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Biomedical subjects

N Takei

Publications and source records attributed to N Takei.

At least 163 records · Page 9Linked to original sources
PubMed1990

Monitoring of acetylcholine released from postnatal rat basal forebrain cholinergic neurons cultured on membrane filter by cell bed perfusion system and HPLC-ECD.

A method for the determination of release of endogenous neurotransmitter from cultured neurons has been developed. Basal forebrain cholinergic neurons from postnatal rats were cultured on polyethyleneimine-coated membrane filter with nerve growth factor. The membrane filter, on which the neurons lived and extended neurites, was packed in a cell bed chamber for a closed perfusion. The perfusate was fractionated and the content of acetylcholine released from cultured neurons was measured by high-performance liquid chromatography-electrochemical detection (HPLC-ECD). Acetylcholine release evoked by glutamate and high K+ was 1.5- and 3-fold greater than the spontaneous level. This method for the determination of the neurotransmitter released from cultured neurons is very advantageous for investigating regulation of transmitter release in central neurons.

Acetylcholine↗
PubMed1990

[Seroepidemiological study on the horizontal infection of HBV in healthy students].

In a seroepidemiological study of hepatitis B virus (HBV) over 7 years from 1982 to 1988, in a fixed population of 633 healthy students (15-20 years old), it was found that one HBV carrier who had adw subtype of HBV had also become sero-positive to r subtype, suggesting the superinfection with r subtype of HBV to the carrier. Then, some serological markers of HBV were further examined in the other 10 HBsAg positive carriers in the same population, and discussed the possibility of horizontal transmission of r subtype of HBV in the population. Of the 10 HBsAg positive carriers, 5 possessed adr subtype, 2 adwr, 2 adw, respectively, and the remaining one was not tested. Four of seven r subtype of HBsAg positive carriers exhibited pre-S2Ag and HBeAg activities which were considered as infectious markers. Epidemiological survey was carried on the four carriers with special reference to the possibility of the superinfection. As a result, it is still unclear the source of the superinfection, but at least, iatrogenically accidental transmission at the time of vaccination and contact infection in everyday life in school may be unlikely to attribute to the horizontal transmission.

Adolescent↗
PubMed1990

Enhancing effect of centrifugation on isolation of influenza virus from clinical specimens.

The use of centrifugation (700 x g, 60 min) in a plaque assay markedly increased (mean, 2.9-fold) the infectivity of all 42 influenza virus strains tested, compared with no centrifugation. Of 13 influenza virus strains isolated from 390 clinical specimens, 9 (69%) were efficiently isolated by the centrifugation assay compared with conventional culture methods. The centrifugation assay may be useful for isolating the influenza virus from clinical specimens.

Centrifugation↗
PubMed1990

Pressure responses and conduction of peristaltic wave in guinea-pig ureter.

Physiological properties of guinea-pig ureteral segments were studied by measuring the internal pressure responses to electrical stimulation in iso-volume conditions and by recording the contraction elicited by local electrical stimulation in iso-pressure conditions with a video-system. In iso-volume conditions, the phasic pressure response of the ureter increased in magnitude with increasing resting intra-luminal pressure and its threshold was lower in the proximal end, i.e., the part nearest to the renal pelvis, and higher in the distal end. In iso-pressure conditions, the average conduction velocity of the contraction wave was 2.30 +/- 0.54 cm/s (mean and standard deviation, n = 20) in the pressure range of 2-4 cmH2O, being slower in the proximal than in the distal ureter. The velocity decreased with increasing internal pressure. The velocity was nearly equal both in the normal direction of conduction and in the reverse one. The duration of the peristaltic contraction was longer in the proximal and shorter in the distal ureter. These results are discussed in connection with the fundamental mechanical properties of smooth muscle cells.

Animals↗
PubMed1990

[A case of long-term survival of a patient with complicated diffuse metastatic leptomeningeal carcinomatosis secondary to lung adenocarcinoma].

