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C Ban

Publications and source records attributed to C Ban.

At least 37 records · Page 2Linked to original sources
PubMed1994

Structure of the recombinant Paramecium tetraurelia calmodulin at 1.68 A resolution.

The crystal structure of the recombinant calmodulin from Paramecium tetraurelia (rPCaM, M(r) = 16 700, 148 residues) has been determined at 1.68 A resolution. X-ray intensity data were collected at 263 K using a Siemens-Nicolet area detector and Cu Kalpha radiation from a rotating-anode source. A total of 35 936 observations were processed with XENGEN1.3 and scaled to yield 16 255 unique reflections with R(symm)(I) of 4.1%. The crystals are triclinic, with unit-cell dimensions a = 29.89, b = 53.42, c = 25.35 A, alpha = 93.67, beta = 96.88, gamma = 89.24 degrees, space group P1, with one molecule in the unit cell. The atomic coordinates of the wild-type Paramecium calmodulin (PCaM) studied in our laboratory provided the starting model. Refinement of the structure by X-PLOR and refitting it into omit maps yielded an R value of 0.194 for 15 965 reflections greater than 3sigma(F) in the 6.0-1.68 A resolution range. The final model contained 1165 protein atoms for all of the 148 residues, four Ca(2+) ions, and 172 water molecules. The dumbbell structure has seven alpha-helices including a long 7.8 turn central helix connecting the two terminal domains each containing two EF-hand (helix-loop-helix motif) calcium-binding sites. The loops within each pair of EF-hand motifs in the N- and C-terminal domains are brought into juxtaposition to form a pair of hydrogen-bonded antiparallel beta-sheets which are extended at either ends by water bridges. The four calcium-binding EF-hands are superposable with r.m.s. deviations of 0.31-0.79 A. The best agreement is between site 1 and site 3 and the worst agreement is between site 1 and 4. The largest differences are in the ninth and tenth residues of the calcium-binding loops probably because of their involvement in the mini beta-sheets. The calcium coordination distances vary between 2.04 and 2.69 A, average 2.34 A. The rPCaM and wild-type PCaM have an r.m.s. deviation of 0.36 A for equivalent C(alpha) atoms. The side chains of Lys13 and Lys115 are more extended in rPCaM compared to the wild type where the post-translational modified di- and tri-methylated lysine residues are more folded. The sequence of PCaM differs from those of mammalian (MCaM) and Drosophila calmodulin (DCaM), but the overall structures are very similar, with r.m.s,. deviations of 0.44 and 1.68 A for equivalent C(alpha) atoms, respectively. However, in rPCaM, the first four N-terminal residues stretch out and make intermolecular crystal contacts, in contrast to those in recombinant Drosophila calmodulin (rDCaM), they stretch out in the opposite direction and towards the second calcium-binding site (see note below), while in MCaM and wild-type PCaM, the N-terminal residues are not visible. The central helix in rPCaM has all its backbone hydrogen bonds intact with no unusually long separation between the carbonyl and amide groups as found in MCaM and rDCaM.

Journal Article↗
PubMed1991

Antibody removal therapy used successfully at delivery of a pregnant patient with Glanzmann's thrombasthenia and multiple anti-platelet antibodies.

A 31-year-old Japanese woman with Glanzmann's thrombasthenia became pregnant voluntarily. She had had transfusions with more than 60 units for severe bleeding. She had multiple antibodies against HLA antigens and platelet glycoprotein IIb/IIIa. No compatible platelets were available. To prevent serious hemorrhage during her delivery, antibody removal therapy was carried out three times. Large molecules including immunoglobulins were removed from more than 3 liters of plasma each time. After the titer of antiplatelet antibodies had decreased in the patient's blood, antihuman globulin-lymphocyte cytotoxicity test compatible platelets were transfused. Her bleeding time improved and delivery was induced successfully despite atonic hemorrhage of about 2,000 g of blood. Her infant had no bleeding problems. This patient is the first with Glanzmann's thrombasthenia to receive antibody removal therapy at delivery.

Adult↗
PubMed1991

The involvement of platelet-activating factor in thrombocytopenia and follicular rupture during gonadotropin-induced superovulation in immature rats.

