Mink cell focus-forming murine leukemia virus infection induces apoptosis of thymic lymphocytes

In a previous study we identified the subpopulations of thymus cells that were infected by the lymphomagenic MCF13 murine leukemia virus (MLV) (F. K. Yoshimura, T. Wang, and M. Cankovic, J. Virol. 73:4890-4898, 1999) and observed an effect on thymus size by virus infection. In this report we describe our results which demonstrate that MCF13 MLV infection of thymuses reduced the number of T lymphocytes in this organ. Histological examination showed diffuse lymphocyte depletion, which was most striking in the CD4(+) CD8(+) lymphocyte-enriched cortical zone. Consistent with this, flow cytometric analysis showed that the lymphocytes which were depleted were predominantly the immature CD3(-) CD4(+) CD8(+) and CD3(+) CD4(+) CD8(+) cells. A comparison of the percentages of live, apoptotic, and dead cells of the gp70(+) and gp70(-) thymic lymphocytes suggested that this effect on thymus cellularity is a result of virus infection. Studies of the survival of thymic T lymphocytes in culture showed that cells from MCF13 MLV-inoculated mice underwent greater apoptosis and death than cells from control animals. Assays for apoptosis included 7-amino-actinomycin D staining, DNA fragmentation, and cleavage of caspase-3 and poly(ADP-ribose) polymerase proenzymes. Our results suggest that apoptosis of thymic lymphocytes by virus infection is an important step in the early stages of MCF13 MLV tumorigenesis.

Phorbol 12-myristate 13-acetate induces alteration in mucin gene expression and biological properties of colon cancer cells

Phorbol esters such as phorbol 12-myristate 13-acetate (PMA) have been reported to modulate diverse cellular responses through signal transduction pathways including the protein kinase C (PKC) pathway. In the present study, we sought to determine the effect of PMA on mucin gene expression and on the biological properties of a human colon cancer cell line, HM3. The cells were treated for 8 and 24 h with various concentrations of PMA and total RNA was extracted and Northern and slot blot analyses were carried out using MUC2, MUC3 and MUC5AC mucin cDNA probes to assess the steady state levels of mRNA. Spent media were collected and the level of cancer associated carbohydrate antigens (T, Tn, sialyl Tn, sialyl Lex, and sialyl Lea) and matrix-degrading metalloproteinase (MMPs) activity were examined. Trypsinized cells were used for assessing in vitro invasion, motility and adhesion to matrigel. Our results showed that PMA caused upregulation of steady state mRNA levels of MUC2, MUC3 and MUC5AC which was inhibited after treatment with protein synthesis inhibitors. Calphostin C, a highly specific inhibitor of protein kinase C significantly inhibited the PMA induced induction of mRNA levels of MUC2, MUC3, and MUC5AC. The levels of all cancer-associated mucin carbohydrate antigens examined in the media were increased by PMA treatment. PMA also caused an increase in MMPs activity and in in vitro invasion and motility properties, but did not affect adhesion of HM3 cells to matrigel. Thus, PMA caused a significant increase in the expression of all three mucin genes through signaling pathways involving protein kinase C and increased secretion of mucin associated carbohydrate antigens. These changes were associated with increases in MMP activity as well as by increases in the invasive and motility properties of HM3 colon cancer cells. These data suggest that protein kinase C signaling pathways may be involved in mucin gene regulation and in modulating the invasive and metastatic properties of colon cancer cells.

