Cataracts among Chernobyl Clean-up Workers: Implications Regarding Permissible Eye Exposures

The eyes of a prospective cohort of 8,607 Chernobyl clean-up workers (liquidators) were assessed for cataract at 12 and 14 years after exposure. The prevalence of strictly age-related cataracts was low, as expected (only 3.9% had nuclear cataracts at either examination), since 90% of the cohort was younger than 55 years of age at first examination. However, posterior subcapsular or cortical cataracts characteristic of radiation exposure were present in 25% of the subjects. The data for Stage 1 cataracts, and specifically for posterior subcapsular cataracts, revealed a significant dose response. When various cataract end points were analyzed for dose thresholds, the confidence intervals all excluded values greater than 700 mGy. Linear-quadratic dose-response models yielded mostly linear associations, with weak evidence of upward curvature. The findings do not support the ICRP 60 risk guideline assumption of a 5-Gy threshold for "detectable opacities" from protracted exposures but rather point to a dose-effect threshold of under 1 Gy. Thus, given that cataract is the dose-limiting ocular pathology in current eye risk guidelines, revision of the allowable exposure of the human visual system to ionizing radiation should be considered.

Enhanced T-cell immunity induced by dendritic cells with phagocytosis of heat shock protein 70 gene-transfected tumor cells in early phase of apoptosis

The dual role of heat shock protein 70 (HSP70), as antigenic peptide chaperone and danger signal, makes it especially important in dendritic cell (DC)-based vaccination. In this study, we investigated the impacts of apoptotic transgenic MCA/HSP tumor cells expressing HSP70 on DC maturation, T-cell stimulation and vaccine efficacy. We found that DCs with phagocytosis of MCA/HSP in early phase of apoptosis expressed more pMHC I complexes, stimulated stronger cytotoxic T lymphocyte (CTL) responses (40% specific killing at an E:T cell ratio of 50) and induced immune protection in 90% of mice against MCA tumor cell challenge, compared with 25% specific CTL killing activity and 60% immune protection seen in mice immunized with DC with phagocytosis of MCA/HSP in late phase of apoptosis (P<0.05). Similar results were confirmed in another EG7 tumor model also expressing HSP70. Taken together, our data demonstrate that HSP70 on apoptotic tumor cells stimulate DC maturation, and DC with phagocytosis of apoptotic tumor cells expressing HSP70 in early phase of apoptosis more efficiently induced tumor-specific CTL responses and immunity than DCs with phagocytosis of apoptotic tumor cells in late phase of apoptosis. These results may have an important impact in designing DC-based antitumor vaccines.

159 LOCALIZATION OF CLAUDIN FAMILY PROTEINS IN PIG EMBRYOS DURING PRE-IMPLANTATION DEVELOPMENT

Tight junctions (TJ) are critical for blastocoel formation in mammalian pre-implantation embryos. Claudin family proteins, which are TJ proteins, are generally important for the barrier function of TJ. However, the expression and localization of claudin proteins are not clarified in mammalian pre-implantation embryos. The present study was designed to examine changes in the localization of claudin isoforms, claudin-1, -2, and -4, in pig parthenogenetic diploids through pre-implantation development. Oocyte–cumulus–granulosa cell complexes were collected from the follicles 4–6 mm in diameter, and then maturation-cultured. Only oocytes with a prominent first polar body were subjected to electro-stimulation after maturation, and they were treated with cytochalasin B to produce parthenogenetic diploids. Presumptive diploids were then cultured for 168 h and observed every 24 h. Embryos of each developmental stage from 2-cell to blastocyst were subjected to immunofluorescence staining of the anti-TJ proteins. Zona-free embryos were fixed and treated with rabbit anti-claudin-1 and -2 polyclonal antibodies or mouse anti-claudin-4 monoclonal antibody, followed by treatment with Alexa fluor 488-labeled goat anti-rabbit IgG antibody or goat anti-mouse IgG antibody. Some embryos were treated with rabbit anti-occludin antibody or anti-ZO-1 antibody for the detection of the TJ-net work. All embryos were counterstained with Hoechst 33342 and observed under an epifluorescence microscope after whole-mounting. The specific fluorescence for all TJ proteins examined was observed in embryos at all pre-implantation stages. Occludin and ZO-1 were detected in the cytoplasm before the morula stage (96 h), and localized toward the boundary region among cells from the morula and early blastocyst stages, reflecting the distribution of the tight junction in embryos. Claudin-1 and -2 localized in the cytoplasm at early-cleaving stages. They were detected in the nucleus after compaction, and the distribution of these proteins in the nucleus was dominant at the blastocyst stage. The distribution of the 2 claudin proteins in the nucleus was quite different; claudin-1 distributed rather homogeneously, but claudin-2 formed several bright spots in the nucleus. Claudin-4 also showed a unique distribution pattern in embryos; it was detected in the cytoplasm with strong fluorescence at the periphery of the nucleus of the 2- and 4-cell embryos. Claudin-4 changed its localization toward the boundary region of cells around the early blastocyst stage (120 h), and then the distribution of claudin-4 was restricted to the boundary region later in the blastocyst stage (144 h). These results indicate that claudin-4, but not claudin-1 and -2, is responsible for the formation of TJ in the pre-implantation embryos, although the function of these claudin proteins in the nucleus is unknown.

