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Biomedical subjects

M Kurata

Publications and source records attributed to M Kurata.

At least 37 records · Page 2Linked to original sources
PubMed1998

[A case of xanthogranulomatous pyelonephritis followed by computed tomographic scan].

Since it is difficult to differentiate xanthoglanulomatous pyelonephritis (XGP) from renal cancer, most cases of XGP are diagnosed after nephrectomy. We report a rare case of XGP followed by abdominal computed tomographic (CT) scan. A 65-year-old woman was admitted with high fever. Drip infusion pyelography showed a right renal stone but did not visualize the right kidney. A swollen right kidney was revealed on abdominal CT scan. Diabetes mellitus was detected by blood examinations and XGP was suspected. Conservative therapy with antibiotics was performed, the symptoms disappeared within 2 weeks and the right atrophic kidney was revealed on abdominal CT scan 12 months after onset. Histopathological findings on a renal biopsy specimen obtained 1.5 months after treatment were compatible with XGP. The diagnosis of XGP will become easier by using a combined approach including radiographic findings, physical finding and other data.

Aged↗
PubMed1997

Dissection of the promoter/operator region and evaluation of N-acylhomoserine lactone mediated transcriptional regulation of elastase expression in Pseudomonas aeruginosa.

In Pseudomonas aeruginosa, expression of the lasB gene which codes for the metalloprotease, elastase, depends on small diffusible N-acylhomoserine lactones. lasB expression is regulated through the interactions of N-3-oxododecanoyl-L-homoserine lactone and N-butanoyl-L-homoserine lactone with the transcriptional activators LasR and VsmR(RhlR), respectively. To investigate lasB expression further, we first located the transcriptional start site to a position 141 bp upstream from the translational start site. Using this information, we constructed a series of plasmids containing consecutive 5' deletions of the upstream region of lasB fused to a promoterless chloramphenicol acetyltransferase reporter gene. The results obtained indicate that three regions are required for efficient transcription of lasB; a 35 bp palindromic sequence located at +26 to +60 bp upstream from the translation start site, and two regions located upstream of the transcription start site, at -135 to -85 bp and -63 to -26 bp, respectively. Deletion of the latter region results in the loss of both N-butanoyl-L-homoserine lactone- and N-3-oxododecanoyl-L-homoserine lactone-mediated stimulation of lasB expression and provides further support for the role of this operator site as a target for either or both LasR and VsmR.

Bacterial Proteins↗
PubMed1997

Different roles of endothelium-derived substances on inhibiting platelet aggregation in whole blood.

1. The inhibitory effects of adenosine, nitroprusside (a nitric oxide donor) and prostacyclin on collagen-induced rabbit platelet aggregation were studied under two different conditions: in whole blood with an impedance method and in platelet-rich plasma (PRP) with a turbidimetric method. 2. All substances tested were less potent in whole blood than in PRP, and the differences in IC50 value between whole blood and PRP were not of the same order of magnitude; adenosine (669-fold), nitroprusside (54-fold) and prostacyclin (2-fold). 3. These results imply that (a) some other, as yet unknown, factors in blood modulate the platelet aggregation; (b) adenosine and nitric oxide act close to the endothelium, and (c) prostacyclin acts as a relatively long lasting circulating hormone.

Adenosine↗
PubMed1997

Effect of blood collection imitating toxicokinetic study on rat hematological parameters.

The effect of blood collection imitating a one-month toxicokinetic study on hematological parameters was studied in male rats (6 weeks of age at the beginning of the experiment). Three groups were established according to blood sampling points per day; Group I (3 points), Group II (5 points) and Group III (10 points). These repeated blood samplings were carried out on the first and last days of this study, and one-point blood sampling was also done every week during the experiment. In each sampling, 0.3 ml of blood was collected from the jugular vein. There were no changes in Group I, but in other groups, especially in Group III, red blood cell counts, hematocrit and hemoglobin concentration decreased during repeated blood sampling. On the other hand, white blood cell counts also decreased, but recovered within 24 hr. Platelet counts did not show any decrement. From the present result, less than 0.9 ml of blood per day is conceivable as the volume without causing changes in hematological parameters. The baseline of the sampling volume can become one reference for toxicokinetic and toxicological studies.

Animals↗
PubMed1997

[Pulmonary aspergilloma with ring enhancement on chest CT scans].

A 77-year-old man with hemoptysis was admitted to our hospital. A coin lesion in the right middle lung field was observed on a chest X-ray film. Enhanced CT scans of the chest showed the coin lesion with clear ring enhancement. Ring-enhanced mass shadow in cases of pulmonary diseases are very rare. The level of anti-aspergillus antibody in serum was high and the patient was given the diagnosis of aspergillosis. An upper lobectomy was done and aspergillus organisms were found.