Inhibitory effect of sodium salicylate on nitric oxide production from TM4 sertoli cells

Nitric oxide (NO) has been proposed to play a role in a variety of inflammatory diseases. Sodium salicylate (NaSal) is the most commonly used anti-inflammatory agent. We investigated whether NaSal can diminish the production of NO in TM4 Sertoli cells. TM4 Sertoli cells produced a small amount of NO upon treatment with recombinant interferon-gamma (rIFN-gamma). The effect of rIFN-gamma was enhanced markedly by the addition of recombinant TNF-alpha (rTNF-alpha) in a dose-dependent manner. NaSal (10 and 20 mM) significantly inhibited NO production from TM4 Sertoli cells induced by rIFN-gamma plus rTNF-alpha. In addition, rIFN-gamma in combination with rTNF-alpha showed a marked increase of the expression of inducible NO synthase (iNOS) protein. Western blot analysis revealed that NaSal (10 and 20 mM) blocked a step of iNOS protein synthesis. The rIFN-gamma plus rTNF-alpha-induced nuclear factor-kappaB (NF-kappaB) activation was significantly blocked by NaSal (10 and 20 mM). On the other hand, neither staurosporine nor polymyxin B significantly inhibited NO production from TM4 Sertoli cells induced by rIFN-gamma plus rTNF-alpha. The present results indicate that NaSal inhibits rIFN-gamma plus rTNF-alpha-induced NO production in TM4 Sertoli cells via the signal transduction pathway of NF-kappaB activation.

Effects of microgravity and hypergravity on aging and longevity of insects

The effects of microgravity and hypergravity on aging are still poorly documented, particularly in mammals. However, there is a growing interest for the use of the fruit fly, Drosophila melanogaster, and this species may be now considered as a model organism in gravitational biology studies dealing with aging.

Dexamethasone suppresses tumor necrosis factor-alpha-induced apoptosis in osteoblasts: possible role for ceramide

Ceramide has been proposed as a second messenger molecule implicated in a variety of biological processes, including apoptosis. Recently, it has been reported that tumor necrosis factor-alpha (TNF-alpha) activates the release of ceramide and that ceramide acts as a mediator for the TNF-alpha-induced stimulation of the binding affinity of nuclear factor-KB (NF-KB), a ubiquitous transcription factor of particular importance in immune and inflammatory responses. In this study we demonstrate that dexamethasone, which reduces the production of ceramide, significantly inhibits TNF-alpha-induced activation of NF-KB, c-Jun N-terminal kinase, also known as stress-activating protein kinase, caspase-3-like cysteine protease, redistribution of cytochrome c, and apoptosis in MC3T3E1 osteoblasts. Compared with TNF-alpha-induced JNK activation, ceramide elicits a more rapid activation of JNK within 30 min. C2-ceramide activates NF-KB and caspase-3 like protease to the same degree and with kinetics similar to those of TNF-alpha. This study provides evidence that the release of ceramide may be required as a second messenger in TNF-alpha-induced apoptosis. These results also suggest a regulatory role for dexamethasone in TNF-alpha-induced apoptosis via inhibition of ceramide release. Therefore, our in vitro results suggest that therapies targeted at the inhibition of ceramide release may abrogate inflammatory processes in TNF-alpha-related diseases, including rheumatoid arthritis and periodontitis.

Taraxacum officinale inhibits tumor necrosis factor-alpha production from rat astrocytes

Substance P (SP) can stimulate production of tumor necrosis factor-alpha (TNF-alpha) from astrocytes stimulated with lipopolysaccharide (LPS). The objective of the current study was to determine the effect of Taraxacum officinale (TO) on the production of TNF-alpha from primary cultures of rat astrocytes. TO (100 and 1000 microg/ml) significantly inhibited the TNF-alpha production by astrocytes stimulated with LPS and SP. Interleukin-1 (IL-1) has been shown to elevate TNF-alpha production from LPS-stimulated astrocytes while having no effect on astrocytes in the absence of LPS. We therefore examined whether IL-1 mediated inhibition of TNF-alpha production from primary astrocytes by TO. Treatment of TO (100 and 1000 microg/ml) to astrocytes stimulated with both LPS and SP decreased IL-1 production significantly. Moreover, the production of TNF-alpha by LPS and SP in astrocytes was progressively inhibited with increasing amount of IL-1 neutralizing antibody. Our results suggest that TO may inhibit TNF-alpha production by inhibiting IL-1 production and that TO has an antiinflammatory activity in the central nervous system.

