Necessity of IgE antibodies and mast cells for manifestation of resistance against larval Haemaphysalis longicornis ticks in mice

Genetically mast cell-deficient WBB6F1-W/Wv mice showed an apparent defect in manifestation of the resistance against larval Haemaphysalis longicornis ticks, but their serum IgE levels increased more than 100-fold after the second tick infestation. Immune sera obtained from the WBB6F1-W/Wv mice were adoptively transferred to the other WBB6F1-W/Wv mice which had received intracutaneous injections of WBB6F1-+/+ mouse-derived cultured mast cells. Because the resistance against ticks was detectable only when both mast cells and IgE antibodies were available, immediate hypersensitivity reaction appeared to have a physiologic role in the manifestation of the resistance against H. longicornis ticks.     

Photoaffinity labeling with dihydropyridine derivatives of crude membranes from rat skeletal, cardiac, ileal, and uterine muscles and whole brain

The characteristics of photoaffinity labeling with the calcium agonist [3H]Bay K 8644 (Bay) and the calcium antagonists [3H]nitrendipine (Nit) and (+)PN200-110 (PN) of crude membranes from rat skeletal, cardiac, ileal, and uterine muscles and whole brain were investigated. In all these crude membranes, [3H](+)PN (20 nM) was mainly photoincorporated into one protein band with a molecular weight of 30,000 - 41,000 Da. It was also incorporated into some other bands of all these crude membranes. The photoincorporation of [3H](+)PN into these crude membranes was inhibited by the presence of 20 microM unlabeled (+)PN. The photoincorporation of [3H](+)PN into these crude membranes depended on its dose and on the time of UV irradiation. No incorporation of [3H](+)PN was observed in the absence of UV irradiation. The incorporation was not affected by the presence of 1 mM CaCl2 and/or 0.15 M NaCl, but was significantly decreased by 20 microM (+)PN and slightly decreased by 20 microM (-)PN, 20 microM Bay, 1 mM diltiazem, or 1 mM verapamil. Namely, enantiomers of PN caused various extents of stereoselective inhibition of photoaffinity labeling by [3H](+)PN of specific protein bands in these crude membranes. [3H]Nit was photoincorporated into these crude membranes in the same way as [3H](+)PN, but [3H]Bay was not photoincorporated. However, 20 microM unlabeled Nit did not consistently inhibit photoaffinity labeling with [3H]Nit. These findings suggested that measurement of photoaffinity of crude membranes from rat skeletal, cardiac, and uterine muscles and whole brain with [3H](+)PN by UV irradiation is a useful method for investigating the characteristics of the voltage-dependent calcium channels that are affected by 1,4-dihydropyridine derivatives.     

A monoclonal antibody that triggers deacylation of an intermediate thrombin-antithrombin III complex

Upon incubation of antithrombin III with thrombin in the presence of a monoclonal antibody recognizing an epitope exposed on the heavy chain part of thrombin-cleaved two-chain antithrombin III, antithrombin III was preferentially cleaved by the enzyme as a substrate, rather than covalently complexed with the enzyme to form an equimolar, stable acyl complex. Once the stable acyl complex was formed between the enzyme and antithrombin III, however, no further liberation of two-chain antithrombin III was observed. Kinetic studies showed that heparin does not affect this reaction, although generation of thrombin-cleaved two-chain antithrombin III is apparently accelerated in accordance with the rate constant for heparin-enhanced thrombin-antithrombin III complex formation. Here we propose the term "switching antibody" for an antibody that triggers deacylation of an intermediate enzyme-inhibitor complex by switching the enzyme-inhibitor reaction from the major pathway of stable acyl complex formation to an alternative pathway of cleavage of the inhibitor as a substrate.     

