Search PubMed⌕ Search

Biomedical subjects

N Yamaguchi

Publications and source records attributed to N Yamaguchi.

At least 469 records · Page 26Linked to original sources
PubMed1992

Paradoxical enhancement of hypoperfusion single photon emission CT images in epileptic focus with bemegride activation. Observation from subtraction of 99mTc hexamethyl-propyleneamine oxime brain single photon emission CT images.

Changes of brain images in single photon emission CTs (SPECTs) before and after intravenous injection of bemegride were examined with simultaneous EEG recording in a patient with occipital lobe epilepsy and in a hysteric patient, using a new method, i.e. subtraction of the SPECT images with 99mTc hexamethyl-propyleneamine oxime. The bemegride injection in the epileptic patient paradoxically intensified the hypoperfusion images as epileptic foci in SPECTs, associated with enhanced interictal epileptic discharges, whereas the hysteric showed no such effects. These findings suggest that the hypoperfusion images closely correlate to the severity of epileptic activity, reflecting a functional rather than a morphological deficit.

Adult↗
PubMed1992

Serotonergic inhibition of limbic and thalamic seizures in cats.

To clarify the role of the serotonergic system in limbic and thalamic epileptic activity, we examined the effects of 5-hydroxytryptophan (5-HTP, 20 and 40 mg/kg) on fully kindled seizures from the hippocampus and lateral geniculate nucleus. The intraperitoneal administration of 20 mg/kg 5-HTP exerted no anticonvulsant effect on hippocampal kindled seizures, and a higher dose (40 mg/kg) produced a significant reduction in the behavioral seizure stage. 5-HTP at 20 mg/kg displayed no suppressive effect on lateral geniculate seizures, and 5-HTP at 40 mg/kg significantly reduced both the seizure stage and afterdischarge duration. Our data suggest that serotonergic mechanisms play an inhibitory role in seizures kindled from these brain regions.

5-Hydroxytryptophan↗
PubMed1992

The rabbit syndrome and antiparkinsonian medication in schizophrenic patients.

Effects of antiparkinsonian medication on the rabbit syndrome (RS) and accompanying parkinsonian symptoms were studied in 5 schizophrenic inpatients receiving long-term antipsychotic medication. All patients showed early improvement of RS following additional treatment with trihexyphenidyl or biperiden, with a significant reduction in the RS score also observed. The improvement of RS paralleled improvement of the parkinsonian symptoms, with the score of the Simpson-Angus rating scale significantly reduced. Our data provide further evidence that the underlying mechanism of RS is similar to that of acute forms of drug-induced parkinsonism.

Adult↗
PubMed1992

Acutely administered haloperidol-induced pattern changes of regional cerebral blood flow in schizophrenics. Observation from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime.

Changes in regional cerebral blood flow in brain images with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime before and after intramuscular injection of haloperidol (0.08 mg/kg) were studied in 5 medicated subjects in their twenties, consisting of 5 schizophrenics and 1 patient with histrionic personality disorder, by a subtraction method of brain images. The haloperidol injection induced two types of perfusion pattern change; in 2 of the schizophrenics, a relative hypoperfusion in the frontal lobes in the images prior to injection was converted to a relative hyperperfusion. In the other 3 schizophrenics and in the patient with histrionic personality disorder, the slight left hemispheric dominance was changed to a marked right hemispheric dominance. The results indicate that haloperidol affects perfusion patterns in schizophrenics.

Acute Disease↗
PubMed1992

Widespread reduction of regional cerebral blood flow during hyperventilation-induced EEG slowing ('buildup'). Observation from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime.

To study the pathophysiological mechanisms of hyperventilation-induced EEG showing, i.e., the so-called 'buildup' phenomenon, changes in regional cerebral blood flow (rCBF) were investigated before and during the phenomenon in a 16-year-old woman with headache, thought to be of neurotic origin, by subtraction technique of brain images with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime (99mTc-HMPAO). The tracer uptake during buildup decreased by 31-42% as compared to baseline values at rest before buildup in all of the measured regions, reflecting a widespread reduction in rCBF. Gas analyses of arterial blood collected during buildup showed a decrease in PaCO2, and increases in PaO2 and pH with a slight decrease in blood pressure and an increase in pulse rate. These results directly demonstrate a close correlation between the hyperventilation-induced EEG and rCBF changes, suggesting that the buildup phenomenon results from cerebral ischemic change, presumably due to cerebral vasoconstriction caused by the PaCO2 decrease.

