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Biomedical subjects

H Iguchi

Publications and source records attributed to H Iguchi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Chloroplast RNA editing required for functional acetyl-CoA carboxylase in plants.

RNA editing is an important post-transcriptional process in chloroplasts and is thought to be functionally significant. Here we show a requirement of RNA editing for a functional enzyme. In peas, acetyl-CoA carboxylase (ACCase), a key enzyme of fatty acid synthesis, is composed of biotin carboxylase with the biotin carboxyl carrier protein and carboxyltransferase (CT). CT is composed of the nuclear-encoded alpha polypeptide and the chloroplast-encoded beta polypeptide in peas. One nucleotide of the beta polypeptide mRNA, which is edited in pea chloroplasts, converts the serine codon to the leucine codon. We show that this RNA editing is required for functional CT by comparing the unedited and edited recombinant enzymes. In plants not having a leucine codon at the same position, editing was shown to take place so as to create the leucine codon, indicating that editing is needed for in vivo CT activity and therefore for ACCase. To our knowledge, ACCase is an essential enzyme, suggesting that the chloroplast RNA editing is necessary for these plants.

Acetyl-CoA Carboxylase↗
PubMed2000

Recombinant carboxyltransferase responsive to redox of pea plastidic acetyl-CoA carboxylase.

Acetyl-CoA carboxylase regulates the rate of fatty acid synthesis. This enzyme in plants is localized in plastids and is believed to be composed of biotin carboxyl carrier protein, biotin carboxylase, and carboxyltransferase made up of alpha and beta polypeptides, although the enzyme has not been purified yet. Accumulated evidence shows that pea plastidic acetyl-CoA carboxylase is activated by light and the activation is caused by light-dependent reduction of carboxyltransferase, but not of biotin carboxylase, via a redox cascade. To understand the reductive activation of carboxyltransferase at the molecular level here, we obtained the active enzyme composed of decahistidine-tagged (His tag) alpha and beta polypeptides through the expression of the pea plastidic carboxyltransferase gene in Escherichia coli. Gel filtration showed that the molecular size of the recombinant carboxyltransferase is in agreement with that of partially purified carboxyltransferase from pea chloroplasts. The catalytic activity of the recombinant enzyme was similar to that of native carboxyltransferase. These results indicate that the molecular structure and conformation of recombinant carboxyltransferase resemble those of its native counterpart and that native carboxyltransferase is indeed composed of alpha and beta polypeptides. This recombinant enzyme was activated by dithiothreitol, a known reductant of S-S bonds, with a profile similar to that of its native counterpart. The recombinant enzyme was activated by reduced thioredoxin-f, a signal transducer of redox potential in chloroplasts under irradiation. Thus, this enzyme was redox-regulated, like that of the native carboxyltransferase.

Acetyl-CoA Carboxylase↗
PubMed2000

Hypercalcemia due to parathyroid hormone-related protein produced by primary ovarian clear cell adenocarcinoma: case report.

OBJECTIVE: Amongovarian carcinomas, clear cell adenocarcinoma is one of the most common histologic subtypes associated with hypercalcemia. However, the mechanisms of hypercalcemia in clear cell adenocarcinoma are still unclear. In the following case report, we tried to determine the etiology of hypercalcemia and also to demonstrate the management of hypercalcemia diagnosed preoperatively. CASE: A 49-year-old woman was diagnosed as having a malignant ovarian tumor with hypercalcemia caused by elevated serum parathyroid hormone-related protein (PTHrP) prior to her primary surgery. Treatment with disodium incadronate promptly normalized the serum calcium level. An immunohistochemical study demonstrated PTHrP expression in the primary ovarian lesion, but not in the metastatic lesion. A Northern blot analysis of the cancer cells from the ovarian tumor confirmed the presence of PTHrP mRNA. CONCLUSION: Humoral hypercalcemia of malignancy in this case has been conclusively shown to be due to the production of PTHrP at the primary ovarian tumor, based on both immunohistochemical and molecular analyses.

