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Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 199 records · Page 11Linked to original sources
PubMed1996

Hydrophilic surroundings requisite for the solubilization of proteins related with their hydrophobicity in the AOT reversed micellar extraction.

The reversed micellar extraction (AOT/isooctane system) using the phase transfer method was investigated in relation to the AOT concentration and the water solubilization for ribonuclease A, lysozyme and cytochrome c. The minimal AOT concentration required for 100% forward extraction was obtained for these proteins. At the minimal AOT concentration, the hydrophilic surroundings, i.e. the molar ratio of water to extracted protein in the organic phase, were independent of the protein concentration for each protein. The hydrophilic surroundings of these proteins were linearly related with Fisher's polarity ratio, p, as an index of the hydrophobicity of the protein. Using this linear relation, a procedure to estimate the sufficient AOT concentration for the protein extraction was proposed. In the cases of cytochrome c and lysozyme, the water concentration was larger than that in the protein-free system in spite of the same AOT condition. On the contrary, in the case of ribonuclease A, this large water uptake in the organic phase was not observed. These differences of water uptake were discussed in relation to the location of the protein in the AOT reversed micelles.

Animals↗
PubMed1995

Poly A-linked non-isotopic microtiter plate reverse transcriptase assay for sensitive detection of clinical human immunodeficiency virus isolates.

A colorimetric reverse transcriptase assay (cRT assay) was developed for quantitative detection of HIV-1. In this format, reverse transcriptase incorporates biotin-labeled dUTP onto oligo-dT primers hybridized to poly A templates. The templates are covalently bound to the surface of microtiter wells. The amount of incorporated biotin-labeled dUTP is measured by binding horseradish peroxidase conjugated streptavidin, washing away unbound peroxidase, adding colorimetric substrate and then reading with a standard colorimetric reader. The sensitivity of the assay is very good. As little as 3 x 10(5) molecules of recombinant HIV-RT can be detected after 20 h of reaction time. Direct comparison using 3 cultured clinical isolates indicates that this level of detection is equivalent to the commercially available p24 antigen capture assay and the HIV-RNA assay based on branched DNA signal amplification. Other retroviruses, such as HIV-2 and feline immunodeficiency virus (FIV), can also be detected in this format. This non-isotopic assay is easy to perform and could provide a convenient and quantitative method for HIV study by monitoring reverse transcriptase, an essential activity in the infection process.

Animals↗
PubMed1995

Mechanisms of hyperkalemia caused by nafamostat mesilate.

1. Nafamostat mesilate (NM) is a novel serine-protease inhibitor used for the treatment of acute pancreatitis and disseminated intravascular coagulation. Recently, NM has been reported to cause hyperkalemia due to reduced urinary excretion of potassium (K). 2. This review briefly summarizes the roles of the cortical collecting duct (CCD) in the renal K excretion. 3. In vitro microperfusion technique was applied to examine whether NM, and its two metabolites, p-guanidinobenzoic acid (PGBA) and 6-amidino-2-naphthol, directly act on the CCD. 4. It was demonstrated that these compounds act mainly on the apical membrane of the collecting duct cell in the CCD and inhibit the amiloride-sensitive sodium (Na) conductance, resulting in an inhibition of K secretion. PGBA had the most potent action. 5. This direct action of these two metabolites, rather than NM, could contribute to the NM-induced hyperkalemia.

Animals↗
PubMed1995

Comparison of cardiovascular responses to airway management: fiberoptic intubation using a new adapter, laryngeal mask insertion, or conventional laryngoscopic intubation.

STUDY OBJECTIVES: To evaluate the circulatory effects of fiberoptic intubation with a newly developed mask adapter and to compare these effects with those obtained with a conventional laryngoscope and laryngeal mask airway with general anesthesia. DESIGN: Randomized study. SETTING: Operating room at a university hospital. PATIENTS: 30 ASA physical status I adult patients scheduled for minor elective surgery. INTERVENTIONS: A Macintosh laryngoscope was used for intubation in Group L (n = 10), a fiberoptic bronchoscope with newly developed mask adapter was used in Group FI (n = 10), and a laryngeal mask airway was used in Group LMA (n = 10). Anesthesia was induced with thiamylal, fentanyl, and vecuronium. Patients were manually ventilated for 4 minutes with sevoflurane. Then their tracheas were intubated with a laryngoscope or fiberoptic bronchoscope, or a laryngeal mask airway was inserted. MEASUREMENTS AND MAIN RESULTS: Blood pressure (BP) and heart rate (HR) were measured continuously. After intubation, the magnitude of change of both BP and HR was greatest in Group L, next highest in Group FI, and lowest in Group LMA. CONCLUSION: Fiberoptic intubation with general anesthesia using the newly developed mask adapter offers an advantage over the standard laryngoscope for patients in whom pressor response of intubation is potentially hazardous.

