Thromboxane A2 receptor is highly expressed in mouse immature thymocytes and mediates DNA fragmentation and apoptosis.

We have recently revealed that the thymus is the organ showing the highest expression of thromboxane (TX) A2 receptor in mice. In this study, thymic cell populations expressing the receptor were identified, and the effects of a TXA2 agonist on these cells were examined. Radioligand binding using a TXA2 receptor-specific radioligand revealed a single class of binding sites in the thymocytes with an affinity and specificity identical to those reported for the TXA2 receptor. The receptor density in these cells was comparable to that seen in blood platelets. This receptor is most highly expressed in CD4-8- and CD4+8+ immature thymocytes, followed by CD4+8- and CD4-8+ cells. The receptor density in splenic T cells was less than one fifth of that in CD4+8+ cells and no binding activity was detectable in splenic B cells. The addition of a TXA2 agonist, STA2, to thymocytes induced the disappearance of the CD4+8+ cells in a time- and concentration-dependent manner and caused DNA fragmentation. These changes were blocked by a specific TXA2 antagonist, S-145. These results demonstrate that TXA2 induces apoptotic cell death in immature thymocytes by acting on the TXA2 receptor on their cell surface and suggest a role for the TXA2/TXA2 receptor system in the thymic micro-environment.

Clinical effects of kestose, a prebiotic oligosaccharide, on the treatment of atopic dermatitis in infants.

BACKGROUND: Oligosaccharides may have beneficial properties of the prevention of atopic dermatitis (AD). Kestose, a fructo-oligosaccharide, stimulates the activity of bifidobacteria. OBJECTIVE: To assess the clinical effect of kestose on the treatment of AD in infants. METHODS: A randomized, double-blind, placebo-controlled trial was carried out using 15 and 14 infants with AD in the kestose group and placebo groups, respectively. One to 2 g kestose and maltose were administered to the subjects in the kestose and placebo groups, respectively, everyday for 12 weeks. Clinical evaluations of AD using Severity Scoring of Atopic Dermatitis (SCORAD) and the enumeration of bifidobacteria in the feces using real-time PCR were performed at Weeks 0, 6, and 12. RESULTS: The medians of the SCORAD score were significantly lower in the kestose group than in the placebo group on both Week 6 (25.3 vs. 36.4; P=0.004) and Week 12 (19.5 vs. 37.5; P<0.001). No significant correlation was found between the improvement of the SCORAD score and the count of bifidobacteria. CONCLUSION: Kestose was found to exert a beneficial effect on the clinical symptoms in infants with AD. The mechanism how does kestose improve the symptoms of AD remains to be elucidated.

Potentiation of glucocorticoid receptor (GR)-mediated signaling by the immunosuppressant tacrolimus in rheumatoid synoviocytes.

OBJECTIVE: The immunosuppressant tacrolimus is known to enhance many aspects of glucocorticoid. In this study, we investigated the effects of tacrolimus on glucocorticoid receptor (GR) signaling using rheumatoid fibroblast-like synoviocytes (RA-FLS). METHODS: The nuclear translocation of GR was analyzed by immunocytochemistry. The DNA binding activity of p65 was assayed by a functional ELISA kit using nuclear extracts. GR-associated FK506-binding protein-51 (FKBP-51) was analyzed by Western blotting following immunoprecipitation of glucocorticoid receptor (GR) complexes. RESULTS: High concentrations (10-7M) of Dexamethasone (Dex) induced GR translocation to the nucleus in RA-FLS. However, the nuclear GR translocation did not occur with low concentrations of Dex (10-9M). Tacrolimus treatment of RA-FLS results in potentiation of GR translocation to the nucleus even in the presence of a low concentration of Dex (10-9M). GR-associated FKBP-51 decreased after tacrolimus treatment. Furthermore, tacrolimus also decreased the IL-1Beta-induced DNA binding activity of p65, a subunit of NF-KappaB, in the presence of 10-9 M of Dex. CONCLUSION: These data suggest that tacrolimus exerts anti-inflammatory properties by potentiating the GR signaling through the GR-immunosuppressant-binding proteins (immunophilins) interaction and its nuclear transport in rheumatoid synovium.