Adenocarcinoma, Clear Cell↗
PubMed2000

Effects of eicosapentaenoic acid intake on plasma fibrinolytic and coagulation activity by using physical load in the young.

To assess the effect of eicosapentaenoic acid (EPA) intake on fibrinolysis and coagulation, 30 male subjects, approximately 19-23 y old, were examined for plasma fibrinolytic and coagulation activity by using a bicycle ergometer load (90 W, 20 min) before and after EPA intake of 1.125 g/d for 2 wk. Because of the EPA intake, the fibrinolytic activity was promoted, the plasmin-alpha 2 plasmininhibitor complex (PIC) level was decreased by 16.7%, and the thrombin-antithrombin III complex (TAT) level was increased by 75.4%; conversely, the D-dimer of the fibrin degradation peptide (D-dimer) level did not change from that before EPA intake. By the physical load, 1 h after ingesting the load, the PIC level was significantly decreased by 26.7%, the TAT level was significantly increased by 51.1%, and the D-dimer level was significantly decreased by 24% in comparison with levels before EPA intake. Thus, as determined by the load, a small amount of daily EPA intake clearly decreased fibrinolytic activity and increased coagulation activity. One hour after a physical load, the rate of change of the gamma-glutamyl transpeptidase (gamma-GTP) level correlated significantly and negatively to the rate of change in the PIC and TAT levels. Thus, EPA intake may affect liver and kidney function. EPA intake decreased systolic blood pressure by 5 mmHg and diastolic blood pressure by 10 mmHg.

Adult↗
PubMed2000

IDPN-induced monoamine and hydroxyl radical changes in the rat brain.

beta-beta'-iminodipropionitrile (IDPN)-induced monoamine and hydroxyl radical changes in the rat brains were studied. IDPN caused decreases in 5-HT and 5-HIAA levels in all brain regions, strongly indicating that IDPN's neurotoxicity primarily affects 5-HT containing neurons. Dopamine and its metabolites' levels decreased in the some regions, most likely due to depression of dopamine metabolic turnover. Our results more clearly demonstrate IDPN-induced monoamine alterations in the rat brain more than previous reports. To clarify one of the pathogenesis of IDPN-induced neurological disorders, we measured hydroxyl radical levels. 2,3-DHBA increased at 1st day, and decreased in some regions at 7th days after discontinuing IDPN. We conclude, hydroxyl radical formation causes neuronal damage, and monoamine changes contribute to IDPN-induced neurological disorder.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2000

Possible effects of one week vitamin K (menaquinone-4) tablets intake on glucose tolerance in healthy young male volunteers with different descarboxy prothrombin levels.

To clarify the roles of vitamin K (VK) in the pancreas, twice oral, glucose tolerance tests were examined in 12 healthy young male volunteers before and after 1 week of VK tablet intake. Blood were collected by venipucture at 0, 30 and 120 min after 75 g oral glucose loading. They then took VK tablets (90 mg/d of menaquinone-4) for 1 week, and the second glucose tolerance test was examined. The subjects were divided into three groups by serum descarboxy prothrombin (DP) levels; four of lowest DP (L-DP), middle of DP (M-DP) and highest DP (H-DP) levels. They were compared by one-factor analysis of variance and Scheffè's F (group differences) and paired t -test (the effects of 1 week of VK intake). Age, body mass index and glucose status [plasma glucose (PG) and immunoreactive insulin (IRI), hemoglobin-Alc, fructosamine] of all groups were almost the same, but the IRI of the H-DP group was higher than that of the other groups at 120 min after the glucose loading (mean+/-SEM; L; 10.6+/-0.9, M-; 17.5+/-4.2, H-; 40.4+/-6.0 microU/ml). One week of VK intake tended to decrease the plasma DP levels of all groups and significantly reduced IRI of the H-DP at 120 min by half (before; 40.4+/-6.0 vs after: 18.4+/-4.6 microU/ml). The IRI/pG ratio in areas under the curve (AUC) of H-DP from 0 to 120 min after the loading was significantly decreased by 1 week of VK tablet intake (before: 31.0+/-7.4 vs after: 20/1+/-3.8 microU/g). These results suggested that there may be some relationship between pharmacological dose of vitamin K and insulin response.