Inhibition of mast cell-mediated anaphylaxis by sochungryong-tang

According to traditional Asian philosophy, sochungryong-tang (S-Tang) is a prescription for treating exterior syndrome. In this study, we investigated the effect of S-Tang on mast cell-mediated anaphylaxis. S-Tang completely inhibited compound 48/80-induced systemic anaphylactic shock at a dose of 100 mg/kg. When S-Tang was given as pretreatment at concentrations ranging from 1 to 1000 mg/kg, the serum histamine levels induced by compound 48/80 were reduced in a dose-dependent manner. S-Tang inhibited the local anaphylaxis activated by anti-dinitrophenyl (DNP) IgE antibody, and also inhibited the histamine release from the rat peritoneal mast cells by compound 48/80 or anti-DNP IgE. These results indicate that S-Tang may contain substances with actions that inhibit mast cell degranulation.

Significance of serum and tissue carcinoembryonic antigen for the prognosis of gastric carcinoma patients

BACKGROUND AND OBJECTIVES

Carcinoembryonic antigen (CEA) has been widely accepted as a tumor marker useful in the diagnosis and management of colorectal carcinoma. When CEA levels are positive in patients with gastric carcinoma, they could be useful prognostic indicators. The value of CEA as a tumor marker for gastric carcinoma, however, remains a matter of controversy. The purpose of this study was to determine whether preoperative serum CEA value and tissue CEA staining are useful prognostic indicators for gastric carcinoma.

METHODS

We measured preoperative serum CEA levels by radioimmunoassay and stained tissue CEA production by tumor cells from gastric carcinomas using immunohistochemical staining in patients with gastric carcinoma.

RESULTS

The patients with preoperative serum CEA levels >10.0 ng/mL had a more prominent serosal invasion, much more lymph node involvement, more advanced stage and more poorly differentiated than did the patients with preoperative serum CEA levels <5.0 ng/mL. The survival rate of patients with serum CEA levels >10.0 ng/mL was poorer than those of patients with serum CEA levels between 5.0 and 10.0 ng/mL, and those of patients with serum CEA levels <5.0 ng/mL (P < 0.05). The preoperative serum CEA levels and tumor CEA-positivity were correlated (P < 0.05). In patients with lymph node metastases, the CEA-positivity (78.0%) was higher than in patients without lymph node metastasis (63.2%) (P < 0.05). A correlation was also found between the depth of tumor invasion and tissue CEA-positivity (P < 0.001). The postoperative survival rate was significantly better in the CEA-negative staining group (78.0%) than in the CEA-positive staining group (60.0%).

CONCLUSIONS

These data suggest that preoperative serum CEA levels and staining for CEA in gastric carcinoma tissue sections may have a predictive value in determining prognostic information for patients with resectable gastric carcinoma.

Biological properties and expression of mucins in 5-fluorouracil resistant HT29 human colon cancer cells

We have previously reported that HT29 human colon cancer cells selected by adaptation to 5-fluorouracil (5FU) (HT29-5FU cells) express increased levels of a major intestinal mucin MUC2 mRNA compared with parental HT29 cells. In this study, we examined in detail the changes in synthesis and secretion of mucin that occur in these cells and accompanying changes in the expression of cancer associated mucin related carbohydrate antigens and cell lineage associated biochemical markers. We further investigated their relationship to biological properties of cells. Northern blot analysis revealed a markedly increased level of MUC2 mRNA but no significant change in the mRNA levels of other mucins in HT29-5FU cells compared with parental HT29 cells. Labeling with radiolabeled precursors demonstrated increased synthesis and secretion of mucin glycoproteins by HT29-5FU cells. Immunoblot analysis showed a higher expression of mucin associated carbohydrate antigens such as T, Tn, sialyl Tn, sialyl Lea, sialyl Lex and non-O-acetylated sialic acid concomitant with significant increases in the expression of goblet cell lineage marker, MUC2 apomucin and a panepithelial cell marker, carcinoembryonic antigen. HT29-5FU cells showed significantly higher adhesion to E-selectin and to matrigel and in vitro invasive properties and significantly increased liver colonization capacity in nude mice following splenic vein injection. Nude mouse xenograft tumors produced by HT29-5FU cells showed a greater degree of differentiation, consisting of mucin secreting glands than those produced by parental HT29 cells. These results indicate that predominantly colonic type mucin, MUC2, has been selectively induced in HT29-5FU cells and that altered regulation of mucin genes associated with altered synthesis and secretion of mucin glycoproteins and the degree of differentiation in cancer cells may be responsible for the altered biological properties of these cells.

