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Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 433 records · Page 24Linked to original sources
PubMed1987

Effects of anion transport inhibitors and ion substitution on Cl- transport in TAL of Henle's loop.

To identify the mechanism of Cl- transport across the thin ascending limb of Henle's loop (TAL), we examined effects of anion transport inhibitors and ionic substitution in the isolated segments of hamsters using the in vitro microperfusion technique. 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) at 10(-3) M changed the NaCl diffusion voltage (Vt) to the orientation that corresponds to the decrease in the Cl(-)-Na+ permeability ratio when it was added either to the bath or to the lumen. DIDS, added to the bath or to the lumen decreased the lumen-to-bath flux coefficient for 36Cl, KCl-(1----b) (X10(-7) cm2/s), from 74.5 +/- 2.1 to 17.9 +/- 3.6 and from 77.7 +/- 3.6 to 51.1 +/- 5.4, respectively, whereas it had little effect on the flux coefficient for 22Na, KNa+(1----b). Elimination of HCO3- slightly increased rather than decreased both NaCl diffusion potential and KCl-(1----b), indicating that Cl- transport is independent of HCO3- transport. Phloretin at 10(-3) M inhibited both diffusion potential and KCl-(1----b) to a similar extent as DIDS did. KNa+(1----b) was also changed little. The inhibitory effect of phloretin was rapid and reversible. Phloridzin was ineffective. Furosemide added to the bath at 10(-3) M decreased Vt and KCl-(1----b) from 29 +/- 0.9 to 5.3 +/- 0.7 mV and from 75.7 +/- 3.9 to 62.8 +/- 4.1 X 10(-7) cm2/s, respectively; but it was ineffective when added to the lumen. Elimination of Na+ caused only a small decrease in KCl-(1----b) from 119.2 +/- 6.9 to 107.3 +/- 8.5 X 10(-7) cm2/s. Elimination of K+ and addition of Ba2+ did not change KCl-(1----b). From these observations, we conclude that Cl- transport across the TAL is distinct from Na+ and is not coupled with Na+, K+, or HCO3-.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1987

Effect of pH on Cl- transport in TAL of Henle's loop.

To further characterize the mechanism of Cl- transport across the hamster thin ascending limb (TAL) of Henle's loop, we examined effects of pH on Cl- permeability as determined by either the choline chloride diffusion voltage or the lumen-to-bath 36Cl flux in the isolated segments perfused in vitro. When pH of the bathing fluid or the perfusate was reduced from 7.4 to 5.8, the Cl(-)-Na+ permeability ratio (PCl/PNa) was reduced from 2.77 +/- 0.21 to 0.48 +/- 0.02 (n = 7, P less than 0.01) or from 2.55 +/- 0.15 to 0.81 +/- 0.11 (n = 6, P less than 0.01), respectively. At 37 degrees C, when the pH of the bathing fluid was reduced from 7.4 to 6.2, the lumen-to-bath flux coefficient for 36Cl (X10(-7) cm2/s) was reduced from 84.8 +/- 7.5 to 20.4 +/- 3.2 (n = 7, P less than 0.01), whereas the value for 22Na was unchanged (27.3 +/- 2.9 vs. 25.3 +/- 2.5, n = 5). From the pH titration curves for PCl/PNa, pKa values for proton binding were 6.31 and 5.78, and Hill's coefficients were 2.1 and 2.3 on the basolateral side and on the luminal side, respectively. Alkalinization had little or no effect on the Cl- permeability. At room temperature, the acid pH did not affect the Cl- permeability. Intracellular acidification with o-nitrophenylacetate also decreased the Cl- permeability.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1987

Genomic heterogeneity of hepatitis B virus in a 54-year-old woman who contracted the infection through materno-fetal transmission.

