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Biomedical subjects

K Sakurai

Publications and source records attributed to K Sakurai.

At least 253 records · Page 14Linked to original sources
PubMed1988

[Management of hemoperitoneum due to rupture of visceral branches of the aorta with a cylinder-type balloon catheter].

We have designed a cylinder-type balloon catheter and devised a new procedure for the management of the aneurysm in a condition difficult for treatment. This balloon catheter consists of a balloon located at the tip of a catheter. The balloon has a central lumen for maintaining the distal aortic bloodflow and can be inflated at various intended sites. The catheter with a deflated balloon was inserted into the abdominal aorta upward through a vascular graft sutured at the side of the aorta. In the case of a ruptured visceral artery, e.g., celiac axis or superior mesenteric artery, controlling of hemorrhage is very difficult because the ruptured lesion is surrounded by an intricate anatomical structure and therefore it is necessary to do the highly invasive procedure of aortic cross-clamping. Therefore we attempted this time to use the device in the management of this disease. In experimental investigation in dogs, this balloon selectively blocked the blood flow to the visceral branches successfully while maintaining the distal aortic flow. With this method, the various hemostatic procedures can be performed satisfactorily without concern for complications, namely renal failure provided that hemorrhage is easy to control in a short time without the aortic clamp. As mentioned above, this instrument will be useful for the management of rupture of the visceral artery and so reduce its mortality rate.

Animals↗
PubMed1987

Physiological assay of liposome-mediated transport of a drug across Xenopus intestine: cell-liposome interaction.

(1) The antagonistic effect of atropine methyl bromide entrapped in liposomes on contraction of Xenopus intestine in vitro induced by acetylcholine was studied. The results provided some insight into cell-liposome interaction. (2) Acetylcholine (0.1 mM) was added to the medium in the bath (serosal solution), while liposomes containing atropine methyl bromide in their internal and external phases were added on the mucosal side of the intestine. Large multilamellar liposomes were prepared from egg lecithin (phosphatidylcholine, PC) and cholesterol in various molar ratios. Atropine methyl bromide had most effect in liposomes composed of PC and cholesterol in a ratio of 7:3, less in those with a ratio of 4:5, and none in those with a ratio of 9:1. These effects were parallel with the sizes of these liposomes, determined by quasi-elastic light-scattering; that is, the larger the liposomes, the greater was their effect. Addition (to the liposomes) of phosphatidic acid, the negative charge of which increases the distance between the lamellar layers, increased the effect, indicating that atropine methyl bromide in the space between lamellar layers was effective. Another type of liposomes in which atropine methyl bromide was present only in the external phase of liposomes was as effective as liposomes in which atropine methyl bromide was present in both the internal and external phases. (3) From these results the following new model for liposome-mediated stimulation of transport of atropine methyl bromide is proposed. Large multilamellar liposomes have structural defects in their external lamellae through which atropine methyl bromide in the mucosal solution can penetrate into the space between the external lamellar layers and move into intestinal cells through regions of fusion between the outermost layers of the liposomes and the cell membrane.

Acetylcholine↗
PubMed1987

beta-D-xylosides and their analogues as artificial initiators of glycosaminoglycan chain synthesis. Aglycone-related variation in their effectiveness in vitro and in ovo.

