Search PubMed⌕ Search

Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 559 records · Page 31Linked to original sources
PubMed1989

Circulatory responses to epidural blockade of treated and untreated hypertensive patients.

The circulatory effects of epidural blockade were studied in 82 hypertensive patients. To compare the circulatory responses to epidural blockade between treated and untreated hypertensive patients, patients were divided into 60 treated and 22 untreated hypertensive patients groups, and to confirm the magnitude of hemodynamic changes according to the segment of epidural approach, each group was then subdivided into 3 groups as cervical, thoracic and lumbar. The blood pressure and the pulse rate were measured before and after establishment of epidural blockade. The baseline blood pressure of untreated group was significantly higher than that of treated one (P < 0.05), but there was no difference between two groups in the initial pulse rate. At 20 min after meperidine administration to epidural space, blood pressure drop was more pronounced in untreated thoracic subgroup than in treated one (P < 0.05), but there was no significant difference in blood pressure drop between treated and untreated groups of cervical and lumbar blockade. Regarding the pulse rate change, there was no significant difference between treated and untreated cases of all the subgroups. The rate of fluid load required to maintain the adequate blood pressure in the first 20 min of epidural blockade was more in treated than in untreated cases of cervical subgroup. During surgery the administration of vasopressor agents was more frequently required to maintain blood pressure in treated and untreated thoracic subgroups, while the administration of vasodilator agents was more frequent in treated and untreated cases of cervical and thoracic subgroups. The incidence of rebound hypertension was relatively high in untreated cervical and thoracic subgroups as compared to treated ones.

Journal Article↗
PubMed1989

An enzyme immunoassay of slow moving protease (SMP) in human gastric mucosa.

A two-site enzyme immunoassay for slow moving protease (SMP) of human gastric mucosa has been developed. The detection limit of SMP was 50 pg/tube and the optimal assay range was 0.5 to 50 ng/tube. This assay system made it possible to measure a trace amount of gastric mucosal SMP in endoscopic biopsy-specimens. Mean gastric mucosal SMP contents of the antrum, the angles, and the distal and proximal corpuses were 4.5, 3.7, 2.6, and 2.5 micrograms/mg protein, respectively. The antral mucosa contained a larger amount of SMP than the gastric mucosa of other area. The present enzyme immunoassay system is sufficiently sensitive for the clinical study of SMP in gastrointestinal tract.

Electrophoresis, Polyacrylamide Gel↗
PubMed1989

Induction of astroglial growth inhibition and differentiation by sialosyl cholesterol.

Normal rat astroblasts in culture were exposed to 11 sialosyl or cholesterol derivatives at concentrations lower than 20 microM. Synthesized sialosyl cholesterols (alpha- and beta-D-N-acetyl neuraminyl cholesterols) and cholesterol sulfate showed a marked growth inhibitory action. Sialosyl cholesterol uniquely evoked an astroglia-like stellation resembling that induced by glia maturation factor (GMF) as well as a suppression of GMF-induced mitogenesis of astroblasts. The minimal incubation period of sialosyl cholesterol for the initiation of growth inhibition was as short as one hour. The inhibitory effect retained an irreversibility even after removal of the drug. Cytosolic protein with 58 kDa Mr in size was specifically phosphorylated by sialosyl cholesterol through a certain protein kinase dependent on neither Ca2+ nor cyclic AMP. The competition experiment of sialosyl cholesterol action revealed that sialosyl and cholesterol moieties were indispensable for the phenomena. These results most likely imply that sialosyl cholesterol alters the membrane microenvironment to affect the affinity of growth factor receptor, protein kinase activity, and/or cytoskeletal anchorages.

Animals↗
PubMed1989

Gelatinases of murine metastatic tumor cells.

The properties of gelatinases secreted in culture medium of murine fibroblasts, macrophages, colonic carcinoma, FBJ virus-induced osteosarcoma, Lewis lung carcinoma and mammary tumor cells were compared. Normal fibroblasts and macrophages secreted gelatinases of 60,000 and 95,000 molecular weights, respectively. Tumor cells secreted both of these gelatinases, although the relative amounts of the 60 kDa and 95 kDa gelatinases differed among the cell lines. The cell lines that had the greatest metastatic potential to the lung secreted the highest amount of 95 kDa gelatinase. The 95 kDa gelatinase produced by tumor cells had properties similar to that of macrophages.

Animals↗
PubMed1989

Facilitation of quadriceps motoneurones by group I afferents from pretibial flexors in man. 1. Possible interneuronal pathway.

