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Biomedical subjects

A Tsuneyoshi

Publications and source records attributed to A Tsuneyoshi.

10 recordsLinked to original sources
PubMed1998

Fibrin-rich and platelet-rich thrombus formation on neointima: recombinant tissue factor pathway inhibitor prevents fibrin formation and neointimal development following repeated balloon injury of rabbit aorta.

Thrombus formation and neointimal growth are the critical events in restenosis after balloon angioplasty. However, the responses of diseased vessels to injuries caused by balloon angioplasty have not been well examined. We investigated the thrombus formation and neointimal development following the balloon injury to the previously induced neointima in the rabbit aorta and the effects of recombinant tissue factor pathway inhibitor (rTFPI) on these responses. Rabbit thoracic aortas were subjected to injury with a Fogarty 4F balloon catheter at 1.75 atm (first injury), and 4 weeks later the same vessels were subjected to the second injury with a Swan-Ganz 5F balloon catheter at 1.4 atm (mild-injury group) or 1.8 atm (severe-injury group), and immediately after that a retrograde bolus injection of rTFPI (100 microg/kg body weight) or saline was performed into the injured segments via the central tube of the Swan-Ganz catheter. Twenty minutes after the second injury, the injured surfaces were covered with platelet-rich thrombi in the mild-injury group and with fibrin-rich thrombi in the severe-injury group. Damaged intimal smooth muscle cells, which were immunohistochemically positive for tissue factor (TF), were observed beneath the fibrin-rich thrombi. The neointima 4 weeks after the second injury was significantly thicker in the severe-injury group than in the mild-injury group. The bolus infusion of rTFPI markedly inhibited fibrin formation on the injured surfaces, and significantly reduced the neointimal development in the severe-injury group at 4 weeks after the second injury. These results indicate that TF-dependent coagulation pathway is primarily responsible for fibrin-rich thrombus formation and may play an important role in neointimal development following the balloon injury to the rabbit aortic neointima. Additionally the bolus administration of rTFPI to the injured vessels could prevent mural thrombus formation and neointimal growth after balloon angioplasty.

Animals↗
PubMed1997

Nicotinic acetylcholine receptor (nACh-R) agonist-induced changes in brain monoamine turnover in mice.

The aim of the present study was to evaluate the effects of nicotinic acetylcholine receptor (nACh-R) agonists such as (-)-nicotine and related compounds on brain monoamine turnover. A single administration of (-)-nicotine (0.04, 0.2, 1.0, and 5.0 mg/kg SC) increased both noradrenaline (NA) and dopamine (DA) turnover in a dose-dependent manner, and the maximum effects were achieved 30 min after treatment with (-)-nicotine (1.0 mg/kg). The effect of (-)-nicotine on serotonin (5-HT) turnover was complicated; 5-HT turnover was increased at a low dose of (-)-nicotine (0.04 mg/kg) but decreased at a high dose (1.0 mg/kg). The (-)-nicotine (1.0 mg/kg)-induced changes in monoamine turnover were blocked by pretreatment with the centrally acting nACh-R channel blocker mecamylamine (2.0 mg/kg i.p.) but not by hexamethonium (2.0 mg/kg i.p.). These findings indicate that systemically administered (-)-nicotine can enhance brain NA and DA turnover and affect 5-HT turnover, both of which are mediated by central nACh-R. The changes in the monoamine turnover induced by (+/-)-anabasine were similar to those induced by (-)-nicotine, while (-)-lobeline and (-)-cytisine had little effect, and 1,1-dimethyl-4-phenyl-piperazinium (DMPP) increased NA and 5-HT turnover but not DA turnover at all doses tested. (S)-3-Methyl-5-(l-methyl-2- pyrrolidinyl)isoxazole (ABT-418), a selective neuronal nACh-R agonist, increased NA, DA and 5-HT turnover, but had a weaker effect on DA turnover than NA and 5-HT turnover. In addition, 9-amino-1,2,3,4-tetrahydroacridine (THA), an acetylcholine esterase inhibitor, also increased monoamine turnover in the brain. Pretreatment with mecamylamine completely blocked the THA-induced increase in NA and 5-HT turnover, but not in DA turnover, suggesting that the nACh-R system is involved in the THA-induced increase in brain NA and 5-HT turnover. On the other hand, (-)-cytisine, a partial agonist for the beta 2 subunit containing nACh-R, completely inhibited the nACh-R agonist- and THA-induced increases in NA turnover, but not in DA turnover, and normalized the changes in 5-HT turnover. In conclusion, the subtypes of nACh-Rs mediating DA turnover may be different from those mediating NA and 5-HT turnover in the CNS.

