Biomedical subjects

N Satoh

Publications and source records attributed to N Satoh.

At least 37 records · Page 2Linked to original sources

PubMed2001

Quantitative PCR determination of human cytomegalovirus in blood cells.

We evaluated a rapid and sensitive method to determine human cytomegalovirus (CMV) DNA levels in blood cells using a quantitative polymerase chain reaction (PCR) technique. This method is based on real-time detection of PCR using a dual fluorescence-labeled probe and a sequence detector. Ten copies of CMV DNA were detected, when 1 microg of DNA from blood samples was used with this method, and a good correlation was obtained between increased concentrations of copy numbers calculated and measured copy numbers of CMV DNA (r = 0.999). Forty normal subjects exhibited no copies of CMV DNA. On the other hand, a 6-month-old girl tested positive for increased levels 4 weeks after liver transplant. This method is simple, accurate, and sensitive for the quantitative detection of CMV DNA in vivo, indicating possible applications for the diagnosis and monitoring of CMV infection.

Cytomegalovirus↗

PubMed2001

Isolation and characterization of genes that are expressed during Ciona intestinalis metamorphosis.

In ascidians, the events of metamorphosis transform the non-feeding, mobile tadpole larva into a filter-feeding, fixed juvenile, and the process involves rearrangements of cells, two organs and physiological changes. Differential screening was used to isolate two genes that are not expressed in swimming larvae but are expressed immediately after the initiation of metamorphosis in Ciona intestinalis. One of the genes, Ci-meta1, encodes a polypeptide with a putative secretion signal sequence, 6 epidermal growth factor (EGF)-like repeats and 13 calcium-binding EGF-like repeats. The gene begins to be expressed immediately after the beginning of metamorphosis in the adhesive organ and is likely to be associated with the signal response for metamorphosis. Another gene named Ci-meta2 encodes a protein with a putative secretion signal and three thrombospondin type-1 repeats. Ci-meta2 gene expression begins at the larval stage and is upregulated in the metamorphosing juveniles. Ci-meta2 expression is found in three regions; the adhesive organ which is also associated with settlement, the neck region between the trunk and the tail of the larva which is associated with tail resorption, and dorsal regions of the trunk which correspond to the location of the siphon primordium. This gene may be involved in the dynamic arrangement of cells during ascidian metamorphosis.

Amino Acid Sequence↗

PubMed2001

Brachyury (T) gene expression and notochord development in Oikopleura longicauda (Appendicularia, Urochordata).

Appendicularia (Larvacea) is a subgroup of Urochordata (Tunicata) comprised of holoplanktonic organisms that retain their tailed architecture throughout their life history, while other tunicates, including ascidians and doliolids, resorb the tail after metamorphosis. In order to investigate the characteristics of the appendicularian unresorbed notochord, we isolated a partial genomic clone and a full-length cDNA sequence homologous to the mouse Brachyury (T) gene from the appendicularian Oikopleura longicauda. Brachyury is known to be predominantly expressed in the notochord cells and plays an important role in their differentiation in other chordates. While phylogenetic analysis robustly supports the orthology of the isolated Brachyury gene, the exon-intron organization found in the genomic clone was distinct from that well-conserved among other T-box genes. In addition to a detailed observation of notochord development in living specimens, whole-mount double in situ hybridization was carried out using a Brachyury probe along with a muscle actin probe. The Brachyury transcripts were found in the notochord of the tailbud embryos and persisted into later stages. The present study highlights characteristics of notochord development in the appendicularian. Furthermore, these results provide basic knowledge for comprehensive understanding of the cellular- and molecular-based mechanisms needed to build the characteristic cytoarchitecture of notochord that varies among tunicate species.

Amino Acid Sequence↗

PubMed2001

Genetic relatedness and variability in inbred and wild populations of the solitary ascidian Ciona intestinalis revealed by arbitrarily primed polymerase chain reaction.

As the first step in the establishment of inbred Ciona intestinalis strains, the genetic backgrounds of several local populations were evaluated on the basis of comparing 313 random amplified polymorphic DNA (RAPD) loci. Cluster analyses of individuals indicated that this species has local genetic characteristics, although various genetic distances among the populations were relatively low. The bulked RAPD analyses revealed that populations from Torihama and from Onagawa were the most distantly related among the 7 populations examined, suggesting that these two populations are the best candidates for outbreeding. Successive inbreeding in the laboratory was achieved using the Onagawa population. Although the genetic similarity of the F(4) progeny became distinctly higher than that of natural populations, F(5) progeny did not survive, presumably owing to homozygous lethal alleles.