The neuronal pathway of the facilitation of quadriceps (Q) motoneurones (MNs) evoked by stimulation of the common peroneal nerve (CPN) has been reinvestigated using both the post-stimulus time histogram (PSTH) method for measurement of the firing probability of individual units and the H reflex technique. It has been found that Ia (and to an unknown extent Ib) afferents from pretibial flexors - but not from peroneal muscles - are responsible for this excitation. The central latency of the CPN-induced excitation of Q MNs was estimated to be 3-3.7 ms longer than that of their monosynaptic Ia excitation. To further investigate the neuronal pathway of the CPN-induced excitation the spatial facilitation technique was used, the effects on the Q H reflex of two conditioning stimuli (applied to the CPN and the femoral nerve - FN) being compared when applied separately and together. When the two conditioning volleys were timed to reach the spinal cord simultaneously the facilitation of the H reflex on combined stimulation was larger than the algebraic sum of the effects by separate stimuli in 40% of the cases. It is argued that this additional facilitation reflects summation at a premotoneuronal level and it is concluded that non-monosynaptic Ia excitation of Q MNs from Q and pretibial flexors is, at least partly, mediated through a common pathway. In those individual units in which stimulation of the FN and/or the CPN evoked a non-monosynaptic Ia excitation, this excitation was reduced on combined stimulation of the two nerves. It is argued that this reflects inhibition of the interneurones mediating the excitation, i.e. consists in a disfacilitation of the MNs. It is suggested that the non-monosynaptic (homonymous and heteronymous) Ia excitation of Q MNs in man (and the inhibition of this excitation) is mediated through a system of neurones similar to the system recently described in the cat by Edgley and Jankowska (1987).

Adult↗
PubMed1989

Neuroendocrine markers in central nervous system neuronal tumors (gangliocytoma and ganglioglioma).

We studied five cases of central nervous system neuronal tumor, one gangliocytoma and four gangliogliomas, both ultrastructurally and immunohistochemically, using antibodies to neuroendocrine markers including tyrosine hydroxylase (TH), serotonin (5HT), somatostatin (SOM), met-enkephalin (MEK), leu-enkephalin (LEK), substance P (SP), gastrin, vasopressin, oxytocin, vasoactive intestinal polypeptide, adrenocorticotropic hormone and calcitonin. In all cases, the presence of dense-core vesicles (60-250 nm) in the neuronal elements was the characteristic ultrastructural finding. Synapses were observed in two cases. Immunohistochemically, variable numbers of neuronal cells showed positive staining for SOM in five cases, TH, MEK and LEK in three cases, and 5HT and SP in one case each. The others were negative. Positive immunoreactivity for multiple markers was shown in all cases. SOM, TH, 5HT and SP were present in the small- to medium-sized cells, while MEK and LEK were almost exclusively confined to the large cells. Our study clearly indicated that these tumors contained neuronal cells which were not homogeneous with regard to neuroendocrine markers.

Biomarkers↗
PubMed1989

Effects of cytokines on cultured microvascular endothelial cells derived from gerbil brain.

Microvascular endothelial cells were isolated from gerbil brain and cultured. These cells retained an endothelial-specific marker, FVIII-related antigen. Alkaline phosphatase activity was also present in early passage. Two weeks after plating, these cells were attached to the culture dishes and had become like cobblestones in appearance. Then, the addition of tumor necrosis factor at a concentration of 1000 U/ml or more suppressed the DNA synthesis activity of endothelial cells by about 70% and induced morphological changes in the cells, which developed a spindle-like form and showed overlapping of cells, indicating loss of contact inhibition. The administration of interferon-tau induced no change. When a similar experiment was performed using culture supernatants of human glioma cells that had been cultured for a few days, DNA synthesis activity was suppressed by approximately 50% or more in 6 of 12 samples. The suppression of activity, however, was abolished by the addition of anti-tumor necrosis factor antibody in these 6 cases, suggesting the presence of activity resembling that of the tumor necrosis factor in the culture supernatants.

Animals↗
PubMed1989

Enhancement of both intracellular uptake and antitumor action of cisplatinum on human neuroblastoma cells by encapsulation in liposomes.

