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Biomedical subjects

Y Umeda

Publications and source records attributed to Y Umeda.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Pure red cell aplasia induced by erythromycin and furosemide effects on in vitro erythroid colony forming unit (CFU-E)].

A 84-year-old man was treated with antibiotics including erythromycin and a diuretic (furosemide) because of acute heart failure and pneumonia. During the treatment, he developed moderate anemia (Hb 8.7g/dl). His anemia improved after the treatment. He again developed marked anemia (Hb 6.3g/dl) during the second treatment with erythromycin and furosemide and received blood transfusions. Bone marrow aspiration study revealed severe erythroid hypoplasia (0.2%). He was referred to our hospital, but he was not treated because his hemoglobin levels and reticulocyte count increased (80%) and his bone marrow showed increased erythroblasts (41.5%). His anemia gradually improved without any treatment. We diagnosed the case as drug-induced pure red cell aplasia (PRCA). We cultured bone marrow cells obtained from the present case and four normal healthy volunteers by a plasma clot method to determine the effects of two drugs on the number of erythroid colony forming unit (CFU-E). Furosemide strongly inhibited the CFU-E colony formation in the patient, but the inhibition effect of erythromycin was moderate. Furthermore, CFU-E was markedly suppressed by a combination of erythromycin and furosemide in both patient and control materials. These results indicate that both furosemide and erythromycin were related to the occurrence of PRCA in this patient.

Aged↗
PubMed1993

Effects of anaesthesia on the removal from plasma of intravenously injected chylomicron-like lipid emulsions in rats and mice.

1. In order to find an anaesthesia with minimum perturbation to the metabolism of chylomicrons, the effects of seven different anaesthetic agents on clearance from plasma of chylomicron-like emulsions were compared. 2. Avertin, urethane, fentanyl, and a ketamine/xylazine mixture all slowed the removal from plasma of emulsion triolein and cholesteryl oleate. The steroid anaesthetic althesin slowed the clearance of emulsion cholesteryl oleate without affecting the removal from plasma of emulsion triolein. Nembutal when injected intravenously at a hypnotic dose did not affect the clearance of emulsion triolein or cholesteryl oleate, whereas at the anaesthetic dose, nembutal slowed the clearance rate of both labelled lipids. 3. Except for althesin, which did not affect the plasma clearance of triolein, fractional clearance rates of emulsion triolein and cholesteryl oleate calculated from blood samples taken during 12 min after injection were significantly slower in the anaesthetized groups compared with controls. However, with avertin, althesin, nembutal and ketamine/xylazine, amounts of radiolabelled triolein and cholesteryl oleate remaining in plasma 25 and 30 min after injection were comparable with the control. Radioactive lipids in plasma remained much higher in rats treated with urethane and fentanyl-fluanisonium even 30 min after injection. 4. Avertin was simple to administer and produced a suitable depth of anaesthesia for minor surgery, tail vein injections and blood sampling, whereas althesin and the ketamine/xylazine mixture required supplementary doses to maintain anaesthesia towards the end of the experiment. We concluded that anaesthesia is best avoided for studies of chylomicron clearance. Avertin is the preferred agent if anaesthesia must be used, for example in newborn rats or in mice.

Anesthetics↗
PubMed1993

Effect of probucol on plasma clearance and organ uptake of chylomicrons and VLDLs in normal and diabetic rats.

Probucol was given to rats made diabetic by streptozotocin. Compared with diabetic rats not receiving probucol or with nondiabetic rats, probucol lowered the plasma concentrations of triglycerides, phospholipids, cholesterol, and apolipoprotein B. The concentrations of serum chylomicrons and very low density lipoprotein (VLDL) were also reduced. In control and diabetic rats, probucol enhanced the clearance of endogenously radiolabeled VLDL from the plasma. Clearances from the plasma of rat lymph chylomicrons or chylomicron-like lipid emulsions were slow in diabetic rats. Probucol normalized chylomicron clearance in diabetic rats primarily by restoring hepatic uptake of remnants, which was decreased in diabetes. In diabetic rats, uptake of chylomicron remnants was increased in a number of extrahepatic tissues, including the heart and kidney. Probucol significantly decreased uptake in some extrahepatic tissues. Increased plasma clearance of VLDL and chylomicrons was associated with an increase in the apolipoprotein CII/CIII and apolipoprotein E/C ratios. Orally administered probucol was specifically incorporated into lymph chylomicrons, and clearance of probucol from the plasma exactly paralleled the clearance of chylomicron remnants, as traced with radiolabeled cholesteryl esters. Chylomicron-like emulsions incorporating probucol were exclusively cleared from the plasma by the liver in normal rats. We conclude that in streptozotocin diabetic rats, probucol is an effective hypolipidemic agent because it promotes the clearance of the triglyceride-rich lipoproteins.

Animals↗
PubMed1993

Isolation, structures, and antifungal activities of new aureobasidins.

