Search PubMed⌕ Search

Biomedical subjects

E Imai

Publications and source records attributed to E Imai.

156 records · Page 9Linked to original sources
PubMedDate not supplied

Recognition of opioid agonist and antagonist in the opioid receptor binding site.

By treating the rat crude synaptosomal fraction with 5,5'-dithio-bis-(2-nitrobenzoic acid), DTNB, a marked decrease of stereo-specific binding of opioid agonist (dihydromorphine or D-Ala-D-Leu-enkephalin) was observed, but there was no effect in the case of the binding of opioid antagonist (naloxone or diprenorphine). The decrease of the agonist binding in the presence of 500 microM of DTNB was nearly equal to that of 100 mM of NaCl. The ability of opioids to inhibit 3H-naloxone binding in the absence of DTNB was compared to their inhibitory potency in the presence of 500 microM of DTNB to obtain DTNB response ratio. This ratio closely correlated with sodium index of each opioid. Potency of the inactivation of the agonist binding by congeners of DTNB changed with net charge of the reagents, and 2,2'-dithiobis-(5-nitropyridine), bearing a positive charge, was most effective. These results suggest that an aliphatic sulfhydryl group, being sensitive to DTNB is located to the active center of an anionic binding site for the agonist, and controls opioid agonist binding through a proton transfer mechanism.

Animals↗
PubMedDate not supplied

Entamoeba dispar: cultivation with sterilized Crithidia fasciculata.

Four isolates of Entamoeba dispar identified by their hexokinase and phosphoglucomutase isoenzyme profile and by their failure to react with Entamoeba histolytica-specific monoclonal antibody (4G6) could be grown in either Diamond's BI-S-33 medium, newly developed BCSI-S (Biosate cysteine starch iron-serum) medium, or casein-free YI-S medium in the presence of Crithidia fasciculata (ReF-1:PRR) sterilized by heating 56 degrees C for 30 min and subsequent incubation with 1% hydrogen peroxide for 24 hours at 4 degrees C. After the cultures were maintained for over 50 passages, the amebae were identified as E. dispar by isoenzyme analysis, polymerase chain reaction with E. histolytica- and E. dispar-specific primers, i.e. p11 plus p12 and p13 plus p14, respectively, and by negative reactivity with monoclonal antibody 4G6. The flagellates added to the culture were judged to be metabolically inactive based on the results of nuclear magnetic resonance spectroscopy, electron microscopy, and polarographic analysis. All of these findings suggest that E. dispar can grow in vitro with metabolically inactive C. fasciculata as a culture associate.

Animals↗
PubMedDate not supplied

The HVJ liposome method.

Recent advancement of gene technology allows us a practical approach to gene therapy. Among various in vivo gene transfer techniques available, the HVJ liposome method is an efficient procedure which could target the glomerular cells. Using this method, HVJ-mediated cell fusion activity enables us to introduce genetic materials directly into the cytosol without degradation. In addition, cointroduction of non-histone nuclear protein, high-mobility group (HMG-1), efficiently facilitates migration of foreign DNA to the nucleus. Although there still exist some limitations, the HVJ liposome method may be applicable to the treatment of glomerular diseases as well as to analysis of the molecular aspects of renal pathophysiology.

Animals↗
PubMedDate not supplied

Glowing podocytes in living mouse: transgenic mouse carrying a podocyte-specific promoter.

Green fluorescence protein (GFP) has been utilized as a marker of gene expression due to the great advantage in its simple and quick detectability. We generated transgenic mice carrying a GFP cDNA under the control of a beta-actin/beta-globin promoter (CX promoter) and cytomegalovirus enhancer. The green luminescence derived from GFP was apparent in skeletal muscle, pancreas, heart and kidney, but not in other tissues. The GFP expression in the kidney was localized in podocytes. Moreover, in situ hybridization of GFP showed that the transcriptional level was highly active in the podocytes. These results suggested that the glowing green fluorescence would be a useful in vivo marker of podocyte in these transgenic lines in the physiological and pathophysiological state, and that the CX promoter could allow a podocyte-specific expression of a molecule of interest in kidney.

Animals↗
PubMedDate not supplied

Pharmacokinetics and lipid-lowering effect of fluvastatin in hypercholesterolaemic patients on maintenance haemodialysis.

Patients undergoing haemodialysis are predisposed to serum lipid abnormalities that can accelerate the development of atherosclerosis. Serum lipid levels must therefore be controlled over a long period. For patients with reduced renal function (including dialysis patients), special attention must be paid to hyperlipidaemia therapy, particularly drug selection. In this study, 30 mg/day fluvastatin was administered orally to five patients receiving maintenance haemodialysis. Their serum lipid levels and blood biochemistry were monitored during the 6 months of fluvastatin administration, and the pharmacokinetic parameters calculated. The therapeutic efficacy and safety of fluvastatin were demonstrated in this patient group. Furthermore, fluvastatin is not influenced by the dialysis membrane and does not accumulate in haemodialysis patients with hyperlipidaemia.

Anticholesteremic Agents↗
PubMedDate not supplied

Effect of hypertonic stress on amino acid levels and system A activity in rat peritoneal mesothelial cells.