To investigate whether the platelets in the ovaries are activated by the action of platelet-activating factor (PAF) during gonadotropin-induced ovulation, we examined the changes in the platelet count in immature rats after administration of PMSG followed 48 h later by human CG (hCG). The platelet count in the inferior vena cava was significantly decreased 48 h after PMSG administration and was further decreased after hCG administration. When both ovaries of rats were extirpated, the administration of PMSG and hCG did not decrease the platelet count. Subcutaneous administration of a PAF antagonist, Y24180 (0.5-5 mg/kg.6 h), after PMSG injection decreased the number of ova shed in a dose-dependent manner. The decrease in the platelet count induced by the administration of PMSG and hCG was reversed to the level of the untreated control group by Y24180 (2.5 mg/kg.6 h). This inhibitory activity of Y24180 on ovulation and thrombocytopenia was completely reversed by the ip injection of synthetic PAF. Subcutaneous administration of indomethacin (IDM) also reduced the number of ova shed in a dose-dependent manner. However, thrombocytopenia was not reversed by IDM. Moreover, the inhibition of ovulation by IDM was not reversed by synthetic PAF. The present study suggests that: 1) platelets are activated by PAF during gonadotropin-induced ovulation in immature rats; 2) PAF is also involved in the rupture of follicles; 3) the presence of the ovary is indispensable for the generation of PAF in gonadotropin-stimulated immature rats; and 4) the mechanism of PAF action on ovulation may be different from that of prostaglandins.

Animals↗
PubMed1990

[Levels of CA130 in maternal sera and amniotic fluid at various gestational ages].

We examined the CA130 concentration in the amniotic fluid, maternal sera, amnion, chorion, decidua and placenta. CA130 in the maternal sera showed an initial increase during early pregnancy, remained low from the 15th weeks of pregnancy until delivery, and then increased after term delivery (249u/ml, mean, n = 27) or mid-trimester abortions (844u/ml, n = 22). The CA130, concentration in the amniotic fluid was high in the mid-trimester and remarkably low at term. Among the tissues examined, amnion and decidua contained a relatively high concentration of CA130. Immunohistochemical examination also demonstrated abundant CA130 in the cytosol of amnion and decidua tissues. The pattern of changes in CA130 in amniotic fluid was similar to that in the amnion and decidua tissue. The results suggest that the amnion cells are the source of CA130 in the amniotic fluid and that the high concentration of CA130 in maternal serum after delivery originates in decidua tissue affected by the separation of the placenta.

Amnion↗
PubMed1989

Immunohistochemical localization and tissue levels of tumor-associated glycoproteins CA 125 and CA 19-9 in the decidua and fetal membranes at various gestational ages.

To investigate the sources and biologic significance of CA 125 and CA 19-9 in amniotic fluid, immunohistochemical and biochemical localization of these tumor-associated glycoproteins in the decidua and fetal membranes was studied. Immunohistochemically, CA 125 and CA 19-9 were localized in the cytoplasm of decidua cells and amnion epithelial cells but not in the chorion and placental tissue. Biochemically, the 12,000 X g supernatant fractions of decidua and amnion tissues contained relatively large amounts of CA 125 and CA 19-9, 73% to 96% of which was present in the cytosolic fractions of these tissues. The CA 125 levels in the amniotic fluid decreased, whereas those of CA 19-9 increased with gestation, which correlated well with the respective levels in amnion tissues. These findings suggest that amnion cells produce and secrete these glycoproteins into the amniotic cavity. However, it is possible that the decidua also secretes CA 125 into the amniotic cavity through the chorion and amnion such as in the case of prolactin.

Amniotic Fluid↗
PubMed1989

Mechanism and clinical significance of elevated CA 125 levels in the sera of pregnant women.

To clarify the mechanism of CA 125 elevation in maternal sera, serum levels of CA 125 and CA 19-9 were measured in 122 apparently healthy pregnant women (fifth to fortieth week of gestation) and 50 postpartum women (26 term deliveries and 24 second-trimester induced abortions). Serum levels of CA 125 showed an initial increase by the tenth week and then decreased to less than 35 U/ml, remaining below this level until delivery. However, within 1 hour after term delivery or second-trimester induced abortion, the CA 125 levels showed a second increase and decreased rapidly thereafter. In contrast, serum levels of CA 19-9 did not change significantly during these periods. Combined with our previous finding that the decidua contains abundant CA 125 but little CA 19-9, these results indicate that the elevated CA 125 levels in maternal sera originate from the decidual cells affected by chorionic invasion or the placental separation.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1988

[The effects of nicotine on the synthesis and secretion of surfactant in the rabbit fetal lung].