Adult↗
PubMed1995

Application of Ca-beta-glycerophosphate for artificial apical barrier formation.

This case demonstrates an artificial apical barrier formation by using calcium-beta-glycerophosphate paste in a nonvital permanent tooth with an open apex communicating with the maxillary sinus. The long-term satisfactory outcome of this case depended on the resolution of periapical pathosis and root canal obturation without overextension.

Adult↗
PubMed1995

Effects of glucocorticoid and mineralocorticoid on potassium transport in the rat medullary thick ascending limb of Henle's loop.

Potassium transport in the thick ascending limb is conducted by heterogeneous cells to opposite directions. Effects of glucocorticoids and mineralocorticoids on potassium transport of the rat medullary thick ascending limb (MTAL) were examined by in vitro microperfusion technique by measuring net potassium flux (JK), and apparent potassium conductances in the apical and basolateral membranes of two cell populations. Segments of MTAL were obtained from four groups of rats: sham operated control rats, adrenalectomized rats (ADX), adrenalectomized rats treated with dexamethasone (DEX), and adrenalectomized rats treated with aldosterone (ALDO). Fractional urinary potassium excretion was reduced by ADX and partially recovered by either DEX or ALDO. JK of the isolated perfused MTAL was markedly decreased by ADX from 5.13 to 1.94 pmol/min/mm. It was partially recovered by DEX (3.36 pmol/min/mm), but not by ALDO (2.07 pmol/min/mm). Random impalement of MTAL cells with a microelectrode in the control group revealed two cell populations; 76% was high basolateral conductance cell (HBC) and 24% was low basolateral conductance cell (LBC). In the ADX group, the basolateral potassium conductance of the HBC cell was markedly reduced, whereas the apical membrane potassium conductance of the HBC cell was increased. These changes were recovered in the DEX group, but not in the ALDO group. Potassium conductances of the apical and basolateral membranes in the LBC were unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Peripherally biased distribution of antigen proteins on the recombinant yeast-derived human hepatitis B virus surface antigen vaccine particle: structural characteristics revealed by small-angle neutron scattering using the contrast variation method.

The internal structure of the recombinant yeast-derived human hepatitis B virus surface antigen vaccine particle was investigated by small-angle neutron scattering using the contrast variation method. Data were collected in aqueous buffer solutions containing 0, 40, 60, and 100% D2O in the q range of 0.005 to 0.2 A-1 at 5 degrees C. The radius of gyration at infinite contrast and the maximum dimension of the particle were estimated to be 107 and 290 A, respectively. The contrast matching point of the particle was determined to correspond to about 30% D2O, indicating that a considerable portion of the vaccine particle is made up of lipids and carbohydrates from yeast. The distance distribution function of the particle at 40% D2O, at which the protein components are matched out to show only the distribution of the remaining lipids and carbohydrates, differed markedly from the functions at other D2Os, and showed the nearly symmetrical profile characteristic of a spherical particle with a diameter of 240 A. The Stuhrmann plot and profile of the distance distribution function at 40% D2O showed that (i) the vaccine is a spherical particle with a diameter of 290 A, in which two different regions in terms of scattering density are distributed radially, (ii) the lipids and carbohydrates form a spherical cluster with a diameter of 240 A in the core region of the particle, and (iii) the surface antigen protein is present in the peripheral region. This architecture of the vaccine particle is favorable for the induction of anti-virus antibodies.

Cloning, Molecular↗
PubMed1995

A case with dicentric translocation between chromosome 9 and 18: confirmation by fluorescent in situ hybridization on metaphase spread.

A female child with dicentric translocation between chromosome 9 and chromosome 18 presented non-specific minor anomalies with laryngomalacia. Chromosomal analyses were performed by the G-banding method and a fluorescence in situ hybridization (FISH) technique with a specific probe for the centromeric region of chromosome 18 and the painting probe for the chromosomes 9 and 18. Her full karyotype was confirmed as 45,XX,tdic(9;18)(p24;p11). This is the first case of dicentric translocation between chromosomes 9 and 18. The FISH technique is an important tool in chromosome diagnostics.

Centromere↗
PubMed1995

[Study on reverse transcriptase inhibiting antibody in plasma of HIV-1 seropositive subjects].

