Biomedical subjects

H Hirano

Publications and source records attributed to H Hirano.

At least 109 records · Page 6Linked to original sources

PubMed1999

5'-upstream structure of the gene coding for chicken riboflavin-binding protein and its relation to estrogen induction.

To elucidate the mechanism of the estrogen-dependent induction of chicken riboflavin-binding protein (RfBP), we analyzed the 5'-upstream structure of its gene. A noncoding exon exists there, and around this sequence, 9 widely spaced half-palindromic estrogen-response element (ERE) motifs (5'-GGTCA or 5'-TGACC) were found. Furthermore, an imperfect ERE-like palindromic sequence (5'-ATGTCANNNTGACAT-3') was also found at the 2.25 kb upstream region. No consensus palindromic ERE was observed. By luciferase reporter assay, the regions containing the half ERE motifs and the imperfect ERE showed estrogen-dependent enhancer activities, suggesting that these two characteristic sequences might confer estrogen-inducibility upon the chicken RfBP gene. However the activities were lower than that of a consensus ERE. It remains uncertain whether these sequences act cooperatively.

5' Untranslated Regions↗

PubMed1999

Changes in levels of 8-hydroxyguanine in DNA, its repair and OGG1 mRNA in rat lungs after intratracheal administration of diesel exhaust particles.

Diesel exhaust particles (DEP), an environmental pollutant, are known to induce lung cancer in experimental animals. To clarify whether reactive oxygen species (ROS) are involved in its carcinogenic mechanism, we examined the levels of 8-hydroxyguanine (8-OH-Gua), its total repair and the repair enzyme OGG1 mRNA in female Fischer 344 rat lungs, as markers of the response to ROS, after DEP was intratracheally instilled. The 8-OH-Gua levels in both DEP-treated groups (2 and 4 mg) were increased during the 2-8 h following exposure to DEP. The 8-OH-Gua repair activities in the DEP-treated groups decreased during the period from 2 h to 2 days following DEP exposure and then recovered to the level of the control group at 5 days after exposure. OGG1 mRNA was induced in rats treated with 4 mg DEP for 5-7 days after administration. In conclusion, the 8-OH-Gua level in rat lung DNA increases markedly at an early phase after DEP exposure, by the generation of ROS and the inhibition of 8-OH-Gua repair activity, and induction of OGG1 mRNA is also a good marker of cellular oxidative stress during carcinogenesis.

Animals↗

PubMed1999

Insulin-like growth factor-1 content and pattern of expression correlates with histopathologic grade in diffusely infiltrating astrocytomas.

Studies of experimental tumorigenesis have strongly implicated signaling of the insulin-like growth factor 1 (IGF-1) as a key component in astrocytic neoplasia; however, its role in the growth of low-grade and malignant human tumors is not well understood. Correlative analyses of IGF-1, p53, and Ki-67 (MIB-1) immunohistochemistry and IGF-1 receptor (IGF-1R) mRNA expression were performed to examine the cellular pattern of IGF-1 signaling in 39 cases of astrocytoma (World Health Organization grades II-IV). Tumor cells expressing IGF-1 and IGF-1R were present in all tumor grades. The proportion of tumor cells that expressed IGF-1 correlated with both histopathologic grade and Ki-67 labeling indices, while expression of IGF-1R mRNA correlated with Ki-67 indices. In cases where stereotactic tissue sampling could be identified with a specific tumor area by neuroimaging features, the numbers of IGF-1 immunoreactive cells correlated with the tumor zones of highest cellularity and Ki-67 labeling. In glioblastomas, the localization of IGF-1 immunoreactivity was notable for several features: frequent accentuation in the perivascular tumor cells surrounding microvascular hyperplasia; increased levels in reactive astrocytes at the margins of tumor infiltration; and selective expression in microvascular cells exhibiting endothelial/pericytic hyperplasia. IGF-1R expression was particularly prominent in tumor cells adjacent to both microvascular hyperplasia and palisading necrosis. These data suggest that IGF-1 signaling occurs early in astroglial tumorigenesis in the setting of cell proliferation. The distinctive correlative patterns of IGF-1 and IGF-1R expression in glioblastomas also suggest that IGF-1 signaling has an association with the development of malignant phenotypes related to aberrant angiogenesis and invasive tumor interactions with reactive brain.