Adult↗
PubMed2000

Changes of HDL subfractions by eicosapentaenoic acid intake and physical load in 20- to 25-year-old men.

The effects of daily eicosapentaenoic acid (EPA) intake and physical activity on high-density lipoprotein (HDL) subfraction, which may be an index of health status, were examined. The HDL subfraction, triglyceride and T-chol levels in the serum of 10 male volunteers aged 20-25 were examined before, immediately after and 1 h after being subjected to a physical load by bicycle ergometer at 90 W for 20 min. Subjects were then given 1.25 g EPA/day for 2 weeks, and the above test was repeated. By EPA intake, the distribution of HDL3b and 3c decreased significantly by 16.8 and 15.3%, respectively, and that of 2b increased significantly by 17.9%. The rate of change of subfraction of the 29th part (2b) of 30 parts in the total range of HDL increased by 67%, and decreased by 47% in 7th part (3c). By physical load, the distribution of HDL2a increased significantly by 15.4%, while 3b tended to decrease. By physical load after EPA intake, the distribution of 2a decreased significantly by 9.7%, and those of 3b and 3c increased significantly by 20.5 and 5.4%, respectively, and that of the 7th part (3c) increased by 37%. Thus, the physical load after EPA intake is effective to prevent arteriosclerosis as increasing the rate of change of HDL3c and as showing the longevity pattern of the HDL subfraction. Concentration of TG in a modal HDL pattern group increased by 95% after EPA intake, but that of a bimodal group did not show any change. HDL-cholesterol level in the bimodal group was higher than that in the modal group, especially after EPA intake. Two type III subjects changed to type IV by the load and the EPA intake, respectively. Thus, it seemed that the transformation from a modal pattern to a bimodal pattern by a certain lifestyle, especially regular physical activity and proper food intake, is a very important trial for the prevention of cerebrovascular diseases.

Adult↗
PubMed2000

Expression of MTA1, a metastasis-associated gene with histone deacetylase activity in pancreatic cancer.

MTA1 has been identified as a metastasis-promoting gene, and its gene expression is correlated with serosal invasion and lymph node metastasis in the gastrointestinal and esophageal cancers. We examined MTA1 mRNA expression levels in 13 cell lines and 23 tumor tissues of pancreatic cancer by quantitative reverse transcription polymerase chain reaction. MTA1 mRNA expression was found in all the cell lines, however its levels were not correlated with the metastatic pontential of each cell line representing hematogenous distant metastasis. In the pancreatic cancer tissues, the overexpression of MTA1 mRNA (tumor/normal ratio >/=1) was observed in 12 out of 23. Pancreatic cancer tissues overexpressing MTA1 mRNA (T/N ratio >/=1) tended to have higher incidence of lymph node metastasis. These results together with previous findings in the gastrointestinal and esophageal cancers suggest that MTA1 might be involved in the progression, particularly in lymph node metastasis of pancreatic cancer.

Carcinoma↗
PubMed2000

Overproduction of IL-8 results in suppression of bone metastasis by lung cancer cells in vivo.

