PubMed Health⌕ Search

Biomedical subjects

M Taira

Publications and source records attributed to M Taira.

At least 19 recordsLinked to original sources
PubMed1995

Insulin stimulates hormone-sensitive cyclic GMP-inhibited cyclic nucleotide phosphodiesterase in rat brown adipose cells.

The presence and regulation of a hormone-sensitive cyclic GMP-inhibited cyclic nucleotide phosphodiesterase (cGI PDE) in rat brown adipose cells was investigated. cDNA clones for two cGI PDE isoforms, cGIP1 and cGIP2, have been isolated. Using a rat cGIP1 (RcGIP1) cDNA probe, RcGIP1 mRNA (approximately 5.3 kb) was detected in Northern blots of both brown and white adipose RNA. cGI PDE was detected in both microsomal and plasma membrane fractions of brown and white adipose cells by Western blotting using anti-RcGIP1 peptide antibody. When cells were incubated with insulin before membrane preparation, cGI PDE activity in the microsomal fraction was increased by 2- to 2.5-fold within 10 min. Isoproterenol also stimulated the activity of cGI PDE in the microsomal fraction by 1.5-fold. In cells incubated with both insulin and isoproterenol, microsomal cGI PDE activity was similar to that in microsomal fractions isolated from cells incubated with insulin alone. These results suggest that the hormonal regulation of cGI PDE, presumably a cGIP1 isoform, in rat brown adipose cells is similar to that in white adipose cells.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

A dominant negative bone morphogenetic protein 4 receptor causes neuralization in Xenopus ectoderm.

Injection of DN-BR mRNA encoding a dominant negative type I receptor for bone morphogenetic protein 4 (BMP4) converted prospective ectoderm into neural tissue in Xenopus animal cap explants, in the absence of expression of mesodermal marker genes. The injected caps expressed a general neural marker NCAM and the forebrain marker opsin. Coinjection of wild-type BMP4 receptor mRNA completely reversed the neuralization by DN-BR. No expression of known neuralizing factors, i.e., noggin and follistatin, was detected in the DN-BR-injected animal caps. Furthermore, neuralization elicited by noggin or 3m, a LIM domain mutant of Xlim-1, was substantially inhibited by co-injection of BMP4 mRNA. Since BMP4 is expressed in the prospective ectoderm during gastrulation, our results suggest that the ventralizing factor BMP4 acts also as a physiological inhibitor of neuralization in the development of Xenopus ectoderm.

Animals↗
PubMed1995

Expression pattern of the murine LIM class homeobox gene Lhx3 in subsets of neural and neuroendocrine tissues.

Murine Lhx3 cDNA isolated from the mouse pituitary cDNA library encodes a LIM-type homeodomain protein that contains two tandemly repeated LIM domains and the homeodomain. The identities of predicted amino acid sequences between the mouse of Lhx3 and Xenopus Xlim-3 genes are 80, 95, and 97% in the LIM domains 1 and 2, and the homeodomain, respectively, and 84% in the entire protein. 5'-RACE procedures and genomic cloning revealed that two distinct N-terminal sequences arise from two different exons 1a and 1b. Exon 1a encodes a sequence similar to that of Xlim-3, whereas exon 1b encodes a different N-terminus. It is likely that there are two transcription initiation sites in the Lhx3 gene. The Lhx3 transcripts were detected by whole mount in situ hybridization as early as day E9.5 post coitum in Rathke's pouch and the closing neural tube. During subsequent development, Lhx3 expression was observed in the anterior and intermediate but not in the posterior lobes of the pituitary, and in the ventral hindbrain and spinal cord. Northern blot analysis of adult tissues showed that Lhx3 mRNA persists in the pituitary. The expression pattern of Lhx3 is well conserved between Xenopus and mouse, underscoring the functional importance of this gene as a regulator of development. A number of established cell lines of pituitary origin express Lhx3 and therefore constitute a useful tool for further study of Lhx3 gene function.

Amino Acid Sequence↗
PubMed1995

The LIM class homeobox gene lim5: implied role in CNS patterning in Xenopus and zebrafish.

