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Biomedical subjects

T Furuta

Publications and source records attributed to T Furuta.

At least 325 records · Page 18Linked to original sources
PubMed1988

Selective effect of doxorubicin suspended in lipiodol on VX2 carcinoma in rabbits.

When Lipiodol Ultra-Fluid (Lipiodol) was given through arteries feeding the tumor, this material was retained in the tumor. After mixing Lipiodol and doxorubicin (adriamycin; ADR), the effect of this antitumor agent on VX2 carcinoma inoculated into the hindlimb in 57 rabbits was investigated. Size of the tumor remarkably decreased in the rabbits treated with ADR 2 mg/kg suspended in Lipiodol and given through the femoral artery. Intraarterial injection of ADR 2 mg/kg alone led to a transient decrease in size of the tumor, but there was a regrowth. The result was comparable to a finding in a group in which half the dose of ADR (1 mg/kg) suspended in Lipiodol was given intraarterially. When ADR 2 mg/kg mixed with Lipiodol was injected directly into the tumor, growth of the tumor was not completely inhibited. Lipiodolized ADR has a prominent antitumor effect, and Lipiodol has the potential to be applied as a carrier of anticancer drugs.

Animals↗
PubMed1988

Precontraction-induced contractile response of isolated canine portal vein to alpha-2 adrenoceptor agonists.

The responses of isolated canine portal veins, in either transverse or longitudinal strip, to alpha-2 adrenoceptor agonists were examined. B-HT920, a selective alpha-2 adrenoceptor agonist, did not elicit an appreciable response in the transverse strips of the portal vein under resting tone (0.5 g/mm width). When the preparation was partially precontracted with phenylephrine, prostaglandin F2 alpha, KCl, Bay K 8644, acetylcholine, 5-hydroxytryptamine, histamine, or A23187, B-HT920 evoked concentration-dependent contractile responses (3 x 10(-9)-10(-6) M). Maximum contractions, which depended on the precontraction levels and the precontracting substances, ranged from 10-35% of those evoked by norepinephrine 10(-5) M. Similar precontraction-dependent contractile responses were obtained in the longitudinal strips. Concentration-response curves of B-HT920 in the transverse strips precontracted with prostaglandin F2 alpha were shifted by yohimbine to the right, but not by prazosin. Schild analysis yielded a slope of unity and a pA2 of 8.79. Clonidine also showed a similar precontraction-dependent contractile response. The lower part of the concentration-response curve of clonidine was shifted by yohimbine. These results may be explained by the presence of postsynaptic alpha-2 adrenoceptors in canine portal vein, which mediate a contractile response under certain conditions.

Adrenergic alpha-Agonists↗
PubMed1988

Electrophysiologic effects of a novel Ca antagonist, SA2572, in isolated rabbit and guinea pig hearts.

Cardiac effects of SA2572, a newly synthesized Ca antagonist, were evaluated in guinea pig and rabbit hearts with electrophysiologic technique. SA2572(10(-6)-10(-5) M) decreased the upstroke velocity (Vmax) and the duration of the action potential (APD30) in guinea pig papillary muscles in a concentration- and frequency-dependent manner without affecting the resting potential. The slow responses (high K+ + isoproterenol) were suppressed by SA2572 at 10(-6) M. In rabbit sinus node, SA2572(10(-7)-5 x 10(-6) M) caused a concentration-dependent decrease in the amplitude and Vmax of the action potential and tended to prolong the spontaneous cycle length. In Langendorff-perfused rabbit hearts electrically driven at 2 Hz, SA2572(5 x 10(-8)-10(-6) M) produced concentration-dependent prolongations of the atrio-His bundle conduction time (A-H interval) and the His bundle-ventricular conduction time (H-V interval) concomitantly with a reduction of the developed tension of the ventricular muscle. These effects of SA2572 on the A-H and H-V intervals were more pronounced at higher stimulation frequency. Enantiospecificity was observed in these actions of SA2572, (-)-isomer of SA2572 having more potent inhibitory effects on slow channel-dependent than on fast channel-dependent phenomena. These results indicate that SA2572 has characteristics of both slow and fast channel blockers, and that these inhibitory effects are frequency dependent.

Action Potentials↗
PubMed1988

Excitatory cholinergic innervation in canine portal and mesenteric veins.

