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T Chiba

Publications and source records attributed to T Chiba.

At least 415 records · Page 23Linked to original sources
PubMed1993

Erythropoietin receptor binds to Friend virus gp55 through other membrane components.

Direct interactions of Friend spleen focus-forming virus glycoprotein gp55 with either erythropoietin receptor (EpoR) or interleukin (IL)2 receptor beta chain (IL2R) (but not with IL3 receptor) have been reported to induce factor-independent prolonged proliferation of erythroid or lymphoid cells. In order to clarify the molecular mechanism by which EpoR-gp55 complex transmits an aberrant growth signal in the absence of erythropoietin, various chimeric receptors constituted with IL2R, EpoR or IL3 receptor were constructed. It was found that coexpression of gp55 and the chimeric receptors containing the cytoplasmic domains of EpoR and the extracellular domains of IL3 (or IL2) receptor in IL3-dependent Ba/F3 cells results in factor-independent growth. Since gp55 in cell membrane has only a two amino acid tail in the cytoplasmic domains and thus cannot interact with EpoR in cytoplasm, our data suggest that gp55 does not bind EpoR directly but interacts with EpoR through third membrane component(s).

Animals↗
PubMed1993

Respiratory suppression by focal cooling of ventral medullary surface in anesthetized rats; functional and neuroanatomical correlate.

Bilateral cooling of the parapyramidal region in the rostral ventral medullary surface (VMS) elicited a reduction in respiratory frequency and phrenic inspiratory activity in halothane anesthetized rats. A distinct cluster of neurons (nucleus parapyramidalis superficialis) was found in a superficial layer (10-15 microns from the surface) just beneath the area where cooling produced suppression of respiration. The rat VMS layer contains neural substrates which regulate the respiratory rhythm generation and inspiratory neural output.

Anesthesia↗
PubMed1993

Tyrosine kinase activation through the extracellular domains of cytokine receptors.

Interaction of cytokines with their membrane receptors induces the proliferation and differentiation of a specific lineage of haematopoietic progenitors. The molecular mechanism of cytokine receptor-mediated signal transduction is unclear because these receptors do not have tyrosine kinase activity. Interleukin-3 and erythropoietin, however, induce transient tyrosine phosphorylation of a common set of proteins as a growth signal, and interleukin-2 induces phosphorylation of an overlapping but distinct set of proteins. Here we show that chimaeric receptors consisting of the extracellular domains of the erythropoietin receptor and the cytoplasmic domains of the interleukin-2 (or interleukin-3) receptor induce an erythropoietin-dependent tyrosine phosphorylation in interleukin-3-dependent Ba/F3 cells; however, chimaeric receptors composed of the extracellular domains of the interleukin-2 receptor and the cytoplasmic domains of the erythropoietin (or interleukin-3) receptor apparently transmit an interleukin-2-dependent signal. Our results indicate that these cytokines transmit distinct signals for activation of specific tyrosine kinases through the extracellular rather than cytoplasmic domains of the receptors.

Amino Acid Sequence↗
PubMed1993

Application of polymer beta-cyclodextrin-treated fetal calf serum to in vitro antibody production.

In order to induce an optimal plaque-forming cell response to sheep red blood cells (anti-SRBC PFC response) in vitro, murine splenocytes have been cultured in RPMI 1640 medium containing 10% fetal calf serum (FCS). In this paper, we report that 10% intact FCS in such a conventional medium can be replaced by 2% modified FCS which has been exposed to insoluble polymer beta-cyclodextrin (CD). The most efficient procedure of treatment of FCS was an incubation of 1/50 diluted FCS with 20 mg/ml polymer beta-CD for 3.5 h at 20 degrees C. The PFC response supported by 2% polymer beta-CD-treated FCS, was the same as that obtained when mixing 10% FCS, and was completely dependent on the existence of antigen (SRBC) and enhanced by 2-mercaptoethanol. The time-course profiles of the PFC responses induced in both cultures were almost the same. The 2% polymer beta-CD-treated FCS-containing medium was also effective in inducing both a primary PFC response to the T cell-independent antigen (trinitrophenyl-lipopolysaccharide) and a polyclonal PFC response stimulated by lipopolysaccharide. Inactive FCS lots (so called deficient lots) also became fully supportive at 2% after treatment with polymer beta-CD. These results indicate that polymer beta-CD-treated FCS is not economical for supporting antibody production, but also useful for those experiments on isolation and analysis of factors derived from cultured lymphocytes.

