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Biomedical subjects

T Sakai

Publications and source records attributed to T Sakai.

At least 343 records · Page 19Linked to original sources
PubMed1999

Structural identification and characterization of arteries and veins in the placental stem villi.

The vascular wall structure in the human full-term placental villi of normal pregnancy was studied by means of light and electron microscopy with an improved technique of perfusion fixation and tissue preparation. We observed 81 sections of stem villi that showed cross-sectional profiles of paired vessels in their center. Both vascular walls contained a large amount of extracellular matrix and no elastic lamina between smooth muscle cells of the media, making identification of the artery and the vein quite difficult at first sight. We then noted that the density of the smooth muscle cell population was always considerably higher in one than the other, and identified the former as artery and the latter as vein on the basis of their connection with larger arteries and veins running on the chorionic plate. Between the paired vessels, the artery had a smaller caliber than the vein, and the ratio of venous to arterial caliber was distributed from 1.0 to 2.5. The thickness of media was usually thicker in the vein than in the artery. Clusters of elastic fibers were found occasionally in the media of arteries and veins, and basement membrane-like materials were associated frequently with the elastic fibers and were distributed widely in the media as well as in the adventitia. In the veins, the smooth muscle cells of the most superficial part of the media contained well-developed rough endoplasmic reticulum and Golgi apparatus, indicating differentiation to secrete extracellular matrices. The present study revealed the difference of wall structure between arteries and veins in the placental stem villi for the first time at the ultrastructural level, and suggested differentiation of venous smooth muscle cells, possibly by some influence from the luminal side.

Adult↗
PubMed1999

Transgastrostomal endoscopic surgery for early gastric carcinoma and submucosal tumor.

BACKGROUND: Laparoscopic intraluminal surgery of the stomach is now widely used for a lesion on the posterior wall. However, this procedure has some technical limitation related to the intricate introduction of the surgical instruments into the gastric lumen. In this article, we report our newly developed technique of transgastrostomal endoscopic surgery that overcomes this limitation and is also suitable for full-thickness gastric wall resection of a lesion in the wall. METHODS: After making a 4-cm-long temporary gastrostomy, a Buess-type endoscope is inserted into the gastric lumen through the gastrostomy. The operation is performed inside the gastric lumen under video camera guidance using electrocautery, scissors, and forceps. After resection, the wound in the mucosa or the wound after full-thickness resection is endoluminally sutured. Mucosal resection was performed in six cases of early gastric carcinoma, two cases of atypical epithelium, and one case of ectopic pancreas. Full-thickness wall resection was performed in four cases of a leiomyoma. RESULTS: In all 13 cases, the lesion could be precisely located by the video camera. All lesions were then resected endoluminally. The mean duration of the operation was 148 min. The postoperative course in all cases was uneventful. CONCLUSIONS: Transgastrostomal endoscopic surgery is minimally invasive and an efficient tissue-preserving technique for the removal of early gastric carcinoma or submucosal tumor.

Adult↗
PubMed1999

Upright posture blunts postprandial splanchnic hyperemia in patients with cirrhosis and portal hypertension.

The aim of this study was to compare postprandial hemodynamic changes observed during assumption of the recumbent posture and upright posture in patients with cirrhosis and portal hypertension. Eleven patients with cirrhosis and portal hypertension were studied. Echo-Doppler examinations were performed to measure flow volume in the portal vein (PV), superior mesenteric artery (SMA), and splenic artery (SA) in the fasting condition. Collateral blood flow was indirectly calculated by determining the difference between the sum of SMA, SA, and PV blood flows. After these measurements were done, each patient received a standardized liquid meal and was then randomly assigned to either maintain supine or upright posture, in a crossover design, on 2 different days (recumbent day and upright day). On each study day, the above-mentioned measurements were repeated 30 min and 60 min after the meal. PV blood flow increased significantly after the meal on the recumbent day (P < 0.01) but not on the upright day (P = 0.78). Although there were significant postprandial increases in SMA blood flow on both study days (P < 0.01, P < 0.01), the effect was less pronounced on the upright day than on the recumbent day (P < 0.01). Postprandial SA blood flow showed no change on the recumbent day (P = 0.64), but decreased significantly on the upright day (P < 0.01). The calculated postprandial collateral blood flow increased significantly on the recumbent day (P < 0.05), but showed no change on the upright day (P = 0.53). These results suggest that the upright posture blunts postprandial splanchnic hyperemia in patients with cirrhosis and portal hypertension.

