Biomedical subjects

S Oki

Publications and source records attributed to S Oki.

At least 19 recordsLinked to original sources

PubMed2001

[A case of free-floating ball thrombus in left atrium with mitral stenosis].

We report a rare case of free-floating ball thrombus in the left atrium with mitral stenosis. The patient was 71-year-old woman who admitted to the local hospital for transient ischemic attack. Electrocardiography showed atrial fibrillation and an echocardiogram examination revealed free-floating ball thrombus in the left atrium with mitral stenosis. She was transferred to our hospital for emergency open heart operation. After removal of the ball thrombus, mitral valve replacement and modified MAZE procedure were successfully performed. The size of the ball thrombus was 40 x 30 x 33 mm and weighed 20 g. Postoperative course was uneventful.

Aged↗

PubMed2000

Stat6 activation and Th2 cell differentiation [correction of proliferation] driven by CD28 [correction of CD28 signals].

CD28 engagement by specific monoclonal antibody (mAb) or binding of the natural ligands, CD80 and CD86, induces tyrosine phosphorylation of CD28, which in turn recruits and activates the signal transducer and activator of transcription 6 (Stat6). The Stat6 association with CD28 is specifically induced by CD80 or CD86 ligand binding and is not dependent upon the secretion of IL-4 or IL-13. Activated Stat6 translocates to the nucleus and binds to a Stat6-responsive element on the human IL-4 promoter. CD28 ligation induces Stat6-dependent transcriptional activation of a reporter gene under the control of a multimerized Stat6-responsive element fused to an essential part of the IL-4 promoter. Primary stimulation of naive CD4(+) T cells with anti-CD28 mAb in the presence of IL-2, but in the absence of anti-CD3 mAb induces preferential production of IL-4 and expression of CCR4 mRNA after secondary stimulation with anti-CD3, indicating the preferential differentiation of Th2 cells. These findings suggest that initial IL-4 production required for commitment of naive T cells toward Th2 cells may be provided in response to signals delivered via CD28 by antigen-presenting cells.

Animals↗

PubMed2000

Age changes of neuromuscular junctions in the extensor digitorum longus muscle of spontaneous thymoma BUF/Mna rats. A scanning and transmission electron microscopic study.

BUF/Mna rats spontaneously develop thymomas and cause muscle weakness of hind legs at an advanced age. This rat strain has been recognized as a suitable animal model for human myasthenia gravis or related myopathies. To characterize the structural changes of neuromuscular junctions (NMJs) in BUF/Mna rats, subneural apparatuses (SNAs) of extensor digitorum longus muscles of young-adult (4-month-old) and aged (22- to 25-month-old) male rats were examined using scanning and transmission electron microscopy. The SNAs of NMJs in young rats consist of complex labyrinthine gutters with numerous slit-like junctional folds. SNAs in aged BUF/Mna rats, however, are characterized by: (1) a group of cup-like depressions with very wide slit-like junctional folds in relatively large muscle fibers (the major type), (2) the presence of slit-like folds on the flat sarcoplasm outside the cup-like depressions or on the protruded sarcoplasm, and (3) winding gutters or a small number of round depressions with poorly developed synaptic folds in small and medium-sized muscle fibers (the minor type). Since similar structural changes have been reported in dystrophic mice or normally aged rats, it is suggested that both the slowly progressing muscle atrophy and age-dependent turnover of muscle fibers may occur in the aged BUF/Mna rats.

Aging↗

PubMed2000

Morphological changes of capillaries in the rat soleus muscle following experimental tenotomy.

We examined the structural changes of capillaries in the rat soleus muscle 4, 7, 14, and 35 days after experimental limb tenotomy. In the soleus muscles after tenotomy, muscle fibres degenerated and some of them were destroyed; the muscle did not seem to recover until the 35th day. On the 14th day, some small muscle fibres, probably regenerating muscle fibres, started forming within the basal-lamina tube and remained after necrosis of a pre-existing muscle fibre. Most capillaries at each stage were of the continuous type. However, about 10% of the capillaries around degenerated muscle fibres at days 4, 7 and 14 consisted of endothelial cells with a small number of fenestrae bridged by a single-layered diaphragm. On the 14th day, capillaries around small regenerating muscle fibres also often had a small number of fenestrations. Even on the 35th day, capillaries occasionally had fenestrations. Additionally, some of the fenestrated capillaries formed small pores at the fenestrated portion of the endothelial cells. The untreated muscles contained only continuous capillaries. These findings suggest that fenestrations in the endothelial cells may occur in intramuscular capillaries not only around degenerated muscle fibres but also around regenerating muscle fibres after tenotomy.

