Search PubMed⌕ Search

Biomedical subjects

C Chiba

Publications and source records attributed to C Chiba.

At least 19 recordsLinked to original sources
PubMed1996

Role of appendix in the development of inflammatory bowel disease in TCR-alpha mutant mice.

T cell receptor-alpha mutant mice (TCR-alpha-/-), created by gene targeting of the TCR-alpha gene in embryonic stem cells, spontaneously develop inflammatory bowel disease (IBD) resembling human ulcerative colitis. Since gut-associated lymphoid tissue is likely to play an important role in the development of chronic intestinal inflammation, we examined the changes in the appendix lymphoid follicle (ALF) and Peyer's patches (PP) in these mice. We found the structure of the ALF to be remarkably similar to that of the PP in the small intestine; in both instances, lymphoid follicles covered by surface epithelium (dome-formation) were found. The amount of proliferation in the lymphoid follicles of the appendix estimated by in vivo incorporation of 5-bromo-2'deoxyuridine was more than two times that of PP in TCR-alpha-/- mice. ELISPOT assay showed an increase of IgA, IgG1, and IgG2a, but not IgM-secreting B cells in ALF of TCR-alpha-/- mice compared to TCR-alpha+/- control mice. Furthermore, TCR-alpha-/- mice revealed an increase of autoantibody-producing B cells against the cytoskeletal protein tropomyosin in ALF as compared to PP. When TCR-alpha-/- mice underwent appendectomy at a young age (3-5 wk), the number of mesenteric lymph nodes cells at 6-7 mo were markedly less than in the sham-operated TCR-alpha-/- mice. Furthermore, appendectomy at 1 mo of age suppressed the development of IBD, with only 3.3% of these mice developing IBD in the 6-7-mo period of observation. In contrast, approximately 80% of controls, including the sham-operated TCR-alpha-/- mice, developed IBD during this period. These results suggest that ALF, rather than PP, is the priming site of cells involved in the disease process and plays an important role in the development of IBD in TCR-alpha-/- mice.

Animals↗
PubMed1996

Cytokine imbalance and autoantibody production in T cell receptor-alpha mutant mice with inflammatory bowel disease.

Spontaneous inflammatory bowel disease (IBD) resembling human ulcerative colitis develops in mice mutant for the T cell receptor alpha gene (TCR-alpha-/-). TCR-alpha-/- mice lack TCR-alpha/beta+ cells but contain TCR-gamma/delta+ cells and a small population of a unique CD4+, TCR-alpha-/beta+(low) cells. Since all the immunoglobulin (Ig) classes are present in these mice, help to B cells must be provided by cells other than TCR-alpha/beta+ cells. In the present study, we found serum levels of IgG1 and IgG2 to be markedly increased in TCR-alpha-/- mice with IBD as compared to TCR-alpha-/- mice without IBD or TCR-alpha+/- controls. An increase in IgG1-, IgG2a- and IgA- but not IgM-secreting mesenteric lymph node (MLN) B cells was detected in TCR-alpha-/- mutant mice. There was also a marked increase in MLN B cells secreting autoantibody (IgG) to tropomyosin, a cytoskeletal protein. Examination of the hyperplastic MLN showed a marked increase in the number of B, TCR-delta+, and CD4+ TCR-alpha-/beta+ cells, similar to the cell population observed at the site of colonic inflammation. Analysis of spontaneous cytokine production by MLN cells using an enzyme-linked immunospot assay, immunohistochemistry, and reverse transcription/polymerase chain reaction showed a decrease of interleukin 2 (IL-2) but a marked increase of IL-4 and interferon gamma (IFN-gamma) production in TCR-alpha-/- mice with IBD as compared to TCR-alpha-/- mice without IBD and TCR alpha+/- control mice. Both TCR-alpha-/beta+ and TCR-delta+ cells were found to be capable of producing IL-4; IFN-gamma was produced mostly by non-T cells, many of which were shown to be CD3- NK 1.1+ cells. We propose that the cytokine imbalance present in these mice results in expansion of B cells, production and switching of autoantibodies to IgG2 subclass, and development of IBD. It is possible that the unusual CD4+ TCR-alpha-/beta+ population and expanded TCR-gamma/delta+ population present in TCR-alpha-/- mice plays a central role in this abnormal immune response.

Animals↗
PubMed1995

Development of interleukin 6 and tumor necrosis factor alpha activity in nasopharyngeal secretions of infants and children during infection with respiratory syncytial virus.

