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Biomedical subjects

A Manabe

Publications and source records attributed to A Manabe.

At least 73 records · Page 4Linked to original sources
PubMed1998

2-HEMA-free dentin bonding system to prevent contraction gap.

The effects of 2-hydroxyethyl methacrylate (2-HEMA) both in the primer and in the commercial dentin bonding agent on the efficacy of the dentin bonding system was evaluated by measuring the polymerization contraction gap width of a commercial resin composite restored in a cylindrical dentin cavity prepared in an extracted human molar. Contraction gap formation was prevented in the group of the EDTA-conditioning followed by glyceryl mono-methacrylate, ethylene glycol and 1,6-hexanediol priming regardless of the 2-HEMA content in the dentin bonding agent containing 10-methacryloxydecyl dihydrogen phosphate. However, gap formation could not be prevented completely by the 2-HEMA priming. Therefore, it was possible to conclude that 2-HEMA was neither essential in the primer nor in the dentin bonding agent because of its low bonding efficacy and the resulting side effects on skin tissue as a delayed allergic reaction.

Dental Bonding↗
PubMed1997

Prevalence and growth characteristics of malignant stem cells in B-lineage acute lymphoblastic leukemia.

We used a stroma-supported culture method to study the prevalence and growth characteristics of malignant stem cells in acute lymphoblastic leukemia (ALL). In 51 of 108 B-lineage ALL samples, bone marrow-derived stroma not only inhibited apoptosis of ALL cells but also supported their proliferation in serum-free medium. When single leukemic cells were placed in the stroma-coated wells of microtiter plates, the percentage of wells with leukemic cell growth after 2 to 5 months of culture ranged from 6% to 20% (median, 15%; 5 experiments). The immunophenotypes and genetic features of cells recovered from these cultures were identical to those noted before culture. All cells maintained their stroma dependency and self-renewal capacity. Leukemic clones derived from single cells contained approximately 10(3) to 10(6) cells after 1 month of culture; other clones became detectable only after prolonged culture. Cell growth in stroma-coated wells correlated with the number of initially seeded cells (1 or 10; r = .87). However, the observed percentages of positive wells seeded with 10 cells always exceeded values predicted from results with single-cell-initiated cultures (P < .003 by paired t-test), suggesting stimulation of leukemic cell growth by paracrine factors. In conclusion, the proportion of ALL cells with clonogenic potential may be considerably higher than previously thought.

Adipose Tissue↗
PubMed1997

Three-dimensional ultrasonography in the first trimester of human pregnancy.

Our purpose was to visualize normal embryonal and fetal surface anatomical structures in the first trimester of human pregnancy by use of three-dimensional ultrasonography with a specially developed abdominal three-dimensional transducer. Four embryos and 31 fetuses of 8-13 weeks gestation were studied with a specially-developed abdominal three-dimensional transducer (3.5 MHz). This imaging system can provide conventional two-dimensional ultrasonography images and can also generate, within seconds, high-quality three-dimensional images in the surface and transparent mode with no need for an external workstation. The percentage of surface anatomical structures visualized at each gestational age interval using two-dimensional and three-dimensional ultrasonography is presented. Head and trunk were depicted in all cases. The number and the clarity of visualization of face, upper and lower extremities, hand, and foot increased with advancing gestation. The free loop of the umbilical cord was depicted in most cases. The number of depictions of abdominal cord insertion, midgut herniation, and yolk sac decreased with the increase of gestation. Genitals could not be identified in the first trimester. The ability to view some surface anatomical structures (face, hand, and foot) was better with three-dimensional ultrasonography than with two-dimensional ultrasonography. Three-dimensional ultrasonography provides a novel means for visualization of surface anatomical structures of the embryo and early fetus. These results suggest that three-dimensional ultrasonography can become an important modality in future embryological and early fetal research and in detection of embryonic and fetal developmental disorders in the first trimester of pregnancy.

Cross-Sectional Studies↗
PubMed1997

Assessment of embryonic anatomy at 6-8 weeks of gestation by intrauterine and transvaginal sonography.

