Search PubMed⌕ Search

Biomedical subjects

S Asano

Publications and source records attributed to S Asano.

At least 289 records · Page 16Linked to original sources
PubMed1994

C-terminal topology of gastric H+,K(+)-ATPase.

An antibody was prepared against a peptide corresponding to residues 1024-1034 (the putative C-terminus) of the alpha-subunit of hog gastric H+,K(+)-ATPase. The antibody bound to a 95 kDa band of H+,K(+)-ATPase that was solubilized in SDS, but not to that of Na+,K(+)-ATPase. It also bound to products of tryptic digestion that included C-terminal fragments of the H+,K(+)-ATPase alpha-subunit. The same amount of the antibody bound to both intact (tight) and lyophilized (leaky) inside-out gastric vesicles, indicating that its epitope is present on the cytosolic side of the vesicles. This finding was further confirmed by using fluorescence-immunolocalization techniques and streptolysin-O to permeabilize newt oxyntic cells. Stimulation of isolated newt oxyntic cells with dibutyryl cyclic AMP induces fusion of tubulovesicles with the apical membrane, so that the luminal domains of the H+,K(+)-ATPase alpha-subunit directly face the cell-suspension medium. The antibody did not bind to the stimulated intact cell, but bound to cells permeabilized with streptolysin-O, indicating that it binds from the cytoplasmic side to the C-terminus of the H+,K(+)-ATPase alpha-subunit in apical and tubulovesicular membrane, and also that the H+,K(+)-ATPase alpha-subunit has an even number of transmembrane domains.

Amino Acid Sequence↗
PubMed1994

Molecular cloning and characterization of G-CSF induced gene cDNA.

G-CSF (granulocyte colony-stimulating factor) is known to specifically stimulate the production and the functional activation of neutrophils. To investigate the intracellular signaling pathway of myeloid cells stimulated by G-CSF, we isolated new genes whose expression was induced by G-CSF. First of all, we constructed lambda gt10 cDNA library from G-CSF-stimulated mononuclear cells (MNC) of a chronic myelogenous leukemia (CML) patient (CML-MNC) and screened the cDNA library by a differential hybridization method. The 24 candidate clones which specifically hybridized with G-CSF-stimulated CML-MNC cDNA probes, but not with unstimulated CML-MNC cDNA probes, were obtained after 8 x 10(4) individual clones had been screened. One of these clones, GIG-1 (G-CSF-induced gene-1), was further characterized. The size of the GIG-1 mRNA was about 0.9kb. The GIG-1 mRNA was expressed mainly in the myeloid leukemic cell lines.

Amino Acid Sequence↗
PubMed1994

Preferential usage of the bone-type leader sequence for the transcripts of liver/bone/kidney-type alkaline phosphatase gene in neutrophilic granulocytes.

Alkaline phosphatase in neutrophils (NAP) is a product of the liver/bone/kidney-type alkaline phosphatase gene, the chromosomal structure of which has recently been analyzed. The gene has two alternative leader sequences resulting in the two types of mRNA (liver-type and bone-type mRNAs), which suggests that the expression of the gene is regulated by independent promoters. To determine the mechanism underlying NAP induction, it is essential to know which type of the mRNAs is dominant in neutrophils. We adopted quantitative polymerase chain reaction method to determine the relative amount of bone-type mRNA in neutrophils. The bone-type mRNA was found to be at least 5 times more than the liver-type mRNA. mRNA of NAP is known to be induced by in vitro treatment of the cells with granulocyte colony-stimulating factor (G-CSF), which is enhanced by a simultaneous addition of retinoic acid. In neutrophils treated with G-CSF, the bone-type mRNA was at least 6 times more than the liver-type mRNA. In neutrophils treated by both G-CSF and retinoic acid, the bone-type mRNA was at least 22 times more than the liver-type mRNA. The results show that the bone-type mRNA is predominantly transcribed in peripheral neutrophils and in neutrophils cultured in vitro.

Alkaline Phosphatase↗
PubMed1994

Cultured rat astrocytes possess Na(+)-Ca2+ exchanger.