LIM homeobox genes are characterized by encoding proteins in which two cysteine-rich LIM domains are associated with a homeodomain. We report the isolation of a gene, named Xlim-5 in Xenopus and lim5 in the zebrafish, that is highly similar in sequence but quite distinct in expression pattern from the previously described Xlim-1/lim1 gene. In both species studied the lim5 gene is expressed in the entire ectoderm in the early gastrula embryo. The Xlim-5 gene is activated in a cell autonomous manner in ectodermal cells, and this activation is suppressed by the mesoderm inducer activin. During neurulation, expression of the lim5 gene in both the frog and fish embryo is rapidly restricted to an anterior region in the developing neural plate/keel. In the 2-day Xenopus and 24-hr zebrafish embryo, this region becomes more sharply defined, forming a strongly lim5-expressing domain in the diencephalon anterior to the midbrain-forebrain boundary. In addition, regions of less intense lim5 expression are seen in the zebrafish embryo in parts of the telencephalon, in the anterior diencephalon coincident with the postoptic commissure, and in restricted regions of the midbrain, hindbrain, and spinal cord. Expression in ventral forebrain is abolished from the 5-somite stage onward in cyclops mutant fish. These results imply a role for lim5 in the patterning of the nervous system, in particular in the early specification of the diencephalon.

Amino Acid Sequence↗
PubMed1995

Mammalian phosphoribosyl-pyrophosphate synthetase.

PRPP synthetase from rat liver exists as large molecular weight aggregates composed of at least three different components. Cloning of cDNA for the catalytic subunit revealed the presence of two highly homologous isoforms of 34 kDa, designated as PRS I and PRS II. Northern blot analysis showed tissue-differential expression of the two isoform genes. cDNA was expressed in E. coli and studies on the recombinant isoforms showed differences in sensitivity to inhibition by ADP and GDP and to heat inactivation. The rat gene for PRS I has 22 kb and is split into 7 exons. cDNAs for human enzymes were also cloned. Human genes for PRS I and PRS II are localized at different regions on the X-chromosome and their promoter regions were examined. Another component, PRPP synthetase-associated protein of 39 kDa (PAP39), was cloned from cDNA library of the rat liver. The deduced amino acid sequence of PAP39 is remarkably similar to those of PRS I and PRS II. Evidence indicated molecular interaction between PAP39 and the catalytic subunits and an inhibitory effect of PAP39 on the catalytic activity. Expression of the PAP39 gene is tissue-differential like the PRS genes, indicating that the composition of PRPP synthetase may differ with the tissue, hence properties of the enzyme would differ. Further studies on these components and their interaction are expected to reveal various mechanisms governing mammalian PRPP synthetase.

Amino Acid Sequence↗
PubMed1995

Distinctive anatomical patterns of gene expression for cGMP-inhibited cyclic nucleotide phosphodiesterases.

Type III cGMP-inhibited phosphodiesterases (PDE3s) play important roles in hormonal regulation of lipolysis, platelet aggregation, myocardial contractility, and smooth muscle relaxation. We have recently characterized two PDE3 subtypes (PDE3A and PDE3B) as products of distinct but related genes. To elucidate their biological roles, in this study we compare cellular patterns of gene expression for these two enzymes during rat embryonic and postnatal development using in situ hybridization. PDE3B [corrected] mRNA is abundant in adipose tissue and is also expressed in hepatocytes throughout development. This mRNA is also highly abundant in embryonic neuroepithelium including the neural retina, but expression is greatly reduced in the mature nervous system. Finally, PDE3B [corrected] mRNA is localized in spermatocytes and renal collecting duct epithelium in adult rats. PDE3B mRNA is highly expressed in the cardiovascular system, including myocardium and arterial and venous smooth muscle, throughout development. It is also abundant in bronchial, genitourinary and gastrointestinal smooth muscle and epithelium, megakaryocytes, and oocytes. PDE3A [corrected] mRNA demonstrates a complex, developmentally regulated pattern of gene expression in the central nervous system. In summary, the two different PDE3s show distinctive tissue-specific patterns of gene expression suggesting that PDE3B [corrected] is involved in hormonal regulation of lipolysis and glycogenolysis, while regulation of myocardial and smooth muscle contractility appears to be a function of PDE3A [corrected]. In addition, the present findings suggest previously unsuspected roles for these enzymes in gametogenesis and neural development.

