Specific cell ablation is a useful method for analyzing the in vivo function of cells. We have developed a simple and sensitive method for conditional cell ablation in transgenic mice, called "toxin receptor-mediated cell knockout." We expressed the diphtheria toxin (DT) receptor in transgenic mice using a hepatocyte-specific promoter and found that injection of DT caused fulminant hepatitis. Three independently established transgenic lines demonstrated a good correlation between the sensitivity of hepatocytes to DT and the expression level of the DT receptors. Moreover, the degree of hepatocyte damage was easily controlled over a wide range of doses of injected DT without any obvious abnormalities in other cells or tissues. This system is useful for generating mouse models of disease and for studying the recovery or regeneration of tissues from cell damage or loss. As DT is a potent inhibitor of protein synthesis in both growing and non-growing cells, the method is applicable to a wide range of cells and tissues in mice or in other DT-insensitive animals.

Amyloid ␤-protein (A␤) assemblies are thought to play primary roles in Alzheimer disease (AD). They are considered to acquire surface tertiary structures, not present in physiologic monomers, that are responsible for exerting toxicity, probably through abnormal interactions with their target(s). Therefore, A␤ assemblies having distinct surface tertiary structures should cause neurotoxicity through distinct mechanisms. Aiming to clarify the molecular basis of neuronal loss, which is a central phenotype in neurodegenerative diseases such as AD, we report here the selective immunoisolation of neurotoxic 10 -15-nm spherical A␤ assemblies termed native amylospheroids (native ASPDs) from AD and dementia with Lewy bodies brains, using ASPD tertiary structure-dependent antibodies. In AD patients, the amount of native ASPDs was correlated with the pathologic severity of disease. Native ASPDs are anti-pan oligomer A11 antibody-negative, high mass (>100 kDa) assemblies that induce degeneration particularly of mature neurons, including those of human origin, in vitro. Importantly, their immunospecificity strongly suggests that native ASPDs have a distinct surface tertiary structure from other reported assemblies such as dimers, A␤-derived diffusible ligands, and A11-positive assemblies. Only ASPD tertiary structure-dependent antibodies could block ASPD-induced neurodegeneration. ASPDs bind presynaptic target(s) on mature neurons and have a mode of toxicity different from those of other assemblies, which have been reported to exert their toxicity through binding postsynaptic targets and probably perturbing glutamatergic synaptic transmission. Thus, our findings indicate that native ASPDs with a distinct toxic surface induce neuronal loss through a different mechanism from other A␤ assemblies.Neurodegenerative diseases, such as Alzheimer disease (AD), 2 Parkinson disease, prion diseases, and the polyglutamine diseases, arise from abnormal protein interactions in the central nervous system (1). In these diseases, complex multistep processes of protein conformational change and accretion produce various nonfibrillar assemblies, leading finally to fibrils (1-5). Recent studies have suggested that the early assemblies in this process might be the most toxic, possibly through the exposure of buried moieties and the formation of surface tertiary structures not present in physiologic monomers (6). These surface tertiary structures could mediate abnormal interactions with other cellular components (1).In AD, extensive studies have suggested that accumulation of amyloid ␤-protein (A␤), a physiologic derivative of amyloid precursor protein (APP), plays a primary pathogenic role (7-9). Various forms of assemblies ranging in mass from dimers up to multimers of ϳ1 MDa have been reported as neurotoxins (10 -13) as follows: protofibrils (14); dimers/trimers (natural low-n oligomers) (15); 3-24-mer A␤-(1-42) assemblies termed A␤-derived diffusible ligands (ADDLs) (16); 12-mers termed globulomers (17) or A␤*56 (18); 15-20-mer A␤ assemblies te...

Cross-linked samples of natural rubber (NR) and synthetic cis-1,4-polyisoprene (IR) were instantaneously expanded to a predetermined strain ratio,  s , using a newly-designed high-speed tensile tester. Crystallization behavior after the cessation of deformation was investigated. The high-cycle wide angle X-ray diffraction (WAXD) measurements could successfully reveal the drastic progress of crystallization within the first a few hundred milliseconds. Quantitative analysis of diffraction intensity clarified coexistence of fast and slow crystallization processes; time constants  f and  s , and amplitude I f and I s , respectively, were estimated for these processes. The values of  f were in the range of 50 to 200 ms, while  s ranged between 2.5 and 4.5 s. Almost linear dependence of I f and I s on  s was clarified. The crystallite size in the directions both parallel and perpendicular to the stretching direction decreased with the increase in timeaveraged nominal stress. The crystal lattice deformed almost linearly with the average nominal stress. For the fast process, correlation between crystallization and stress relaxation was not recognized, while linear relationship between them was found for the slow process. In every case, strain-induced crystallization was found to be the major origin of stress relaxation. Based on the results, effects of strain on crystallization of polymer melt were discussed.