Journal Article↗

PubMed2001

Optimal stimulus level conditions for measurements of distortion product otoacoustic emissions.

OBJECTIVE: Distortion product otoacoustic emission (DPOAE) is a tool for an objective examination of the cochlea function. While the clinical application of DPOEA test is in progress, the measurements vary depending on the stimulus conditions. We aimed to determine the most appropriate stimulus level in the clinical application of DPOAE test. METHODS: Ninety-seven normal hearing ears and 80 hearing-impaired ears (total 177) were subjected to this study. Two levels of stimulations (L1 and L2) were applied as follows: L1 = L2 = 70 dB; L1 = L2 = 60 dB and L1 = 60/L2 = 50 dB, and DP level was measured at each stimulation, and compared with hearing level. RESULTS: DP level was highest at L1 = L2 = 70 dB. Normal hearing ears and hearing-impaired ears were well differentiated at L1 = L2 = 60 dB. CONCLUSION: In clinical application of DPOAE test, DP levels should be measured at the stimulus level most appropriate for the purposes.

Acoustic Stimulation↗

PubMed2001

Sensorineural hearing loss induced by radiation as a late effect: five cases followed by audiogram.

OBJECTIVE: We studied the progression of the late radiation-induced sensorineural hearing loss (SNHL) to discuss the pathological mechanism responsible for the progression with referring to past reports. METHODS: Five cases were selected among the SNHL cases diagnosed at the Department of Otolaryngology. Hokkaido University. All the cases were followed up with audiograms. RESULTS: All of the five cases showed gradual progression of SNHL, which developed mostly 1 2 years after irradiation for brain tumors. Two of them showed rapid progression from time to time with sudden onset in their clinical courses. All the patients were resistant to any medication such as steroid, vitamin B12 or cerebral circulation activators. CONCLUSION: Two patterns of progressions of radiation-induced hearing loss were observed. Both of them were considered to be explainable by ischemic changes of the vessels as reported earlier. Since there is no effective treatment for radiation-induced SNHL, it is most important to enlighten clinicians in general on this disease.

Adult↗

PubMed2001

Pulmonary artery reflection for differentially diagnosing primary pulmonary hypertension and chronic pulmonary thromboembolism.

OBJECTIVES: The purpose of this investigation was to differentiate chronic pulmonary thromboembolism (CPTE) from primary pulmonary hypertension (PPH) by means of the indexes of pulmonary arterial reflection. BACKGROUND: These differences in the primary lesions would make pulmonary artery reflection occur earlier in CPTE than in PPH. Although the analysis of pulsatility of pulmonary arterial pressure is useful in the differential diagnosis of PPH and CPTE, it is not known whether the analysis of pulmonary artery reflection can differentiate CPTE from PPH. METHODS: Since CPTE predominantly involves the proximal arteries, whereas PPH involve the peripheral arteries, we hypothesized that patients with CPTE have a large augmentation index and a short inflection time. For this study, we enrolled 62 patients who had CPTE (31 patients) and PPH (31 patients). We measured pulmonary arterial pressure using a fluid filled system that included a balloon-tipped flow directed catheter. To quantify the pulmonary artery reflection, we used the augmentation index and inflection time. RESULTS: The augmentation index was markedly higher in CPTE than it was in PPH (27.4% +/- 15.2% [SD] and -25.1% +/- 26.9%, respectively, p < 0.001) and was diagnostic in separating the two groups. Inflection time separated the two groups reasonably well (97 +/- 20 ms and 210 +/- 49 ms, respectively, p < 0.001). CONCLUSIONS: The analysis of pulmonary arterial reflection is useful in the differential diagnosis of CPTE and PPH.

Adult↗

PubMed2001

Patterning the protochordate neural tube.

The complex vertebrate nervous system has evolved from a simpler nervous system such as that seen in present-day protochordates. Through a recent accumulation of gene-expression data, together with fine anatomical studies, we are now able to identify both how the neural tube was patterned when it first evolved and what is truly novel in the vertebrate neural tube. We are entering a new era in the understanding of how the evolution of novel vertebrate structures is linked to genetic evolution.

