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Biomedical subjects

S Katoh

Publications and source records attributed to S Katoh.

At least 235 records · Page 13Linked to original sources
PubMed1991

Cloning and sequencing of cDNA encoding human sepiapterin reductase--an enzyme involved in tetrahydrobiopterin biosynthesis.

A full-length cDNA clone for sepiapterin reductase, an enzyme involved in tetrahydrobiopterin biosynthesis, was isolated from a human liver cDNA library by plaque hybridization. The nucleotide sequence of hSPR 8-25, which contained an entire coding region of the enzyme, was determined. The clone encoded a protein of 261 amino acids with a calculated molecular mass of 28,047 daltons. The predicted amino acid sequence of human sepiapterin reductase showed a 74% identity with the rat enzyme. We further found a striking homology between human SPR and carbonyl reductase, estradiol 17 beta-dehydrogenase, and 3 beta-hydroxy-5-ene steroid dehydrogenase, especially in their N-terminal region.

Alcohol Oxidoreductases↗
PubMed1991

Computer studies on the stereostructure and quantum chemical properties of 6-pyruvoyl tetrahydropterin, the key intermediate of tetrahydrobiopterin biosynthesis.

The optimized geometry of the conformation of atoms constituting the 6-pyruvoyl tetrahydropterin molecule, the labile key intermediate of tetrahydrobiopterin biosynthesis, was obtained by molecular orbital calculations within the MINDO/3 framework. The stereostructure of the molecule showing the preferred mode for binding to sepiapterin reductase or pyruvoyl tetrahydropterin reductase was drawn in perspective. The resulting structure with the equatorial staggered configuration of the 6-1',2'-dioxopropyl (pyruvoyl) side chain indicated that O(1') and H(6) were located in the trans position around the C(6)-C(1') bond and that the two vicinal carbonyls in the side chain were fixed in the incomplete trans form. The calculation of atomic charges and LUMO coefficients of these carbonyls suggests that the C2'-carbonyl may be more reactive toward NADPH than the C1'-carbonyl in the enzymatic reaction.

Alcohol Oxidoreductases↗
PubMed1991

[Qualitative assessment of centrilobular emphysema using computed tomography].

The ability of computed tomography (CT) in the qualitative assessment of centrilobular emphysema (CLE) was studied, with special reference to the morphological relationship between emphysematous change and relatively large bronchovascular bundle forming the margin of secondary pulmonary lobule. Three autopsied lobes with mild, moderate and severe CLE were fixed by the method of Heitzman. Then high resolution CT (HRCT) was applied to those inflation-fixed lobes, which allowed for direct one-to-one pathologic correlation. Furthermore, HRCT findings of these clinical cases with emphysema were analysed. Emphysematous change in CLE was observed as low-attenuation area (LAA) within the homogeneous background on Ct images. In mild and moderate cases, LAA's were round or oval in shape, however in severe case they were observed to be irregular in shape. The border between LAA and parenchyma was not clearly defined, however in severe case LAA was found to be bordered partially or rather subtotally by the bronchovascular bundle. In mild and moderate cases, LAA's were observed to be distant from relatively large bronchovascular bundle. On the other hand, in severe case, only a small amount of lung parenchyma was left between LAA and bronchovascular bundle. These findings correspond to morphologic characteristics of CLE, that is, the process of emphysematous change tends to take place in the center of the secondary lobule, and even if the lobe is severely destroyed, some portion of the peripheral acinus is still preserved at lobular margin. Thus, CT can help to identify the presence of CLE. Furthermore, CT scan analysis of severe grade emphysema may lead to the differentiation between CLE and panlobular emphysema.

Aged↗
PubMed1991

Transgenic mice expressing a B cell growth and differentiation factor gene (interleukin 5) develop eosinophilia and autoantibody production.

