Biomedical subjects

J T Seo

Publications and source records attributed to J T Seo.

At least 19 recordsLinked to original sources

PubMed2002

Staurosporine mobilizes Ca(2+) from secretory granules by inhibiting protein kinase C in rat submandibular acinar cells.

Staurosporine was previously shown to mobilize Ca(2+) from the thapsigargin-insensitive Ca(2+) store in rat submandibular acinar cells. However, the nature of the store is not yet known. Therefore, in the present study, the staurosporine-releasable intracellular Ca(2+) store was characterized. Staurosporine increased the cytosolic Ca(2+) concentration ([Ca(2+)](c)) after the inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) store was depleted. Ionomycin caused only small increases in [Ca(2+)](c) after the depletion of the IP(3)-sensitive Ca(2+) store, whereas ionomycin+monensin caused large increases. However, ionomycin+monensin did not increase [Ca(2+)](c) when added after [Ca(2+)](c) was increased by staurosporine, indicating that the acidic Ca(2+) store was the main source of Ca(2+). The acidic Ca(2+) store appeared to be associated with secretory granules, since ionomycin+monensin- and staurosporine-induced [Ca(2+)](c) increases were significantly reduced when the acinar cells were degranulated. The effect of staurosporine on [Ca(2+)](c) was mimicked by other protein kinase C inhibitors. Therefore, we conclude that staurosporine mobilizes Ca(2+) from secretory granules, probably through the inhibition of protein kinase C in rat submandibular acinar cells.

Animals↗

PubMed2001

Calcium signalling--an overview.

Calcium (Ca2+) is an almost universal intracellular messenger, controlling a diverse range of cellular processes, such as gene transcription, muscle contraction and cell proliferation. The ability of a simple ion such as Ca2+ to play a pivotal role in cell biology results from the facility that cells have to shape Ca2+ signals in the dimensions of space, time and amplitude. To generate the variety of observed Ca2+ signals, different cell types employ components selected from a Ca2+ signalling 'toolkit', which comprizes an array of signalling, homeostatic and sensory mechanisms. By mixing and matching components from the toolkit, cells can obtain Ca2+ signals that suit their physiology.

Animals↗

PubMed2001

Minimally invasive technique for sural nerve harvesting: technical description and follow-up.

OBJECTIVES: To provide instruction and the results of a minimally invasive technique for sural nerve harvesting in preparation for interposition nerve grafting during radical retropubic prostatectomy. METHODS: Twelve men underwent nerve harvesting performed using a tendon stripper. The short-form McGill Pain Questionnaire was completed preoperatively and at 6 months postoperatively. RESULTS: No significant morbidity from the leg resulted as a result of the sural nerve harvest. The results of the short-form McGill Pain Questionnaire demonstrated no significant sensory or affective changes in the leg. The average operative time for the entire harvesting procedure, including skin closure, was 15 minutes. The estimated blood loss was less than 5 mL (range 2 to 10). No wound infection or skin erythema was observed. The discharge to home was not delayed compared with the usual length of stay after radical retropubic prostatectomy. CONCLUSIONS: This minimally invasive sural nerve harvesting technique is easy to perform and has minimal morbidity.

Blood Loss, Surgical↗

PubMed2001

Predictive factors of successful testicular sperm recovery in non-obstructive azoospermia patients.

