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Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 523 records · Page 29Linked to original sources
PubMed1996

Selective extraction of beta-blockers from biological fluids by column-switching high-performance liquid chromatography using an internal-surface phenylboronic acid precolumn.

A column-switching HPLC method using an internal-surface phenylboronic acid precolumn for the selective extraction of beta-blockers from biological fluids has been developed. Filtered urine and plasma samples (50 microliters) were injected onto the precolumn equilibrated with methanol-0.05 M disodium hydrogenphosphate (5:95, v/v). After the precolumn had been washed briefly, the selectively retained beta-blockers were eluted with methanol-0.05 M phosphate buffer (pH 2.0) and transferred to a reversed-phase analytical column, on which they were then separated. Even after exposure to at least 160 injections of non-treated urine and plasma samples, the retention efficiency of the precolumn was maintained with no increase in back pressure. Quantitative recoveries and good reproducibility were demonstrated with pindolol.

Adrenergic beta-Antagonists↗
PubMed1996

Expression of MUC apomucins in normal pancreas and pancreatic tumours.

The epithelial expression of apomucins MUC1, MUC2, MUC3, and MUC5/6 was examined in normal pancreas and in pancreatic lesions, using immunohistochemical methods. In normal pancreas (n = 5), MUC1 apomucin was expressed in ducts and some acini, but there was no expression of MUC2, MUC3, or MUC5/6. In chronic pancreatitis (n = 5), MUC1 apomucin was expressed, but expression of the other apomucins was not noted. However, mucous hyperplastic foci of pancreatic ducts expressed MUC5/6 apomucin in 2/5 cases (40 percent). In intraductal papillary-mucinous neoplasm (IPMN) of the pancreas (n = 9), MUC1, MUC2, MUC3, and MUC5/6 apomucins were expressed in 8/9 (89 percent), 0/9 (0 per cent), 4/9 (44 per cent), and 9/9 (100 per cent) case, respectively. In pancreatic mucinous cystadenoma (n = 8), MUC1, MUC2, MUC3, and MUC5/6 apomucins were expressed in 7/8 (88 percent), 0/8 (0 percent), (25 percent), and 3/8 (38 percent) cases, respectively. In invasive ductal adenocarcinoma of the pancreas (n = 25), expression of MUC1, MUC2, MUC3, and MUC5/6 apomucins was found in 25/25 (100 percent), 1/25 (4 percent), 20/25 (80 percent), and 24/25 (96 percent) cases, respectively. Atypical mucous duct hyperplasia near cancer cells consistently expressed MUC1 apomucin and occasionally expressed MUC3 and MUC5/6. In positive cases, MUC1 apomucin expression was noted in the cell membrane facing the ductal or neoplastic lumina, while expression of MUC2, MUC3, and MUC5/6 apomucins was found in the cytoplasm. These results suggest that MUC3 and MUC5/6 apomucins newly emerge during the neoplastic transformation of pancreatic mucinous cystadenoma and IPMN and during pancreatic ductal carcinogenesis, while MUC1 apomucin remains positive and MUC2 apomucin remains almost negative during neoplastic transformation.

Aged↗
PubMed1996

Experimental study on nerve regeneration through the basement membrane tubes of the nerve, muscle, and artery.

We evaluated neurotization after transplantation with lyophilized nerves, muscles, and arteries, and examined the possibility of practical application of long bridging grafts. Grafts of 10 mm and 25 mm of lyophilized nerves, muscles, and arteries harvested from Fisher rats were transplanted to the sciatic nerves of recipient Lewis rats. The histological changes undergone by short grafts were observed at weekly intervals. The sham-operated and isograft groups were used to compare the results of long grafts. In both the nerve and muscle-graft group, regenerated axons grew out through the residual basement membrane tube. But in the muscle graft group, phagocytosis of myofibril debris took longer than that of degenerated axons. No statistical differences were found between results of TSI, induced EMG, and quantitative analysis of myelinated axons in the nerve and muscle graft groups. No neurotization was noted in the long artery graft. In long grafts, laminin found on the basement membrane may not be sufficient to accelerate neurotization, and arteries should not be used for tubulization.

Animals↗
PubMed1996

Development of Neutral and Nearly Neutral Theories

A short history of the major features of neutral theories of molecular evolution is presented. Emphasis is placed on the nearly neutral theory, as this version of the neutral theory has explained the widest range of phenomena. The shift of interest from protein to DNA evolution is chronicled, leading to the modern view that silent and replacement substitutions are responding to different evolutionary forces. However, the exact nature and magnitude of these forces remains controversial, as all current theoretical models suffer either from assumptions that are not quite realistic or from an inability to account readily for all phenomena. Although the gathering of sequence data has been the main effort of contemporary population genetics, further exploration of theoretical models of molecular evolution would provide a more coherent framework for data analysis.

Journal Article↗
PubMed1996

Internal stenting of the hepaticojejunostomy and pancreaticojejunostomy in patients undergoing pancreatoduodenectomy to promote earlier discharge from hospital.

