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Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 379 records · Page 21Linked to original sources
PubMed1989

K+ channel currents in basolateral membrane of distal convoluted tubule of rabbit kidney.

To examine the nature of ion-conductive pathways in the basolateral membrane of rabbit distal convoluted tubule (DCT), we recorded single-channel currents from the tubule segment isolated from collagenase-treated kidney. Using cell-attached patch pipettes filled with 130 mM KCl, 5.4 mM CaCl2, and 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (pH 7.4), we observed K+ channels in the basolateral membrane of DCT, having two different single-channel conductances of 48.7 +/- 1.4 (n = 9) and 60.6 +/- 1.4 pS (n = 7). Both types of channels were completely blocked by 0.1 mM BaCl2. Both channels have same open probability of approximately 0.5 at the intrinsic basolateral membrane voltage and were recorded with similar incidence. Mean open and closed times were 31.5 +/- 5.2 and 41.3 +/- 16.0 ms for the smaller channel, and 31.5 +/- 5.1 and 36.7 +/- 8.7 ms for the larger channel, respectively. These kinetic properties did not show any clear voltage dependence in both channels. Because of apparent similarity of channel kinetics, it is possible that both activities might represent different states of the same channel. For definite conclusion, however, further investigations are necessary. In three recordings from 54 successful patches, we observed a flickering channel with rapid kinetics, which was insensitive to 1 meq/l Ba2+. The conductance of this channel was 76.6 pS (n = 2). The extrapolated zero current voltage was 76.0 mV (n = 2), indicating that this channel is permeable to K+. From these results, we suggest that K+ channels constitute conductive pathways for K+ in the basolateral membrane of rabbit DCT.

Animals↗
PubMed1989

Effects of Cl- transport inhibitors on Cl- permeability across hamster ascending thin limb.

The highly conductive Cl- transport pathway exists in the ascending thin limb (ATL) of Henle's loop. To characterize the mechanism of the Cl- conductance across the ATL, we examined effects on Cl- permeability across hamster ATL of Cl- transport inhibitors, including 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), diphenylamine carboxylate (DPC), and anthracene-9-carboxylic acid (9-AC), by the in vitro microperfusion technique. NPPB added to the bath caused reversible suppression of the relative permeability of Cl- to Na+ (PCl/PNa), as estimated from the NaCl diffusion voltage in a dose-dependent manner in a range from 3 x 10(-6) to 10(-3) M. The concentration of NPPB that inhibited PCl/PNa by 50% (ID50) was approximately 3 X 10(-5) M. When 3 X 10(-5) M NPPB was added to the bath, the lumen-to-bath flux coefficient for 36Cl (Kl----b,Cl- 10(-7) cm2/s) was decreased from 130.7 +/- 7.3 to 52.2 +/- 11.6 (n = 7, P less than 0.01). Application of NPPB in the lumen also caused reversible suppression of PCl/PNa, but this effect was less potent compared with the application of the drug via the bath. Whereas 10(-3) M 9-AC or 10(-3) M DPC decreased PCl/PNa by 6.5 +/- 1.2 and 10.2 +/- 2.6%, respectively, 3 X 10(-4) M NPPB decreased PCl/PNa by 69.7 +/- 3.8%. In maleimide-treated tubules, addition of 10(-3) M N-ethylmaleimide (NEM) increased PCl/PNa from 1.0 +/- 0.1 to 1.8 +/- 0.1 (n = 7, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Sodium chloride and water transport in the thin descending limb of Henle of the quail.

