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Biomedical subjects

R Shimokawa

Publications and source records attributed to R Shimokawa.

At least 19 recordsLinked to original sources
PubMed2002

Hypergravity modulates behavioral nociceptive responses in rats.

Hypergravity (2G) exposure elevated the nociceptive threshold (pain suppression) concomitantly with evoked neuronal activity in the hypothalamus. Young Wistar male rats were exposed to 2G by centrifugal rotation for 10 min. Before and after 2G exposure, the nociceptive threshold was measured as the withdrawal reflex by using the von Frey type needle at a total of 8 sites of each rat (nose, four quarters, upper and lower back, tail), and then rats were sacrificed. Fos expression was examined immunohistochemically in the hypothalamic slices of the 2G-treated rats. When rats were exposed to 2G hypergravity, the nociceptive threshold was significantly elevated to approximately 150 to 250% of the 1G baseline control levels in all the examination sites. The 2G hypergravity remarkably induced Fos expression in the paraventricular and arcuate nuclei of the hypothalamus. The analgesic effects of 2G hypergravity were attenuated by naloxone pretreatment. Data indicate that hypergravity induces analgesic effects in rats, mediated through hypothalamic neuronal activity in the endogenous opioid system and hypothalamo-pituitary-adrenal axis.

Animals↗
PubMed2001

Atypical form of dural graft associated Creutzfeldt-Jakob disease: report of a postmortem case with review of the literature.

A postmortem case of an atypical form of dural graft associated Creutzfeldt-Jakob disease (CJD) is described. A 42 year old man developed progressive spastic paresis 163 months after a cadaveric dura mater graft. He presented with no myoclonus and very late occurrence of periodic synchronous discharges on EEG. The prion protein (PrP) gene was homozygous for methionine at the polymorphic codon 129. Neuropathological examination disclosed plaque-like PrP deposits with atypical distribution of synaptic PrP accumulations in the brain. This patient represents an atypical form of dural graft associated CJD characterised by unusual clinicopathological features.

Adult↗
PubMed2001

Hypergravity and opioid-mediated pain suppression in rats.

It is known that pain suppression in animals is induced by certain environmental stimulus. However, little is known about the effects of gravitational alteration on the nociceptive responses in rats. A recent study indicated that Fos protein expression was strongly induced in the vestibular-related brainstem regions of rats that were exposed to 2 G hypergravity (Gustave Dit Duflo et al., 2000). A number of studies indicate that Fos expression is induced in the brain by various kinds of stress. We showed that either long-term exposure or short-term exposure to 2 G hypergravity elevated the nociceptive threshold in the rat skin surfaces, in concomitant with Fos induction in the hypothalamus including the arcuate nucleus and paraventricular nucleus (Kumei et al., 2000). We have examined the possible involvement of beta-endorphin, an endogenous opioid, in the hypergravity-induced analgesic effects on rats and its counteraction by naloxone, an opioid receptor antagonist.

Animals↗
PubMed2000

Nociceptive responses and immunohistochemical changes in the rat brain under gravity stress.

It is well known that exposure to various stresses leads to pain suppression in animals. However, there is no report about the effects of gravitational alteration to serve as a kind of stress. The purpose of the present study is to clarify the effect of hypergravity (2 G) on the nociceptive responses and histochemical changes in rats. We examined the level of the threshold of withdrawal reflex against the noxious [correction of noxicious] stimulation in rats that were exposed to 2 G. Data show that the 2 G exposure elevates the nociceptive threshold. We have demonstrated for the first time that gravity change induces analgesic effects on rats in concomitant with c-fos induction in the arcuate, and paraventricular nuclei of rat hypothalamus. Gravity change acts as a kind of stress in rats.

Analgesia↗
PubMed1997

Inhibition of fructose-6-phosphate,2-kinase by N-bromoacetylethanolamine phosphate in vitro and in vivo.

Fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase (Fru-6-P,2-kinase/Fru-2,6-BPase), a bifunctional enzyme, catalyzes the synthesis and degradation of a potent activator, fructose-2,6-bisphosphate (Fru-2,6-P2), of phosphofructokinase, and has been postulated to be an important enzyme in the regulation of glycolysis in mammalian tissues. The purpose of this study was to determine whether or not N-bromoacetylethanolamine phosphate (BrAcNHEtOP), a specific active site-directed inactivator of Fru-6-P,2-kinase, is useful for studies on the role of Fru-6-P,2-kinase in the regulation of glycolysis in vivo. BrAcNHEtOP inactivated purified recombinant rat testis-type Fru-6-P,2-kinase as well as Fru-6-P,2-kinase in a rat liver extract, with half maximum inactivation concentrations of 2 and 15 mM, respectively, on 30 min incubation at 30 degrees C. The increases in Fru-6-P,2-kinase activity and the Fru-2,6-P2 concentration in livers, prepared from fasted rats, induced by high glucose (50 mM) perfusion were suppressed in parallel after pre-perfusion with 1 to 10 mM BrAcNHEtOP, dose-dependently. Five hours after intraperitoneal injection of BrAcNHEtOP (50 to 150 mg/kg) into mice, the Fru-6-P,2-kinase activity and Fru-2,6-P2 concentration in livers had decreased in parallel, dose-dependently. These effects continued for 24 h and were accompanied by decreases in the fructose-1,6-bisphosphate, triose phosphates, and lactate contents, although the contents of glucose-6-phosphate and fructose-6-phosphate did not change. These results suggested that BrAcNHEtOP inactivates Fru-6-P, 2-kinase, resulting in a decrease in the Fru-2,6-P2 level, which causes inactivation of phosphofructokinase and consequently inhibition of glycolysis in liver. Furthermore, the suppressed levels of Fru-6-P,2-kinase activity and metabolites in mice livers were sustained by daily injection of BrAcNHEtOP for 4 days, and body weight gain was also suppressed during the administration of BrAcNHEtOP. These results suggested that BrAcNHEtOP will be a useful reagent for studying the role of Fru-6-P,2-kinase in vivo.

