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T Ohta

Publications and source records attributed to T Ohta.

At least 1,027 records · Page 57Linked to original sources
PubMed1990

Recognition sites of tRNA by a thermostable tRNA(guanosine-2'-)-methyltransferase from Thermus thermophilus HB27.

Recognition sites of tRNA by tRNA(guanosine-2'-)-methyltransferase (Gm-methylase) [EC 2.1.1.34] from an extreme thermophile, Thermus thermophilus HB27, were studied by two independent methods--fragment reactions and footprinting analyses, using yeast tRNA(Phe) and Escherichia coli tRNA(fMet) as substrates. None of the tRNA-derived oligonucleotides which have the G-G sequence but are not long enough to form the "stem-loop" structure could be methylated by Gm-methylase. The 5'-half fragments having the intact D-"stem-loop" structure served as substrates for Gm-methylase, with a similar Vmax but 6-8 times larger Km, as compared with the intact tRNAs. The results of footprinting analyses were consistent with the foregoing findings. Gm-methylase protected only the D-loop region of tRNA from RNase T1 attack, but other parts of tRNA extending from the amino acid stem to the T arm became more sensitive to RNase T1, suggesting a considerable change of tRNA tertiary structure due to complex formation with Gm-methylase. These results indicate that a D-"stem-loop" structure is a prerequisite for recognition by Gm-methylase.

Amino Acids↗
PubMed1990

Morphological study of cholesterol hepatolithiasis. Report of three cases.

Three cases of pure cholesterol intrahepatic stones are compared morphologically to those of calcium bilirubinate stones. Cholesterol stones were found in the intrahepatic bile duct of the left lateral lobe in two cases and in both the left lateral and the right posterior lobe in one. Although the chronic inflammatory reaction and fibrous thickening of bile duct wall were similar in both types of hepatolithiasis, the proliferation of intrahepatic periductal glands and the production of mucin were rather mild, compared to that is the liner containing calcium bilirubinate stones. Multiple intramural cholesterol calculi and cholesterin granulomas (cholesterin crystals surrounded by foreign-body giant cells) were found within the cystically dilated small bile duct branches and/or conduits of periductal glands. The calculi and granulomas were characteristic for cholesterol hepatolithiasis. These findings suggest that the formation of the cholesterol stones differs from that of calcium bilirubinate stones; the perturbation of factors influencing cholesterol nucleation in the hepatic bile may be related to the changed microenvironment of the intrahepatic bile ducts, which is followed by the formation of cholesterol stones.

Adult↗
PubMed1990

1,24(R)-dihydroxyvitamin D3, a novel active form of vitamin D3 with high activity for inducing epidermal differentiation but decreased hypercalcemic activity.

1 alpha,25-Dihydroxyvitamin D3 (1,25(OH)2D3) is known to be a hormonally active form of vitamin D3 in the regulation of intracellular and extracellular calcium levels and of differentiation of myeloid cells and epidermal keratinocytes. We found that 1 alpha,24(R)-dihydroxyvitamin D3 (1,24(OH)2D3), a novel synthetic derivative of vitamin D3, is also active in regulating the differentiation of epidermal keratinocytes. 1,24(OH)2D3 had the same affinity as 1,25(OH)2D3 for a receptor isolated from the epidermis of newborn mice. The incubation of mouse epidermal keratinocytes with 1,24(OH)2D3 induced their differentiation in a time- and dose-dependent manner, as determined by the formation of a cornified envelope and an increase in the activity of transglutaminase. 1,24(OH)2D3 inhibited DNA synthesis of epidermal keratinocytes and also increased their cytosolic calcium level. These effects of 1,24(OH)2D3 were similar to, or rather more than, those of physiologically active 1,25(OH)2D3. However, 1,24(OH)2D3 was found to cause less hypercalcemia than 1,25(OH)2D3 when administrated intravenously to rats, suggesting its possible therapeutic value in psoriasis.

Animals↗
PubMed1990

Elucidation of chemical compounds responsible for foot malodour.

Short-chain fatty acids from the socks and feet of subjects either with strong foot odour or with weak or no foot odour were extracted with ethyl ether, and then analysed by gas chromatography/mass spectrometry (GC/MS). Short chain fatty acids were found in greater amounts from those subjects with strong foot odour. Iso-valeric acid was present in all the subjects with foot odour but was not detected in those without. Olfactory evaluations of the various short-chain fatty acid solutions were in agreement with the GC/MS analyses. By incubating sweat and lipid from subjects with strong foot odour, we succeeded in reproducing the foot malodour. GC/MS analyses of reproduced foot odour revealed that short-chain fatty acids were present in a similar composition to that found in vivo.