Platelet-derived growth factor (PDGF) receptor-alpha activates c-Jun NH2-terminal kinase-1 and antagonizes PDGF receptor-beta -induced phenotypic transformation

Platelet-derived growth factor (PDGF) is a potent mitogen for mesenchymal cells. The PDGF B-chain (c-sis proto-oncogene) homodimer (PDGF BB) and v-sis, its viral counterpart, activate both alpha- and beta-receptor subunits (alpha-PDGFR and beta-PDGFR) and mediate anchorage-independent growth in NIH3T3 cells. In contrast, the PDGF A chain homodimer (PDGF AA) activates alpha-PDGFR only and fails to induce phenotypic transformation. In the present study, we investigated alpha- and beta-PDGFR specific signaling pathways that are responsible for the differences between the transforming ability of PDGF AA and BB. To study PDGF BB activation of beta-PDGFR, we established NIH3T3 clones in which alpha-PDGFR signaling is inhibited by a dominant-negative alpha-PDGFR, or an antisense construct of alpha-PDGFR. Here, we demonstrate that beta-PDGFR activation alone is sufficient for PDGF BB-mediated anchorage-independent cell growth. More importantly, inhibition of alpha-PDGFR signaling enhanced PDGF BB-mediated phenotypic transformation, suggesting that alpha-PDGFR antagonizes beta-PDGFR-induced transformation. While both alpha- and beta-receptors effectively activate ERKs, alpha-PDGFR, but not beta-PDGFR, activates stress-activated protein kinase-1/c-Jun NH(2)-terminal kinase-1 (JNK-1). Inhibition of JNK-1 activity using a dominant-negative JNK-1 mutant markedly enhanced PDGF BB-mediated anchorage-independent cell growth, demonstrating an antagonistic role for JNK-1 in PDGF-induced transformation. Consistently, overexpression of wild-type JNK-1 reduced PDGF BB-mediated transformation. Taken together, the present study showed that alpha- and beta-PDGFRs differentially regulate Ras-mitogen-activated protein kinase pathways critical for regulation of cell transformation, and transformation suppressing activity of alpha-PDGFR involves JNK-1 activation.

Effective deacetylation of chitin under conditions of 15 psi/121 degrees C

Deacetylation of chitin under autoclaving conditions (15 psi/121 degrees C) was evaluated for the preparation of chitosan under different NaOH concentrations and reaction times. Deacetylation was effectively achieved by treatment of chitin under elevated temperature and pressure with 45% NaOH for 30 min and a solids/solvent ratio of 1:15. Treated chitosan showed similar nitrogen content (7.42%), degree of deacetylation (90.4%), and molecular mass (1560 kDa) but significantly higher viscosity values (2025 cP) compared with those (7.40%, 87.6%, 1304 kDa, and 143 cP, respectively) of a commercial chitosan. Reduction of the solids/solvent ratio from 1:15 to 1:10 did not affect degree of deacetylation, viscosity, and molecular mass of chitosan.