A minimally hypomorphic mutation in Btk resulting in reduced B cell numbers but no clinical disease.

Reduced B cell numbers and a mutation in Btk are considered sufficient to make the diagnosis of X-linked agammaglobulinaemia. In the process of conducting family studies, we identified a 58-year-old healthy man with an amino acid substitution, Y418H, in the adenosine-5'-triphosphate binding site of Btk. Immunofluorescence studies showed that this man had 0.85% CD19+ B cells (normal 4-18%) in the peripheral circulation and his monocytes were positive for Btk. He had borderline low serum immunoglobulins but normal titres to tetanus toxoid and multiple pneumococcal serotypes. To determine the functional consequences of the amino acid substitution, a Btk- chicken B cell line, DT40, was transfected with expression vectors producing wild-type Btk or Y418H Btk. The transfected cells were stimulated with anti-IgM and calcium flux and inositol triphosphate (IP3) production were measured. Cells bearing the mutant protein demonstrated consistently a 15-20% decrease in both calcium flux and IP3 production. These findings indicate that even a modest decrease in Btk function can impair B cell proliferation or survival. However, a mutation in Btk and reduced numbers of B cells are not always associated with clinical disease.

Effect of intestinal microbiota on the induction of regulatory CD25+ CD4+ T cells.

When oral tolerance was induced in either specific pathogen-free (SPF) or germ-free (GF) mice, ovalbumin (OVA) feeding before immunization induced oral tolerance successfully in SPF mice. On the other hand, OVA-specific immunoglobulin G1 (IgG1) and IgE titres in OVA-fed GF mice were comparable to those in phosphate-buffered saline-fed GF mice, thus demonstrating that oral tolerance could not be induced in GF mice. The frequencies of CD25(+) CD4(+)/CD4(+) cells in the mesenteric lymph node (MLN) and the absolute number of CD25(+) CD4(+) cells in the Peyer's patches and MLN of naive GF mice were significantly lower than those in naive SPF mice. In an in vitro assay, the CD25(+) CD4(+) cells from the naive SPF mice suppressed more effectively the proliferation of responder cells in a dose-dependent manner than those from the GF mice. In addition, the CD25(+) CD4(+) regulatory T (T(reg)) cells from the naive SPF mice produced higher amounts of interleukin (IL)-10 and transforming growth factor (TGF)-beta than those from the GF mice. When anti-TGF-beta neutralizing antibody, but not anti-IL-10 neutralizing antibody, was added to the in vitro proliferation assay, the suppressive effect of the CD25(+) CD4(+) T(reg) cells from the SPF mice was attenuated to the same level as that of the CD25(+) CD4(+) cells from the GF mice. In conclusion, the TGF-beta-producing CD25(+) CD4(+) T(reg) cells from the MLN of SPF mice played a major role in oral tolerance induction. In addition, as the regulatory function of the CD25(+) CD4(+) cells from the naive GF mice was much lower than that of the CD25(+) CD4(+) T(reg) cells from the SPF mice, indigenous microbiota are thus considered to contribute to the induction and maintenance of CD25(+) CD4(+) T(reg) cells.

A unique, short sequence determines p53 gene basal and UV-inducible expression in normal human cells.

The p53 tumor suppressor protein plays a central role in the cellular defence against agents which cause genetic damage. The induction and activation of p53 upon stress has been shown at post-transcription level by multiple mechanisms, while the regulatory role of p53 gene transcription is still poorly understood. Here we show that the causative mechanisms underlying this activation are attributed in part to the promoter function of p53. In various normal human cells, p53 gene expression is induced transcriptionally by ultraviolet (UV) but not X-ray irradiation. We determined that, by p53 promoter dissection, the 21 bp element (PE21) responsible for this UV activation resides adjacent to, and upstream to the putative NFkappaB binding site. Moreover, the PE21 sequence was found to be a primary determinant for human p53 gene basal expression carrying bi-directional transcriptional initiation activity, which controls the initiation of RNA synthesis about 50 bases downstream, indicating that the sequence plays a critical role in both basal and inducible transcription. Finally, we detected the putative PE21 binding factor(s) in nuclear extracts from non-irradiated and irradiated cells. Since the PE21 sequence does not show any homologies to the conventional TATA or GC box, or to an 'initiatior', all of which determine the initiation site for transcription, the PE21 sequence appears to be a new class in eukaryotic promoter elements. Our results indicate that the mechanism of PE21-directed p53 mRNA transcription has an important role in the cellular stress response as well as tumor suppression.