Adolescent↗
PubMed1992

Action of the N-methyl-D-aspartate receptor antagonist MK-801 against focal seizure activity from the feline hippocampus.

This study assessed the effects of MK-801 (0.1 and 0.5 mg/kg), a noncompetitive antagonist of N-methyl-D-aspartate receptors, on focal seizure activity elicited by electrical stimulation to the feline hippocampus. Neither afterdischarge duration nor behavioral seizure stage was significantly suppressed following intraperitoneal administration of MK-801 at two dose. Rather, MK-801 at a higher dose induced hippocampal seizure status in some of the cats tested. The present data suggest convulsant properties of MK-801 and limitations of its clinical utility as an antiepileptic agent.

Animals↗
PubMed1992

Enhancement of the growth of human osteosarcoma cells by human interferon-gamma.

It is well known that interferons inhibit cell growth. However, we found that human interferon-gamma (HuIFN-gamma) enhanced the growth of human osteosarcoma cells, HOS-Y1 cells, in a dose-dependent manner. This enhancing effect was found only under the following conditions: when the cells were precultured for 2 or 3 days and then treated with HuIFN-gamma for 2, 3, or 4 days, and when the cells were seeded at a density of 1,000 or 2,000 cells/well. The degree of enhancement of cell growth was maximum when the cells were precultured at a density of 1,000 cells/well for 3 days and then treated with HuIFN-gamma for 2 days. The enhancing effect of HuIFN-gamma disappeared in the presence of anti-HuIFN-gamma antibody. In addition, it was found that the conditioned medium from HOS-Y1 cells enhanced the growth of HOS-Y1 cells, and that the conditioned medium from HOS-Y1 cells cultured with HuIFN-gamma enhanced the cell growth more than that from cells cultured without HuIFN-gamma. Epidermal growth factor (EGF), acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta 1(TGF-beta 1) did not enhance the growth of HOS-Y1 cells. These results suggest that HuIFN-gamma enhanced the cell growth by augmenting the production of unknown growth factor(s) in HOS-Y1 cells via an autocrine mechanism.

Antibodies, Monoclonal↗
PubMed1992

Detection of platelet-specific protein mRNAs in different megakaryoblasts using the reverse transcriptase polymerase chain reaction.

The short segments of cDNA encoding glycoprotein (GP)Ib alpha, GPIIb, GPIIIa and platelet factor (PF) 4 were amplified using reverse transcriptase-polymerase chain reaction (RT-PCR) in order to characterize various types of megakaryoblasts. Cell lines with megakaryocytic features (K562, CMK and HEL) were tested. GPIb alpha, GPIIb and GPIIIa mRNAs were found to be present in K562, CMK and HEL cells, while only HEL cells expressed PF4 or mRNA. These results suggested that megakaryoblastic cell lines could be categorized into two groups, one with the PF4 transcript and the other without it. PF4 mRNA was present in the cells obtained from one Down's syndrome patient with transient myeloproliferative disorder and in one patient with primary myelofibrosis and megakaryoblastosis. On the other hand, one patient with acute megakaryoblastic leukemia transformed from refractory anemia had a poor prognosis with megakaryoblastic leukemia cells which expressed no PF4 mRNA. These observations suggested that the expression of PF4 mRNA in peripheral blood megakaryoblasts may indicate the absence of a true leukemic process.

Aged↗
PubMed1992

Megakaryocytic leukemia and platelet factor 4.

The de novo megakaryocytic leukemia fulfilling the FAB criteria is still an uncommonly recognized variant of acute leukemia. Many studies have shown that the megakaryocytic leukemic events may occur at a pluripotent stem cell level and clinical observations reveal that the megakaryocytic leukemias are diverse entities. The immunophenotyping using monoclonal antibodies against platelet specific surface antigens and the ultrastructural detection of platelet peroxidase reaction do not provide sufficiently useful information to determine whether a megakaryocytic leukemia is chronic, acute, therapy-responsive or therapy-unresponsive. More sophisticated techniques are required to further characterize megakaryocytic leukemic cells. In this review, we emphasize that megakaryocytic leukemic cells can be categorized into two groups; one with the PF4 mRNA, and the other without it, and that the expression of PF4 mRNA in the blasts could be a useful marker for the identification of mature megakaryoblasts. It seems that the patients with blasts expressing PF4 mRNA will have a longer survival and a better response to chemotherapy than those without PF4. We further discuss the fact that the detection of mRNAs of the IL-6 receptor, PDGF A- and B-chains, and TGF beta 1 in megakaryocytic leukemic cells will be useful to clarify the mechanisms involved in the proliferation of megakaryocytic leukemic cells and fibroblasts in the bone marrow. Furthermore, we reviewed data showing that megakaryocytic erythroid, and mast cell lineages share the nuclear transcription factor known as GF-1 (NF-E1 or Erf-1). We suggest that characterization of megakaryocytic leukemia should be performed using monoclonal antibodies against erythroid, megakaryocytic and mast cell lineages.