Interleukin 5 (IL-5) has been suggested to be involved in the growth and differentiation of B cells and eosinophils. Especially, Ly-1+ B cells, which have been considered to produce autoantibodies, are selectively developed by this lymphokine in long-term bone marrow culture. To envisage the possible engagement of IL-5 in the development of these cells in vivo, transgenic mice carrying the mouse IL-5 gene ligated with a metallothionein promoter were generated. Transgenic mice carrying the IL-5 gene exhibited elevated levels of IL-5 in the serum and an increase in the levels of serum IgM and IgA. A massive eosinophilia in peripheral blood, bone marrow, and spleen, and an infiltration of muscle and liver with eosinophils, were observed. When cadmium-containing saline was injected intraperitoneally into transgenic mice, IL-5 production was augmented about five times within 24 h, and a distinctive Ly-1+ B cell population became apparent in the spleen after 5 d. IL-5 receptors were detected on those cells by monoclonal antibodies against IL-5 receptors. Another interesting finding in these transgenic mice was an increase in polyreactive anti-DNA antibodies of IgM class. It is suggested, therefore, that aberrant expression of the IL-5 gene may induce accumulation of Ly-1+ B cells and eosinophils. Furthermore, this IL-5 transgenic mouse can be a model mouse for eosinophilia, and we can determine the role of IL-5 in the differentiation of Ly-1+ B cells and eosinophils by using this mouse.

Animals↗
PubMed1991

Changes in transglutaminase activity in carbon tetrachloride-damaged rat liver.

A significant decrease in transglutaminase (TGase) activity was observed in the cytosol and nuclear fractions of carbon tetrachloride-damaged rat liver. The degree of decrease in TGase activity in the cytosol fraction was closely related to the serum transaminase level. Gel filtration studies revealed that TGase activity in 80 kDa fractions significantly decreased, but that in 160 kDa fractions slightly increased after carbon tetrachloride treatment.

Alanine Transaminase↗
PubMed1991

Incorporation and activation of a membrane-bound enzyme in bilayers of liposomes.

The effects of lipid composition and fluidity of lipid bilayers on incorporation and activation of membrane-bound D-fructose dehydrogenase are described in this study. The incorporation of the enzyme into bilayers of small unilamellar vesicles (SUV) made of several phospholipids resulted in enzyme activation with magnitudes higher than that observed in the presence of Triton X-100, indicating that this higher activation is due to lipid-protein interaction. The activity was highest in the presence of SUV formed by the addition of 10% DL-alpha-dipalmitoylphosphatidylethanolamine to L-alpha-dimyristoylphosphatidylcholine, which resulted in eightfold higher activation compared with that of the enzyme in its free state. This activation did not appear to be due to the degree of incorporation of the enzyme, indicating that incorporation is distinct from the activation event. Thus, it is probably the lipid environment that leads to higher activation of the enzyme. A break in the Arrhenius plot of the activity of the membrane-bound enzyme at temperatures close to the phase transition of the phospholipid implies that changes in the physical state of the lipid bilayer influence the enzyme activity. Furthermore, immobilization of D-fructose dehydrogenase, previously adsorbed to SUV, on urethane prepolymer also resulted in about eightfold higher activation than that of the free enzyme.

Carbohydrate Dehydrogenases↗
PubMed1991

Studies on 67Ga uptake by mouse granuloma tissues.

In connection with the uptake of 67Ga into the inflammatory tissues, such as granuloma tissues produced with turpentine oil, the influence of Fe3+ on the uptake of 67Ga into mouse granuloma and normal tissues and on the uptake of 125I-labeled transferrin and 59Fe were investigated. Fe3+ decreased the uptake of 67Ga into the liver and spleen, but had no influence on the uptake of 67Ga into the granuloma tissues. The uptake patterns of 125I-labeled transferrin and 59Fe in the granuloma tissues were not consistent with that of 67Ga at all. These results show that the uptake of 67Ga into the granuloma tissues occurs in a free, transferrin-unbound form, but into the liver and spleen in a transferrin-bound form.

Animals↗
PubMed1991

Culture of human outer root sheath cells from plucked hair follicles in serum-free conditions.

We succeeded in culturing human outer root sheath cells (ORSC) in serum-free conditions without a biological feeder layer. The combination of collagen type IV substrate and modified MCDB 153 medium supplemented with bovine pituitary gland extract (K-GM medium) could support the growth of ORSC. These cells can be serially cultivated for at least 4 passages and stored in liquid nitrogen with good recovery. Thus, a large series of experiments using ORSC may be run simultaneously.

Cell Division↗
PubMed1991

Internalization model using rat liver plasma membrane for receptor-mediated endocytosis of epidermal growth factor.

