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Biomedical subjects

T Ichikawa

Publications and source records attributed to T Ichikawa.

At least 307 records · Page 17Linked to original sources
PubMed1995

Gastric mucosal damage accompanying changes in mucin induced by histamine in rats.

The present study was carried out to clarify the mechanism of histamine-induced gastric mucosal damage in rats. Following an injection of histamine (80 mg/kg), pH dropped within 30 min. and then recovered control value (pH = 4-5) 4 hr later. The decrease in mucosal mucin content and the appearance of haemorrhagic erosions followed the drop in pH. The recovery of mucosal mucin content preceded the healing of haemorrhagic erosions and pH recovery to the control level. Histamine also caused qualitative changes in corpus mucins. These qualitative changes induced by histamine were eliminated at 7 hr following the administration of histamine. It appears from the present results that increase in HCl and decrease in mucins induced by histamine bring about gastric damage.

Animals↗
PubMed1995

Inhibitory effect of phosphorylated oligosaccharides prepared from potato starch on the formation of calcium phosphate.

The inhibitory effect of phosphorylated oligosaccharides, which were prepared from potato starch, on the formation of calcium phosphate in vitro were investigated. Phosphorylated oligosaccharides from potato were fractionated by ion-exchange chromatography into two fractions, PO-1 and PO-2. Fraction PO-1 was composed of maltotriose, maltotetraose, and maltopentaose to which one phosphate group was attached. Fraction PO-2 was predominantly composed of maltopentaose and maltohexaose to which at least two phosphate groups were attached. The average degree of polymerization of dephosphorylated PO-1 and PO-2 was evaluated to be 4.02 and 5.82, respectively. Fraction PO-2 was the main component having an inhibitory effect on calcium phosphate formation. In addition, among the phosphorylated monosaccharides, glucose-1,6-diphosphate and fructose-1,6-diphosphate were more effective inhibitors of the formation of calcium phosphate than glucose-6-phosphate and fructose-6-phosphate. These results suggest that the strength of the inhibitory effect might depend on the number of phosphate groups attached to each sugar molecule.

Calcium↗
PubMed1995

[A study on intratesticular aromatase activity in male infertility].

We report here the influence of intratesticular aromatase activity and intratesticular estrogen concentration on spermatogenesis. In the present study, we measured the levels of aromatase activity and the concentrations of intratesticular testosterone (T) and estradiol (E2) in 21 testicular tissues from biopsy of 20 idiopathic male infertility patients, 5 testicular tissues from castration of 4 prostatic cancer patients and a testicular tissue from an autopsy. Serum T, Free T, E2, LH and FSH were also measured if possible. Aromatase activity in the testis were assayed by measuring the amount of 3H2O formed during the conversion of [1 beta-3H] androstenedione to estrogen. Histological evaluation of the testes were performed using the Johnsen's score count (JSC) method. The rate of aromatase activity was linear in regard to time and amount of tissue. The production of 3H2O was inhibited by 4-hydroxyandrostenedione. The apparent Km (Michaelis constant) of the reaction was 23.2 nM. The rate of aromatase activity increased linearly as JSC level decreased (r = 0.67). Also, it significantly correlated with intratesticular T (r = 0.69), E2 (r = 0.88) and T/E2 ratio (r = -0.85), whereas it was not correlated with serum T, free T, E2, T/E2 ratio and free T/E2 ratio. Therefore, our results suggest the possibility that the increase in the rate of aromatase activity and the concentration of E2 may influence spermatogenesis.

Adult↗
PubMed1995

A highly sensitive enzyme immunoassay for G-CSF in human plasma.

We have developed a sensitive sandwich enzyme-linked immunosorbent assay (ELISA) to measure granulocyte colony-stimulating factor (G-CSF) in human plasma. This ELISA employs a combination of a mouse monoclonal antibody (MAb) as the first antibody and an affinity-purified sheep polyclonal antibody conjugated with beta-D-galactosidase as the second antibody. The coefficients of intra- and interassay variations were 2.2 to 3.6% and 8.3 to 10.2%, respectively. The assay had no cross-reactivity with four other human cytokines. Plasma G-CSF levels in healthy volunteers could easily be measured because the detection limit was 0.5 pg/mL. The mean plasma G-CSF concentration in 57 healthy volunteers (aged 19 to 47; 27 males and 30 females) was 10.5 +/- 4.5 pg/mL standard deviation [SD]). There was no statistically significant relationship between plasma G-CSF concentration and absolute neutrophil counts in those healthy volunteers (r = 0.259; p = 0.052).

