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Biomedical subjects

H Sakai

Publications and source records attributed to H Sakai.

At least 829 records · Page 46Linked to original sources
PubMed1991

Inhibitions of acid secretion by E3810 and omeprazole, and their reversal by glutathione.

A substituted benzimidazole ([4-(3-methoxypropoxy)-3-methylpyridine-2-yl]methylsulfinyl)- 1H-benzimidazole sodium salt (E3810), is a gastric proton pump (H+, K(+)-ATPase) inhibitor. E3810 and omeprazole inhibited acid accumulation dose dependently as measured with aminopyrine uptake in isolated rabbit gastric glands, their IC50 values being 0.16 and 0.36 microM, respectively. The addition of exogenous reduced glutathione (GSH) to the gland suspension reactivated dose dependently the acid secretion which had been inhibited by 2 microM E3810 or omeprazole as a function of the incubation time. Furthermore, GSH at 1 and 3 mM reversed the antisecretory effect of E3810 more quickly than it did that of omeprazole. The antisecretory effect of E3810 was slightly greater than that of omeprazole in histamine-stimulated fistula dogs in vivo. The duration of the antisecretory activity of E3810 at concentrations of 2 and 4 mg/kg was shorter than that of omeprazole at the same concentrations in pentagastrin-stimulated fistula dogs. The reversal of the antisecretory activity of the inhibitors in dogs is suggested to be due to the action of endogenous extracellular GSH, in addition to de novo synthesis of the proton pump, because bullfrog gastric mucosae were found in the present study to secrete GSH into the mucosal solution at the rate of about 0.25 nmol/min/g tissue.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1991

Development of tyrosine hydroxylase-like immunoreactive structures in the chick retina: three-dimensional analysis.

This study was designed to investigate the developmental profile of tyrosine hydroxylase-like immunoreactive structures in the chick retina in both frozen sections and wholemount preparations. In frozen sections, cells with tyrosine hydroxylase-like immunoreactivity were first detected in 10 to 15 cell rows from the innermost part of the inner nuclear layer on embryonic or incubation day 11. They were seen in the inner cell rows of the inner nuclear layer during later periods; by embryonic day 18, the immunoreactive cells were located 1 to 3 cell rows outward from the innermost part of the inner nuclear layer where mature immunoreactive cells mainly exist. The immunoreactive cells began to give rise to processes on embryonic day 13. The processes (possibly dendrites) gradually increased in number and intensity in sublayers 1 and 4 of the inner plexiform layer during prenatal life. Several days after hatching, an abrupt increase in immunoreactive processes was noted in sublayer 1 but not in sublayer 4. On the sixth postnatal day, retinal neural elements immunoreactive for tyrosine hydroxylase seemed to exhibit a distribution pattern similar to that of the adult chick. In wholemount retinas, immunoreactive cells were initially detected at the earliest stage of embryonic day 12 in a small circle termed "starting area" occupying the ventral part of the temporal retinal field. The closer to the "starting area," the earlier the retinal area began to express many immunoreactive cells. Thus tyrosine hydroxylase cell density in individual retinal areas, as represented by cell number per square millimeter, peaked in different developmental periods varying from embryonic day 12 to day 14. At this stage, immunoreactive cells were arranged irregularly in the retina. Thereafter, the cell density as well as total cell number gradually declined and reached a plateau around embryonic day 20 when tyrosine hydroxylase-like immunoreactive cells, like those in the mature retina, showed an even distribution throughout the retina.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Inhibition of actin polymerization by a synthetic dodecapeptide patterned on the sequence around the actin-binding site of cofilin.

Cofilin is an F-actin side-binding and -depolymerizing protein with an apparent molecular mass of 21 kDa. By means of the end label fingerprinting method, the amino acid residue on cofilin sequence cross-linked to actin by zero length cross-linker, 1-ethyl-3-(3-dimethylamino propyl)carbodiimide, was identified as Lys112 and/or Lys114. A synthetic dodecapeptide patterned on the sequence around the actin-cross-linking site of cofilin (Trp104-Met115) inhibited the binding of cofilin to actin. Moreover, the dodecapeptide was found to be a potent inhibitor of actin polymerization. Thus, we conclude that the dodecapeptide sequence constitutes the region essential for the actin-binding and -depolymerizing activity of cofilin. A sequence similar to the dodecapeptide is found in other actin-depolymerizing proteins, destrin, actin-depolymerizing factor, and depactin. Therefore, the dodecapeptide sequence may be a consensus sequence essential for actin-binding and -depolymerizing activity in actin-depolymerizing proteins.

Actin Depolymerizing Factors↗
PubMed1991

Functional analyses of the domain structure of microtubule-associated protein-4 (MAP-U).