From the plasma of a 54-year-old woman, who acquired the persistent carrier state of hepatitis B virus through materno-fetal transmission, 49 clones of viral genomes were propagated. They did not reveal any differences in the size and number of cleavage products with any of 11 restriction endonucleases. Randomly selected 5 clones were classified into 3 groups by the variation at 4 positions in the nucleotide sequence of the envelope and core genes. The complete nucleotide sequences were determined for 3 of them, each representing a group, and they all had a genomic length of 3215 nucleotides. Variation was found in from 5 to 11 nucleotides. Assuming the infection with the common ancestor virus at birth, hepatitis B virus genomes in her plasma were estimated to have evolved at a rate from 1.4 to 3.2 x 10(-5) nucleotide substitutions per site per year. This value is 10(4)-fold greater than DNA genomes, 10(2)-fold less than human immunodeficiency virus but in the same order as most RNA viruses including certain retroviruses.

Base Sequence↗
PubMed1987

Staged repair of supravalvular aortic stenosis associated with severe multiple peripheral pulmonary stenoses: report of extended peripheral pulmonary arterioplasty.

This paper describes surgical experience in supravalvular aortic stenosis associated with severe multiple peripheral pulmonary stenoses treated by a staged approach: initial staged repair of the bilateral pulmonary stenoses by arterioplasty through a thoracotomy and later definitive intracardiac repair of supra-valvular aortic stenosis. Our experience in two cases proved that the peripheral pulmonary arteries could be exposed up to the segmental branches by dissection from the pulmonary hilum through a lateral thoracotomy without damaging the lung parenchyma. The stenotic areas could then be repaired with either a bifurcated or trifurcated pericardial patch.

Aortic Valve Stenosis↗
PubMed1986

Application of hepatitis B core particles produced by human primary hepatocellular carcinoma (PLC/342) propagated in nude mice to the determination of anti-HBc by passive hemagglutination.

Human primary hepatocellular carcinoma (PLC/342), carried by nude mice, produces hepatitis B core particles as well as hepatitis B surface antigen particles. Core particles purified form PLC/342 tumors displayed epitopes of hepatitis B core antigen (HBcAg) but not epitopes of hepatitis B e antigen (HBeAg) on their surface, unlike core particles prepared from Dane particles, derived from plasma of asymptomatic carriers, that expressed epitopes of both HBcAg and HBeAg. Core particles obtained from PLC/342 tumors were applied to the determination of antibody to HBcAg (anti-HBc) by passive hemagglutination. The assay detected anti-HBc not only in individuals with persistent infection with hepatitis B virus and in those who had recovered from transient infection, but also in patients with acute type B hepatitis, indicating that it can detect anti-HBc of either IgG or IgM class. A liberal availability of core particles from tumors carried by nude mice, taken together with an easy applicability of the method, would make the passive hemagglutination for anti-HBc a valuable tool in clinical and epidemiological studies, especially in places where sophisticated methods are not feasible.

Acute Disease↗
PubMed1986

Difference in molecular size of receptors for alpha-rat atrial natriuretic polypeptide among the kidney, aorta, and adrenal gland as identified by direct UV-photoaffinity labeling.

In order to identify the molecular size of receptors for alpha-rat atrial natriuretic polypeptide (alpha-rANP), we utilized the direct UV irradiation method for photoaffinity labeling with the biologically active [125I] alpha-rANP. In the preparation of isolated glomerulus and the inner medullary collecting duct (IMCT)-rich fraction, the autoradiograms of the electrophoresed sodium dodecyl sulfate (SDS)-polyacrylamide gels showed a single radioactive band which is displaceable with unlabeled alpha-rANP. The dose-dependent displacement fit very well with a binding-inhibition curve representing the binding affinity of 6.5 X 10(-10) M. The molecular size of the ligand-receptor complex was about 65,000 daltons for both glomerulus and IMCT-rich fraction. In contrast, in homogenate of the aorta and adrenal gland, the ligand-receptor complex was 140,000 daltons.

Adrenal Glands↗
PubMed1986

Additive effects of atrial natriuretic polypeptide and of renal vasodilating agents in the anesthetized dog.

