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Biomedical subjects

Junichi Tanaka

Publications and source records attributed to Junichi Tanaka.

48 records · Page 3Linked to original sources
PubMed2002

Enhanced response of subfornical organ neurons projecting to the hypothalamic paraventricular nucleus to angiotensin II in spontaneously hypertensive rats.

Thirty subfornical organ (SFO) neurons in normotensive Wistar-Kyoto (WKY) rats and 32 SFO neurons in spontaneously hypertensive rats (SHR) were antidromically activated by electrical stimulation of the hypothalamic paraventricular nucleus (PVN) under urethane anesthesia. The spontaneous firing rate was significantly higher in SHR than in WKY rats. No significant differences in the latency, conduction velocity, and threshold of antidromic response were observed between WKY and SHR. All the identified SFO units were tested for a response to intracarotid injection of angiotensin II (ANG II, 20-ng/kg b.w.t.). Injections of ANG II elicited an increase in the activity of 21 units in WKY and 20 units in SHR and a depression in the firing of one unit in WKY rats, but did not affect the remaining units. The magnitude of the excitatory response caused by the ANG II injection was much greater in SHR than in WKY rats. These results show that there are differences between WKY and SHR in the spontaneous discharge rate of SFO neurons projecting to the PVN and in their response to circulating ANG II.

Action Potentials↗
PubMed2002

Alpha-adrenergic control of ANG II-induced drinking in the rat median preoptic nucleus.

The present study was carried out to investigate the contribution of angiotensinergic and catecholaminergic systems in the median preoptic nucleus (MnPO) to the drinking response elicited by activation of the subfornical organ (SFO) following injections of angiotensin II (ANG II) in the awake unrestrained rat. Microinjection of ANG II into the SFO caused the drinking response. The water intake caused by ANG II injected into the SFO was significantly enhanced by previous injections of phenylephrine, an alpha-adrenoceptor agonist, but not by isoprenaline, a beta-adrenoceptor agonist. Previous injections of either saralasin, a specific ANG II antagonist, or phentolamine, an alpha-adrenoceptor antagonist, into the MnPO significantly attenuated the water intake caused by the ANG II injection into the SFO. Similar injections of timolol, a beta-adrenoceptor antagonist, or the vehicle into the MnPO had no significant effect on the drinking response. These results show the involvement of both angiotensinergic and alpha-adrenergic systems in the MnPO in the drinking response induced by ANG II acting at the SFO, and imply that the alpha-adrenergic system may serve to enhance the neural inputs including the angiotensinergic inputs from the SFO, thereby causing increased dipsogenic response.

Adrenergic alpha-Agonists↗
PubMed2002

Paraventricular noradrenergic systems participate in angiotensin II-induced drinking.

The present study was designed to examine the role of noradrenergic systems in the hypothalamic paraventricular nucleus (PVN) in the drinking response induced by microinjection of angiotensin II (ANG II) into the subfornical organ (SFO) in the awake rat. Intracerebral microdialysis techniques were utilized to quantify the extracellular concentration of noradrenaline (NA) in the region of the PVN. Injections of ANG II (10(-6)M, 0.2 microl) into the SFO significantly increased NA release in the PVN area. The increase in the NA concentration caused by the ANG II injection was significantly attenuated by water ingestion. In urethane-anesthetized rats, injections of ANG II into the SFO elicited an elevation in mean arterial pressure (MAP). On the other hand, intravenous injections of the alpha-agonist metaraminol (5 microg) slightly decreased the release of NA in the PVN area that accompanied an elevation in MAP. These results show that the noradrenergic system in the PVN area may be involved in the dipsogenic response induced by ANG II acting at the SFO.

Angiotensin II↗
PubMed2002

Cyclotheonamide E4 and E5, new potent tryptase inhibitors from an Ircinia species of sponge.

Tryptase is a protease released from mast cells and is believed to contribute to the inflammatory process in allergic diseases including asthma. In the course of screening to find tryptase inhibitors, we isolated two new tryptase inhibitors, cyclotheonamide E4 (3) and E5 (4), from a marine sponge of the genus Ircinia. The structures of these molecules were determined by interpretation of 1H and 13C NMR spectra, and they were shown to be closely related to the previously reported cyclotheonamides E (1), E2, and E3 (2). These molecules contain two unusual amino acids, vinylogous tyrosine and alpha-ketohomoarginine, which are involved in strong activities against serine proteases. Cyclotheonamide E4 showed potent inhibitory activity against human tryptase (IC50 5.1 nM). Therefore, cyclotheonamide E4 may be useful as a therapeutic agent in the treatment of allergic diseases including asthma.