A possibility that the canine portal and mesenteric veins may have an excitatory cholinergic innervation similar to that observed in the middle segment of the inferior vena cava (IVC) was investigated. After adrenergic blockade with prazosin, contractile responses of isolated longitudinal strips of the portal and mesenteric veins to transmural electrical stimulation were greatly diminished. Subsequent anticholinesterase (neostigmine or physostigmine) treatment, however, revealed in the nerve-evoked contraction a component that was antagonized by atropine. The same phenomenon was also observed in circular strips of the portal and mesenteric veins but was absent in those of the external jugular, saphenous, and splenic veins. In accord with the results of nerve stimulation, concentration-response curves of acetylcholine-induced contraction were shifted leftward by neostigmine in strips of the portal and mesenteric veins as well as of the middle segment of IVC. In contrast, no shift was observed in 12 other different sites of the venous system. Cholinesterase staining demonstrated positively stained smooth muscle and nerve fibers in the portal and mesenteric veins and in the middle segment of IVC. These findings indicate the existence of excitatory cholinergic innervation in the portal and mesenteric veins, which may reflect the common embryological origin of smooth muscle of these veins with the intestinal muscle.

Acetylcholine↗
PubMed1988

Hyperthermia for brain tumors: improved delivery with a new cooling system.

Hyperthermia has emerged as an adjunct to other forms of brain tumor therapy. Interstitial microwave irradiation is an effective method of inducing localized brain hyperthermia. One of the problems with this technique, however, is the overheating of tissue adjacent to the antenna. In this study, a cooling system for the interstitial microwave antenna was developed for the purpose of providing uniform and accurate heating by the elimination of overheating. The ability to generate more uniform hyperthermic fields was evaluated in normal monkey brains. Six monkeys under general anesthesia and controlled respiration underwent parietooccipital craniectomies 4 x 4 cm in size. The antenna cooling system was constructed of a silicone tube 5.0 mm in outer diameter. Silicone-coated interstitial microwave antennae 1.5 mm in diameter were used. A single antenna or a square array (1.6 cm on a side) of 4 antennae was inserted into the brain with the coupled system to a depth of 2 cm. The brain tissue was heated by 2450-MHz microwave irradiation. Temperature distributions were mapped using nonperturbing thermocouples. These thermal profiles were compared with those generated without the cooling system. In the experiments with the single antenna, the antenna cooling system eliminated the overheating and rapid radial falloff in temperature, without a reduction of the hyperthermic field. In the four-antennae experiments using the cooling system, the thermal field was dramatically flattened with minimal reduction in size; however, the area maintained at a therapeutic temperature range (42-45 degrees C) was significantly enlarged by the cooling system.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Factors influencing fibrin-induced pulmonary edema.

Effects of depth of anesthesia, pH of fibrinogen and thrombin, and interventions in the vagus nerves on the development of fibrin-induced pulmonary edema were examined in the rat. Rats were anesthetized with an intraperitoneal injection of pentobarbital sodium, 25 or 50 mg/kg. Solutions of fibrinogen and thrombin at the same pH were separately injected into the cisterna magna. The pH values were adjusted to 6.5 or 8.5 with Tris buffer. Interventions in the vagus nerves, which consisted of atropine administration at a dose of 1 mg/kg, i.v. or bilateral vagotomy, were performed before the intracisternal injection of fibrinogen and thrombin. Animals in which no interventions in the vagus nerve was performed were designated as intact rats. Lung-water ratio was calculated as a ratio of the difference between wet and dry lung weight to dry lung weight. Incidences of pulmonary edema and lung-water ratios were lower under deep anesthesia than under light anesthesia. Both parameters were low in the vagotomized rats treated under deep anesthesia with fibrinogen and thrombin at a pH of 8.5, as compared to those treated similarly at pH 6.5. This phenomenon was not observed under light anesthesia. Interventions in the vagus nerves influenced the development of pulmonary edema to various degrees, depending on the pH values of the injected fibrinogen and thrombin. As suggested from these results, well-defined, specific conditions are required for investigating the mechanism triggering the development of fibrin-induced pulmonary edema.

Anesthesia↗
PubMed1988

Prolonged inhibitory effects of nilvadipine (FR34235) following washout in isolated rabbit aorta and mesenteric artery.

Duration of the inhibitory effects of nilvadipine and some other Ca2+ entry blockers following washout was studied in isolated rabbit aorta and distal portion of mesenteric artery. The inhibitory effects of nilvadipine on KCl-induced contraction of aorta lasted longer than those of diltiazem, nifedipine, and nicardipine. Durations of nilvadipine were dose-dependently prolonged. The 50% recovery time, a parameter of the duration of action following washout, of nilvadipine at 10(-9) and 3 X 10(-9) M was 2.5 and 3.2 h, respectively. The long-lasting inhibitory effects of nilvadipine were pronounced at low [Ca]o. Similar prolonged actions of nilvadipine, compared with those of diltiazem and nifedipine, were observed in norepinephrine (NE)-induced contraction of the distal portion of mesenteric artery, of which tonic contractions were highly sensitive to Ca2+ entry blockers. Despite the long action of nilvadipine after washout in mesenteric artery, the onset of the inhibition of NE contraction was prompt. These pharmacological properties of nilvadipine, especially those seen in mesenteric artery, may be consistent with its long action as an antihypertensive agent.

