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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 325 records · Page 18Linked to original sources
PubMed1999

Prostaglandin E1 produces spasmolytic effects on histamine-induced bronchoconstriction in dogs.

OBJECTIVE: In this study, we evaluated the spasmolytic effect of intravenous prostaglandin (PG) E1 on histamine-induced bronchoconstriction with a direct visualization method using a superfine fiberoptic bronchoscope. SETTING: A university research laboratory. SUBJECTS: Mongrel dogs. INTERVENTIONS: The bronchial cross-sectional area (BCA) of mongrel dogs was measured by a direct visualization method using a superfine fiberoptic bronchoscope. Bronchoconstriction was elicited with histamine (H) infusion: 10 microg/kg iv bolus + 500 microg/kg/h continuous iv. The first protocol (n = 7) was designed to determine the effects of intravenous bolus of PGE1: 0 (saline), 0.01, 0.1, 1.0 and 10 microg/kg on H-induced bronchoconstriction. BCA was assessed before and 30 min after starting the H infusion and 5 min after each dose of intravenous PGE1. The second protocol was designed to determine whether continuous intravenous infusion of PGE1 reverses H-induced bronchoconstriction. In the PG group (n = 6), PGE1 was continuously infused at 0.1 microg/kg/min (20 mL/hr). In the control group (n = 6), saline was administered at a rate of 20 mL/hr iv. BCA was assessed before and 30 min after starting the H-infusion and at 5, 10, 30 and 60 min after commencing the PGE1 or saline infusion. Arterial blood was obtained simultaneously for measurement of plasma concentrations of epinephrine and norepinephrine by gas chromatography mass spectrometry. MEASUREMENTS AND MAIN RESULTS: In the first protocol, PGE1 produced a dose-dependent increase in the percentage of BCA and 10 microg/kg of PGE1 almost fully reversed the H-induced bronchoconstriction. Plasma catecholamines did not change significantly. In the second protocol, continuous infusion of PGE1 produced a time-dependent reversal of H-induced bronchoconstriction (percentage of BCA increased to 80.0+/-9.0% 60 min after the start of PGE1 infusion), whereas saline infusion did not reverse the bronchoconstriction. Plasma catecholamines did not change significantly in either group. CONCLUSIONS: Both intravenous bolus and continuous intravenous infusion of PGE1 reversed the H-induced bronchoconstriction. PGE1 may be used safely for patients with the hyperreactive airway and might be useful as a therapeutic agent for these patients.

Alprostadil↗
PubMed1999

Functional and binding studies of insurmountable antagonism of 606A, a novel AT1-receptor antagonist in rabbit tissues.

Angiotensin AT1-receptor antagonists can be classified into two types, surmountable and insurmountable ones, based on the way they inhibit angiotensin II (AII)-induced vasoconstriction. To elucidate the causes of the difference, we studied how several antagonists associate with and dissociate from AT1-receptor sites by using rabbit adrenal cortical membrane. Four antagonists, 606A, EXP3174, CV11974, and E4177, showed equipotent competitive antagonism when they were added simultaneous with [125I]-AII in binding experiments. However, in AII-induced contraction studies with rabbit aorta, 606A, EXP3174, and CV11974 inhibited the contraction noncompetitively, whereas E4177 inhibited competitively. The longer the pretreatment period with EXP3174 or CV11974, the more effectively the antagonists suppressed AII-induced contraction. However, the suppression of contraction by 606A and E4177 changed little with the length of the pretreatment period. AII-induced contraction of 606A- or E4177-treated aorta recovered easily by washout, but that of CV11974-treated aorta was hard to recover by washout. These results obtained in the aorta were consistent with their characteristics observed in the AII binding study in the rabbit adrenal cortical membrane in cases of EXP3174 and CV11974. The differences between association rate with and dissociation rate from the AT1 receptor of E4177 and 606A were slight, in spite of the clear difference between their action in the contraction study. Because of the variations observed with the four compounds, mechanisms of insurmountable antagonism may not be uniform among AT1-receptor antagonists.

Angiotensin II↗
PubMed1999

Epidermal growth factor-dependent dissociation of CrkII proto-oncogene product from the epidermal growth factor receptor in human glioma cells.

