Molecular characterization of a gene locus encoding biosynthesis pathway of Streptococcus mutans serotype C-specific antigen.
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Antigens, Bacterial↗
Biomedical subjects
T Koga
Publications and source records attributed to T Koga.
Mediastinal parathyroid adenoma detected by 99mTc-methoxyisobutylisonitrile: report of a case.
We report herein the case of a 30-year-old man in whom ectopic mediastinal parathyroid adenoma was detected by 99mTc-methoxyisobutylisonitrile scintigraphy (99mTc-MIBI). The patient presented with a history of recurrent renal stones and was diagnosed as having primary hyperparathyroidism due to elevated serum levels of calcium and intact parathyroid hormone (i-PTH) levels. On admission, his serum calcium value was 12.1 mg/dl and the i-PTH level was 137 pg/ml. Ultrasonography, computed tomography (CT), and 201TlCl-99mTcO4- subtraction scintigraphy (Tl-Tc) were performed but none of these imaging techniques was able to detect an enlarged parathyroid gland. Selective venous sampling revealed that the serum i-PTH level was highest at 422 pg/ml in the left brachiocephalic vein. Exploration of the neck also proved unsuccessful. Finally, we performed 99mTc-MIBI which revealed and delineated an enlarged parathyroid gland in the upper mediastinum. Tumor extirpation was subsequently performed through a left thoracotomy. Pathologically, the tumor was confirmed to be a parathyroid adenoma and the serum calcium and i-PTH levels returned to within the normal ranges postoperatively.
Adenoma↗
Quaternary structure-dependent idiotope and antigen binding of a monoclonal antibody specific for conformational epitope on type II collagen.
We previously generated a monoclonal antibody (mAb) against a putative pathogenic epitope on native type II collagen (CII) for the induction of collagen-induced arthritis in mice (mAb1), and an anti-idiotypic mAb which appears to possess the internal image of the CII epitope (mAb2). In the present study, the structural basis of the antigen/mAb1 and mAb1/mAb2 interactions was examined. When partially SH-reduced mAb1 was analysed on Western blots, only fragments containing both heavy (H) and light (L) chains were recognized by mAb2. When mAb2 was partially SH-reduced, only fragments containing both H and L chains were recognized by mAb1. H and L chains were separated from mAb1 in a reduced, denatured condition, and each chain and a mixture of the two were refolded. mAb2 reacted specifically to the renatured whole IgG molecule of mAb1, but not to the refolded L or to H chains. Recombinant single chain Fv (scFv) generated from mAb1 and mAb2 had properties of the original mAbs, whereas genetically constructed chimeric scFvs, consisting of VH from mAb1 and an irrelevant VL. or VL of mAb1 and an irrelevant VH. did not react either to CII or to mAb2. Thus, interactions among CII, mAb1 and mAb2 appear to depend on quaternary structures containing different protein subunits. These observations support the internal image property of the mAb2. In addition, this dependency on quaternary structure for recognition of proteins may also be relevant to other protein-protein interactions.
Amino Acid Sequence↗
Neuronal gagging activity patterns may be generated by neurons in the reticular area dorsomedial to the retrofacial nucleus in dogs.
Expulsion is induced when hypercapnea and hypoxia develop during retching, or when the oropharyngeal mucosa is irritated (the gag reflex). The central pattern generator (CPG) for expulsion has been suggested to coexist with the CPG for retching in the reticular area dorsomedial to the retrofacial nucleus, which may correspond to the Botzinger complex (BOT). However, its participation in gagging induced by oropharyngeal irritation is unclear. To elucidate such participation, the firing patterns of BOT neurons were observed during gagging induced by stimulation of superior laryngeal afferents in decerebrate, paralyzed dogs. Only 23% of inspiratory and 34% of expiratory BOT neurons increased their firing in response to stimulation of the superior laryngeal nerve. In contrast, 75% of nonrespiratory BOT neurons showed enhanced firing with this stimulation. During gagging, each nonrespiratory, inspiratory, and expiratory BOT neuron fired with the same pattern that they exhibited during expulsion caused by changes in blood gases. These firing patterns could be classified into five types and are thought to be appropriate for generating neuronal gagging activity. These results suggest that the CPG for expulsion in the BOT produces gagging when it is activated by oropharyngolaryngeal afferents.
