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Biomedical subjects

N Arita

Publications and source records attributed to N Arita.

171 records · Page 10Linked to original sources

Levels in stroke patients of CSF astroprotein, an astrocyte-specific cerebroprotein.

Astroprotein (an astrocyte-specific cerebroprotein) levels in cerebrospinal fluid (CSF) were determined by radioimmunoassay in 47 stroke patients. (Astroprotein is immunologically identical to glial fibrillary acidic protein.) Astroprotein levels in CSF increased markedly in acute cases of intracerebral hemorrhage and slightly to moderately in some acute cases of subarachnoid hemorrhage and cerebral infarction. In intracerebral hemorrhage, CSF astroprotein levels in the acute stage of the ictus reflected the size of the lesion and were used to estimate the clinical outcome. In subarachnoid hemorrhage and cerebral infarction, CSF astroprotein levels were related to the general neurological state. Evidence obtained indicated that fundamentally different destructive and/or degenerative processes in the brain may be involved in intracerebral hemorrhage, subarachnoid hemorrhage and cerebral infarction and that determination of CSF astroprotein may have clinical significance in stroke patients.

Acute Disease↗

Relationship between ophthalmic artery blood flow and recanalization of occluded carotid artery. Ultrasonic Doppler study.

Ophthalmic artery blood flow in 5 patients with internal carotid artery occlusion of sudden onset was monitored by an ultrasonic Doppler flowmeter to investigate the possible relationship to spontaneous recanalization of the occluded artery. The occluded internal carotid arteries of 2 patients were confirmed angiographically to recanalize and the reversed flow of their ophthalmic arteries changed to physiological flow after the recanalization. The ophthalmic artery blood flow remained reversed in 2 patients whose occluded internal carotid arteries did not recanalize on the follow up angiograms. In the other patient, whose ophthalmic artery blood flow was not detected by the ultrasonic Doppler flowmeter in the acute stage, physiological flow through the ophthalmic artery was detected later. The occluded internal carotid artery did not recanalize and this physiological ophthalmic artery blood flow was filled through the circle of Willis.

Acute Disease↗

Transplantation of xenogeneic cells secreting beta-endorphin for pain treatment: analysis of the ability of components of complement to penetrate through polymer capsules.

The permeation of component of complement and secreted peptides through polymer capsules (PM30, K6305, and K5708) were examined. To analyze permeability by complement, the degree of hemolysis of sensitized sheep erythrocytes (EA) (1 x 10(9)/ml) enclosed in each type of capsule was examined after 24-h incubation in culture medium containing 10% human serum. PM30 and K6305 prevented the permeation of complement well, while K5708 did not. EA suspended in alginate prevented hemolysis even in K5708. Peptide permeation through the capsules was assessed by measuring the concentration of ACTH secreted by proopiomelanocortin (POMC)-gene-transfected-Neuro2A in the culture medium on days 4, 7, 14, 21, and 28 after encapsulation. The ACTH levels in the culture medium remained high until day 28. Alginate appeared to prevent the secretion, because ACTH levels decreased in alginate-suspended cells after day 14. The PM30-K6306 double capsules containing cell lines, Neuro2A, BHK21 (hamster fibroblasts), L929 (mouse fibroblasts), and HF-SKFII (human fibroblasts) were transplanted into the cerebrospinal fluid (CSF) space of the monkeys in the lumber region. The morphological examination showed the partial survival of Neuro2A, and BHK21 and HF-SKFII, which were cells concordant with the monkeys. On the other hand, L929 cells, which were discordant with the monkeys, could not survive at all. Because these results suggest that the complement components penetrate the polymer capsules, concordant cells are preferable for xenografting with polymer capsules into the CSF space.

Adrenocorticotropic Hormone↗

Long-term functional assessment of encapsulated cells transfected with Tet-On system.

