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Biomedical subjects

C Koyama

Publications and source records attributed to C Koyama.

18 recordsLinked to original sources
PubMed2001

Enhanced protein levels of protein thiol/disulphide oxidoreductases in placentae from pre-eclamptic subjects.

Recent studies have indicated that pre-eclampsia is closely associated with oxidative stress both in maternal circulation and in the placenta. Protein thiol/disulphide oxidoreductases, such as thioredoxin, glutaredoxin, and protein disulphide isomerase have recently been found to eliminate reactive oxygen species (ROS) and regenerate oxidatively damaged proteins. Protein thiol/disulphide oxidoreductases may also play a role in combating pre-eclampsia. In this study, we examined the accumulation of 4-hydroxy-2-nonenal (HNE)-modified proteins, which are markers of lipid peroxidation, in human placentae of normal and pre-eclamptic subjects. We also examined the protein levels of thioredoxin, glutaredoxin, and protein disulphide isomerase in placentae. Immunoblotting and immunohistochemistry showed that HNE-modified proteins accumulated to a greater extent in pre-eclamptic placentae than in normal placentae. In both normal and pre-eclamptic placentae, thioredoxin, glutaredoxin, and protein disulphide isomerase were detected in the trophoblasts of the floating villi. The levels of these proteins were increased approximately 2- to 3-fold in the pre-eclamptic placentae compared to the normal placentae. These results indicated that the pre-eclamptic placentae were exposed to oxidative stress and that the protein thiol/disulphide oxidoreductases were adaptively induced in pre-eclamptic placentae, suggesting possible roles for thioredoxin, glutaredoxin, and protein disulphide isomerase in protecting placental functions against oxidative stress caused by pre-eclampsia.

Adult↗
PubMed1993

Newly established murine pituitary folliculo-stellate-like cell line (TtT/GF) secretes potent pituitary glandular cell survival factors, one of which corresponds to metalloproteinase inhibitor.

A mouse folliculo-stellate cell (FS cell) line, TtT/GF, was found to secrete a potent survival factor influencing a somatotropic cell line (MtT/S) in serum-free medium. A three-step chromatography purification procedure using heparin-affinity chromatography, anion-exchange chromatography and gel-filtration chromatography revealed that the factor was a 27 kDa protein. Amino-terminal sequence analysis showed that the N-terminal 20 amino acids of the 27 kDa protein corresponded to those of human tissue inhibitor of metalloproteinase-II (TIMP-II). These results indicate that FS cells secrete TIMP-II, which probably protects the composition of the extracellular matrix and acts as a cell survival factor for endocrine cells in the anterior pituitary gland.

Amino Acid Sequence↗
PubMed1993

Pituitary folliculo-stellate-like cell line (TtT/GF) responds to novel hypophysiotropic peptide (pituitary adenylate cyclase-activating peptide), showing increased adenosine 3',5'-monophosphate and interleukin-6 secretion and cell proliferation.

Several studies have shown that folliculo-stellate cells (FS cells) in the anterior pituitary gland exhibit paracrine functions. Recently, we established a pituitary FS-like cell line, TtT/GF, which was derived from an isologously transplantable pituitary thyrotropic tumor line induced by radiothyroidectomy. In studies to examine the function of FS cells, we found that two forms of a novel hypophysiotropic peptide, pituitary adenylate cyclase-activating polypeptide (PACAP), were potent activators of TtT/GF cells. Both the 27- and 38-amino acid forms of PACAP (PACAP-27 and PACAP-38) and vasoactive intestinal peptide (VIP) increased the levels of cAMP in TtT/GF cells in a similar dose-dependent manner. PACAP-27 and PACAP-38 specifically stimulated the proliferation of TtT/GF cells dose dependently, whereas VIP was ineffective. The minimal effective concentration of the PACAPs inducing cell proliferation was between 10(-8)-10(-7) M. However, PACAP-27 was much less potent than PACAP-38 in stimulating cell proliferation and DNA synthesis. PACAP-38, PACAP-27, and VIP all stimulated the release of interleukin-6 (IL-6) from TtT/GF cells. PACAP 38 (10(-8) M) stimulated IL-6 production effectively within 1 h of incubation, and the level attained at 8 h of cultivation (620 pg/ml) was nearly 10-fold that in the absence of PACAP-38 (60 pg/ml). PACAP-38 and VIP stimulated IL-6 secretion significantly at 10(-10)-10(-9) M in a bell-shaped manner; the maximum values were 10(-7) and 10(-8) M, respectively. On the other hand, IL-6 secretion stimulated by PACAP-27 became saturated at 10(-8) M, and the maximum value (320 pg/ml) was about 25% of that stimulated by PACAP-38 (1280 pg/ml). These findings obtained using TtT/GF cells as a model of FS cells suggest that PACAP acts as a hypophysiotropic factor, which targets FS cells and stimulates their proliferation, adenylate cyclase activation, and IL-6 secretion.

