Biomedical subjects

T Segawa

Publications and source records attributed to T Segawa.

242 records · Page 14Linked to original sources

PubMedDate not supplied

Fluorescence digital image analysis of serotonin-induced calcium oscillations in single blood platelets.

The intracellular concentration of Ca2+ [( Ca2+]i) was monitored continuously in single rabbit blood platelets by digital imaging microscopy in conjunction with Fura-2, a specific Ca(2+)-indicator dye. Ionomycin as well as aluminium fluoride caused sustained increase in [Ca2+]i in the platelet, but oscillations of [Ca2+]i were not observed. Serotonin (5-HT) induced oscillatory increases in [Ca2+]i in the presence of 1 mM CaCl2; these had not been detectable in cell populations because the oscillations were not in synchrony. This effect of 5-HT was diminished when CaCl2 was omitted from the medium, and was antagonized by 1 microM ketanserin, a specific 5-HT2 receptor antagonist. Furthermore, DOI, a specific 5-HT2 agonist, had the same effect as 5-HT at lower concentration. A specific effector mechanism, not fully understood at present, therefore appears to mediate 5-HT2 receptors thereby allowing rabbit platelets to generate [Ca2+]i oscillations. It is suggested that protein kinase C in platelets might play a key role in the regulation of [Ca2+]i, and possibly in [Ca2+]i oscillations.

Aluminum↗

PubMedDate not supplied

Long-term survivors after hepatectomy for hepatocellular carcinoma.

Sixteen long-term (more than 5 years) survivors after hepatic resection performed for hepatocellular carcinoma (HCC) from 1970 to 1988, were reviewed. The mean age of the patients was 51 years. There were 11 males and 5 females. HBs antigen was positive in 9 patients. Liver cirrhosis was associated with 11 patients but its severity was designated as Child's A in all patients except one. The mean tumour diameter was 2.8 cm and was relatively small. At the first operation, limited procedures (i.e. partial hepatectomy and subsegmentectomy) were employed in 87.5% of patients. A large percentage of tumours were located in S5 and S6 segments. A recurrence of HCC occurred in 9 patients after the first resection. A second resection was carried out in 7 patients, in 2 of which a third resection was done. Transcatheter arterial embolization (TAE) was performed on 4 patients. These results show that, in addition to detection of small tumours and early resection, repeated operation or TAE for treatment of recurrent HCC was important in achieving long-term survival after HCC resection.

Carcinoma, Hepatocellular↗

PubMedDate not supplied

Evaluation of the maximal excretion rate of indocyanin green as a prognostic indicator in patients undergoing biliary decompression for obstructive jaundice.

To assess the postoperative outcome of jaundiced patients and to select the optimal timing for surgical intervention, indocyanin green (ICG) concentrations in the bile were measured after biliary decompression in patients with obstructive jaundice. The maximal excretion rate of ICG in the bile was calculated as a function of time (ICG Bmax). Among 59 patients with positive ICG Bmax values, morbidity was 15.2% and postoperative hospital mortality was 3.3%. However, the morbidity and mortality in nine patients with values between -0.5 and 0 were 88.8 and 44.4%, respectively. The 13 patients with in ICG Bmax below -0.5 had a 76.9% morbidity and a 61.5% mortality. The patients with ICG Bmax values below 0 showed a significantly higher morbidity and mortality than positive ICG Bmax patients. In patients showing ICG Bmax values below -0.5, surgery is contraindicated despite intensive postoperative care. The ICG Bmax value improved according to the increasing effect of biliary decompression. The index is useful not only as a prognostic index in the early phase of biliary decompression but also as an index of bile secretory capacity at a given time. By means of time course measurement of this index, the suitable time for operation can be determined. The ICG Bmax is a useful and reliable indicator in the assessment of hepatobiliary functional reserve in jaundiced patients after biliary decompression and prior to further surgical intervention.

Adult↗

PubMedDate not supplied

Effects of ulinastatin, an antiprotease, on alloxan-induced lung injury in dogs.

To determine if alloxan-induced lung injury could be prevented by an antiprotease, ulinastatin, we used three groups of five anesthetized, ventilated dogs. They were given saline (20 ml/kg/hr) infusion alone (saline group), alloxan (75 mg/kg) + saline infusion (alloxan group), or ulinastatin (50,000 U/kg) + alloxan + saline infusion (ulinastatin group). The course of all dogs was followed for three hours. In the saline group, extravascular lung water to blood-free dry weight (Qwl/dQl) was 3.22 +/- 0.31 g/g (mean +/- SE). The alloxan group presented the following significant findings: a decrease in white blood cell and platelet counts (44.2% and 68.2% of control, respectively) at five minutes; an increase in thromboxane B2 and 6-keto-prostaglandin F1 alpha (731.6% and 476.6% of control, respectively) at 15 minutes; an increase in beta-glucuronidase (124.8% of control) at 30 minutes; and an increase in Qwl/dQl (8.84 +/- 1.82 g/g) at the end of experiment. The addition of ulinastatin significantly reduced most alloxan-induced effects: differences in white blood cell counts, thromboxane B2, 6-keto-prostaglandin F1 alpha, and Qwl/dQl between the saline and ulinastatin groups were small. We conclude that ulinastatin significantly reduces the extent of lung water accumulation in alloxan-induced lung injury.

