[Ovarian insufficiency (so called 'poor responder')].
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Diagnosis, Differential↗
Biomedical subjects
Takashi Ohba
Publications and source records attributed to Takashi Ohba.
Activation of follistatin promoter by GnRH in LbetaT2 gonadotroph cells.
Follistatin (FS) is produced and secreted from gonadotroph cells in pituitary gland as well as granulosa cells in the ovary. In the present study, we found that the FS promoter is activated by GnRH in the gonadotroph cell line, LbetaT2. Therefore, we examined the signal transduction pathways involved in the mechanism. The activation of the FS promoter by GnRH was inhibited by calphostin C, a protein kinase C inhibitor, and U0126, a MAP kinase kinase (MEK) inhibitor. Phosphorylation by protein kinase C of myristoylated alanine-rich C kinase substrate (MARCKS) in LbetaT2 cells was observed after 3-min treatment with GnRH and declined after 30 min. The subsequent activation of MAP kinase was also transient, and down-regulation of protein kinase C completely inhibited the MAP kinase activation by GnRH, suggesting that the transient activation of protein kinase C led to the transient activation of MAP kinase. Although phorbol 12-myristate 13-acetate treatment increased phosphorylation of MARCKS and activated MAP kinase, it did not activate the FS promoter. Genistein, a tyrosine kinase inhibitor, completely inhibited the GnRH-induced activation of the FS promoter, while no inhibition of the MAP kinase pathway was observed. These results suggest that the activations of both the protein kinase C and tyrosine kinase pathways are necessary for the activation of the FS promoter in gonadotroph cells.
Animals↗
Developmental and neurobehavioral effects of perinatal exposure to polychlorinated biphenyls in mice.
Because behavioral deficits associated with gestational exposure to polychlorinated biphenyls (PCBs) have been a concern, we studied the developmental and neurobehavioral effects of perinatal exposure to Aroclor 1254 (A1254), a commercial mixture of PCBs, in mice. The PCB mixture (A1254; 0, 6, 18, and 54 mg/kg body weight) was administered to pregnant mice (C57BL/6Cr) every 3 days by gavage from gestational day (GD) 6 to postnatal day (PND) 20. Compared with the control, treatment with A1254 did not alter the maternal body weight during the gestation and lactation periods. The body weight of the offspring did not differ among treatments. To assess the effects on offspring following such exposure, physical and neurobehavioral development (i.e., pinna detachment, hair growth, eye opening, incisor eruption, grasp reflex, righting reflex, walking, negative geotaxis, and cliff avoidance) was observed before weaning. At PND 7, poor adult-like responses in negative geotaxis were observed in all exposed groups. When the offspring were at 8-week old, the PCB-treated (18 mg/kg body weight) mice showed a decreased walking speed in the open-field test, and a prolonged time to reach the platform in the water maze test. Spontaneous locomotion activity was not affected by PCB exposure at 9 weeks . These results showed that perinatal exposure to PCBs produces several behavioral alterations in mice. Although dose-dependent changes were not observed, the neurobehavioral effects such as a decreased walking speed in the open-field test and a prolonged time to reach the platform in the water maze test remained in adulthood after the seeming recovery from the transient delay in development before weaning.
Age Factors↗
Speciation-capable field instrument for the measurement of arsenite and arsenate in water.
Hydride generation to form arsine and in-line preconcentration of the arsine into an alkaline KMnO4 receiver followed by molybdenum blue (MB) colorimetric determination of the arsenate formed is proposed for the highly sensitive and separate measurement of total inorganic As and As(III). Reduction of As to AsH3 is carried out by NaBH4; when the reduction is carried out at pH 1, all the inorganic As is reduced to AsH3, and when carried out at pH 7, only As(III) is reduced. Reductions at the two different pH levels are carried out in two different arsine generators simultaneously using constant addition of NaBH4 with solenoid pumps. The AsH3 is collected by individual porous membrane diffusion scrubbers filled with a stationary solution of KMnO4, and the contents of the two scrubbers sequentially enter a flow analysis stream. MB is formed by merging with a ammonium molybdate-ascorbic acid reagent, passing through a heated reactor, and is then measured by a LED/photodiode-based absorbance detector. Robustness was confirmed for total As using three types of certified natural water samples. Speciation analysis data from well water samples analyzed by this method agree well with HPLC-ICPMS measurements in a different laboratory. The system has been successfully applied to field measurements of As(III) and As(V), where levels were significantly below 1 mug/L. For a 20-mL sample, the limits of detection (LODs) for this inexpensive instrument are 0.3 microg/L for both As(III) and total As. When an 80-mL sample is analyzed, LODs are 0.07 microg/L As(III) and 0.09 microg/L total As. The general approach should be applicable to many other analyte species of interest that can be isolated from the matrix by the formation of a suitable volatile compound that can be recaptured.
Journal Article↗
What we have learned from isolated cells from human ovary?
