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Biomedical subjects

M Goto

Publications and source records attributed to M Goto.

At least 217 records · Page 12Linked to original sources
PubMed1999

High mobility group-like protein in bovine milk stimulates the proliferation of osteoblastic MC3T3-E1 cells.

The active component in bovine milk on the proliferation of osteoblastic MC3T3-E1 cells was purified and identified. Growth-promoting activity was measured by [(3)H]thymidine incorporation on the cell. The molecular weight of the purified protein was 10 kDa. The amino-terminal sequence of this 10-kDa protein was identical to bovine high mobility group protein (HMG) 1. This 10-kDa protein is suggested to be a basic protein and to have an HMG box, a consensus sequence motif among the HMG family. From these results, we named this protein HMG-like protein. HMG is a ubiquitous nonhistone component of chromatin and considered to be implicated in DNA replication. We found this protein in milk, and it showed a growth-promoting activity. We propose the possibility that HMG-like protein existed in milk and plays an important role for neonate in bone formation by activating osteoblasts.

Amino Acid Sequence↗
PubMed1999

Prolonged diastolic time fraction protects myocardial perfusion when coronary blood flow is reduced.

BACKGROUND: Because coronary blood flow is impeded during systole, the duration of diastole is an important determinant of myocardial perfusion. The aim of this study was to show that coronary flow modulates the duration of diastole at constant heart rate. METHODS AND RESULTS: In anesthetized, open-chest dogs, diastolic time fraction (DTF) increased significantly when coronary flow was reduced by lowering perfusion pressure from 100 to 70, 55, and 40 mm Hg. On average, DTF increased from 0.47+/-0.04 to 0.55+/-0.03 after a pressure step from 100 to 40 mm Hg in control, from 0.42+/-0.04 to 0.47+/-0.04 after administration of adenosine, and from 0.46+/-0.07 to 0.55+/-0.06 after L-NMMA (mean+/-SD, 6 dogs for control and adenosine, 4 dogs for L-NMMA, all P<0.05). Flow normalized to its value at full dilation and pressure of 90 mm Hg (375+/-25 mL/min) increased during the period of reduced pressure at 40 mm Hg; control, from 0.005+/-63 (2 seconds after pressure step) to 0.09+/-0.06 (15 seconds after pressure step); with adenosine, from 0.19+/-0.06 to 0. 22+/-0.06; and with L-NMMA, from 0.013+/-0.007 to 0.12+/-0.02 (all P<0.05). The increase in DTF at low pressure may be explained by a decrease in interstitial volume at low pressure, which either decreases the preload of the myocytes or reduces the buffer capacity for ions determining repolarization, thereby causing an earlier onset of relaxation. CONCLUSIONS: Because the largest increase in DTF occurs at pressures below the autoregulatory range when blood flow to the subendocardium is closely related to DTF, modulation of DTF by coronary blood flow can provide an important regulatory mechanism to match supply and demand of the myocardium when vasodilatory reserve is exhausted.

Adenosine↗
PubMed1999

Werner syndrome helicase contains a 5'-->3' exonuclease activity that digests DNA and RNA strands in DNA/DNA and RNA/DNA duplexes dependent on unwinding.

We show that WRN helicase contains a unique 5'-->3' exonuclease activity in the N-terminal region. Adeletion mutant lacking 231 N-terminal amino acid residues, made in a baculovirus system, did nothave this activity, while it showed ATPase and DNA helicase activities. This exonuclease activity was co-precipitated with the helicase activity using monoclonal antibodies specific to WRN helicase, indicating that it is an integral component with WRN helicase. The exonuclease in WRN helicase does not digest free single-stranded DNA or RNA, but it digests a strand in the duplex DNA or an RNA strand in a RNA/DNA heteroduplex in a 5'-->3' direction dependent on duplex unwinding. The digestion products were identified as 5'-mononucleotides. Our data show that WRN helicase needs a single-stranded 3' overhang region for efficient binding and unwinding of duplex molecules, while blunt-ended or 5' overhang duplex molecules were hardly unwound. These findings suggest that the WRN helicase and integral 5'-->3' exonuclease activities are involved in preventing a hyper-recombination by resolving entangled structures of DNA and RNA/DNA heteroduplexes that may be generated during rep-lication, repair and/or transcription.