NK cell colony formation from human fetal thymocytes.

We established a clonal cell culture system for human natural killer (NK) cells from fetal thymocytes. Thymocytes of 16 to 22 gestational weeks were cultured in methylcellulose in the presence of interleukin (IL)-7, IL-15, and steel factor (SF). After 14 days in incubation, large, diffuse colonies consisting of small cells were identified. Cells in the colonies were medium- to large-sized granular lymphocytes, expressing CD56 but not CD3, and revealed lytic activity against K562 cells. Colony-forming units (CFU)-NK were enriched in lineage negative (Lin- ) CD34++ subpopulations of fetal thymocytes, whereas a smaller number of CFU-NK also existed in Lin-CD34+ and Lin-CD34- subpopulations. Cytokine requirement for the NK cell colony formation was examined under serum-free conditions. As a single agent, only IL-15, but not IL-2, IL-7, or SF, supported NK cell colony formation. IL-15 had synergy with IL-7 and SF independently, and the maximal number of colonies were obtained when the three cytokines were present. IL-2 also supported NK cell colony formation in the presence of SF. When IL-2 was added to cultures containing IL-15 alone, IL-15 plus SF, or IL-15, SF, and IL-7, the numbers of NK cell colonies were reduced relative to those without IL-2. These results indicate that IL-2 may regulate IL-15-responsive NK cell progenitors. This clonal culture system will be a useful tool in the investigation of NK cell ontogeny.

Termination by early deletion of V beta 8 + T cells of aged mice in response to staphylococcal enterotoxin B.

The changes in the T cell repertoire of aging BALB/c mice include an increase of V beta 8 + T cells, most of which have a relatively low density of T cell receptors (TCR). We investigated the response of V beta 8 + T cells to staphylococcal enterotoxin B (SEB), a superantigen from a common bacterium, the anamnestic response to which is thought usually to be part of the defense against infection. The injection of an amount of SEB optimum for V beta 8 + T cell proliferation in young mice induced little or no proliferative response in aged mice, and within one or two days they died in shock with apoptotic cells in the spleen, a sign of T cell-shock caused by SEB. Flowcytometry analysis (FCA) 15 h after SEB injection, when cell division had not yet started, revealed the loss of 90% of V beta 8 + T cells in the blood and of 50% in the spleen in mice of all ages tested. However, conspicuous in the remaining V beta 8 + T cells in the spleens of the young mice but not in those of the aged mice, was an increased cellular complexity, as shown by the fact that light was strongly side scattered in FCA, indicating intracellular re-organization. The remaining T cells in the young could include progenitors for the expanding population of V beta 8 + T cells. As seen in lethal shock, V beta 8 + T cells in the aged are not unresponsive to SEB in vitro. They responded to the antigen by increasing the amount of TCR up to the level of that in young mice, but without proliferation. The proliferation arrest of V beta 8 + T cells of aged mice was found to be an intrinsic defect in in vitro cell mixture experiments, in which they were cocultured with young spleen cells which provided a complete immune microenvironment. It was simultaneously found in vitro that most of the V beta 8 + T cells from aged mice disappeared after antigen stimulation and that their disappearance was prevented by the presence of spleen cells from young mice, although they still did not proliferate. Taken all together the findings suggest that V beta 8+ T cells in the aged are at the end state of maturation and terminate by apoptotic death, causing T-cell shock in response to SEB.

Restraint stress elevates the plasma interleukin-6 levels in germ-free mice.

