Biomedical subjects

T Tabira

Publications and source records attributed to T Tabira.

At least 109 records · Page 6Linked to original sources

PubMed1993

Effect of growth factors and cytokines on expression of amyloid beta protein precursor mRNAs in cultured neural cells.

We analyzed the effect of several growth factors and cytokines on the expression of amyloid beta protein precursor (APP) mRNAs in cultured mouse neuronal and glial cells. In neuronal cultures from embryonic day-15 brain. Northern blotting revealed that APP mRNAs increased by 1.3- to 2.6-fold when treated with nerve growth factor, basic fibroblast growth factor, interleukin 1, interleukin 2, interleukin 3, interleukin 6 or granulocyte-macrophage colony-stimulating factor but not with tumor necrosis factor alpha. An S1 nuclease protection assay revealed that the enhanced APP mRNA in neuronal cultures was exclusively APP695 mRNA. On the other hand, astrocyte-enriched cultures prepared from postnatal day-2 brain did not show any significant alteration among these factors. We conclude that certain growth factors and cytokines could enhance APP 695 mRNA expression in neurons in vitro.

Amyloid beta-Protein Precursor↗

PubMed1993

Neurite promoting activity of collagens on embryonic neurons: decreased effect at the postnatal stage.

We studied the in vitro neurite outgrowth activity of fibronectin, laminin, heparan sulfate proteoglycan, type I collagen, type IV collagen, and type VIII collagen in cholinergic neuronal cell lines and primary cultured neurons. All these substances had high neurite promoting activity on primary cultured neurons from embryonic mouse brain. However, collagens had no such an effect on primary cultured neurons from postnatal brain. When neuronal cell lines were used, collagens and other extracellular matrix substances were equally and highly effective on cells originated from embryonic brain, but collagens were less effective on cells from postnatal brain. These findings suggest that postnatal neurons lose the neuritic responsiveness to collagens earlier than that of other ECM.

Animals↗

PubMed1992

Constitutive expression of 65-kDa heat shock protein (HSP65)-like immunoreactivity in cultured mouse oligodendrocytes.

The expression of mycobacterial 65-kDa heat shock protein (HSP65)-like immunoreactivity in cultured mouse oligodendrocytes and astrocytes was investigated using three monoclonal antibodies (ML30, IA1, 3A) specific for the mycobacterial HSP65. In western blot analysis, these antibodies recognized the proteins with molecular weights approximately of 50-, 60-, and 70-kDa expressed in both heat-stressed and unstressed glial cells. When the cells were exposed to heat stress, the expression of both 50- and 70-kDa proteins was attenuated, whereas that of the 60-kDa protein was not affected. On immunocytochemical studies, an appreciable level of HSP65 immunolabelling was identified in most (> 90%) oligodendrocytes under both heat-stressed and unstressed conditions but only marginally detectable in most (> 95%) astrocytes. These results indicate that mouse oligodendrocytes in vitro express the mycobacterial HSP65-like immunoreactivity constitutively.

Animals↗

PubMed1992

Stress induces neuronal death in the hippocampus of castrated rats.

Whereas loss of CA3 neurons in the hippocampus of monkeys which died of stress ulcers suggests that some structural changes may occur, there is no direct evidence that shows stress-induced irreversible changes of neurons. When rats were orchidectomized (castrated) and stressed by restraint and immersion in water for 15 min/day for 30 days, significant loss of hippocampal CA3 and CA4 neurons was observed. Furthermore, primary cultured hippocampal neurons survived shorter when treated with corticosterone. This neuronal loss was prevented by simultaneous administration of testosterone in vivo and in vitro. These findings indicate that stress can contribute to neuronal degeneration associated with hypogonadal conditions such as aging.

Androstanols↗

PubMed1992

Heterogeneous induction of 72-kDa heat shock protein (HSP72) in cultured mouse oligodendrocytes and astrocytes.