Birds and mammals can produce hyperosmotic urine, but their renal morphology and urine-concentrating mechanisms differ. To elucidate the countercurrent urine concentration mechanism in birds, we examined the structure and transport properties of the descending limb (DL) of Henle of mammalian-type nephrons in Japanese quail, Coturnix coturnix. In the avian renal medulla, a prominent ring of collecting ducts and scattered thick limbs surrounds a core of capillaries and DLs. Epithelial cells in the upper DL (DLu) have abundant microvilli and shallow, tight junctions; cells in the lower DL are flat and have little interdigitation. Transepithelial voltage was zero when the DLu was perfused and bathed in isosmotic avian Ringer solution. The efflux coefficients (10(-7) cm2/s) for Na (31.7 +/- 2.3) and Cl (24.9 +/- 3.6) were not significantly different and were unaltered by ouabain (10(-4) M) (32.5 +/- 2.2). Diffusional water permeability measured by [3H]H2O was low (73.0 +/- 7.8, 10(-7) cm2/s). Volume flux was nearly zero and increased only slightly when an osmotic gradient was imposed. These results suggest the DLu is highly permeable to Na and Cl and virtually impermeable to water; thus NaCl extruded actively from the thick ascending limb may enter the DL unaccompanied by water. This countercurrent multiplication system by use of single-solute recycling and a transport cascade of graded hairpin turns may help establish an osmotic gradient along the medullary cone. Thus avian and mammalian renal countercurrent multiplication systems may differ.

Animals↗
PubMed1989

Coronary aneurysms in a young adult: report of a case suspected of Kawasaki disease.

An autopsy case of coronary aneurysm was reported. The patient, a 23-year-old Japanese man, suddenly fell unconscious during a karate match and died an hour later. The autopsy revealed coronary aneurysms, one of which was accompanied by thrombosis. Histologically, the aneurysmal walls showed marked scar formation and intimal thickening and the state was regarded as healed arteritis. By taking a precise history from his parents, Kawasaki disease was thought to be the probable cause of the coronary aneurysms.

Adult↗
PubMed1989

Development of effective cross-linking method for bioactive substance--enzyme immobilization using glutaraldehyde oligomers.

When a 10% aqueous solution of glutaraldehyde (GA) was alkalized to pH 8.5 in borate buffer solution and heated at 60 degrees C, the ultraviolet spectrum of GA solution showed two distinct absorption maxima. The one at 280 nm with a weak absorbance ascribable to the C = O bond in the aldehyde group shifted to near 300 nm after 50 min with a slight increase in its intensity. Another maximum at 235 nm with a strong absorbance was ascribable to the C = C bond of the alpha,beta-unsaturated aldehyde group which was formed by aldol condensation reaction of GA monomer, and its absorbance increased markedly with increasing reaction time. The high performance liquid chromatography (HPLC) analysis with detection at 235 nm indicated that several GA oligomers were formed by the alkali treatment and their concentrations increased. The cross-linking ability of these oligomers was examined by immobilizing enzymes (alcohol dehydrogenase (ADH), glutamate dehydrogenase (GLDH] to an aminated polymer gel matrix by reaction with the treated GA solution. The enzyme activities increased with increasing concentration of GA oligomers. Then, the GA oligomers were isolated and used as the cross-linking agent. The activities of ADH and GLDH were 4-fold and 13-fold higher, respectively, than those obtained by using untreated GA solution, while the total amounts of immobilized enzymes were almost unchanged. These results suggest that GA oligomers may act as cross-linkers in a manner different from the generally accepted Schiff base formation reaction; a possible mechanism may involve addition reaction of an amino group to the double bond in the aldol condensate of GA.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Dehydrogenase↗
PubMed1989

[Preparation of monoclonal antibodies against duck hepatitis B core antigen and analysis of the monoclonal antibodies].