Reduced IL-2 but elevated IL-4, IL-6, and IgE serum levels in patients with cerebral infarction during the acute stage

Cytokines in the central nervous system (CNS) may play an important role in functioning as intercellular signals that orchestrate the response to injury. Whether this is a cause or result of the brain disease process is uncertain. We investigated IFN-gamma, IL-2, IL-4, IL-6, and IgE in the sera of 38 patients with cerebral infarction during the acute stage and 10 normal controls using an originally devised sensitive sandwich enzyme-linked immunosorbent assay (ELISA). We found that serum levels of IL-2 derived from T helper 1 (Th1) cells were slightly reduced in patients with cerebral infarction, whereas serum levels of IL-4 and IL-6 derived from Th2 cells were elevated significantly. IL-4 induces synthesis of IgE in human B cells. Endogenous IL-6 plays an obligatory role in IL-4-dependent human IgE synthesis. We observed that serum IgE levels were elevated significantly in patients with cerebral infarction. However, serum IFN-gamma levels were not elevated significantly in cerebral infarction patients. These findings suggest that elevated IL-4, IL-6, and IgE levels in the human serum may be an important factor in cerebral infarction during the acute stage. Decrease of IL-2 levels in the serum of patients with cerebral infarction may be a regulatory mechanism.

Inhibitory effect of anaphylactic shock by caffeine in rats

Caffeine is known to reduce evoked histamine secretion, but the effects of caffeine on anaphylactic shock have not been clarified. We have investigated the effects of caffeine on anaphylactic shock in rats. Systemic anaphylactic shock by compound 48/80 injection was monitored for 1 h. An IgE-dependent local anaphylactic shock was generated by sensitizing the skin with anti-dinitrophenyl (DNP) IgE followed 48 h later with an injection of antigen. Caffeine inhibited compound 48/80-induced anaphylatic shock to 40% with a dose of 1 mg/kg. Caffeine (0.1 mg/kg) inhibited to 56.4+/-0.4% passive cutaneous anaphylactic shock activated by anti-DNP IgE. Caffeine (5-20 mM) significantly inhibited histamine release from rat peritoneal mast cells (RPMCs) activated by compound 48/80 or anti-DNP IgE. Especially, caffeine (20 mM) inhibited by 96.7+/-0.5% histamine release activated by compound 48/80. Moreover, caffeine (1-20 mM) had a significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha production from RPMCs. The level of cAMP in RPMCs, when caffeine (20 mM) was added, increased significantly after 5-60 min compared with that of a normal control. These results indicate that caffeine inhibits immediate-type allergic reactions by inhibition of mast cell degranulation in vivo and in vitro.

Characterization of the human EPLIN (Epithelial Protein Lost in Neoplasm) gene reveals distinct promoters for the two EPLIN isoforms

EPLIN is a novel LIM domain protein that co-localizes to the actin stress fibers and focal adhesion plaques. We previously have demonstrated that two isoforms, the 600aa EPLIN-alpha and the 759aa EPLIN-beta, are generated from a single gene. In the majority of human breast and prostate cancer cell lines, the expression of EPLIN-alpha is significantly reduced, while the expression of EPLIN-beta is either up-regulated or unchanged. To understand the basis of this differential regulation, we have determined the organization of the human EPLIN gene. The human EPLIN100kb and consists of 11 exons. The EPLIN-beta mRNA requires all 11 exons, while the EPLIN-alpha mRNA requires Exons 4-11. The transcriptional start sites of EPLIN-alpha were mapped within the third intron by 5' RACE and S1 nuclease protection. Similarly, the 5' ends of EPLIN-beta were mapped upstream of Exon 1. The DNA sequences flanking the EPLIN-alpha or EPLIN-beta transcriptional start sites were capable of stimulating the expression of promoter reporter constructs. Interestingly, the endogenous transcription of EPLIN-alpha, but not EPLIN-beta, could be stimulated by serum, indicating that the expression of two EPLIN isoforms can be independently regulated. A consensus serum response element was present within 100bp upstream of the transcriptional start sites of EPLIN-alpha. The activity of 0.7kb EPLIN-alpha promoter reporter construct could be enhanced by activated RhoA, indicating that this serum response element is functional.