Aged↗
PubMed1999

Gastric enterochromaffin-like-cell tumor with liver and splenic metastases.

We report a patient with gastric enterochromaffin-like-cell tumor with liver and splenic metastases. He was 68 years old and presented with major complaints of epigastric pain and weight loss. Under the diagnosis of gastric carcinoma with liver metastasis, total gastrectomy with splenectomy and lateral segmentectomy of the liver was performed. Intraoperative findings resulted in a diagnosis of adenocarcinoma T3N2P0H1, in stage IVa. Histological examination of the resected specimens showed a well differentiated neuroendocrine carcinoma (enterochromaffin-like-cell tumor) with liver and splenic metastasis which demonstrated high-grade lymphatic and vascular invasion. There was no lymph node metastasis. The tumor cells in the stomach, liver and spleen were immunoreactive for chromogranin A and Grimelius--positive. We review the literature, as well as presenting this case report.

Aged↗
PubMed1999

Dissection of the middle cerebral artery caused by invasion of malignant glioma presenting as acute onset of hemiplegia.

A 57-year-old, previously healthy man who developed acute onset of hemiplegia is presented. Neuro-imaging studies on admission suggested dissection of the middle cerebral artery producing infarction in the frontotemporal region. In contrast to his stable clinical course, serial neuro-imaging studies disclosed rapid growth of malignant glioma, which was confirmed at surgery. Microscopic examination of the surgical specimen demonstrated invasion of glioma cells into the arterial wall associated with intramural haematoma formation of the middle cerebral artery. This case is the first to document dissection of an intracranial artery caused by invasion of tumour cells.

Acute Disease↗
PubMed1999

Increased cerebrospinal fluid levels of substance P in patients with amyotrophic lateral sclerosis. Short communication.

To clarify the mechanism of brain and spinal cord impairment in amyotrophic lateral sclerosis (ALS), we measured the cerebrospinal fluid (CSF) levels of substance P (SP) in 11 patients with sporadic ALS. Findings were compared with those obtained in controls and diseased controls. The CSF SP levels of patients with ALS, and particularly in patients with a disease duration of less than 2.5 years, were significantly higher than those in controls. These findings strongly suggested that SP may play an important role in the pathophysiology of ALS.

Adult↗
PubMed1999

Thoracic aortic aneurysm repair with an endovascular stent graft: the "first generation".

OBJECTIVE: The feasibility and efficacy trial of an endovascular stent-grafting system for the treatment of aneurysms of the descending thoracic aorta was investigated. METHODS: After Institutional Review Board approval, 103 patients (mean age 69 years) underwent stent graft repair of a descending thoracic aortic aneurysm between July 1992 and November 1997. The stent graft was fabricated using self-expanding "Z" stents covered by a woven Dacron tube graft. Follow-up, which averaged 22 months, was 100% complete. Simultaneous open abdominal aortic aneurysm repair was performed in 19 patients. RESULTS: Complete aneurysm thrombosis was achieved in 86 patients (83%). Early mortality, defined as a death during the same hospitalization or in less than 30 days, was 9 +/- 3%, and was significantly associated with preoperative cerebrovascular accident (CVA) or myocardial infarction. Major perioperative morbidity occurred in 31 patients, and included paraplegia in 3, CVA in 7, and respiratory insufficiency in 12 patients each. Actuarial survival was 81 +/- 4% at 1 year, and 73 +/- 5% at 2 years. Treatment failure (including all late, sudden, unexplained deaths) occurred in 38 patients, and only 53 +/- 10% of patients were free of treatment failure at 3.7 years. Five patients required late operative therapy for endoleaks associated with aneurysm enlargement. CONCLUSIONS: Satisfactory results were achieved using this "first-generation" homemade stent graft device. Mortality and morbidity occurred frequently, but may have been associated with the high-risk character of this patient population. Medium-term results were acceptable, but continued aortic enlargement, with the late development of endoleaks, is a significant concern. Second-generation devices with commercial development, coupled with this initial experience, should allow improved clinical results in the future. Longer term follow-up is still necessary to fully define the efficacy of this endovascular approach.

Adult↗
PubMed1999

Autologous heart cell transplantation improves cardiac function after myocardial injury.

