Biomedical subjects

Y Tanabe

Publications and source records attributed to Y Tanabe.

At least 127 records · Page 7Linked to original sources

PubMed1997

Specific attenuation of the pressure-induced contraction of rat cerebral artery by herbimycin A.

In order to determine whether protein tyrosine kinase mechanisms are involved in pressure-induced contraction, we compared effects of three structurally unrelated tyrosine kinase inhibitors and orthovanadate, a tyrosine phosphatase inhibitor, on the pressure-induced contraction of the posterior cerebral artery isolated from rats. The change in vessel diameter was continuously measured with a width analyzer. Herbimycin A inhibited the pressure-induced contraction, while it only slightly inhibited contractions produced by potassium chloride or 9,11-dideoxy-11alpha,9alpha-epoxymethano prostaglandin F2alpha (U46619). Genistein inhibited not only the pressure-induced contraction but also the U46619-induced one. Tyrphostin 23 significantly attenuated contractions in response to three different stimuli, i.e., pressure, potassium chloride and U46619. Orthovanadate potentiated the pressure-induced contraction. These results suggest that herbimycin A is a specific and potent inhibitor of the pressure-induced contraction and that a protein tyrosine kinase mechanism may play an important role in the genesis of the pressure-induced contraction of the rat cerebral artery.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1997

The effects of transmural pressure on prostacyclin release from porcine endocardial endothelial cells--comparison with vascular endothelial cells.

We assessed the effect of pressure on the release of prostacyclin (PGI2) from cultured endocardial endothelial cells (EECs) and vascular endothelial cells (VECs). EECs were harvested from the right ventricle (RV) and left ventricle (LV) of porcine hearts, and VECs from pulmonary artery (PA), aorta (Ao) and coronary artery (CA). Confluent EECs and VECs were incubated for 30 min under various pressures (0, 50, 100, 150 mmHg) and PGI2 release from each cell was measured. Pressure-induced PGI2 release from LV-EECs was larger than that from RV-EECs. Pressure also increased PGI2 release from both PA- and Ao-VECs, but not from CA-VECs. These findings suggest that endocardium can produce PGI2 in response to pressure and PGI2 released into the coronary blood from the ventricle may play an important role in the prevention of myocardial ischemia.

Animals↗

PubMed1997

Dichloroacetate treatment in Leigh syndrome caused by mitochondrial DNA mutation.

Sodium dichloroacetate (DCA) was administered to a 1-year-old female case of Leigh syndrome, who had a T > G point mutation at nt 8993 of mitochondrial DNA. Her biochemical and clinical symptoms improved gradually, but proton magnetic resonance spectroscopy revealed reduction of the N-acetylaspartate/creatine ratio, and magnetic resonance imaging showed progressive cerebral atrophy despite the DCA therapy. These results suggest that DCA therapy may not retard the progress of the primary disease in Leigh syndrome, but produced clinical improvement most likely by reducing toxic accumulation of lactate.

Aspartic Acid↗

PubMed1997

Stretch-induced contraction of rabbit isolated pulmonary artery and the involvement of endothelium-derived thromboxane A2.

1. The mechanism of stretch-induced contraction of the intrapulmonary artery of rabbit was studied with special regard to the endothelium-dependence and production of prostanoids. 2. Isolated intrapulmonary artery of rabbits in ring form produced contraction when stretched slowly up to 180% of its initial muscle length (= 100%) at a rate of 0.44 mm s-1, with a stimulus period of 5 min. 3. The stretch-induced contraction was attenuated by the mechanical removal of the endothelium, inhibitors of cyclo-oxygenase such as aspirin and indomethacin, [1S-[1 alpha,2 alpha (Z),3 alpha,4 alpha]]-7-[3-[[2-[(phenylamino)carbonyl] hydrazino]methyl]-7-oxabicyclo[2.2.1]hept-2-y1]-5-heptenoic acid (SQ 29,548), which is a thromboxane A2/prostaglandin H2 receptor antagonist, or by ozagrel, an inhibitor of thromboxane A2 synthase. 4. Biochemical assay indicated that the production of thromboxane B2, a stable metabolite of thromboxane A2, was increased 17 times in response to stretch only when the endothelium was intact. The production of thromboxane B2 was also inhibited by aspirin or ozagrel. 5. The production of 6-keto prostaglandin F1 alpha, a stable metabolite of prostacyclin, was also increased in response to stretch in the preparation with intact endothelium. However, ozagrel showed no apparent effect on the production of 6-keto prostaglandin F1 alpha. 6. These results suggest that a mechanical stimulus like stretch can act on endothelial cells of rabbit pulmonary artery to cause contraction by activation of arachidonic acid metabolism via the cyclooxygenase pathway and subsequent release of thromboxane A2 and/or an increase in the ratio of thromboxane A2/prostacyclin.

