[Physiopathology of diabetes mellitus--insulin secretory dysfunction or resistance? 1) Secretory dysfunction].
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Animals↗
Biomedical subjects
Y Yamada
Publications and source records attributed to Y Yamada.
Neural cell response to multiple novel sites on laminin-1.
The basement membrane protein laminin-1 is a potent stimulator of neurite outgrowth for a variety of neuronal cell types. Previous studies have identified neurite outgrowth activity in several distinct regions of the laminin-1 molecule. In this study, 545 overlapping 12- to 14-mer synthetic peptides, corresponding to most of the amino acid sequence of the alpha1, beta1, and gamma1 chains of laminin-1, were screened for cell attachment and neurite outgrowth activity using primary cultures of mouse cerebellar granule neurons and two neuronal cell lines. We identified 48 peptides derived from novel regions of the laminin-1 molecule that were positive for neural cell adhesion activity. Only the cerebellar cells were found to have true neurite outgrowth activity with certain of the peptides, whereas some peptides induced short spike-like process with the cell lines. Although 23 of these peptides were active on all 3 cell types screened, 25 others showed cell-type specificity in their activity. These studies show that (1) there are multiple and distinct sites on laminin-1 for cell adhesion and neurite-like outgrowth and (2) that there are neural cell-type-specific active domains. The multiple active sites found explains, in part, the potent activity of laminin-1 on neurite outgrowth.
Amino Acid Sequence↗
Hyperfunction of neutrophils in a patient with BCR/ABL negative chronic myeloid leukemia: a case report with in vitro studies.
BACKGROUND: Among patients diagnosed with chronic myeloid leukemia (CML), a small percentage lack a BCR/ABL fusion gene, a landmark of CML. Their clinical features are distinct from patients with BCR/ABL positive CML, although to the authors' knowledge the pathogenesis to date has been unknown. METHODS: A 50-year-old female patient with BCR/ABL negative CML and multiple complications of Graves disease, Sweet syndrome, and a fatal pulmonary alveolar proteinosis (PAP) is described in the current study. To show a clonal origin of her myeloid cells, hypoxanthine phosphoribosyltransferase (HPRT) assay was applied. Because the patient developed a progressive and fatal neutrophilia, a screening of cell functions in neutrophilic lineage, including in vitro colony assay of her bone marrow cells and production of superoxide and interleukin-8 (IL-8) by blood neutrophils was performed. RESULTS: Southern blot analysis based on the polymorphism of the HPRT gene was compatible with monoclonality of her neutrophils. The patient had an increased amount of bone marrow granulocyte-macrophage progenitor cells, which formed colonies in response to a very low dose (0.1 ng/mL) of granulocyte-colony stimulating factor. In vitro production of superoxide and IL-8, which is an inducer of positive chemotaxis of neutrophils, by her peripheral neutrophils was markedly augmented. Her bronchoalveolar lavage fluid also contained a significant amount of IL-8 as well as an unusual infiltration of neutrophils. CONCLUSIONS: In the patient in the current study, hyperfunction of the neutrophils might have contributed to the onset of PAP as well as Sweet syndrome and to the pathogenesis of BCR/ABL negative CML.
Bone Marrow↗
Association of a Leu(10)-->Pro polymorphism of the transforming growth factor-beta1 with genetic susceptibility to osteoporosis and spinal osteoarthritis.
Osteoporosis and osteoarthritis each exhibit a strong genetic component. Although polymorphisms of a variety of genes have been associated with bone mineral density and genetic susceptibility to osteoporosis or to osteoarthritis, the genes responsible for these conditions have not been definitively identified. We have shown that a T(869)-->C polymorphism of the transforming growth factor-beta1 (TGF-beta1) gene, which results in a Leu-->Pro substitution at amino acid 10, is associated with bone mineral density in Japanese adolescents and postmenopausal women, with genetic susceptibility to osteoporosis or spinal osteoarthritis, and with the outcome of treatment for osteoporosis with active vitamin D. I here review our recent studies, which have provided insight into the function of TGF-beta1 as well as into the role of genetic factors in the development of osteoporosis and osteoarthritis.