Mice were immunized against duck hepatitis B virus core (DHBc) particles isolated from the liver of asymptomatic carrier ducks of duck hepatitis B virus (DHBV) by ultracentrifugation. Their spleen cells were fused with mouse myeloma (NS-1) cells, and 12 clones of hybridoma cells secreting antibodies against DHBc (anti-DHBc) were isolated. According to the reactivity to core particles and core peptide obtained from DHBc particles treated with SDS-2ME, the 12 antibodies were classified into two groups. Two monoclonal antibodies reacted against both core particles and core peptide (B-type), the other ten monoclonal antibodies reacted against core particles but did not react against core peptide obtained from DHBc particles treated with SDS-2 ME. (A-type). Solid phase enzyme immuno assay (EIA) using these two types of antibodies could detect core antigenisity not only in the liver homogenate but also in the DHBV infected serum. Sucrose gradient analysis and gel filtration analysis revealed this DHBc antigenisity in the serum is not carried by core particles but carried by core peptide, equivalent to HBe antigen in the serum of Hepatitis B virus (HBV) carrier. This EIA may provide sensitive test monitoring both serum DHBe antigen levels and DHBc antigen levels in the liver during DHBV infection.

Animals↗
PubMed1989

Does the polystomatic gland exist?

According to the P.N.A., the N.A.J. and some scholars, the sublingual gland has the ductus sublingualis major and ductus sublinguales minores. This means that the gland is a polystomatic gland. We intended to determine whether the so-called polystomatic gland exists or not. 1. According to the P.N.A., the N.A.J. and some scholars, the gl. sublingualis has the ductus sublingualis major and ductus sublinguales minores. This means the gland is a polystomatic gland. However, the formation of one gland with plural excretory ducts is embryologically impossible, in other words, the polystomatic gland does not exist. 2. Many scholars described that the gl. sublingualis was composed of the gl. sublingualis major and g11. sublinguales minores. However, they are completely different kinds of glands. Accordingly, we suggest the terms for these glands: the g1. sublingualis and its ductus sublingualis ("major" is useless), the g11. sublinguales minores and their ductus sublinguales minores. 3. The N.A.V.J. and some scholars use the term g1. sublingualis polystomatica or parvicanalaris. However, this is a group of a number of independent glands each of which has its own excretory duct. Such a gland should not be regarded as a single gland. We suggest that the term g11. sublinguales minores and their excretory ducts should be replaced with the term the ductus sublinguales minores. 4. The g1. lingualis anterior, g1. retromolaris and g1. lacrimalis are not single glands but a group of several independent glands each of which has its own excretory duct. Accordingly, they should be termed the g11. linguales anteriores, g11. retromolares and g11. lacrimales such as the g11. labiales, g11. buccales and g11. palatinae.

Animals↗
PubMed1989

A new differentiation type of the chief cells in the cat gastric gland.

We demonstrated a new differentiation type of chief cell in the cat gastric gland. 1. Numerous PAS-positive cells were distributed not only in the glandular body but also in the glandular base. 2. These cells, namely immature chief cells, contained a large number of claret-colored fine pepsinogen granules. 3. Immature chief cells did not exist in the glandular base of man and many other types of animals. 4. The PAS-positive cells in the glandular base gradually decreased in PAS-positive substance and changed into PAS-negative cells with a reticulate framework. These mature chief cells contained numerous dark blue coarse pepsinogen granules. 5. The mature chief cells reacted moderately to AB (pH 2.5), and weakly to AB (pH 0.5), while staining with PAS-AB (pH 2.5) produced a moderate to strong color reaction of AB. Such reactions were characteristic to these cells and could not be found in man or many other types of animals studied. 6. PAS-positive cells i.e. the immature chief cells, reacted strongly to AB (pH 2.5), and moderately to AB (pH 0.5), while staining with PAS-AB (pH 2.5) produced a violet color. 7. The above-mentioned reactions were the same in mucous neck cells with mean undifferentiated characteristics. Such cells do not exist in the glandular base of man and many other types of animals. 8. The glandular base is generally occupied only by mature chief cells, though a large number of undifferentiated cells or immature chief cells were distributed in the same area of the cat.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminosalicylic Acid↗
PubMed1989

[The effect of orthographic difference between kanji and kana word on incidental memory].

