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51.
Conserved tRNA gene cluster in starfish mitochondrial DNA 总被引:10,自引:0,他引:10
Howard T. Jacobs Shuichi Asakawa Takeyoshi Araki Kin-ichiro Miura Michael J. Smith Kimitsuna Watanabe 《Current genetics》1989,15(3):193-206
Summary Partial sequencing of mtDNA from four long-diverged species of starfish reveals the existence of a conserved cluster of 13 tRNA genes, organized in a manner similar to that of the tRNA cluster of sea urchin mtDNA, but located at a position distant from the presumed replication origin. These findings suggest that a clustered organization of tRNA genes may have been present in the ancestral mitochondrial genome, and raise the possibility that tRNAs may have catalyzed the dispersal rather than the accumulation of the genes which encode them. 相似文献
52.
Effect of serum amyloid P component level on transthyretin-derived amyloid deposition in a transgenic mouse model of familial amyloidotic polyneuropathy. 下载免费PDF全文
T. Murakami S. Yi S. Maeda F. Tashiro K. Yamamura K. Takahashi K. Shimada S. Araki 《The American journal of pathology》1992,141(2):451-456
To elucidate the pathogenesis of amyloid deposition associated with familial amyloidotic polyneuropathy (FAP), we developed several transgenic mouse lines carrying the human mutant transthyretin (TTR) gene. We found that human TTR and mouse serum amyloid P component (SAP) are deposited as amyloid in tissues of these mouse lines. Because SAP is a major acute-phase reactant in mice, we asked whether repeated injections of Escherichia coli lipopolysaccharide (LPS) would enhance the amyloid deposition in one of these transgenic mouse lines. During the course of repeated LPS injections, serum levels of SAP in the transgenic mice remained between severalfold to about 50-fold higher than seen in the absence of stimulation. As no significant difference was detected in the onset, progression, and tissue distribution of TTR-derived amyloid (ATTR) deposition between the LPS-stimulated and unstimulated transgenic mice, the induction of SAP synthesis by acute inflammation probably does not affect the onset and extent of ATTR deposition. 相似文献
53.
Breast milk macrophages spontaneously produce granulocyte-macrophage colony-stimulating factor and differentiate into dendritic cells in the presence of exogenous interleukin-4 alone 下载免费PDF全文
Ichikawa M Sugita M Takahashi M Satomi M Takeshita T Araki T Takahashi H 《Immunology》2003,108(2):189-195
Peripheral blood monocytes extravasate and differentiate into tissue macrophages to mediate effective local defence, but how tissue-specific stimuli and environments may influence their functions remains unknown. Here, we found that peripheral blood monocytes gained the ability to produce granulocyte-macrophage colony-stimulating factor (GM-CSF) upon exposure to breast milk and differentiated into CD1+ dendritic cells (DCs) in the presence of exogenous interleukin-4 (IL-4) alone. This in vitro observation appeared physiologically relevant since macrophages that were freshly isolated from breast milk were also found to produce GM-CSF spontaneously. Furthermore, in contrast to peripheral blood monocytes that differentiated into DCs only in the presence of both exogenous GM-CSF and IL-4, differentiation of breast milk macrophages into DCs was induced by incubation with exogenous IL-4 alone. These IL-4-stimulated breast milk macrophages were efficient in stimulating T cells, suggesting their potential role in mediating T-cell-dependent immune responses in situ. On the other hand, unexpected expression of DC-SIGN, a DC-specific receptor for human immunodeficiency virus (HIV), even in unstimulated breast milk macrophages, may favour HIV infection, resulting in an increased risk of mother-to-infant vertical transmission of the virus via breast milk. Thus, tissue-specific development of macrophages is often linked to effective local immunity, but may potentially provide an opportunity for a pathogen to spread and transmit. 相似文献
54.
