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Biomedical subjects

M Kawamura

Publications and source records attributed to M Kawamura.

At least 55 records · Page 3Linked to original sources

Novel mutations in ABCA1 gene in Japanese patients with Tangier disease and familial high density lipoprotein deficiency with coronary heart disease.

Mutations in the ATP-binding cassette transporter 1 (ABCA1) gene have been recently identified as the molecular defect in Tangier disease (TD) and familial high density lipoprotein deficiency (FHA). We here report novel mutations in the ABCA1 gene in two sisters from a Japanese family with TD who have been described previously (S. Ohtaki, H. Nakagawa, N. Kida, H. Nakamura, K. Tsuda, S. Yokoyama, T. Yamamura, S. Tajima, A. Yamamoto, Atherosclerosis 49 (1983)) and a family with FHA. Both probands of TD and FHA developed coronary heart disease. Sequence analysis of the ABCA1 gene from the patients with TD revealed a homozygous G to A transition at nucleotide 3805 of the cDNA resulting in the substitution of Asp 1229 with Asn in exon 27, and a C to T at nucleotide 6181 resulting in the substitution of Arg 2021 with Trp in exon 47. Sequence analysis of the ABCA1 gene from the FHA patient revealed a homozygous 4 bp CGCC deletion from nucleotide 3787 to 3790 resulting in premature termination by frameshift at codon 1224. These mutations were confirmed by restriction digestion analysis, and were not found in 141 control subjects. Our findings indicate that mutations in the ABCA1 gene are associated with TD as well as FHA.

ATP Binding Cassette Transporter 1↗

Potent dibasic GPIIb/IIIa antagonists with reduced prolongation of bleeding time: synthesis and pharmacological evaluation of 2-oxopiperazine derivatives.

A series of 2-oxopiperazine derivatives, possessing basic moieties at the 3- and the 4-positions, were synthesized and evaluated for their abilities to inhibit platelet aggregation and for their effects on bleeding time. Among the compounds, 2-[(3S)-4-[2-[(4-guanidinobenzoyl)amino]acetyl]-3-[3-[(4-guanidinobenzoyl)amino]propyl]-2-oxopiperazinyl]acetic acid (12c) showed a potent inhibitory effect on platelet aggregation and good dissociation between the efficacy and the bleeding side effect. Intravenous infusion of compound 12c at 1.6 microg/mL/min completely prevented arterial thrombus formation induced by endothelial injury in guinea pigs. The dose of 12c that prolonged the bleeding time to three times the control value was 5.8 microg/mL/min. These results suggest that compound 12c might be useful in the clinical treatment of thrombotic diseases, and we selected 12c (TAK-024) as a candidate for the clinical trials.

Adenosine Diphosphate↗

Precise measurement of the positive muon anomalous magnetic moment.

A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.

Journal Article↗

The functional unit of Na,K-ATPase is a monomeric alphabeta protomer.

The ouabain-resistant and ouabain-sensitive alpha-subunit cRNAs in various molar ratios were injected into Xenopus oocytes together with cRNA for the beta-subunit. The ouabain-resistant ATPase activity, as well as ouabain-resistant Rb+ uptake, of the injected oocytes increased linearly with increasing the amount of cRNA for the ouabain-resistant alpha-subunit. When a functionless mutant was used instead of the ouabain-sensitive alpha-subunit, similar results were obtained in ATPase activity and Rb+ uptake. These results indicate that a monomeric alphabeta protomer is a functional unit of membrane-bound Na,K-ATPase, even if the enzyme exists structurally as a diprotomer or higher oligomers in membranes.

Animals↗

A cross-cultural comparison of dental health attitudes and behaviour among freshman dental students in Japan, Hong Kong and West China.

OBJECTIVE: To clarify the differences in dental health attitudes/behaviour among freshman dental students. DESIGN: Cross-cultural differences. SETTING: Japan, Hong Kong and West China. PARTICIPANTS AND METHODS: The original version of the Hiroshima University-Dental Behavioural Inventory (HU-DBI) was written in Japanese. After testing the validity of both English and Chinese versions, the original version of the HU-DBI was administered to 58 freshman Japanese dental students, the English version to 43 Hong Kong Chinese peers and the Chinese version to 39 West Chinese peers. RESULTS: Significant cultural differences were found for 16 items out of 20. The most striking result was that the Japanese students were more likely to have used a dye to see how clean their teeth were, compared to their Chinese peers (P<0.001). The Chinese students were less likely to have a belief that they could clean their teeth well without using toothpaste (P<0.001), whereas higher percentages of the Chinese students worried about having bad breath (P<0.001). A higher percentage of the Hong Kong students reported that they regularly checked their teeth in a mirror than did their West Chinese or Japanese peers (P<0.05). CONCLUSIONS: There were considerable differences in dental health attitudes/behaviour among freshman dental students in the three cultural groups.

