiology of mood disorders.     

Incorporation of a matrix metalloproteinase-sensitive substrate into self-assembling peptides - a model for biofunctional scaffolds

Controlling and guiding cell behavior requires scaffolding materials capable of programming the three-dimensional (3-D) extracellular environment. In this study, we devised a new self-assembling peptide template for synthesizing nanofibrous hydrogels containing cell-responsive ligands. In particular, the insertion of a matrix metalloproteinase-2 (MMP-2) labile hexapeptide into the self-assembling building blocks of arginine-alanine-aspartate-alanine (RADA) was investigated. A series of peptides, varied by the position of the MMP-2 hexapeptide substrate and the length of RADA blocks, were prepared by parallel synthesis. Their self-assembling capabilities were characterized and compared by circular dichroism spectroscopy and dynamical mechanical analysis. Among all the different insertion patterns, the sequence comprising a centrically positioned MMP-2 substrate was flanked with three RADA units on each side self-assembled into a hydrogel matrix, with mechanical properties and nanofiber morphology comparable to the native material built with (RADA)(4) alone. Exposure of the new gel to MMP-2 resulted in peptide cleavage, as confirmed by mass spectroscopy, and a decrease in surface hardness, as detected by nanoindentor, indicating that the enzyme mediated degradation was localized to the gel surface. The new design can be used for introducing biological functions into self-assembling peptides to create scaffolding materials with potential applications in areas such as tissue engineering and regenerative medicine.     

WT1 peptide vaccine for the treatment of cancer

Wilms' tumor gene WT1 is expressed in various kinds of cancers. Human WT1-specific cytotoxic T lymphocytes (CTLs) were generated, and mice immunized with WT1 peptide rejected challenges by WT1-expressing cancer cells without auto-aggression to normal organs. Furthermore, WT1 antibodies and WT1-specific CTLs were detected in cancer patients, indicating that WT1 protein was immunogenic. These findings provided us with the rationale for cancer immunotherapy targeting WT1. Clinical trials of WT1 peptide vaccination for cancer patients were started, and WT1 vaccination-related immunological responses and clinical responses, including reduction of leukemic cells, reduction of M-protein amount in myeloma, and shrinkage of solid cancer, were observed. Valuable information about immune responses against tumor antigens can be obtained by the analysis of samples from the vaccinated patients, which should lead to further improvement of cancer vaccine.     

The contribution of quasi-joint stiffness of the ankle joint to gait in patients with hemiparesis

Background

The role of ankle joint stiffness during gait in patients with hemiparesis has not been clarified. The purpose of this study was to determine the contribution of quasi-joint stiffness of the ankle joint to spatiotemporal and kinetic parameters regarding gait in patients with hemiparesis due to brain tumor or stroke and healthy individuals.

Methods

Spatiotemporal and kinetic parameters regarding gait in twelve patients with hemiparesis due to brain tumor or stroke and nine healthy individuals were measured with a 3-dimensional motion analysis system. Quasi-joint stiffness was calculated from the slope of the linear regression of the moment–angle curve of the ankle joint during the second rocker.

Findings

There was no significant difference in quasi-joint stiffness among both sides of patients and the right side of controls. Quasi-joint stiffness on the paretic side of patients with hemiparesis positively correlated with maximal ankle power (r = 0.73, P < 0.01) and gait speed (r = 0.66, P < 0.05). In contrast, quasi-joint stiffness in controls negatively correlated with maximal ankle power (r = − 0.73, P < 0.05) and gait speed (r = − 0.76, P < 0.05).

Interpretation

Our findings suggested that ankle power during gait might be generated by increasing quasi-joint stiffness in patients with hemiparesis. In contrast, healthy individuals might decrease quasi-joint stiffness to avoid deceleration of forward tilt of the tibia. Our findings might be useful for selecting treatment for increased ankle stiffness due to contracture and spasticity in patients with hemiparesis.