Astrocytoma↗

PubMed1999

Isolation and characterization of cytosolic and membrane-bound deubiquitinylating enzymes from bovine brain.

The deubiquitinylating enzymes (DUBs), that release free ubiquitin (Ub) from its precursors or ubiquitinylated proteins, are known to comprise of a large protein family in eukaryotes, but those in mammalian tissues remain largely unknown. Here we report the existence of unexpectedly large species of DUBs in both soluble and membrane-bound fractions of bovine brain, based on their ability to cleave (125)I-labeled Ub-fused alphaNH-MHISPPEPESEEEEEHYC (designated as Ub-PESTc). Two cytosolic enzymes, tentatively called sDUB-1 and sDUB-2, with molecular masses of about 30 kDa were purified to near homogeneity by Ub-Sepharose affinity chromatography. sDUB-1 and sDUB-2 corresponded to UCH-L3 and UCH-L1/PGP 9.5, respectively. Intriguingly, the particulate fraction of the brain homogenate was found to also contain strong activities against (125)I-Ub-PESTc, which can be solubilized by treatment with 5% n-heptyl-beta-D-thioglucoside and 1% Nonidet P-40, but not by washing with 1 M NaCl. From the solubilized material, two new 30-kDa, membranous DUBs (called mDUB-1 and mDUB-2) were purified to apparent homogeneity by Ub-Sepharose chromatography. Two other Ub-aldehyde sensitive DUBs, designated as mDUB-3 and mDUB-4, were also partially purified by conventional chromatographic operations. These mDUBs differed from each other in substrate specificity and exhibited different characteristics from the sDUBs, revealing that they are a new type of membrane-bound DUB. These results indicate the presence of divergent DUBs in mammalian brain, which may contribute to regulation of numerous pivotal cellular functions mediated by the covalent modification of Ub.

Amino Acid Sequence↗

PubMed1999

Immunohistochemical localization of beta-1,4-galactosyltransferase in human pancreatic tissues.

beta-1,4-Galactosyltransferase (GalTase) is the glycosyltransferase in the Golgi apparatus that transfers galactose from UDP-galactose to terminal N-acetylglucosamine residues in glycoconjugates with formation of a beta-1,4 linkage. Neoplasms undergo various changes in the carbohydrate moieties of their glycoconjugates. This process also indicates the possibility of changes in glycosyltransferases themselves. Therefore, we compared the binding pattern of a monoclonal antibody (MAb8628) against GalTase in both normal and neoplastic exocrine pancreatic tissues. Ten normal and 11 neoplastic human exocrine pancreatic tissues obtained from surgery were used. Frozen sections were incubated with this antibody. Supranuclear regions and terminal bars of normal duct cells and acinar cells revealed positive staining for GalTase at the light microscopic level. Centroacinar cells revealed positive staining in their perinuclear region. Neoplastic cells were also stained in their supranuclear regions and terminal bars. Supranuclear regions were well developed in neoplastic cells and intensely stained compared with those in normal cells. The supranuclear regions and the terminal bars corresponded to the trans cisternae of the Golgi apparatus and the junctional complex (i.e., tight junction and adherens junction), respectively, seen at the electron microscopic level. Pancreatic neoplastic changes thus led to an increase in the expression of GalTase in the Golgi apparatus, the increase of which may have an important effect on the intercellular adhesion and communication among pancreatic epithelial cells. Measurement of this enzyme is useful for diagnosis of exocrine pancreatic neoplastic changes from normal tissues.

Adenocarcinoma↗

PubMed1999

A case report: rare case of primary transitional cell carcinoma of the fallopian tube.