Achilles Tendon↗

PubMed2000

[Myelopathy caused by tentorial dural arteriovenous fistula: a rare case report].

A 51-year-old man with myelopathy due to intracranial dural arteriovenous fistula (dural AVF) is reported. At age 46, the patient experienced subarachnoid hemorrhage caused by rupture of the dural AVF and underwent embolization of the lesion at another hospital. At this time, the patient complained of numbness in his legs and showed paraplegic gait disturbance. MRI scan revealed swelling of the cervical spinal cord. Cerebral angiograms demonstrated the recurrence of tentorial dural AVF fed by bilateral meningohypopheseal trunks and the right posterior inferior cerebellar artery. Arteriovenous shunt (AV shunt) flow was drained into the anterior spinal vein. It seemed that the swelling of the spinal cord and myelopathy was caused by venous hypertension of spinal veins. After surgical interruption of the right petrosal vein which connected dAVF with cerebellar veins, AV shunt was obliterated successfully. Postoperative cerebral angiograms showed disappearance of dural AVF. The patient became ambulant and his cervical spinal cord appeared normal on the postoperative MRI scan. Surgical interruption of the draining vein was simple, effective and essential treatment.

Arteriovenous Fistula↗

PubMed2000

[Clinical evaluation of granisetron hydrochloride for nausea and vomiting induced by oral anticancer drugs].

We investigated the antiemetic effect, safety and usefulness of granisetron hydrochloride tablets on nausea and vomiting induced by oral anticancer drugs used in chemotherapy for gastric cancer and colorectal cancer. In the present trial, oral administration of granisetron hydrochloride was performed during 5 days after nausea or vomiting. 1) Clinically, the effective rate of granisetron hydrochloride (the percentage of cases in which the drug was assessed as "Remarkably effective" or "Effective") was more than 75% on each day of administration. There were no adverse events or abnormal laboratory tests. 2) In terms of usefulness, granisetron hydrochloride was rated "Extremely useful" or "Useful" in 17 out of 23 cases (78.2%). The above results have shown that granisetron hydrochloride tablets, administrated orally once daily at a dose of 2 mg, have an excellent antiemetic effect, and that this is a safe and useful drug.

Administration, Oral↗

PubMed2000

[Malignant peripheral nerve sheath tumor with divergent cartilage differentiation from the acoustic nerve: case report].

Malignant peripheral nerve sheath tumors(MPNSTs) of the acoustic nerve are very rare. Only seven cases of MPNST arising from the acoustic nerve have been reported. The authors present a case of MPNST with divergent cartilage and melanotic differentiation of the acoustic nerve. The patient was a 69 year old man admitted to our neurosurgical service in January 1999 complaining of left facial nerve palsy and hearing difficulty of his left ear. The initial CT showed a tumor at the left cerebellopontine angle region. On MRI the tumor was depicted as low intensity on T 1-weighted image and high intensity on T 2-weighted image, the mass was heterogeneously enhanced after administration of Gd-DTPA. The partial removal of the tumor was performed in January 1999. He was discharged February 1999. But he was admitted again because of progressive cerebellar ataxia. MRI showed the rapid regrowth of the residual tumor. In March 1999, complete removal of the tumor was performed. Histopathological analysis revealed a malignant spindle cell neoplasm with divergent cartilage and melanotic differentiation. We review the relevant literature concerning MPNST of the acoustic nerve and discuss the clinical features of malignant eighth cranial nerve tumor.

Aged↗

PubMed1999

Autoantibodies to T cell costimulatory molecules in systemic autoimmune diseases.

To determine whether antilymphocyte Abs to T cell costimulatory molecules are generated in patients with autoimmune diseases and, if they exist, to clarify the mechanism of their production and pathological roles, we investigated the presence of autoantibodies to CTLA-4 (CD152), CD28, B7-1 (CD80), and B7-2 (CD86) in serum samples obtained from patients with various autoimmune diseases and from normal subjects using recombinant fusion proteins. In ELISAs, anti-CD28, anti-B7-1, and anti-B7-2 Abs were rarely seen, whereas anti-CTLA-4 Abs were detected in 8.2% of the patients with systemic lupus erythematosus, 18.8% of those with rheumatoid arthritis, 3.1% of those with systemic sclerosis, 31.8% of those with Behçet's disease, 13.3% of those with Sjögren's syndrome, and 0% of healthy donors. This reactivity was confirmed by immunoblotting. More importantly, the purified anti-CTLA-4 Abs reacted with CTLA-4 expressed on P815 cells by flow cytometry. In addition, we found at least three epitopes on the CTLA-4 molecule. Furthermore, among the patients with Behçet's disease, uveitis was seen significantly less frequently in the anti-CTLA-4 Ab-positive patients. Taken collectively, these data indicate that anti-CTLA-4 autoantibodies are generated in systemic autoimmune diseases by an Ag-driven mechanism and may modulate the immune response in vivo by binding to CTLA-4 on T cells.