A series of aryl and alkyl O-beta-D-xylosides and their analogues with S, NH or CH2 in the glycosidic linkage were prepared and examined for their ability to act as artificial chain initiators of chondroitin (dermatan) sulphate synthesis in embryonic chick cartilage, foetal rat skin and 6-week-old-rat aorta under conditions where normal protein-core synthesis was inhibited by cycloheximide. For all these tissues in culture, phenyl O-beta-D-xyloside and phenyl beta-D-thioxyloside were clearly more effective than the corresponding N-xyloside and homo-C-xyloside. Introduction of a carboxy group to the para position of their aglycone yielded derivatives with far lower initiator activity. In a concentration range lower than 0.1 mM, the effectiveness of alkyl beta-D-thioxyloside was greatly influenced by the carbon number (n) of the alkyl group and was at a maximum at n = 7 or 8 for the cartilage, at n = 5 for the skin and at n = 4 for the aorta. In the beta-xyloside-treated cartilages, the average length of newly formed chondroitin sulphate chains reflected the chain-initiator activity of added xyloside, i.e. the higher the initiator activity, the shorter the average chain length. In the skin and aorta, none of the drugs could relieve the inhibition of heparan sulphate synthesis caused by cycloheximide. Fertilized hens' eggs were each injected on day 9 with 9.2 mumol of beta-xyloside and the skeletal systems of embryos were examined a week later. The embryos treated with beta-xylosides of relatively high initiator activity showed a 30-40% decrease in the overall growth rate of skeletons, whereas those treated with beta-xylosides of low initiator activity showed little or no decrease in the growth rate. The results are consistent with the notion that the observed change in skeletal morphology results mainly, if not completely, from beta-xyloside-induced synthesis of core-protein-free chondroitin sulphate, and further suggest that a procedure employing a series of beta-xyloside homologues with various initiator activities will furnish an easily applied criterion on which to test the specificity of xyloside action on biological processes.

Animals↗
PubMed1987

Influence of PSK (Krestin) on resistance to infection of Pseudomonas aeruginosa in tumor-bearing mice.

C3H/He mice were inoculated with Pseudomonas aeruginosa by various routes 1 day after X5563 transplantation or 4 days after cyclophosphamide (CY) administration. Administration of PSK (Krestin) i.p. or p.o. to the tumor-bearing mice or CY-treated tumor-bearing mice resulted in an increase in survival rates. Viable P. aeruginosa were inoculated i.v. on day 0 into mice inoculated with tumor cells on day -12 and vaccinated with killed P. aeruginosa on day -10, or into mice inoculated with tumor cells on day -15, treated with CY on day -14 and vaccinated on day -10. Resistance to infection, which is enhanced by vaccination, was depressed by tumor burden or treatment with CY, but such depression was prevented by PSK administration.

Adjuvants, Immunologic↗
PubMed1987

Radiation-induced occlusion of the artery in the distal lower extremity--a case report.

In a 54 year-old man, a symptomatic occlusion of the popliteal artery and its trifurcation occurred following radiotherapy. Three years following curative radiotherapy to the upper tibia for metastatic renal cell carcinoma, he began experiencing intermittent claudication of the calf, which suddenly progressed to severe rest pain and coldness of the foot, and eventually to ischemic ulcer. Angiogram revealed an atherosclerotic occlusion well localized within the field of the previous irradiation. The significance of this rare entity is discussed from various aspects.

Arterial Occlusive Diseases↗
PubMed1987

Epicardial mapping during induction of nonsustained polymorphic ventricular tachycardia in a 7-day-old canine myocardial infarction model.

Programmed electrical stimulation and epicardial mapping were performed to study electrophysiologic mechanisms for induction of nonsustained polymorphic ventricular tachycardia in 29 dogs with 7-day-old myocardial infarction. Nine dogs had 15 different episodes of reproducible monomorphic ventricular tachycardia (11 sustained and 4 nonsustained) (group A). Seven episodes of polymorphic ventricular tachycardia (group B) were induced in six dogs, three of which degenerated into ventricular fibrillation. Epicardial activation time during premature stimulation at the time of tachycardia induction was more prolonged in group A than in group B (183 +/- 43 vs 123 +/- 35 msec, p less than 0.01). Furthermore, induction of ventricular tachycardia was preceded by the development of functional block in 13 of 15 group A tachycardias, but in only three of seven group B tachycardias. During polymorphic ventricular tachycardia, epicardial activation patterns were radial from the earliest epicardial activation site, similar to those observed during left ventricular endocardial pacing. QRS polymorphism was associated with a beat-to-beat variation in the earliest epicardial activation site. In conclusion, inducibility of nonsustained polymorphic ventricular tachycardia is less dependent on the epicardial activation sequence than on monomorphic ventricular tachycardia.

