Search PubMed⌕ Search

Biomedical subjects

S K Kang

Publications and source records attributed to S K Kang.

At least 55 records · Page 3Linked to original sources
PubMed2001

Differential regulation of two forms of gonadotropin-releasing hormone messenger ribonucleic acid in human granulosa-luteal cells.

Until recently, the primate brain was thought to contain only one form of GnRH known as mammalian GnRH (GnRH-I). The recent cloning of a second form of GnRH (GnRH-II) with characteristics of chicken GnRH-II in the primate brain has prompted a reevaluation of the role of GnRH in reproductive functions. In the present study, we investigated the hormonal regulation of GnRH-II messenger RNA (mRNA) and its functional role in the human granulosa-luteal cells (hGLCs), and we provided novel evidence for differential hormonal regulation of GnRH-II vs. GnRH-I mRNA expression. Human GLCs were treated with various concentrations of GnRH-II, GnRH-II agonist (GnRH-II-a), or GnRH-I agonist (GnRH-I-a; leuprolide) in the absence or presence of FSH or human CG (hCG). The expression levels of GnRH-II, GnRH-I, and GnRH receptor (GnRHR) mRNA were investigated using semiquantitative or competitive RT-PCR. A significant decrease in GnRH-II and GnRHR mRNA levels was observed in cells treated with GnRH-II or GnRH-II-a. In contrast, GnRH-I-a revealed a biphasic effect (up- and down-regulation) of GnRH-I and GnRHR mRNA, suggesting that GnRH-I and GnRH-II may differentially regulate GnRHR and their ligands (GnRH-I and GnRH-II). Treatment with FSH or hCG increased GnRH-II mRNA levels but decreased GnRH-I mRNA levels, further indicating that GnRH-I and GnRH-II mRNA levels are differentially regulated. To investigate the physiological role of GnRH-II, hGLCs were treated with GnRH-II or GnRH-II-a in the presence or absence of hCG, for 24 h, and progesterone secretion was measured by RIA. Both GnRH-II and GnRH-II-a inhibited basal and hCG-stimulated progesterone secretion, effects which were similar to the effects of GnRH-I treatment on ovarian steroidogenesis. Next, hGLCs were treated with various concentrations of GnRH-II, GnRH-II-a, or GnRH-I-a; and the expression levels of FSH receptor and LH receptor were investigated using semiquantitative RT-PCR. A significant down-regulation of FSH receptor and LH receptor was observed in cells treated with GnRH-II, GnRH-II-a, and GnRH-I-a, demonstrating that GnRH-II and GnRH-I may exert their antigonadotropic effect by down-regulating gonadotropin receptors. Interestingly, GnRH-II and GnRH-II-a did not affect basal and hCG-stimulated intracellular cAMP accumulation, suggesting that the antigonadotropic effect of GnRH-II may be independent of modulation of cAMP levels. Taken together, these results suggest that GnRH-II may have biological effects similar to those of GnRH-I but is under differential hormonal regulation in the human ovary.

Animals↗
PubMed2001

Stimulation of mitogen-activated protein kinase by gonadotropin-releasing hormone in human granulosa-luteal cells.

The present study investigated the activation of mitogen-activated protein kinases (MAPKs) by a GnRH agonist (GnRHa) in human granulosa-luteal cells (hGLCs). The phosphorylation state of p44 and p42 MAPK was examined using antibodies that distinguish phospho-p44/42 MAPK (Thr(202)/Tyr(204)) from total p44/42 MAPK (activated plus inactivated). Activation of MAPK by GnRHa was observed within 5 min and was sustained for 60 min after treatment. GnRHa stimulated MAPK activation in a dose-dependent manner, with maximum stimulation (6.7-fold over basal levels) at 10(-7) M. Pretreatment with a protein kinase C (PKC) inhibitor, GF109203X, completely blocked GnRHa-induced MAPK activation. In addition, pretreatment with a PKC activator, phorbol-12-myristate 13-acetate, potentiated GnRH-induced MAPK activation. These results indicate that GnRHa stimulates MAPK activation through a PKC-dependent pathway in hGLCs, possibly coupled to G(q)alpha protein. MAPK activation was also observed in response to 8-bromo-cAMP or cholera toxin, but not pertussis toxin. Forskolin (50 microM) substantially stimulated a rapid cAMP accumulation, whereas GnRHa (10(-7) M) or pertussis toxin (100 mg/ml) did not affect basal intracellular cAMP levels. Cotreatment of GnRHa (10(-7) M) did not attenuate forskolin- or hCG-stimulated cAMP accumulation. These results suggest that the GnRH receptor is probably not coupled to G(s)alpha or G(i)alpha in hGLCs. Finally, GnRHa (10(-7) M) stimulated a significant increase in Elk-1 phosphorylation and c-fos messenger RNA expression, as revealed by an in vitro kinase assay and Northern blot analysis, respectively. These results clearly demonstrate that GnRH activates the MAPK cascade through a PKC-dependent pathway in the human ovary.