The stem of sinomenium acutum inhibits mast cell-mediated anaphylactic reactions and tumor necrosis factor-alpha production from rat peritoneal mast cells

The aqueous extract of Sinomenium acutum stem (SSAE) (0.1-1000 mg/kg) dose-dependently inhibited systemic anaphylactic reaction induced by compound 48/80 in mice. In particular, SSAE reduced compound 48/80-induced anaphylactic reaction with 50% at the dose of 1000 mg/kg. SSAE (100-1000 mg/kg) also significantly inhibited local anaphylactic reaction activated by anti-dinitrophenyl (DNP) IgE. When mice were pretreated with SSAE at a concentration ranging from 0.1 to 1000 mg/kg, the plasma histamine levels were reduced in a dose-dependent manner. SSAE (1-1000 microg/ml) dose-dependently inhibited histamine release from the rat peritoneal mast cells (RPMCs) activated by compound 48/80 or anti-DNP IgE. In addition, SSAE (0.1 microg/ml) had a significant inhibitory effect on anti-DNP IgE-induced tumor necrosis factor-alpha (TNF-alpha) production. These results indicate that SSAE inhibits mast cell-mediated anaphylactic reactions and TNF-alpha production from mast cells.

Production of hydrogen peroxide by serum and its involvement in cell proliferation in ROS 17/2.8 osteoblasts

The effects of hydrogen peroxide, which fetal bovine serum (FBS) releases, on proliferation have been studied in ROS 17/2.8 osteoblasts. Cell proliferation, when activated by FBS, was inhibited by catalase in ROS 17/2.8 osteoblasts, but did not in primary osteoblast-like cells. Serum-induced extracellular signal-regulated kinase(ERK) activity was reduced by the pretreated catalase in ROS 17/2.8 osteoblasts. In addition, the present studies demonstrate that addition of FBS led to an increase of fluorescence of dihydrorhodamine 123, indicating formation of free radicals including hydrogen peroxide in ROS 17/2.8 osteoblasts, but not in primary osteoblast-like cells. These phenomena may account for the generation of reactive oxygen species during cellular proliferation in ROS 17/2.8 osteoblasts.

Inhibitory effect of mast cell-mediated immediate-type allergic reactions by sulfapyridine

We examined the effect of sulfapyridine on mast cell-mediated immediate-type allergic reactions. Sulfapyridine (1 and 10 microg/kg) significantly inhibited systemic allergic reaction induced by compound 48/80 in rats. Sulfapyridine (1 and 10 microg/kg) also inhibited significantly local mast cell-mediated immediate-type allergic reactions activated by anti-dinitrophenyl (DNP) IgE. Moreover, sulfapyridine inhibited histamine release dose-dependently in the rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti-DNP IgE. When sulfapyridine was added, the level of cAMP in RPMC, transiently and significantly increased about 4-fold compared with that of basal cells. These results indicate that sulfapyridine inhibits mast cell-mediated immediate-type allergic reactions in vivo and in vitro.

Regulatory effect of cytokine production in patients with cerebral infarction by Yulda-Hanso-Tang

Yulda-Hanso-Tang (YH-Tang) is a prescription for the Taeumin cerebral infarction (CI) patients according to Sasang constitution philosophy. Taeumin patients with CI were treated with YH-Tang during the acute stage. Clinical signs of CI disappeared markedly in about 2 weeks after oral administration of YH-Tang in all patients. The mean interleukin (IL)-2 serum levels were lower in the patients with CI than in the normal groups, whereas the mean IL-4, IL-6 and IgE levels were significantly higher in the patients. There were no significant differences in interferon-gamma (IFN-gamma) levels between the groups. Serum IFN-gamma and IL-2 levels derived from T helper (Th)1 cells elevated significantly in the patients with CI by YH-Tang administration. Significant reduced serum levels of IL-4 and IL-6 derived from Th2 cells and IgE were observed in the patients treated with YH-Tang. During the period of YH-Tang administration, there were no other adverse effects. The data indicate that YH-Tang has a good CI treatment effect, and that its action may be due to regulation of cytokine production.

