Biomedical subjects

T Asano

Publications and source records attributed to T Asano.

At least 397 records · Page 22Linked to original sources

PubMed1995

Fractures of the floor of the anterior cranial fossa.

We treated 28 patients with anterior cranial fossa floor fractures. Computed tomography (CT) scans adjusted to bone density disclosed three fracture types: (1) penetrating fractures through the orbita or ethmoid sinus; (2) simple or multiple linear fractures; and (3) extensive comminuted anterior cranial fossa floor fractures. Thirteen patients underwent emergent surgery for treatment of open depressed fractures (most common in type 3 fractures), for foreign bodies (in type 1 fractures), and for optic canal decompression. Large dural lacerations were always present in patients with type 3 fractures, and repairs were made with dural substitutes. Only one patient developed postoperative cerebrospinal fluid leakage. Nine (32%) of the patients in our series had visual involvement, but visual acuity recovered or improved in six patients. Our study shows that initial neuroradiologic evaluation with CT scans is important in patients with frontobasal fractures, and that secure dural repair during primary operation helps prevent cerebrospinal fluid leakage.

Adolescent↗

PubMed1995

Frequent p53 accumulation in the chronically sun-exposed epidermis and clonal expansion of p53 mutant cells in the epidermis adjacent to basal cell carcinoma.

p53 expression was studied immunohistochemically to identify a precursor lesion of basal cell carcinoma (BCC) in the epidermis adjacent to BCC. With two different anti-p53 antibodies of CM1 and DO7, p53 expression was frequently detected in the epidermis adjacent to BCCs arising on the face and in the normal epidermis with usual sun exposure. In the epidermis adjacent to BCC, stained cells were occasionally clustered in a small area, but no cluster was found in the normal epidermis with usual sun exposure. The expression was less frequent in the normal epidermis with rare sun exposure. Ten cases of normal skin with usual sun exposure, showing CM1 staining in the epidermis, were screened for p53 gene mutations with polymerase chain reaction-single-strand conformation polymorphism analysis using DNAs obtained from the epidermis. No mutation was detected in exons 2 to 10 of the p53 gene in these 10 cases. The epidermis flanking three BCCs that was stained with CM1, on the other hand, carried a missense mutation of C to G transversion at a dipyrimidine site of codon 249. This alteration replaced arginine with threonine. The mutation of codon 249 was not detected in the three BCCs. Our results first suggest that ultraviolet light irradiating the skin in a daily life induces p53 accumulation in the epidermis and secondly that the frequent clonal expansion of p53 mutant cells occurs in the epidermis adjacent to BCCs. This clonal expansion of mutant p53 may provide a molecular basis for high risk of developing subsequent new skin cancers in patients with BCC.

Adolescent↗

PubMed1995

Enhancement of the antitumor effect by combined use of high-energy shock waves and ATX-70.

The antitumor effects of high-energy shock waves (HESW) in combination with ATX-70 [a gallium-porphyrin complex, 2,4-bis(1-decyloxyethyl)-Ga(III)-1,3,5,8-tetramethylporphyrin++ +-6, 7-dipropionyl diaspartic acid [sequence: see text] were investigated. In vitro, the cell damage to mouse MH134 hepatoma after HESW treatment was enhanced by adding ATX-70. In vivo, HESW and ATX-70 combination therapy inhibited cell growth. However, neither HESW treatment alone nor ATX-70 treatment alone inhibited cell growth. These results imply that the antitumor effects of HESW and ATX-70 combined therapy are caused by activation of ATX-70 by HESW.

Animals↗

PubMed1995

Superoxide anions in the pathogenesis of talc-induced cerebral vasocontraction.

