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Biomedical subjects

A Tamura

Publications and source records attributed to A Tamura.

At least 199 records · Page 11Linked to original sources
PubMed1997

Limited but significant protective effect of hypothermia on ultra-early-type ischemic neuronal injury in the thalamus.

We investigated the protective effect of hypothermia on ultra-early-type ischemic injury in the thalamic reticular nucleus of the rat. Cerebral ischemia was produced by 5 min of cardiac arrest followed by resuscitation. Rectal and cranial temperature during and after cardiac arrest was maintained at 37-38 degrees C in the normothermic group and at 32-33 degrees C in the hypothermic group. In the postischemic hypothermic group, temperature was maintained at 32-33 degrees C starting 15 min after normothermic ischemia. Histological damage was evaluated quantitatively. While after 5 min of recirculation there was no difference in morphological changes in terms of neuronal halo formation, intraischemic hypothermia reduced the severity of the degenerative changes represented by vacuolated or dark neurons by 15 min. Postischemic hypothermia failed to show any evidence of protection by 30 min. The protective effect of intraischemic hypothermia remained significant when evaluated at 14 days after ischemia by volumetry of the lesion and neuronal density analysis, whereas postischemic hypothermia had no clear protective effect. These results suggest that the protective effect of intraischemic hypothermia applies to neurons susceptible to ultra-early-type injury, but the effect of postischemic hypothermia is limited because normothermic ischemia results in extensive degeneration in these neurons by 15 min.

Animals↗
PubMed1997

Ehrlichia sennetsu groE operon and antigenic properties of the GroEL homolog.

A clone expressing an immunoreactive 55-kilodalton (kDa) protein of Ehrlichia sennetsu, the causative agent of human Sennetsu ehrlichiosis, was isolated from a gene library of this organism. Sequence analysis of the DNA insert revealed two open reading frames, encoding proteins of 10,620 and 58,225 kDa, respectively. These deduced amino acid sequences were homologous to those of the GroES and GroEL heat shock proteins (HSP) of other bacteria, respectively. Phylogenetic trees based on GroES and GroEL homologs of several bacteria including E. sennetsu showed a relationship similar to that based on 16S rRNA gene sequences. The recombinant and native 55-kDa proteins of E. sennetsu, GroEL homolog, reacted with a monoclonal antibody (SPA807) which recognizes a homologous sequence between human and mycobacterial HSP60 and a polyclonal antibody (SPA804) to cyanobacteria HSP60, but not with antibodies to HSP60 of several other organisms used. Furthermore, anti-recombinant E. sennetsu 55-kDa protein antibody prepared in a rabbit was reactive to HSP60 antigens of other Ehrlichia and Rickettsia species, but not GroEL of E. coli. The recombinant 55-kDa protein would be a useful tool for studying the role of this antigen in the immune response to E. sennetsu infection.

Amino Acid Sequence↗
PubMed1997

Cytochrome b in human complex II (succinate-ubiquinone oxidoreductase): cDNA cloning of the components in liver mitochondria and chromosome assignment of the genes for the large (SDHC) and small (SDHD) subunits to 1q21 and 11q23.

Complex II (succinate-ubiquinone oxidoreductase) is an important enzyme complex in both the tricarboxylic acid cycle and the aerobic respiratory chains of mitochondria in eukaryotic cells and prokaryotic organisms. In this study, the amino acid sequences of the large (cybL) and small (cybS) subunits of cytochrome b in human liver complex II were deduced from cDNAs isolated by homology probing with mixed primers for the polymerase chain reaction. The mature cybL and cybS contain 140 and 103 amino acids, respectively, and show little similarity to the amino acid sequences of the subunits from other species in contrast to the highly conserved features of the flavoprotein (Fp) subunit and iron-sulfur protein (Ip) subunit. From hydrophobicity analysis, both cybL and cybS appear to have three transmembrane segments, indicating their role as membrane-anchors for the enzyme complex. Histidine residues, which are possible heme axial ligands in cytochrome b of complex II, were found in the second transmembrane segment of each subunit. The genes for cybL (SDHC) and cybS (SDHD) were mapped to chromosome 1q21 and 11q23, respectively by fluorescent in situ hybridization (FISH).

Base Sequence↗
PubMed1997

Modulation of protein kinases and microtubule-associated proteins and changes in ultrastructure in female rat pituitary cells: effects of estrogen and bromocriptine.

