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S Kawabata

Publications and source records attributed to S Kawabata.

At least 19 recordsLinked to original sources
PubMed1998

Molecular analyses of glucosyltransferase genes among strains of Streptococcus mutans.

Three glucosyltransferase (GTase) genes (gtfB, gtfC and gtfD) were cloned and sequenced from clinically isolated strains of Streptococcus mutans MT8148 (serotype c), MT4239 (c), MT4245 (e), MT4467 (e) and MT4251 (f), respectively. Comparison of the gtf genes revealed that interstrain difference of gtfB and gtfD was limited, while gtfC showed significant interstrain variations. Similar to gtfB and gtfD, gtfC possessed five direct repeats composed of homologous unit in the carboxyl-terminal portion. The repeating unit consisted of 63-65 amino acid residues and is responsible for glucan binding. The gtfC gene from S. mutans MT4245 lacked the fourth unit. Multiple alignment with the gtf sequence of strain GS-5 (c) revealed several changes in these gtf genes due to frameshift mutations. The peptides encoded by the gtfB, gtfC and gtfD genes of GS-5 were 1, 80, and 32 amino acid residues shorter than those of the test strains except strain MT4245.

Bacterial Proteins↗
PubMed1998

Two hevein homologs isolated from the seed of Pharbitis nil L. exhibit potent antifungal activity.

Two antifungal peptides (Pn-AMP1 and Pn-AMP2) have been purified to homogeneity from seeds of Pharbitis nil. The amino acid sequences of Pn-AMP1 (41 amino acid0 residues) and Pn-AMP2 (40 amino acid residues) were identical except that Pn-AMP1 has an additional serine residue at the carboxyl-terminus. The molecular masses of Pn-AMP1 and Pn-AMP2 were confirmed as 4299.7 and 4213.2 Da, respectively. Both the Pn-AMPs were highly basic (pI 12.02) and had characteristics of cysteine/glycine rich chitin-binding domain. Pn-AMPs exhibited potent antifungal activity against both chitin-containing and non-chitin-containing fungi in the cell wall. Concentrations required for 50% inhibition of fungal growth were ranged from 3 to 26 micrograms/ml for Pn-AMP1 and from 0.6 to 75 micrograms/ml for Pn-AMP2. The Pn-AMPs penetrated very rapidly into fungal hyphae and localized at septum and hyphal tips of fungi, which caused burst of hyphal tips. Burst of hyphae resulted in disruption of the fungal membrane and leakage of the cytoplasmic materials. To our knowledge, Pn-AMPs are the first hevein-like proteins that show similar fungicidal effects as thionins do.

Amino Acid Sequence↗
PubMed1998

Targeted lymph-node immunization with whole inactivated simian immunodeficiency virus (SIV) or envelope and core subunit antigen vaccines does not reliably protect rhesus macaques from vaginal challenge with SIVmac251.

OBJECTIVE: Sexual transmission of HIV is the most common route of HIV transmission throughout the world. To prevent sexually transmitted HIV infection, a vaccine is urgently needed. A previous report demonstrated the targeted immunization of the iliac lymph nodes with simian immunodeficiency virus (SIV) subunits protects rhesus macaques from rectal challenge with SIV. We sought to determine whether this immunization strategy could protect rhesus macaques from vaginal challenge with SIV. DESIGN: Macaques were immunized with either whole-killed SIV or envelope and core subunit antigen vaccines. Using three independent groups, with three macaques in each group, macaques were immunized by the targeted iliac lymph-node (TILN) route, injecting the vaccine close to the iliac lymph nodes that drain the genital tract. RESULTS: The TILN immunization procedure induced high-titer SIV-specific immunoglobulin (Ig) G antibodies in serum in all animals and anti-SIV IgG and IgA antibodies in the cervicovaginal secretions of most animals. After a series of three or four TILN immunizations, the animals were intravaginally challenged with SIVmac251. All animals became virus isolation-positive, except one animal immunized with SIV p27 and gp120. This animal was virus isolation-negative but SIV DNA proviral sequences were detected in peripheral blood mononuclear cells. CONCLUSIONS: In this series of studies, reliable protection from vaginal transmission of SIV was not achieved by the TILN immunization procedure.