Cytokine (interleukin 6 [IL-6] and tumor necrosis factor alpha [TNF-alpha]) activity in nasopharyngeal secretions of 21 infants and children (19 days to 16 months old) infected with primary respiratory syncytial virus was determined by an enzyme-linked immunosorbent assay. IL-6 and TNF-alpha were detectable in 100% (21 of 21) and 67% (14 of 21) of cases during the course of infection, respectively. Generally, TNF-alpha activity was high in the acute phase and declined thereafter, sometimes to undetectable levels. IL-6 activity was also highest in the acute phase and declined thereafter in infants younger than 5 months, while in patients older than 5 months, it-increased during the course of the disease to peak in the early convalescent phase. These observations suggest that inflammatory cytokines are produced in vivo in infants and children in response to primary respiratory syncytial virus infection and may be involved in disease pathogenesis. However, the mechanism of induction of cytokines may be different for infants and children in different age groups.

Antibody Specificity↗
PubMed1995

Responses mediated by excitatory and inhibitory amino acid receptors in solitary spiking cells from normal newt retina.

Whole-cell currents activated by L-glutamate, kainate (KA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA), N-methyl-D-aspartate (NMDA), gamma-aminobutyric acid (GABA), and glycine were recorded from spiking cells enzymatically dissociated from adult newt retina. Most spiking cells responded to both AMPA and KA. KA tended to be a more potent agonist for them than AMPA. The reversal potential of both AMPA and KA responses was about -7 mV; this value was similar to that (about -5 mV) of glutamate response. AMPA- and KA-induced currents may be carried by monovalent cations, such as Na+, because their reversal potentials were sensitive to external Na+. About half of the spiking cells examined responded to mixtures of NMDA and glycine. Extracellular Mg2+ blocked completely the response to NMDA plus glycine in spiking cells held at negative membrane potentials, but not at positive membrane potentials. Almost all spiking cells responded to the inhibitory amino acids GABA and glycine. Dose-dependent desensitization was observed in both GABA and glycine responses. Currents activated by GABA and glycine were carried by Cl-. Bicuculline and strychnine strongly suppressed the responses to GABA and glycine, respectively, suggesting the existence of GABAA receptors and conventional glycine receptors in the spiking cells.

Amino Acids↗
PubMed1995

Development of responses to excitatory and inhibitory amino acids in spiking cells during retinal regeneration in the adult newt.

Responsiveness to amino acids in solitary spiking cells dissociated from regenerating newt retinae at different stages were studied by whole-cell patch-clamp methods in comparison with that in the normal retina. Cells from regenerating retinae of 1-2 cell thickness ("early" stage) lacked the receptors for kainate (KA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA), N-methyl-D-aspartate (NMDA), gamma-aminobutyric acid (GABA), and glycine. AMPA/KA, NMDA, GABAA, and glycine receptors, each of which were electrophysiologically and pharmacologically similar to those in the normal retina, appeared in spiking cells before regenerating retina had segregated into two synaptic layers. During subsequent regeneration stage, the time course of appearance of amino acid receptors seems to be different between excitatory and inhibitory ones. Cells which responded to GABA and glycine gradually increased in number to normal levels, and the current amplitude induced by these amino acids also increased monotonically. The number of cells responding to the excitatory amino acids appeared to be maximal at a period of synaptic segregation. During subsequent regeneration, however, cells responded to AMPA and NMDA decreased in number and returned to the number of cells in the normal retina, while cells which responded to KA were maintained at the same number as those in the normal retina. The amplitudes of the current induced by excitatory amino acids also became maximal at a period of synaptic segregation. During subsequent regeneration, AMPA- and KA-induced currents declined to the normal level, while NMDA-induced currents were maintained.

Action Potentials↗
PubMed1994

APB (2-amino-4-phosphonobutyric acid) activates a chloride conductance in ganglion cells isolated from newt retina.

In vertebrate retinae, APB (2-amino-4-phosphonobutyrate) selectively activates glutamate receptors of ON-bipolar cells. Thus, APB has been used as a pharmacological tool for studying the functional retinal circuitry and the inputs to higher-order pathways of the visual centres. Direct action of APB on ganglion cells has not previously been demonstrated. We now report, using whole-cell patch-clamp recordings, that APB has a direct inhibitory effect on ganglion cells isolated from newt retina. APB-induced currents were dependent upon the intracellular Cl- concentration. Their reversal potential values agreed with theoretical values of Cl- equilibrium potential. Strychnine, a glycine receptor blocker, inhibited the APB response. These results may suggest that APB activates the Cl- channels of ganglion cells through glycine receptors.