Animals↗
PubMed1995

Insulin resistance associated with decreased levels of insulin-receptor messenger ribonucleic acid: evidence of a de novo mutation in the maternal allele.

Mutations in the insulin receptor gene may lead to insulin resistance and diabetes mellitus in some patients. We have studied an insulin-resistant patient with leprechaunism. Insulin binding to the patient's fibroblasts was markedly decreased. Determination of the nucleotide sequence of the patient's insulin receptor gene revealed heterozygosity for a 2-basepair deletion in exon 15. If the premessenger ribonucleic acid (pre-mRNA) is spliced normally, it causes a replacement of codon 970 in the beta-subunit with a premature chain termination codon, thereby deleting most of the intracellular domain of the receptor. The mRNA transcribed from the allele with a 2-base-pair deletion is likely to be unstable because mRNA transcripts from this allele could not be detected by complementary DNA sequencing. Northern blot analysis showed that the patient's insulin receptor mRNA was decreased by 90% compared with that of a control subject, thus suggesting that the patient is a compound heterozygote for two mutations that decrease levels of insulin receptor mRNA. This deletion mutation in exon 15 seems to be a de novo mutation, because it was not detected in either parent. Investigation of the inheritance of a silent sequence polymorphism in exon 17 provided that the deletion occurred in the maternal allele. Furthermore, linkage analysis suggests that the second mutation is derived from the patient's father, although we could not directly identify it by sequencing the coding region of the insulin receptor gene. Therefore, it is possible that this mutation is present in a regulatory domain of the insulin receptor gene, acting in cis-dominant fashion to reduce the levels of insulin receptor mRNA. Analyses of the hypervariable region in the myoglobin and pMCT118 loci were consistent with the assumption that the father and mother studied here are indeed the biological parents of the diseased patient. We hereby conclude that the patient is a compound heterozygote for two mutant alleles, both of which are responsible for the reduced levels of insulin receptor mRNA and insulin binding.

Adult↗
PubMed1995

Subarachnoid hemorrhage of unknown origin associated with Weber-Christian disease--case report.

A 58-year-old female, who had suffered from Weber-Christian disease for 26 years, presented with subarachnoid hemorrhage. Cerebral angiography showed dilatation of the basilar tip. An operation was performed in the chronic stage. The wall of dilated basilar artery was tough, but that of the right superior cerebellar artery was very thin and three small aneurysms were found on the right middle cerebral artery. Blood levels of fibrin degradation products, plasmin-alpha 2-plasmin inhibitor complex, and thrombin-antithrombin III complex were increased. The abnormality of the coagulation-fibrinolysis system and the fragility of the cerebral arteries related to Weber-Christian disease were probably the cause of the subarachnoid hemorrhage.

Basilar Artery↗
PubMed1995

[A case of successful treatment of chronic sternal osteomyelitis and mediastinitis after ascending aorta and hemiarch reconstruction].

Mediastinitis is one of severe and fatal complications after cardiac surgery, especially in the presence of a prosthetic graft. A 70-year-old male, who was suffered from chronic sternal osteomyelitis and mediastinitis after ascending aorta and hemiarch reconstruction was reported. He developed high fever and leucocytosis on the 16th postoperative day. Wound culture was positive for Grampositive organisms. He was diagnosed as having sternal osteomyelitis and mediastinitis and treated by sternal bone debridement and irrigation with dilute povidone iodine solution with no effects. Total excision of the infected sternum, irrigation with non-diluted solution of povidone iodine and omental transfer were performed successfully. The literature regarding omental transfer for mediastinitis and infected prosthetic grafts was briefly reviewed.

Aged↗
PubMed1995

LIM domain proteins.