The expression of 72-kDa heat shock protein (HSP72) in cultured mouse oligodendrocytes and astrocytes exposed to heat shock was investigated by double immunolabelling with anti-HSP72 monoclonal antibody (C92F3B-1) and antibodies against galactocerebroside (GalC) or glial fibrillary acidic protein (GFAP). After 3 h recovery from heat shock, an intermediate level of HSP72 immunolabelling was localized in the nucleolus and cytoplasm of astrocytes (less than 25%) and to a lesser extent in oligodendrocytes (less than 2%). After 8-48 h, HSP72 was expressed intensely in the cytoplasm and nuclear matrix of oligodendrocytes (20-40%), while weak/intermediate immunostaining was detectable in astrocytes (5-15%). The levels of HSP72 expressed in oligodendrocytes and astrocytes decreased around 72-120 h, but a few oligodendrocytes (4%) remained intensely immunolabelled. These results indicate that heat shock induces HSP72 in both oligodendrocytes and astrocytes. However, this response is heterogeneous.

Animals↗

PubMed1992

Potentially amyloidogenic, carboxyl-terminal derivatives of the amyloid protein precursor.

The 39- to 43-amino acid amyloid beta protein (beta AP), which is deposited as amyloid in Alzheimer's disease, is encoded as an internal peptide that begins 99 residues from the carboxyl terminus of a 695- to 770-amino acid glycoprotein referred to as the amyloid beta protein precursor (beta APP). To clarify the processing that produces amyloid, carboxyl-terminal derivatives of the beta APP were analyzed. This analysis showed that the beta APP is normally processed into a complex set of 8- to 12-kilodalton carboxyl-terminal derivatives. The two largest derivatives in human brain have the entire beta AP at or near their amino terminus and are likely to be intermediates in the pathway leading to amyloid deposition.

Amyloid↗

PubMed1992

Neuroblastoma x spinal cord (NSC) hybrid cell lines resemble developing motor neurons.

We have developed a series of mouse-mouse neural hybrid cell lines by fusing the aminopterin-sensitive neuroblastoma N18TG2 with motor neuron-enriched embryonic day 12-14 spinal cord cells. Of 30 neuroblastoma-spinal cord (NSC) hybrids displaying a multipolar neuron-like phenotype, 10 express choline acetyltransferase, and 4 induce twitching in cocultured mouse myotubules. NSC-19, NSC-34, and their subclones express additional properties expected of motor neurons, including generation of action potentials, expression of neurofilament triplet proteins, and acetylcholine synthesis, storage, and release. In addition, NSC-34 cells induce acetylcholine receptor clusters on cocultured myotubes, and undergo a vimentin-neurofilament switch with maturation in culture, similar to that occurring in neuronal development. NSC cell lines appear to model selected aspects of motor neuron development in an immortalized clonal system.

Acetylcholinesterase↗

PubMed1992

Coexistence of cholinergic, catecholaminergic, serotonergic, and glutamatergic neurotransmitter markers in mouse clonal hybrid neurons derived from the septal region.

Two clonal immortalized neurons designated SN6.1b and SN6.2a were isolated by limiting dilution from a mouse embryonic septal cholinergic neuronal hybrid cell line SN6 (Hammond et al., 1986). In the serum-containing medium without extra differentiating agents, one-third of SN6.1b cells stably exhibited a morphology of differentiated neurons with extensive elaborate neurites, while a majority of SN6.2a cells, along with the parent cell line SN6, were round in shape with poorly branched short processes. Neurochemical studies showed that both clones synthesized choline acetyltransferase (ChAT), dopamine, norepinephrine, serotonin, and glutamate. Immunocytochemically, they expressed a number of neuronal antigens, such as 200-kDa neurofilament protein, neuron-specific enolase, microtubule-associated protein 2, tau protein, tubulin, neural cell adhesion molecule, Thy-1.2, saxitoxin-binding sodium channel protein, ChAT, tyrosine hydroxylase, serotonin, and glutamate. The coexistence of cholinergic, catecholaminergic, serotonergic, and glutamatergic neurotransmitter markers in the clonal hybrid septal neurons that express a variety of immunocytochemical properties of differentiated neurons suggests that embryonic septal cholinergic neurons are potentially multiphenotypic with respect to neurotransmitter synthesis.

Amino Acids↗

PubMed1992

Establishment of mouse-immortalized hybrid clones expressing characteristics of differentiated neurons derived from the cerebellar and brain stem regions.