Human glioma cells frequently overexpress epidermal growth factor receptor (EGFR). We found that the CrkII proto-oncogene product was associated with the EGFR in human glioma cells in the absence of epidermal growth factor (EGF). EGF stimulation of glioma cells induced the phosphorylation of tyrosine 221 of the CrkII protein, which correlates with its dissociation from the EGFR. By contrast, Shc and Grb2 were inducibly associated with the EGFR in response to EGF stimulation of glioma cells. In A431 cells, epidermoid carcinoma cells which overexpress EGFR, CrkII was tyrosine-phosphorylated and associated with the EGFR in an EGF-dependent manner. Therefore, the dissociation of CrkII from the EGFR upon stimulation with EGF appears to be specific to glioma cells. The Cbl oncogene product was also tyrosine-phosphorylated in U87MG glioma cells upon EGF stimulation. However, unlike in other cell lines, CrkII was not inducibly bound to Cbl in U87MG glioma cells. Thus, EGF-dependent binding of CrkII to phosphotyrosine-containing proteins appears to be suppressed in glioma cells. To evaluate the physiological role of dissociation of CrkII from EGFR, we expressed the CrkII-23 mutant in glioma cells. CrkII-23 mutant, which was isolated as a suppressor gene of the EGF-dependent transformation of NRK cells, binds constitutively to EGFR. We found that expression of CrkII-23 inhibited the anchorage-independent growth of the glioma cells in the presence of EGF. Taken together, these data implicate EGF-dependent dissociation of CrkII from EGFR in the oncogenicity of human glioma cells.

Cell Adhesion↗
PubMed1999

[Use of a rapid detection assay for influenza virus, on nasal aspirate specimens].

We investigated the usefulness of a rapid antigen detection kit using optical immunoassay for influenza virus (FLU OIA, BioStar, USA). Nasal aspirates were taken from 92 influenza suspected outpatients between March to April of 1999. Compared with virus isolation and PCR, the sensitivity of FLU OIA was 88.5% and 81.6%, and the specificity was 65.2% and 72.2%. All isolated viruses were influenza type B virus. It was difficult to differentiate the weak-positive and negative cases, leading to the rather low specificity, although the assay procedure was easy and quick. FLU OIA may be a useful rapid diagnosis kit for influenza in pediatric outpatient clinics and wards, because it can detect both influenza type A and type B viruses.

Antigens, Viral↗
PubMed1999

ADP-ribosylation as an intermediate step in inactivation of rifampin by a mycobacterial gene.

Mycobacterium smegmatis DSM43756 inactivates rifampin, and the inactivated antibiotic product recovered from culture medium was ribosylated on the 23-OH group. To study this process, the gene responsible for the inactivation was expressed at high levels by the lac promoter in Escherichia coli conferring resistance to >500 microg of antibiotic per ml. Cell homogenates generated a novel derivative designated RIP-TAs; in this study, we determined that RIP-TAs is 23-(O-ADP-ribosyl)rifampin. Our results indicated that RIP-TAs is an intermediate in the pathway leading to ribosylated rifampin and that the previously characterized gene encodes a mono(ADP-ribosyl)transferase which, however, shows no sequence similarity to other enzymes of this class.

ADP Ribose Transferases↗
PubMed1999

Functional characteristics of basolateral peptide transporter in the human intestinal cell line Caco-2.

The apical H+-coupled peptide transporter (PEPT1) and basolateral peptide transporter in human intestinal Caco-2 cells were functionally compared by the characterization of [14C]glycylsarcosine transport. The glycylsarcosine uptake via the basolateral peptide transporter was less sensitive to medium pH than uptake via PEPT1 and was not transported against the concentration gradient. Kinetic analysis indicated that glycylsarcosine uptake across the basolateral membranes was apparently mediated by a single peptide transporter. Small peptides and beta-lactam antibiotics inhibited glycylsarcosine uptake by the basolateral peptide transporter, and these inhibitions were revealed to be competitive. Comparison of the inhibition constant values of various beta-lactam antibiotics between PEPT1 and the basolateral peptide transporter suggested that the former had a higher affinity than the latter. A histidine residue modifier, diethyl pyrocarbonate, inhibited glycylsarcosine uptake by both transporters, although the inhibitory effect was greater on PEPT1. These findings suggest that a single facilitative peptide transporter is expressed at the basolateral membranes of Caco-2 cells and that PEPT1 and the basolateral peptide transporter cooperate in the efficient transepithelial transport of small peptides and peptidelike drugs.

Caco-2 Cells↗
PubMed1999

Prevalence of hepatitis G virus in liver disease.

