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Biomedical subjects

Y Tsukamoto

Publications and source records attributed to Y Tsukamoto.

At least 19 recordsLinked to original sources
PubMed1992

Age-associated decreases in prostaglandin contents in human gastric mucosa.

This study was designed to clarify effects of ageing on human gastric mucosal prostaglandin (PG) contents. Forty examinees were divided into 5 age groups of 8 persons each, as follows: age under 40, age 40-49, age 50-59, age 60-69, and age over 70. PG contents in human gastric mucosa were measured by microcolumn high performance liquid chromatography (HPLC) with helium/cadmium laser induced fluorescence detection using biopsy samples obtained by endoscopy. The contents of 6-keto-PGF1 alpha, PGF2 alpha, PGE2, and PGD2 in the under 40 group were 638 +/- 39, 97 +/- 16, 468 +/- 68, 497 +/- 86 (pg/mg tissue), respectively. No significant differences in PG contents among groups aged under 70 were observed. In contrast, significantly low PG contents in the over 70 group were observed, i.e., the contents of 6-keto-PGF1 alpha, PGF2 alpha, PGE2, and PGD2 were 311 +/- 58, 36 +/- 8, 196 +/- 48, 171 +/- 40, respectively, and their contents were significantly lower than those in other age groups. In conclusion, gastric mucosal PG contents decrease significantly in over 70 years-old and this might be a contributing factor in the pathogenesis of gastric ulcers in elderly people.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Parathyroid hormone stimulates ATP-dependent calcium pump activity by a different mode in proximal and distal tubules of the rat.

A new technique was developed to isolate basolateral membrane vesicles individually from proximal and distal tubules of the rat cortex. This new technique enabled us to study differences in their kinetics and mechanisms of hormonal regulation of Ca pump between proximal and distal tubules. The Ca pump in distal tubule has very high affinity (42.6 nM Ca2+) and the one in proximal tubule has relatively low affinity (75.6 nM Ca2+). Parathyroidectomy (PTX) decreased the Vmax of Ca pump activity in proximal tubule (4.68 +/- 0.99 vs. 9.08 +/- 2.21 nmol 45Ca2+/min per mg protein BLMV, P less than 0.05), while it increased Km in distal tubule (93.1 +/- 11.0 vs. 35.1 +/- 16.1 nM Ca2+, P less than 0.05). Restoration of serum Ca2+ concentration by 1,25(OH)2D3 supplement could not reverse these changes by PTX in Ca pump activity in either the proximal or the distal tubule. In conclusion, this study strongly suggested that parathyroid hormone stimulated Ca pump activity by increasing the Vmax in proximal tubule and by increasing the affinity in distal tubule. 1,25(OH)2D3 does not have a direct effect on the basolateral membrane Ca pump activity.

Adenosine Triphosphate↗
PubMed1992

Influence of low dissolved oxygen concentration in body fluid on corrosion fatigue behaviors of implant metals.

In their previous study, the authors carried out a fatigue test for AISI 316, 316L stainless steels and COP1 alloy in a living animal body and observed a remarkable deterioration in the fatigue durability of these metals. In that study, it was concluded that the reason the corrosion resistance of the metals was reduced in the living body was that the low concentration of dissolved oxygen gas in the body fluid (the partial pressure pO2; 28-78 mmHg) was insufficient to form the chromium oxide passivation film on the metal surface, and the base metal (iron) was released into the environmental fluid in ionic form. In this paper, with the concentration of dissolved oxygen gas in a physiological normal saline solution being set equivalent to that of living body fluid, fatigue tests on AISI 316 were made to simulate the stress corrosion behavior of the metal in the living body. As a result, remarkable deterioration of fatigue strength was observed in the low O2 concentrated normal saline solution, which was the same as that in the living animal body.

Animals↗
PubMed1992

Mineralized nodule formation by cultures of human dental pulp-derived fibroblasts.

Pulp fibroblasts were isolated from human deciduous and supernumerary teeth and cultured in vitro. With continued culture in normal tissue-culture medium, six pulp fibroblast strains formed cell nodules after 10-15 days. By electron microscopy the nodules had matrix vesicles, and needle-shaped crystals associated with a dense network of collagen fibrils. The crystalline material exhibited a pattern consistent with hydroxyapatite when nodules were examined by X-ray diffractometry. Furthermore, the cells showed high levels of alkaline phosphatase activity, which could be increased more than seven-fold by the addition of 1,25(OH)2D3 (5 x 10(-9)-5 x 10(-8) M). In addition to the production of type I collagen, these cells also synthesized fibronectin and osteonectin. The formation of mineralized tissue nodules by pulp cells in vitro provides a useful system for study of the pathological calcification of pulp tissues.

