Biomedical subjects

T Iida

Publications and source records attributed to T Iida.

At least 145 records · Page 8Linked to original sources

PubMed1999

Occurrence of free D-amino acids and aspartate racemases in hyperthermophilic archaea.

The occurrence of free D-amino acids and aspartate racemases in several hyperthermophilic archaea was investigated. Aspartic acid in all the hyperthermophilic archaea was highly racemized. The ratio of D-aspartic acid to total aspartic acid was in the range of 43.0 to 49.1%. The crude extracts of the hyperthermophiles exhibited aspartate racemase activity at 70 degrees C, and aspartate racemase homologous genes in them were identified by PCR. D-Enantiomers of other amino acids (alanine, leucine, phenylalanine, and lysine) in Thermococcus strains were also detected. Some of them might be by-products of aspartate racemase. It is proven that D-amino acids are produced in some hyperthermophilic archaea, although their function is unknown.

Amino Acid Isomerases↗

PubMed1999

Isolation, cloning, and expression of an acid phosphatase containing phosphotyrosyl phosphatase activity from Prevotella intermedia.

A novel acid phosphatase containing phosphotyrosyl phosphatase (PTPase) activity, designated PiACP, from Prevotella intermedia ATCC 25611, an anaerobe implicated in progressive periodontal disease, has been purified and characterized. PiACP, a monomer with an apparent molecular mass of 30 kDa, did not require divalent metal cations for activity and was sensitive to orthovanadate but highly resistant to okadaic acid. The enzyme exhibited substantial activity against tyrosine phosphate-containing peptides derived from the epidermal growth factor receptor. On the basis of N-terminal and internal amino acid sequences of purified PiACP, the gene coding for PiACP was isolated and sequenced. The PiACP gene consisted of 792 bp and coded for a basic protein with an M(r) of 29,164. The deduced amino acid sequence exhibited striking similarity (25 to 64%) to those of members of class A bacterial acid phosphatases, including PhoC of Morganella morganii, and involved a conserved phosphatase sequence motif that is shared among several lipid phosphatases and the mammalian glucose-6-phosphatases. The highly conservative motif HCXAGXXR in the active domain of PTPase was not found in PiACP. Mutagenesis of recombinant PiACP showed that His-170 and His-209 were essential for activity. Thus, the class A bacterial acid phosphatases including PiACP may function as atypical PTPases, the biological functions of which remain to be determined.

Acid Phosphatase↗

PubMed1999

Isotype-specific changes in the amount of beta-tubulin RNA in synchronized tobacco BY2 cells.

The 3'-ends of the beta-tubulin cDNA were amplified from tobacco BY2 polyA+ RNA. According to the differences in the predicted amino acid sequence at the extreme C-terminal, they were grouped into three different isotypes, NTB1 in which "EEGDYYEEDEEDLNEA", NTB2 in which "EEEYYEDEEEA QED" and NTB3 in which "DECEYEEEEEYDHEGN" follows the conservative "YQQYQDATAD" sequence. Using unique 3'-untranslated regions as probes, changes in the RNA levels of each beta-tubulin isotype were determined by dot-blot hybridization. The levels exhibited characteristic rhythms in the cell cycle. NTB1 RNA was highest in S phase in comparison to NTB2 RNA level which was highest in late G2. On the other hand, NTB3 RNA level was highest in early G2.

3' Untranslated Regions↗

PubMed1999

Complete nucleotide sequence of the prophage VT2-Sakai carrying the verotoxin 2 genes of the enterohemorrhagic Escherichia coli O157:H7 derived from the Sakai outbreak.

The enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain RIMD 0509952, derived from an outbreak in Sakai city, Japan, in 1996, produces two kinds of verotoxins, VT1 and VT2, encoded by the stx1 and stx2 genes. In the EHEC strains, as well as in other VT-producing E. coli strains, the toxins are encoded by lysogenic bacteriophages. The EHEC O157:H7 strain RIMD 0509952 did not produce plaque-forming phage particles upon inducing treatments. We have determined the complete nucleotide sequence of a prophage, VT2-Sakai, carrying the stx2A and stx2B genes on the chromosome, and presumed the putative functions of the encoded proteins and the cis-acting DNA elements based on sequence homology data. To our surprise, the sequences in the regions of VT2-Sakai corresponding to the early gene regulators and replication proteins, and the DNA sequences recognized by the regulators share very limited homology to those of the VT2-encoding 933W phage carried by the EHEC O157:H7 strain EDL933 reported by Plunkett et al. (J. Bacteriol., p1767-1778, 181, 1999), although the sequences corresponding to the structural components are almost identical. These data suggest that these two phages were derived from a common ancestral phage and that either or both of them underwent multiple genetic rearrangements. An IS629 insertion was found downstream of the stx2B gene and upstream of the lysis gene S, and this might be responsible for the absence of plaque-forming activity in the lysate obtained after inducing treatments.

