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Biomedical subjects

H Endou

Publications and source records attributed to H Endou.

At least 163 records · Page 9Linked to original sources
PubMed1982

Characterization of alpha-fetoprotein secreted from cultured reuber H-35 hepatoma cells.

Reuber H-35 hepatoma cells were examined for their ability to synthesize protein in vitro, especially to produce alpha-fetoprotein (AFP). The presence of AFP in the culture supernatant solution was determined immunologically by the micro-Ouchterlony method. Charge heterogeneity of AFP was examined electrophoretically in continuous gradient polyacrylamide microgels. With regard to the duration of culture, there was no remarkable change in the ratio of two peaks of AFP, and which came out as a major combined peak and a similar peak by PAS staining on the condition of added SDS. These findings indicated that Reuber H-35 hepatoma cells had potential to produce two charge variants of AFP in vitro.

Animals↗
PubMed1982

Distribution of gamma-glutamyl transpeptidase and glutaminase isoenzymes in the rabbit single nephron.

"Phosphate-independent maleate-stimulated glutaminase" was investigated as a function of gamma-glutamyl transpeptidase (gamma-GTP). The activity of gamma-GTP in brush border membranes was found to be four times higher than that in the microsomal fraction of the renal cortex. This gamma-GTP activity was exclusively located in the proximal tubule of isolated single nephrons. Specific activity of gamma-GTP was 105 U/g protein (19.8 microU/mm length) in the first 2 mm portion of the proximal tubule and 1352 U/g protein (209 microU/mm) in the last 2 mm portion of the proximal straight tubule. Activity of phosphate independent glutaminase (PIG) was distributed in the same patterns as those of gamma-GTP, not only in the subcellular fractions, but also in the isolated nephron segments. On the other hand, phosphate dependent glutaminase (PDG) was distributed highly in the papillary mitochondrial fraction and in the distal tubule. Observations on the effect of pH on the enzyme activities of gamma-GTP and PDG showed that these enzyme activities were decreased significantly when the pH of the assay mixture was lowered. In the case of PIG, however, the effect of pH was just reversed. From these findings, it may be possible to interpret that gamma-GTP may play an important role in ammonia production in the brush border membrane of the proximal tubule as a function of glutaminase.

Animals↗
PubMed1982

Cyclic AMP-dependent protein kinase activity and endogenous protein phosphorylation in isolated cortical segments of rabbit nephron.

Cyclic AMP-dependent protein kinase activity and endogenous protein phosphorylating activity are reported for 6 cortical segments of the rabbit nephron which were microdissected and collected according to their morphology. The 6 cortical nephron segments, namely the glomerulus (Glm), proximal convoluted tubule (PCT), proximal straight tubule (PST), cortical ascending limb of Henle's loop (CAL), distal convoluted tubule (DCT), and cortical collecting tubule (CCT), showed protein kinase activities which were increased 1.8-4.9 fold by 10(-6) M cyclic AMP in the presence of histone IIA, histone f2b or histone f3 as a protein substrate. However, all these segments showed little or no cyclic AMP dependent increase of activity with either protamine or alpha-casein as a protein substrate. Cyclic AMP increased the endogenous protein phosphorylation of Glm (10(-6) M cyclic AMP), of CAL (10(-7) and 10(-8) M cyclic AMP), of DCT (10(-6) M cyclic AMP) and of CCT (10(-8), 10(-7) and 10(-6) M cyclic AMP). In contrast, PCT showed decreased endogenous protein phosphorylation in the presence of 10(-7), 10(-5) and 10(-4) M cyclic AMP.

Animals↗
PubMed1981

Localization of kallikrein-like activity along a single nephron in rabbits.

