Biomedical subjects

S Shimada

Publications and source records attributed to S Shimada.

At least 181 records · Page 10Linked to original sources

PubMed1996

GLAST mRNA expression in the periventricular area of experimental hydrocephalus.

Glutamate transporters play an important role in maintaining the extracellular glutamate concentration below the neurotoxic level. We investigated the expression of glutamate/aspartate transporter (GLAST) mRNA in the periventricular region of rats with kaolin-induced hydrocephalus by in situ hybridization (ISH). The density of GLAST mRNA-positive cells and the level of hybridization signals per positive cell significantly increased in the acute stage of hydrocephalus. We also demonstrated co-localization of GLAST mRNA and GFAP immunoreactivity in a single cell using the combined methods of ISH and immunohistochemistry. These findings suggest that GLAST is expressed in the reactive astrocytes of the periventricular area and regulates extracellular glutamate concentration after hydrocephalic brain injury.

Amino Acid Transport System X-AG↗

PubMed1996

Cellular localization of Na+/MYO-inositol co-transporter mRNA in the rat brain.

The distribution of Na+/MYO-inositol co-transporter (SMIT) mRNA in the rat brain was studied by in situ hybridization histochemistry. The highest levels of SMIT mRNA were observed in the choroid plexus. Intense hybridization signals were found in the pineal gland, the area postrema, the hippocampus, the locus coeruleus, the suprachiasmatic nucleus, the olfactory bulb and the Purkinje cell and granule cell layers of the cerebellum. Low to moderate levels of labelling were detected in almost all neurones and small glia-like cells throughout the brain. These results suggest that almost all cells in the brain possess an SMIT-mediated osmotic and ionic regulatory system, and uneven densities of positive SMIT mRNA signals may reflect the differences in sensitivity of the cells to osmotic and ionic changes and also reflect differences in permeability of capillaries.

Animals↗

PubMed1996

Expression of Na+/myo-inositol cotransporter mRNA in the inner ear of the rat.

We have demonstrated the cellular localization of Na+/myo-inositol cotransporter (SMIT) mRNA in the rat inner ear by in situ hybridization. In the cochlea, the most intense SMIT mRNA signals were observed in fibrocytes of the spiral ligament, moderate signals were found in the spiral limbus, inner hair cells and spiral ganglion cells, while the hybridization signals were almost undetectable in the marginal cells of the stria vascularis and outer hair cells. In the vestibular system, moderate hybridization signals were found in the sensory epithelium, fibrocytes and vestibular ganglion cells. These findings suggest that SMIT plays an important role in maintenance of intracellular ionic balance and cell volume in the inner ear, especially in the fibrocytes associated with generation of the ion gradients between the endolymph and perilymph.

Animals↗

PubMed1996

Expression of Na+/myo-inositol cotransporter mRNA in normal and hypertonic stress rat eyes.

We studied the localization of Na+/myo-inositol cotransporter (SMIT) mRNA in normal and hypertonic stress rat eyes by in situ hybridization histochemistry using cRNA probes. SMIT mRNA signals were observed in the iris-ciliary body, the lens epithelial cells, and the ganglion cell layer and the inner nuclear layer of the retina. There was a rapid increase on SMIT mRNA in the retina of hypertonic stress rats compared with control rats. These findings suggest that Na+/myo-inositol cotransporter gene expression is osmotically regulated in vivo to protect retinal neuronal function against hypertonic stress.

Animals↗

PubMed1996

Widespread brain distribution of mRNA encoding the orphan neurotransmitter transporter v7-3.

Orphan transporter v7-3 is a member of a new subfamily of Na+, Cl- dependent neurotransmitter transporters with two large extracellular loops. Distribution of v7-3 mRNA was investigated in the rat brain. In situ hybridization study revealed that v7-3 mRNA was widely distributed in the rat central nervous system, including the olfactory bulb, the hypothalamus, the cerebral cortex, the hippocampus, and the cerebellum. In addition, intense v7-3 mRNA expression was found in the motor nuclei including the oculomotor nucleus, abducens nucleus, trigeminal motor nucleus, facial nucleus, hypoglossal nucleus and ventral horn of spinal cord. Intense hybridization signals were also observed in the nuclei containing monoaminergic neurons, such as locus coeruleus, the substantia nigra pars compacta, the ventral tegmental area, the dorsal raphe nucleus and the median raphe nucleus. This multifocal and broad nature of the v7-3 distribution suggests widespread roles for this gene product in neurons mediating several important brain function.