The LIM domain is a cysteine-rich domain composed of 2 special zinc fingers that are joined by a 2-amino acid spacer. Some proteins are constituted by LIM domains only while others contain a variety of different functional domains. LIM proteins form a diverse group which includes transcription factors and cytoskeletal proteins. The primary role of LIM domains appears to be in protein-protein interaction, through the formation of dimers with identical or different LIM domains or by binding distinct proteins. In LIM homeodomain proteins, LIM domains seem to function as negative regulatory domains. LIM homeodomain proteins are involved in the control of cell lineage determination and the regulation of differentiation, and LIM-only proteins may have similar roles. LIM-only proteins are also implicated in the control of cell proliferation since several genes encoding such proteins are associated with oncogenic chromosome translocations. In analyzing sequence relationships between LIM domains we suggest that they may be arranged into 5 groups which appear to correlate with the structural and functional properties of the proteins containing these domains.

Amino Acid Sequence↗
PubMed1994

Islet amyloid polypeptide and its N-terminal and C-terminal flanking peptides' immunoreactivity in islet amyloid of diabetic patients.

We determined immunohistochemically whether the islet amyloid polypeptide (IAPP)/amylin precursor is one component of islet amyloid, using polyclonal antibodies specific for human IAPP8-17 and amino (N)-terminal and carboxy (C)-terminal flanking peptides. To enhance immunostaining of the amyloid, we pretreated the pancreatic tissue sections with 100% formic acid. In three non-diabetic subjects, pancreatic islet cells were immunoreactive to anti-IAPP8-17 and anti-N-terminal and C-terminal flanking peptide antibodies and the reactivity was enhanced with formic acid pretreatment. In six type 2 diabetic subjects and a subject with type A insulin resistance, islet amyloid deposits were reactive to anti-IAPP8-17 antibody, but not to anti-N-terminal and C-terminal flanking peptide antibodies. Formic acid pretreatment markedly enhanced the reactivity to anti-IAPP8-17 antibody; however, it failed to show the reactivity to anti-N-terminal and C-terminal flanking peptide antibodies. Formic acid pretreatment of pancreatic tissue sections prepared for immunostaining is useful for visualization of buried epitopes of mature IAPP and its precursor molecules, either in islet amyloid deposits or in the islet cells. We conclude that the IAPP precursor and N-terminal and C-terminal flanking peptides are not constituents of human islet amyloid.

Adult↗
PubMed1993

Histological difference between complete responders and non-responders to interferon therapy of the livers of patients with chronic hepatitis C.

Liver histology was compared in patients with chronic hepatitis C to note the differences between responders and non-responders to interferon treatment. Fifty-eight patients were administered interferon in varying doses and over various periods, and were then followed up for 1 year. According to the improvement status of serum alanine aminotransferase (ALT) levels during this period, the patients were classified into complete responders who showed complete normalization of ALT; partial responders who exhibited a significant decrease, but not complete normalization of ALT; and non-responders who did not reveal any significant decrease of ALT. Before application of the interferon treatment, liver biopsies were analyzed in four parameters and given scores from 0 to 5 for three groups in cord with no prior knowledge of the efficacy. The parameters included necroinflammation, fibrosis/lobular distortion, portal lymphocytic reaction and portal (or fibrous septal) outline destruction. Results indicated that there were no significant differences in the score of necroinflammation and portal lymphocytic reaction between the complete responder group and the non-responder group. In contrast, the complete responder group exhibited weaker fibrosis/lobular distortion and less portal outline destruction than the non-responder group. The partial responder group was more akin to the former group in these parameters. Thus, it is safe to conclude that liver histology may predict the efficacy of interferon treatment.

Adult↗
PubMed1992

Elevated expression of the ornithine decarboxylase gene in human esophageal cancer.