Cells, Cultured↗
PubMed2001

Estradiol regulates gonadotropin-releasing hormone (GnRH) and its receptor gene expression and antagonizes the growth inhibitory effects of GnRH in human ovarian surface epithelial and ovarian cancer cells.

In the present study, we investigated the expression of estrogen receptors (ERalpha and ERbeta) in human ovarian surface epithelial (hOSE) cells and the ovarian cancer cell line, OVCAR-3, and provided novel evidence that estrogen may have a growth regulatory effect in these cells. Expression levels of ERalpha messenger RNA (mRNA) were 1.5-fold higher in OVCAR-3 cells than in hOSE cells, as revealed by semiquantitative RT-PCR and Southern blot analysis. A significant increase (3.3-fold) in ERss mRNA levels was observed in OVCAR-3 cells compared with hOSE cells. In parallel with mRNA levels, expression levels of ERalpha and ERbeta proteins were also higher in OVCAR-3 cells compared with hOSE cells. We recently proposed that GnRH and its receptor may have an autocrine role in hOSE and ovarian cancer cells. To determine whether estrogen regulates GnRH and GnRH receptor (GnRHR), hOSE and OVCAR-3 cells were treated with various concentrations of 17beta-estradiol for 24 h. Expression levels of GnRH and GnRHR mRNA were examined using quantitative and competitive RT-PCR, respectively. Treatment with 17beta-estradiol induced a significant down-regulation of GnRH mRNA in OVCAR-3 cells, but not in hOSE cells and of GnRHR mRNA in both hOSE and OVCAR-3 cells. Tamoxifen, an estrogen antagonist, prevented the effects of 17ssestradiol, suggesting that estradiol action is mediated via the ER. Finally, the effect of estrogen on the growth of hOSE and OVCAR-3 cells was investigated. The cells were treated with various concentrations of 17ss-estradiol, and the proliferative index of cells was measured using [(3)H]thymidine incorporation and DNA fluorometric assays. 17beta-Estradiol stimulated the growth of OVCAR-3 cells in a dose- and time-dependent manner. In contrast, 17beta-estradiol failed to stimulate the growth of hOSE cells. As estrogen down-regulated GnRH and GnRHR mRNA, we investigated whether estrogen treatment blocks the growth inhibitory effect of a GnRH agonist in OVCAR-3 and hOSE cells. Cells were treated with 17beta-estradiol (10(-7) M) together with (D-Ala(6))-GnRH (10(-7) M), and the proliferative index of cells was measured. Pre- or cotreatment of cells with 17beta-estradiol significantly attenuated the growth inhibitory effect of the GnRH agonist in OVCAR-3 cells, whereas no effect of 17ss-estradiol treatment was observed in hOSE cells. To our knowledge, these results provide the first demonstration of a potential interaction between the estradiol/ER and GnRH/GnRHR systems, which may be important in the growth regulation of normal and neoplastic hOSE cells.

Cell Division↗
PubMed2001

Adenosine triphosphate activates mitogen-activated protein kinase in human granulosa-luteal cells.