Adult↗
PubMed1995

Stimulating effect of excess iron feeding on spontaneous lung tumor promotion in mice.

This study was undertaken to estimate if dietary iron could stimulate factors which promote spontaneous lung tumorigenesis in A/J mice, by measuring biochemical parameters of oxidative stress on pulmonary nuclei, ornithine decarboxylase (ODC) and spermidine/spermine N1-acetyltransferase (SAT) activities as markers of tumor promotion. Feeding excessive iron (500%) to A/J mice for 28 weeks significantly elevated pulmonary DNA single strand break (DNA-SSB) as well as nuclear thiobarbituric acid reactive substances (TBARS) in connection with the increase of nuclear nonheme iron level. In contrast, nuclear alpha-tocopherol levels in the iron-loaded group significantly decreased as compared to that in the control group. Pulmonary ODC and SAT activities showed increasing tendency on feeding excess iron for 28 weeks. These results suggest that dietary iron stimulates spontaneous lung tumor promotion in A/J mice, partly due to the enhancement of oxidative damage to the pulmonary nuclei.

Acetyltransferases↗
PubMed1995

[CT analysis of aortic cobwebs in aortic dissection].

Contrast-enhanced CT images in patients with acute or chronic aortic dissection were evaluated for the purpose of determining the clinical usefulness of "aortic cobwebs", which were originally reported by Williams et al. as an anatomical marker of the false lumen. Aortic cobwebs were detected in 13 of 44 cases (30%), demonstrating as low density structures in the false lumen continuing from the intimal flap. The aortic cobwebs were mainly linear in shape, and the size ranged from 5 x 1 to 15 x 3 mm (mean: 9 x 2 mm). Aortic cobwebs were more frequently demonstrated in chronic than in acute cases, and were more often detected in the abdominal aorta. Follow-up CT examinations of the cobwebs revealed no interval change in six cases, disappearance in three cases and thickening in one case. There was no significant correlation between the sequential changes in the cobwebs and dilatation or thrombus formation in the false lumen. Aortic cobwebs seem to represent partially residual bands of the aortic media incompletely sheared from the aortic wall during the initial processes of aortic dissection. These structures are considered to be a reliable anatomic marker and to be useful for CT identification of the false lumen in aortic dissection.

Adult↗
PubMed1995

Active oxygen generated in the process of carcinogen metabolism can induce oxidative damage in nuclei.

In the present study, we examined whether active oxygen formed in the process of 4-nitroquinoline 1-oxide (4NQO) reduction by DT-diaphorase could induce oxidative stress on the pulmonary nuclei. The rapid production of OH- radical-like species after the start of the 4NQO reduction was observed, and subsequent induction of nuclear lipid peroxidation occurred. In conjugation with this event, DNA damage estimated as DNA single strand breaks (DNA-SSB) increased in a time-dependent manner. The induction of this DNA damage was partially inhibited by mannitol or vitamin E treatment. These findings suggest that the active oxygen generated in the process of the 4NQO reduction can induce oxidative damage on the pulmonary nuclei.

4-Nitroquinoline-1-oxide↗
PubMed1995

Development of a new soft gas permeable contact lens with Dk 300.

The effects on the rabbit cornea of a new gas permeable nonhydrophilic soft contact lens made of newly designed polymer with a Dk value of 300 were studied physiologically, histologically, and histochemically during 5 days of daily wear followed by 14 days of extended wear. Corneal swelling was observed to be within 10% of corneal thickness during the wear period. No serious corneal surface changes were observed. Specular microscopy showed no endothelial changes in terms of cell density, coefficient of variation of cell area (CV), or hexagonality before and 2 weeks after lens wear. Histochemical study using periodic acid-Schiff staining and histological study with hematoxylin-eosin revealed no remarkable changes. Scanning electron microscopy revealed slight focal changes; there were no significant changes. The results show that the new soft gas permeable contact lens has no harmful effect on the rabbit cornea.

Animals↗
PubMed1995

[Early diagnosis of pancreatic carcinoma and utility of helical CT].