Progressive proliferative and dysplastic typhlocolitis in aging syrian hamsters naturally infected with Helicobacter spp.: a spontaneous model of inflammatory bowel disease

Helicobacter spp. have been implicated in a variety of gastrointestinal tract diseases, including peptic ulcer disease, gastric cancer, and inflammatory bowel disease (IBD), in humans and animals. Although most models of IBD are experimentally induced, spontaneous or natural models of IBD are rare. Herein, we describe a long-term study of chronic, progressive lesions that develop in the distal portion of the large bowel of unmanipulated Syrian hamsters naturally infected with Helicobacter spp. Twenty-four Syrian hamsters of three age groups (group A, 1 month [n = 4], group B, 7-12 months [n = 12], group C, 18-24 months [n = 12]), underwent complete postmortem examination. Results of microbial isolation and polymerase chain reaction and restriction fragment length polymorphism analyses confirmed the presence of Helicobacter spp. infection in the distal portion of the large bowel of all animals. Additionally, confounding pathogens, such as Clostridium difficile, Lawsonia intracellularis, and Giardia spp. that can cause proliferative enteritis, were absent in the hamsters of this study. Histopathologic scores for inflammation (P < 0.01), hyperplasia (P < 0.01), and dysplasia (P < 0.05) were significantly higher in the ileocecocolic (ICC) junction of animals in group C, relative to group A. Dysplastic lesions of various grades were detected in 5 of 11 hamsters in group C. Interestingly, the segment of the bowel that is usually colonized by Helicobacter spp. in hamsters had the most severe lesions. One hamster of group C developed a malignant fibrous histiocytoma, whereas another hamster developed a round cell sarcoma originating from the ICC junction. Thus, lesions in the distal portion of the large bowel of aging hamsters naturally colonized with Helicobacter spp. warrants developing the hamster as an animal model of IBD and potentially IBD-related cancer.

A multivariate model for ordinal trait analysis

Many economically important characteristics of agricultural crops are measured as ordinal traits. Statistical analysis of the genetic basis of ordinal traits appears to be quite different from regular quantitative traits. The generalized linear model methodology implemented via the Newton-Raphson algorithm offers improved efficiency in the analysis of such data, but does not take full advantage of the extensive theory developed in the linear model arena. Instead, we develop a multivariate model for ordinal trait analysis and implement an EM algorithm for parameter estimation. We also propose a method for calculating the variance-covariance matrix of the estimated parameters. The EM equations turn out to be extremely similar to formulae seen in standard linear model analysis. Computer simulations are performed to validate the EM algorithm. A real data set is analyzed to demonstrate the application of the method. The advantages of the EM algorithm over other methods are addressed. Application of the method to QTL mapping for ordinal traits is demonstrated using a simulated baclcross (BC) population.