Adult↗
PubMed1990

Co-release of PHI and VIP in dog stomach by peripheral and central vagal stimulation.

1. The purpose of this investigation was to examine the outputs of peptide histidine isoleucine (PHI) and vasoactive intestinal peptide (VIP) from the gastric corpus in response to stimulation of the peripheral (PVS) and central (CVS) ends of the vagus nerve and to compare the effects of PHI on gastric motility and blood flow with those of VIP in atropine-treated dogs. 2. PVS and CVS caused parallel increases in gastric venous plasma concentrations of VIP and PHI. The molar ratios of the peptides (VIP/PHI) appearing in the gastric venous plasma were about 1.5 for PVS at 10 Hz, 0.65 for PVS at 40 Hz and about 0.7 for CVS at 10 Hz. 3. The molar ratio of peptide concentration extracted from the gastric corpus was about 1.5 in the muscle layer and 2.7 in the mucosal layer. 4. Intra-arterially-injected PHI was about 5 fold and 50 fold less effective in producing gastric relaxation and vasodilatation, respectively, than VIP. 5. These results indicate that PHI is co-released with VIP by peripheral vagal stimulation and by initiation of the vago-vagal reflex, and that PHI seems to have an important role in the regulation of gastric motility but not gastric blood flow in the dog.

Animals↗
PubMed1990

Mechanical, electrical and cyclic nucleotide responses to peptide VIP and inhibitory nerve stimulation in rat stomach.

1. Effects of apamin on electrical and mechanical activities and cyclic nucleotide accumulation in response to vasoactive intestinal peptide (VIP) and intramural nerve stimulation were investigated in isolated circular strips of the rat stomach in the presence of atropine and guanethidine. 2. Circular muscles generated rhythmic contractions and slow waves in the antrum but not in the fundus. Intramural nerve stimulation and VIP caused frequency- and dose-dependent relaxation of fundic strips and inhibition of spontaneous contractions of antral strips. Apamin partly reduced the responses to intramural nerve stimulation but not those to VIP. 3. In the antrum, apamin reduced inhibitory junction potentials (IJPs) evoked at the nadir of slow waves but not at their zenith. In the fundus, apamin partly decreased the amplitude of IJPs. Repetitive nerve stimulation was associated with an apamin-sensitive hyperpolarization and apamin-resistant decrease in the slow wave amplitude in the antrum. 4. VIP caused a dose-dependent hyperpolarization of fundic circular muscle membrane. In the antrum, VIP inhibited spike potentials superimposed on slow waves and it decreased the slow wave amplitude in about half of the preparations. These electrical responses to VIP were resistant to apamin. 5. Intramural nerve stimulation evoked an apamin-resistant output of VIP from muscle strips, which no longer occurred after tetrodotoxin or removal of extracellular Ca2+. 6. Intramural nerve stimulation and VIP elicited apamin-resistant increases in cyclic AMP and cyclic GMP accumulations. The effects of VIP on cyclic AMP were greater than those on cyclic GMP. The effects of intramural nerve stimulation on cyclic GMP were faster in onset than those of cyclic AMP. 7. It is suggested that VIP is a neurotransmitter of the intramural inhibitory nerves concerned in the apamin-resistant relaxation of the rat stomach.

Action Potentials↗
PubMed1990

The balance between different peptidoglycan precursors determines whether Escherichia coli cells will elongate or divide.

The rodA(Sui) mutation allows cell division to take place at 42 degrees C in ftsI23 mutant cells, which produce a thermolabile penicillin-binding protein 3 (PBP3, the septation-specific peptidoglycan transpeptidase). We show here that the mutation in rodA is a single-base change from a glutamine to a chain termination (amber) codon, and that an amber suppressor (supE) present in the strain restores the ability to produce a reduced level of normal RodA protein. The reduced level of RodA is accompanied by an increase in the levels of two other proteins (PBP2 and PBP5) encoded by genes in the rodA operon. We show that an increased level of PBP5 is by itself sufficient to restore cell division to ftsI23 cells at 42 degrees C. Two other treatments were found to restore division capacity to the mutant: an increase in PBP6 (which is a D-alanine carboxypeptidase like PBP5) or suitable concentrations of D-cycloserine. All of the above treatments have the effect of reducing the number of pentapeptide side chains in peptidoglycan and increasing the number of tripeptides. We conclude that the effect of the rodA(Sui) mutation is to indirectly increase the availability of tripeptide side chains, which are used preferentially by PBP3 as acceptors in transpeptidation. A change in the proportions of different kinds of peptide side chain in the peptidoglycan can therefore determine whether cells will divide.