BACKGROUND: Fetal ventricular cardiomyocyte transplantation into a cardiac scar improved ventricular function, but these cells were eventually eliminated by rejection. We therefore examined the feasibility of autologous adult heart cell transplantation. METHODS: A transmural scar was produced in the left ventricular free wall of adult rats by cryoinjury. The left atrial appendage was harvested, and the atrial heart cells were cultured and their number expanded ex vivo. Three weeks after cryoinjury, either a cell suspension (2 x 10(6) cells, n = 12 rats, transplant group) or culture medium (n = 10 rats, control group) was injected into the scar. Rats having a sham operation (n = 5) did not undergo cryoinjury or transplantation with cells or culture medium. RESULTS: Five weeks after injection, ventricular function was evaluated in a Langendorff preparation, measuring systolic, diastolic, and developed pressures over a range of intraventricular balloon volumes. Systolic and developed pressures were greater in the transplant group than in the control group (p = 0.0001). Rats with a sham operation had the greatest systolic, diastolic, and developed pressures (p = 0.0001). Histologic studies demonstrated survival of the transplanted heart cells within the scar. The area of the scar was smaller (p = 0.0003) and its thickness greater (p = 0.0003) in rats in the transplant group. Left ventricular chamber volume was smaller in the transplant group (p = 0.043). CONCLUSIONS: Transplantation of autologous cultured adult atrial heart cells limited scar thinning and dilatation and improved myocardial function compared with results in control hearts. This technique may lead to a novel therapy to prevent scar expansion after a myocardial infarction and prevent the development of congestive heart failure.

Animals↗
PubMed1999

Monokine stimulation of interleukin-11 production by human vascular smooth muscle cells in vitro.

Human vascular smooth muscle cells (VSMC) are a component of blood vessels, and secrete a variety of cytokines in atherosclerotic loci. Interleukin-11 (IL-11), a member of IL-6-like cytokines, is reported to be involved in inflammation and tissue remodeling, both of which are observed in atherosclerosis. However, no information is available as to the production of IL-11 by VSMC. Therefore, the expression of IL-11 in VSMC is investigated. The amounts of IL-11 protein and mRNA were determined by enzyme-linked immunosorbent assay (ELISA) and Northern blot analysis, respectively. The expression of IL-11 in VSMC was also immunohistochemically determined. IL-1 alpha, transforming growth factor-beta (TGF beta) and, to a lesser extent, tumor necrosis factor-alpha (TNF alpha) stimulated the IL-11 production by VSMC, and the stimulatory effects of IL-1 alpha and TGF beta on IL-11 production were dose-dependent. IL-1 alpha and TNF alpha synergistically augmented TGF beta-stimulated IL-11 production by VSMC. Immunohistochemical staining also revealed the expression of IL-11 protein in VSMC. Furthermore, IL-1 alpha, TGF beta, and TNF alpha induced IL-11 gene expression in VSMC. Because IL-6-like cytokines are reported to be cytoprotective, monokine-stimulated IL-11 may have a potent protective role in atherosclerotic lesions.

Arteriosclerosis↗
PubMed1999

Distance between mitral anulus and papillary muscles: anatomic study in normal human hearts.

BACKGROUND: Preservation of the annulo-papillary muscle continuity in mitral valve replacement is important. Even in patients who require excision of the mitral apparatus, the continuity can be restored. However, there is no guide to the proper length for the resuspension. METHODS: In 57 normal cadaveric hearts, the distance from the tip of the papillary muscle to its corresponding mitral anulus was directly measured. RESULTS: The distance from the tip of the anterolateral papillary muscle to the left trigone (10-o'clock position: D10) and to the point between the anterior and the middle scallops of the mural leaflet (8-o'clock position: D8) was 23.5 +/- 3.7 mm and 23.2 +/- 3.6 mm, respectively. The distance from the tip of the posteromedial papillary muscle to the right trigone (2-o'clock position: D2) and to the point between the middle and the posterior scallops of the mural leaflet (4-o'clock position: D4) was 23.5 +/- 4.0 mm and 23.5 +/- 3.9 mm, respectively. There was no statistically significant difference among the 4 distances (P =.96). Each distance was significantly longer than the corresponding chordae tendineae (D10 vs the anterior main chorda: 17.2 +/- 3.9 mm, D8 vs the anterior cleft chorda: 14.5 +/- 3.2 mm, D2 vs the posterior main chorda: 17.9 +/- 4.3 mm, and D4 vs the posterior cleft chorda: 14.9 +/- 3.2 mm, respectively; P =.0001). The mean distance had a significant correlation with the mitral annular diameter (r = 0.31, P =.019). CONCLUSIONS: In normal hearts, the annulo-papillary muscle distances of the mitral apparatus are similar in 2-, 4-, 8-, and 10-o'clock positions and correlate with the mitral annular diameter.

Adult↗
PubMed1999

Fetal cell transplantation: a comparison of three cell types.