Bacterial Toxins↗

PubMed1999

Human T cell leukemia virus type I-associated myelopathy in a patient with systemic lupus erythematosus.

A case of human T cell leukemia virus type I (HTLV-1) associated myelopathy (HAM)/tropical spastic paraparesis (TSP) with 14-year history of systemic lupus erythematosus (SLE) is reported. For 9 years, the numbness of the feet and sacral region progressed with occasional urinary incontinence and constipation. She was admitted to hospital due to gait disturbance and aggravation of SLE and the diagnosis of HAM/TSP was confirmed, indicating that HTLV-1 infection is associated with the development of not only HAM/TSP but also SLE.

Blotting, Western↗

PubMed1999

[Dynamic MRI of intraductal papilloma].

MRI findings were retrospectively investigated in five cases of papilloma of the breast. The tumors, which had a smooth margin, were 8-28 mm in size and round(3), oval(1), and irregular(1)in shape. All tumors were well enhanced with Gd-DTPA: four were enhanced homogeneously and one inhomogeneously. Dynamic study demonstrated two different time-intensity curves: 1) an early enhancement pattern and 2) a slower enhancement pattern. Three tumors showed the early enhancement pattern, which is well known to be characteristic of malignancy, while the other two showed the slower enhancement pattern. In the latter cases, the intensity could not be measured accurately because the tumors were too small to set the ROI exactly within them. In conclusion, three of five papillomas demonstrated the early enhancement pattern on dynamic study, which means that the time-intensity curve cannot distinguish papilloma from carcinoma. Therefore, morphological features should also be taken into consideration in making the diagnosis.

Adult↗

PubMed1999

[Effect of protoporphyrin on digestive tract absorption of dioxins in rats].

This paper presents the fecal excretion of polychlorinated dibenzo-p-dioxin (PCDD) congeners, and polychlorinated dibenzofuran (PCDF) congeners in male rats fed a diet containing 0.5% disodiumprotoporphyrin (PPNa) or 0.5% hemin. The animals were administered 4 g of 0.5% PPNa or 0.5% hemin diet containing 0.5 ml of the causal rice-bran oil of Yusho that had occurred in the Southwest part of Japan in 1968 and kept on the same diet for five days. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with 0.5% PPNa were 2.1 and 1.9 times higher, respectively, than that in the group fed with a control diet. Hemin did not show any significant effect on the inhibition of absorption of dioxins. Next, the rats were given a diet containing 0.5% PPNa or 0.5% Hemin for four weeks after a week interval from the day of the causal rice-bran oil administration. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with 0.5% PPNa were stimulated 2.1 times higher, respectively, than that in the group fed with a control diet. Hemin did not show any significant effect on the inhibition of re-absorption of dioxins.

Animals↗

PubMed1999

[Effect of green vegetable on digestive tract absorption of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in rats].

The effect green vegetable on fecal excretion of polychlorinated dibenzo-p-dioxin (PCDD) congeners and polychlorinated dibenzofuran (PCDF) congeners was examined in male rats. The rats were administered 10% vegetable diets or a basal diet containing 0.2 ml of the causal rice-bran oil of Yusho that had occurred in the Southwest part of Japan in 1968 and kept on the same diet for five days. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with Komatsuna, Mitsuba, Spinach and Perilla were 7.6-11.6 and 6.5-9.4 times higher, respectively, than that in the group fed with a basal diet. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with Kale, Chinese chive, Shungiku, Chingentsuai, Green lettus and Sweet pepper were 3.3-4.8 and 4.3-4.5 times higher, respectively, than that in the basal group. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with Chinese cabbage, Broccoli, Onion, Welsh onion, Cabbage and Celery were 1.6-3.0 and 1.2-1.3 times higher, respectively, than that in the basal group. A correlation between Chllophyll consumption and fecal excretion of PCDD and PCDF congeners was highly significant (p < 0.01). Next, we investigated the fecal excretion of PCDD and PCDF congeners from day 8 to day 35 in rats administered with 0.5 ml of the rice oil. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with Perilla, Kale and Spinach were 3.1-4.9 and 3.0-3.6 times higner, respectively, than that in the basal group. The presents results suggest that the green vegetables might be useful in treatment of humans exposed to PCDD and PCDF congeners.

