Biomedical subjects

K Nagashima

Publications and source records attributed to K Nagashima.

At least 91 records · Page 5Linked to original sources

PubMed2000

Eosinophilic inclusions in ependymoma represent microlumina: a light and electron microscopic study.

A study was undertaken to determine the pathological significance of previously unrecognized intracytoplasmic eosinophilic inclusions (IEIs) in ependymoma. The study group consisted of 58 ependymomas, all of which were pathologically characterized and graded according to the 1993 WHO classification. Electron microscopic studies were performed in 16 cases. The study showed that 33 (57%) ependymomas had IEIs and that in 8 cases these were abundant. Round and eosinophilic, their sizes varied from 10 microns to a tiny dot. Similar eosinophilic bodies were also observed between tumor cells. The inclusions were weakly PAS positive. On immunostains, IEIs were frequently positive for glial fibrillary acidic protein, less often for S-100 protein, and for epithelial membrane protein and CAM 5.2. They were negative for AE1/AE3, carcinoembryonic antigen and Ber-EP4. Ultrastructurally, IEIs represented intracytoplasmic lumens containing microvilli and cilia. These microlumina also frequently contained granulo-tubular materials. With reference to tumor subtypes, IEIs occurred most frequently in ordinary and clear cell ependymomas. IEIs were also present in 4 of 6 anaplastic ependymomas studied. In conclusion, IEIs represent microlumina and occur in more than a half of ependymomas including malignant examples. Their finding is a helpful diagnostic feature of ependymoma.

Adolescent↗

PubMed2000

Membrane expression of annexin I is enhanced by calcium and TPA in cultured human keratinocytes.

Annexin I plays an important role in the process of keratinization as a component of the cornified envelope. To elucidate the function of annexin I in keratinization, we investigated the effects of calcium, epinephrine, hydrocortisone, and 12-O-tetradecanoyl phorbol 13-acetate (TPA) on the expression and localization of annexin I in cultured human keratinocytes. Normal human keratinocytes were cultured in serum-free culture medium (0.15 mM calcium) until 70% confluence. After incubation with a higher concentration of calcium (1.8 mM), TPA (100 nM), epinephrine (50 microM), or hydrocortisone (10 microM) for 24 h, the expression of annexin I protein and mRNA was examined using immunofluorescence, Western blot, and Northern blot techniques. Immunofluorescence microscopy showed increased membrane staining of annexin I by calcium, which was inhibited by the addition of epinephrine or hydrocortisone. Western blotting confirmed elevated annexin I on the cell membrane. It was increased in the cell membrane fraction, but not in the cytosol fraction. Interestingly, the mRNA level of annexin I was slightly reduced after incubation with calcium, whereas TPA upregulated both membrane expression and the mRNA level. Secretion of annexin I was increased by TPA but inhibited by calcium. Because calcium and TPA are known to promote keratinization, our data suggest that annexin I expression on the cell membrane is involved in the process of keratinization.

Annexin A1↗

PubMed2000

Regeneration of lymphatic vessels and lipometabolism in an experimental rat model of extensive dissection of the abdominal periaortic lymphatic vessels and lymph nodes.

The present study was conducted to analyze the regeneration of lymphatic vessels and lipometabolism in an experimental rat model of extensive dissection of the abdominal periaortic lymphatic vessels and lymph nodes from the renal artery to the mesenteric and celiac artery. Findings showing the regeneration of mesenteric lymphatic vessels were classified as complete, incomplete, or no regeneration. The incomplete regeneration of fine irregular lymphatic vessels was observed in all rats, 2 and 3 weeks postoperatively. At the same time, triglyceride (TG) was found to be significantly lower (P < 0.05) in the rats that were given extensive dissection than in the control group, due to chylomicron blockade after lymphatic dissection. The TG recovered to within the normal range around 4 weeks postoperatively following the growth of fine regenerated lymphatic vessels or collateral route formation.