Animals↗
Mitochondrial genotype associated with longevity and its inhibitory effect on mutagenesis.
Mitochondria are not only the major site of ATP production in cells but also an important source of reactive oxygen species (ROS) under certain pathological conditions. Because mitochondrial DNA (mtDNA) in the mitochondrial matrix is exposed to ROS that leak from the respiratory chain, this extranuclear genome is prone to mutations. Therefore, the mitochondrial genome is a rich source of single nucleotide polymorphisms (SNPs) and the functional significance of SNPs in the mitochondrial genome is comparable to that of SNPs in the entire nuclear genome. To demonstrate the contribution of mitochondrial SNPs to the susceptibility to adult-onset diseases, we analyzed the mtDNA from Japanese centenarians and identified a longevity-associated mitochondrial genotype, Mt5178A. Because this genotype was demonstrated to suppress the occurrence of mtDNA mutations in the oocytes, it also would seem to decelerate the accumulation of mtDNA mutations in the somatic cells with increasing age. This genotype is likely to confer resistance to adult-onset diseases by suppressing obesity and atherosclerosis.
Animals↗
Molecular characterization of the S-adenosyl-L-methionine:3'-hydroxy-N-methylcoclaurine 4'-O-methyltransferase involved in isoquinoline alkaloid biosynthesis in Coptis japonica.
S-adenosyl-L-methionine:3'-hydroxy-N-methylcoclaurine 4'-O-methyltransferase (4'-OMT) catalyzes the conversion of 3'-hydroxy-N-methylcoclaurine to reticuline, an important intermediate in synthesizing isoquinoline alkaloids. In an earlier step in the biosynthetic pathway to reticuline, another O-methyltransferase, S-adenosyl-L-methionine:norcoclaurine 6-O-methyltransferase (6-OMT), catalyzes methylation of the 6-hydroxyl group of norcoclaurine. We isolated two kinds of cDNA clones that correspond to the internal amino acid sequences of a 6-OMT/4'-OMT preparation from cultured Coptis japonica cells. Heterologously expressed proteins had 6-OMT or 4'-OMT activities, indicative that each cDNA encodes a different enzyme. 4'-OMT was purified using recombinant protein, and its enzymological properties were characterized. It had enzymological characteristics similar to those of 6-OMT; the active enzyme was the dimer of the subunit, no divalent cations were required for activity, and there was inhibition by Fe(2+), Cu(2+), Co(2+), Zn(2+), or Ni(2+), but none by the SH reagent. 4'-OMT clearly had different substrate specificity. It methylated (R,S)-6-O-methylnorlaudanosoline, as well as (R, S)-laudanosoline and (R,S)-norlaudanosoline. Laudanosoline, an N-methylated substrate, was a much better substrate for 4'-OMT than norlaudanosoline. 6-OMT methylated norlaudanosoline and laudanosoline equally. Further characterization of the substrate saturation and product inhibition kinetics indicated that 4'-OMT follows an ordered Bi Bi mechanism, whereas 6-OMT follows a Ping-Pong Bi Bi mechanism. The molecular evolution of these two related O-methyltransferases is discussed.
Alkaloids↗
Identification of a plausible biosynthetic enzyme for the IM-2-type autoregulator in Streptomyces antibioticus.
Virginiae butanolides (VBs) and IM-2 are members of Streptomyces hormones called 'butyrolactone autoregulators' which regulate the antibiotic production in Streptomyces species at nanomolar concentrations. Cell-free extract of a VB-A overproducer, Streptomyces antibioticus NF-18, is capable of catalyzing the final step of the autoregulator biosynthesis, namely, the NADPH-dependent reduction of 6-dehydroVB-A. However, physico-chemical analyses of the purified enzymatic products revealed that, in addition to the VB-type isomer [(2R,3R,6S)-enantiomer], IM-2-type isomers [(2R,3R, 6R)- and (2S,3S,6S)-enantiomers] were also produced from (+/-)-6-dehydroVB-A, suggesting the existence of several 6-dehydroVB-A reductases with respective stereoselectivities. The reductase activity of the crude extracts was separated into two activity peaks, peak I (major) and peak II (minor), by DEAE-5PW HPLC. Chiral HPLC analyses demonstrated that peak I enzyme and peak II enzyme catalyzed the production of (2R,3R,6S), (2R,3R,6R) and (2S,3S, 6S) isomers at ratios of 46:1:3.2 and 4.9:1:1.5, respectively, indicating clearly that S. antibioticus NF-18 possesses at least two 6-dehydroVB-A reductases: one much favored toward VB-A biosynthesis, the other with relaxed stereoselectivity capable of synthesizing both VB-type and IM-2-type autoregulators.
