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Biomedical subjects

K Yamaguchi

Publications and source records attributed to K Yamaguchi.

At least 91 records · Page 5Linked to original sources
PubMed2001

Lipoolygosaccharide indirectly enhances inflammatory lesions in lungs as a primary infection site by non-encapsulated and type B Haemophilus influenzae through production of cytokines.

We investigated the role of cytokines in differences in histopathologic changes in the lung between bronchopneumonia caused by non-encapsulated Haemophilus influenzae strain 770235f(0)b(0)and systemic disease caused by type b H. influenzae strain 770235f(0)b(+). Tumour necrosis factor-alpha (TNF-alpha), interleukin-(IL)-6 and IL-1 beta levels in bronchoalveolar lavage fluid (BALF) samples of mice infected with strain 770235f(0)b(0)were higher than in those infected with strain 770235f(0)b(+)until 24 h post-infection. Serum IL-6 rapidly increased in strain 770235f(0)b(0)infection after 72 h post-infection. Serum TNF-alpha level in strain 770235f(0)b(0)infection appeared earlier than in strain 770235f(0)b(+)infection. IL-1 beta production in strain 770235f(0)b(+)infection was later than in strain 770235f(0)b(0)infection. Moreover, a biphasic concentration pattern of TNF-alpha and IL-6 was noted in BALF of mice with strain 770235f(0)b(0)infection.

Animals↗
PubMed2001

Luminescent FeSi(2) crystal structures induced by heteroepitaxial stress on Si(111).

The crystal structures and the luminescent properties of FeSi(2) in the FeSi(2)/Si heteroepitaxial system have been investigated by first principles calculations. The results indicate that the heteroepitaxial beta-FeSi(2) facing Si(111) by the (110) plane will be deformed from an orthorhombic to a monoclinic P2(1)/c structure with a gamma angle of 95 degrees. The strained crystal has a direct gap band structure and a finite oscillator strength of 0.7 between the band edges at the Y point. Since an indirect type band structure is obtained for other heteroepitaxial relationships, as well as for the bulk beta-FeSi(2), we propose the strained FeSi(2)(110)/Si(111) structure to be the origin of the luminescence observed in the FeSi(2)/Si systems.

Journal Article↗
PubMed2001

Overexpression of lysosomal-type sialidase leads to suppression of metastasis associated with reversion of malignant phenotype in murine B16 melanoma cells.

Increased sialylation in cell surface glycoproteins is one characteristic feature of cancer cells, particularly related to their metastatic potential and invasiveness. Expression of lysosomal-type sialidase, which plays a major role in hydrolysis of such sialo-glycoproteins, is therefore considered to have a great influence on malignant properties of cancer cells. To investigate whether the sialidase expression level is linked to the malignant phenotype, we transfected B16-BL6 murine melanoma cells, a highly invasive and metastatic line, with an expression vector harboring a rat lysosomal sialidase cDNA; then clones were isolated and examined for changes in biological character. Sialidase-overexpressing cells showed suppression of experimental pulmonary metastasis and tumor progression. The transfectants exhibited diminished cell growth, anchorage-independent growth and increased sensitivity to apoptosis induced by suspension culture or serum depletion in vitro, but no significant alterations in invasiveness, cell motility and cell attachment to fibronectin, collagen IV and laminin. Flow cytometric analysis with either peanut agglutinin (PNA) or Ricinus communis agglutinin (RCA) lectin revealed that desialylated forms of glycoproteins on the cell surfaces were increased. In particular, a desialylated form of a cell surface glycoprotein of 83 kDa was prominent in the transfectants, as determined by galactose oxidase labeling. These observations indicate that sialidase expression is inversely associated with metastatic potential and tumor growth in cancer cells, probably through a regulation mechanism that suppresses cell growth and anchorage-independent growth and promotes apoptosis with deprivation of cell anchorage.

Animals↗
PubMed2001

Constitution of Grignard reagent RMgCl in tetrahydrofuran.

