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Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 181 records · Page 10Linked to original sources
PubMed1997

[Fulminant subacute sclerosing panencephalitis: clinical and neuropathological observations].

We describe a 3-year-old boy with subacute sclerosing panencephalitis (SSPE) who died 4 months after its onset. His initial symptoms were drowsiness and left hemiplegia. He became comatose in 10 days, and developed a decortical posture after 45 days. He suffered from multiple cerebral hemorrhage and infarction 3 months later. Oligodendrocytes were positively stained by immunocytochemical stain with a complement-fixing measles antibody. Light microscopy revealed glial nodules, perivascular cuffing and reactive gliosis. Small arteries showed intimal thickening with resultant occlusion and occasional recanalization. These findings suggested vascular involvement in SSPE. This case illustrates the difference between the fulminant and chronic forms of SSPE.

Brain↗
PubMed1996

Transcriptional activation of RACTK1 K+ channel gene by apical alkalization in renal cortical collecting duct cells.

We have previously demonstrated that RACTK1 cDNA encodes a pH sensitive K+ channel expressed in the apical side of renal collecting tubule cells. To determine whether extracellular pH induces the RACTK1 gene expression in the renal cortical collecting duct (CCD) cells, we measured mRNA of the RACTK1 using cultured rabbit CCD cells. Alkalization of incubation medium activated the transcription of the RACKTK1 gene in a time- and dose-dependent manner after 1 h, and reached a maximal level after 12 h. To examine whether the stimulation of mRNA by alkalization of body fluid occurs also in vivo, mRNA levels were measured in mice loaded with acid or alkali. The RACTK1 mRNA was increased in association with the rise in urinary pH. To examine side face of the effect of pH on stimulation of mRNA, we observed the effect of pH in the apical or the basolateral side in the preparation where CCD cells were cultured on filter membrane supports. Alkalization of the apical side but not of the basolateral side, was shown to be a determinant in inducting the RACTK1 mRNA. These findings suggest that, in addition to rapid direct regulation of RACTK1 K+ channel conductance by intracellular pH, this channel is also regulated by the changes in luminal pH through synthesis of channel protein by transcriptional activation.

Animals↗
PubMed1996

Effect of hepatocyte growth factor on the proliferation of intrasplenically transplanted hepatocytes in rats.

The effect of human hepatocyte growth factor on the proliferation of intrasplenically transplanted hepatocytes was investigated. A human hepatocyte growth factor (360 micrograms/kg BW) was administered intravenously every 24 hr for 5 days following hepatocyte transplantation in rats. A significant increase in hepatocyte proliferation was observed morphologically and immunohistochemically (p < 0.05). The bromodexyuridine labeling index was significantly greater in human hepatocyte growth factor treated rats than in the control rats (p < 0.05). Hepatocyte growth factor may promote the proliferation of intrasplenically transplanted hepatocytes.

Animals↗
PubMed1996

Small-angle neutron scattering instrument of institute for solid state physics, the University of Tokyo (SANS-U) and its application to biology.

A small-angle neutron spectrometer (SANS-U) suitable for the study of mesoscopic structure in the field of polymer chemistry and biology, has been constructed at the guide hall of JRR-3M reactor at the Japan Atomic Energy Research Institute. The instrument is 32m long and utilizes a mechanical velocity selector and pinhole collimation to provide a continuous beam with variable wavelength in the range from 5 to 10 A. The neutron detector is a 65 x 65 cm2 2D position sensitive proportional counter. The practical Q range of SANS-U is 0.0008 to 0.45 A-1. The design, characteristics and performance of SANS-U are described with some biological studies using SANS-U.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

Staged repair of tetralogy of Fallot and pulmonary atresia without central pulmonary arteries.

A 15-year-old boy with tetralogy of Fallot and pulmonary atresia without central pulmonary arteries who was successfully treated using a staged approach is presented. The first stage consisted of the creation of central pulmonary arteries. In the second stage, the continuity between the right ventricle and the pulmonary arteries was established with closure of the ventricular septal defect. Some patients previously considered to be unsuitable candidates for correction may be successfully repaired using this approach.

