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Biomedical subjects

A Okamura

Publications and source records attributed to A Okamura.

At least 73 records · Page 4Linked to original sources
PubMed1998

Heterogeneity of cadherin-8 expression in the neonatal rat striatum: comparison with striatal compartments.

Mechanisms of organization of the striatal compartments are poorly understood, although involvement of cell adhesion molecules in the compartmentalization has been suggested. Cadherin-8 distribution in the neonatal rat striatum was immunohistochemically studied using a rabbit anti-cadherin-8 antiserum. Intensity of cadherin-8 immunolabeling in the striatum was heterogeneous from postnatal day 0 to postnatal day 7. At postnatal day 9, cadherin-8 immunoreactivity was so weak that heterogeneity was no longer clearly seen. Cadherin-8 immunoreactivity was not detectable at postnatal day 14. Cadherin-8-rich and cadherin-8-poor areas were identical to calbindin-rich areas and tyrosine hydroxylase-rich patches, respectively, in allocation, indicating that cadherin-8 was predominantly expressed in the striatal matrix. These results suggest that cadherin-8 is involved in formation of the striatal compartmentalized structures during brain development.

Animals↗
PubMed1998

[An experimental study of local chemotherapy for metastatic lung tumor--isolated lung perfusion and pulmonary artery infusion].

PURPOSE: We evaluated the efficacy of local chemotherapy using isolated lung perfusion (ILP) and pulmonary artery infusion (PAI) in vivo to improve prognosis for patients with metastatic lung diseases. MATERIAL AND METHODS: Male F344 rats were used. The left lung was isolated and chemotherapeutic agents were administrated to the isolated lung by the ILP or PAI technique. Agents used were cisplatin (CDDP) and fluorouracil (5-FU), and their levels in the perfused lung and serum were measured (renal levels were also measured in CDDP groups). The results were compared with those obtained following intravenous administration (i.v.). In the ILP group, the left pulmonary artery and vein were clamped during perfusion. The agents were infused from the pulmonary artery, and the perfusate was collected from the pulmonary venotomy site following flushing with saline before declamping. In the PAI group, the left pulmonary artery was clamped and perfused with 0.2 ml of the agents, pulmonary arterial flow was occluded for 20 minutes, and perfusate was not collected. Rats were sacrificed 5 minutes after declamping in both groups, and the perfused lung and blood (and also kidneys in the CDDP group) were collected for pharmacokinetic examination. Histological examination of the perfused lung was also performed. RESULTS: In the ILP group treated with 1 mg of CDDP and PAI group treated with 0.1 mg of CDDP administration, the lung CDDP levels were significantly higher and the serum and renal CDDP levels were significantly lower than those in the IV group. In the ILP group treated with 150 mg of 5-FU and PAI group treated with 10 mg of 5-FU, the lung 5-FU levels were significantly higher than those in all IV groups and the serum 5-FU levels were lower than those in the IV group treated with 10 mg and 15 mg of 5-FU. The bronchopulmonary construction was histologically maintained in the perfused lung in each group. CONCLUSION: We concluded that local chemotherapy using ILP or PAI could be a safe and effective choice of therapy, and this method may be clinically applicable.

Animals↗
PubMed1998

[The pharmacokinetics of a fibrin adhesive agent applied to the rat lung].

PURPOSE: Although fibrin adhesive agents are frequently applied in the clinical setting, their pharmacokinetics in vivo remain to be clarified. We examined the pharmacokinetics of a fibrin adhesive agent applied to the rat lung. MATERIAL AND METHODS: Male Sprague Dawley rats were used. Under general anesthesia, left thoracotomy was performed, and the left lung was incised about 1 cm length and 1 mm depth. This incision was sutured with 9-0 nylon, and a fibrin adhesive agent containing 125I-labeled fibrinogen was applied. On days 1, 3, 7 and 14 after the operation, the left lung, right lung, liver and kidneys were collected. The tissue distribution of radioactivity was examined by determining the 125I levels in each organ as well as calculating the tissue levels of radioactivity. RESULTS: The tissue distribution of radioactivity in the left lung was significantly higher than those in other organs on days 1 and 3. The tissue levels of radioactivity in the left lung was significantly higher than those in other organs on days 1, 3 and 7. Each value rapidly decreased after day 7. CONCLUSION: A fibrin adhesive agent applied to the lung significantly remained at a high level through the inflammatory and proliferative phases followed by a prompt decrease before the phase of cicatrization. Therefore it is considered that a fibrin adhesive agent applied to the lung is satisfactory for the healing of wounds.

