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Biomedical subjects

O Sato

Publications and source records attributed to O Sato.

At least 73 records · Page 4Linked to original sources
PubMed1997

Glucose metabolism and protective biochemical mechanisms in a rat brain affected by kaolin-induced hydrocephalus.

To clarify glucose metabolism in a hydrocephalic rat brain, substances related to glycolytic metabolism were biochemically measured. Kaolin-induced hydrocephalic rats were sacrificed and lactate dehydrogenase (LDH), LDH isozyme, lactate, adenosine triphosphate (ATP), and isocitrate dehydrogenase (ICDH) were measured in the following regions: cortex, thalamus, midbrain, hippocampus, cerebellum, and pons with medulla. During the development of hydrocephalus, lactate and LDH increased in most regions, the LDH M-subunit increased in the cortex, and ICDH decreased in most regions. However, ATP levels did not change. The increases in lactate, LDH and M-subunit suggested an anaerobic environment in the cell leading to activation of the anaerobic glycolysis. The decrease in ICDH represented a diminution of the tricarboxylic acid cycle. Through these alterations, the ATP level can be kept constant during the course of hydrocephalus, allowing the brain to create a better biochemical milieu.

Adenosine Triphosphate↗
PubMed1997

Adenovirus-mediated transfer of tissue-type plasminogen activator gene to human endothelial cells.

BACKGROUND: Seeding of vascular grafts with genetically engineered human endothelial cells (hECs) secreting antithrombogenic or fibrinolytic agents has considerable clinical potential. METHODS: An adenoviral vector was used to transfer the human tissue-type plasminogen activator (htPA) gene to hECs, and the ability of the transduced hECs to secrete htPA was examined. Cultured hECs on plates were incubated with various concentrations of recombinant adenoviruses containing the htPA or LacZ gene for various times to determine the optimal transfer conditions. Transduced hECs were seeded onto fibronectin-coated expanded polytetrafluoroethylene grafts (4 mm in diameter), some of which were exposed to pulsatile flow in vitro. RESULTS: Effective transduction of the htPA gene into hECs (htPAhECs) was achieved with viral soup at a multiplicity of infection of 30 after incubation for 1 day, which yielded 4.8 +/- 0.20 x 10(3) ng/10(6) cells/6 hr htPA antigen on plates (n = 3), 2.2 +/- 2.0 x 10(3) ng/10(6) cells/6 hr on grafts (n = 6), and 6.8 +/- 1.7 x 10(2) ng/10(6) cells/6 hr on perfused grafts (n = 6). The retention of htPAhECs by perfused grafts was 84.0% +/- 3.0%, comparable with the noninfected (82.1% +/- 8.0%) and mock-infected (94.2% +/- 0.4%) hEC values. CONCLUSIONS: By adenoviral vector-mediated gene transfer, 10(2-3)-fold enhancement of htPA secretion was demonstrated, which did not affect cell retention by grafts.

Adenoviridae↗
PubMed1997

Ruptured abdominal aorta secondary to psoas muscle abscess due to Klebsiella pneumoniae in an alcoholic.

An alcoholic patient with low back pain and Klebsiella pneumoniae septicaemia is reported. Computed tomography revealed abdominal aortic rupture associated with a psoas abscess. Aortic ligation above and below the rupture site and an axillo-femoral bypass were performed, but the patient died on the first postoperative day. Alcoholism is a common underlying disease in K. pneumoniae septicaemia and its septic metastasis to the psoas muscle. The prognosis of aortic infection secondary to psoas abscess is very poor once aortic rupture occurs. Prompt abscess drainage following correct diagnosis and arterial reconstruction before aortic rupture are mandatory.

Adult↗
PubMed1997

Intraoperative evaluation of small-calibre arterial reconstructions.

A new hammerhead-shaped, small probe for intraoperative duplex ultrasound was devised to evaluate small-calibre arterial reconstructions. This probe was used in two patients; one with terminal liver cirrhosis who had a left hepatic lobe that had been transplanted from her mother, and a second patient with limb-threatening ischaemia who had undergone arterial reconstructions. The technique was diagnostically useful and contributed to successful clinical outcomes.

Adolescent↗
PubMed1997

Murine P-glycoprotein on stromal vessels mediates multidrug resistance in intracerebral human glioma xenografts.

