Biomedical subjects

T Nakazawa

Publications and source records attributed to T Nakazawa.

At least 73 records · Page 4Linked to original sources

PubMed2000

Modulation of tumor necrosis factor-alpha production with anti-hypertensive drugs.

It is well known that some anti-hypertensive drugs affect insulin sensitivity and that tumor necrosis factor-alpha (TNF-alpha) is a mediator of obesity-associated insulin resistance. In this study, we have investigated the effect of anti-hypertensive drugs, calcium (Ca) channel blockers (amlodipine, manidipine and nicardipine), an alpha(1)-blocker (doxazosin), a beta(1)-blocker (metoprolol), and a thiazide diuretic (hydrochlorothiazide), on lipopolysaccharide (LPS)-induced TNF-alpha production. TNF-alpha production, measured with a bioassay and an immunoassay, was evaluated both in vivo and in vitro, by utilizing mice and a human peripheral blood mononuclear cell culture, respectively. Nicardipine, or amlodipine, manidipine and doxazosin significantly inhibited TNF-alpha production in mice at doses more than one or ten times higher than those used clinically, respectively. On the other hand, metoprolol increased TNF-alpha production at doses of more than 10 times those used clinically, whereas hydrochlorothiazide did not alter production of the cytokine. The in vivo effects of these drugs were not necessary parallel to the in vitro effects. Because high doses of these drugs in mice correspond to clinical doses and effects in human, these actions may be related to beneficial and/or harmful effects of these drugs on TNF-alpha mediated diseases, including insulin resistance.

Adrenergic alpha-Antagonists↗

PubMed2000

Acute glomerulonephritis after human parvovirus B19 infection.

We evaluated clinical and histological characteristics of four adult patients who presented with acute glomerulonephritic syndrome with serological confirmation of recent HPB19 infection. All patients had generalized edema with urinary abnormalities. Body weight gain ranged from 3 to 10 kg. Three of the patients had contact with erythema infectiosum simultaneously with or within 10 days before development of flu-like symptoms. Two patients had an erythematous rash, and one patient had lower-extremity purpura. Joint pain was present in three of the patients. All patients had proteinuria and hematuria. Renal functions were normal except in one patient who had a serum creatinine of 3.2 mg/dL. Three of the patients had hypocomplementemia. All renal biopsy specimens were characterized by glomerular leukocyte infiltration and endothelial cell swelling. Mesangiolysis was seen in three of the patients. C3 was deposited in a coarse granular pattern along the capillary walls in all cases. Electron microscopic examination showed marked expansion of the subendothelial space of glomerular capillaries in all patients. Subendothelial electron-dense deposits were present in all patients. Immunohistochemical analysis using monoclonal anti-HPB19 antibody showed that one of the four patients had positive staining in the glomeruli. DNA extracted from renal biopsy specimens contained HPB19 DNA, as shown by polymerase chain reaction (PCR) analysis in all patients. PCR amplification of the renal DNA generated a 104-bp product, which hybridized to an HPB19-specific probe. No control group subjects contained HPB19 DNA as determined by PCR. This circumstantial evidence indicates that HPB19 infection may be one of the causes of acute glomerulonephritis in normal individuals.

Acute Disease↗

PubMed2000

Digital glomerular reconstruction in a patient with a sporadic adult form of glomerulocystic kidney disease.

This study describes a sporadic adult form of glomerulocystic kidney disease in a 52-year-old man. To determine whether the aperture of the proximal tubule was stenosed or obstructed to clarify the pathogenesis of glomerular cyst development, 100 serial sections of the open biopsy specimen were made. Ten glomerular cysts were reconstructed using three-dimensional imaging analysis. Bowman's capsule (glomerular cyst) volume, the volume of glomerular tufts, and the area of the proximal tubular opening were estimated using imaging analysis. The volumes of Bowman's capsule and of glomerular tufts were 0.0098 +/- 0.0039 mm3 (mean +/- SD) (normal: 0.0041 to 0.0083 mm3) and 0.0026 +/- 0.0013 mm3, respectively. The area of the proximal tubular opening was 0.0017 +/- 0.0003 mm2 (normal: 0.0012 to 0.0028 mm2). There was neither obstruction nor stenosis of the opening of the renal tubule in this sporadic adult form of glomerulocystic kidney disease. After 4 years of hemodialysis, the glomerular cysts, as well as the kidneys, enlarged. This study shows that the main cause of glomerular cyst development is not glomerulotubular neck obstruction.

