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Biomedical subjects

Y Amano

Publications and source records attributed to Y Amano.

At least 73 records · Page 4Linked to original sources
PubMed1996

Fine substrate specificities of four exo-type cellulases produced by Aspergillus niger, Trichoderma reesei, and Irpex lacteus on (1-->3), (1-->4)-beta-D-glucans and xyloglucan.

To investigate the fine substrate specificities of four highly purified exo-type cellulases (Exo-A from Aspergillus niger, CBHI and CBHII from Trichoderma reesei, and Ex-1 from Irpex lacteus), water-soluble substrates such as barley glucan, xyloglucan from tamarind (Tamarindus indica L.), and their oligosaccharides were employed. Four exo-type cellulases immediately hydrolyzed 3-O-beta-D-cellotriosylglucose to produce cellobiose and laminaribiose. In contrast, CBHII showed no hydrolytic activity towards 3(2)-O-beta-D-cello-biosylcellobiose, which was hydrolyzed to cellobiose by the other exo-type cellulases. These cellulases hydrolyzed the internal linkages of barley glucan and lichenan in an endo-type fashion to produce cellobiose and mix-linked oligosaccharides as main products. The DP-lowering activities of the four exo-type cellulases on barley glucan were in the order of Ex-1, CBHII, Exo-A, and CBHI. Based on gel permeation chromatography analysis of the hydrolysates, Ex-1 seemed to attack the internal cellobiosyl unit adjacent to beta-1,3-glucosidic linkages in barley glucan molecule more frequently than did the other cellulases. Xyloglucan was hydrolyzed only by CBHI and CBHII, and produced hepta-, octa-, and nona-saccharides. In addition, a xyloglucan tetradecasaccharide (XG14) was split only to heptasaccharide (XG7) by CBHI and CBHII.

Aspergillus niger↗
PubMed1996

Preliminary report on teratogenic effects of zonisamide in the offspring of treated women with epilepsy.

PURPOSE: We wished to assess the risk of teratogenicity of zonisamide (ZNS) in humans. METHODS: Pregnant epileptic women treated with ZNS and their offspring were prospectively monitored from June 1989 to December 1994. The outcome of pregnancy and status of neonates were examined based on the same standardized protocol. RESULTS: Twenty-six offspring exposed to ZNS with or without other antiepileptic drugs (AEDs) were studied. Malformations were detected in 2 offspring (7.7%) exposed to ZNS polypharmacy. Anencephaly was detected in one case at 16 weeks of gestation (case 1, artificial abortion), and atrial septal defect was detected in another case at 37 weeks of gestation (case 2, delivery by cesarean section). Serum concentrations of ZNS during the first trimester of pregnancy were 6.1 micrograms/ml in case 1 and 6.3 micrograms/ml in case 2; in both cases, the levels were below the therapeutic concentration range of ZNS. CONCLUSIONS: Teratogenic effects of ZNS were not clearly defined from these results since malformations were detected in two polypharmacy cases but not in four monopharmacy cases. The present data do not indicate that the risk of ZNS teratogenicity is greater than that of other conventional AEDs. However, such risk cannot be neglected even at therapeutic dosages or concentrations of ZNS, especially in patients receiving poly-pharmacy.

Abnormalities, Drug-Induced↗
PubMed1996

Cyclic pentapeptide endothelin A receptor antagonists with attenuated in vivo clearance.

A series of analogues of BQ-123 (1), a potent cyclic pentapeptide endothelin A receptor antagonist, with amino acids linked to the side-chain of the Pro residue via an ester linkage was synthesized. All analogues synthesized exhibited potent endothelin A receptor binding affinity similar to that of 1. Of the synthesized analogues, the Lys, Arg and N alpha,N epsilon-dimethyllysine analogues, 9d-f, exhibited about a three-fold attenuation of in vivo clearance compared with 1. In rats, these analogues exhibited a 3-fold-higher plasma concentration and a longer retention time in plasma as compared with those of 1. The attenuated in vivo clearance was thought to be a consequence of decreased extraction of the compounds from the blood via the hepatic anion transport system, which efficiently extracts 1 from the blood.

Amino Acid Sequence↗
PubMed1996

Aberrant growth of granulocyte-macrophage progenitors in juvenile chronic myelogenous leukemia in serum-free culture.

