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Biomedical subjects

T Imagawa

Publications and source records attributed to T Imagawa.

At least 73 records · Page 4Linked to original sources
PubMed1997

Morphological and morphometric features of the deformed cervical and caudal vertebrae in a new mutant knotty-tail (knt/knt) mouse.

Morphological and morphometric examinations were conducted on skeletons of knotty-tail (knt/knt) mouse, a new autosomal recessive mutant. The knt/knt mice have short and knotty tails. The number of caudal vertebrae is reduced and their deformed caudal vertebrae show no parallelism between the epiphyseal planes and no osseous fusions. Morphological changes, except for the caudal vertebrae, are confined to the neural arches of the axis in knt/knt mice. As for the tail anomaly, the knt gene seems to have the same action as the tk gene, but knt/knt mice differ from other strains with respect to cervical morphology. The morphometry of the caudal vertebrae revealed that knt/knt mice have a discontinuous and lower ratio of width to length after their 6th caudal vertebra. The morphometry also revealed that knt/knt mice have 1) broadened cervical vertebrae in the transverse direction, 2) thickened ventral lamina of the 6th cervical vertebra and 3) shortened and broadened ventral tuberculum of the atlas. From these results, the knt/knt mouse was considered to be a new pleomorphic mutant.

Animals↗
PubMed1997

Mixed connective tissue disease in childhood: a nationwide retrospective study in Japan.

Sixty-six children with mixed connective tissue disease (MCTD) were analyzed by a nationwide prospective study. The diagnostic significance of Raynaud's phenomenon and positive anti-RNP antibody was confirmed, and additional symptoms including swelling of fingers, facial erythema, and polyarthralgia, and laboratory findings such as positive rheumatoid factor, hypergammaglobulinemia, and increased levels of myogenic enzymes, were variably positive. These clinical and laboratory characteristics of MCTD were critically different from those of systemic lupus erythematosus, indicating that MCTD is an independent entity of disease.

Adolescent↗
PubMed1997

[A case of macrophage activation syndrome developed with systemic juvenile rheumatoid arthritis].

We reported a child of macrophage activation syndrome (MAS) associated with the course of systemic juvenile rheumatoid arthritis (sJRA). The clinical and laboratory findings in our case was ascribed to the overproduced inflammatory cytokines especially TNF-alpha by activated macrophages. Moreover, macrophage-colony stimulating factor (M-CSF) was also elevated in the active phase of the disease, and decreased in the convalescent phase, indicating that M-CSF can be the most potent stimulator of macrophages to produce inflammatory cytokines. Cyclosporine A along with plasmaexchange and corticosteroid, instead of VP16 or other immunosuppresive agents, was effecting in the management of this severe, life-threatening MAS.

Anemia↗
PubMed1996

Generation of cell transfectants expressing cardiac calcium ion channel and calcium indicator protein aequorin.

Chinese hamster ovary (CHO) cells stably coexpressing cardiac calcium ion channel [L-type calcium channel or ryanodine receptor (RyR)] and the calcium-sensitive bioluminescent protein aequorin were generated by transfecting aequorin cDNA. In a selected clone, C1-17, carrying the L-type calcium channel, depolarization induced by high concentration of K+ produces aequorin luminescence. In another clone, R3-7, carrying RyR, caffeine produces aequorin luminescence. In the presence of selective calcium ion channel blockers, the aequorin luminescence was inhibited in a dose-dependent manner. These results indicate that functionally expressed calcium ion channels in these transformants can be monitored through the activation of endogenous aequorin luminescence following a physiological signal similar to that of native calcium channel. Moreover, the aequorin system compared very well with Fura-2 measurements. Thus, the recombinant cell models, which expressed cloned calcium channel and aequorin, will contribute to the elucidation of Ca2+ movement through the cell surface and intracellular calcium ion channels.

Aequorin↗
PubMed1996

Ser-27, Tyr-10 and Tyr-7 in the alpha-chain of pig stomach H+,K(+)-ATPase as Ca(2+)-dependent phosphorylatable sites by intrinsic and extrinsic protein kinases.

