CD1 expression defines subsets of follicular and marginal zone B cells in the spleen: beta 2-microglobulin-dependent and independent forms

We have used multicolor FACS analysis, immunohistology, and functional assays to study the expression of CD1 on B cell subsets from normal and beta 2m-/- mice. Two B cell subpopulations were identified that express high levels of CD1 in normal mice: splenic marginal zone B cells (IgMhigh IgDlow CD21high CD24intermediate CD23- CD43-) and a newly identified subpopulation of follicular B cells. The latter cells are unusual, because they are IgDhigh CD23+, like follicular B cells, but express high levels of CD21 and IgM, an expression pattern that is associated with marginal zone B cells. Therefore, the high-level expression of CD1 and CD21 was found to be closely associated on splenic B cells. Immunohistology confirmed the expression of CD1 on marginal zone B cells and on clusters of B cells in splenic follicles. Both the high-level CD1 expression by these cells and the low-level CD1 expression by subpopulations of B cells in the spleen, lymph node, peritoneal cavity, and bone marrow were markedly reduced in beta 2m-/- mice. Despite this, a CD1-restricted T cell clone proliferated vigorously in response to LPS-activated spleen cells that had been obtained from both beta 2m-/- and wild-type mice. This response was inhibited by the 3C11 anti-CD1 mAb. These results show the heterogeneity of B cell subsets in their expression of the beta 2m-dependent form of CD1. They further suggest that a beta 2m-independent form of CD1 is expressed on B cells that can stimulate T cells; however, this form is not easily visualized with the anti-CD1 mAb used here.     

The formation or the reduction of a disulfide bridge on the gamma subunit of chloroplast ATP synthase affects the inhibitory effect of the epsilon subunit

We have studied the change of the catalytic activity of chimeric complexes that were formed by chloroplast coupling factor 1 (CF1) -gamma, alpha and beta subunits of thermophilic bacterial F1 after formation or reduction of the disulfide bridge of different gamma subunits modified by oligonucleotide-directed mutagenesis techniques. For this purpose, three mutant gamma subunits were produced: gamma Delta194-230, here 37 amino acids from Pro-194 to Ile-230 are deleted, gammaC199A, Cys-199 is changed to Ala, and gamma Delta200-204, amino acids from Asp-200 to Lys-204 are deleted. All of the chimeric subunit complexes produced from each of these mutant CF1-gamma subunits and alpha and beta subunits from thermophilic bacterial F1 lost the sensitivity against thiol reagents when compared with the complex containing wild-type CF1-gamma. The pH optimum (pH 8.5-9.0) and the concentration of methanol to stimulate ATPase activities were not affected by these mutations. These indicate that the introduction of the mutations did not change the main features of ATPase activity of the chimeric complex. However, the interaction between gamma subunit and epsilon subunit was strongly influenced by the type of gamma subunit itself. Although the ATPase activity of the chimeric complex that contained gamma Delta200-204 or gammaC199A was inhibited by the addition of recombinant epsilon subunit from CF1 similarly to complexes containing the reduced wild-type gamma subunit, the recombinant epsilon subunit did not inhibit the ATPase of the complex, which contained the oxidized form of gamma subunit. Therefore the affinity of the epsilon subunit to the gamma subunit may be dependent on the state of the gamma subunit or the epsilon subunit may bind to the oxidized form of gamma subunit in a mode that does not inhibit the activity. The ATPase activity of the complex that contains gamma Delta194-230 was not efficiently inhibited by epsilon subunit. These results show that the formation or reduction of the disulfide bond on the gamma subunit may induce a conformational change in the region that directly affects the interaction of this subunit with the adjacent epsilon subunit.     

Mechanical behaviour of a combined joint composed of mechanical fastening and adhesive bonding

A study has been made of ‘combined’ joints consisting of mechanical fastening and adhesive bonding between rigid adherends. The mechanical characteristics of such ‘hybrid’ butt and lap shear joints have been derived by theoretical analysis. Results from experimental tests in combined joints giver reasonable agreement with the theoretical equations relating joint load to deformation.     

Temperature measurements of polymer melts in the heating barrel during injection molding. Part I. Temperature distribution along the screw axis in the reservoir

A new procedure has been developed to measure the temperature distribution of the polymer melts along the screw axis during injection by using a small sheath thermocouple. At the same time, the effects of molding conditions on temperature distribution has been studied. The temperature distribution of the polymer melt along the screw axis during injection can be obtained from the difference between the standard temperature profile and the temperature profile of the polymer melt with unknown and non-uniform temperature measured under the same rate of injection. The temperature of a polymer melt within a shot is not uniform. The difference between the maximum and the minimum temperature within a shot may exceed 10°C in some cases. There are two major factors which govern the effects of molding conditions on the temperature distribution of the polymer melts during injection. The first is the amount of shear heating in the metering zone. The second is the amount of heat absorbed into the polymer in the compression and feed zones.     

Determination of dissolved natural thorium and uranium in Horonobe and Mizunami Underground Research Laboratory groundwater and its thermodynamic analysis

At two underground research laboratories situated at Horonobe and Mizunami, Japan, trace amounts of natural thorium and uranium dissolved in deep groundwater were investigated with the help of chemical pre-concentration method. The groundwater was sampled from underground boreholes under the geochemical condition of no atmospheric exposure, and the colloid contribution was checked by in situ two size-fractionated ultrafiltration systems. A rough decrease by half in the concentration after in situ filtration suggested the presence of natural colloids and suspended matter that were carriers of a portion of the elements. The Th and U concentrations in groundwater after 10 kDa filtration was evaluated as dissolved species, and was identified thermodynamically using existing hydrogeological and geochemical data, such as the mineral components in the groundwater at a given pH, ionic strength, concentration of co-existing ions, redox potential, and a hypothetical solubility-limiting solid phase. The crystalline solid phase of tetravalent thorium and uranium dioxides made the solubility very low compared with that of the amorphous phase.     

Cultivation of rat hepatocytes in a medium based on commercially available infusate solutions

The possibility of using commercially available infusate solutions as a culture medium for hepatocytes was investigated in primary monolayer cultures of rat hepatocytes. The addition of Ca2+ to the infusate medium was necessary for hepatocytes to express their albumin secreting ability. The infusate medium supplemented with hormones (10(-7) M insulin and 10(-7) M dexamethasone) and Ca2+ (72.5 mg/l) allowed hepatocytes to produce albumin of an amount comparable to that produced in Williams' E medium. The activity of released lactate dehydrogenase (LDH) was kept at a low level throughout the cultivation in the infusate medium.     

Comparison of measured value and calculated value of multiplestability in forced-flow cooled superconductors

The multiple stability observed exclusively in forced-flow cooled superconductors is numerically calculated, and the result is quantitatively compared with the value measured by J.W. Lue et al. (1980). The calculated and measured values agreed well in certain cases, and did not in others. Based on this comparison, the effects of the transient heat transfer coefficient and ohmic heat generation on the quantitative prediction of stability are discussed. From this comparison, it is learned that a precise understanding of the transient heat transfer coefficient is essential for reliable predictions, and also that the ordinary evaluation method of ohmic heat generation, which considers the flux-flow resistance, tends to overevaluate the situation