Reverse transcriptase (RT) inhibiting antibody in a series of plasma of HIV-1-seropositive subjects was quantitatively measured by poly A-linked colorimetric microtiter plate assay. The plasma were obtained from 6 asymptomatic carrier (AC)s and from 3 patients who progressed to AIDS. They had been followed 29-51 months. RT inhibiting antibody levels in the plasma were measured by inhibition assay against HTLV-IIIB RT activity. In five of the 6 AC cases, RT inhibiting antibodies in the serial plasma maintained high levels, and 50% inhibiting titers of the serial plasma did not decrease throughout the observation periods (45-51 months). HIV isolation from peripheral blood mononuclear cell (PBMC) of these 5 ACs did not succeed, and HIV p24 antigens were not detected in the plasma. In one AC case (046) RT inhibiting antibody levels gradually decreased after 48 months. In this case, HIV p24 antigen was not detected in the serial plasma throughout the observation period (48 months), but HIV was isolated from PBMC after 27 months. On the other hand, RT inhibiting antibody levels in the serial plasma of all 3 patients who progressed to AIDS gradually decreased in observation periods (29-35 months). HIV strains were isolated from these 3 cases. These results suggest that reduction of RT inhibiting antibody levels correlate well with the success of HIV isolation and with progression of clinical manifestation.

AIDS Serodiagnosis↗
PubMed1995

[Prior enrichment of HIV-DNA with probe-DNA particles for an efficient PCR diagnosis].

PCR mediated detection of HIV-DNA has been widely used. However, compared with traditional immunological diagnoses, the extraction of DNA is a laborious and time consuming step. We have developed a procedure for the efficient isolation and concentration of HIV-DNA from cell lysates. We report here a novel method by one can recover HIV-DNA in a small volume (approximately 50 microliters) of solution from a large volume of crude cell lysate which contains as few as several copies. The method uses the specific hybridization of HIV-DNA to HIV probe-DNA particles. This prior enrichment augmented the sensitivity in the detection of HIV-DNA by PCR, and allows us to make a diagnosis even if the specimen contained an extremely low copy number of HIV-DNA molecules in a large volume, which would have otherwise resulted in false-negative data with the conventional extraction method. The method also enables the examination of 100 individual blood specimens in a combined form. Thus, the application of the present enrichment procedure with HIV probe-DNA particles should reduce the labor and cost of HIV diagnosis, since the HIV positive samples represent a very minor group of people among specimens subjected to clinical laboratory tests, and particularly, among blood samples voluntarily donated to be used for transfusions.

Base Sequence↗
PubMed1995

Differentiation of human immunodeficiency virus type 1 (HIV-1) infections with HIV-2-cross-reacting antibody from mixed infections with HIV-1 and HIV-2 by serological absorption test.

The interpretation of dual seroreactivity with human immunodeficiency virus type 1 (HIV-1) and HIV-2 in blood samples is a serious problem facing AIDS researchers worldwide. Some samples of sera from HIV-1-infected patients showed a serological cross-reaction with HIV-2, causing confusion regarding the serodiagnosis. Therefore, we tried to differentiate these serum samples from those containing real mixed infections with both types of virus. Sera from patients with HIV-1 infections with HIV-2 cross-reacting antibody in Japan were distinguished from sera from patients with mixed infections with HIV-1 and HIV-2 in West Africa by our serological cross-absorption test, which proved to be highly specific and useful for serodiagnosis.

AIDS Serodiagnosis↗
PubMed1995

Prior enrichment of human immunodeficiency virus DNA with probe DNA particles for efficient PCR diagnosis.

We report here a novel method by which one can recover human immunodeficiency virus (HIV) DNA in a small volume (approximately 50 microliters) of solution from 8 ml of crude cell lysate which contains as few as several HIV DNA copies. The method uses the specific binding of HIV DNA to HIV probe DNA particles. The HIV DNA thus concentrated on the particles can be subjected to the PCR assay. The method also enables the examination of 100 individual blood specimens in a combined form.

Base Sequence↗
PubMed1995

Immunohistochemical localization of pH-sensitive K+ channel, RACTK1.

RACTK1 cDNA encodes a pH-sensitive K+ channel from the renal cortical collecting tubule cells, which is only localized in the kidney by Northern blots (Suzuki, M., K. Takahashi, M. Ikeda, H. Hayakawa, A. Ogawa, Y. Kawaguchi, and O. Sakai. Nature Lond. 367: 642-645, 1994). We further investigated the localization of the channel by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemical analysis showed that the signal was detected in various epithelia, including the luminal membrane of the cortical collecting tubules, artery of the kidney, and pancreatic ducts. Interestingly, the signal was also detected in the coronary vascular smooth muscle and cerebral artery. These tissue distributions were confirmed by localization of mRNA determined by RT-PCR. These findings suggest that RACTK1 encoding pH-sensitive K+ channels is widely distributed in epithelia as well as in vascular smooth muscle cells.