ATP has been shown to activate the phospholipase C/diacylglycerol/protein kinase C (PKC) pathway. However, little is known about the downstream signaling events. The present study was designed to examine the effect of ATP on activation of the mitogen-activated protein kinase (MAPK) signaling pathway and its physiological role in human granulosa-luteal cells. Western blot analysis, using a monoclonal antibody that detected the phosphorylated forms of extracellular signal-regulated kinase-1 and -2 (p42(mapk) and p44 (mapk), respectively), demonstrated that ATP activated MAPK in a dose- and time-dependent manner. Treatment of the cells with suramin (a P2 purinoceptor antagonist), neomycin (a phospholipase C inhibitor), staurosporin (a PKC inhibitor), or PD98059 (an MAPK/ERK kinase inhibitor) significantly attenuated the ATP-induced activation of MAPK. In contrast, ATP-induced MAPK activation was not significantly affected by pertussis toxin (a G(i) inhibitor). To examine the role of G(s) protein, the intracellular cAMP level was determined after treatment with ATP or hCG. No significant elevation of intracellular cAMP was noted after ATP treatment. To determine the role of MAPK in steroidogenesis, human granulosa-luteal cells were treated with ATP, hCG, or ATP plus hCG in the presence or absence of PD98059. RIA revealed that ATP alone did not significantly affect the basal progesterone concentration. However, hCG-induced progesterone production was reduced by ATP treatment. PD98059 reversed the inhibitory effect of ATP on hCG-induced progesterone production. To our knowledge, this is the first demonstration of ATP-induced activation of the MAPK signaling pathway in the human ovary. These results support the idea that the MAPK signaling pathway is involved in mediating ATP actions in the human ovary.

Adenosine Triphosphate↗
PubMed2001

Estradiol up-regulates antiapoptotic Bcl-2 messenger ribonucleic acid and protein in tumorigenic ovarian surface epithelium cells.

Most epithelial ovarian tumors appear to arise from the ovarian surface epithelium (OSE). Even though it has been suggested that estrogen may be associated with ovarian tumorigenesis, the exact role of estrogen in the regulation of apoptosis in neoplastic OSE cells remains uncertain. Immortalized OSE (IOSE) cell lines were generated from human normal OSE. These cell lines represent early neoplastic (IOSE-29), tumorigenic (IOSE-29EC), and late neoplastic (IOSE-29EC/T4 and IOSE-29EC/T5) transformation stages from human normal OSE. The present studies demonstrated that both mRNAs and proteins of estrogen receptor (ER) alpha and beta were expressed in IOSE cell lines. No difference was observed in normal OSE and IOSE-29 cells, whereas treatment with 17beta-estradiol (E(2); 10(-8)-10(-6) M) resulted in an increased thymidine incorporation and DNA content per culture in IOSE-29EC cells. This effect of E(2) was attenuated with tamoxifen treatment (10(-6) M), the estrogen antagonist, suggesting that the effect of E(2) is mediated through specific ERs. There was no stimulatory effect on thymidine incorporation before day 6, but after 6 days of E(2) treatment, thymidine incorporation was significantly increased. Because the ratio of thymidine incorporation to DNA content per culture did not change, this E(2) effect does not appear to indicate stimulation of proliferation but, rather, inhibition of apoptosis. In addition, treatment with tamoxifen (10(-6) M) induced apoptosis up to 3-fold in IOSE-29EC cells, whereas cotreatment with E(2) (10(-8)-10(-6) M) plus tamoxifen attenuated tamoxifen-induced apoptosis in a dose-dependent manner. Both proapoptotic bax and antiapoptotic bcl-2 at messenger RNA (mRNA) and protein levels were expressed in IOSE cell lines. Interestingly, treatments with E(2) resulted in a significant increase of bcl-2 mRNA and protein levels (2- and 1.7-fold, respectively), whereas no difference was observed in bax mRNA level. Thus, E(2) may enhance survival of IOSE-29EC by up-regulating bcl-2, and antiapoptotic bcl-2 may be a dominant regulator of apoptotic pathway in these cells. In conclusion, the present study indicates that early neoplastic (IOSE-29), tumorigenic (IOSE-29EC), and late neoplastic (IOSE-29EC/T4 and T5) OSE cells expressed both ERalpha and ERbeta at the mRNA and protein levels. In addition, E(2) prevented tamoxifen induced-apoptosis through ERs. The mechanism of E(2) action may be associated with up-regulation of bcl-2 gene at mRNA and protein levels. These results suggest that estrogen may play a role in ovarian tumorigenesis by preventing apoptosis in tumorigenic OSE cells.

Apoptosis↗
PubMed2001

Role of mitogen-activated protein kinase in prostaglandin f(2alpha) action in human granulosa-luteal cells.