The effects of nicotine administration on the synthesis and secretion of surfactant in the rabbit fetal lung were studied by measuring phosphatidylcholine (PC) and phosphatidylglycerol (PG) in the fetal lung tissue and amniotic fluid. The concentrations of both PC and PG in the lung tissue were decreased by administering nicotine to the mother. On the other hand, the concentrations of PC and PG in the amnniotic fluid were not altered by nicotine administration. Moreover, the PG/PC ratio in the amniotic fluid of the nicotine group was similar to that of the control group. The plasma catecholamine levels were elevated in the growth retarded fetuses from nicotine-treated mothers. These findings indicated that the administration of nicotine to the mother suppressed the synthesis of surfactant in the fetal lung but enhanced the secretion of surfactant to the alveolar cavity, probably via the stimulation of beta-receptor by catecholamine, and that the biochemical maturity of the surfactant was not altered by the administration of nicotine to the mother. The results of the present study might provide basic information to help to understand the clinical experiences reported by others i.e. that in the newborn from a smoking mother, respiratory distress occurred less frequently than in those from non-smokers.

Amniotic Fluid↗
PubMed1987

Functional differentiation in steroidogenesis of two types of luteal cells isolated from mature human corpora lutea of menstrual cycle.

Enriched small and large cell fractions were prepared from mature corpora lutea from 15 women in the midluteal phase by enzymatic dissociation, followed by Percoll gradient centrifugation. The steroidogenic function of each cell type was assessed by measuring the gonadal steroids released into the incubation medium. The large cell fraction was estimated to be 97% pure, with minimal contamination by small cells, whereas the small cell fraction was approximately 68% pure, being contaminated with 10% large cells and 22% nonsteroidogenic cells. In the unstimulated state, large cells were approximately 2-fold more potent in progesterone formation and aromatase activity, but only half as potent in androstenedione and testosterone formation as an equal number of small cells. When stimulated with hCG, the small cells responded with significant increases in progesterone, androstenedione, and testosterone release, but the large cells did not. Both cell types secreted estrone and 17 beta-estradiol in the presence of androgen substrate, but the addition of FSH significantly stimulated aromatization only in large cells. Thus, small and large human luteal cells have steroidogenic properties similar to those exhibited by follicular thecal and granulosa cells, respectively.

Androstenedione↗
PubMed1986

Metabolism of platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in human fetal membranes and decidua vera.

We have previously reported that platelet-activating factor (PAF) is present in human amniotic fluid obtained from women in labor. We have also demonstrated that PAF, lyso-PAF, and alkyl acyl-sn-glycero-3-phosphocholine (AA-GPC) are present in human amnion tissue. In the reported study, we have investigated the enzymes involved in PAF metabolism in amnion tissue and their regulation. A phospholipase A2 activity has been demonstrated in amnion tissue which cleaves alkyl acyl (long-chain) sn-glycero-3-phosphocholine. The enzyme activity is not altered by Ca2+ and is distinctly different from the phospholipase A2 that we have previously characterized in this tissue. Amnion tissue contains acetyltransferase activity which requires Ca2+ and is associated with the microsomal fraction. Acetylhydrolase is also present in the cytosolic fraction of amnion tissue. Acetylhydrolase activity has also been demonstrated in amniotic fluid. The affinities of acetyltransferase (for lyso-PAF) and acetylhydrolase (for PAF) were unaffected by Ca2+. In the presence of Ca2+, however, the specific activity of acetyltransferase was increased four- to fivefold while that of acetylhydrolase was unaffected. Acetyltransferase and acetylhydrolase activities in fetal membranes and decidua were similar and were unchanged with gestational age. The possible role of PAF in the initiation of human parturition is discussed.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1986

Impaired steroidogenic function of corpora lutea from hyperprolactinemic baboons induced by sulpiride.

It has been noticed that hyperprolactinemia can cause luteal insufficiency as well as anovulation in women. In order to explore the mechanism underlying this disorder, hyperprolactinemia was induced in baboons (Papio cynocephalus) by daily administration of sulpiride during follicular and early luteal phases. In hyperprolactinemic baboons, the plasma progesterone level was suppressed without notable changes in plasma estradiol, LH and FSH levels. When corpora lutea from these baboons were examined in vitro to investigate their ability to convert 14C-pregnenolone into various steroids, there was progressive inhibition of steroid metabolism related to the plasma levels of prolactin. These findings strongly suggest, although do not actually prove, that an elevated level of prolactin could directly impair luteal function by adversely affecting 3 beta-hydroxysteroid dehydrogenase activity.

Animals↗
PubMed1985

Platelet-activating factor metabolism in human amnion and the responses of this tissue to extracellular platelet-activating factor.