HARA-B cells were established from the bone lesion in nude mice formed after an intracardiac inoculation of the human lung cancer-derived cells (HARA), and production of IL-8 in HARA-B cells was decreased as compared to that in the parental HARA cells. This suggests a possible relationship between IL-8 production and bone metastasis. Thus, we examined the effect of IL-8 on bone metastasis using HARA-B cells transfected with experimental (IL-8-cDNA) and/or control plasmid in the experimental bone metastasis model in nude mice. Growth rates of both cells in vitro were similar. Control cells developed radiologically detectable bone metastases in 50% of nude mice tested, whereas experimental cells did not develop bone metastases. Osteoclastic bone resorption is an important step in the process of bone metastasis, and IL-8 possesses an inhibitory effect on osteoclastic bone resorption. These results suggest that IL-8 suppresses bone metastasis, which might be attributed to the inhibitory effect of IL-8 on osteoclastic bone resorption.

Animals↗
PubMed1999

Highly sensitive determination of N-terminal prolyl dipeptides, proline and hydroxyproline in urine by high-performance liquid chromatography using a new fluorescent labelling reagent, 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride.

A highly sensitive pre-column HPLC method for simultaneous determination of prolyl dipeptides, Pro and Hyp in urine was developed. The analytes were labelled with 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride at 70 degrees C for 20 min. The derivatives separated on tandem reversed-phase columns by a gradient elution and were monitored with fluorescence detection at 318 nm (excitation) and 392 nm (emission). The detection limits for prolyl dipeptides, Pro and Hyp were 1-5 fmol/injection (S/N = 3). Urine samples were treated with o-phthalaldehyde, followed by purification on a Bond Elut C18 column before conducting the labelling reaction. Pro-Hyp, Pro-Gly and Pro-Pro were identified as prolyl dipeptides in urine. The within-day and between-day relative standard deviations were 1.5-4.8 and 1.7-5.8%, respectively. The concentrations of Pro-Hyp, Pro-Gly, Pro-Pro, Pro and Hyp in normal human urine were 97.6 +/- 28.2, 2.74 +/- 1.48, 2.08 +/- 1.13, 6.71 +/- 3.34 and 2.30 +/- 1.59 nmol/mg creatinine, respectively.

Chromatography, High Pressure Liquid↗
PubMed1999

Differentiation and growth inhibition of glioma cells induced by transfer of trk A proto-oncogene.

The induction of growth inhibition and differentiation of a glioma cell line by transfection of trk A cDNA was examined, and production of endogenous nerve growth factor (NGF) also was studied in these cells. When human trk A cDNA was transfected into a human glioma cell line, U-251MG, which lacks expression of both endogenous trk A and low-affinity NGF receptor, the transfectant expressed the exogenous trk A mRNA and a functional high-affinity NGF receptor. Transfection of trk A cDNA caused a partial induction of cell differentiation, G1 arrest, growth inhibition, tyrosine phosphorylation of the trk A proto-oncogene product, and activation of MAP kinase. Exogenous NGF treatment induced further terminal differentiation and growth inhibition. In summary, our data suggest that endogenous NGF secreted by glioma cells has an important role in the induction of glioma-cell differentiation occuring with transfer of exogenous trk A cDNA.

Animals↗
PubMed1999

Cystine protects cochlear outer hair cells against glutamate toxicity.

We previously reported that long-term exposure to glutamate (Glu) induced death of cochlear outer hair cells (OHCs). However, the mechanisms of OHC death induced by Glu were unclear. In the central nervous system, Glu is known to interfere with a cystine-Glu antiporter, leading to a decrease in cystine uptake and reducing the intracellular glutathione level. We therefore investigated the effect of cystine supplementation on degeneration of OHCs caused by long-term exposure to Glu. Supplementation of cystine significantly decreased the number of dying OHCs. These findings suggest that a cystine-Glu interaction may be involved in the mechanism of OHC degeneration caused by Glu.

Analysis of Variance↗
PubMed1999

Facile degradation of apolipoprotein B by radical reactions and the presence of cleaved proteins in serum.