In the ovary it has been demonstrated that PGF(2alpha) activates the phospholipase C (PLC)/diacylglycerol/protein kinase C pathway. However, little is known about the downstream signaling events that mediate subsequent cellular responses such as steroidogenesis. The present study was designed to examine the effect of PGF(2alpha) on activation of the mitogen-activated protein kinase (MAPK) signaling pathway and its physiological role in human granulosa-luteal cells (hGLCs). Human GLCs, obtained from women undergoing in vitro fertilization-embryo transfer, were treated with increasing concentrations of PGF(2alpha) (10 nmol/L to 10 micromol/L) for 5 min. For time-course experiments, hGLCs were treated with 1 micromol/L PGF(2alpha) for 1, 5, 10, or 20 min. Western blot analysis, using a monoclonal antibody that detected the phosphorylated forms of extracellular signal-regulated kinases 1 and 2 (p42(mapk) and p44(mapk), respectively), demonstrated that PGF(2alpha) activated MAPK in hGLCs in a dose- and time-dependent manner. Treatment of the cells with neomycin (10 mmol/L; a PLC inhibitor), bisindolylmaleimide I (5 micromol/L; a PKC inhibitor), or PD98059 (50 micromol/L; a MEK inhibitor and a MAPK kinase inhibitor) significantly attenuated the PGF(2alpha)-induced activation of MAPK. In contrast, MAPK activation was not significantly affected by pertussis toxin (200 ng/mL; a G(i) inhibitor) pretreatment. To determine the role of MAPK in steroidogenesis, hGLCs were treated with PGF(2alpha) (1 micromol/L), hCG (1 IU/mL), or PGF(2alpha) plus hCG in the presence or absence of PD98059. Progesterone levels in the culture medium were examined by RIA. Treatment of hGLCs with PGF(2alpha) significantly inhibited hCG-induced progesterone production. The presence of the MEK inhibitor, PD98059, reversed the inhibitory effect of PGF(2alpha) on hCG-induced progesterone production. To our knowledge, it is the first demonstration of PGF(2alpha)-induced activation of the MAPK signaling pathway in the human ovary. These results indicated that PGF(2alpha) activated MAPK subsequent to PLC and PKC activation through pertussis toxin-insensitive G protein in hGLCs. Further, we demonstrated that PGF(2alpha)-induced MAPK activation is associated with modulation of progesterone production. These results support the idea that the MAPK signaling pathway is involved in mediating PGF(2alpha) actions in the human ovary.

Cells, Cultured↗
PubMed2001

Direct action of melatonin in human granulosa-luteal cells.

The direct involvement of melatonin in modulation of ovarian steroidogenesis, the high levels of melatonin found in human follicular fluid, and the presence of melatonin binding sites in the ovary led us to hypothesize that melatonin acts as a modulator of ovarian function. In contrast to the hypothalamus and pituitary, the mechanism of melatonin action at the level of the ovary is still poorly understood. In the present study, we investigated the gene expression of the two different forms of melatonin receptors in human granulosa-luteal cells, using RT-PCR. PCR products corresponding to the expected sizes of the melatonin receptor subtypes, mt(1)-R and MT(2)-R, were obtained from granulosa-luteal cells, and the authenticity of the PCR products was confirmed by Southern blot hybridization with cDNA probes. Subsequent cloning and sequence analysis revealed that the ovarian mt(1)-R and MT(2)-R cDNAs are identical to their brain counterparts. Because gonadotropins and GnRH acting through specific receptors in the human ovary regulate cellular functions, we investigated the role of melatonin in the regulation of FSH receptor, LH receptor, GnRH, and GnRH receptor levels. Treatment with melatonin (10 pM-100 nM) significantly increased LH receptor mRNA levels without altering the expression of the FSH receptor gene. Both GnRH and GnRH receptor mRNA levels were significantly decreased, to 61% and 45% of control levels, respectively, after melatonin treatment. Melatonin treatment alone had no effect on basal progesterone production but enhanced the effects of human CG-stimulated progesterone production. Because MAPKs are activated in response to a diverse array of extracellular stimuli leading to the regulation of cell growth, division, and differentiation, and because melatonin has been shown to modulate cellular proliferation and differentiation, in this study, we demonstrated that melatonin activated MAPK in a dose- and time-dependent manner. In summary, our studies demonstrate, for the first time, that melatonin can regulate progesterone production, LH receptor, GnRH, and GnRH receptor gene expression through melatonin receptors in human granulosa-luteal cells, which may be mediated via the MAPK pathway and activation of Elk-1. Our results support the notion that melatonin plays a direct role in regulating ovarian function.