4-Butyrolactone↗
A role for hematopoietic stem cells in promoting angiogenesis.
Angiogenesis is an important event for embryonic organogenesis as well as for tissue repair in the adult. Here, we show that hematopoietic stem cells (HSCs) play important roles for angiogenesis during embryogenesis. To investigate the role of HSCs in endothelial cell (EC) development, we analyzed AML1-deficient embryos, which lack definitive hematopoiesis. These embryos showed defective angiogenesis in the head and pericardium. Para-aortic splanchnopleural (P-Sp) explant cultures on stromal cells (P-Sp culture) did not generate definitive hematopoietic cells and showed defective angiogenesis in the AML1 null embryo. Disrupted angiogenesis in P-Sp cultures from AML1 null embryos was rescued by addition of HSCs or angiopoietin-1 (Ang1). HSCs, which express Ang1, directly promoted migration of ECs in vivo and in vitro. These results indicate that HSCs are critical for angiogenesis.
Angiopoietin-1↗
Head movements and neck muscle activities associated with the jaw movement during mastication in the rabbit authors.
Rhythmical head movements and neck muscle activities associated with the masticatory jaw movement were investigated in rabbits. In natural mastication, head movements and neck muscle activities showed a rhythmical feature synchronized with jaw movement. During cortically induced rhythmical jaw movements, some neck muscle showed rhythmical activity induced by biting a wooden stick. Neck muscles may contribute to the rhythmical head movement after loading the tooth with food.
Animals↗
Effect of a long-lasting opioid receptor antagonist (naltrexone) on pulsatile LH release in early postpartum Holstein dairy cows.
The present trial was the first one to investigate the effect of an intravenous injection of naltrexone, an opioid receptor antagonist that has a longer duration of action than that of naloxone, on the LH pulse in early postpartum Holstein dairy cows. On Day 10 postpartum, blood samples were collected from cows at 10-min intervals for a period of 4 h before (pre-injection period) and a period of 5 h after (post-injection period) an intravenous injection of 10 mL of saline (Control Group, n=5) or 300 mg of naltrexone in 10 mL of saline (Naltrexone Group, n=5). The plasma LH level was assayed by double antibody radioimmunoassay. The number of LH peaks per 1 h, the mean LH level, and the amplitude of LH peaks were analyzed utilizing the Pulsar algorithm, and data were compared by repeated measures ANOVA. No differences were observed in the parameters of LH pulse in the pre-injection period between the Control and the Naltrexone Groups (P>0.10). In the Naltrexone Group, the number of LH peaks per 1 h and the mean LH level were significantly higher in the post-injection period than in the pre-injection period (0.85 +/- 0.29 vs. 1.24 +/- 0.17, P<0.05, and 1.81 +/- 0.70 vs. 2.47 +/- 0.92 ng/ml, P<0.05, respectively), but there was no significant increase in the amplitude of LH peaks (1.48 +/- 0.64 vs. 1.83 +/- 0.82 ng/ml, P>0.10). In contrast, all of the parameters of LH pulse remained unchanged in the Control Group (P>0.10). These results suggested that an intravenous injection of naltrexone activates the LH pulse.
Animals↗
Frequent beta-catenin gene mutations and accumulations of the protein in the putative preneoplastic lesions lacking macroscopic aberrant crypt foci appearance, in rat colon carcinogenesis.