Bovine microtubule-associated protein-4 (MAP-4), which was previously named MAP-U, consists of an amino-terminal projection domain (N-domain) and a carboxyl-terminal microtubule-binding domain (C-domain) (Aizawa, H., Emori, Y., Murofushi, H., Kawasaki, H., Sakai, H., and Suzuki, K. (1990) J. Biol. Chem. 265, 13849-13855). The C-domain contains a region rich in proline (Pro-rich region) and a region containing four assembly-promoting sequences (AP sequence region) which is shared by MAP-2 and tau. We purified a series of truncated fragments of MAP-4 expressed in Escherichia coli. An N-domain fragment did not bind to microtubules, while a C-domain fragment promoted microtubule assembly. Both of the fragments corresponding to the Pro-rich region (P fragment) and the AP sequence region (A4 fragment) promoted tubulin polymerization, although the A4 fragment had lower activity than intact MAP-4 and P fragment. A4 fragment produced morphologically normal microtubules whereas P fragment produced abnormal microtubules such as duplex microtubules and tight bundles of microtubules with diverse diameters. We concluded that both Pro-rich and AP sequence regions take part in the promotion of tubulin polymerization, and that the former is important for the MAP to bind to microtubules with high efficiency and the latter is essential for the formation of microtubules with normal morphology.

Amino Acid Sequence↗
PubMed1991

Crystallization and characterization of a lectin obtained from a mushroom, Aleuria aurantia.

A fucose-specific lectin with a unique sugar recognizing property was purified from an orange peel mushroom, Aleuria aurantia, by using a specific affinity adsorbent prepared from L-fucose and starch. From 100 g of fruiting bodies, 145 mg of pure lectin was obtained. The lectin was crystallized and the crystals showed hexagonal bipyramid in shape. Distribution of hydrophobic and hydrophilic regions in the molecule of this lectin was predicted from the amino acid sequence deduced from the previously reported nucleotide sequence of the lectin cDNA. Circular dichroism spectra revealed a very low content of alpha-helical and beta-sheet structures and a relatively high content of turns in this lectin. From the spectrum observed in the presence of L-fucose, a hapten sugar of this lectin, certain conformational change was assumed to occur.

Basidiomycota↗
PubMed1991

Regulation of glpD and glpE gene expression by a cyclic AMP-cAMP receptor protein (cAMP-CRP) complex in Escherichia coli.

The glpE gene of E. coli was found to be transcribed divergently with respect to glpD, which is adjacent to glpE head-to-head on the E. coli chromosome. We constructed glpD- and/or glpE-lacZ fusion plasmids, which provided glpD and lacZ as reporter genes. The expression of glpD and glpE, under the control of the cAMP-CRP complex, was examined by measuring the activities in E. coli cells of beta-galactosidase encoded by lacZ and glycerol-3-phosphate dehydrogenase encoded by glpD. In the double-reporter-gene system, the expression of glpD and glpE was found to be positively regulated by cAMP-CRP. We also confirmed that intracellular levels of the translation products and the transcripts from glpD and glpE were positively regulated by cAMP-CRP. The cAMP-mediated induction of gene expression of glpD and glpE was significantly affected by structural alterations of the single CRP-binding site between glpD and glpE. These results indicate that the single CRP-binding site is a cis-acting element involved in the positive regulation of the expression of both glpD and glpE at the transcriptional level.

Base Sequence↗
PubMed1991

In vitro effects on microtubule dynamics of purified Xenopus M phase-activated MAP kinase.

The protein kinase MAP kinase, also called MAP2 kinase, is a serine/threonine kinase whose activation and phosphorylation are induced by a variety of mitogens, and which is thought to have a critical role in a network of protein kinases in mitogenic signal transduction. A burst in kinase activation and protein phosphorylation may also be important in triggering the dramatic reorganization of the cell during the transition from interphase to mitosis. The interphase-metaphase transition of microtubule arrays is under the control of p34cdc2 kinase, a central control element in the G2-M transition of the cell cycle. Here we show that a Xenopus kinase, closely related to the mitogen-activated mammalian MAP kinase, is phosphorylated and activated during M phase of meiotic and mitotic cell cycles, and that the interphase-metaphase transition of microtubule arrays can be induced by the addition of purified Xenopus M phase-activated MAP kinase or mammalian mitogen-activated MAP kinase to interphase extracts in vitro.

Animals↗
PubMed1991

Fine structure of substance P-containing nerve fibers in the rat lateral septum; simultaneous localization in pre- and postsynaptic elements.