The mechanisms involved in sustaining the high levels of ornithine decarboxylase (ODC) activity in human cancers are not well defined. We examined the level of expression of ODC mRNA together with ODC activity in surgically excised human cancers, including esophagus, stomach, colon, and liver tumors, the objective being to determine whether the ODC mRNA level correlates with enhancement of ODC activity in these cancers. Among these tumors, the esophageal cancers had the highest ODC activity (120 +/- 43.9 pmol of CO2/h/mg of protein), compared with the stomach (37.6 +/- 13.7), colon (22.8 +/- 5.9), and liver (10.2 +/- 5.6) cancers. A remarkable increase in ODC mRNA was seen in all of the esophageal cancers. The ratio of ODC mRNA in the tumors, relative to the paired normal tissues, was 14.6 +/- 3.7. Some increase was noted in some of the stomach (2.9 +/- 0.9) and colon (2.1 +/- 0.9) cancers, but there was no increase in the liver tumors (0.9 +/- 0.2). A significant correlation was noted between ODC activity and mRNA expression in cancerous and noncancerous tissues of the esophagus, stomach, and colon, thereby suggesting that increased steady-state mRNA may be responsible for the high ODC activity in these tumors. Southern blot analysis of the DNA from the esophageal cancers revealed no amplification or significant rearrangement of the gene. Mechanisms sustaining high ODC mRNA levels in esophageal cancers may be an enhancement of the promoter activity of this gene or stabilization of the mRNA.

Blotting, Northern↗
PubMed1992

The motor cortex and the coding of force.

The relation of cellular activity in the motor cortex to the direction of two-dimensional isometric force was investigated under dynamic conditions in monkeys. A task was designed so that three force variables were dissociated: the force exerted by the subject, the net force, and the change in force. Recordings of neuronal activity in the motor cortex revealed that the activity of single cells was directionally tuned and that this tuning was invariant across different directions of a bias force. Cell activity was not related to the direction of force exerted by the subject, which changed drastically as the bias force changed. In contrast, the direction of net force, the direction of force change, and the visually instructed direction all remained quite invariant and congruent and could be the directional variables, alone or in combination, to which cell activity might relate.

Animals↗
PubMed1992

Molecular cloning and expression of human myocardial cGMP-inhibited cAMP phosphodiesterase.

We have cloned a cDNA for a myocardial cGMP-inhibited cAMP phosphodiesterase (cGI PDE) from a human heart cDNA library in lambda Zap II. The open reading frame [3.5 kilobases (kb)] of cDNA clone n.13.2 (7.7 kb) encodes a protein of 125 kDa. In Northern blots of total human ventricle RNA, a single mRNA species (8.3 kb) hybridized with a 4-kb EcoRI restriction fragment of clone n.13.2 cDNA (containing the entire open reading frame). The carboxyl-terminal region of the deduced amino acid sequence of the cGI PDE contains the putative catalytic domain conserved among mammalian PDE families. A partial cDNA clone, n.2, encoding a truncated, 54-kDa cGI PDE containing the conserved domain was expressed as a catalytically active fusion protein in Escherichia coli. cAMP hydrolytic activity was inhibited by cGMP and OPC 3911 but not by rolipram. Thus, this report provides direct proof that the conserved domain contains the catalytic core of cGI PDEs.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

Promoter regions of the human X-linked housekeeping genes PRPS1 and PRPS2 encoding phosphoribosylpyrophosphate synthetase subunit I and II isoforms.

The 5' regions of the human phosphoribosylpyrophosphate synthetase subunit I and II genes (PRPS1 and PRPS2, respectively) were isolated and sequenced. A comparison of the nucleotide sequences between human and rat PRPS1 genes revealed that the sequences around the transcription initiation sites were conserved over 56 nucleotides, and that a TATA-like sequence, a CCAAT box and three putative Sp1 binding sites were present at almost the same positions in the GC-rich sequences. Two major transcription initiation sites were localized in the human PRPS1, one of the two was located 27 nucleotides downstream from the TATA-like sequence, while the upstream initiation site was in the TATA-like sequence. The promoter region of the human PRPS2 gene was also GC-rich and contained a TATA-like sequence, four Sp1 binding sites and a homopyrimidine stretch. The initiation sites were localized at 90 nucleotides upstream from the ATG initiation codon. Chloramphenicol acetyltransferase (CAT)/promoter fusion assays showed that a 2.0 kb region (human PRPS1) and a 1.1 kb region (human PRPS2) possessed the promoter activities in four cell lines. The CAT activities in the three human cell lines tended to correlate with the steady-state mRNA levels of the PRPS1 and PRPS2 genes. These results suggest that the 5' flanking regions cloned contribute to the cell-differential expression of these two genes.

Amino Acid Sequence↗