Alkaline Phosphatase↗
PubMed1992

Gap junctions between the pedicles of macaque foveal cones.

Cone terminals ("pedicles") in the fovea of macaque retina were studied in electron micrographs of serial sections. Pedicles were sheathed in glia except for small (0.2 microns 2) fenestrations, 4.8 +/- 1.7 per pedicle. At each fenestration the membranes of adjacent pedicles were contiguous and marked by an adherent junction, which in turn was invariably associated with gap junctions. There were 3.2 +/- 1.4 gap junctions per adherent junction and thus, about fifteen gap junctions per pedicle. The gap junctions were small, 1.6 x 10(-3) +/- 1.8 x 10(-3) microns 2 (mean +/- SD) and were formed indiscriminately with all neighboring pedicles. An upper bound was estimated of 170 connexons per pedicle and thus a coupling conductance of 1.7 x 10(4) pS. Available psychophysical data suggest that the junctions are uncoupled at high luminance. They may couple at lower luminance where spatial averaging would improve contrast sensitivity without cost to spatial acuity.

Animals↗
PubMed1992

Motion of the bipolar hip prosthesis components. Friction studied in cadavers.

It has been postulated that most hip motion occurs at the inner bearing in bipolar hip prosthesis. However, radiography and cineradiography analyses have shown that the inner bearing is not always the primary articulation. We studied the frictional behavior of bipolar prosthesis and Austin-Moore prostheses and the motion of the bipolar prosthesis using a pendulum apparatus. The primary articulation was altered according to the amount of loading. When a load of 10 kg was applied to the joint, motion occurred at both bearings with friction coefficients 0.061 at the inner bearing and 0.026 at the outer bearing. With loads of over 20 kg, the outer bearing was the primary articulation. The inner bearing was the dominant articulation only when the acetabular cartilage had been removed. Our results suggest that the motion of bipolar prostheses occurs mainly at the outer bearing during normal walking, and that this prosthesis cannot be expected to reduce wear of articular cartilage.

Biomechanical Phenomena↗
PubMed1992

Mechanism and prevention of chronic colonic inflammation with trinitrobenzene sulfonic acid in rats.

1. The role of prostanoids in experimental colitis with trinitrobenzene sulfonic acid (TNBS) in rats was investigated. The effects of cyclosporine A (CsA) on the development of experimental colitis were also examined. 2. Five kinds of prostanoids were detected in rat colonic tissue by high performance liquid chromatography. These were 6-keto-prostaglandin (PG) F1 alpha, PGF2 alpha, PGE2, PGD2 and thromboxane B2. 3. In TNBS-induced experimental colitis, all prostanoid concentrations except PGD2 increased, although the time courses differed from each other. 4. Medication with indomethacin markedly reduced prostanoid concentrations in TNBS-induced colitis. However, indomethacin did not show any effect on damage scores. 5. Cyclosporine A reduced damage scores 14 days after TNBS treatment, and the protective effects were observed, whereas CsA did not affect colonic tissue prostanoid concentrations. 6. Prostanoids might be produced secondarily in the genesis of TNBS-induced colitis, although they may attenuate the inflammatory response. It was also suggested that CsA was likely to have therapeutic effects on experimental colitis by inhibiting the immune reaction with TNBS, which induced the chronic inflammation.

Animals↗
PubMed1992

Reconstitution and partial purification of calcium transport activity from rat kidney cortex.

An ATP-dependent Ca2+ uptake system from rat renal cortical basolateral membranes was solubilized with Triton X-100 and reconstituted into liposomes with lecithin. In the presence of Mg2+, Ca2+ uptake in the reconstituted vesicles was time and ATP dependent and was inhibited by vanadate. Ca2+ uptake in basolateral membrane vesicles depleted of endogenous calmodulin was enhanced by exogenous calmodulin and depressed by R-24571. This sensitivity to calmodulin and R-24571 was lost upon reconstitution in the presence and absence of leupeptin. Vesicles containing Ca2+ uptake activity were separated by gradient centrifugation after Ca2+ was taken up and accumulated as calcium phosphate in the vesicles. This resulted in Ca2+ uptake activity that was enriched 25 times. However, Ca(2+)-dependent adenosinetriphosphatase (ATPase) activity was not enriched significantly. This Ca(2+)-ATPase had two kinetic forms for Ca2+: one was a high-affinity low-capacity form; the other had a low affinity and high capacity. The Ca(2+)-ATPase activity also had two kinetic forms for ATP. All kinetic forms were inhibited by Mg2+. Vanadate, calmodulin, and R-24571 had no effects on Ca(2+)-ATPase activity. A protein doublet of Ca(2+)-dependent hydroxylamine-sensitive phosphorylated intermediates was demonstrated at 125 and 136 kDa in the purified vesicles. This doublet was not altered by addition of leupeptin throughout the purification.

