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Biomedical subjects

T Eguchi

Publications and source records attributed to T Eguchi.

At least 145 records · Page 8Linked to original sources

Chemo-enzymatic synthesis of optically pure l-leucovorin, an augmentor of 5-fluorouracil cytotoxicity against cancer.

Optically pure l-leucovorin was synthesized on a large scale by the combination of chemical and enzymatic processes. After reduction of folate with zinc, dihydrofolate was reduced asymmetrically to (6)-tetra-hydrofolate by use of dihydrofolate reductase from E. coli C600/pTP600, with simultaneous NADPH cofactor recycling using glucose dehydrogenase from Gluconobacter scleroideus KY3613. Calcium l-leucovorin.4H2O (113 g) was obtained from (6S)-tetrahydrofolate via 5,10-methyenyltetrahydrofolate by formylation, reflux, addition of calcium ions and floricil column chromatography, with an overall yield of 50% based on folate. The l-leucovorin showed optical purity of 99.9% de as (6S)-form.

Escherichia coli↗

Effects of 1,25-dihydroxyvitamin D3 and its analogs on butyrate-induced differentiation of HT-29 human colonic carcinoma cells and on the reversal of the differentiated phenotype.

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) greatly enhances sodium butyrate (NaB)-induced enterocyte differentiation of HT-29 human colonic carcinoma cells while 1,25-(OH)2D3 alone induces growth restriction without associated differentiation. In the present study, the efficacies of various analogs of 1,25-(OH)2D3 to enhance NaB-induced HT-29 differentiation and to prolong the reversal of the differentiated phenotype under NaB-free growth conditions were subsequently examined. Extent of HT-29 differentiation was assessed by measurement of alkaline phosphatase (AP) activity, appearance of mucin-producing cells, changes in morphological characteristics, and expression of differentiation-associated cytokeratin proteins. Among active analogs of 1,25-(OH)2D3, 26,26,26,27,27,27-hexafluoro-1,25-(OH)2D3 (F6-1,25-(OH)2D3), 24,24-difluoro-24-homo-1,25-(OH)2D3, and 26,27-dimethyl-1,25-(OH)2D3 were 100-, 10-, and 5-fold, respectively, more effective than 1,25-(OH)2D3 in enhancing NaB-induced mucin production. Combined use of NaB and F6-1,25-(OH)2D3 (10(-9) M) also induced HT-29 cells to form highly differentiated goblet-like enterocytes, and increased both cellular AP enzymatic activity and tissue-type cytokeratin content. This differentiated state was qualitatively more advanced than that achieved by a combination of NaB and 10(-7) M 1,25-(OH)2D3. NaB-mediated HT-29 differentiation (in short-term inductions) was found to be reversible following a return to NaB-free medium. HT-29 cells differentiated by combined use of NaB and 1,25-(OH)2D3 or its analogs exhibited a significant prolonged reversal time relative to cells differentiated with NaB alone. The most prominent effect was achieved using cells differentiated with NaB and 10(-9) M F6-1,25-(OH)2D3 which exhibited a 7-fold prolonged reversal time over colonocytes differentiated by NaB alone. Our data suggest that a combined use of NaB and 1,25-(OH)2D3 or its derivatives may provide a convenient in vitro model system to probe molecular events associated with steroid-target tissue interactions in a differentiating cell system as commonly occurs in vivo. Such an analysis might lend itself to design of a rational combination differentiation-based therapy for the clinical management of colon cancer.

Butyrates↗

Simultaneous determination of keto and non-keto bile acids in human serum by gas chromatography with selected ion monitoring.

A reliable method for the simultaneous determination of keto and non-keto bile acids in human serum was developed. Carbonyl substituents of bile acid ethyl esters were converted into methyloxime and hydroxyl substituents into dimethylethylsilyl ethers and the products were analysed directly by capillary gas chromatography with selected ion monitoring using [2H4]chenodeoxycholic and [2H4]3 alpha-hydroxy-7-oxo-5 beta-cholanoic acids as internal standards. The bile acid peaks on the selected ion chromatogram were separated without interference from endogenous substances present in serum. Recoveries of individual keto bile acids added to serum range from 74.4 to 94.7% with a mean of 87.1%. Eight kinds of keto bile acids not previously found in sera of normal subjects, namely 3-oxo-, 3-oxo-7 alpha-hydroxy-, 3-oxo-12 alpha-hydroxy-, 3 alpha-hydroxy-7-oxo, 3 alpha-hydroxy-12-oxo-, 3-oxo-7 alpha,12 alpha-dihydroxy-, 3 alpha,7 alpha-dihydroxy-12-oxo- and 3 alpha,12 alpha-dihydroxy-7-oxo-5 beta-cholanoic acids were identified and quantified. The total concentration of keto bile acids was found to be 0.16 +/- 0.08 nmol/ml and constituted 2.9 +/- 1.5% of that of the usual non-keto bile acids in peripheral venous serum.