Adolescent↗

PubMed2000

Unique mechanism of Helicobacter pylori for colonizing the gastric mucus.

Helicobacter pylori is a human gastric pathogen causing chronic infection. Urease and motility using flagella are essential factors for its colonization. Urease of H. pylori exists both on the surface and in the cytoplasm, and is involved in neutralizing gastric acid and in chemotactic motility. H. pylori senses the concentration gradients of urea in the gastric mucus layer, then moves toward the epithelial surface by chemotactic movement. The energy source for the flagella movement is the proton motive force. The hydrolysis of urea by the cytoplasmic urease possibly generates additional energy for the flagellar rotation in the mucus gel layer.

Animals↗

PubMed2000

Transmission of Helicobacter pylori from challenged to nonchallenged nude mice kept in a single cage.

To determine the transmission route of Helicobacter pylori, one nude mouse was challenged by H. pylori, and then raised with nonchallenged nude mice in a single cage in a sterilized environment with and without exposure to their feces. After coraising for two and four weeks, all mice were killed to determine H. pylori in the stomach, saliva, and feces and to assess gastritis grade. Natural transmission of H. pylori occurred in 50% (2/4) and 70% (7/10) of mice after two weeks and four weeks of coraising when they were exposed to their feces. H. pylori was detected not only in the stomach but also in saliva and feces by PCR of all challenged and transmitted mice. However, no transmission occurred in mice not exposed to feces of a challenged mouse, while sharing food and water in a single cage. These findings suggest that the fecal-oral transmission route is important, at least in the animal model. Serum levels of anti-H. pylori urease IgG of the H. pylori-transmitted mice increased after coraising, and gastritis was observed in the stomach of both challenged and transmitted mice. We conclude that H. pylori bacteria are transmitted through the fecal-oral route from challenged to nonchallenged nude mice, resulting in gastritis.

Animals↗

PubMed2000

Effects of HNS-32, a novel antiarrhythmic drug, on ventricular arrhythmias induced by coronary artery occlusion and reperfusion in anesthetized rats.

HNS-32 (N1,N1-dimethyl-N2-(2-pyridylmethyl)-5-isopropyl-3, 8-dimethylazulene-1-carboxamidine: CAS 186086-10-2) is a newly synthesized compound, and possesses antiarrhythmic properties with vasodilator action in dog hearts. The aim of this study was to investigate the dose-dependent effects of HNS-32 on ischemia- and/or reperfusion-induced ventricular arrhythmias in anesthetized rats in vivo and compared with those of mexiletine. Saline or drugs were administered intravenously 5 min prior to coronary artery occlusion. On the ischemia-induced ventricular arrhythmias, HNS-32 showed dose-dependent reduction of total number of premature ventricular complexes (PVC) from 2091+/-225 to 656+/-116 and 286+/-69 beats/30 min (p < 0.05), the ventricular tachycardia (VT) duration from 183+/-33 to 28+/-9 and 4+/-2 sec (p < 0.05), the incidence of VT from 100 to 90 (n.s.) and 40% (p < 0.05), and the incidence of ventricular fibrillation (VF) from 50 to 0 and 0% (p < 0.05) with 3 and 5 mg/kg, respectively. Mexiletine also reduced these parameters to 936+/-159 beats/30 min (p < 0.05), 39+/-22 sec (p < 0.05), 90% (n.s.) and 10% (n.s.), respectively. HNS-32 completely suppressed the late reperfusion-induced arrhythmias, however mexiletine did not affect them. On the early reperfusion-induced ventricular arrhythmias, HNS-32 showed dose-dependent reduction of VT duration from 126+/-34 to 37+/-12 and 3+/-2 sec (p < 0.05), incidence of VT from 100 to 90 (n.s.) and 40% (p < 0.05), incidence of VF from 100 to 10 and 0% (p < 0.05), and mortality rate from 90 to 0 and 0% (p < 0.05), with 3 and 5 mg/kg, respectively. Mexiletine also reduced these parameters to 16+/-9 sec (p < 0.05), 80 (n.s.), 50 (p < 0.05), and 10% (p < 0.05), respectively. HNS-32 significantly reduced the heart rate in a dose-dependent manner, from 399+/-14 to 350+/-8 and 299+/-10 beats/min (p < 0.05) with 3 and 5 mg/kg, respectively. The antiarrhythmic effects of HNS-32 were more potent than that of the similar dose of mexiletine against occlusion-induced and reperfusion-induced arrhythmias in in vivo rats.

