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Biomedical subjects

S Yamauchi

Publications and source records attributed to S Yamauchi.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Sequential coronary artery bypass grafting utilizing the internal thoracic and gastroepiploic artery as in situ grafts].

36 consecutive patients (male:female = 33:3, mean age 57.3) underwent sequential coronary artery bypass grafting (CABG) utilizing the left internal thoracic artery (LITA, n = 30), right gastroepiploic artery (RGEA, n = 8) as in situ grafts. Two patients received sequential bypass grafting with both grafts simultaneously. No right internal thoracic arteries were used except for one as a free nonsequential graft. Taking into account the adjunctive venous anastomoses and the arterial nonsequential anastomoses, there were 3.5 anastomoses per patients. Proxymal side-to-side anastomosis of LITAs were all constructed on the diagonal branches except for one on the proxymal Left Anterior Descending Coronary Artery (LAD), whereas that of the RGEAs were on the proxymal Right Coronary Artery (RCA) (2), distal RCA (6) or distal circumflex (1). Distal end-to-side anastomoses of LITAs were all on the LAD, and those of the RGEAs were on the distal RCA (3) or distal circumflex artery (5). Proxymal side-to-side anastomoses were always performed first, allowing us to assess the distal flow through the graft before we anastomose it to the distal branch. We routinely obtain a preoperative angiogram of the arterial grafts, which enable us to fully assess the suitability of the arteries as in situ grafts. There were no perioperative deaths, nor perioperative myocardial infarctions, however, two patients died of extracardiac causes at 42 and 68 days after operation respectively. For the thirty four survivors, followup was complete (4-49 months, average 12.3 months). One still had angina of Canadian Cardiovascular Society Classification (CCSC) class 2, and 33 were free of angina.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Clinical evaluation of a new type of centrifugal pump.

The major problems with existing centrifugal pumps are leakage, mechanical trauma, and thrombus formation. In consideration of these problems, a new compact centrifugal pump system was developed. The purpose of this study was to evaluate the new centrifugal pump system clinically. Ten patients underwent open heart surgery with a centrifugal pump or a roller pump. During surgery, hemodynamic and hematological data were obtained. A pulsatile assist device in the pump circuit was used in patients with severe heart disease. There was neither operative death nor hospital mortality, and there was no difference with regard to hemodynamic data between the two groups. The centrifugal pump groups, however, had significantly lower hemolysis, especially during prolonged cardiopulmonary bypass. This centrifugal pump could also create sufficient pulsatile flow with a pulsatile assist device. Postoperative macroscopic and microscopic findings demonstrated the smooth surface of the pump without thrombus formation. This centrifugal pump system might be useful for prolonged cardiopulmonary bypass.

Adolescent↗
PubMed1993

Use of intraoperative mapping to optimize surgical ablation of atrial flutter.

The purpose of this study was to develop a surgical treatment for atrial flutter using intraoperative activation sequence mapping to minimize the surgical procedure necessary to ablate the flutter. A canine model (n = 10) of left atrial enlargement was developed by creating a shunt from the left subclavian artery to the left superior pulmonary vein. Sustained atrial flutter was easily induced in this model. The flutter consisted of a single reentrant circuit that rotated around one or two anatomic obstacles linked by a region of functional block. Epicardial templates, consisting of 252 bipolar electrodes, were used to record activation time maps. After localization of the reentrant circuit, surgical incisions were placed to interrupt the pathways. In all 10 animals, flutter could be induced and intraoperative mapping localized the reentrant circuit. Seven circuits were in the right atrium and three were in the left atrium. The operation ablated all of the preoperative circuits. However, in 5 of the animals, flutter originating from a new circuit could be induced. Activation sequence mapping before and after operation demonstrates that there are multiple potential reentrant pathways in this canine model of atrial flutter. Therefore, all potential pathways must be surgically interrupted to prevent inducibility of atrial flutter.

Animals↗
PubMed1993

[Stabilization of ascorbic acid aqueous solution by protamine].