Afferent Pathways↗
Evaluation of abdominal lymphadenopathy in children by ultrasonography.
BACKGROUND: There may be uncertainty as to whether enlarged abdominal lymph nodes (LNs) in children are normal or abnormal. OBJECTIVE: To compare, by ultrasonography (US), enlarged abdominal LNs in healthy children with those in children with acute abdominal pain or acute gastroenteritis. MATERIALS AND METHODS: One hundred and twenty-two asymptomatic children were selected by questionnaire and compared with 44 children with acute abdominal pain of unknown origin and 27 children with acute gastroenteritis. The number of LNs, their location, their shape and the presence of tenderness as detected by finger compression of each LN were evaluated. The children were divided into four groups according to age: 0-2, 3-6, 7-10, and 11-15 years. RESULTS: LNs were detected in the ileo-caecal and/or para-aortic areas in almost all of the asymptomatic children. The number of large LNs ( > 10 mm) in the para-aortic areas was higher in the older children (>/= 7 years of age) than in the younger children ( </= 6 years of age) (P < 0.05). The number of spindle-shaped LNs (ratio of long- to short-axis diameter >/= 2.0) was increased in the older children. The number of LNs was not increased in the children with acute abdominal pain. The size of the LNs was largest in the children with acute gastroenteritis, followed by the children with acute abdominal pain and the asymptomatic children (P < 0.001). Although the shape of the LNs was no different among the three groups of children, the frequency of round-shaped LNs (ratio of long- to short-axis diameter < 2.0) was greater in the older children with acute abdominal pain or acute gastroenteritis than in the asymptomatic children (P < 0.01). The number of LNs with tenderness detected by finger compression was significantly greater in the children with acute abdominal pain and acute gastroenteritis than in the asymptomatic children (P < 0.0001). CONCLUSION: The number of large and round-shaped LNs with tenderness tended to be increased in the children with acute gastroenteritis and acute abdominal pain. There is no clear specificity of LN enlargement in the children with acute abdominal pain, and the main challenge is to diagnose or estimate the organic pathology by US, regardless of the presence of lymphadenopathy.
Abdomen↗
Positive and negative CD4+ thymocyte selection by a single MHC class II/peptide ligand affected by its expression level in the thymus.
The central event in thymic selection of T cells bearing alpha beta TCRs is their interaction with self-peptides bound to self-MHC molecules. With the use of transgenic mouse lines expressing a single peptide/MHC class II complex, we show that CD4+ T cells with the preferential usage of particular TCR V(alpha)s and V(beta)s were selected to mature on this complex in lines with the lower expression, whereas such CD4+ T cells were eliminated in the thymus in a line with the relatively high expression. When a low expressing line was crossed with a high expressing line, the frequency of CD4+ T cells selected by this complex markedly decreased. Thus, these results suggest that a single peptide/MHC class II complex, being affected by its cell surface density in the thymus, can serve as both positively and negatively selecting ligand in vivo.
Amino Acid Sequence↗
Effects of monatepil, a novel calcium antagonist with alpha 1-adrenergic blocking activity, on the low-density lipoprotein receptor in human skin fibroblasts.
To investigate the mechanisms of the hypolipidemic effect of monatepil, a new class of calcium antagonists with alpha 1-adrenergic blocking activity, we examined the effects of the drug on low-density lipoprotein (LDL) receptor activity and the level of LDL receptor mRNA present in cultured human skin fibroblasts. At concentrations of 2 x 10(-5) M, monatepil increased the binding (248 +/- 43%; mean +/- SD), internalization (374 +/- 18%), and degradation (145 +/- 2%) of 125I-LDL in human skin fibroblasts (n = 3, p < 0.05). Treatment of human skin fibroblasts with 2 x 10(-5) M of monatepil for 6 hours resulted in an increase in LDL receptor mRNA to 163% of the control level (n = 2), as shown by Northern blot analysis. Our results suggest that the hypolipidemic clinical effects of monatepil may be due to increased LDL receptor activity.