We have recently reported that sustained contraction of the canine basilar artery induced by the intrathecal injection of talc (crystallized hydrous magnesium silicate) mimicked delayed vasospasm following subarachnoid haemorrhage. The present study aims to examine the pathomechanism underlying talc-induced vasocontraction, from the viewpoint of free radical theory, which has been established as a cause of delayed vasospasm. We estimated the effects of a prolonged intrathecal infusion of human recombinant Cu/Zn superoxide dismutase (hr SOD) on the contraction of the basilar artery caused by the intrathecal injection of talc in beagle dogs, which were assigned to the three groups: G1, sham operation with saline treatment; G2, talc injection with saline treatment; and G3, talc injection with 2 ml of hr SOD (7 x 10(4) U/ml) treatment. Talc administration resulted in the reduction in the angiographic calibre of the basilar artery by 63 and 61% on days 3 and 7 (G2). The treatment with hr SOD (G3) led to a significant attenuation of talc-induced contraction of the basilar artery on days 3 (P < 0.05 vs. G2) and 7 (P < 0.05 vs. G2). In the basilar artery wall of days 3 and 7 in G2, pathological changes such as myonecrosis, cytoplasmic vacuolation and detached intercellular junctions were observed. However, these pathological changes almost disappeared in G3. The present findings suggest that superoxide anions may initiate and/or mediate talc-induced vasocontraction and subsequent structural damage of the basilar artery.

Animals↗

PubMed1995

[Study of serial bronchoalveolar lavage in patients with aspergilloma: cell reaction at the affected sites and penetration of miconazole and flucytosine into the lesion].

We have performed serial bronchoalveolar lavage (BAL) examination in two patients with asperigilloma and compared that of total cell count and cell population with control groups (5 non-smokers, 10 smokers) and other pulmonary infectious diseases: 7 each with mycoplasmal pneumonia and pulmonary tuberculosis, 6 with bacterial pneumonia, and 5 with chlamydial pneumonia. Miconazole (MCZ) by drip intravenous infusion of 400 mg/day and flucytosine (5-FC) by oral intake of 4.5 to 6.0 g/day were administered to one patient with aspergilloma, and we studied the serum and BALF concentration about 5 hours after administration. The followings results were obtained: 1. In aspergilloma, the cell population of neutrophils in BALF increased compared with control groups (p < 0.01) and other pulmonary infectious disease. 2. The serum and BALF levels of MCZ ranged from 0.1 to 0.3 micrograms/ml, < 0.1 14.4 micrograms/ml, respectively. On the other hand, the serum and BALF levels of 5-FC ranged from < 0.2 to 9.3 micrograms/ml, and < 0.4 to 1.5 micrograms/ml, respectively. From these results, we consider that neutrophils play the main role in the immune host defense in aspergilloma, and the combination of intracavitary infusion of MCZ and oral administration of 5-FC should be the treatment of choice.

Administration, Oral↗

PubMed1995

Isolation of extracellular 28- and 42-kilodalton beta-1,3-glucanases and comparison of three beta-1,3-glucanases produced by Bacillus circulans IAM1165.

Bacillus circulans IAM1165 produces three major extracellular beta-1,3-glucanases (molecular masses, 28, 42, and 91 kDa) during the stationary phase of growth. The 28- and 42-kDa enzymes were purified to homogeneity from the culture supernatant in this study. The properties of these two enzymes were examined, together with those of the 91-kDa enzyme previously isolated. The enzymatic properties of the 28- and 42-kDa beta-1,3-glucanases closely resemble each other. The enzymes belong to a category of endo type 1,3-beta-D-glucan glucanohydrolases. The enzymes were active at pH 4.0 to 7.0. The optimum temperature of the reactions was 60 degrees C when laminarin (a soluble beta-1,3-glucan) was used as the substrate at pH 7.0. The enzymes hydrolyzed barley glucan and lichenan (beta-1,3-1,4-glucans) more effectively than laminarin. Of the three enzymes, the 42-kDa enzyme lysed fungal cell walls the most effectively.

Amino Acid Sequence↗

PubMed1995

The structure and function of p55PIK reveal a new regulatory subunit for phosphatidylinositol 3-kinase.