Base Sequence↗
PubMed1992

Modulation of GM-CSF receptor beta-subunit and interleukin-6 receptor mRNA expression in a human megakaryocytic leukemia cell line.

Our present study was designed to clarify the mechanism by which the same megakaryocyte progenitor cells respond to various cytokines at different stages of megakaryocyte development. We examined the changes in mRNA expression of granulocyte macrophage colony-stimulating factor receptor beta-subunit (GM-CSFR beta-subunit), which was a common subunit of a high-affinity interleukin-3 receptor (IL-3R) and a high-affinity GM-CSFR, and interleukin-6 receptor (IL-6R) during megakaryocyte development in a human megakaryocytic leukemia cell line (CMK) which could proliferate and/or differentiate in the presence of 12-O-tetradecanoylphorbol 13-acetate (TPA), IL-3, GM-CSF, and IL-6. We found that GM-CSFR beta-subunit mRNA was expressed constitutively in CMK cells and was transiently down-regulated by TPA and IL-6, while the expression of IL-6R mRNA was increased by TPA in association with the differentiation of megakaryocytes. Furthermore, the TPA-induced down-regulation of GM-CSFR beta-subunit mRNA expression and its recovery were blocked by cycloheximide (CHX), a protein synthesis inhibitor, suggesting that these modulations required de novo protein synthesis. These findings imply that multi-lineage cytokines such as GM-CSF and IL-3 may contribute preferentially to the regulation of the earlier development of megakaryocyte progenitor cells with high densities of multi-lineage cytokine receptors, while IL-6 may be limited in its action to supporting the maturation of more differentiated megakaryocyte progenitor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Differentiation↗
PubMed1992

Gallyas-Schiff stain for senile plaques.

Gallyas technique was modified by a direct application of Schiff's reagent after physical development, resulting in distinctive staining of amyloid deposits in argyrophilic structures. With this modified method, senile plaques in Alzheimer's disease are clearer. This method is easy to perform and suitable for routine neuropathological examination.

Alzheimer Disease↗
PubMed1992

Machine perfusion of isolated kidney at 37 degrees C using pyridoxalated hemoglobin-polyoxyethylene (PHP) solution, UW solution and its combination.

To preserve isolated kidney normothermically, PHP containing UW components were evaluated as perfusates. Kidneys were flushed out by Lactate Ringer solution immediately after isolation from mongrel dogs, and then connected to the perfusion circuit which consists of a preservation box, a reservoir of perfusate, a membrane oxygenator and a drive unit. PHP containing 140 mEq/l of Na+ and 4 mEq/l of K+ (PHP(E)), UW solution (UW) and UW components added PHP(E) were prepared and adjusted at pH 7.4 prior to use. Temperature and perfusion pressure were controlled at 37 degrees C and 100 mmHg, respectively. During 12 hour perfusion, remarkable changes in pH were seen in UW group and PHP group while higher oxygen consumption was noted in PHP(E)+UW group than that in PHP(E) group. The histological findings showed moderate damages of tubular epithelial cells and maintaining normal glomerular structure in PHP(E)+UW while severe damage of both tubulus in UW group were seen. There was no edematous degeneration in both UW and PHP(E)+UW groups, however, it was seen in PHP(E) alone. It was suggested that components of UW solution have positive effect on normothermic machine perfusion with PHP(E) solution.

Adenosine↗
PubMed1992

[Serotonergic mechanisms in hippocampal kindled seizures--inhibitory effects of L-5-hydroxytryptophan and 8-hydroxy-2-(di-n-propylamino)tetralin].