Phospholipid vesicles (phosphatidylcholine:phosphatidylserine:cholesterol = 6:2:3 in molar ratio) with a small unilamellar structure were used as drug carriers for introducing cis-diamminedichloroplatinum (CDDP) into human neuroblastoma cells, IMR-32, GOTO, Nagai, and TGW. DNA synthesis of IMR-32 cells among the human neuroblastoma cell lines was inhibited most strongly by CDDP-liposomes. CDDP-liposomes dose-dependently inhibited the DNA synthesis of IMR-32 in a similar fashion to that observed with free CDDP, but the drug concentration required to induce 50% inhibition of DNA synthesis for CDDP-liposomes (IC50: 0.7 micrograms CDDP/ml) was 1/3 of the IC50 for free CDDP (2.0 micrograms CDDP/ml). In support of the marked growth-inhibitory action of CDDP-liposomes, the intracellular incorporation rate of CDDP-liposomes was 3-fold higher when liposomes were used as carriers than when free CDDP was directly applied. CDDP-liposomes showed a stronger growth inhibition on IMR-32 cells at a high cell density than at a low density in culture. CDDP-liposomes were rapidly incorporated by IMR-32 cells within 5 min, resulting in the inhibition of DNA synthesis to 40% of the control. Swiss albino mouse 3T3 cells were less inhibited by CDDP-liposomes than by free CDDP, suggesting that encapsulation of CDDP in liposomes decreases cytotoxicity to normal cells.

Biological Transport↗
PubMed1989

Angiographic follow-up study of cerebral arteriovenous malformations with reference to their enlargement and regression.

Twenty patients with cerebral arteriovenous malformations (AVMs) were followed up by angiography. Of the 20 AVMs, 16 were nontreated and the remaining 4 were residual. The follow-up periods between the two examinations were from 5 to 28 years, with a median interval of 15 years. At follow-up, the size of the AVM had increased in 4 patients (20%), decreased in 4 (20%), totally regressed in 4 (20%), and was unchanged in 8 (40%). In cases of enlarged AVMs, the patients were all young: from 0 to 11 years old at first angiography and from 6 to 30 at second angiography. The decrease or total regression of the AVM occurred in older patients (over 30 years old at second angiography), and the AVMs were relatively small and fed by single or a few feeders. The patient's age and the size of AVM should be considered when operative indications are discussed.

Adolescent↗
PubMed1989

Intracranial extradural pressure monitoring after direct operation on ruptured cerebral aneurysms.

Intracranial extradural pressure (ICP) was monitored by using a miniaturized transducer for an average period of 8 days after direct operation in 55 patients with ruptured cerebral aneurysms. Acute stage operation and drainage of cerebrospinal fluid were simultaneously performed in most of the patients. In many grade I patients with satisfactory cisternal drainage, ICP was monotonously stable, with faint pressure waves. When the drained fluid volume decreased or drainage was removed, however, ICP was elevated moderately, with associated pressure waves present. There were no A-waves observed in any of the patients. Decreases of mean ICP and disappearance of pressure waves were found 2 to 3 hours after infusion of 200 or 300 ml of 10% glycerol or 20% mannitol in patients without drainage or with an inadequate drain, but were not found in patients with a good drain. In a patient showing diffuse severe vasospasm, a rapid elevation of ICP caused by marked brain edema was observed. In patients with residual aneurysms or incompletely clipped aneurysms, ICP increased immediately after rupture of these aneurysms. The daily mean ICP was higher in patients with a clinically poor condition and/or severe subarachnoid hemorrhage on admission than in those with a good condition and/or mild subarachnoid hemorrhage, in spite of a functional drain. There was a poor outcome in about half of the patients showing maximum daily mean ICP greater than 30 mm Hg or frequent B-waves. No complications caused by ICP monitoring were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Symptomatic Rathke's cleft cyst simulating arachnoid cyst--case report.

A case of symptomatic Rathke's cleft cyst simulating an arachnoid cyst is presented. Although computed tomography and magnetic resonance imaging showed that the cyst content was identical to cerebrospinal fluid, there was faint contrast enhancement in part of the wall. Histological observation suggested that the somewhat vascular connective tissue associated with nests of pituitary cells might have contributed to the enhancement. This type of Rathke's cleft cyst requires further clinical and neuroradiological studies.

Arachnoid↗
PubMed1989

[Reconstructive vascular surgery in the territory of the anterior cerebral artery in children with moyamoya disease].

The hemodynamics of the anterior cerebral arteries (ACAs) were studied in 28 children with moyamoya disease. In 39% of 56 cerebral hemispheres, antegrade filling of the ACAs was not verified by preoperative angiography. On the other hand, adequate collateral pathways to the ACA territory were generally not achieved by encephalomyosynangiosis (EMS) or superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis. The authors have devised new surgical methods for the revascularization of the ACA territory, which they term "encephaloarteriosynangiosis" (EAS) and "encephalogaleosynangiosis" (EGS). In these procedures, one or several burr holes are made in the frontal skull, the dura mater is incised, and either the frontal branch of the STA or the pedicled galea aponeurotica stump is placed on the surface of the frontal cortex. In addition to EMS or STA-MCA anastomosis, these methods were applied to 23 cerebral hemispheres in 14 pediatric patients. In 14 cerebral hemispheres (61%) of 10 patients, postoperative external carotid angiograms showed some cortical branches in the ACA territory, and clinical improvement was achieved in patients with transient ischemic attacks affecting the lower extremities. The results of this study demonstrate that EAS and EGS are simple and useful techniques for revascularization of the ACA territory. In addition, EGS can be applied to the territory of the posterior cerebral artery.