We have demonstrated the internalization of epidermal growth factor (EGF) using membrane isolated from rat liver. The isolated membrane exhibited a saturation curve of the binding of 125I-EGF. Furthermore, competition between the binding of 125I-EGF and unlabeled EGF to the isolated membrane was observed. These results were similar to those obtained from whole hepatocytes. In order to confirm whether or not the present experimental system using the isolated membrane can be used for the study of receptor-mediated endocytosis, the internalization of pre-bound EGF in the isolated membrane was assessed by two different methods. First, acid-insensitive 125I-EGF time-dependently increased following incubation at 37 degrees C. Secondly, EGF became inaccessible to the exogenous 125I-anti-EGF antibody when under the same condition. These processes were dependent on adenosine triphosphate, but independent of Ca2+ and stimulated by guanosine triphosphate. These results demonstrate that receptor-mediated endocytosis occurred in the isolated membrane.

Animals↗
PubMed1991

Appraisal of adjuvant chemoendocrine therapy with tamoxifen plus tegafur in patients with breast cancer.

To assess chemoendocrine therapy in the adjuvant treatment of patients with Stage II or III breast cancer, 228 patients were enrolled in a 12-month trial period from January 1982 to January 1983. One hundred ninety evaluable patients were followed up for five years. The regimen in this trial consisted of intravenous administration of 13 mg of mitomycin C per m2 during the operation and 6.5 mg of the same drug per m2 on the first day, and oral administration of 600 mg of tegafur per m2 alone or supplemented with 13 mg of tamoxifen per m2 for two years. No survival advantage was observed with addition of tamoxifen to tegafur in terms of five-year survival (88.7% vs 86.6% for Stage II and 69.9% vs 82.2% for Stage III). However, there was a significant prolongation of relapse-free survival among patients receiving tegafur and tamoxifen as compared with those who received tegafur alone: 72.9% vs 55.8% (p = 0.098 in the logrank test).

Adult↗
PubMed1991

[Anti-bacterial defense mechanisms of the urinary tract constructed from intestinal segments. Studies on cell population and phagocytotic activity of urinary leucocytes, and bacterial growth in urine].

Cell population of urinary leucocytes of 22 patients (intestine group) who underwent operations using intestinal segments for the urinary tract was compared with that of 26 complicated UTI patients without surgical intervention (control group). Eosinophils were recognized in 15.5 per cent of urinary leucocytes of the intestine group. However, in the control group, urine eosinophils were recognized only in 0.15 per cent. Although in sterile urines of the intestine group eosinophils were recognized in 30.8 per cent, in infected urines, the percentage of eosinophils decreased. Conversely, the percentage of neutrophils increased to 91.9 per cent. These findings suggest that neutrophils play an important role in infected urines of the intestine group as in urines of the control group. Significant differences were found in the values of urinary secretory IgA, IgG, IgM and urinary osmolarity. To evaluate the influence of these differences on the activity of phagocytosis of urinary leucocytes, the activity of phagocytosis of polymorphonuclear leucocytes (PMN), isolated from the peripheral blood, was investigated in immersion in urines of both groups. The mean rate of phagocytosis of E. coli in urines of both groups showed no statistically significant differences. However, urinary osmolarity of the intestine group was within the suitable range for phagocytosis and the activity of phagocytosis in urine was correlated with the value of IgG, which suggests that IgG has the opsonic effect. In contrast, the activity of phagocytosis in urine of the control group was strongly correlated with the value of urinary osmolarity. The growth of Providencia, Streptococcus, P. aeruginosa, whose frequency of isolation from urine of both groups was different in our previous study, and E. coli was studied in urine of the two groups. No significant difference in the growth of all bacteria was found, however. This finding suggests that the difference in the frequency of isolation of these bacteria from urine possibly depends on the adhesion of bacteria to intestinal epithelium.

Adolescent↗
PubMed1991

[Anti-bacterial defense mechanisms of the urinary tract constructed from intestinal segments. Preliminary studies on urinary tract infections, secretory IgA and composition of urine].

The characteristics of urinary tract infections (UTI), secretory IgA and urine composition of 24 patients (intestine group) who underwent operations using intestinal segments in urinary tract were compared with those of 26 complicated UTI patients without surgical intervention (control group). No significant differences were found in the frequency of either mono or polymicrobial infections between both groups. However, the frequency of bacterial isolation was different in the two groups, Streptococcus spp. and Providencia spp. were frequently isolated and P. aeruginosa was rarely isolated from the urine of the intestine group compared with from the urine of the control group. Furthermore, in polymicrobial infections of the intestine group with indwelling catheters, E. faecalis and Providencia spp. were frequently isolated simultaneously. The mean value of urinary secretory IgA was 94.0 micrograms/dl in the intestine group and 25.0 mu/dl in the control group (p less than 0.0001). The mean urinary osmolarity was 370 mOsm/kg in the intestine group and 500 mOsm/kg in the control group (p less than 0.005). The other parameters, including urinary pH and urea N concentration, showed no statistically significant differences. These findings suggest that urinary tract constructed from intestinal segments differs from the urinary tract without surgical intervention in the feature of UTI and anti-bacterial defense mechanisms.