Animals↗
PubMed1988

[Early diagnosis of metastatic brain tumor].

For the early diagnosis of metastatic brain tumor, careful and long-term follow-up is important when the primary tumor has already been found. Metastatic brain tumor should be suspected whenever neurological symptoms develop in such a patient. In the cases of lung cancer or lung metastases, CT scan of brain should be taken even if the patients have no neurological symptoms, because lung cancer frequently metastasizes to the brain and other cancers metastasize to the brain via the lung. When the primary sites are unknown, primary brain tumors should be distinguished. Relatively rapid progression of symptoms including mental disturbance, multiple lesions on CT scan, lesions on chest X ray film, careful cerebral angiogram and MRI are helpful for the differential diagnosis.

Biomarkers, Tumor↗
PubMed1988

Distinctive characteristics of the splenic vein in the dog. Its morphological and pharmacological discontinuities with the portal vein and splenic capsule.

Vascular characteristics of the splenic vein are entirely different from the portal vein in the dog. We compared the responsiveness of the splenic capsule, which contains abundant smooth muscle with the portal and splenic veins. With respect to potentiation of acetylcholine-induced contraction by neostigmine, the relaxation response to isoproterenol and the contractile response to 5-hydroxytryptamine, the splenic capsule differed from the splenic vein, but was rather similar to the portal vein. A site of morphological and pharmacological discontinuity between the portal vein and the splenic vein occurred at the junction of the splenic vein and the left gastric vein to form the gastrosplenic vein. This junction may coincide with the site of connection of the embryonic splenic vein, a newly formed efferent vein of the spleen, with the portal vein, which was reported by Miki [cf. Bevan et al.: 4th Int. Symp. on Vascular Neuroeffector Mechanisms; Raven Press, New York 1983]. On the splenic side, histological examination revealed that smooth muscle of the splenic capsule and trabeculae are interconnected, but did not extend to the splenic vein. At openings of the trabecular veins into the 'intrasplenic' portion of the splenic vein the trabecular smooth muscle continued to the extended capsule. The site of change in pharmacological responses was also found to be located between the trabeculae and the intrasplenic portion of the splenic vein. Thus the splenic vein can be regarded as a distinct segment of vessel inserted between the portal vein and the spleen. This may reflect differences in embryogenesis of their smooth muscle.

Animals↗
PubMed1988

[Assessment of interaction between the left and right ventricles using pressure-volume loops in various heart diseases].

To assess the interaction and interdependence of left and right ventricular function, ECG-gated radionuclide angiocardiography was performed immediately after cardiac catheterization during right atrial pacing for 11 patients with old myocardial infarction (MI), two with non-obstructive hypertrophic cardiomyopathy, one with aortic stenosis (AS), two with pulmonary infarction (PI), and one with neurocirculatory asthenia (NCA). Absolute left ventricular (LV) volume curves were obtained by the count-based method with attenuation factor corrections. Biventricular pressure and volume curves were digitized and synchronized to end-diastole, and pressure-volume (P-V) loops were constructed throughout a cardiac cycle. The stroke work index (SWI), the work index per min (WI/M) and the contractility index (CNTI) were calculated from the P-V loops. In a patient with NCA, LV end-diastolic volume decreased during rapid pacing, but no significant change in the LV end-systolic P-V relation was recognized. However, the entire right ventricular (RV) P-V loop was shifted toward the left during rapid pacing. In a patient with AS, the LV P-V loop was markedly enlarged and every parameter of LV function was much greater than that of the right ventricle due to increased LV afterload. The areas of RV P-V loops in two patients with PI were larger than those of other patients, because RV pressure was relatively high, and RV volume was increased. It is suggested that RV pressure and volume overloads prevail in patients with PI. In four MI patients with three vessel disease and having collateral circulation, the LV end-systolic P-V relationship was shifted toward the lower right, and every parameter (SWI, WI/M, CNTI) of LV function decreased by rapid pacing. Myocardial ischemia may be induced by rapid pacing stress, causing decreased LV contractility. It was concluded that the P-V loops obtained by RNA and catheterization are clinically useful for estimating the interaction and interdependence between right and left ventricular hemodynamics.

Adult↗
PubMed1988

[Antitumor activity of CPT-11 against rat Walker 256 carcinoma].

The antitumor activity of CPT-11 on rat Walker 256 carcinoma was investigated. Intraperitoneal, intravenous or oral administration of CPT-11 caused a remarkable prolongation of the life span of Wistar rat implanted with Walker 256 intraperitoneally. Intravenous injection and oral administration of CPT-11 markedly inhibited the growth of subcutaneously implanted Walker 256. CPT-11 showed a considerable antitumor activity by continuous intravenous injection against the solid type Walker 256.