Protamine was found to stabilize ascorbic acid (AsA) in aqueous solution. The concentration of AsA (50 mumol/l) dissolved in 0.05 M phosphate buffer, pH 7, decreased by 57% after standing for 90 min at 30 degrees C, whereas 91% of AsA remained under the same conditions in the presence of 60 mumol/l protamine. When 0.5 mumol/l of copper ion (II) was added to the above AsA solution (0.05 M phosphate buffer, pH 7) in the absence of protamine, AsA decreased by 5% after standing for 15 min at 30 degrees C. On the other hand, 91% of AsA remained after 15 min and 52% of AsA remained after 90 min under the same conditions in the presence of 60 mumol/l protamine. Furthermore, the effect of protamine on the stability of AsA in various pH solutions (pH 1-10) was examined after standing for 90 min at 30 degrees C. Degradation of AsA was accelerated by increasing the pH from 1 to 10. On the other hand, the effect of protamine (60 mumol/l) on the stabilization of AsA was recognizable above pH 5 and degradation of AsA was controlled at higher pH. When 0.5 mumol/l of copper ion (II) was added to the above solutions in the absence of protamine, degradation of AsA was greatly accelerated above pH 5. When 60 mumol/l of protamine was added to the solutions, the effect of protamine on the stabilization of AsA was observed above pH 5 and degradation of AsA was controlled at higher pH.

Ascorbic Acid↗
PubMed1992

Mammotropes and somatotropes in the adenohypophysis of androgenized female mice: morphological and immunohistochemical studies by light microscopy correlated with routine electron microscopy.

Female mice were divided into androgenized (AF) and control (CF) groups. The AF mice were injected subcutaneously with testosterone propionate (Tp) and the CF mice with sesame oil at 5 days of age. Mammotropes (PRL cells) and somatotropes (GH cells) in the adenohypophyses of these mice when they became adults were studied with immunohistochemistry and morphometry by light microscopy correlated with routine electron microscopy. In CF mice, almost all of the PRL-immunoreactive cells (about 43% of all parenchymal cells) were type I (classical) PRL cells, and almost all of the GH-immunoreactive cells (about 30% of all parenchymal cells) were type I (classical) GH cells. Type II PRL cells accounted for about 0.4% of parenchymal cells, and type II GH cells were about 2.5% of all parenchymal cells. In AF mice, the percentages of PRL and GH cells were not significantly different from those of CF mice. Mammosomatotropes (Ms cells) in both groups were less than 1% of all parenchymal cells. Numbers of all parenchymal, PRL and GH cells, however, were increased significantly in AF mice when compared to those in CF, because the adenohypophysis was increased in volume in AF mice. Type I PRL cells were larger in AF than in CF. The ultrastructure suggested that type I PRL cells may show increased PRL synthesis and secretion in AF mice. Furthermore, AF mice, in which the hypothalamus is masculinized by the neonatal treatment with Tp, retained feminine characteristics in the population and size of PRL cells and GH cells in the adenohypophysis.

Androgens↗
PubMed1992

Immunohistological analysis in the distribution of cells in the fetal porcine adenohypophysis.

Adenohypophyses of porcine fetuses from 25 to 110 days of gestation were studied by immunohistochemical staining to ascertain the ontogeny of specific cell types and their spatial distribution in the pars distalis. No hormone-containing cells were found before 30 days of gestation. ACTH cells were observed first at 40 days, while GH and LH cells appeared first at 60 days. PRL cells were initially detected at 105 days. ACTH immunoreactive cells were also observed in the pars intermedia at 40 days. Blood capillaries were interposed between cell cords of the pars distalis after 40 days of gestation. ACTH cells were evenly distribution in all areas of the pars distalis except the rostral area (sex zone). GH cells were densely distributed in lateral wings of the pars distalis and immediately anterior to Rathke's lumen. PRL cells resembled GH cells in their distribution pattern, but PRL cells were fewer in number. LH cells were scattered in the sex zone of the pars distalis from 60 to 80 days of gestation. After 90 days, they became scattered throughout the pars distalis but were more numerous in the sex zone than in other areas. The inductive elements of adenohypophysial cells from Rathke's pouch epithelia are discussed. We hypothesize that cell cords of specific areas facing Rathke's lumen may differentiate into specific cell types of the pars distalis during fetal life.

Adrenocorticotropic Hormone↗
PubMed1992

[Combined superior-transseptal approach to the mitral valve].

We report a technique to improve exposure of the mitral valve apparatus. This technique that combines superior left atriotomy and interatrial septotomy can be helpful in patients with a small left atrium and reoperation. It has been used effectively in five patients and potential complication with this procedure has not occurred. The operative technique and indication are discussed in this paper.

Adult↗
PubMed1992

The effect of augmented atrial hypothermia on atrial refractory period, conduction, and atrial flutter/fibrillation in the canine heart.

