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Biomedical subjects

M Sakuma

Publications and source records attributed to M Sakuma.

At least 163 records · Page 9Linked to original sources
PubMed1987

[Studies on the elastic properties of vascular prostheses].

The difference of mechanical properties between a vascular prosthesis and its host arteries is suggested to be a contributing factor in graft failure and different methods have been used to evaluate the elasticity of arterial graft. In this study, a new type ultrasonic displacement meter combined with B-mode imaging was developed and dynamic compliance of four types of arterial grafts currently available for clinical use, human saphenous vein, human umbilical vein, velour Dacron and expanded polytetrafluoroethylene (EPTFE), were measured in vitro and in vivo. Dynamic compliance was derived from intraluminal pulsatile pressure and diameter change of the vessel obtained from the displacement meter. The in vitro examination showed that the human umbilical vein was the most compliant among human saphenous vein, velour Dacron and EPTFE. The human saphenous vein was compliant in low intraluminal pressure less than 50 mmHg, and became more stiff than the human umbilical vein with increasing pressure. After experimental implantation, the compliance of human umbilical vein and EPTFE showed similar characteristics in vitro, with the exception of velour Dacron, which was progressively less compliant. In comparison of compliance of human arteries to that of arterial grafts, a mismatch in compliance between grafts and host arteries was obviously demonstrated.

Blood Vessel Prosthesis↗
PubMed1986

Surgical treatment of aortic dissection: application of Ivalon sponge to the dissected lumen.

With canine disease models for aortic dissection, we performed comparative evaluations of several surgical procedures for the management of this dissection. From these experimental procedures, we developed a new operative technique, the Ivalon sponge occlusion method, designed to promote thrombus formation and to mesh (organize) effectively with the tissue ingrowth of the peripheral dilated, dissected aortic lumen. The details of the technique are described. It has been used successfully in 12 patients with DeBakey type I and type III aortic dissection. Based on our experimental and clinical evaluations, although the results are preliminary, we believe this operative technique is a simple, effective approach for the management of extended aortic dissection.

Adult↗
PubMed1986

Phasic changes in immunocytochemical stainability of pituitary luteinizing hormone cells associated with their ultrastructural changes during estrous cycle in the rat.

Changes in the immunoreactivity of pituitary luteinizing hormone (LH) cells and in their fine structure were studied in 4-day-cyclic female rats along with the radioimmunoassay of pituitary and serum LH. Pituitary LH increased during diestrus (DE) and in early proestrus (PE) to a maximal level at noon of PE, followed by a marked decrease by 2100 h PE. Serum LH stayed at low levels in estrus (E) and in DE, while they displayed a significant increase at PE. Light microscopic immunocytochemistry distinguished intensely and weakly stained cells using rat LH beta antiserum. The populations of intensely stained cells were 80% at PE, 30% at E and 75% at DE. This suggests that all of the LH cells do not secrete LH synchronously on the afternoon of PE. Immunoreactivity of LH cells was related to the amount of secretory granules stored in the cells as determined by the superimposition technique. Analysis of the LH storage site by the protein A-gold method confirmed that the small secretory granules, which accumulated in LH cells at DE or PE, certainly contain LH. At least two LH cell types were distinguished: one is the oval or polygonal cell with flattened rER numerous mitochondria, abundant small secretory granules (about 200 nm), a well developed Golgi complex, and a round nucleus. The other has similar structural characteristics along with large secretory granules which are more than 300 nm in diameter. At noon of PE almost all of the LH cells were the first type while the second ones were mainly found at DE or E. The relationship of these LH cell types of the male gonadotrophs is discussed.

Animals↗
PubMed1986

A case of lactate dehydrogenase (LDH)-IgG complex formation which causes low plasma LDH activity and an abnormal LDH isozyme pattern.

A case of an LDH-IgG complex formation which causes low plasma LDH activity and an abnormal LDH isozyme pattern was reported. A patient had pericarditis and myocardial hypertrophy of asymmetrical septal hypertrophy type. The same IgG was recognized in pericardial effusion. From a column chromatographic study, the molecular weight of LDH-IgG complex was estimated as being about 490,000. This complex was speculated as the IgG1-LDH2. The mechanism by which LDH-IgG is formed and the relationship between the complex itself and cardiac diseases remain unknown.