Several recent reports demonstrated that restraint stress elevates plasma IL-6 levels; however, the precise mechanism whereby stress stimuli trigger the production of IL-6 remains to be clarified. In this study, in order to elucidate whether or not the intestinal microflora contribute to the stress-induced IL-6 elevation, the plasma IL-6 response of germ-free (GF) mice, which are indeed devoid of indigenous microflora, was compared to that of specific pathogen-free (SPF) mice. The plasma IL-6 level increased after 1 h of restraint stress and thereafter gradually decreased in GF mice as well as in SPF mice. In addition, such a stress-induced IL-6 elevation was also found in the mice reconstituted with SPF feces. The expression levels of IL-6 mRNA in the liver increased after 1 h of stress in both GF and SPF mice based on the findings of a semiquantitative RT-PCR method, although no such increase was observed in the spleen and kidney of both groups of mice. These results thus indicate that restraint stress is capable of elevating the plasma IL-6 levels independently of the intestinal microflora and the liver is one of the main sources responsible for the increased plasma IL-6 during stress.

The failure of oral tolerance induction is functionally coupled to the absence of T cells in Peyer's patches under germfree conditions.

Although intestinal bacterial flora has been thought to play a role in the induction of oral tolerance, the mechanism has yet to be elucidated. We therefore examined the bacterial flora-dependent acquisition of susceptibility to oral tolerance induction using a gnotobiotic murine model. Germ-free (GF) mice exhibited a significant shortage of T cells in the PPs in comparison to SPF mice. A recovery in the number of such T cells was accomplished in the gnotobiotic mice associated with Bifidobacterium infantis or Escherichia coli but not in the gnotobiotic mice with Clostridium perfringens or Staphylococcus aureus. To examine the susceptibility to oral tolerance induction, these mice were orally given ovalbumin (OVA) as a tolerogen and then injected i.p. with the Ag. The Ag-specific IgG1 in the serum remained at a low level in both SPF and those gnotobiotic mice groups containing a sufficient number of T cells in the PPs. However, no such unresponsiveness in the Ab response was observed in GF or the other gnotobiotic mice groups containing only a few T cells in the tissues. Adoptive cell transfer analysis clearly showed that a sufficient number of T cells in the PPs is required for the induction of oral tolerance. Furthermore, the reduced expression of SLC (secondary lymphoid-tissue chemokine), which is responsible for T-cell migration to lymphoid organs, was observed in the PPs of GF mice, resulting in a shortage of T cells in the tissues. However, the reduced expression of SLC was restored even in the GF mice after conventionalization, thus suggesting that the failure of oral tolerance induction is functionally coupled to the innate absence of T cells under the GF condition.

The effect of sofalcone on indomethacin-induced gastric ulcers in a Helicobacter pylori-infected gnotobiotic murine model.

BACKGROUND: Sofalcone has been reported to exert anti-ulcer and gastroprotective actions, but its exact mechanism of action remains unknown. In our laboratory, we found that indomethacin-induced gastric ulcers become worse when associated with Helicobacter pylori infection. METHODS: We employed the H. pylori-infected gnotobiotic murine model to examine the effect of sofalcone on indomethacin-induced gastric ulcers in the presence of H. pylori infection. In vitro experiments were also done to evaluate the effects of sofalcone on H. pylori growth, adherence of H. pylori to the MKN45 cells (a human gastric epithelial cell line), and these cells' IL-8 production in the presence of H. pylori. RESULTS: We found that sofalcone produced a significant improvement in ulcer size as well as a substantial reduction in the number of H. pylori colonies in H. pylori-infected gnotobiotic mice. In vitro sofalcone has a significant bacteriocidal effect against H. pylori and can also significantly prevent adherence of this bacterium to MKN45 cells, thus remarkably reducing IL-8 production of these cells in response to stimulation by H. pylori. CONCLUSION: Our results suggest that sofalcone can improve ulcer healing by the mechanisms mentioned above.

A new anti-MRSA antibiotic complex, WAP-8294A. I. Taxonomy, isolation and biological activities.