Animals↗
PubMed1993

Characterization of gastrin/CCK receptors on gastric carcinoid tumor membrane of Mastomys natalensis.

Recently, we identified the specific binding site for gastrin on the gastric carcinoid tumor of Mastomys (Praomys) natalensis. In this study, precise characterization of the gastrin binding site on these tumors was performed. Both 125I-human gastrin I (gastrin) and 125I-CCK-8 bound specifically to the cell membrane, and Scatchard analysis revealed a high affinity binding site for each ligand with similar Kd and Bmax values. The specific binding of both 125I-gastrin and 125I-CCK-8 was displaced in a concentration-dependent manner by various related peptides with a relative potency order of CCK-8 > or = gastrin < des(SO3)CCK-8. In addition, L364,718 as well as L365,260 displaced the binding of both ligands with similar potencies. Furthermore, not only gastrin but also CCK-8 increased [Ca2+]i in these tumor cells, the action of both being inhibited by L364,718 as well as by L365,260 (10(-7) M). These results suggest that the carcinoid tumor of Mastomys possesses a high affinity gastrin/CCK binding site coupled to the increase of [Ca2+]i.

Animals↗
PubMed1993

Cytomegalovirus mononucleosis--associated gastric ulcers in normal host.

A case of cytomegalovirus (CMV) mononucleosis associated with gastric ulcers is reported in a normal non-immunocompromised host. The demonstration of intranuclear inclusion bodies in a few gastric glandular epithelial cells contributed to the diagnosis of CMV gastritis. Extraction of DNA from the gastric biopsy specimens and the amplification of CMV-DNA by the polymerase chain reaction (PCR) showed the presence of CMV-DNA in the gastric mucosa. In situ hybridization with a probe derived from CMV genomic regions demonstrated the numerous glandular cells with CMV-DNA at the nuclear region. Treatment with a proton pump inhibitor to suppress gastric acid secretion was useful to mitigate the epigastralgia and to hasten the ulcer healing. The value of highly sensitive PCR and the in situ hybridization method to detect the CMV-DNA were emphasized for rapid and sensitive diagnosis of CMV gastritis.

Adult↗
PubMed1993

High prevalence of hepatitis B and C viral markers in Japanese patients with hepatocellular carcinoma.

In order to assess the etiologic role of hepatitis C virus (HCV) as well as hepatitis B virus (HBV) in the etiology of HCC, we compared the prevalence of HCV-related antibodies (anti-C100-3, anti-CP9, anti-CP10) and HBV-related markers (HBsAg, anti-HBs, anti-HBc) in sera of patients with liver cirrhosis (LC) with (n = 62) and without (n = 54) hepatocellular carcinoma (HCC). In HBsAg-negative cases, at least one HCV-related marker (including HCV RNA) was detected in 92.3% (48/52) of HCC cases and in all of the 44 LC cases without HCC, with no significant difference between these two groups. In HBsAg-positive cases, the prevalence of either one of these HCV-related markers was 40.0% (4/10) both in patients with and without HCC, and there was no significant difference between these two groups. Moreover, in HBsAg-negative cases and 11 cases of positive HCV-related markers, the prevalence of anti-HBs and/or anti-HBc was significantly higher in LC patients with HCC (85.4%) than those without HCC (43.2%, P < 0.001). These results show a high prevalence of hepatitis B and C viral markers in Japanese patients with HCC and further indicate that previous HBV infection is a risk factor in the occurrence of HCC in HBsAg-negative LC and LC with positive HCV-related markers.

Carcinoma, Hepatocellular↗
PubMed1993

Membrane properties and dendritic arborization of the intermediolateral nucleus neurons in the guinea-pig thoracic spinal cord in vitro.