Animals↗

PubMed1999

[Blood PCB analysis by capillary column-gas chromatograph/quadruple mass spectrometer--comparison with packed column-electron capture detector/gas chromatograph].

The contents of polychlorinated biphenyls (PCBs) in the blood of Yusho patients (Y) and normal subjects (N) were analyzed, using a gas-chromatograph equipped with a capillary column/quadruple mass spectrometer (capillary column GC/MS). While the average of the content of blood PCBs was 679 ppt in N, those were 2960, 1480 and 1090 ppt in Y diagnosed previously as A, B and C patterns, respectively. The contents of non-ortho coplanar PCBs (3,3',4,4' Tetra-, 3,3',4,4',5-Penta- plus 3,3',4,4',5,5'-Hexa-CB) were 0.9-2.1 ppt in Y, and 0.8 ppt in N. The contents of eight mono-ortho coplanar PCBs having the toxic equivalency factors (TEFs) were 118-424 (Y) and 78 ppt (N), respectively. The differences between Y and N in the species of mono-ortho coplanar PCBs contained were observed as follows: 2,3,3',4,4',5- and 2,3,3',4,4',5'-Hexa-CB were predominant in Y, whereas 2,3,4,4',5-Penta-CB was a major congener in N. The levels of di-ortho coplanar PCBs (2,2',3,4,4',5,5' plus 2,2',3,3',4,4'5-Hepta-CB) were determined to be 195-608 and 98 ppt in Y and N, respectively. In both groups, the content of the former isomer was greater than the latter. Total TEQ values were 0.214-1.226 ppt in Y, and 0.148 ppt in N. The analyses were also performed by a conventional method in which a GC equipped with a packed column/electron capture detector (packed column GC/ECD) was used, and the results obtained were compared with those by capillary column GC/MS method. The results showed that the total PCB levels obtained by capillary column GC/MS method were 56-61% in Y and 67% in N of those obtained by packed column GC/ECD method.

Adult↗

PubMed1999

[Detection of early hilar lung cancers with fluorescence bronchoscopy].

The development of fluorescence bronchoscopy has made it possible to diagnose locally superficial hilar lung cancers such as carcinoma in situ, and in some cases atypical squamous metaplasia thought to be precancerous lesions. The selection of a treatment modality can be difficult for early hilar lung cancers due to problems associated with multiple lung carcinomas and the large number of heavy smokers afflicted. Many patients also have decreased pulmonary function. If carcinoma in situ and microinvasive carcinomas can be detected early, it may be possible to treat them radically with a less invasive method than surgery, such as endoscopic laser therapy. Centrally arising squamous cell carcinoma of the tracheobronchial tree, especially in heavy smokers, is thought to develop in multiple stages from squamous metaplasia, to atypical squamous metaplasia, followed by carcinoma in situ, and finally invasive cancer. However, it is hoped that preventive medicine for lung cancer will be established whereby patients with localized atypical squamous metaplasia detected by fluorescence bronchoscopy can be carefully monitored and motivated to stop smoking, and also administered chemopreventive agents.

Adult↗

PubMed1999

Establishment and characterization of human ovarian clear cell adenocarcinoma cell line (SMOV-2), and its cytotoxity by anticancer agents.

A novel cell line derived from a surgically resected ovarian clear cell adenocarcinoma of 46 year-old Japanese woman was established and designated SMOV-2. Cells of this lineage were continuously propagated in vitro over 44 months and were grown in a mono-layered sheet with a doubling time of 48.2 hours. The histopathology of the transplanted tumor in nude mice showed two distinctive cell types, hobnail cells and clear cells, which demonstrated recognizable characteristics of clear cell adenocarcinoma, as compared to resected original tumors. At the molecular level, SMOV-2 cells had the wild type p53 genes that were free from missence mutations. Anticancer agents (cisplatin and paclitaxel) were examined for cytotoxity against these SMOV-2 cells in vitro. These examinations revealed that the chemotherapy-treated cells had decreased proliferation, cell cycle arrests, and induction of apoptosis by the anticancer agents. As can be gleaned from this research, SMOV-2 is a valuable model to study the mechanism of apoptotic responses of solid tumors to future anticancer agents.