Aureobasidins are a group of cyclic depsipeptides with antifungal activity and are produced by Aureobasidium pullulans. Aureobasidins are composed of eight amino acids and one hydroxy acid such as 2-hydroxy-3-methylpentanoic acid (Hmp), and highly lipophilic. Five new aureobasidins, S1, S2a, S2b, S3 and S4, which have higher hydrophilicity in reversed phase HPLC than the known aureobasidins A-R, were discovered in a fermentation broth of A. pullulans R106 by means of on-line liquid chromatography/mass spectrometry with electrospray ionization. We identified the structures of the compounds and studied their antifungal activities. Three of the new aureobasidins, S2b, S3 and S4, which have hydroxylated Hmp as the hydroxy acid, were highly active against Candida spp. and Cryptococcus neoformans.

Amino Acid Sequence↗
PubMed1993

[Changes of bone marrow MRI pattern in aplastic anemia before and after bone marrow transplantation].

In order to evaluate the usefulness of magnetic resonance imaging (MRI) in estimating bone marrow cellularity, we performed T1-weighted MRI of the lumbar vertebral marrow in two patients with severe aplastic anemia, before and after bone marrow transplantation (BMT). High signal intensity was detected in the bone marrow before BMT, but the bone marrow pattern of MRI became normal after BMT. MRI seems to be effective for evaluating bone marrow cellularity and recovery, and for monitoring therapeutic effects in patients with aplastic anemia before and after treatment with BMT.

Adult↗
PubMed1992

Analysis of oligosaccharides by on-line high-performance liquid chromatography and ion-spray mass spectrometry.

Oligosaccharides were analyzed by a combination of high-performance liquid chromatography (HPLC) and mass spectrometry (MS). First, oligosaccharides labeled with 2-aminopyridine were studied to see if they could be analyzed by MS under the conditions used for separation by HPLC. Pyridylamino (PA)-oligosaccharides could be analyzed under these conditions, although the mass spectra were affected. Then, liquid chromatography-mass spectrometry was used to analyze a PA-oligosaccharide mixture derived from human immunoglobulin G. The PA-oligosaccharides were separated on a reversed-phase column and mass-analyzed directly. The observed molecular weights were close to or identical to those expected from the structures, which were estimated from the elution position on HPLC. This method is rapid and simple, as the mass spectrometer can give the accurate molecular weight of each PA-oligosaccharide in one chromatography run, even if the HPLC separation is incomplete. This method can be used to extend the so-called two-dimensional mapping of PA-oligosaccharides. The structure can be studied in greater detail by tandem MS.

Carbohydrate Conformation↗
PubMed1991

A change in the spontaneous release of endogenous acetylcholine from rat striatal slices after repeated injection of haloperidol.

The spontaneous and 50 mM K(+)-stimulated release of endogenous acetylcholine (ACh) from rat striatal slices was measured to investigate an adaptive change of striatal ACh after a withdrawal period for 24 h from chronic treatment of the rat with haloperidol. The haloperidol injections (2.5 mg/kg/day) for a period of 3, 7 or 14 days all reduced the spontaneous release of ACh significantly by 20-50% without changing tissue levels of ACh. On the contrary, these treatments produced a very small (by about 10%) but significant increase in K(+)-stimulated release except for the treatment of 7 days. These results suggest that the spontaneous ACh release is under the control of a dopaminergic mechanism, which might be different from the mechanism controlling the evoked release of ACh and emerges following withdrawal from chronic haloperidol treatment.

Acetylcholine↗
PubMed1991

Intrapulmonary bronchial circulation during hemorrhage.

Experiments were conducted on 119 anesthetized and artificially ventilated rats to evaluate effects of a physiological stimulus (hemorrhage) to the sympothoadrenal system on the bronchial circulation. In the presence of a sufficient dose of a vasopressin V1-receptor antagonist, moderate (81 mmHg on average, 33 rats) or severe hypotension (69 mmHg, 28 rats) was produced by controlled hemorrhage (11 or 9 rats, respectively), or by treatment with phenoxybenzamine (0.1 mg/kg, i.v., 12 rats, or 1.0 mg/kg, 10 rats), or the highly selective alpha 1-adrenoceptor antagonist, bunazosin (0.01 mg/kg i.v., 10 rats, or 0.1 mg/kg, 9 rats). During hypotension, the intrapulmonary bronchial blood flow (microsphere method) was decreased in a dose-dependent manner in the two antagonist-treated groups. However, these decreases were only of a moderate degree compared to the severe decrease in the hemorrhage group. Although the bronchovascular resistance was not significantly changed after treatment with either antagonist, this variable was greatly elevated during severe hemorrhagic hypotension, reaching 240 +/- 51% (P less than 0.001 with either antagonist study) of its baseline level. Changes in the pulmonary arterial and left atrial pressures, plasma vasopressin concentration, and renin activity were found to be less influential on these responses in 58 rats. Overall, we concluded that the sympathoadrenal mechanism powerfully increased the resistance and decreased the blood flow of the intrapulmonary bronchial circulation.