In order to examine the contribution of an increase in renal papillary plasma flow to the mechanism of natriuresis by atrial natriuretic polypeptide (ANP), we compared the natriuretic effects of ANP administered into the renal artery of the dog together with secretin or acetylcholine (ACh). At an equivalent renal vasodilating dose, ACh increased urinary excretion of sodium (UNaV) to 212 +/- 36% of the control associated with a decrease in urine osmolality (62 +/- 6%), whereas secretin did not change UNaV (113 +/- 12%) or urine osmolality (101 +/- 14%). This result was compatible with the view that ACh causes natriuresis mainly by increasing papillary plasma flow. Combined administration of ANP with secretin caused a marked increase in UNaV to 407 +/- 55%, in association with a decrease in urine osmolality to 55 +/- 9%, suggesting that ANP may cause natriuresis by a mechanism similar to that of ACh. Combined administration of ANP with ACh further increased UNaV to 323 +/- 67% and decreased urine osmolality to 50 +/- 6%. These observations suggest that ANP and ACh share common but not identical mechanisms of natriuretic action since ANP caused additional natriuresis during ACh infusion. These findings, however, do not necessarily exclude the possibility that ANP also inhibits renal sodium reabsorption by a direct action.

Acetylcholine↗
PubMed1986

A solid-phase enzyme immunoassay for the common and subtypic determinants of hepatitis B surface antigen with monoclonal antibodies.

Monoclonal antibodies were raised against the common (a) as well as subtypic determinants (d, y, w and r) of hepatitis B surface antigen (HBsAg). They were applied to subtyping HBsAg by sandwiching it between antibody against a fixed on a solid-phase support and antibody against one or other of d, y, w and r, linked to horseradish peroxidase. The assay was applied to evaluate antigenic specificities of the NIH and Japanese panels composed of 44 sera containing HBsAg particles of various subtypes. HBsAg particles of a hybrid subtype, adyr, were sandwiched between monoclonal antibody against d and that against y, thereby indicating that they possessed both d and y determinants on the selfsame particle. The expression of d and y determinants on hybrid HBsAg particles was much less than that on ordinary particles of adw, adr, ayw or ayr subtype.

Animals↗
PubMed1986

A radioimmunoassay that sandwiches human interleukin-2 between radiolabeled monoclonal antibody and the receptor on a hematopoietic cell line.

Two monoclonal antibodies were raised against human interleukin-2 (IL-2) produced by E. coli harboring recombinant complemental DNA. Both antibodies did not neutralize its activity, nor did they inhibit the binding of IL-2 to the receptor on target cells. Taking advantage of the ability of monoclonal antibodies to detect IL-2 that had bound to the receptor, a radioimmunoassay was developed that sandwiched IL-2 between the radiolabeled monoclonal antibody and the receptor on a hematopoietic cell line infected with human T cell leukemia virus Type I. The assay had the advantage of detecting only IL-2 with the ability to bind to the receptor, and displayed a linear dose-response relationship over concentrations ranging from 5 to 100 ng/ml.

Antibodies, Monoclonal↗
PubMed1986

Killer toxin from Hansenula mrakii selectively inhibits cell wall synthesis in a sensitive yeast.

Hansenula mrakii secretes extracellularly a killer toxin which kills sensitive Saccharomyces cerevisiae. In protoplasts of this yeast, the killer toxin selectively inhibited the synthesis of alkali-insoluble acid-insoluble polysaccharides consisting mainly of beta-glucan, but did not inhibit either the synthesis of other cell wall polysaccharides, such as mannan, chitin and alkali-insoluble acid-soluble polysaccharides, or the synthesis of protein. Consistent with these results, the toxin was inhibitory to the beta-(1,3)-glucan synthetase activity of a cell-free extract from sensitive S. cerevisiae.

Cell Wall↗
PubMed1986

Application of monoclonal antibodies to the isolation and characterization of a killer toxin secreted by Hansenula mrakii.

A strain of yeast, Hansenula mrakii, secretes a toxin that kills sensitive yeasts, such as Saccharomyces cerevisiae Monoclonal antibodies raised against the toxin had both binding and neutralizing activities. The toxin in culture media was isolated by an affinity column of monoclonal antibody. The toxin is a basic polypeptide with an isoelectric point at pH 9.1, and devoid of mannosides. It is composed of 88 amino acid residues with a molecular size of 10 721 Da. The monoclonal antibodies could be applicable to the analysis of biologically active sites on the toxin, in an attempt to synthesize chemically a small peptide with killer activity and little immunogenicity.

Amino Acid Sequence↗