Enhancement of radiation induced cell death in chicken B lymphocytes by withaferin A

Withaferin A (WA), a plant withanolide, has shown significant radiosensitizing effect in vitro and in vivo. Inhibition of DNA repair has been suggested as a mechanism of radiosensitization by WA. To test this, the effect of withaferin A on survival of DT40 chicken B-lymphocyte cell line and its repair deficient single gene mutants Rad54-/-, Ku70-/- and double mutant Ku70-/- /Rad54-/- after irradiation was studied. Exponentially growing cells were treated for 1 hr with 5 microM WA and then exposed to different doses of X-rays. Cell survival was studied by clonogenic assay. WA significantly reduced survival of DT40, Ku70-/- and Ku70-/- /Rad54-/-, but not Rad54-/- cells, suggesting that WA enhances radiosensitivity by interfering with homologous repair, the major pathway of DSB repair in these cells. Inhibition of DNA repair is further indicated in a significant decrease in surviving fraction of DT40 cells by post-irradiation incubation with WA. This could have relevance to cancer radiotherapy.

Clock gene dysfunction in patients with obstructive sleep apnoea syndrome

Clock genes regulate mammalian circadian rhythms, and dysfunction of clock genes can contribute to various disorders. To investigate whether obstructive sleep apnoea syndrome (OSAS) influences clock gene function, the present authors examined Period1 (Per1) mRNA expression in vitro and in vivo. In eight healthy subjects and eight OSAS patients, plasma noradrenaline, serum interleukin (IL)-6, high-sensitivity C-reactive protein (hsCRP) and Per1 mRNA expression in peripheral whole blood were measured. Expression of Per1 mRNA in cultured cells was examined under IL-6 or noradrenaline stimulation in vitro. After noradrenaline was administered to mice in vivo, Per1 mRNA expression in the brain was examined. The concentrations of serum IL-6, hsCRP and plasma noradrenaline were elevated in OSAS patients, but improved by continuous positive airway pressure (CPAP) therapy. Per1 mRNA expression in the peripheral blood significantly decreased at 02:00 h by CPAP in OSAS patients. Stimulation with IL-6 did not directly induce Per1 mRNA in vitro. Administration of noradrenaline induced Per1 mRNA in the cerebral cortex of mice in vivo. The current study revealed that obstructive sleep apnoea syndrome caused clock gene dysfunction, and continuous positive airway pressure helped to improve it. Sympathetic activation and elevation of the plasma noradrenaline concentration in obstructive sleep apnoea syndrome may be one of the factors involved in disorders of Period1 mRNA expression.

Characterization of a proteolytic enzyme derived from a Bacillus strain that effectively degrades prion protein

AIMS

The purpose of this paper was to screen candidate bacterial strains for the production of proteases suitable for application to the degradation of pathogenic forms of prion protein (PrP(Sc)). This paper describes the biochemical characteristics and proteolytic activity of the isolated protease.

METHODS AND RESULTS

After screening more than 200 bacterial proteases for keratinolytic activity, we identified a Bacillus stain that produced a protease exhibiting high-degradation activity against a scrapie PrP(Sc). Sequence analysis indicated that this serine-protease belonged to the Subtilisin family and had optimum pH and temperature ranges of 9-10 and 60-70 degrees C. Western blotting analysis revealed that the protease was also capable of decomposing bovine spongiform encephalopathy-infected brain homogenate. In addition, the protease was demonstrated to degrade dried PrP(Sc) that had become firmly attached to a plastic surface considerably more effectively than proteinase K or PWD-1, a previously reported keratinase.

CONCLUSIONS

These results indicate that the isolated protease exhibited higher activity for PrP(Sc) degradation compared with other proteases examined.

SIGNIFICANCE AND IMPACT OF THE STUDY

This protease could be used under moderate conditions for the decontamination of precision instruments that are susceptible to PrP(Sc) contamination.

Fanconi anemia: genetic analysis of a human disease using chicken system

Fanconi anemia (FA) is a rare hereditary disorder characterized by skeletal abnormalities, bone marrow failure, and an increased incidence of cancer. The basic cellular abnormality in FA has been postulated to lie in the DNA repair mechanisms because cells from FA patients display chromosomal breakage, which is particularly remarkable following induction of DNA crosslinks. However, experimental evidence for this hypothesis has been lacking. To test whether DNA repair is really defective in FA cells, we disrupted several FA genes in chicken B cell line DT40. By measuring efficiency of gene conversion and hypermutation at the Immunoglobulin locus, we have shown that DT40 FA mutant cell lines exhibited defects in homologous DNA recombination, and possibly, translesion synthesis. However, levels of sister chromatid exchange, another important cellular event mediated by HR, were not reduced, possibly indicating the role of FA genes only in a subpathway of HR. Our results indicate that chicken DT40 cells could be highly useful in molecular dissection of basic biochemical processes, which are deficient in a human genetic disorder.

Genetic and epigenetic alterations in the differential diagnosis of malignant melanoma and spitzoid lesion

BACKGROUND

The histopathological differentiation of malignant melanoma and Spitz naevus often presents diagnostic problems.

OBJECTIVES

We aimed to find out applicable diagnostic parameters other than routine pathology.

METHODS

The cases included conventional melanomas and Spitz naevi as well as atypical spitzoid lesions that had posed diagnostic difficulties. We examined hotspots of mutation in the BRAF, NRAS and HRAS genes by polymerase chain reaction-based direct sequencing. We also analysed DNA copy number aberrations and the methylation of CpG sequences in several cancer-related genes by utilizing a novel methylation-specific multiplex ligation-dependent probe amplification method.