Adolescent↗
PubMed1996

On the equivalence of superordinate concepts.

Psychological studies of superordinates have generally treated them as equivalent. However, many languages distinguish mass superordinates (e.g., clothing) from count superordinates (e.g., vehicle). In the present paper, experimental evidence is presented which suggests that the two types of superordinates are conceptually distinct as well. One study showed that the members of mass superordinates more often co-occur. A second study showed that people more often interact with the members of mass superordinates in temporal proximity whereas people primarily interact with single members of count superordinates on a specific occasion. Also, properties that characterize an individual are a more salient aspect of count superordinates. These findings imply that mass superordinates refer to unindividuated groups of objects, united by spatial and functional contiguity. Two other studies supported this hypothesis by showing that the class inclusion relation between a single object and a category is stronger for count superordinates. Taken together, the findings suggest that mass superordinates are not true taxonomic categories. We relate the findings to previous views of superordinates and to the count/mass distinction in general.

Adult↗
PubMed1996

Study of the collection and separation of umbilical cord blood for use in hematopoietic progenitor cell transplantation.

Human umbilical cord blood has been used as an alternative source of cells for repopulating bone marrow in allogenic bone marrow transplantation in children. The number of transplantations of umbilical cord blood cells is increasing worldwide. Umbilical cord blood was collected from 52 subjects at a single collection at the time of delivery, and separated using the red blood cell sedimentation technique. Nucleated cells harvested from the fraction enriched with white blood cells were used for an assay to detect colony-forming unit granulocyte-macrophage (CFU-GM) derived cell colonies and a flow cytometric analysis of CD34+ cells under variable conditions. The number of hematopoietic progenitor cells that might be reconstituted to bone marrow was estimated. The mean duration time from the beginning of delivery to complete collection of cord blood was 9.9 min (range 5 to approximately 20 min). The mean volume of umbilical cord blood for the 52 collections was 69.1 ml (range 15-135 ml), containing 1.001% CD34+ cells (range 0.21% approximately 2.63%) and 4 x 10(5) cells of CFU-GM derived colonies (range 0.2 x 10(5) approximately 10.0 x 10(5) cells) within 24 h at 4 degrees C after delivery of the infant. There was no contamination by the mother's lymphocytes according to cytogenetic analysis using pYNH24, which is a probe with a variable number of tandem repeat markers. These findings indicated that umbilical cord blood can be easily collected using the syringe method and separated by the red blood cell sedimentation technique using 6% hydroxyethylstarch. Within 24 h at 4 degrees C, hematopoietic progenitor cells were well detected using an assay for CFU-GM derived colonies and were measured by flow cytometric analysis. However, the instability of the number of hematopoietic progenitor cells must be resolved for safe transplantation of hematopoietic progenitor cells as a source of cells for repopulating bone marrow in children.

Antigens, CD34↗
PubMed1996

Unilateral anomalous left common carotid artery; a case report.

An anomaly of the left common carotid artery was observed in a Japanese male cadaver during an anatomy class at the Saitama Medical School in 1995. The superior thyroid, lingual and facial arteries arose from the common carotid artery, and the posterior auricular, maxillary and superficial temporal arteries arose from the common carotid artery by a common trunk. The occipital and ascending pharyngeal arteries arose from the internal carotid artery. The left carotid body (glomus caroticum) was observed to be slightly below the lingual artery, behind the common carotid artery, and it was located at the level of the intervertebral disk between C2 and C3 or at the same level as the right carotid body. The carotid body was richly innervated by a branch of the glossopharyngeal nerve and by a plexus of sympathetic fibers from the vagus and glossopharyngeal nerves. We assumed that the artery above the level of the carotid body was the internal carotid artery; there was no specific external carotid artery and all branches of the external carotid artery arose from the internal carotid artery.

Aged↗
PubMed1996

A new technique for laparoscopic cholecystectomy--retrograde laparoscopic cholecystectomy: an analysis of 81 cases.

