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T Saito

Publications and source records attributed to T Saito.

At least 19 recordsLinked to original sources
PubMed1992

DNA binding and transcriptional regulatory activity of mammalian achaete-scute homologous (MASH) proteins revealed by interaction with a muscle-specific enhancer.

The MASH genes are vertebrate homologues of achaete-scute, genes required for neuronal determination in Drosophila. The sequence of MASH1 and MASH2 contains a basic helix-loop-helix (bHLH) motif that is present in other transcriptional regulators such as MyoD and E12. In the absence of an authentic target for the MASH proteins, we examined their DNA binding and transcriptional regulatory activity by using a binding site (the E box) from the muscle creatine kinase (MCK) gene, a target of MyoD. Like myogenic bHLH proteins, the MASH proteins form heterooligomers with E12 that bind the MCK E box with high affinity in vitro. Unexpectedly, however, MASH1 and MASH2 also activate transcription of both exogenous and endogenous MCK in transfected C3H/10T1/2 fibroblasts. However, they do not induce myogenesis. Myogenic activity is not exclusively a property of the MyoD basic region, as substitution of this domain fails to confer myogenic activity on MASH1. These data suggest that different bHLH proteins may activate overlapping but distinct sets of target genes in the same cell type.

Amino Acid Sequence↗
PubMed1992

Characterization of a new avian-like influenza A virus from horses in China.

In March 1989 a severe outbreak of respiratory disease occurred in horses in the Jilin and Heilongjiang provinces of Northeast China that caused up to 20% mortality in some herds. An influenza virus of the H3N8 subtype was isolated from the infected animals and was antigenically and molecularly distinguishable from the equine 2 (H3N8) viruses currently circulating in the world. The reference strain A/Equine/Jilin/1/89 (H3N8) was most closely related to avian H3N8 influenza viruses. Sequence comparisons of the entire hemagglutinin (HA), nucleoprotein (NP), neuraminidase (NA), matrix (M), and NS genes along with partial sequences of the three polymerase (PB1, PB2, PA) genes suggest that six of the eight gene segments (PA, HA, NP, NA, M, NS) are closely related to avian influenza viruses. Since direct sequence analysis can only provide a crude measure of relationship, phylogenetic analysis was done on the sequence information. Phylogenetic analyses of the entire HA, NP, M, and NS genes and of partial sequences of PB1, PB2, and PA indicated that these genes are of recent avian origin. The NP gene segment is closely related to the gene segment found in the newly described H14 subtype isolated from ducks in the USSR. The A/Equine/Jilin/1/89 (H3N8) influenza virus failed to replicate in ducks, but did replicate and cause disease in mice on initial inoculation and on subsequent passaging caused 100% mortality. In ferrets, the virus caused severe influenza symptoms. A second outbreak of influenza in horses in Northeast China occurred in April 1990 in the Heilongjiang province with 48% morbidity and no mortality. The viruses isolated from this outbreak were antigenically indistinguishable from those in the 1989 outbreak and it is probable that the reduced mortality was due to the immune status of of the horses in the region. No influenza was detected in horses in Northern China in the spring, summer, or fall of 1991 and no influenza has been detected in horses in adjacent areas. Our analysis suggests that this new equine influenza virus in horses in Northeast China is the latest influenza virus in mammals to emerge from the avian gene pool in nature and that it may have spread to horses without reassortment. The appearance of this new equine virus in China emphasizes the potential for whole avian influenza viruses to successfully enter mammalian hosts and serves as a model and a warning for the appearance of new pandemic influenza viruses in humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

pH dependence of the action of arginine vasopressin in renal collecting tubule.

We determined whether extracellular pH (pHe) and intracellular pH (pHi) modulate the cellular actions of arginine vasopressin (AVP) in rat renal papillary collecting tubule cells in culture. AVP significantly increased cellular adenosine 3',5'-cyclic monophosphate (cAMP) production and cellular free calcium concentration ([Ca2+]i). pHe ranging from 6.8 to 8.0 distributed the pHi between 6.94 and 7.27. The acidified pHe reduced the AVP- and forskolin-induced cAMP production, the AVP-mobilized [Ca2+]i, and [3H]AVP receptor binding, and the alkalinized pHe enhanced the AVP- and forskolin-produced cAMP. Intracellular acidification occurred under three different conditions as follows: using carbonyl cyanide-m-chlorophenylhydrazone (CCCP), acetate buffer, and bicarbonate buffer with a reduced concentration of bicarbonate. Intracellular acidification significantly diminished both the AVP- and forskolin-induced increases in cAMP production and the AVP-mobilized [Ca2+]i but did not alter [3H]AVP receptor binding. Intracellular alkalinization by NH4Cl or chloride-free bicarbonate buffer, in contrast, augmented them. These results indicate that alterations in pHi modulate the cellular action of AVP to produce cAMP and mobilize [Ca2+]i in renal papillary collecting tubule cells. Also, reduced receptor binding of AVP is involved in the mechanism of the effects of low pHe.

