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Biomedical subjects

K Kawano

Publications and source records attributed to K Kawano.

At least 55 records · Page 3Linked to original sources
PubMed2001

A study of quality assessment in clinical microbiology performance of independent laboratories in Tokyo: 18-year participation in the Tokyo Metropolitan Government External Quality Assessment Program.

We evaluated the performance of independent microbiology laboratories in Tokyo over an 18-year period of participation in the external quality assessment (EQA) program, and we estimated the impact of the EQA program. The study design was a longitudinal retrospective analysis of performance, including isolation, identification, and antimicrobial susceptibility testing of bacteria from simulated patients' samples, in "open" surveys compared with "blind" surveys. Independent microbiology laboratories, licensed by the Tokyo Metropolitan Government, have been subject to mandatory evaluation by the EQA program since 1982. Survey reports, correspondence, annual guidance meetings, and inspections are used as quality improvement strategies. The performance for identification in "blind" surveys was significantly worse than that in "open" surveys (P < 0.001). Poorly performing laboratories had common features, including inadequate supervision by physicians and lack of familiarity with the impact of variations on the use of the standards. However, there were improvements in the performance of identification of some pathogens. The performance of susceptibility testing has not yet reached the relatively high level seen for identification. Some of the smaller laboratories have been gradually acquired by commercial chains operating outside Tokyo. The EQA program has established a role both in regard to laboratory improvement and as an educational tool. However, the program lags behind these of other developed countries in regard to the practical sciences. The main problems in regard to laboratory improvements are a shortage of human resources in clinical microbiology, lack of standardization of laboratory methods, and the pressures of financial constraints in the Japanese medical insurance system.

Data Collection↗
PubMed2001

Expression of a novel RNA-splicing factor, RA301/Tra2beta, in vascular lesions and its role in smooth muscle cell proliferation.

RA301/Tra2beta, a sequence-specific RNA-binding protein, was first cloned as a stress molecule in re-oxygenated astrocytes. In human vascular tissues, we have found enhanced RA301/Tra2beta expression in coronary artery with intimal thickening, and atherosclerotic aorta. Balloon injury to the rat carotid artery induced RA301/Tra2beta transcripts followed by expression of the antigen, which was detected in medial and neointimal vascular smooth muscle cells (VSMCs). In cultured VSMCs, hypoxia/re-oxygenation caused induction of RA301/Tra2beta and was accompanied by cell proliferation, both of which were blocked by the addition of either diphenyl iodonium, a NADPH oxidase inhibitor, PD98059, a mitogen-activated protein kinase kinase inhibitor, or antisense oligonucleotide for RA301/Tra2beta. Consistent with a link between RA301/Tra2beta and cell proliferation, platelet-derived growth factor also induced expression of RA301/Tra2beta in cultured VSMCS: These data suggest a possible role for RA301/Tra2beta in the regulation of VSMC proliferation, especially in the setting of hypoxia/re-oxygenation-induced cell stress.

Adolescent↗
PubMed2001

Thermal stability and enzymatic activity of a smaller lysozyme from silk moth (Bombyx mori).

Bombyx mori lysozyme is 10 amino acids shorter than hen egg-white lysozyme, which is a typical c-type lysozyme. It was expressed by using the methylotrophic yeast Pichia pastoris. The thermal stability and the enzymatic activity of the Bombyx mori lysozyme were estimated and compared with those of human and hen egg-white lysozymes. The denaturation temperature was 17-26 degrees C lower than those of human and hen egg-white lysozymes. Further, the enthalpy change and the heat capacity change for unfolding were smaller than those of human lysozyme. It was also confirmed that the stability against guanidine hydrochloride was lower than those of the other two lysozymes. The enzymatic activity toward a simple synthetic substrate was measured and compared with those of human and hen egg-white lysozymes. The B-F binding mode was obviously dominant, although the A-E binding mode was preferred in human and hen egg-white lysozymes.