The morphological and electrophysiological properties of neurons in the intermediolateral nucleus (IML) were studied in the transverse and longitudinal slice of guinea-pig thoracic spinal cord (T2-T3) using intracellular staining and recording techniques. Two morophologically different types of neurons were observed: fusiform cells with craniocaudally oriented dendrites, and multipolar cells with dendrites diffusely extending in the IML. The ratio of fusiform to multipolar cells was 4:1. The fusiform cells were identified as sympathetic preganglionic neurons (SPNs) by their antidromic responses to stimulation of the ventral root exit zone, while the multipolar cells were not antidromically activated by stimulation of this site. Both cell types showed similar resting membrane potential and input resistance. The tonic responses of these neurons to hyperpolarizing current pulses were characteristically different: the SPNs had a marked hyperpolarizing sag at the break of the pulse, caused by an A current, while the unidentified neurons showed no A current. In addition, the SPNs had much longer duration of spike and afterhyperpolarization, as well as lower frequency of spontaneous or current-evoked firing, than the unidentified neurons. These observations suggest that, in the absence of the criterion of antidromic activation by stimulation of the axon, it is still possible to differentiate SPNs from other IML neurons on the basis of morphological and electrophysiological properties of the neuron.

Animals↗
PubMed1993

Phosphate-activated glutaminase immunoreactive synapses in the intermediolateral nucleus of rat thoracic spinal cord.

A monoclonal antibody against phosphate-activated glutaminase was used to identify glutamatergic neuronal components in the intermediolateral nucleus of the thoracic spinal cord of the rat. Under electron microscopy of the intermediolateral nucleus, most glutaminase immunoreactivity was detected in the axoplasm surrounding spherical synaptic vesicles in the presynaptic axon varicosities which formed asymmetric synapses with small dendrites and occasionally with neuronal cell bodies. About 40% of axon varicosities within the intermediolateral nucleus and 49% of the axon varicosities forming asymmetric synaptic contacts showed glutaminase immunoreactivity. Glutaminase immunoreactivity was further seen in mitochondria of neuronal perikarya and dendrites in the intermediolateral nucleus, and occasionally in the cytoplasm of the dendrites and glial processes in the vicinity of glutaminase-immunoreactive axon varicosities. By the combined method of immunocytochemistry and retrograde axonal transport, glutaminase-immunoreactive axons were shown to make direct synaptic contacts with the preganglionic sympathetic neurons, which were retrogradely labeled by injection of horseradish peroxidase conjugated with choleratoxin B subunit into the superior cervical ganglion. The present results indicate that glutaminase-containing axons are the major synaptic inputs to intermediolateral nucleus neurons including preganglionic sympathetic ones, suggesting that glutamate is used as the neurotransmitter to control those neurons in the intermediolateral nucleus.

Animals↗
PubMed1993

Distinct receptors for cholecystokinin and gastrin on canine fundic D-cells.

Despite the extensive amino acid homology between gastrin and cholecystokinin (CCK) at the biologically active carboxyl terminus, the receptors through which these peptides exert their action are heterogeneous. In previous studies, we have examined the biological activity of gastrin/CCK peptides on isolated canine fundic D-cells and observed that CCK is a more potent and efficacious stimulant of somatostatin release than gastrin. We performed the present studies to distinguish between distinct CCK (CCK-A subtype) and gastrin (CCK-B/gastrin subtype) receptors on canine D-cells. Consistent with this observation was our finding that the CCK-A receptor selective antagonist L-364,718 dose dependently (10(-11)-10(-7) M) inhibited CCK-mediated somatostatin release but at the same doses did not alter the effect of gastrin. CCK and gastrin exhibited similar potency in displacing bound 125I-labeled Leu15 gastrin-17 from D-cells. However, when 125I-CCK octapeptide (CCK-8) was used as the radioligand, a fraction of the bound label could not be displaced with gastrin, but this fraction was completely displaced with CCK-8. In D-cells pretreated with high concentrations of gastrin, L-364,718 was able to inhibit the gastrin-resistant fraction of 125I-CCK-8 binding, but the CCK-B/gastrin receptor selective antagonist (PD 134308) was unable to influence this fraction of binding in doses as high as 10(-6) M. These studies delineate the presence of distinct CCK-A and CCK-B/gastrin receptors on canine fundic D-cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Homologous desensitization of histamine H2 receptors in the human gastric carcinoma cell line MKN-45.