Animals↗

PubMed2000

Oculopharyngeal muscular dystrophy in a Japanese family with a short GCG expansion (GCG)(11) in PABP2 gene.

Clinicopathological and molecular genetic findings on a new Japanese family with oculopharyngeal muscular dystrophy are reported. The family has 54 members, ten of whom are affected (seven male and three female), in 3 generations. Three affected males, one affected female and one unaffected female of seven living siblings in the third generation were examined. Bilateral ptosis developed in the 4th and 5th decades in the three male cases, and in the 7th decade in the female, and this was followed by diplopia, nasal voice, dysphagia and muscle weakness. In addition, severe external ophthalmoplegia, dysphonia, and proximal amyotrophy were prominent in this family. Electromyographs revealed myogenic/neurogenic changes, and computed tomography disclosed selective muscle wasting with fatty replacement, predominantly in the lower extremities. Muscle biopsy in the four affected patients showed variation in fiber size, and the presence of small angulated fibers and occasional rimmed vacuoles. Electron microscopic examination revealed an accumulation of filamentous inclusions in muscle fiber nuclei. DNA analysis identified that (GCG)(6) in the PABP2 gene was expanded to (GCG)(11) in the four affected cases examined. All studies were negative in the one unaffected. These results confirm that OPMD is caused by GCG short expansion and provides insights into the genetic mechanisms which may contribute to adult onset myopathy, confined to oculopharyngeal muscles.

Aged↗

PubMed2000

Sequential observation of liver cell regeneration after massive hepatic necrosis in auxiliary partial orthotopic liver transplantation.

The morphogenesis of hepatocytes after massive hepatic necrosis to recovery through liver cell regeneration has not been fully understood. Sequential biopsies were performed on the native liver of a 22-year-old man who underwent auxiliary partial orthotopic liver transplantation 1 month after fulminant hepatitis. Auxiliary partial orthotopic liver transplantation was successful, and the biopsy samples permitted us to examine the regenerating process of hepatocytes after massive necrosis. At the time of auxiliary partial orthotopic liver transplantation (postoperative day 0), 95% of hepatocytes were lost and a few ductules were found in the portal areas. The ductules stained with cytokeratin 19. At postoperative day 7, the ductules began to increase in size and number and became dilated over a period of 1 month, when individual hepatocytes with clear cytoplasm appeared from the ductules. As the differentiation of hepatocytes increased, the expression of cytokeratin 19 was found to decrease. From 2 to 3 months, all of the ductules were transformed into hepatocytes, and they began to form round cell clusters. From 3 to 6 months, the round cell clusters became organized into trabecula with fibrosis. From 6 to 12 months, a lobular architecture was established, and by 14 months, the necrotic liver was fully recovered to normal. This study by examination of sequential biopsies demonstrates the progression of the regenerating process from total hepatic necrosis to complete recovery.

Adult↗

PubMed2000

T-0162, a novel free radical scavenger, reduces myocardial infarct size in rabbits.