Adolescent↗

Analysis of 20-year follow-up study of LVP regimen for adult acute lymphoblastic leukemia.

In an attempt to develop a new intensive chemotherapy for adults with untreated acute lymphoblastic leukemia (ALL), 3 sequential programs were designed for 62 patients (age range, 15 to 74 years; median age, 32 years) consisting of the LVP-79 (1979-1984, 27 patients), LVP-85 (1984-1986, 14 patients), and LVP-87 (1987-1989, 21 patients) regimens. The influence of clinical and biologic characteristics on the patient outcome was also examined. L-asparaginase (L-asp), vincristine, and prednisolone, defined collectively as LVP, were administered for induction chemotherapy in all protocols. After achieving complete remission (CR), patients underwent 2 years of multi-agent consolidation, intensification, and maintenance therapy consisting of various combinations. No significant differences were noted between the 3 groups regarding CR rate or survival. In total, 47 of 62 patients (75.8%) achieved CR. The median overall survival (OS) and median CR durations were 550 days and 341 days, respectively. Overall, the estimated survival rate at 20 years was 18.1%. The disease-free survival rate at 20 years was 26.2%. According to univariate analysis, the most favorable pretreatment characteristic for achieving CR was age. A younger age (<40 years of age), platelet count >30 x 10(9)/L, having L1 morphology (French-American-British [FAB]classification subtype), female sex, and the absence of chromosomal abnormalities also helped improve survival rate. According to multivariate analysis, presence of Ph chromosome was found to be a major influencing factor for OS. Although higher doses of L-asp were administered than those used in previous studies, the adverse effect of L-asp was rarely identified. Therefore, it should be considered one of the key drugs for treatment of adult ALL. Further strategies still need to be developed to obtain better survival in adult ALL.

Adolescent↗

Transient spontaneous regression of aggressive non-Hodgkin's lymphoma confined to the adrenal glands.

A 72-year-old-man with night sweats and a low-grade fever was found to have bilateral adrenal enlargement associated with incipient adrenal insufficiency. Without any intervention, these adrenal lesions regressed spontaneously, accompanied by disappearance of clinical symptoms. Seven months later, however, the lesions became enlarged and exceeded their initial size while remaining confined to the adrenals, associated with reappearance of nights sweats and overt adrenal insufficiency. Upon unilateral laparoscopic adrenalectomy, the lesion proved histopathologically to be diffuse large B cell non-Hodgkin's lymphoma (NHL). After contralateral laparoscopic adrenalectomy and adjuvant chemotherapy, the patient remains alive with no recurrence at 26 months. Treatment with bilateral adrenalectomy and chemotherapy is effective for aggressive NHL confined to bilateral adrenal glands. A transient clinical improvement without treatment was considered to be due to a spontaneous regression of NHL, although we could not confirm the histological results before the regression. Such tumor behavior showing spontaneous regression in spite of aggressive histology may also be related to the favorable outcome, even though regression was transient.

Adrenal Gland Neoplasms↗

Sindbis viral-mediated expression of Ca2+-permeable AMPA receptors at hippocampal CA1 synapses and induction of NMDA receptor-independent long-term potentiation.

Gene manipulation in order to artificially express a particular gene in neurons in the central nervous system is a powerful tool for the analysis of brain function. Sindbis viral vectors have been developed to express high levels of foreign genes in postmitotic brain neurons with little transfection of glial cells. In this study, we expressed the gene encoding the unedited GluR2 (GluR-B) subunit of the AMPA-type glutamate receptor that forms inwardly rectifying and Ca2+-permeable channels, in rat CA1 hippocampal neurons in slice cultures using Sindbis viral vectors. The pyramidal cell layer of the CA1 region was injected with recombinant Sindbis viruses encoding both enhanced green fluorescent protein (GFP) and unedited GluR2. The GFP fluorescence from CA1 neurons could be detected as early as 6 h and reached a maximal level about 48 h postinfection. The inwardly rectifying and Ca2+-permeable AMPA receptors were expressed in most CA1 pyramidal cells expressing GFP. These AMPA receptors expressed by gene transfer were involved in fast excitatory neurotransmission elicited by electrical stimulation of the Schaffer collaterals in the stratum radiatum. Tetanic stimulation of Schaffer collaterals induced NMDA receptor-independent, long-term potentiation due to Ca2+ influx through the newly expressed AMPA receptors in the area densely stained with GFP. Thus, the combined use of Sindbis viral vectors with the GFP reporter allowed physiological examination of the roles of a specific gene product in synaptic function in well-characterized brain neurons.