The constitution of Grignard reagent, RMgCl (R = Me, tBu, Ph or benzyl), was investigated in the solid state by means of X-ray crystallography and in THF by coldspray ionization mass spectrometry (CSI-MS). Three types of crystal structures, (a) [Mg2(mu-Cl3)(THF)6](+)*[RMgCl2(THF)](-), (b) R2Mg4Cl6(THF)6, and (c) [2Mg2(mu-Cl3)(THF)6](+)*[R4Mg2Cl2]2-, were identified, and MeMg2(mu-Cl3)(THF)4-6 were detected as major species of MeMgCl in solution.

Journal Article↗
PubMed2001

Increased expression of P-cadherin mRNA in the mouse peritoneum after carbon dioxide insufflation.

BACKGROUND: Although systemic responses to carbon dioxide (CO(2)) pneumoperitoneum have been studied, there have been few reports of local responses within the peritoneum. We investigated the expression of mRNA for adhesion molecules involved in cell-cell interactions, including ICAM-1, VCAM-1, CD44, E-cadherin, P-cadherin, and N-cadherin, after the induction of a CO(2) pneumoperitoneum in mice. METHODS: Mice were treated with CO(2) pneumoperitoneum (4-6 mmHg for 30 min) and then killed after 24 h, 48 h, and 72 h. The peritoneum of the abdominal wall was resected, and total RNA was extracted by the acid guanidinium thiocyanate-phenol-chloroform extraction procedure, cDNA were synthesized by reverse transcription. Expression of the mRNA for each gene was normalized to that of b-actin for semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The expression of P-cadherin mRNA was significantly increased at 48 h (p = 0.007) and returned to the control level by 72 h after CO(2) pneumoperitoneum. The expression of CD44 increased gradually, reaching a peak at 48 h and returning to the control value by 72 h after CO(2) pneumoperitoneum. Expression of ICAM-1 mRNA was not changed significantly after the application of CO(2). CONCLUSION: The expression of P-cadherin mRNA in the peritoneum can be induced to repair injuries to mesothelial cells caused by CO(2) pneumoperitoneum.

Actins↗
PubMed2001

Characterization of encapsulating supramolecules by using CSI-MS with ionization-promoting reagents.

Guanidine nitrate, DMF, DMA, and DMSO are proven to be efficient ionization-promoting reagents in coldspray ionization mass spectrometry (CSI-MS) for the self-assembled cage Pt compound 1 in aqueous solution. These reagents made it possible to characterize the structures of encapsulated guest molecules in the cage. Detailed structure determinations of the cage compound encapsulating various kinds of guest molecules by using positive CSI-MS with ionization-promoting reagents are described.

Journal Article↗
PubMed2001

A self-assembled homooxacalix[3]arene-based dimeric capsule constructed by a Pd(II)-pyridine interaction which shows a novel chiral twisting motion in response to guest inclusion.

A capsule-like molecule was constructed by dimerization of pyridine-containing homooxacalix[3]aryl esters utilizing a Pd(II)-pyridine interaction when Li(+) ions were bound to the ionophoric lower rims. (1)H NMR spectral studies showed that the self-assembled molecular capsule 3b.(Li(+))(2) has a highly symmetrical D(3)(h)-structure. It was also found that this self-assembled molecular system can form capsular structures in the presence of Na(+) or ammonium (RNH(3)(+)) ions. Very interestingly, these molecular capsules are twisted into triply bridged helical structures, and chiral RNH(3)(+) guests included in the cavity induce a change in the (P) versus (M) ratio, resulting in high chiral induction ( approximately 70%). These results indicate that the self-assembled molecular capsule 3b has a novel chiral factor in which the (P) versus (M) equilibrium is readily controllable by the inclusion of chiral guest molecules.

Journal Article↗
PubMed2001

T-cell lines from 2 patients with adenosine deaminase (ADA) deficiency showed the restoration of ADA activity resulted from the reversion of an inherited mutation.