Animals↗
PubMed1991

Structure of aureobasidin A.

Aureobasidin A, a new antifungal antibiotic, was isolated from the culture medium of Aureobasidium pullulans R106. Aureobasidin A was a cyclic depsipeptide consisting of eight alpha-amino acid units and one hydroxy acid unit. The structures of the units were found by acid hydrolysis of the antibiotic to be 2(R)-hydroxy-3(R)-methylpentanoic acid, beta-hydroxy-N-methyl-L-valine, N-methyl-L-valine, L-proline, allo-L-isoleucine, N-methyl-L-phenylalanine, L-leucine, and L-phenyl-alanine. The sequence of the units was identified by NMR and FAB-MS of the products from the alkaline hydrolysis of aureobasidin A.

Amino Acid Sequence↗
PubMed1991

Analysis of nucleic acids by ion-spray mass spectrometry.

We analyzed various synthetic oligonucleotides with the use of ion-spray mass spectrometer. The most suitable conditions were investigated for analyzing oligonucleotides with molecular weights ranging from 3000 to 15000. We have found that the pH of the solvent was critical to reduce the formation of adduct ions in the mass spectra. Tandem mass spectrometry was also used to study the sequences.

Base Sequence↗
PubMed1990

Decrease in the evoked release of endogenous dopamine and dihydroxyphenylacetic acid from rat striatal slices after withdrawal from repeated haloperidol.

The release of endogenous DA (dopamine) and DOPAC (3,4-dihydroxyphenylacetic acid) from rat striatal slices was measured after withdrawal from a prior long-term treatment of the rat with haloperidol to investigate adaptive changes in striatal DA and DOPAC release induced by chronic haloperidol treatment. Striatal slices prepared 24 h after the last injection of daily treatment with haloperidol for up to 14 days (2.5 mg/kg per day) were superfused and stimulated for 5 min with K+ (50 mM). Haloperidol treatment for 3 or 7 days decreased K(+)-stimulated DA release by maximally 35%, but a 14-day treatment was not effective. The K(+)-stimulated release of DOPAC, which occurred after the change in DA release, was reduced significantly by the treatment for 7 or 14 days. A higher daily dose of haloperidol (10 mg/kg per day) produced a more pronounced decrease in stimulated DA release after a 14-day treatment without having an effect after 3 days. However, the stimulated release of DOPAC decreased markedly after both 3 and 14 days of haloperidol treatment. The slight reduction in the DA content of the slices after K+ stimulation was seen in some haloperidol-treated tissues, although this change did not always parallel the simultaneous decrease in DA release. These results indicate that the K(+)-induced stimulation of endogenous DA release and the synthesis of DA are impaired after withdrawal from repeated haloperidol treatment.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Release of endogenous acetylcholine from rat brain slices with or without cholinesterase inhibition and its potentiation by hemicholinium-3.

The direct measurement of basal and high K(+)-stimulated release of endogenous acetylcholine from striatum and hippocampus slices was achieved without as well as with a cholinesterase inhibitor, physostigmine. Hemicholinium-3, opposite to its well-known activity as an inhibitor of endogenous acetylcholine release, significantly potentiated both the basal and stimulated release, in particular in the absence of physostigmine, suggesting an involvement of some unknown activity stimulating ACh release in hemicholinium-3.

Acetylcholine↗
PubMed1990

High-level expression of P-glycoprotein and 85 kD protein as assessed by flow cytometry and immunocytochemistry in leukemias and malignant lymphomas.

Acquired resistance developed after chemotherapy is characterized by lower sensitivity to anticancer agents. We utilized two monoclonal antibodies (MABs): MRK16 which recognized 170 to 180 kD P-glycoprotein and MRK20 which recognized 85 kD protein, to investigate the frequency of multidrug-resistant cancer cells appearing during treatment of 23 cases of leukemias and 27 cases of malignant lymphomas. The reactivities of these MABs with lymphocytes and blastic cells were examined by flow cytometry and immunocytochemistry. The following findings were obtained. First, among 50 cases, increases in MRK16-reactive cells and MRK20-reactive cells were noted in 17 cases (34%) and 28 cases (56%), respectively. Second, the increase of MRK16-positive cells in three cases and the increase of MRK20-positive cells in two cases were correlated with dosages of the corresponding anticancer drugs used. Although we investigated the total amounts of anti-cancer drugs used, we were not able to detect exactly when P-glycoprotein recognized by MRK16 and the 85 kDa protein recognized by MRK20 appeared in these resistant cells during treatment. More cases will be required to investigate the significance between treatment and reactivity of MRK16 or MRK20 with leukemia or lymphomas cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