The fine structure of nerve fibers with substance P (SP)-like immunoreactivity in the rat lateral septum (LS) was investigated by preembedding immunoelectron microscopy. SP axon terminals frequently made synapses with non-immunoreactive neuronal soma and dendrites in the LS. Occasionally, two closely apposed nerve endings with SP immunoreactivity were presynaptic to the soma. A small number of immunopositive axon terminals formed synapses not only with neuronal perikarya but also with small dendrites in the vicinity of the perikarya. There were also some SP dendrites in contact with immunoreactive as well as non-immunoreactive nerve endings. These findings may provide a morphological basis for the complexity of SP actions on septal neurons.

Animals↗
PubMed1991

Functional division and reconstruction of a plasmid replication origin: molecular dissection of the oriV of the broad-host-range plasmid RSF1010.

Two single-stranded DNA initiation signals (designated ssi) present in the origin of vegetative DNA replication (oriV) of the broad-host-range plasmid RSF1010 are essential for the priming of replication of each complementary DNA strand of this plasmid in Escherichia coli. Each of the RSF1010 ssi signals, ssiA and ssiB, could be replaced by a primosome assembly site from plasmid pACY184 or from bacteriophage phi X174. In these chimeric origins, replication of the strand complementary to that containing the primosome assembly site was no longer dependent on the RSF1010 primase, protein RepB', but required the E. coli primase, DnaG. If both ssiA and ssiB sites of RSF1010 were replaced by primosome assembly sites, protein RepB' was no longer essential for the replication at this origin, whereas proteins RepA and RepC of RSF1010 were still required. These results strongly suggest that the two ssi sites and the RepB' protein actually direct the priming of DNA synthesis in the replication of RSF1010, and the proteins RepA and RepC are involved in the prepriming events--i.e., the opening of the DNA duplex at oriV. It is evident that the origin of RSF1010 can be separated into three functional domains and reconstructed by replacing the ssi sites with heterologous elements.

Base Sequence↗
PubMed1991

Xenopus M phase MAP kinase: isolation of its cDNA and activation by MPF.

MAP kinase is activated and phosphorylated during M phase of the Xenopus oocyte cell cycle, and induces the interphase-M phase transition of microtubule dynamics in vitro. We have carried out molecular cloning of Xenopus M phase MAP kinase and report its entire amino acid sequence. There is no marked change in the MAP kinase mRNA level during the cell cycle. Moreover, studies with an anti-MAP kinase antiserum indicate that MAP kinase activity may be regulated posttranslationally, most likely by phosphorylation. We show that MAP kinase can be activated by microinjection of MPF into immature oocytes or by adding MPF to cell-free extracts of interphase eggs. These results suggest that MAP kinase functions as an intermediate between MPF and the interphase-M phase transition of microtubule organization.

Amino Acid Sequence↗
PubMed1991

Immunohistochemical prostatic acid phosphatase level as a prognostic factor of prostatic carcinoma.

To determine whether prostatic acid phosphatase (PAP) immunoreactivity in prostatic adenocarcinoma is a reliable prognostic factor, the PAP immunohistochemical distribution has been examined in 78 prostatic carcinoma cases. The intensity of PAP immunostaining was graded from 0 to 2, and the scores of the primary and the secondary staining patterns were added to assess the extent of the PAP expression in needle biopsy specimens. As a result, a higher cancer-specific survival rate was observed in patients showing a greater PAP immunostaining (P less than 0.01). Further, a multivariate analysis was made of possible prognostic factors (age, stage, Gleason score, serum PAP, PAP-immunostaining score, and the initial treatment) to estimate the extent of their impact on cancer-specific survival. Results have confirmed that the difference in PAP immunoreactivity is an excellent, independent prognostic factor for prostatic carcinoma.

Acid Phosphatase↗
PubMed1991

Mitochondrial mutations restricting spontaneous translational frameshift suppression in the yeast Saccharomyces cerevisiae.

The +1 frameshift mutation, M5631, which is located in the gene (oxi1) for cytochrome c oxidase II (COXII) of the yeast mitochondrial genome, is suppressed spontaneously to a remarkably high extent (20%-30%). The full-length wild-type COXII produced as a result of suppression allows the mutant strain to grow with a "leaky" phenotype on non-fermentable medium. In order to elucidate the factors and interactions involved in this translational suppression, the strain with the frameshift mutation was mutated by MnCl2 treatment and a large number of mutants showing restriction of the suppression were isolated. Of 20 mutants exhibiting a strong, restricted, respiration-deficient (RD) phenotype, 6 were identified as having mutations in the mitochondrial genome. Furthermore, genetic analyses mapped one mutation to the vicinity of the gene for tRNA(Pro) and two others to a region of the tRNA cluster where two-thirds of all mitochondrial tRNA genes are encoded. The degree of restriction of the spontaneous frameshift suppression was characterized at the translational level by in vivo 35S-labeling of the mitochondrial translational products and immunoblotting. These results showed that in some of these mutant strains the frameshift suppression product is synthesized to the same extent as in the leaky parent strain. It is suggested that more than one +1 frame-shifted product is made as a result of suppression in these strains: one is as functional as the wild-type COXII, the other(s) is (are) nonfunctional and prevent leaky growth on non-fermentable medium. A possible mechanism for this heterogenous frameshift suppression is discussed.

