Search PubMed⌕ Search

Biomedical subjects

Y Ando

Publications and source records attributed to Y Ando.

At least 433 records · Page 24Linked to original sources
PubMed1993

Epidermal growth factor and insulin-like growth factor I enhance keratinocyte migration.

Although their mechanisms of action are unclear, a number of growth factors has been shown to promote cutaneous wound repair. Keratinocyte migration and proliferation are required for re-epithelialization, and there is evidence to suggest that these processes may be regulated by one or more growth factors that promote wound repair. Using the phagokinetic assay, which allows direct observation of migration path as a gold-particle-free area, we examined the effects of epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) on human keratinocyte migration. Addition of EGF to defined medium in the absence of any other growth factor induced an increase in migration of 2.5-4.5 fold after overnight incubation; the effect of EGF on migration was concentration dependent, with a maximum at 10 to 50 ng/ml EGF. Concentration-dependent enhancement of keratinocyte migration was similarly observed with IGF-I as well as insulin. With all factors, migration was observed on colloidal gold plates coated with collagen IV or with fibronectin but not in the absence of matrix coating. To examine further the involvement of the EGF receptor in keratinocyte migration, we tested the effect of a monoclonal antibody to the EGF receptor that acts as an antagonist. EGF-induced migration was completely prevented by this antibody; however, the enhancement by insulin or IGF-I was not blocked. These results suggest that IGF-I and insulin enhance keratinocyte migration by a mechanism distinct from that of EGF.

Cell Movement↗
PubMed1993

Differential alterations of dihydrofolate reductase gene in human leukemia cell lines made resistant to various folate analogues.

In order to clarify a molecular mechanism of folate resistance in leukemia cells, we studied alterations of the dihydrofolate reductase (DHFR) gene in a human leukemia cell line, MOLT-3, and its sublines made resistant to methotrexate (MTX), trimetrexate (TMQ) and N10-propargyl-5,8-dideazafolic acid (CB3717), alone or in combination. Major alterations of the DHFR gene were examined by Southern analysis of high-molecular-weight DNA. The presence of a base change (T-->C) at nucleotide position 91 of the DHFR gene, which is reported to be responsible for the reduced affinity of the enzyme for MTX in an MTX-resistant human colon carcinoma cell, was examined by allele-specific oligonucleotide hybridization. In a 10,000-fold MTX-resistant subline (MOLT-3/MTX10,000), the normal allele of DHFR gene had been amplified. In contrast, a 200-fold TMQ-resistant subline (MOLT-3/TMQ200) and a 30-fold CB3717-resistant subline selected from MOLT-3/TMQ200 (MOLT-3/TMQ200-CB-3717(30)) were shown to have the mutant allele. Furthermore, the mutant allele had been amplified in a 500-fold MTX-resistant subline, which was established by the continuous exposure of the MOLT-3/TMQ200 cells to stepwise increases of drug concentration and designated as MOLT-3/TMQ200-MTX500. On the other hand, a 40-fold-resistant subline to CB3717 alone (MOLT-3/CB3717(40)) showed the normal allele without amplification. These data suggest that complex alterations of the DHFR gene are involved in the molecular mechanisms of folate resistance that can be differentially introduced into leukemia cells by exposure to various folate analogues, alone or in combination.

Antineoplastic Agents↗
PubMed1993

Stereochemistry during aflatoxin biosynthesis: conversion of norsolorinic acid to averufin.

A reaction sequence, norsolorinic acid (NA)-->averantin (AVN)-->5'-hydroxyaverantin (HAVN)-->averufin (AVR), is the early part of a biosynthetic pathway for aflatoxins. In this study, we determined the stereochemical relationship among these metabolites by using chiral high-performance liquid chromatography. In cell-free experiments using the cytosol fraction of Aspergillus parasiticus NIAH-26, (1'S)-AVN was exclusively produced from NA in the presence of NADPH. Also, only (1'S)-AVN, and not (1'R)-AVN, served as a substrate for the reverse reaction from AVN to NA. When the microsome fraction of NIAH-26 was incubated with (1'S)-AVN in the presence of NADPH, two HAVN diastereomers and one AVR enantiomer were formed, whereas these substances were never produced from (1'R)-AVN. Moreover, (1'S,5'R)-AVR was exclusively formed from both HAVN diastereomers by the cytosol fraction in the presence of NAD. The feeding experiments using this mutant showed that aflatoxins were produced from (1'S,5'R)-AVR but not from (1'R,5'S)-AVR. These results indicate that the enzymes involved in this pathway show strict stereospecificity to their substrates and that the configuration of (1'S,5'R)-AVR leading to the formation of aflatoxins is due to the stereospecificity of NA dehydrogenase which catalyzes the reaction between (1'S)-AVN and NA.