Animals↗
PubMed1998

Neurotoxicity evoked by N-methyl-D-aspartate in the organotypic static slice cultures of rat cerebral cortices: effect of GABA(A) receptor activation.

We investigated the neurotoxicity evoked by N-methyl-D-aspartate (NMDA) receptor stimulation in the organotypic static slice cultures of rat cerebral cortices. We also examined whether the gamma-aminobutyric acid (GABA)A receptor agonist muscimol has a protective effect on the NMDA-mediated neurotoxicity in this culture system. NMDA-mediated cytotoxicity was evaluated histologically and quantified by the measurement of lactate dehydrogenase (LDH) release into the culture medium. There was an NMDA-induced, dose-dependent leakage of LDH release and neuronal cell death, which were not attenuated by muscimol treatment. The results suggested that NMDA neurotoxicity is reproduced in the organotypic culture, and that GABA(A) receptor activation exerted no protective action against the NMDA cytotoxicity.

Animals↗
PubMed1998

Ovarian teratoma with gliomatosis peritonei: report of two cases.

Gliomatosis peritonei, a rare condition related to ovarian teratomas, involves the peritoneal implantation of numerous nodules of predominantly mature glial tissues. We report herein the cases of two patients with immature ovarian teratoma associated with gliomatosis peritonei, in one of whom a rapid progression of teratomatous implants occurred 14 weeks after her initial surgery. Gliomatosis peritonei is considered benign in most cases; however, some reports have documented the rapid recurrence of immature peritoneal implants, as implantation is associated with teratomas of all grades. Thus, in the face of peritoneal implants suspected to be of a teratomatous nature, thorough and extensive sampling is essential to exclude the presence of immature elements which may imply a poor prognosis and require aggressive therapy.

Ascitic Fluid↗
PubMed1998

Possible complications of magnetic coil stimulation in living tissue: assessment of changes in epiphyseal cartilage.

To assess the influence of repeated magnetic coil stimulation (MCS) of the peripheral nervous system on epiphyseal cartilage, we evaluated histological and structural changes after repeated MCS applied to the knee joints of young rabbits. There was a slight but significant histological change when repeated MCS at 100% intensity (100% of the maximal output) exceeded 600 times per day. However, we found no gross structural effects on the bone. We conclude that, if these results can be extrapolated to humans, MCS should be safe for stimulating peripheral nervous system for clinical electrophysiologic examinations in children.

Animals↗
PubMed1998

Cadherin-8 protein expression in gray matter structures and nerve fibers of the neonatal and adult mouse brain.

The topological distribution of mouse cadherin-8 protein in the neonatal and adult mouse brain was studied immunohistochemically using a rabbit antiserum. Cadherin-8 expression was restricted to several areas in neonatal brains constituting particular neural circuits, i.e. the limbic system, the basal ganglia-thalamocortical circuit, and the cerebellum and related nuclei. In addition, the nerve fibers linking some of the cadherin-8-positive areas, i.e. the habenulo-interpeduncular tract, decussation of the dorsal tegmentum, the medial longitudinal fasciculus, transverse pontine fibers, the brachium conjunctivum and the inferior cerebellar peduncle were cadherin-8 positive, as were the spinal tract of the trigeminal nerve, oculomotor nerve, facial nerve and trigeminal nerve. Cadherin-8 expression also showed a patch-like distribution in the intermediate gray layer of the superior colliculus, resembling acetylcholinesterase-rich patches in allocation. Segmentally organized cadherin-8-positive areas were found in the neonatal cerebellar Purkinje cell layer. Some nuclei and fibers in the brainstem and cerebellum, expressing cadherin-8 at neonatal stages, were also stained in the adult mouse brain. These findings suggest that cadherin-8 is involved in the formation of particular neural circuits by connecting areas expressing this molecule with positive nerve fibers, and indicate its possible implication in subdivisional organization in the superior colliculus and cerebellum.

Animals↗
PubMed1998

Hepatic infarction following percutaneous ethanol injection therapy for hepatocellular carcinoma.

We report on two patients who developed hepatic infarction after undergoing percutaneous ethanol injection therapy (PEIT) for hepatocellular carcinoma (HCC). In both cases, liver function parameters deteriorated immediately after the ethanol injection, and enhanced computed tomography images showed a wedge-shaped avascular low-density area due to hepatic infarction. In one patient, PEIT was performed for a nodule treated with transcatheter arterial infusion (TAI) using a suspension of styrene maleic acid neocarzinostatin (SMANCS) 4 weeks before. In the other patient, TAI with SMANCS had been carried out 14 months previously for a different nodule in the same segment where the nodule treated with PEIT was located. When PEIT is used for patients with HCC who have previously undergone TAI, especially with SMANCS, PEIT may induce hepatic infarction.