This study focused on the intracellular signal transduction system and microtubule-associated proteins (MAPs), such as MAP-2 and Tau protein. The modulation of these proteins and their correlation with ultrastructural changes were investigated in rat pituitary prolactin (PRL) cells. Adult female Wistar rats were treated with estrogen and bromocriptine and their pituitary glands were removed for analysis of the expression of tubulin, MAP-2, Tau protein, protein kinase C (PKC), and calcium calmodulin (CaM) kinase. Western blot analysis showed that estrogen increased and bromocriptine decreased the expression of PKC alpha, beta 1, beta 2, CaM kinase alpha, beta, MAP-2, and Tau protein. MAP-2 and Tau protein, which are cytosolic proteins, being translated on free ribosomes, were associated with the membrane of whirling rough endoplasmic reticulum (RER) in estrogen-treated cells and dissociated with vesiculated RER induced by bromocriptine. These results suggested that the modulation of MAP-2 and Tau protein may reflect changes of PKC and CaM kinase, and that the quantitative changes and intracellular modulation of MAPs induced by estrogen and bromocriptine, i.e., estrogen-induced association and bromocriptine-induced dissociation of MAP-2 and Tau protein with membrane of RER, may reflect the dynamics of microtubules and are associated with structural changes in the RER and changes in the synthesis and intracellular transport of PRL.

Animals↗
PubMed1997

Cerebroprotective effects of a novel pyrazoline derivative, MS-153, on focal ischemia in rats.

MS-153 ((R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline) is a novel pyrazoline compound that has potent cerebroprotective effects in the rat focal cerebral ischemia model. Middle cerebral artery (MCA) occlusion in rats allows detailed assessment of both functional and morphological sequelae of brain infarct. Using this model, we evaluated the cerebroprotective effects of MS-153. Treatment with MS-153 (12.5 mg/kg, i.v. bolus followed by 6.25 mg/kg/hr or 25.0 mg/kg, i.v. bolus followed by 12.5 mg/kg/hr infusion for 7 days) significantly reduced infarct volumes and improved neurological deficits in MCA occluded rats 7 days after occlusion. Delayed treatment significantly reduced infarct volume 24 hr after MCA occlusion when MS-153 (25.0 mg/kg, i.v. bolus followed by 12.5 mg/kg/hr infusion for 21 hr) administration was started 3 hr after occlusion. Brain edema was also significantly improved when MS-153 (25.0 mg/kg, i.v. bolus followed by 12.5 mg/kg/hr infusion for 18 hr) administration was started 6 hr after occlusion.

Analysis of Variance↗
PubMed1997

The use of bronchofiberscopy for diagnosis of allergic bronchopulmonary aspergillosis.

To assess the use of bronchofiberscopy for the diagnosis of allergic bronchopulmonary aspergillosis (ABPA), we retrospectively analyzed bronchofiberscopic and pathologic findings of specimens obtained by bronchofiberscopy in 8 patients who met the British criteria for ABPA. Two of the 8 patients completely met Rosenberg's primary criteria for ABPA, while the remaining 6 lacked only 1 or 2 immunologic and radiographic conditions of the criteria. Bronchofiberscopic inspection revealed the presence of mucus plugs in all patients. Pathologic examination of plug specimens obtained by suction from 6 of 7 of these patients showed that the plugs consisted of allergic mucin containing fungal hyphae, diagnostic of ABPA. Bronchofiberscopy appears to be a useful tool in the diagnosis of ABPA, if immunologic and radiographic findings are not typical of ABPA. This bronchofiberscopic method is easily applicable for diagnosing allergic bronchopulmonary fungal disease (ABPFD) in addition to ABPA.

Adolescent↗
PubMed1997

Ventricular hemorrhage at an early stage of moyamoya disease--case report.

A 19-year-old male presented with intraventricular hemorrhage manifesting as sudden onset of headache. Angiography showed mild stenotic changes in the distal internal carotid artery and proximal anterior cerebral artery only on the right. The anterior choroidal artery and lenticulostriate arteries appeared dilated, and an aneurysm-like shadow was seen in the distal right anterior choroidal artery. He was discharged without treatment. Eighteen months later, he presented with a second intraventricular hemorrhage manifesting as sudden occipitalgia, vomiting, and nausea. He had hyperreflexia of the left extremities and paresthesia of the left upper extremity. Angiography showed marked progression of the vascular abnormalities bilaterally. Moyamoya vessels were also present. He received bilateral encephalo-duro-arterio-myo-synangiosis with good results. Moyamoya disease may cause hemorrhage even at an early stage.

Adult↗
PubMed1997

Short-latency somatosensory evoked potentials in patients with brain stem tumor: study of N20 and N18 potentials.