Abatacept↗

PubMed1999

Outcomes of surgical treatment for cervical myelopathy in patients more than 75 years of age.

STUDY DESIGN: Retrospective study on the results of surgical treatment of compressive cervical myelopathy in patients more than 75 years of age. OBJECTIVES: To investigate clinical features and surgical outcomes of compressive cervical myelopathy in aged patients and to discuss the role of surgical treatment. SUMMARY OF BACKGROUND DATA: There are few data focused on the outcomes of surgery in patients with cervical myelopathy who are more than 75 years of age. METHODS: Seventeen patients with compressive cervical myelopathy who underwent surgery were reviewed. The average age at the time of surgery was 77.2 years. Posterior decompression in 15 patients and anterior decompression in 2 patients were performed. Neurologic deficits before and after surgery were assessed using a scoring system proposed by the Japanese Orthopaedic Association (JOA score). Independence of daily living was evaluated. Radiologic features were examined with radiographs and magnetic resonance imaging. Clinical results were compared with those of patients less than 65 years old as a control. RESULTS: The preoperative mean JOA score was 6.1, the postoperative maximum JOA scores averaged 11.4, and the recovery rate was 48.4%. These were significantly inferior to scores in those less than 65 years of age. All seven of the patients who could not walk even with aids before surgery became independent in daily activities after surgery. At the final follow-up, the mean JOA score had decreased to 10.7 and the recovery rate to 39.1%. Five of nine patients whose follow-up periods were more than 5 years showed decreases in JOA score, although all patients were still ambulatory. CONCLUSIONS: Surgical decompression for cervical myelopathy appears to be beneficial, even in patients more than 75 years of age, in improving neurologic function and ability to engage in activities of daily living.

Activities of Daily Living↗

PubMed1999

Abdominal Aortic Dilatation in Japanese Residents.

The correlation between abdominal aortic dilatation and arteriosclerotic risk factors was studied in 2514 Japanese residents (947 men, 1567 women, mean age 70 years old). The aortic diameter was measured by ultrasound and an aortic dilatation was defined as above 30 mm in diameter, including abdominal aortic aneurysm (AAA). Forty-three (1.7%) patients with a dilated aorta and 2471 with a normal-sized aorta were compared. Abdominal aortic dilatation was significantly (p < 0.01) more frequent in men than in women (3% vs 0.7%). Obesity and hyperlipidemia were slightly (p < 0.1) more frequent in patients with a dilated aorta than in those with a normal-sized aorta. There were no significant differences between the two groups in mean age, frequency of smoking, diabetes mellitus, and coronary artery disease. In conclusion, male obesity and hyperlipidemia may be risk factors for aortic dilatation in Japan. Women may not be screened because of cost-effectiveness. The prevalence of aortic dilatation in Japan was lower than in European countries. However, screening for AAA using ultrasound would be advantageous when considering the grave prognoses of ruptured AAA.

Journal Article↗

PubMed1999

Postoperative brain complications following retrograde cerebral perfusion.

This study was undertaken to investigate the neurological risk factors associated with the retrograde cerebral perfusion (RCP) technique, by examining the relationship between intraoperative parameters and post-operative brain complications. A total of 12 patients who underwent surgery for thoracic aortic aneurysms using the RCP technique were included in this study. Profound hypothermia was induced through cardiopulmonary bypass which was established with a femoral arterial cannula and bicaval return. During RCP, a venous drainage cannula from the superior vena cava (SVC) was switched over to the arterial return circuit, and oxygenated blood was retrogradely infused through the SVC. The perfusion flow rate was maintained at 273 +/- 113 ml/min and the SVC pressure was maintained at 15 +/- 6 mmHg. The RCP time was 68 +/- 27 min with a range of 27-130 min, and the lowest rectal temperature was 16 +/- 1 degrees C. The total elapsed time until emergence from anesthesia after the operation was 12 +/- 6 h. The operation time correlated with the awakening time (r = 0.729, P = 0.0088). Longer RCP times of up to 101 and 130 min tended to result in post-operative brain damage. The lowest rectal temperature also correlated with the awakening time (r = 0.697, P = 0.0149), and an inverse correlation between the SVC pressure and the awakening time was observed (r = -0. 727, P = 0.0091). These findings demonstrate the importance of reducing both the RCP and operation times to decrease the incidence of brain damage. If carried out under optimal conditions, including perfusion pressure and brain temperature, RCP could be marginally prolonged safely without causing major neurological complications.