BACKGROUND AND STUDY AIMS: A new technique of laparoscopic cholecystectomy is presented here. This new method, retrograde laparoscopic cholecystectomy (RLC) from fundus to cystic duct downward, may have advantages when exposure of the cystic duct and the common duct are difficult and therefore hazardous. PATIENTS AND METHODS: We carried out laparoscopic cholecystectomy in 173 patients; RLC was performed in 81, The operative procedure is as follows: first, the cystic duct and artery are exposed at the junction of the ampulla. The cystic duct is clipped, and the artery is divided. Removal of the gallbladder is then started from the fundus to cystic duct downward. After the gallbladder has been dissected from the liver bed, the cystic duct is double-clipped and divided. This approach provides better visualization of the gallbladder, cystic duct, and common duct, with less chance of common duct injury, due to clear identification of the ductal system, without the need for intraoperative cholangiography. RESULTS: Eighty-one RLCs were performed without severe complications, either immediate or late. The mean operating time was 23 minutes shorter in RLC than in the usual laparoscopic cholecystectomy, because intraoperative cholangiography was used much less often. CONCLUSION: RLC appears to be a safe procedure, and does not affect the conventional method.

Adult↗
PubMed1996

Effects of halothane, isoflurane and sevoflurane on ischemia-reperfusion injury in the perfused liver of fasted rats.

BACKGROUND: Although intraoperative ischemia-reperfusion of the liver generally occurs under general anesthesia, little is known about the direct effect of anesthetic agents on hepatic injury due to this phenomenon. The effect of volatile anesthetics on ischemia-reperfusion injury was studied using isolated liver perfusion. METHODS: The liver was isolated from 24-h-fasted male Sprague-Dawley rats and perfused through the portal vein with a modified Krebs-Ringer bicarbonate solution in a recirculating perfusion-aeration system. Ischemia was induced by reducing the baseline perfusion pressure from 1.2 to 0.2 kPa followed by reperfusion to baseline level. The ischemia-reperfusion injury was assessed by LDH release from the perfused liver. We studied the effect of halothane, isoflurane and sevoflurane on the ischemia-reperfusion injury during 20 min of control conditions, exposure of the liver to 60 min of ischemia and reperfusion for 90 min. RESULTS: Ischemia was evident by reduced portal vein flow and oxygen consumption, and caused an increase in lactate production. Reperfusion caused a transient reduction in lactate production and a significant increase in LDH release. All anesthetics reduced hepatic oxygen consumption and increased the net lactate production during control conditions. Volatile anesthetics also significantly attenuated LDH release during reperfusion. The suppression of LDH release was observed even when isoflurane was administered during the reperfusion period, but not when it was administered only during ischemia. CONCLUSION: These results indicate that volatile anesthetics may protect the fasted liver from early, neutrophil-independent, ischemia-reperfusion injury by acting during the reperfusion phase.

Anesthetics, Inhalation↗
PubMed1996

Electrophysiological characterization of RACTK1 K+ channel in stable cell line.

RACTK1 is a pH-sensitive K+ channel cloned from rabbit renal collecting tubule cells. To characterize the function of this K+ channel in more detail, RACTK1 was transfected to an established cell line and the patch-clamp study was performed. cDNA of RACTK1 was inserted in the pMAM vector and transfected to Chinese hamster ovary cells. In one of 36 cell lines, the channel protein as expressed by the dexamethasone-induced mRNA and was detected by the specific antibody. The RACTK1 K+ channel with 80 pS was consistently observed. In inside-out patch, Ca2+ at concentrations higher than 500 nM activated the channel. Open probability was decreased by protein kinase A (from 45 to 4.2%, n+6) but not by protein kinase C. Whole cell currents of the transformed cells represented K+ conductance that was not blocked by an addition of charybdotoxin but by apamin. RACTK1 K+ channel has similar, though not identical, characteristics to the Ca2+ -activated K+ channel. RACTK1 might therefore encode a subunit of the intermediate conductance Ca2+ -activated K+ channel observed in the apical membrane of the rabbit renal collecting duct.

Alkaline Phosphatase↗
PubMed1996

Optimal transport parameters of the inner medullary collecting duct in interaction between urine concentrating and urea excreting mechanisms: a computer simulation study.