Animals↗
PubMed1992

Primary cutaneous plasmacytoma: treatment with intralesional tumour necrosis factor-alpha.

We report a case of primary multiple cutaneous plasmacytomas, without underlying multiple myeloma, treated with intralesional tumour necrosis factor-alpha (TNF-alpha). A marked reduction in tumour size, with no significant adverse effects, suggests that intralesional TNF-alpha is an effective treatment for non-solid malignant tumours. Extramedullary plasmacytoma, especially involving the skin as a primary site, has rarely been reported in the English literature. We describe the ninth reported case of multiple cutaneous plasmacytomas without underlying multiple myeloma. Intralesional tumour necrosis factor-alpha (TNF-alpha) was used to treat this disease and its anti-tumour effect quantitatively evaluated by comparing the tumour size and histological change before and after treatment.

Aged↗
PubMed1990

Experimental neurotoxicity of 5-fluorouracil and its derivatives is due to poisoning by the monofluorinated organic metabolites, monofluoroacetic acid and alpha-fluoro-beta-alanine.

Two metabolites of 5-fluorouracil (FU), monofluoroacetic acid (FA) and alpha-fluoro-beta-alanine (FBAL), were continuously administered into the left ventricle of the brain in cats for up to 1 month to investigate the mechanism of neurotoxicity of FU and its derivatives. The cumulative doses of FU and FBAL over a 1-month period were 1.5-45 mg (20 cats) and 0.2-4.8 mg (21 cats), respectively. As controls for each experimental group, acetic acid (AA) and beta-alanine (BAL) were administered. In terms of survival time in relation to the cumulative dose and molecular weight, FBAL was more toxic than FA. Neuropathologically, two types of change, vacuoles and necrosis/softening-like change, were found. The vacuoles were 20-50 microns in diameter, and distributed mainly in the cerebellar nuclei, white matter and the tectum and tegmentum of the brain stem in both experimental groups. Electron microscopically, these vacuoles were due to splitting of the myelin intraperiod line or separation between the axon and the innermost layer of myelin. Necrosis/softening-like change occurred preferentially in the FBAL group and was located symmetrically in the superior and inferior colliculi, oculomotor nuclei and thalamus. Both types of neuropathological change, especially those in the FBAL group, were similar to those found in cats orally administered with FU and its derivatives.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Extensive cerebral infarction due to involvement of both anterior cerebral arteries by Wegener's granulomatosis.

The central nervous system is often affected in Wegener's granulomatosis (WG), but massive cerebral infarction due to occlusion of branches of the anterior cerebral arteries (ACA) by granulomatous lesions or thrombosis, or both, has seldom been reported. A case is reported here of a 67 year old man with WG complicated by generalised necrotising vasculitis in the lung, kidney, and gastrointestinal tract, and cerebral infarction in the territory of both anterior cerebral arteries, probably caused by thrombosis and a contiguous invasion of granulomatous lesion from the nasal cavity.

Aged↗
PubMed1983

Pemphigus vulgaris involving the mouth and esophagus. Report of a case and review of the literature.

A case of pemphigus vulgaris involving the mouth and esophagus is presented. Cases of pemphigus vulgaris involving the esophagus in the literature are reviewed; the initial symptom in all cases is in the oral cavity. Although the mortality rate for pemphigus vulgaris involving the esophagus is relatively high, the present case was managed successfully by active therapy with steroids.

Adult↗
PubMed1982

Mucoepidermoid carcinoma of the thymic region.

A case of mucoepidermoid carcinoma in thymus in a 59-year-old Japanese female is presented. She died of cardiac tamponade due to tumor invasion ater a 5 years' clinical course. At autopsy the main tumor was found in the thymic region with metastases to the sternum, regional lymph nodes, pericardial, and left pleural cavity. The mucoepidermoid carcinoma might be probably originated from a hen's egg-sized cyst which was located in the upper posterior aspect of the tumor-involved thymus. No teratomatous components were present. The cyst was most likely to be of thymic or bronchogenic cyst origin, though it was not determined, in view of the lining with pseudostratified ciliated columnar epithelium of the cystic wall and the surrounding with the thymic tissue outside. Moreover, there was thymic hyperplasia with germinal center that was compatible with SLE-like symptoms in her past history and autoimmune nature of the autopsy findings of pulmonary fibrosis.

Carcinoma↗
PubMed1977

An enzyme histochemical study of non-Hodgkin's lymphoma and allied disease.

The enzyme activity for alpha-naphthyl-acetate esterase, naphthol-AS-acetate esterase, naphthol-AS-D-chloroacetate esterase, acid phosphatase, L(+)-tartrate-resistant acid phosphatase, adenosine triphosphatase, and 5'-nucleotidase was examined on the neoplastic cells of giant follicular lymphoblastoma, the so-called reticulum cell sarcoma and Sézary syndrome. The neoplastic cells of giant follicular lymphoblastoma showed distinct activity for adenosine triphosphatase and 5'-nucleotidase, and those of the so-called reticulum cell sarcoma had no characteristic nature of the reticulum cells or histiocytes enzyme histochemically. These findings suggest that these neoplastic cells may be derived from the B-cell system. In Sézary syndrome, acid phosphatase activity was localized in a small paranuclear area in Sézary cells, which were considered to have a T-cell nature. It is thought that these enzyme histochemical methods are easy and useful in differentiating the B- or T-cell nature and the classification of non-Hodgkin's lymphomas.

Acid Phosphatase↗