Adult↗

Type-C virus-like particles in a human B-cell lymphoma cell line.

Type-C virus-like particles (VLPs) were found in an Epstein-Barr (EB) virus-infected human B-cell lymphoma cell line, SP-50B, that was established from a patient with non-Hodgkin lymphoma. The cell line continuously produces a small number of type-C VLPs, 150-200 nm in diameter, over 1 year. SP-50B cells were negative for HTLV-I and HTLV-II antigens and did not contain the HTLV-I genome. In addition, two EB virus nuclear antigen (EBNA)-positive B-cell lines, SP-54-Cord and SP-57-CLL, were established from human cord blood and chronic lymphocytic leukemia (CLL), respectively, by coculture with lethally irradiated SP-50B cells. Type-C VLPs with the same morphology were also found in both cell lines.

Antibodies, Antinuclear↗

Synthesis and biological activity of (22E,25R)- and (22,25S)-22-dehydro- 1 alpha,25-dihydroxy-26-methylvitamin D3.

Both 25-epimers of (22E)-22-dehydro-1 alpha,25-dihydroxy-26-methylvitamin D3 [22-dehydro-26-methyl-1,25-(OH)2D3] were synthesized. The biological activity of these compounds was tested in binding affinity to chick intestinal receptor protein of 1 alpha,25-dihydroxy-vitamin D3 [1,25-(OH)2D3] and in stimulating for intestinal calcium transport and bone calcium mobilization with vitamin D-deficient rats. The relative potency of (25R)- and (25S)-22-dehydro-26-homo-1,25-(OH)2D3 and 1,25-(OH)2D3 in competing for the intestinal cytosolic binding was 1.7:1.5:1. A similar order of activity was observed on intestinal calcium transport and bone calcium mobilization. In the ability for stimulation of intestinal calcium transport, (25R)- and (25S)-22-dehydro-26-methyl-1,25-(OH)2D3 were about 3.6 and 2.1 times as active as 1,25-(OH)2D3, respectively. In bone calcium mobilization tests, (25R)- and (25S)-22-dehydro-26-methyl-1,25-(OH)2D3 were estimated to be 2.2 and 1.6 times as potent as 1,25-(OH)2D3, respectively.

Animals↗

Prominent meningeal enhancement adjacent to meningioma on Gd-DTPA-enhanced MR images: histopathologic correlation.

To assess tissue changes responsible for enhancement of the meninges adjacent to meningiomas on magnetic resonance (MR) images, the authors correlated the MR imaging characteristics of meningeal lesions seen before and after administration of gadolinium diethylenetriamine-pentaacetic acid (DTPA) with the appearance of these lesions on contrast material-enhanced computed tomographic (CT) images and with histopathologic findings in four patients. Histopathologic examination of meninges showed increased loose connective tissue, hypervascularity, and dilated vessels. There was neoplastic infiltration of the dura mater in two patients but it was restricted to the immediate junction of neoplasm and dura mater, with maximum peripheral extension within 1 mm of the tumor margin. In both patients the meninges were enhanced far beyond the neoplastic infiltration. The other two patients showed no infiltration of dura mater. These findings suggest that pathologic enhancement of meninges adjacent to meningioma after administration of Gd-DTPA mainly represents reactive changes to the neoplasm and does not necessarily indicate neoplastic involvement.

Female↗

Effect on carbon lengthening at the side chain terminal of 1 alpha,25-dihydroxyvitamin D3 for calcium regulating activity.