Animals↗
PubMed1992

Establishment of a folliculo-stellate-like cell line from a murine thyrotropic pituitary tumor.

An isologously transplantable mouse thyrotropic pituitary tumor (TtTb) that had been induced by radiothyroidectomy was found to form lobules composed of parenchymal glandular cell elements. The surfaces of these lobules were covered by stellate cells bearing long processes that gave a strong immunopositive reaction with a specific antiserum against glial fibrillary acidic protein (GFAP). GFAP was also positive in pituitary folliculo-stellate cells (FS cells). Since in the anterior pituitary gland, no other cellular component showing positive staining with anti-GFAP antibody was observed, it seems probable that the GFAP-positive cells in the thyrotropic tumor are related to the FS cells in the anterior pituitary. Upon cultivation of the thyrotropic tumor, cells with long processes appeared. These cells showed strong staining for GFAP and were dependent on basic fibroblast growth factor for cell growth. By repeated passage, the GFAP-positive cells became a stably growing immortal cell line, which was tentatively named TtT/GF. Since the characteristics of TtT/GF were similar to those of FS cells in the anterior pituitary, i.e. the presence of many lysosomes and numerous intermediate filaments in the cytoplasm, phagocytic activity, follicle formation, and GFAP and S-100 protein positivity, we suggest that TtT/GF cells are derived from pituitary FS cells.

Animals↗
PubMed1988

Effects of cimetidine on lidocaine distribution in rats.

The effects of cimetidine on the disappearance from plasma, plasma protein binding, tissue distribution, tissue binding in vitro and uptake by erythrocytes of lidocaine were studied in rats. The plasma disappearance of lidocaine after a 10 mg/kg bolus injection was analyzed by a two-compartment open model. In the cimetidine-treated rats (50 mg/kg bolus injection, the plasma total body clearance (Cltot), the volume of distribution at the steady state (Vdss) and the elimination rate constant of the central compartment (kel) of lidocaine decreased by 27, 28 and 32% of those of the non-treated rats, respectively. The plasma concentration of lidocaine at the steady state, after a loading dose (7.62 mg/kg body weight) followed by an infusion (0.16 mg/min/kg), increased from 1.62 to 2.69 micrograms/ml after cimetidine treatment. The tissue-to-plasma concentration ratio (Kp) in spleen, stomach and skin decreased to 64, 62 and 62% of the values of the non-treated rats. In addition, the blood-to-plasma concentration ratio (Rb) decreased by 26% in cimetidine-treated rats. In vitro tissue-to-plasma concentration ratios (Kp, vitro) of lidocaine in spleen, stomach and skin homogenate were decreased to 58, 45 and 68% by cimetidine treatment. In these tissues, the percentage decreases of Kp, vitro agreed with those of Kp determined in vivo. The decrease of Kp by cimetidine treatment may be due to the inhibition of tissue binding of lidocaine. The uptake of lidocaine by erythrocytes was decreased by cimetidine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1971

[Hypotension].

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Adrenal Cortex Hormones↗
PubMedDate not supplied

Myxoid leiomyosarcoma of the uterus. Report of a case with cytologic findings.

BACKGROUND: Myxoid leiomyosarcoma is a rare variant of uterine sarcoma, exhibiting malignant biologic behavior despite the absence of cytologic atypia and of significant mitotic activity. CASE: A 20-year-old female was referred with a cystic pelvic mass. At laparotomy, the tumor, weighed 2,200 g and originating in the left lateral uterine wall, was removed. Microscopic examination revealed well-differentiated smooth muscle cells without atypia and with a few mitotic figures in the copious myxoid matrix, suggesting myxoid leiomyosarcoma. Three years following laparotomy, an irregular mass around the uterus was noted on sonographic examination, suggesting local recurrence. Two years and six months later, the second operation was performed, and a locally recurrent, multicystic tumor weighing 3,500 g was excised. The histopathology was similar to that of the primary tumor. Cytologic findings on imprint material from the tumor revealed a few isolated or sheet like small cells consisting of spindle and polygonal cells with round and oval nuclei. Cytologic atypia was also minimal. CONCLUSION: Myxoid leiomyosarcoma should be included in the differential diagnosis of smooth muscle neoplasia.

Adult↗
PubMedDate not supplied

[Controversial aspects in traumatic lesions of the pancreas].

The pancreatic anatomo-functional characteristics explain the traumatic gravidity and the problems in diagnostic. Its lesion is treated surgically, with controversial aspects. In terms of literature and analytic description of a case, were established: the initial course of trauma can be uncharacteristic, with normal amilasemia and abdomen Rx; the ultrasonography can determine the diagnosis; in cases of proximal transection of pancreas, the surgical treatment can include pancreatic derivation, in early operations, under favourable conditions.

Accidents, Traffic↗