Recovery of testicular spermatozoa from non-obstructive azoospermic patients for intracytoplasmic sperm injection (ICSI) is a recent advance in the treatment of male infertility. The purpose of this study is to identify predictive factors for sperm recovery in non-obstructive azoospermic patients. A total of 178 men with non-obstructive azoospermia had multiple testicular sperm extraction (TESE) procedures to recover spermatozoa for intracytoplasmic sperm injection (ICSI) from June 1996 to February 1999. Testicular volume, serum follicle stimulating hormone (FSH) level and testicular histology were examined as positive predictive factors for sperm recovery. Testis biopsies were categorized as severe hypospermatogenesis, maturation arrest and Sertoli cell-only syndrome based on the most advanced pattern of spermatogenesis seen on histology. Sperm retrieval success rates for the patients in three histopathological categories were compared. Spermatozoa were successfully recovered in 94 of 178 (52.8%) men. Sperm were retrieved in 13 of 80 (16.3%) with Sertoli cell-only syndrome, 15 of 24 (62.5%) with maturation arrest, and 66 out of 74 (89.2%) with severe hypospermatogenesis. Spermatozoa recovery has no correlation with testicular volume or serum FSH level. When compared against Sertoli cell-only syndrome, the odds of sperm retrieval success rate was 44.3 times higher in severe hypospermatogenesis and 8.4 times in maturation arrest. These results demonstrate meaningful correlation between successful testicular sperm recovery and testis histopathology. Only testicular histopathology can be used as a predictor of successful sperm recovery.

Adult↗

PubMed2001

Zn2+-induced ERK activation mediated by reactive oxygen species causes cell death in differentiated PC12 cells.

Recent studies have provided evidence that Zn2+ plays a crucial role in ischemia- and seizure-induced neuronal death. However, the intracellular signaling pathways involved in Zn2+-induced cell death are largely unknown. In the present study, we investigated the roles of mitogen-activated protein kinases (MAPKs), such as c-Jun N-terminal kinase (JNK), p38 MAPK and extracellular signal-regulated kinase (ERK), and of reactive oxygen species (ROS) in Zn2+-induced cell death using differentiated PC12 cells. Intracellular accumulation of Zn2+ induced by the combined application of pyrithione (5 microM), a Zn2+ ionophore, and Zn2+ (10 microM) caused cell death and activated JNK and ERK, but not p38 MAPK. Preventing JNK activation by the expression of dominant negative SEK1 (SEKAL) did not attenuate Zn2+-induced cell death, whereas the inhibition of ERK with PD98059 and the expression of dominant negative Ras mutant (RasN17) significantly prevented cell death. Inhibition of protein kinase C (PKC) and phosphatidylinositol-3 kinase had little effect on Zn2+-induced ERK activation. Intracellular Zn2+ accumulation resulted in the generation of ROS, and antioxidants prevented both the ERK activation and the cell death induced by Zn2+. Therefore, we conclude that although Zn2+ activates JNK and ERK, only ERK contributes to Zn2+-induced cell death, and that ERK activation is mediated by ROS via the Ras/Raf/MEK/ERK signaling pathway.

Animals↗

PubMed2000

Biphasic effects of dithiocarbamates on the activity of nuclear factor-kappaB.

Dithiocarbamates are well-known antioxidants and nuclear factor-kappaB (NF-kappaB) inhibitors. Recently, they have been characterized as zinc ionophores. Concentration-dependent biphasic effects of dithiocarbamates on NF-kappaB activity have been widely reported. We studied the mechanism of this phenomenon in relation to Zn(2+) influx. Two dithiocarbamates, pyrrolidine dithiocarbamate and diethyldithiocarbamate, showed concentration-dependent biphasic effects in inhibiting NF-kappaB activation in cerebral endothelial cells. These unique effects of dithiocarbamates on NF-kappaB were tightly linked to their ability to elevate intracellular Zn(2+)500 microM), dithiocarbamates started to lose their ability to promote Zn(2+) influx and to inhibit NF-kappaB activation. These results might provide insight into the appropriate use of dithiocarbamates in various disorders.

Animals↗

PubMed2000

A novel effect of rebamipide: generation of [Ca(2+)](i) oscillations through activation of CCK(1) receptors in rat pancreatic acinar cells.