Diverse signals converge at MAPK cascades in plant

Mitogen-activated protein kinases (MAPKs) are important signal transducing enzymes that connects diverse receptors/sensors to a wide range of cellular responses in mammals, yeasts and plants. In recent years, a large number of different components of plant MAPK cascades were isolated. Molecular and biochemical studies have revealed that plant MAPKs play important role in the response to a broad variety of biotic and abiotic stresses, including wounding, pathogen infection, temperature, drought, salinity, but also in the signaling of plant hormones and the cell division. This review briefly summaries the recent research results about the cross-talk and complexity of MAP kinase cascades in plant obtained from functional analyses.

HCHs and DDTs in sediment-dwelling animals from the Yangtze Estuary, China

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2-5.5 ng g(-1) and averaged 3.5 ng g(-1) in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g(-1), with a mean of 34.5 ng g(-1). In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g(-1) and averaged 13.8 ng g(-1), whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g(-1) with a mean value of 5.9 ng g(-1). The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.

Precision placement of instruments for minimally invasive procedures using a “needle driver” robot

Medical practice continues to move toward less invasive procedures. Many of these procedures require the precision placement of a needle in the anatomy. Over the past several years, our research team has been investigating the use of a robotic needle driver to assist the physician in this task. This paper summarizes our work in this area. The robotic system is briefly described, followed by a description of a clinical trial in spinal nerve blockade. The robot was used under joystick control to place a 22 gauge needle in the spines of 10 patients using fluoroscopic imaging. The results were equivalent to the current manual procedure. We next describe our follow-up clinical application in lung biopsy for lung cancer screening under CT fluoroscopy. The system concept is discussed and the results of a phantom study are presented. A start-up company named ImageGuide has recently been formed to commercialize the robot. Their revised robot design is presented, along with plans to install a ceiling-mounted version of the robot in the CT fluoroscopy suite at Georgetown University.

HCHs and DDTs in salt marsh plants (Scirpus) from the Yangtze estuary and nearby coastal areas, China

HCHs and DDTs in salt marsh plants taken from intertidal flats in the Yangtze estuary and coastal area in April and July 2002 were determined by GC-ECD. A significant seasonal effect was observed for HCHs and DDTs in sources and concentration levels in different sample types including above-ground tissues and roots as well as the whole plants and rhizospheric sediments. The results indicated that the concentration of t-HCH was higher in the above-ground tissues than in their roots in April; however, the partitioning of DDTs between contaminated sediments and the roots showed the higher concentrations of t-DDT in their roots. HCHs and DDTs concentration levels were higher in above-ground tissues than in roots in July. BCFs of HCHs and DDTs exhibited lower values with higher levels of contaminants in sediments, and higher values with lower levels in sediments.

Water Clusters on Graphite: Methodology for Quantum Chemical A Priori Prediction of Reaction Rate Constants

The properties, interactions, and reactions of cyclic water clusters (H(2)O)(n=1-5) on model systems for a graphite surface have been studied using pure B3LYP, dispersion-augmented density functional tight binding (DFTB-D), and integrated ONIOM(B3LYP:DFTB-D) methods. Coronene C(24)H(12) as well as polycircumcoronenes C(96)H(24) and C(216)H(36) in monolayer, bilayer, and trilayer arrangements were used as model systems to simulate ABA bulk graphite. Structures, binding energies, and vibrational frequencies of water clusters on mono- and bilayer graphite models have been calculated, and structural changes and frequency shifts due to the water cluster-graphite interactions are discussed. ONIOM(B3LYP:DFTB-D) with coronene and water in the high level and C(96)H(24) in the low level mimics the effect of extended graphite pi-conjugation on the water-graphite interaction very reasonably and suggests that water clusters only weakly interact with graphite surfaces, as suggested by the fact that water is an excellent graphite lubricant. We use the ONIOM(B3LYP:DFTB-D) method to predict rate constants for model pathways of water dissociative adsorption on graphite. Quantum chemical molecular dynamics (QM/MD) simulations of water clusters and water addition products on the C(96)H(24) graphite model are presented using the DFTB-D method. A three-stage strategy is devised for a priori investigations of high temperature corrosion processes of graphite surfaces due to interaction with water molecules and fragments.