1. We investigated the effects of 1-(3-tert-butyl-2-hydroxy-5-methoxyphenyl)-3-(3-pyridylmethyl)urea hydrochloride (T-0162), a novel low-molecular weight free radical scavenger, on the generation of superoxide anions and hydroxyl radicals in vitro and in vivo and on myocardial infarct (MI) size in an in vivo model of MI in rabbits. 2. It was found that T-0162 scavenged both superoxide anions and hydroxyl radicals in a concentration-dependent manner in vitro. 3. In an in vivo rabbit model with 30 min coronary occlusion and 30min reperfusion, T-0162 scavenged hydroxyl radicals generated in the myocardium during reperfusion. 4. Anaesthetized open-chest Japanese white male rabbits were subjected to 30 min coronary occlusion and 48 h reperfusion. The control group (n = 10) was infused with 10% lecithin solution for 220 min from 10 min before occlusion to 180 min after reperfusion. The pretreatment group (n = 10) was infused with T-0162 dissolved in 10% lecithin solution for 220 min from 10 min before occlusion to 180 min after reperfusion at a rate of 400 microg/kg per min. The post-treatment group (n = 10) was injected with an i.v. bolus of 10 mg/kg T-0162 and was then infused with 400 microg/kg per min T-0162 for 190 min from 10 min before reperfusion to 180 min after reperfusion. After 48 h reperfusion, infarct size was measured histologically and expressed as a percentage of area at risk (AAR). 5. There was no significant difference in haemodynamic parameters among the three groups throughout the experimental period. The per cent infarct size of the AAR in the T-0162 groups (24.8+/-4.3 and 30.5+/-3.9% for pre- and posttreatment groups, respectively) was significantly reduced compared with control (44.7+/-4.1%; P<0.05). There was no significant difference in the AAR among the three groups. 6. In conclusion, T-0162 reduces MI size through the inhibition of reperfusion injury.

Animals↗

PubMed2000

Dural band pathology in syringomyelia with Chiari type I malformation.

Surgical material taken from the 'outer layer' of thickened dura mater (dural band) at the craniovertebral junction of eight cases of syringomyelia with Chiari type I malformation was histologically examined in comparison with four autopsy cases as controls. The dural band was thickened and there were increased numbers of collagen fibers which showed fiber splitting, hyalinous nodule, calcification and/or ossification. These changes were not observed in the four control cases. Thus, it is suggested that the thickening of the dura mater may be a causative factor of syringomyelia with Chiari type I malformation. In addition, the histology of the thickened dura mater suggests the condition may be a consequence of birth injury in these patients.

Adolescent↗

PubMed2000

P-ANCA-positive Wegener's granulomatosis presenting with hypertrophic pachymeningitis and multiple cranial neuropathies: case report and review of literature.

An autopsy case of hypertrophic pachymeningitis and multiple cranial neuropathies is reported. A 53-year-old woman with paraplegia and various neurological signs which developed over a 2 year period was diagnosed as having an epidural mass with thickened dura mater extending from the lower cervical to the thoracic spinal cord. In addition, bilateral episcleritis, blephaloptosis, and blindness of the right eye with various cranial nerve deficits were found to be caused by the mass lesions involving the paranasal sinuses, orbit, and the cavernous sinus. Perinuclear antineutrophil cytoplasmic antibody (p-ANCA) was positive, but cytoplasmic antineutrophil cytoplasmic antibody (c-ANCA) was negative by enzyme-linked immunosorbent assay. The partially removed epidural mass with hypertrophied dura mater and biopsy of the paranasal lesions showed chronic granulomatous inflammation with vasculitis. The remaining lesions resolved with steroid therapy with remarkable neurological improvement. The positive p-ANCA test, paranasal involvement, the report of a similar histopathological case and a review of the literature on granulomatous pachymeningitis suggest the presence of p-ANCA-positive Wegener's granulomatosis with central nervous system involvement characterized by hypertrophic pachymeningitis and/or multiple cranial neuropathies.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed2000

Encephalomyelitis, brain tumors, neuromuscular diseases and miscellaneous disorders.

Japanese neuropathologists have accomplished and contributed to a considerable number of achievements, and some of these are cited in other articles in this issue. Several of these achievements as well as other miscellaneous discoveries are briefly summarized in the present paper. Specifically these relate to rabies postvaccinal encephalomyelitis, experimental allergic encephalomyelitis, brain tumor research, neuromuscular disorders, schizophrenia, viral infections, glial inclusion body in multiple system atrophy, and the neurobiology of glia.

Brain Neoplasms↗

PubMed2000

Cerebral vasculitis in chronic mucocutaneous candidiasis: autopsy case report.