Acetylcholine↗

PubMed1997

Persistent production of interferon-gamma (IFN-gamma) and IL-12 is essential for the generation of protective immunity against Listeria monocytogenes.

IFN-gamma and IL-12 are believed to be important in the host defence against Listeria infection in mice. However, the relationship between these two cytokines and generation of protective immunity remains poorly understood. In the present study, it was found that at least 4 days of immunizing infection were required for the generation of protective immunity against L. monocytogenes. Protective immunity was generated only by immunizing infection with virulent strain. Even repeated injections of avirulent strain failed to induce protective immunity. When the immunizing infection was terminated with antibiotics, generation of protective immunity and IFN-gamma-producing ability was impaired, while expression of IFN-gamma and IL-12 was also impaired. The mutual relationship between IFN-gamma and IL-12 in L. monocytogenes infection was analysed in vitro. After neutralization of IL-12, IFN-gamma production was completely blocked and IFN-gamma expression was also inhibited. In contrast, there was no change of IL-12 expression after neutralization of IFN-gamma. Taking all facts into consideration, it may be concluded that persistent production of IFN-gamma induced by persistent production of IL-12 during immunizing infection is essential for the generation of protective immunity against L. monocytogenes.

Animals↗

PubMed1997

Epilepsy in peroxisomal diseases.

PURPOSE: To clarify the electroclinical manifestation of epileptic seizures and the evolution of epilepsy in patients with peroxisomal diseases. METHODS: Retrospective review of the medical records and EEGs of 14 patients with peroxisomal diseases: seven with Zellweger syndrome (ZS), two with neonatal adrenoleukodystrophy (NALD), two with acyl-CoA oxidase deficiency (AOXD), two with bifunctional enzyme deficiency (BFED), and one with rhizomelic chondrodysplasia punctata (RCDP). The diagnoses were made by biochemical analysis and pathological examinations in our laboratory. RESULTS: Patients manifested serious neurologic deficits in the neonatal period or in early or late infancy. Patients with ZS or AOXD had partial motor seizures originating in the arms or legs or corners of the mouth. Their seizures did not culminate in generalized tonic-clonic seizures and were easily controlled by antiepileptic drugs (AEDs). Interictal EEGs of the patients with ZS showed infrequent bilateral independent multifocal spikes, predominantly in the frontal motor cortex and its surrounding regions. The EEGs of patients with AOXD showed interictal fast theta activity, predominantly in the frontocentral regions. Patients with BFED also had partial motor seizures in early infancy, but the seizures were intractable, evolving in one case to myoclonic seizures. Interictal EEGs of patients with BFED showed bilateral independent multifocal spikes that evolved to bilateral diffuse high-voltage slow waves in one case and to a hypsarythmic pattern in another case as the disease progressed. Patients with NALD had intractable tonic seizures or epileptic spasms. Interictal EEGs showed high-voltage slow waves and bilateral independent multifocal spikes, evolving in one patient to a flat pattern. The patient with RCDP, whose interictal EEGs showed frequent multifocal independent spikes, did not have epileptic seizures. CONCLUSIONS: The age of epilepsy onset or the duration of survival is related to the types of seizures occurring in patients with peroxisomal diseases. Neonates or young infants usually have partial motor seizures (facial twitching or clonic convulsions of the arms or legs) of various multifocal origins. Older infants may have generalized seizures at the onset of the disease or evolutionally. Seizure intractability is usually less severe in patients with ZS or AOXD than in patients with NALD or BFED. There is no relation between the electroclinical characteristics of epilepsy and the genetic complementation groups in peroxisomal diseases.