In order to investigate the presence of renal kallikrein, the localization of kallikrein-like proteolytic activity along a single nephron was determined in rabbits. Single nephrons were dissected into 8 segments under a microscope. Activity was fluorometrically measured with two different substrates (benzoyl-L-arginine ethyl ester: BAEE and prolyl-phenylalanyl-arginine-methylcoumarin amide: MCA). Proteolytic activity could be detected in the early (S1), the middle (S2), and the terminal (S3) portions of the proximal tubule and in the granular portion of the distal tubule (DCTg). With MCA, the specific activity in S1, S2, S3 and DCTg was 0.77 +/- 0.08, 0.28 +/- 0.10, 0.13 +/- 0.05, and 0.27 +/- 0.05 pmoles/microgram/min, respectively. The activity in DCTg was inhibited by aprotinin but that in the proximal tubules was not inhibited. No activity was found in the glomerulus, the thick ascending limb of Henle's loop, the bright portion of the distal tubule, and the light portion of the cortical collecting tubule. The inhibition of the activity by aprotinin in DCTg suggests that intrarenal kallikrein could be localized only in DCTg.

Animals↗
PubMed1980

[Evaluation of nephrotoxic site in rat proximal tubule: intrarenal distributions of three enzymes and effects of mercuric chloride and gentamicin on their excretion into urine (author's transl)].

Intrarenal distributions of three enzymes, gamma-glutamyl transpeptidase (gamma-GTP), alkaline phosphatase (Al-p) and leucine aminopeptidase (LAP) were determined using six segments of nephrons. These enzymes were localized only in the proximal tubule. Intra-proximal distributions of the enzymes, however, were not uniform. The order of each enzyme activity in three segments of the proximal tubule, S1, S2 and S3 was as follows: Formula: (See Text) With subcutaneous administration of HgCl2 (1.0 mg/kg/day), urinary excretions of all three enzymes were increased from the 1st to the 2nd day and then decreased to the control level. However, after intraperitoneal administration of gentamicin sulfate (40 mg/kg/day), only Al-p activity in urine was significantly increased on the 1st day. Because of the lack of increasing blood levels of these enzymes after treatment, increased urinary excretions of the enzymes probably originate from the kidney, particularly the proximal tubule. The prominently increased excretion of gamma-GTP and LAP after HgCl2 treatment means that HgCl2 might damage S2 and S3, because the excretory patterns of the three enzymes were similar to their distribution profiles in S2 and S3. On the other hand, the toxic action of GM may be localized in S1 portion, in which Al-p activity proved to be highest among the three enzymes.

Alkaline Phosphatase↗
PubMed1979

Glucose dehydrogenase (hexose 6-phosphate dehydrogenase) and the microsomal electron transport system. Evidence supporting their possible functional relationship.

The ability of a microsomal enzyme, glucose dehydrogenase (hexose 6-phosphate dehydrogenease) to supply NADPH to the microsomal electron transport system, was investigated. Microsomes could perform oxidative demethylation of aminopyrine using microsomal glucose dehydrogenase in situ as an NADPH generator. This demethylation reaction had apparent Km values of 2.61 X 10(-5) M for NADP+, 4.93 X 10(-5) m for glucose 6-phosphate, and 2.14 X 10(-4) m for 2-deoxyglucose 6-phosphate, a synthetic substrate for glucose dehydrogenase. Phenobarbital treatment enhanced this demethylation activity more markedly than glucose dehydrogenase activity itself. Latent activity of glucose dehydrogenase in intact microsomes could be detected by using inhibitors of microsomal electron transport, i.e. carbon monoxide and p-chloromercuribenzoate (PCMB), and under anaerobic conditions. These observations indicate that in microsomes the NADPH generated by glucose dehydrogenase is immediately oxidized by NADPH-cytochrome c reductase, and that glucose dehydrogenase may be functioning to supply NADPH.

Aminopyrine N-Demethylase↗
PubMed1979

Suppressive effect of dipyridamole on the proteinuria of aminonucleoside nephrosis in rat.