Change of telomerase activity in rectal cancer with chemoradiation therapy

Telomerase, an enzyme associated with cellular immortality, is expressed by most malignant cells and is inactive in most normal somatic cells, with the exception of proliferative stem cells, germ cells and activated lymphocytes. Measuring telomerase activity clinically may provide useful diagnostic and prognostic information of cancer. The purpose of this study was to investigate the change in telomerase activity following chemoradiation in rectal cancer, which almost always produces positive enzymatic activity. A total of 24 tumor tissue samples were used in this study, consisting of 12 paired specimens before and 4 weeks after chemoradiation. Telomerase activity was determined by PCR-based telomeric repeat amplification protocol (TRAP) assay. The telomerase activity was positive in 10 out of 12 patients (83%) in pre-irradiated and post-irradiated states. The levels of telomerase activity was decreased in 8 out of 10 patients after chemoradiation (80%) and two cases showed no change in enzymatic activity. One case showed no activity in either sample. The other case showed no enzymatic activity in the pre-irradiated sample, but showed weak activity in the post-irradiated sample. These data indicate that telomerase activity in rectal cancer is reduced after neoadjuvant chemoradiation therapy, possibly suggesting a mechanism of downstaging following chemoradiation therapy in cancer.

Cellular invasion of Orientia tsutsugamushi requires initial interaction with cell surface heparan sulfate

Role of transmembrane heparan sulfate proteoglycans on invasion of Orientia tsutsugamushi into host cells was investigated. Pretreatment with heparan sulfate and heparin inhibited the infection of O. tsutsugamushi for L cell, mouse fibroblast, whereas other glycosaminoglycans had little effect. These same treatments were also shown to reduce the infection in a dose-dependent manner, and enzymatic treatment of cells with heparitinase, but not chondroitinase ABC, inhibited the infection. In addition, mutant cell lines of Chinese hamster ovarian cell defective in heparan sulfate synthesis but not chondrotin sulfate synthesis and defective in all glycosaminoglycan synthesis showed marked reduction in susceptibility to infection by O. tsutsugamushi. Also mutant cell lines, which express heparan sulfate proteoglycans at low level, showed intermediate level of infectivity. Finally O. tsutsugamushi bind to(35)S-labelled heparin. Collectively, these findings provide strong evidence that heparan sulfate proteoglycans contribute to the attachment of O. tsutsugamushi to the cells.

Protective mechanism of glucose against alloxan-induced beta-cell damage: pivotal role of ATP

Glucose prevents the development of diabetes induced by alloxan. In the present study, the protective mechanism of glucose against alloxan-induced beta-cell damage was investigated using HIT-T 15 cell, a Syrian hamster transformed beta-cell line. Alloxan caused beta-cell damages with DNA fragmentation, inhibition of glucose-stimulated insulin release, and decrease of cellular ATP level, but all of these beta-cell damages by alloxan were prevented by the presence of 20 mM glucose. Oligomycin, a specific inhibitor of ATP synthase, completely abolished the protective effects of glucose against alloxan-induced cell damage. Furthermore, treatment of nuclei isolated from HIT-T15 cells with ATP significantly prevented the DNA fragmentation induced by Ca2+. The results indicate that ATP produced during glucose metabolism plays a pivotal role in the protection of glucose against alloxan-induced beta-cell damage.