Acyl-CoA Oxidase↗

PubMed1997

Procainamide induced change of the width of the zone of entrainment and its relation to the inducibility of reentrant ventricular tachycardia.

Procainamide depresses conduction velocity and prolongs refractoriness in myocardium responsible for reentrant VT, but the mechanism by which the induction of VT is suppressed after procainamide administration remains to be determined. In the present study, the relationship between electrophysiological parameters and the noninducibility of VT was assessed during procainamide therapy with a special reference to the change of an excitable gap. Clinically documented monomorphic sustained VT was induced in 30 patients and, utilizing the phenomenon of transient entrainment, the zone of entrainment was measured as the difference between the cycle length of VT and the longest paced cycle length interrupting VT (block cycle length) which was determined as the paced cycle length decreased in steps of 10 ms, and used as an index of the excitable gap. The effective refractory period was measured at the pacing site and the paced QRS duration was used as an index of the global conduction time in the ventricle. The cycle length of VT, the block cycle length, and the width of the zone of entrainment were determined and compared between the responders and nonresponders. In 15 patients, these parameters were determined at the intermediate dose and related to subsequent noninducibility at the final dose. At the final doses of procainamide, VT was suppressed in 8 (26.7%) of 30 patients. However, the cycle length of VT, the block cycle length, and the width of the zone of entrainment were unable to predict the drug efficacy, i.e., noninducibility. The change in the effective refractory period at the pacing site or the width of the paced QRS duration was not different between the responders and nonresponders. Among the variables, only the width of the zone of entrainment showed a significant narrowing in the responders at the intermediate dose of procainamide, and it was smaller than that of the nonresponders. The significant narrowing of the width of the zone of entrainment was associated with the subsequent noninducibility of VT at the final dose. The present study showed that the baseline cycle length of VT, the block cycle length, the drug induced change of the effective refractory period, or the paced QRS duration was not a predictor of the noninducibility after procainamide administration. However, a significant narrowing of the width of the zone of entrainment at the intermediate dose was associated with the noninducibility of VT at the final dose.

Adolescent↗

PubMed1997

Extensive interbreeding occurred among multiple matriarchal ancestors during the domestication of dogs: evidence from inter- and intraspecies polymorphisms in the D-loop region of mitochondrial DNA between dogs and wolves.

To test the hypothesis that the domestic dogs are derived from several different ancestral gray wolf populations, we compared the sequence of the displacement (D)-loop region of the mitochondrial DNA (mtDNA) from 24 breeds of domestic dog (34 individual dogs) and 3 subspecies of gray wolf (Canis lupus lupus, C.l. pallipes and C.l. chanco; 19 individuals). The intraspecific sequence variations within domestic dogs (0.00-3.19%) and within wolves (0.00-2.88%) were comparable to the interspecific variations between domestic dogs and wolves (0.30-3.35%). A repetitive sequence with repeat units (TACACGTA/GCG) that causes the size variation in the D-loop region was also found in both dogs and wolves. However, no nucleotide substitutions or repetitive arrays were specific for domestic dogs or for wolves. These results showed that there is a close genetic relationship between dogs and wolves. Two major clades appeared in the phylogenetic trees constructed by neighbor-joining and by the maximum parsimony method; one clade containing Chinese wolf (C.l. chanco) showed extensive variations while the other showed only slight variation. This showed that there were two major genetic components both in domestic dogs and in wolves. However, neither clades nor haplotypes specific for any dog breed were observed, whereas subspecies-specific clades were found in Asiatic wolves. These results suggested that the extant breeds of domestic dogs have maintained a large degree of mtDNA polymorphisms introduced from their ancestral wolf populations, and that extensive interbreedings had occurred among multiple matriarchal origins.

Animals↗

PubMed1997

Incidence of dogs possessing red blood cells with high K in Japan and East Asia.