A case of long-term survival of a female patient with complicated diffuse metastatic leptomeningeal carcinomatosis (DMLC) secondary to lung cancer is reported. A 36-year-old woman, hospitalized with a chief complaint of headache and unproductive cough, was diagnosed as having primary lung adenocarcinoma (T4N1M1 oss) and was given systemic chemotherapy. Although progressive deterioration of her headache continued, repeated neurological examination, cerebrospinal fluid (CSF) examination, and cranial CT scans failed to show evidence of metastasis to the central nervous system, and the only finding suggesting CNS involvement was an elevated CEA level in CSF. Later in the course of her treatment, the patient suddenly lost her vision and subsequently consciousness due to acute increased intracranial pressure, and emergency ventricular drainage was performed for therapeutic and diagnostic purposes. Malignant cells were found in CSF obtained from a ventricular drainage and she was treated successfully by systemic and intrathecal chemotherapeutic agents. She was discharged after a ventriculoperitoneal shunt operation for hydrocephalus; a double-dome reservoir was used for continuous intrathecal administration of the anticancer drugs, and a shunt filter was located in the tube to prevent the dissemination of cancer cells. In addition to methotrexate and cytosine arabinoside, ACNU and interleukin-2 were administered intrathecally without serious adverse effects, but no apparent therapeutic effects were noted either. She survived over 2 years after DMLC was first diagnosed. At autopsy DMLC secondary to lung adenocarcinoma was confirmed, but no evidence of leukoencephalopathy due to aggressive intrathecal chemotherapy was found. Current therapy for patients with DMLC and its clinical problems are discussed in relation to our experience in this case.

Adenocarcinoma↗
PubMed1989

Increase in choline acetyltransferase activity in septum of rats after transient forebrain ischemia: a possible role of factors released in the hippocampus.

Choline acetyltransferase (ChAT) activity increased in rat septum 2 weeks after a transient forebrain ischemia. Extracts were prepared from hippocampus in which CA1 pyramidal neurons had been selectively destroyed by the ischemic insult. ChAT activity in septal neuronal cultures treated with these extracts for 6 days was significantly higher than that in control cultures.

Animals↗
PubMed1989

Transplantation of septal cholinergic neurons to the hippocampus improves memory impairments of spatial learning in rats treated with AF64A.

Embryonic septal neurons were transplanted into damaged hippocampus in adult rats which had received lateral ventricular administration of AF64A, a cholinergic neurotoxin. About 3 months after transplantation, the rats with bilateral septal grafts showed significant improvement in the radial maze and T-maze tasks. Many ingrowths of acetylcholinesterase (AChE)-positive fibers originating from the grafts were observed in the hippocampus of the rats which showed good performance in these learning tasks. These results indicate that transplantation of septal cholinergic neurons into the AF64A-treated hippocampus may induce at least partial recovery in learning tasks believed to involve the hippocampus.

Animals↗
PubMed1989

Age-related decline of acetylcholine release evoked by depolarizing stimulation.

Release of endogenous acetylcholine (ACh) from the dorsal hippocampus in response to depolarizing stimulation with high-K+ infusion was examined in young and aged rats using the method of in vivo dialysis. ACh content in the dialysate was determined by high-performance liquid chromatography-electrochemical detection (HPCC-ECD). During the high-K+ stimulation, the concentration of ACh in the dialysate only slightly increased in aged rats in contrast with young rats where the ACh content during stimulation increased about 2-fold of the basal level. These results showed that ACh release evoked by depolarizing stimulation declined through aging in the hippocampus.

Acetylcholine↗
PubMed1989

Recovery of hippocampal cholinergic activity by transplantation of septal neurons in AF64A treated rats.

Embryonic septal neurons were transplanted into the hippocampus of adult rats which had received lateral-ventricular administration of AF64A, a cholinergic neurotoxin, and the effects on hippocampal cholinergic activity were studied. One week after AF64A administration, we injected dissociated septal cell suspension into the dorsal hippocampus, unilaterally. About 3 months after the transplantation, acetylcholine (ACh)-rich septal grafts formed extensive acetylcholinesterase (AChE)-positive fibers into the host hippocampus, recovering choline acetyltransferase (ChAT) level only in the grafted side. These results indicate that septal implants can produce a partial recovery of the cholinergic activity in the chemically damaged hippocampus.

Acetylcholinesterase↗
PubMed1989

Intracellular storage and evoked release of acetylcholine from postnatal rat basal forebrain cholinergic neurons in culture with nerve growth factor.

Cholinergic neurons from the septum area, the vertical limb of the diagonal band of Broca, and the nucleus basalis of Meynert of postnatal 13-day-old rats were cultured with or without nerve growth factor (NGF) conditions. Total choline acetyltransferase (ChAT) activities, acetylcholine (ACh) contents, and survival numbers of cholinergic neurons in culture from each of three distinct regions were increased by NGF treatment, but little difference was found in cellular ChAT activities and ACh contents obtained in cultures with or without NGF. The result shows that NGF promotes the survival of cholinergic neurons from 13-day-old rats. Furthermore, the release of ACh from cultured neurons was investigated. The cells cultured with NGF showed a larger increase of the high K+-evoked ACh release than those cultured without NGF. However, NGF had no effect on spontaneous release. This suggests that NGF could regenerate and sustain the stimulation-evoked release mechanisms of ACh in cultured cholinergic neurons from postnatal rats.