Acetylglucosamine↗
PubMed2001

Apolipoprotein B secretion and atherosclerosis are decreased in mice with phospholipid-transfer protein deficiency.

Increased secretion and levels of ApoB-containing lipoproteins (BLp) commonly occur in familial hyperlipidemia, obesity and diabetes. The plasma phospholipid-transfer protein (PLTP) is known to mediate transfer of phospholipids between BLp and HDL during their intravascular metabolism. To address a possible role of PLTP in dyslipidemia and atherogenesis, we bred mice deficient in the gene encoding PLTP (PLTP-deficient mice) using different hyperlipidemic mouse strains. In ApoB-transgenic and ApoE-deficient backgrounds, PLTP deficiency resulted in reduced production and levels of BLp and markedly decreased atherosclerosis. BLp secretion was diminished in hepatocytes from ApoB-transgenic PLTP-deficient mice, a defect that was corrected when PLTP was reintroduced in adenovirus. The studies reveal a major, unexpected role of PLTP in regulating the secretion of BLp and identify PLTP as a therapeutic target.

Animals↗
PubMed2001

Acute effects of cigarette smoking on platelet-dependent thrombin generation.

AIMS: Thrombin is an important factor in the pathogenesis of thrombotic diseases. To clarify whether smoking has an effect in platelet-dependent thrombogenesis, we studied the acute effects of smoking on platelet-dependent thrombin level in smokers. METHODS AND RESULTS: Subjects consisted of ten smokers and nine non-smokers. Platelet-dependent thrombin level measured after overnight fasting was greater in smokers than in non-smokers (smokers vs non-smokers, 121 +/- 47 vs 56 +/- 5 mIU. ml(-1), P < 0.01). When subjects in the smokers group smoked two cigarettes containing 0.9 mg of nicotine per cigarette, platelet-dependent thrombin levels showed a transient three-fold increase in blood samples obtained immediately after smoking (365+/-76 mIU. ml(-1), P < 0.001). Thrombin levels in the blood samples obtained 10 min and 30 min after smoking were less than that in the samples obtained immediately after smoking ceased, but were not significantly different from those in the samples obtained before smoking. Blood nicotine level increased significantly immediately after smoking (P < 0.001), and plasma protein C activity decreased significantly 30 min after smoking (P < 0.05). When nicotine or cotinine was added to the platelet-rich plasma of non-smokers ex vivo, the platelet-dependent thrombin level increased significantly (P < 0.002). CONCLUSION: Platelet-dependent thrombin level is enhanced in smokers, even when not smoking, when compared with non-smokers and increases immediately after smoking. Increases in nicotine and cotinine levels caused by smoking induced a prothrombotic state in smokers via increased platelet-dependent thrombogenesis.

Adult↗
PubMed2001

Construction of an expression system of insect lysozyme lacking thermal stability: the effect of selection of signal sequence on level of expression in the Pichia pastoris expression system.

Expression systems of human and silkworm lysozymes were constructed using the methylotrophic yeast Pichia pastoris as a host. The leader sequence and its prepro peptide of alpha-factor (a peptide pheromone derived from yeast) and the native signal sequences of these lysozymes, were used as secretion signals. When the alpha-factor leader is used as the signal sequence, human lysozyme is secreted at a much higher level than is silkworm lysozyme. On the other hand, silkworm lysozyme, when its native signal is used, is secreted more efficiently than human lysozyme. Therefore, we expected that human lysozyme cDNA with a silkworm native signal would be secreted more efficiently than human lysozyme with its native signal. However, its level of expression was not increased. This result indicates that the native signal of silkworm lysozyme does not promote the secretion of the lysozyme, but rather alpha-factor leader inhibits the secretion. Silkworm lysozyme with the alpha-factor leader is so unstable that it could be easily attacked by some proteases and our findings suggest that the level of expression of heterologous protein with signal peptides and its stability are greatly affected by the selection of the appropriate secretion signal sequence.

Amino Acid Sequence↗
PubMed2001

Postprandial neuronal activation in the nucleus of the solitary tract is partly mediated by CCK-A receptors.