Two experiments were designed to examine the effect of orthographic difference between Kanji and Kana word on memory. The experiments were carried out in incidental memory paradigms, where high and low imagery words without any homonyms were used as stimuli. In Exp. I, subjects were instructed to perform a phonological orienting task, then they were forced to take an unexpected memory test. Number of correct free recall for low imagery words was larger in Kanji than in Kana. In Exp. II, however, where subjects were instructed to perform a semantic orienting task, this effect was disappeared. These results were interpreted in terms of semantic encoding.

Adult↗
PubMed1989

[Observation with SEM on the displacement of mucosal surface in process of denture fabrication].

The process of denture fabrication entails a series of steps that begin with impression-taking. Dimensional accuracy and displacement of surface repeatability affect results in these individual steps. Although changes in individual materials have already been measured in the past, there has been almost no measurement up to now of denture fabrication up to the denture base, using the mucous membrane as the standard and then measuring changes in the displacement of surface repeatability for each step. Noticing this lack, the authors used a Scanning Electron Microscope (SEM), presently the only non-contact measuring instrument that can be used, and measured changes at the different stages including the mucous membrane, the impression materials, the plaster and the resin. A drying process is required for the mucous membrane, and such a process can cause changes in the mucous membrane which is the basis of measurement. For this reason, the authors used Araldite, a product from Ciba-Geigy AG, as a replica material and made replicas for all the test materials, using the replicas for measurement. Results were as follows: 1. Araldite was used as the replica material, thus making it possible with the SEM to observe changes in the displacement of surface repeatability at the individual stages. 2. Major changes in the accuracy of surface were observed during impression-taking and in the period of moving from the impression material to the plaster. 3. During high-power observation with the SEM, the fine bumps on the surface of the plaster and resin disappeared and the surfaces became smooth. This is believed to be the result of the separating agent and heat.

Dental Impression Materials↗
PubMed1989

[A statistical study on distribution patterns of plasma free amino acids].

We investigated the distribution patterns of 23 plasma free amino acids in 875 healthy adults (375 males and 500 females, aged from 30 to 50 years), which were obtained after an overnight fast, using three statistical parameters of MLL (Maximum Logarithmic Likelihood), square root of b1, b2, and selected their patterns from the three of ordinary normal, log-normal and square root-normal distributions. The distribution patterns of the majority of plasma free amino acids were found to be either log-normal or square root-normal, and occasionally ordinary normal. We also evaluated the reliability of our selection system by a simulation model of 100 sets of values for plasma free amino acids that were randomly determined by the parameters of original data. Good reliability was observed for some amino acids. Our selection system may be useful for comparing the present results with the future results that will be obtained by other methods.

Adult↗
PubMed1989

[Surgical treatment of interrupted aortic arch in infants under three months of age].

From March, 1982, through March, 1988, 8 infants less than 3 months of age underwent surgical treatment of interrupted aortic arch. Five patients had IAA type A and 3 patients had type B. Seven patients with associated VSD underwent staged operations and 1 infant with aortopulmonary window underwent primary repair off cardiopulmonary bypass. Aortic arch reconstruction was by subclavian aortic anastomosis (6) or large tube graft (8 mm) interposition (2) combined with pulmonary artery banding (5). All seven patients with associated VSD survived the first-stage operation. One patient subsequently underwent pulmonary artery banding, two underwent patch aortoplasty and four patients underwent intracardiac repair and removal of a pulmonary artery band, with six survivors (86%). The operative death occurred in an infant in whom modified Damus-Kaye-Stansel operation was carried out for severe subaortic stenosis, which rerouting all left ventricular blood through VSD and the main pulmonary artery into the ascending aorta and reconstructing right ventricular-distal pulmonary artery connection by a valved external conduit. All six surviving patients are doing well at present (mean follow up of 3 years) without any significant pressure gradient between the ascending and thoracic aorta. Based on these data we conclude: (1) Aortic arch reconstruction and pulmonary artery banding can be reliably performed even in critically ill infants with IAA and isolated VSD. (2) The primary repair will provide better chance of survival in infants with IAA associated with significant LVOTO, truncus arteriosus or aortopulmonary window that do not readily lend themselves to pulmonary artery banding.