Internal stenting of the hepaticojejunostomy and pancreaticojejunostomy was performed in 11 consecutive patients undergoing pancreatoduodenectomy between July 1992, and July 1994, to promote earlier discharge from hospital. Although minor leakage of the pancreaticojejunostomy occurred in 4 patients, this resolved within a short period and all 11 patients were able to be discharged by the 29th postoperative day in good health and without any intubation. Follow-up abdominal X-ray and computed tomography (CT) scans proved that all 22 of the stenting tubes had spontaneously fallen out by the 176th postoperative day. No complication related to the stenting tubes occurred in any of our patients.

Adult↗
PubMed1996

Fluorine-18 fluoro-2-deoxyglucose positron emission tomography in recurrent rectal cancer: relation to tumour size and cellularity.

The aim of this study was to assess the value of fluorine-18 fluoro-2-deoxyglucose (FDG) positron emission tomography in patients with recurrent rectal cancer, in relation to tumour size and cellularity. Thirty-seven patients (21 mean and 16 women; mean age, 55.4+/-9.58 years) with suspected recurrence of rectal cancer were studied. FDG uptake was quantified by the differential absorption ratio (DAR). In 29 patients magnetic resonance imaging was also performed. To evaluate the signal intensity of the lesion, the lesion to muscle signal intensity ratios (SIR) were calculated on T2-weighted images. In seven patients who received surgical treatment the DAR and SIR were compared with the tumour cellularity. All 32 patients with confirmed recurrence showed increased FDG accumulation in the mass (DAR=4.57+/-1.89) in comparison with low FDG accumulation in five patients with scar (DAR=1.17+/-0.43). There was a significant correlation (r=0.661, P<0.001) between the DAR and the tumour diameter. There was no correlation between the DAR and SIR, whereas there was a significant correlation (r=0.565, P<0.01) between the DAR corrected using count recovery coefficient (DAR*) and SIR. In the histopathological findings there was a tendency for the DAR* and SIR to correlate with tumour cellularity. It is concluded that the DAR of recurrent rectal cancer should be evaluated taking into consideration the tumour size and cellularity.

Deoxyglucose↗
PubMed1996

Physical map of a YAC contig containing the region of the human gene (HYRC) complementing hyper-radiosensitivity of the scid mouse mutation.

We previously mapped the putative human HYRC (the hyper-radiosensitivity of the scid mutation, complementing gene) to human chromosome 8q11.1 by fluorescence in situ hybridization (FISH) using Alu-based PCR products from a mouse-human scid radiation cell hybrid (RD15/5) as probes. From a cosmid library constructed from RD15/5, 57 cosmid clones containing human DNA inserts were isolated. 18 of which were mapped to 8q11. Based on the sequences of plasmid subclones of the 18 cosmids, five novel sequence-tagged-sites (STSs) were made. By a screening of the CEPH-YAC library with these STSs, five yeast artificial chromosome (YAC) clones were isolated. All these YAC clones were confirmed not to be chimeric by FISH, but two of them showed deleted human insert DNAs. Using the other 3 non-deleted YACs, we constructed a physical map covering the HYRC region. We confirmed that the recently isolated gene (the DNA-PKcs gene) which is a strong candidate for HYRC is located within the present contig and spans less than 200 kb. This map will be useful for the analysis of the genomic structure of the DNA-PKcs gene and for isolation of other complementing genes in the HYRC region.

Animals↗
PubMed1996

Surfactant therapy for respiratory failure due to near-drowning.

We report a nearly drowned 3-year-old boy who was treated successfully with exogenous bovine surfactant. Exogenous surfactant should be administered to patients with refractory respiratory failure based on the pulmonary pathophysiology in near-drowning.

Biological Products↗
PubMed1996

Modulation of calcium current by ATP in guinea-pig adrenal chromaffin cells.

The effects of extracellular adenosine 5'-triphosphate (ATP) on voltage-dependent Ca2+ currents were examined using the whole-cell voltage-clamp technique in guinea-pig isolated adrenal chromaffin cells. ATP (500 microM) reversibly suppressed Ca2+ currents in the presence of 5mM Ca2+ in the extracellular solution. The inhibitory effect of ATP on Ca2+ currents tended to increase with increases in the peak amplitude of ATP-evoked current when the intracellular solution contained 0.1 or 1 mM ethylenebis(oxonitrilo)tetraacetate(EGTA). Using the intracellular solution containing 10mM EGTA, on the other hand, the inhibitory effect did not change regardless of the amplitude of current responses to ATP. In the presence of 10 mM Ba2+, ATP (100 microM) reduced Ba2+ currents in a manner similar to Ca2+ currents. This reduction was decreased by dialysis of cells with the internal solution containing guanosine 5'-O-(2-thiodiphosphate) (GDP [beta-S]; 1 mM) or guanosine 5'-O-(3-thiotriphosphate) (GTP [gamma-S]; 100 microM). A depolarizing prepulse to + 100 mV partly relieved ATP-induced reduction of Ba2+ currents. ADP, AMP and adenosine also reduced Ba2+ currents and the effect of adenosine was the most potent. Adenosine (0.5 and 1 mM) significantly inhibited adrenaline secretion induced by nicotine (50 microM). These results suggest that Ca2+ entry through ATP-activated non-selective cation channels results in the inactivation of voltage-dependent Ca2+ channels. In addition, ATP seems to modulate Ca2+ channels via the pathway related to G-protein. Adenine nucleotides and adenosine may play a role in controlling secretory activity in guinea-pig adrenal chromaffin cells.

