Search PubMed⌕ Search

Biomedical subjects

T Higuchi

Publications and source records attributed to T Higuchi.

At least 253 records · Page 14Linked to original sources
PubMed1998

Human large luteal cells in the menstrual cycle and early pregnancy express leukotriene A4 hydrolase.

Leukotriene (LT) A4 hydrolase (EC3.3.2.6) converts LTA4 to LTB4 which shows a chemotactic activity to leukocytes. To investigate the involvement of LTB4 in human corpus luteum (CL) function, the localization of LTA4 hydrolase in human ovarian tissues was examined by immunohistochemistry with a rabbit polyclonal antibody against LTA4 hydrolase. The enzyme was weakly expressed on granulosa cells of the follicles. After ovulation, the intensity of LTA4 hydrolase on large luteal cells increased and was highest in the midluteal phase. High expression was also observed in the CL of early pregnancy. In theca interna and small luteal cells, LTA4 hydrolase was weakly detected in all developmental stages. Immunoblot analysis demonstrated that the molecular mass of LTA4 hydrolase expressed in CL was 62 kDa, and confirmed that LTA4 hydrolase expression increased during CL formation and remained high in early pregnancy. The sequence encoding mRNA of LTA4 hydrolase, which was isolated from CL and amplified by polymerase chain reaction, was shown to be identical to the previously reported one. Immunocytochemistry showed that LTA4 hydrolase expression in cultured granulosa cells increased over 4 days in vitro and was enhanced by human chorionic gonadotrophin treatment. These expression profiles of LTA4 hydrolase suggest the involvement of LTB4 in luteal cell function during CL formation and early pregnancy.

Adolescent↗
PubMed1998

Distribution of fallover in the carboxylase reaction and fallover-inducible sites among ribulose 1,5-bisphosphate carboxylase/oxygenases of photosynthetic organisms.

The biphasic reaction course, fallover, of carboxylation catalysed by ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) has been known as a characteristic of the enzyme from higher land plants. Fallover consists of hysteresis in the reaction seen during the initial several minutes and a very slow suicide inhibition by inhibitors formed from the substrate ribulose-1,5-bisphosphate (RuBP). This study examined the relationship between occurrence of fallover and non-catalytic RuBP-binding sites, and the putative hysteresis-inducible sites (Lys-21 and Lys-305 of the large subunit in spinach RuBisCO) amongst RuBisCOs of a wide variety of photosynthetic organisms. Fallover could be detected by following the course of the carboxylase reaction at 1 mM RuBP and the non-catalytic binding sites by alleviation of fallover at 5 mM RuBP. RuBisCO from Euglena gracilis showed the same linear reaction course at both RuBP concentrations, indicating an association between an absence of fallover and an absence of the non-catalytic binding sites. This was supported by the results of an equilibrium binding assay for this enzyme with a transition state analogue. Green macroalgae and non-green algae contained the plant-type, fallover enzyme. RuBisCOs from Conjugatae, Closterium ehrenbergii, Gonatozygon monotaenium and Netrium digitus, showed a much smaller decrease in activity at 1 mM RuBP than the spinach enzyme and the reaction courses of these enzymes at 5 mM RuBP were almost linear. RuBisCO of a primitive type Conjugatae, Mesotaenium caldariorum, showed the same linear course at both RuBP concentrations. Sequencing of rbcL of these organisms indicated that Lys-305 was changed into arginine with Lys-21 conserved.

Amino Acid Sequence↗
PubMed1998

Molecular cloning, water channel activity and tissue specific expression of two isoforms of radish vacuolar aquaporin.