Aged↗
PubMed1985

Tympanograms of otitis media with effusion: an experimental study.

A sufficient explanation concerning tympanogram (TG) of otitis media with effusion (OME) has not been reported. The purpose of the present study was to investigate the relationship between the types of TG and actual pathological status of the middle ear system by means of experimentally modified middle ear clefts. In the present experiments, human temporal bones, guinea pigs' bullae and plastic models were used. The results were as follows: (1) Water was gradually poured into the middle ear cleft through the Eustachian tube. When the water level rose above the umbo, the height of TG slightly exceeded that of the original TG. Further addition of water produced M-shaped TG, however, flat TG (type B) was not detected until the water-line nearly reached the aditus. A similar phenomenon was observed in the plastic models when the water level reached the aditus-equivalent-site. (2) Tympanometrically measured middle ear pressure (MEP) was almost equivalent to the actual MEP recorded by a manometer when the tympanic membrane was normal. However, this result could not be duplicated in flaccid or adhesive tympanic membrane cases. (3) A clear reduction in the height of TG in guinea pigs' bullae was observed with decreased air volume. In addition, shallow TG was produced by an occlusion of the aditus of the human temporal bones and of the aditus-equivalent-site of the plastic models. It was demonstrated that the TG pattern depends on the fluid volume and location, air volume of mastoid cavity, intratympanic pressure and eardrum condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Impedance Tests↗
PubMed1985

Hemodynamic effect of cilostazol on increasing peripheral blood flow in arteriosclerosis obliterans.

The novel synthetic antithrombotic drug, cilostazol (6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2(1H)-qui nolinone, OPC-13013) was orally administered in a dose of 200 mg/day to 4 patients with arteriosclerosis obliterans (ASO) in the lower extremities to evaluate the hemodynamic effects of the drug. After 2 weeks of treatment, tissue blood flow through the pedal vessels was measured in 8 legs by the venous occlusion method using a strain-gauge plethysmograph. The flow measured during reactive hyperemia was shown to have significantly increased from 5.04 +/- 1.90 to 9.05 +/- 4.77 ml/min/100 g tissue (p less than 0.05, t-test), the rate being 80.68 +/- 66.61% of the initial level. The drug was, therefore, considered to have high clinical potential in the treatment of chronic arterial occlusion such as ASO and Buerger's disease (thromboangiitis obliterans). The drug was also shown to be of value in supporting the reconstruction of circulation in the lower extremities.

Aged↗
PubMed1984

Characteristics of analgesia induced by noncatecholic phenylethylamine derivatives: possible involvement of endogenous opioid peptides and serotonin in phenylethylamine analog-induced analgesia.

Characteristics of the analgesic action of phenylethylamine derivatives, amphetamine, phenylethylamine (PEA), hydroxyphenylethylamine (OHPEA) and hydroxyphenylalanine (OHF), were examined. Pain threshold of mice was measured by using the hot plate method. OHPEA (50 mg/kg), amphetamine (0.5-8 mg/kg) or PEA (50 mg/kg) produced an analgesic effect in the absence of MAO inhibitor, and the analgesia was reversed by naloxone (5 mg/kg) or reserpine (2 mg/kg x 2). Ten mg/kg of PEA, 250 mg/kg of OHF and 10 mg/kg of OHPEA could not produce detectable analgesia, but they revealed analgesic activity when mice were pretreated with pargyline (100 mg/kg). Analgesia induced by a combined use of PEA, OHF or OHPEA with pargyline was inhibited by naloxone or p-chlorophenylalanine (PCPA), an inhibitor of serotonin synthesis. Amphetamine-induced analgesia was also blocked by PCPA. Analgesia induced by PEA or OHPEA was blocked by methysergide (2 mg/kg). From the above findings, it was concluded that PEA, OHPEA, OHF and amphetamine possess similar characteristics in their analgesic action, and their analgesic actions involve the participation of endogenous serotonin and endogenous opioid peptides.

2-Hydroxyphenethylamine↗