A series of analogs of 1 alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3 (1)] with alkyl substitutions in 26- and 27-positions have been tested for their activity 1) in competing with 1,25-(OH)2D3 for binding to chick intestinal cytosol receptor, 2) in ability for formation of multinucleated cells (MNC) with various osteoclastic cell characteristics from blast cells, and 3) in stimulating bone calcium mobilization in vitamin D-deficient rats. The relative potencies of 1,25-(OH)2D3, 1 alpha,25-dihydroxy-26,27-dimethylvitamin D3 (2), 1 alpha,25-dihydroxy-26,27-diethylvitamin D3 (3), and 1 alpha,25-dihydroxy-26,27-dipropylvitamin D3 (4) in competing for intestinal cytosolic binding were 1:1.1:0.25:0.05. The similar order of the abilities on formation of the multinucleated cells in the same series was observed. In a bone calcium mobilization test with vitamin D-deficient rats, 1 alpha,25-dihydroxy-26,27-dimethylvitamin D3 showed slightly less activity than 1,25-(OH)2D3 at 12 h after administration, but long lasting activity was observed during time course experiments. 1 alpha,25-Dihydroxy-26,27-diethylvitamin D3, and 1 alpha,25-dihydroxy-26,27-dipropylvitamin D3 were found to be much less active than 1,25-(OH)2D3 in a bone calcium mobilization test.

Animals↗

[A rapid diagnosis (SK-013) for periodontitis based on the enzymatic activity of periodontopathic bacteria. Study on the characterization of the SK-013 and the enzyme specificity].

We present studies for development of an enzymatic diagnostic method for periodontitis. A rapid and sensitive diagnostic method named SK-013 was provided by Sunstar Inc. to evaluate the peptidase activities specifically derived from periodontopathic bacteria such as Bacteroides gingivalis, Bacteroides forsythus and Treponema denticola and some strains of Capnocytophaga species. The results obtained indicated the specificity of the enzymatic reaction in this system.

Bacteroides↗

[Changes in content of excitatory amino acids in the brain and cerebrospinal fluid].

Recently epilepsy is analysed on terms of two different conditions, seizure susceptibility and seizure induction. Much attention has been paid to excitatory amino acids in these conditions. An examination was made of changes of glutamate and aspartate in the brain and cerebrospinal fluid (CSF) in a cat amygdaloid kindling model so as to determine whether excitatory amino acids are possibly involved in seizure susceptibility and seizure induction. Twenty crossbred adult cats were divided into four groups: a sham operation group (Sh) as the control, just after stage 4 seizure group (S4), just after stage 6 seizure group (S6), and stage 6 group 2 weeks after the last stimulation (S6-2W). CSF, blood and 13 individual brain regions were taken at 9 + 4 degrees C, and their glutamate and aspartate contents were measured by high performance liquid chromatography (HPLC). Glutamate concentration was significantly higher in the S6 group than in the Sh group in CSF and less in the S6 group than in the Sh group in the left and right amygdala, hippocampus and piriform cortex. No aspartate could be detected in the CSF of any group, nor did it change significantly in the blood or brain. Based on the above results, the content and release of glutamate and aspartate apparently do not change in seizure susceptibility and glutamate is released from kindled tissues in seizure induction, thus showing it to be involved in seizure induction in a cat amygdaloid kindling.

Animals↗

The establishment of Epstein-Barr virus nuclear antigen-positive (SP-50B) and Epstein-Barr virus nuclear antigen-negative (SP-53) cell lines with t(11;14)(q13;q32) chromosome abnormality from an intermediate lymphocytic lymphoma.

Two lymphoma cell lines, SP-50B and SP-53, were established from peripheral blood of a 58-year-old woman with leukemic conversion of intermediate lymphocytic lymphoma. These cell lines grew in suspension with or without forming clumps of cells. SP-50B was morphologically similar to the common Epstein-Barr (EB) virus-transformed lymphoblastoid cell lines and was positive for EB virus nuclear antigen (EBNA), whereas SP-53 closely resembled the patient's lymphoma cells and was negative for EBNA. Both cell lines expressed the same phenotypic markers as original lymphoma cells (CpIg+, SmIg+, OKIa1+, Leu12+) and possessed t(11;14)(q13;q32) chromosome translocation. These results indicate that although morphologically different, SP-50B and SP-53 were both derived from patient's lymphoma cells. The long-term cultivation of EBNA-positive and EBNA-negative B-cell lymphoma lines from a single donor has not been previously reported. These cell lines would provide useful tools for studying the oncogenic role of EB virus and bcl-1 oncogene that is located on chromosome 11q13.