An autopsy case of chronic mucocutaneous candidiasis (CMCC) is reported here, in which cerebral vasculitis developed in the final stage. A 32-year-old man who had suffered from superficial candidial infection since his childhood was diagnosed as having CMCC. During the past 7 years the patient had developed various associated disorders including insulin-dependent diabetes mellitus (IDDM), common variable immunodeficiency (CVID), candidial esophagitis, multiple digestive tract ulcers and pyothorax. In 1998, at the age of 32, he developed convulsions that were accompanied by impairment of consciousness, and which were temporarily treated with steroid pulsed-medication. Epileptic status associated with widespread cerebral infarctions occurred subsequently, however, and the patient died of sepsis 2 months later. At autopsy, multiple cerebral infarctions and arterial thrombosis were evident. These were histologically proven to be primary vasculitis which was confined solely to the brain, and this was verified by general pathological examination. Thus, some as yet unknown cerebrovascular factors might be involved in the onset of an autoimmune-related vasculitis in patients with a longstanding immunodeficiency state such as CMCC.

Adult↗

PubMed2000

Declining of memory functions of normal elderly persons.

Two studies examined the declining of memory functions in normal elderly persons using the Yokota memory test (YMT), which includes 15 items concerning verbal and non-verbal memory functions. In the first study, 552 subjects over 40 years of age in five age groups were examined. Factor analysis revealed that YMT consisted of two factors pertaining to short-term/working memory, and two factors pertaining to long-term memory. It is suggested that the former was more affected than the latter, with aging. In the second study, YMT was examined in relation to the revised version of Hasegawa dementia scale (HDS-R), which was the most popular intelligence scale for the elderly in Japan. As a result, memory functions differentially declined with the decreasing score of HDS-R, which suggests that memory functions differentially declined with progressive risk of dementia.

Adult↗

PubMed2000

Glial cell line-derived neurotrophic factor modulates ischemia-induced tyrosine hydroxylase expression in rat hippocampus.

Recently, we have reported that glial cell line-derived neurotrophic factor (GDNF), which supports the survival of dopaminergic neurons, prevents delayed neuronal death in the hippocampal CA1 region induced by transient forebrain ischemia. In the present study, we examined the role of GDNF in the expression of tyrosine hydroxylase (TH) mRNA induced by transient forebrain ischemia in rats. The expression of TH mRNA was increased in a time-dependent manner, with a significant increase in 24 h to 7 days, in the hippocampus after induction of transient forebrain ischemia, as determined using the reverse transcription and polymerase chain reaction method. Although it has been suggested that the increase of dopamine beta-hydroxylase mRNA expression correlates with the activation of noradrenergic neurons, no increase of dopamine beta-hydroxylase mRNA in the hippocampus was observed in our system. Western blot analysis revealed that TH protein, but not dopamine beta-hydroxylase protein, was produced in a time-dependent manner in the hippocampus during the ischemia. Interestingly, the induction level of TH mRNA was reduced by intrahippocampal microinjection of GDNF (1.0 microg), and this local GDNF treatment also reduced the increase of TH-like immunohistochemistry-positive terminals in the hippocampus. In contrast, local GDNF treatment of normal rats increased the TH mRNA expression at 6-12 h. These findings suggest that GDNF protects against neuronal degeneration including delayed neuronal death in the hippocampal CA1 region by modulating the expression levels of TH mRNA and protein.

Animals↗

PubMed2000

A novel hydroxyl radical scavenger, nicaraven, protects the liver from warm ischemia and reperfusion injury.