Our purpose was to compare the ultrasound visualization of the early first-trimester embryo using transvaginal and intrauterine sonography. In all, 32 women about to undergo therapeutic abortion at 6-8.9 weeks gestation were studied using a specially developed catheter-based, high-resolution, real-time miniature (2.4 mm outer diameter) ultrasonography transducer (20 MHz). Before the intrauterine sonographic procedure was performed, transvaginal sonographic assessment of the embryo was conducted. The parameters evaluated included the ability to visualize anatomical structures and a subjective assessment of the overall image clarity. The ability to view most organs was better with intrauterine sonography compared to transvaginal sonography, and this was especially true for the brain, spine, heart, liver, midgut herniation, extremities, and sacral tail. Moreover, it was possible to obtain finer image quality of very small embryonic structures with intrauterine sonography than with transvaginal sonography. Stomach, spleen, kidney, and bladder could not be depicted with both techniques. One cystic hygroma was diagnosed at 7 weeks 6 days using intrauterine sonography, but not with transvaginal sonography. Intrauterine sonography may provide additional information on the visualization of anatomical structures of the embryo in the early first trimester of pregnancy. In this limited series, one case of cystic hygroma was demonstrated and, thus, there is a potential for its use in the early detection of embryonic malformation. These results suggest that intrauterine sonography may be a valuable tool in imaging the early first-trimester embryo, complementing and not replacing transvaginal sonography in high-risk pregnancies.

Congenital Abnormalities↗
PubMed1997

Plasma catecholamines and Doppler-derived cardiac time intervals in vaginally and cesarean delivered neonates.

OBJECTIVE: Our purpose was to compare Doppler-derived cardiac time intervals and cord plasma levels of catecholamines in vaginally and cesarean delivered neonates. METHODS: Doppler echocardiographic assessments of fetal and neonatal cardiac time intervals were made to determine differences in circulatory changes in 8 neonates delivered vaginally and 12 delivered by elective cesarean section. Aortic and pulmonary acceleration time (AT), ejection time (ET), and the AT/ET ratio in systole were assessed at various time points from antenatal to 72 h after delivery. Umbilical artery blood gas and acid-base values, and cord blood concentrations of epinephrine and norepinephrine were also measured. RESULTS: Umbilical artery blood pH in the cesarean section group was significantly lower than that in the vaginal delivery group (p < 0.05). Base deficit in umbilical artery blood and cord blood norepinephrine in cesarean delivered neonates were significantly higher than those in vaginally delivered neonates, respectively (p < 0.05). There were no significant changes in aortic cardiac time intervals between the 2 groups at any of the various time points. However, pulmonary AT and the AT/ET ratio were significantly lower in the normal vaginal delivery group than those in the cesarean section group 6 h after delivery (p < 0.05). CONCLUSIONS: The lower AT and AT/ET ratio of the pulmonary artery in vaginally delivered neonates may reflect an increase in pulmonary vascular resistance, indicating transient pulmonary hypertension. The findings were the reverse of what might be expected from an elevated pulmonary vascular resistance and transient pulmonary hypertension in cesarean delivered neonates.

Adult↗
PubMed1997

[Phagocytosis of fungi in the peripheral blood neutrophils of two children with cancer during treatment with fluconazole].

We report on two children with malignancy who showed fungemia despite the antifungal treatment with fluconazole. Case 1 was a 7-year-old girl with a recurrence of stage IV neuroblastoma. She had profound neutropenia and fungemia developed after a month-long treatment with fluconazole. Her peripheral blood smear showed phagocytosis in the neutrophils and they were identified as fungi by immunofluorescence method (Fungi flora Y). She died two days after the diagnosis of fungemia. Rhodotorula rubra was isolated after her death. Case 2 was a 2-year-old boy with disseminated Langerhans cell histiocytosis. He had profound neuropenia and fungemia developed after treatment with fluconazole for 6 months. His peripheral blood smear also showed phagocytosis in the neutrophils and they were identified as fungi by Fungi flora Y. He was treated with intravenously administered amphotericin-B. However, he died 13 days after the diagnosis of fungemia. Candida guilliermondii was isolated after his death. Careful observation of the peripheral blood smear is important for early detection of fungi and Fungi flora Y is a quick and useful method to identify fungi. Fluconazole-resistant fungus should be considered when patients with neutorpenia are treated prophylactically with fluconazole for a long time.

Antifungal Agents↗
PubMed1996

Transcriptional repression activity of N-MYC protein requires phosphorylation by MAP kinase.

The transrepressing function of the N-myc protein is due to the distinct domains located at the N-terminus. In this report we introduced various point mutations around the myc boxes of the N-myc protein to examine whether the phosphorylation of the protein affected its transrepressing function. Serine (Ser) residues located at amino acid numbers 12, 31, 51, and 65 were changed to leucine or arginine, and the expression vectors of the mutant proteins were transfected to HeLa cells together with the luciferase gene linked to the MHC class I gene. Among the mutants, only the N(51)-myc carrying mutation at Ser(51), a target for mitogen-activated protein kinase (MAP kinase), lost the repression activity, while the other mutant proteins preserved it. Formation in vitro of the specific nucleoprotein complexes on the H2TF1/NFkappaB element, a major target for transrepression by N-myc protein, was interfered by the wild-type N-myc protein, but not by the Ser(51)-mutated protein. The results suggest that the phosphorylation of the N-myc protein at Ser(51) by MAP kinase is required for the transcriptional repression activity of the protein.