Aflatoxins↗
PubMed1993

Functional evidence for an apical V1 receptor in rabbit cortical collecting duct.

In the rabbit cortical collecting duct (CCD) perfused in vitro, we recently found that luminal arginine vasopressin (AVP) hyperpolarizes the transepithelial voltage (Vt) and inhibits the hydrosmotic effect of basolateral AVP. The present study was undertaken to characterize the apical receptor of the CCD for AVP. In contrast to AVP, luminal application of 1-desamino-8-D-arginine vasopressin (DDAVP), a V2 agonist, did not significantly induce hyperpolarization. Luminal oxytocin (OXT) hyperpolarized Vt, interfering with the effect of superimposed luminal AVP, whereas [Thr4,Gly7]OXT, an OXT agonist, did not reproduce the effect of OXT. The effects of luminal AVP and OXT were abolished by [d(CH2)5,Tyr(Me)]-AVP, a V1 antagonist. Finally, luminal applications of AVP metabolite neuropeptides, pGlu-Asn-Cys(Cys)-Pro-Arg and pGlu-Asn-Cys(Cys)-Pro-Arg-Gly-NH2, were without effect on Vt. These data suggest that luminal AVP induces hyperpolarization through an apical V1 receptor but not through a V2 receptor or an OXT receptor.

Amino Acid Sequence↗
PubMed1993

Secondary hypoplastic anemia in patients with familial amyloidotic polyneuropathy.

The anemia of patients with familial amyloidotic polyneuropathy (FAP) was evaluated. Anemia was seen in 32 (91%) of the 35 FAP patients, more often with progression of the disease. The incidence of macrocytic hypochromic anemia was the most common type (40%). In 14 autopsied and 2 biopsied cases, no amyloid deposition was detected in the bone marrow. Thirteen (81%) of the 16 FAP patients showed hypoplastic bone marrow. Bone marrow aspiration of 2 patients revealed a decreased ratio of erythrocytic/myelocytic cells. The plasma levels of vitamin B12 and folate were within normal ranges. Neither oral nor intravenous administration of iron had any effect on the anemia of FAP patients. Intravenous erythropoietin elevated blood hemoglobin levels and blood pressure in 2 patients. Orthostatic hypotension, one of the most common symptoms of FAP, was unexpectedly improved. Secondary hypoplastic anemia is common in FAP, but treatment of anemia in this disease using erythropoietin is promising.

Adult↗
PubMed1993

Phase I clinical and pharmacokinetic study of a 14-day infusion of etoposide in patients with lung cancer.

PURPOSE: A phase I study was conducted to determine the maximum-tolerated dose (MTD) of a 14-day continuous infusion of etoposide, and to evaluate the pharmacokinetics in patients with lung cancer. PATIENTS AND METHODS: Etoposide was administered continuously through a central venous catheter using a pump. The starting dose level was 300 mg/m2 over 14 days, with dose escalations of 100 mg/m2 over 14 days until unacceptable toxicities occurred. Pharmacokinetic studies were performed in all patients. RESULTS: Twenty-one patients, 20 with non-small-cell lung cancer and one with refractory small-cell lung cancer, received 37 courses. No World Health Organization (WHO) grade III or greater toxicity occurred at doses up to 400 mg/m2 over 14 days. At 700 mg/m2 over 14 days, all four patients experienced grade III or IV leukocytopenia, and two developed grade III stomatitis. No cumulative toxicity was observed. A steady concentration of etoposide was achieved 24 hours after the start of chemotherapy, and it was significantly correlated with surviving fractions of leukocytes (r = -.64, P = .001) and platelets (r = -.68, P < .001). The leukocyte count at the termination of chemotherapy predicted the nadir count (r = .93, P < .001). CONCLUSION: Steady blood levels of etoposide were maintained for prolonged periods, during 14-day continuous infusions. Leukocytopenia and stomatitis were dose-limiting. Nadir counts and surviving fractions of leukocytes were predicted by the leukocyte count at the end of chemotherapy and the concentration of etoposide, respectively. The recommended dose for phase II trials is 600 mg/m2 over 14 days.