Two clonal immortalized neurons designated CL8c4.7 and CL8a5.2 were established by somatic cell fusion between a hypoxanthine phosphoribosyltransferase-(HPRT-) deficient neuroblastoma N18TG2 and newborn mouse cerebellar/brain stem neurons. In the serum-containing medium without extra differentiating agents, both clones exhibited a morphology of differentiated neurons. They contained high levels of glutamate but no gamma-aminobutyric acid (GABA). The CL8a5.2 clone synthesized choline acetyltransferase and serotonin. In immunocytochemical studies, both clones expressed 200 kD neurofilament protein, neuron-specific enolase, microtubule-associated protein 2 (MAP2), tau protein, neuronal cell adhesion molecule (N-CAM), HNK-1, Thy-1.2, saxitoxin-binding sodium channel protein, and glutamate. Synaptophysin immunoreactivity was identified in the neuritic terminals of CL8c4.7 cells. Most of these antigens were barely detectable on N18TG2 cells. Electrophysiologically, both clones generated action potentials in response to electrical stimuli. The hybrid clones that express characteristics of differentiated neurons derived from the cerebellar and brain stem regions might be invaluable for the study of the molecular basis of neuronal differentiation and degeneration in these regions.

Amino Acids↗

PubMed1992

Cerebral cortical amyloid protein precursor mRNA expression is similar in Alzheimer's disease and other neurodegenerative diseases.

The expression of 3 beta-amyloid protein precursor (APP) mRNAs (695, 751, and 770) in the cerebral cortex in Alzheimer's disease and other neurodegenerative diseases was analyzed by the S1 nuclease protection assay. We found no significant Alzheimer's disease-specific alteration of APP mRNA expression when compared to the other neurological diseases as controls. Since the expression of this mRNA was not correlated with amyloid deposition, it is possible that gliosis/neuronal loss may secondarily alter APP mRNA expression. However, the current study revealed no significant correlation between them.

Adult↗

PubMed1991

Alzheimer's disease amyloid beta-clipping enzyme (APP secretase): identification, purification, and characterization of the enzyme.

Alzheimer's disease (AD) is the most frequent cause of dementia, although no genetic abnormality has been identified. Recent studies have elucidated the molecular defect in AD, including the abnormal deposition of amyloid beta peptide (beta/A4) in senile plaques of affected individuals. Normal brain contains the enzyme, APP secretase, which cleaves inside the beta/A4 portion of the precursor protein (APP); abnormal processing of APP occurs in AD brain. Until now, no evidence has been provided that APP secretase is an intracellular proteinase. We have now prepared two synthetic substrates of APP secretase, both of which contain the cleavage point and are much more sensitive than substrates previously available to identify APP secretase. Using these substrates, we found an intracellular proteinase that has APP secretase activity. This proteinase has been identified as cathepsin B.

Alzheimer Disease↗

PubMed1991

Parvalbumin-immunoreactive neurons in the human central nervous system are decreased in Alzheimer's disease.

Immunohistochemical localization of the Ca(2+)-binding protein parvalbumin (PV) was investigated in the adult human central nervous system (CNS). The antiserum against purified rat skeletal muscle PV specifically recognized certain neuronal populations and their processes. Strongly positive were Purkinje, basket and stellate cells of the cerebellum, cerebral cortical nonpyramidal cells, and neurons in the thalamic reticular and ventrolateral nuclei, subthalamic nucleus, lateral and medial geniculate bodies, vestibular and cochlear nuclei, spinal trigeminal nucleus, cuneate and gracile nuclei, and dorsal nucleus of Clarke. Negative were cortical pyramidal neurons, neurons of the autonomic nerves, and neurons in the caudate nucleus, putamen, dentate nucleus, inferior olive, and substantia gelatinosa. The number and size of PV-immunoreactive neurons were significantly decreased in Alzheimer's disease. However, the decrease was not disease specific.

Adult↗

PubMed1991

Cytotoxic and suppressor activities in patients with HTLV-I-associated myelopathy.

Since there are several immune abnormalities and autoimmune-like features in human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/HTLV-I-associated tropical spastic paraparesis (HAM/TSP), we examined cytotoxic and suppressor cell functions in HAM/TSP. In this study, we assayed cell-mediated cytotoxicity of CD8+ T-cell lines established from cerebrospinal fluid lymphocytes of two patients with HAM and concanavalin A-induced suppressor cell activities of peripheral blood lymphocytes from five patients with HAM. Our study revealed that three of four CD8+ T-cell lines showed cytotoxic activities against autologous CD4+ T-cell lines infected with HTLV-I, and two of the three lines showed major histocompatibility complex class I-restricted cytotoxicity. We also demonstrated that the concanavalin A-induced suppressor function was not defective in HAM patients. Therefore, the immune abnormalities and autoimmune-like features observed in HAM/TSP may not result from defective cytotoxic or suppressor cell activities.

