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Biomedical subjects

M Taniguchi

Publications and source records attributed to M Taniguchi.

At least 253 records · Page 14Linked to original sources
PubMed1999

Clinical characteristics of upper airway resistance syndrome.

Polysomnographic findings and clinical symptoms were investigated in 14 cases of upper airway resistance syndrome. The mean scores of the Epworth sleepiness scale and self-rating depression scale in eight cases were 13.5 and 38.6, respectively. The mean sleep latency of the multiple sleep latency test in four cases was 10.2 min. Seven cases were treated with continuous positive airway pressure (CPAP), and one with hormone replacement therapy. The most common symptom was daytime sleepiness. Five cases had hypertension. CPAP reduced increasing negative esophageal pressure (Pes) and frequency of EEG arousals, and improved hypertension in one case. Hormone replacement therapy ameliorated increasing negative Pes and clinical symptoms.

Adult↗
PubMed1999

Differential regulation of adenine nucleotide translocators by hypertonicity in the brain.

To determine the gene(s) induced by hypertonicity in the brain, we performed a differential display analysis using RNA isolated from isotonic and hypertonic rat astrocytes. One cDNA rapidly up-regulated by hypertonicity was isolated, and the DNA sequence revealed that it was identical to adenine nucleotide translocator (ANT)2. ANT2 protein exchanges intramitochondrial ATP for cytoplasmic ADP. Among three ANT isoforms, only ANT2 mRNA was up-regulated markedly from 1 to 4 h after exposure to hypertonicity. Induction of the mRNA did not require de novo protein synthesis. Furthermore, ADP translocase activity in mitochondria of astrocytes was increased significantly by hypertonicity. To see the localization and regulation of ANT2 mRNA in the brain, we performed in situ hybridization of rat brain after intraperitoneal injection of a high concentration of NaCl. Although there were only weak signals in the control, intense hybridization signals were seen in hypertonic rat whole brain. Microscopic examination showed that ANT2 signals were present in the neurons, as well as glial cells. These results suggest that ANT2 may play a role in brain cells to adapt to the hypertonic environment.

Adenosine Diphosphate↗
PubMed1999

Neuroprotective role of Na+/myo-inositol cotransporter against veratridine cytotoxicity.

Na+/myo-inositol cotransporter has been shown to protect cells from the perturbing effects of hypertonic stress by the accumulation of myo-inositol. Here we report a regulatory mechanism for the cotransporter. Induction of myo-inositol cotransporter mRNA was observed after exposure to veratridine, a voltage-gated sodium channel opener. The veratridine-elicited induction was inhibited when Na+ was eliminated from the bath, although calcium chelation failed to modify the gene expression. Veratridine evoked an accumulation of Na+ in the cells, which paralleled the abundance of the mRNA. These results strongly suggested that an increase in Na+ influx due to sodium channel opening affected transcription of the cotransporter gene. Activity of the myo-inositol cotransporter was also up-regulated after veratridine exposure. To clarify the possible roles of myoinositol accumulation under veratridine exposure, we next examined the neurotoxic effects of veratridine when myo-inositol uptake was blocked. Neither 30 microM veratridine nor 500 microM 2-O,C-methylene myo-inositol, a competitive inhibitor of myo-inositol, elicited apparent cytotoxicity. However, a combination of these agents markedly increased cytotoxicity in culture, suggesting that an adequate amount of myo-inositol was necessary when the cells were stimulated with veratridine.

Carrier Proteins↗
PubMed1999

Fc receptor beta subunit is required for full activation of mast cells through Fc receptor engagement.