Amino Acid Sequence↗
PubMed1996

Stroma-supported culture in childhood B-lineage acute lymphoblastic leukemia cells predicts treatment outcome.

We developed a stroma cell culture system that suppresses apoptosis of malignant cells from cases of B-lineage acute lymphoblastic leukemia. By multiparameter flow cytometric measurements of cell recovery after culture on stromal layers, we assessed the growth potential of 70 cases of newly diagnosed B-lineage acute lymphoblastic leukemia and related the findings of treatment outcome in a single program of chemotherapy. The numbers of leukemic cells recovered after 7 d of culture ranged from < 1 to 292% (median, 91%). The basis of poor cell recoveries from stromal layers appeared to be a propensity of the lymphoblasts to undergo apoptosis. The probability of event-free survival at 4 yr of follow-up was 50 +/- 9% (SE) among patients with higher cell recoveries ( > 91%), and 94 +/- 6% among those with reduced cell recoveries (+/- 91%; P = 0.0003). The prognostic value of leukemic cell recovery after culture exceeded estimates for all other recognized high-risk features and remained the most significant after adjustment with all competing covariates. Thus, the survival ability of leukemic cells on bone marrow-derived stromal layers reflects aggressiveness of the disease and is a powerful, independent predictor of treatment outcome in children with B-lineage acute lymphoblastic leukemia.

Analysis of Variance↗
PubMed1996

Dietary wheat gluten alleviates the elevation of serum transaminase activities in D-galactosamine-injected rats.

The effects of dietary protein on the elevation of activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in D-galactosamine-injected rats were investigated. The rats fed with experimental diets containing test protein sources for 2 weeks were injected with D-galactosamine (0.8 g.kg-1 body weight). The activities of AST and ALT in serum were assayed after 20 h. According to the results, these enzyme activities in the rats fed 40% casein diet were higher than those of 5, 10, or 20% casein groups. In the 40% gluten group, these enzyme activities were lower than in the 40% casein group. This difference was not considered to be caused by the deficit of L-lysine and L-threonine in gluten. The extent of the reduction of UTP and UDP-glucose in liver by D-galactosamine was almost the same in the 40% gluten and 40% casein groups. These results suggest that levels and quality of dietary protein affect the susceptibility of animals to the hepatotoxin D-galactosamine and dietary gluten was found to alleviate the elevation of serum transaminases in rats by the drug.

Alanine Transaminase↗
PubMed1996

Contact dermatitis caused by 2-HEMA and GM dentin primer solutions applied to guinea pigs and humans.

The purposes of this study were to examine whether 2-HEMA, GM, and methacrylic acid cause contact dermatitis, and to determine the optimum concentrations of these primers for sensitization and challenge in guinea pigs. A sensitizing concentration of 0.2% 2-HEMA resulted in strong rubefaction and several vesiculopapules in response to the challenge, and a sensitizing concentration of 0.5% GM produced strong rubefaction at 24 hours. We also observed the development of contact dermatitis on human brachia in a closed-patch test. Skin that was treated with both 2-HEMA and GM clearly showed the onset of rubefaction and itchiness. 2-HEMA caused sensitized delayed allergic reactions at all the concentrations tested.

Animals↗
PubMed1996

Evaluation of skin irritation and sensitization of two diol solutions used as experimental dentin primers in humans and guinea pigs.

The purpose of the present study was to evaluate the safety of ethylene glyco (EG) and 1,6-hexanediol (HD) solutions as experimental dentin primers when subjected to the guinea pig maximization test (GPMT), primary irritation test, cumulative skin irritation test and human patch test. No primary and cumulative skin irritation resulting from the use of 62.5% EG or 45% HD solutions was observed. In the case of GPMT, the animals sensitized with 2-hydroxyethyl methacrylate (2-HEMA) responded to 100% HD. 62.5% EG and 45% HD as dentin primers were safer than 2-HEMA such as a methacrylic primer.

Adult↗
PubMed1996

Contact angle of dentin bonding agents on the dentin surface.

Physical changes in the surface characteristics of dentin during bonding procedures were evaluated by measuring the contact angles of three standard liquids, to determine the surface free energy, and that of a commercially available dual cured dentin bonding agent dropped on the primed dentin surface. The commercial dentin bonding agent did not form a hemispherical shape on the ground dentin surface, probably because it penetrated into the smear layer due to the microcapillary effect. Not could the contact angle be measured on the dentin surfaces treated with any of four experimental primers, because the bonding agent rapidly spread over the primed dentin surface. It was concluded that the priming of the dentin surface after removing the smear layer served to increase the surface free energy and to improve the wettability of the bonding agent on the dentin.

