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S Y Ho

Publications and source records attributed to S Y Ho.

At least 145 records · Page 8Linked to original sources
PubMed1996

Fatty acid uptake by Caco-2 human intestinal cells.

The Caco-2 human enterocytic cell line was used to study the kinetics and mechanism of intestinal long chain fatty acid uptake. Initial rates of palmitate (16:0), oleate (18:1), and octanoate (8:0) uptake were determined for adherent cells at greater than 7 days confluence. Uptake of long chain 18:1 and 16:0 by cells grown on coverslips was saturable with an apparent Km of 0.3 microM, but also included a notable diffusive component. Uptake of short chain 8:0, on the other hand, was linear up to 10 microM. Cells grown on permeable Transwell filters were used to study uptake at the apical versus the basolateral membrane. Uptake of long chain (18:1 and 16:0), but not short chain (8:0), fatty acid was saturable at both surfaces with a similar Km of 0.3 microM. In addition, long chain but not short chain fatty acid uptake was competitively inhibitable. Western blot analysis demonstrated that Caco-2 cells express a protein immunoreactive with antibodies to the rat liver plasma membrane fatty acid binding protein (FABPpm), which is thought to be involved in long chain fatty acid transport. Nevertheless, long chain fatty acid uptake was not inhibited by pretreatment of the cells with an FABPpm antibody, nor by pretreatment with two proteases. These data support a saturable component in the transport of long chain but not short chain fatty acids by human intestinal epithelial cells, which may involve an as yet unknown plasma membrane protein.

Animals↗
PubMed1996

[Ischemic preconditioning and exogenous L-arginine reduce infarct size in rabbit heart].

The effects of NO donor--L-arginine (L-arg) and ischemic preconditioning (IP) on the hemodynamics and myocardial infarct size were examined in the anesthetized rabbit subjected to myocardial ischemia-repefusion to define whether exogenous L-arg could exert a beneficial effect in this pathological model, and whether the L-arg-NO pathway was involved in the cardioprotection provided by IP. The results obtained were as follows: (1) During the course of ischemia (30 min)-reperfusion (180 min), blood pressure, heart rate and myocardial oxygen consumption decreased progressively, and the myocardial infarct size occupied 33.9 +/- 2.4% of the whole left ventricle. (2) The myocardial infarct size could be reduced to 20.1 +/- 2.2% (P < 0.01) by pretreatment with L-arg (300 mg/kg). This myocardial protective effect of L-arg was abolished by NO synthesis inhibitor--Nitro-L-arginine (L-NNA), thereby indicating the involvement of L-arg-NO pathway. (3) IP significantly reduced the infarct size to 21.9 +/- 2.1% (P < 0.01), indicating the prominent cardioprotective effect of such an intervention. Since L-NNA showed no effect on the cardioprotection afforded by IP, it was implied that the L-arg-NO pathway was not involved in the cardioprotective mechanism of IP. (4) Exogenous L-arg might markedly augment cardioprotection provided by IP. The above results strongly suggested that the cardioprotective effect of L-arg on ischemia-reperfused myocardium was mediated by L-arg-NO pathway, which, however, was not involved in the cardioprotection provided by IP.

Animals↗
PubMed1996

[Effects of L-NNA and NO donors on spontaneous activity of rostral ventrolateral medulla neurons].

The effects of intravenous injection of a NO synthase inhibitor--N-nitro-L-arginine (L-NNA) and NO donors--sodium nitroprusside (SNP) and SIN-1 on blood pressure (BP), heart rate (HR) and spontaneous activity of rostral ventrolateral medulla (RVLM) neurons were examined in 22 anesthetized rats to define the action site of L-arginine: NO pathway in BP regulation. The results obtained were as follows. (1) Following i.v. injection of L-NNA, mean artery pressure (MAP), HR and spontaneous discharge rate of 14 RVLM neurons were all increased, all effects starting at 5 min after administration of L-NNA and lasting for more than 30 min. (2) In response to i.v. injection of SNP, MAP was decreased with concomitant increase in HR and the discharge rate of 23 RVLM neurons decreased in a dose-dependent manner. These effects were rapid in onset and also disappeared promptly. To exclude the effect of cerebral ischemia induced by decreased of BP, the effects of intracarotid injection of SNP were examined. Following i.a. injection, MAP was only slightly decreased and HR showed no significant change, but the discharge rate of 14 RVLM neurons was significantly decreased. (3) During i.v. injection of another NO donor--SIN-I, MAP and the spontaneous discharge rate of 11 RVLM neurons were decreased. The above results indicate that the L-arginine: NO pathway may exert a modulatory action on the blood pressure through rostral ventrolateral medulla.