Animals↗
PubMed1999

Connections of the precommissural nucleus.

The connections of the precomissural nucleus (PRC) have been examined with anterograde and retrograde axonal tracing methods in the rat. Experiments with cholera toxin B subunit (CTb) indicate that the PRC shares a number of common afferent sources with the dorsolateral periaqueductal gray (PAG). Thus, we have shown that the nucleus receives substantial inputs from the prefrontal cortex, specific domains of the rostral part of the lateral septal nucleus, rostral zona incerta, perifornical region, anterior hypothalamic nucleus, ventromedial hypothalamic nucleus, dorsal premammillary nucleus, medial regions of the intermediate and deep layers of the superior colliculus, and cuneiform nucleus. Moreover, the PRC also receives inputs from several PAG regions and from neural sites involved in the control of attentive or motivational state, including the laterodorsal tegemental nucleus and the ventral tegmental area. The efferent projections of the PRC were analyzed by using the Phaseolus vulgaris-leucoagglutinin (PHA-L) method. Notably, the PRC presents a projection pattern that resembles in many ways the pattern described previously for the rostral dorsolateral PAG in addition to projections to a number of targets that also are innervated by neighboring pretectal nuclei, including the rostrodorsomedial part of the lateral dorsal thalamic nucleus, the ventral part of the lateral geniculate complex, the medial pretectal nucleus, the nucleus of the posterior commissure, and the ventrolateral part of the subcuneiform reticular nucleus. Overall, the results suggest that the PRC might be viewed as a rostral component of the PAG, and the possible functional significance of the nucleus is discussed in terms of its connections.

Animals↗
PubMed1999

Polymorphism in RANTES chemokine promoter affects HIV-1 disease progression.

RANTES (regulated on activation normal T cell expressed and secreted) is one of the natural ligands for the chemokine receptor CCR5 and potently suppresses in vitro replication of the R5 strains of HIV-1, which use CCR5 as a coreceptor. Previous studies showed that peripheral blood mononuclear cells or CD4(+) lymphocytes obtained from different individuals had wide variations in their ability to secrete RANTES. These findings prompted us to analyze the upstream noncoding region of the RANTES gene, which contains cis-acting elements involved in RANTES promoter activity, in 272 HIV-1-infected and 193 non-HIV-1-infected individuals in Japan. Our results showed that there were two polymorphic positions, one of which was associated with reduced CD4(+) lymphocyte depletion rates during untreated periods in HIV-1-infected individuals. This mutation, RANTES-28G, occurred at an allele frequency of approximately 17% in the non-HIV-1-infected Japanese population and exerted no influence on the incidence of HIV-1 infection. Functional analyses of RANTES promoter activity indicated that the RANTES-28G mutation increases transcription of the RANTES gene. Taken together, these data suggest that the RANTES-28G mutation increases RANTES expression in HIV-1-infected individuals and thus delays the progression of the HIV-1 disease.

Base Sequence↗
PubMed1999

Unusual features of thyroid carcinomas in Japanese patients with Werner syndrome and possible genotype-phenotype relations to cell type and race.

BACKGROUND: Werner syndrome (WS), an autosomal recessive disease characterized by premature aging, has a high frequency of association with six rare neoplasms in Japanese patients, and only four of these neoplasms also occur excessively in whites. Several differ from what is usual in their epidemiology and/or histology. Described in this article are peculiarities in the occurrences of follicular and papillary thyroid carcinomas among Japanese patients and the possible genotype-phenotype relations pertaining to cell types and the absence of excess thyroid carcinoma occurrence in whites with WS. METHODS: Epidemiologic features of 23 histologically diagnosed thyroid carcinomas from a series of 150 cancers in 845 Japanese patients with WS were compared with those of 19,446 tumors in a Japanese national registry of thyroid carcinomas from 1977-1991. Germline mutations had been determined by molecular studies of peripheral blood. RESULTS: The average age of patients with thyroid carcinoma was 39 years for those with WS and 49 years for the registry patients. The female-to-male ratios were 2.3:1 and 6.6:1, respectively. The rates of occurrence of papillary, follicular, and anaplastic carcinomas were 35%, 48%, and 13% for Japanese patients with WS and 78%, 14%, and 2% in the general Japanese population. All four cases of follicular carcinoma had germline mutations of the WS gene in the C-terminal region, and the germline mutation for the only papillary carcinoma was in the N-terminal region. CONCLUSIONS: This study suggests two possible WS genotype-phenotype relations. One concerns thyroid carcinoma histology; the other concerns frequent mutations that occur in the C-terminal region in Japanese patients, but not in white patients, with WS. These may account for the excess thyroid carcinoma occurrence among Japanese.