CCK-A receptors and neurons of the nucleus of the solitary tract (NTS) are involved in the regulation of food intake, and in rats, there is evidence for involvement of an intestinal vagal afferent pathway. Studies investigating the role of CCK-A receptors in activation of NTS neurons using highly selective CCK-A receptor agonists and antagonists have yielded conflicting data. In the present study, we investigated CCK-induced and postprandial activation of NTS neurons, together with food intake studies, in CCK-A receptor-deficient Otsuka Long-Evans Tokushima fatty (OLETF) rats. Activated NTS neurons were detected using immunohistological staining for c-Fos protein. Exogenous CCK increased the number of c-Fos protein-positive cells in the NTS of Sprague-Dawley and CCK-A receptor-intact Long-Evans Tokushima Otsuka (LETO) rats but had no effect in CCK-A receptor-deficient OLETF rats. Food intake-induced c-Fos protein expression in NTS neurons was significantly reduced in CCK-A receptor-deficient OLETF rats compared with Sprague-Dawley or LETO rats. Postprandial c-Fos protein expression in the NTS was also significantly decreased after pretreatment with the CCK-A receptor antagonist MK329 after both short- and long-term fasting periods. Exogenous CCK decreased cumulative food intake in Sprague-Dawley and LETO rats but not in OLETF rats. These data demonstrate that CCK-A receptors are involved in the CCK- and food-induced c-Fos protein expression in the NTS. Taken together with the results of the food intake studies, this suggests that activation of CCK-A receptors is involved in the postprandial activation of NTS neurons and in the regulation of food intake.

Animals↗
PubMed2001

Single-unit activity in cortical area MST associated with disparity-vergence eye movements: evidence for population coding.

Single-unit discharges were recorded in the medial superior temporal area (MST) of five behaving monkeys. Brief (230-ms) horizontal disparity steps were applied to large correlated or anticorrelated random-dot patterns (in which the dots had the same or opposite contrast, respectively, at the two eyes), eliciting vergence eye movements at short latencies [65.8 +/- 4.5 (SD) ms]. Disparity tuning curves, describing the dependence of the initial vergence responses (measured over the period 50-110 ms after the step) on the magnitude of the steps, resembled the derivative of a Gaussian, the curves obtained with correlated and anticorrelated patterns having opposite sign. Cells with disparity-related activity were isolated using correlated stimuli, and disparity tuning curves describing the dependence of these initial neuronal responses (measured over the period of 40-100 ms) on the magnitude of the disparity step were constructed (n = 102 cells). Using objective criteria and the fuzzy c-means clustering algorithm, disparity tuning curves were sorted into four groups based on their shapes. A post hoc comparison indicated that these four groups had features in common with four of the classes of disparity-selective neurons in striate cortex, but three of the four groups appeared to be part of a continuum. Most of the data were obtained from two monkeys, and when the disparity tuning curves of all the individual neurons recorded from either monkey were summed together, they fitted the disparity tuning curve for that same animal's vergence responses remarkably well (r(2): 0.93, 0.98). Fifty-six of the neurons recorded from these two monkeys were also tested with anticorrelated patterns, and all showed significant modulation of their activity (P < 0.005, 1-way ANOVA). Further, when all of the disparity tuning curves obtained with these patterns from either monkey were summed together, they too fitted the disparity tuning curve for that same animal's vergence responses very well (r(2): 0.95, 0.96). Indeed, the summed activity even reproduced idiosyncratic differences in the vergence responses of the two monkeys. Based on these and other observations on the temporal coding of events, we hypothesize that the magnitude, direction, and time course of the initial vergence velocity responses associated with disparity steps applied to large patterns are all encoded in the summed activity of the disparity-sensitive cells in MST. Latency data suggest that this activity in MST occurs early enough to play an active role in the generation of vergence eye movements at short latencies.

Algorithms↗
PubMed2001

Change in neuronal firing patterns in the process of motor command generation for the ocular following response.