It was found previously that platelet-activating factor (PAF, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is undetectable in human amniotic fluid obtained before labor but is present in the majority of samples of amniotic fluid obtained after labor. In the present investigation, the amount of PAF in amnion tissue and the ability of this tissue to produce PAF and respond to PAF were investigated. Amounts of PAF in amnion obtained either during the second trimester of gestation or at term (before labor) were similar. After labor, however, the amount of PAF in amnion increased to 2.5-times that in amnion before labor without any discernible changes in the amounts of two related glycerophospholipids viz., 1-0-alkyl-sn-glycero-3-phosphocholine and 1-0-alkyl-2-acyl-sn-glycero-3-phosphocholine. The Ca2+-ionophore A23187, in the presence of Ca2+, caused an increase in the amount of PAF in amnion tissue disks but PAF did not appear to be released into the incubation medium. The stimulation of PAF formation by A23187 and Ca2+ was not affected by the addition of indomethacin. Addition of PAF to disks of amnion tissue resulted in an increase in the concentration of prostaglandin E2 in the incubation medium. An increase in prostaglandin E2 formation of similar magnitude was induced by A23187. Based on these results it is concluded that PAF can be synthesized in amnion tissue and net production is stimulated by Ca2+. In addition, amnion is receptive to extracellular PAF and exhibits, as one response, an increased production of prostaglandin E2.

Amnion↗
PubMed1985

[Fetal maturation and amniotic fluid levels of catecholamines and their metabolites].

Phosphatidylglycerol (PG), a phospholipid closely associated with fetal lung maturity, appears in the amniotic fluid (AF) of complicated pregnant women much earlier than it usually increases during uneventful pregnancy. In this study, AF PG levels, measured by an enzymatic method, were correlated with AF concentrations of catecholamines (CAT) and the deaminated metabolites of dopamine (3,4-dihydroxyphenylacetic acid; DOPAC) and norepinephrine (3,4-dihydroxyphenylglycol; DOPEG), all of which were determined by radioenzymatic assay. AF concentrations of CAT increased with the advance of gestation especially after 36 weeks of gestation, when clinically apparent fetal distress was not present. Three to four fold higher levels of DOPAC and DOPEG over their parent CAT were found in AF. Even prior to 37 weeks of gestation, high concentrations of CAT were found in the pregnancies complicated with fetal distress, and significant correlation was noted for PG versus dopamine (p less than 0.005), norepinephrine (p less than 0.05) epinephrine (p less than 0.02) and DOPEG (p less than 0.05), but not DOPAC. Such a correlation was not observed after 37 weeks of gestation. These findings suggest that fetal CAT plays a primary role in developing fetal lung maturation and that AF PG and CAT increase as a response to chronic distress, only before 37 weeks of gestation.

Adrenal Glands↗
PubMed1984

The identification and characterization of protein kinase C activity in fetal membranes.

Protein kinase C activity was demonstrated in cytosolic fractions prepared from human amnion and decidua vera tissues. The enzyme has been partially purified and was found to be glycerophospholipid-dependent. Phosphatidylserine was most active in the stimulation of protein kinase C. Ca2+ was also required for the expression of the enzyme activity. In the presence of unsaturated diacylglycerols, maximum activation of protein kinase C was observed at suboptimal concentrations of Ca2+. A possible role of phospholipid-dependent protein kinase C in the regulation of arachidonic acid release in this tissue is discussed.

Amnion↗
PubMed1983

Adenomatoid tumor--like structures in the subperitoneal nodules produced by sex steroids.

Multiple subperitoneal nodules were produced in the abdominal cavities of guinea pigs treated with various doses of estradiol benzoate for 3 months. Gland-like structures with intervening fibrous stroma were observed in 20% of these nodules. These gland-like structures resembled adenomatoid tumors, but were composed of cells that resembled mesothelium, ciliated cells, and cells with mucin in the cytoplasm. Some parts were composed of cells that had a squamous appearance. In guinea pigs, pretreatment with estradiol benzoate followed by treatment with a combination of estradiol benzoate and progesterone for 1 to 3 months produced nodules with gland-like structures similar to those produced by estrogen treatment alone. However, the gland-like structures were composed only of cells that resembled mesothelium and cells with cilia. Therefore, we conjecture that the formation of gland-like structures in the subperitoneal nodules is the result of mesothelial inclusions and their proliferation and that some of these mesothelial cells were differentiated into ciliated, mucinous, and squamous cells by estrogen.

Adenoma↗
PubMed1983

Ultrastructural study of minute uterine leiomyomas.

Minute uterine leiomyomas, less than 3 mm in diameter, were studied by electron microscopy. In five of 15 cases, morphologically different types of smooth muscle cell were identified. In the central region of leiomyomas, most myoma cells were characterized by filaments sporadically located in the cytoplasm and well-developed organelles. These cells were interpreted as immature smooth muscle cells. In the outer layer of nodules, the cells were a more mature form of smooth muscle cell and resembled normal myometrial cells. The differences suggest that differentiation of the smooth muscle cells occurs early in the growth of uterine leiomyoma.

Adult↗