Administration, Oral↗
PubMed1987

Determination of stable isotopically substituted histidine in human plasma by gas chromatography-mass spectrometry.

A gas chromatographic-electron-impact mass spectrometric method for the determination of stable isotopically substituted histidine in human plasma has been developed. Histidine was derivatized to alpha N-trifluoroacetyl-imN-carbethoxyhistidine n-butyl ester (TCB derivative) by a three-step reaction: an initial esterification by 3 M n-butanolic hydrochloric acid, followed by trifluoroacetylation with trifluoroacetic anhydride and then ethoxycarbonylation with diethyl pyrocarbonate. Quantitation was carried out by selected-ion monitoring on the molecular ions (m/z 379, 383 and 385) of the respective TCB derivatives of histidine, [1-15N,5,beta,beta-2H3]histidine (histidine-[M + 4]) and [1,3-15N2,5,alpha,beta,beta-2H4]histidine (histidine-[M + 6]). The sensitivity, specificity, precision and accuracy of the method were demonstrated to be satisfactory for application to a pharmacokinetic study of histidine after administration of a trace amount of stable isotopically substituted histidine (histidine-[M + 4]) in humans.

Chemical Phenomena↗
PubMed1987

Advanced gastric cancer successfully resected following cisplatin therapy: report of a case.

A case of unresectable advanced gastric cancer was treated with cis-dichlorodiammine platinum (CDDP) at a dosage of 30 mg/day for 5 days every month after operation. After three courses of administration, examinations revealed that the tumor had disappeared, and an evaluation of complete response was made. Four months later, a second-look operation was performed; and it was found that the cancer was smaller than a thumb and could be resected radically. No significant side effects were observed during CDDP therapy.

Adenocarcinoma↗
PubMed1987

Growth of 9-L and RT-9 gliosarcoma in female rats.

Published studies of 9-L and RT-9 gliosarcoma have been done only in male rats and it is widely assumed that these tumors do not grow in female rats. In this study 9-L and RT-9 gliosarcoma was inoculated into the brains of male and female Fisher CD rats. The tumors grew with essentially the same incidence and survival time in both sexes, confirming that female rats can be used as well as male rats in experiments using RT-9 and 9-L gliosarcomas.

Animals↗
PubMed1987

Detection of circulating antigens of Pneumocystis carinii in human sera by a sandwich enzyme-immunoassay.

A countercurrent immunoelectrophoresis test has been used for detection of circulating antigens of Pneumocystis carinii in humans; however, this study describes another experiment by sandwich enzyme-immunoassay. Antiserum was prepared by immunizing rabbits with P. carinii cysts which had been propagated in athymic nude rats. Profiles of time course in patients with the positive antigenemia show that P. carinii antigens are detectable prior to an onset of acute pneumonia. Since the sandwich enzyme-immunoassay has an ability of comparing serially monitored levels of the antigen in a quantitative value, the method is to be widely used as a clinical laboratory examination.

Animals↗
PubMed1987

Continuous infusion of vecuronium: the effect of anesthetic agents.

The authors studied the effects of enflurane, isoflurane, and fentanyl, each in combination with 60% nitrous oxide, on the vecuronium infusion rate necessary to maintain constant 90% depression of control muscle twitch tension. Thirty healthy surgical patients were given an initial 0.1 mg/kg bolus of vecuronium, followed by an infusion of vecuronium at an initial rate of 1.0 microgram . kg-1 . min-1. After 1 h of steady-state 90% twitch depression, plasma vecuronium concentrations (Css90) were measured by capillary column gas chromatography. Total plasma clearance of vecuronium was estimated using Css90 values. Vecuronium infusion rates (mean +/- SD) were similar for patients given enflurane (0.28 +/- 0.13 microgram . kg-1 . min-1) and isoflurane (0.30 +/- 0.13 microgram . kg-1 . min-1), but significantly higher in patients given fentanyl (0.92 +/- 0.37 microgram . kg-1 . min-1). Values for Css90 in the patients receiving enflurane and isoflurane were similar (71 +/- 34 and 72 +/- 44 ng/ml, respectively), but significantly higher in those receiving fentanyl (165 +/- 48 ng/ml). Total plasma clearance was similar during enflurane, isoflurane, and fentanyl anesthesia (4.4 +/- 2.6, 4.6 +/- 1.2, and 5.6 +/- 1.9 ml X kg-1 min-1, respectively). The authors conclude that patients receiving isoflurane and enflurane require markedly lower vecuronium infusion rates to achieve 90% neuromuscular blockade than those receiving fentanyl. The enhancement of neuromuscular blockade by isoflurane and enflurane represents a change in the pharmacodynamics of vecuronium-induced neuromuscular blockade, rather than a change in pharmacokinetics.

Anesthetics↗