Adolescent↗
PubMed1991

[CT findings in panacinar emphysema].

We analyzed the CT images (in vivo) of 5 lobes (right middle lobe, 1; left lower lobe, 1; right lower lobe, 3) with panacinar emphysema (PAE) obtained at autopsy or thoracotomy for solitary lung tumor. The lobes were inflation-fixed by the method of Heitzman and sliced axially for a CT-pathologic correlative study. One lobe with mild PAE had normal appearance on CT; however, the other four lobes with PAE demonstrated low-attenuation areas (LAAs) of various shapes and sizes on CT. LAAs were locally distributed on CT slices in one lobe, dominant in the inner zones in two lobes, and diffuse in one lobe. Relatively normal to diminished vasculature was observed within the LAAs of four lobes. These CT findings differed significantly from those of centriacinar emphysema (CAE) as reported in other studies. We conclude that CT is useful in the clinical diagnosis of PAE and its differentiation from CAE.

Aged↗
PubMed1991

Effect of dietary chloride on spontaneously hypertensive rat.

The anionic component of sodium salt has been reported to contribute to hypertension in some animal models and hypertensive patients. In the present study, the anionic effects on exacerbation of hypertension in spontaneously hypertensive rat (SHR) were investigated by chronic loading tests with two sources of sodium, viz. sodium chloride (NaCl; 0.9% solution) and sodium bicarbonate (NaHCO3; 1.28% solution), using SHRs with normal renal function (NRF) and with chronic renal failure (CRF; produced by cryosurgery). In addition, extracellular fluid volume (ECFV: inulin space) was measured in SHRs with NRF and CRF. In the NRF groups, systolic blood pressure (SBP) reached 230 mmHg at Week 13, and there was no significant difference in SBP between the NaCl and NaHCO3 groups. In the CRF groups, SBP of the NaCl group was significantly higher (p less than 0.01) than that of the NaHCO3 group (280 mmHg vs. 230 mmHg at Week 15). ECFV was also greater in the NaCl group than in the NaHCO3 group (ECFV: NaCl vs. NaHCO3, 15.9 +/- 1.7 vs. 14.0 +/- 0.9 at Week 13; and 16.2 +/- 1.1 vs. 14.2 +/- 1.2 at Week 15, respectively). These results indicate that chloride ion plays an important role in the pathogenesis of hypertension in SHR with CRF. Expansion of ECFV is considered to be one of the mechanisms whereby the hypertension is exacerbated.

Animals↗
PubMed1991

Modulation of epidermal growth factor binding to receptor by isoproterenol and cholera toxin in primary cultured hepatocytes.

The treatment of rat hepatocytes with isoproterenol induced the increase in the affinity of high affinity binding sites and the decrease in the number of low affinity binding sites of epidermal growth factor (EGF). Similar results were obtained from the pretreatment of hepatocytes with cholera toxin. These results suggest that adenylate cyclase affects the affinity and number of EGF-receptor in hepatocytes.

Adenylyl Cyclases↗
PubMed1991

Irregular isoantibodies in the sera of patients undergoing chronic hemodialysis.

We screened 89 patients undergoing chronic hemodialysis for irregular isoantibodies. Irregular isoantibodies were detected in six patients (6.7%). This is an extremely high percentage compared with previous reports, considering that the presence of irregular isoantibodies was estimated to be 2.91% in multiparas, in whom they were found most frequently. This may be due to the fact that hemodialysis patients often receive blood transfusions but it also suggests that hemodialysis per se may induce the production of irregular isoantibodies. The blood-group specificities of the irregular isoantibodies detected were anti-N, anti-Leb + anti-HI, anti-Lea + anti-Leb, anti-H and anti-I, anti-P1, anti-rh" (E). The majority of the cases with irregular isoantibodies were examined because of clinical problems during hemodialysis. Therefore, we checked for the presence of irregular isoantibodies before the induction of hemodialysis and every three to six months thereafter.

Adult↗