Short-latency somatosensory evoked potentials (SSEPs) elicited by median nerve stimulation were studied in 17 patients with brain stem tumor. A total of 35 SSEP records were obtained and classified into five groups: 13 in Group I, central conduction time (CCT) < 7.56 msec (within the normal limits); eight in Group II, CCT > or = 7.56 msec; nine in Group III, N20 potential was abolished; four in Group IV, N20 and N18 potentials were abolished; and one in Group V, N20, N18, and P14 potentials were abolished. These SSEP groups were correlated with the size and location of the brain stem tumor on magnetic resonance images. N20 potentials were unchanged in latency in patients with small localized gadolinium (Gd)-enhanced lesions. In contrast, the N20 potentials were abolished in patients with tumors extending to the dorsal pons and the upper medulla oblongata. The extent of nonenhanced low-intensity lesion did not correlate with the changes of the N20 potentials. The degree of the impairment of the N20 potentials reflected the severity of the clinical symptoms. The N20 potential can evaluate brain stem dysfunction caused by brain stem tumor. The N18 potentials were abolished in four patients, in whom the tumor extension (one Gd-enhanced lesion, three low-intensity lesions) involved not only the pons but also the medulla oblongata. Therefore, the N18 potentials are probably generated from the medulla oblongata.

Adolescent↗
PubMed1997

Flow cytometric DNA content analysis of ultraviolet light-induced squamous cell carcinomas: a comparative study of squamous cell carcinomas of the lip and those arising from other sites of sun-damaged skin.

The development of squamous cell carcinoma (SCC) of the lip is considered to be mainly related to excessive sun exposure. However, its higher metastatic rate is distinct from that of SCCs arising from other sites of sun-damaged skin. Flow cytometric DNA content analysis, using paraffin-embedded specimens, was performed on 15 SCCs of the lip and 32 SCCs arising from other sites of sun-damaged skin. A significantly lower incidence of DNA-aneuploidy was observed in SCCs of the lip (2/15) than in those of sun-damaged skin (15/32) (p < 0.05). The mean age of patients with SCC of the lip (66.7 +/- 11.6 years; mean +/- SD) was significantly lower than that of the other patients (78.1 +/- 11.1 years) (p < 0.01). There was no significant difference between the mean diameter size of tumors on the lip (19.5 +/- 5.7 mm) and that of tumors on other sites of sun-damaged skin (30.7 +/- 20.5 mm). These results suggest that additional carcinogenic factors besides ultraviolet light may be involved in the development of SCC of the lip.

Adult↗
PubMed1997

MR detection of secondary changes remote from ischemia: preliminary observations after occlusion of the middle cerebral artery in rats.

PURPOSE: To determine whether secondary MR changes occur in the thalamus or the substantia nigra after middle cerebral artery (MCA) occlusion in rats. METHODS: Sprague-Dawley rats were subjected to MCA occlusion. At varying intervals, proton density-, T1-, and T2-weighted images were obtained with a 4.7-T superconductive MR unit. RESULTS: T2-weighted images revealed an area of high signal intensity in the ipsilateral substantia nigra 4 days after occlusion. A lesion of low signal intensity appeared in the ipsilateral thalamus 7 days after surgery on proton density- and/or T2-weighted images. CONCLUSION: MR showed secondary changes in the thalamus and the substantia nigra after MCA occlusion in rats. MR imaging should provide more information on the neuropathology of the delayed neuronal degeneration after cerebral ischemia.

Animals↗
PubMed1997

[Mycetoma-forming pulmonary nocardiosis and endobronchial polypoid lesion].

A 46-year-old man was admitted to the hospital for evaluation of a dense infiltrative shadow in the right middle lung field. Bronchoscopic examination revealed a polypoid lesion in the right middle-lobe bronchus (Bb11(5)). Examination of a biopsy specimen showed a lump with many Nocardia asteroides bacteria. The response to chemotherapy, which included sulfomethoxazole, was poor, and therefore a right middle lobectomy was done. Three mycetomas were found inside the ectatic bronchi in the S5 area. Pulmonary Nocardia mycetoma is rare.

Bronchi↗
PubMed1997

Psoriasis vulgaris coexistent with epidermolysis bullosa acquisita.

Autoimmune bullous diseases, such as bullous pemphigoid or pemphigus vulgaris, occasionally develop in psoriatic patients. In addition, a novel subepidermal bullous disease with autoantibodies against a lower lamina lucida antigen of 200 kDa has recently been reported in association with psoriasis. We describe here a patient with psoriasis vulgaris who developed epidermolysis bullosa acquisita (EBA). Direct immunofluorescence revealed linear deposition of IgG and C3 at the basement membrane zone. The patient's serum bound to the dermal side of salt-split normal human skin. However, immunoblot analysis demonstrated that the patient's serum reacted with an EBA antigen of 290 kDa. EBA should be included in the list of autoimmune diseases associated with psoriasis vulgaris.

Adult↗
PubMed1996

Memantine induces heat shock protein HSP70 in the posterior cingulate cortex, retrosplenial cortex and dentate gyrus of rat brain.

