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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 217 records · Page 12Linked to original sources

Expression of a MADS box gene, MEF2D, in neurons of the mouse central nervous system: implication of its binary function in myogenic and neurogenic cell lineages.

MEF2D, a member of myocyte-specific enhancer binding factor 2 (MEF2) gene family, was shown by Northern blot hybridization to be strongly expressed in the head portion of mouse embryos at later stages of ontogenesis, in the cerebellum and the cerebrum of adult mice, in cultured cell lines of neuronal origin, and in skeletal and cardiac muscles. During ontogenesis, MEF2D transcripts were detected by in situ hybridization in the olfactory bulb, entorhinal cortex, pyriform cortex, and hippocampus, in Purkinje and granule cells, and in large neurons in both the ventral and dorsal horns of spinal cord. Adult mice continued to express MEF2D in these limited areas of the central nervous system. Thus, MEF2D seems to be involved in either the differentiation process or the function of these neurons.

Age Factors↗

Dually innervating nociceptive networks in the rat lumbar posterior longitudinal ligaments.

STUDY DESIGN: The present study investigated the distribution of sensory and autonomic nerves to the posterior longitudinal ligament of the rat lumbar vertebra. OBJECTIVE: The results were analyzed to provide a new insight into the pathogenesis of low back pain. SUMMARY OF BACKGROUND DATA: Previous studies that have descriptively reported on posterior longitudinal ligament innervation have attributed important roles to the sinuvertebral nerve as an output of nociceptive sensation. Meanwhile, development of immunohistochemistry has made it possible to identify numerous neurotransmitters, and thus various suggested pathophysiologic roles of the nerve fibers in the posterior longitudinal ligament. However, such microscopic identification of the nerve fibers has not been able to reveal comprehensive distributions of the various fibers, which are presumed to be derived from the sinuvertebral nerve. METHODS: Rat posterior longitudinal ligaments of whole thickness was immunohistochemically stained for calcitonin gene-related peptide and tyrosine hydroxylase, which have been considered markers of nociceptive and noradrenergic fibers respectively. Light-microscopic and electron-microscopic observation was reinforced with another experimental study in which resection of the dorsal root ganglia induced characteristic denervation patterns to the rat posterior longitudinal ligament. RESULTS: The present study revealed that the lumbar. PLL was dually innervated by two distinctive systems of nociceptive fibers. One of the systems was polysegmentally innervated and closely associated with autonomic innervation, whereas the other was unisegmentally innervated and not associated with autonomic fibers. CONCLUSION: Pathogenesis of low back pain can be better understood if the presence of the two distinctive nerve systems innervating the posterior longitudinal ligament is taken into account.

Animals↗

Chaperone function of calreticulin when expressed in the endoplasmic reticulum as the membrane-anchored and soluble forms.

A unique type of chaperone that requires glucose trimming of the target proteins has been shown to be important for their maturation in the endoplasmic reticulum (ER). Calnexin, an ER membrane chaperone, is the first example of such a class. Here, we focus on calreticulin, a major ER luminal protein, which shares with calnexin two sets of characteristic sequence repeat. We evaluated the chaperone function of calreticulin by expressing it on the ER luminal membrane surface. We constructed a membrane-anchored calreticulin chimera by fusing truncated calreticulin to the membrane-anchoring tagged segment of calnexin. When expressed in HepG2 cells, the calreticulin chimera transiently interacted with a set of nascent secretory proteins in a castanospermine-sensitive manner. The spectrum of proteins recognized by the membrane-anchored calreticulin was remarkably similar to that observed with calnexin. Next, we tested if such a chaperone function of calreticulin is expressed at its physiological location. Luminally expressed calreticulin preferentially bound to nascent transferrin and released it upon chase. Association with other calnexin ligands was observed, however, at low efficiencies. Interactions were abrogated by castanospermine treatment. We conclude that calreticulin per se is another chaperone with apparently the same characteristics as calnexin and selectively interacts with nascent transferrin in the lumen, suggesting that calreticulin may cover the diversity of maturations.

Amino Acid Sequence↗

Induction of endometrial adenocarcinomas by a single intra-uterine administration of N-ethyl-N'-nitro-N-nitrosoguanidine to aged Donryu rats showing spontaneously persistent estrus.