Ammonium Chloride↗
PubMed1992

pH dependence of inhibition of arginine vasopressin-induced adenosine 3',5'-monophosphate production by cellular sodium depletion in rat renal inner medullary collecting duct cells in culture.

The present study was undertaken to determine whether the change in cellular Na+ concentration ( [Na+]i) or cellular pH (pHi) is essential for the modulation by Na+/H+ antiporter of the cellular action of arginine vasopressin (AVP) in renal inner medullary collecting duct cells in culture. Extracellular Na+ depletion promptly decreased [Na+]i from 15.8 to 5.4 mM (P less than 0.01), which was closely related to the decrease in pHi (7.19 to 6.97; P less than 0.01). In the presence of 0.5 mM 3-isobutyl-1-methylxanthine, AVP increased cellular cAMP production in a dose-dependent manner. This was significantly blunted in the Na(+)-depleted cells (1 nM AVP; 481.9 vs. 341.0 fmol/micrograms protein; P less than 0.01). When cells were incubated with the Na(+)-depleted medium containing 25 mM NaHCO3, [Na+]i decreased promptly, but the pHi remained unchanged. Under this condition, the AVP-induced increase in cellular cAMP production was not altered (1 nM AVP; 390.9 vs. 334.8 fmol/micrograms protein). Also, after the Na(+)-depleted cells were incubated in 20 mM NH4Cl, which promptly normalized pHi despite the decreased [Na+]i, the response of cAMP production to AVP was restored. Amiloride (1 x 10(-5)-1 x 10(-3) M), which blocks the Na+/H+ exchange, decreased pHi and AVP- and forskolin-induced cAMP production in a dose-dependent manner. These results indicate that the decrease in [Na+]i promptly inhibits AVP-induced cAMP production mediated through the reduction in pHi in renal inner medullary collecting duct cells.

Amiloride↗
PubMed1992

Ultracytochemistry of glucose-6-phosphate dehydrogenase in adrenal gland.

The distribution of glucose-6-phosphate dehydrogenase (G6PD) activity has been studied by a copper ferrocyanide method in the adrenal cortex cells of a rat. The site of the G6PDH activity was close to the ribosome between the round mitochondria of zonas fasciculata and reticularis.

Adrenal Glands↗
PubMed1992

High incidence of nuclear accumulation of p53 protein in gastric cancer.

The accumulation of p53 protein in the nuclei of cancer cells is known to correlate well with the presence of mutations in the p53 gene. We therefore investigated the immunohistochemical reactivity of the anti-p53 antibody, PAb1801, in specimens taken from 149 cases of primary gastric cancer and processed by acetone fixation, in order to elucidate the incidence and clinicopathological significance of p53 alterations in gastric cancer. Thirty-four out of 99 (34%) advanced gastric cancers and 11 out of 50 (22%) early gastric cancers showed positive reactions in the nuclei. The nuclei of non-cancerous cells, including gastric glandular epithelial cells, however, were not stained. Histopathologically, a nuclear accumulation of p53 protein was seen frequently in papillary adenocarcinoma, well- to moderately-differentiated tubular adenocarcinoma and poorly-differentiated adenocarcinoma with solid nests or focal tubular structures (43/101, 43%), but was rarely seen in signet-ring cell carcinoma, mucinous adenocarcinoma or poorly-differentiated adenocarcinoma growing in a scattered manner (2/48, 4%). There was no correlation between stainability of p53 protein and clinicopathological features such as depth of tumor invasion, microscopic lymphatic invasion, microscopic venous invasion, nodal involvement and clinicopathological stage in papillary adenocarcinoma, well- to moderately-differentiated tubular adenocarcinoma and poorly-differentiated adenocarcinoma with solid nests or focal tubular structures. The results suggest papillary adenocarcinoma, well- to moderately-differentiated tubular adenocarcinoma and poorly-differentiated adenocarcinoma with solid nests or focal tubular structures to share a common carcinogenetic pathway in which mutation of the p53 gene has an important role to play at a relatively early stage. Additionally, we showed the applicability of immunohistochemical detection of p53 protein in endoscopic biopsy material routinely formalin-fixed. The current method may be of some help in routine practice in discriminating between normal, precancerous and cancer cells in the stomach.

Adenocarcinoma↗
PubMed1992

Optic atrophy, sensorineural hearing loss and polyneuropathy--a case of sporadic Rosenberg-Chutorian syndrome.

We report on a 41-year-old woman with slowly progressive motor dominant polyneuropathy, optic atrophy and sensorineural deafness, but without any known familial feature. These neurological manifestations were in accordance with the syndrome reported by Rosenberg and Chutorian in 1967 (Rosenberg-Chutorian syndrome), a unique form of Charcot-Marie-Tooth disease. The syndrome was first reported to be autosomal dominant in trait, but subsequently recessive forms and sporadic ones have also been described. Nerve biopsy and neurophysiological studies including electromyography, nerve conduction velocities, somatosensory evoked potentials, auditory brainstem responses, and visual evoked potentials revealed the axonopathic involvement of the central nervous system as well as the peripheral nervous system. Since neurophysiological aspects of this particular syndrome have not been well studied, these results would provide some insight into the understanding of this disorder.