The high-affinity IgE receptor (Fc epsilonRI) and the low-affinity IgG receptor (Fc gammaRIII) on mast cells are the key molecules involved in triggering the allergic reaction. These receptors share the common beta subunit (FcRbeta) which contains an immunoreceptor tyrosine-based activation motif and transduces the signals of these receptors' aggregation. In rodents, FcRbeta is essential for the cell surface expression of the Fc epsilonRI. In humans, the FcRbeta gene was reported to be one of the candidate genes causing atopic diseases. However, the role of FcRbeta in vivo still remains ambiguous. To elucidate the functions of FcRbeta, we developed the mice lacking FcRbeta [FcRbeta(-/-)]. The FcRbeta(-/-) mice lacked the expression of the Fc epsilonRI on mast cells and IgE-mediated passive cutaneous anaphylaxis (PCA) was not induced in FcRbeta(-/-) mice as was expected. In these mice, the expression of IgG receptors on mast cells was augmented but the IgG-mediated PCA reaction was attenuated. Although with bone marrow-derived cultured mast cells from FcRbeta(-/-), adhesion to fibronectin and Ca2+ flux upon aggregation of IgG receptors were enhanced, mast cells co-cultured with 3T3 fibroblasts exhibited impaired degranulation on receptor aggregation. These observations indicate that FcRbeta accelerates the degranulation of mature mast cells via the IgG receptor in connective tissues.

3T3 Cells↗
PubMed1999

A novel recognition motif of human NKT antigen receptor for a glycolipid ligand.

Murine NKT cells can recognize alpha-galactosylceramide (alpha-GalCer) in the context of a class Ib CD1d molecule. Here we show that alpha-GalCer can selectively activate freshly isolated human Valpha24(+)Vbeta11(+) cells, functionally defining the human NKT cells. The naive human NKT cell repertoire consisted of cells expressing an invariant Valpha24JalphaQ chain and a diverse array of beta chains derived from a single Vbeta11 gene segment. Stimulation with alpha-GalCer expanded a polyclonal subset of the human NKT cell repertoire carrying a novel complementarity-determining region (CDR) 3beta consensus motif that may directly interact with the sugar moiety of alpha-GalCer. Our data suggest that certain redundancy is allowed for CDR3beta of NKT antigen receptor to interact with the ligand and provide a first clue to understand the novel protein-carbohydrate interaction mechanisms.

Adult↗
PubMed1999

Target cells for an immunosuppressive cytokine, glycosylation-inhibiting factor.

Receptors for bioactive glycosylation-inhibiting factor (GIF) were demonstrated using a bioactive mutant of recombinant human (rh) GIF, which is comparable to the suppressor T (Ts) cell-derived bioactive GIF in its affinity for the receptors on helper T (Th) hybridoma cells. Both naive T and B cells in normal mouse spleen lacked GIF receptors. However, presentation of specific antigen to naive T cells resulted in the expression of the receptors on activated T cells. Furthermore, activation of small resting B cells with F(ab')2 fragments of anti-mouse IgM plus IL-4, lipopolysaccharide (LPS) plus IL-4 or LPS plus dextran sulfate induced the expression of the receptors within 48 h of B cell stimulation. It was also found that NK T cells freshly isolated from mouse spleen, but not conventional NK cells, expressed receptors for GIF. CD4(+) and CD4(-) subpopulations of NK T cells showed a similar binding capability. Mature dendritic cells derived from bone marrow did not bear the receptors. The dissociation constant (Kd) of the interaction between the bioactive rhGIF mutant and the high-affinity receptors was 10-100 pM, whereas inactive wild-type rhGIF failed to bind to the receptors. A bioactive derivative of rhGIF suppressed both IgG1 and IgE synthesis by purified B cells activated by LPS and IL-4, indicating that the binding of bioactive GIF to its receptors on activated B cells results in suppression of their differentiation.

Animals↗
PubMed1999

Compilation and characterization of Arabidopsis thaliana response regulators implicated in His-Asp phosphorelay signal transduction.

His-Asp phosphorelays are evolutionary-conserved powerful biological tactics for intracellular signal transduction. Such a phosphorelay is generally made up of "sensor histidine (His)-kinases", "response regulators", and "histidine-containing (HPt) phosphotransmitters". In the higher plant, Arabidopsis thaliana, results from recent intensive studies suggested that His-Asp phosphorelays may be widely used for propagating environmental stimuli, such as phytohormones (e.g., ethylene and cytokinin). In this study, we first inspected extensively the occurrence of Arabidopsis response regulators in order to compile and characterize them. The results showed that this higher plant has, at least, 14 members of the family of response regulators that can be classified into two distinct subtypes (type-A and type-B), as judged from their structural designs, biochemical properties, and expression profiles. Comparative studies were conducted for each representative (ARR3 and ARR4 for type-A, and ARR10 for type-B). It was suggested that expression of the type-A response regulator is cytokinin-inducible, while that of the type-B response regulator appears to be not. Results from yeast two-hybrid analyses suggested that the type-B response regulator may have an ability to stably interact with a set of HPt phosphotransmitters (AHPs). These and other results will be discussed with special reference to the His-Asp phosphorelay signaling network in Arabidopsis thaliana.