Animals↗

PubMed2000

Magnetic resonance imaging of a non-pigmented adenoma of the ciliary epithelium.

PURPOSE: A non-pigmented adenoma of the ciliary epithelium is rare. No good documentation has been reported in which magnetic resonance imaging (MRI), histological examination, and immunohistological evaluation have all been conducted. We showed how this tumor differed from ciliary body melanoma. METHODS: We evaluated the ciliary body tumor by MRI, histological examination, and immunohistochemical examination. The data was compared with previously reported cases. RESULT: The tumor was classified as an adenoma of the non-pigmented ciliary epithelium with extracellular pools of hyaluronidase-sensitive mucopolysaccharide. The MRI appearance of the vitreous in our patient showed hyperintensity on T1, isointensity on T2 and marked enhancement with gadolinium. None of 3 other reported patients exhibited the same signals. CONCLUSION: MRI appearance is most variable in adenomas and no microscopical diagnosis can be based on that. Our patient showed isointensity on T2 with marked enhancement by gadolinium when compared to malignant melanoma.

Adenoma↗

PubMed2000

A novel in vitro effect of the mucosal protective agent sofalcone--inhibition of chemotactic motility in Helicobacter pylori.

BACKGROUND: Motility of Helicobacter pylori is essential for colonization. H. pylori has been shown to exhibit chemotactic activity toward urea and sodium and bicarbonate ions, which are secreted from the gastric epithelia. The importance of urease activity for chemotactic motility of H. pylori in a viscous environment has also been shown. Consequently, application of drugs inhibiting chemotactic motility has been proposed as a strategy for H. pylori eradication. This inhibitory effect can be evaluated through assay of chemotaxis and swarming. MATERIALS AND METHODS: H. pylori CPY3401 and ATCC43504 were grown on brucella agar plates/broth supplemented with 3% horse serum under microaerobic conditions (N2, 85%; O2, 5%; CO2, 10%). For motility assay, H. pylori cells grown on brucella-serum agar were stabbed into motility agar containing 0.35% refined agar in brucella-serum broth and the swarming zone was measured. For the chemotaxis assay, cells were suspended in 10 mM potassium phosphate buffer, pH 7.0, with 3% polyvinyl-pyrrolidone and assayed as described previously. Bacterial swimming in the fluid environment was observed under dark-field microscopy. RESULTS: Numbers of bacteria attracted toward 1 microM flurofamide were reduced with increasing concentrations of sofalcone (0.2-222 microM). In addition, the size of the swarming zone was reduced in motility agar containing 22 and 222 microM sofalcone. On the other hand, 22 microM sofalcone did not inhibit bacterial growth on day 3. Bacterial swimming speed in brucella broth was slower in the presence of 22 and 222 microM sofalcone than in its absence. CONCLUSION: Sofalcone was found to inhibit chemotactic motility of H. pylori. This drug may be useful for inhibiting the bacterium's ability to colonize the human stomach.