Cells, Cultured↗
PubMed2001

Adenosine triphosphate-evoked cytosolic calcium oscillations in human granulosa-luteal cells: role of protein kinase C.

ATP has been shown to modulate progesterone production in human granulosa-luteal cells (hGLCs) in vitro. After binding to a G protein-coupled P2 purinergic receptor, ATP stimulates phospholipase C. The resultant production of diacylglycerol and inositol triphosphate activates protein kinase C (PKC) and intracellular calcium [Ca(2+)](i) mobilization, respectively. In the present study, we examined the potential cross-talk between the PKC and Ca(2+) pathway in ATP signal transduction. Specifically, the effect of PKC on regulating ATP-evoked [Ca(2+)](i) oscillations were examined in hGLCs. Using microspectrofluorimetry, [Ca(2+)](i) oscillations were detected in Fura-2 loaded hGLCs in primary culture. The amplitudes of the ATP-triggered [Ca(2+)](i) oscillations were reduced in a dose-dependent manner by pretreating the cells with various concentrations (1 nM to 10 microM) of the PKC activator, phorbol-12-myristate-13-acetate (PMA). A 10 microM concentration of PMA completely suppressed 10 microM ATP-induced oscillations. The inhibitory effect occurred even when PMA was given during the plateau phase of ATP evoked [Ca(2+)](i) oscillations, suggesting that extracellular calcium influx was inhibited. The role of PKC was further substantiated by the observation that, in the presence of a PKC inhibitor, bisindolylmaleimide I, ATP-induced [Ca(2+)](i) oscillations were not completely suppressed by PMA. Furthermore, homologous desensitization of ATP-induced calcium oscillations was partially reversed by bisindolylmaleimide I, suggesting that activated PKC may be involved in the mechanism of desensitization. These results demonstrate that PKC negatively regulates the ATP-evoked [Ca(2+)](i) mobilization from both intracellular stores and extracellular influx in hGLCs and further support a modulatory role of ATP and P2 purinoceptor in ovarian steroidogenesis.

Adenosine Triphosphate↗
PubMed2001

The regulation of apoptosis by activin and transforming growth factor-beta in early neoplastic and tumorigenic ovarian surface epithelium.

Most ovarian neoplasms arise from the ovarian surface epithelium (OSE), and multiple growth factors have been implicated to influence the transformation from OSE. The present study was performed to investigate the role of activin and transforming growth factor-beta (TGFbeta) in normal and neoplastic OSE cells. An immortalized OSE cell line (IOSE-29) was generated from normal OSE by transfecting simian virus 40 large T antigen and was rendered tumorigenic after subsequent transfection with the E-cadherin gene (IOSE-29EC). The activin/inhibin subunits and activin receptors were expressed at both messenger ribonucleic acids and protein levels in these cells, suggesting that activin may have an autocrine role in neoplastic OSE cells. Treatments with activin (1-100 ng/mL) resulted in a significant decrease in cell proliferation in both IOSE-29 and IOSE-29EC cells, although we have shown that it stimulated the growth of ovarian cancer cells and had no effect on normal OSE. This inhibitory effect was attenuated with cotreatment with follistatin. Treatment with TGFbeta (0.1-10 ng/mL) also significantly decreased the proliferation of normal, IOSE-29, and IOSE-29EC cells in a dose-dependent manner. In addition, treatments with both activin and TGFbeta resulted in an increase in DNA fragmentation in IOSE-29EC cells in a dose-dependent manner. This apoptotic effect of activin was attenuated by cotreatment with follistatin. Treatment with TGFbeta (1 and 10 ng/mL) resulted in a significant decrease in Bcl-2 protein (up to 50%) in IOSE-29EC, whereas no difference was observed in Bax protein levels. Therefore, down-regulated Bcl-2 by TGFbeta may eventually induce apoptosis in IOSE-29EC cells. In contrast, no difference was observed in Bax and Bcl-2 protein expression after treatment with activin. In conclusion, the present study indicates that activin and TGFbeta inhibited growth and induced apoptosis in early neoplastic (IOSE-29) and tumorigenic OSE (IOSE-29EC) cells. Furthermore, antiapoptotic Bcl-2 protein was down-regulated by TGFbeta, whereas no difference was produced in Bax protein by activin or TGFbeta treatment or in Bcl-2 protein by activin. These results suggest that activin and TGFbeta may play a role in growth inhibition and induction of apoptosis in early neoplastic and tumorigenic stage of ovarian cancer.