Induction of endometrial adenocarcinomas by a single intra-uterine administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) to aged rats was examined. Donryu rats showing spontaneously persistent estrus were given a single intra-uterine administration of ENNG (20 mg/kg) at 10 months (44 weeks) of age. At the termination of the experiment (week 34 after the ENNG-treatment), 22% and 13% incidences of endometrial adenocarcinomas were observed in the experimental and control groups, respectively, the difference being without significance. No variation was found in the endocrine environment between experimental and non carcinogen-treated control animals throughout the experimental period. These results show that ENNG-treatment alone is not sufficient in aged rats for high induction of endometrial carcinomas. Comparison of the data with those from our previous studies, in which ENNG was given at a young age (10 weeks of age), indicates that young rats may be more sensitive than their old counterparts.

Adenocarcinoma↗

Genetic dissection of susceptibility to radiation-induced apoptosis of thymocytes and mapping of Rapop1, a novel susceptibility gene.

Genetic dissection of susceptibility to radiation-induced apoptosis of thymocytes was performed by counting dead cells in histologically processed thymuses after 0.5 Gy of whole-body X-irradiation, using recombinant congenic (CcS/Dem) strains derived from inbred mouse strains BALB/cHeA (susceptible) and STS/A (resistant). A high (8/20) number of strains with lower dead cell scores than BALB/cHeA among CcS/Dem recombinant congenic strains (RCS), which contain 12.5% of STS/A genome in the genetic background of BALB/cHeA strain, indicates that the difference between BALB/cHeA and STS/A is caused by several genes and that susceptibility probably requires BALB/cHeA alleles at more than one locus. Similar results were obtained with CXS/Hg recombinant inbred (CXS/Hg) strains. Analysis of F2 hybrids between BALB/cHeA and CcS-7, one of the CcS/Dem strains that showed lower dead cell scores than BALB/cHeA, demonstrated that a novel gene (Rapop1, radiation-induced apoptosis 1) controlling susceptibility to radiation-induced apoptosis in the thymus is located in the proximal region of mouse chromosome 16.

Animals↗

Intact antigen presentation for Epstein-Barr virus (EBV)-specific CTL by a lymphoblastoid cell line established from a patient with severe chronic active EBV infection.

Severe chronic active Epstein-Barr virus (EBV) infection is a lymphoproliferative disease characterized by extremely high antibody titers to EBV, fever, lymphadenopathy, hepatosplenomegaly, and pancytopenia, without any prior immunological abnormality. A spontaneous lymphoblastoid cell line was established from a 4-year-old boy with severe chronic active EBV infection. Immunofluorescence and Western blotting analyses showed that the cell line was of B cell origin and expressed Epstein-Barr nuclear antigens 1, 2 3a, 3b and 3c, and latent membrane protein 1, which are reported to be targets for EBV-specific cytotoxic T lymphocytes (CTL). The cytotoxicity of peripheral blood mononuclear cells derived from the patient and his HLA-identical sister was assayed against the cell line. The cell line was recognized and killed by anti-EBV CTL derived from the HLA-identical sister, but the patient's peripheral blood mononuclear cells had no cytotoxicity. We conclude that antigen presentation in the EBV-infected cells from the patient is intact and sufficient for generation of an EBV-specific CTL response. These observations suggest that severe chronic active EBV infection may not be caused by impaired EBV-antigen presentation of the infected cells but by impaired cellular immune responses to the virus. Our results also suggest the therapeutic possibility that this disease may be treated by adoptive transfer of EBV-specific CTL or bone marrow transplantation from an HLA-matched donor whose immune response to EBV is intact.

Animals↗

Neurofibroma of the stomach: report of a case.

We report herein the case of a 71-year-old-Japanese woman who was admitted to hospital for surgical treatment of a lower abdominal tumor. At laparotomy the tumor was found to be pedunculated and growing extramurally from the greater curvature of the stomach. Thus, a wedge resection of the stomach, including the mass, was performed. The tumor measured about 9 x 8 x 7 cm and histological examination of the resected specimen showed that the main elements consisted of wavy, long-spindled cells, which crossed irregularly, indicating that it was palisading negative. Immunohistochemically, the specimen was positive for both S-100 protein and Alcian blue. From these findings, the tumor was histologically diagnosed as a neurofibroma. The patient had an uneventful postoperative course and no signs of recurrence have been recognized in the 3 years since her operation.