Animals↗

PubMed1996

Expression of dopamine transporter mRNA and its binding site in fetal nigral cells transplanted into the striatum of 6-OHDA lesioned rat.

Neurological disorders in rat model of hemi-Parkinson's disease can be compensated by the transplantation of fetal nigral cells. However, the role of the dopamine transporter (DAT) in this recovery has not been clarified. To clarify this mechanism, we examined the expression of DAT in the caudate putamen (CPu) by in situ hybridization histochemistry (mRNA) and autoradiography (using the ligand [125I] beta-CIT, which labels DAT) and compared them with the recovery of motor disturbance revealed with methamphetamine-induced rotation. Models were made with the stereotaxic injection of 6-hydroxydopamine into the left side of the substantia nigra pars compacta. Cell suspensions from rat fetus (embryonic day 14-15) were transplanted into the lesioned side of CPu. Methamphetamine-induced rotation, expression of DAT mRNA, and [125I] beta-CIT binding were evaluated 2, 4 and 12 weeks after the transplantation. Methamphetamine-induced rotation recovered partly in the 2nd week and significantly in the 4th week. [125I] beta-CIT binding increased with time and the dense binding was detected 4 and 12 weeks after the transplantation. In all transplanted rats, cells expressing DAT mRNA were found in CPu. These results indicated that transplanted fetal dopaminergic cells maturated in CPu of host animals and extended nerve terminals where high density of DAT binding sites were found.

Animals↗

PubMed1996

Rapid and transient up-regulation of Na+/myo-inositol cotransporter transcription in the brain of acute hypernatremic rats.

The osmoregulatory system is well developed in the brain. Osmolytes contribute to maintenance of cell volume and cellular functions without changing intracellular ionic composition. Myo-inositol is regarded as one of the major osmolytes in the brain. In the present study, we investigated the changes in expressions of sodium myo-inositol cotransporter (SMIT) mRNA in the brain of acute hypernatremic rats by in-situ hybridization and Northern blot methods. Under moderate acute hypernatremic conditions, SMIT mRNA level increased markedly at 1 h and returned to almost control levels at 3 h, in accordance with plasma Na+ concentrations. Especially, distinct increases in SMIT mRNA expression were observed in the granule cells and glial cells in the cerebellum. These findings indicate that SMIT plays an important role in osmoregulation, especially in the early stages of acute hypernatremia in the brain.

Animals↗

PubMed1996

Changes in glutamate/aspartate transporter (GLAST/GluT-1) mRNA expression following facial nerve transection.

Expression of glutamate/aspartate transporter (GLAST/GluT-1) was investigated in the axotomized facial nucleus by in-situ hybridization. Hybridization signals for GLAST mRNA were almost undetectable in the facial nucleus of sham-operated animals. However, the hybridization signals were seen from 3 days after facial nerve transection onward in the nucleus of the affected side. These signals lasted at least 5 weeks. Microautoradiograms showed that small non-neuronal cells in the ipsilateral facial nucleus expressed signals of GLAST mRNA after axotomy. These findings suggest that non-neuronal cells, presumably astrocytes, may protect axotomized motor neurons against glutamate toxicity via up-regulation of GLAST in the facial nucleus.

Amino Acid Transport System X-AG↗

PubMed1996

Clinical observation of spontaneous anginal attacks and multivessel spasm in variant angina pectoris with normal coronary arteries: evaluation by 24-hour 12-lead electrocardiography with computer analysis.