The pancreatic carcinoma, what is one of difficult carcinomas to treat. It is because the pancreatic carcinoma does infiltrate to external at early stage. However, it leads to increase of operation with significance to check it at early stage. Helical CT is developed in late years, and spread rapidly. This examination includes many clinical utilities. In early diagnosis of pancreatic carcinoma, improve former problems, and is thought that utility is high.

Humans↗
PubMed1995

[MR imaging findings of the femoral marrow in myelodysplastic syndrome].

MR imaging of the femoral marrow was performed in 30 patients with myelodysplastic syndrome (MDS), 11 cases of which evolved to acute myeloid leukemia (AML). The MRI appearance was classified into five patterns: 1) fatty marrow; 2) faint signal; 3) nodular pattern; 4) heterogeneous infiltration; and 5) diffuse infiltration. For each type of MDS, MRI patterns of the femoral marrow were evaluated and compared with those in normal subjects as well as in patients with aplastic anemia. Signal intensity alteration, a low signal on T1-weighted SE image and a high signal on STIR image, began in the proximal femoral marrow almost symmetrically in patients with MDS. The area of abnormal signal intensity tended to gradually extend towards the distal portion of the femur as the disease progressed. MRI patterns of the femoral marrow correlated with marrow cellularity, and diffuse marrow infiltration was noted in patients with a more advanced type of MDS or with severe anemia. There were limitations to making an accurate diagnosis of the MDS type on the basis of the MRI pattern. Progression of the MRI appearance in the course of MDS was thought to be a sign suggesting evolution to AML. It was difficult to differentiate hypoplastic MDS from aplastic anemia, although the nodular pattern was commonly seen in the latter disease.

Adult↗
PubMed1995

[Hepato-biliary excretion of water-soluble iodinated contrast medium shortly after abdominal angiography].

Thirty-nine patients underwent CT examination 15 to 30 min after abdominal angiography with ioxaglate. Gallbladder opacification was observed in 15 patients in the absence of clinical evidence of renal impairment. Among them, 14 patients revealed liver cirrhosis or chronic hepatitis, and one patient showed severe fatty liver on CT. The amount of contrast medium used varied from 70 ml to 310 ml (mean 180 ml). There was no significant relationship between visualization of the gallbladder and the total dose of ioxaglate or presence of liver dysfunction, which indicated that gallbladder opacification was not a rare phenomenon on CT shortly after abdominal angiography with a normal dose of ioxaglate. Gallbladder opacification on CT examination shortly after abdominal angiography shows that the hepatobiliary tract is important in the excretion of ioxaglate.

Abdomen↗
PubMed1995

Pilot-hole preparation for proper implant positioning and the enhancement of bone formation.

We have demonstrated a new insertion technique, "pilot-hole preparation", for proper implant positioning. The purpose of this study was to investigate the histological and biomechanical efficacies of the technique. We analyzed the influence of implant position on the stress distribution to the bone by the two-dimensional finite element method (FEM). In addition, we studied the influence of the pre-operative pilot-hole preparation on the bone tissue in vivo using histological examination.

Adult↗
PubMed1994

Involvement of L-tryptophan aminotransferase in indole-3-acetic acid biosynthesis in Enterobacter cloacae.

L-Tryptophan aminotransferase (L-tryptophan:2-oxoglutarate aminotransferase; EC 2.6.1.27) from Enterobacter cloacae was purified 62-fold and characterized to determine its role in indole-3-acetic acid biosynthesis. The enzyme reversibly catalyzed the transamination of L-tryptophan with 2-oxoglutarate as the amino acceptor to yield indole-3-pyruvic acid and L-glutamate, and the Km values for L-tryptophan and indole-3-pyruvic acid were 3.3 mM and 24 microM, respectively. In the indole-3-acetaldehyde synthesis experiments in vitro, 94% of L-tryptophan was efficiently converted to indole-3-acetaldehyde by the purified L-tryptophan aminotransferase plus indolepyruvate decarboxylase. Furthermore, the amounts of L-tryptophan decreased with increases in the indolepyruvate decarboxylase activity, while the amounts of indole-3-acetaldehyde increased with increases in this activity. In genetic experiments, the amounts of L-tryptophan produced by Enterobacter and Pseudomonas strains harboring the gene for indolepyruvate decarboxylase were lower than those produced by these same strains without the gene, while the amounts of indole-3-acetic acid produced by Enterobacter and Pseudomonas strains harboring the gene for indolepyruvate decarboxylase were higher than those produced by these same strains without the gene. These results clearly show that L-tryptophan aminotransferase is involved in the indole-3-acetic acid biosynthesis and that indolepyruvate decarboxylase is the rate-limiting step in this pathway.