Amino Acid Sequence↗
PubMed1999

Differential expression of genes for response regulators in response to cytokinins and nitrate in Arabidopsis thaliana.

In Arabidopsis thaliana, a number of response regulators are presumably involved in His-Asp phosphorelay signal transduction in response to environmental stimuli, such as phytohormones. Previously, it was shown that expression of a certain set of genes for response regulators are cytokinin- and nitrate-responsive in their mRNA accumulation, under certain growth conditions [Taniguchi et al. (1998) FEBS Lett. 429: 259, Brandstatter and Kieber (1998) Plant Cell 10: 1009]. To answer the critical question of whether or not other response regulator genes, so far identified in Arabidopsis thaliana, are also cytokinin-inducible, here an extended comparative examination was carried out. It was demonstrated that not all of response regulator genes are necessarily cytokinin-responsive in their transcription. Rather, the members of a certain subfamily (type-A) are cytokinin-responsive, but those belonging to the other (type-B) are not. The presumed nitrate-responsiveness was also assessed for the same set of response regulators, and the analogous view was supported. These results suggest that the two subtypes of response regulators differ from each other, as judged from not only their structural designs, but also the expression profiles of their transcripts in response to plant stimuli.

Arabidopsis↗
PubMed1999

Natural killer T cell ligand alpha-galactosylceramide inhibited lymph node metastasis of highly metastatic melanoma cells.

The role of natural killer T (NKT) cells in the prevention of multiple tumor metastasis was examined. The i.v. inoculation of a highly metastatic subline of B16-BL6 (B16-BL6-HM) melanoma cells resulted in the formation of metastatic nodules in lymph nodes in addition to lung, intrapleural cavity, and ovary. However, treatment of the mice with the NKT cell ligand alpha-galactosylceramide (alpha-GalCer) three times from 1 day after B16-BL6-HM melanoma inoculation caused a significant inhibition of multiple metastasis. Lymph node metastasis of B16-BL6-HM was almost completely blocked by alpha-GalCer treatment. This antimetastatic effect of alpha-GalCer was abolished in NKT cell-deficient mice. These results suggest that alpha-GalCer-activated NKT cells played a critical role in the prevention of lymph node metastasis of melanoma cells.

Adjuvants, Immunologic↗
PubMed1999

Development of REM sleep atonia.

OBJECTIVES: To study the functional development of neuronal systems that suppress muscle activity, we quantified the chronological change of atonia in rapid-eye-movement sleep (REMS). METHODS: REMS atonia was quantified by the tonic and phasic inhibition indices (TII and PII). TII indicates the shortness of chin muscle activity, whereas PII standardizes the simultaneous occurrence of chin muscle activity and bursts of rapid eye movements. TII and PII were calculated in REMS of 135 polysomnographical recordings obtained in healthy humans from premature babies to a 77-year-old man. RESULTS: TII increased significantly with age, while PII decreased significantly. TII reached an adult level at preadolescence, while PII at early infancy. CONCLUSION: Human nervous systems involved in both tonic and phasic inhibition in REMS raise their activities with age. Since TII and PII reach adult levels at different ages, suppression of muscle activity is hypothesized to be mediated through at least 2 independent systems in humans.

Adolescent↗
PubMed1999

Retrograde temporal order amnesia resulting from damage to the fornix.

Some amnesic patients show an impairment of temporal order memory that cannot be accounted for by content memory deficits. The performance of an amnesic patient on memory tasks assessing the patient's content and temporal memories for remotely acquired material is described, after a lesion including the bilateral anterior fornix and adjacent anterior thalamus. The patient displayed a deficit in the temporal order tasks for remotely acquired information. Neither frontal cognitive deficits nor recognition deficits can account for this patient's poor temporal memory. This retrograde temporal order memory impairment without content memory deficits were not seen in previously reported thalamic amnesic patients. Accordingly, the present patient's poor retrograde temporal memory could hardly be explained by only a thalamic lesion. It is concluded that the patient's impairment of temporal order memory for the retrograde material is probably due to the direct disconnection between the frontal lobe and the hippocampus by disruption of the fornix.