A major membrane intrinsic protein (VM23) in vacuoles of radish (Raphanus) tap root was investigated. The cDNAs for two isoforms of VM23, gamma- and delta-VM23, encode polypeptides of 253 and 248 amino acids, respectively. gamma- and delta-VM23 correspond to the gamma- and delta-TIP (tonoplast intrinsic protein) of Arabidopsis. The deduced amino acid sequences of the two VM23 isoforms were 60% identical. The amino-terminal sequence of gamma-VM23 showed agreement with the direct sequence of the purified VM23, suggesting that gamma-VM23 is the most abundant molecule among the VM23 isoforms. When mRNAs of gamma- and delta-VM23 were injected into Xenopus oocytes, the osmotic water permeability of oocytes increased 6-fold (60 to 200 microns s-1) of the control oocytes. The transcripts of both isoforms were detected in a high level in growing hypocotyls and young leaves, but delta-VM23 was not detected in seedling roots. Light illumination enhanced the transcription of two genes of VM23 in cotyledons and roots but suppressed their expression in hypocotyls the growth of which was inhibited by light. These findings suggest that the expression of VM23 is tightly related to cell elongation.

Amino Acid Sequence↗
PubMed1998

In vitro effect of contrast agents during immunoradiometric assay for tumour-associated antigens.

The aim of this study was to investigate if contrast agents interfere with the performance of an immunoradiometric assay (IRMA) in vitro for serum tumour-associated antigen. Each of five carcinoembryonic antigen (CEA)-positive sera, CA-130-positive sera and tissue polypeptide antigen (TPA)-positive sera was mixed with six contrast agents: Ioversol 350, Iopamidol 370, Iomeprol 300, Iomeprol 400, Iohexol 300 and Gadopenteic acid in 50:50, 50:20, 50:5.0, 50:1.0, 50:0.5 and 50:0.1 microl proportions. Following IRMA, the interference of binding rates in each mixture was calculated, and the serum concentrations of CEA, CA-130 and TPA were estimated and compared with the originals. All contrast agents used were able to inhibit the binding rate with IRMA and the inhibition rates were in proportion to the amount of contrast agent. The detection of serum concentrations of CEA, CA-130 and TPA was significantly inhibited in the mixtures with more than 5.0 microl of contrast agent in all cases. Apart from Iomeprol 400, there was no significant inhibition of detection at the lowest concentrations of contrast agents. Iomeprol 400 was the strongest inhibitor and Gadopenteic acid the weakest inhibitor for each IRMA of the contrast agents employed. In conclusion, our results demonstrate that contrast agents may reduce the immunoreaction of antibody and antigen and lead to in vitro inhibition during immunoassays. It would be unwise to perform any plasma/serum immunoassay on a sample collected within 24 h of the administration of contrast agent considering the pharmacokinetics.

Aged↗
PubMed1998

99Tcm-labelled chimeric human/mouse anti-granulocyte antibody bone marrow scintigraphy: a preliminary clinical study.

Bone marrow scintigraphy using 99Tcm-labelled chimeric anti-granulocyte antibody (anti-NCA-95) was performed in 17 patients with haematological disorders and skeletal metastases. Chimeric anti-NCA-95 antibody (chNCA95 Ab, 0.2 mg) labelled with 444 MBq 99Tcm was administered to obtain bone marrow images 4 h post-injection. One week later, an 111In-chloride bone marrow scan was performed on nine patients with haematological disorders. Lumbar bone marrow-to-background (L/B) and ilium-to-background (I/B) uptake ratios were calculated for each scan. In six patients with suspected skeletal metastases, 99Tcm-HMDP bone scans were performed. No patient had any adverse reaction or any immune reaction over 20 weeks. In the patients with haematological disorders, the L/B and I/B ratios of the 99Tcm-chNCA95 Ab scan were 3.41 +/- 0.90 and 1.23 +/- 0.31, whereas those of the 111In-chloride scan were 1.58 +/- 0.32 and 1.00 +/- 0.32, respectively. In assessing findings of irregular central bone marrow uptake and peripheral expansion of the bone marrow, the 99Tcm-chNCA95 Ab scan was much better than the 111In-chloride scan. In the six patients with suspected skeletal bone metastases, three true-positive and two true-negative results were observed. This preliminary study has revealed that 99Tcm-chNCA95 Ab scanning is safe and useful in the diagnosis of haematological disorders and skeletal metastases.