Activating mutations in the beta-catenin gene is thought to be responsible for the excessive beta-catenin signaling involved in the majority of carcinogen-induced colonic carcinomas. To determine whether beta-catenin signaling is involved in the initial stage of colon carcinogenesis, mutational analysis of the gene and immunohistochemistry for beta-catenin protein were performed in the early appearing lesions, including aberrant crypt foci (ACF), of colonic mucosa in rats given azoxymethane. Male F344 rats received s.c. injections of azoxymethane at a dose of 15 mg/kg body weight, once weekly for 3 weeks, and they were sacrificed 10 weeks after the carcinogen treatment. The colonic mucosa was examined in en face preparations and in serial sections after the observation in whole mount preparations. Microscopical observations in the cross sections have shown two populations of histologically altered crypts. The first type had a macroscopic feature resembling ACF [histologically altered crypts with ACF appearance (HACAs)]. The second type of altered crypts did not have the ACF-like appearance and could not be clearly distinguished from adjacent normal crypts in whole mount preparations [histologically altered crypts with macroscopically normal-like appearance (HACNs)]. The beta-catenin gene mutations were recognized in 10 of 15 HACNs (67%) and 3 of 15 HACAs (20%). Frequent immunoreactivity of beta-catenin protein was seen in the cytoplasm of HACNs (13 of 15 cases), whereas apparent accumulation was not confirmed in any HACAs analyzed. These results suggest that (a) there are two types of putative preneoplastic lesions in cancer-predisposed colonic mucosa, and beta-catenin signaling may contribute to the initial stage of colon carcinogenesis; and (b) HACNs are more likely to be direct precursors of colon tumors than HACAs in the rat colon carcinogenesis.
Amino Acid Substitution↗
Association of a T29-->C polymorphism of the transforming growth factor-beta1 gene with genetic susceptibility to myocardial infarction in Japanese.
BACKGROUND: Transforming growth factor-beta (TGF-beta) is an important regulator of vascular remodeling and is involved in the pathogenesis of atherosclerosis. A T-->C transition at nucleotide 29 of the TGF-beta1 gene results in a Leu-->Pro substitution at amino acid 10 of the signal peptide. We have now examined a possible association of TGF-beta1 genotype with myocardial infarction (MI) in a Japanese population. METHODS AND RESULTS: TGF-beta1 genotype was determined in 315 Japanese patients (234 men and 81 women) with MI and 591 control subjects (289 men and 302 women). We found that age, body mass index, and incidence of habitual smoking, hypertension, diabetes mellitus, and hypercholesterolemia did not differ between the 2 groups for either men or women. Multivariable logistic regression analysis, however, demonstrated the frequency of the T allele to be significantly higher in male subjects with MI than in controls (TT + TC versus CC; P<0.0001, odds ratio 3.5, 95% CI 2.0 to 6.3). In contrast, the T allele was not associated with the prevalence of MI in women. In both male MI patients and controls, the serum concentration of TGF-beta1 was significantly higher in individuals with the CC genotype than in subjects with the TT or TC genotype. CONCLUSIONS: Findings suggest that the T allele at nucleotide 29 in the TGF-beta1 gene is a risk factor for genetic susceptibility to MI, at least in middle-aged Japanese men.
Aged↗
Cell adhesive sequences in mouse laminin beta1 chain.
Laminin-1, a major component of the basement membrane, consists of three different chains, alpha1, beta1, and gamma1. We sought to identify cell adhesive sequences from the mouse laminin beta1 chain by testing HT-1080 fibrosarcoma and B16-F10 melanoma cells for binding to 187 overlapping synthetic peptides which covered the entire chain. Fourteen peptides showed cell adhesive activities with either peptide-conjugated Sepharose beads or peptide-coated plates or both. Additional cells, including neuronal, endothelial, and salivary gland cells, showed biological responses in a cell type-specific manner. B-7, B-133, and B-160 showed the most potent cell attachment. Cell binding on three peptides (B-34, B-133, and B-160) was inhibited by EDTA. Cell adhesion to 11 of the 12 active peptides was inhibited to varying degrees by heparin. Of the 17 active peptides identified in the laminin beta1 chain in this and other studies, 8 are clustered on the amino terminal globular domain, suggesting a possible important role in cell binding for this domain that may be multifunctional. These data demonstrate that the laminin beta1 chain has multiple active sites for cell adhesion, some of which are cell-type specific.