Acetylcholine↗
PubMed1989

Effect of deuterium oxide (D2O) on the IgE-mediated Ca2+ influx, arachidonic acid and histamine release in rat basophilic leukemia cells.

Deuterium oxide (D2O), which is known to stimulate microtubule aggregation, enhanced the IgE-mediated 45Ca2+ influx, (14C)-arachidonic acid and histamine release in rat basophilic leukemia cells (RBL-2H3) in the same dose-dependent manner (up to 90% (v/v]. We compared the interaction between D2O and a variety of groups of pharmacological agents. A microtubule depolymerizing agent, demecolcine, which inhibited the IgE-mediated (14C)-arachidonic acid and histamine release without affecting 45Ca2+ influx, was counteracted by 45% D2O. Taxol, a microtubule stabilizing agent, which had an inhibitory effect on the above three steps, was also reversed by 45% D2O. These results would support the previous data on the interaction between D2O and microtubules and would further suggest that the status of microtubule aggregation may be related to the secretory process. Calmodulin inhibitors (W-7, trifluoperazine) blocked the IgE-mediated 45Ca2+ influx, (14C)-arachidonic acid and histamine release in the same dose-dependent manner, but were counteracted by 45% D2O. In contrast, the effects of proteinase inhibitors (TPCK, TLCK), an adenylate cyclase inhibitor (ddAdo), a phosphodiesterase inhibitor (aminophylline), a phospholipid methylation inhibitor (DZA + Hcy) and microfilament blockers (cytochalasin B and D) were not counteracted by 45% D2O. These results would suggest that D2O may be associated with calmodulin directly or indirectly possibly through some relationship between calmodulin and microtubules.

Animals↗
PubMed1988

Transplantation of fetal and early postnatal rat septal cholinergic neurons cultured in serum-free and serum-containing medium with nerve growth factor.

Fetal rat (E17-E19) septal neurons were cultured in a defined, serum-free medium for 6-8 days with or without nerve growth factor (NGF) and transplanted into the hippocampus or the surrounding ventricle of 28 adult rats denervated of its septal input by a fimbria-fornix transection. The cholinergic septal neurons, which were visualized by acetylcholinesterase (AChE) histochemistry, always survived in transplantation to the adult brains from nearly pure neuronal cultures. Although choline acetyltransferase (ChAT) activity of septal neurons in culture was greatly increased (5.59-fold) by the addition of NGF to the defined medium, this ChAT induction appeared to have little effect on the subsequent survival or growth of the septal neurons after transplantation. These results demonstrate that survival of cultured fetal septal cholinergic neurons following transplantation is not dependent upon the presence of NGF or serum- or glia-derived factors during the preliminary culture. Postnatal rat (P4) septal neurons cultured for 5 days in serum-containing medium with NGF were also successfully transplanted in one of 3 cases.

Acetylcholinesterase↗
PubMed1988

Nerve growth factor increases the intracellular content of acetylcholine in cultured septal neurons from developing rats.

The effects of nerve growth factor (NGF) on the intracellular content of acetylcholine (ACh) in cultured septal neurons from developing rats have been examined. The content of ACh could be measured by using HPLC and electrochemical detection (HPLC-ECD), coupled with an immobilized enzyme column. This method of determination is very simple and rapid, and is highly sensitive. The content of ACh and the activity of choline acetyltransferase (ChAT) in cultured postnatal day 1 (P1) septal neurons grown on an astroglial "feeder" layer was increased during the period of cultivation by the addition of NGF. The activities of ChAT and the content of ACh increased in a dose-dependent manner in direct relationship to the different amounts of NGF employed. These effects of NGF, i.e., elevating the intracellular content of ACh, accompanied by an increase in activity of ChAT, also were confirmed in the P1 septal organotypic cultures. Additionally, embryonic day 17 (E17) septal neurons in a serum-free medium displayed a similar responsiveness to NGF with respect to the elevation in the content of ACh and the increase in activity of ChAT. These results suggest that intracellular levels of ACh are likely to be regulated by NGF in a fashion similar to that of the activity levels of the biosynthetic enzyme.

Acetylcholine↗