6-Ketoprostaglandin F1 alpha↗

PubMedDate not supplied

Inhibition by lombricine from earthworm (Lumbricus terrestris) of the growth of spontaneous mammary tumours in SHN mice.

The effects of lombricine extracted and purified from earthworm (Lumbricus terrestris) skin on the growth of palpable sizes (approximately 5 mm) of spontaneous mammary tumours were studied in SHN mice. In Experiment 1, daily subcutaneous injections of lombricine (0.3 mg/0.05 ml olive oil) inhibited markedly the growth of tumours associated with the retardation of the growth of preneoplastic mammary hyperplastic alveolar nodules. In 1H-NMR spectra, the experimental mice had lower serum levels of lactic acid and glucose than the control. On the other hand, urine of the former group contained higher levels of allantoin, creatine and creatinine than that of the latter. In Experiment 2, lombricine given as diet at the concentration of 120 mg/kg also inhibited the growth of tumours, though to a lesser degree than the injection. The treatment had little effect on 1H-NMR spectra of either serum or urine and normal and preneoplastic mammary gland growth. All results indicate that the inhibition by lombricine of the growth of mammary tumours is at least partly due to the maintenance of homeostasis of the body including the regulation of the excess uptake of glucose as a source of energy and nutrition.

Animals↗

PubMedDate not supplied

Suppression by beta-carotene-rich algae Dunaliella bardawil of the progression, but not the development, of spontaneous mammary tumours in SHN virgin mice.

We previously found that beta-carotene-rich algae Dunaliella bardawil markedly inhibited spontaneous mammary tumourigenesis of mice. This study was carried out to clarify whether D. bardawil inhibits the development or the progression or both of mammary tumours. A high mammary tumour strain of SHN virgin mice were given vitamin A deficient AIN-76TM diet supplemented with D. bardawil during the limited period of 3 months between 1-4 months of age (Experiment I: the stage of tumour development), 4-7 months (Experiment II: the stage of initiation and progression) or 7-10 months (Experiment III: the stage of progression). The concentration of beta-carotene in the diet was 5.1 x 10(-5)%. The respective controls received AIN-76TM diet containing retinyl palmitate (2.2 x 10(-4)%) during the same periods as in the experimental groups. Both the experimental and the control mice were fed a commercial diet during all other periods. The diets and tap water were provided ad libitum. In Experiment I, mammary tumour incidence was higher in the experimental group than in the control at all months examined except at 5 months of age, while the cause is not clear at present. Meanwhile, mammary tumourigenesis was significantly suppressed in the experimental mice compared to the controls in Experiments II and III. Whereas tumorous mice were higher than non-tumorous mice in blood levels of lactic acid and glucose in the control, mice given D. bardawil maintained the levels of non-tumorous mice even after the development of tumours. D. bardawil feeding also induced a higher glucose tolerance. All results strongly suggest that D. bardawil can inhibit the progression of spontaneous mammary tumours of mice by increasing the homeostatic potential of the host animals as well as by the well-known antioxidant function of beta-carotene in D. bardawil.

Adrenal Glands↗

PubMedDate not supplied

Effects of motherwort (Leonurus sibiricus L) on preneoplastic and neoplastic mammary gland growth in multiparous GR/A mice.

Chronic ingestion of methanol extract of the above-ground part of motherwort (Leonurus sibiricus L) in drinking water at the concentration of 0.5% enhanced the development of both pregnancy-dependent mammary tumours (PDMT) and mammary cancers originated from PDMT. By contrast, the treatment markedly suppressed the development of mammary cancers that originated from hyperplastic alveolar nodules (HAN) associated with the decreased formation of HAN. The incidence of uterine adenomyosis was also inhibited in mice given motherwort. The urinary excretion of allantoin, creatine and creatinine and glucose tolerance were stimulated by motherwort. The cause of discrepancy of the effects of motherwort on mammary cancers due to their origins is not clear at present. However, the stimulation by the agent of the excretion of any carcinogenic factors may at least partly contribute to its inhibition of mammary cancers originating from HAN.

Animals↗

PubMedDate not supplied

Interactions of carteolol and other beta-adrenoceptor blocking agents with serotonin receptor subtypes.

The importance of the anti-serotonergic activity of carteolol and other beta-adrenoceptor blockers in their efficacy as anti-migraine agents has been examined in the membrane fraction of rat brain frontal cortex and pig choroid plexus, using radioligand binding methods. Carteolol and l-propranolol, which are suggested to have anti-migraine activity in man, were found to be active inhibitors of the binding of [125I]ICYP to 5-HT1B recognition sites and of [3H]-8-OH-DPAT to 5-HT1A recognition sites. Carteolol is devoid of activity at 5-HT1C and 5-HT2 recognition sites, whereas l-propranolol shows substantial affinity for these receptor subtypes. Atenolol, another beta-adrenoceptor blocker with anti-migraine activity, is devoid of activity at any of the 5-HT receptor subtypes examined. The possibility that carteolol and other beta-adrenoceptor antagonists exert their pharmacological effects through central 5-HT receptor subtypes is discussed in relation to the potential mechanism of the anti-migraine activity of carteolol.

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