Anastomosis, Surgical↗
PubMed1988

Structure-activity relationships of alpha-human atrial natriuretic peptide.

The spasmolytic activity of synthetic alpha-human atrial natriuretic peptide (alpha-hANP) and its related peptides was determined in vitro using the chick rectum and the rat aorta. Natriuretic activity was also measured in the anesthetized rat, alpha-hANP-(7-28), with the NH2-terminal hexapeptide truncated, had greater spasmolytic and natriuretic effect than did alpha-hANP-(1-28). These responses were reduced by truncation of the COOH-terminal residues. alpha-hANP-(7-23), the cyclic structure of alpha-hANP-(1-28), exhibited weak aortic relaxation and natriuretic activities. However, alpha-hANP-(7-23) produced a greater relaxation than did alpha-hANP-(1-28) in the chick rectum. Elimination of Gly at position 9 reduced the spasmolytic and natriuretic activity. Substitution of amino acid residues at position 8, 12 and 13 changed these activities. Analogues containing the ethylene linkage instead of the disulphide bond had weak biological activity. These results indicate that the size of the 17-amino acid ring and the COOH-terminal residues of alpha-hANP are important for the expression of spasmolytic and natriuretic activity.

Amino Acids↗
PubMed1988

Inhibition by the antilipogenic antibiotic cerulenin of thrombin-induced activation of human platelets.

Upon incubation with an antibiotic cerulenin, human platelets lost their abilities to aggregate and to release serotonin or ATP in response to various stimuli such as thrombin, ADP, collagen and platelet activating factor. The loss of activities was dependent on both incubation time and cerulenin concentrations. As judged by 14C-serotonin release, concentrations of cerulenin required for the half-maximal inhibition of thrombin-induced activation were 5-10 and 70 micrograms/ml in the incubation for 120 min at 37 degrees C for washed platelets and those in platelet rich plasma, respectively. The cerulenin treatment also resulted in a significant inhibition of 14C-acetate incorporation into the lipid fraction of platelets, suggesting that de novo synthesis of fatty acids was inhibited by the treatment. No release of lactate dehydrogenase activity nor morphological changes in platelet structure was detected upon cerulenin treatment. When effects of cerulenin on intracellular Ca2+ concentration were examined, mobilization of intracellular Ca2+ by thrombin was significantly depressed in the cerulenin-treated platelets as judged by Fura2, Quin2 or chlortetracycline fluorescence. Since the influx of external Ca2+ is not essential to the thrombin-induced platelet activation (Rink, T. J. et al. FEBS Lett. 148 21-26, 1982), the results suggest that cerulenin-treatments affect the platelet function through the inhibition of intracellular Ca2+ mobilization.

Adenosine Triphosphate↗
PubMed1988

Requirement of the Escherichia coli dnaA gene function for integrative suppression of dnaA mutations by plasmid R 100-1.

The phenotype of Escherichia coli dnaA missense and nonsense mutations was integratively suppressed by plasmid R100-1. The suppressed strains, however, could not survive when the dnaA function was totally inactivated. This was demonstrated by the inability of replacing the dnaA allele in the suppressed strain by a dnaA::Tn10 insertion using phage P1-mediated transduction. When the intact dnaA+ allele was additionally supplied by a specialized transducing phage, lambda imm21 dnaA+, which integrated at the att lambda site on the E. coli chromosome, then the dnaA::Tn10 insertion, together with a delta oriC deletion, were able to be introduced into the suppressed strain. Thus, the mechanisms of dnaA function for oriC and for the replication origin of R100-1 may not be quite the same.

Bacterial Proteins↗