Search PubMed⌕ Search

Biomedical subjects

M Murakami

Publications and source records attributed to M Murakami.

At least 811 records · Page 45Linked to original sources
PubMed1993

[Role of Helicobacter pylori infection in gastric metaplasia in the duodenum in the production of duodenal ulcer].

Helicobacter pylori (H. pylori) is frequently detected in not only the antrum but also the gastric juice and the duodenum with gastric metaplasia, which is believed to be a response of duodenal mucosa to injury by hyperacidity, in most of duodenal ulcer patients. Conversely, the normal duodenum is not infected with H. pylori in non-duodenal ulcer patients, even if H. pylori is present in the antrum and/or the gastric juice. All patients with H. pylori in the duodenum has the H. pylori infection in the gastric antrum. Patients with H. pylori in the gastric juice also has H. pylori infection in the antrum. These findings may support the following hypothesis in the formation of duodenal ulcer. A high duodenal acid load leads to the formation of gastric metaplasia in the duodenal bulb, where can be easily infected by gastric H. pylori through the gastric juice. As a result of the duodenal colonization of H. pylori, the duodenal mucosa impaired by ammonia of H. pylori could has the formation of duodenal ulcer.

Duodenal Ulcer↗
PubMed1993

[The EEG background activity in children with epilepsy--effects of the removal of anticonvulsants on the EEG].

The development of the EEG background activity is generally impaired in children with epilepsy. Antiepileptic drugs (AEDs) are one of the important factor which influence the EEG background activity. We studied the effect of AEDs on the EEG. Subjects were 46 normal children and 48 children with epilepsy aged 5 to 15, who had not any organic brain damage and showed normal psychomotor development. Forty children with epilepsy (CBZ; 30 cases, VPA; 10 cases) had been on monopharmacy and 8 cases on polypharmacy. All of them have outgrown their epilepsy. The serial EEGs were recorded during withdrawal and after discontinuation of AED in each patient. These records were evaluated using computerized power spectral analysis. CBZ reduction associated with a decrease in delta and theta powers and an increase in alpha-2 power, which were also observed at VPA reduction in concomitant AEDs (VPA+CBZ). No parameter changed by VPA reduction in monopharmacy. The slowing of the EEG background activity was noticed even after discontinuation of CBZ. It required more time after discontinuation of CBZ in younger children than older before the EEG background activity became normal controls. These findings suggested that CBZ had a adverse effect, which was more remarkable in younger children than older children, on the development of EEG background activity and that the effect of CBZ on EEG was different from that of VPA.

Adolescent↗
PubMed1993

[Anaesthetic management of pediatric renal transplantation for chronic renal failure].

We evaluated the preoperative and intraoperative general condition of 33 pediatric kidney recipients. Eighteen patients were anaesthetized with lumbar epidural anaesthesia. Ten patients were with nitrous oxide-oxygen-halothane, 5 cases were with NLA. Preoperatively many children had cardiovascular and metabolic complications. For example 39% of patients had history of hypertension. Sixty-seven percent of patients were found to have cardiomegaly (cardio-thoracic ratio > 50%) with chest X-ray film. Seven of 9 patients undergoing echocardiogram had abnormality of cardiac wall motion, valvular impairment, pericardial effusion. In forty-eight percent of patients, hyperlipidemia was found. During operation we could not maintain the cardiovascular stability following intratracheal intubation and manipulation of vena cava or abdominal aorta under NLA or nitrous oxide-oxygen-halothane anesthesia. Epidural analgesia inhibited the cardiovascular fluctuation following these surgical stresses. We concluded that epidural analgesia is the best anaesthesia for pediatric renal transplantation and phentolamine or PGE1 are useful to maintain cardiovascular stability and transplanted kidney function.

Adolescent↗
PubMed1993

[A technique for a rapid imaging of regional CBF and partition coefficient using dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine (123I-IMP)].