Activin Receptors↗
PubMed2001

Antigonadotropic action of adenosine triphosphate in human granulosa-luteal cells: involvement of protein kinase Calpha.

The presence of P2U purinoceptor in human granulosa-luteal cells (hGLCs) indicates a potential role of ATP in regulating ovarian function. In this study an inhibitory effect of ATP on hCG-induced cAMP production was observed. Extracellular ATP has been shown to activate protein kinase C (PKC) after binding to a purinoceptor. To understand the role of PKC in mediating ATP action, hCG-stimulated cAMP level was examined in the presence of the PKC activator, 1 micromol/L phorbol 12-myristate 13-acetate (PMA), or the PKC inhibitor, 1 micromol/L staurosporin or 1 micromol/L bisindolylmaleimide I. PMA, like 10 micromol/L ATP, significantly reduced hCG-evoked cAMP production. In addition, the inhibitory effect of ATP was reversed by staurosporin and bisindolylmaleimide I. To further investigate the involvement of PKC isoforms in mediating the inhibitory effect of ATP, the presence of PKC isoforms in cultured hGLCs was examined by Western blot using monoclonal antibodies against specific isoforms. Translocation of PKC isoforms from cytosolic fraction to membrane fraction was studied to identify the active PKC isozymes subsequent to ATP treatment. The change in PKC isoform in PKC-depleted cells (achieved by exposure to PMA for 18 h) was also examined. Our results demonstrated the presence of PKCalpha, -delta, -iota, and -lambda isoforms in hGLCs and the translocation of PKCalpha subsequent to ATP treatment. In PKC-depleted cells the PKCalpha level was reduced, and no significant effect of ATP on hCG-stimulated cAMP production was observed. To our knowledge, this is the first demonstration of PKC isoforms in hGLCs and the involvement of activated PKC in mediating the antigonadotropic effect of extracellular ATP. Taken together, these results further support a role of this neurotransmitter in regulating human ovarian function.

Adenosine Triphosphate↗
PubMed2001

Bee venom pretreatment has both an antinociceptive and anti-inflammatory effect on carrageenan-induced inflammation.

Although the injection of bee venom (BV) has been reported to evoke tonic pain and hyperalgesia, there is conflicting evidence in the literature indicating that BV can also exert an anti-inflammatory and antinociceptive effects on inflammation. In this regard, BV has been traditionally used in Oriental medicine to relieve pain and to treat chronic inflammatory diseases such as rheumatoid arthritis. The present study was designed to test the hypothesis that BV induces acute nociception under normal conditions, but that it can serve as a potent anti-inflammatory and antinociceptive agent in a localized inflammatory state. The experiments were designed to evaluate the effect of BV pretreatment on carrageenan (CR)-induced acute paw edema and thermal hyperalgesia. In addition, spinal cord Fos expression induced by peripheral inflammation was quantitatively analyzed. In normal animals subcutaneous BV injection into the hindlimb was found to slightly increase Fos expression in the spinal cord without producing detectable nociceptive behaviors or hyperalgesia. In contrast pretreatment with BV (0.8 mg/kg) 30 min prior to CR injection suppressed both the paw edema and thermal hyperalgesia evoked by CR. In addition, there was a positive correlation between the percent change in paw volume and the expression of Fos positive neurons in the spinal cord. These results indicate that BV pretreatment has both antinociceptive and anti-inflammatory effects in CR-induced inflammatory pain. These data also suggest that BV administration may be useful in the treatment of the pain and edema associated with chronic inflammatory diseases.

Animals↗
PubMed2001

Hypodipsic hypernatremia with intact AVP response to non-osmotic stimuli induced by hypothalamic tumor: a case report.