Amino Acid Sequence↗
PubMed1991

Generation and characterization of the human immunodeficiency virus type 1 mutants.

Mutations were introduced by recombinant DNA techniques into 9 genes of an infectious molecular clone of human immunodeficiency virus type 1. The 24 mutants generated were characterized biochemically and biologically by transfection and infection experiments. None of the mutants which have mutations in gag (p17, p24, and p15 regions), pol (protease, reverse transcriptase, and endonuclease domains), env (gp120 region), tat, or rev were infectious, whereas vif, vpr, vpu, some of env (gp41) and nef mutants could grow in human CD4+ cells to various degrees. Of the non-infectious mutants, only endonuclease (pol) and gp41 mutants exhibited normal phenotypes with respect to the production of functional reverse transcriptase, the expression of gag, pol, and env proteins, and the generation of progeny virions, when examined in transient assays. All infectious mutants killed the CD4+ cells with the exception of a mutant carrying a defect in the vif gene.

Blotting, Western↗
PubMed1991

Bile acids in human plasma interfere with cholecystokinin bioassay using dispersed pancreatic acini.

A bioassay using dispersed pancreatic acini was used to measure fasting plasma cholecystokinin (CCK) concentrations in 105 patients with various kinds of gastrointestinal diseases, 17 patients with diabetes mellitus, and 6 healthy volunteers. High plasma CCK bioactivities were observed in patients with obstructive jaundice, choledocolithiasis, and primary biliary cirrhosis. Twenty-three samples with high CCK bioactivities were assayed by the same bioassay after the addition of a specific CCK antagonist and by a CCK radioimmunoassay in order to determine whether the high CCK-like bioactivity was due to circulating CCK or other factors. High CCK bioactivities were partially inhibited by the specific CCK antagonist, CR-1409, but the activities were not totally abolished. The residual bioactivities (not inhibited by CR-1409) correlated with plasma bile acid concentrations. The inhibitable CCK bioactivities correlated with plasma CCK levels obtained by radioimmunoassay. Although the bioassay using dispersed pancreatic acini has several advantages for measuring plasma CCK, this method overestimates CCK bioactivities in patients with high plasma bile acid concentrations.

Animals↗
PubMed1991

Malignant fibrous histiocytoma of the liver--a case report.

A case of surgically confirmed primary malignant fibrous histiocytoma of the liver is presented. A 35-year-old man was admitted to hospital with an epigastric mass. No abnormal laboratory findings, including tumor markers, were detected. Ultrasound and computed tomography showed the main tumor in the left lateral segment and a daughter nodule in the posterior segment of the liver. Arteriography demonstrated a slightly hypervascular mass in the left lateral segment. Histological examination of the resected tumor showed bundles of spindle cells with a focal storiform pattern, which were intermingled with bizarre giant cells, therefore a diagnosis of malignant fibrous histiocytoma was made.

Adult↗
PubMed1991

The use of the laryngeal mask airway in pediatric anesthesia.

Laryngeal mask airway (LMA) insertion was tried in 120 pediatric cases, from 2 months to 12 years of age. Initial indications for LMA were the same as for a face mask, except for two additional conditions; anticipation of difficulty with intubation and difficulty in management by a face mask. Size 2 LMA was used in the vast majority of cases. The insertion was successful on the first trial in 108 cases. More than one trial was necessary in 9 cases but only 3 cases required more than 3 trials. Insertion could not be completed in 3 cases. The relationship between the depth of LMA at the front teeth and age could be roughly described by "depth = 10 cm + 0.3 x Age". LMA was found to provide a better and more secure airway than the face mask without direct tracheal intervention. Heart rate did not increase with LMA insertion. It is easy to use and can be used in place of the face mask, but complications such as stomach air inflation due to too vigorous manual ventilation, slight pharyngeal injury, and airway obstruction due to kinking of LMA can occur. These complications can be avoided and must be kept in mind during it's use. LMA itself can be used to obtain a patent airway where an endotracheal airway is difficult to obtain. LMA-aided tracheal intubation can be extremely useful in obtaining endotracheal airways. Non-blind techniques can be used with LMA to increase safety. LMA is a very useful addition to pediatric anesthesia practice.

Journal Article↗