Adenocarcinoma, Follicular↗
PubMed1999

Enhanced shear-induced platelet aggregation in acute myocardial infarction.

BACKGROUND: Experiments under controlled flow conditions indicate that the binding of von Willebrand factor (vWF) to platelet glycoprotein (GP) Ibalpha and integrin alphaIIbbeta3 (GP IIb/IIIa complex) is crucial for aggregation at elevated shear rates. We have tested how the plasma of patients with acute myocardial infarction affects this process. METHODS AND RESULTS: Citrated plasma was obtained from 18 patients with acute myocardial infarction within 6 hours from the onset of symptoms and from 26 control subjects with chest pain syndrome without evidence of ischemia. Aggregation of normal platelets at high shear rates was significantly greater in the presence of patient than control plasma and was inhibited by both anti-GP Ibalpha and anti-alphaIIbbeta3 monoclonal antibodies. The observed values (mean+/-SD) were 47.6+/-17.8% versus 30.1+/-9.9% at 10 800 s-1 (P<0.01) and 32.9+/-14.1% versus 17.5+/-9.5% at 7200 s-1 (P<0.01), respectively, and were positively correlated with plasma vWF antigen levels and ristocetin cofactor activities. In contrast, at the lower shear rate of 1200 s-1, aggregation was similar in the presence of control or patient plasma and was not inhibited by the anti-GP Ibalpha antibody. Both vWF antigen and platelet aggregation decreased 2 weeks after the onset of myocardial infarction. CONCLUSIONS: Shear-induced platelet aggregation is enhanced in plasma in the presence of acute myocardial infarction, apparently as a result of increased vWF concentration. This may contribute to the onset of acute coronary artery thrombosis and early reocclusion after reperfusion treatment.

Adult↗
PubMed1999

Fos-like immunoreactivity in the periaqueductal gray of rats exposed to a natural predator.

In the present study we examined, in rats exposed to a predator (cat), the distribution of neurons expressing Fos along the continuum formed by the central gray surrounding the caudal pole of the third ventricle and the periaqueductal gray (PAG). After the predatory encounter, a distinct cluster of Fos-immunoreactive cells was observed in the precommissural nucleus. In the rostral two-thirds of the PAG, Fos expression was mostly seen in the dorsomedial and dorsolateral regions. In contrast, at caudal levels of the PAG, most of the Fos-labelled neurons were distributed in the lateral and ventrolateral PAG. These results are discussed and compared with the pattern of the PAG activation after fear conditioned to a context or elicited by aversive foot shock.

Animals↗
PubMed1999

Reconsideration of senescence, immortalization and telomere maintenance of Epstein-Barr virus-transformed human B-lymphoblastoid cell lines.

We review recent data on senescence and immortalization of human B-lymphoblastoid cell lines (LCLs) transformed by the Epstein-Barr virus (EBV). Although EBV-transformed LCLs are generally believed to be immortalized, a series of recent studies, including ours, provided strong evidence that they are mostly mortal and have non-malignant properties, except for a small proportion of LCLs that are immortalized by developing a strong telomerase activity. A large proportion of mortal LCLs have exceptionally long lifespans. Some of them have a lifespan over 150 population-doubling levels, keeping a relatively constant telomere length in spite of the absence of a detectable telomerase activity, suggesting that they maintain telomeres by a pathway other than that using telomerase. Here we propose a model of an alternative pathway to maintain telomeres of such long-lived mortal LCLs by exploiting extra-chromosomal telomere repeat DNA, which was recently found by us.