Antineoplastic Agents↗
PubMed1998

Increased hepatic nicotinamide N-methyltransferase activity as a marker of cancer cachexia in mice bearing colon 26 adenocarcinoma.

When a cachexigenic subclone (clone 20) of murine colon 26 adenocarcinoma was transplanted into female BALB/c mice, hepatic NNMT activity continued to increase until death in proportion to progressive carcass weight loss, a marker of cancer cachexia. On the other hand, noncachexigenic subclone (clone 5)-transplanted mice showed neither increase of NNMT activity nor carcass weight loss. Among cytostatic fluorinated pyrimidines, 5'-dFUrd could inhibit the increase of NNMT activity and prevent weight loss in mice bearing clone 20. On the other hand, 2'-dFUrd did not show these effects. 5-FUra and Tegafur inhibited the increase of NNMT activity at higher concentrations. These findings suggest that the levels of hepatic NNMT activity are closely associated with the degree of weight loss, and they appear to be a useful marker of cancer cachexia.

Adenocarcinoma↗
PubMed1998

An autopsy case of fetal Gaucher disease.

BACKGROUND: A case of fetal form of Gaucher disease in a Japanese fetus is presented. RESULTS: A macerated baby showing hydrops fetalis was dissected at 29 weeks of gestation. The fetus was heavier in the body, liver and spleen than a normal fetus at the same gestation period. It also suffered from pericardial effusion and ascites. The diagnosis of Gaucher disease was made by histological and biochemical findings. In microscopical examinations 'Gaucher cells', which were periodic acid-Shiff (PAS)-positive, alcian blue-positive and CD68-positive, existed in the lungs, liver, spleen, thymus, adrenal glands, bone marrow and brain. In thin layer chromatography, a large quantity of glucocerebroside was seen to have accumulated in the patient's organs.

Adult↗
PubMed1998

Occult papillary thyroid carcinoma in Hashimoto's thyroiditis presenting as a metastatic bone tumor.

Some occult thyroid carcinomas are hypothesized to regress and be eventually obliterated. We report here a patient whose condition supports this hypothesis. A 51-year-old male with primary hypothyroidism due to Hashimoto's thyroiditis suffered from a rib bone tumor. He had a diffuse goiter with no nodular lesion. Serum FT4 and TSH concentrations were 0.8 ng/dl and 36.4 microU/ml on taking 100 microg/day of T4. Anti-Tg- and -TPO-Ab were strongly positive (99 and 1380 U/ml). The iodine 123 scintigraphy demonstrated clear accumulation in the rib tumor, whereas the thyroid was scarcely visible. Biopsy of the rib tumor showed papillary proliferation of large atypical cells, which were immunohistochemically positive for thyroglobulin. Metastatic bone tumor of papillary thyroid carcinoma was therefore strongly suspected. He underwent a total thyroidectomy and the thyroid was stepwise sectioned completely at 3 mm intervals. The thyroid condition was diagnosed as Hashimoto's thyroiditis demonstrating diffuse and dense fibrosis, lymphocyte infiltration with lymphoid follicles and flattened atrophied follicles, but no carcinomatous foci were found. He was treated with I-131 and scintigraphy after the ingestion showed distinct accumulation in the rib tumors similar to that before thyroidectomy. No other abnormal uptake was observed. It is suggested that the primary occult thyroid papillary carcinoma regressed and was obliterated possibly by some immunologic or other host-resistance factors after it metastasized to the distant bone.

Bone Neoplasms↗
PubMed1998

A comparative analysis of integrating visual representations with haptic displays.

As further advances in visual display technologies and force feedback devices are integrated in virtual systems, questions remain: What level of reality does the system provide to the user? Is the environment convincing enough to engage the user and to maximize transfer? Are the visual and haptic displays fully integrated to provide seamless operation in the simulated environment? Does the system provide not only the ability to navigate through a simulated environment, but also realistic interaction with instrumentation and structures? We report on our advances in developing a virtual simulation system for training in functional endoscopic sinus surgery (FESS). Specifically, we will present work on subject trials exploring the realism provided by integrated visual and haptic displays, and compare and contrast surface vs. volume representation for presenting realistic models of the anatomy for surgical interaction.

Computer Simulation↗
PubMed1998

[Activation of bradykinin formation cascade on receiving autologous blood transfusion through a white cell-reduction filter in a patient treated with an ACE inhibitor].