Aged↗
PubMed1997

[Self-expanding nitinol stents for treatment of bilateral main bronchial stenosis caused by esophageal cancer].

A 68-year-old man was admitted because of dyspnea. Nine months earlier, he had undergone radiotherapy for esophageal carcinoma. Chest CT scan obtained on admission showed a tumor shadow behind the tracheal carina. Bronchoscopy revealed that the lower trachea and bilateral main bronchi were compressed from the back and narrowed by the esophageal cancer. To maintain the airway, under fluoroscopic and guide-wire control, a self-expanding nitinol stent (SENS, Accuflex, Microvasive) was implanted in the lower trachea and left main bronchus. At the same time, other SENS was similarly implanted in the lower trachea and right main bronchus. During the implantation, the left nitinol stent was connected to the side of the right nitinol stent to form a T-shape. There was little sputum at the joint portion of the stents and the ventilation of both lungs remained adequate. Severe dyspnea markedly improved after placement of two nitinol stents. Knitted SENS is made of a nickel titanium alloy. SENS was formulated for use in the management of biliary obstruction. However, it is highly flexible and easy to implant. So, it is suitable for the treatment of airway obstruction. Although the implantation of SENS in extensive tracheobronchial stenosis has not previously been reported, it should be useful for prevention of airway obstruction.

Aged↗
PubMed1996

Purification and characterization of LasR as a DNA-binding protein.

In Pseudomonas aeruginosa, the activator protein LasR and a cognate autoinducer (AI) are required for expression of the elastase gene (lasB). In the present study, we investigated the binding properties of the P. aeruginosa lasR gene product. The LasR protein was overexpressed and purified as a glutathione S-transferase (GST) fusion protein. Using gel retardation and UV cross-linking analysis, we demonstrated that the GST-LasR could bind to a separate site in the lasB upstream operator regions 1 and 3 in the presence of the autoinducer. Regions 1 and 3 are located at 105 and 42 base pairs upstream, respectively, from the lasB transcriptional start site. Our present results clearly demonstrate that LasR is a specific DNA-binding protein that regulates the transcription of the lasB gene in the presence of an autoinducer.

4-Butyrolactone↗
PubMed1996

Solitary cavernous hemangioma of the duodenum: report of a case.

Vascular lesions of the duodenum, including hemangioma, are rare causes of gastrointestinal bleeding. We herein describe a 52-year-old woman with a solitary cavernous hemangioma of the duodenum that caused chronic gastrointestinal bleeding. Repeated upper gastrointestinal endoscopy and a barium meal study revealed a solitary vascular tumor in the fourth portion of the duodenum, although the initial investigations including selective angiography were unsuccessful. A wedge resection of the duodenum was performed and microscopical examination showed a cavernous hemangioma. Vascular lesions should therefore also be considered in the differential diagnosis of patients with gastrointestinal bleeding of unknown origin.

Diagnosis, Differential↗
PubMed1996

Lack of chemoprevention effects of the monoterpene d-limonene in a rat multi-organ carcinogenesis model.

Modifying effects of dietary administration of the monoterpene d-limonene were examined using a multi-organ carcinogenesis model. Groups of twenty F344 male rats were treated sequentially with N-diethylnitrosamine (DEN, i.p.), N-methyl-N-nitrosourea (MNU, i.p.), 1,2-dimethylhydrazine (DMH, s.c.), N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN, in drinking water) and dihydroxy-di-N-propylnitrosamine (DHPN, in drinking water) during the first 4 weeks (DMBDD treatment), and then d-limonene was administered in the diet, at the dose of 2.0, 1.0 or 0.5%. The maximal tolerable dose was 2.0% under the present conditions. Further groups were treated with DMBDD or 2.0% d-limonene alone as controls. All surviving animals were killed at week 28, and major organs were examined histopathologically for development of preneoplastic and neoplastic lesions. The incidences and/or multiplicities of renal atypical tubules and adenomas were increased in animals fed 2.0% d-limonene. The immunohistochemical reactivity for alpha2u-globulin in the proximal tubules was greater in rats fed d-limonene than in the carcinogen alone group. No enhancing or inhibitory effect was noted for tumor development in other organs. The present results indicate a lack of any chemopreventive effect of d-limonene in any organ of male rats under the present experimental conditions.

1,2-Dimethylhydrazine↗
PubMed1996

New hydrolyzable tannins, shephagenins A and B, from Shepherdia argentea as HIV-1 reverse transcriptase inhibitors.

