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M Imai

Publications and source records attributed to M Imai.

At least 145 records · Page 8Linked to original sources
PubMed1998

[Evaluation of a rapid enzyme immunoassay membrane test for diagnosis of influenza A virus infection].

A rapid enzyme immunoassay membrane test, Directigen Flu A (Becton Dickinson, USA), was evaluated by using virus isolates and clinical specimens. The reference laboratory diagnosis was based on the results of virus isolation. Directigen Flu A was reactive for all subtypes of human influenza A viruses, including reference strains of H1N1, H2N2 and H3N2. Moreover, H5N1 (Hongkong/156/97) was also detected by this kit. No cross reactivity was detected with other respiratory viruses. Directigen Flu A showed positive reaction with the solution containing influenza A virus of 2.4 x 10(3) pfu/assay. The rapid test demonstrated 77.9% sensitivity and 98.4% specificity for testing of throat swabs from children with respiratory symptoms. It showed higher sensitivity and specificity (92.1% and 100%) for testing of nasopharyngeal aspirates. Directigen Flu A should be useful for the rapid diagnosis of influenza A virus infection.

Antigens, Viral↗
PubMed1998

Effect of protamine on cation-selective permeability in hamster medullary thick ascending limb of Henle's loop.

To estimate the contribution of the paracellular shunt pathway to cation-selective permeability in the hamster medullary thick ascending limb of Henle's loop, we observed the effect of protamine, a selective blocker of paracellular conductance, on salt-diffusion voltage (dVT) in the isolated nephron segment perfused in vitro. When 300 microg/ml protamine was added to the lumen, the lumen-positive dVT generated upon reduction of the lumen NaCl concentration was decreased from 5.1 +/- 0.9 to 0.8 +/- 0.8 mV and the calculated Na+/Cl- permeability ratio was decreased from 1.40 +/- 0.14 to 0.86 +/- 0.08. Although the effect of protamine persisted after removal of the agent from the lumen, addition of 30 U/ml heparin, which neutralizes protamine, returned the dVT toward the control level. This effect was almost the same when the orientation of the imposed NaCl gradient was reversed. Protamine exhibited a similar effect on dVT in the presence of ouabain added to the bath. Protamine was without effect from the bath. Protamine did not affect the basel VT perfused with the control solution. Increased VT by decreasing perfusion pressure was inhibited by adding protamine from the lumen. These observations suggest that the paracellular pathway contributes to the cation selectivity of the medullary thick ascending limb. The cation selectivity of the paracellular shunt pathway may mainly account for the changes in VT which are either dependent on the luminal flow rate or transmural NaCl concentration gradient, while it may not contribute to the basal level of VT.

Animals↗
PubMed1998

Effects of dichloroacetate in three patients with MELAS.

We present the clinical and laboratory effects of dichloroacetate (DCA) in three children with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) who had not responded to other medications. Administration of DCA lowered the elevated levels of lactate and pyruvate in the serum and CSF. DCA ameliorated abdominal pain, headache, and strokelike episodes, and improved cognitive function and fatigability in the three patients during the study period. Some transient liver dysfunction, hypocalcemia, and peripheral neuropathy were observed. The use of DCA in MELAS merits further study.

Adolescent↗
PubMed1998

Disposition characteristics of glycosylated poly(amino acids) as liver cell-specific drug carrier.

Potentials of glycosylated poly(amino acids) as carriers of drugs and/or polynucleotides to the liver were studied in mice in detail. Poly-L-glutamic acid (PLGA) and poly-L-lysine (PLL) were selected as carrier backbones and modified with 2-imino-2-methoxyethyl 1-thiogalactoside or mannoside to obtain galactosylated and mannosylated derivatives. After intravenous injection in mice at a dose of 1 mg/kg, Gal-PLGA and Man-PLGA were selectively taken up by the liver parenchymal cells (PC) and liver nonparenchymal cells (NPC), respectively. Moreover, the uptake of Gal-PLGA and Man-PLGA by the liver were significantly inhibited by the presence of Gal-BSA and Man-BSA, respectively. On the other hand, PLL was targeted to the liver without glycosylation. However, Gal-PLL and Man-PLL showed higher accumulation in the liver than unmodified PLL. Although Gal-PLL and Man-PLL showed different distribution between PC and NPC from that of PLL, the effect of the modifications was less pronounced than the cases of PLGA derivatives. In addition, these glycosylated poly(amino acids) investigated, regardless of the type of amino acid or the sugar grafted, were rapidly degraded to be eluted in the low molecular weight fractions in a gel filtration chromatography. These results suggest that glycosylated PLGAs can be useful carriers of low molecular drugs to the liver cells through conjugation, while glycosylated PLLs could be targetable carriers to the cells after the reduction of their cationic charge by complex formation with polynucleotides.