Aminobutyrates↗
PubMed1993

Development of voltage-gated currents in newt retinal neuroblasts in culture.

Neuroblasts dissociated from early regenerating newt retina (18-20 days after surgery) survived in culture and extended neurites. They were classified into three groups on the basis of neurite outgrowth patterns; monopolar, bipolar, and multipolar varieties. Freshly dissociated neuroblasts (3-15 h in culture) were characterized by slow-rising action potentials with long duration, mediated by inward Na+ currents. After a few days in culture, these cells produced much briefer action potentials mediated by the characteristic Na+, Ca2+ and K+ currents of ganglion cells dissociated from normal retina. The results suggest that neuroblasts in early regenerating retina differentiate in vitro into spiking cells, possibly ganglion cells, characterized by their morphology and voltage-dependent ionic currents.

Action Potentials↗
PubMed1992

Glutamatergic motoneurons in the stomatogastric ganglion of the mantis shrimp Squilla oratoria.

1. Transmitters of motoneurons in the stomatogastric ganglion (STG) of Squilla were identified by analyzing the excitatory neuromuscular properties of muscles in the posterior cardiac plate (pcp) and pyloric regions. 2. Bath and iontophoretic applications of glutamate produce depolarizations in these muscles. The pharmacological experiments and desensitization of the junctional receptors elucidate the glutamatergic nature of the excitatory junctional potentials (EJPs) evoked in the constrictor and dilator muscles. The reversal potentials for the excitatory junctional current (EJC) and for the glutamate-induced current are almost the same. 3. Some types of dilator muscle show sensitivity to both glutamate and acetylcholine (ACh) exogenously applied. The pharmacological evidence and desensitization of the junctional receptors indicate the glutamatergic nature of neuromuscular junctions in these dually sensitive muscles. The reversal potentials for the EJC and for the ACh-induced current are not identical. 4. Glutamate is a candidate as an excitatory neuro-transmitter at the neuromuscular junctions which the STG motoneurons named PCP, PY, PD, LA and VC make with the identified muscles. Kainic and quisqualic acids which act on glutamate receptors are potent excitants of these muscles. Extrajunctional receptors to ACh are present in two types of the muscle innervated by LA and VC. 5. Neurotransmitters used by the STG motoneurons of stomatopods are compared to those of decapods.

Acetylcholine↗
PubMed1991

Mechanisms underlying burst generation of the pyloric muscle in the mantis shrimp, Squilla oratoria.

The pyloric constrictor muscles of the stomach in Squilla can generate spikes by synaptic activation via the motor nerve from the stomatogastric ganglion. Spikes are followed by slow depolarizing afterpotentials (DAPs) which lead to sustained depolarization during a burst of spikes. 1. The frequency of rhythmic bursts induced by continuous depolarization is membrane voltage-dependent. A brief depolarizing or hyperpolarizing pulse can trigger or terminate bursts, respectively, in a threshold-dependent manner. 2. The conductance increases during the DAP response. The amplitude of DAP decreases by imposed depolarization, whereas it increases by hyperpolarization. DAPs from successive spikes sum to produce a sustained depolarizing potential capable of firing a burst. 3. The spike and DAP are reduced in amplitude by decreasing [Ca]o, enhanced by Sr2+ or Ba2+ substituted for Ca2+, and blocked by Co2+ or Mn2+. DAPs are selectively blocked by Ni2+, and the spike is followed by a hyperpolarizing afterpotential. 4. The spike and DAP are prolonged by intracellular injection of the Ca2+ chelator EGTA. A hyperpolarizing afterpotential is abolished by EGTA and enhanced by increasing [Ca]o. The DAP is diminished in Na(+)-free saline and reduced by tetrodotoxin. 5. It is concluded that the muscle fiber is endowed with endogenous oscillatory properties and that the oscillatory membrane events result from changes of a voltage- and time-dependent conductance to Ca2+ and Na+ and a Ca2+ activated conductance to K+.

Animals↗
PubMed1990

Social preference of female gerbils (Meriones unguiculatus) as influenced by coat color of males.