When pig stomach membrane H+,K(+)-ATPase preparations were incubated with [gamma-32P]ATP, Mg2+ and Ca2+, reversible phosphorylation of specific Tyr and Ser residues in the N-terminal alpha-chain of H+,K(+)-ATPase occurred without any detectable phosphorylation in other regions of the alpha-chain. Mild tosylphenylalanyl chloromethyl ketone trypsin treatment followed by reverse-phase column chromatography yielded three radioactive peptide peaks. The first peak contained both Tyr10(32P) and Tyr7(32P) and the second peak contained Tyr10(32P). The third peak contained Ser27(32P) which was also obtained after trypsin treatment of partially purified H+,K(+)-ATPase preparations phosphorylated with protein kinase-C + Ca2+ or protein kinase-A. This is the first demonstration of Ca2(+)-dependent phosphorylation of the alpha-chain of H+,K(+)-ATPase by protein kinases.

Amino Acid Sequence↗
PubMed1996

Phosphorylation-dependent regulation of cardiac Na+/Ca2+ exchanger via protein kinase C.

The cardiac Na+/Ca2+ exchanger (NCX1) plays a major role in the extrusion of Ca2+ from cardiomyocytes. We studied the role of protein phosphorylation in the regulation of cardiac NCX1 using CCL39 stably overexpressing the canine cardiac NCX1 and rat neonatal cardiomyocytes. In both cell types, the NCX1 protein immunoprecipitated with a chicken anti-NCX1 antibody exhibited a significant basal phosphorylation that was further enhanced by treatment with endothelin-1, acidic fibroblast growth factor, phorbol 12-myristate 13-acetate, or okadaic acid. In contrast, calphostin C, K252a, or EGTA inhibited the phosphorylation. The phosphorylation occurred on two major tryptic phosphopeptides (P1 and P2) exclusively on serine residues. Evidence is presented suggesting that P2 was derived from an N-terminal half (amino acids 240-475) of the central cytoplasmic domain of NCX1 and was phosphorylated directly by protein kinase C (PKC). The agents that increased NCX1 phosphorylation significantly enhanced both the forward and reverse modes of Na+/Ca2+ exchange. This exchange activation exhibited a very good correlation with the NCX1 phosphorylation. In NCX1-transfected cells, PKC down-regulation following prolonged exposure to phorbol 12-myristate 13-acetate abolished the acidic fibroblast growth factor-induced activation of exchange activity. On the other hand, cell ATP depletion reduced the exchange activity and abolished the effects of the above agents on exchange activity. These results indicate that the cardiac NCX1 is up-regulated by PKC-catalyzed phosphorylation. The cardiac NCX1 thus could play an important role in the previously reported negative inotropic actions of phorbol esters and other PKC-activating agents.

Adenosine Triphosphate↗
PubMed1996

[A case of staphylococcal scalded skin syndrome caused by exfoliative toxin-B producing MRSA].

We experienced a 6 month-old infant who suffered from staphylococcal scalded skin syndrome (SSSS), whose mother used steroid ointment for the infant's erythematous skin rash for 2 days. On the 3rd day, the infant was admitted to our hospital with fever, erythema on the trunk and extremities, and flaccid blisters and erosions at periorificial areas and the neck. Nikolsky's sign was positive. S. aureus was cultured from the throat, conjunctival inflammatory lesion and exudates. The biological characteristics of the isolates were coagulase type I, enterotoxin-nonproducing, TSST-1-nonproducing, protease pattern: D type, and plasmid profile: 563 kbp. The investigation of exfoliative toxin (ET) revealed negative for ET-A but positive for ET-B, proved by polymerase chain reaction (PCR). The isolated strain of S. aureus was demonstrated to be methicillin-resistant (MRSA), which was further defined to be positive for mec A gene by PCR method. It will be possible for such toxigenic ET-B producing MRSA to gain the dominant status in NICU or closed areas.

Base Sequence↗
PubMed1996

The innervation of the chromaffin cells in the head kidney of the carp, Cyprinus carpio; regional differences of the connections between nerve endings and chromaffin cells.

Nerve fibres and their connections with chromaffin cells in the carp head kidney were studied by light and electron microscopy. Some nerve bundles entered the head kidney from the dorsal aspect along veins. Many unmyelinated axons emerged from the nerve bundles to invade the clusters of chromaffin cells, the distribution of which was restricted to the neighbourhood of the venous trunks and their tributaries. Most of the nerve endings were attached to a chromaffin cell by synaptic junctions and were generally invaginated into the cell. Some nerve endings were flattened in shape and connected with two chromaffin cells. Occasional exocytotic figures of synaptic vesicles opening into the intercellular space, or synaptic junctions along the course of the nerve fibre were observed. The percentage of the chromaffin cells supplied by nerve endings in the head kidney as a whole was similar to that in primitive amphibians. The distribution of the chromaffin cells and the frequency of their innervation suggest that carp chromaffin cells are phylogenetically similar to those of amphibians. The frequencies of synaptic connections in the carp head kidney showed regional differences. The number in dorsal portion was significantly higher than that in two ventral portions. It is suggested that chromaffin cells in the head kidney are separable into two populations: one (in the dorsal portion) shows closer and the other (in the ventral portions) less contact with nerve fibres. The fine structure of the nerve endings indicates that catecholamine secretion of carp chromaffin cells is partially modulated by nerve fibres (probably preganglionic cholinergic fibres). However, the low frequency of synaptic connections on the chromaffin cells and their distribution suggest that carp chromaffin cells are mainly modulated by the endocrine system via the bloodstream.