Animals↗

PubMed2001

Ascidian embryos as a model system to analyze expression and function of developmental genes.

Ascidians have served as an appropriate experimental system in developmental biology for more than a century. The fertilized egg develops quickly into a tadpole larva, which consists of a small number of organs including epidermis, central nervous system with two sensory organs, endoderm and mesenchyme in the trunk, and notochord and muscle in the tail. This configuration of the ascidian tadpole is thought to represent the most simplified and primitive chordate body plan. Their embryogenesis is simple, and lineage of embryonic cells is well documented. The ascidian genome contains a basic set of genes with less redundancy compared to the vertebrate genome. Cloning and characterization of developmental genes indicate that each gene is expressed under discrete spatio-temporal pattern within their lineage. In addition, the use of various molecular techniques in the ascidian embryo system highlights its advantages as a future experimental system to explore the molecular mechanisms underlying the expression and function of developmental genes as well as genetic circuitry responsible for the establishment of the basic chordate body plan. This review is aimed to highlight the recent advances in ascidian embryology.

Animals↗

PubMed2001

Involvement of Rel/NF-kappaB in regulation of ascidian notochord formation.

The Rel/NF-kappaB family is known to be involved in a wide variety of biological processes, including morphogenesis. In the present study, two protochordate cDNA clones encoding Rel/NF-kappaB proteins, named As-rel1 and As-rel2, were isolated from a fertilized egg cDNA library of the ascidian Halocynthia roretzi. The As-rel1 protein is a typical Rel/NF-kappaB family member, containing a Rel homology domain, a nuclear localization sequence and a C-terminal putative transcription activation domain, while the As-rel2 protein is a novel Rel/NF-kappaB family member that lacks a nuclear localization sequence and the C-terminal domain. Northern blot analyses showed that both transcripts were maternally expressed and that their expression changed during development of H. roretzi embryos. Although injection of the As-rel2 mRNA into H. roretzi fertilized eggs had little effect on embryonic development, injection of the As-rel1 mRNA interfered greatly with notochord formation, resulting in a shortened tail with a reduced number of notochord cells. In contrast, embryos co-injected with As-rel1 and As-rel2 mRNA developed normally, indicating that the As-rel2 protein rescued the defect in notochord formation induced by the injection of As-rel1 mRNA alone. These results strongly suggest that the As-rel1 protein functions as a suppressor in ascidian notochord formation, while the As-rel2 protein has an antagonistic effect on the action of the As-rel1 protein.

Amino Acid Sequence↗

PubMed2001

Hypoxic ventilatory depression in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes.

We describe a case of a 21-year-old man with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) who presented with hypoxic ventilatory depression. He had chronic hypoventilation, which was not explained by weakness of respiratory muscles. His hypercapnic ventilatory response was not impaired. In contrast, hypoxic ventilatory depression was observed in the isocapnic progressive hypoxic response test. After exposure to hypoxic conditions, his respiratory frequency decreased and tidal volume was unchanged. The hypoxic ventilatory depression was partially blocked by pretreatment with aminophylline. In conclusion, we need to be careful with patients with MELAS who are hypoxaemic because a vicious circle of hypoxia and hypoventilation can occur.

Adenosine↗

PubMed2001

Uveitopathogenic sites in recoverin.

PURPOSE: This study was carried out in order to determine the most potent and novel uveitopathogenic sites of recoverin using synthetic peptides. METHODS: Several synthetic peptides containing the recoverin sequence plus adjuvants were injected into Lewis rats, and the uveitopathogenic sequence was defined, clinically, histologically, and immunologically. RESULTS: Peptides containing of amino acids 57-85 and 136-167 induced severe EAU, and the lowest doses to induce EAU were 20 microg and 10 microg, respectively. Lymphocyte proliferative reactions were also positive for peptides 57-85 and 136-167. The core sequences within the uveitopathogenic site were 65-79 and 153-164. Peptides of amino acids 65-79 within 57-85 and 149-167 within 136-167 were the smallest in the recoverin sequence, respectively, that could induce severe EAU. CONCLUSION: We found recoverin has some novel potent uveitopathogenic sites, 149-167. These findings of the uveitopathogenic sites in recoverin may lead to improved understanding of the pathogenesis of uveitis and the means to design specific treatment.