Animals↗
PubMed1998

[Topography, size and number of cortical tubers in tuberous sclerosis with West syndrome].

To predict the prognosis of tuberous sclerosis with West syndrome, we studied the relation between the cortical tubers and the neurological evolution. We reviewed the clinical data on the seizure evolution and developmental status of 7 patients (3 males and 4 females) and estimated the number, size and location of cortical tubers on 5 mm-thick T2-weighted MR images. The cortical tubers were grouped into categories: small (10 mm or less in maximum diameter), medium (10 to 25 mm) and large (25 mm or more). The first MRI study was performed at ages form 3 months to 18 years, and the follow-up study was performed on 6 out of the 7 patients. We also estimated the interval change of cortical tubers. The average number of cortical tubers was 12.1 per patient, being larger than the values previously reported for the patients of tuberous sclerosis without West syndrome. However, the numbers varied widely from 1 to 29. Two patients with good outcome had more than 10 tubers, whereas two patients with poor outcome had less than 5 tubers. All the patients with good outcome were female. Follow-up MRI in one patient revealed a marked increase in the number of cortical tubers, from 15 (at the age of 5 months) to 23 (at 4 years 2 months), which probably resulted from physiological hypomyelination during infancy. Some tubers corresponded to a electroencephalographic focus, whereas others did not. There was no difference in the topography of cortical tubers between the patients with good prognosis and those with poor prognosis. Thus, it was hard to make the prognosticate a case of tuberous sclerosis based solely on the number and topography of cortical tubers on MRI.

Cerebral Cortex↗
PubMed1998

[Vascular endothelial growth factor levels in the aqueous and serum in diabetic retinopathy with or without neovascular glaucoma].

We determined the levels of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in the aqueous and serum in non-insulin dependent diabetic patients with proliferative retinopathy (n = 12) and neovascular glaucoma (n = 11). The aqueous levels of PEGF/VPF were significantly higher in both groups than in 10 diabetics without such complications. The levels were very high in patients with neovascular glaucoma, suggesting that VEGF/VPF is involved in the pathogenesis and progression of diabetic neovascular glaucoma. The serum levels were not significantly related to the presence or the stage of retinopathy. The findings suggest the possibility of treatment of neovascular glaucoma using anti- VRGF/VFP preparations.

Adult↗
PubMed1997

Proton secretion in the upper part of the descending limb of long-looped nephron from hamsters.

The proton transport processes in the upper part of the descending limb of the long-looped nephron (LDLu) from hamsters were studied using a fluorescent dye, 2',7'-bis(carboxyethyl)carboxyfluorescein (BCECF) in microperfused single nephron preparations. Intracellular pH (pHi), as assessed by the measurement of the fluorescence of BCECF trapped in the cytoplasm, was 7.23 +/- 0.05 (n = 18) under nominally HCO3--free conditions. Ouabain, when added to the bath, decreased pHi by 0.22 units. After an NH4Cl prepulse, the initial proton extrusion rate was 1.23 +/- 0.26 (n = 9) pH units/min, and was retarded in the presence of 1 mM amiloride either in the bath or in the lumen. pHi failed to recover when Na+ was eliminated from ambient solutions. These observations suggest that Na+/H+ antiporters exist both in the apical and basolateral cell membranes. By measuring tubular fluid pH (pHt) under stopped flow conditions, we examined whether the hamster LDLu has the capacity to generate and maintain a transmural H+ gradient. After the tubular outflow was obstructed, the luminal fluid was rapidly acidified, reaching a steady-state pH of 6.84 +/- 0.09 (n = 7). The steady-state pH was influenced by bath pH. Tubular fluid acidification was not observed in the absence of Na+ and was prevented by ouabain. We conclude that the hamster LDLu has the capability to generate and maintain a transmural proton gradient by proton secretion via a luminal Na+/H+ antiporter which is secondarily driven by the Na+-K+ ATPase in the basolateral membrane.

Acids↗
PubMed1997

Successful treatment of a rectal anastomotic stenosis by transanal endoscopic microsurgery (TEM) using the contact Nd:YAG laser.