Adenosine Triphosphate↗
PubMed1992

Effects of histamine H2-receptor antagonists and a proton pump inhibitor on the mucosal hydroxyproline content of ethanol-HCl-induced gastric lesions in rats.

We evaluated the effects of different antisecretory agents (H2-receptor antagonists and a proton pump inhibitor) on collagen regeneration in rat gastric lesions induced by intragastric administration of 50% ethanol +0.15 N HCl (EtOH-HCl). The lesion indices showed the highest value 30 min after administration of EtOH-HCl and a significantly decreased value 15 h later. The mucosal hydroxyproline concentration was significantly increased 30 min after EtOH-HCl administration, reached a maximum 6 h later and subsequently decreased as time passed. Intraperitoneal administration of cimetidine at a dose of 100 mg/kg or famotidine at a dose of 5 mg/kg 30 min after EtOH-HCl administration could not reduce the lesion indices in less than 24 h and suppressed the increase in mucosal hydroxyproline concentrations significantly compared with the control group. On the other hand, treatment with 10 mg/kg of E-3810, a proton pump inhibitor, had no effects on the lesion healing nor on the fluctuation of mucosal hydroxyproline concentrations. These facts suggest that H2-receptor antagonists might delay the healing of EtOH-HCl-induced gastric lesions through the suppression of collagen regeneration under the condition of exclusion of gastric acid secretion.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1992

Effect of duodenal mucosal blood flow on duodenal alkaline secretion in rats.

To investigate the role of duodenal mucosal blood flow (DMBF) in the regulation of duodenal alkaline secretion (DAS), both parameters were measured before and after the administration of various drugs in rats. The DMBF was determined using an electrolytically generated hydrogen gas clearance technique, and the DAS was measured by the perfusion method. The administration of dulcerozine, a potent duodenal ulcerogenic agent, at a dose of 250 mg/kg and serotonin at a dose of 20 mg/kg, which produces duodenal ulcerations with an acid load, decreased both DMBF and DAS. On the other hand, the administration of secretin at a dose of 10 U/kg increased both parameters. There were parallel changes in DMBF and DAS. It is concluded, therefore, that DAS may be regulated by DMBF and that both parameters may be involved in the defense mechanism of duodenal mucosa.

Alkalies↗
PubMed1992

Heterotopic intestinal membrane in a retroperitoneal tumor.

Plain abdominal X-rays of a 13-year-old girl with chief complaints of back pain revealed calcification in the upper left abdomen. A calcified tumor was confirmed at the dorsal side of the pancreatic tail upon admission. A completely formed colic membrane free of all other germ layers was discovered within the tumor, leading to a diagnosis of heterotopic colonic membrane. To our knowledge, there have been no other cases of heterotopic intestinal tissue of this type, so we consider this an extremely rare case worth reporting.

Adolescent↗
PubMed1992

Rotation osteotomy for dislocation of the radial head. 6 cases followed for 7 (3-10) years.

We performed rotation osteotomy of the radius in 5 patients with congenital and 1 with post-traumatic anterior dislocation of the radial head. At a mean of 7 (3-10) years follow-up, the chief complaints had disappeared and an anatomical radiographic reduction had been obtained in all the cases. Except for 1 case with limited supination of the forearm, no postoperative complication was noted.

Adolescent↗
PubMed1992

New technique using intraductal ultrasonography for the diagnosis of diseases of the pancreatobiliary system.

Intraductal ultrasonography (IDUS), a new technique for visualizing arterial structures, operates at an ultrasound frequency of 30 MHz to produce high resolution, cross-sectional images in real time. The purpose of this study was to provide a basis for interpreting IDUS images in vitro. We also attempted to determine the clinical usefulness of the IDUS system in diagnosing pancreatobiliary diseases in vivo. IDUS echograms of both the bile duct (BD) and main pancreatic duct (MPD) from autopsy specimens of 15 patients demonstrated three distinct layers with a fine reticular pattern in the pancreas in vitro. In clinical cases, the MPD and BD of four patients could be scanned by inserting the IDUS catheter via the major papilla without requiring endoscopic sphincterotomy. We hope that IDUS will become routine in scanning the BD and MPD to achieve early and accurate diagnoses of pancreatobiliary diseases.