The suppressive effect of dipyridamole on the proteinuria of aminonucleoside nephrosis and protamine-induced proteinuria, was investigated. Male Wistar rats were given puromycin aminonucleoside (80 mg/kg s.c.) or protamine sulfate (20 mg/kg i.v.), and the urine was collected in metabolic cages. The content of proteins in the urine was determined by using a continuous gradient microgel electrophoresis procedure. Dipyridamole (20 mg/kg p.o.) suppressed the excretion of albumin and proteins larger than albumin (HMP) in aminonucleoside nephrosis. But the excertion of proteins smaller than albumin (LMP) was not affected by dipyridamole. Dipyridamole also suppressed the excertion of HMP in protamine-induced proteinuria, though the excretion of albumin and LMP was not affected. Puromycin aminonucleoside and protamine sulfate were known to cause renal glomerular epithelial changes referred to as "fusion" of foot processes. Since dipyridamole was effective in suppressing the both types of proteinuria, this drug was considered to improve the damaged renal glomerular barrier for plasma proteins.

Albuminuria↗
PubMed1978

Quantitative analysis of electrophoretically separated proteins using Coomassie blue.

Electrophoresis of 125I-labelled rat albumin from 0.5 to 700 ng was performed with a 5 microliter capillary tube in which 4-40% continuous gradient polyacrylamide gel was prepared. The linear relationship was obtained by using double logarithm plots between protein amounts and densitometric areas of the protein bands stained with Coomassie blue. The radioactivities of the same gels and the protein amounts were also shown to be linear. In the case of rat gamma-globulin, the linear relationship was also obtained. As an applied example of this method, the urinary gamma-globulin excretion showed marked changes caused by the circadian rhythm in rats.

Albuminuria↗
PubMed1975

Relationship between L-alanine and sodium ion transport in isolated renal tubules.

1. Rat renal tubules were isolated by incubation with collagenase. The Na+ concentration in the tubules at 37 degrees C was increased by additions of g-strophantin and L-alanine. The increase of Na+ in the presence of both g-strophantin and L-alanine was stronger than with either alone. 2. Radioactive sodium (22-Na), which was taken up by the tubules at 0 degrees C in K+-free medium, was more slowly washed out in the buffer with added g-strophantin than in the control buffer, but L-alanine had no effect. 3. At 0 degrees C incubation without K+, g-strophantin did not affect the 22-Na transport of the tubules. But under the same conditions, L-alanine increased Na+ uptake significantly, and in conjunction with it, L-alanine uptake was also increased. 4. The relationship between L-alanine uptake and intra- extracellular Na+ concentration gradients was linear. The ration of L-alanine to Na+ uptake at 0 degrees C was about 1:2. 5. In the incubation without K+ at 0 degrees C, L-alanine could be accumulated in tubules against the chemical concentration gradient (about 1.5-fold). 6. In the incubation without K+ at 37 degrees C, the L-alanine concentration in tubules after 5 min was already steady (Ci/Ce = 2.2), but with K+ it was not stabilized after 10 min. The ration Ci/Ce with K+ WAS HIGHER THAN WITHOUT K+. 7. G-Strophantin, p-hydroxymercuribenzoate, amiloride, and 2,4-dinitrophenol inhibited L-alanine uptake in the tubules and at the same time increased Na+ concentration. The relationship between the L-alanine uptakes inhibited by g-strophantin, amiloride and dinitrophenol, and the respective intra- extracellular Na+ concentration gradients was strikingly linear. But in the case of p-hydroxymercuribenzoate there was no correlation. 8. The results indicate that L-alanine transport into the renal tubules might be regulated mainly by the intra- extracellular Na+ concentration gradient and that inhibitors such as g-strophantin, amiloride, and dinitrophenol could have a secondary effect on the L-alanine transport which follows the change of Na+ concentration in cells. p-Hydroxymercuribenzoate might have an inhibiting effect on the binding of carrier with Na+ and/or L-alanine.