We report the advantage of employing transanal endoscopic microsurgery (TEM) using the contact Nd:YAG laser for the treatment of a rectal anastomotic stenosis. A 72-year-old woman was admitted to our hospital with a postoperative rectal anastomotic stenosis. Twenty months prior to admission, the patient underwent a low anterior resection for the treatment of the rectal cancer using an EEA stapling device. A barium enema and colonoscopy revealed a rectal stenosis, 0.8-cm diameter. This stenosis was at the anastomotic site, approximately 4.0 from the dental line. An endoscopic treatment was performed transanally using the contact Nd:YAG laser. The stenotic rectal wall was fulgurated or vaporized completely. There were no intraoperative or postoperative complications. We concluded that TEM appears to be a safe and minimally invasive procedure. Furthermore, the contact Nd:YAG laser is very effective in treating the gastrointestinal stenotic area. To our knowledge, this is the first successful report of this novel procedure.

Aged↗
PubMed1997

Production of inhibin A and inhibin B in human ovarian sex cord stromal tumors.

OBJECTIVE: Our purpose was to examine the cellular localization of inhibin subunits and messenger ribonucleic acid expressions for the inhibin subunits and the serum levels of inhibin A and inhibin B in human ovarian sex cord stromal tumors. STUDY DESIGN: We examined the immunohistochemical localization of the inhibin subunits and the expression of the corresponding messenger ribonucleic acids by Northern blot analysis in a granulosa cell tumor and a Sertoli-Leydig cell tumor. We also measured serum concentrations of dimeric inhibin A and inhibin B by two-site enzyme-linked immunosorbent assay. RESULTS: Immunostaining specific for the inhibin alpha, betaA, and betaB subunits was observed in the granulosa cell tumor. In the Sertoli-Leydig cell tumor we observed immunostaining specific for the alpha subunit in Leydig tumor cells and that specific for the betaA subunit in Sertoli tumor cells and that specific for the betaB subunit in both tumor cells. Northern blot analysis revealed the presence of messenger ribonucleic acids for the alpha, betaA, and betaB subunits in the granulosa cell tumor and the Sertoli-Leydig cell tumor. The serum levels of dimeric inhibin A and inhibin B in patients were elevated preoperatively and decreased progressively after surgery. CONCLUSION: Our results suggest that inhibin A and inhibin B are produced by the human sex cord stromal tumors and that inhibins might be the useful markers of the tumors.

Adolescent↗
PubMed1997

A cross-linguistic study of early word meaning: universal ontology and linguistic influence.

This research concerns how children learn the distinction between substance names and object names. Quine (1969) proposed that children learn the distinction through learning the syntactic distinctions inherent in count/mass grammar. However, Soja et al. (1991) found that English-speaking 2-year-olds, who did not seem to have acquired count/mass grammar, distinguished objects from substances in a word extension task, suggesting a pre-linguistic ontological distinction. To test whether the distinction between object names and substance names is conceptually or linguistically driven, we repeated Soja et al.'s study with English- and Japanese-speaking 2-, 2.5-, and 4-year-olds and adults. Japanese does not make a count-mass grammatical distinction: all inanimate nouns are treated alike. Thus if young Japanese children made the object-substance distinction in word meaning, this would support the early ontology position over the linguistic influence position. We used three types of standards: substances (e.g., sand in an S-shape), simple objects (e.g., a kidney-shaped piece of paraffin) and complex objects (e.g., a wood whisk). The subjects learned novel nouns in neutral syntax denoting each standard entity. They were then asked which of the two alternatives--one matching in shape but not material and the other matching in material but not shape--would also be named by the same label. The results suggest the universal use of ontological knowledge in early word learning. Children in both languages showed differentiation between (complex) objects and substances as early as 2 years of age. However, there were also early cross-linguistic differences. American and Japanese children generalized the simple object instances and the substance instances differently. We speculate that children universally make a distinction between individuals and non-individuals in word learning but that the nature of the categories and the boundary between them is influenced by language.

Adult↗
PubMed1997

Serum levels of inhibin A and inhibin B in women with normal and abnormal luteal function.