We investigated the properties of granulocyte-macrophage (GM) progenitors obtained from patients with juvenile chronic myelogenous leukemia (JCML). CD34+ bone marrow cells from a patient with JCML, unlike normal bone marrow cells, generated a large number of cells in serum-containing liquid culture without additional hematopoietic factors. In serum-deprived culture, only granulocyte colony-stimulating factor (G-CSF) had a modest stimulatory effect on GM colony growth in normal controls. In contrast, stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-3 (IL-3), as well as G-CSF, when tested individually, generated significant numbers of GM colonies in some JCML patients. All two-factor combinations generated significantly more GM colonies in JCML compared with normal controls. In particular, GM-CSF plus SCF exerted an interaction equivalent to the all-factor combination in most patients. Significant differences in the size and constituent cells of GM colonies stimulated by GM-CSF plus SCF were also observed. These results suggest that one possible mechanism for the excessive cell production in JCML is the strong proliferation of GM progenitors induced by hematopoietic factors, especially SCF. According to immunofluorescent analysis, however, it is unlikely that this multiplication is due to an increase in the cell surface expression of c-kit receptors on JCML progenitors.

Antigens, CD34↗
PubMed1996

[MR images of bone marrow in aplastic anemia and correlation between MR findings and age].

We observed 125 lumbar vertebrae in 25 patients with aplastic anemia using a 0.5-T MR imager. Bone marrow patterns of aplastic anemia on STIR images were classified into five types: 1) homogeneously low intensity fatty marrow, 2) fatty marrow with scattered hematopoietic nodules, 3) fatty marrow with marginal hematopoietic regions, 4) fatty marrow surrounded by bandlike hematopoietic regions, and 5) homogeneously high-signal-intensity hematopoietic marrow. STIR images defined the fatty marrow as a markedly hypointense region and the hematopoietic marrow as a high signal intense area. Many cases included the homogeneously fatty marrow and fatty marrow with marginal hematopoietic areas, whereas marrow with a broad range of hematopoiesis was detected in patients younger than 40 years. MR images also demonstrated that fatty marrow could shift to hematopoietic marrow following therapy. MR images were useful for detection of the bone marrow distribution of aplastic anemia, related to aging and treatment.

Adolescent↗
PubMed1996

[MR imaging of hematopoietic regions in bone marrow of aplastic anemia : diagnostic usefulness of opposed phase T1-weighted images].

The signal intensity of hematopoietic regions in the marrow of aplastic anemia were investigated on opposed phase T1-weighted images (op-T1WI) with a 0.5-Tesla MR unit. Hematopoietic regions were classified into two groups : 1) low intensity hematopoietic areas (LH) isointense to normal marrow and 2) high intensity hematopoietic regions (HH) with higher intensity than normal marrow on op-T1WI. a) The signal intensity of LH was significantly lower than that of HH on STIR. b) LH converted in to HH with improvement of laboratory data after therapy, whereas HH decreased with impairment of data. c) In addition, HH were hyperintense to cerebrospinal fluid on op-T1WI. These results indicated that the signal intensity of hematopoietic regions on op-T1WI reflected the cellularity in these regions and that aplastic anemia included hypercellular regions relative to normal marrow.

Adolescent↗
PubMed1995

Autocrine growth of transitional cell carcinoma of the bladder induced by granulocyte-colony stimulating factor.

Granulocyte-colony stimulating factor (G-CSF) produced by nonhematopoietic malignant cells has been reported to be capable of inducing a leukemoid reaction in the host through intense stimulation of leukocyte production. Furthermore, this is frequently associated with aggressive tumor cell growth and a detrimental clinical outcome. In this study, we identified bladder cancer cells producing G-CSF with the expression of the functional receptor, which provides direct evidence of autocrine growth of bladder cancer cells induced by G-CSF. The cancer cells used in this study were obtained from a 76-year-old man who had a metastatic transitional cell carcinoma of the bladder and who demonstrated marked leukocytosis, his peripheral blood leukocyte count was 94,900 leukocytes/mm3, and his serum G-CSF level was 103 pg/ml. The culture medium in which the cancer cells were grown exclusively contained a significant amount of G-CSF (5560 pg/ml). Significant G-CSF mRNA expression and G-CSF receptor mRNA expression in the cultured cells were demonstrated by the reverse transcription-PCR method. In addition, binding studies with the use of radiolabeled recombinant G-CSF demonstrated the presence of high-affinity G-CSF binding receptors on the cultured cancer cells. Finally, the proliferation of the cultured cancer cells was stimulated by exogenous G-CSF administration, and this stimulation was inhibited by adding anti-G-CSF antibody, as demonstrated by both the flow cytometric bromodeoxyuridine incorporation technique and the [3H]thymidine incorporation assay. These results strongly suggest that G-CSF production by the bladder cancer cells studied augments autocrine growth. Therefore, we recommend exercising caution in the clinical use of G-CSF for bladder cancer patients.

Aged↗
PubMed1995

Purification and characterization of an ATP-dependent amidohydrolase, N-methylhydantoin amidohydrolase, from Pseudomonas putida 77.