Amino Acid Sequence↗
Time to recover from atrial hormonal, mechanical, and electrical dysfunction after successful electrical cardioversion of persistent atrial fibrillation.
Although transient atrial dysfunction has been reported after electrical cardioversion of atrial fibrillation (AF), the difference in the time to recover from the atrial hormonal, mechanical, and electrical dysfunction has not been described. Thus, we evaluated the time course of recovery from atrial hormonal, mechanical, and electrical dysfunction after cardioversion in patients with nonvalvular AF. We attempted electrical cardioversion in 87 consecutive patients with nonvalvular AF that had persisted for > or =6 months, and in 24 patients (28%) with maintained sinus rhythm for > or =6 months. To evaluate atrial hormonal, mechanical, and electrical dysfunction in these 24 patients, we measured plasma concentration of atrial natriuretic peptide, the atrial peak velocity in transmitral flow, and the ratio of peak systolic-to-diastolic pulmonary venous flow (S/D ratio) using echocardiography, and the duration and the root mean voltage for the terminal 20 ms (LP20) of the filtered P wave using P-wave signal-averaged electrocardiography. Atrial natriuretic peptide rapidly returned to baseline within 1 day after cardioversion, and maintained these levels for 6 months. Atrial peak velocity in transmitral flow and S/D ratio were significantly increased at 2 weeks, and continued to increase until 1 month, and then reached a plateau. The duration and LP20 began to recover only 6 months after cardioversion. One to 3 years after conversion, the duration and LP20 had nearly reached a plateau, but the latter value remained below normal. In patients with nonvalvular AF of prolonged duration, recovery from atrial electrical dysfunction after sinus conversion took much longer than that from either atrial hormonal or mechanical dysfunction.
Aged↗
Constitutive activation of transcription factor AP-1 in primary adult T-cell leukemia cells.
Human T-cell leukemia virus type-I (HTLV-I) is the etiologic agent of adult T-cell leukemia (ATL). This study examined the status of the oncogenic transcription factor AP-1 in leukemic cells freshly isolated from patients with ATL. Leukemic cells from peripheral blood of all patients with ATL exhibited constitutive AP-1 DNA binding activity, whereas mononuclear cells from normal individuals did not. In agreement with previous studies, HTLV-I transforming protein, Tax, was found to stimulate the DNA binding activity of AP-1 in a T-cell line. However, HTLV-I genes, including Tax, were not significantly expressed in leukemic cells freshly obtained from patients with ATL. Moreover, all T-cell lines derived from leukemic cells of patients with ATL also displayed constitutive AP-1 DNA binding activity, but expressed little Tax protein. Thus, leukemic cells of patients with ATL appear to have Tax-independent mechanisms that induce AP-1 activity, both in vivo and in vitro. In antibody supershift experiments, AP-1 in fresh leukemic cells and ATL-derived cell lines were found to contain JunD. Consistently, all primary ATL cells and ATL-derived cell lines expressed high levels of JunD messenger RNA. Our results suggest that AP-1 is activated in leukemic cells of patients with ATL through a Tax-independent mechanism and this may play a role in the deregulated phenotypes of ATL leukemic cells. (Blood. 2000;95:3915-3921)
Adult↗
The mode of actions of lysozyme as an immunoglobulin production stimulating factor.