Adult↗
PubMed1993

Effects of dose rate and energy level on fission neutron (252Cf) tumorigenesis in B6C3F1 mice.

The effects of the dose rate and the energy of fission neutrons using an iron block on tumorigenesis in B6C3F1 mice were examined. Six-week-old female animals were divided into 4 groups and exposes to 252Cf neutron irradiation at dose rates of 0.05 cGy/min, with (Group 1) or without (Group 2) filtering through a 10 cm thick iron block, 0.8 cGy/min (Group 3) or 0 (Group 4 controls). Total neutron exposure was 50 cGy in each of groups 1-3 and total irradiation dose was 56, 75 and 75 cGy in Groups 1-3, respectively. Total tumor incidences or multiplicity were significantly higher in Group 3 than in Group 1. A similar tendency was observed as compared to Group 2, ovarian and Harderian gland tumors being mainly affected and adrenal tumors were significantly higher in Group 2 than in Group 1. The results indicated a clear increase in tumorigenesis with the higher dose rate and no filtering influence of iron was evident, despite the drop in neutron energy level.

Animals↗
PubMed1993

Role of gastric digestion in the absorption of slowly digestible peptide, oligo-L-methionine, in rats.

Absorption of a slowly digestible peptide, oligo-L-methionine (OM), added to a low casein diet was faster than absorption of OM added to a low soybean protein isolate diet in early stages of feeding in chronic portal-cannulated rats. In the present study, the gastric digestion of 14C-labeled OM in rats fed a casein-based diet was higher than that in rats fed an soybean protein isolate-based diet 30 min and 3 hr after feeding. In rats with chronic bile-pancreatic juice diversion from the proximal small intestine, the higher gastric solubilization of OM in the stomach of the casein group was also observed, but the contents of soluble digest of OM in the stomach were lower than those in the normal rats. The portal absorption of OM in the casein group was higher than in the soybean protein isolate group both 30 min and 4 hr after feeding in the bile-pancreatic juice-diverted rats, and the difference of the portal absorption between the diet groups corresponded to the difference of the amount of solubilized OM in the upper small intestine; this, in turn, depends on pepsin digestion in the stomach. These findings suggest that the difference between the two diet groups in the ability to digest OM in the stomach can at least partly explain the higher portal absorption of OM in the casein group in the early stages of feeding.

Animals↗
PubMed1993

Effect of the angiotensin converting enzyme inhibitor, captopril, on proteinuria in chronic glomerular disease.

The antiproteinuric effect of the angiotensin-I-converting enzyme inhibitor, captopril, was studied in 14 patients (10 men and 4 women, age range of 24 to 60 years) with chronic glomerulonephritis in whom IgA nephritis had been confirmed by renal biopsy. Eight of the 14 patients had received antihypertensive drugs such as calcium channel blockers, diuretics or beta-blockers. Captopril was added to these regimens at 25 mg twice daily in 3 patients, and 37.5 mg in 11 patients. Proteinuria decreased from 2.55 +/- 0.48 g/day to 1.58 +/- 0.35 g/day within three months after the start of administration. In 4 patients (28.6%), the extent of reduction was over 50%, and in 8 patients (57.1%), over 25%. Blood pressure, creatinine clearance and serum creatinine were not changed significantly. There was a positive linear correlation between the extent of reduction of proteinuria and the increase in plasma renin activity (r = 0.93, p < 0.001). We conclude that captopril reduces proteinuria in some patients with IgA nephritis whose plasma renin activity responds to the drug.

Adult↗
PubMed1993

[Importance of primer selection in 5'NC region for the detection of hepatitis C virus RNA by polymerase chain reaction].

We compared two primer sets (A: 167bp, B: 269bp) derived from highly conserved domains within the 5' noncoding region (5'NC) of the hepatitis C virus (HCV) genome for their ability to detect HCV-RNA in a nested cDNA polymerase chain reaction assay (nested-PCR) in sera from 31 patients suspected of having HCV infection. Seventeen (54%) of 31 patients were positive for HCV-RNA with both primer sets. Using primer set A, 14(93%) of 15 samples with positive and 3(19%) of 16 samples with negative anti-HCV antibody test gave positive results for HCV-RNA. With primer set B, 15(100%) of 15 antibody positive samples and 2(13%) of 16 negative samples were positive for HCV-RNA. One antibody negative sample from a patient with alcoholic liver cirrhosis was positive for HCV-RNA only with primer set A. Another sample with positive antibody test, from a patient with chronic renal failure, was positive for HCV-RNA only with primer set B. A combination of more than one set of primers directed to the highly conserved 5'NC region, as well as proper selection of the exact nucleotide sequences, are important in improving the detection rate of HCV-RNA by PCR in serum of infected patients.