Animals↗
PubMed1996

Morphological studies of the hyalocytes in the chicken eye: scanning electron microscopy and inflammatory response after the intravitreous injection of carbon particles.

Hyalocytes in the pecten oculi and ciliary body of adult chickens and their response to Escherichia coli were investigated by transmission and scanning electron microscopy and the inflammatory response following the intravitreous injection of colloidal carbon examined by microscopy. In normal chickens, the hyalocytes were mainly found on the pleats of the pecten oculi and on the ciliary body. There were no hyalocytes on the retina. There is thus a close relationship between the vasculature in the tissues surrounding the vitreous chamber and the distribution of hyalocytes. The hyalocytes, which were predominantly spindle shaped or oval in contour, displayed a ruffled surface with occasional blebs, filopodia and lamellipodia. Flattened hyalocytes with relatively few and short pseudopodia were frequently observed, especially on the ciliary body. Hyalocytes responded quickly to E. coli bacteria which they phagocytosed. The response to colloidal carbon in the vitreous chamber had 3 distinct changes. In the 1st (2 d after carbon injection), the hyalocytes, the resident macrophages, actively ingested the carbon particles without significant leucocyte recruitment. In the 2nd stage (at 7-14 d), a large number of macrophages infiltrated the ciliary body and emigrated into the vitreous chamber. In the 3rd stage (at 30 d), the infiltration by macrophages into the ciliary body was complete. The carbon-laden macrophages disappeared from the vitreous body but accumulated on the pecten oculi and retina. They were exclusively drained through the scleral venous sinus in the iridocorneal angle.

Animals↗
PubMed1996

The apical caecal diverticulum of the chicken identified as a lymphoid organ.

A peculiar structure, observed as a dome-like protrusion at the apex of the caecum, was investigated macroscopically and histologically in healthy White Leghorn chickens. It was hemispheric or spherical in shape and as it consisted of a lumen with a wall occupied by lymphoid tissue, this structure was designated the apical caecal diverticulum (ACD). ACD were detected in 25.2% of examined chickens and had a mean diameter and height of 1.9 mm and 1.2 mm respectively. Histologically, both the lamina propria mucosae and the submucosa of ACD consisted of well developed aggregated lymphoid nodules. Each nodule was covered by follicle-associated epithelium which contained cells resembling M cells. Some secondary nodules extended into the subserosa. The muscularis mucosae and the stratum circulae of the tunica muscularis disappeared near the entrance to ACD. The stratum longitudinale also gradually decreased in thickness around the entrance, becoming an extremely thin layer in the diverticulum wall. At the caecal apex, each stratum of the tunica muscularis was thinner than in the caecal body and separated into several muscle bundles. These bundles were occasionally displaced by developed lymphoid nodules, causing them to protrude into the subserosa. The high frequency of ACD suggests that caecal apex may be sites for immunological surveillance in the chicken caecum. In addition to the intense and frequent antiperistalsis at the apex suggested by Yasukawa (1959), possible causes for the formation of ACD included (1) the fragility of the tunica muscularis at the ACD, and (2) the local removal of the physical supporting structures by the development of lymphoid nodules.

Animals↗
PubMed1995

Reversible phosphorylation of both Tyr7 and Tyr10 in the alpha-chain of pig stomach H+,K(+)-ATPase by a membrane-bound kinase and a phosphatase.