Phosphatidylinositol 3-kinase (PI-3 kinase) is implicated in the regulation of diverse cellular processes, including insulin-stimulated glucose transport. PI-3 kinase is composed of a 110-kDa catalytic subunit and an 85-kDa regulatory subunit. Here, we describe p55PIK, a new regulatory subunit that was isolated by screening expression libraries with tyrosine-phosphorylated insulin receptor substrate 1 (IRS-1). p55PIK is composed of a unique 30-residue NH2 terminus followed by a proline-rich motif and two Src homology 2 (SH2) domains with significant sequence identify to those in p85. p55PIK mRNA is expressed early during development, remains abundant in adult mouse brain and testis tissue, and is detectable in adult adipocytes and heart and kidney tissues. p55PIK forms a stable complex with p110, and it associates with IRS-1 during insulin stimulation. Moreover, the activated insulin receptor phosphorylates p55PIK in Sf9 cells, and insulin stimulates p55PIK phosphorylation in CHOIR/p55PIK cells. The unique features of p55PIK suggest that it is important in receptor signaling.

Amino Acid Sequence↗

PubMed1995

Gastrointestinal motor inhibition by exogenous human, salmon, and eel calcitonin in conscious dogs.

Effects of synthetic eel (E-), salmon (S-), and human (H-) calcitonin (CT) on gastrointestinal motility were studied in conscious beagle dogs, which had been implanted with strain gauge force transducers. Intramuscular administration of E-, S-, or H-CT interrupted gastric migrating motor complexes, digestive pattern, and gastric emptying. The order of potency was E-CT = S-CT > H-CT. Motor inhibition induced by CT occurred independently of plasma immunoreactive motilin levels or hypocalcemia. In addition, E-CT and S-CT induced vomiting without a retrograde giant contraction (RGC) during the postprandial state. Apomorphine or CuSO4 initiated RGC prior to vomiting. RGC induced by apomorphine was inhibited by pretreatment with E-CT as well as hexamethonium, atropine, or surgical vagotomy. E-CT showed no inhibitory effect on nicotine stimulated contraction of isolated guinea-pig ileum. These results suggest that peripherally administered CT inhibits canine gastrointestinal motility at the central nervous system level by lowering vagal activity.

Analgesics↗

PubMed1995

Human GLUT-2 overexpression does not affect glucose-stimulated insulin secretion in MIN6 cells.

Accumulated evidence suggests that GLUT-2, in addition to its role in glucose transport, may also have other functions in glucose-stimulated insulin secretion. As a first step in addressing this possibility, we have engineered MIN6 cells overexpressing human GLUT-2 by transfection with human GLUT-2 cDNA. Stable transformants harboring human GLUT-2 cDNA exhibited an approximately twofold increase in 3-O-methyl-D-glucose uptake at 0.5 and 15 mM. Glucokinase activity or glucose utilization measured by conversion of [5-3H]glucose to [3H]H2O was not, however, altered in the MIN6 cells overexpressing human GLUT-2. Furthermore, glucose-stimulated insulin secretion was not affected by over-expression of human GLUT-2. An abundance of GLUT-2, therefore, does not correlate with the glucose responsiveness of cells in which glycolysis is regulated at the glucose phosphorylating step. These data suggest that GLUT-2 by itself does not have significant functions other than its role in glucose transport in glucose sensing by MIN6 cells.

3-O-Methylglucose↗

PubMed1995

Early ultrastructural glomerular alterations in neonatal nephrotic mice (ICGN strain).

ICGN is a strain of mice with hereditary nephrotic syndrome of an unknown cause. In this study, early glomerular alterations in newborn ICGN mice were observed with electron microscopy to gain a better insight into the onset of the disease. Development of the glomeruli was normal until fusion of epithelial and endothelial basement membranes in the developing capillary stage. From the maturing glomerulus stage onward, the fused glomerular basement membrane (GBM) increased in thickness by excessive accumulation of the basement membrane material secreted from the epithelial cells. This accumulation was followed by overall loss of epithelial foot processes in the glomeruli. These findings indicate that the disease in ICGN mice is caused by some defect(s) in the GMB maturation process, which may be crucial for the generation of the glomerular permselectivity.

Animals↗

PubMed1995

Characterization of rat GLUT5 and functional analysis of chimeric proteins of GLUT1 glucose transporter and GLUT5 fructose transporter.