Na(+)-Ca2+ exchange activity in its reverse mode was demonstrated in cultured rat astrocytes. Combination of ouabain (1 mM) and monensin (20 microM) caused a marked increase in 45Ca2+ uptake in astrocytes. 45Ca2+ uptake was also stimulated by lowering the external Na+ concentration. Ouabain plus monensin-stimulated 45Ca2+ uptake was blocked by 3,4-dichlorobenzamil (IC50, 16 microM), an inhibitor of Na(+)-Ca2+ exchanger, but not by nifedipine (0.1 microM). The stimulated-45Ca2+ uptake was observed even in K(+)-free medium, and external K+ at 5-10 mM caused a 2.2-fold increase in the uptake. Microspectrofluorimetry using the Ca(2+)-sensitive dye fura-2 showed that ouabain plus monensin increased intracellular Ca2+ concentration in single astrocytes. The Ca2+ signal was dependent on external Ca2+ (EC50, 1.4 mM), and blocked by 20 microM 3,4-dichlorobenzamil, but not by Ca2+ channel blockers (Cd2+, 20 microM; Ni2+, 100 microM). Antiserum of cardiac Na(+)-Ca2+ exchanger recognized 160 and 120-135 kDa proteins on SDS-polyacrylamide gel electrophoresis of astrocyte homogenate. Northern blot analysis revealed the presence of mRNA for the exchanger protein in astrocytes. These findings indicate that Na(+)-Ca2+ exchanger which is modulated by K+ is present in cultured rat astrocytes.

Amiloride↗
PubMed1994

Effect of long-term cyclic mechanical load on protein synthesis and morphological changes in cultured myocardial cells from neonatal rat.

We studied the effect of prolonged cyclic mechanical stimulation on protein synthesis and morphological changes in cultured cardiac myocytes isolated from 3-day-old neonatal rats to develop an in vitro model for cardiac hypertrophy induced by a mechanical load. Myocardial cells were cultured on deformative culture plates with M-199 culture medium in the presence or absence of fetal calf serum (FCS), and a cyclic mechanical load was applied for 2 hours up to 15 days. Mechanical stimulation for 2 hours increased the 14C-phenylalanine incorporation rate of myocardial cells, both in the absence and presence of FCS or when the myocardial cells were either beating or arrested with tetrodotoxin. The incorporation rate always increased by mechanical stimulation during 15 days of cell culture as compared to cells that sustained no mechanical stress. The cell size and protein content, which increased gradually with mechanical stimulation and reached a maximum at 10 days, were even greater in the presence of FCS. Within 10 days myocardial cells had aligned in the direction of the maximal cyclic mechanical load. In these cells electron microscopy revealed an increase in the number of myofilaments associated with the development of mitochondria as recognized in the adult myocardial cells. These results indicate that long-term cyclic mechanical loading of cultured myocardial cells may be a good in vitro model for the study of cardiac hypertrophy.

Animals↗
PubMed1994

Cloning, heterologous expression, and localization of a novel crystal protein gene from Bacillus thuringiensis serovar japonensis strain buibui toxic to scarabaeid insects.

Recombinant Escherichia coli strains harboring pAG1, pAG2, pKBB100, and pKBB101 were cloned by using antiserum constructed against 130-kDa crystal protein antigen of Bacillus thuringiensis serovar japonensis strain Buibui. DNAs in the recombinant strains hybridized to the 26-base oligonucleotide probe corresponding to N-terminal amino acids of the 130-kDa crystal protein of strain Buibui. Cultures of the recombinant strains were toxic to larvae of the cupreous chafer, Anomala cuprea. Furthermore, the production of the 130-kDa polypeptide was demonstrated in the cells harboring pAG1 and pAG2 by immunoblot analysis with antiserum against the 130-kDa crystal protein. Southern hybridization analysis showed that the 130-kDa crystal protein gene is located on the chromosomal DNA of strain Buibui. On the other hand, DNA probes derived from cryIA(a) and cryIIIA genes did not hybridize to the DNA of strain Buibui.

Animals↗
PubMed1994

Reconstruction of an iliac crest defect with a bioactive ceramic prosthesis.