Animals↗
PubMed1998

Diagnostic potential and pitfalls of ultrasound-guided fine-needle aspiration cytology for breast lesions.

Ultrasound (US)-guided fine-needle aspiration cytology (FNAC) is now widely accepted as a diagnostic procedure for breast lesions. Along with its advantages, US-guided FNAC also has some pitfalls. The recognition of these pitfalls for this procedure is extremely important for the strict management of the disease. We retrospectively investigated the diagnostic potential and pitfalls of US-guided FNAC in the diagnosis of breast lesions. This study consisted of 348 aspirated samples from 274 breast tumors. The rate of sufficient aspirates was 74% after a single aspiration, while sufficient materials were finally obtained from 93% of the tumors by repeated aspirations. The rate was lower in tumors measuring less than 10 mm in diameter (62%), and in sclerosing adenosis (25%). The sensitivity of FNAC was 65%, the specificity was 75%, the border diagnosis rate was 18%, and the positive predictive value was 92%. The false-negative rate was higher in noninvasive carcinoma (45%). The border diagnosis rate was also higher in scirrhous carcinoma (29%). There were also five false-positive cases. Limited to nonpalpable lesions, the sufficient aspirates rate was 70% and the accuracy was 67%.

Adenocarcinoma, Scirrhous↗
PubMed1998

High mucosal levels of tumor necrosis factor alpha messenger RNA in AIDS-associated cytomegalovirus-induced esophagitis.

BACKGROUND & AIMS: To evaluate the role of tumor necrosis factor alpha (TNF-alpha), a key inflammatory cytokine, in cytomegalovirus-associated gastrointestinal disease, we quantitated the level of TNF-alpha messenger RNA (mRNA) in esophageal mucosa from patients with cytomegalovirus-associated esophagitis and acquired immunodeficiency syndrome. METHODS: Four patients underwent endoscopic biopsy of their cytomegalovirus-associated esophageal ulcers before and after ganciclovir therapy. The level of TNF-alpha mRNA in coded esophageal specimens was assessed by in situ hybridization, reverse-transcription polymerase chain reaction, and quantitative polymerase chain reaction. RESULTS: Esophageal mucosa from 3 patients whose ulcers healed or markedly improved contained before therapy numerous macrophages expressing TNF-alpha mRNA and high tissue levels of TNF-alpha mRNA that decreased substantially or were not detectable after therapy. In contrast, esophageal specimens from the single patient whose ulcer worsened after therapy contained many mucosal macrophages expressing TNF-alpha mRNA before as well as after therapy, and the high number of molecules of TNF-alpha mRNA present in the tissue before therapy increased further after treatment. CONCLUSIONS: Increased macrophage production and high tissue levels of TNF-alpha mRNA are associated with cytomegalovirus-associated esophageal ulcers and probably contribute to the inflammatory response associated with cytomegalovirus-induced gastrointestinal disease.

AIDS-Related Opportunistic Infections↗
PubMed1998

Peptide mimics of the CTLA4-binding domain stimulate T-cell proliferation.

Phage library clones selected by a conformational epitope-recognizing and inhibitory monoclonal antibody may display moieties that mimic a receptor/ligand-like three-dimensional structure. This pseudoreceptor/ligand should be able to bind to natural ligand/receptor molecules. We tested this idea using anti-T cell costimulatory molecule antibodies and successfully isolated phage clones with costimulatory effects on T-cell proliferation. This strategy facilitates the designing of regulatory peptide molecules in the absence of precise information about the structure-function relationships in receptor/ligand interactions.

Abatacept↗
PubMed1998

Induction of Th2 cytokine expression for p27-specific IgA B cell responses after targeted lymph node immunization with simian immunodeficiency virus antigens in rhesus macaques.

To determine if there is an association between the isotype of simian immunodeficiency virus (SIV)-specific B cell responses and the profile of Th1 and Th2 cytokine expression, rhesus macaques were immunized with SIV antigens via the iliac lymph nodes, using a targeted lymph node (TLN) immunization procedure. When CD4+ T cells purified from antigen-stimulated peripheral blood mononuclear cells were analyzed, the levels of Th2 cytokine production were gradually increased after the second and third immunizations. However, interferon-gamma production did not change. Analysis of SIV-specific B cell responses revealed that the main isotype was IgG after the second and third immunizations. In addition, a peak of SIV-specific IgA B cell responses was noted following the third immunization. These findings suggest that the induction of Th2 type responses in TLN-immunized rhesus macaques reflects the sequence of initial induction of SIV-specific IgG-producing cells followed by IgA-secreting cells.