The purpose of this study was to test the assumption that the cause for postoperative atrial flutter/fibrillation after cardiopulmonary bypass is inadequate atrial myocardial protection. Dogs were subjected to cardioplegic arrest for 60 minutes without augmented atrial hypothermia (seven dogs, control group) or augmented atrial hypothermia with topical atrial cooling (seven dogs, study group). Twenty-five electrodes (15 on the right atrium and 10 on the left atrium) were fixed on the atria to measure effective refractory period and conduction time. Data were taken before bypass, immediately after bypass, and 2 hours after bypass. During cardioplegic arrest the mean temperatures measured in the atria were significantly lower (p less than 0.001) in the study group (13.5 degrees +/- 7.0 degrees C) than in the control group (23.7 degrees +/- 3.2 degrees C). There was no significant change in the mean effective refractory period after bypass in the control or study groups or in the prevalence of inducibility of atrial flutter/fibrillation by extrastimulation (3/7 dogs in the control group and 2/7 in the study group). During right atrial pacing, total conduction times were significantly longer (p less than 0.025 at cycle lengths of 300 and 350 msec) in the control group (74 +/- 5 msec and 75 +/- 7 msec, respectively) than in the study group (65 +/- 9 msec and 64 +/- 8 msec, respectively) immediately after bypass. Two hours after bypass, however, there were no significant differences under the same conditions between the two groups. There were no significant differences in conduction during left atrial pacing after bypass. Comparing those atria that were inducible with those not inducible demonstrated a significantly increased dispersion of effective refractory period (90 +/- 23 msec versus 74 +/- 18 msec, p less than 0.05) and increased conduction time in the inducible group. We concluded that augmented atrial hypothermia during cardioplegic arrest had no effect on the inducibility of fibrillation, had no effect on repolarization, and had only a small effect on conduction, which resolved within 2 hours after bypass. However, the study demonstrates that when the atria are inducible the substrates are an increased dispersion of refractoriness and a prolongation of conduction time.

Animals↗
PubMed1991

Presence of influenza virus-reactive glycophorins other than glycophorin A in human erythrocyte membranes.

The reactivities against seven hemagglutinins including influenza A and B viruses of six sialoglycoprotein (glycophorin) fractions, M-Frs.1-3 and N-Frs.1-3, separated from human OMs and ONs erythrocyte membranes by a combination of the LIS-phenol method and gel filtration were studied. The serological results show that M-Fr.1 and N-Fr.1 were glycophorins AM and AN, respectively, the reactivities against influenza A and B viruses of both M-Fr.2 and N-Fr.2 which contained glycophorins B and C were remarkably higher than that of glycophorin A and the reactivities against influenza viruses of both M-Fr.3 and N-Fr.3 which contained glycophorins B and D were considerably lower than that of glycophorin A.

Amino Acids↗
PubMed1991

Transgenic mice expressing a B cell growth and differentiation factor gene (interleukin 5) develop eosinophilia and autoantibody production.

Interleukin 5 (IL-5) has been suggested to be involved in the growth and differentiation of B cells and eosinophils. Especially, Ly-1+ B cells, which have been considered to produce autoantibodies, are selectively developed by this lymphokine in long-term bone marrow culture. To envisage the possible engagement of IL-5 in the development of these cells in vivo, transgenic mice carrying the mouse IL-5 gene ligated with a metallothionein promoter were generated. Transgenic mice carrying the IL-5 gene exhibited elevated levels of IL-5 in the serum and an increase in the levels of serum IgM and IgA. A massive eosinophilia in peripheral blood, bone marrow, and spleen, and an infiltration of muscle and liver with eosinophils, were observed. When cadmium-containing saline was injected intraperitoneally into transgenic mice, IL-5 production was augmented about five times within 24 h, and a distinctive Ly-1+ B cell population became apparent in the spleen after 5 d. IL-5 receptors were detected on those cells by monoclonal antibodies against IL-5 receptors. Another interesting finding in these transgenic mice was an increase in polyreactive anti-DNA antibodies of IgM class. It is suggested, therefore, that aberrant expression of the IL-5 gene may induce accumulation of Ly-1+ B cells and eosinophils. Furthermore, this IL-5 transgenic mouse can be a model mouse for eosinophilia, and we can determine the role of IL-5 in the differentiation of Ly-1+ B cells and eosinophils by using this mouse.

Animals↗
PubMed1991

Prenatal and postnatal development of the large intestine in the insectivore Suncus murinus, the laboratory shrew.