WAP-8294A, produced by Lysobacter sp., is a complex consisting of water soluble depsipeptide antibiotics. It was further purified by column chromatographies and HPLC, and 19 components were obtained. WAP-8294A2, a major component, and minor components A1, A4, Ax8, Ax9 and Ax13 were active against gram-positive bacteria, in particular, methicillin-resistant Staphylococcus aureus (MRSA) in vitro. WAP-8294A2 was highly active in vivo in mice against the systemic infection of MRSA.

Production of recombinant human midkine in yeast, Pichia pastoris.

Recombinant human midkine was expressed in the cells of Pichia pastoris under the control of the AOX1 gene promoter. The expression of midkine was efficiently induced by methanol in a high cell density fermentation. Approximately 0.3 g/l culture of midkine accumulated in the cells by 72 h after induction. When the cells were disrupted, midkine was recovered in an insoluble form, and was insoluble even in the presence of 7 M urea. The precipitate was dissolved in the buffer solution (pH 8) containing 8 M guanidine hydrochloride, 10 mM dithiothreitol, 1 mM EDTA and 50 mM Tris-Cl, and then, midkine was renatured by dialysis at high concentration against the buffer solution (pH 8) containing 0.5 M sodium chloride and 20 mM Tris-Cl. The renatured midkine was recovered using a SP-Sepharose column, and purified further by Heparin-Sepharose column chromatography. Approximately 64 mg/l culture of the purified midkine was obtained. The amino acid sequence of amino-terminus and the amino acid composition of midkine were the same as those of Met-midkine that has a methionine residue at the amino-teminus. Mass spectrometry of purified Met-midkine showed a mass of 13370.7 Da (average), almost the theoretical mass for it. The Met-midkine enhanced the proliferation of Chinese hamster ovary (CHO) cells.

Application of loop diuretics for treatment of sensorineural hearing impairment. Experimental and clinical study.

In a series of animal experiments on guinea pigs and rats, conducted in an attempt to find a better solution for the treatment of sensorineural hearing impairment and tinnitus-known as diseases almost impossible to heal-it was revealed electrophysiologically, biochemically and electronmicroscopically that loop diuretics, referred to as ototoxic drugs, cause an increased amount of the therapeutic preparation to transfer to the inner ear fluid. It is concluded, on the basis of the encouraging results of these experiments, that combined medication with metabolic activator, steroid hormone and loop diuretics is significantly more effective in improving the symptoms of patients with inner ear deafness and tinnitus.

A questionnaire survey on the use of dust respirators among lead workers in small scale companies.

In order to find out whether dust respirators are properly used among lead workers in small scale manufacturing companies of lead pigments and stabilizers, a questionnaire survey was carried out for 141 lead workers. The questionnaire consisting of 7 items of questions including selection, use, maintenance, storage and instruction of respirators was distributed to all 141 workers. This survey revealed that 22% of the total workers wore unauthorized dust respirators, and that 73% used a knitcover. Instruction by health supervisors of how to use and where to store the respirators was found to be effective for inspection of valve and a proper place to store dust respirator. However, the result that significantly large percentage of workers used the knitcover following the health supervisors' instruction can be taken to indicate that health supervisors should be given more precise information on deteriorated face-sealing of the respirator facepiece with the knitcover.

A study on the effects of countermeasures for vibrating tool workers using an impact wrench.

The aims of this study were (1) to measure frequency-weighted vibration acceleration and (2) to study the effects of introducing a vibration-proof impact wrench on VWF in workers. The subject pool was 383 male workers who were regularly using an impact wrench and taking special medical examinations for vibration syndrome in a factory from 1982 to 1999. The prevalence of workers with VWF increased gradually after 1982, reached a peak value (4.8%) in 1986, gradually decreased after 1987, and disappeared in 1994. Sixteen subjects who had had VWF at least one time during the observation period were selected for this study. The stages of VWF were at stage I on the Stockholm Workshop scale in all subjects. After the vibration-proof impact wrench was introduced in 1986, the vibration acceleration of the impact wrench measured on the handle decreased from 8.6-11.1 m/s2 to 5.1-7.1 m/s2. The actual time per day that subjects were assumed to use the impact wrench was 108 minutes. The subjects actually used an impact wrench more than the occupational exposure limit allowed. However, VWF disappeared after the introduction of a vibration-proof impact wrench. This might have resulted from the combined effect of introducing the vibration-proof impact wrench and certain countermeasures that were taken against cold working environments.