Animals↗
PubMed1996

[Effects of microinjection of L-NNA and SNP into ventrolateral medulla on blood pressure, heart rate and renal sympathetic nerve activity in rats].

The effects of microinjection of a NO synthase inhibitor--N-nitro-L-arginine (L-NNA) and NO donor-sodium nitroprusside (SNP) into ventrolateral medulla on blood pressure (BP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were examined in anesthetized rats to define the role of L-arginine: NO pathway in the central regulation of BP and to explore the underlying mechanism. The results obtained were as follows: (1) Following microinjection of L-NNA into rostral ventrolateral medulla (RVLM), both of MAP and RSNA were increased. The effects lasted for more than 30 min and could be reversed by prior intravenous injection of L-arginine. (2) In response to microinjection of SNP into RVLM, MAP and RSNA were decreased, while HR showed no significant change. (3) During microinjection of L-NNA into caudal ventrolateral medulla (CVLM), MAP, HR and RSNA were decreased. (4) Upon injection of SNP into CVLM, MAP and RSNA were increased, but HR showed no significant change. The above-mentioned results indicate that the L-arginine: NO pathway may exhibit a modulatory action on the activity of ventrolateral medulla neurons.

Animals↗
PubMed1995

Pathologic elucidation of the echocardiographic features of Ebstein's malformation of the morphologically tricuspid valve in discordant atrioventricular connections.

We defined the morphology of the left atrioventricular valve in Ebstein's malformation associated with congenitally corrected transposition to elucidate the approach to diagnosis by echocardiography. We found 14 unequivocal cases out of a total of 3,720 specimens. We noted the atrial arrangement, displacement, and nature of the tricuspid leaflets, and axis of the plane of the tricuspid orifice. We constructed ratios of volume of the atrialized to the functional right ventricle, and of the right to left ventricle, as well as distances of the septal attachments of the atrioventricular junctions to the respective ventricular apices. Three specimens had abnormalities of cardiac position, and 8 had ventricular septal defect. The tricuspid valve plane was rotated 47 +/- 21 degrees from its usual position into the ventricle. The tricuspid valvar tissue was variably attached to the underlying myocardium, with the most severely affected lesion being the mural leaflet followed by the septal leaflet, and the anterior leaflet attachment the least affected. Abnormalities of the tendinous cords and the effective valvar orifice occurred in 3 specimens. The ratio of the atrialized to the functional right ventricular volume was 0.74 +/- 0.49; the ratio of the fetal right to left ventricular volume was 1.18:1 +/- 0.70:1. These data suggest that plastic repairs of the right ventricle would leave a small functional right ventricle, but that valve replacement could restore the volume of the ventricle. Thus, the plane of displacement of the valve in corrected transposition appears less amenable to 4-chamber echocardiography than other forms of Ebstein's malformation. Changes in the echocardiographic planes should display the morphology and also provide some hemodynamic information.

Adult↗
PubMed1995

Rhabdomyosarcoma of the vagina in a postmenopausal woman: report of a case and review of the literature.

Most rhabdomyosarcomas (RMSs) of the female genital tract occur in infants and young children as sarcoma botryoides. Vaginal RMS occurring in a postmenopausal woman is extremely rare. To our knowledge, only three vaginal RMSs have been reported in patients who were over 50 years of age. Herein, the first case in Taiwan and the fourth case in the world is reported, and the pertinent literature is briefly reviewed. A 63-year-old woman complained of a few days of abnormal vaginal bleeding. Vaginal examination demonstrated two black polypoid tumors located at the left-lateral and posterior wall of the vagina. The patient had previously undergone a vaginal total hysterectomy for rectocele and urine incontinence, so surgical treatment including local wide excision and bilateral salpingo-oophorectomy were performed under the diagnosis of malignant vaginal tumor. The clinical, histopathological, and immunohistochemical studies revealed a group Ia pleomorphic RMS. Postoperative radiotherapy was performed. The patient remains alive and well 12 months after a combined therapy.

Combined Modality Therapy↗
PubMed1995

Internalization of microbubbles by tumor cells in vivo and in vitro.