Animals↗

Dimensional stability and weight changes of tissue conditioners.

The dimensional stability of tissue conditioners characterizes the ability of the materials to yield accurate functional impressions of oral mucosa. This study evaluated the linear dimensional changes with time of six tissue conditioners (COE Comfort, FITT, GC Soft-Liner, Hydro-Cast, SR-Ivoseal and Visco-Gel) using a travelling microscope, and relationship between these changes and weight changes. The absorption and solubility of these materials were also determined. The percentage changes in dimension and weight in water storage were measured at 2 (baseline), 8 and 24 h, and 2, 4, 7, 14 and 21 days after specimen preparation. All materials except SR-Ivoseal exhibited shrinkage and weight loss during water storage, whilst SR-Ivoseal exhibited expansion and an increase in weight. The percentage solubility for all materials except SR-Ivoseal was higher than the percentage absorption. A positive linear relationship was found between the percentage changes in linear dimension and those in weight (r=0.797 - 0.986, P < 0.05). Water absorption and solubility of the materials were found to be associated with dimensional changes. The results suggest that the period recommended for forming functional impressions would be 24 h after insertion in the mouth. In addition, it is important to select tissue conditioners suitable for functional impressions because of the wide ranges of dimensional stability among the materials.

Absorption↗

Effect of age on renal functional and orthostatic vascular response in healthy men.

1. Few studies have been reported concerning the effect of ageing on renal functional and vascular responses to various stresses during ordinary life. In the present study, we examined the effect of age on changes in renal sodium handling and renal vascular resistance (RVR) in response to standing from a supine position in subjects with normal renal function. 2. We selected 43 healthy males in the second through to the seventh decade of life and gave them a constant dietary sodium intake before the study period. Renal function was estimated by standard clearance methods with the subject in a state of euvolaemia. 3. The mean daily urinary excretion of sodium was 236 +/- 22 mEq. Standing from a supine position was associated with significant decreases (P < 0.0001) in creatinine clearance (from 125 +/- 18 to 117 +/- 19 mL/min per 1.73 m2), sodium excretion (from 178 +/- 29 to 97 +/- 23 microEq/min) and fractional excretion of sodium (from 1.02 +/- 0.19 to 0.60 +/- 0.13%). A significant increase (P < 0.0001) in the RVR index (from 0.11 +/- 0.03 to 0.14 +/- 0.04 units) was noted. Univariate analysis indicated that while the change in RVR associated with standing was significantly diminished (P < 0.05) in older subjects, orthostatic changes in other parameters associated with standing were minimally influenced by age. 4. In conclusion, although the renal vascular response is impaired in advanced age, the renal functional response to orthostasis is otherwise maintained in healthy elderly subjects under conditions of normal sodium intake and clinical euvolaemia.

Age Factors↗

Development of a new hollow fiber silicone membrane oxygenator: in vitro study.

An experimental silicone hollow fiber membrane oxygenator for long-term extracorporeal membrane oxygenation (ECMO) was developed in our laboratory using an ultrathin silicone hollow fiber. However, the marginal gas transfer performances and a high-pressure drop in some cases were demonstrated in the initial models. In order to improve performance the following features were incorporated in the most recent oxygenator model: increasing the fiber length and total surface area, decreasing the packing density, and modifying the flow distributor. The aim of this study was to evaluate the gas transfer performances and biocompatibility of this newly improved model with in vitro experiments. According to the established method in our laboratory, in vitro studies were performed using fresh bovine blood. Gas transfer performance tests were performed at a blood flow rate of 0.5 to 6 L/min and a V/Q ratio (V = gas flow rate, Q = blood flow rate) of 2 and 3. Hemolysis tests were performed at a blood flow rate of 1 and 5 L/min. Blood pressure drop was also measured. At a blood flow rate of 1 L/min and V/Q = 3, the O2 and CO2 gas transfer rates were 72.45 +/- 1.24 and 39.87 +/- 2.92 ml/min, respectively. At a blood flow rate of 2 L/min and V/Q = 3, the O2 and CO2 gas transfer rates were 128.83 +/- 1.09 and 47.49 +/- 5.11 ml/min. Clearly, these data were superior to those obtained with previous models. As for the pressure drop and hemolytic performance, remarkable improvements were also demonstrated. These data indicate that this newly improved oxygenator is superior to the previous model and may be clinically acceptable for long-term ECMO application.