Between June 1987 and December 1990, an iliac crest prosthesis made of bioactive apatite- and wollastonite-containing glass ceramic (A-W.GC) was used in 60 patients for the reconstruction of the iliac crest defect after harvesting autogenous tricortical iliac bone graft. The clinical results of this prosthesis were satisfactory. No patients felt spontaneous pain in the reconstructed area, and 93% of the patients had no tenderness there. In the radiological evaluation at the final follow-up, no apparent "radiolucent clear zone" was detected at the prosthesis-iliac bone junction in 98% of the patients. Excellent new bone formation between the prosthesis and the iliac crest was also noticed in 96% of the patients. The A-W.GC iliac crest prosthesis was beneficial for reconstruction of the iliac crest defect.

Adolescent↗
PubMed1994

Involvement of the sympathetic nervous system in antihypertensive effect of cicletanine in salt-loaded young spontaneously hypertensive rats.

We examined the role of the sympathetic nervous system in the antihypertensive effect of long-term (4-week) administration of cicletanine (50 mg/100 g in diet) in young (6 week-old) spontaneously hypertensive rats (SHR) fed an 8.0% salt-containing diet. Salt loading accelerated the development of hypertension in young SHR (mean blood pressure [BP]: 158 +/- 3 v 196 +/- 5 mm Hg, P < .01). Although cicletanine did not affect mean BP in non-salt-loaded SHR, it reversed salt-induced hypertension (155 +/- 3 mm Hg, P < .01). Salt loading elevated plasma norepinephrine (NE) (246 +/- 16 v 451 +/- 87 pg/mL, P < .05) but simultaneous administration of cicletanine inhibited the increase in plasma NE with salt loading (234 +/- 12 pg/mL, P < .01). Hexamethonium, a ganglionic blocking agent, produced a greater hypotensive effect in salt-loaded than in non-salt-loaded SHR (-40 +/- 4 v -78 +/- 4 mm Hg, P < .01). In salt-loaded SHR with cicletanine, however, the hypotensive effect of hexamethonium was suppressed compared with salt-loaded SHR without cicletanine (-52 +/- 4 mm Hg, P < .01). Both plasma NE (r = 0.608, P < .01) and decrease in mean BP with hexamethonium (r = -0.798, P < .01) correlated with baseline mean BP. Thus, cicletanine inhibited the salt-induced rise in mean BP of young SHR, possibly through the suppression of enhanced sympathetic nerve activity.

Animals↗
PubMed1994

Monoclonal antibody HK4013 recognizes an epitope specific for gastric subtype of H+,K(+)-ATPase.

Monoclonal antibody HK4013 raised against hog gastric vesicles dose-dependently inhibited gastric H+,K(+)-ATPase activity, formation of phosphoenzyme from ATP, and proton uptake into gastric vesicles. This antibody did not cross-react with related P-type ATPases such as hog kidney Na+,K(+)-ATPase or rabbit sarcoplasmic reticulum Ca(2+)-ATPase. It did not bind to the solubilized gastric H+,K(+)-ATPase, indicating that this antibody recognizes a higher-order structural epitope. The epitope is present on the cytosolic surface of H+,K(+)-ATPase. The addition of K+ to a solution containing gastric H+,K(+)-ATPase decreased the fluorescence intensity of the enzyme labeled with fluorescein isothiocyanate (FITC), showing the conformational transition from the E1 to E2K+ form. When H+,K(+)-ATPase was preincubated with HK4013, the addition of K+ did not decrease but increased the FITC fluorescence, indicating that this antibody changed the conformational state, at least near the ATP binding site. This is in contrast with the case of monoclonal antibody HK4001, which inhibited the decrease of the fluorescence. The fact that these two antibodies recognize different epitopes is consistent with previously reported facts that monoclonal antibody HK4001 inhibits the ouabain-insensitive K(+)-ATPase activity of rat distal colon but antibody HK4013 does not, and that the former stains the rabbit distal H+,K(+)-ATPase but the latter does not.

Animals↗
PubMed1994

Characterization of larvicidal toxin protein from Bacillus thuringiensis serovar japonensis strain Buibui specific for scarabaeid beetles.