An invasion-independent pathway of blood-borne metastasis: a new murine mammary tumor model 下载免费PDF全文
Sugino T Kusakabe T Hoshi N Yamaguchi T Kawaguchi T Goodison S Sekimata M Homma Y Suzuki T 《The American journal of pathology》2002,160(6):1973-1980
It is generally believed that active invasion by cancer cells is essential to the metastatic process. In this report, we describe a murine mammary tumor (MCH66) model of metastasis that does not require invasion into the vascular wall of both the primary tumor and the target organ, in this case, the lung. The process involves intravasation of tumor nests surrounded by sinusoidal blood vessels, followed by intravascular tumor growth in the lung, without penetration of the vascular wall during the process. Comparative studies using a nonmetastatic MCH66 clone (MCH66C8) and another highly invasive metastatic cell line (MCH416) suggested that high angiogenic activity and sinusoidal remodeling of tumor blood vessels were prerequisites for MCH66 metastasis. Differential cDNA analysis identified several genes that were overexpressed by MCH66, including genes for the angiogenesis factor pleiotrophin, and extracellular matrix-associated molecules that may modulate the microenvironment toward neovascularization. Our analyses suggest that tumor angiogenesis plays a role in the induction of invasion-independent metastasis. This model should prove useful in screening and development of new therapeutic agents for cancer metastasis. 相似文献
55.
Mineharu A Mori Y Nimura Y Takamaki A Araki M Yamaji J Yoshida R Takenaka H Kubota T 《The Japanese journal of physiology》2005,55(1):53-60
We examined the effect of the Ca(2+) concentration in the endolymph ([Ca](e)) or in the endolymphatic surface cells ([Ca](i)) on the endocochlear potential (EP) by using an endolymphatic or perilymphatic perfusion technique, respectively. (i) A large increase in [Ca](e) up to approximately 10(-3) M with a fall in the EP was induced by transient asphyxia ( approximately 2 min) or by the intravenous administration of furosemide (60 mg/kg), and a significant correlation was obtained between the EP and p[Ca](e) (= -log [Ca](e), r = 0.998). (ii) Perfusion of the endolymph with 10 mM EGTA for 5 min neither produced any significant change in the EP nor altered the asphyxia-induced change in EP (DeltaEP(asp)), suggesting that neither [Ca](e) nor the Ca(2+) concentration gradient across the stria vascularis contributed directly to the generation of the EP in the condition of low [Ca](e). In contrast, endolymphatic perfusion with high Ca(2+) (more than 10 mM) produced a decrease in EP and a significant correlation was obtained between the EP and the Ca(2+) concentration of perfusion solution (r = 0.982), suggesting that Ca(2+) permeability may exist across the stria vascularis. (iii) The administration of a Ca(2+) chelator, EGTA-acetoxymethyl ester (AM, 0.3 mM), to the endolymph, which produced a gradual increase in EP, suppressed significantly, by 60-80%, DeltaEP(asp) or furosemide-induced changes in EP. In contrast, perilymphatic administration of 0.5 mM EGTA-AM caused no significant suppression of the DeltaEP(asp). These findings suggest that [Ca](i) plays an important role in generating/maintaining a large positive EP. 相似文献
56.
Each animal was chronically implanted with bipolar electrodes in dorsal central gray matter (DCG) and was trained to press a lever to decrease the DCG-stimulation current. Chlordiazepoxide (5-20 mg/kg, PO), diazepam (2-10 mg/kg, PO) and bromazepam (1-5 mg/kg, PO) produced dose-dependent increases in the DCG-stimulation threshold 1-4 h after administration without affecting motor performance. Meprobamate (200 mg/kg, PO) and pentobarbital (10 mg/kg, PO) also slightly increased the stimulation threshold. Their potency was in the order of bromazepam greater than diazepam greater than chlordiazepoxide greater than pentobarbital greater than meprobamate. The increase in the threshold induced by diazepam (10 mg/kg, PO) was inhibited by the GABA antagonists, bicuculline (1 mg/kg, IP) and picrotoxin (0.1 mg/kg, IP). These results suggest that decreased susceptibility to brain stimulation is involved in suppressing effects of anxiolytic drugs on the escape behavior, and also that the antiaversive action of benzodiazepines may be related to a GABAergic mechanism. 相似文献
57.
58.