Animals↗

Hemodynamic analysis of esophageal varices using color Doppler endoscopic ultrasonography to predict recurrence after endoscopic treatment.

BACKGROUND AND STUDY AIMS: The time to recurrence of esophageal varices may vary greatly between patients even after the same endoscopic therapy. To clarify the factors which contribute to recurrence after endoscopic treatment, the hemodynamics and morphology of the left gastric vein (LGV) were investigated using color Doppler endoscopic ultrasonography (EUS). PATIENTS AND METHODS: A total of 31 patients with high-risk esophageal varices underwent color Doppler-EUS before receiving endoscopic variceal ligation and endoscopic injection sclerotherapy combined therapy. Endoscopic examination was performed every 3 months after the treatment to evaluate recurrence of varices. RESULTS: A total of 18 patients responded to the therapy, while 13 patients did not respond, and had recurrence within 12 months. The hepatofugal flow velocity in the LGV trunk was significantly lower in the responders (9.9 vs. 13.9 cm/sec; P = 0.02). The branch pattern of the LGV was categorized into three groups: anterior branch dominant, posterior branch dominant, and no-dominant type. The incidence of the anterior branch dominant type was significantly less in responders (17 vs. 70 %; P = 0.01). There was no significant difference in the LGV trunk diameter and the size of the paraesophageal vein between the two groups. CONCLUSION: Risk factors for recurrence can be analyzed in detail using color Doppler-EUS. Further investigation using color Doppler-EUS may enable us to select the optimal way to treat esophageal varices to prevent recurrence.

Adult↗

Low power diode laser treatment using indocyanine green for eradication of esophageal varices.

BACKGROUND AND STUDY AIMS: Endoscopic variceal ligation (EVL) is an alternative to sclerotherapy for the treatment of esophageal varices, but is associated with higher rates of recurrence and subsequent bleeding than sclerotherapy. To prevent recurrence of varices after EVL, we have developed a low-dose diode laser therapy combined with the injection of indocyanine green, which allows enhanced tissue absorption of the laser beam selectively around varices. In this study we investigated the efficacy and safety of this technique. PATIENTS AND METHODS: Eight patients with F2 or F3 esophageal varices were enrolled. At 1 week after EVL, indocyanine green solution (1 mg/ml) was injected submucosally around the remaining varices. A diode laser (power 10 watts) was applied to the surface from the esophagogastric junction to 5 cm above it. The spot size was kept to 5 mm in diameter. RESULTS: Laser irradiation was performed safely, without bleeding from the varices, or perforation. There were no major complications. Endoscopy 1 month later showed F0 forms in seven patients, F1 in one patient, and no red color sign in any patient. No recurrence of varices has been observed in any of the patients during the follow-up period of at least 12 months. CONCLUSION: This technique may provide a simple, safe and effective procedure, as an additional treatment to EVL, for the prevention of recurrence of esophageal varices.

Adult↗

The anesthetic interaction between adenosine triphosphate and N-methyl-D-aspartate receptor antagonists in the rat.

Modulation of synaptic neurotransmission through the ligand-gated ion channel is probably involved in the mechanisms of analgesic and anesthetic actions. In the central nervous system, adenosine triphosphate and glutamate are fast excitatory neurotransmitters through their effects on P2X and N-methyl-D-aspartate (NMDA) receptors respectively. To examine the anesthetic interaction between adenosine triphosphate and NMDA receptor antagonists, we studied the effect of intracerebroventricular administration of P2 and/or NMDA antagonists on the minimum alveolar concentration (MAC) of sevoflurane in rats. Intracerebro- ventricular administration of phosphonopentanoic acid azophenyl-2',4'-disulfonate and D (-)-2-anino-5-phophonopentanoic acid, P2 and NMDA antagonists, significantly reduced the MAC of sevoflurane. The reduction of the MAC by both phosphonopentanoic acid azophenyl-2',4'-disulfonate and D (-)-2-anino-5-phophonopentanoic acid was dose-dependent. The effect of coadministration of both antagonists was additive in the reduction of sevoflurane minimum alveolar concentration. These results suggest that P2 and NMDA receptors mediate nociceptive/anesthetic processing as inhibition of these receptors resulted in analgesic and anesthetic effects. However the pathway mediated through each receptor may be different postsynaptically and/or one of these presynaptic receptors may modulate the neurotransmitter release of the other.