The phenotype of high K (HK) red blood cells, which is an autosomal recessive, was found in dog groups from 10 of 13 breeds or populations in Japan. The incidence of HK was 26 to 38% in the San'in-Shiba, Shinshu-Shiba and Akita breeds, and the gene frequencies of HK ranged from 0.513 to 0.612. The highest incidence (42%) was found in the Jindo breed from Korea, and the gene frequency was 0.652. Two other groups from Korea also possessed this HK variation. However, although HK cells were not found in dogs from Taiwan, Indonesia, Mongolia and Sakhalin, Russia, the HK phenotype is clearly distributed now throughout Japan and Korea.

Animals↗

PubMed1997

Three-dimensional computed tomography imaging of a frontal skull base fracture.

A 7-year-old boy presented with recurrent meningitis after head trauma. Coronal computed tomography (CT) revealed prolapse of the intracranial soft tissue into the right ethmoidal sinus, leading to the diagnosis of right frontal skull base fracture. Three-dimensional CT with bone windows provided a lifelike image of the fracture lateral to the right olfactory groove. This image was most useful in the preoperative planning of the repair surgery.

Child↗

PubMed1996

Involvement of various combinations of endogenous inflammatory cytokines in Listeria monocytogenes-induced expression of inducible nitric oxide synthase in mice.

Using a in vitro infection of spleen cells with Listeria monocytogenes, the relationship between endogenous cytokines and the expression of inducible nitric oxide synthase (iNOS) was examined. When all interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 alpha, or the combination of IFN-gamma with either TNF-alpha or IL-1 alpha were neutralized by antibodies, there was a significant reduction of iNOS expression and nitrite production in culture. However, there was no reduction of iNOS expression and nitrite production when these cytokines were individually neutralized. After the depletion of natural killer cells, there was no change in the expression of Listeria-induced iNOS and nitrite production although the IFN-gamma production was abrogated. Neutralization of TNF-alpha and IL-1 alpha in natural killer cell-depleted culture resulted in the reduction of iNOS expression. Thus, various combinations of cytokines to play an important role in iNOS induction by L. monocytogenes.

Animals↗

PubMed1996

Diversity and pattern in the developing spinal cord.

The generation of distinct neuronal cell types in appropriate numbers and at precise positions underlies the assembly of neural circuits that encode animal behavior. Despite the complexity of the vertebrate central nervous system, advances have been made in defining the principles that control the diversification and patterning of its component cells. A combination of molecular genetic, biochemical, and embryological assays has begun to reveal the identity and mechanism of action of molecules that induce and pattern neural tissue and the role of transcription factors in establishing generic and specific neuronal fates. Some of these advances are discussed here, focusing on the spinal cord as a model system for analyzing the molecular control of central nervous system development in vertebrates.

Animals↗

PubMed1996

Expression of the Streptomyces coelicolor A3(2) ptpA gene encoding a phosphotyrosine protein phosphatase leads to overproduction of secondary metabolites in S. lividans.

A DNA fragment that caused pigment production in Streptomyces lividans was isolated from a gene library of PstI-digested chromosomal fragments of S. coelicolor A3(2). Subcloning and nucleotide sequencing proved the identity of the cloned gene to ptpA encoding a low-molecular-mass phosphotyrosine protein phosphatase. The S. lividans transformant containing ptpA on pIJ41 with a copy number of 3 4 per genome produced large amounts of undecylprodigiosin and A-factor, in addition to the pigmented antibiotic actinorhodin, whereas the transformant containing ptpA on an SCP2* derivative with a copy number of 1-2 did not. The PtpA protein produced as a fusion to the maltose binding protein in Escherichia coli showed phosphatase activity toward o-phosphotyrosine, but not toward o-phosphoserine or a-threonine. Introduction of a mutant ptpA gene encoding an inactive protein with serine instead of the 9th cysteine caused no pigmentation. Disruption of the chromosomal ptpA gene of S. coelicolor A3(2), however, appeared to cause no detectable effect on the production of the pigmented antibiotics or A-factor and the ptpA disruptants developed aerial mycelium and spores normally.

4-Butyrolactone↗

PubMed1996

T2 shortening in childhood moyamoya disease.