Aged↗

Semotiadil inhibits the development of right ventricular hypertrophy and medial thickening of pulmonary arteries in a rat model of pulmonary hypertension.

This study was designed to compare the effects of semotiadil, a novel calcium antagonist, with those of diltiazem on the development of right ventricular hypertrophy and medial thickening of pulmonary arteries in a rat model of pulmonary hypertension. Pulmonary hypertension was induced by a single injection of monocrotaline (80 mg/kg). Twenty-four hours later (day 1), oral administration of semotiadil (10, 30, or 100 mg/kg per day) or diltiazem (100 or 300 mg/kg per day) was initiated. The wall thickness of the right ventricle (RV), the RV myocardial fiber diameter, the percent medial pulmonary artery thickness, and the percent area of smooth muscle in pulmonary arteries were determined on day 28. The magnitude of all parameters was significantly less in the group of seven rats that received semotiadil at 100 mg/kg per day than in the group of seven rats treated with diltiazem at 300 mg/kg per day. Semotiadil at 100 mg/kg per day inhibits the development of RV hypertrophy and medial thickening of pulmonary arteries significantly more effectively than diltiazem at 300 mg/kg per day.

Administration, Oral↗

Effects of Na(+)-H+ exchange blocker amiloride on left ventricular remodeling after anterior myocardial infarction in rats.

We investigated the effects of amiloride, a Na(+)-H+ exchange blocker, on ventricular remodeling in an infarcted rat model. In the amiloride group, the left descending coronary artery was ligated and rats were given amiloride (1 mg/kg/day, n = 11) in their drinking water for 4 weeks. In the control group, rats were given water for 4 weeks (n = 8) after myocardial infarction. The rats were killed on day 28. Both the ratio of heart weight to body weight and that of left ventricular weight to body weight were significantly less in the amiloride group (p < 0.05). The diameter of a myocardial fiber in the region adjacent to the operated area was significantly reduced in the amiloride group compared with the control group (p < 0.05). Left ventricular cavity dimension was significantly smaller in the amiloride group than that in control group (p < 0.05). Our findings suggest that amiloride prevents ventricular remodeling after myocardial infarction.

Amiloride↗

Purification and characterization of a novel 70-kDa brain protein associated with seizure activities.

Using ion exchange HPLC and ammonium sulfate precipitation, we have purified a 70-kDa protein (P70) specific to the cobalt-induced epileptogenic cortex of rat cerebrum and determined certain of its biochemical properties. P70 has a similar isoelectric point (pI; 4.6-4.8), amino acid composition and N-terminal amino acid sequence to rat serum albumin (RSA). Intracortical application of purified P70 to the motor area of normal rat cerebrum induces both ECoG seizure discharges and behavioral seizures. The data suggest that P70 is a novel albumin-like protein linked to the generation of seizure activities. However, it can be clearly distinguished from RSA, since it is able to produce seizure, is a glycoprotein and can be readily separated from RSA by 2-dimensional electrophoresis.

Albumins↗

Heterotopic gastric mucosa of the gallbladder.

A case of heterotopic gastric mucosa in the fundus of the gallbladder is reported. A 23-year-old man, who had been healthy and asymptomatic, visited our hospital because of abnormal findings in a liver enzyme test given during a routine health screening. Ultrasonography demonstrated a highly echogenic polypoid mass in the fundus of the gallbladder. The gallbladder mass was confirmed by both computed tomography and intravenous cholangiogram. After a 10-month follow up, laparoscopic cholecystectomy was performed. Intraoperative touch smear cytology of this lesion revealed class II cells. The surgical specimen revealed a 15 x 10 x 5 mm polypoid lesion in the fundus, with no gallstones in the gallbladder. Histologically, the polypoid lesion consisted of both fundic type and pyloric type gastric glands located in the mucosa of the gallbladder. In the literature, 42 cases of heterotopic gastric mucosa of the gallbladder have been reported, only 3 of which, including this present case, were found incidentally, with no apparent symptoms.

Adult↗

Adenomyoma of the common hepatic duct.