Animals↗
PubMed1987

Local myocardial electrogram and potassium concentration changes in superficial and deep intramyocardium and their relations with early ischaemic ventricular arrhythmias.

Bipolar myocardial electrograms and extracellular potassium concentrations were simultaneously monitored using double barrelled probes during 30 min of acute ischaemia in 15 dogs in vivo. The responsiveness of the time from the onset of the limb lead electrocardiogram to the peak deflection of the local electrogram to extracellular potassium changes was more prominent in superficial intramyocardium than in deep intramyocardium, despite similar changes in potassium concentration in both layers. The changes in electrogram duration and amplitude were related to extracellular potassium concentration both in superficial and deep intramyocardium. Immediate phase ventricular arrhythmias (within the first 10 min of acute ischaemia) were characterised by delayed activity mainly due to an increase in the time to peak of the electrogram in superficial intramyocardium. In contrast, in dogs showing delayed phase arrhythmias (within 10-30 min of acute ischaemia) delayed activity associated with pronounced changes in potassium concentration and electrogram duration and amplitude were noted in deep intramyocardium. Thus the two phasic appearances of early ischaemic ventricular arrhythmias with different origins seem to be related to the features of the conduction pathway in superficial intramyocardium and the severe local electrogram changes associated with a pronounced increase in extracellular potassium concentration in deep intramyocardium.

Acute Disease↗
PubMed1987

Involvement of endogenous noradrenaline release in methylene blue-induced contraction of isolated rabbit aorta.

The vasocontractile response to methylene blue (Meb) was investigated in isolated rabbit aorta. Meb (1-100 microM) induced a slowly developing contraction after a long latency in rabbit aortic strip. The maximal contraction was obtained by 50 microM Meb, which corresponded to 1 microM noradrenaline (NA)-induced contraction. Once the maximal contraction was induced by Meb, the strip completely lost the contractile response to a further application of Meb. The usual NA-induced contraction, however, could be observed in such a Meb-insensitive aortic strip. Meb-induced contractions were not affected by atropine, diphenhydramine, methysergide, indomethacin, nordihydroguaiaretic acid and removal of endothelial cells from the aortic strip, but they were abolished by prazosin. In aortic strips from rabbits pretreated with reserpine (3.0 mg/kg, i.m.) for a day, Meb failed to induce contraction. Meb evoked the [3H] release from [3H]NA-preloaded aortic strips. In high performance liquid chromatographic analysis, a considerable amount of NA was found in the bathing fluid of the aortic strip in the presence of Meb. In addition, Meb pretreatment inhibited [3H]NA uptake by the aortic strip and abolished the contractile response to an electrical stimulation of adrenergic nerve terminals. Although Meb decreased the basal level of cyclic GMP in the aortic strip, Meb-induced [3H]NA release from the aortic strip was not affected by 8-bromo cyclic GMP. These results suggest that Meb-induced contraction of rabbit aorta is due to the release of endogenous NA from its storage pools of intramural adrenergic nerves through an independent mechanism of its cyclic GMP lowering effect. In addition, incubation of aortic strips with Meb resulted in depleting the storage NA and blocking the nerve function, suggesting that Meb might be useful for a pharmacological tool as an adrenergic neuron blocking agent in vitro.

Animals↗
PubMed1987

Examination of the direct effects of nicorandil, verapamil, propranolol, and nitroglycerin on the hypoxic canine myocardium.