Two new hydrolyzable tannins, shephagenins A and B, were isolated along with hippophaenin A and strictinin from the leaf extract of Shepherdia argentea, which showed a remarkable inhibitory activity against human immunodeficiency virus (HIV)-1 reverse transcriptase. Their structures, having a gluconic acid core, have been elucidated on the basis of spectroscopic and chemical methods. The inhibitory effect of the leaf extract on HIV-1 reverse transcriptase was found to be due to tannins, and their activities were stronger than that of (-)-epigallocatechin gallate as a positive control.

Antiviral Agents↗
PubMed1995

Flush induced by fluoroquinolones in canine skin.

The flush induced by two fluoroquinolone antibacterial agents, balofloxacin and ofloxacin, was studied in beagle dogs. Intradermal injection of the fluoroquinolones at concentrations above 10(-5) M produced a localized flushed area. The flush responses to fluoroquinolones were inhibited by co-administration with H2-antagonist(s) (ranitidine or cimetidine), but not with H1-antagonist(s) (mepyramine or chlorpheniramine). Similar inhibitory effects of these H2-antagonists were observed for the response to histamine. The flush responses to fluoroquinolones were inhibited by a local pretreatment with compound 48/80 administered to deplete the local stores of mast cell-bound histamine. When the fluoroquinolones were orally administered at a dose of 400 mg/kg, the concentration of histamine in plasma was increased, being accompanied by systemic erythema. These results indicate that the flush induced by fluoroquinolones is mediated by histamine release from canine cutaneous mast cells and H2-receptor stimulation.

Animals↗
PubMed1995

A comparative study of whole-blood platelet aggregation in laboratory animals: its species differences and comparison with turbidimetric method.

We undertook a systematic comparison of whole-blood platelet aggregation concerning species difference of commonly used laboratory animals (rabbits, guinea pigs, rats and dogs), agonist difference (collagen, ADP and platelet activating factor [PAF] and technical difference against a traditional method of turbidimetry. Collagen-induced aggregation with whole-blood aggregometry was less variable among species tested and was similar to the results obtained by turbidimetry, which measures platelet aggregation in citrated plasma. In contrast, whole-blood aggregometry in responses to ADP and PAF showed marked species difference, being different from turbidimetry. Our results provide species difference among laboratory animals and suggest that the modulations of platelet aggregation by other blood elements probably differ in each species and with stimulating agonists.

Animals↗
PubMed1995

Effects of the release of arachidonic acid from 1-ether-linked phospholipids on opsonized-zymosan stimulated rabbit alveolar macrophages.

On rabbit alveolar macrophages prelabeled with double tracers of [3H]arachidonic acid (20:4) for 30 min (short-term labeling) and of [14C]20:4 for 12 h (long-term labeling), the relationship between phospholipid subclasses and the release of 20:4 on stimulation with opsonized-zymosan (OZ) was investigated. Stimulation with 500 micrograms of OZ/ml for 1 h caused a significant decrease in the radioactivity of incorporated [3H]20:4 in all phosphatidylcholine (PC) subclasses of the cells: by 48% in 1-O-alkyl-2-acyl-sn-glycerol-3-phosphocholine (alkylacyl-GPC), and by 24% in 1,2-diacyl-GPC (diacyl-GPC), and slightly in 1-O-alk-1'-enyl-2-acyl-GPC (alkylacyl-GPC). In phosphatidylethanolamine (PE) a significant decrease in the incorporated [3H]20:4 was also observed in the 1,2-diacyl-sn-glycerol-3-phosphoethanolamine (diacyl-GPE, 45%). On the other hand, the radio activity of [14C]20:4 incorporated by long-term labeling into PC decreased significantly, by approximately 40%, in the alkylacyl-GPC and slightly in the alkenylacyl-GPC. In PE, a significant decrease (approximately 32%) in radioactivity of [14C]20:4 was observed only in the alkenylacyl-GPE which incorporated the largest amount of [14C]20:4 among the cellular phospholipids in its labeling and which showed the biggest decrease in [14C]20:4 in the PC and PE subclasses on stimulation with OZ. These results suggest that on OZ stimulation of rabbit alveolar macrophages, PC and PE subclasses involved in the mobilization of 20:4 depend on each 20:4 pool which is extracted in the cells.

Animals↗
PubMed1994

Intracellular receptor-type transcription factor, LasR, contains a highly conserved amphipathic region which precedes the putative helix-turn-helix DNA binding motif.