Chemical Phenomena↗
PubMed1996

Human B-cell progenitors and bone marrow microenvironment.

Apoptosis of normal and leukemic immature B-cells in vitro is suppressed by contact with bone marrow-derived stromal layers. In stroma-supported cultures of immature B-cells, we found that ligation of CD38, a type II transmembrane protein, inhibited the cell growth and induced apoptosis. CD38 ligation also induced tyrosine phosphorylation and activation of intracellular substrates, including syk, phospholipase C-gamma, c-cbl, and phosphatidylinositol 3-kinase (PI 3-K). Wortmannin and LY294002, two potent inhibitors of PI 3K, rescued immature B cells from CD38-mediated growth suppression. In vitro culture of leukemic lymphoblasts may have potentially important clinical application. First, stroma-supported cultures of acute lymphoblastic leukemia (ALL) cells can determine the growth potential of leukemic cells. In a series of 70 children enrolled in a single program of chemotherapy, cell growth on stroma was a powerful and independent prognostic indicator. Second, a culture system capable of maintaining the majority of ALL blast cells at high levels of viability is also ideally suited for testing antileukemic drugs. Promising results were obtained with 2-chloro-deoxyadenosine and interleukin-4, leading to clinical trials of these two compounds in children with refractory ALL. In addition, we compared the direct antileukemic activities of dexamethasone and prednisolone and found that dexamethasone is five to six times more cytotoxic (on a molar basis) than prednisolone, in agreement with the anti-inflammatory activities of these drugs. This finding may serve to guide the selection of dexamethasone dosage in the treatment of ALL.

ADP-ribosyl Cyclase↗
PubMed1995

Molecular cloning of the complementary DNA for the mouse pyruvate kinase M-2 gene whose expression is dependent upon cell differentiation.

A cDNA encoding M2-type pyruvate kinase from mouse was cloned and its nucleotide sequence was determined. The cDNA encoded a protein containing 531 amino acids, the nucleotide and amino acid sequences of which were 93.2% and 98.1%, respectively, homologous to those of rat M2 pyruvate kinase. Expression of the pyruvate kinase in mouse embryonal carcinoma P19 cells altered according to differentiation stages; high at undifferentiated and low at differentiated stages.

Amino Acid Sequence↗
PubMed1995

Hypertensive intra-arterial chemotherapy for endometrial carcinoma assessed by transvaginal Doppler ultrasound and magnetic resonance imaging.

We examined the effectiveness of hypertensive intra-arterial chemotherapy for endometrial carcinoma using transvaginal Doppler ultrasound and magnetic resonance imaging. Angiotensin II, 100 mg cisplatin, and 40 mg doxorubicin were prescribed for 8 patients with endometrial carcinoma (3 stage Ia; 3 stage Ib; 2 stage II). The resistance index (RI) was obtained for intratumoral blood flow velocity waveforms by transvaginal Doppler ultrasound and changes in RI (delta RI: differences before and after chemotherapy) were calculated. The tumor volume (TV) was also evaluated, based on the T2-weighted image of magnetic resonance imaging (MRI). The decrease in tumor size [DR-T: (TV before chemotherapy--TV after chemotherapy)/TV before chemotherapy x 100] was determined. RI measurements did not correlate with TV, either before or after chemotherapy. The delta RI varied from 0.007 to 0.615 (mean: 0.207) and DR-T varied from 20.1% to 65.0% (mean: 45.5%). The correlation between delta RI and DR-T [DR-T = 23.5 + 167.2 (delta RI)-165.6 (delta RI)2; R2 = 0.772, p < 0.05] was significant. Therefore, we confirmed the effectiveness of hypertensive intra-arterial chemotherapy for endometrial carcinoma using both transvaginal Doppler ultrasound and MRI.

Adenocarcinoma↗
PubMed1995

A delayed hypersensitivity reaction to dentine primer in the guinea-pig.

OBJECTIVE: This study was undertaken to examine the possibility of a delayed hypersensitivity reaction or contact dermatitis occurring in the guinea-pig in response to methacrylate derivatives used as experimental dentine primers. METHODS: The dentine primers 2-HEMA, GM, MA and MMA were tested in a guinea-pig maximization test. RESULTS: All the dentine primers tested produced positive delayed hypersensitivity reactions in the guinea-pig. MMA produced the most severe reaction. CONCLUSION: It is concluded that in the clinical situation, clinicians and other members of the dental team should be aware of the need for careful handling of the dentine primers tested.

Animals↗