2-Amino-5-phosphonovalerate↗

[Serovar-distribution and drug-resistance of Salmonella strains isolated from domestic and imported cases during 1995-1999 in Tokyo].

A total of 2,277 non-typhoidal Salmonella strains consisting of 1,807 domestic strains and 470 imported strains isolated from sporadic cases during 1995-1999 in Tokyo, were examined regarding their serovar-distibution and their drug-resistance. The serological typing results showed that the domestic strains were classified into 17 O-groups and 99 serovars, and the imported strains were classified into 12 O-groups and 58 serovars. Among the serovars identified, Salmonella serovar Enteritidis (S. Enteritidis), S. Thompson, S. Hadar, S. Infantis, S. Typhimurium, and S. Litchfield were predominant in the domestic strains, whereas S. Enteritidis, S. Anatum, S. Hadar, and S. Weltevreden were predominant in the imported strains. The drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM, and NFLX) showed that 34.0% of the domestic strains and 33.0% of the imported strains were resistant to any of the drugs examined. The serovars of a high resistant rate during this period were S. Blockley (100%), S. Hadar (96.6%), S. Typhimurium (63.6%), and S. Enteritidis (62.2%) in the domestic strains and S. Blockley (100%), S. Hadar (97.1%), S. Rissen (88.9%), S. Emek (83.3%), S. Panama (83.3%), and S. Typhimurium (77.8%) in the imported strains. Drug-resistance patterns of the resistant isolates varied to 60 types. Prevalent patterns recognized were SM, TC.SM, TC, TC.SM.KM.ST, TC.SM.KM, and CP.TC.SM.ABPC in the domestic strains and TC.SM, TC, NA, TC.SM.KM.NA, and TC.SM.NA in the imported strains.

Drug Resistance, Microbial↗

[Increasing fluoroquinolone low-sensitivity in enterotoxigenic Escherichia coli isolated from diarrhea of overseas travelers in Tokyo].

Drug resistance trends were investigated for 1,318 enterotoxigenic Escherichia coli (ETEC) isolated from overseas traveler's diarrheal cases in Tokyo during 1988-1999. A total of 1.6% (21 strains) were nalidixic-acid resistant and fluoroquinolones (NFLX, OFLX, CPFX, LVFX, TFLX, SPFX; FQ) low-sensitive (or low-level-resistant). None of the strains were high-level-resistant to FQ. The FQ low-sensitive strains were isolated in 1996 for the first time, and increased from 3.4% in 1996 to 15.8% in 1999. Countries visited by travelers with the FQ low-sensitive ETEC were India (16 cases), Nepal (3 cases), Cambodia (1 case), and Egypt (1 case). Drug resistance-patterns of the FQ low-sensitive strains, including other drugs (CP, TC, SM, KM, ABPC, ST, NA, and FOM) tested, varied among the 6 types. Among those, multidrug resistant strains accounted for 57.1% (12 strains). The enterotoxin producing types of strains were LT (4 strains), ST (10 strains), and both (7 strains). The serotypes of the strains were classified into 16 types. The quinolone resistance determining regions (QRDRs) of the gyrA genes of the FQ low-sensitive strains were sequenced. The mutations of a Ser to a Leu at position 83 (Ser-83-->Leu) was found in 19 strains, and Asp-87-->Tyr was found in 2 strains.

Anti-Infective Agents↗

Improvement in right lung atelectasis (middle lobe syndrome) following administration of low-dose roxithromycin.

Middle lobe syndrome is a distinct clinical entity characterized by right middle lobe atelectasis. Prompt diagnosis and initiation of medical therapy including the administration of antibiotics and the avoidance of irritating agents may be effective. However, abnormal shadows on chest radiography remain unchanged even when acute symptoms have disappeared, suggesting latent lesional inflammation or recurrence. We describe 2 cases of atelectasis in the middle lobe of the right lung which resolved completely after administration of low-dose roxithromycin. Thus, low-dose therapy with a macrolide could be of interest or some value in these cases, but it is too early to draw a definite conclusion.

Aged↗