IMP is a flow tracer due to a large first pass extraction fraction and high affinity in the brain, but significant clearance from the brain causes change of distribution when the scan start time is delayed. The purpose of the present study is to develop a new method to rapidly calculate a quantitative CBF image by taking into account for the clearance effects. A dynamic SPECT scan was performed on 5 subjects (4 patients with cerebral infarction and 1 normal volunteer) following slow intravenous infusion of 123I-IMP. The arterial input function was obtained by frequent blood sampling and by measuring an octanol extraction ratio for each sample. Firstly, non-linear least square fitting (NLS) was performed to investigate the tracer kinetics of 123I-IMP. The 3 compartment model analysis yielded negligibly small k3 (retaining rate constant) (0.0056 +/- 0.0128 (ml/ml/min)), and consistent k1 (transport rate constant) with those determined by 2 compartment model (2CM) analysis (r = 0.96, p < 0.001). In addition, k1 was consistent with CBF measured by 15O water PET technique. These observations suggested validity of using 2CM for describing the IMP tracer kinetics. Secondly, a weighted integration (WI) technique has been implemented to calculate rapidly images of CBF and partition coefficient (Vd). The WI technique yielded values of CBF (k1) and Vd (k1/k2). They were confirmed to be consistent with those determined by NLS technique (CBF; r = 0.99, p < 0.001, Vd; r = 0.99, p < 0.001), and calculated k1 agreed well with PET CBF (r = 0.91, p < 0.001). We observed changed Vd in infarcted patients. This supports an importance for calculating of Vd image. Vd image will provide additional clinical information because 123I-IMP binding mechanism may be related to cell viability.

Adult↗
PubMed1993

[Development of the background activity of EEG in children with epilepsy; comparison with normal children].

We investigated the development of the background activity of EEGs in 150 children with epilepsy by means of computerized power spectral analysis, using Fourier transformation by O1 Twenty-seven cases with idiopathic generalized epilepsy (IGE), 30 cases with idiopathic partial epilepsy (IPE), 60 cases with symptomatic partial epilepsy (SPE), 33 cases with cryptogenic partial epilepsy (CPE) and 48 normal children were studied. The records with paroxysmal activity at 01 were excluded in this study. In normal children, total, delta and theta powers showed a significant inverse correlation with age, but alpha-2 and beta-2 powers showed a significant positive correlation with age. In children with epilepsy, there were significant increases of delta and theta powers and a decrease of alpha-2 power compared with normal children. The development of the EEGs was different among the patients with various types of the epileptic syndrome. It was suggested that age, prognosis and anticonvulsants were important factors which influence the EEGs background activity.

Adolescent↗
PubMed1993

[Factors affecting P300 latencies in epileptic children].

Auditory event-related potentials (ERPs) were recorded from 131 epileptic children of 4 to 20 years of age, and the related factors affecting P300 latencies were evaluated using multiple regression analysis. The examined factors were as follows: (1) age at P300 recording and duration of illness, (2) seizure types and epileptic syndromes, (3) anti-epileptic drugs (AEDs), (4) seizure prognosis, (5) organic brain dysfunctions, (6) x-ray CT and (7) EEG background activity and frequency of paroxysms. ERPs were elicited with the oddball paradigm. Five factors of them had significant correlations with P300 latencies. 1) P300 latencies were gradually shortened with age. 2) P300 latencies were prolonged in the patients before and during AED medication compared with those during the period of off-therapy. 3) Symptomatic partial epilepsy showed obviously prolonged P300 latencies. 4) P300 latencies were shortened with increasing alpha 2 power of EEG. 5) P300 latencies became prolonged with the length of illness.

Adolescent↗
PubMed1993

[A case of spontaneous spinal epidural hematoma].

A 14-month-old girl with spontaneous spinal epidural hematoma and complete postoperative recovery was described. MRI proved to be a sensitive tool in identifying the nature and extent of this lesion. A review of literature was made with particular emphasis on the pediatric age group.

Age Factors↗
PubMed1992

[MR imaging of bone metastasis].

One hundred and three patients with known malignancy and suspected bone metastasis underwent magnetic resonance imaging. In 93%, the metastatic lesions, detected both on plain films and radionuclide bone scans, showed decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images. All lesions, except one lesion showing much blastic change on plain films, showed contrast enhancement with Gd-DTPA administration. Although further investigation is needed, a correlation between the type of primary malignancy and the signal intensity of the metastatic lesion is suggested. Among 312 metastatic lesions detected by MR imaging, 272 lesions (87%) and 134 lesions (40%) were also detected by radionuclide bone scans and plain films, respectively. In five cases, MR imaging clearly revealed the lesion compressing the spinal cord, which helped us formulate a therapeutic plan. We conclude that MR imaging is the most sensitive examination for detecting bone metastasis and is necessary for planning treatment.