In situ analysis of centromere segregation in C57BL/6 x Mus spretus interspecific backcrosses

The analysis of major satellite sequence differences between Mus spretus and laboratory mice provides a robust method for analyzing the centromere location for the genetic maps of each mouse chromosome. Fluorescence in situ hybridization (FISH) of a genomic probe, pMR196, for the laboratory mouse major satellite sequences was used to identify C57BL/6Ros (B6) pericentromeric heterochromatin in progeny of reciprocal backcross matings. These included 80 (B6xM. spretus)F₁xM. spretus progeny (BSS) and 70 (B6xM. spretus)F₁xB6 (BSB) progeny. FISH analysis of pericentromeric heterochromatin was conducted on the same metaphase spreads that were karyotypically analyzed for chromosomespecific banding patterns. Analysis of chromosomal segregation suggested that there was not primary deviation from random assortment during meiosis in the interspecific hybrid female, because nearly all of the 190 pair-wise comparisons did not deviate from expected and because there was no consistent pattern of deviation of the same chromosomes in the reciprocal backcross progeny from similar (C57BL/6xM. spretus)F₁ hybrid females. These results affirm the value of using the major satellite to genetically mark pericentromeric heterochromatin in the analysis of the segregation and assortment of centromeres in Mus interspecific crosses.     

Localization of the ATP-binding site in the 23-kDa and 20-kDa regions of the heavy chain of the skeletal muscle myosin head

Three kinds of ATP analogues were synthesized. These ATP analogues can be classified into two conformations, i.e. syn and anti forms with respect to the N-glycosidic bond between adenine and ribose groups of ATP. 3'-O-(N-Methylanthraniloyl)-2-azidoadenosine 5'-triphosphate (MantN2(3)ATP) is recognized as the anti form, as ATP, and the other two, 3'-O-(N-methylanthraniloyl)-8-azidoadenosine 5'-triphosphate (MantN8(3)ATP) and 1,N6-etheno-8-azidoadenosine 5'-triphosphate (epsilon N8(3)ATP) are both syn forms. Mant and etheno groups are both fluorescent which allows detection of their binding to proteins. The photochemical binding of azido groups in ATP analogues to the myosin active site, examined in the presence and absence of ATP, showed that all the analogues bound to the site of myosin ATPase. These analogues also acted as substrates of the ATPase and were hydrolyzed in the active site, as judged by competitive inhibition of the ATPase and by their ATPase activities. Of these analogues, MantN2(3)ATP is very similar to ATP in divalent-cation dependence of its hydrolysis rate and in its ability to trap ADP in the active site with vanadate, while the other two are different from ATP in these respects. The photochemical binding sites of ATP analogues were localized by gel electrophoresis of trypsinized myosin ATPase with photocross-linked ATP analogues and/or by isolating the modified peptides. MantN2(3)ATP was found in the 23-kDa fragment which has a structure common to ATP-binding proteins, i.e. Gly-Xaa-Xaa-Gly-Xaa-Gly-Lys-Thr. Mant N8(3)ATP was found in a region of the 20-kDa fragment where actin is reported to attach.     

Freeze-Fracture images on filipin-sterol complexes in the thyroid follicle epithelial cell of mice with special regard to absence of cholesterol at the site of micropinocytosis

Summary In order to clarify the distribution of cholesterol in the plasma-and cyto-membranes of the thyroid follicle cell, freeze-fracture images of the filipin-treated tissues of normal and TSH-treated mice were observed. The filipin-sterol complexes, 25 to 30 nm protuberances or pits are distributed densely and almost homogeneously on the fractured plasma membrane, though the small depressions showing aggregates of intramembrane particles lack the complexes. Each depression corresponds to the coated pit, which might be an initial site for micropinocytosis of the luminal colloid. The limiting membranes of all the large colloid droplets reabsorbed are generally very rich in the complexes, but some small regions on the limiting membrane of the droplet are less in their density. The membranes of the rough endoplasmic reticulum, of the nucleus and of the Golgi apparatus are almost free from the complexes, though small clusters consisting of 2–5 complexes are rarely scattered. In thin sections, the membranes which are rich in the filipinsterol complexes become obscure in their fine structure after treatment with filipin for 12–14 h.This study was supperted by grants from the Japan Ministry of Education     

Endogenous basic fibroblast growth factor-dependent induction of collagenase and interleukin-6 in tumor necrosis factor-treated human microvascular endothelial cells.