The delta-endo toxin proteins from Bacillus thuringiensis which kill the larvae of various scarabaeid beetles such as Anomala cuprea, A. rufocuprea and Popillia japonica were purified by DEAE ion exchange chromatography. A protein with a molecular size of 130 kDa was purified. During the purification a minor peak was also detected which was estimated to be 67 kDa by SDS-PAGE. Both 130 and 67 kDa proteins showed larvicidal activity against A. cuprea. The lethal concentration of the 130 kDa protein which killed 50% of the larvae tested (LC50) against A. cuprea was 2 micrograms g-1 compost. A comparison by SDS-PAGE of the V8 protease digestion pattern of the 130 and 67 kDa larvicidal proteins showed that proteolytic resistant core peptides of approximately 60 kDa molecular size were resulted. The N-terminus amino acid sequence of the 130 and 67 kDa proteins was determined to be NH2-XXPNNQNEYEIIDAL and NH2-XSRNPGTFI, respectively, which is not identical to the sequence of CryIA, CryIB, CryIC and CryIII proteins.

Amino Acid Sequence↗
PubMed1994

Thymus aplasia in distal trisomy 14q syndrome: an autopsy case with a review of the literature.

The present authors report an autopsy case of a malformed male newborn with de novo duplication of the distal part of the long arm of chromosome 14 (14q24.1 to 14qter) in this paper. The partial trisomy of 14q was due to the unbalanced translocation at the end of the satellite stalk of chromosome 14. This autopsy case also had many kinds of external malformations including odd skull and facies, narrow thorax, and prominent calcaneus as well as retentio testis. The autopsy examination revealed aplasia of the thymus and marked hypoplasia of systemic lymphoid tissues. During an immunohistochemical study of the lymphoid tissues the population of T cells showed only a minority of lymphocytes. While several cases of distal trisomy 14q with cardiac malformations or a developmental abnormality of the thymus and the parathyroids seen in the third and fourth pouch defects have been reported previously, the present case was the first of this syndrome with aplasia of the thymus and systemic lymphoid hypoplasia.

Abnormalities, Multiple↗
PubMed1994

A case of pseudo-Bartter's syndrome due to intestinal malrotation.

Intestinal malrotation presenting beyond the neonatal period is associated with a multiplicity of symptoms, which are often non-specific and, consequently, are associated with delays in diagnosis. Pseudo-Bartter's syndrome, which mimics the manifestations of Bartter's syndrome, can be caused by a severe chloride deficiency secondary to vomiting, diarrhea, perspiration, diuretic abuse and so on. We describe a 6 year old boy who had been admitted to hospital three times during the preceding year. The patient lapsed into a critical condition with profound hypochloremia and hypokalemic metabolic alkalosis induced by extremely massive vomiting. The attacks of vomiting were spasmodic and self-limited. During the episodes of vomiting he fulfilled the criteria of pseudo-Bartter's syndrome, including hyperreninemia, hyperaldosteronism and normal blood pressure, but in the intervals between attacks he was completely asymptomatic. At the third admission, examination supported an overall clinical picture of bowel obstruction, which was confirmed by radiographic examination. Laparotomy revealed a midgut volvulus with intestinal malrotation. After surgery he made a good recovery and was symptom-free. In this patient, the high degree of hypochloremia and hypovolemia activated the renin-angiotensin-aldosterone system, then aldosterone promoted intensive reabsorption of sodium and excretion of potassium into the urine. Consequently the diagnosis of pseudo-Bartter's syndrome was establish on the basis of an extreme decrease in urinary chloride and an increase in urinary potassium concentration. It is relatively rare for vomiting due to intestinal malrotation to induce pseudo-Bartter's syndrome. The importance of considering this rare diagnosis in such cases is discussed.

Bartter Syndrome↗
PubMed1994

Activation of G protein-coupled K+ channels by dopamine in human GH-producing cells.

Dopamine (DA) inhibited the secretion of growth hormone (GH) from cultured human GH-secreting adenoma cells. The mechanism of this DA effect on these cultured cells was investigated with electrophysiological techniques. Under current clamp, DA (10(-6) M) hyperpolarized the membrane and arrested Ca(2+)-dependent action potentials. Voltage clamp experiments revealed that this membrane hyperpolarization was the result of a K+ conductance increase caused by DA. The current-voltage relationship of the DA-induced K+ current showed an inward-going rectification. Application of sulpiride (10(-6) M) abolished the DA-induced K+ current, indicating that the hyperpolarization was caused by the activation of D2-like receptors. Pertussis toxin (PTX) treatment eliminated the DA-induced K+ current as well as the DA-induced inhibition of GH secretion. An intracellular application of guanosine-5'-O-(3-thiotriphosphate) (100 microM) evoked a spontaneous increase in the K+ current in the absence of an agonist, and the application of DA did not further increase conductance. Intracellular application of guanosine-5'-O-(2-thiodiphosphate) (2 mM) inhibited the DA-induced K+ current. These results indicate that the DA-induced K+ channel is coupled to a G protein. When adenosine 3',5'-cyclic monophosphate (cAMP, 100 microM) was added to the patch-pipette solution, the DA-induced K+ current was still observed, indicating that the DA-induced K+ current was not caused by an inhibition of cAMP production.(ABSTRACT TRUNCATED AT 250 WORDS)