N-Methylhydantoin amidohydrolase, an ATP-dependent amidohydrolase involved in microbial degradation of creatinine, was purified 70-fold to homogeneity, with a 62% overall recovery, and was crystallized from Pseudomonas putida 77. The enzyme has a relative molecular mass of 300,000. It is a tetramer of two identical small subunits (M(r) 70,000) and two identical large subunits (M(r) 80,000). The enzyme requires ATP for the amidohydrolysis of N-methylhydantoin and vice versa. Mg2+, Mn2+ or Co2+, and K+, NH4+, Rb+ or Cs+, were absolutely required concomitantly for the enzyme activity as divalent and monovalent cations, respectively. The Km and Vmax values for N-methylhydantoin were 32 microM and 9.0 mumol.min-1.mg protein-1. The hydrolysis of amide compounds and coupled hydrolysis of ATP were observed with hydantoin, DL-5-methylhydantoin, glutarimide and succimide in addition to N-methylhydantoin. 2-Pyrrolidone, 2-oxazolidone, delta-valerolactam, 2,4-thiazolidinedione, 2-imidazolidone, D-5-oxoproline methyl ester, DL-5-oxoproline methyl ester, and naturally occurring pyrimidine compounds, i.e. dihydrouracil, dihydrothymine, uracil, and thymine, effectively stimulated ATP hydrolysis by the enzyme without undergoing detectable self-hydrolysis.

Adenosine Triphosphate↗
PubMed1995

[Contrast enhancement and morphological findings of hematopoietic regions of bone marrow on MR imaging: comparative study with spondylitis and vertebral tumors].

The enhanced MR findings of hematopoietic regions in aplastic anemia were compared with those of spondylitis, metastatic vertebral tumors and hematologic neoplasms. The enhanced MR images showed hematopoietic regions to homogeneously enhance and occupy the margin of vertebral bodies, while spondylitis and metastatic tumors appeared as round, inhomogeneously enhancing lesions. MR images of leukemia and myelodysplastic syndrome showed homogeneous enhancement at the margins of vertebrae that was difficult to differentiate from hematopoietic regions. Enhanced MR images were useful in detecting the hematopoietic areas in marrow and differentiating them from spondylitis and metastatic tumors, although further experience is needed to distinguish between tumorous hyperplastic regions and benign hematopoietic regions in marrow.

Adult↗
PubMed1994

Binding of [3H](+)-PN200-110 to aortic membranes from normotensive and spontaneously hypertensive rats.

We report here the quantitative evaluation of binding density (Bmax) of [3H](+)-PN200-110 in aortic membranes obtained from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. At both 4 and 13 weeks of age, there were no significant differences in Bmax and the dissociation constants (Kd) of [3H](+)-PN200-110 binding between SHR and WKY rat aortas. Irrespective of strain, the Kd increased and the Bmax decreased with age. These results suggest that the number of Ca2+ channels in aortas of SHR and WKY rats are not significantly different, even when hypertension is established in SHR.

Aging↗
PubMed1994

[Evaluation of bone marrow by opposed phase T1-weighted images and enhanced MR imaging].

We investigated bone marrow in a control group, cases of aplastic anemia and post-irradiation patients by examining T1-weighted (T1WI), short TI inversion recovery (STIR), opposed phase T1WI (op-T1WI) and Gd-DTPA enhanced op-T1WI images obtained by 0.5T MRI. Bone marrow was classified into four types based on MR findings. Normal marrow showed low intensity on op-T1WI and STIR images without enhancement (I). Fatty marrow, which showed high intensity on T1WI and op-T1WI images was observed in aplastic anemia and post-irradiation patients (II). Hematopoietic marrow (III) showed low intensity on op-T1WI and enhanced, while active hematopoietic marrow (IV) revealed high intensity on both STIR and op-T1WI images and was enhanced following Gd-DTPA infusion. Aplastic anemia of moderate grade included types II, III and IV. Enhanced MR was needed to differentiate between types I and III since both types showed low intensity on op-T1WI images. Furthermore, type IV was considered as hyperplastic compared with type III. Enhanced MR and op-T1WI images were useful in evaluating hematopoiesis of bone marrow.

Adolescent↗
PubMed1994

Species-dependent expression of the hyoscyamine 6 beta-hydroxylase gene in the pericycle.