Adenosine↗
PubMed1996

In vivo microautoradiography of [3H]1,24(OH)2D3 (tacalcitol) following topical application to normal rats and in vitro metabolism in human keratinocytes.

This study was conducted to investigate the mechanism of topical absorption of [3H]1,24(OH)2D3 (1,24-dihydroxyvitamin D3; tacalcitol) by applying an ointment containing 4 micrograms2/g [3H]1,24(OH)2D3 to the skin of rats using an occlusion method. Microautoradiography of the skin at the application site 1 h after topical treatment showed a high concentration of radiolabel in the stratum corneum, the epidermis and around the hair follicles. Radiolabel was also seen in the epidermis and hair follicle areas 8 h and 24 h after application. The radiolabel was distributed to a minor extent to the subcutaneous fat layer. Microautoradiography showed two routes of purcutaneous absorption of 1,24(OH)2D3: through the stratum corneum and epidermis into the microvessels, and through hair follicle areas into the bloodstream. After topical application of an ointment containing 4 micrograms/g or 40 micrograms/g [3H]1,24(OH)2D3 to the shaved neck skin of rats, the absorption rate, estimated by excretion in the urine and faeces, was about 30% of the total applied radioactivity. The main excretion route after topical application was in the faeces. Furthermore, 1,24(OH)2D3 added to human adult keratinocytes was not metabolized into other compounds, and only the unchanged compound was detected. These findings strongly suggest that 1,24(OH)2D3 distributed into the epidermis acts on epidermal keratinocytes. Topical application of 1,24(OH)2D3 appears to be a possible approach to the treatment of psoriasis and other skin diseases through its action on the 1,25(OH)2D3 receptor, which reportedly plays a very important role in the regulation of proliferation and differentiation of keratinocytes.

Absorption↗
PubMed1996

Tacalcitol (1,24(OH)2D3, TV-02) inhibits phorbol ester-induced epidermal proliferation and cutaneous inflammation, and induces epidermal differentiation in mice.

In this study, we examined the cutaneous effects of tacalcitol [1,24(R)(OH)2D3] on epidermal proliferation, differentiation, and skin inflammation in vivo using hairless mice. Tacalcitol was shown to inhibit epidermal proliferation using TPA-induced ornithine decarboxylase activity and DNA synthesis as indices, and the induction of epidermal differentiation using type I transglutaminase activity as an index. Tacalcitol also displayed an antiinflammatory effect on TPA-induced inflammatory changes histopathologically. These results confirm the clinical efficacy of tacalcitol in psoriasis, and suggest that it may be efficacious in the treatment of other inflammatory skin diseases.

Administration, Topical↗
PubMed1996

Local bone turnover in the metaphysis of the proximal tibia and the lumbar vertebra during the early periods after ovariectomy in rats.

To clarify the local changes in bone formation and resorption during the early period after ovariectomy (OVX), 200 SD rats, 4 months of age, underwent OVX or sham surgeries and seven to nine rats from each group were terminated at 1, 3, 7, 11, 15, 19, 23, 28, 35, 63, and 91 days postsurgery after tetracycline labeling. Serum intact osteocalcin levels were measured. Undecalcified sections of the 5th lumbar body (L5) and the right proximal tibia were measured for trabecular bone area, the labeled perimeters and the interlabeling distances after Villanueva's staining. On the 4th lumbar body (L4) and the left proximal tibia, undecalcified sections were measured for the trabecular osteoclast by tartrate-resistant acid phosphatase staining. The uterine horns were atrophied on the 3rd postovariectomy day (day 3). Serum osteocalcin levels increased on day 7 and reached the highest value on day 23. In either L5 or the metaphysis of the proximal tibia, trabecular bone volume (BV/TV) significantly decreased on day 15. The trabecular bone loss on day 28 was approximately 50% in the tibia and 15% in the L5. In either the lumbar or the tibia, osteoclast numbers significantly increased at day 3, and peaked between days 15 and 23. In the tibia, however, the bone formation rates (BFR/BS) were significantly reduced on the 3rd and 7th post-surgical days compared with the start value for both the OVX and sham groups. The BFR/BS values in L5 did not decrease during the first 7 days in either group. The BFR/BS values were then increased for both L5 and the tibia after day 7. These data clearly demonstrated that the local bone turnover 7 days post-OVX was identical in the proximal tibia and the lumbar vertebra. In the proximal tibia, however, it may be suggested that the increased bone resorption and reduced formation within 7 days after OVX due to the combined effects of both an estrogen deficiency and the surgical intervention would possibly play a critical role in the greater magnitude of the trabecular bone loss.

Animals↗