Alleles↗
PubMed1990

Regulation of glucose transporters in LLC-PK1 cells: effects of D-glucose and monosaccharides.

Regulation of D-glucose transport in the porcine kidney epithelial cell line LLC-PK1 was examined. To identify the sodium-coupled glucose transporter (SGLT), we cloned and sequenced several partial cDNAs homologous to SGLT1 from rabbit small intestine (M. A. Hediger, M. J. Coady, T. S. Ikeda, and E. M. Wright, Nature (London) 330:379-381, 1987). The extensive homology of the two sequences leads us to suggest that the high-affinity SGLT expressed by LLC-PK1 cells is SGLT1. SGLT1 mRNA levels were highest when the D-glucose concentration in the culture medium was 5 to 10 mM. Addition of D-mannose or D-fructose, but not D-galactose, in the presence of 5 mM D-glucose suppressed SGLT1 mRNA levels. SGLT1 activity, measured by methyl alpha-D-glucopyranoside uptake, paralleled message levels except in cultures containing D-galactose. Therefore, SGLT1 gene expression may respond either to the cellular energy status or to the concentration of a hexose metabolite(s). By isolating several cDNAs homologous to rat GLUT-1, we identified the facilitated glucose transporter in LLC-PK1 cells as the erythroid/brain type GLUT-1. High-stringency hybridization of a single mRNA transcript to the rat GLUT-1 cDNA probe and failure to observe additional transcripts hybridizing either to GLUT-1 or to GLUT-2 probes at low stringency provide evidence that GLUT-1 is the major facilitated glucose transporter in this cell line. LLC-PK1 GLUT-1 mRNAs were highest at medium D-glucose concentrations of less than or equal to 2 mM. D-Fructose, D-mannose, and to a lesser extent D-galactose all suppressed GLUT-1 mRNA levels. Since the pattern of SGLT1 and GLUT-1 expression differed, particularly in low D-glucose or in the presence of D-galactose, we suggest that the two transporters are regulated independently.

Amino Acid Sequence↗
PubMed1990

Lipid and apolipoprotein compositions of two species of ApoA-I containing lipoproteins in young girls with insulin-dependent diabetes mellitus.

Two species of lipoproteins containing apoA-I (A-ILp), lipoprotein containing apoA-I and apoA-II (LpA-I/A-II), and lipoprotein containing apoA-I but no apoA-II were isolated from 12 girls with insulin-dependent diabetes mellitus (IDDM) and from 19 healthy controls using affinity chromatography. When characterizing the lipid and apolipoprotein compositions, we noted compositional changes. In A-ILp, the levels of lipid, except for triglyceride, and the level of apoC-III were significantly higher in IDDM. In LpA-I/A-II, the levels of lipids, except for triglyceride, the levels of apoC-III, and the ratio of apoA-I to apoA-II were significantly higher in IDDM. In lipoprotein containing apoA-I but no apoA-II, the levels of all lipids and apolipoproteins in IDDM were similar to those in the controls. The percent phospholipid in A-ILp and LpA-I/A-II was significantly higher in IDDM. All of these changes of A-ILp are similar to those associated with the reduced risk in the nondiabetic population. However, apolipoprotein changes of LpA-I/A-II may possibly be related to the accelerated atherosclerotic processes noted in patients with IDDM.

Adolescent↗
PubMed1990

Effects of exercise on coronary risk factors in obese, middle-aged subjects.

The effects of exercise (10000 walk steps/day) and diet (1500 kcal/day) for 4 months on coronary risk factors (obesity, hypertension, serum lipid and lipoprotein abnormalities) were studied in 332 obese, middle-aged subjects. Body weight, skinfold thickness, systolic and diastolic blood pressures, serum lipid and lipoproteins (total cholesterol, triglyceride, and beta-lipoprotein) improved significantly (p less than 0.05) during the program. The degree of improvement in blood pressures, serum lipids and lipoproteins was greater in abnormal blood pressure (greater than 140/90 mmHg) or abnormal serum lipid group than in normal group. A significant correlation was observed between daily number of walk steps and the improvement of body weight, diastolic blood pressure and HDL-cholesterol. Increase of daily steps during the program showed a significant (p less than 0.05) correlation to the change in HDL-cholesterol. It was suggested that mild exercise characterized by brisk walking was effective in the treatment of obesity, hypertension and low HDL-cholesterolemia in obese, middle-aged subjects.