B-Lymphocytes↗
PubMed1999

Detection by epitope-defined monoclonal antibodies of Werner DNA helicases in the nucleoplasm and their upregulation by cell transformation and immortalization.

We prepared several monoclonal antibodies (mAbs) specific for the NH2- and COOH-terminal regions of the DNA helicase (WRN helicase) responsible for Werner's syndrome known as a premature aging disease. With these antibodies, we detected by immunoblot analysis the endogenous WRN helicase of a relative mass of 180 kD in several lines of cultured cells, but not in patient cells with a defined mutation. Immunocytochemical staining of proliferating fibroblasts and tumor cells showed that the major part of WRN helicase is in the nucleoplasm and not in the nucleolus. Similar experiments with a rat mAb specific to the mouse homologue of human WRN helicase yielded an identical conclusion. Although this nucleoplasmic staining was evident in cells in interphase, the condensed chromatin structure in metaphase was not stained by the same mAbs, suggesting that WRN helicases exist perhaps in a soluble form or bound to the unfolded chromatin structure. From quantitative immunoblot analysis, higher levels of WRN helicase were observed in all transformed cells and tumor cells examined than those of normal cells. The expression of WRN helicase was enhanced consistently in fibroblasts and B-lymphoblastoid cells by transformation with SV-40 and Epstein-Barr virus, respectively, suggesting that rapidly proliferating cells require a high copy numbers of WRN helicase.

Animals↗
PubMed1999

Functional analysis of HO gene in delayed homothallism in Saccharomyces cerevisiae wy2.

Saccharomyces cerevisiae wy2 exhibits a novel life cycle, with delayed homothallism caused by a defective HO gene. In this strain, gradual diploidization occurs during successive subcultures. Three amino acids of wy2 HO were different from those of wild-type (wt) HO, which included a nonsense mutation (TAG) from Trp-292 and two amino acid changes of His-475 to Leu and Glu-530 to Lys. The ho gene of heterothallic strain CG379 was also sequenced in this study. Four amino acids of ho were different from those of HO. Among different amino acids in wy2 HO and ho, the alteration of His-475 to Leu was common between them. His-475 in HO was previously suggested to be involved in the DNA binding. We constructed a variety of chimeric HO genes by exchanging the corresponding restriction fragments generated from the wt HO, wy2 HO and ho genes. These results and the site-directed mutagenesis studies allowed us to draw the following conclusions: (a) Gly-223 is essential for HO activity; (b) mutation of His-475 to Leu significantly reduces the HO activity; (c) amber mutation (TAG) in wy2 HO car be suppressed inefficiently.

Amino Acid Sequence↗
PubMed1999

Involvement of NF-kappaB p50/p65 heterodimer in activation of the human pro-interleukin-1beta gene at two subregions of the upstream enhancer element.

A region between-3134 and -2729 bp upstream from the transcription site of the human pro-interleukin 1beta (proIL-1beta) gene was identified as an LPS-responsive enhancer element. In this study, the influence of the sequences located between -3134 and -2987 on the transcriptional activity of the proIL-1beta gene in LPS-stimulated Raw 264.7 cells was examined in detail. The results obtained by transient transfection of fos -CAT constructs that contained serial 5'-deletion mutations showed that the region between -3134 and -3059 appears to be required for the induction of transcription by LPS. Gel shift assay studies with synthetic oligonucleotides corresponding to partial sequences of the latter region and nuclear extracts from stimulated cells revealed specific protein binding sites between -3110 and -3090 and between -3079 and -3059. These specific bindings were time and LPS dose dependent. The results of supershift analysis using specific antibodies against transcription factors suggested that both binding complexes contained the NF-kappaB components p50 and p65, and did not contain other NF-kappaB proteins (p52, c-Rel, Rel B), AP-1 proteins (c-Fos, C-Jun), CREB or C/EBPbeta (NF-IL6). Mutation of either of the putative NF-kappaB-binding sites in the enhancer element decreased the LPS-stimulated transcriptional activity. These data indicated that two NF-kappaB-binding sites, which are located between -3134 and -3059, are critical for the activation of proIL-1beta gene transcription.