Adrenergic alpha-1 Receptor Antagonists↗
Ambulatory blood pressure monitoring in patients with essential hypertension treated with a new calcium antagonist, cilnidipine.
Cilnidipine (FRC-8653), a new dihydropyridine calcium antagonist, was given to 14 hospitalized patients with essential hypertension, and 24-hour ambulatory blood pressure (BP) monitoring was performed. Once-daily administration of cilnidipine (5-20 mg) for 1-3 weeks decreased the 24-hour average BP significantly from 149 +/- 4/88 +/- 2 mmHg to 141 +/- 3/82 +/- 2 mmHg without any change in the pulse rate. The decrease in ambulatory BP by cilnidipine was evident during the daytime (156 +/- 4/93 +/- 2 mmHg to 143 +/- 5/84 +/- 2 mmHg, p < 0.01 for systolic BP and p < 0.01 for diastolic BP), while it was mild during nighttime (141 +/- 4/80 +/- 2 mmHg to 133 +/- 4/76 +/- 3 mmHg, p < 0.05 for systolic and ns for diastolic BP). The decrease in the ambulatory BP over the whole day and during the nighttime was significantly correlated with the basal ambulatory BP levels. When the subjects were divided into the high ambulatory BP (n = 7) and low ambulatory BP (n = 7) groups, the BP reduction by cilnidipine was evident throughout 24 hours in the high ambulatory BP group, while it was mild and significant only during daytime in the low ambulatory BP group. In summary, once-daily cilnidipine exerts a sufficient and prolonged reduction of BP without an increase in the pulse rate in patients with hypertension. The potency of cilnidipine to decrease ambulatory BP may depend on the basal ambulatory BP level. Cilnidipine is thus a useful antihypertensive drug that may not cause an excessive decrease in BP or a reflex tachycardia.
Adult↗
Prevention of collagen-induced arthritis (CIA) by treatment with polyethylene glycol-conjugated type II collagen; distinct tolerogenic property of the conjugated collagen from the native one.
Administration of a soluble protein into animals prior to challenge immunization induces immunological tolerance which is specific for the protein. In addition, chemical modification of proteins with polyethylene glycol (PEG) has been reported to convert the immunogenic proteins to become tolerogenic. However, differences in tolerogenic properties between PEG-modified proteins and the native counterparts have never been analysed. The ability of PEG-conjugated type II collagen (PEG-CII) to attenuate CIA, an animal model for rheumatoid arthritis, was compared with the native unconjugated CII. Groups of DBA/1 J mice were treated weekly with i.p. injections with PEG-CII, native CII, or vehicle alone for 3 weeks, before they were challenged with CII in adjuvants. The induction of tolerance was confirmed in both PEG-CII- and CII-pretreated mice when suppression of lymph node T cell proliferation in response to CII was noted. The degrees of suppression of T cell proliferation were comparable between the two pretreated groups. However, induction of arthritis and production of IgG anti-CII antibody were more markedly suppressed in PEG-CII-pretreated mice than in native CII-pretreated mice, although the severity of arthritis and antibody levels in the latter group were also lower than in control mice. IgG2a and IgG2b antibody levels were equally suppressed in the two pretreated groups, whereas the IgG1 level was significantly lower in the PEG-CII-pretreated group than in the native CII-pretreated group. The results provide the first evidence that attachment of PEG to CII renders the protein more tolerogenic.
Animals↗
Linoleic and alpha-linolenic acids differently modify the effects of elaidic acid on polyunsaturated fatty acid metabolism and some immune indices in rats.