Animals↗
PubMed1998

New types of clotting factors and defense molecules found in horseshoe crab hemolymph: their structures and functions.

Invertebrate animals, which lack adaptive immune systems, have developed defense systems, so-called innate immunity, that respond to common antigens on the surface of potential pathogens. One such defense system is involved in the cellular responses of horseshoe crab hemocytes to invaders. Hemocytes contain two types, large (L) and small (S), of secretory granules, and the contents of these granules are released in response to invading microbes via exocytosis. Recent biochemical and immunological studies on the granular components of L- and S-granules demonstrated that the two types of granules selectively store granule-specific proteins participating in the host defense systems. L-Granules contain all the clotting factors essential for hemolymph coagulation, protease inhibitors including serpins and cystatin, and anti-lipopolysaccharide (LPS) factor and several tachylectins with LPS binding and bacterial agglutinating activities. On the other hand, S-granules contain various new cysteine-rich basic proteins with antimicrobial or bacterial agglutinating activities, such as tachyplesins, big defensin, tachycitin, and tachystatins. The co-localization of these proteins in the granules and their release into the hemolymph suggest that they serve synergistically to construct an effective host defense system against invaders. Here, the structures and functions of these new types of defense molecules found in the Japanese horseshoe crab (Tachypleus tridentatus) are reviewed.

Animals↗
PubMed1998

[A case of unresectable advanced gastric cancer with severe obstructive jaundice responding to combined chemotherapy with 5-fluorouracil and low-dose cisplatin].

A 69-year-old male patient with gastric cancer complaining severe jaundice was readmitted for the purpose of chemotherapy. The primary tumor was unresectable, and his jaundice was gradually increasing because of the growth of tumor, so the patient was treated by combined chemotherapy with 5-fluorouracil and low-dose cisplatin for 2 courses (1 course = 4 weeks), which resulted in remarkable reduction of jaundice without any severe side effects. So, the patient could be discharged and spend a useful life for about 10 months with good quality of life. This therapy might be a useful palliative chemotherapy for cases of this kind.

Aged↗
PubMed1997

A novel alkaline phosphatase-based isolation method allows characterization of intraepithelial lymphocytes from villi tip and crypt regions of murine small intestine.

The isolation of intestinal intraepithelial lymphocytes (IEL) is a major prerequisite for the investigation of cellular and molecular cross-talk in the intestinal mucosa. Since intestinal epithelial cells exhibit distinct functional features at the villi tip and crypt levels, such differences could extend to IEL. We developed a mechanical procedure for isolation of IEL from these distinct epithelial sites to test our hypothesis. Cells isolated from the intestinal epithelium by sequential incubations under stirring were segregated based upon their alkaline phosphatase (AP) activity since villi tip and crypt fractions expressed high and low AP activity, respectively. IEL preparations obtained after a further purification step in Percoll gradient contained > 90% Integrin alpha IEL chain+, CD3+ T cells, and no Ig+ cells. Villi tip IEL preparations possessed increased numbers of low density IEL when compared to crypt IEL, suggesting that distinct IEL-epithelial cell interactions occur at the intestinal villi tip and crypt levels.

Alkaline Phosphatase↗
PubMed1997

A newly identified horseshoe crab lectin with binding specificity to O-antigen of bacterial lipopolysaccharides.