Antibacterial properties and partial cDNA sequences of cecropin-like antibacterial peptides from the common cutworm, Spodoptera litura

The antibacterial properties and cDNA sequences of two types of antibacterial peptides from the haemolymph of immunized common cutworm, Spodoptera litura larvae, were determined. Since the primary structures of peptides deduced from cDNA sequences showed significant homologies to cecropins A and B, they were named as Spodoptera cecropins A and B. Spodoptera cecropins were broadly effective against Gram-positive and negative bacteria. They also retained antibacterial activities in all conditions tested (at pH 5.6-8.0 and in the presence of 50-150 mM NaCl) that was adapted to confirm the antibacterial properties of Spodoptera cecropins. These results indicate that the change of pH and the increase of salt concentration in the media do not influence the activities of Spodoptera cecropins. For the reverse transcription (RT)-polymerase chain reaction (PCR) to obtain the complete primary sequence, the primer designed according to the conserved region of the cecropin leader sequences was used, which was determined by the comparison of the cDNA sequences of known cecropins. The results from RT-PCR presented that the partial cDNAs of Spodoptera cecropins A and B encode 57 and 58 amino acids, including the sequences of mature peptides, respectively. In addition, Northern blot analysis with (32)P-labeled PCR product coding for Spodoptera cecropin A revealed that Spodoptera cecropin genes are expressed in immunized fat body, but not in normal fat body.

Protein kinase C independent activation of inducible nitric oxide synthase by tumor necrosis factor-alpha in TM4 Sertoli cells

To investigate the nitric oxide (NO) production and its signalling mechanism in TM4 Sertoli cells, the cells were treated with recombinant tumor necrosis factor-alpha (rTNF-alpha), recombinant interleukin-1 alpha (rIL-1alpha), or lipopolysaccharide (LPS), either alone or in combination with recombinant interferon-gamma (rIFN-gamma), and NO production was measured by using the Griess method. TM4 Sertoli cells produced a small amount of NO upon treatment with rIFN-gamma. The effect of rIFN-gamma was drastically increased by cotreatment with rTNF-alpha in a dose-dependent manner. However, combination of rIL-1alpha or LPS with rIFN-gamma did not synergize to activate cells. RIFN-gamma in combination with rTNF-alpha showed marked increase of the expression of iNOS protein. Protein kinase C inhibitors did not inhibit the production of NO induced by rIFN-gamma plus rTNF-alpha. These results suggest that the role of TNF-alpha is to provide TM4 Sertoli cells with the active cofactor for NO production and TNF-alpha-induced signaling for induction of NO synthesis is not dependent on protein kinase C activation.

H-ras, but not N-ras, induces an invasive phenotype in human breast epithelial cells: a role for MMP-2 in the H-ras-induced invasive phenotype

Elevated p21ras expression is associated with tumor aggressiveness in breast cancer including the extent of invasion into fat tissues, infiltration into lymphatic vessels and tumor recurrence. In the present study, we have examined the roles of H-ras and N-ras, members of the human ras gene family, in the pathogenesis of breast cancer. We show that H-ras, but not N-ras, induces an invasive phenotype in human breast epithelial cells (MCF10A) as determined by the Matrigel invasion assay, whereas both H-ras and N-ras induce anchorage-independent growth, as shown by soft agar assay. We examined the effects of H-ras and N-ras activation on the expression of MMP-2 and MMP-9, which can degrade type IV collagen, the major structural collagen of the basement membrane. We show that MMP-2 is efficiently induced by H-ras, whereas MMP-9 induction is more prominent in N-ras-activated MCF10A cells. We also show that H-ras-mediated invasiveness is significantly inhibited when the expression of MMP-2 is down-regulated, using an oligodeoxyribonucleotide complementary to the MMP-2 mRNA, or when MMP-2 activity is blocked by its inhibitor TIMP-2 (tissue inhibitors of matrix metalloproteinase-2). Our results show that the H-ras-induced invasive phenotype is associated more closely with the expression of MMP-2 in human breast epithelial cells, rather than the induction of MMP-9 expression, as shown previously for rat embryonic fibroblasts.