Anatomical lesions of hypothalamic area associated with hypodipsic hypernatremia have been reported only rarely. We report here a case of hypodipsic hypernatremia induced by a hypothalamic lesion. A 25-yr-old man, who had been treated with radiation for hypothalamic tumor 5-yr before, was admitted for evaluation of hypernatremia and hypokalemia. He never felt thirst despite the elevated plasma osmolality and usually refused to drink intentionally. Plasma arginine vasopressin (AVP) level was normal despite the severe hypernatremic hyperosmolar state and urine was not properly concentrated, while AVP secretion was rapidly induced by water deprivation and urine osmolality also progressively increased to the near maximum concentration range. All of these findings were consistent with an isolated defect in osmoregulation of thirst, which was considered as the cause of chronic hypernatremia in the patient without an absolute deficiency in AVP secretion. Hypokalemia could be induced by activation of the renin-angiotensin-aldosterone system as a result of volume depletion. However, inappropriately low values of plasma aldosterone levels despite high plasma renin activity could not induce symptomatic hypokalemia and metabolic alkalosis. The relatively low serum aldosterone levels compared with high plasma renin activity might result from hypernatremia. Hypernatremia and hypokalemia were gradually corrected by intentional water intake only.

Adult↗
PubMed2001

Massive thrombosis after central venous catheterization in a patient with previously undiagnosed Behcet's disease.

Thrombosis is an important complication of central venous catheterization. Among the many intrinsic and extrinsic factors, the patient's medical disease can play a role in thrombogenesis. Behcet's disease (BD), classified as a vasculitis, is a multisystem disease involving the small blood vessels. It is often difficult to recognize and diagnose the disease. A 24-yr-old female patient showed massive central venous thrombosis which caused superior vena cava syndrome after subclavian vein catheterization. Twenty days after catheterization, the patient exhibited swelling of the face, neck, and both upper extremities. Despite thrombectomy and continuous anticoagulation therapy, her facial and upper extremity swelling reappeared and follow-up chest computed tomography (CT) showed the recurrent thrombosis in the same central veins previously affected. A diagnosis of BD was then made. Following steroid therapy, neither clinical symptoms nor CT findings suggestive of central venous thrombosis were observed during the subsequent 6-months of follow-up period. This case emphasizes that central venous catheterization in a patient with BD should be performed with great caution.

Adult↗
PubMed2001

The effect of cilostazol on glucose tolerance and insulin resistance in a rat model of non-insulin dependent diabetes mellitus.

BACKGROUND: It has been reported that many peripheral vasodilating drugs might improve insulin resistance. Cilostazol, a antithrombotic agent, increases peripheral blood flow in non-insulin dependent diabetic patients. The effect of cilostazol treatment on insulin resistance in streptozotocin (STZ)-induced non-insulin dependent diabetic Wistar rats was examined. METHODS: About a half of two-day old neonate siblings were injected intraperitoneally with STZ and maintained for six months, at which time they were compared with age-matched control rats for intraperitoneal glucose tolerance test (IPGTT) and for glucose infusion rate (GINF) in a euglycemic hyperinsulinemic glucose-clamp study. After that, these studies were also performed after feeding rat chow containing cilostazol (100 mg/kg/day) to rats with STZ-induced non-insulin dependent diabetes mellitus for four-weeks and compared with those of age-matched control rats. RESULTS: In the intraperitoneal glucose tolerance test studies, plasma glucose levels of STZ-induced non-insulin dependent diabetic rats were significantly higher and plasma insulin levels significantly lower than those of age-matched control rats in the age of six months. Glucose infusion rate was lower in STZ-induced non-insulin dependent diabetic rats than those of age-matched control rats. However, after a four-week cilostazol treatment, glucose infusion rate of STZ-induced non-insulin dependent diabetic rats was not significantly different from that of control rats. CONCLUSION: These findings suggested that cilostazol may improve insulin resistance in STZ-induced non-insulin dependent diabetic rats.

Animals↗
PubMed2001

A case of bronchiolitis obliterans organizing pneumonia with renal dysfunction after renal transplantation.

A 35-year-old male renal transplant patient was admitted with 3-week history of cough and myalgia after a 3-month post-transplantation. The patient's posttransplant course was uncomplicated and had no rejection. But on admission, the serum creatinine was 3.0 mg/dl and high-resolution computed tomography (HRCT) showed bilateral patchy densities and peripheral consolidations. Renal biopsy revealed mononuclear cell infiltration and non-specific tubular injury without evidence of rejection. An open lung biopsy was performed which showed multiple fibroblast plugs filling airspaces that were typical pathologic features of bronchiolitis obliterans with organizing pneumonia (BOOP). After prednisone therapy, the patient's pulmonary symptoms and radiographic findings rapidly recovered and serum creatinine also decreased from 3.0 to 2.1 mg/dl. Although the cause of renal dysfunction was not elucidated, we herein report a rare case of BOOP with renal dysfunction after renal transplantation.