To explore whether the metabolic responses to trans, compared with cis, fatty acids depend on the source of dietary polyunsaturated fatty acids (PUFA), male Sprague-Dawley rats, 5 weeks old, were fed on diets containing 30 g oleic (cis) or elaidic (trans) acids/kg in combination with either 70 g perilla oil (alpha-linolenic acid) or safflowerseed oil (linoleic acid)/kg for 3 weeks in separate experiments. The dietary fats were adjusted to have the same level of total PUFA. The dietary manipulation did not influence the growth indices, but spleen weight was greater when the dietary PUFA source was perilla oil. The incorporation of trans fatty acid into liver phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine and adipose tissue lipids, particularly phospholipids, was significantly higher when rats were fed on safflowerseed oil compared with perilla oil. However, only limited differences were observed in the effects of cis and trans fatty acids on the proportions of PUFA in liver phospholipids. Splenic production of prostaglandin E2 was reduced by trans fatty acid when safflowerseed oil was the PUFA source, but no trans effect was observed on leukotriene C4 production. Dietary PUFA significantly influenced the concentration of plasma immunoglobulins (Ig) but the effect of geometry was only seen in IgG which was increased by trans acid. Dietary trans fatty acid increased the CD4+:CD8+ T-lymphocyte ratio in the spleen, reflecting a decreasing trend of the proportion of CD8+, when combined with perilla oil. These observations indicate that the type of PUFA simultaneously ingested specifically influences the effect that trans acid exerts on PUFA metabolism, eicosanoid production and some immune indices.
Animals↗
Differential requirement of MHC class II molecules expressed on hematopoietic cells for positive selection of CD4+ thymocytes in TCR alpha beta and TCR beta transgenic mice.
To address whether expression of the relevant MHC molecules on thymic epithelial cells (TEC) is sufficient for positive selection, the fate of CD4+ T cells directed by the DR alpha E beta b molecule was compared between two lines of HLA-DRA transgenic mice, DR alpha-24 expressing DR alpha E beta b on TEC and hematopoietic cells, and DR alpha-30 expressing the molecule on TEC but not on other cell lineages. CD4+ T cells were selected to mature on DR alpha E beta b molecules in both lines deficient for the endogenous MHC class I and class II molecules, whereas CD4+ T cell differentiation in DR alpha-30, as compared with that in DR alpha-24, was severely impaired when these mice were crossed with mice transgenic for the DR alpha E beta b-restricted alpha beta TCR. In contrast, CD4+ T cells expressing the same TCR alpha beta as the transgenes were selected to mature in DR alpha-30 crossed with the single TCR beta transgenic mice. Taken together, these results indicate that the restricted expression of DR alpha E beta b on TEC is sufficient for positive selection in the TCR beta and non-TCR transgenic mice, but the expression on both TEC and hematopoietic cells is required for that in the TCR alpha beta transgenic mice. In the light of the difference in the developmental stage at which alpha beta TCR are expressed between TCR alpha beta and TCR beta transgenic mice, the interaction of the TCR alpha beta with DR alpha E beta b molecules expressed on hematopoietic cells required for positive selection in TCR alpha beta transgenic mice could be mapped to the early stage of T cell differentiation and might mimic 'undefined' early signaling of thymocytes in physiological T cell differentiation.
Animals↗
Characterization of acetohexamide reductases purified from rabbit liver, kidney, and heart: structural requirements for substrates and inhibitors.
The structural requirements of acetohexamide reductases purified from rabbit liver, kidney, and heart for substrates and inhibitors were examined. Acetohexamide, an oral antidiabetic drug with a ketone group, and analogs of it with various alkyl groups instead of the cyclohexyl group were used as substrates for these three enzymes. The results obtained as to substrate specificity suggested that the nature of the substrate-binding region of the heart enzyme is markedly different from those of the substrate-binding regions of the liver and kidney enzymes. Tolbutamide, which has no ketone group within its chemical structure, strongly inhibited the heart enzyme, whereas it had little ability to inhibit the liver or kidney enzyme. The inhibition of the heart enzyme by tolbutamide was competitive with respect to acetohexamide and uncompetitive with respect to NADPH. Furthermore, tolbutamide analogs with n-pentyl and n-hexyl groups instead of the n-butyl group exhibited very pronounced inhibition of only the heart enzyme. Therefore, it is reasonable to postulate that the heart enzyme, unlike the liver and kidney ones, has a cleft of a strongly hydrophobic nature near its substrate-binding region, and that this hydrophobic cleft plays a critical role in the interaction of the heart enzyme with the cyclohexyl group of acetohexamide.