OBJECTIVE: We have previously reported that fetal cardiomyocyte transplantation into myocardial scar improves heart function. The mechanism by which this occurs, however, has not been elucidated. To investigate possible mechanisms by which cell transplantation may improve heart function, we compared cardiac function after transplantation of 3 different fetal cell types: cardiomyocytes, smooth muscle cells (nonstriated muscle cells), and fibroblasts (noncontractile cells). METHODS: A left ventricular scar was created by cryoinjury in adult rats. Four weeks after injury, cultured fetal ventricular cardiomyocytes (n = 13), enteric smooth muscle cells (n = 10), skin fibroblasts (n = 10), or culture medium (control, n = 15 total) were injected into the myocardial scar. All rats received cyclosporine A (INN: ciclosporin). Four weeks after transplantation, left ventricular function was evaluated in a Langendorff preparation. RESULTS: The implanted cells were identified histologically. All transplanted cell types formed tissue within the myocardial scar. At an end-diastolic volume of 0.2 mL, developed pressures in cardiomyocytes group were significantly greater than smooth muscle cells and skin fibroblasts groups (cardiomyocytes, 134% +/- 22% of control; smooth muscle cells, 108% +/- 14% of control; skin fibroblasts, 106% +/- 17% of control; P =.0001), as were +dP/dt(max) (cardiomyocytes, 119% +/- 37% of control; smooth muscle cells, 98% +/- 18% of control; skin fibroblasts, 92% +/- 11% of control; P =. 0001) and -dP/dt(max) (cardiomyocytes, 126% +/- 29% of control; smooth muscle cells, 108% +/- 19% of control; skin fibroblasts, 99% +/- 16% control; P =.0001). CONCLUSIONS: Fetal cardiomyocytes transplanted into myocardial scar provided greater contractility and relaxation than fetal smooth muscle cells or fetal fibroblasts. The contractile and elastic properties of transplanted cells determine the degree of improvement in ventricular function achievable with cell transplantation.

Animals↗
PubMed1999

Mouse semaphorin H inhibits neurite outgrowth from sensory neurons.

Mouse semaphorin H (M-semaH) was structurally similar to semaphorin III/D, a mammalian homologue of collapsin 1 which was identified as a collapsing factor for sensory nerves. In this study we investigated the expression patterns of M-semaH mRNA and the protein binding sites in the trunk of mouse embryos. M-semaH mRNA was expressed in the mesenchymal tissues surrounding each dorsal root ganglia. These tissues include the caudal sclerotome and perinotochordal mesenchyme, which were thought to express factors repulsive to axons. M-semaH binding was detected on the spinal nerves. We further investigated, using in vitro co-culture assay, whether M-semaH acted as a chemorepulsive molecule on sensory axons. The results suggested that M-semaH was a candidate for a chemorepellent expressed in the mesenchyme surrounding the sensory ganglia, which is involved in the axonal guidance mechanism of sensory nerves in the trunk.

3T3 Cells↗
PubMed1999

Effect of transcatheter arterial chemoembolization on kidney hemodynamics and function in patients with cirrhosis and hepatocellular carcinoma.

BACKGROUND/AIMS: Transcatheter arterial chemoembolization (TACE) may have deleterious effect on the kidney in patients with cirrhosis and hepatocellular carcinoma. The aim of the study was to test this hypothesis. METHODS: Twenty-four patients with cirrhosis and hepatocellular carcinomas were included. They consisted of 16 patients undergoing a single TACE and eight patients undergoing diagnostic angiography. Doppler ultrasonography was used to measure hepatic artery pulsatility index (HA-PI) and renal artery pulsatility index (RA-PI) before and 1 day and 10 days after the procedure. Similarly, kidney function was assessed by measuring creatinine clearance. In addition, plasma renin activity, noradrenaline, and endothelin-1 were also measured. RESULTS: In patients receiving diagnostic angiography, no significant changes in HA-PI were observed after the procedure. In contrast, HA-PI increased significantly 1 day after the procedure (19%, p<0.01) in patients undergoing TACE, although it returned to baseline value 10 days after the procedure. In patients undergoing diagnostic angiography, no significant changes in RA-PI were observed after the procedure. Similarly, no detectable changes in RA-PI were noted in patients undergoing TACE. A transient small reduction in creatinine clearance was noted after the procedure in patients undergoing diagnostic angiography (-12%, p<0.05) and in those undergoing TACE (-11%, p<0.05). However, the effect was similar in the two groups (two-way ANOVA, p=0.72). No significant changes in plasma renin activity, noradrenaline, and endothelin-1 were observed after either diagnostic angiography or TACE. CONCLUSIONS: These results suggest that TACE per se has no deleterious effect on the kidney hemodynamics and function in patients with cirrhosis and hepatocellular carcinoma.