Serotonin (5-HT) has been considered to possess an inhibitory action against the kindling development, but the role of 5-HT in kindled seizures is unclear. Furthermore, most previous studies have dealt with amygdaloid kindling. To clarify the role of the 5-HT system in epilepsy, we examined the effects of 5-hydroxytryptophan (5-HTP), a precursor which elevates brain 5-HT, and 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a 5-HT 1 a receptor agonist, on seizures kindled from the feline hippocampus (HIP). Following the completion of HIP kindling, five cats received 0.9% saline, 5-HTP (20 or 40 mg/kg, i.p.) or 8-OH-DPAT (0.1 or 1.0 mg/kg, i.v.). Drugs were administered 15 min (8-OH-DPAT) or 1 hr (5-HTP) prior to electrical stimulation at the generalized seizure triggering threshold, and the anticonvulsant effects were assessed by the behavioral seizure stage and afterdischarge (AD) duration. Both 5-HTP and 8-OH-DPAT suppressed dose-dependently HIP-kindled seizures. The administration of 5-HTP at 40 mg/kg and of 8-OH-DPAT at 1.0 mg/kg produced a marked or complete suppression of HIP-kindled seizures in most of the cats tested, and was found to significantly reduce the seizure stage when compared with the saline control. Both drugs tended to shorten the AD duration, but this effect did not reach statistically significant levels. The present data suggest that the 5-HT system plays an important role in HIP-kindled seizures, and that the 5-HT 1 a receptors have an inhibitory effect on the kindled focal epileptic activity of the HIP.

5-Hydroxytryptophan↗
PubMed1992

Development of a new method for detection of platelet factor 3 like activity.

We asked the question, "Can thalassemic erythrocytes play some role in alteration of the hemostatic system?", because clinical examination of thalassemic patients shows symptoms and signs related to alterations in hemostatic and circulatory systems, and thalassemic erythrocytes are different from normal erythrocytes. We obtained one of the answers to the question: The erythrocytes of postsplenectomized patients of beta-thalassemia/HbE disease could stimulate their own platelets to aggregate spontaneously. To know the role of erythrocytes in platelet aggregation, we wanted to examine the effect of thalassemic erythrocytes on the coagulation system by focusing of PF3-like activity of erythrocytes, because PF3-like activity of the ghosts of erythrocytes had been reported. For the study, we tried to develop a technique that was accurate and sensitive enough to detect PF3-like activity of blood. The system we developed was the following: 1) We activated the intrinsic coagulation pathway of commercial standard plasma by ellagic acid. 2) CaCl2, a fixed amount of PF 3 and synthetic thrombin inhibitor MD 805 were added to the reaction mixture. 3) At a fixed time, thrombin activity in the mixture was measured by using S-2238 as a substrate. At full activation of the contact system by ellagic acid, the amount of thrombin formed in a certain time depended on the amount of PF3-like substances such as cephalin, freeze-thawed platelets or ghosts of erythrocytes added to the test system, indicating that PF3-like activity of those substances can be measured by the activity of thrombin generated in a fixed time.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Tests↗
PubMed1992

Detection of PF3 availability in whole blood from volunteers and beta-thalassemia/HbE patients: a promising method for prediction of thrombotic tendency.

The platelet factor 3 (PF 3) plays a very important role in activation of coagulation factors and is regarded to be available during activation of platelets. However, membrane fraction of erythrocytes is also shown to have PF 3-like activity, suggesting that the abnormal erythrocytes may accelerate the activation of platelet by forming thrombin on their abnormal membrane or by way of other factors of the abnormal erythrocytes, and may increase the availability of PF 3 in whole blood (WB). To examine this hypothesis, we developed a method for determination of PF 3 activity, because the method now available for the PF3 determination could not detect changes in PF 3 activity with time. The principles of our method were as follows: 1) The reaction system was adjusted so that the amount of thrombin generated in a fixed reaction time correlates with the amount of PF 3. 2) To avoid inhibition of thrombin activity by antithrombin III, a synthetic thrombin inhibitor, MD 805, was added to the system and the activity of thrombin generated was measured by synthetic thrombin substrate S-2238 using A405 as an indicator of the availability of PF3. The results obtained by the method were the following: WB taken from volunteers showed A405 of 0.12 +/- 0.02 at 30 minutes after blood collection and then the A405 increased to 0.27 +/- 0.03 at 90 minutes. However, one volunteer showed the value of 0.59 at 90 minutes, though the value at 30 minutes was 0.16. The platelet number in his WB did not change during the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