Although the accumulation of urea in the renal medulla is essential for the formation of concentrated urine, it is also necessary for the kidney to excrete considerable amounts of urea into the urine as a waste product of protein degradation. Thus, the urine concentrating capacity is attained by the interaction with the efficiency of urea excretion. To seek the best condition for this phenomenon, we developed an objective function for evaluating urea excreting capacity relative to urine concentrating capacity by using a mathematical model consisting of components of the countercurrent multiplication system: the ascending thin limb, capillary network, and inner medullary collecting duct. The values of the objective functions were calculated as three-dimensional functions of transport parameters for the inner medullary collecting duct, including hydraulic conductivity, urea permeability, and reflection coefficient for urea. The results of the computer analysis revealed that the maximum value of the objective function was attained when values for transport parameters of the inner medullary collecting duct corresponded to those experimentally obtained values reported previously. We conclude that the maximum urine concentrating capacity is limited by the efficiency of urea excreting capacity of the kidney, and vice versa.

Biological Transport↗
PubMed1996

Cytokine modulation of inhibin secretion in cultured rat granulosa cells.

In the present study, we examined the effects of tumour necrosis factor alpha (TNF alpha) and interleukin-1 beta (IL-1 beta) on inhibin secretion by cultured rat granulosa cells using immunoblotting and two-site enzyme immunoassay for inhibin A (alpha-beta A dimer). FSH stimulated the secretion of the inhibin alpha-beta A dimer (32 kDa) by the cells in a dose-dependent manner. In addition to the predominant 32 kDa inhibin alpha-beta A dimer staining, staining of minor immunoreactive bands was also enhanced by FSH. TNF alpha alone did not have any effect on inhibin secretion. Immunoblot analyses using an antiserum against alpha-subunit and an antiserum against beta A-subunit revealed a dose-dependent inhibition by TNF alpha of FSH-stimulated secretion of inhibin by rat granulosa cells. Similarly, TNF alpha inhibited in a dose-dependent manner FSH-stimulated inhibin secretion when measured using a two-site enzyme immunoassay. IL-1 beta alone did not exert any effect on inhibin secretion but it inhibited FSH-stimulated inhibin release in a dose-dependent manner (using both immunoblotting and a two-site assay for inhibin A). The present observations suggest that TNF alpha and IL-1 beta inhibit gonadotrophin-stimulated inhibin production by cultured rat granulosa cells.

Animals↗
PubMed1996

Colon cancer with a high serum alpha-fetoprotein level.

We report on a patient with colon cancer and a very high serum alpha-fetoprotein level. This 75-yr-old man presented with right lower quadrant abdominal pain. An abdominal CT scan as well as ultrasonography showed a tumor in the cecum. Serum alpha-fetoprotein level was extremely high (3,070 ng/ml). At laparotomy, a large mass was found in the cecum, and a right hemicolectomy was performed. Histological examination, including immunohistochemical study, showed an adenocarcinoma of the colon producing alpha-fetoprotein.

Adenocarcinoma↗
PubMed1996

Functional characterization of vasopressin V1 and V2 receptors in the rabbit renal cortical collecting duct.

Recently we clarified the mechanism in which arginine-vasopressin (AVP) applied from the luminal side inhibits the basolateral Cl- conductance, which is stimulated by basolateral AVP. However, to prove that these vasopressin phenomena are expressed via receptor mediated actions, we examined the effect of specific V1 and V2 receptor antagonists, OPC-21268 and OPC-31260, respectively, on the electrical response to vasopressin in the rabbit CCD perfused in vitro. In the presence of the V2-antagonist, basolateral AVP caused only the activation of luminal Na+ conductance, indicating a V1 action. In the presence of the V1 antagonist, basolateral AVP caused the same biphasic responses in electrical parameters as cyclic AMP, representing a pure V2 action. On the other hand, a rise in cell Ca2+ in response to AVP was completely abolished in the presence of the V1-antagonist, but not by the V2-antagonist in the bath. These data confirm our earlier findings that rabbit CCD possesses both V1 and V2 receptors in the basolateral membrane. We conclude that electrical responses to AVP in the rabbit CCD are a complex of V1 and V2 receptor-mediated actions.

Animals↗