To explore the process of motor command generation for the ocular following response, we recorded the activity of single neurons in the medial superior temporal (MST) area of the cortex, the dorsolateral pontine nucleus (DLPN), and the ventral paraflocculus (VPFL) of the cerebellum of alert monkeys during ocular following elicited by sudden movements of a large-field pattern. Using second-order linear-regression models, we analyzed the quantitative relationships between neuronal firing frequency patterns and eye movements or retinal errors specified by three parameters (position, velocity, and acceleration). We first attempted to reconstruct the temporal waveform of each neuronal response to each visual stimulus and computed the coefficients for each parameter using the least-square error method for each stimulus condition. The temporal firing patterns were generally well reconstructed [coefficient of determination index (CD) > 0.7] from either the retinal error or the associated ocular following response. In the MST and DLPN datasets, however, the fit with the retinal error model was generally better than with the eye-movement model, and the estimated coefficients of acceleration and velocity ranged widely, indicating that temporal patterns in these regions showed considerable diversity. The acceleration component is greater in MST and DLPN than in VPFL, suggesting that an integration occurs in this pathway. When we determined how well the temporal patterns of the neuronal responses of a given cell could be reconstructed for all visual stimuli using a single set of coefficients, good fits were found only for Purkinje cells (P- cells) in the VPFL using the eye-movement model. In these cases, the coefficients of acceleration and velocity for each cell were similar, and the mean ratio of the acceleration and velocity coefficients was close to that of motor neurons. These results indicate that individual MST and DLPN neurons are each encoding some selective aspects of the sensory stimulus (visual motion), whereas the P-cells in VPFL are encoding the complete dynamic command signals for the associated motor response (ocular following). We conclude that the sensory-to-motor transformation for the ocular following response occurs at the P-cells in VPFL.

Animals↗
PubMed2001

Platelet-dependent thrombin generation in patients with unstable angina pectoris.

Platelet-dependent thrombin generation was assessed during both unstable and stable periods in 59 patients with unstable angina and at rest in 31 healthy controls. Thrombin generation during the unstable period was significantly greater than that at rest in the healthy control group (p < 0.0001) and that during the stable period (p < 0.0001). Changes in thrombin generation were related to the time after onset of unstable angina, not to degree of improvement in the severity of coronary stenosis.

Adult↗
PubMed2001

TMC-69, a new antitumor antibiotic with Cdc25A inhibitory activity, produced by Chrysosporium sp. TC1068. Taxonomy, fermentation and biological activities.

A new antibiotic designated TMC-69 has been isolated from the fermentation broth of a fungal strain Chrysosporium sp. TC 1068. TMC-69 exhibited moderate in vitro cytotoxic activity. TMC-69-6H, a derivative of TMC-69 prepared by hydrogenation, possessed more potent in vitro cytotoxicity than TMC-69, and exhibited in vivo antitumor activity against murine P388 leukemia and B16 melanoma. TMC-69-6H was found to specifically inhibit Cdc25A and B phosphatases.

Animals↗
PubMed2001

TMC-205 a new transcriptional up-regulator of SV40 promoter produced by an unidentified fungus. Fermentation, isolation, physico-chemical properties, structural determination and biological activities.

A new transcriptional up-regulator designated TMC-205 was discovered from the fermentation broth of an unidentified fungal strain TC 1630 by using an SV40 promoter-luciferase reporter assay. Based on spectroscopic analyses, its structure was determined to be (E)-6-(3-methyl-1,3-butadienyl)- H-indole-3-carboxylic acid. Expression of the luciferase activity was activated ca. 2-, 4-, and 6-fold by 1, 10, and 100 microM TMC-205, respectively. TMC-205 activated the transcriptional activity in a manner dependent on the presence of the enhancer element of SV40 in its promoter region.

Chemical Phenomena↗
PubMed2001

[Intracameral suturing technique using the Kawano cannula].