The poorly differentiated human gastric carcinoma cell line MKN-45 possesses histamine H2 receptors, which are linked to stimulation of adenosine 3',5'-cyclic monophosphate (cAMP) production. Pretreatment of MKN-45 cells with histamine elicited a rapid and dose-dependent inhibition of cAMP production in response to subsequent administration of histamine, whereas pretreatment with prostaglandin E2 (PGE2) or forskolin, both of which stimulate cAMP formation in these cells, had no effect on the histamine-induced cAMP production. Neither NaF- nor forskolin-induced cAMP production was affected by histamine pretreatment. Scatchard analysis of data obtained for [3H]-tiotidine binding showed that histamine pretreatment affected neither the number of histamine H2 receptors nor the binding affinity of the ligand for the receptors. Finally, histamine pretreatment had no effect on cAMP response to subsequent addition of PGE2, which was reduced by PGE2 pretreatment. These results suggest that histamine induces homologous desensitization of H2 receptors on MKN-45 cells by a mechanism that does not involve stimulation of cAMP production.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Cellular hypertrophy and hyperplasia of airway smooth muscles underlying bronchial asthma. A 3-D morphometric study.

In order to study whether hyperplasia or hypertrophy of cells is responsible for the thickening of airway muscles, 3-D morphometry of airway muscle cells was performed on resin-embedded semithin serial sections of autopsied lungs from 10 asthmatics and five control subjects. There were five Type I and five Type II asthmatic lungs, as defined in an earlier study, thickened muscles being found only in the central bronchi in Type I and distributed over the whole airway tree in Type II. The analysis was based on "unbiased" 3-D morphometry to obtain the numerical density NV of muscle cells using a "disector," a spatial probe introduced by Sterio in 1984, which we modified into a stack of serial sections. The mean number NL of cells per unit airway length and the mean volume Vc of a single muscle cell were also determined. In Type I asthmatics, the number of cells increased in the larger bronchi unaccompanied by cellular hypertrophy at any level of the airway tree. In contrast, in Type II asthmatics, hypertrophy was shown to prevail over the whole airway, but it was most remarkable in the bronchioles, whereas hyperplasia was mild and localized only in the bronchi. The two types of asthmatic lungs may therefore result from different pathogeneses.

Adult↗
PubMed1993

Involvement of CD8+ T cells in delayed-type hypersensitivity responses against bovine leukemia virus (BLV) induced in sheep vaccinated with recombinant vaccinia virus expressing BLV envelope glycoprotein.

Delayed-type hypersensitivity responses against bovine leukemia virus (BLV) envelope glycoprotein (gp60) were induced in the skin of sheep vaccinated with recombinant vaccinia virus (RVV) expressing BLV glycoprotein. The lesions were characterized by marked infiltration of lymphocytes, slight migration of neutrophils, eosinophils, and macrophages in the dermis to hypodermis, and partial intercellular edema in the reticular layer. Immunohistochemical analysis with monoclonal antibodies demonstrated that the lymphocytic infiltrates consisted mainly of CD8+ T cells (53.7-55.8% at 48 hours post-challenge of BLV), CD4+ T cells (24.7-26.7%), and B cells (11.5-16.9%). The role of CD4+ and CD8+ T cells in suppressing BLV growth in RVV-vaccinated animals is discussed.

Animals↗
PubMed1993

Calcitonin gene-related peptide: a neurotransmitter involved in capsaicin-sensitive afferent nerve-mediated gastric mucosal protection.

Calcitonin gene-related peptide (CGRP), a potent vasodilating peptide, is present in primary afferent neurons of the gastric mucosa. However, its functional role in the stomach is not well established. The present study was undertaken to elucidate the involvement of gastric CGRP in the mechanism of protection against mucosal damage. Newborn Wistar rats were made CGRP-deficient by intraperitoneal injection of a sensory neurotoxin, capsaicin. All the experiments were performed 2.5 months after birth. The formation of mucosal lesions by administration of indomethacin to CGRP-deficient rats was significantly enhanced in comparison with that in normal rats. Intragastric administration of capsaicin significantly reduced the indomethacin-induced gastric mucosal lesions in normal rats. Pretreatment with a CGRP antagonist abolished the protective action of intragastric capsaicin against damaging agents. In isolated perfused stomach from normal rats, acute arterial infusion of capsaicin significantly reduced the perfusion pressure of the left gastric artery, with a simultaneous increase in CGRP and somatostatin secretion. The reduction of perfusion pressure and the increase of somatostatin secretion were inhibited by concomitant administration of a CGRP antagonist. In contrast, capsaicin infusion had no effect in CGRP-deficient rats. These results suggest that CGRP in the stomach plays a pivotal role in protection against gastric mucosal damage by indomethacin, possibly through an increase in gastric blood flow and somatostatin secretion.