Human glioma usually shows intrinsic multidrug resistance because of the blood-brain barrier (BBB), in which membrane-associated P-glycoprotein (P-gp), encoded by the human multidrug resistance gene MDR1, plays a role. We studied drug sensitivity to vincristine (VCR), doxorubicin (DOX) and nimustine (ACNU) in both intracerebrally and subcutaneously xenotransplanted human glioma. We examined the levels of MDR1 and murine mdr3 gene expression in the xenografts by reverse transcriptase polymerase chain reaction and the localization of P-gp by immunohistochemistry. Six of seven subcutaneously transplanted xenografts (scX) were sensitive to the above three drugs. In contrast, all three intracerebrally transplanted human glioma xenografts (icX) were resistant to P-gp-mediated drugs VCR and DOX, but were sensitive to the non-P-gp-mediated drug ACNU. Neither icX nor scX showed any MDR1 expression. Intracerebrally transplanted human glioma xenografts showed an increased level of murine mdr3 gene expression, whereas scX showed only faint expression. The localization of P-gp was limited to the stromal vessels in icX by immunohistochemistry, whereas scX expressed no P-gp. Our findings suggest that the P-gp expressed on the stromal vessels in icX is a major contributing factor to multidrug resistance in human glioma in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Prognostic factors in delayed ischaemic deficit with vasospasm in patients undergoing early aneurysm surgery.

We have examined prognostic factors in delayed ischaemic deficit attributed to vasospasm following subarachnoid haemorrhage (SAH) and early aneurysm surgery. Among 605 patients with SAH, 201 patients developed a delayed ischaemic deficit and 137 of these underwent early surgery. These 137 patients were classified into groups A and B by outcome at 3 months after SAH (group A: the delayed ischaemic deficit was associated with an adverse outcome; group B: no adverse outcome). Factors indicating an unfavourable outcome were as follows: (i) older age; (ii) poor WFNS grade on admission; (iii) Fisher's scale of 4; (iv) intracerebral haemorrhage; (v) delayed ischaemic deficit following rerupture; (vi) complications of surgical intervention; (vii) delayed ischaemic deficit with disturbance of consciousness; (viii) lack of immediate improvement with hypervolaemic therapy; and (ix) intracranial complications after hypervolaemic therapy. We suggest that the reversibility of a delayed ischaemic deficit is determined by preceding brain damage and/or surgical complications.

Adult↗
PubMed1997

Clinical analysis of abdominal aortic aneurysms associated with iliofemoral occlusive disease.

Patients with abdominal aortic aneurysm (AAA) associated with iliofemoral occlusive disease due to arteriosclerosis obliterans (ASO) are often encountered clinically, but their clinical characteristics remain poorly defined. We divided 275 patients undergoing aneurysmectomy into 2 groups: 58 patients with both AAA and ASO (Group A) and 217 patients with AAA only (Group B). General characteristics, morphological features of the aneurysms, surgical procedures and operative results were then compared between the groups. In Group A, ruptured aneurysms were significantly less common (p = 0.005) and the aneurysms were smaller (p = 0.0009). The most common cause of death in Group A was acute myocardial infarction (3/7), in contrast to aneurysmal rupture of another arterial segment and malignancy (6/27, each) in Group B. These findings indicate that patients with AAA and ASO represent a subgroup of patients with particular clinical features.

Aged↗
PubMed1997

Surgical results of abdominal aortic aneurysm repair in patients with chronic renal dysfunction.

The purpose of this study was to determine the influence of preoperative renal dysfunction on the outcome of patients undergoing elective, infrarenal abdominal aortic aneurysm (AAA) repair. Patients undergoing AAA repair from 1984 to 1996 (n = 250) were divided into 2 groups, according to their preoperative serum creatinine levels: > or = 1.5 mg/dl (group A, n = 33) and < 1.5 mg/dl (group B, n = 217). There was no apparent difference in the incidences of preoperative risk factors, excluding ischemic heart disease, between the groups. The mortality rates of the 2 groups did not differ (9.9% vs 3.2% in groups A and B, respectively, p = 0.13), but the morbidity rate of group A (30.3%) was significantly higher than that of group B (12.9%, p = 0.0095). The 5-year cumulative survival rate of group A patients was 60%, which was significantly lower (p < 0.0001) than that of group B patients (84%). Five group A patients underwent simultaneous renal artery reconstruction, which relieved postoperative renal deterioration in 4, although 2 of them developed chronic renal failure requiring hemodialysis over 5 years after the operation. These findings suggest that morbidity and long-term survival in patients with renal dysfunction can be severe after AAA repair and that simultaneous renal artery reconstruction may delay renal function decline.

Aged↗
PubMed1997

Perforin-secreting killer cell infiltration in the aortic tissue of patients with atherosclerotic aortic aneurysm.