Adult↗
PubMed1998

Spongiotic annular erythema in SS-A/SS-B antibody negative Sjögren's syndrome.

We reported four cases of Sjögren's syndrome (SjS) who manifested a new type of annular erythema that differs from the previously described annular erythema seen in anti-SS-A/SS-B antibody positive SjS in both clinical and histological findings. Characteristic histological features are the presence of spongiotic changes around the acrosyringium and perivascular lymphocytic infiltration without liquefaction degeneration or epidermal change, suggesting lupus erythematosus. No complement or immunoglobulin depositions are demonstrated along the basement membrane zone or around blood vessels. Clinically, this type of erythema usually appears on the trunk or extremities with itchy sensations, especially in summer, which contrasts with the preferential occurrence of the previously reported SjS related annular erythema on the facial skin in winter. Immunologically, all four cases lacked anti-SS-A and anti-SS-B antibodies, but possessed positive anti-microsome antibodies or thyroid tests. In three cases, metal allergy was demonstrated by patch test, which might suggest that the sweat duct is the primary target of excreted metals in this condition and that underlying SjS might play some role in the higher prevalence of metal allergy or in induction of sweat duct injury, similar to the interstitial nephritis which is now thought to be an exocrine manifestation of SjS.

Adult↗
PubMed1998

Polymorphism of the 5'-flanking region of the human tumor necrosis factor (TNF)-alpha gene in Japanese.

Polymorphism of the 5'-flanking promoter/enhancer region of the TNF-alpha gene in Japanese is not well understood. To better understand it, we have determined the 1,358 base pair sequence of the 5'-flanking region of the TNF-alpha gene in nine Japanese, and identified three new polymorphisms at positions 1,031 (T to C change, termed as -1,031C), -863 (C to A, -863A), and -857 (C to T, -857T), with the former two in one allele. The level of TNF-alpha production by concanavalin A (Con A)-activated peripheral blood mononuclear cells from the five donors possessing at least one new allele was 1.8-fold higher than that from the remaining four donors with the dominant allele. The transcriptional promoter activity of the 1,031C/-863A or -857T allele in response to Con A stimulation was 2.0 or 1.7-fold higher than that of the dominant allele, respectively. The allele frequencies of -1,031C, -863A, -857T, -308A (G to A), and -238A (G to A) (the latter two were previously reported) in 575 healthy Japanese were 16.0, 14.0, 17.7, 1.7 and 2.0%, respectively. The -1,031C/-863A or -857T allele was in significant linkage disequilibrium with HLA-B61, -B39 and -DRB1*0901, or with HLA-B54, -B35, -B59, and -DRB1*0405, respectively. The newly identified alleles observed in a relatively large proportion of Japanese may be related to differences in levels of TNF-alpha production in immune responses to various stimuli among individuals.

Alleles↗
PubMed1998

Hepatic hydrothorax in the absence of ascites.

Pleural effusion due to hepatic cirrhosis and ascites is well known, but hepatic hydrothorax in the absence of ascites is a rare complication. We report a case of liver cirrhosis due to hepatitis C virus with a large and recurring pleural effusion that had an apparent abdominal source in the absence of ascites. We review the characteristics and treatment for hepatic hydrothorax in the absence of ascites.

Adult↗
PubMed1998

Genetic and serological evidence for multiple instances of unrecognized transmission of hepatitis C virus in hemodialysis units.

We investigated the unrecognized patient-to-patient transmission of hepatitis C virus (HCV) in hemodialysis units by performing phylogenetic and serological analyses of hypervariable region 1 (HVR1) of HCV. Of the 62 patients in one center, 11 were positive for HCV RNA. A total of 24 HVR1 sequences, including the minor population of sequences of HCV isolates, from each patient were closely related and classified into five clusters by phylogenetic analysis. Of the 11 patients, 5 were infected with multiple clusters of HCV. Two patients were infected with HCV during an 18-month interval between examinations, and these HVR1 sequences fell into one of the five clusters. In another hemodialysis center, 5 of the 20 patients were HCV RNA positive, and two HVR1 sequences were found to be closely related and phylogenetically derived from the same cluster. The antibody responses of these patients to the HVR1 peptides representative of the genetic clusters revealed exactly the same clustering as that shown by phylogenetic analysis. These findings suggest that phylogenetic and serological analyses of HVR1 sensitively detect unrecognized and multiple transmission of HCV occurring within the same room in hemodialysis centers. Fingerprinting analyses using hypervariable regions of infectious agents are useful in identifying the precise route of transmission of infection.