OBJECTIVE: To determine whether serum inhibin A and inhibin B concentrations are lower in patients with luteal dysfunction than in women with normal luteal function. METHODS: Serum samples were collected from seven healthy women with regular menstrual cycles. Serum samples on days +5 to +9 after the LH surge were collected from patients with luteal dysfunction. The diagnosis of luteal dysfunction was based on a luteal phase duration less than 11 days and a single midluteal progesterone level below 10 ng/mL. Serum levels of inhibin A, inhibin B, progesterone, estradiol (E2), FSH, and LH were measured. RESULTS: The serum inhibin A levels were increased toward the late follicular phase. The levels reached a maximum during the midluteal phase, followed by a fall during the late luteal phase. The serum inhibin B levels were high during the follicular phases and the early luteal phase. The levels decreased during the midluteal and late luteal phases. Serum levels (mean +/- standard error of the mean) of inhibin A in patients with luteal dysfunction were significantly lower than those in women during the midluteal phase (26.2 +/- 2.9 compared to 41.9 +/- 2.8 pg/mL; P < .01) in addition to the expected decrease in serum progesterone levels (6.3 +/- 0.7 compared to 14.7 +/- 1.2 ng/mL; P < .01). Serum inhibin B levels did not differ significantly between normal women and those with luteal dysfunction. There also were no significant differences in the E2, FSH, and LH levels. CONCLUSION: Levels of inhibin A, but not of inhibin B, may reflect the human luteal function.

Adult↗
PubMed1997

Some properties of inorganic pyrophosphatase from Bacillus subtilis.

Inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1; PPase) from Bacillus subtilis was purified to a homogeneous state electrophoretically when analysed by SDS-PAGE. The enzyme consists of six identical subunits; the molecular weight of the native enzyme estimated by gel filtration was approx. 120,000, and denaturing polyacrylamide gel electrophoresis gave a single band corresponding to 24,000. The enzyme absolutely required a divalent cation for its activity. Mg2+ was most effective, showing two steps of concentration-dependent activation. Mg2+ could be partially replaced by Mn2+ and Co2+. The enzyme was thermostable in the presence of Mg2+, and no loss of activity was observed on the incubation at 55 degrees C for an hour.

Bacillus subtilis↗
PubMed1997

Isoflurane attenuates early neutrophil-independent hypoxia-reoxygenation injuries in the reperfused liver in fasted rats.

BACKGROUND: Ischemia-hypoxia followed by reperfusion and reoxygenation injures cells and organs. Previous studies have indicated that isoflurane may protect organs from ischemia-reperfusion or hypoxia-reoxygenation. This study investigated the ability of isoflurane to protect the liver from hypoxia-reoxygenation injury and the mechanisms of this phenomenon. METHODS: The isolated liver was perfused at a constant pressure of 12 cm H2O with a modified Krebs-Ringer-bicarbonate solution saturated with a 95% oxygen/5% carbon dioxide gas mixture. Hypoxic perfusion produced by decreasing the oxygen concentration in the gas mixture to 10% was followed by perfusion at 95% oxygen for 60 min. Viability of the liver was assessed by lactate dehydrogenase release from the liver. Isoflurane at 0.5, 1, and 2 minimum alveolar concentration was administered to assess the effect of isoflurane on hypoxia-reperfusion injury. To determine the effect of isoflurane on extracellular generation of superoxide in the liver, the reduction of ferricytochrome c with or without superoxide dismutase was measured. RESULTS: Lactate dehydrogenase release was transiently but dramatically increased by reoxygenation and significantly attenuated by 1 and 2 minimum alveolar concentration of isoflurane. Suppression of Kupffer cells with gadolinium chloride also attenuated the lactate dehydrogenase release. Isoflurane significantly reduced the superoxide generation on reperfusion. CONCLUSIONS: The results show that isoflurane protected the liver from an early reoxygenation injury presumably mediated by Kupffer cells. The mechanisms of the inhibitory effects of isoflurane on the injury may involve suppression of extracellular superoxide generation during reoxygenation.

Anesthetics, Inhalation↗
PubMed1997

Heat shock protein 70 messenger RNA reflects the severity of ischemia/hypoxia-reperfusion injury in the perfused rat liver.