Inherited deficiency of adenosine deaminase (ADA) results in one of the autosomal recessive forms of severe combined immunodeficiency. This report discusses 2 patients with ADA deficiency from different families, in whom a possible reverse mutation had occurred. The novel mutations were identified in the ADA gene from the patients, and both their parents were revealed to be carriers. Unexpectedly, established patient T-cell lines, not B-cell lines, showed half-normal levels of ADA enzyme activity. Reevaluation of the mutations in these T-cell lines indicated that one of the inherited ADA gene mutations was reverted in both patients. At least one of the patients seemed to possess the revertant cells in vivo; however, the mutant cells might have overcome the revertant after receiving ADA enzyme replacement therapy. These findings may have significant implications regarding the prospects for stem cell gene therapy for ADA deficiency.

Adenosine Deaminase↗
PubMed2001

Menin, a gene product responsible for multiple endocrine neoplasia type 1, interacts with the putative tumor metastasis suppressor nm23.

Although the gene responsible for multiple endocrine neoplasia type 1 (MEN1) has been identified, the function of its gene product, menin, is unknown. To examine the biological role of the MEN1 gene, we searched for associated proteins with a yeast two-hybrid system using the MEN1 cDNA fragment as bait. On screening a rat fetal brain embryonic day 17 library, in which a high level of MEN1 expression was detected, we identified a putative tumor metastasis suppressor nm23/nucleoside diphosphate (NDP) kinase as an associated protein. This finding was confirmed by in vitro interaction assays based on glutathione S-transferase pull down experiments. The association required almost the entire menin protein, and several missense MEN1 mutations reported in MEN1 patients caused a loss of the binding activity for nm23. This result suggests that this interaction may play important roles in the biological functions of the menin protein, including tumor suppressor activity.

Animals↗
PubMed2001

Spontaneous in vivo reversion of an inherited mutation in the Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency disease, arising from mutations of the WAS-protein (WASP) gene. Previously, we have reported that mononuclear cells from WAS patients showed lack/reduced of the intracellular WASP (WASP(dim)) by flow cytometric analysis, and analysis of WASP by flow cytometry (FCM-WASP) was useful for WAS diagnosis. In this study, we report a WAS patient who showed the unique pattern of FCM-WASP. The patient had the small population of normal expression of WASP (WASP(bright)) mononuclear cells together with the major WASP(dim) population. The WASP(bright) cells were detected in T cells, not in B cells or in monocytes. Surprisingly, the molecular studies of the WASP(bright) cells revealed that the inherited mutation of WASP gene was reversed to normal. His mother was proved as a WAS carrier, and HLA studies and microsatellite polymorphic studies proved that the WASP(bright) cells were derived from the patient himself. Therefore, we concluded that the WASP(bright) cells were resulted from spontaneous in vivo reversion of the inherited mutation. Furthermore, the scanning electron microscopic studies indicated that WASP-positive cells from the patient restored the dense microvillus surface projections that were hardly observed in the WASP(dim) cells. This case might have significant implications regarding the prospects of the future gene therapy for WAS patients.

Adult↗
PubMed2001

Nociceptive stimulation increases NO synthase mRNA and vasopressin heteronuclearRNA in the rat paraventricular nucleus.

Nociceptive stimulation causes neuroendocrine responses such as arginine vasopressin (AVP) release and activation of the hypothalamo-pituitary-adrenal (HPA) axis. We examined the effects of nociceptive stimulation on the expression levels of neuronal nitric oxide synthase (nNOS) mRNA, heteronuclear (hn)RNA for AVP and AVP mRNA in the rat paraventricular nucleus (PVN) and supraoptic nucleus (SON), using in situ hybridization histochemistry. For nociceptive stimulation, formalin (5%) or saline was injected subcutaneously (s.c.) into the bilateral hind paws of rats. The expression of the nNOS gene in the PVN was significantly increased 2 and 6 h after s.c. injection of formalin in comparison with that in untreated and saline injected rats. The expression of the nNOS gene in the SON did not change in the untreated, saline- and formalin-injected rats. The AVP hnRNA in the PVN and SON was also significantly increased 15, 30 min and 2 h after s.c. injection of formalin, though AVP mRNA did not change at any time points that we studied. Plasma concentration of AVP was significantly increased 15 min after s.c. injection of formalin. These results suggest that NO in the PVN may be involved in nociceptive stimulation-induced neuroendocrine responses.