Animals↗
PubMed1999

Flow dependence and time constant of the change in nitric oxide concentration measured in the vascular media.

It has been considered that the concentration of endothelium-derived nitric oxide (NO) in the arterial vascular wall changes in response to flow-induced shear stress. In the present study, using an NO-sensitive electrode, the aim was to directly evaluate the relationship between perfusion rate and NO concentration in the arterial vascular wall. The NO microelectrode (diameter: 100 microns) was inserted into the vascular media of isolated canine femoral arteries, and the vessel was perfused with a Krebs-Henseleit buffer solution. A flow-related change in NO concentration in the vascular media was then evaluated by changing perfusion rate. NO concentration attained a peak value with a first-order time delay by a stepwise increase in perfusion rate, and the peak-level NO concentration was linearly correlated with perfusion rate in each vessel (10-154 pA at 2.1-72.3 ml min-1; n = 7, r2 = 0.89-0.99, p < 0.03). The average time constant for an increase in NO current with a stepwise increase in perfusion rate was 24 +/- 3 s (n = 5). NO production was increased by perfusing a solution containing 1 mmol l-1 L-arginine and was attenuated by 100 mumol l-1 NG-nitro-L-arginine, indicating the intactness of the endothelium, proper insertion of the NO electrode and selective detection of NO by the electrode. It is concluded that the NO microelectrode is applicable to NO measurement in the vascular media where NO controls vascular tone and that the concentration of NO in the arterial vascular media changes with perfusion rate in a rate-dependent manner as well as with a time constant of about 24 s for a stepwise increase in flow.

Animals↗
PubMed1999

Biochemical effect of intra-articular injections of high molecular weight hyaluronate in rheumatoid arthritis patients.

OBJECTIVE: The purpose of this study was to analyze the biochemical characteristics of synovial fluids after treatment of patients with rheumatoid arthritis (RA) with intra-articularly injected hyaluronate (HA). TREATMENT: In a double-blind study, 13 patients received intra-articular injections of 1% HA in phosphate buffered saline (PBS) while 13 other patients were injected 0.01% HA in PBS, as the control group. Injections were administered once a week for five weeks. METHODS: Clinical efficacy and characteristics of synovial fluid were compared between groups. RESULTS: Significant clinical improvement was observed in the HA-treated group compared to the control group. The viscosity of retained synovial fluid increased. Stringing and HA concentration increased significantly whereas the concentrations of protein and chondroitin sulfate 4 and 6 decreased significantly. The HA molecular weight remained the same in both groups. CONCLUSION: Intra-articular HA injection altered the properties of synovial fluid and proved efficacious for patients with RA.

Arthritis, Rheumatoid↗
PubMed1999

Immunological diagnosis of Werner syndrome by down-regulated and truncated gene products.

Although immunological methods are widely used to diagnose various infectious diseases, they have rarely been employed to detect genetic diseases. In this study, we have established an immunoblot analysis system for the diagnosis of Werner syndrome (WS), a recessive genetic disorder causing premature aging and an enhanced risk of rare cancers. The method uses an immunoblot technique with specific monoclonal antibodies to WS gene product, and B-lymphoblastoid cell lines (LCLs) transformed by Epstein-Barr virus; these cell lines express an increased level of normal WS gene product DNA helicase. The method clearly distinguishes normal from patient LCLs containing any of the mutation types found so far in Japan, primarily because of the drastically reduced levels of mutated gene products, and secondarily because of the truncated product sizes. A comparison of this immunological diagnosis with the symptom-based clinical diagnosis has narrowed down the criteria of symptoms essential for WS diagnosis. This procedure is compatible with, and has some advantage over, the genetic method, because WS patients can be diagnosed without determining the mutated gene sequences. The method exemplified in WS may also be applied to detect some other genetic diseases.

Adult↗
PubMed1999

Endothelium-derived nitric oxide enhances the effect of intraaortic balloon pumping on diastolic coronary flow.