Lipid-coated microbubbles (LCM) administered intravenously (i.v.) to rats bearing brain tumor, specifically enhance tumor visualization by ultrasound [1]. In order to understand the basis for this observation, we have examined the interactions of LCM with glioblastoma (C6) and gliosarcoma (9L) tumor cells in vivo and in vitro. LCM and LCM labeled with the fluorescent lipophilic dye 3,3'-dioctadecyloxacarbocyanine perchlorate (diO) were administered to rats bearing brain tumor. LCM and diO-labeled LCM were found principally at the tumor site with no evidence of label in the surrounding normal brain tissue. Analysis of the tumor by confocal laser scanning microscopy revealed that labeled LCM were inside the tumor cells. Similar analysis of LCM interactions with C6 and 9L cells in culture showed that LCM first adsorb at the surface of the cells, and with time became localized inside the cells. Binding and internalization proceeded faster at 37 degrees C than at room temperature (RT). Staining of live cells with N-(3-((2,4-dinitrophenyl)amino)propyl)-N-(3-aminopropyl) methylamine dihydrochloride (DAMP), a dye that recognizes acidic compartments, showed that the majority of internalized LCM was associated with compartments containing DAMP. If the same uptake mechanism were operative in vivo, it would indicate that a portion of LCM bypasses the reticuloendothelial system and become endocytosed directly by tumor cells.

Animals↗
PubMed1995

Anatomic spectrum of abnormal ventriculoarterial connections: surgical implications.

To clarify the salient anatomic features of surgical significance, we investigated 33 specimens representing the spectrum of abnormal ventriculoarterial connections. In those with tetralogy of Fallot or double-outlet right ventricle with subaortic ventricular septal defect, the muscular outlet septum separating the subarterial outflow tracts was always inserted into (or in front of) the anterior limb of the septomarginal trabeculation (septal band). In those having double-outlet right ventricle with doubly committed ventricular septal defect, the outlet septum was lacking. When the ventricular septal defect was in subpulmonary position, with either double-outlet or discordant ventriculoarterial connections, the outlet septum was attached to the posterior limb of the septomarginal trabeculation. The outlet septum was deviated into the subpulmonary outlet in hearts with discordant ventriculoarterial connections and pulmonary stenosis. It is the interrelations between the septomarginal trabeculation, the outlet septum, and the ventriculoinfundibular fold that hold the key to the understanding of surgical anatomy and determine the optimal choice of procedure for definitive biventricular repair.

Cardiac Surgical Procedures↗
PubMed1995

A bicuspid pulmonary valve is not a contraindication for the arterial switch operation.

There are no obvious criteria concerning the optimal repair for complete transposition with bicuspid pulmonary valve if neither the organic changes in the valve nor the pressure gradient between the left ventricle and the pulmonary trunk are severe. Instead of intraatrial switching or intraventricular rerouting in such circumstances, we have proceeded to the arterial switch procedure in 6 patients with an adequate diameter of the pulmonary valve (greater than 100% of the calculated normal aortic orifice). Postoperative catheterization (at approximately 8 months after the procedures) showed no pressure gradient between the left ventricle and the neoaorta except for a finding of 34 mm Hg difference in 1 patient who had undergone simultaneous subpulmonary myotomy. Echocardiography (7 years later in the longest follow-up) has shown no more than slight regurgitation across the bicuspid neoaortic valve, with no progressive increase of blood velocity across the valve. From these results in the middle term, we conclude that the arterial switch procedure remains an option of choice for patients with initially bicuspid pulmonary valve, providing there is no severe subpulmonary stenosis.

Aorta↗
PubMed1995

The forgotten interleaflet triangles: a review of the surgical anatomy of the aortic valve.

Surgical descriptions of the aortic root are not always in keeping with anatomy as observed in the autopsied heart. Although all surgeons appreciate that the concept of the aortic annulus does not imply the presence of a straight ring as a hinge point, the nature of the supporting fibrous structures relative to the semilunar attachment of the leaflets has yet to be clarified. We have analyzed 50 normal aortic roots, two fetal aortic roots sectioned histologically in horizontal and sagittal planes, respectively, and two autopsied adult hearts in which prosthetic aortic valves had been inserted during life. Our results demonstrate the important interrelationships between aortic sinuses, valvar leaflets, and supporting left ventricular structures that produce the three fibrous interleaflet triangles. It is the structure and location of these triangles that is the key to the understanding of the surgical anatomy. Our results also show that the presently used definition of commissure does not reflect adequately the extent of the zones of apposition between adjacent valvar leaflets, essential for normal function when the valve is closed.

Adult↗
PubMed1995

Coronary arterial anatomy in double-outlet right ventricle with subpulmonary VSD.