To investigate the biological and biochemical properties of GLUT5, rat GLUT5 complementary DNA was transfected into Chinese hamster ovary cells. Rat GLUT5 was exclusively targeted to the plasma membrane and exhibited a transport activity, not for glucose, but for fructose. The affinity for fructose (Km = 11.6mM) was much higher than that of GLUT2, the other glucose transporter with fructose transport activity. Interestingly, rat GLUT5 was not photolabeled with 0.5 microM cytochalasin B, whereas a similar amount of GLUT1 was adequately photolabeled under the same experimental conditions. Next, to investigate the domains required for transport of glucose/fructose in GLUT1 and/or GLUT5, several chimeric GLUT1/GLUT5 proteins were expressed, and their glucose and/or fructose transport activities were studied. The intracellular middle loop and the region encompassing the membrane spanning domains 7-12 were observed to have crucial roles in GLUT1 glucose transport, whereas replacement of the N-terminal half or the intracellular C-terminal region with the corresponding region of GLUT5 produced no marked effects on glucose transport activity. In contrast, both the N-terminal half encompassing the region from the N-terminus through the 6th membrane spanning domain and the intracellular C-terminal region were mandatory for GLUT5 fructose transport. In conclusion, GLUT5 is a transporter exclusively for fructose and the structural requirements for fructose transport are more stringent than those for glucose transport among hexose transporter proteins.

Affinity Labels↗

PubMed1995

Muscarinic receptor subtypes mediating catecholamine secretion and increase in intracellular Ca2+ concentration in adrenal chromaffin cells of the guinea pig.

Muscarinic receptor subtypes mediating catecholamine secretion and increase in the intracellular concentration of Ca2+ ([Ca2+]i) were examined using muscarinic agonists and antagonists in dispersed adrenal chromaffin cells of the guinea pig. All muscarinic agonists (1-1,000 microM) tested caused increases in adrenaline secretion in a dose-dependent manner. Muscarine and methacholine were more effective than bethanechol, oxotremorine and pilocarpine. Muscarine and oxotremorine caused a small increase in adrenaline secretion even in the absence of extracellular Ca2+. Both 4-DAMP (0.1 microM) and pirenzepine (0.1 microM), but not methoctramine (0.1 microM), shifted the dose-response curve for muscarine-induced adrenaline secretion to the right. These muscarinic agonists also caused increase in [Ca2+]i in the presence of extracellular Ca2+. Muscarine-induced [Ca2+]i rises were reduced, but not abolished, by removal of extracellular Ca2+. These results suggest that catecholamine secretion induced by muscarinic agonists is mediated through M1, or M1 and M3 muscarinic receptor subtypes in adrenal chromaffin cells of the guinea pig.

Adrenal Medulla↗

PubMed1995

Peroxidase activity and cell differentiation in developing salivary glands of the rats.

Peroxidase (PO) activity-positive cells were found to develop in both the sublingual and submandibular glands of the rat on day 19 of gestation. The PO activity in the nuclear envelope (NE), endoplasmic reticulum (ER), Golgi apparatus (G) and secretory granules (SG) of these cells were enhanced day by day. However, no PO activity was detected in the parotid gland on the same day. In the parotid gland PO-positive cells were detected first on postnatal day 1. After birth the PO activity in the SG of both the sublingual and submandibular glands gradually diminished in intensity and disappeared, whereas the activity persisted in the parotid gland. From postnatal day 1 to 14, the NE and ER of the cells in the parotid and sublingual glands exhibited intense PO activity, while cells containing mucous SG appeared. The cells were identified as mucoserous acinar cells. These mucoserous cells later differentiated into different cell types: serous cells in the parotid gland and mucous cells in the sublingual gland. As the submandibular gland developed, PO activity-positive serous cells also differentiated into mucoserous cells and the activity in the G and SG disappeared. The parotid, sublingual and submandibular glands of perinatal rats have clearly showed varied growth, with the advent processes of PO activity and cell differentiation, whereas PO activity in the G concomitantly occurred with SG activity.

Aging↗

PubMed1995