We identified a novel horseshoe crab hemocyte-derived lectin, which we named tachylectin-4. It has more potent hemagglutinating activity against human A-type erythrocytes than a previously identified hemocyte lectin with an affinity to N-acetylglucosamine, tachylectin-2. The purified tachylectin-4 is an oligomeric glycoprotein of 470 kDa, composed of subunits of 30 and 31.5 kDa. Ca2+ at 10 mM enhanced the hemagglutinating activity 4-fold, and the activity was inhibited by EDTA and o-phenanthroline. L-Fucose and N-acetylneuraminic acid at 100 mM completely inhibited the activity of tachylectin-4. The activity was also inhibited more strongly by bacterial S-type lipopolysaccharides (LPS) but not by R-type LPS lacking O-antigen. The most effective S-type LPS was from Escherichia coli O111:B4, and the minimum concentration required for inhibiting agglutination against human A-type erythrocytes (0.1 microg/ml) was 160-fold lower than those of S-type LPS from Salmonella minnesota. Therefore, colitose (3-deoxy-L-fucose), a unique sugar present in the O-antigen of E. coli O111:B4 with structural similarity to L-fucose, is the most probable candidate for a specific ligand of tachylectin-4. A cDNA coding for tachylectin-4 was isolated from a hemocyte cDNA library. The open reading frame of the 1344-base pair cDNA coded for the mature protein with 232 amino acids. There is no significant sequence similarity to any other known LPS-binding lectins, whereas tachylectin-4 is homologous to the NH2-terminal domain with unknown functions of Xenopus laevis pentraxin 1.

Amino Acid Sequence↗
PubMed1997

Nucleotide sequence and molecular characterization of a gene encoding GTP-binding protein from Streptococcus gordonii.

A 1286-bp fragment of chromosomal DNA from Streptococcus gordonii strain Challis was cloned and sequenced. The gene sgg consisted of 897-bp nucleotides encoding a 299-amino acid polypeptide (33,200 Da). The deduced amino acid sequence exhibited significant similarity to Era, G protein of Escherichia coli. The nucleotide binding assay demonstrated that recombinant Sgg bound [32P]GTP but not [32P]ATP, [32P]CTP, or [32P]UTP. These findings indicate that Sgg is a member of the G protein superfamily in the genus Streptococcus.

Amino Acid Sequence↗
PubMed1997

Oral immunization with simian immunodeficiency virus p55gag and cholera toxin elicits both mucosal IgA and systemic IgG immune responses in nonhuman primates.

Rhesus macaques were orally immunized with a mucosal vaccine consisting of two different concentrations (1 mg vs 250 microg) of recombinant SIV p55gag (p55) with or without cholera toxin (CT, 50 microg) as a mucosal adjuvant. The plasma from macaques receiving the higher dose of p55 (1 mg) and CT had higher p55-specific IgG and IgA Ab titers compared with macaques that received the lower dose of p55 (250 microg) and CT. Further, high levels of p55-specific IgG and IgA Abs were present in external secretions from both groups. The level of p55-induced T cell responses was elevated in PBMCs isolated from the high dose group compared with the low dose group. When culture supernatants from these p55-stimulated PBMCs were examined for Th1 (IFN-gamma) and Th2 (IL-4 and IL-10) cytokines, both IFN-gamma and IL-10 were present, but IL-4 was absent. CD4+ T cells isolated from these p55-stimulated PBMCs contained IFN-gamma spot-forming cells (SFCs) but not IL-4 SFCs. These results were further confirmed by cytokine-specific reverse transcriptase PCR analysis, where p55-specific CD4+ T cells expressed mRNA for IFN-gamma, IL-6, and IL-10, but not IL-4. These findings suggest that oral immunization of nonhuman primates induced both IFN-gamma-secreting Th1 and select Th2 cytokine (e.g., IL-6 and IL-10)-producing CD4+ Th cells, which accounted for the generation of p55-specific systemic and mucosal Ab responses.

Administration, Oral↗
PubMed1997

Purification and characterization of prophenoloxidase from the hemolymph of coleopteran insect, Holotrichia diomphalia larvae.

Prophenoloxidase (pro-PO), a precursor of phenol oxidase (PO), was purified from the hemolymph of coleopteran Holotrichia diomphalia larvae. The enzyme was purified to apparent homogeneity, in six steps of chromatography, using Sephadex G-100, CM-52, Dextran-sulfate Sepharose CL-6B, Phenyl Sepharose CL-4B, Sephacryl S-200, and a Mono-Q column. The preparation exhibited a single band on SDS-PAGE. The proenzyme had a molecular weight of 158 kDa, as estimated by gel filtration. On SDS-PAGE under reducing conditions, it gave a 79 kDa band, indicating that it forms a dimer of the 79 kDa protein. On the other hand, the purified pro-PO gave two well-separated peaks, named pro-PO-1 and pro-PO-2, on reverse-phase HPLC. Amino acid compositions of both proteins were indistinguishable, thereby suggesting the presence of an allelic variant or an isoprotein. On dextran-sulfate Sepharose CL-6B chromatography, a fraction containing prophenoloxidase activating enzyme(s) (PPAE fraction), free from pro-PO, was also separated. In reconstitution experiments, the activation of purified pro-PO by PPAE fraction, was observed in the presence of 5 mM Ca2+, with a specific limited proteolysis. The NH2-terminal sequence of generated PO was determined to be NH2-Phe-Gly-Glu-Asp-Asp-. The activated PO oxidized o-diphenols but did not oxidize mono-phenol and p-diphenol substrates. The purified pro-PO was not activated by trypsin, alpha-chymotrypsin, and SDS.