We have experienced a case of anaphylactoid reaction on receiving autologous blood transfusion through a WBC filter for packed red blood cell (PRBC). The patient was a 71-year-old man with a history of hypertension treated with oral antihypertensive drug; enalapril, an angiotensin converting enzyme (ACE) inhibitor, who received anesthesia for Y-graft replacement. Autologous blood was obtained after the induction of general anesthesia in the operating room. Upon starting to return the stored blood with an unintentional use of a WBC filter, arterial blood pressure (ABP) fell within the first minute of the transfusion. We obtained three blood samples; pre-filtered blood (PRE), postfiltered blood (POST) and arterial blood (CIRC) after the event, and analyzed concentrations of bradykinin (BK), high molecular weight kininogen (HMWK) and high molecular weight kininogen-light chain (HMWK-LC). BK was higher in POST than in PRE. HMWK was lower in POST than in PRE, while HMWK-LC was higher in POST than in PRE. HMWK in CIRC was lower than in PRE, and HMWK-LC was higher in CIRC than in PRE. HMWK and HMWK-LC changes after the event suggest that BK formation cascade in the patient was activated on receiving the transfusion. ACE inhibitors were reported to augment such activation. The WBC filter has the negatively charged surface on filteration material and may activate the cascade. While WBC filters can avoid transfusion related reactions, hemodynamic responses should be watched closely in patients treated with ACE inhibitors.

Aged↗
PubMed1998

[Anti-fibrinogen antibody detected in a patient with systemic lupus erythematosus and disseminated intravascular coagulation].

A 22-year-old woman was admitted to our hospital with fever, generalized lymphadenopathy, and pancytopenia in February 1995. She was diagnosed as having systemic lupus erythematosus (SLE) based on positivity for anti-nuclear antibody, and polyarthritis among other findings. A diagnosis of disseminated intravascular coagulation (DIC) was made based on the increase of FDP and other data (DIC score: 7). We also detected an anti-fibrinogen antibody. Lymph node biopsy revealed subacute necrotizing inflammation and there were on signs of the hemophagocytic phenomenon in bone marrow. The DIC score improved and the anti-fibrinogen antibody disappeared in association with the response of SLE to prednisolone therapy. The onset of SLE associated with DIC has never been reported before, as far as we could determine. The mechanism of DIC associated with SLE may be related to endothelial damage caused by immune complexes.

Adult↗
PubMed1998

[Vascular endothelial cells and renin-angiotensin system].

The vascular renin-angiotensin system (RAS) is regulated independently from circulating RAS and plays a role in the local regulation of vascular tone, the modulation of sympathetic activity and vascular remodeling. Endothelial cells are a major source of angiotensin converting enzyme (ACE), which produces angiotensin II and degrades bradykinin, in normal arteries. Mechanical stress such as transmural pressure, stretch stress and shear stress appear to contribute to the regulation of endothelial ACE activity. In contrast, vessels with intimal proliferation such as atheromatous plaque and neointima following balloon injury show expression of ACE in smooth muscle cells and macrophages in the intimal lesions. Activation of ACE in intimal SMC may relate to a phenotypic change of SMC from the contracting type of the synthetic type. Activation of ACE in macrophages is also related to the transformation of macrophages from monocytes. Concerning the role of the activated RAS, elevated blood pressure and vascular tonus by angiotensin II are candidates of vascular injury and plaque rupture. Angiotensin II stimulates migration and proliferation of smooth muscle cells and production of extracellular matrix. Furthermore, angiotensin II increases oxidized-LDL which may be related to the forming of macrophages. These evidence suggest that activation of vascular RAS following endothelial dysfunction/injury play an important role in the pathogenesis of vascular remodeling and atherosclerosis.

Animals↗
PubMed1997

Cyclin-D1-gene amplification is a more potent prognostic factor than its protein over-expression in human head-and-neck squamous-cell carcinoma.

To evaluate the prognostic significance of cyclin D1 protein/gene expressions in human head-and-neck squamous-cell carcinoma (HNSCC), we examined amplification of the cyclin-D1 gene (CCND1) by the differential PCR method and over-expression of cyclin-D1 protein by immunohistochemistry in 45 paraffin-embedded sections from HNSCC. Amplification of CCND1 was found in 10 (22%) cases and over-expression of cyclin D1 was found in 24 (53%) cases. CCND1 amplification was also found in 3 (25%) of 12 cases of dysplastic lesions adjacent to HNSCC. The overall 5-year survival of patients with CCND1 amplification or with protein over-production was significantly lower than that of patients without (p < 0.0001 and p < 0.05, respectively). However, with multivariate analysis, only amplification of CCND1 retained an independent prognostic value (p = 0.0018). These suggest that CCND1 amplification occurs at early stages of HNSCC tumorigenesis and is a more useful prognostic factor than over-expression of cyclin D1 in HNSCC.

Adult↗