Anti-Ulcer Agents↗

PubMed2000

Identification of the urease operon in Helicobacter pylori and its control by mRNA decay in response to pH.

We investigated the transcription of the urease gene cluster ureABIEFGH in Helicobacter pylori to determine the regulation of gene expression of the highly produced enzyme urease. Northern blot hybridization analysis demonstrated that cells of the wild-type strain grown in an ordinary broth had transcripts of ureAB, ureABI, ureI, ureIE' and ure'FGH, but cells of a ureI-disrupted mutant had only the ureAB transcript. When the wild-type cells were exposed to pH 8 for 30 min, very little mRNA was detected. However, when exposed to pH 6, a large amount of the ureIE" transcript, which was longer than the ureIE' transcript, together with the additional transcripts ureABIEFGH and ure'EFGH were detected. Rifampicin addition experiments demonstrated that urease mRNAs, and the ureIE' transcripts in particular, are more stable at pH 5.5 than at pH 7. In accord with these results, urease activity in the crude cell extract of the pH 5.5 culture was twice as much as that of the pH 7 culture, although the amounts of UreA and UreB detected by immunoblot analysis were similar. The transcription start point of ureI was identified by primer extension using a ureA promoter-deleted mutant, and a consensus sequence of RpoD-RNA polymerase was found in the ureI promoter. The 3' end of the ureIE" mRNA, determined using S1 nuclease mapping, revealed that the transcript is able to cover the majority of the ureE open reading frame (ORF) that might be sufficient for UreE activity. Based on the above results, we conclude that the urease gene cluster of H. pylori consists of two operons, ureAB and ureIEFGH, and that primary transcripts of the latter as well as the read-through transcript, ureABIEFGH, are cleaved to produce several species of mRNA. It has been suggested that the ureIEFGH operon is regulated post-transcriptionally by mRNA decay in response to environmental pH. We are tempted to speculate that the ureE" transcript present in acidic pH may contribute to produce an active product that can proceed the nickel incorporation to the active centre, the final step of urease biosynthesis.

Amino Acid Sequence↗

PubMed2000

Tracheoesophageal fistula after blunt chest trauma: successful diagnosis by computed tomography.

A case of tracheoesophageal fistula after blunt trauma is reported. A 27-year-old man who suffered from an automobile traffic accident complained of strong choking after drinking water. Computed tomography demonstrated a defect between the esophagus and the trachea just above the carina. Acquired tracheoesophageal fistula was suspected and promptly confirmed by contrast esophagogram. The defects of the trachea and esophagus was repaired by primary suture and buttressed using a pedicled intercostal flap. The postoperative course was uneventful.

Accidents, Traffic↗

PubMed2000

Comparison of outer membrane protein genes omp and pmp in the whole genome sequences of Chlamydia pneumoniae isolates from Japan and the United States.

Chlamydia pneumoniae is a widespread pathogen of the respiratory tract that is also associated with atherosclerosis. The whole genome sequence was determined for a Japanese isolate, C. pneumoniae strain J138. The sequence predicted a variety of genes encoding outer membrane proteins (OMPs) including ompA and porB, another 10 predicted omp genes, and 27 pmp genes. All were detected in the whole genome sequence of strain CWL029, a strain isolated and sequenced in the United States. A comparative study of the OMPs of the two strains revealed a nucleotide sequence identity of 89.6%-100% (deduced amino acid sequence identity, 71.1%-100%). The overall genomic organization and location of genes are identical in both strains. Thus, a few unique sequences of the OMPs may be essential for specific attributes that define the differential biology of two C. pneumoniae strains.

Bacterial Outer Membrane Proteins↗

PubMed2000

Chlamydia pneumoniae in atherosclerotic and nonatherosclerotic tissue.