Base Sequence↗
PubMed1993

[Estimation of megakaryothrombopoiesis by mean platelet volume in leukemia patients during the course of chemotherapy and patients undergoing bone marrow transplantation].

The mean platelet volume (MPV) was measured in 14 patients with acute leukemia during the course of chemotherapy for remission induction and 21 patients undergoing bone marrow transplantation, in order to assess its usefulness as an indicator for megakaryothrombopoiesis at bone marrow suppression and recovery. In patients with acute leukemia, the MPV fell from 9.7 +/- 0.8 fl to 9.2 +/- 0.4 fl during the myelosuppression, and then it rose transiently to 10.2 +/- 0.5 fl and fell to 9.3 +/- 0.5 fl during recovery of platelet count. Similarly, in patients undergoing bone marrow transplantation, the MPV elevation was followed by the recovery of platelet count. Thus, when engraftment was defined as this MPV elevation, engraftment was confirmed significantly earlier by MPV (19.9 +/- 5.8 days) than by platelet count (24.8 +/- 6.7 days). MPV should be a useful indicator for engraftment or recovery from marrow aplasia in cases of acute leukemia and those of bone marrow transplantation.

Acute Disease↗
PubMed1993

[Detection of methicillin-resistant Staphylococcus aureus by in vitro enzymatic amplification of mecA and femA genes].

In the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection, rapid detection of MRSA is extremely important. The mecA gene codes the new drug resistant polypeptides called penicillin-binding protein 2a (PBP2a) or 2'(PBP2'), which mediates the clinically relevant resistance to all beta-lactam antibiotics. This gene could be beneficial in the detection of MRSA using the polymerase chain reaction (PCR). However, the identical mecA gene has been found in both coagulase-positive and coagulase-negative Staphylococcus with the appropriate methicillin-resistant phenotype. The second gene related to the expression of methicillin-resistance has been called femA. In this study, we amplified both mecA and femA genes by PCR in 97 strains and 32 clinical specimens. The mecA gene was positive in all 63(100%) MRSA strains and 2(6%) of the 34 methicillin-sensitive Staphylococcus aureus (MSSA) strains. Two strains with the methicillin-sensitive phenotype and the mecA gene resulted in methicillin-resistance when cultured on an agar plate containing 4.5% NaCl. The mecA gene was also present in all 10(100%) coagulase-negative Staphylococcus strains with the methicillin-resistant phenotype. The femA gene was positive in all 97(100%) MRSA and MSSA strains. On the other hand, the femA gene was absent from coagulase -negative Staphylococcus strains with the methicillin-resistant phenotype. Although the mechanism by which the product of femA gene influences the expression of methicillin-resistance is unknown, the gene appears to be restricted only in coagulase-positive Staphylococcus, regardless of methicillin-resistance. In conclusion, in vitro enzymatic amplification of both mecA and femA genes would lead to rapid and definite diagnosis of the MRSA infection.

Base Sequence↗
PubMed1993

[Detection of alterations of dihydrofolate reductase gene in folate-resistant leukemia cells by in vitro enzymatic amplification].

Three methods for analyzing the products of polymerase chain reaction were applied to detect complex alterations of dihydrofolate reductase (DHFR) gene, in order to assess their value in detection of folate-resistance in leukemia cells. A single point mutation in the second position of codon 31, a T-to-C transition, in trimetrexate (TMQ) resistant MOLT-3/TMQ200 cells was detected by either allele-specific oligonucleotide hybridization or restriction pattern of the PCR product. These two analyses allowed us to detect not only the presence of the mutation, but also the amplification of the mutated gene in TMQ-methotrexate (MTX) doubly-resistant MOLT-3/TMQ200-MTX500 cells. The base change was confirmed by direct sequencing method of the PCR product. Using these analyses of the PCR product, the complex alterations of DHFR gene are to be examined in leukemic patient cells.

Base Sequence↗