We have examined 38 hearts with a double-outlet right ventricle with a subpulmonary ventricular septal defect. We divided the hearts into three groups according to the angle between the planes formed between the outlet septum and the remainder of the muscular ventricular septum; namely, at approximately right angles (15 hearts), parallel (11 hearts), and at an acute angle (12 hearts). The coronary arterial pattern corresponding to that seen in the normal heart was present in 11 hearts (73%) of the "right angle" group, in only one heart (8%) of the "acute angle" group, and in none of the "parallel" group. In contrast, the most common pattern in the setting of complete transposition was observed in none, 8%, and 91% of each group, respectively. Other diverse patterns were recognized in the hearts in the acute angle group, and the incidence of abnormal branching was significantly higher in this than in the other groups (p < 0.01). Knowledge of these anatomic variations in the course of the coronary arteries, some of which would cause problems at either definitive repair or reoperation, are essential for those seeking to achieve optimal surgical repair.

Coronary Vessel Anomalies↗
PubMed1995

Atrial appendages and venoatrial connections in hearts from patients with visceral heterotaxy.

BACKGROUND: Venoatrial connections are important when choosing surgical options for patients with visceral heterotaxy. The precise morphology of the atriums, however, is often obfuscated by the term "visceral heterotaxy." This morphologic study aims to clarify the features of significance to the cardiac surgeon. METHODS: We investigated 183 hearts from patients known from postmortem inspection to have so-called visceral heterotaxy. The connections of the systemic and pulmonary veins to the atriums, and the detailed morphology of the atriums, were examined in each case. RESULTS: Pectinate muscles extended bilaterally to the crux in 125 hearts determined to have isomeric morphologically right appendages. The other 58 hearts all exhibited bilaterally smooth-walled vestibules, and were diagnosed as having isomeric left appendages. Bilateral superior caval veins were frequent in both groups. The inferior caval vein was right- or left-sided with equal frequency in both groups, but was interrupted only in hearts with isomeric left appendages. The pulmonary veins connected in extraatrial fashion in 48% of cases with isomeric right appendages, whereas, most commonly, pulmonary veins were connected bilaterally to the atriums in those with isomeric left appendages (60%). CONCLUSIONS: Both the morphology of the atrial appendages and the venoatrial connections need to be distinguished to establish precise diagnoses in patients with so-called visceral heterotaxy ("splenic syndromes").

Abnormalities, Multiple↗
PubMed1995

Three-dimensional echocardiography can simulate intraoperative visualization of congenitally malformed hearts.

BACKGROUND: The new technique of three-dimensional echocardiography can display the studied anatomy in any desired view plane. We sought to establish whether the reconstructions produced could provide views of the heart comparable with those obtained by the surgeon in the operating room. METHODS: Ninety-four patients, aged 1 day to 19 years (mean, 4.3 years), were examined. The ultrasound probe was placed either on the chest or subcostally and acquired 80 to 100 perpendicular parallel images of the heart with electrocardiographic and respiratory gating. Any plane, in particular oblique planes, within the data set can be analyzed. Whenever possible, the arrangement as seen by the surgeon was photographed, or heart specimens with similar intracardiac lesions were cut to simulate the view of the surgeons, to validate the echo-cardiographic reconstructions. RESULTS: Three-dimensional reconstruction of perimembranous ventricular septal defects, atrial septal defects, or anomalies of the atrioventricular valves could be displayed as viewed through an atriotomy. In similar fashion, reconstructions of muscular or doubly committed ventricular septal defects, along with obstruction of the right ventricular outflow tract, could be prepared as seen through a right ventriculotomy. Obstruction of the left ventricular outflow tract was shown as viewed through an aortotomy. Transthoracic three-dimensional echocardiography provided additional information in the prospective diagnosis of supravalvar mitral membrane, doubly committed subarterial ventricular septal defect, and subaortic stenosis caused by a restrictive ventricular septal defect in double inlet left ventricle. CONCLUSIONS: Three-dimensional echocardiography can simulate the display of the heart as seen by the surgeon in the operating room, and therefore can aid in better planning of surgical repair.

Adolescent↗
PubMed1995

Fibrous obstruction within the left ventricular outflow tract associated with ventricular septal defect: a pathologic study.