Carcinomas other than adenocarcinomas are extremely rare in the fallopian tube. A 42-year-old woman with watery, intermittent vaginal discharge was found to have a left adnexal tumor. This case was diagnosed as primary carcinoma of the fallopian tube, FIGO Stage Ia. She underwent a total abdominal hysterectomy, a bilateral salpingo-oophorectomy, a pelvic and periaortic lymphoadenectomy, and an omentectomy, followed by cisplatin-based chemotherapy. Four years after the initial diagnosis of the disease, she remains in a disease-free state. Histologically, the tumor revealed a primary transitional cell carcinoma of the left fallopian tube. The findings on an immunohistochemical test for an epithelial membrane antigen, the CA125 antigen, were positive, whereas findings on a test for CEA were negative. We report a case of a malignant neoplasm of the fallopian tube with histological features of transitional cell carcinoma that arose from the tubal epithelium.

Adult↗

PubMed1999

A Chinese traditional medicine, sho-saiko-to (xiao-chaihu-tang), reduces the bioavailability of tolbutamide after oral administration in rats.

The effects of Sho-saiko-to on the pharmacokinetics of tolbutamide were investigated in rats. After intravenous administration of tolbutamide (5 mg/kg), no significant change in the pharmacokinetics of tolbutamide was observed in both groups of single and multiple (7 days) pre-administration of Sho-saiko-to (500 mg/kg). In the study of single oral administration of tolbutamide (50 mg/kg), co-administration of Sho-saiko-to tended to accelerate the initial absorption rate of tolbutamide. The area under the plasma concentration-time curve of tolbutamide after oral administration was significantly reduced by Sho-saiko-to. Subsequently, a significant decrease was observed in the oral bioavailability of this drug when Sho-saiko-to was given concomitantly. These findings suggest that Sho-saiko-to reduces the bioavailability of tolbutamide after oral administration in rats, and that this change is not related to hepatic metabolism.

Algorithms↗

PubMed1999

Direct interaction between gingival fibroblasts and lymphoid cells induces inflammatory cytokine mRNA expression in gingival fibroblasts.

In inflamed periodontal lesions, dense infiltration of lymphocytes is usually observed in the extravascular periodontal connective tissue, adjacent to gingival fibroblasts. Our previous study revealed that activated lymphocytes can adhesively interact with gingival fibroblasts in vitro. In the present study, we investigated whether gingival fibroblasts are activated through direct interaction with lymphoid cells by monitoring the expression of inflammatory cytokine mRNA in human gingival fibroblasts (HGF). Co-culture with various human lymphoid cells in vitro resulted in a marked increase in the expression of IL-1alpha, IL-1beta, and IL-6 mRNA by the HGF. In addition, expression of the mRNA of the IL-1beta-converting enzyme (ICE), which is essential to produce the mature form of IL-1beta, was constitutively observed in the HGF, suggesting that mature IL-1beta is produced by these cells. When HGF were cultured with the culture supernatant of the lymphoid cells, the increase in the inflammatory cytokine mRNA expression was not observed. Similarly, when HGF and lymphoid cells were cultured in the same well but separated by a membrane which prevented direct contact between the cells, no increase in inflammatory cytokine mRNA expression was observed. These results strongly indicate that direct interaction between these heterotypic cell types transduces activation signals into HGF that induce an increase in inflammatory cytokine mRNA expression. Furthermore, IL-1beta mRNA expression in the HGF was synergistically increased when HGF directly interacted with lymphoid cells in the presence of exogeneous IL-1beta. The present study demonstrates that direct interaction between HGF and lymphoid cells stimulates HGF to increase inflammatory cytokine mRNA expression, and raises the possibility that heterotypic cell-cell interaction may facilitate local inflammatory reactions.

Caspase 1↗

PubMed1999

Distribution of ciprofloxacin into the central nervous system in rats with acute renal or hepatic failure.