Acetohexamide↗
Hen egg-white lysozyme inhibits biological activities of lipopolysaccharides from periodontopathic bacteria.
Lysozyme has a bactericidal activity for some strains of Gram-positive bacteria, by enzymatic cleavage of peptidoglycans that constitute the cell wall. Hen egg-white lysozyme (HEL) was tested in vitro for effects on biological activities of lipopolysaccharides from periodontopathic Gram-negative bacteria. Actinobacillus actinomycetemcomitans, Prevotella intermedia and Porphyromonas gingivalis. HEL inhibited a wide range of activities of these lipopolysaccharides, including activation of Limulus amoebocyte lysate, stimulation of human leukocytes to secrete tumour necrosis factor-alpha, polyclonal activation of mouse B cells, and promotion of osteoclastic differentiation in mouse bone marrow cultures. The anti-endotoxic activity of HEL may be worthy of being intended for periodontal therapy.
Aggregatibacter actinomycetemcomitans↗
In vitro and in vivo antibacterial activities of CS-834, a novel oral carbapenem.
CS-834 is a novel oral carbapenem antibiotic. This compound is an ester-type prodrug of the active metabolite R-95867. The antibacterial activity of R-95867 was tested against 1,323 clinical isolates of 35 species and was compared with those of oral cephems, i.e., cefteram, cefpodoxime, cefdinir, and cefditoren, and that of a parenteral carbapenem, imipenem. R-95867 exhibited a broad spectrum of activity covering both gram-positive and -negative aerobes and anaerobes. Its activity was superior to those of the other compounds tested against most of the bacterial species tested. R-95867 showed potent antibacterial activity against clinically significant pathogens: methicillin-susceptible Staphylococcus aureus including ofloxacin-resistant strains, Streptococcus pneumoniae including penicillin-resistant strains, Clostridium perfringens, Neisseria spp., Moraxella catarrhalis, most members of the family Enterobacteriaceae, and Haemophilus influenzae (MIC at which 90% of strains are inhibited, < or =0.006 to 0.78 microg/ml). R-95867 was quite stable to hydrolysis by most of the beta-lactamases tested except the metallo-beta-lactamases from Stenotrophomonas maltophilia and Bacteroides fragilis. R-95867 showed potent bactericidal activity against S. aureus and Escherichia coli. Penicillin-binding proteins 1 and 4 of S. aureus and 1Bs, 2, 3, and 4 of E. coli had high affinities for R-95867. The in vivo efficacy of CS-834 was evaluated in murine systemic infections caused by 16 strains of gram-positive and -negative pathogens. The efficacy of CS-834 was in many cases superior to those of cefteram pivoxil, cefpodoxime proxetil, cefdinir, and cefditoren pivoxil, especially against infections caused by S. aureus, penicillin-resistant S. pneumoniae, E. coli, Citrobacter freundii, and Proteus vulgaris. Among the drugs tested, CS-834 showed the highest efficacy against experimental pneumonia in mice caused by penicillin-resistant S. pneumoniae.
Administration, Oral↗
Identification of a frameshift mutation resulting in premature termination and loss of cell wall anchoring of the PAc antigen of Streptococcus mutans GS-5.
Most strains of Streptococcus mutans possess a 190-kDa protein antigen (PAc) on their cell surfaces, while strain GS-5 produces extracellularly a 155-kDa PAc protein. The pac gene of strain GS-5 consists of 3,477 bp and codes for a protein of 1,158 amino acids. One insertion of an adenine into the 3,469th, 3,470th, or 3,471st position from the start codon results in a frameshift mutation at codon 1157 with subsequent termination after 3 additional codons.