Cell-mediated immunity has been implicated in the pathogenesis of vascular cell injury in patients with atherosclerotic aortic aneurysms. To clarify the immunologic mechanisms involved, we examined the expression of a cytolytic factor, perforin, in infiltrating cells from aortic tissue samples taken from 6 patients with atherosclerotic aortic aneurysms. Immunohistochemical studies showed that the infiltrating cells consisted mainly of macrophages, natural killer (NK) cells, cytotoxic T lymphocytes (CTLs), and T helper cells, and that perforin was expressed in NK cells and CTLs. Immunoelectron microscopic studies demonstrated that the infiltrating cells released massive amounts of perforin directly on to the surface of arterial vascular cells. These findings provide the first direct evidence that some of the infiltrating cells in the aortic tissue consist of killer cells, and strongly suggest that these killer cells, especially NK cells and CTLs, may play a critical role in the vascular cell injury caused by atherosclerotic aortic aneurysm by releasing perforin.

Aged↗
PubMed1997

Surgical indications in patients with an intracerebral hemorrhage due to ruptured middle cerebral artery aneurysm.

In this retrospective study, the authors analyzed surgical outcomes in patients who suffered an intracerebral hemorrhage (ICH) as a result of a ruptured middle cerebral artery aneurysm. They studied 47 patients who underwent early aneurysm surgery and hematoma evacuation within 24 hours after onset of ICH. The types of ICH were classified into three groups according to their appearance on computerized tomography scanning: 1) temporal ICH; 2) intrasylvian hematoma; and 3) ICH with diffuse subarachnoid hemorrhage (SAH). Overall, 25 patients (53%) achieved a favorable outcome and 18 (38%) died. Factors that could be used to predict a favorable outcome included age less than 60 years, temporal ICH, World Federation of Neurological Surgeons Grade II or III, absence of a surgical complication, and a hematoma volume less than 25 ml. In the patients with temporal ICH, eight of nine patients achieved a good recovery and no patient developed a surgical complication or delayed ischemic deficit. The significant prognostic factor in patients with an intrasylvian hematoma was surgery within 6 hours after onset of symptoms. In patients with temporal ICH or intrasylvian hematoma, the results of the initial neurological examination did not accurately predict outcome. On the other hand, in patients with ICH and diffuse SAH, those patients who developed an ICH with a volume greater than 25 ml had a poor prognosis. These results indicate that aggressive surgical treatment should be performed in patients with a temporal ICH or an intrasylvian hematoma, regardless of the neurological findings on admission; in patients with ICH and diffuse SAH, a careful review of surgical indications is required.

Aged↗
PubMed1996

Restricted usage of T-cell receptor Valpha-Vbeta genes in infiltrating cells in aortic tissue of patients with Takayasu's arteritis.

BACKGROUND: Infiltration by perforin-secreting killer lymphocytes, such as T cells and natural killer cells, has been shown to be involved in the pathogenesis of vascular cell damage in Takayasu's arteritis. METHODS AND RESULTS: To investigate the immunological mechanisms involved, especially the nature of T-cell infiltration in Takayasu's arteritis as well as atherosclerosis, we analyzed the expression of T-cell receptor (TCR) Valpha and Vbeta genes in infiltrating cells in the aortic tissue of patients with Takayasu's arteritis and the atherosclerotic aortic aneurysm by polymerase chain reaction (PCR). We also analyzed the expression of cytokine genes by PCR. We found that the repertoires of TCR Valpha as well as Vbeta gene transcripts in Takayasu's arteritis were restricted. The infiltrating cells expressing Valpha2, Valpha16, Valpha17, Vbeta7, and Vbeta13.1 were found in 3 of 4 patients. In contrast, TCR Valpha-Vbeta repertoires in atherosclerotic aortic aneurysm were polyclonal. There was no significant difference in the pattern of cytokine gene expression between the two diseases. CONCLUSIONS: The restricted usage of TCR Valpha as well as Vbeta genes by infiltrating T cells in Takayasu's arteritis may indicate that a specific antigen in the aortic tissue was targeted. Our findings provide the evidence that distinct immunological mechanisms are involved in the pathogenesis of Takayasu's arteritis and atherosclerotic aortic aneurysm.

Aged↗
PubMed1996

Photoinduced Magnetization of a Cobalt-Iron Cyanide

Photoinduced magnetization was observed in a Prussian blue analog, K0.2Co1.4- [Fe(CN)6]&middot;6.9H2O. An increase in the critical temperature from 16 to 19 kelvin was observed as a result of red light illumination. Moreover, the magnetization in the ferrimagnetic region below 16 kelvin was substantially increased after illumination and could be restored almost to its original level by thermal treatment. These effects are thought to be caused by an internal photochemical redox reaction. Furthermore, blue light illumination could be used to partly remove the enhancement of the magnetization. Such control over magnetic properties by optical stimuli may have application in magneto-optical devices.

Journal Article↗
PubMed1996

Neurovascular developmental interaction: a specific form of vascular maldevelopment in the malformed brain. I. An experimental study and proposal of a new teratological concept.