OBJECTIVE: Peritoneal mesothelial cells (PMC) are exposed to a hypertonic environment during peritoneal dialysis. When exposed to a hypertonic medium, many types of cells accumulate small osmotically active organic solutes, which are called osmolytes, to match the higher external osmolality. However, no information has been available concerning the osmolytes in PMC. To investigate osmoregulation in rat PMC, the levels of amino acids in the cells and the activity of system A, a major neutral amino acid transport, were measured after switching to a medium made hypertonic by the addition of NaCl. System A was measured by Na+-dependent [14C]-2-methylamino-isobutyric acid (MeAIB) uptake. RESULTS: Total amount of 20 amino acids increased from 306 to 757 nmol/mg protein after 12 hours of hypertonicity. The amount of neutral amino acids accounted for 81% of the increase in total amino acids. Glutamine, alanine, glycine, threonine, and serine were the major neutral amino acids that accumulated in the hypertonic mesothelial cells. The amount of neutral amino acids increased 2.9-fold after 12 hr of hypertonicity, and decreased thereafter. MeAIB uptake increased 36-fold relative to the uptake in isotonic cells after 4-8 hr of hypertonicity. When the culture medium was made hypertonic by adding raffinose or glucose, the activity of system A was also stimulated (raffinose > glucose > NaCl). System A was located on both the apical and basal sides of isotonic PMC, and extracellular hypertonicity stimulated the MeAIB uptake on both sides. CONCLUSIONS: These data indicate that neutral amino acids and system A transport play an important role in early-phase osmoregulation in rat peritoneal mesothelial cells.

Amino Acids↗
PubMedDate not supplied

Angiotensinogen gene polymorphism of threonine/methionine at position 235-potential problems of the modified restriction endonuclease (Tth111-I) digestion method.

There are four methods for detecting the angiotensinogen gene Agt T235/M235; 1) allele-specific oligonucleotide hybridization (PCR-ASO); 2) mutagenically separated PCR (MS-PCR) using three primers to amplify all possible alleles in on PCR reaction; 3) restriction endonuclease Tth111-I; 4) SfaN-I digestion method using mismatched primer for the PCR (modified PCR-RFLP). Two of these four methods have been used in Japanese studies. The reported allelic frequencies of Agt T235/M235 in normal controls in the Japanese population are around 0.75-0.84/0.25-0.16 (as a whole 0.80/0.20) by PCR-ASO and 0.70-0.65/0.30-0.35 (as a whole 0.67/0.33) by the modified PCR-RFLP (Tth111-I). The present study tested how these methods contribute to the differences in Agt T235/M235. By PCR-ASO, the genotypes could be clearly determined. However, it is hard to complete every digestive reaction under the experimental conditions described for modified PCR-RFLP (Tth111-I). Thus, for studying Agt T235/M235, PCR-ASO or some method other than PCR-RFLP (Tth111-I) can be recommended. Our findings suggest that the allele frequency of Agt T235/M235 in the normal Japanese population is closer to 0.75-0.84/0.25-0.16. Although a strong association was reported between the Agt T235 allele and essential hypertension or myocardial infarction, using the modified PCR-RFLP (Tth111-I), two of three studies using PCR-ASO found no or only a weak association. The relationship between the Agt T235 allele and essential hypertension or myocardial infarction in the Japanese population needs to be assessed.

Angiotensinogen↗
PubMedDate not supplied

Gene transfer and kidney disease.

There is little doubt that molecular biological intervention therapy has come of age and its potential is arousing tremendous excitement. A gene transfer technique, the HVJ-liposome method, is now applicable as a tool for the dissection of molecular aspects in the pathophysiology of renal diseases, and for gene therapy in experimental glomerulonephritis. Overexpressed transforming growth factor (TGF)-beta in the normal rat glomeruli, by gene transfer of TGF-beta cDNA, leads to glomerulosclerosis. However, inhibition of the TGF-beta action by antisense oligonucleotides can suppress the development of the experimental glomerulonephritis. We investigated whether in vivo gene transfer of chimeric proteins, composed of the extracellular domain of TGF-beta type II receptor fused with IgC-Fc, suppresses experimental glomerulonephritis. The expression of TGF-beta in glomeruli was suppressed and so was the extracellular matrix expansion. Taken together with clinical observation of up-regulation of TGF-beta in various glomerulopathies, the dys-regulation of the TGF-beta is important in the development of glomerulosclerosis, and manipulation of this overexpression may prove a novel therapeutic approach for slowing the progression of the disease.

Gene Transfer Techniques↗
PubMedDate not supplied

Histoculture drug response assay, a possible examination system for predicting the antitumor effect of aromatase inhibitors in patients with breast cancer.

Histoculture drug response assay (HDRA) systems have been used in evaluating the cytotoxic effects of chemotherapeutic agents for many kinds of advanced cancers. We have adapted the HDRA system to estimate the antitumor effect of aromatase (estrogen synthetase) inhibitors on breast cancer. Small pieces of breast cancer tissue specimens were placed onto a collagen-matrix filled with medium containing testosterone (a substrate for aromatase) or testosterone plus an aromatase inhibitor. At the end of culture, [3H]-thymidine incorporation was measured in aliquots of the histocultured specimens after 10 days culture. The increment of thymidine incorporation in testosterone-treated specimens to that of control provides an index of existence of aromatase and estrogen-dependency, since converted estradiol from added testosterone by aromatase stimulates the incorporation. The decrease in the index of "testosterone + aromatase inhibitor"/"testosterone" indicates the antitumor effect of the aromatase inhibitor on breast cancer. Twenty-one 25 breast cancer surgical specimens were successfully cultured, and 6 showed the increased incorporation of [3H]-thymidine by testosterone. Aromatase inhibitor blocked this stimulation in these 6 specimens. These results suggested that this antitumor effect is related to the inhibition of aromatase and the aromatase inhibitor would be effective for individual patients with breast cancer which responds to testosterone in this histoculture assay system. The histoculture technique we used here is therefore expected to be useful in predicting the efficacy of aromatase inhibitors for individual patients with breast cancer.

Antineoplastic Agents↗