Pharmacokinetic changes of various drugs have been reported in renal or hepatic failure. The present study employed ciprofloxacin, a quinolone antibiotic having neurotoxic side effects, to assess the influence of these diseases on distribution of ciprofloxacin into the central nervous system (CNS). After intravenous dosing of ciprofloxacin (10-30 mg kg(-1)), ciprofloxacin levels in plasma and brain were measured in normal rats (Wistar, male, 10-week-old) and those with acute renal and hepatic injuries which were induced by uranyl nitrate and carbon tetrachloride (CCl4), respectively. In the uranyl nitrate-treated rats, the plasma elimination half-life of ciprofloxacin was prolonged and the total body clearance was reduced when compared with those in the normal rats. Similar but smaller changes were observed in the CCl4-treated group. Brain levels of ciprofloxacin were significantly increased by both uranyl nitrate and CCl4 treatments. A proportional correlation between serum unbound levels and brain levels of ciprofloxacin was observed in the normal group. However, brain-to-serum unbound concentration ratios of ciprofloxacin were reduced in the rats with renal or hepatic failure. These results suggest that renal failure as well as hepatic failure retards elimination of ciprofloxacin from the blood, leading to elevation of the CNS level, and also that ciprofloxacin distribution in the brain is reduced in these disease states.

Animals↗

PubMed1999

Possible involvement of Ca2+ entry and its pharmacological characteristics responsible for endothelium-dependent, NO-mediated relaxation induced by thapsigargin in guinea-pig aorta.

Thapsigargin, a specific inhibitor of Ca(2+)-pump Ca(2+)-ATPase in the sarcoplasmic/endoplasmic reticulum (SR/ER), produces an endothelium-dependent vascular relaxation. In the present study, pharmacological features of thapsigargin-induced endothelium-dependent relaxation were functionally characterized in the isolated guinea-pig aorta especially focusing on the Ca2+ mobilization mechanisms in endothelial cells. Thapsigargin-induced endothelium-dependent vascular relaxation was markedly suppressed by N(G)-nitro-L-arginine (L-NNA) and calmidazolium, suggesting that the vascular relaxation to thapsigargin is largely attributable to endothelium-derived nitric oxide (NO) produced as a result of the activation of Ca2+, calmodulin-dependent NO synthase (NOS). Removal of Ca2+ from the external solution abolished the endothelium-dependent relaxation of guinea-pig aorta in response to thapsigargin. Thapsigargin-induced endothelium-dependent relaxation was inhibited more strongly compared with the endothelium-independent relaxation to an NO donor, SIN-1 (3-(4-morpholinyl)-sydnonimine), when the artery preparation was preconstricted with a high concentration (80 mM) of KCl instead of agonistic stimulation. Endothelium-dependent relaxation induced by thapsigargin was not affected by diltiazem, a blocker of L-type voltage-gated Ca2+ channels. SK&F96365 (1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1 H-imidazole) and Ni2+, both of which block capacitative Ca(2+) entry, did not show any appreciable inhibitory effects on the endothelium-dependent relaxation to thapsigargin. These findings suggest that in guinea-pig aorta, endothelium-dependent NO-mediated relaxation induced by thapsigargin is preceded by the increase in the cytosolic free Ca2+ concentrations ([Ca2+]cyt) following the depletion of stored Ca2+ in thapsigargin-sensitive store sites in endothelial cells. Although the increase in [Ca2+]cyt responsible for the activation of endothelium NOS leading to thapsigargin-induced vascular relaxation may be ascribed to the capacitative Ca2+ entry from extracellular space, the Ca2+ entry mechanism stimulated with thapsigargin is deficient in sensitivity to SK&F96365 and Ni2+ in the endothelium of guinea-pig aorta.

Animals↗

PubMed1999

Hyaluronic acid suppresses the reduction of alpha2(VI) collagen gene expression caused by interleukin-1beta in cultured rabbit articular chondrocytes.