BACKGROUND: Reactive oxygen species have been considered to be involved in liver injury at the procurement, preservation, and transplantation from donors without beating hearts. A novel hydroxyl radical scavenger, nicaraven with hydrophilic and lipophilic properties, infiltrates both intracellular and extracellular spaces where it effectively scavenges reactive oxygen species. Protection by nicaraven against ischemia and reperfusion damage of the brain, heart, and kidneys has been shown. The effect of this agent on the liver remains unclear. METHODS: Two-hour total hepatic vascular exclusion was used. Eighteen beagle dogs were randomly assigned to 2 groups: 12 animals were not treated (group I) and 6 were treated with nicaraven (group II). Nicaraven was administered intravenously (2mg/kg/min) for 60 minutes before ischemia and for 3 hours, starting 30 minutes before reperfusion. RESULTS: Two-week survival rates were 25% in group I and 100% in group II (P <.01). Nicaraven inhibited lipid peroxidation in the liver, improved hepatic and systemic hemodynamics and energy metabolism, and suppressed liver enzyme release, endothelin-1 elevation in hepatic venous blood, histologic damage, and neutrophil infiltration into the liver. CONCLUSIONS: Nicaraven exerted hepatic protection against warm ischemia and reperfusion injury. This may indicate nicaraven as a potential candidate to attenuate liver injury from warm ischemia and preservation in transplantation from donors without beating hearts.

Adenine Nucleotides↗

PubMed2000

Monoclonal antibodies against topoisomerase I suppressed DNA relaxation and HIV-1 cDNA synthesis.

Human immunodeficiency virus type 1 (HIV-1) virion is known to carry a number of cellular components including cellular topoisomerase I. Previously, we have demonstrated that topoisomerase I enhances HIV-1 cDNA synthesis in reverse transcription (RT) assays in vitro. In the present study, we have produced six monoclonal antibodies (MAbs) against human topoisomerase I. The MAbs suppressed nicking/closing of supercoiled DNA and cDNA synthesis in an endogenous reverse transcription (ERT) assay using a detergent-disrupted HIV-1 virion. Thus, the results suggest that topoisomerase I plays an important role in RNA-directed DNA polymerization.

Animals↗

PubMed2000

Infection with JC virus and possible dysplastic ganglion-like transformation of the cerebral cortical neurons in a case of progressive multifocal leukoencephalopathy.

Infection of the cerebral cortical neurons with JC virus (JCV) with possible dysplastic ganglion-like alteration of the infected neurons found in a case of progressive multifocal leukoencephalopathy (PML) is described. The patient was a 21-year-old man with common variable immunodeficiency who died of PML after a 9-month clinical course. At autopsy, the white matter of the cerebrum, brainstem, cerebellum, and spinal cord exhibited extensive demyelination and necrosis. Numerous inclusion-bearing oligodendrocytes and bizarre astrocytes were found. In the occipital and temporal cortex, thick band-like aggregates of dysplastic ganglion-like cells (DGLCs) were found. These DGLCs showed immunohistochemical properties of neurons, and nuclei of some DGLCs were immunoreactive for large T antigen of SV40/JCV and p53, but not for capsid protein JCV VP1. In situ hybridization for mRNA of JCV large T antigen revealed positive signals in the nuclei of some DGLCs. These results indicate that JCV infected neurons and it is suggested that binding of the large T antigen with cellular proteins could have resulted in the dysplastic, ganglion cell-like change of the infected neurons, although the possibility that the aggregates of DGLCs represent a pre-existent malformative lesion of the cortex cannot be excluded completely.

Adult↗

PubMed2000

Identification of a key target sequence to block human immunodeficiency virus type 1 replication within the gag-pol transframe domain.