In the ovary, morphodynamics of follicles with cyclic maturation, ovulation and repair occur under the control of various tropic factors. The ovarian functions have been mostly studied by using subhuman primates and non-primate animals because of the limited availability of closely staged human specimens. We have recently established the in vitro culture systems of ovarian surface epithelium (OSE) and granulosa cells of humans, and subsequently developed the immortalization of each cell. The immortalized cell lines may supply us advanced studies on ovarian disorders as well as its physiological functions. On the embryologically putative müllerian potential of coelomic epithelium, endometriosis can be explained by coelomic metaplasia from the peritoneal mesothelium, including OSE. We can microscopically observe a continuity from flat epithelial cells on the ovarian surface or within the cortical inclusion cysts to endometriotic gland cells. The primary human OSE cells exhibited a glandular-stromal structure similar to endometriosis when they were co-cultured with endometrial stromal cells in an estrogen-rich environment. Primary and immortalized OSE cells converted the estrone to estradiol, and expressed the genes for steroidogenic factor-1 (SF-1), p450arom and 17beta-HSDs. This character of OSE was, in part, similar to the granulosa cells. One of the immortalized OSE clone produces disseminated tumors mimicking undifferentiated carcinomas in nude mice. Ovarian granulosa cells play a key role in the functional maturation of the entire follicle. The molecular pathways in granulosa cells responsible for the growth, differentiation, and nursing the oocyte are still largely unknown. Our immortalized human granulosa cell line, GC1a, obtained from developing follicles, showed no steroid hormone biosynthesis, and no detectable expression of the genes for StAR or cytochrome p450 enzymes due to the lack of SF-1. Transfected SF-1 elicited estradiol secretion in GC1a cells with concomitant expression of the genes encoding the proteins for gonadal steroidogenesis. The enzymatic activity of 17beta-HSD was also achieved by SF-1 transgene. These results indicate that SF-1 controls the gene expression required for steroidogenesis in the human developing follicle. Clinically, immortalized GC1a cells from human origin, with steroidogenic capacity, may serve as a feeder layer for in vitro oocyte maturation. Further investigations of our immortalized OSE and granulosa cells of humans will allow us to clarify whether they have a single progenitor cell.
Animals↗
Ovarian hyperstimulation syndrome-model rats; the manifestation and clinical implication.
Ovarian hyperstimulation syndrome (OHSS) is the most serious complication of ovulation induction with the gonadotropins. Though vascular endothelial growth factor (VEGF) has been implicated as a prime causative factor of OHSS progression, other factors must also be involved in the pathogenesis of OHSS. We have established an experimental model of OHSS in immature female rats. The ovarian weights and vascular permeability of the OHSS model rats are significantly increased by the ovarian stimulation with human chorionic gonadotropin (hCG). hCG elicits VEGF production in OHSS model rat ovaries. The addition of potent synthetic progesterone antagonist RU486, which reduces the extension of OHSS, attenuates the ovarian kinin and VEGF production dose-dependently whereas the VEGF gene expression was stable. VEGF protein detected in both the lung and the liver of the OHSS model rats is not affected at 24 h after the addition of hCG and RU486 in contrast to the ovary. Our results demonstrate that progesterone is implicated in the development of OHSS, in part, to enhance the ovarian VEGF production by post-transcriptional and organ-specific control.
Animals↗
Characterization of macrophages in the decidual atherotic spiral artery with special reference to the cytology of foam cells.
"Acute atherosis" is characteristic in the spiral arteries of the placental bed of preeclampsia and a wide range of pregnancy disorders. The arterial lesion is histologically characterized by fibrinoid necrosis of the vessel walls with infiltration of foam cells, which under a light microscope appears similar to that seen in atherosclerosis. Although acute atherosis is currently considered as atheromatous-like lesions, the precise cellular mechanisms inducing these changes remain unelucidated. By histochemistry, immunohistochemistry, and electron microscopy, we investigated the decidual spiral arteries obtained by placental bed biopsy from 11 preeclamptic and 15 nonpreeclamptic women. In the decidual spiral arteries of preeclamptic patients, acute atherosis was observed in 23.5% (20/85 arteries). Fibrin deposition and accumulation of foam cells were observed more frequently in preeclamptic patients than in nonpreeclamptic patients. Endothelial cells remained in the atheromatous lesion, while the smooth muscle layer surrounding fibrin and foam cells became thin and was finally destroyed. The foam cells were immunohistochemically shown to be macrophages and neutral fat and phospholipids were histochemically demonstrated in them. Ultrastructurally, their cytoplasm was occupied by variously sized lipid droplets and membrane-bound myelin-like granules (myelinosomes). Plasma concentration of monocyte chemoattractant protein 1 (MCP-1), a potent monocyte chemoattractant factor, was significantly elevated in preeclamptic patients compared with normal healthy controls (P < 0.01). In conclusion, injuries to the smooth muscle layer and intramural fibrinoid necrosis may result in infiltration of monocytes into the arterial walls, their maturation into macrophages, and the transformation into foam cells. Considering that atherosclerosis is developed by accumulation of lipid-laden macrophages and migration and proliferation of smooth muscle cells, the roles of macrophages in acute atherosis differ from those in atherosclerosis.
Arteries↗
Organ-specific production control of vascular endothelial growth factor in ovarian hyperstimulation syndrome-model rats.
Overproduction of vascular endothelial growth factor (VEGF) following human chorionic gonadotropin (hCG) stimulation has been implicated as one of the causative factors in the development of ovarian hyperstimulation syndrome (OHSS). The objective of this study was to clarify the action of hCG and progesterone, one of the possible factors for OHSS, on VEGF production and gene expression using OHSS-model rats. A total of 40 immature female Wistar rats were stimulated with 10 IU of equine chorionic gonadotropin for four consecutive days from the 22nd to 25th day of life followed by subcutaneous injection of 30 IU of hCG on the 26th day of life. RU486 and progesterone were injected 24 h after the hCG injection. Tissues and blood samples were collected on the 28th day. hCG elicited VEGF production in the OHSS-model rat ovaries. Ovarian weights of the OHSS model rats were significantly increased through day 26 by the ovarian stimulation with single dose of 30 IU hCG. Addition of anti-progesterone RU486, which reduced the ovarian enlargement, attenuated VEGF production dose dependently whereas the VEGF gene expression was stable. In the lung and liver, neither hCG nor RU486 affected VEGF production and gene expression. These results suggested that progesterone regulates VEGF production at the post-transcriptional level in a tissue specific manner in the hyperstimulated ovary.
Animals↗