In order to investigate how alpha2(VI) collagen gene is regulated by inflammatory cytokines in cultured rabbit articular chondrocytes, we examined the effect of interleukin-1beta (IL-1beta) on this collagen mRNA expression. Polylayer cultures of chondrocytes were exposed to IL-1beta (0.1, 1, 10 ng/ml). Quantitative detection of specific mRNA for this collagen was carried out by reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, to investigate the effect of hyaluronic acid (HA) on alpha2(VI) collagen mRNA expression by IL-1beta chondrocytes were exposed to IL-1beta (10 ng/ml) in the presence of HA (0.01, 0.1, 1 mg/ml) with molecular weight of 900 kDa. Chondrocytes were also exposed to IL-1beta (10 ng/ml) in the presence of HA (1 mg/ml) with molecular weights of 200, 900 and 2000 kDa. Alpha2(VI) collagen mRNA expression was decreased significantly in chondrocytes cultured with 1 and 10 ng/ml of IL-1beta. However, the addition of both IL-1beta and HA (0.1, 1 mg/ml) or both IL-1beta and HA (1 mg/ml) with all the molecular weight significantly suppressed these reduced mRNA levels. No tendency for this suppression to depend on the molecular weight was observed. These results suggest that suppression of transcriptional activity for type VI collagen will be associated with the reduction of cartilage matrix tissue and that HA will be associated with the suppression of the effect of IL-1beta.

Adjuvants, Immunologic↗

PubMed1999

Localization of the O-linked N-acetylglucosamine transferase in rat pancreas.

O-linked N-acetylglucosamine transferase (OGT) catalyzes the attachment ofN-acetylglucosamine (GlcNAc) monosaccharides to the hydroxyl group of serine or threonine residues of intracellular proteins and may play an important role in the hexosamine pathway. Glucose-induced insulin resistance is mediated by increased activity of the hexosamine pathway. In the present study, we examined the localization of OGT mRNA and OGT protein in the rat pancreas. The sites of OGT mRNA expression were determined by in situ hybridization histochemistry with a digoxigenin (DIG)-labeled antisense cRNA probe. Intense hybridization signals were present in the exocrine acinar cells, while weaker ones were detected in the islets of Langerhans. This distribution was confirmed using additional antisense cRNA or oligo-cDNA probes complementary to different regions of OGT mRNA. In addition, immunofluorescence staining with antibody raised against OGT stained both the exocrine acinar cells and endocrine islet cells. In the acinar cell nucleus, the zymogen granule region and contour of the cell were intensely stained. In the islets of Langerhans, especially in the alpha-cells, intense staining with anti-OGT antibody was observed. These staining patterns were almost identical to those seen when staining for the O-linked GlcNAc (O-GlcNAc) modification. Immuno-electron microscopy showed that OGT is localized to the euchromatin of the nucleus and around the secretory granules of exocrine acinar cells and endocrine islet cells. These results suggest that OGT is involved in the regulation of transcription and of granular secretion. Thus, one or more O-GlcNAcylated proteins may be important components of the glucose-sensing mechanism in the pancreas.

Animals↗

PubMed1999

Changes in lectin binding patterns in rat esophageal epithelium during development.

Changes in lectin binding patterns during the development of rat esophageal epithelium were examined by light- and electron-microscopy. For the light microscopical observations, 15 kinds of biotinylated lectins were used. Stainings with these lectins were weak before 17 days p.c. (post coitum). On the other hand, positive reactions were progressively observed after 18 days p.c. Among them, ConA and WGA showed a positive reaction on all layers of the epithelium; whereas DSA was positive for the middle and surface layers and UEA-1 was positive for only the middle layer. Electron microscopical observations revealed that UEA-1 showed a strongly positive reaction along the cell membranes of middle-layer cells, and on the apical cell membranes of basal cells. It also showed positive staining on Golgi membranes of the cells in the middle layer. ConA and DSA showed a positive reaction on cell, Golgi, and nuclear membranes. It was confirmed that the differentiation of the three layers (surface, middle and basal layers) of epithelial cells morphologically started to be observed after 17 days p.c. These results suggest that the distribution of glycoproteins in the esophageal epithelium changes in accordance with mucous epithelial cell differentiation.