OBJECTIVES: Using a new, computerized 24-h 12-lead electrocardiographic (ECG) recording and analysis system (the EAGLE system), we sought to evaluate the clinical manifestations of ischemic episodes in patients with variant angina and normal coronary arteries. BACKGROUND: Although the prognosis of variant angina without significant organic stenosis is generally good, the incidence of multivessel spasm, a major prognostic factor, is surprisingly high in provocation tests. METHODS: A total of 122 patients with suspected variant or unstable angina underwent 24-h examination with the EAGLE system and two-channel Holter monitoring. Thirty patients in this group were diagnosed as having variant angina with normal or nearly normal coronary arteries. Twenty-two (73%) of these 30 patients developed anginal attacks with ST segment elevation during monitoring and were enrolled in the study. RESULTS: The 22 patients had a total of 138 episodes of transient ST segment elevation and 13 episodes of ST segment depression. No arrhythmias were observed during ST segment depression, but 26 episodes of ST segment elevation (19%) were associated with arrhythmias: 7 with premature ventricular contractions, 3 with ventricular bigeminy, 3 with complete atrioventricular (AV) block, 1 with complete AV block and couplets of premature ventricular contractions and 12 with marked sinus bradycardia (< 45 beats/min). Ten (45%) of the 22 patients had multivessel spasm. We observed three different patterns of multivessel spasm: 1) spasm at a different site on different occasions (migratory spasm); 2) spasm that sequentially affected two different sites; 3) simultaneous spasm at more than one site. The duration of ST segment elevation was much longer in patients with sequential and simultaneous spasm than in those with single-vessel spasm, and arrhythmias were more frequent during these two types of multivessel spasm. CONCLUSIONS: Although the prognosis of multivessel spasm is believed to be poor, this may not necessarily be so. Anginal attacks due to sequential and simultaneous multivessel spasm seem to be more dangerous than those involving single-vessel spasm or migratory multivessel spasm.

Aged↗

PubMed1996

Expression of betaine transporter mRNA: its unique localization and rapid regulation in rat kidney.

Betaine is a major compatible osmolyte in the renal medulla. It is taken up into cells via the betaine gamma-amino-n-butyric acid transporter (BGT-1). We investigated the localization of BGT-1 mRNA and its acute regulation by NaCl and furosemide administration. In situ hybridization revealed that BGT-1 mRNA is predominantly present in the outer medulla and papilla. Less intense signals were seen in the inner medulla and no signals were found in the cortex. Microscopic examination suggested that intense signals were present in the medullary thick ascending limbs of Henle's loop (MTAL) and the inner medullary collecting ducts (IMCD). A reverse transcription and polymerase chain reaction assay of individual microdissected segments along the nephron confirmed its localization. Intraperitoneal administration of NaCl rapidly increased the signal in the MTAL, and furosemide prevented the increase in BGT-1 mRNA by NaCl loading. In contrast, BGT-1 mRNA in the IMCD is less sensitive to these kinds of acute regulation. These results suggest that BGT-1 expression in the MTAL is rapidly regulated in response to the magnitude of NaCl absorption, as suggested for the expression of Na+/myo-inositol cotransporter.

Aldehyde Reductase↗

PubMed1996

Development and cytolytic function of intestinal intraepithelial T lymphocytes in antigen-minimized mice.

Intraepithelial T lymphocytes in the small intestine (IEL) consist of alpha beta T-cell receptor (TCR)-bearing T cells (alpha beta-IEL) and gamma delta TCR-bearing T cells (gamma delta-IEL). Development and cytolytic activation of alpha beta-IEL sharply attenuate in germ-free (GF) mice fed a natural diet (Nat-GF), but the number and cytotoxicity of gamma delta-IEL are comparable between conventional (CV) and Nat-GF mice. In this report, we compared the properties of IEL in Nat-GF mice and GF mice fed antigen-minimized diet (AgM-GF mice) of C57BL/6 strain to evaluate an influence of gut antigenic load on IEL development. Numbers of alpha beta-IEL and gamma delta-IEL in AgM-GF mice were less by 1.9- and 1.4-fold than those in Nat-GF mice, respectively. Significant decreases in the proportions of CD4+8-, CD4-8 alpha beta +, and CD4+8+ subsets and a resultant increase in the ratio of CD4-8 alpha alpha + subset were evident in alpha beta-IEL of Nat-GF mice compared with CV mice, but the subset constitution of alpha beta-IEL was similar between Nat-GF and AgM-GF mice. In contrast, relative composition of gamma delta-IEL was not different between CV, Nat-GF, and AgM-GF mice. alpha beta-IEL displayed low cytolytic activity in Nat-GF mice and were almost deprived of their cytotoxicity under the antigen-minimized condition. While gamma delta-IEL were strongly cytolytic in Nat-GF mice their cytolytic activity was remarkably reduced in AgM-GF mice. These results indicate that gamma delta-IEL are activated independently of microbial colonization in the gastrointestinal tract but their activation occurs in response to the exogenous antigenic substances other than live micro-organisms.

Animals↗

PubMed1996

Reg gene expression is increased in rat gastric enterochromaffin-like cells following water immersion stress.