Amino Acid Sequence↗
PubMed1998

Immunoblastic lymphadenopathy-like T cell lymphoma evolving into a massive plasma cell proliferation with biclonal paraproteinemia.

We present a case of immunoblastic lymphadenopathy-like T cell lymphoma (IBL-T) who subsequently developed a massive proliferation of plasma cells. At diagnosis of IBL-T, the patient had polyclonal hypergammaglobulinemia and subsequently, while on chemotherapy, developed paraproteinemia with biclonal peaks and the IBL-T lesion was replaced with a massive proliferation of CD38-positive plasma cells. The evolution was not likely to be attributed to a new neoplastic proliferation of B cells. It appeared that two B cell clones possibly had a growth advantage among the polyclonal B cells due to a depletion of suppressor T cells or to a disturbance in the immune system.

ADP-ribosyl Cyclase↗
PubMed1998

Online evolution for a self-adapting robotic navigation system using evolvable hardware.

Great interest has been shown in the application of the principles of artificial life to physically embedded systems such as mobile robots, computer networks, home devices able continuously and autonomously to adapt their behavior to changes of the environments. At the same time researchers have been working on the development of evolvable hardware, and new integrated circuits that are able to adapt their hardware autonomously and in real time in a changing environment. This article describes the navigation task for a real mobile robot and its implementation on evolvable hardware. The robot must track a colored ball, while avoiding obstacles in an environment that is unknown and dynamic. Although a model-free evolution method is not feasible for real-world applications due to the sheer number of possible interactions with the environment, we show that a model-based evolution can reduce these interactions by two orders of magnitude, even when some of the robot's sensors are blinded, thus allowing us to apply evolutionary processes online to obtain a self-adaptive tracking system in the real world, when the implementation is accelerated by the utilization of evolvable hardware.

Biological Evolution↗
PubMed1998

Endothelin-converting enzyme-1 is expressed on human ovarian follicles and corpora lutea of menstrual cycle and early pregnancy.

We have previously reported that membrane-bound amino- and carboxypeptidases were expressed on the human follicles and corpora lutea (CL), and we proposed that these peptidases are involved in ovarian functions, probably by regulating the extracellular peptide concentrations. In this study, we examined the expression of endothelin-converting enzyme-1 (ECE-1) on human follicles and CL, which is a membrane-bound endopeptidase and is known to convert big endothelin-1 to endothelin-1. In the preovulatory follicles, immunohistochemical study showed that ECE-1 was expressed, with moderate intensity, on the theca interna cells and weakly on the granulosa cells. In the menstrual and pregnant CL, ECE-1 was highly expressed on both large and small luteal cells, indicating that ECE-1 expression increases during luteinization. Western blotting analysis revealed that the molecular mass of the ECE-1 extracted from the menstrual CL was 130 kDa and that ECE-1 was more strongly expressed on the CL in early and midluteal phases than the CL in late luteal phases. In the isolated luteinizing granulosa cells obtained from patients undergoing in vitro fertilization, ECE-1 was immunohistochemically detected on their cell surface. The activity of ECE-1 was also detected on cultured luteinizing granulosa cells by measuring endothelin-1 production from its precursor. The activity of ECE-1 was significantly enhanced by the treatment of human CG (10 U/mL) and interleukin (IL)-1 (10 ng/mL) during 4-day culture, whereas no significant alteration was observed by IL-4 (10 ng/mL) and IL-10 (10 ng/mL) treatment. These results indicate that ECE-1 is a cell surface differentiation-related molecule of human granulosa and of theca interna cells and suggest that the expression of ECE-1 is regulated by LH/human CG and cytokines.