BACKGROUND: High shear rate with pulsation is one of the major stimuli for the release of endothelium-derived nitric oxide leading to coronary arteriolar dilation. Intraaortic balloon pumping mechanically enhances shear rate and diastolic-to-systolic flow oscillation. We aimed to evaluate whether or not coronary blood flow augmentation during intraaortic balloon pumping is mediated by coronary arteriolar dilation through endothelium-derived nitric oxide release. METHODS: Using a charge-coupled device intravital videomicroscope, we observed epicardial coronary arterioles (40 to 220 microm in diameter) in anesthetized open-chest dogs (n = 10) during 2:1 mode of intraaortic balloon pumping. Endothelium-derived nitric oxide-mediated vasodilatory effects of intraaortic balloon pumping were evaluated by comparing end-diastolic arteriolar diameters between the coupled beats of on and off intraaortic balloon pumping before and after intracoronary endothelium-derived nitric oxide synthesis inhibition with Nomega-nitro-L-arginine (L-NNA, 2 micromol/min) administration. RESULTS: Intraaortic balloon pumping increased coronary arteriolar diameters and coronary blood flow by 11.4%+/-1.8% (p < 0.0001) and 33.4%+/-4.1% (p < 0.001), respectively. Vasodilation was greater in small arterioles (<110 microm; 15.4%+/-2.2%) than in large arterioles (> or =110 microm; 4.2%+/-1.2%, p < 0.0001). L-NNA attenuated the intraaortic balloon pumping-induced vasodilation and augmentation of coronary blood flow to 4.6%+/-1.0% (p < 0.001) and to 20.8%+/-2.1%, (p < 0.05), respectively. Attenuation of vasodilatory effect by L-NNA was observed mainly in small arterioles (from 15.4%+/-2.2% to 5.9%+/-1.2%). CONCLUSIONS: Intraaortic balloon pumping augmented coronary blood flow by dilating coronary arterioles in diastole, more significantly in small arterioles than in large arterioles. Endothelium-derived nitric oxide inhibition markedly attenuated these effects. We conclude that, in a canine model, endothelium-derived nitric oxide contributes to mechanical enhancement of the coronary blood flow with diastolic arteriolar vasodilation during intraaortic balloon pumping.

Acetylcholine↗
PubMed1999

Tumor necrosis factor-alpha alters glucose metabolism in suckling rats.

Tumor necrosis factor-alpha (TNF-alpha), an important mediator of endotoxic shock, induces hypoglycemia and shock in adult animals. Indomethacin ameliorates TNF-alpha-induced hypoglycemia in the adult. However, effects of TNF-alpha on glucose metabolism in the newborn have not been well documented. The present study showed that in 10-day-old rats injected with TNF-alpha (4.5 x 10(7) U/kg, intraperitoneally) the plasma glucose concentration increased from 4.1 +/- 0.3 mmol/L to 6.9 +/- 0.5 mmol/L (P < .05) at 2 hours and subsequently decreased to 1.4 +/- 0.5 mmol/L (P < .05) at 6 hours, although plasma lactate concentration increased from 1.1 +/- 0.1 mmol/L to 5.5 +/- 0.3 mmol/L (P < .05) at 6 hours. Plasma insulin concentration remained unchanged throughout the experiment. TNF-alpha increased GLUT 1 messenger RNA (mRNA) abundance in the brain, liver, muscle, and fatty tissue (P < .05). Glucose uptake increased in association with the increase of GLUT1 mRNA abundance. TNF-alpha decreased mRNA abundance of GLUT 2 and phosphoenolpyruvate carboxykinase (PEPCK) in liver, suggesting decreased gluconeogenesis. Indomethacin (1.5 mg/kg 20 minutes before TNF-alpha, intraperitoneally) attenuated the hypoglycemia, the lactacidemia, and the increase of GLUT1 mRNA abundance and glucose uptake. Indomethacin attenuated the decrease of PEPCK mRNA abundance. We concluded that TNF-alpha induced hypoglycemia, increasing GLUT1 mRNA abundance and glucose uptake and decreasing PEPCK mRNA abundance in 10-day-old rats. Indomethacin attenuated the TNF-alpha-induced glucose dyshomeostasis.

Animals↗