Alanine↗
PubMed1975

Inhibition of gluconeogenesis in rat renal cortex slices by metabolites of L-tryptophan in vitro.

The inhibitory effects of metabolites of L-tryptophan on gluconeo-genesis in rat renal cortex has been established. 1. Glucose production was inhibitied by quinolinate in vitro. The inhibition is due to the decreased phosphoenolpyruvate carboxykinase activity. As suggested for purified enzyme systems, quinolinate seems to exert its action in tissue slices by chelating divalent metal ions. The minimum effective extracellular concentration of the inhibitor was 5 X 10(-5) M with pyruvate as a precursor for gluconeo-genesis. 2. The effect of 3-hydroxyanthranilate is stronger (minimal effective concentration 10(-5) M) than that of quinolinate. 3-Hydroxyanthranilate may be effective in its original form and/or as a dimer degrandation product. The compound(s) exert a second effect in addition to blocking the phosphoenolpyruvate carboxykinase. This block is attained by conversion of 3-hydroxyanthranilate to quinolinate. The non-quinolinate mediated effect may be due to a reduced ATP regeneration. 3. It is suggested that kidney cortex responds sensitively to disturbances in ATP metabolism by reduction of glucose synthesis, when it is not the result of blocked formation of phosphoenolpyruvate.

3-Hydroxyanthranilic Acid↗
PubMed1975

Kinetic studies on microsomal glucose dehydrogenase in rat liver.

Glucose dehydrogenase from rat liver microsomes was found to react not only with glucose as a substrate but also with glucose 6-phosphate, 2-deoxyglucose 6-phosphate and galactose 6-phosphate. The relative maximum activity of this enzyme was 29% for glucose 6-phosphate, 99% for 2-deoxyglucose 6-phosphate, and 25% for galactose 6-phosphate, compared with 100% for glucose with NADP. The enzyme could utilize either NAD or NADP as a coenzyme. Using polyacrylamide gradient gel electrophoresis, we were able to detect several enzymatically active bands by incubation of the gels in a tetrazolium assay mixture. Each band had different Km values for the substrates (3.0 x 10(-5)M glucose 6-phosphate with NADP to 2.4M glucose with NAD) and for coenzymes (1.3 x 10(-6)M NAD with galactose 6-phosphate to 5.9 x 10(-5)M NAD with glucose). Though glucose 6-phosphate and galactose 6-phosphate reacted with glucose dehydrogenase, they inhibited the reaction of this enzyme only when either glucose or 2-deoxyglucose 6-phosphate was used as a substrate. The Ki values for glucose 6-phosphate with glucose as substrate were 4.0 x 10(-6)M with NAD, and 8.4 x 10(-6)M with NADP; for galactose 6-phosphate they were 6.7 x10(-6)M with NAD and 6.0 x 10(-6)M with NADP. The Ki values for glucose 6-phosphate with 2-deoxyglucose 6-phosphate as substrate were 6.3 x 10(-6)M with NAD and 8.9 x 10(-6)M with NADP; and for galactose 6-phosphate, 8.0 x 10(-6)M with NAD and 3.5 x 10(-6)M with NADP. Both NADH and NADPH inhibited glucose dehydrogenase when the corresponding oxidized coenzymes were used (Ki values: 8.0 x 10(-5)M by NADH and 9.1 x 10(-5)M by NADPH), while only NADPH inhibited cytoplasmic glucose 6-phosphate dehydrogenase (Ki: 2.4 x 10(-5)M). The results indicate that glucose dehydrogenase cannot directly oxidize glucose in vivo, but it might play a similar role to glucose 6-phosphate dehydrogenase. The differences in the kinetics of glucose dehydrogenase and glucose 6-phosphate dehydrogenase show that glucose 6-phosphate and galactose 6-phosphate could be metabolized in quite different ways in the microsomes and cytoplasm of rat liver.

Alcohol Oxidoreductases↗