Carboxy-Lyases↗
PubMed1994

Vitamin E acts as a useful chemopreventive agent to reduce spontaneous lung tumorigenesis in mice.

The present study was designed to evaluate whether vitamin E could be a useful chemopreventive agent to reduce spontaneous lung tumorigenesis in mice. Starting at 6 weeks of age, groups were divided into three groups, i.e. A/J mice fed a control diet (A/J control), A/J mice fed a vitamin E-supplemented diet (A/J vitamin E) and ddY mice fed a control diet (ddY control). At the 28th experimental week, nuclear NADPH-driven active oxygen generation, thiobarbituric acid reactive substances (TBARS) and DNA single strand breaks (DNA-SSB) in A/J mice fed a control diet were significantly higher than those in the ddY control group. A/J mice fed Vitamin E for 28 weeks could decrease the levels of TBARS and DNA-SSB with a significant difference, as compared with those in A/J control mice. The nuclear alpha-tocopherol levels in A/J controls were significantly lower than those in ddY controls, on the contrary, the vitamin feeding to A/J mice increased nuclear alpha-tocopherol levels more than that in the ddY controls. At the 40th experimental week, lung tumor incidence and tumor multiplicity (percentage of mice with tumors) in A/J controls were reduced and brought close to those in ddY control mice by vitamin E. Then the alpha-tocopherol level in plasma of A/J controls was significantly lower than the level in plasma of ddY controls, and the level in tumor-bearing mice in A/J controls also showed a lower level with significant difference as compared to that in non-tumor-bearing mice of A/J controls. These results suggest that the difference in susceptibility to spontaneous lung tumorigenesis between A/J and ddY mice partly depends on the difference of oxidative stress on the pulmonary nuclei, and vitamin E can act as a useful chemopreventive agent to reduce spontaneous lung tumorigenesis in mice.

Animals↗
PubMed1994

Differential suppression of mammary and prostate cancer metastasis by human chromosomes 17 and 11.

Metastasis suppressor activities have previously been mapped to human chromosomes 17 and 11. Decreased expression of the metastasis suppressor gene NM23, which is located on chromosome 17, has been correlated with increased metastatic potential in mammary cancers. A region on human chromosome 11, from 11p11.2-p13, has been shown to suppress metastasis in rat prostatic carcinoma cells. In both cases the metastasis suppressor activity had no effect on tumorigenicity or tumor growth rate, demonstrating that the encoded activities are distinct from effects of tumor suppression. To determine whether these human chromosomes encode general or tissue-specific metastasis suppressor activities, a truncated human chromosome 17 (i.e., pter-q23) and a full-length human chromosome 11 were separately transferred into highly metastatic rat mammary and prostate cancer cell lines and tested for their ability to suppress spontaneous metastasis in vivo. These studies demonstrated that when the pter-q23 region of human chromosome 17 is retained by the microcell hybrids, the metastatic ability of both mammary and prostatic cancer cells is suppressed. In contrast, when the pter-q14 region of human chromosome 11 is retained, only the metastatic ability of prostatic cancer cells is suppressed. Additional studies demonstrated that the metastasis suppressor activity encoded by the chromosome 17 pter-q23 region is p53-independent and not due to enhanced expression of NM23 protein.

Animals↗
PubMed1994

[Three-dimensional imaging of portal and hepatic veins using helical CT with intravenous injection of contrast medium].

The authors developed a simple new method for obtaining three-dimensional helical CT images that simultaneously depict both the portal and hepatic veins. One hundred ml of contrast medium was injected intravenously, and helical CT was carried out. Three-dimensional venous images were successfully displayed with rotational movement on the CRT monitor. The new method provided high-quality images in which the anatomical relationship between the portal and hepatic venous systems could be clearly visualized. This information was useful in helping angiographers to successfully perform transjugular intrahepatic portosystemic shunt and will be of great value for the presurgical planning of hepatic resection.

Adult↗