Effects of intracoronary administration of verapamil (VER), nitroglycerin (TNG), propranolol (PRO), and nicorandil (NIC) on regional hypoxia were examined in 39 open-chest dogs. Distal left anterior descending coronary artery was perfused for 5 min with deoxygenated Krebs-Henseleit solution (KHS) in group 1 (n = 9), VER-containing (1.3 mg/dl) KHS in group 2 (n = 9), TNG-containing (0.5 mg/dl) KHS in group 3 (n = 7), PRO-containing (0.4 or 0.8 mg/dl) KHS in group 4 (n = 7), and NIC-containing (0.5 or 2.5 mg/dl) KHS in group 5 (n = 7). Transmural biopsy at 5 min revealed a less severe metabolic deterioration in the hypoxic myocardium in groups 2, 4, and 5, as evidenced by higher ATP content (2.99 +/- 0.73, 2.81 +/- 0.35, and 3.14 +/- 1.20 mumol/g in groups 2, 4, and 5, respectively) and lower lactate accumulation (5.16 +/- 0.59, 5.62 +/- 1.44, and 5.05 +/- 1.12 mumol/g in groups 2, 4, and 5, respectively) compared with those in group 1 (2.09 +/- 0.45 mumol/g in ATP and 8.77 +/- 2.34 mumol/g in lactate). Metabolic preservation by VER, PRO, and NIC were not mediated by changes in hemodynamics and regional myocardial contraction. On the other hand, any significant protective effects were not noted in group 3, despite a significant reduction in rate-pressure products. Under an aerobic condition these agents affected regional myocardial contraction in a different manner from each other.

Animals↗
PubMed1987

[A case of malignant melanoma, axillary lymph node metastasis proved by fine needle aspiration biopsy cytology].

We report the case of a 57-year-old man with a malignant melanoma in the subunguinal region of his right thumb associated with the palpable axillary lymph nodes. Its metastasis was confirmed by fine needle aspiration biopsy cytology. Prognosis if a malignant melanoma is protean by its stage. Thus information regarding the axillary metastasis is mandatory for deciding the therapeutic plan. Fine needle aspiration biopsy cytology is a useful technique for diagnosing lymph node metastasis.

Axilla↗
PubMed1986

Comparative effects of intracoronary administration of propranolol with systemic administration on hypoxic canine myocardium.

Myocardial protective effects of intracoronary administration of relatively small doses of propranolol were examined and compared with systemic administration in 20 open-chest dogs. In group 1 (n = 6) rate-pressure-product (R X P) did not change during 5-minute left anterior descending artery (LAD) perfusion with deoxygenated Krebs-Henseleit solutions (KHS). However, R X P decreased by the same degree in group 2 (n = 7), which received perfusion with KHS containing 0.4 or 0.8 mg/dl of propranolol, and in group 3 (n = 7) given LAD perfusion with original KHS and systemic administration of 0.02 to 0.04 mg/kg of propranolol. Total administered doses of propranolol were the same for groups 2 and 3. Transmural biopsy after 5 minutes of perfusion revealed less severe metabolic deterioration of hypoxic myocardium in group 2 when compared with that in group 1, as evidenced by higher ATP (adenosine triphosphate) (2.81 +/- 0.35 versus 2.23 +/- 0.45 mumol/g, p less than 0.05) and lower lactate content (5.62 +/- 1.44 versus 9.01 +/- 2.62 mumol/g, p less than 0.05). On the other hand, significant metabolic preservation was not noted in group 3. Sequential changes in regional myocardial contraction did not differ among the three groups. In conclusion, intracoronary administration of propranolol showed myocardial protective effects that were not mediated by the changes in hemodynamics and myocardial contraction.

Adenine Nucleotides↗
PubMed1986

The adult type pulmonary hamartoma in an 11-year-old boy.

Hamartoma of the lung occurs most often in persons after the age of 40, but quite rarely among children. This paper reports on an 11-year-old boy with a pulmonary hamartoma in the right upper lobe. The patient was asymptomatic, but a well demarcated, solitary, lobulated nodule with a "popcorn"-shaped calcification was visualised on chest x-ray film. An upper lobectomy was carried out to remove the lesion. The post-operative course was uneventful. Two years post-operatively, the child was symptom-free and has been developing normally.

Child↗