A facile cleavage of peptide bonds of apolipoprotein B (apoB) by radical reaction is reported. When human LDL was subjected to oxidative damage using Cu2+, extensive degradation of apoB was observed based on immunoblotting. The degradation of apoB was inhibited by radical scavengers (beta-mercaptoethanol, butylated hydroxytoluene, and probucol) and promoted by a radical initiator [2, 2'-azobis(2-amidinopropane)dihydrochloride]. When human serum was treated with Cu2+, a similar cleavage pattern of apoB was observed. The cleaved apoB proteins were also detected in normal serum on the basis of immunoblots. These results suggest that apoB is highly reactive toward radicals in vitro and in vivo, with reaction resulting in the cleavage of peptide bonds.

Adult↗
PubMed1999

The effect of diet on blood vitamin K status and urinary mineral excretion assessed by a food questionnaire.

To assess Vitamin K (VK) status by food questionnaire, healthy young males (32) and females (9) were given a food list of 50 VK rich foods (identified in the 4th edition standard tables of food composition in Japan). After checking the food names and approximate amount eaten for 7 days, early morning blood and urine samples were collected. Prothrombin and hepaplastin was tested and plasma protein induced by VK absence factor II (PIVKA-II), osteocalcin, and calcium, phosphorous and magnesium in plasma and urine were determined. Participants who have a habit of eating natto, a traditional Japanese food very rich in Vitamin K, VK were excluded, and lowest and highest VK consumers were compared (males; lowest 7 vs. highest 7, females; 3 vs. 3). Plasma PIVKA-II levels, and urinary calcium and magnesium excretion of the lowest was significantly higher, but urinary phosphorus was lower, than that of the highest in females. In the natto eaters, daily mean VK intakes and hepaplastin test results of natto eaters were significantly higher, but urinary calcium excretions were lower than that of non natto eaters in males. These results suggest that Daily VK intake estimated from a questionnaire, is well related to real VK status, and also that natto is a good dietary source of vitamin K.

Adult↗
PubMed1999

Pancreatic carcinoma associated with chronic pancreatitis.

The incidence of invasive ductal carcinoma of the pancreas was 3.1% (6 cases) in 196 patients with definite chronic pancreatitis. Five patients (3 men and 2 women) had calcific pancreatitis and 1 patient (man) had non-calcific pancreatitis. Large pancreatic stones were recognized in 2 women. Most of the patients complained of continuous intractable abdominal pain and/or back pain together with weight loss and appetite loss. Serum CA19-9 levels and exacerbation of glucose intolerance were retrospectively noted to have been elevated in 1 patient. However, it was difficult to obtain a definitive diagnosis by imaging examinations earlier, due to the presence of chronic pancreatitis. Median survival of the 6 patients was 6.5 months from admission.

Adenocarcinoma↗
PubMed1999

Relationship between acute insulin response and vitamin K intake in healthy young male volunteers.

To evaluate the effects of vitamin K (VK) on pancreatic function, especially on acute insulin response, 25 healthy young male volunteers were given an oral load of 75 g of glucose, and their mean daily VK intake was estimated by a one-week food check list. After excluding low (<20) and high (> or =25) body mass index (BMI) subjects, the remaining 16 participants were divided into three semi-equal groups according to VK intake. Blood VK status of the low VK intake group tended to be poorer than that of the high intake group (median of 5 samples: prothrombin time; 12.5 vs 12.2s and protein-induced VK absence-factor-II; 23 vs 15 mAU/ml), but fasting plasma glucose status was not markedly different between both groups: [plasma glucose (PG); 87 vs 86 mg/dl, immunoreactive insulin (IRI); 6.7 vs 5.3 microU/ml, HbA1c; 4.8 vs 4.9%]. However, at 30 min after glucose loading, PG of the low VK intake group tended to be higher than those of the high intake group (160 vs 145 mg/dl) and IRI was lower (36.1 vs 52.3 microU/ml). Insulinogenic index (incremental IRI/incremental PG, 0-30 min) of the low VK intake group was significantly lower than that of the high intake group (0.4 vs 0.9). These results suggested that VK may play an important role on the acute insulin response in glucose tolerance.

Adult↗