Amino Acid Sequence↗
Role of the charged tail in localization of a surface protein antigen of Streptococcus mutans.
To make clear the role of the C terminus of a surface protein antigen (PAc) of Streptococcus mutans, stepwise truncations beginning at the C terminus of PAc were performed by utilizing site-directed mutagenesis. A remarkable increase in the amount of cell-free PAc was observed upon deletion of four or more amino acid residues at the C terminus. On the other hand, the amount of cell surface PAc gradually decreased when increasing numbers (four or more) of amino acid residues were deleted at the C terminus, and deletion of six amino acids involving both the total charged tail and Leu, an amino acid residue immediately upstream of the charged tail, resulted in a drastic reduction in the amount of cell surface PAc. These results indicate that the cytoplasmic charged tail and Leu residue are required for cell surface localization of PAc in S. mutans.
Antigens, Bacterial↗
Effects of antibodies against cell surface protein antigen PAc-glucosyltransferase fusion proteins on glucan synthesis and cell adhesion of Streptococcus mutans.
Cell surface protein antigen (PAc) and glucosyltransferases (GTFs) produced by Streptococcus mutans are considered to be major colonization factors of the organism, and the inhibition of these two factors is predicted to provide protection against dental caries. In this study, we have constructed fusion protein PAcA-GB, a fusion of the saliva-binding alanine-rich region (PAcA) of PAc with the glucan binding (GB) domain of GTF-I, an enzyme catalyzing the synthesis of water-insoluble glucan from sucrose, and fusion protein PAcA-SB, a fusion of PAcA with the sucrose binding (SB) domain of GTF-I. The recombinant fusion proteins were purified from cell extracts of Escherichia coli harboring the fusion genes, and rabbit antibodies against these fusion proteins were prepared. Water-insoluble glucan synthesis by cell-associated and cell-free GTF preparations from S. mutans as well as total glucan synthesis by GTF-I was markedly inhibited by anti-PAcA-GB immunoglobulin G (IgG) antibodies but not by anti-PAcA-SB IgG antibodies. Significant inhibition of the sucrose-independent and sucrose-dependent adhesion of S. mutans to saliva-coated hydroxyapatite beads was observed when anti-PAcA-GB antibodies were added to the reaction mixture. Anti-PAcA-SB antibodies inhibited the adhesion of S. mutans to the beads in the absence of sucrose but not in the presence of sucrose. Immunization with the fusion protein PAcA-GB may be useful for controlling the colonization of teeth by S. mutans.
Animals↗
Identification of a fourth gene involved in dTDP-rhamnose synthesis in Streptococcus mutans.
We had isolated three genes (rmlA, rmlB, and rmlC) involved in dTDP-rhamnose synthesis in Streptococcus mutans and found that three genes were insufficient for dTDP-rhamnose synthesis (Y. Tsukioka, Y. Yamashita, T. Oho, Y. Nakano, and T. Koga, J. Bacteriol. 179:1126-1134, 1997). The rmlD gene of S. mutans, encoding the enzyme which catalyzes the last step of dTDP-rhamnose synthesis, has been cloned and sequenced. The cell extract of Escherichia coli expressing the rmlD gene of S. mutans exhibited enzymatic activity corresponding to its counterpart in Shigella flexneri, a gram-negative bacterium. Rhamnose was not detected in the cell wall preparation purified from the mutant in which the cloned gene was insertionally inactivated. Rabbit antiserum against S. mutans serotype c-specific antigen did not react with autoclaved extracts from the mutant. The rmlD gene product of S. mutans compensated for the incompleteness of dTDP-rhamnose synthesis by the three previously isolated genes. These results indicate that the rmlD gene product is indispensable for the dTDP-rhamnose pathway and subsequently for the synthesis of serotype-specific antigen in S. mutans. Furthermore, conservation of the rmlD gene in Streptococcus species was demonstrated by Southern blot analysis.
Amino Acid Sequence↗