Female gerbils (Meriones unguiculatus) of three distinct coat colors (agouti, black, and sandy or pink-eyed dilution) were tested in a Y-maze whose arms led to compartments containing unfamiliar male gerbils of varying coat colors. The stimulus animals were separated from the females by a Plexiglas door. The trials lasted for 2 min and each female was exposed to the following four combinations: two males of the same coloring as the female; one male of the same color and another of a different color from the female; both males of different color from the female. The number of crossings to the left and right arms was relayed by photocells to an IBM PC computer. The results indicate that agouti females preferred visiting the arm occupied by agouti males while those of the other coat colors showed no preference for the "wild-type" males. Instead, sandy and black female gerbils preferred to be in proximity with those of non-wild types.

Animals↗
PubMed1983

Benign familial neonatal convulsions.

A pedigree of so-called benign familial neonatal convulsions was reported. Nine members experienced convulsions in the neonatal period and/or in early infancy. All members except one had good prognosis. One member had mild mental retardation and epilepsy with rolandic EEG foci. It was suggested that some common genetic factors may be involved in the etiology of benign familial neonatal convulsions, convulsions of unknown etiology in infancy (Fukuyama) and epilepsy with rolandic EEG foci. A review of literature revealed that about 14% of cases with benign familial neonatal convulsions eventually developed epilepsy.

Adolescent↗
PubMed1983

[Experimental and clinical evaluation of cefotetan in pediatrics].

Basic and clinical studies on cefotetan (CTT) were carried out and the results were as follows: Absorption and excretion Two patients were given 10 mg/kg of CTT by one shot intravenous injection. At 30 minutes after injection, mean serum level was 76.5 micrograms/ml and the half-life time was 2.3 hours. Mean 6-hour urinary recovery in same patients was 57.5%. Clinical evaluation Forty-two patients were treated with CTT, in doses of 19.2-102.9 mg/kg divided 2-4 times per day for 3-10 days intravenously. Responses were excellent in 14, good in 23, fair in 1, poor in 4, and the overall efficacy rate was 88.1%. As to adverse reaction, urticaria was observed in 1 patient. Abnormal laboratory data noted were elevation of GOT in 1, GOT and GPT in 2, creatinine in 1, and eosinophilia in 3 patients.

Adolescent↗
PubMed1983

[Clinical evaluation of cefpiramide in pediatrics].

Cefpiramide (CPM) is a newly developed cephalosporin. Clinical studies on this drug were carried out and the results were as follows; Forty-three patients (purulent lymphadenitis 2, cellulitis 2, purulent otitis media 1, purulent tonsillitis 3, acute bronchitis 2, pneumonia 22, bronchiectasis 1, urinary tract infection 10) were treated with CPM, in doses of 20 approximately 82 mg/kg divided 2 approximately 4 times per day for 3 approximately 11 days intravenously. The overall efficacy rate was 83.7%. As to adverse reaction, 4 cases, which includes 3 cases of diarrhea and 1 case of exanthema, were observed. Abnormal laboratory data noted were liver dysfunction in 3 cases (6.8%), and eosinophilia in 2 cases (4.5%).

Adolescent↗
PubMed1982

[Basic and clinical studies on cefmenoxime in pediatric field].

Cefmenoxime (CMX) is a newly developed cephalosporin. Basic and clinical studies on this drug was carried out and the results were as follows. 1. Serum level and urinary recovery A 7 years old male was administered 10 mg per kilogram of CMX by one shot intravenous injection. Serum levels were 23.3 micrograms/ml at the time of 15 minutes after injection, 12.0 micrograms/ml at 30 minutes, 3.9 micrograms/ml at 1 hour, 2.0 micrograms/ml at 2 hours, and 0.3 micrograms/ml at 4 hours. In this same patient, 6-hour urinary recovery was 54.7%. 2. Clinical evaluation and adverse reaction Thirty-seven patients (upper respiratory infection 4, pneumonia 20, pyothorax 1, purulent lymphadenitis 1, cellulitis 2, sepsis 1 and urinary tract infection 8) were treated with CMX in doses of 30 approximately 212 mg/kg divided 3 approximately 4 times per day for 1.5 approximately 21 days intravenously. The overall efficacy rate was 94.6%. As to adverse reaction, exanthema and drug fever were observed in 1 patient respectively. Abnormal laboratory data noted were eosinophilia in 2.3%, and elevation of serum transaminase in 9.8%.

Cefmenoxime↗