Dendritic cells and macrophages are the first and major producers of TNF-alpha in pancreatic islets in the nonobese diabetic mouse

The nonobese diabetic (NOD) mouse spontaneously develops autoimmune insulin-dependent diabetes mellitus (IDDM) and serves as an animal model for human type I diabetes. TNF-alpha is known to be produced by islet-infiltrating mononuclear cells during insulitis and subsequent beta cell destruction and has been implicated in the pathogenesis of IDDM. Previously, T cells have been suggested as the main source of TNF-alpha in the islet infiltrate. However, on immunohistochemical analysis of TNF-alpha expression in islets, we are able to show that the staining pattern of TNF-alpha resembles that of dendritic cells (DC) and macrophages (Mphi) rather than T cells and that TNF-alpha is expressed in islets at the very early stages of insulitis when no T cells are detected. On double staining for TNF-alpha and cell surface markers, we can demonstrate that TNF-alpha staining clearly correlates with DC and Mphi, whereas there is a poor correlation with T cells. This feature was observed at both early and late stages of insulitis. TNF-alpha expression was also seen in NOD-SCID islets, in addition to a peri-islet infiltration consisting of DC and Mphi, indicating that T cells are not required for the early DC and Mphi infiltration and TNF-alpha expression in islets. In conclusion, our results show that DC and Mphi are the major, early source of TNF-alpha in the NOD islet infiltrate and that TNF-alpha can be expressed independently of T cells, indicating that the early DC and Mphi infiltration and expression of TNF-alpha are crucial in initiation of diabetes.     

Vibration of shear-deformable rectangular plates using a spline-function Rayleigh-Ritz approach

The prediction of the natural frequencies of vibration of rectangular plates or orthotropic laminates is described, through the use of B-spline functions as trial functions in a Rayleigh-Ritz approach. Through-thickness shear deformation effects are included in the analysis and hence assumptions have to be made for the spatial variation over the plate middle surface of each of the lateral deflection and the two rotation components. Two versions of the spline-function Rayleigh-Ritz approach are described: in one of these the deflection and rotations are represented by functions of the same polynomial order, whilst in the other a lower-order representation is used for each rotation component in one of the co-ordinate directions. It is shown in a number of applications that the former version leads to shear-locking behaviour whilst the latter version avoids this behaviour and is suitable for the analysis of both thick and thin plates.     

冷弯型钢桁架的强度和性能研究

对13个冷弯C型钢制成的全尺桁架构件进行了试验,分析了多种不同的加固方法以分析其对此截面性能提高的效果。采用集中点荷载给构件加载,模拟屋顶桁架的真实受力条件。结果显示:邻近踵板的上弦杆的局部屈曲是结构的主要破坏模式。板的畸变或蠕变会发生在没有充分加固的踵板处。研究还发现螺距的增加也会使得截面承载力增强。对连接踵板的上弦杆,踵板加劲肋和浅肋加劲板之间的踵连接的加固,能很明显地提高桁架的性能。同时采用了交互式设计公式和CSAS136-07中推荐的直接强度法对上弦杆进行了梁柱分析。     

A finite-deflection analysis of shallow arches by the discrete element method

The discrete element displacement method is used to analyse the finite-deflection behaviour of shallow arches. The arches are idealized as assemblies of shallow curved elements and the necessary properties of the displacement patterns in these elements are discussed. Numerical solutions of the geometrically non-linear problem are obtained by directly minimizing the total potential energy of the system.     

Vaccination against ergot alkaloids and the effect of endophyte-infected fescue seed-based diets on rabbits