Animals↗
PubMed2002

New scalarane class sesterterpenes from an Indonesian sponge, Phyllospongia sp.

A series of scalarane class sesterterpenes (1-8) have been isolated from an Indonesian sponge, Phyllospongia sp. Their structures were determined by spectroscopic analysis and confirmed by single-crystal X-ray diffraction on compound 1. The absolute stereochemistry of 1 was established by modified Mosher's method.

Animals↗
PubMed2002

[A case of gastric cancer with paraaortic lymph node metastasis responding to TS-1/CDDP as neoadjuvant chemotherapy].

A 64-year-old male visited our hospital with complaints of epigastric pain. Computed tomography (CT) showed gastric cancer with extensive paraaortic lymph node metastasis. We decided that a curative operation was impossible, and administered the following chemotherapy. After 120 mg/day of TS-1 was orally administered for 3 weeks followed by 2 drug-free weeks with 90 mg of CDDP was administered intravenously on day 8, CT showed a 90.6% reduction in the paraaortic lymph node metastasis. No serious adverse reaction was observed. After 2 courses of this chemotherapy, surgery was performed after informed consent was obtained from the patient. Histrogical result showed PR. The patient is now healthy and no sign of recurrence has been observed. TS-1/CDDP therapy is useful for advanced gastric cancer.

Adenocarcinoma↗
PubMed2002

[A case of esophageal cancer successfully treated by chemoradiotherapy after resection for multiple liver metastasis of sigmoid colon cancer].

The patient was a 56-year-old man. Colonoscopic findings showed a cancerous lesion of the sigmoid colon and we performed curative sigmoidectomy. Four months after the operation, abdominal CT scan revealed multiple metastatic lesions in the liver. We performed lateral segmentectomy and partial resection of the S4, S6, S8 segments and cannulation for hepatic arterial infusion chemotherapy. Continuous hepatic arterial infusion chemotherapy with 5-FU (1,000 mg/body/day) was performed for two weeks as a postoperative adjuvant chemotherapy. Immediately after the therapy, endoscopic examination for upper digestive tract showed a 0-lpl type cancer lesion in the middle of the thoracic esophagus. Concurrent chemoradiotherapy with low-dose FP was efficacious and a complete response was obtained. The patient has survived for nine months after the operation without any sign of recurrence. It is suggested that concurrent chemoradiotherapy an effective treatment for esophageal cancer.

Chemotherapy, Adjuvant↗
PubMedDate not supplied

Fluorescent kabiramides: new probes to quantify actin in vitro and in vivo.

We present the design, synthesis, and biochemical and spectroscopic characterization of five functional fluorescent conjugates of kabiramide C (KabC), a small molecule biomimetic of gelsolin. The tetramethylrhodamine (TMR), rhodol green (RG), IC5, dapoxyl (DAP), and fluorescein diester (FDE) conjugates of KabC bind specifically to actin at the barbed end in a 1:1 complex. These probes are shown to function in an indistinguishable manner to the unmodified KabC. Various modalities of the fluorescence emission of these KabC probes, including fluorescence anisotropy and fluorescence resonance energy transfer, are used for the development of assays for the rapid determination of G-actin concentration in solution. The TMR-KabC and FDE-KabC probes are cell permeable and provide unique imaging information on the distribution and dynamics of actin filament within living cells.

3T3 Cells↗
PubMedDate not supplied

An autopsy case of Pena-Shokeir syndrome: severe retardation of skeletal muscle development compared with neuronal abnormalities.

An infant with multiple joint ankyloses, facial anomalies, and pulmonary hypoplasia, features similar to the phenotype of Pena-Shokeir syndrome, was examined at autopsy. Histological examination of the skeletal muscles revealed many small muscle fibers in a mixed, not group, distribution, although the structure of them was normally arranged. Histochemical assessment of adenosine triphosphatase (ATPase) activity of the iliopsoas muscle demonstrated the failure of the differentiation into type I fibers and the retardation of the skeletal muscle. At the same time, severe pulmonary hypoplasia, which was the likely cause for the retardation of the respiratory system, was found. In contrast to these numerous pathologic changes in the skeletal muscles, no significant abnormalities were observed in the central nervous system except for a somewhat immature external appearance; however, an examination of the spinal cord could not be carried out. Overall, this pattern of pathology suggests the possibility that developmental disorders of the mesenchyme are the primary contributors to the pathogenesis of Pena-Shokeir syndrome, while the immaturity of the central nervous system is involved to a lesser degree.

Abnormalities, Multiple↗