Aged↗

PubMed1999

Capillary changes with fenestrations in the contralateral soleus muscle of the rat following unilateral limb immobilization.

Using electron microscopy, we examined structural changes in the capillaries of the immobilized and contralateral soleus muscles in the rat after the unilateral limb had been immobilized for 4 weeks. Individual contralateral muscle fibers showed a normal structure, compared with the structure in the immobilized muscle fibers. Most capillaries in the contralateral muscle were of the continuous type. However, about 5% of the examined capillaries in these muscles in each rat had fenestrations. The non-nuclear portions of the endothelial cells in these capillaries were extremely thin and were perforated by several fenestrations that were bridged by a single-layered diaphragm. The fenestration of capillaries in the contralateral muscle may have been caused by some the unilateral limb immobilization.

Animals↗

PubMed1999

Augmentation of CTLA-4 expression by wortmannin: involvement of lysosomal sorting properties of CTLA-4.

CTLA-4 (CD152) is transiently induced on the cell surface of activated T cells and expression is limited at a low level. In this study, we investigated the possibility that phosphatidylinositol 3 kinase (PI 3-K) and other related PI kinases associated with the cytoplasmic domain of CTLA-4 are involved in intracellular trafficking and sorting of CTLA-4 protein. Treatment with micromolar concentrations of wortmannin (WN) for >4 h enhanced both cell-surface and intracellular CTLA-4 without affecting its transcriptional activities in a murine mastocytoma cell line transfected with the human CTLA-4 gene and normal activated CD4(+) T cells. However, a more specific PI 3-K inhibitor, LY294002, failed to affect CTLA-4 expression, indicating that the action of WN is independent of conventional PI 3-K activities. WN down-regulated specific association of CTLA-4 with adaptor proteins and its endocytosis. The fact that lysosomotropic agents, ammonium chloride and monensin, enhanced CTLA-4 expression suggests that WN may also block lysosomal sorting and consequent degradation of CTLA-4. Co-localization of CTLA-4 and lysosome-associated membrane protein-1 detected by immunofluorescence microscopy indicates the actual lysosomal sorting of CTLA-4. Our data suggest the existence of WN-sensitive enzymes, which promote lysosomal sorting of CTLA-4. In addition to rapid endocytosis by clathrin-associated adaptor complex, a prompt sorting of CTLA-4 to lysosomes may be one of the regulatory mechanisms for managing CTLA-4 signals in intracellular trafficking pathways.

Abatacept↗

PubMed1999

Aged neuromuscular junctions in the extensor digitorum longus muscle of the rat as revealed by scanning electron microscopy.

We examined the overall morphology of subneural apparatuses (SNAs) at neuromuscular junctions by scanning electron microscopy in the extensor digitorum longus muscle of aged (18 months) rats. Most of aged SNAs were mainly characterized by a large number (more than 20) of cup-like depressions (2-5 microns in diameter) with numerous slit-like junctional folds about 0.1 micron wide and 5 microns at maximum length, while some SNAs consisted of a small number (fewer than 10) of depressions or poorly-developed gutters containing pit-like and/or slit-like junctional folds. Additionally, numerous slits were often found outside the depressions, possibly indicating the pre-existing junctional folds persisted for a long time after the gutter-into-cup transformation of the SNAs. These structural changes of SNAs during ageing are discussed briefly.

Aging↗

PubMed1999

High incidence of meningioma among Hiroshima atomic bomb survivors.