In our previous study, xenogeneic mouse neuroblastoma cells bearing the POMC gene, the precursor of ACTH and beta-endorphin, were implanted within polymer capsules into the CSF space of rats. Although ACTH and beta-endorphin were secreted, we were not able to control the amounts or times of hormone release. A promoter that is inducible by administration of tetracycline derivatives (Tet) was linked to the POMC gene to control its gene expression (Neuro2A-Tet-On-POMC; NTP). The results showed that POMC gene expression in the implanted encapsulated NTP cells could be regulated in a dose-dependent manner by Tet administration to the hosts. However, no analysis of gene control with the Tet-On system over a long period has been performed. In this study, encapsulated NTP cells were treated in vitro with doxycycline (Dox) (1.0, 10, 100, 1000 ng/ml) continuously for a month. On day 4, the amount of ACTH secretion was dependent on the Dox dose. But in the course of the experiment, the difference of ACTH secretion among those treated with Dox 10, 100, and 1000 ng/ml was eliminated. On the other hand, NTP cells, which were treated with Dox (1000 ng/ml) just on days 7, 14, 21, and 28, secreted almost the same amount of ACTH in 24 h. From these results, for clinical use, an NTP cell line that secretes enough opiate to reduce pain sensitivity without Dox should be established, and Dox could then be administered if necessary.

Adrenocorticotropic Hormone↗

Hypogonadism of male prolactinomas: relation to pulsatile secretion of LH.

In order to investigate whether a hypothalamic disorder cause hypogonadism in male prolactinomas, LH pulsatile secretion was studied in 13 male patients. Serum PRL levels ranged from 186 to 45,000 ng ml-1 before treatment, and all the tumors were macroadenomas. Reduced LH secretion was revealed in 5 of 13 patients, and FSH was reduced in 1 of 13. Serum testosterone (T) levels were lower than the normal limit in all the patients. HCG tests in 3 patients showed good responses, but the peak values of T were lower than those of normal men. LH pulsatilities were examined in 5 hyperprolactinemic patients before treatment, in 4 hyperprolactinemic patients after operation, and in 8 normoprolactinemic patients after operation and/or bromocriptine treatment. There was no significant difference of the mean LH values, the frequencies of LH pulses, and amplitudes among the hyperprolactinemic patients before operation (n = 5), the normoprolactinemic patients after operation (n = 8), and normal men (n = 7). From these results, it was evident that the hypothalamus and pituitary function of male prolactinomas were well preserved, in spite of higher serum PRL levels and larger tumor size than those reported in females. It is suggested that the main cause of hypogonadism in these patients is due to testicular dysfunction resulting from excessive serum PRL.

Adult↗

Effect of MX2, a new morpholino anthracycline, against experimental brain tumors.

A new lipophilic morpholino anthracycline derivative, MX2, has an antitumor activity against a wide spectrum of experimental tumors. We examined the effect of MX2 against experimental brain tumors. At a low dose, MX2 exhibited strong growth inhibitory activity against human and rat glioma cells. The survival time of rats with meningeal carcinomatosis induced by intracisternal inoculation of Walker 256 carcinosarcoma cells was significantly prolonged by intravenous MX2. The growth of subcutaneously implanted glioma in rats was significantly retarded by intravenous MX2. These results suggest that MX2 warrants further experimental evaluation of its efficacy against malignant brain tumors including gliomas.

Animals↗

Antitumor effect of bromocriptine on estrogen-induced rat prolactinomas: ultrastructural alterations of secretory granules.

A quantitative analysis of ultrastructural alterations of secretory granules in correlation with prolactin (PRL) concentrations in estrogen-induced rat prolactinomas was performed to investigate the mechanism of the cytosuppressive action of bromocriptine (CB). The secretory granules of CB-treated adenomas increased in number but not in volume. The degree of exocytosis of the granules showed no significant decrease as reported previously, but rather an increase in adenomas treated with CB for 3 days. Radioimmunoassay revealed a decrease in PRL concentrations of adenoma tissues. and a marked reduction in serum PRL levels. These results suggest a low level of PRL in the secretory granules of the CB-treated pituitary adenomas.

Adenoma↗

Leptomeningeal dissemination of malignant glioma: immunohistochemical analysis of tenascin and glial fibrillary acidic protein.

Immunohistochemical expression of tenascin (TN) and glial fibrillary acidic protein (GFAP) was investigated in 9 human malignant gliomas with leptomeningeal dissemination. In these patients intracerebral glioma tissues obtained at operation and/or autopsy displayed localized expression of TN in tumor vessels and stroma. In contrast, TN was expressed in the tumor vessels, tumor stroma, and the cytoplasm of tumor cells to a high degree throughout all the leptomeningeal tumor tissues obtained at autopsy, whereas there was much less expression of GFAP in these tissues than at the primary site. These findings suggest that TN expression and decrease of GFAP expression in glioma tissue may be involved in the development of leptomeningeal dissemination.

Adolescent↗