OBJECTIVES: To determine whether ischemia-reperfusion and hypoxia-reoxygenation cause cellular damages and stress responses in an isolated perfused rat liver model. To determine whether the increased synthesis of stress protein messenger RNA reflects cellular injury. DESIGN: Prospective, controlled study. SETTING: Institutional laboratories. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Isolated rat livers with cell free perfusion were exposed to various periods of ischemia-reperfusion or hypoxia-reoxygenation. MEASUREMENTS AND MAIN RESULTS: We measured hepatic oxygen consumption and alanine aminotransferase leakage from liver during perfusion. We analyzed the gene expression of heat shock protein 70, a major stress protein, of the liver by Northern blotting after perfusion. The expression of heat shock protein 70 messenger RNA augmented as the reperfusion period increased. The expression level after graded ischemia or hypoxia significantly correlated with the calculated hepatic oxygen debt (r2 = .737; p < .001; n = 21), or with the accumulated alanine aminotransferase leakage from the liver (r2 = .509; p < .001; n = 21). CONCLUSIONS: These results suggest that the accumulation of heat shock protein 70 messenger RNA reflects the severity of ischemia-reperfusion and hypoxia-reoxygenation injuries, and that a stress response in reperfusion can be triggered without formed elements of blood.

Alanine Transaminase↗
PubMed1997

Effects of volatile anesthetics on the calcium ionophore A23187-mediated alterations in hepatic flow and metabolism in the perfused liver in fasted rats.

Alterations in intracellular calcium homeostasis have been implicated in heptic injury. Volatile anesthetics modulate the homeostasis of intracellular calcium. The effects of volatile anesthetics on the hemodynamic and metabolic alterations induced by the calcium ionophore A23187 were studied using isolated liver perfusion in fasted rats. The liver was isolated from 24 hr-fasted male Sprague-Dawley rats, and perfused through the portal vein at a constant pressure of 1.2 kPa in a recirculating perfusion-aeration system. Halothane, isoflurane and sevoflurane were administered at 2%, 3% and 4.4%, respectively. All volatile anesthetics maintained basal hepatic flow, reduced oxygen consumption, and transiently enhanced net lactate production. A23187 at initial concentrations of 0.8 to 3.2 microM decreased hepatic flow and oxygen consumption in a dose-dependent manner, and enhanced lactate production. All anesthetics significantly attenuated the decreases in hepatic flow and oxygen consumption after administration of A23187 at 1.6 microM. None of the anesthetics significantly influenced the A23187-induced enhancement of net lactate production. Volatile anesthetics may attenuate the hepatic vasoconstriction and oxygen debt induced by intracellular calcium overload.

Anesthetics, Inhalation↗
PubMed1997

[Rapid detection of influenza virus A (AH1, AH3) and B by nested-polymerase chain reaction].

We applied the Nested-polymerase chain reaction (PCR) for laboratory diagnosis of influenza virus infection. We used three primer sets for detection of influenza virus A (AH1, AH3) and B. The primer sets for each type (AH1, AH3, B) was able to detect specifically each type of influenza. We measured the sensitivity for detection of vaccine strains. The PCR method was able to detect 0.9 PFU/assey of AH1 type, 1.0 PFU/assey of AH3 type and 1.8 PFU/assey of B type. Out of 46 isolation negative but antibody positive cases, 38 cases were positive for PCR (82.6%). This method is sensitive and useful for rapid diagnosis of influenza virus infection.

Humans↗
PubMed1997

[Simple method for typing human immunodeficiency virus type I (B, E) by PCR and chronological change of distribution of subtype (B to E) in Japan].

We analyzed the clade distribution of B and E in HIV-1 isolates in Japan by a nested PCR method using 5'-CCCACAAGATTTAAATATG-3' of the gag gene as clade B primer and 5'-CCCACAAGATTTAAACTCC-3' of the gag gene as clade E primer. Seventy-two anti-HIV-1 confirmatory positive serum samples were collected during a period of 1991-1996 in two hospitals in Yokohama City. Peripheral blood mononuclear cells were obtained from the buffy coat of these samples and extracted DNA were used for nested PCR. The 72 cases comprised of 11 Japanese hemophiliacs, 14 Japanese male homosexuals, 19 Japanese male heterosexuals, 5 Japanese female heterosexuals and 23 Thai female heterosexuals. Of these 36 were clade B and 35 were clade E and one case showed positive PCR results for both B and E primers. Almost all male Japanese hemophiliacs and homosexuals in our sample have clade B, while the female Thai heterosexuals have clade E, irrespective of the year of isolation. As for Japanese male heterosexuals, through 1993, clade B was predominant but since 1994, the predominate clade switched to clade E. Although the number of Japanese female heterosexuals in our sample is small, clade B was isolated in 2 cases even after 1994.

Female↗