Bone Neoplasms↗
PubMed1992

Release of 14-kDa group-II phospholipase A2 from activated mast cells and its possible involvement in the regulation of the degranulation process.

Group II phospholipase A2 was detected in appreciable amounts in rat peritoneal mast cells. The effect of several inhibitors specific to 14-kDa group-II phospholipase A2, including two proteinaceous inhibitors and a product of microorganisms with a low molecular mass, on mast-cell activation was examined. When rat peritoneal mast cells were sensitized with IgE and then challenged with antigen, the specific phospholipase-A2 inhibitors suppressed histamine release in a concentration-dependent manner. By contrast, these inhibitors showed no effect on prostaglandin generation under the same conditions. Histamine release from rat peritoneal mast cells subjected to non-immunochemical stimuli, such as concanavalin A, the Ca2+ ionophore A23187, compound 48/80 and substance P was also suppressed. When rat peritoneal mast cells were treated with 14-kDa-group-II-phospholipase-A2-specific inhibitors, washed and stimulated, histamine release was not affected appreciably. Similar suppressive effects of the inhibitors on histamine release were observed with mouse cultured bone-marrow-derived mast cells. When bone-marrow-derived mast cells were activated, they secreted both a soluble and an ecto-enzyme form of 14-kDa group-II phospholipase A2, although appearance of the enzyme associated with the external surface of cells was observed transiently. An appreciable amount of membrane phospholipids was degraded during activation of mast cells, which was decreased by treatment with 14-kDa-group-II-phospholipase-A2 inhibitor. These observations suggest that degranulation and eicosanoid generation in mast cells are regulated independently by discrete phospholipases A2 and that the 14-kDa group-II phospholipase A2 released from mast cells during activation may play an essential role in the progression of the degranulation process.

Animals↗
PubMed1992

Interleukin-6 signal transducer gp130 mediates oncostatin M signaling.

Oncostatin M (OM) is a multifunctional cytokine that is structurally and functionally related to interleukin 6 (IL-6) and leukemia inhibitory factor (LIF). The specific receptor for OM has been demonstrated (by chemical cross-linking) to be a 150-kDa protein in a number of cell lines. The IL-6 signal transducer, gp130, is also an affinity converter for the LIF receptor. It does not bind to either IL-6 or LIF, but associates with the alpha subunits of the receptors and transduces the signals. We examined the possible involvement of gp130 in OM binding and signaling. We demonstrate that: (a) anti-gp130 monoclonal antibodies (mAbs) block the inhibitory effect of OM on A375 cell growth, (b) the binding and cross-linking of 125I-OM to H2981 cells are completely abolished by anti-gp130 mAbs, (c) the cross-linked OM-receptor complex is immunoprecipitated by anti-gp130 mAbs, and (d) COS-7 cells transfected with the full-length cDNA encoding gp130 exhibit increased OM binding and cross-linking, which are also blocked by anti-gp130 mAbs. Therefore, we conclude that the 150-kDa OM binding protein previously characterized in a variety of cell lines is gp130. OM is the natural ligand for gp130 and gp130 mediates the biological responses of OM.

Animals↗
PubMed1992

[Effect of Ca(2+)-channel antagonists on the corticoidogenesis in primary cultured bovine adrenocortical cells].

We investigated the effect of Ca(2+)-channel antagonists, Nicardipine(N), Verapamil(V) and Flunarizine(F), on the corticoidogenesis(CG) in primary cultured bovine adrenocortical cells. To examine the effect on receptor operated Ca(2+)-channel(ROC) and voltage operated Ca(2+)-channel(VOC), involved in corticoid synthesis, adrenocorticotropic hormone(ACTH) and high-K+ were used respectively. With or without the antagonists, cells were incubated at 37 degrees C for 1h in the presence of ACTH (100pM) or K+ (30mM). Corticoid was measured fluorometrically using cortisol as the standard. N and V inhibited not only ACTH-induced CG, but high K(+)-induced CG in a concentration-dependent manner. However, F inhibited only high K(+)-induced CG, and did not affect ACTH-induced CG. These inhibitions were observed at the low micromolar concentrations (below 40 microM) of the antagonists. In the regulation of corticoid synthesis, we indicate that F has an inhibitory effect on VOC without ROC; on the other hand, N and V inhibit both ROC and VOC.

Adrenal Cortex↗
PubMed1992

Characterization of human thyrotropin receptor-related peptide-like immunoreactivity in peripheral blood of Graves' disease.