Adolescent↗
PubMed1989

Bilateral lenticulostriate arteriovenous malformations--case report.

A 6-year-old male with bilateral lenticulostriate arteriovenous malformations (AVMs) had suffered an intraventricular hemorrhage at the age of 10 days. Transfemoral cerebral angiography performed 6 years later revealed bilateral AVMs at the basal ganglia accompanied by vascular anomalies. Both AVMs appeared inoperable, and were treated conservatively. Bilateral, symmetrical cerebral AVMs are extremely rare, only three such cases having been reported.

Arteriovenous Malformations↗
PubMed1989

Tumor-infiltrating lymphocytes and histocompatibility antigens in primary intracranial germinomas.

Subpopulations of tumor-infiltrating lymphocytes (TIL's) and the major histocompatibility complex (MHC) antigens of neoplastic cells were examined in three intracranial germinomas by an immunohistochemical method using monoclonal antibodies. About 70% to 80% of TIL's were T lymphocytes which were either infiltrating diffusely or in clusters, whereas 20% to 30% of TIL's were B lymphocytes which tend to cluster in tumor tissues. Examination of T lymphocyte phenotypes revealed both the cytotoxic/suppressor and helper/inducer T lymphocytes, as in other tumors. However, the existence of a considerable number of B lymphocytes in the TIL population was uncommon and seemed to be a characteristic feature of the intracranial germinoma, which might suggest a difference of host immune response to this neoplasm as compared to other tumors. On examination of the MHC antigens, no MHC class I or II antigens in the neoplastic cells were stained, while positive staining for both antigens was seen in the TIL and stroma tissues. From these findings, it was suggested that the degree of TIL infiltration might not be correlated with the expression of MHC antigens in neoplastic cells in cases of primary intracranial germinoma.

Adolescent↗
PubMed1989

DNA synthesis, blood flow, and glucose utilization in experimental rat brain tumors.

The relationships between distribution of deoxyribonucleic acid (DNA)-synthesizing cells (S-phase cells) and blood flow and glucose utilization were investigated in rat brain tumors using an autoradiographic technique and immunoperoxidase staining for bromodeoxyuridine (BUdR). Two strains of rat brain tumor were used: strain A and B, both induced by the Rous sarcoma virus. Strain A was biologically more malignant than strain B. The blood flow was unevenly distributed in the tumor, compared with the contralateral cortex, the average blood flow in the tumor was about 50% in strain A and 60% in strain B. The distribution of blood flow did not correlate with the distribution of S-phase cells or with the distribution of vessels in the tumor in either strain A or B. The average glucose utilization in strain A was about 250% and in strain B about 170% of that of the contralateral cortex. The high glucose utilization area correlated well with the distribution of BUdR-positive nuclei in strain B. These findings suggest that the biological malignancy of a tumor correlates with glucose utilization rather than with blood flow, and that malignant brain tumors show a marked increase in glucose utilization for nucleic acid synthesis.

Animals↗
PubMed1989

Analysis of mixed lymphocyte-tumor culture in patients with malignant brain tumor.

To ascertain whether tumor-specific immune response occurs in patients with malignant brain tumors, lymphocyte blastogenetic responses to tumor cells were examined in 18 patients prior to operation and other treatment. Among 12 patients with malignant glioma, the peripheral blood lymphocytes (PBL's) showed a positive blastogenetic response to their own glioma cells in seven (58.3%), whereas the tumor-infiltrating lymphocytes (TIL's) showed a positive response in only three (25%). In four (66.7%) of six patients with metastatic brain tumors, however, both the PBL's and TIL's showed a positive blastogenetic response to their own tumor cells. In these four patients, this lymphocyte blastogenetic response to tumor cells were at a much lower level compared with phytohemagglutinin P or allogeneic lymphocyte stimulation. Furthermore, these responses were increased when the cells were cultured with interferon-gamma (500 U). Other lymphokines had no effect on the response. This method appears to be useful in identifying the tumor-specific immune response in patients with malignant brain tumor.

Adolescent↗