Animals↗

PubMed2001

Brachyury homolog (HpTa) is involved in the formation of archenteron and secondary mesenchyme cell differentiation in the sea urchin embryo.

Sea urchin Brachyury homolog (HpTa) is expressed exclusively in the vegetal plate and secondary mesenchyme cells in the embryos of sea urchin Hemicentrotus pulcherrimus. In order to gain insights into the role of HpTa during sea urchin development, we designed experiments to perturb the embryo by inducing ectopic overexpression of HpTa by injecting fertilized eggs with HpTa mRNA. The overexpression of HpTa resulted in suppression of the formation of vegetal plate and secondary mesenchyme cells. We assume that the interaction of HpTa with unknown factors is required for the activation of the HpTa target genes, and that the excess amount of HpTa proteins produced from injected HpTa mRNA depletes the co-factors. In consequence, the target genes of HpTa would be repressed by the overexpression of HpTa. We suggest that HpTa is involved in the formation of the vegetal plate and the differentiation of secondary mesenchyme cells.

Journal Article↗

PubMed2001

Decreased triglyceride-rich lipoproteins in transgenic skinny mice overexpressing leptin.

Leptin is an adipocyte-derived circulating satiety factor with a variety of biological effects. Evidence has accumulated suggesting that leptin may modulate glucose and lipid metabolism. In the present study, we examined lipid metabolism in transgenic skinny mice with elevated plasma leptin concentrations. The plasma concentrations of triglycerides and free fatty acids in transgenic skinny mice were 71.5 (P < 0.01) and 89.1% (P < 0.05) of those in their nontransgenic littermates, respectively. Separation of plasma into lipoprotein classes by ultracentrifugation revealed that very low density lipoprotein-triglyceride concentrations were markedly reduced in transgenic skinny mice relative to the controls. The clearance of triglycerides estimated by a fat-loading test was enhanced in transgenic skinny mice; the triglyceride concentration in transgenic skinny mice 3 h after fat loading was 39.7% (P < 0.05) of that of their nontransgenic littermates. Postheparin plasma lipoprotein lipase activity increased 1.4-fold (P < 0.05) in transgenic skinny mice. Our data demonstrated a significant reduction in plasma triglyceride concentrations, accompanied by increased lipoprotein lipase activity in transgenic skinny mice overexpressing leptin, suggesting that leptin plays a role in long-term triglyceride metabolism.

Animals↗

PubMed2001

Generation of dendritic cells from leukaemia cells of a patient with acute promyelocytic leukaemia by culture with GM-CSF, IL-4 and TNF-alpha.

Dendritic cells are potent antigen-presenting cells derived from CD34+ haemopoietic stem cells. Dendritic cells have been reported to be generated from cells in granulocytic lineage as well as monocytes, blood dendritic cell precursors and lymphoid progenitors. In order to explore the differentiation pathway of dendritic cells from granulocytic cells and the applicability of leukaemia-derived dendritic cells for anti-leukaemic immunotherapy in acute leukaemia of granulocytic origin, we tried to generate dendritic cells from leukaemia cells of a patient with acute promyelocytic leukaemia (APL). Leukaemia cells were cultured with GM-CSF, IL-4 and TNF-alpha for 10 days. Azurophilic granule-containing cells with marked cytoplasmic projections were generated in the culture. FACS analysis of these cultured cells revealed the generation of CD1a+, CD83+, CD80+, CD86+, CD40+ and HLA-DR+ cells. The leukaemic origin of these dendritic-like cells was demonstrated by in situ hybridization of magnetic-bead-sorted CD1a+ dendritic cells using the DNA probes of t(15;17). Cells generated by culturing leukaemia cells were demonstrated to have a potent antigen-presenting function in allogeneic mixed leucocyte cultures. These findings show the plausibility of the previously reported pathway of dendritic cell maturation through granulocytic cells and suggest the possibility of anti-leukaemic immunotherapy using leukaemia-derived dendritic cells even in patients with acute promyelocytic leukaemia.

Adult↗

PubMed2001

Central serotonergic mechanisms on head twitch response induced by benzodiazepine receptor agonists.