Antigens, Viral↗

Nicotinic acetylcholine receptor-ion channels involved in synaptic currents in bullfrog sympathetic ganglion cells and effects of atropine.

The nicotinic acetylcholine receptor-ion channels (AChR channels) of the bullfrog sympathetic ganglion cells were studied with a two-electrode voltage clamp technique. The decay phase of the fast excitatory postsynaptic current (fast e.p.s.c.) in B-type neurones followed a double exponential function whose time constants were 3.2 and 8.0 ms at -60 mV and increased with membrane hyperpolarization. Likewise, the decay phase of the fast e.p.s.c. in C-type neurones was double-exponential with time constants of 4.4 and 12.3 ms (at -60 mV). The miniature e.p.s.c. in B-type neurones also decayed with a double exponential function (2.7 and 15.4 ms at -100 mV). Analysis of acetylcholine-induced current fluctuations revealed the power spectral density distribution of a double Lorentzian function which yielded the time constants of elementary events [tau noise(f) and tau noise(s): 1.7 and 29.7 ms, respectively, at -100 mV] and the averaged elementary conductance (gamma: 7.8 pS). The amplitude of fast e.p.s.c. and the time constant of the fast component of its decay phase decreased during the initial ("acute") phase (within 15 min) of the action of atropine (3 microM), but recovered during the later ("chronic") phase (more than 30 min after application) of the action. The slow component was affected by atropine in a manner similar to the fast component during the "acute" phase. During the "chronic phase", however, the slow time constant recovered and exceeded the control value. Furthermore, this prolongation remained for at least 1 h after the removal of atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

Clinical usefulness of dual-label Schilling test for pancreatic exocrine function.

The usefulness of the pancreatic dual-label Schilling test as an indirect test of pancreatic exocrine function was evaluated. This dual-label Schilling test was based on the difference of absorption for [58Co]cobalamin bound to hog R protein and [57Co]cobalamin bound to intrinsic factor. In this study, the test was performed in 7 normal subjects, 5 patients with pancreatectomy, 12 patients with chronic pancreatitis, 10 patients with suspicion of chronic pancreatitis, and 13 patients without chronic pancreatitis. The normal lower limit (mean -2 SD) of excretion ratio for [58Co]/[57Co] in 24-h urine was 0.68. Of the 26 patients on whom endoscopic retrograde pancreatography was performed, none of the 9 patients with normal pancreatogram, 4 of the 9 patients with mild to moderate pancreatitic changes in pancreatogram, and 7 of the 8 patients with advanced pancreatitic changes in pancreatogram showed a positive value lower than the ratio of 0.68 in this test. In 28 patients examined with the direct test of pancreatic secretory capacity, 2 of the 13 patients with normal function, 6 of the 9 patients with mild dysfunction, and 5 of the 6 patients with definite dysfunction were positive in this test. The results of the pancreatic dual-label Schilling test significantly correlated with those of a direct test of pancreatic secretory capacity and the findings of pancreatitic changes in pancreatogram (p less than 0.01, chi 2 test). The ratio for [58Co]/[57Co] correlated (r = 0.73) with the maximal bicarbonate concentration in duodenal juice of the direct test of pancreatic secretory capacity. The impairment of bicarbonate output by the pancreas may adversely affect the transfer of cobalamin from R protein to intrinsic factor. It suggested that the pancreatic dual-label Schilling test is useful for detecting not only patients with severe pancreatic insufficiency but also the relatively early stage of chronic pancreatitis with bicarbonate secretory dysfunction of the pancreas.

4-Aminobenzoic Acid↗

High voltage electric pulses efficiently induce fusion of cells in monolayer culture.

High voltage electric pulses, 1000 V/cm, were found to induce cell fusion efficiently when delivered to cells growing in a monolayer culture. The maximum yield of fused cells was about 30% of cells remaining after treatment. Colonies of interspecies hybrid cells between mouse and others also appeared with a frequency of 3 X 10(-4) - 2 X 10(-5) after culturing fused cells in a selection medium that permits the growth of only hybrid cells. This method of electrofusion was applied for complementation analysis of DNA repair-deficient xeroderma pigmentosum cells. Efficient cell fusion was also observed with these human diploid fibroblasts and the resulting heterodikaryons showed a recovery of ultraviolet light-induced unscheduled DNA synthesis to the same extent as in normal cells.

Animals↗