BACKGROUND: Intracameral suturing procedures are often so difficult that new techniques need to be devised. CASE: A case of photophobia caused by the pupillary distortion after anterior chamber lens implantation in cataract surgery with vitreous loss. METHODS AND RESULTS: In contrast to use of the healon cannula, pupilloplasty was more easily and safely performed using the Kawano irrigation cannula (M-91, Inami, Tokyo) by supporting and/or pressing the iris with the wide, flat distal end of the instrument, and also by inserting the needle end into the cannula through the large created port. CONCLUSION: The Kawano irrigation cannula is a safe and useful tool in intraocular suturing procedures.

Aged↗
PubMed2001

[The relationship of serum mitochondrial creatine kinase and rotavirus gastroenteritis in pediatric patients].

The objective of this study was to investigate the relationship between serum mitochondrial creatine kinase(mCK) and rotavirus gastroenteritis in pediatric patients. Stool and serum specimens were simultaneously collected from 45 patients(25 males and 20 females) with suspected rotavirus gastroenteritis from January to December 1998. Stool specimens were tested by rotavirus latex agglutination assay. Fourteen patients(10 males, 4 females) were proved as positive, and peak season was in winter and early spring(7 positive cases in March). Six of the 14 were younger than one and 7 were between one and two. Total serum CK activity was measured by The Japan Society of Clinical Chemistry (JSCC) recommended method, and mCK activity was calculated from mCK fraction % obtained by CK isoenzyme electrophoresis. Patients' mCK activities were as follows, rotavirus antigen positive patients(n = 14): 60.0 +/- 20.6 U/l and rotavirus antigen negative patients(n = 31): 7.2 +/- 5.5 U/l. Significant difference was observed between rotavirus antigen positive group and rotavirus antigen negative group(p < 0.01), and control children group(n = 105): 7.1 +/- 2.9 U/l, (p < 0.01). The clinical implications and mechanisms of increased serum mCK activity are unclear. It is known that histological study of the small intestine from rotavirus gastroenteritis patients reveal shortened villi and mononuclear cell infiltration of the lamia propria; electron microscopy shows mitochondrial swelling and sparse irregular microvilli. Elevated serum mCK level of rotavirus gastroenteritis patient may therefore reflect diffused intestinal epithelial cell damage.

Child, Preschool↗
PubMed2001

[Renal metastasis originating from pulmonary carcinoma: a case report].

A 61-year-old woman, who had undergone total right pneumonectomy 22 months before due to lung cancer (adenosquamous cell carcinoma) was admitted for macroscopic hematuria. Abdominal CT showed two renal tumors in the right kidney. Right radical nephrectomy was performed, because no imaging study showed any other metastasis. Pathological examination revealed adenosquamous cell carcinoma, which was the same pathology as the lung cancer had been. She died of the left lung metastasis 24 months after right radical nephrectomy. Her prognosis was thought to have been prolonged by the operation of right radical nephrectomy.

Carcinoma, Adenosquamous↗
PubMed2001

[Quality control survey implemented by Japan Medical Association and standardization of external quality assessment in Japan].

International Final Draft on quality management of medical laboratory by International Organization for Standardization (ISO) will be published soon. According to this draft, the accreditation of the laboratories should be given by the third party on the basis of objective matter, and the external quality control survey results is thought to be the most important indices for the accreditation. Although variety of external quality control surveys are now implementing in Japan, most of those surveys are done only once a year. Therefore, we could not evaluate the laboratories performance by any of those survey results. If those quality control surveys are done with the standardized system, summative results from different survey could give us fair evaluation on each participating laboratories. Japan Medical Association (JMA) is now making final draft on standardized method for quality assessment system with the consensus between the JMA, Japanese Society of Laboratory Medicine (JSLM, former Japan Society of Clinical Pathology), Japanese Association of Laboratory Medical Technologists (JALMT) and Japan Registered Clinical Laboratories Association (JRCLA). When this quality assessment system actually starts, Japanese people may receive great benefit from the laboratory tests.

Clinical Laboratory Techniques↗