We have cloned and sequenced the lasR gene, which is involved in the transcriptional activation of several pathogenic factors, from Pseudomonas aeruginosa IFO3455 and PA103. These clones were predicted to be an open reading frame of 239 amino acids as reported for the PAO1 strain. There is only a single base change resulting in an amino acid exchange from M145 (PAO1) to I (IFO3455). PA103 DNA differs with PAO1 DNA in two bases resulting in only a single amino acid substitution from R179 to W. When the IFO3455 LasR was expressed in a PA103 strain which is known to be LasR defective, proteinase gene activation was detected, however, when PA103 LasR was expressed, no enhancement was measurable. From these results, it appears that the amino acid substitution of R179 to W inactivated LasR activity. This substitution is located in the highly conserved sequence found in many transcription factors, including sigma factors, and may disrupt amphipathic alpha-helix, predicted for the 176 to 189 region, which precedes the putative helix-turn-helix DNA binding motif. We presumed that these three helices may contribute to specific DNA binding.

Amino Acid Sequence↗
PubMed1994

Elastase gene expression in non-elastase-producing Pseudomonas aeruginosa strains using novel shuttle vector systems.

In order to determine whether non-elastase-producing strains of Pseudomonas aeruginosa such as N-10, PA103 and IFO3080 can express foreign elastase genes, we introduced elastase genes from P. aeruginosa IFO3455 (elastase-producing) as well as from PA103 and N-10 into non-elastase-producing P. aeruginosa strains. Results suggested that gene expression, secretion, and precursor processing systems of elastase were essentially normal in P. aeruginosa N-10 and IFO3080. Our studies using various elastase genes showed that both the elastase structural gene and 5'-upstream regions of P. aeruginosa PA103 were also normal. This was confirmed by the finding that P. aeruginosa N-10 and IFO3080 which carry the PA103 elastase gene produced elastase. Several deleted or chimeric genes were constructed using the 5'-upstream regions of elastase genes from P. aeruginosa N-10 or PA103 and studies of expression revealed that two individual DNA bases seem to be important in suppressing P. aeruginosa N-10 elastase gene expression. Possible reasons for the lack of elastase expression in these non-elastase-producing strains are discussed.

Base Sequence↗
PubMed1994

Effects of ionic and nonionic contrast media on cardiohemodynamics and quality of radiographic image during canine angiography.

Cardiovascular responses and radiographic image quality during cerebral angiography, aortofemoral angiography and left ventriculography with nonionic ioxilan, iohexol or iopamidol were compared with those of ionic sodium meglumine diatrizoate in pentobarbital anesthetized dogs. Injection of all contrast media caused cardiovascular changes to a greater or lesser degree, e.g., hypotension, bradycardia, tachycardia, a decrease in left ventricular pressure (LVP) and its first derivative (dP/dt), and prolongation of the P-Q and Q-T intervals. Ionic diatrizoate had a greater effect on cardiovascular parameters than nonionic contrast media during angiography in all areas. Moreover, diatrizoate produced cardiac arrhythmias and prominent changes in blood rheology concerned with blood viscosity and deformability of the erythrocyte. The cause of various effects of contrast media seemed to lie mainly in osmolality, viscosity and partially ionic additives. The radiographic image quality of all of the contrast media used was similar, but nonionic ioxilan and iohexol with lower iodine content and low osmolality gave better radio opacity than ionic diatrizoate in cerebral angiography. These results suggested that nonionic contrast media should be recommended as a diagnostic tool for both animals and human patients in poor health.

Angiography↗
PubMed1993

31P and 23Na nuclear magnetic resonance study on forebrain ischemia in rats with shift reagent Dy(TTHA).

31P and 23Na nuclear magnetic resonance (NMR) spectroscopy was employed to study the dynamic changes in intracellular high-energy phosphates and sodium during 15 min of forebrain ischemia and recirculation in in vivo rat brain. In the presence of the shift reagent Dysprosium triethylenetetramine-N,N,N",N",N"',N"'-hexaacetic and [Dy(TTHA)], the sodium peak separated into two peaks, unshifted and shifted. During 15 min of ischemia, the unshifted sodium peak decreased and the shifted sodium peak increased. With recirculation, the unshifted and the shifted sodium peaks returned to the preischemia level within 10 min, but the shifted one increased during 30-60 min. Intracellular high-energy phosphates and intracellular pH (pHi) decreased during 15 min of ischemia and returned to the preischemia levels within 20 min of recirculation. We conclude that the decrease in unshifted sodium peak during ischemia is due to the decrease in subarachnoid sodium and the cellular influx of interstitial sodium would be minimum. The increase in shifted sodium peak during ischemia is considered to be due to the dilatation of cerebral blood vessels and the increase in interstitial sodium which was transported from subarachnoid space.

Journal Article↗