BACKGROUND & AIMS: Reg gene has been isolated from regenerating rat pancreatic islets, and subsequent studies have shown a trophic effect of Reg protein on islet cells. However, little is known about the role of Reg protein in the stomach. The aim of this study was to clarify the localization of Reg messenger RNA (mRNA) and its product in the stomach and to examine changes in the level of their expression during regeneration of gastric mucosal cells. METHODS: Gastric lesions were experimentally induced in Sprague-Dawley rats by water immersion stress. Northern blot analysis and in situ hybridization studies were performed to examine changes in mRNA levels. Immunohistochemical studies were performed to identify the cellular localization and to investigate the change in Reg protein level. RESULTS: Reg mRNA and its product were distributed in the basal part of the oxyntic mucosa and were expressed mainly in enterochromaffin-like cells. Levels of both Reg mRNA and its product were markedly increased in the water immersion-induced gastric lesions. CONCLUSIONS: Reg mRNA and its product are expressed in gastric enterochromaffin-like cells, and their levels are increased during the healing process of water immersion-induced gastric lesions.

Animals↗

PubMed1996

Knee laxity in patients with osteoarthritis and rheumatoid arthritis.

Thirty-four patients with osteoarthritis (OA) and 32 patients with rheumatoid arthritis (RA) were studied to determine the effects of OA and RA on the laxity of the knee joints. Laxity was measured with the Genucom Knee Analysis System. The antero-posterior laxity of the OA and RA knees was greater than the control, normal knees in the early stage, and decreased with the severity of disease in OA, but not in RA. Severe OA and RA were associated with a restricted internal-external rotation at the knee joint compared with the control. Internal-external rotation decreased with worsening of both diseases. Varus-valgus laxity tended to increase slightly with the severity of disease. While the morphological changes of the cruciate ligaments in advanced OA and RA were not statistically different, the laxity of OA-afflicted knees was affected slightly by the severity of the damage to the cruciate ligaments.

Adult↗

PubMed1996

A new device for the treatment of coloproctostomic stricture after double stapling anastomoses.

OBJECTIVE: A new device of staple cutter was developed to evaluate the clinical effect for the treatment of rectal stricture after the double stapling anastomosis. SUMMARY BACKGROUND DATA: The double stapling technique has become an established reconstruction method for patients with low anterior resection. The major complication of anastomotic stricture associated with circular stapling has been reported to be harmful and distressing. Because underlying mechanisms of stricture are not well understood, no prophylactic means have been developed and this results in postoperative dilation still being the only treatment available. Although various dilation methods are used for the treatment of stricture, none is fully satisfactory. METHODS: Low anterior resection was performed in 30 patients with rectal carcinoma using a double stapling technique. First, the incidence of the anastomotic stricture and the clinical factors that contribute to the stricture formation were studied. Second, the clinical effects and advantages of the treatment of coloproctostomic stricture using the newly developed device (staple cutter) were evaluated. RESULTS: Nine (30%) of 30 patients had anastomotic stricture with the symptom of distressing frequent bowel movement. There was no significant relation between the clinical factors and the stricture when compared with that of nonstricture patients. Excellent dilation was performed in all of the nine strictures using the staple cutter, and the symptom of stricture disappeared dramatically in eight patients (89%) within 1 week. The recurrence of stricture occurred in two patients; however, it has not been observed after one further use of this treatment. The staple cutter is safe and easy to use even at the bedside, and except for a conventional anoscope, no special equipment, including fluoroscope, was needed. CONCLUSIONS: From the significant effects and advantages, the procedure using staple cutter is recommended highly for the treatment of circular stapling anastomotic stricture of the rectum.

Adult↗

PubMed1996

Induction of Na+/myo-inositol cotransporter mRNA after focal cerebral ischemia: evidence for extensive osmotic stress in remote areas.

Myo-inositol is one of the major organic osmolytes in the brain. It is accumulated into cells through an Na+/ myo-inositol cotransporter (SMIT) that is regulated by extracellular tonicity. To investigate the role of SMIT in the brain after cerebral ischemia, we examined expression of SMIT mRNA in the rat brain after middle cerebral artery occlusion, which would reflect alteration of extracellular tonicity. The expression of SMIT mRNA was markedly increased 12 h after surgery in the cortex of the affected side and lasted until the second day. Increased expression was also found in the contralateral cingulate cortex. Up-regulated expression was found predominantly in the neurons in remote areas, although nonneuronal cells adjacent to the ischemic core also expressed this mRNA. These results suggest that cerebral ischemia causes extensive osmotic stress in brain and that the neuronal cells respond to this stress by increasing SMIT expression.