Alkaloids↗
PubMed1996

Successful treatment of bronchial mucoepidermoid carcinoma in an 11-year-old boy by bronchoplasty: report of a case.

We report herein the rare case of an 11-year-old boy in whom mucoepidermoid carcinoma of the right upper lobe bronchus was successfully treated by bronchoplasty. The patient underwent bronchoscopy to investigate the cause of relapsing respiratory infections over the past 2 years, which revealed a tumor at the orifice of the right upper lobe bronchus. Thus, a right upper sleeve lobectomy was effectively carried out, preserving right pulmonary function. The tumor was observed to partially invade the bronchial wall, but not the lung parenchyma. Histological examination confirmed a diagnosis of mucoepidermoid carcinoma, classified as grade 2 by Conlan's classification. The patient has been well and free of recurrence for 3 years postoperatively.

Anastomosis, Surgical↗
PubMed1996

Effects of inflation pressure of balloon catheter on vascular injuries and subsequent development of intimal hyperplasia in rabbit aorta.

Balloon catheter de-endothelialization is the most popular means of arterial injury in experimental animals and has been used as the model system to investigate atherogenesis and restenosis after percutaneous transluminal coronary angioplasty (PTCA). The aim of this study was to examine the relationship between balloon inflation pressure and vascular damage and also subsequent intimal hyperplasia. Retrograde pullback balloon injury of rabbit aortas was made at three different balloon pressures (1.5, 1.75, and 2.0 atm). The medial injuries, such as necrosis of smooth muscle cells and disruption of elastic lamina, were occasionally found in the injured segment of the aorta by balloon catheter at 1.75 atm and more frequently at 2.0 atm. No prominent medial injury was observed in the aortic segment to balloon catheter injury at 1.5 atm; Intimal hyperplasia developed in each animal and increased with time, 2, 4, and 8 weeks after injury. The intimal hyperplasia followed by balloon injury at 1.75 and 2.0 atm was more prominent than that at 1.5 atm, however, the development of the intimal hyperplasia was not parallel to the degree of inflation pressure. On the other hand, decrease of DNA content of the media and reduction of norepinephrine-induced vasoconstriction were observed in a pressure-dependent manner after balloon injury. These findings indicate that intimal hyperplasia is not proportionally correlated to the severity of the vascular injury. The control of inflation pressure is very important in order to examine vascular injuries, subsequent intimal hyperplasia and vasomotor responses in animal models of balloon catheter injury.

Animals↗
PubMed1994

Suramin inhibits intimal thickening following intimal injury in the rabbit aorta in vivo.

OBJECTIVE: Proliferation of vascular smooth muscle cells is a major event in atherogenesis. Several growth factors have been well documented to control this proliferation. Inhibition by suramin of the binding of some growth factors to their receptors has recently been reported. The aim of this study was to examine the effects of this agent on neointimal thickening following intimal mechanical injury, as well as on platelet function. METHODS: Intimal thickening was induced by indwelling of polyethylene tubing for 24 h in the rabbit aorta. Rabbits were killed 10 d after drawing out the tubing. Throughout the experiment, suramin (15 mg.kg-1) was injected intravenously every 24 h. Morphological and morphometrical studies were performed in the suramin treated group (n = 6) and in a control group (n = 6). Platelet-rich plasma was prepared from animals before and 3 h after injection of suramin. Platelet aggregation and ATP release induced by collagen were examined. Platelet adhesion on the de-endothelialised area of the rabbit aorta was also examined in the two groups. RESULTS: The mean intimal thickening in the suramin treated group was significantly less than in the control group. Smooth muscle cell replication and cell density in the thickened intima of the suramin treated group were less than in control. Suramin did not affect collagen induced platelet aggregation, ATP release, or platelet adhesion. CONCLUSIONS: Suramin has an inhibitory effect on the neointimal thickening and intimal smooth muscle cell proliferation after intimal injury in the rabbit aorta, but has no effect on platelet function.

Animals↗
PubMed1993

Effect of somatostatin on circadian rhythms of firing and 2-deoxyglucose uptake in rat suprachiasmatic slices.