As we demonstrated before, hen egg white lysozyme stimulates immunoglobulin production by a human-human hybridoma line, HB4C5 cells and human peripheral blood lymphocytes. Then, the mode of actions of lysozyme as an immunoglobulin production stimulating factor was investigated. The immunoglobulin production stimulating activity of lysozyme was inactivated by trypsin digestion, even though the enzymatic activity was completely preserved. This fact suggests that the immunoglobulin production stimulating effect of lysozyme is irrelevant to its enzymatic function. Furthermore, this means that the effect is a novel function of this enzyme. Lysozyme enhanced IgM production by transcription-suppressed HB4C5 cells treated with actinomycin D. However, the enzyme was ineffective to accelerate IgM production by translation-suppressed HB4C5 cells treated with cycloheximide or sodium fluoride. In addition, the intracellular IgM content of HB4C5 cells treated with monensin for suppression of the post-transcription activity was obviously increased by lysozyme, although the secretion of IgM was inhibited. These findings suggest that lysozyme accelerates the translation process to enhance immunoglobulin productivity.
Animals↗
Peri-operative blood lactate levels in recipients of living-related liver transplantation.
BACKGROUND: The role of changes in peri-operative blood lactate levels in recipients of living-related liver transplants has not yet been clarified. METHODS: Forty-three recipients were included in this study. Blood lactate, plasma total bilirubin, aminotransferase, body temperature, and gastric mucosal PCO2 levels were measured at six time points during surgery: just before the initiation of surgery, just after dissection of the hepatic vasculature, at the end of the anhepatic phase, and 30, 60, and 120 min after reperfusion. We calculated the rate of lactate accumulation during the pre-anhepatic and anhepatic phases and the elimination rate during reperfusion (neohepatic phase), and examined the correlation between these results and the clinical findings. RESULTS: The rate of lactate elimination during the neohepatic phase was correlated with the ratio of graft weight to standard liver volume (P<0.0001). There was also a significant correlation between the rate of lactate accumulation during the pre-anhepatic phase and the preoperative total bilirubin levels (P=0.0008). CONCLUSIONS: Each pre-anhepatic, anhepatic, and neohepatic phase had a characteristic blood lactate profile. The graft size strongly affected lactate levels during the early neohepatic phase.
Adult↗
Structure and activity of specific inhibitors of thymidine phosphorylase to potentiate the function of antitumor 2'-deoxyribonucleosides.
A new class of 5-halogenated pyrimidine analogs substituted at the 6-position was evaluated as competitive inhibitors of thymidine phosphorylase (TPase). The most potent member of the series was 5-chloro-6-(2-iminopyrrolidin-1-yl)methyl-2,4(1H,3H)-pyrimidine dio ne hydrochloride (TPI), which has an apparent K(i) value of 1.7 x 10(-8) M. TPI selectively inhibited the activity of TPase, but not that of uridine phosphorylase, thymidine kinase, orotate phosphoribosyltransferase, or dihydropyrimidine dehydrogenase. In vitro inhibition studies of TPI using a thymidine analogue, 5-trifluoromethyl-2'-deoxyuridine (F(3)dThd), as the substrate demonstrated that F(3)dThd phosphorolytic activity was inhibited markedly by TPI (1 x 10(-6) M) in extracts from the liver, small intestine, and tumors of humans, from the liver and small intestine of cynomolgus monkeys, and from the liver of rodents, but not from the liver or small intestine of dogs or the small intestine of rodents, suggesting that the distribution of TPase differs between humans and animal species, and that TPI could contribute to the modulation of TPase in humans. When F(3)dThd or 5-iodo-2'-deoxyuridine (IdUrd) was coadministered to mice with TPI at a molar ratio of 1:1, the blood levels of F(3)dThd (or IdUrd) were about 2-fold higher than when F(3)dThd (or IdUrd) was administered alone. In monkeys, the maximum concentration (C(max)) and the area under the concentration-time curve (AUC) after oral F(3)dThd alone were 0.23 microg/mL and 0.28 microg. hr/mL, respectively, but markedly increased to 15.18 microg/mL (approximately 70-fold) and 28.47 microg. hr/mL (approximately 100-fold), respectively, when combined with equimolar TPI. Combined oral administration of TPI significantly potentiated the antitumor activity of F(3)dThd on AZ-521 human stomach cancer xenografts in nude mice. In conclusion, TPI may contribute not only to inhibition of TPase-mediated biological functions but also to potentiation of the biological activity of various 2'-deoxyuridine and thymidine derivatives by combining with them.
Administration, Oral↗