Since the atomic bomb explosions in Hiroshima and Nagasaki, high incidences of leukemia, thyroid cancer and other tumors have been reported as atomic bomb-induced tumors. We investigated the incidence of meningioma among Hiroshima atomic bomb survivors. Sixty-eight patients surgically treated for meningioma who had been within 2.0 km of the hypocenter of the explosion were identified. Six hundred and seven non-exposed patients with meningioma were also studied. Treatment dates were from 1975 to 1992. The incidences of meningioma among 68 subjects within 2.0 km and 607 non-exposed patients were 8.7 and 3.0 cases per 10(5) persons per year, respectively. The incidences of meningioma among the survivors of Hiroshima in 5-year intervals since 1975 were 5.3, 7.4, 10.1, and 14.9, respectively. The incidences of meningioma classified by distances from the hypocenter of 1.5-2.0 km, 1.0-1.5 km and less than 1.0 km were 6.3, 7.6 and 20.0, respectively. The incidences of meningioma classified by doses to the brain of 0-0.099 Sv, 0.1-0.99 Sv and more than 1.0 Sv were 7.7, 9.2 and 18.2, respectively. The incidence of meningioma among Hiroshima atomic bomb survivors has increased since 1975. There was a significant correlation between the incidence and the dose of radiation to the brain. The present findings strongly suggest that meningioma is one of the tumors induced by atomic bombing in Hiroshima.

Brain↗

PubMed1999

[Efficacy of adjuvant hepatic arterial infusion chemotherapy following resection of colorectal liver metastases].

PURPOSE: The aim of this study is to evaluate the effect of adjuvant hepatic arterial infusion chemotherapy (HAIC) following liver resection on the frequency of residual liver recurrence and overall survival. PATIENTS AND METHODS: During 1992 to 1997, 84 patients with liver metastasis from colorectal cancer resected curatively had undergone adjuvant HAIC. The regimen of the HAIC is 1,500 mg of 5-FU by 24-hr continuous infusion once a week for eight weeks. 37 cases in the HAIC group, including patients given more than 7 g of 5-FU, were compared with the control group. RESULT: The cumulative 5-year liver recurrence-free ratios were 72.6% in the HAIC group and 29.8% in the control group (p = 0.0005). The cumulative 5-year survival ratios were 61.4% in the HAIC group and 28.0% in the control group (p = 0.0069). Multivariate analysis revealed that more than 5 mm of surgical margin and adjuvant HAIC significantly decreased the risk of recurrences in residual liver. CONCLUSION: Adjuvant HAIC is an effective procedure to prevent recurrence in residual liver and improve the prognosis of patients with liver metastasis from colorectal cancer.

Adult↗

PubMed1999

[Supratentorial ectopic ependymoma: a case report].

Ependymomas usually arise from the ventricular surface and approximately two-thirds of them are infratentorial. We present an unusual case of supratentorial ependymoma located in the parietal parenchyma and exhibiting no continuity with the ventricular system. On March 30, 1998, a 63-year-old woman was admitted to our neurosurgical service because of a sudden consciousness loss attack two weeks before. On admission, neurological examination revealed no abnormal findings. Computerized tomography (CT) revealed a mass lesion of the parietal lobe which was enhanced homogeneously. Magnetic resonance imaging (MRI) also showed the mass of the parietal lobe which was iso-intense on T1-weighted images, iso and high intense on T2-weighted images and homogeneously enhanced by administration of Gd-DTPA. In the angiography, left carotid angiograms showed a tumor stain. On February 26, 1998, total removal of the tumor was performed using stereotactic craniotomy with neuronavigator and intraoperative echography. After surgery, focal radiation therapy (56Gy) was carried out. The pathological diagnosis was cellular ependymoma with partial clear cell components. Several kinds of tumor may occur in the cerebral parenchyma. We conclude, however, that ependymoma has to be included in the differential diagnosis when the tumor location is distant from the ventricles.

Brain Neoplasms↗

PubMed1998

Micrometastatic colorectal cancer lesions in the liver.

A surgical resection of metastatic liver lesions from colorectal cancer contributes to an improved prognosis. However, the postoperative recurrence rate remains high, particularly in the residual liver. This is probably the result of the failure to detect small lesions. In the present study, we histologically examined the presence of intrahepatic micrometastases, which are considered to be related to recurrence in the residual liver. Intrahepatic micrometastases were histologically examined in 31 resected specimens of 25 patients undergoing a hepatic resection because of metastasis to the liver from colorectal cancer. Micrometastases were found in 14 of 25 cases (56.0%). They were located in the portal veins, central veins, sinusoid, and bile ducts. The longest distance from the main metastasis was 38.2 (mean 7.5 +/- 8.0) mm. The size of the macrometastases became larger, and the frequency of micrometastases and the distance of micrometastases from macrometastases had a tendency to increase. Continuous invasion of the macrometastases into the micrometastases through the vasculature or bile duct was also observed. These results suggested that some micrometastases observed in the metastatic liver from colorectal cancer were thus seeded from the primary lesions, while other micrometastases originated from the macrometastatic lesions as satellite lesions.

Colorectal Neoplasms↗