The process of the development of the intracranial vessels was studied by means of immunohistochemical analysis of factor VIII in normal and exencephalic chick fetuses. The results revealed that the development of blood vessels in exencephalic brain was far advanced beyond the norm, with intense immunoreactivity to factor VIII on postincubation day 16 exceeding that on day 21 in normal controls. Compared with results regarding the direction of the overgrowth in the neuronal maturation process in the previous study using the chick exencephaly model, the findings of overmatured blood vessels were compatible with NSE- and somatostatin-positive elements that appeared especially in the overgrowth foci. The results of the present study suggested the pathogenic development of the "area cerebrovasculosa" in the neural placode as a phenomenon consequent upon hypervascularization in response to neuronal overgrowth, as seen in human cases of exencephaly or anencephaly. We emphasize the significance of this specific phenomenon in the development of the fetal central nervous system, namely neurovascular developmental interaction.

Animals↗
PubMed1996

Experimental models of congenital hydrocephalus and comparable clinical problems in the fetal and neonatal periods.

Morphological and developmental changes of the ventricular system are analyzed in three major experimental models of congenital hydrocephalus in the rat: 6-aminonicotinamide (6-AN)-induced and LEW/Jms and HTX mutant hydrocephalus. The clinically comparable forms of hydrocephalus and problems occurring during each period of intrauterine hydrocephalus are then discussed. Comparative morphological study revealed that 6-AN-induced hydrocephalus was comparable to the Dandy-Walker syndrome and that the critical period regarding this syndrome in fetal life was at the time of "legal termination". The LEW/Jms and HTX mutant models were identical with regard to the form of progressive hydrocephalus in the postnatal period, but the condition underlying the hydrocephalus during the fetal period differed. The LEW/Jms model was comparable to primary congenital aqueductal stenosis (aqueductal agenesis), and the hydrocephalic state appeared in the period of "intrauterine preservation" before pulmonary maturation was completed. On the other hand, the HTX fetuses demonstrated secondary change of the aqueduct in the perinatal period, although the model was considered to be of congenital communicating hydrocephalus. Cerebrospinal fluid (CSF) dynamics studied in the fetuses with 6-AN-induced hydrocephalus disclosed considerable pathophysiology comparable to "hydromyelic hydrocephalus." The historical trends of animal experimental models of congenital hydrocephalus are reviewed and comparable clinical problems suggested by those models discussed further.

6-Aminonicotinamide↗
PubMed1996

Neurological and medico-social problems of spina bifida patients in adolescence and adulthood.

Chronological changes in the neurological manifestations of spina bifida are well recognized in the early developmental periods: fetal, neonatal, infantile, pre-school and school life. However, little has been written about the medical and medico-social problems of spina bifida patients in adulthood. Patients now in this age group had the condition diagnosed and managed in an era when modern neurosurgical concepts were only just beginning to be established with the aid of invasive methodology. In our series of 141 cases of spina bifida, 18 patients (13.5%) were over 16 years of age. These included 9 cases each of spina bifida aperta (myeloschisis) and spina bifida occulta (spinal lipoma). The ages ranged from 16 to 47 years (mean: 23.5 years) in the former and from 16 to 57 years (mean: 29.2 years) in the latter group. During the long-term follow-up with quantitative analysis of the spinal neurological changes using the spina bifida neurological scale (SBNS), the final outcomes appeared very grave. Except for 1 case in each group-1 grade III in the spina bifida aperta group and 1 grade II in the spina bifida occulta group-all patients over the age of 27 years were classed as having grade IV disease. There were 2 patients with spina bifida aperta in whom postoperative paraplegia appeared after delayed radical repair (at the ages of 3 years and 18 years) and 3 patients with spina bifida occulta in whom obvious neurological deterioration was observed as the natural history with ongoing paraparesis at the spinal level or late onset of sexual problems. The other group included 2 patients with spinal lipoma in whom late neurological deterioration was observed and who were obliged to undergo a second operation in spite of aggressive early procedures performed during infancy. Among the patients with spina bifida aperta, 2 had marked ventriculomegaly as a form of long-standing overt ventriculomegaly in the adult (LOVA). After the CSF shunt procedure both these patients had problems with delicate shunt dependence and requested fine shunt flow regulation. Two patients in this group also suffered from severe depression. This study involves a limited number of patients, but it may be useful for reference on various points: (1) future prospects for the management of pediatric cases of spina bifida as practiced in the majority of hospitals; (2) natural histories of untreated cases and surgical indications for preventive procedure in spinal lipoma in early infancy; and (3) internationally differing levels of management of spina bifida and the historical development of individual countries' approaches to the problems.

Adolescent↗