The positivity rate and localization of Chlamydia pneumoniae were investigated in atherosclerotic and nonatherosclerotic tissues by immunohistochemistry, polymerase chain reaction, and cell culture. In total, 67 atheromatous plaques from Japanese symptomatic patients and 110 nonatherosclerotic tissues and organs were evaluated. Of these, 62% of atherosclerotic plaques from symptomatic patients were infected with C. pneumoniae compared with just 2% of nonatherosclerotic tissues. Immunohistochemically stained C. pneumoniae were found most often in smooth muscle cells, less often in macrophages, and in a few endothelial cells.

Adult↗

PubMed2000

Ascending cholangitis as a cause of pyogenic liver abscesses complicated by a gastric submucosal abscess and fistula.

Ruptures of nonamebic (pyogenic) liver abscesses into the thorax and peritoneum are very uncommon; but, hepatoduodenal and hepatocolonic fistulas are ever more rare. We report a case where ascending cholangitis was associated with pyogenic liver abscess formation and a gastric fistula. Drainage into the stomach was demonstrated by gastroduodenal endoscopy for gastric bleeding. After fistula formation, we could successfully treat the inflammation caused by infection of Citrobacter freundii and Candida albicans with intravenous infusion of both antibiotic and antifungal agents.

Aged↗

PubMed2000

Apoptosis of acinar cells is involved in chronic pancreatitis in Wbn/Kob rats: role of glucocorticoids.

The involvement of pancreatic acinar cell apoptosis and its relation to glucocorticoid exposure were investigated in spontaneously occurring chronic pancreatitis in male Wistar Bonn/Kobori (WBN/Kob) rats. Although most lobules were not inflamed in 10-week-old WBN/Kob, increased apoptosis of pancreatic acinar cells, confirmed by TUNEL staining was focally observed (0.10 +/- 0.10 vs. 0.05 +/- 0.10/field in 10-week Wistar rats). Localized hemorrhagic lesions and brown foci in the splenic lobes were apparent, with significant decrease in pancreas weight in 20-week WBN/Kob rats along with marked apoptosis (1.95 +/- 0.31 vs. 0.07 +/- 0.04/field in 20-week Wistar rats). Electron microscopy revealed apoptotic bodies to be present in acinar cells. Pancreatic myeloperoxidase activities, indirect indices of granulocyte infiltration, as well as histologic scores were significantly increased at 15 and 20 weeks, and endogenous corticosterone levels were significantly decreased at 10, 15, and 20 weeks as compared with values for age-matched Wistar rats. Prednisolone in the drinking water (0.01 mg/mL; calculated dose, 1.03 0.03 mg/kg/d) for 10 weeks significantly attenuated increases in numbers of apoptotic acinar cells and pancreatic myeloperoxidase activities and tended to reduce the histologic scores in 20-week WBN/Kob rats as compared with the vehicle group. In summary, (a) apoptosis of pancreatic acinar cells is involved in chronic pancreatitis, (b) endogenous corticosterone is decreased, and (c) prednisolone treatment attenuates both apoptosis of pancreatic acinar cells and chronic pancreatitis in male WBN/Kob rats. We conclude that apoptosis of acinar cells related to decreased corticosterone may be a trigger of chronic pancreatitis in this model.

Adrenocorticotropic Hormone↗

PubMed2000

The dsbA-dsbB disulfide bond formation system of Burkholderia cepacia is involved in the production of protease and alkaline phosphatase, motility, metal resistance, and multi-drug resistance.

In a previous study, we isolated a dsbB mutant of Burkholderia cepacia KF1 and showed that phenotypes of protease production and motility are dependent on DsbB, a membrane-bound disulfide bond oxidoreductase. We have now isolated a dsbA mutant by transposon mutagenesis, cloned the dsbA gene encoding a periplasmic disulfide bond oxidoreductase, and characterized the function of the DsbA-DsbB disulfide bond formation system in B. cepacia. The complementing DNA fragment had an open reading frame for a 212-amino acid polypeptide with a potential redox-active site sequence of Cys-Pro-His-Cys that is homologous to Escherichia coli DsbA. The dsbA mutant, as well as the previously isolated dsbB mutant, was defective in the production of extracellular protease and alkaline phosphatase, as well as in motility. In addition, mutation in the DsbA-DsbB system resulted in an increase in sensitivity to Cd2+ and Zn2+ as well as a variety of antibiotics including beta-lactams, kanamycin, erythromycin, novobiocin, ofloxacin and sodium dodecyl sulfate. These results suggested that the DsbA-DsbB system might be involved in the formation of a metal efflux system as well as a multi-drug resistance system.