Although the full sequence of the human immunodeficiency virus type 1 (HIV-1) genome has been known for more than a decade, effective genetic antivirals have yet to be developed. Here we show that, of 22 regions examined, one highly conserved sequence (ACTCTTTGGCAACGA) near the 3' end of the HIV-1 gag-pol transframe region, encoding viral protease residues 4 to 8 and a C-terminal Vpr-binding motif of p6(Gag) protein in two different reading frames, can be successfully targeted by an antisense peptide nucleic acid oligomer named PNA(PR2). A disrupted translation of gag-pol mRNA induced at the PNA(PR2)-annealing site resulted in a decreased synthesis of Pr160(Gag-Pol) polyprotein, hence the viral protease, a predominant expression of Pr55(Gag) devoid of a fully functional p6(Gag) protein, and the excessive intracellular cleavage of Gag precursor proteins, hindering the processes of virion assembly. Treatment with PNA(PR2) abolished virion production by up to 99% in chronically HIV-1-infected H9 cells and in peripheral blood mononuclear cells infected with clinical HIV-1 isolates with the multidrug-resistant phenotype. This particular segment of the gag-pol transframe gene appears to offer a distinctive advantage over other regions in invading viral structural genes and restraining HIV-1 replication in infected cells and may potentially be exploited as a novel antiviral genetic target.

3' Untranslated Regions↗

PubMed2000

Analysis of capsid formation of human polyomavirus JC (Tokyo-1 strain) by a eukaryotic expression system: splicing of late RNAs, translation and nuclear transport of major capsid protein VP1, and capsid assembly.

Human polyomavirus JC (JCV) can encode the three capsid proteins VP1, VP2, and VP3, downstream of the agnoprotein in the late region. JCV virions are identified in the nucleus of infected cells. In this study, we have elucidated unique features of JCV capsid formation by using a eukaryotic expression system. Structures of JCV polycistronic late RNAs (M1 to M4 and possibly M5 and M6) generated by alternative splicing were determined. VP1 would be synthesized from M2 RNA, and VP2 and VP3 would be synthesized from M1 RNA. The presence of the open reading frame of the agnoprotein or the leader sequence (nucleotides 275 to 409) can decrease the expression level of VP1. VP1 was efficiently transported to the nucleus in the presence of VP2 and VP3 but distributed both in the cytoplasm and in the nucleus in their absence. Mutation analysis indicated that inefficiency in nuclear transport of VP1 is due to the unique structure in the N-terminal sequence, KRKGERK. Within the nucleus, VP1 was localized discretely and identified as speckles in the presence of VP2 and VP3 but distributed diffusely in their absence. These results suggest that VP1 was efficiently transported to the nucleus and localized in the discrete subnuclear regions, possibly with VP2 and VP3. By electron microscopy, recombinant virus particles were identified in the nucleus, and their intranuclear distribution was consistent with distribution of speckles. This system provides a useful model with which to understand JCV capsid formation and the structures and functions of the JCV capsid proteins.

Alternative Splicing↗

PubMed2000

Rap2 as a slowly responding molecular switch in the Rap1 signaling cascade.

Rap2 is a member of the Ras family of GTPases and exhibits 60% identity to Rap1, but the function and regulation of Rap2 remain obscure. We found that, unlike the other Ras family proteins, the GTP-bound active form exceeded 50% of total Rap2 protein in adherent cells. Guanine nucleotide exchange factors (GEFs) for Rap1, C3G, Epac (or cyclic AMP [cAMP]-GEF), CalDAG-GEFI, PDZ-GEF1, and GFR efficiently increased the level of GTP-Rap2 both in 293T cells and in vitro. GTPase-activating proteins (GAPs) for Rap1, rap1GAPII and SPA-1, stimulated Rap2 GTPase, but with low efficiency. The half-life of GTP-Rap2 was significantly longer than that of GTP-Rap1 in 293T cells, indicating that low sensitivity to GAPs caused a high GTP/GDP ratio on Rap2. Rap2 bound to the Ras-binding domain of Raf and inhibited Ras-dependent activation of Elk1 transcription factor, as did Rap1. The level of GTP-Rap2 in rat 3Y1 fibroblasts was decreased by the expression of v-Src, and expression of a GTPase-deficient Rap2 mutant inhibited v-Src-dependent transformation of 3Y1 cells. Altogether, Rap2 is regulated by a similar set of GEFs and GAPs as Rap1 and functions as a slowly responding molecular switch in the Rap1 signaling cascade.

3T3 Cells↗