Amnesia↗
PubMed1999

Syndrome of inappropriate secretion of antidiuretic hormone associated with idiopathic normal pressure hydrocephalus.

A 79-year-old woman suffering from urinary incontinence and unsteady gait was diagnosed as having idiopathic normal pressure hydrocephalus (NPH) with hyponatremia due to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The concentration of antidiuretic hormone was high while the plasma osmolality was low in the presence of concentrated urine during the episodes of hyponatremia. Magnetic resonance imaging (MRI) of the head showed enlargement of the third and lateral ventricles. After ventriculoperitoneal shunt surgery, the symptoms of NPH and hyponatremia improved. It may be possibly explained that mechanical pressure on the hypothalamus from the third ventricle is responsible for hyponatremia.

Aged↗
PubMed1999

Application of a rigid endoscope to the microsurgical management of 54 cerebral aneurysms: results in 48 patients.

OBJECT: To enhance visual confirmation of regional anatomy, endoscopy was introduced during microsurgery for cerebral aneurysms. The risks and benefits are analyzed in the present study. METHODS: The endoscopic technique was used during microsurgery for 54 aneurysms in 48 patients. Forty-three aneurysms were located in the anterior circulation and 11 were in the posterior circulation. Thirty-eight aneurysms (70.4%) had not ruptured. All ruptured aneurysms in the present series produced Hunt and Hess Grade I or II subarachnoid hemorrhage. After initial exposure achieved with the aid of a microscope, the rigid endoscope was introduced to confirm the regional anatomy, including the aneurysm neck and adjacent structures. The necks of 43 aneurysms were clipped using microscopic control or simultaneous microscopic/endoscopic control. After clipping, the positions of the clip and nearby structures were inspected using the endoscope. Use of the neuroendoscope provided useful information that further clarified the regional anatomy in 44 cases (81.5%) either before or after neck clipping. In nine cases (16.7%), these details were available only with the use of the endoscope. In five cases (9.3%), the surgeons reapplied the clip on the basis of endoscopic information obtained after the initial clipping. There were two cases in which surgical complications were possibly related to the endoscopic procedures (one patient with asymptomatic cerebral contusion and another with transient oculomotor palsy). CONCLUSIONS: It is the authors' impression that the use of the endoscope in the microsurgical management of cerebral aneurysms enhanced the safety and reliability of the surgery. However, there is a prerequisite for the surgeon to be familiar with this instrumentation and fully prepared for the risks and inconveniences of endoscopic procedures.

Adult↗
PubMed1999

HUB1 is an autoantigen frequently eliciting humoral immune response in patients with adult T cell leukemia.

The immunological screening of a cDNA phage expression library prepared from an adult T cell leukemia (ATL) cell line, ST1, was performed with IgG class antibodies in the serum of an ATL patient by the SEREX method to analyze the repertoire of antigen molecules in ATL. Ten different cDNAs, 7 previously reported and 3 newly identified, were isolated. One of the identified cDNAs was homologous to the recently reported gene, HTLV-I U5RE binding protein 1 (HUB1) encoding a protein binding to a possible repressor element of the long terminal repeat of the human T lymphotropic virus type I (HTLV-I). The obtained cDNA was expressed as a fusion protein with glutathione S-transferase. HUB1 protein was prepared by subsequent treatment of the fusion protein with thrombin. Reactivity of IgG serum samples from ATL patients, asymptomatic HTLV-I carriers and normal donors against the purified protein was examined by Western blot analysis. Twenty-one out of 30 samples (70.0%) from ATL patients, 10/24 samples (41.7%) from HTLV-I carriers and 9/24 samples (37.5%) from healthy donors showed positive reactivity, indicating the autoantigenicity of HUB1. The development of ATL may be related to higher production of antibodies against HUB1.

Adult↗