Development of the large intestine in the insectivore Suncus murinus (the laboratory shrew) was investigated from day 21 to 30 of gestation and from birth to 20 days of age. Two days before birth, the stratified epithelium in the large intestine changed into a single layer. Although neither villi nor villus-like structures were ever present, fissures, corresponding to openings of the crypts, appeared on the mucosal surface before birth. These increased in number as well as in width and depth, connected with each other, and gave the mucosal surface a ridge-like appearance by 20 days of age. An elevation containing submucosae appeared shortly after birth and formed a large circular fold during the neonatal period. Goblet cells were the predominant epithelial cell type. Individual epithelial cells were mature-looking a few days before birth; goblet cells contained numerous mucous globules and absorptive cells possessed well-developed organelles. However, although goblet cells increased in number and exhibited active mucous-releasing forms after birth, absorptive cells never showed morphologic evidence of active endocytosis, such as apical endocytotic complexes and large supranuclear vacuoles. Each epithelial cell was similar in ultrastructure to that of the adult shortly after birth.

Age Factors↗
PubMed1991

Increase in serum and bile cholesterol and HMG-CoA reductase by lovastatin in rats.

Lovastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, is effective in the treatment of hypercholesterolemic patients and is currently being evaluated as a potential agent for dissolving gallstones. We therefore evaluated its effect on cholesterol metabolism in a rat model. A low-cholesterol diet containing 0.1% lovastatin was fed 15 h and 7 and 21 days. Microsomal HMG-CoA reductase activity, hepatic cholesterol synthesis, blood cholesterol, and biliary lipid output were determined and compared with control rats. Hepatic cholesterol synthesis increased ninefold after 7 days and levels of HMG-CoA reductase activity sevenfold. Biliary cholesterol excretion maximally increased fourfold. Biliary lipid output was still elevated after 21 days of treatment (cholesterol 3-fold and phospholipid 2-fold, P less than 0.01). Bile salt output did not change. Augmented responses to lovastatin were present but less on the high-cholesterol diet. The data are consistent with the hypothesis that lovastatin increases HMG-CoA reductase activity through a feedback mechanism that promoted increased cholesterol synthesis, biliary lipid secretion, and elevated blood cholesterol. There was an apparent coupling of biliary cholesterol output with phospholipids but not with bile salts. Although lovastatin also increased microsomal HMG-CoA reductase activity in humans, cholesterol synthesis is not stimulated but is inhibited. This may be explained by higher permeability of the microsomal membranes for lovastatin. Thus the effect of HMG-CoA reductase inhibitors on cholesterol synthesis in different species should then depend on the properties of microsomal membranes.

Animals↗
PubMed1991

[Immunohistochemical studies on a new antigens associated with squamous cell cancer in oncogenesis of uterine cervical cancer].

We examined the localization of squamous cell cancer associated antigens (SCCAA) in dysplasia, cancer in situ (CIS) and microinvasive SCC of the uterine cervix, since detection of SCCAA in these subjects is highly effective for early diagnosis. Anti-squamous cell cancer associated antibody (Anti SCCAAb IgG) was prepared by immunizing rabbits with specific components at around PI 6.1 that were originally purified from SCC of maxillary sinus. In this study, the following results were obtained by the immunoperoxidase method. (1) Eleven out of 15(73%) cases of dysplasia, 20 out of 26(77%) cases of CIS, 21 out of 24(88%) cases of Stage I, 13 out of 14(93%) cases of Stage II and 9 out of 10(90%) cases of Stage III-IV in the clinical stages of SCC showed positive staining, while controls of unrelated SCC were almost negative. (2) The SCCAA positive ratio was 2 out of 2 cases of small cell nonkeratinized type, 86% in large cell nonkeratinized type and 94% in Keratinized type of SCC. (3) The SCCAA was demonstrated on all the layers of stratified squamous epithelium in a lesion of CIS and some layers migrated to adjacent nonneoplastic lesion with lateral invasion in middle layer. These results suggest that the demonstration of SCCAA may be useful in diagnosing the malignant transformation of squamous epithelium in the early stage of SCC.

Antigens, Neoplasm↗
PubMed1990

Phenols as internal standards in reversed-phase high-performance liquid chromatography in pharmaceutical analysis.

To find a series of compounds for use as internal standards in reversed-phase high-performance liquid chromatography, about 70 commercially available phenols were chromatographed under various conditions. The stationary phases used were hydrocarbon chemically bonded silica gels (phenyl, C8 and C18 columns). The mobile phases consisted of 10-60% aqueous-organic solutions (organic solvents, methanol, acetonitrile, tetrahydrofuran and mixtures thereof; aqueous phases, water, buffer solutions of pH 2 and 7, 20 mM sodium sulphate or water containing 5 mM of counter ion). A series of 30 phenol derivatives showed a constant order of elution regardless of the separation conditions and are useful as potential internal standards.

Chromatography, High Pressure Liquid↗