We examined T2 shortening in six children with infarcts due to moyamoya disease to clarify whether there are characteristic patterns of T2 shortening in the deep grey and white matter. Profound T2 shortening in the deep grey and white matter was observed in the acute stage of infarct in two cases, which changed to high intensity in the chronic stage; in this stage no T2 shortening was demonstrated in any case. Neither haemorrhagic infarction nor calcification was seen on CT or MRI. There could be longitudinally different T2 shortening patterns between infarcts due to moyamoya disease and other disorders.

Cerebral Cortex↗

PubMed1996

Basement membrane abnormality in merosin-negative congenital muscular dystrophy.

In muscle biopsy specimens from three patients with merosin-negative congenital muscular dystrophy (CMD), there was marked variation in fiber size with evidence of necrotic and regenerating processes and with marked interstitial fibrosis. No muscle fibers or intramuscular nerves stained with merosin antibody. On electron microscopy, the basement membrane of all the muscle fibers was very poorly discernible and there were occasional disruptions, while the basement membrane of the Schwann cells was well preserved. On the other hand, the sarcolemmal basement membrane in merosin-positive CMD was well preserved even in patient with severe interstitial fibrosis. It remains to be determined how the defective basement membrane in merosin-negative CMD induces defective sarcolemma and eventual fiber necrosis.

Basement Membrane↗

PubMed1996

Mechanism of tachycardia-dependent appearance of ventricular extrasystoles in concealed bigeminy.

A case of concealed ventricular bigeminy is reported in which the number of sinus QRS complexes intervening between two successive noninterpolated extrasystoles was always uneven. Coupling intervals of manifest extrasystoles to the preceding sinus QRS complexes were almost fixed and much longer than sinus QT intervals. Bradycardia-dependent disappearance of manifest bigeminy and tachycardia-dependent appearance of extrasystoles occurred in this case. Apparently, 2:1 block of sinus impulses occurred in the reentrant pathway, with markedly depressed conductivity. Concealed electrotonic conduction of blocked sinus impulses in the pathway of extrasystoles may have favored the appearance of the subsequent manifest extrasystoles without concealed conduction owing to two-level block. A possible explanation for the mechanism of such concealed bigeminy is presented, which uses the concepts of longitudinal dissociation and electrotonic inhibition in the reentrant pathway with markedly depressed conductivity.

Adult↗

PubMed1996

Case report: primary splenic non-Hodgkin's B cell lymphoma in a patient with chronic hepatitis C.

A case of primary splenic lymphoma in a patient with chronic hepatitis C is reported. A 69-year-old man with chronic hepatitis C was admitted to Fukuoka City Hospital for evaluation of an enlarging splenic tumour. In the spleen, ultrasonographic examination revealed a hypoechoic tumour and computed tomography demonstrated a non-enhancing low density area measuring 7 cm in diameter; coeliac angiography revealed a hypovascular tumour. Gallium scintigraphy showed uptake of the radioisotope in the splenic tumour. A splenectomy was performed and the morphological and immunohistochemical findings of this tumour were compatible with those of non-Hodgin's B cell lymphoma. Recently, cases of malignant B cell lymphoma associated with hepatitis C virus infection have been reported. Lymphotropism of hepatitis C virus may play a pathological role in the development of non-Hodgkin's lymphoma. We emphasize the importance of considering lymphoma in the differential diagnosis of extrahepatic disorders during the course of chronic hepatitis C virus infections.

Aged↗

PubMed1996

Haemorrhagic shock and encephalopathy associated with rotavirus infection.

We report on a 21-month-old girl with a haemorrhagic shock and encephalopathy who survived. Rotavirus genomic ribonucleic acid was detected by reverse transcription polymerase chain reaction in stool, blood and cerebrospinal fluid. Serum antibody titres of the rotavirus were also high. Plasmapheresis had a stabilizing effect on the course of the disease. This case indicates that rotavirus infection may play an important role in the devastating cascade that occurs in some patients with this syndrome. The findings suggest that extensive investigation for rotavirus infection, particularly infection of the central nervous system, should be carried out in patients with haemorrhagic shock and encephalopathy.

Brain Diseases↗