The prevalence of hepatitis G virus (HGV) in liver disease of non-A, -B, -C viral hepatitis, hepatitis B and hepatitis C was determined. Two of 44 patients (4.5%) with liver injury without any hepatitis A, B or C marker were positive for HGV. One of five cases of hepatocellular carcinoma was positive for HGV. One of three cases with fulminant hepatitis was positive for HGV. This case was negative at the onset of fulminant hepatitis and became positive after plasmapheresis. No patient with acute (n=8) or chronic (n=5) hepatitis or liver cirrhosis (n=8) was positive for HGV in non-A, -B, -C liver disease. One of 30 patients with various HBV-positive liver diseases and nine (17.3) of 52 patients with type C liver disease were positive for HGV. In patients with hepatitis C, four (28.6%) of 14 HGV-co-infected patients were complicated with diabetes mellitus compared with four (10.5%) of 38 single hepatitis C virus (HCV)-infected patients (not significant). In 12 HGV-positive patients, eight of 10 (80%) had a history of blood transfusion. In HCV-positive patients, co-infection with HGV was not a risk factor in patients with diabetes mellitus as a complication. HGV appeared to cause non-A, -B, -C hepatitis rarely, and its main route of infection was blood transfusion.

Adolescent↗
PubMed1999

CREB-independent regulation by CBP is a novel mechanism of human growth hormone gene expression.

Hypothalamic growth hormone-releasing hormone (GHRH) stimulates growth hormone (GH) gene expression in anterior pituitary somatotrophs by binding to the GHRH receptor, a G-protein-coupled transmembrane receptor, and by mediating a cAMP-mediated protein kinase A (PKA) signal-transduction pathway. Two nonclassical cAMP-response element motifs (CGTCA) are located at nucleotides -187/-183 (distal cAMP-response element; dCRE) and -99/-95 (proximal cAMP-response element; pCRE) of the human GH promoter and are required for cAMP responsiveness, along with the pituitary-specific transcription factor Pit-1 (official nomenclature, POU1F1). Although a role for cAMP-response element binding protein (CREB) in GH stimulation by PKA has been suggested, it is unclear how the effect may be mediated. CREB binding protein (CBP) is a nuclear cofactor named for its ability to bind CREB. However, CBP also binds other nuclear proteins. We determined that CBP interacts with Pit-1 and is a cofactor for Pit-1-dependent activation of the human GH promoter. This pathway appears to be independent of CREB, with CPB being the likely target of phosphorylation by PKA.

Base Sequence↗
PubMed1999

Serum concentration of 20K human growth hormone (20K hGH) measured by a specific enzyme-linked immunosorbent assay. Study Group of 20K hGH.

Several GH isoforms have been identified in pituitary and serum, the most abundant of which is the 22K human GH (hGH) isoform. The 20K hGH isoform is produced by alternative splicing of GH messenger ribonucleic acid and comprises approximately 10% of all GH in the pituitary. The physiological role of 20K hGH remains to be determined, partly because of the lack of a simple and specific assay. We have established sensitive enzyme-linked immunosorbent assays (ELISAs) specific to 20K and 22K hGH. To determine whether regulation of 20K hGH secretion is the same as that for 22K hGH, we measured serum concentrations of both species of hGH in normal subjects and patients with a variety of endocrine disorders. The serum levels of 20K hGH after overnight fasting was 118 +/- 178 pg/mL (n = 282) in normal women, significantly higher than that in normal men (64 +/- 170 pg/mL; n = 226). However, there was no difference in the proportion of 20K hGH to 20K plus 22K hGH between men (6.3 +/- 2.6%, mean +/- SD; n = 176) and women (6.3 +/- 2.1%; n = 263). No correlation was detected between the ratio of 20K hGH and age, body height, body weight, or body fat mass in normal subjects. The proportion of 20K hGH was significantly (P < 0.001) higher in patients with active acromegaly (9.2 +/- 2.2%; n = 33) and patients with anorexia nervosa (9.0 +/- 1.9; n = 8), both of which are characterized by chronic elevation of circulating GH levels. The proportion of 20K hGH in successfully treated acromegalic patients did not differ from that in normal subjects, suggesting that GH-producing pituitary tumors secrete a higher proportion of 20K hGH, or that a chronic excess of 22K hGH alters the MCR of 20K hGH. The values in patients with adult GH deficiency, hyperthyroidism, primary hypothyroidism, or GH-independent short stature did not differ from those in normal subjects. The 20K ratio did not change after acute GH provocative tests, such as the insulin tolerance test and the GHRH test. These results suggest that secretion of 20K hGH from the pituitary is under the same control as that of 22K hGH. This new assay may provide a tool for understanding the physiological or pathophysiological role of the 20K hGH isoform.