Intraperitoneal injection of benzodiazepine receptor agonists (estazolam, zopiclone, triazolam: 0.03-0.24 mmol/kg) induces the head twitch response (HTR). The present study was undertaken to examine the possible participation of the serotonergic system in the mechanism of head twitches induced by benzodiazepine receptor agonists (BZ-RAs). The HTR induced by BZ-RAs was suppressed by pretreatment with ketanserine (1 mg/kg, i.p.), a selective 5-HT(2) receptor antagonist. Pretreatment with fluoxetine (10 mg/kg, i.p.), a 5-HT reuptake inhibitor, and 8-hydroxy-2-(di-n-propylamino)tetralin, a 5-HT(1A) receptor agonist, also suppressed the HTR induced by BZ-RAs. These results suggest that the HTR induced by BZ-RAs may be the result of an activation of postsynaptic 5-HT(2) receptors, probably due to direct action.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2001

FGF signals are involved in the differentiation of notochord cells and mesenchyme cells of the ascidian Halocynthia roretzi.

Differentiation of notochord cells and mesenchyme cells of the ascidian Halocynthia roretzi requires interactions with neighboring endodermal cells and previous experiments suggest that these interactions require fibroblast growth factor (FGF). In the present study, we examined the role of FGF in these interactions by disrupting signaling using the dominant negative form of the FGF receptor. An FGF receptor gene of H. roretzi (HrFGFR) is expressed both maternally and zygotically. The maternally expressed transcript was ubiquitously distributed in fertilized eggs and in early embryos. Zygotic expression became evident by the neurula stage and transcripts were detected in epidermal cells of the posterior half of embryos. Synthetic mRNA for the dominant negative form of FGFR, in which the intracellular tyrosine kinase domain was deleted, was injected into fertilized eggs to interfere with the possible function of HRFGFR: Injected eggs cleaved and gastrulated the same as the control embryos. Analyses of the expression of differentiation markers in the experimental embryos indicated that the differentiation of epidermal cells, muscle cells and endodermal cells was not affected significantly. However, manipulated embryos showed downregulation of notochord-specific Brachyury expression and failure of notochord cell differentiation, resulting in the development of tailbud embryos with shorted tails. The expression of an actin gene that is normally expressed in mesenchyme cells was also suppressed. These results suggest that FGF signals are involved in differentiation of notochord cells and mesenchyme cells in Halocynthia embryos. Furthermore, the patterning of a neuron-specific tubulin gene expression was disturbed, suggesting that the formation of the nervous system was directly affected by disrupting FGF signals or indirectly affected due to the disruption of normal notochord formation.

Amino Acid Sequence↗

PubMed2001

Gene expression profiles in Ciona intestinalis tailbud embryos.

A set of 3423 expressed sequence tags derived from the Ciona intestinalis tailbud embryos was categorized into 1213 independent clusters. When compared with DNA Data Bank of Japan database, 502 clusters of them showed significant matches to reported proteins with distinct function, whereas 184 lacked sufficient information to be categorized (including reported proteins with undefined function) and 527 had no significant similarities to known proteins. Sequence similarity analyses of the 502 clusters in relation to the biosynthetic function, as well as the structure of the message population at this stage, demonstrated that 390 of them were associated with functions that many kinds of cells use, 85 with cell-cell communication and 27 with transcription factors and other gene regulatory proteins. All of the 1213 clusters were subjected to whole-mount in situ hybridization to analyze the gene expression profiles at this stage. A total of 387 clusters showed expression specific to a certain tissue or organ; 149 showed epidermis-specific expression; 34 were specific to the nervous system; 29 to endoderm; 112 to mesenchyme; 32 to notochord; and 31 to muscle. Many genes were also specifically expressed in multiple tissues. The study also highlighted characteristic gene expression profiles dependent on the tissues. In addition, several genes showed intriguing expression patterns that have not been reported previously; for example, four genes were expressed specifically in the nerve cord cells and one gene was expressed only in the posterior part of muscle cells. This study provides molecular markers for each of the tissues and/or organs that constitutes the Ciona tailbud embryo. The sequence information will also be used for further genome scientific approach to explore molecular mechanisms involved in the formation of one of the most primitive chordate body plans.

Animals↗