Effect of osteopontin alleles on beta-glucan-induced granuloma formation in the mouse liver 总被引:1,自引:0,他引:1 下载免费PDF全文
Tanaka K Morimoto J Kon S Kimura C Inobe M Diao H Hirschfeld G Weiss JM Uede T 《The American journal of pathology》2004,164(2):567-575
The granuloma formation is a host defense response against persistent irritants. Osteopontin is centrally involved in the formation of granulomas. Three osteopontin alleles, designated a, b, and c, have been found in mice. Here we used a murine model of zymosan (beta-glucan)-induced granuloma formation in the liver to determine possible functional differences between the osteopontin alleles in cell-mediated immunity. In contrast to mice with alleles a or c, mice with the allele b was defective in granuloma formation. As detected by mRNA expression, cytokines and chemokines known to be critically involved in granuloma formation were elicited in liver tissue, regardless of the osteopontin allele expressed. Alignment of the deduced amino acid sequences showed that unlike osteopontin c, b differs from a in 11 amino acids. All three osteopontin alleles had normal cell-binding properties. However, only the b allelic form was defective in the induction of cell migration as tested with dendritic cells. In conclusion, generation of a granulomatous response in mice depends critically on the presence of a functional osteopontin allele. Defective granuloma formation in mice with allele b is likely to be because of an impaired chemotactic function of the osteopontin b protein on immunocompetent cells. 相似文献
59.
Immunolocalization of extracellular matrix proteins and integrins in sarcoid lymph nodes 总被引:1,自引:0,他引:1
K. Shigehara Noriharu Shijubo Michio Hirasawa Shosaku Abe Toshimitsu Uede 《Virchows Archiv : an international journal of pathology》1998,433(1):55-61
To improve our understanding of the role of extracellular matrix (ECM) proteins and integrins during the processes of granuloma
formation in sarcoidosis, we examined the distribution of ECM proteins and the expression of integrins in sarcoid lymph nodes
by immunohistochemical methods. We also examined the expression of transforming growth factor-β1 (TGF-β1), which is one of
major regulators for synthesis of ECM proteins. Most ECM proteins were detected in the periphery of the granulomas in a concentric
pattern, and fibronectin was diffusely detected from an early to a regressive stage. Compared with normal lymph nodes, most
β1-integrin subfamilies (α1, α4, α5 and α6) were more strongly expressed on lymphocytes around the granulomas. Epithelioid
cells exhibited strong expression of the α5 molecule. Fibroblasts exhibited the expression of the α2 and α5 molecules surrounding
ECM proteins. The α5β1 molecule had a distribution similar to that of fibronectin. TGF-β1 was detected in epithelioid cells
throughout the various evolutional stages and its expression was especially marked in mature granulomas. Interaction of fibronectin
and the α5β1 molecule may have an important role in the process of formation of sarcoid granuloma. The expression of TGF-β1
may be involved in the regression of sarcoid granuloma by initiating fibrosis and atrophy of epithelioid cells.
Received: 2 December 1997 / Accepted: 19 February 1998 相似文献
60.
Toshimitsu Iwashita Munetomo Enjoji 《Virchows Archiv : an international journal of pathology》1987,411(4):305-309
Summary A clinicopathological and immunohistochemical study was done on 23 plexiform (multinodular) neurilemomas excised from 20 Japanese. Ages of the subjects ranged from 2 years to 69 years with a mean age of 30 years. The tumours occurred most often on the trunk (14), and were located commonly in the dermis and subcutis (19). Three lesions apparently originated from the peripheral nerve trunks. Multiple tumours were observed in six instances, and two were associated with von Recklinghausen's disease. Microscopically, they appeared as multinodular growths, most nodules were moderately cellular, and both Antoni A and B patterns were distinct in 10 tumours. Obvious Verocay bodies were noted in seven tumours and abortive ones in five. Immunohistochemical reactivity to S-100 protein was demonstrated in both nuclei and cytoplasm of almost all tumour cells of all lesions examined. Recurrences are nil among the 4 patients who could be followed. Correlations with trauma and with von Recklinghausen's disease are briefly discussed. 相似文献