Dopamine↗
PubMed1994

A rise in antineutrophil cytoplasmic antibody in a patient with systemic vasculitis in remission.

We report a 42-year-old man who showed alveolar hemorrhage and glomerulonephritis as well as episcleritis and skin rash. He had an extremely high titer of cytoplasm-staining antineutrophil cytoplasmic antibody (C-ANCA) and was diagnosed as having systemic vasculitis based on histological findings of kidney and skin biopsies. After immunosuppressive therapy clinical manifestations resolved within several weeks and C-ANCA titers commensurably declined. C-ANCA titers, however, increased again and remained high despite clinical remission. In general, there is a close relationship between ANCA titers and clinical activities in ANCA-associated diseases, but they displayed a large discrepancy in this patient. Indeed, the serum of the patient in remission contained the antibody against 29-kD neutrophil extracts which was detected by immunoblot analysis. These findings suggest that C-ANCA may not necessarily be, by itself, pathogenetic for the development of the vasculitis.

Adult↗
PubMed1994

Racemization: its biological significance on neuropathogenesis of Alzheimer's disease.

Amyloid beta protein (A beta) in neuritic plaques of Alzheimer's disease has been found to be racemized and/or isomerized at their Asp residues. To elucidate the effect of racemization on the aggregation properties of A beta, we synthesized three kinds of A beta peptides in which D-Asp was substituted for L-Asp residues, i.e, normal A beta 1-40, [D-Asp7]A beta 1-40 and [D-Asp23]A beta 1-40. The aggregation and fibril formation of each peptide was examined by means of spectrofluorometry and electron microscopy. Of the three peptides, normal A beta showed the gradual increase of aggregation while [D-Asp7]A beta 1-40 and [D-Asp23] A beta 1-40 showed more enhanced aggregation at the final stage when the fibril formations were detected in all peptides solutions by electron microscopy. A comparative immunohistochemical study by anti-racemized A beta antibody and anti-A beta 1-42/43 antibody further showed the in vivo incorporation of D-Asp in senile plaques of Alzheimer's disease brains, which may be involved in plaque formation at the later stage than the deposition of the longer form of A beta (A beta 1-42/43). Taken together with the recent accumulated evidence on the aggregation mechanisms of A beta, the data presented here suggest that racemization may occur after the amyloid fibril formation but enhance the aggregation process by shifting the equilibrium of A beta from the soluble form to the insoluble form in Alzheimer's disease.

Alzheimer Disease↗
PubMed1994

Richter's syndrome showing pronounced lymphadenopathy in response to administration of granulocyte colony-stimulating factor.

A patient with Richter's syndrome developed rapid generalized lymph node enlargement with a decrease of peripheral blood lymphocytes after recombinant human granulocyte colony-stimulating factor (rhG-CSF) therapy for neutropenia induced by chemotherapy. The lymphadenopathy subsided spontaneously following discontinuation of rhG-CSF medication. Reinstitution of rhG-CSF therapy was followed by the same response as during initial therapy. Histopathologically, the lesions were characteristic of diffuse large cell lymphoma (DLL) with no evidence of myeloid cell involvement. No spontaneous contraction of enlarged lymph nodes followed withdrawal of the second course, but the enlargement subsided with chemotherapy. The patient died of myocardial infarction. All residual tumors examined post mortem presented microscopic features of small lymphocytic lymphoma (SLL), and G-CSF receptor was demonstrated on these neoplastic cells by Northern blot hybridization analysis. This observation indicates that some B cell malignancies may retain G-CSF receptor and respond to G-CSF.

Aged↗