Afferent Pathways↗
PubMed1993

Development of neoglycoproteins conjugated with natural oligosaccharides through carboxyl residues of proteins and its application to recombinant human interleukin 1.

In order to develop glycosylated cytokines, neoglycoproteins were synthesized utilizing naturally occurring oligosaccharides. High mannose type oligosaccharide-asparagine (Asn)s, containing Man8GN2-Asn, Man7GN2-Asn and Man6GN2-Asn, were obtained from quail ovalbumin and were coupled to bovine serum albumin (BSA) by carbodiimide-mediated coupling. Major reaction occurred between amino residues of oligosaccharide-Asns and carboxyl residues of BSA. Approximately one molecules of oligosaccharides-Asns were coupled to per molecule of BSA with 50% yield of glycosylation. Among the oligosaccharides, Man6GN2-Asn appeared to be conjugated predominantly. While this strategy was applied to recombinant human interleukin 1 alpha (IL-1 alpha), three molecules of oligosaccharide-Asns were introduced into per molecule of IL-1 with 10% yield of glycosylation.

Animals↗
PubMed1993

Gastrin/CCK-B receptors on brain, gastric parietal cells and ECL carcinoid tumor of Mastomys natalensis.

Cholecystokinin (CCK)-8 and human gastrin I (gastrin) were found to be almost equipotent in displacing the specific binding of not only 125I-CCK-8 but also 125I-gastrin to both ECL carcinoid tumor and parietal cell membranes of Mastomys natalensis. These binding specificities of the native gastrin receptors for CCK-8 and gastrin were identical to that of the cloned gastrin receptor from the ECL carcinoid tumor expressed on CHO-K1 cells. In contrast, CCK-8 was approximately 10-20 times as potent as gastrin in inhibiting the binding of the two radioligands to the Mastomys brain membrane. However, the nucleotide sequences of RT-PCR products of mRNAs extracted from not only the isolated parietal cells but also the brain were identical to that of the gastrin receptor cDNA from the ECL carcinoid tumor. Thus, the gastrin receptors on the parietal cells and the brain appear to be encoded by the same gene as those on the ECL carcinoid tumor in Mastomys. The reason for the difference in binding characteristics between the cloned gastrin receptor and the native gastrin/CCK-B receptor in the brain remains to be elucidated.

Animals↗
PubMed1993

[Learning processing in an epileptic with amnesia after memory task repetition].

We reported that some learning accomplished by an epileptic patient (YS) with organic amnesia after memory task repetition. YS's learning appeared inflexible; That was depending memory task procedural. The purpose of this paper is to investigate procedural learning processing in YS with memory disorder. We examined procedural learning in picture naming task repetition in YS and normal controls, using semantic priming paradigm. After start key press, a prime picture was displayed on the CRT display, thereafter, a target picture appeared. The subjects' task was to name the target picture aloud as rapidly and accurately as possible. In the examination, we manipulated a time interval between start key press and the prime on. Two interval conditions were used. One was the constant interval, 1010ms and another was varied interval, varied between 400ms and 1010ms. After conditioning session with constant interval, the test session with constant and varied interval was carried out. We analyzed reaction time (RT) in naming the picture targets in the test session in relation to the conditions. YS's RT in the test session with constant was shorter than in the test session with varied interval. No interval effects were found in the controls. The results indicated that previous experiment in conditioning session had larger effect on the YS's performance than the controls'. This suggests hypotheses that the learning in the patient with amnesia is tied to the specific conditions in the learning experience. The results can be explained in terms of procedural learning in YS, which is automatic processing.

Adult↗