An antiserum raised against an alignment of amino acid-(32-56), termed TSHRP-1, in the extracellular domain of human thyrotropin (TSH) receptor was used to identify the TSH receptor-like substance in plasma of Graves' disease. The dilution curve of plasma TSHRP-1-like immunoreactivity was observed in a manner parallel to the standard synthetic peptide curve in radioimmunoassay, and its molecular weight estimated approximately 60 kDa. The amounts of TSHRP-1-like immunoreactivity were significantly higher in Graves' plasma than those in plasma of normal and hypothyroid patients due to Hashimoto's thyroiditis. The present results indicate that human peripheral blood possesses a soluble form of the extracellular domain of TSH receptor which may contribute to the pathophysiology of Graves' disease.

Biomarkers↗
PubMed1992

Further mechanistic study on intestinal absorption enhanced by unsaturated fatty acids: reversible effect by sulfhydryl modification.

In order to study the relationship between the sulfhydryl (SH) modification of membrane-associated proteins and the oleic acid-induced permeability enhancement of the colonic mucosa, in vitro and in situ absorption studies were performed using rat colon and carboxyfluorescein as an impermeable dye. The pretreatment of the mucosa with diamide, a bifunctional sulfhydryl modifier, in in vitro experiments with the everted colonic loops reduced the absorption enhancing effect of oleic acid in a concentration-dependent manner, less inhibitory effect, though just a little, was observed as compared to N-ethylmaleimide. The inhibition caused by the addition of diamide was absolutely restored by exposure of the mucosa to dithiothreitol. On the other hand, these SH modifiers showed no pronounced effect on the in vivo permeability of quinine which is well-known to be absorbed by a passive transport system mainly via the membrane lipid bilayer. These results obtained in the present study have identified an important role of the functional SH groups of membrane proteins on modulating the permeability alteration of the mucosal epithelium provoked by oleic acid. Furthermore, the SH proteins have been revealed as being unimportant in the intestinal absorption of lipoid-soluble compounds.

Animals↗
PubMed1992

Antigen-induced apoptotic death of Ly-1 B cells responsible for autoimmune disease in transgenic mice.

Studies on transgenic mice expressing immunoglobulins against self-antigens have shown that self-tolerance is maintained by active elimination (clonal deletion), functional inactivation (clonal anergy) of self-reactive B cells, or a combination of both. We have established and characterized a transgenic mouse line expressing an anti-erythrocyte autoantibody. In contrast to other autoantibody transgenic lines, about 50% of the animals of this transgenic line suffer from autoimmune disease, indicating a loss of self-tolerance. Here we show that peritoneal Ly-1 B cells (also known as B-1 cells) are responsible for this autoimmune disease in our transgenic mice. A few self-reactive Ly-1 B cells that have somehow escaped the deletion mechanism expand in the peritoneum because of the absence of self-antigen. These Ly-1 B cells are eliminated in vivo by apoptosis once exposed to self-antigen. On the basis of these results we propose a novel autoantibody production mechanism whereby self-reactive B cells sequestered in compartments free of self-antigens may survive, proliferate and be activated for generation of pathogenic autoantibodies in autoimmune diseases.

Anemia, Hemolytic, Autoimmune↗
PubMed1992

Differential regulation of thyrotropin-releasing hormone receptor mRNA levels by thyroid hormone in vivo and in vitro (GH3 cells).

We studied the effect of thyroid status on thyrotropin-releasing hormone receptor (TRH-R) mRNA levels both in vivo and in vitro (GH3 cells) using a cloned rat TRH-R cDNA by RT-PCR. Experimental hypothyroid rats were produced by total thyroidectomy and were then killed 7 days after the operation. TRH receptor binding in the anterior pituitary and serum TSH level were elevated approximately 2-fold and 8-fold, respectively, in 7 day thyroidectomized rats. TRH-R mRNA levels in hypothyroid rats were also increased significantly compared with those of normal rats. In GH3 cells, however, no significant change of TRH-R mRNA level was observed between cultures treated with triiodothyronine (T3, 10(-9) and 10(-7) M) and the untreated group. The present data indicate that 1) the in vivo effects of thyroid status on TRH-R mRNA levels differ from the in vitro one, and that 2) the down regulation of TRH-R binding by thyroid hormone in GH3 cells may be mediated by translational or post-translational mechanisms.

Amino Acid Sequence↗