RESULTS

Twenty three of 24 conventional melanomas showed at least one of the genetic and epigenetic alterations examined, although one acral melanoma did not show any alteration. By sharp contrast, 12 Spitz naevi with an unambiguous histopathology showed no or few chromosomal aberrations, no oncogene mutations and no methylation of CpG sequences. Of the 16 ambiguous spitzoid lesions, most of which were designated atypical Spitz tumour by one of the authors, all but one showed no mutations, no methylations and few copy number aberrations. However, three tumours showed copy number loss of the cyclin-dependent kinase inhibitor 2A gene (CDKN2A), an alteration observed frequently in melanomas but not found in conventional Spitz naevi. These results show that, although most atypical Spitz tumours do not differ from conventional Spitz naevi showing virtually no genetic and epigenetic aberrations, some cases may have chromosomal aberrations that include copy number loss of the CDKN2A gene.

CONCLUSIONS

Genetic and epigenetic analyses may be useful as an additional diagnostic tool to distinguish between melanoma and Spitz naevus, and may help to define subgroups in atypical Spitz tumours.

Quantification of the rat spinal microglial response to peripheral nerve injury as revealed by immunohistochemical image analysis and flow cytometry

Microgliosis is implicated in the pathophysiology of several neurological disorders, including neuropathic pain. Consequently, perturbation of microgliosis is a mechanistic and drug development target in neuropathic pain, which highlights the requirement for specific, sensitive and reproducible methods of microgliosis measurement. In this study, we used the spinal microgliosis associated with L5 spinal nerve transection and minocycline-induced attenuation thereof to: (1) evaluate novel software based semi-quantitative image analysis paradigms for the assessment of immunohistochemical images. Microgliosis was revealed by immunoreactivity to OX42. Several image analysis paradigms were assessed and compared to a previously validated subjective categorical rating scale. This comparison revealed that grey scale measurement of the proportion of a defined area of spinal cord occupied by OX42 immunoreactive cells is a robust image analysis paradigm. (2) Develop and validate a flow cytometric approach for quantification of spinal microgliosis. The flow cytometric technique reliably quantified microgliosis in spinal cord cell suspensions, using OX42 and ED9 immunoreactivity to identify microglia.

The results suggest that image analysis of immunohistochemical revelation of microgliosis reliably detects the spinal microgliosis in response to peripheral nerve injury and pharmacological attenuation thereof. In addition, flow cytometry provides an alternative approach for quantitative analysis of spinal microgliosis elicited by nerve injury.

Bonding nature and structural phase transition in fullerene based nanomaterials

Rare-earth-metal-doped fullerides with a nominal composition of R3C70 (R = Sm, Eu, Yb) adopt a pseudomonoclinic structure in which C70 dimers glued with rare-earth ions are involved. High-temperature powder X-ray diffraction experiments revealed that the dimers undergo reversible first-order structural phase transitions, associated with reduction of the unit cell volume, similar to the results observed in previous high-pressure experiments. Structural analyses showed that C70 molecules are realigned to form closely packed structures, causing a reduction of volume at high temperature. The derived charge density map indicates that the transitions can be regarded as reversible structural changes from fullerene dimers to monomers. These features are ascribed to the unique bonding nature of rare-earth C70 compounds.

Specific detection of prion antigenic determinants retained in bovine meat and bone meal by flow microbead immunoassay

AIMS

The purpose of this study was to develop an effective method for detecting prion (PrP) antigenic determinants remaining in bovine meat and bone meal (MBM) using pressurized fluid extraction (PSE) equipment and flow microbead immunoassay (FMI).

METHODS AND RESULTS

Using the FMI, bovine recombinant PrP could be determined quantitatively in the 7 pmol-7 nmol range using anti-PrP peptide polyclonal antibody-coupled microbeads and anti-PrP monoclonal antibody (SAF61) as a detection antibody. PSE extraction at 120 degrees C for 5 min under high pressure was most effective for eluting PrP determinants from bovine MBMs. The FMI was capable of detecting PrP determinants in bovine MBM extracts with high specificity and indicated that the MBMs contained high levels of PrP determinants. This assay was also applied to the detection of PrP(Sc) determinants in bovine MBM spiked with a scrapie-infected brain at a weight ratio of 50 : 1.

CONCLUSIONS

These data indicate that this assay was effective for the specific detection of PrP determinants contained in bovine MBM extracts.

SIGNIFICANCE AND IMPACT OF THE STUDY

To our knowledge, this is the first report detailing the detection of PrP determinants in bovine MBM. The assay could be applied to securing the safety of bovine MBM.

[Right atrial blood cyst; report of a case]

A 53-year-old female was admitted to our hospital for examination of an abnormal shadow on chest X-ray. Computed tomography (CT) revealed a large mass of 3 cm in diameter in the right atrium. The mass arose from the right atrial septum and was removed with the interatrial septum. Histological specimen showed a blood cyst contained serous effusion.

Magnetic-field switching of crystal structure in an orbital-spin-coupled system: MnV2O4

We studied the magnetic and structural properties of spinel MnV2O4, which has S=5/2 spin with no orbital degrees of freedom on the Mn2+ site and S=1 spin and three orbital degrees of freedom on the V3+ site. We found that the ferrimagnetic ordering at TN=56.5K and the structural phase transition at Ts=53.5K are closely correlated in this compound and found a switching of crystal structure between cubic and tetragonal phases by the magnetic field. This phenomenon can be explained by the coupling between orbital and spin degrees of freedom in the t2g states of the V site.