Tumor necrosis factor-alpha (TNF-alpha) has been shown to enhance the synthesis of interleukin-6 (IL-6) and collagenase in human omental microvascular endothelial (HOME) cell (Mawatari, M., Kohno, K., Mizoguchi, H., Matsuda, T., Asoh, K., Van Damme, J. V., Welgus, H. G., and Kuwano, M. (1989) J. Immunol. 143, 1619-1627). In the present study, we have examined whether the TNF-alpha-induced synthesis of IL-6 or collagenase in HOME cells is mediated by an inducible growth factor. Among several growth factors examined, we found that the expression of basic fibroblast growth factor (bFGF) mRNA was the one most prominently enhanced when HOME cells were treated with TNF-alpha. The increase of bFGF mRNA by TNF-alpha in HOME cells was observed in both a dose- and time-dependent manner when assayed by Northern blot analysis. The induction of bFGF mRNA was observed by 3 h after incubation with TNF-alpha, and the maximal increase of 5-fold was obtained after 12 h of incubation with 100 units/ml TNF-alpha. Western blot analysis confirmed the enhanced synthesis of bFGF by TNF-alpha. Metabolic labeling and immunoprecipitation assays of bFGF showed that exposure to TNF-alpha enhanced secretion of bFGF into culture medium and also that TNF-alpha stimulated the production of bFGF molecules with molecular masses of 18, 21, and 22.5 kDa in HOME cells. TNF-alpha induced the expression of collagenase mRNA and IL-6 mRNA in HOME cells as well, and the coadministration of neutralizing anti-bFGF antibody almost completely blocked the effects of TNF-alpha. The treatment of HOME cells with exogenous bFGF significantly stimulated the expression of collagenase mRNA and IL-6 mRNA in HOME cells. Therefore, the biological effects of TNF-alpha on HOME cells may be mediated, at least in part, by TNF-alpha-induced bFGF.     

Characterization of an abnormal fibrinogen Osaka V with the replacement of gamma-arginine 375 by glycine. The lack of high affinity calcium binding to D-domains and the lack of protective effect of calcium on fibrinolysis.

Prolonged thrombin time was completely corrected by the addition of millimolar concentrations of calcium in a new abnormal fibrinogen, Osaka V. Analysis of lysyl endopeptidase digests of A alpha-, B beta-, or gamma-chains by high performance liquid chromatography, and the following amino acid sequence analysis of relevant peptides revealed that about 50% of the gamma-chain has a replacement of gamma-arginine 375 by glycine. When fibrinogen was digested with plasmin in the presence of millimolar concentration of calcium, the amount of fragment D1 was about 50% of the normal control, and the rest was further cleaved to fragment D2, D3, or D62 with an apparent Mr of 62,000. Plasmic digestion of cross-linked fibrin in the presence of calcium resulted in the appearance of an abnormal fragment with an apparent Mr of 123,000 as well as fragments D2, D3, and D62, concomitant with the decrease of D dimer. The gamma-remnant of the abnormal fragment proved to be a cross-linked complex of the normal D1 gamma-remnant and residues 374-406/411 of the abnormal gamma-chain. The number of high affinity Ca(2+)-binding sites for the normal fibrinogen and fibrinogen Osaka V obtained by equilibrium dialysis was 2.88 (about 3) and 1.85, respectively, and that for the abnormal molecules was calculated as 0.9 (about 1) from their relative amounts in the samples, suggesting the lack of two Ca(2+)-binding sites in the D-domains. These data suggest that the normal structure of the COOH-terminal portion of the gamma-chain including residue 375 is required for the full expression of high affinity calcium binding to D-domains, the ability to be protected by calcium against plasmic digestion, and fibrin polymerization. During these studies, we found that the NH2-terminal amino acid of the gamma-remnant in fragments D or D dimer which were obtained after prolonged digestion with plasmin is gamma-Met89.