Animals↗

PubMed1996

Haemodynamic effects of differing blood transfusion rates in infants less than 1500 g.

OBJECTIVE: To investigate whether the haemodynamic effects of the standard 2-3 h blood transfusion increases the risk for intraventricular haemorrhage (IVH) and patent ductus arteriosus (PDA) in very low birthweight infants. METHODOLOGY: In a randomized controlled study, haemodynamic changes using slow and rapid transfusion were compared. Twenty-seven very low birthweight infants were divided between 12h (n = 14) and 3h (n = 13) transfusion groups. Blood pressure, ejection fraction (EF), anterior cerebral artery pulsatility index (PI), blood gases, serum electrolytes and haematocrit were measured pre- and post-transfusion. Infectious status was also monitored. RESULTS: Blood pressure (48.1/25.5 vs 55.7/30.2 mmHg) and EF (0.68 vs 0.73) increased significantly during rapid transfusion (P<0.01) but remained stable with slow transfusion. Serum potassium, base excess and incidence of infection did not increase in either group. CONCLUSIONS: Slow transfusion causes less haemodynamic disturbance than rapid transfusion, thereby preventing the potential risk for IVH and PDA.

Blood Transfusion↗

PubMed1996

Expression, but lack of calcium mobilization by high-affinity IgE Fc epsilon receptor I on human epidermal and dermal Langerhans cells.

In atopic dermatitis (AD) patients, IgE molecules are demonstrated on the surface of Langerhans cells (LC). Fc epsilon RI molecules, which are present on the surface of LC in AD patients as well as normal individuals, are responsible for this binding. In this study, we have investigated phenotypic and functional characteristics of Fc epsilon RI on epidermal and dermal cell populations. Epidermal and dermal cell suspensions were prepared enzymatically with dispase followed by either trypsin or collagenase treatment, respectively. Peripheral blood basophils were negatively selected by excluding other leukocytes with surface marker staining. Consistent with previous reports, both peripheral blood basophils and epidermal LC were positively stained with anti Fc epsilon RI monoclonal antibody. In addition, an Fc epsilon RI positive population was demonstrated among dermal HLA-DR positive cells. These cells express significant amounts of HLA-DR molecules (DRHi) and co-express CD 1 a molecules, which identifies them as LC-like dendritic APC of the dermis. No other Fc epsilon RI positive population was found in the other dermal DRMid or DR- populations, except for a minor DRLo population, presumably mast cells. To analyze whether these Fc epsilon RI molecules are signal transducing for LC, intracellular calcium mobilization after crosslinking of Fc epsilon RI was measured with flow cytometry. Following crosslinking, peripheral blood basophils clearly increased intracellular calcium. On the other hand, neither normal epidermal LC nor dermal DRHiCD1a + cells changed their intracellular calcium level after Fc epsilon RI crosslinking. These data indicate that normal epidermal and dermal LC, but not basophils, are resistant to calcium flux following Fc epsilon RI engagement.

Adult↗

PubMed1996

Schizosaccharomyces pombe is more sensitive to pressure stress than Saccharomyces cerevisiae.

The effects of hydrostatic pressure on ultrastructure, microtubules and microfilaments of Schizosaccharomyces pombe were investigated by fluorescence microscopy, conventional electron microscopy and immunoelectron microscopy. Cells were treated with hydrostatic pressure from 0.1 to 400 MPa for 10 min at room temperature. The nuclear membrane was disrupted at above 100 MPa. At 150 MPa the matrixes of mitochondria had an electron dense area. At 250 MPa the cytoplasmic substances changed dramatically, the cellular organelles could hardly be detected and the fragmented nuclear membrane was barely visible. The fluorescence in alpha-tubulin was lost in most of the cells at 100 MPa. The gold particles for anti alpha-tubulin were not visible in the cells at the same level. Cell cycle specific actin distribution was lost even at 50 MPa, although actin dots localized at the central region remained unchanged. Thick actin cables appeared at 100 MPa. Complete depolymerization of F-actin was observed at 150 MPa. These results suggest that S. pombe cells were more sensitive than Saccharomyces cerevisiae cells. The damage to microtubules and nuclear membrane caused by hydrostatic pressure was though to be followed by breakdown of nuclear division apparatus and the inhibition of nuclear division. This damage might contribute to the frequent formation of polyploidy in S. pombe.

Actin Cytoskeleton↗