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Biomedical subjects

K Seto

Publications and source records attributed to K Seto.

At least 145 records · Page 8Linked to original sources
PubMed1988

Influence of microinjection of corticosterone into ventromedial hypothalamus on hepatic acetate metabolism in rabbits.

Corticosterone was injected into the ventromedial hypothalamus (VMH) of rabbits, and changes in hepatic acetate metabolism were studied. The microinjection of corticosterone with seasame oil into the VMH of intact rabbits increased the rates of 14C transfer from 14C-1-acetate into CO2, glucose, ketone bodies, triglyceride, free cholesterol, free fatty acids and phospholipids but decreased those of 14C transfer into cholesterol ester. However, corticosterone injected into the VMH of rabbits with VMH lesions or the parietal cortex of intact rabbits was without effect on the hepatic acetate metabolism. From these results it might be suggested that the VMH is an integral part of the corticosterone-sensitive brain regulator system in the hepatic acetate metabolism.

Acetates↗
PubMed1988

Electrophysiology of neurones projections from the rat A1 noradrenergic region to the medial preoptic/anterior hypothalamic area: lack of effect of the oestrous cycle on their excitability.

The neuronal excitability of presumed A1 noradrenergic neurones in the ventrolateral medulla (VLM) which directly project to the medial preoptic/anterior hypothalamic area was analysed in pro-oestrous and metoestrous female rats under urethane anaesthesia. No significant difference was detected between the two groups for the antidromic activation threshold, absolute refractory period, frequency of successful antidromic propagation into the somatodendritic membrane, duration of post-stimulus inhibition, or spontaneous firing rate of these neurones. These results do not support the idea that the neuronal somata of A1 noradrenergic neurones in the VLM show a pro-oestrous increase in excitability during the oestrous cycle, although limitations of the methodology employed do not completely rule out this possibility.

Animals↗
PubMed1988

[Basic and clinical studies on patients who have undergone autologous or allogeneic bone marrow transplantation].

Bone marrow transplantation (BMT) is now increasingly applied not only to hematologic disorders such as leukemias and aplastic anemia but also to some of solid tumors. We experienced ten cases of bone marrow harvest and six cases of autologous or allogeneic BMT during the period from June, 1986 to August, 1987. For autologous BMT cases, bone marrow cells were harvested and cryopreserved at -196 degrees C in liquid nitrogen tank and colony forming assays were examined to ascertain the colony forming ability of harvested bone marrow stem cells. Recovery of colony forming ability after cryopreservation in colony forming unit in culture and burst forming unit in erythrocyte is about 63 to 73% and well preserved. Among 6 cases undergone BMT, five cases are patients with advanced solid tumors including breast cancer, seminoma, lung cancer, malignant lymphoma and brain tumor and these 5 cases have undergone autologous BMT. Conditioning regimen for each cancer in autologous BMT differs based upon conventional chemotherapy regimen and two to four fold dose of conventionally used chemotherapy regimen were administered and after two or three days of high dose chemotherapy, cryopreserved bone marrow cells were thawed and infused. Peripheral white blood cells and platelets were recovered to more than 1000/microliters and 5 x 10(4)/microliters, respectively, within 21 days after bone marrow cell infusion. Disappearance or decrease in tumor size was observed in all cases except brain tumor even though those cases were advanced ones. After autologous BMT, recurrence occurred within three to five months in three cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Lateral hypothalamic region excites the activity of vasopressin neurons in the supraoptic nucleus through subfornical organ neurons.

In urethane-anesthetized male rats, microinjection of angiotensin II into the lateral hypothalamic area excited the activity of about half (N = 7) of subfornical organ neurons (N = 15) antidromically identified as projecting to the hypothalamic supraoptic nucleus. Microinjection of angiotensin II also excited the activity of approximately one-quarter (N = 8) of putative vasopressin-secreting neurons (N = 28) in the hypothalamic supraoptic nucleus and these excitatory responses of putative vasopressin-secreting neurons were blocked (N = 3) or attenuated (N = 3) by pretreatment with the angiotensin II antagonist saralasin, but not by isotonic saline (N = 2), in the subfornical organ.

Action Potentials↗
PubMed1987

Subfornical organ neurons act to enhance the activity of paraventricular vasopressin neurons in response to intravenous angiotensin II.

The effects of pretreatment of the angiotensin II (ANGII) antagonist, saralasin (Sar), in the subfornical organ (SFO) on intravenous ANGII-induced responses of the activity of phasically firing paraventricular nucleus (PVN) neurons (n = 23) antidromically identified as projecting to the posterior pituitary were examined in urethane-anesthetized rats. The activity of the majority (n = 18) of identified PVN neurons was excited by intravenously administered ANGII, whereas the remaining neurons (n = 5) were not affected. The excitatory responses (n = 13) to ANGII were prevented by pretreatment with Sar, but not by isotonic saline (n = 3), in the SFO. These results suggest that ANGII-sensitive SFO neurons may act to enhance the excitability of putative vasopressin (VP)-secreting neurons in the PVN in response to circulating ANGII.

Action Potentials↗
PubMed1987

Influence of microinjection of glucagon into ventromedial hypothalamus on acetate metabolism in liver slices of rabbit.

Glucagon was injected directly into the ventromedial hypothalamic nuclei (VMH) of rabbits, and changes in hepatic acetate metabolism were studied. The injection of 3 ng glucagon into the VMH of intact rabbits increased the rates of 14C transfer from 14C-1-acetate into CO2, glucose and ketone bodies but decreased those into cholesterol ester, triglyceride, free cholesterol, free fatty acids and phospholipids. However, after glucagon injection into the VMH of rabbits with VMH lesions and the parietal cortex of intact rabbits, hepatic acetate metabolism did not differ from that of the control rabbits, which received saline injection into the same brain regions. These observations support the hypothesis that the VMH are parts of a glucagon-sensitive brain regulator system in the hepatic acetate metabolism.