Human myelogenous leukaemic cells can be induced to differentiate into the monocyte/macrophage pathway by protein inducers called differentiation inducing factors (DIF) in conditioned media of mitogen-stimulated human peripheral blood leukocytes. However, human DIF has not yet been well characterized. DIF is known to be a T-cell lymphokine, as it can be obtained from the T-cell line HUT-102 and can be partially purified from medium conditioned by phytohaemagglutinin (PHA)-stimulated lymphocytes. We found that monocytes also produce factor(s) that induce differentiation of human myelogenous leukaemia cell lines to cells with macrophage-like characteristics. This factor(s) has activity different from that of colony-stimulating factor(s) or interferons. We have now purified a DIF to homogeneity from medium conditioned by PHA-stimulated leukocytes using a human myeloblastic leukemia cell line, ML-1, as target cells. The purified DIF has a relative molecular mass (Mr) of approximately 17,000, with an NH2-terminal sequence the same as that of human tumour necrosis factor (TNF). Recombinant human TNF (rHuTNF) induces differentiation of ML-1 cells and an anti-pDIF monoclonal antibody can neutralize both differentiation inducing activity and cytotoxic activity of DIF and rHuTNF. The findings indicate that one of the DIF(s) produced by leukocytes is probably TNF.

Phase behavior of silica-filled poly(dimethylsiloxane) (PDMS) network was investigated by wide-angle X-ray diffraction (WAXD) under various strain ratio between room temperature and -100°C, and anomalous polymorphic behavior was discovered. At room temperature, when sufficient strain was applied, PDMS network was found to transform into the mesomorphic phase from which only a pair of sharp equatorial reflections and faint meridional scattering were obtained in the WAXD pattern. At low temperature, PDMS network crystallized into one of three different crystal forms according to strain ratio. These crystal forms were denoted as , transient and forms in the descending order of corresponding strain ratio. The mesomorphic phase at room temperature transformed into the crystalline  form by reducing temperature. There was an anomalous feature about the transition of the crystalline forms that the position of reflections in the WAXD pattern changed continuously and reversibly with strain between the  and the  forms through the transient form, while keeping the diffraction angles almost unchanged.3

Core-binding factor A1 (Cbfa1), also called Pebp2 A/ AML3, is a transcription factor that belongs to the runtdomain gene family. Cbfa1-deficient mice are completely incapable of both endochondral and intramembranous bone formation, indicating that Cbfa1 is indispensable for osteogenesis. Maturation of chondrocytes in these mice is also disorganized, suggesting that Cbfa1 may also play a role in chondrogenesis. The aim of this study was to examine the expression and regulation of Pebp2 A/ AML3/Cbfa1 expression in the chondrocyte-like cell line, TC6. Northern blot analysis indicated that Cbfa1 mRNA was constitutively expressed as a 6·3 kb message in TC6 cells and the level of Cbfa1 expression was enhanced by treatment with bone morphogenetic protein-2 (BMP2) in a time-and dose-dependent manner. This effect was blocked by an RNA polymerase inhibitor, 5,6-dichloro-1---ribofuranosylbenzimidazole, but not by a protein synthesis inhibitor, cycloheximide. Western blot analysis of the cell lysates using polyclonal antibody raised against Cbfa1 indicated that BMP2 treatment increased the Cbfa1 protein level in TC6 cells. In TC6 cells, BMP2 treatment enhanced expression of alkaline phosphatase and type I collagen mRNAs but suppressed that of type II collagen mRNA. In addition to TC6 cells, Cbfa1 mRNA was also expressed in primary cultures of chondrocytes and BMP2 treatment enhanced Cbfa1 mRNA expression in these cells similarly to its effect on TC6 cells. These data indicate that the Pebp2 A/AML3/Cbfa1 gene is expressed in a chondrocyte-like cell line, TC6, and its expression is enhanced by treatment with BMP.

Background: Motor three-wheel drivers provide an important means of transportation in Sri Lanka, comprising 15% of motorized road vehicles. Although three-wheel driving is a widespread occupation for Sri Lankan men, little is known about their general health or risk factors.Objectives: This paper investigates chronic illnesses and risk factors for such illnesses in a sample of 33 three-wheel drivers in Galle, Sri Lanka.Methods: A qualitative investigation was conducted between June and August 2012. 20 three-wheel drivers participated in 60-minute semi-structured interviews, and 13 participated in semi- structured focus groups related to their work-related health concerns.Results: Illness reported included musculoskeletal pain, hypercholesteremia, hypertension, and diabetes. Participants identified work-related stress and substance abuse as risk factors.Conclusions: Participants described a cycle of work related stress, substance use, and chronic illness. Community-based education on the risks of substance use and alternative means of coping may be an effective  intervention for these workers. DOI: http://dx.doi.org/10.3126/ijosh.v3i2.7662

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