Animals↗

PubMed1999

Modified cervical cerclage in pregnant women with advanced bulging membranes: knee-chest positioning.

BACKGROUND: Emergent cervical cerclage is often unsuccessful in patients with severely protruding fetal membranes for the following reasons: (1) difficulty in pushing the bulging membranes into the cervix; (2) risk of premature rupture of membranes during the operative procedures; and (3) displacement of the cerclage tape by the shortened cervix. METHODS: We performed Shirodkar's cervical cerclage with a slight modification. Using a metreurynter, a primary suture was made with the patient placed in the knee-chest position; a Shirodkar's cerclage was then performed in the dorsal lithotomy position. RESULTS: Since 1992, we have performed this procedure on five patients whose fetal membranes bulged into the vagina, at a gestational period of 20-24 weeks. When a patient was placed in the knee-chest position, the bulging membranes intruded spontaneously into the uterine cavity, but the procedure did not cause the membranes to rupture in any patient. The procedure prolonged the pregnancy to longer than 36 gestational weeks in two of the five patients. Three infants survived intact. CONCLUSIONS: Our promising experience warrants further studies on the advantages of the knee-chest position during the application of cervical cerclage in pregnant women who present with fetal membranes that bulge through a widely dilated cervix.

Adult↗

PubMed1999

The Listeria monocytogenes DnaK chaperone is required for stress tolerance and efficient phagocytosis with macrophages.

Listeria monocytogenes is a facultative intracellular pathogen which can escape bactericidal mechanisms and grow within macrophages. The intracellular environment of macrophages is one of the most stressful environments encountered by an invading bacterium during the course of infection. To study the role of the major stress protein, DnaK, of L. monocytogenes in survival under intracellular stress induced by macrophage-phagocytosis as well as under extracellular environmental stresses, we cloned, sequenced, and analyzed the dnaK locus from L. monocytogenes. Then we constructed an insertional mutation in the dnaK gene by homologous recombination and characterized it. Sequencing has revealed that the dnaK locus consists of four open reading frames in the order hrcA-grpE-dnaK-dnaJ. The mutant grows neither at temperatures above 39 degrees C nor under acidic conditions e.g. pH 3.0. Using the macrophage cell line JA-4, the ability of the dnaK mutant to grow intracellularly was examined. Immediately after phagocytosis, the number of viable dnaK mutant bacteria found within macrophages was significantly lower compared to that of intracellular wild type bacteria. However, following a 1-3 h latency period, the mutant multiplied in a similar fashion to the wild type within macrophage cells. A quantitative analysis of intracellular bacteria in macrophage cells by microscope and a binding assay of bacteria to the surface of macrophages by ELISA revealed that the lower number of viable dnaK mutant in macrophages after phagocytosis is due to the low efficiency of phagocytosis resulting from the reduced binding capacity of the dnaK mutant. These results demonstrate that DnaK of L. monocytogenes is essentially required for survival under high temperatures and acidic conditions. Though it does not largely contribute to the survival of L. monocytogenes in macrophage cells, it is essential for efficient phagocytosis. This is the first evidence that DnaK is required for the efficient phagocytosis of a facultative intracellular pathogen with macrophages.

Amino Acid Sequence↗

PubMed1999

Masticatory ability in relation to oral status and general health on aging.

In recent years in the field of clinical dentistry, and particularly in gerodontics, there has been a growing awareness of the importance of nutrition. Because a lack of masticatory ability leads to an impaired nutritional status, the dentist must be abreast of current knowledge on masticatory ability. Although there are many approaches to the measurement of masticatory ability with natural or functional teeth, there is no ideal method for this measurement in the elderly. This is because the elderly are usually missing more than half of their teeth, and thus have various dentitions. For example, the dentition of 70-years old subjects varies from no missing teeth to no remaining teeth. Moreover, the prosthetic appliances used vary from partial dentures to complete dentures. The present study was performed to establish a method for the objective assessment of masticatory ability which could be applied to the elderly, with their various dentitions. We demonstrated a useful jelly of varying hardness (G-1 jelly) for this assessment. In addition, we examined the correlation between masticatory ability, oral status and general health of the elderly, using this new assessment method.