Acromegaly↗
PubMed1999

Serum levels of 20-kilodalton human growth hormone (GH) are parallel those of 22-kilodalton human GH in normal and short children.

Twenty-kilodalton human GH (20K), which is one of the human GH (hGH) variants, is thought to be produced by alternative premessenger ribonucleic acid splicing. However, its physiological role is still unclear due to the lack of a specific assay. We have measured serum 20K and 22-kDa hGH (22K) by specific ELISAs to investigate the physiological role of 20K in children. The subjects were 162 normal children, aged 1 month to 20 yr; 12 patients with GH deficiency (GHD), aged 11 months to 13 yr; 57 children with non-GHD short stature, aged 2-17 yr; and 13 girls with Turner's syndrome, aged 5 months to 15 yr. Samples were collected at random from normal children and were collected after hGH provocative tests and 3-h nocturnal sleep from GHD, non-GHD short stature, and Turner's syndrome children. The mean basal serum concentrations of 22K and 20K were 2.4 +/- 2.8 ng/mL and 152.3 +/- 184.0 pg/mL in normal boys and 2.5 +/- 3.1 ng/mL and 130.6 +/- 171.5 pg/mL in normal girls, respectively. The percentages of 20K (%20K) were 5.8 +/- 2.1% and 6.0 +/- 3.2% in 83 normal boys and 79 normal girls, respectively. There was no significant difference in %20K either among ages or between the prepubertal stage and the pubertal stage in normal boys and girls. The mean %20K values in basal samples of provocative tests in 12 patients with GHD, non-GHD short stature, and Turner's syndrome were 6.5 +/- 2.4%, 6.5 +/- 3.8%, and 5.9 +/- 3.2%, respectively. There was no significant difference in %20K among normal children and these growth disorders, and there was no significant difference in %20K throughout the hGH provocative tests and 3-h nocturnal sleep in these growth disorders. There was also no significant correlation between the percentage of 20K and the height SD score or body mass index in either normal children or subjects with these growth disorders. In conclusion, the %20K is constant, regardless of age, sex, puberty, height SD score, body mass index, and GH secretion status. The regulation of serum 20K levels remains to be established.

Adolescent↗
PubMed1999

Effects of fosfomycin and imipenem-cilastatin on the nephrotoxicity of vancomycin and cisplatin in rats.

The nephrotoxicity of vancomycin and cisplatin and the protective effects of fosfomycin and imipenem-cilastatin on renal function have been studied in rats. The renal clearance of vancomycin after the induction of renal dysfunction was also evaluated by calculating the glomerular filtration rate (GFR) and its secretory clearance. Plasma concentrations of creatinine and urea nitrogen increased dose-dependently after vancomycin injection. No such increases were observed after co-treatment with fosfomycin or imipenem-cilastatin. Changes of N-acetyl-beta-D-glucosaminidase activity in the urine of vancomycin-treated rats were not remarkable compared with those in cisplatin-treated animals. The reduced renal clearance of vancomycin in rats with acute renal failure induced by vancomycin was because of a decrease in both GFR and secretory clearance. However, the changes in GFR and secretory clearance were not proportional-the change in GFR was more pronounced than that of secretory clearance in the experimental groups. In addition, the renal clearance of vancomycin was maintained at the control level after co-administration of fosfomycin or imipenem-cilastatin with vancomycin. These results suggest that vancomycin impairs glomerular filtration more markedly than renal tubular function as compared with cisplatin. Co-administration with fosfomycin or imipenem-cilastatin confers significant protection against the nephrotoxic effects of vancomycin.

Acetylglucosaminidase↗
PubMed1999

Identification and immunological characterization of a novel 40-kDa protein linked to CD98 antigen.

Monoclonal antibodies (mAbs) were obtained from hybridoma clones established by cell fusion between mouse myeloma cells and spleen cells from a mouse immunized against an affinity-purified 40-kDa component of rat 125-kDa glycoprotein (GP125). Two mAbs designated as 3F2 and 6B4 detected a 40-kDa and a 125-kDa band under reducing and nonreducing conditions, respectively, in extracts prepared from rat, mouse and human tumor cells. Association of the 40-kDa protein with CD98 was revealed by sandwich-type enzyme-linked immunosorbent assay. The two mAbs were strongly reactive with various tumor cells and activated lymphocytes, but were only weakly reactive with resting lymphocytes. Confocal microscopy indicated colocalization of CD98 and the 40-kDa protein defined with 3F2 and 6B4 at the cell surface and perinuclear regions. On immunohistochemical analysis of frozen sections of rat tongue, the anti-rat CD98 mAb B3 selectively stained the basal layer and 3F2 stained the upper epithelial part in addition to the basal layer, indicating the existence of CD98-unlinked 40-kDa protein.