A very rare case of adenomyoma of the common hepatic duct is described. A 54-year-old woman was admitted with impending obstructive jaundice secondary to adenomyoma of the common hepatic duct. Our impression, formulated from her clinical presentation, endoscopic investigations, and biochemical and radiological findings, was a cancer of the proximal common hepatic duct. The patient was treated successfully by combination surgical resection and hepaticojejunostomy. Despite our obtaining an intraoperative frozen section, final histological examination was required to confirm the diagnosis. The patient remains well 16 months postoperatively. A survey of the world literature revealed that this is the second report of adenomyoma occurring in the common hepatic duct.

Adenomyoma↗

Sandostatin inhibits development of medial proliferation of pulmonary arteries in a rat model of pulmonary hypertension.

We investigated the effects of subcutaneous administration of 50 and 100 micrograms/kg/day of sandostatin on monocrotaline-induced medial proliferation of pulmonary arteries and right ventricular overload in rats. In a dosage of 100 micrograms/kg/day, sandostatin significantly reduced right ventricular systolic pressure, the mass ratio of the right ventricular free wall to the left ventricle, the right ventricular wall thickness, the right ventricular myofiber diameter, the percent medial pulmonary artery thickness, the percent area of smooth muscle cell, and proliferating cell nuclear antigen activity. Our results suggest that sandostatin inhibits development of medial proliferation of pulmonary arteries and right ventricular overload in a dosage of 100 micrograms/kg/day.

Animals↗

Reactivity of anti-erythrocyte antibody induced by Babesia gibsoni infection against aged erythrocytes.

Effects of ageing treatment of erythrocytes to binding activity of the anti-erythrocyte antibody(s) in the serum of dogs infected artificially with Babesia gibsoni were examined by enzyme-linked immunosorbent assay (ELISA) using fixed cell antigen. When erythrocytes made senescent by two artificial ageing treatments, one of which was storing erythrocytes at 37 degrees C in medium for some days and the other was oxidation of erythrocytes with phenylhydrazine, reactivity of anti-erythrocyte antibody(s) in the infected serum to both types of treated erythrocytes was increased. These results suggest that such antibody(s) could play a role as one of the causes of anemia in canine babesiosis.

Anemia↗

Contribution of cyclic GMP generation to the relaxation by nipradilol in the rabbit aorta.

1. Contribution of cyclic GMP generation to the relaxation by nipradilol of vascular smooth muscle was studied in the isolated rabbit aorta contracted by phenylephrine (10(-7) M) or prostaglandin F2 alpha (PGF2 alpha, 3 x 10(-6) M). 2. Nipradilol-induced relaxation in both contractions and increase in cyclic GMP content were inhibited by methylene blue (10(-5) M). 3. The relations between the increase in cyclic GMP and the relaxation produced by nipradilol and nitroglycerin were fitted to sigmoid curves. The increase in cyclic GMP at 50% relaxation by nipradilol was smaller than that by nitroglycerin (1.2-fold increase as against 3-fold increase). 4. These results suggest a smaller contribution of cyclic GMP generation through activation of soluble guanylate cyclase to nipradilol-induced relaxation in the rabbit aorta.

Adrenergic beta-Antagonists↗

Contribution of activation of K+ channels to glyceryl trinitrate-induced relaxation of rabbit aorta.

1. Possible contribution of K+ channel opening to the relaxation by glyceryl trinitrate (GTN) was examined using isolated rabbit aorta. 2. While glibenclamide and apamin failed to affect relaxation by GTN, both charybdotoxin (ChTx) and iberiotoxin (IbTx) effectively attenuated GTN-induced relaxation. 3. The increase in cGMP produced by GTN was not attenuated by ChTx and IbTx. 4. The inhibitory effect of ChTx on GTN-induced relaxation was not reduced in the presence of zaprinast, indicating that cGMP but not GMP was responsible for activation of the K+ channel. 5. Okadaic acid, a selective inhibitor of protein phosphatase 2A, had no effect on the relaxation by GTN. These results indicate that, though small in degree, activation of a ChTx-sensitive K+ channel (large conductance Ca(2+)-activated K+ channel) is involved in the GTN-induced relaxation in rabbit aorta.

3',5'-Cyclic-GMP Phosphodiesterases↗