Acetates↗
PubMed1987

Influence of electrical stimulation of the limbic structure on glucagon level in rabbit's plasma.

Amygdala (AMYG) stimulation caused marked increase in the circulating level of glucagon and these stimulatory effects were abolished by lesions of stria terminalis (ST). Stimulation of dorsal hippocampus (DHPC), on the other hand, greatly decreased the glucagon level and lesions of dorsal fornix (DFX) abolished these stimulatory effects. These results suggested that the reciprocal influence of AMYG and DHPC on plasma level of glucagon played some role in the regulation of glucagon release and these limbic structure had hypothalamic-mediated effects on glucagon release.

Amygdala↗
PubMed1986

Lateral hypothalamic area stimulation excites neurons in the region of the subfornical organ with efferent projections to the hypothalamic paraventricular nucleus in the rat.

Fifteen neurons in the region of the subfornical organ (SFO) were antidromically activated by electrical stimulation of the paraventricular nucleus (PVN) in the rat. Electrical stimulation of the lateral hypothalamic area (LHA) excited the activity of 9 of the identified units, but did not affect the remaining units. The excitatory response of the identified units was blocked by microiontophoretically (MIPh) applied saralasin (Sar), an angiotensin II (ANGII) antagonist, but not by atropine (Atr), a muscarinic antagonist. These results suggest that the LHA has an excitatory influence on the activity of neurons in the region of the SFO with efferent projections to the PVN and that the influence may be mediated by ANGII receptors.

Angiotensin II↗
PubMed1986

Leukoplakia-associated multiple carcinomas in patients with tongue carcinoma.

A series of 522 patients with a diagnosis of squamous cell carcinoma or carcinoma in situ of the tongue were reviewed and followed. Leukoplakia was found in 88 of these patients before and after the diagnosis of tongue carcinoma. A high incidence of multiple carcinomas in the oral cavity and pharynx (116 times greater than expected) was encountered in tongue carcinoma patients. The observed incidence of multiple oral carcinomas in the group with tongue carcinoma with leukoplakia was five times greater than that of the subjects without leukoplakia. The incidence of secondary esophageal carcinomas was also high, 12 times greater than the statistical expection. However, there was no increased occurrence of secondary esophageal carcinomas in the patients with leukoplakia.

Carcinoma in Situ↗
PubMed1986

The applicability of noninvasive His bundle electrogram to assessing the effect of digitalis on atrioventricular conduction.

His bundle electrograms were recorded by a signal averaging technique using the Takayasu vectorial lead system, and effects of ouabain on the atrioventricular conduction were investigated using Wistar rats. Ouabain was given intraperitoneally at 30 min intervals in doses of 1-40 mg/kg. When ouabain dosage was increased to 20 mg/kg, the prolongation of PQ interval became prominent and P waves were hidden on the preceding T waves. Dose-related prolongation of PQ and AH intervals was observed in the 1-15 mg/kg dosages. Ouabain-induced ventricular arrhythmias occurred in the 30 mg/kg dosage. Dose-related prolongation of QRS duration and HV interval was observed in the 1-25 mg/kg dosages. These prolongations were significant by the analysis of variance (p less than 0.01). Prolongation of PQ and AH intervals is probably due to a digitalis-induced increase in parasympathetic nerve activity. However, the reason for the prolongation of HV interval and QRS duration was uncertain. Direct effects of ouabain on the conduction system, or central nervous system effects of ouabain on cardiovascular function were speculated. These results suggest the applicability of the noninvasive record of His bundle electrogram to assessing the digitalis effect even on the human atrioventricular conduction.

Animals↗
PubMed1986

Experimental study on the relationship between cardiac arrhythmias and sleep states by ambulatory ECG-EEC monitoring.

The relationship between cardiac arrhythmias and sleep states was investigated in rats using the ambulatory ECG-EEG monitoring system under the 14/10 light-dark illumination schedule. Records of 14 rats obtained over 94 days were analyzed. Bradyarrhythmias (SA block and AV block) and ventricular arrhythmias [ventricular premature contraction (VPC) and short run of VPCs (ventricular tachycardia, VT)] were observed. Average number of episodes of bradyarrhythmia per day was 7.5, and the ratio of SA block to AV block was 34.9% to 65.1%. Average VPC or VT occurrence per day was 0.9 or 0.1 times, respectively. Sleep states were divided into alertness, slow-wave sleep, and paradoxical sleep, and the relationship between sleep states and arrhythmias was investigated. Bradyarrhythmias appeared predominantly during paradoxical sleep, while ventricular arrhythmias appeared during alertness as well as paradoxical sleep. Bradyarrhythmic episodes decreased by right or left vagotomy 78% or 70%, respectively. Sinus bradyarrhythmias disappeared almost completely by the right vagotomy, while the occurrence of AV block decreased by the right or left vagotomy. Circadian rhythms in arrhythmias were also analyzed by the cosine-fitting technique, and significant circadian rhythms were demonstrated in both bradyarrhythmias and ventricular arrhythmias. Acrophases were 9:56 A.M. and 1:47 A.M., respectively. Occurrence of VT was rare, but the most frequent incidental time zone was immediately following transition from light effects (rest) to dark (activity). This knowledge of circadian rhythm effects in arrhythmias must be incorporated into improved treatment of arrhythmias.

Animals↗