Aged↗

PubMed1998

Physical and genetic maps of the Leptospira interrogans serovar icterohaemorrhagiae strain Ictero no.1 chromosome and sequencing of a 19-kb region of the genome containing the 5S rRNA gene.

We report the construction of physical and genetic maps of the chromosome of Leptospira interrogans serovar icterohaemorrhagiae strain Ictero No.1 using pulsed-field gel electrophoresis of DNA fragments generated by digestion with enzymes SrfI, AscI, FseI, and NotI and using reciprocal hybridization. We also sequenced the 19-kilobase (kb) DNA segment including the one gene for 5S rRNA (rrf) of pathogenic Leptospira. The size of the chromosome of the strain Ictero No.1 was estimated to be 4673kb and was found to be similar to those of the chromosomes of the leptospira strains Verdun (serovar icterohaemorrhagiae) and RZ11 (serovar pomona). The strains Verdun and RZ11 carry a small 350-kb replicon (minichromosome), and the strain Ictero No.1 also contained the same kind of molecule together with the chromosome. The physical maps of the strains Ictero No.1 and Verdun were almost identical, as were the locations of the selected genes, except for the location of one of the 16S rRNA genes. Overall, the genetic organization appeared to be conserved within the serovar icterohaemorrhagiae strains. In the sequenced region, we identified 10 putative ORFs and one rrf sequence, and the transcription orientations were all the same. A homology search for the products deduced from the sequenced data revealed that the orf H exhibited high similarity to malic acid enzyme of Haemophilus influenzae and fumarate hydratase of Escherichia coli (orf J). The rest of the putative products encoded by ORFs in the sequenced region showed little similarity with the proteins contained in the databases and were considered to be unknown proteins.

Bacterial Proteins↗

PubMed1998

Constitutive chemokine production results in activation of leukocyte function-associated antigen-1 on adult T-cell leukemia cells.

Adult T-cell leukemia (ATL) is characterized by massive infiltration of circulating ATL cells into a variety of tissues, a finding often associated with poor prognosis. Leukocyte migration from circulation into tissue depends on integrin-mediated adhesion to endothelium, and integrins are tightly regulated by several stimuli, such as inflammatory chemokines. However, the exact mechanisms that enhance adherence of leukemic cells to the endothelium and infiltration into tissues remain to be fully understood. We investigated the mechanisms of extravasation of leukemic cells using ATL cells and report the following novel features of endogenous chemokine-induced adhesion of ATL cells to the endothelium. ATL cells spontaneously adhered to endothelial cells without exogenous stimulation. Integrin leukocyte function-associated antigen-1 (LFA-1) on ATL cells was spontaneously activated. ATL cells produced high amounts of chemokines, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta. Adhesion of ATL cells to endothelial cells and the expression of activated form of LFA-1 were reduced by pretreatment with pertussis toxin, wortmannin, or anti-MIP-1alpha and MIP-1beta antibodies or transfection with antisense of MIP-1alpha or MIP-1beta. Spontaneous polymerization of cytoskeletal F-actin was observed in ATL cells, which was also inhibited by pertussis toxin and wortmannin. We propose that ATL cells adhere to endothelial cells through an adhesion cascade similar to normal leukocytes and that the chemokines produced by ATL cells are involved in triggering integrin LFA-1 through cytoskeletal rearrangement induced by G-protein-dependent activation of phosphoinositide 3-kinases in an autocrine manner. These events result in a strong adhesion of ATL cells to the endothelium and spontaneous transendothelial migration.

3-Phosphoinositide-Dependent Protein Kinases↗