In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus appears to act as a circadian clock. The SCN vasoactive intestinal polypeptide-like immunoreactive neurons, which may act to mediate photic information in the SCN, receive input from neurons immunoreactive for somatostatin (SST). Therefore we investigated the role of SST as a transmitter for entrainment by analyzing the phase-resetting effect of SST on the circadian rhythm of SCN firing activity. Perfusion of SST increased 2-deoxyglucose uptake at circadian time (CT) 18, but not at CT6. A 1-h or 15-min treatment with SST produced phase delays when it was administered at CT13-14 and phase advances at CT22-23. Thus SST-induced phase changes are similar to those for light pulses to animals under constant darkness. The present findings suggest that SST is a transmitter for mediating information of entrainment to circadian clocks within the SCN.

Animals↗
PubMed1992

Effect of substance P on circadian rhythms of firing activity and the 2-deoxyglucose uptake in the rat suprachiasmatic nucleus in vitro.

The suprachiasmatic nuclei (SCN) have been identified as a pacemaker for many circadian rhythms in mammals. Although substance P (SP) fibers from retina are found to terminate the SCN, the physiological role of this peptide is uncertain. The 2-deoxyglucose (2-DG) uptake and firing activity in the SCN show a robust circadian change. SP causes an increase in 2-DG uptake by SCN during the subjective night but not during subjective day. SP-induced increase in 2-DG uptake is blocked by co-treatment with the SP receptor antagonist, spantide. Treatment with SP produces phase shifts of circadian rhythm in spontaneous neural activity in SCN neurons with a phase-response curve that is similar to the effect of light pulses to animals under constant darkness. SP-induced phase change is also blocked by pretreatment with spantide. SP-induced increase in 2-DG uptake and phase changes in firing activity occur only during subjective night, at circadian times when photic phase shifting of activity occurs. The present results suggest that SP may be an important transmitter for conveying environmental light-dark information from retina to the SCN.

Action Potentials↗
PubMed1992

Phase-resetting effect of 8-OH-DPAT, a serotonin1A receptor agonist, on the circadian rhythm of firing rate in the rat suprachiasmatic nuclei in vitro.

The 5-HTergic neurons in the mesencephalic raphe nuclei provide a robust projection to the hypothalamic suprachiasmatic nucleus (SCN), the site of a putative neuronal circadian pacemaker. Although it has been suggested that 5-HT neurons may play a role in the circadian timing system, this role has not yet been specified. Prosser et al. (Brain Res., 534 (1990) 336-339) reported that 1 h treatments with quipazine induce robust phase shifts in vitro, and that this effect depends upon the circadian time of treatment. However, quipazine is a non-specific 5-HT agonist. Besides, it is reported that the 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino)tetraline hydrobromide (8-OH-DPAT) affected a circadian rhythm of hamster wheel-running activity. In the present study we investigated whether the 5-HT1A agonist 8-OH-DPAT can reset the phase of the SCN clock when it is isolated in vitro. The present results show that 1 h treatments with 8-OH-DPAT induce robust phase advances in vitro when it was administered during the subjective day. This result suggests that 5HT1A receptor functioning may play a role in modulating the phase of SCN clock, especially during the subjective day.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1990

[Postoperative recurrence of the patients with the stage I, II non small cell lung cancer].

The study population consisted of 42 patients with squamous cell carcinoma and 46 patients with adenocarcinoma of stage I, 12 patients with squamous cell carcinoma and 7 patients with adenocarcinoma of stage II lung cancer who underwent curative surgical resection. Local recurrence and metastasis was not significant in both histological types in stage I, II. Lung and bone metastasis was dominant in the both cases of squamous cell carcinoma, adenocarcinoma and brain metastasis in the cases of adenocarcinoma. Concerning the period to first recurrence following the operation, the recurrences of stage I squamous cell carcinoma occurred 28% within 1 year after surgery, 28% during 1-2 years after surgery and those of stage II squamous cell carcinoma occurred 11% within 1 year. On the other hand, the recurrences of stage I adenocarcinoma occurred 25% within 1 year, 31% during 1-2 years, 25% over 2 years after surgery and those of stage II adenocarcinoma occurred 13% within 1 year. In the cases with squamous cell carcinoma, the 5-year survival rate (56%) of stage I was not significant compared with those (59%) of stage II. On the other hand, in the adenocarcinoma, the 5-year survival rate (54%) of stage I was significantly better than those (29%) of stage II (p less than 0.05).

Adenocarcinoma↗