Animals↗
PubMed2001

Creation of novel chiral cryptophanes by a self-assembling method utilizing a pyridyl-Pd(II) interaction.

[structure: see text]. This Letter demonstrates the molecular design of novel self-assembled chiral cryptophanes. Mediated by square-planar Pd(II) complexes, racemic pyridyl cyclotriveratrylene derivative rac-2 self-assembles into mixtures of racemic chiral cryptophanes and meso cryptophanes (1), which interconvert with each other, and the rates are remarkably enhanced by the addition of a slight excess of rac-2. On the other hand, optically resolved P-2 or M-2 self-assembles into the chiral cryptophane as the only product.

Journal Article↗
PubMed2001

Laparoscopically assisted resection of choledochal cyst and Roux-en-Y reconstruction.

UNLABELLED: Laparoscopic surgery for a congenital choledochal cyst was accomplished in five of eight adult patients for whom it was attempted (63%). Creation of a Roux-en-Y jejunal limb by midline minilaparotomy and hepaticojejunostomy using a laparoscopic sewing instrument facilitated the procedure. BACKGROUND: Congenital choledochal cyst is a good indication for laparoscopic surgery. However, only two case reports are available at this writing. METHODS: Eight adult patients, ages 19 to 61 years (mean, 32.6 years), underwent laparoscopically assisted resection of the choledochal cyst and Roux-en-Y hepaticojejunostomy. RESULTS: The whole procedure was accomplished in five patients (63%). The duration of the procedure ranged from 525 to 680 min (average, 616 min). Open conversion in three patients was necessitated by severance of a small common hepatic duct because of disorientation caused by previous laparoscopic cholecystectomy, electrocautery injury to the common channel distal to the anomalous pancreaticobiliary junction, or heavy adhesion around the cyst secondary to recent severe cholangitis. Creation of a Roux-en-Y jejunal limb by midline minilaparotomy and hepaticojejunostomy using a laparoscopic sewing instrument facilitated the procedure. CONCLUSIONS: Laparoscopically assisted resection of the choledochal cyst and hepaticojejunostomy are technically feasible and deserve further clinical trials.

Adult↗
PubMed2001

Catalytic asymmetric epoxidation of enones using La-BINOL-triphenylarsine oxide complex: structural determination of the asymmetric catalyst.

The catalytic asymmetric epoxidation of enones using the La-BINOL-Ph(3)As=O complex generated from La(O-i-Pr)(3), BINOL, and Ph(3)As=O in a ratio of 1:1:1 is described herein. Using 1-5 mol % of the asymmetric catalyst, a variety of enones, including a dienone and a cis-enone, were found to be epoxidized in a reasonable reaction time, providing the corresponding epoxy ketones in up to 99% yield and with more than 99% ee. The possible structure of the actual asymmetric catalyst has been clarified by various methods, including X-ray crystal structure analysis. This is the first X-ray analysis of an alkali-metal free lanthanoid-BINOL complex. Although La(binaphthoxide)(2)(Ph(3)As=O)(2) (7) was observed as the major complex in the complexes' solution, generated from La(O-i-Pr)(3), BINOL, and Ph(3)As=O in a ratio of 1:1:1, the possible active species turned out to be the La-BINOL-Ph(3)As=O complex in a ratio of 1:1:1. A probable reaction mechanism of the catalytic asymmetric epoxidation of enones is also proposed, suggesting that preferential formation of a heterochiral complex is the reason for asymmetric amplification. Moreover, the interesting role of La(O-i-Pr)(3) for accelerating the epoxidations while maintaining high ee's is discussed.