Peripheral hemodynamics evaluated by acceleration plethysmography in workers exposed to lead.

To clarify the effect of lead exposure on peripheral hemodynamics, acceleration plethysmography (APG) was performed for 48 male subjects occupationally exposed to lead (exposure group) and 43 male subjects with no history of occupational exposure to lead (control group). In the exposure group, the blood lead concentration (Pb-B) was also measured. Each APG parameter was assessed by comparing measured data with the standard aging curves. A significant negative correlation was obtained between the parameter--b/a and Pb-B. The exposure group showed significantly lower values of parameters--b/a (p < 0.01) and d/a (p < 0.05) than the control group. The parameter--b/a in the exposure group dose-dependently decreased with increases in length of working career (duration of exposure to lead) and Pb-B. The parameter--b/a significantly (p < 0.05) decreased in subjects with working careers of 5 years or more and in subjects whose Pb-B was 40 micrograms/100 ml or more. These results suggest that lead exposure affects peripheral hemodynamics as evaluated by APG.

Ecological mechanism of protection of intestinal bacterial flora against Salmonella typhimurium infection.

Our results indicate that the responsiveness of the phagocytic and intracellular killing process of peripheral blood granulocytes and peritoneal phagocytic cells in infected germfree mice is due primarily to the OCl- (hypochloride ion) with myeloperoxidase involvement, while the response in infected conventional mice is brought about mainly by the O2- (superoxide anion). These facts are believed to be invaluable footholds in elucidating the quantitative and qualitative differences in phagocytic cell response depending upon the presence or absence of intestinal flora.

Selection of hypotoxigenic Vibrio cholerae population by human intestinal bacteria in gnotobiotic mice.

Strains of human intestinal bacteria when cultured with Vibrio cholerae 569B, classical Inaba, exerted either inhibitory or promotive effects on cholera toxin production. An inhibitory strain of Bacteroides fragilis was orally given to germfree mice a week before vibrio administration. In vibrio-monoassociated mice, the toxin production of most vibrios isolated from feces was as high as the inocula, while in Bacteroides-vibrio-diassociated mice toxin production decreased starting on day 3 after vibrio administration and vibrios with 1/250 to 1/1,000 of the toxin production levels of the inocula dominated 1 and 2 wk after administration. The number of vibrios remained basically unchanged in vibrio-monoassociated mice, but was kept low in Bacteroides-vibrio-diassociated mice throughout the experimental period of 4 wk. Fecal concentration of succinic acid was higher in Bacteroides-associated mice than in vibrio-monoassociated mice. An isolate from a vibrio-monoassociated mouse yielded poorer colony formation on a heart infusion agar plate containing 6.25 mM succinic acid than a vibrio from a Bacteroides-vibrio-diassociated mouse. Isolates from agar plates containing succinic acid showed low cholera toxin productivity. Thus, the presence of the Bacteroides in gnotobiotic mice may have resulted in the selection of a less toxigenic vibrio population, and succinic acid produced in abundance in Bacteroides-associated mice may be one of the selecting factors.

Intestinal bacterial flora and host defense mechanisms.

The protective mechanisms of intestinal bacterial flora against exogenous infections will be discussed in this paper. Experimental data on protective function of Escherichia coli, Enterococcus faecalis and Bacteroides distasonis comprising intestinal flora against oral infection of Shigella flexneri which causes localized infection are presented. Furthermore, the present investigation deals with non-specific defense mechanism which indicate that protective activity of intestinal flora against parenteral infection of Salmonella typhimurium mainly depend upon the larger number of functional kupffer cells in conventional mice than in that of their germfree counterparts.