When pig stomach membrane H+,K(+)-ATPase preparations were incubated with [gamma-32P]ATP and Mg2+ with vanadate, 32P was incorporated into the alpha-chain of H+,K(+)-ATPase to a steady-state level of approximately 0.7 mol of phosphotyrosine (Tyr(P))/mol of phosphoenzyme intermediates. The addition of a membrane H+,K(+)-ATPase preparation with Mg2+ accelerated the liberation of 32P from Tyr(P) residues in the alpha-chain. Mild tosylphenylalanyl chloromethyl ketone-trypsin treatment solubilized 32P-containing peptides from the alpha-chain almost completely. A reverse-phase column chromatography of the supernatant gave two peaks of 32P-peptide with similar total radioactivities. The amino acid sequence of both peaks was shown to be Gly-Lys-Ala-Glu-Asn-Tyr-Glu-Leu-Tyr-Gln--, which is consistent with the amino-terminal sequence of the alpha-chain of H+,K(+)-ATPase deduced from cDNA from pig stomach except that the initial Met was absent. The comparison of the recovery of amino acid from each Edman cycle showed that the phosphorylation of Tyr10 occurred preceding the phosphorylation of Tyr7. These data and others suggested the presence of a novel membrane-bound enzyme system to participate in reversible phosphorylation of both Tyr residues in the alpha-chain of H+,K(+)-ATPase.

Amino Acid Sequence↗
PubMed1995

[A case of tuberculous meningitis followed by tuberculoma with pan-hypopituitarism].

We reported a case who suffered from tuberculous meningitis at 10 months of age, and progressed to basal tuberculoma despite intensive drug therapy with isoniazid, rifampin, and streptomycin. Pan-hypopituitaliam due to basal tuberculoma was effectively replaced by the administration of anti-diuretic hormone (DDAVP) and levothyroxine sodium. Basal tuberculoma was finally removed by surgical operation. Histopathological examination of the tuberculoma revealed Mycobacterium tuberculosis and Langhans giant cells. During the 6 years after the operation, her growth rate was found to be retarded, and the administration of human growth hormone was started. Remarkable catch-up growth was demonstrated. We like to emphasize that infantile tuberculosis, mostly a result of intafamilial transmission, may manifest meningitis in the early phase of the disease, and it sometimes progresses to basal tuberculoma unresponsive to anti-mycobacterial drug therapy.

Child↗
PubMed1995

Sodium orthovanadate increases phospholipase A2 activity in isolated rat fat pads: a role of phospholipase A2 in the vanadate-stimulated release of lipoprotein lipase activity.

Phospholipase (PL) A2 activity prepared from isolated rat fat pads incubated with sodium orthovanadate (vanadate) was increased in a time- and dose-dependent manner. The increasing effect of vanadate was reduced in the presence of tyrosine kinase inhibitors. Under the inhibition of protein synthesis by cycloheximide, vanadate still showed a full effect on the increase in PL A2 activity. Various PL A2 inhibitors, such as manoalide, quinacrine and p-bromophenacyl bromide, suppressed the stimulatory release of lipoprotein lipase (LPL) activity from the fat pads by vanadate. Moreover, the vanadate-stimulated release of LPL activity was decreased by the cyclooxygenase and thromboxane synthetase inhibitors, and a thromboxane A2 receptor antagonist, but was never suppressed by a lipooxygenase inhibitor. The stimulatory release of LPL activity by vanadate was also decreased in the presence of tyrosine kinase inhibitors. These results suggest that vanadate increases PL A2 activity, and the increase in PL A2 activity is partly involved in the vanadate-stimulated release of LPL activity with an association to the membrane tyrosine kinase.

Adipose Tissue↗
PubMed1995

A role of protein kinase C in the alteration of renal glucose-6-phosphatase activity caused by fluoride.

In this study, protein kinase C was demonstrated to operate as a down-regulator of glucose-6-phosphatase in the kidney, at least. Renal glucose-6-phosphatase activity reached a maximum level in 3 h after the administration of fluoride to rats. The incremental increase of renal glucose-6-phosphatase activity caused by fluoride administration was markedly amplified by the administration of staurosporine (66 micrograms/kg, i.p.), which has inhibitory activity against protein kinase C, or by the administration of H-7 (5 mumol/kg, i.p.), a specific and strong inhibitor of protein kinase C. Interestingly, the finding indicated that protein kinase C operates as a down regulator of renal glucose-6-phosphatase activity. The finding was reconfirmed by the result that fluoride-stimulated glucose-6-phosphatase activity was further enhanced by treatment with calphostin C (200 nmol/kg, i.p.), a specific and strong inhibitor of protein kinase C, but the change was small. Moreover, calmodulin was indicated as being possibly concerned with the down regulation of renal glucose-6-phosphatase activity by using W-7 (5 mumol/kg, i.p.), a calmodulin specific inhibitor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