Amino Acid Sequence↗
PubMed1997

Analysis of glycosidic linkages in saccharide compounds by post-source decay fragment methods in matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy.

Maltotriosyl- and panosyl-alpha-cyclodextrins and the nonaose of pullulan were analyzed by post-source decay (PSD) fragment methods of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy. By the mass number analysis, it was found that all of the PSD fragment ions were produced by cleavages of glycosidic linkages. Comparison of the relative intensities of the ions in those compounds enabled us to distinguish two kinds of glycosidic linkages, alpha 1-4 and alpha 1-6, by MALDI-TOFMS with a new type of ion reflector: the curved field reflectron.

Carbohydrate Sequence↗
PubMed1997

Biochemical and physicochemical characterization of normal and variant forms of human MTH1 protein with antimutagenic activity.

8-Oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP) is produced during cellular metabolism, and its misincorporation into DNA causes mutation. Human cells possess an enzyme that hydrolyzes 8-oxo-dGTP to the corresponding nucleoside monophosphate, thereby preventing misincorporation of 8-oxo-7,8-dihydroguanine into DNA. Sequence analyses of the MTH1 gene, encoding the 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphatase (8-oxo-dGTPase) protein in human cell lines revealed that a G to A base substitution frequently occurs at codon 83, which causes a change of valine to methionine in the MTH1 protein [Wu, C. et al., Biochem. Biophys. Res. Commun. 214 (1995) 1239-1245]. Here we isolated cDNAs for the two types of MTH1 protein and expressed them in Escherichia coli mutT-. cells, devoid of their own 8-oxo-dGTPase activity. The two forms of proteins were purified to physical homogeneity, and amino acid analyses confirmed that the variant protein, Met83-MTH1, indeed carries the corresponding amino acid substitution. Met83-MTH1, but not normal type Val83-MTH1, was separated into two peaks in hydrophobic interacting chromatography. 8-Oxo-dGTPase activity of Met83-MTH1 is more thermolabile than that of Val83-MTH1. Circular dichroism (CD) and fluorescence spectroscopic analyses confirmed this conclusion. CD further indicated that Met83-MTH1 has a higher alpha-helix content.

Amino Acid Substitution↗
PubMed1997

Tissue distribution and subcellular localization of rabbit liver metalloendopeptidase.

We have previously isolated rabbit liver microsomal metalloendopeptidase (MEP) as a candidate for the processing enzyme of vitamin K-dependent plasma proteins. A cDNA coding for MEP has revealed that it is structurally related to metalloendopeptidase-24.15, which catalyzes the proteolytic processing of several bioactive peptides. In this study we examined the tissue distribution and subcellular localization of MEP by light and electron microscopic immunohistochemical methods, in addition to Northern blot analysis. Chicken polyclonal antibodies were raised by using synthetic peptides AG1 (Met31-Asn46) and AG3 (Asp537-Gly551) derived from the sequence of MEP. Both anti-AG1 and anti-AG3 antibodies reacted specifically with MEP, as judged by Western blotting and immunohistochemical methods. Both antibodies gave an identical staining distribution, which was localized on the luminal cell surfaces and in the cytoplasm of the following organs: liver, brain, lungs, kidneys, esophagus, stomach, duodenum, pancreas, placenta, epididymis, uterus, ovary, and oviduct. Northern blot analysis revealed that the expression of MEP mRNA is similar to its immunohistochemical distribution except in the heart. These results suggest that MEP may participate more closely in a degradation role in peptide metabolism in various tissues than in a processing role of the proprotein, like metalloendopeptidase-24.15.

Amino Acid Sequence↗