Animals↗
PubMed1999

Potent homophthalimide-type inhibitors of B16F10/L5 mouse melanoma cell invasion.

Recently, we developed a series of novel and potent aminopeptidase inhibitors with a homophthalimide skeleton. Among them, N-(2,6-diethylphenyl)homophthalimide (PIQ-22) possesses a specific aminopeptidase-inhibiting activity more potent than that of bestatin or actinonin, as assayed in terms of hydrolysis of L-alanine 4-methylcoumaryl-7-amide (Ala-AMC) by human acute lymphoblastic leukemia MOLT-4 cells. We show here that PIQ-22 and its 2,6-dimethylphenyl derivative (PIQ-11) are more potent inhibitors of tumor cell invasion than bestatin and actinonin in a Matrigel assay using mouse melanoma B16F10/L5 cells.

Aminopeptidases↗
PubMed1999

Construction of the single-chain Fv from 196-14 antibody toward ovarian cancer-associated antigen CA125.

The variable regions of heavy- and light-chains of mouse monoclonal antibody 196-14 toward ovarian cancer-associated antigen CA125 were linked with a peptide linker (GSTSGSGKSSEGKG) and a histidine tag was attached at the carboxyl terminal. This single-chain Fv (scFv) with a histidine tag was expressed in Escherichia coli as an inclusion body. The inclusion body was solubilized with guanidium chloride, followed by purification on nickel nitrilotriacetic acid agarose column and refolding into the active form. The scFv thus obtained bound to the Siso cells, which express CA125, and may recognize the same epitope as the parental 196-14 antibody IgG does.

Animals↗
PubMed1999

Modification by heme oxygenase inhibitor, tin protoporphyrin, of cellular differentiation of human myeloid leukemia K562 cell line.

Human myeloid leukemia K562 cells can be induced to differentiate to mature cells bidirectionally, i.e., hemin induces erythroid differentiation, while 12-O-tetradecanoylphorbol 13-acetate (TPA) induces differentiation to monocytes. TPA is also a potent inducer of heme oxygenase (HO), which catabolizes heme to biliverdin. We show here that TPA suppresses hemin-induced erythroid differentiation of K562 cells, while retinoids augment it. Further, an HO inhibitor, tin protoporphyrin (SnPP), suppresses TPA-induced K562 cell differentiation to monocytes. It was also found that co-treatment of K562 cells with SnPP and TPA induces erythroid differentiation of K562 cells, though SnPP alone or TPA alone does not induce erythroid differentiation, suggesting a role of HO in the directional switch of differentiation.

Cell Differentiation↗
PubMed1999

Retinoid X receptor-antagonistic diazepinylbenzoic acids.

Several dibenzodiazepine derivatives were identified as novel retinoid X receptor (RXR) antagonists on the basis of inhibitory activity on retinoid-induced cell differentiation of human promyelocytic leukemia cells HL-60 and transactivation assay using retinoic acid receptors (RARs) and RXRs in COS-1 cells. 4-(5H-2,3-(2,5-Dimethyl-2,5-hexano)-5-n- propyldibenzo[b,e][1,4]diazepin-11-yl)benzoic acid (HX603, 6c) is an N-n-propyl derivative of an RXR pan-agonist HX600 (6a), and exhibited RXR-selective antagonistic activity. Similar RXR-antagonistic activities were observed with 4-(5H-2,3-(2,5-dimethyl-2,5-hexano)-5-methyl- 8-nitrodibenzo[b,e][1,4]diazepin-11-yl)benzoic acid (HX531, 7a) and 4-(5H-10,11-dihydro-5,10-dimethyl-2,3-(2,5-dimethyl- 2,5-hexano)-dibenzo[b,e][1,4]diazepin-11-yl)benzoic acid (HX711, 8b), which also inhibited transactivation of RARs induced by an RAR agonist, Am80. These compounds inhibited HL-60 cell differentiation induced by the combination of a low concentration of the retinoid agonist Am80 with an RXR agonist (a retinoid synergist, HX600). These results indicated that HX603 (6c), and the related RXR antagonists inhibit the activation of RAR-RXR heterodimers as well as RXR homodimers, which is a distinct characteristic different from that of the known RXR antagonist, LG100754 (9).

Animals↗