Three sequential experiments were conducted with rabbits to 1) determine the effect of endophyte-infected (E+) tall fescue seed on rabbit performance and examine the effect of anti-ergot alkaloid immunization on rabbit performance and protectiveness against fescue toxicosis, 2) compare immunogens designed to elicit systemic anti-ergot alkaloid antibodies, and 3) select a superior adjuvant. In Exp. 1, rabbits (n = 6/treatment) fed E+ fescue seed diets (20%, 340 ppb total ergot alkaloids) had reduced (P < .05) intake and weight gain compared with endophyte-free (E-) controls, whereas apparent diet digestibility was not different between E+ and E-. Rabbits immunized against ergot alkaloids (E+ vac) with lysergol conjugated to human serum albumin (Ly-HSA) had greater (P < .05) intake than E+ rabbits during the wk 1 of a 3-wk dietary challenge. In Exp. 2, rabbits (n = 4/treatment) were immunized with Ly-HSA, with H100-B (ergot alkaloid hapten, H100-different protein carrier, B conjugate), or combinations of both with alum as adjuvant. Greatest (P < .001) anti-ergot alkaloid antibody (Ab) titer developed in the group immunized with H100-B. In Exp. 3, rabbits (n = 4/treatment) were immunized with the immunogen H100-B in conjunction with six adjuvants. Freund's incomplete adjuvant (FIA) in combination with DEAE-dextran and FIA alone gave highest anti-ergot titers. In summary, rabbit weight gain and intake were reduced by feeding E+ fescue seed diets, immunization against ergot alkaloids provided temporary improvement in intake, and H100-B conjugate with FIA or FIA + DEAE-dextran as adjuvants elicited a superior anti-ergot immune response. We believe that rabbits may serve as a model animal for fescue toxicosis research.     

Chromosomal characteristics of malignant lymphoma in northern pike (Esox lucius) from the United States

Chromosome analyses were performed on tumor cells and normal hematopoietic cells of northern pike bearing malignant lymphomas. The normal pike karyotype contains 50 acrocentric chromosomes, among which the sex chromosomes are not identifiable by available techniques. Metaphases from 19 primary lymphomas showed a consistent pattern of chromosome anomalies consisting of 1 submetacentric marker, 1 minute marker, and 3 to 5 pairs of smaller-than-normal chromosomes, set within a mode of 50 and a range of 46 to 54. Occasional cells had 2 identical submetacentric markers. Cells from presumptively normal renal hematopoietic tissue in 41 lymphoma-bearing pike showed the euploid karyotype, with the exception of 2 cases in which some cells with the neoplastic pattern were found. This probably indicated occult neoplastic involvement of renal hematopoietic tissue, in spite of the absence of histological evidence of involvement. In many cases, some of the cells taken directly from lymphomas bore the normal karyotype. It is not known whether these cells were reactive lymphoid cells or lymphoma cells that had not developed those anomalies typically associated with the tumors. The findings do not permit a conclusion regarding agent versus cellular transmission. However, the pike lymphoma is an excellent example of a neoplasm with a karyotypic "signature."     

Vapex—Gravity-assisted Film Drainage for Heavy Oil Recovery

Reservoir heavy oils of viscosity higher than 20 cp are difficult to recover efficiently. A new vapor extraction process called Vapex which uses horizontal wells and volatile solvents is being developed, primarily in Canada. This process lowers the viscosity of the oil by dilution and the oil is produced by gravity drainage (vertical movement of fluids) to horizontal wells placed low in the reservoir. More oil should be produced at lower production and energy costs. The Vapex process is outlined in this article and followed by some experimental work demonstrating gravity drainage flow in films at the macro- and micro-scale.     

QATAR'S OIL AND GASFIELDS: A REVIEW

In this paper, we review the oil- and gasfields located within the State of Qatar, and survey the discovery and development of hydrocarbons in Qatar over the past 60 years. This development history can be divided into two phases — before and after 1990. Until 1990, four producing areas had been identified, one onshore and three offshore. The single onshore field (Dukhan) has three oil-producing reservoirs, beneath which is a non-associated gas reservoir. Offshore, the first producing area comprises three oil and associated gasfields (Idd El Shargi, Maydan Mahzam and Bul Hanine); while the second is the super-giant North gasfield. Qatar also shares with Abu Dhabi the offshore Al-Bunduq gasfield. Although a number of other areas were explored by seismic survey and drilling, no further commercial oil was declared. Since 1990, however, there has been considerable further exploration around the offshore producing areas, and a number of new fields have been discovered (e.g. Al-Khalij, Al-Rayyan and Al-Shaheen).