Journal Article↗
PubMed2001

Molecular basis for hematopoietic/mesenchymal interaction during initiation of Peyer's patch organogenesis.

Mice deficient in lymphotoxin beta receptor (LTbetaR) or interleukin 7 receptor alpha (IL-7Ralpha) lack Peyer's patches (PPs). Deficiency in CXC chemokine receptor 5 (CXCR5) also severely affects the development of PPs. A molecular network involving these three signaling pathways has been implicated in PP organogenesis, but it remains unclear how they are connected during this process. We have shown that PP organogenesis is initiated at sites containing IL-7Ralpha(+) lymphoid cells and vascular cell adhesion molecule (VCAM)-1/intercellular adhesion molecule (ICAM)-1 expressing nonlymphoid elements. Here we characterize these lymphoid and nonlymphoid components in terms of chemokine signals. The lymphoid population expresses CXCR5 and has a strong chemotactic response to B lymphocyte chemoattractant (BLC). Importantly, chemokines produced by VCAM-1(+)ICAM-1(+) nonlymphoid cells mediate the recruitment of lymphoid cells. Furthermore, we show that these VCAM-1(+)ICAM-1(+) cells are mesenchymal cells that are activated by lymphoid cells through the LTbetaR to express adhesion molecules and chemokines. Thus, promotion of PP development relies on mutual interaction between mesenchymal and lymphoid cells.

Animals↗
PubMed2001

Early recruitment of neutrophils determines subsequent T1/T2 host responses in a murine model of Legionella pneumophila pneumonia.

The contribution of neutrophils to lethal sensitivity and cytokine balance governing T1 and T2 host responses was assessed in a murine model of Legionella pneumophila pneumonia. Neutrophil depletion by administration of granulocyte-specific mAb RB6-8C5 at 1 day before infection rendered mice approximately 100-fold more susceptible to lethal pneumonia induced by L. pneumophila. However, this treatment did not alter early bacterial clearance, despite a substantial decrease in neutrophil influx at this time point. Cytokine profiles in the lungs of control mice demonstrated strong T1 responses, characterized by an increase of IFN-gamma and IL-12. In contrast, neutrophil-depleted mice exhibited significantly lower levels of IFN-gamma and IL-12, and elevation of T2 cytokines, IL-4 and IL-10. Immunohistochemistry of bronchoalveolar lavage cells demonstrated the presence of IL-12 in neutrophils, but not alveolar macrophages. Moreover, IL-12 was detected in lavage cell lysates by ELISA, which was paralleled to neutrophil number. However, intratracheal administration of recombinant murine IL-12 did not restore resistance, whereas reconstitution of IFN-gamma drastically improved bacterial clearance and survival in neutrophil-depleted mice. Taken together, these data demonstrated that neutrophils play crucial roles in primary L. pneumophila infection, not via direct killing but more immunomodulatory effects. Our results suggest that the early recruitment of neutrophils may contribute to T1 polarization in a murine model of L. pneumophila pneumonia.

Animals↗
PubMed2001

Sequential change of virus markers in seroconverters with community-acquired infection of human T lymphotropic virus type I.

Twenty-three human T lymphotropic virus type I (HTLV-I) seroconverters were identified among 1120 HTLV-I-seronegative adults followed up for 11 years in an area of Japan endemic for HTLV-I. The geometric mean titer of anti-HTLV-I was 1:453 in the first year after seroconversion; the titer of each subject did not change significantly during 2-10 years of follow-up. HTLV-I proviral DNA load was quantified in 15 seroconverters, and a broad range of levels was observed-from <10 to >1000 copies/10(5) peripheral blood mononuclear cells. However, there was no obvious change in HTLV-I proviral DNA load over several years within individual subjects. Therefore, both proviral DNA load and humoral response in adult HTLV-I seroconverters were shown to stabilize within a few years after initial infection. In addition, 1 subject tested positive for HTLV-I proviral DNA before antibody seroconversion, which suggests the existence of a window period in community-acquired infection.

Aged↗