Animals↗
PubMed1995

Electrophysiological study of luminal and basolateral vasopressin in rabbit cortical collecting duct.

To clarify the mechanism of action of arginine vasopressin (AVP) on ionic conductances, electrophysiological technique was applied to the rabbit cortical collecting duct (CCD) perfused in vitro. When AVP (100 pM) was added to the bath, transepithelial voltage (VT), transepithelial resistance (RT), and fractional resistance of the apical membrane (fRA) of the principal cell displayed biphasic responses: initial increase in lumen-negative VT (phase I) was associated with decreases in RT and fRA, whereas secondary decrease in VT (phase II) was associated with increases in RT and fRA. In phase I, depolarization of the luminal membrane was observed due to stimulation of Na+ conductance in the luminal membrane. In phase II, mixed responses of both hyperpolarization of the luminal membrane, due to late inhibition of Na+ conductance, and depolarization of the basolateral membrane, due to stimulation of Cl- conductance, were observed. 8-(4-Chlorophenylthio)-adenosine 3',5'-cyclic monophosphate, as a pure vascular AVP receptor 2 (V2) action, mimicked the actions of AVP. Addition of AVP (100 pM to 1 nM) in the lumen resulted in increases in lumen-negative VT and RT. Luminal AVP did not affect the electrical parameters in beta-intercalated cells. In principal cells, luminal AVP caused sustained increase in total membrane resistance (Ri), together with an initial depolarization of the luminal membrane followed by a late hyperpolarization of the basolateral membrane. Because the initial response was abolished in the presence of 2 mM Ba2+ in the lumen, an inhibition of luminal K+ conductance may be responsible for the initial phase of luminal AVP action. Late hyperpolarization of the basolateral membrane associated with an increase in membrane resistance was abolished in the absence of ambient Cl-. Under the condition where Cl- conductance of the basolateral membrane was stimulated by administration of cAMP in the bath, voltage deflections of the basolateral membrane on changing Cl- concentration in the bath from 120 to 12 mM decreased by 88% in the presence of luminal AVP. These observations are in accord with the view that the basolateral Cl- conductance was inhibited by luminal AVP in the later phase. These data indicate that AVP in the lumen inhibits basolateral Cl- conductance, which is stimulated by AVP in the bath.

Animals↗
PubMed1995

Autologous pericardial patch repair for postinfarction ventricular septal perforation.

Surgical therapy for ventricular septal perforation associated with acute myocardial infarction is thought to reduce ventricular chamber volume and distort the ventricle due to excision of the myocardium. A 69-year old man underwent elective surgery that used an autologous pericardial patch without excising the myocardium. Intraventricular repair using the autologous pericardial patch enabled preservation of ventricular geometry and chamber volume and did not result in a depression of cardiac function. Moreover, it has been reported that this surgical procedure protects against suture bleeding and decreases the amount of foreign material required, thus possibly reducing the risk of infectious complications.

Aged↗
PubMed1995

Prevalence of antibodies to type A influenza viruses in swine sera 1990-1994.

A total of 3,120 swine sera collected for the years 1990-94 were tested for the presence of hemagglutination-inhibition (HI) antibodies against swine (H1N1) and human (H1N1 and H3N2) strains of influenza virus. No HI antibody against the swine strains was recognized during 18 months, though a slight prevalence (1.5-9.2%) of the antibodies was observed over the entire period. A wide variance in the incidence (0-26.3%) of antibodies against the human H3N2 strains was observed among the swine population.

Animals↗
PubMed1995

Immunohistochemical localization of inhibin alpha- and beta A-subunits in the ovary of immature female rats.

Immunohistochemical localization of inhibin alpha- and beta A-subunits was examined in the ovaries of immature female rats. The granulosa cells in various sized ovarian follicles obtained from rats that were 10-24 days old exhibited positive staining for inhibin alpha- and beta A-subunits. The relative intensities of immunostaining for alpha- and beta A-subunits increased during follicular growth and maturation. Ova and internal thecal cells did not show any immunostaining for inhibin alpha- and/or beta A-subunits. These results suggest that granulosa cells of immature rat ovaries may produce inhibin from the 10th day after birth, and that an increase in the number of mature ovarian follicles results in an increase in inhibin production in the immature rat ovary during prepubertal development.

Aging↗