Adult↗
PubMed1998

Improved nitric oxide detection using 2,3-diaminonaphthalene and its application to the evaluation of novel nitric oxide synthase inhibitors.

A specific and sensitive detection method for nitric oxide (NO) in living cells and tissue culture systems is required in the search for novel NO synthase (NOS) inhibitors. We have improved a fluorometric determination with 2,3-diaminonaphthalene (DAN) by the addition of 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO) as an oxidant to form NO2 from NO. This method is 3 times more sensitive than that without PTIO, and is suitable for examining the NOS-inhibitory activity of large numbers of test compounds using a 96-well microplate reader. The improved method was applied to N-monomethyl-L-arginine (L-NMMA) as a known inhibitor and the derivatives of 2-phenyl-1,2-benzisoselenazol-3(2H)-one as teat compounds in order to investigate the effect of these compounds on NO production from activated rat aortic smooth muscle cells. The results obtained indicate that this method is suitable for the rapid assay of large numbers of test compounds.

2-Naphthylamine↗
PubMed1998

Optimum conditions for the 13C-phenylalanine breath test.

We have conducted optimization studies to develop a superior 13C-phenylalanine breath test for the diagnosis of liver disease. First, we examined the optimum 13C-labeling position in phenylalanine for use in a breath test based on infrared spectroscopic detection of 13CO2 in exhaled air. L-[1-13C]Phenylalanine gave the best result. Next, a suitable dosage to give a short peak time (the time expressed in minutes at which 13CO2 excretion is maximal) after administration was determined. The 13CO2/12CO2 ratio in exhaled air after administration of 100 mg/body of L-[1-13C]phenylalanine peaked sharply at 15 min. We also examined the effect of food on the hepatic metabolism of L-[1-13C]phenylalanine. We found that a fasting period of over 7 h before the test resulted in a higher 13CO2 peak excretion. The peak appeared sooner than that in the 13C-phenacetin breath test and, therefore, the 13C-phenylalanine breath test appears preferable for the rapid evaluation of hepatic function.

Breath Tests↗
PubMed1998

Xylose transport insensitivity to catabolite inhibition by phosphoenolpyruvate:sugar phosphotransferase system in Tetragenococcus halophila.

Tetragenococcus halophila accumulates glucose and 2-deoxyglucose (dGlc) via the phosphoenolpyruvate:sugar phosphotransferase system (PTS), and pentoses, maltose, and glycerol via non-PTS carriers. Based on the discovery that xylose metabolism in T. halophila was subject to catabolite repression but not to catabolite inhibition, we designed a selection protocol for thermosensitive mutants pleiotropically unable to use sugars. One such mutant was a ptsI mutant with a thermosensitive enzyme I (EI) of the PTS (leaky at 30 degrees C). Using this ptsI mutant, catabolite inhibitions was studied. dGlc was more strongly inhibitory of glycerol uptake in the mutant than in the parent because of the leaky ptsI mutation. Thermoinactivation of EI at 42 degrees C resulted in the total loss of uptake of PTS sugars and in the virtual abolishment of glycerol uptake. However, xylose uptake of the ptsI mutant was scarcely inhibited by dGlc even after thermoinactivation of EI. These results suggest that sensitivities of non-PTS uptakes to PTS-mediated inhibition vary among non-PTS sugars.

Biological Transport↗
PubMed1998

Selective fermentation of xylose by a mutant of Tetragenococcus halophila defective in phosphoenolpyruvate:mannose phosphotransferase, phosphofructokinase, and glucokinase.

Tetragenococcus halophila is a Gram-positive halophilic lactic acid bacterium used for soy sauce fermentation. We isolated a mutant, T. halophila 3E4, triply defective in phosphoenolpyruvate:mannose phosphotransferase, phosphofructokinase, and glucokinase. 3E4 selectively metabolized pentoses such as xylose and arabinose in the presence of hexoses such as glucose and galactose. We present here an example of the metabolic engineering of catabolite control.

Fermentation↗