Adenocarcinoma, Clear Cell↗

PubMed1998

Glutathione downregulates the phosphorylation of I kappa B: autoloop regulation of the NF-kappa B-mediated expression of NF-kappa B subunits by TNF-alpha in mouse vascular endothelial cells.

Nuclear factor-kappa B (NF-kappa B) regulates gene expression upon immune and inflammatory responses. It has been demonstrated that redox regulation by thiols is involved in the signal-transduction cascade. In this study, we examined the effect of glutathione (GSH) on the NF-kappa B activity and the expression of NF-kappa B subunits induced by tumor necrosis factor-alpha (TNF-alpha) using mouse vascular endothelial cells. GSH inhibited the serine phosphorylation of I kappa B-alpha by TNF-alpha, leading to the downregulation of NF-kappa B-DNA binding activity followed by decreased expression of p65/p50 and I kappa B mRNAs. The regulation of the autoregulatory loop for the NF-kappa B activation and the expression of NF-kappa B subunits may be important in endothelial cells in response to cytokines.

Animals↗

PubMed1998

FKBP-type peptidyl-prolyl cis-trans isomerase from a sulfur-dependent hyperthermophilic archaeon, Thermococcus sp. KS-1.

A gene encoding an FK506 binding protein (FKBP)-type peptidyl-prolyl cis-trans isomerase (PPIase) was cloned from a hyperthermophilic archaeon, Thermococcus sp. KS-1, and sequenced. This gene encoded an FKBP with 159 amino-acid residues with a molecular mass of 17.6kDa. Two insertion sequences with 13 and 44 amino acids were found in the regions corresponding to the bulge and flap regions of human FKBP-12, respectively. Comparison with other archaeal FKBP sequences obtained from reported genome sequences revealed that the insertion sequences in the bulge and flap regions were common to archaeal FKBPs. It was also revealed that archaeal FKBPs are classified into two groups: one is approx. 17kDa and the other 27kDa. This Thermococcus FKBP (TcFK) belonged to the smaller archaeal FKBP. In this TcFK, 9 out of 15 amino acid residues forming the FK506 binding pocket of human FKBP12 were found. This gene was expressed in Escherichia coli and the recombinant protein was purified. The purified protein showed PPIase activity and its activity was inhibited by FK506 with an IC50 of 7 microM. This enzyme showed high kinetic stability with a half-life of 40 min at 100 degrees C. Catalytic efficiency of this recombinant PPIase was 1.2-times higher with the substrate N-succinyl-A-L-P-F-p-nitroanilide than with N-succinyl-A-A-P-F-p-nitroanilide.

Amino Acid Sequence↗

PubMed1998

Group II chaperonin in a thermophilic methanogen, Methanococcus thermolithotrophicus. Chaperone activity and filament-forming ability.

A gene encoding 544 amino acids for a subunit of group II chaperonin (thermosome) was cloned from a thermophilic methanogen, Methanococcus thermolithotrophicus. The deduced amino acid sequence showed 66.5, 56.1, and 20.1% similarities to those of Methanopyrus kandleri and Thermoplasma acidophilum and group I chaperonin of Escherichia coli, respectively. We call this chaperonin MTTS (M. thermolithotrophicus thermosome). The MTTS gene was expressed in E. coli. The purified recombinant MTTS seemed to be monomeric on gel filtration in the absence of Mg2+ and ATP. The monomer assembled to an oligomer (complex) in the presence of 50 mM MgCl2, 0.25 mM ATP, and 0.3 M (NH4)2SO4. It was eluted immediately before the elution volume of E. coli GroEL tetradecamer on gel filtration with a TSKgel G3000SWXL column. This reconstructed MTTS complex showed the cylindrical structure with two stacked rings in electron microscopy. The MTTS complex formed filamentous structures in the presence of Mg2+ and ATP at the protein concentration above 3.0 mg/ml. This filament formation was reversible. The MTTS filament was dissociated to the complex by dilution to the protein concentration of 0.2 mg/ml, even in the presence of Mg2+ and ATP. The MTTS complex exhibited weak ATPase activity with the hydrolysis rate of 74 mol of ATP hydrolysis/mol of MTTS complex/min at 70 degreesC. The MTTS complex promoted the refolding of chemically denatured thermophilic archaeal citrate synthase and glucose dehydrogenase at 50 degreesC in an ATP-dependent fashion. The analysis of nucleotide specificity of chaperone activity of MTTS suggested that it was coupled with hydrolysis of ATP, CTP, or UTP.