Adult↗
PubMed2000

Gonadotropin-releasing hormone activates mitogen-activated protein kinase in human ovarian and placental cells.

Considering that the action of gonadotropin-releasing hormone (GnRH) may be mediated via different signaling pathways in extrapituitary tissues, in the present study we investigated the role of the human GnRH receptor (GnRHR) in activating mitogen-activated protein kinases (MAPKs), which regulate cell growth, division, and differentiation. The phosphorylation state of p44 and p42 MAPKs was examined using antibodies that distinguish phospho-p44/42 MAPK (P-MAPK, Thr(202)/Tyr(204)) from total p44/42 MAPK (T-MAPK, activated plus inactivated) in human ovarian and placental cells. Cell cultures were treated with various concentrations of a GnRH agonist, (D-Ala(6))-GnRH, for 5 min. (D-Ala(6))-GnRH stimulated a rapid activation of P-MAPK in human granulosa-luteal cells (hGLCs) and immortalized extravillous trophoblast (IEVT) cells. Interestingly, (D-Ala(6))-GnRH treatment of ovarian cancer (OVCAR-3) and placental carcinoma (JEG-3) cells induced a biphasic regulatory pattern in P-MAPK activity. In contrast, no change of T-MAPK levels was observed following addition of the GnRH agonist in the ovarian and placental cells examined. The physiological implication of MAPK activation by GnRH in the ovarian and placental cells was also investigated. Human GLCs were treated with (D-Ala(6))-GnRH for 24 h, and progesterone secretion was measured by an established RIA. (D-Ala(6))-GnRH induced a significant decrease in progesterone secretion with maximum inhibition (a 45% decrease over basal level) at 10(-7) M. This inhibitory effect was completely reversed by pretreatment with MAPK/ERK kinase 1 (MEK1) inhibitor (PD98059), suggesting the involvement of the MAPK pathway in hGLCs. Placental JEG-3 cells were treated with (D-Ala(6))-GnRH for 24 h, and betahCG mRNA level was measured using Northern blot analysis. (D-Ala(6))-GnRH stimulated the expression of betahCG mRNA to 160% of control value in JEG-3 cells. In contrast to the ovarian cells, pretreatment of JEG-3 cells with PD98059 failed to block the stimulatory effect of GnRH on betahCG mRNA level, suggesting that other signaling pathway(s) may play a more dominant role in GnRH-induced betahCG mRNA expression. To our knowledge, this is the first demonstration that (1) GnRH induces activation of the MAPK signaling pathway in normal and carcinoma cells of the human ovary and placenta, and (2) MAPK mediates the direct action of GnRH on progesterone production in hGLCs.

Animals↗
PubMed2000

Effect of Jindangwon on streptozotocin-induced diabetes.

The inhibitory effects of the traditional herbal medicine Jindangwon (JDW) on streptozotocin (ST)-induced diabetic mellitus were studied using the ST-treated diabetic model. Glucokinase activity of pancreatic islets was severely impaired by ST treatment. However, when ST-treated islets were treated with 1 mg/ml of JDW, the enzyme activities of glucokinase and hexokinase were protected, glucose-6-phosphatase was not. When the effects of JDW on ST-induced ATP/ADP ratio of islets were assayed, JDW was effective in restoring of ATP/ADP ratio. In addition, ST decreased the enzyme activities of PDH, while JDW had a protective effect on the enzyme. ST-induced cGMP accumulation was significantly inhibited by JDW treatment. Furthermore, ST-induced nitrite formation was significantly inhibited by JDW treatment. JDW also showed the suppressed nitrite production in ST-treated pancreatic islet cells. When the islets (200/condition) were treated with ST (5 mM for 30 min), and then JDW was added to the ST-treated cells, 1.0 mg/ml of JDW showed the activated and recovered aconitase activity in pancreatic islet cells. When the effect of ST on the gene expression of pancreatic GLUT2 and glucokinase were examined, the level of GLUT2 and glucokinase mRNA in pancreatic islets was significantly decreased. However, JDW protected and improved the expression of protein and genes, indicating that JDW is effective on ST-induced inhibition of gene expression of GLUT2, glucokinase and proinsulin in islets. These results suggested that JDW is effective in this model to treat ST-induced diabetes.

Adenosine Diphosphate↗