Adult↗

PubMed1991

HLA-DRB1, -DQA1, -DQB1, -DPA1 and -DPB1 genes in Japanese multiple sclerosis patients.

Japanese MS patients and controls were examined for the distribution of HLA-DRB1, -DQA1, -DQB1, -DPA1 and -DPB1 alleles using in vitro amplification of genomic DNA and probing with sequence-specific oligonucleotides. No significant difference in frequency of the examined alleles was observed among the two groups. This is in contrast to Norwegian MS patients, where an association to a combination of certain DQA1 and DQB1 alleles has previously been demonstrated.

Alleles↗

PubMed1990

Trophic effect of granulocyte-macrophage colony-stimulating factor on central cholinergic neurons in vitro.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) elevated choline acetyltransferase (ChAT) activities of mouse septal neurons as well as of cholinergic hybridoma line cells SN6.10.2.2 in vitro. It augmented ChAT activities and neurite extension of interleukin 3-activated cholinergic neurons. Thus, GM-CSF should be added as a trophic factor for central cholinergic neurons.

Animals↗

PubMed1990

Developmental and differential expression of beta amyloid protein precursor mRNAs in mouse brain.

S1 nuclease analysis was used to determine the levels and patterns of three beta amyloid protein precursor (BPP) mRNAs in mouse developmental brain and in primary neuronal and glial cultures. BPP695 mRNA lacking the Kunitz proteinase inhibitor (KPI) domain was detected exclusively in neuronal cultures and increased considerably in late embryonic and early postnatal periods. On the other hand, BPP751 and 770 mRNAs with KPI domain were detected predominantly in astrocyte- and microglia-enriched cultures and increased slightly only in embryonic stages. These results suggest that the product of each BPP mRNA may play a different role in the brain.

Alzheimer Disease↗

PubMed1990

Association of a particular amino acid sequence of the HLA-DR beta 1 chain with HTLV-I-associated myelopathy.

Analyses of HLA-DRB1 gene using polymerase chain reaction and sequence-specific oligonucleotide probes reveal that the amino acid sequence Glu-Gln-Arg-Arg-Ala-Ala-Val at positions 69-75 of the third hypervariable region (HVR) of HLA-DR beta 1 chain is significantly associated with HTLV-I-associated myelopathy (HAM). Since the frequency of this sequence in HTLV-I carriers is almost the same as that in controls from Kagoshima (an endemic area of HTLV-I), this sequence may be related to susceptibility to HAM rather than to susceptibility to HTLV-I infection. Since this third HVR functions as putative antigen-binding sites and T cell recognition sites, the amino acid sequence of positions 68-73 was analyzed in detail. The analysis reveals that Gln70 and Arg71 are relevant to the occurrence of HAM.

Alleles↗

PubMed1990

Lymphokine production by encephalitogenic and non-encephalitogenic T-cell clones reactive to the same antigenic determinant.

Among the myelin basic protein (MBP)-specific T-cell clones mediating experimental allergic encephalomyelitis (EAE), which were established from SJL/J mice, one clone was found to have lost its encephalitogenicity during long-term passages in vitro, although the clone keeps its specific reactivity to the encephalitogenic determinant lying in the sequence of guinea pig MBP 89-101. To clarify the difference between the encephalitogenic T-cell clone (4b.14a) and non-encephalitogenic T-cell clone (4b.14a/n), we examined various lymphokines secreted into the culture media of 4b.14a and 4b.14a/n. The results show that the activities of lymphotoxin, interferon-gamma or interleukin-2 were not different between encephalitogenic clones and 4b.14a/n, whereas the activity of tumor necrosis factor-alpha, possibly secreted from antigen-presenting cells, was higher in culture media of 4b.14a/n. Moreover, the culture fluid of both 4b.14a/n and 4b.14a revealed suppressive effect on the proliferation of 4b.14a stimulated by MBP 89-101, but the effect was not different between the two clones. Thus, it is suggested that neither production of lymphokines examined so far nor soluble suppressive substance is related to the loss of encephalitogenicity of the T-cell clone.

Animals↗