Blood Pressure↗
PubMed1990

Infantile myofibromatosis with a solitary lesion in the skull--case report.

The term "infantile myofibromatosis" was coined in 1981 to describe a rare type of soft-tissue tumor in infants. Solitary lesions are usual, but extremely rare in the skull. An infantile case involving a lesion in the left parietal bone is described. The patient was a 6-month-old girl admitted with a mass measuring 2 x 2 cm in the left parietal region. Skull x-rays showed an osteolytic lesion with a sclerotic margin in the parietal bone. Computed tomographic (CT) scans revealed a low-density mass with homogeneous enhancement. The tumor adhered to the dura and had destroyed the left parietal bone. Histological examination disclosed spindle-shaped cells arranged in short bundles and abundant vasculature. Phosphotungstic acid hematoxylin staining revealed longitudinal fibrils resembling myofibroblasts. This is the first report in which CT findings are described in a case of infantile myofibromatosis with a solitary lesion occurring in the skull.

Female↗
PubMed1990

Coexistence of intracranial meningioma and primary malignant lymphoma--case report.

The authors present a case of multiple primary intracranial tumors of different cell types. A 62-year-old female presented with symptoms suggestive of an intracranial mass lesion. Computer tomographic scans revealed two lesions, one in the right temporal lobe and one in the posterior fossa. Both tumors were approached in one operation. The right temporal tumor was diagnosed as primary malignant lymphoma, and the right posterior fossa tumor as meningioma. Phacomatosis was ruled out as a possible etiology. Multiple primary intracranial tumors of different cell types are rare, and this is the first report of coexistent intracranial meningioma and malignant lymphoma.

Brain Neoplasms↗
PubMed1990

A new neurosurgical ventriculoscope--technical note.

A new, flexible fiberoptic ventriculoscope for observation of the ventricles and major cisterns is reported. This device has been safely used to examine patients with obstructive hydrocephalus due to lesions within the lateral and third ventricles or to congenital aqueductal stenosis. With this instrument, a pineal tumor protruding into the third ventricle was successfully observed and photographed in situ.

Adult↗
PubMed1990

Molecular cloning and nucleotide sequence of the aminopeptidase T gene of Thermus aquaticus YT-1 and its high-level expression in Escherichia coli.

Aminopeptidase T (AP-T) is a metallo-dependent dimeric enzyme of Thermus aquaticus YT-1, an extremely thermophilic bacterium. We cloned the AP-T gene from T. aquaticus YT-1 into Escherichia coli using a synthetic oligonucleotide as a hybridization probe. The nucleotide sequence of the AP-T gene was found to encode 408 amino acid residues with GTG as a start codon. The molecular weight was calculated to be 44,820. The AP-T was overproduced in E. coli (about 5% of total soluble protein) when the start codon of the gene was changed from GTG to ATG, and the gene was downstream from the tac promoter. The AP-T expressed in E. coli was heat stable and easily purified by heat treatment (80 degrees C, 30 min). The N-terminal amino acid sequence of AP-T showed similarity with that of aminopeptidase II from Bacillus stearothermophilus.

Amino Acid Sequence↗
PubMed1990

[Long-term arterial infusion chemotherapy to the cancer patients].

Arterial infusion chemotherapy is an effective method for unresectable and recurrent cancer patients. But this method had some problems, in terms of efficacy, side effect and safety. Thus, we studied these problems in 33 patients. We inserted the tube into the proper hepatic artery in 25 cases and into the aorta in 8 cases, and used anticancer drugs, such as MMC, ADM and CDDP. In this study, no serial or severe side effects were noted. On the other hand, the obstruction of catheter and artery was found in a few cases. We encountered 2 cases of CR and 11 cases of PR. The effectiveness of this method is approximately 46.4%. These results suggested that long term arterial infusion chemotherapy for outpatients was a safe and effective method from the view point of quality of life in cancer patients.

Adult↗
PubMed1990

[Study of intraarteric infusion chemotherapy with drug delivery system].

We have studied the effect of intraarteric infusion chemotherapy with missile chemotherapy, induced hypertensive chemotherapy and/or two-route infusion chemotherapy in 14 liver tumors (7 cases with liver metastasis from gastric cancer, 3 cases with liver metastasis from colonic cancer, 4 cases with hepatoma). Results indicated that PR in 6 (46.1%) out the 13 evaluated cases. The toxicity was not evident except for slight bone marrow depression with 5 cases and a low grade fever with 2 cases. These results indicate that intraarterial infusion chemotherapy with drug delivery system can be considered one of the treatment therapies available for a nonresectable tumor.

Aged↗