Adenoma, Bile Duct↗
PubMed1992

Reduction of adverse effects of indomethacin by anti-allergic drugs in rat stomachs.

This study was designed to elucidate the role of leukotrienes (LT) in indomethacin-induced gastric ulcers in relation to effects of clinically available anti-allergic drugs, azelastine (Azeptin, CAS 58581-89-8) and oxatomide (CAS 60607-34-3). Azelastine (2 mg/kg) or oxatomide (30 mg/kg) was administered intragastrically once 15 min before intragastrical administration of 12 mg/kg of indomethacin. Mucosal prostaglandins (PGs) and LTs were measured by high-performance liquid chromatography (HPLC). In the control rats, 4 kinds of PGs, i.e., 6-keto-PGF1 alpha, PGF2 alpha, PGE2 and PGD2, were detected in gastric mucosa, but no LT was detected. Administration of indomethacin caused severe gastric ulcers (lesion scores; 31.2 +/- 11.1 mm), and all prostaglandins were diminished completely. In contrast, LTC4 and LTD4 (peptide-LTs) were detected and the sum of their levels was 18.5 +/- 7.1 ng/g tissue. Irrespective of indomethacin administration, lesion scores were remarkably reduced in rats treated with azelastine or oxatomide (17.0 +/- 8.1 and 16.0 +/- 8.0, respectively). Azelastine and oxatomide treatment did not improve mucosal PG levels, however, both drugs reduced significantly increases in peptide-LT level, 9.3 +/- 4.6 and 8.6 +/- 4.4, respectively. These results suggest that increases in mucosal LT levels are also involved in the formation of indomethacin-induced gastric ulcers. Combined therapy using anti-allergic drugs and non-steroidal anti-inflammatory drugs might be recommended.

Animals↗
PubMed1992

[Relapse of peptic ulcer after quick healing induced by proton pump inhibitors].

Peptic ulcers treated with a proton pump inhibitor heal more quickly than those treated with a histamine H2 receptor antagonist. Although satisfactory healing without relapse is desirable in the medical treatment of peptic ulcers, the relapse rate after treatment with proton pump inhibitors has not been sufficiently studied. Up to now, several reports have suggested that peptic ulcers treated with omeprazole recur less frequently than those treated with H2 antagonists. Our experimental studies on angiogenesis in granulation tissue of acetic acid-induced gastric ulcers, gastric mucosal collagen synthesis etc., show that H2 antagonists have an inhibitory effect on wound healing, but that proton pump inhibitors do not. It is suggested, therefore, that proton pump inhibitors may at least have no undesirable effect on the natural history of peptic ulcer.

Adenosine Triphosphatases↗
PubMed1992

[Imaging diagnosis of the insulinoma--the clinical usefulness of intraductal ultrasonography of the pancreas and color Doppler sonography].

5 cases of small-sized insulinoma of the pancreas were studied to evaluate the ability of diagnostic imaging techniques to determine tumor location. Techniques used were extracorporeal ultrasonography, endoscopic ultrasonography (EUS), angiography, percutaneous transhepatic portal catheterization and CT. EUS was superior to the other modalities in diagnosing the location of insulinomas. We employed Color Doppler (CD) ultrasonography in one case and obtained color expression in the tumor and a pulsatile wave in the FFT analysis. Intraductal sonography of the pancreas (IDSP) was also performed in this case resulting peripheral echo-lucent, central echogenic mass. From these results, we expect that CD and IDSP will be useful in clinical application for diagnosing various tumors.

Adult↗
PubMed1992

Prevalence of gallbladder polyps among apparently healthy Japanese: ultrasonographic study.

The prevalence of gallbladder polyps was investigated in apparently healthy Japanese who underwent abdominal ultrasonography as part of their health screening examination. The polyps found were differentiated from gallstones, adenomas, or carcinomas as much as possible, and were considered to be cholesterol polyps. The prevalence of such gallbladder polyps was higher among males in every decade of age evaluated. The subjects with gallbladder polyps were more obese than the control group without gallbladder polyps, on abdominal ultrasonograms. The prevalence of gallbladder polyps rose in accordance with a rise in obesity index. At each range of obesity index, the prevalence of gallbladder polyps was higher among males. The prevalence of gallbladder polyps was highest among the middle-aged (40- and 50-yr-old) males, similar to the curve of the obesity index. In females, the obesity index increased with age, with no accompanying rise in the prevalence of gallbladder polyps. These data suggest that obesity contributes to the formation of cholesterol polyps of the gallbladder.

Adolescent↗