High-affinity N-methyl-D-aspartate (NMDA) receptor antagonists like MK-801 are known to induce the heat shock protein, HSP70, in the posterior cingulate cortex and retrosplenial cortex of rat brain. Memantine, which is a low affinity uncompetitive NMDA receptor antagonist, has been used in the treatment of Parkinson's disease in Europe. The faster kinetics of memantine in blocking and unblocking the NMDA receptor-operated ion channel as opposed to high-affinity NMDA antagonists like MK-801 has been thought to account for the safety of memantine. The present study evaluated the neurotoxic potential of memantine and amantadine using the induction of HSP70 immunoreactivity in rat brain. Memantine (25, 50, 75 mg/kg) induced HSP70 in the posterior cingulate, retrosplenial cortex and dentate gyrus of rat brain. In contrast, amantadine (50, 100, 200 mg/kg) did not induce HSP70 in the rat brain. These results suggest that memantine has an antagonistic effect at NMDA receptor in vivo, and raises the possibility that high doses of memantine may cause neuronal damage similar to those observed with other high-affinity NMDA receptor antagonists.

Animals↗
PubMed1996

Regional distribution of heparin-binding epidermal growth factor-like growth factor mRNA and protein in adult rat forebrain.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a recently described member of the EGF family that binds to and stimulates phosphorylation of the EGF receptor (EGFR). In this study, we examined the cellular localization of HB-EGF gene transcripts and protein in adult rat forebrain. In situ hybridization studies showed that neurons in various regions, including cortex, hippocampus, and deep structures, express HB-EGF mRNA. Positively labeled cells were also present in white matter, which suggests that both neurons and glia express HB-EGF mRNA. Immunohistochemical studies with an antibody specific to proHB-EGF, a transmembrane form of HB-EGF, demonstrated ubiquitous immunoreactivity in neurons and glial cells in white matter. In view of the wide expression of its cognitive receptor, EGFR, in central nervous system neurons, our results suggest that HB-EGF is an endogenous ligand for EGFR in the central nervous system and may play an important role in physiological conditions.

Animals↗
PubMed1996

Inhibition of apoptosis and augmentation of lymphoproliferation in bcl-2 transgenic Fas/Fas ligand-defective mice.

Mice defective in Fas (CD95 or APO-1) or its ligand (lpr or gld mice) develop age-dependent lymphadenopathy and systemic autoimmune disease. T cells accumulating in the lymph nodes of these mice express reduced levels of Bcl-2 protein and are susceptible to spontaneous and glucocorticoid-induced apoptosis. We backcrossed bcl-2 transgenic mice to lpr and gld mice to homozygosity to determine the effects of Bcl-2 overexpression. T cells in these mice were resistant to spontaneous and glucocorticoid-induced apoptosis in vitro. Moreover, the accumulation of CD4(-)CD8(-) T cells in the lymph nodes and the spleens was augmented, suggesting that a Bcl-2-dependent mechanism regulating the number of T cells residing in the peripheral lymphoid organs in addition to the Fas-mediated pathway exists.

Animals↗
PubMed1996

Patterns of growth inhibitory factor (GIF) and glial fibrillary acidic protein relative level changes differ following left middle cerebral artery occlusion in rats.

Growth inhibitory factor (GIF) has been identified as a new metallothionein-like protein, the level of which is decreased in the Alzheimer's disease brain. GIF and glial fibrillary acidic protein (GFAP) have been reported to be expressed in reactive astrocytes in the rat brain following stab wounds. Moreover, strong expression of GIF mRNA in reactive astrocytes after ventricular injection of kainic acid has been demonstrated. To clarify the biological functions of GIF and GFAP in repair of the CNS, we examined changes in their relative levels to sham control using a Western blotting technique in the rat left hemisphere following occlusion of the left middle cerebral artery, for 28 days after surgery. The GIF relative level declined to 56% of the sham-operated control value on day 7. Thereafter the GIF relative level increased and returned to the normal relative level by days 21-28. The GFAP relative level increased from day 3 and reached a maximum of 120% of the sham-operated control value on days 14-21. While GIF and GFAP were both detected in reactive astrocytes, an increase in the GFAP relative level occurred prior to an increase in GIF relative level following the ischemia. The patterns of changes in relative expression levels of GIF and GFAP were quite similar to those in our previous studies on effects of cerebral stab wounds in rats, although the changes were more rapid in the previous studies. GIF and GFAP appear to play different roles in the repair of the CNS. The present results also indicated that GIF could play an important role in CNS repair after cerebral ischemia and provide new insights into the mechanism of gliosis investigated mainly from the viewpoint of GFAP.

Animals↗