The tropane alkaloid scopolamine is synthesized in the pericycle of branch roots in certain species of the Solanaceae. The enzyme responsible for the synthesis of scopolamine from hyoscyamine is hyoscyamine 6 beta-hydroxylase (H6H). The gene for H6H was isolated from Hyoscyamus niger. It has an exon/intron organization very similar to those for ethylene-forming enzymes, suggesting a common evolutionary origin. The 827-bp 5' flanking region of the H6H gene was fused to the beta-glucuronidase (GUS) reporter gene and transferred to three solanaceous species by Agrobacterium-mediated transformation systems: H. niger and belladonna (Atropa belladonna), which have high and low levels, respectively, of H6H mRNA in the root, and tobacco (Nicotiana tabacum), which has no endogenous H6H gene. Histochemical analysis showed that GUS expression occurred in the pericycle and at the root meristem of transgenic H. niger hairy roots, but only at the root meristem of transgenic H. niger hairy roots, but only at the root meristem of hairy roots and plants of transgenic tobacco. In transgenic hairy roots and regenerated plants of belladonna, the root meristem was stained with GUS activity, except for a few transformants in which the vascular cylinder was also stained. These studies indicate that the cell-specific expression of the H6H gene is controlled by some genetic regulation specific to scopolamine-producing plants.

Amino Acid Sequence↗
PubMed1994

[The usefulness of MRI for the diagnosis of abnormal pregnancies].

The clinical usefulness of MRI for the diagnosis of abnormal pregnancies was evaluated. Pelvic MRI was carried out on 29 cases suspected of abnormal pregnancy by ultrasonography and clinical examinations. The abnormal pregnancies were classified into three categories: (1) maternal abnormalities, (2) fetal abnormalities and (3) placental abnormalities. (1) MRI was of great value for the diagnosis of maternal abnormalities, particularly in cases of coexistent pelvic tumors. MRI allowed diagnosis of uterine leiomyomas and dermoid cyst through its excellent tissue characterization and broad range of vision. (2) MRI was useful in making diagnoses of fetal central nervous anomalies and fetal death, since the lack of fetal movement and the lesions were clear enough to be detected by MRI. However, anomalies in the fetal trunk or extremities could only be demonstrated, but not diagnosed, by MRI owing to its inferior spatial and time resolution. (3) MRI showed placenta accreta and placental hematoma. Although accurate diagnosis was difficult because of their rarity, MRI revealed the hemorrhagic component of the lesions, which was not shown by ultrasonography. The author believes MRI has potential usefulness in making diagnoses of placental abnormalities through its tissue characterization. MRI was superior to ultrasonography in the soft tissue characterization, field of view, while MRI was inferior in time and spatial resolution. In summary MRI should be used in case of abnormal pregnancies such as pelvic tumors, fetal nervous anomalies and placental hemorrhagic lesions. MRI will become useful for the diagnosis of other abnormalities as its spatial resolution and fast scan technology advances.

Adult↗
PubMed1994

Effects of lymph node stromal cells on the differentiation of a cell line established from an atypical prolymphocytic leukemia with phenotypes of both chronic lymphocytic and hairy cell leukemias.

We investigated the effects of stromal cells, obtained from lymph nodes with various lymphoid disorders and characterized immunocytochemically as fibroblasts, on the maturation of a cell line "HN" established from an atypical PLL (prolymphocytic leukemia) having phenotypic characteristics of both CLL (chronic lymphocytic leukemia) and HCL (hairy cell leukemia). Coculture with stromal cells, irrespective of the kind of lymphoid disease affecting the lymph node, induced a plasmacytoid cytology in HN cells, an increase of cIg gamma, and decreases of sIg gamma, CD5, CD21, HC2, and B-ly7. In contrast, coculture with the stromal cells produced no marked effects on hairy cells from two HCL patients. Similarly, coculture with stromal cell supernatant or with various cytokines shown to be produced by bone marrow stromal cells produced no effects on HN cells. We propose that lymph node stromal cells play an important role in the differentiation of B cells through direct contact and that HN cells will be useful for investigating the differentiation pathway of chronic B cell leukemia cells.

Acid Phosphatase↗
PubMed1994

Quantitative evaluation of intraarterial lymphocyte injection therapy for lymph edema using MR imaging.

Five patients with unilateral leg lymph edema had intraarterial injections of lymphocytes in the affected leg with consequent improvement in 3. To assess the degree of lymph edema, T2 and intensity ratio between the 2 legs in STIR images were used. Mean and SD of T2 values in the subcutaneous tissue were measured using a triple echo sequence and found larger on the edematous side than in the opposite extremity. The mean T2 shortening obtained after the lymphocyte therapy correlated well with the reduction of limb circumference. Mean T2 reflects the fluid content, and SD of T2 the fluid distribution in the subcutaneous tissue. The degree of lymph edema and the effect of therapy can be evaluated quantitatively by measuring the value of the T2 relaxation time.

Adult↗