Alkaline Phosphatase↗

PubMed2000

Differences in genotypes of Helicobacter pylori from different human populations.

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.

Amino Acid Isomerases↗

PubMed2000

Functional organization and insertion specificity of IS607, a chimeric element of Helicobacter pylori.

A search by subtractive hybridization for sequences present in only certain strains of Helicobacter pylori led to the discovery of a 2-kb transposable element to be called IS607, which further PCR and hybridization tests indicated was present in about one-fifth of H. pylori strains worldwide. IS607 contained two open reading frames (ORFs) of possibly different phylogenetic origin. One ORF (orfB) exhibited protein-level homology to one of two putative transposase genes found in several other chimeric elements including IS605 (also of H. pylori) and IS1535 (of Mycobacterium tuberculosis). The second IS607 gene (orfA) was unrelated to the second gene of IS605 and might possibly be chimeric itself: it exhibited protein-level homology to merR bacterial regulatory genes in the first approximately 50 codons and homology to the second gene of IS1535 (annotated as "resolvase," apparently due to a weak short recombinase motif) in the remaining three-fourths of its length. IS607 was found to transpose in Escherichia coli, and analyses of sequences of IS607-target DNA junctions in H. pylori and E. coli indicated that it inserted either next to or between adjacent GG nucleotides, and generated either a 2-bp or a 0-bp target sequence duplication, respectively. Mutational tests showed that its transposition in E. coli required orfA but not orfB, suggesting that OrfA protein may represent a new, previously unrecognized, family of bacterial transposases.

Amino Acid Sequence↗

PubMed2000

In vitro pharmacological profile of SK-896, a new human motilin analogue.

SK-896 ([Leu(13)]motilin-Hse) is a new human motilin analogue synthesized by Escherichia coli using a biotechnological method. We investigated the binding of SK-896 to motilin receptors and the contractile effect of SK-896 on smooth muscle preparations isolated from the gastrointestinal tract and various regional organs in order to clarify its in vitro pharmacological profile. SK-896 inhibited the binding of (125)I-human motilin to rabbit gastroduodenal motilin receptors with the same potency as unlabeled human motilin. The IC(50) values of SK-896 and human motilin were 3.5 +/- 1.5 and 3.1 +/- 1.8 nmol/l, respectively. The K(d) of human motilin was 3.0 +/- 1.5 nmol/l, and the Ki of SK-896 was 3.4 +/- 1.5 nmol/l. SK-896 induced contraction of smooth muscle preparations isolated from rabbit duodenum in a concentration-dependent manner. However, there was no effect of SK-896 on duodenal preparations isolated from the dog and the rat. SK-896 thus exhibited species specificity in its contractile effect. We next investigated the effect of SK-896 on various smooth muscle preparations isolated from rabbit gastrointestinal tract, trachea, bladder, gallbladder, uterus, vas deferens and artery. Results showed that SK-896 induced contraction of smooth muscle preparations isolated from gastrointestinal tract, with potencies in the order duodenum > gastric pylorus = jejunum = descending colon > ascending colon >/= ileum. However, there was no effect of SK-896 on smooth muscle preparations from gastric fundus and other regional organs. SK-896 thus exhibited regional specificity in its contractile effect. Moreover, the effects of SK-896 on smooth muscle preparations from rabbit duodenum were the same as those of human motilin, and were not inhibited by pretreatment with tetrodotoxin and atropine but were inhibited by verapamil. These findings indicate that SK-896 has the same pharmacological profile as human motilin. They suggest that SK-896 acts on gastrointestinal smooth muscle isolated from rabbit directly and specifically.

Animals↗