OBJECTIVES: We examined the nature of ridges within the left ventricular outflow tract associated with ventricular septal defects that might be found by echocardiography. BACKGROUND: Echocardiography displays even small ridges well. Surgical removal of such ridges at the time of defect closure is recommended. METHODS: We examined 37 heart specimens with ventricular septal defects with a ridge, noting its nature and relation to the defect and adjacent valves. We excluded left ventricular outflow tract obstruction associated with complex lesions. RESULTS: Defects were perimembranous in 25 specimens, muscular in 8 and part of an atrioventricular septal defect in 5. Some hearts had multiple defects. Many of the original reports had not mentioned ridges. Three distinct ridge patterns were found. The first (n = 18) was a fold of endocardial tissue related to the membranous septum. The second (n = 12) was a defect of a fibrous nature; in 8 this was a discrete, protuberant fibrous ridge, and in 4 the obstruction was diffuse, which we termed keloidal. The third pattern (n = 7) lay circumferentially around the ventricular septal defect, seemingly associated with the defect's attempted spontaneous diminution in size. Endocardial folds were not found in specimens from patients > 5 years old. Fibrous and keloidal lesions, which may represent a continuum of progression, generally were found in specimens from older patients. Histologic studies of 17 specimens confirmed the morphologic findings. The endocardial folds were endothelial tissue, whereas the fibrous and keloidal ridges were of fibrous tissue, as were circumferential lesions. All specimens had mitral-semilunar valvular continuity. CONCLUSIONS: Endocardial fold and circumferential lesions appear to be benign. The endocardial folds arose from the membranous ventricular septum, were not protuberant and usually were found in younger patients. The fibrous ridges, in contrast, were protuberant and were always associated with the underlying muscle of the outlet septum. These pathologic distinctions may facilitate echocardiographic diagnosis and prognosis.

Adolescent↗
PubMed1995

The relationship of the outlet septum to the aortic outflow tract in hearts with interruption of the aortic arch.

We examined 13 hearts with concordant atrioventricular and ventriculoarterial connections and interruption of the aortic arch to establish and describe the morphologic features of the outflow tracts in relation to axial deviation and malalignment of the outlet septum as opposed to overriding of the arterial valvular orifices. Interruption in all cases but one was between the left common carotid and left subclavian arteries; the other arch was interrupted at the isthmus. A patent arterial duct and ventricular septal defect were universally present. When its borders were viewed from the right ventricle, the ventricular septal defect was perimembranous in seven hearts, had exclusively muscular borders in four hearts, and was doubly committed and juxta-arterial in the remaining two hearts. Malalignment between the muscular ventricular septum and outlet septum, or a fibrous raphe, as judged when the heart was viewed in its short axis, was found in 12 of the hearts. Posterior and leftward axial deviation of the outlet septum in its long axis was found in 4 of the 12 hearts and also in one heart that did not have short-axis malalignment. Attachments of the leaflets of the pulmonary valve in both right and left ventricles, however, were present in only one of the specimens, this being a case with a doubly committed and juxta-arterial defect. These separate features of the outflow tract in hearts with interruption of the aortic arch, therefore, require thorough assessment when surgical management is planned. All these variable features can be assessed preoperatively by cross-sectional echocardiography, which should be directed toward defining the degree of development and alignment of the outlet septum, as well as the length of the subpulmonary infundibulum.

Aorta, Thoracic↗
PubMed1995

The surgical anatomy of coronary venous return in hearts with isomeric atrial appendages.

Although absence of the coronary sinus is widely recognized in hearts with isomerism of the right atrial appendages, little attention has been paid to the fashion of the venous return from the heart itself. In this study, the arrangement of coronary venous return was investigated in 99 specimens with isomeric right and 49 with isomeric left appendages. In the normal heart, the coronary veins consist of a circumflex component within the atrioventricular groove and longitudinal components on the ventricular mass. The circumflex venous system was seen in 44 hearts with isomerism of left appendages (90%), but 23 of these hearts lacked the anatomic features of the coronary sinus. Circumflex veins were entirely lacking in the other 10% of hearts with isomeric left appendages and in all those with isomeric right appendages. In these hearts, longitudinal veins drained independently into the atria in three patterns. The first was a direct connection, with the venous orifice opening between the trabeculations of the atrial wall immediately having crossed the atrioventricular groove. The second was a crooked return, with the vein running an intramural course along the atrioventricular groove. The third was a distant connection, reaching superiorly to the smooth-walled atrial component after running an intramural course. Intramural courses were seen in 19% of the longitudinal veins, such veins being found in 62% of all hearts with no circumflex venous system. These findings, which to the best of our knowledge have never previously been recognized in detail, almost certainly have potential surgical significance.

Coronary Vessel Anomalies↗