Aged↗
PubMed1999

Anticancer drugs inhibit induction of NO synthase in rat in vivo.

Nitric oxide (NO), synthesized by inducible NO synthase (iNOS) in immunoreactive cells, plays important roles in their activities such as bactericidal and tumoricidal functions. We examined the distribution of iNOS and evaluated the effects of anticancer drugs, 4'-epi-doxorubicin (EPI-DXR) and mitomycin C (MMC), on iNOS induction by lipopolysaccharide in rats. Ascites cells and bone marrow showed the highest induction of iNOS in the tested organs. Administration of EPI-DXR to rats strongly inhibited iNOS induction in lung, ascites, and bone marrow, but only slightly in liver and spleen. MMC administration inhibited the induction in the most immune reactive organs.

Animals↗
PubMed1999

Optical imaging of the spatiotemporal patterning of neural responses in the embryonic chick superior cervical ganglion.

Multiple-site optical recording of transmembrane potential changes with a voltage-sensitive dye was used to reveal the functional expression and developmental changes of the postsynaptic potentials in the early embryonic chick superior cervical ganglion. The ganglia were isolated from five- to 12-day-old chick embryos with preganglionic nerve fibres (vertebral and/or cervical carotic nerves) attached. The preparations were stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). Voltage-related optical (absorbance) changes were recorded simultaneously from 127 contiguous loci in the preparation, using a 12 x 12-element photodiode array. Optical changes having two components were evoked by preganglionic nerve stimulation. One component was the fast spike-like signal and another the delayed slow signal. The amplitude of the slow signal was decreased by repetitive stimulation, reduced by low external calcium ion concentrations and eliminated in the presence of manganese or cadmium ions. The slow signals were also eliminated in the presence of D-tubocurarine. Accordingly, we concluded that the slow signal corresponds to cholinergic excitatory postsynaptic potentials. In the five- and six-day-old superior cervical ganglia, only the fast optical signals (referred to as the action potentials) were recorded. Slow optical signals (referred to as the excitatory postsynaptic potentials) were detected from preparations older than seven days. The amplitude of the slow optical signal gradually increased, together with an expansion of the response area, as the developmental stage proceeded from seven to 10 days. To compare the distribution patterns of the neural responses evoked by stimuli applied to the cervical carotic and vertebral nerves, we have mapped and imaged the spatial patterning of the synaptic responses. In the maps, the positions of the peak size regions of the slow signals were assessed, and we found that there were differences in the location of these areas for the cervical carotic vs vertebral nerves. From these experimental results, we conclude that synaptic function within the chick superior cervical ganglion is initiated at the seven-day-old embryonic stage, and reaches a maximum level at 10 days. Synaptic transmission at these stages is mediated solely by nicotinic acetylcholine receptors. The spatial mapping of the synaptic responses reveals that the neural populations related synaptically to the cervical carotic and vertebral nerves are located separately within the ganglion, even at an early developmental stage.

Animals↗
PubMed1999

Developmental localization of semaphorin H messenger RNA acting as a collapsing factor on sensory axons in the mouse brain.

Semaphorins/collapsins, a family of genes with a semaphorin domain conserved from insects through to mammals, are believed to be involved in axon guidance during neuronal development. We report the expression patterns of mouse semaphorin messenger RNAs. Among secreted semaphorins, mouse semaphorin H is structurally most similar to semaphorin III/D, the first semaphorin identified as a collapsing factor for sensory axons. However, its expression patterns apparently differ from those of semaphorin III/D. The messenger RNAs are distributed in the brain widely but unevenly during development, in particular, in the main olfactory bulb, hippocampus and pontine nucleus. In the trunk, the expression level is high in mesodermal tissues surrounding the dorsal root ganglia, while it is low in the spinal cord. Moreover, we examined whether this molecule has activity to collapse growth cones of sensory neurons, as well as semaphorin III/D. Mouse semaphorin H collapsed growth cones of sensory neurons of the dorsal root ganglion in a dose-dependent manner, and anti-neuropilin antibodies inhibited this activity. Taken together, these results suggest that mouse semaphorin H can function as a chemorepellent to guide sensory peripheral nerves, most likely via neuropilin as a receptor.

Amino Acid Sequence↗