Adult↗
PubMed1992

[Antibodies to GM1 ganglioside in motor neuron disease--in comparison with demyelinating neuropathy].

We studied serum antibodies to GM1 ganglioside by enzyme linked immunosorbent assay (ELISA) in 55 patients with motor neuron disease (MND) composed of 36 ALS and 19 lower motor neuron disease (LMND), 44 patients with demyelinating neuropathy (DN) composed of 29 Guillain-Barré syndrome (GBS) and 15 chronic inflammatory demyelinating polyneuropathy (CIDP), and 21 healthy controls. High levels of serum antibodies against GM1 were confirmed by thin-layer chromatography overlay procedure. In MND group, the mean level of anti-GM1 IgM antibodies was not significantly elevated in comparison with controls. There was no significant difference in anti-GM1 antibodies between ALS group and LMND group, while anti-GM1 IgM antibodies in DN group, especially in GBS group, were significantly elevated (p < 0.001). High levels of anti-GM1 IgM antibodies (greater than the mean level plus 3 standard deviations of controls) were detected in 9 patients (6 with ALS and 3 with LMND) with MND (16.4%) and 16 patients (11 with GBS and 5 with CIDP) with DN (36.4%). Serum antibodies to GM1 reacted with GD1b ganglioside in only one patient with MND and 10 patients (8 with GBS and 2 with CIDP) with DN. Anti-GM1 IgG antibodies were elevated significantly in DN group. There was no correlation among anti-GM1 IgM antibodies and both duration and severity of illness in MND. In some patients with MND, levels of anti-GM1 IgM antibodies became high in the advanced stage. It is unclear whether these antibodies are primary manifestation or consequence of motor neuron disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies↗
PubMed1992

[Paraproteinemia and motor neuron disease].

In some patients, motor neuron disease (MND) is associated with a paraprotein, raising the question that there may be a relationship between MND and monoclonal gammopathy. We analysed the presence of monoclonal immunoglobulin in the serum from 53 patients with MND using immunofixation in cellulose acetate membrane. The incidence of paraproteins in 6 cases (11.3%) of patients with MND exceeds values found with cellulose acetate membrane supports in reported populations (below 1%), even when age was also considered. Monoclonal components were IgG (33%), IgM (33%) and IgA (33%). In six cases, four showed typical changes of amyotrophic lateral sclerosis and other two patients were spinal progressive muscular atrophy (SPMA) in autopsy. No malignancy was detected in all cases. These results corroborate the concept of a probable association between MND and benign monoclonal gammopathy (plasma cell dyscrasia). A patient with SPMA had transient elevation of IgG-GM1 antibodies. Other five patients with M-proteinemia did not show elevated serum anti GM1 antibodies.

Female↗
PubMed1979

[Development of high-sensitivity radio gas chromatography--specific characteristics of a long path internal gas flow proportional counter (author's transl)].

A long path internal gas flow proportional counter was devised was to be used as a high sensitivity detector for radio gas chromatography, and its performance characteristics were investigated. The long path counter tube used for this detector has a sufficiently long passage in comparison with the diameter. The counter tube for general use is made of brass or copper tube 1 cm in diameter, 100 cm in length with a mirror finish on all internal surface, and the center electrode is of tungsten wire 0.05 mm in diameter. For actual use, several of these counter tubes are connected in series in assembly to hold the total volume of a gas sample in the counting system over a desired counting period. Thus this flow detector as an integral type one and gives directly a counting rate. Experiments showed that the dynamic counting efficiencies of tritium and carbon-14 were about 90% and equal to the static counting efficiencies. Furthermore, with this detector, the counting rate does not appear to be affected by minor variations of the effective inner volume of the counter tube and the flow rate of counting gas.

Carbon Radioisotopes↗
PubMed1979

[The vasopressor role of ADH in the maintenance of blood pressure in experimentally hypertensive rats (author's transl)].

In order to investigate the vasopressor role of ADH in the regulation of blood pressure, passive immunization experiments with an antibody to AVP were carried out in experimentally hypertensive rats. In hypertensive rats treated with deoxycorticosterone acetate (DOCA), spontaneously hypertensive rats (SHR) and spontaneously hypertensive stroke-prone rats (SHR-sp), the intravenous injection of a specific vasopressin antibody resulted in a transient fall of blood pressure of 11 approximately 25mmHg, while in rats with two-kidney Goldblatt hypertension and normal rats, the blood pressure was not affected. This strongly suggests that ADH contributed to systemic vaso-constriction in DOCA hypertension and spontaneous hypertension in rats.

Animals↗