Adenosine Triphosphatases↗

PubMed1998

Relation between evolutionary distance and enzymatic properties among the members of the CYP52A subfamily of Candida maltosa.

The CYP52A subfamily of the alkane-assimilating yeast Candida maltosa consists of six structurally related isoforms. Four of them (CYP52A3, 4, 5, and 9) are strongly induced by alkanes and play an important role for the conversion of various alkanes and fatty acids. Taking advantage of a homologous overexpression system, we found in the present study that both of the two other CYP52A forms, CYP52A10 and CYP52A11, represent specialists for the hydroxylation of lauric acid suggesting their preference for short-chain fatty acids. At the same time, they hydroxylated palmitic acid only moderately and failed to convert hexadecane. Based on the now completed knowledge about the principal substrate specificities of all members of the CYP52A subfamily of C. maltosa, it became apparent that evolutionarily more distantly related P450 forms developed either to alkane or to fatty acid hydroxylases, whereas P450 forms which retained the ability to convert both types of substrates were also found to be evolutionarily related to both alkane and fatty acid hydroxylases.

Candida↗

PubMed1998

Essential role of mitochondrially encoded large rRNA for germ-line formation in Drosophila embryos.

In Drosophila, pole cells, the progenitors of the germ line, are induced by the factors localized in the posterior pole region of oocytes and cleavage embryos, or germ plasm. Polar granules in germ plasm are electron-dense structures and have been proposed to contain factors essential for pole cell formation. Mitochondrially encoded large ribosomal RNA (mtlrRNA) has been identified as a component of polar granules. We previously have shown that mtlrRNA is able to rescue embryos that fail to form pole cells as a result of UV irradiation. However, there is a possibility that the function of mtlrRNA is limited to UV-irradiated embryos, and the question of whether mtlrRNA is required for the normal pathway leading to pole cell formation remains unanswered. In this study, we report that the reduction of mtlrRNA in germ plasm by injecting anti-mtlrRNA ribozymes into cleavage embryos leads to their inability to form pole cells. Other components of germ plasm, namely oskar mRNA, germ cell-less mRNA, and Vasa and Tudor proteins appear to be unaffected in these ribozyme-injected embryos. These results support an essential role for mtlrRNA in pole cell formation. We propose that mitochondrially encoded molecules participate in a key event in early cell-type specification.

Animals↗

PubMed1998

Amino acid sequence and D/L-configuration determination of peptides utilizing liberated N-terminus phenylthiohydantoin amino acids.

In this paper, we examined the possibility of using conventional Edman degradation with phenyl isothiocyanate for the simultaneous determination of both the sequence and the D/L-configuration of amino acids in peptides. Boron trifluoride and HCl-methanol (1:10, v/v) were adopted as the cyclization/cleavage and conversion reagents instead of the respective use of anhydrous trifluoroacetic acid (TFA) and 20% aqueous TFA to suppress the amino acid residue racemization. The enantiomeric separation of 18 phenylthiohydantoin amino acids was achieved on two types of chiral stationary phases bonded with beta-cyclodextrin. The proposed Edman procedure was applied to a synthetic beta-amyloid 1-16 with all L-forms as a model peptide, affording the amino acid sequence and configuration determination up to 12 residues.

Chromatography, High Pressure Liquid↗

PubMed1998

Hammerhead ribozymes against gamma-glutamylcysteine synthetase mRNA down-regulate intracellular glutathione concentration of mouse islet cells.

gamma-Glutamylcysteine synthetase (gamma-GCS) is a key enzyme in glutathione synthesis and is thought to play a significant role in intracellular detoxification systems. To specifically suppress gamma-GCS gene expression, we constructed two different hammerhead ribozymes against gamma-GCS mRNA transcripts. Two cleavage sites were targeted as follows: site 1 for anti-gamma-GCS ribozyme (H), a GUU triplet located from +348 to +350 of the gamma-GCS heavy chain, and site 2 for anti-gamma-GCS ribozyme (L), a GUU triplet located from +235 to +237 of the gamma-GCS light chain. The anti-gamma-GCS ribozymes effectively cleaved gamma-GCS mRNA in a cell-free system. When transfected into a Min-6 mouse islet cell line, these anti-gamma-GCS ribozymes not only suppressed gamma-GCS gene expression, but also reduced intracellular glutathione concentration. These results suggest that the ribozyme-mediated down-regulation of gamma-GCS gene expression may be useful for analyzing the glutathione-associated cellular defense systems of pancreatic islet cells.

Animals↗