The protective effect of 2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinon-4-yl]-propionic acid (rebamipide) on gastric mucosa is well established. Here we demonstrate that rebamipide acts on pancreatic acinar cells to generate oscillations of intracellular Ca(2+) concentration ([Ca(2+)](i)) through the activation of cholecystokinin subtype 1 (CCK(1)) receptors. At concentrations higher than 5 microM, rebamipide induced [Ca(2+)](i) oscillations in individual fura-2-loaded pancreatic acinar cells. The frequency of oscillations increased with increasing concentrations of rebamipide, while the latency between stimulation of cells and initiation of [Ca(2+)](i) oscillations decreased with increasing concentration. The [Ca(2+)](i) oscillations evoked by rebamipide were inhibited by the CCK(1) receptor antagonist L-364,718 but not by atropine or the CCK(2) receptor antagonist L-365,260 indicating that rebamipide is a nonpeptide CCK(1) receptor agonist.

Alanine↗

PubMed2000

Expression pattern of germ cell-specific genes in the testis of patients with nonobstructive azoospermia: usefulness as a molecular marker to predict the presence of testicular sperm.

OBJECTIVE: To analyze the expression pattern of testis-specific genes of patients with various spermatogenic defects and their usefulness as a molecular marker to predict the presence of testicular spermatozoa in patients with nonobstructive azoospermia undergoing IVF. DESIGN: Prospective, controlled study. SETTING: Hospital-based infertility research laboratory. PATIENT(S): Fifty-eight men with azoospermia or severe oligozoospermia. INTERVENTION(S): Testicular biopsy was done in the patients with obstructive or nonobstructive azoospermia, including Sertoli cell-only syndrome, maturation arrest, severe hypospermatogenesis, and normal spermatogenesis. MAIN OUTCOME MEASURE(S): Reverse transcriptase polymerase chain reaction was performed using 1 microgram of total RNA extracted from testicular tissues. Three pairs of primers were used for amplification of male germ cell-specific genes (DAZ, transcribed in male germ cells; PGK2, in late spermatocytes and spermatids; protamine-2, in spermatids) as molecular markers. Testicular sperm was obtained by multiple testicular sperm extraction. RESULT(S): The DAZ, PGK2, and protamine-2 genes were expressed in 38, 30, and 21 of the 43 patients with nonobstructive azoospermia, respectively. Testicular spermatozoa were successfully extracted in 4 of 43 patients with nonobstructive azoospermia with the use of multiple testicular sperm extraction. Detection of protamine-2 transcripts predicted the presence or absence of spermatozoa in the testicular tissue in 39 of 43 patients (91%). CONCLUSION(S): Expression of the protamine-2 gene may be a useful molecular marker to predict the presence of testicular sperm in patients with nonobstructive azoospermia.

Adult↗

PubMed2000

Semen quality over a 10-year period in 22,249 men in Korea.

A retrospective study was conducted in a large population presenting with infertility to determine whether sperm quality has changed in Korea in the last 10 years. We reviewed sperm concentration, motility and semen volume in 22,249 men from whom semen was collected in our laboratory between January 1989 and April 1998 and analysed according to WHO (1987) guidelines. Mean age of the men was 32 years (range 21-40). Data were collected in healthy men with infertility. The mean sperm concentration was 60.5 x 10(6)/mL from 1989 to 1998. There was no statistically significant difference for each year (p > 0.05). Semen volume and sperm motility were also unchanged during the same time period. There was no significant association between either age or year of birth and semen quality. Of the total population, 4033 men (19.0%) exhibited azoospermia and 8397 men (40. 1%) had normal semen parameters which satisfied the 1987 WHO criteria. The changes observed in the semen parameters analysed in this large population showed no evidence of deteriorating semen quality in Korea over the last 10 years.

Adult↗

PubMed2000

Na(+)-dependent transporters mediate HCO(3)(-) salvage across the luminal membrane of the main pancreatic duct.

To study the roles of Na(+)-dependent H(+) transporters, we characterized H(+) efflux mechanisms in the pancreatic duct in wild-type, NHE2(-/-), and NHE3(-/-) mice. The pancreatic duct expresses NHE1 in the basolateral membrane, and NHE2 and NHE3 in the luminal membrane, but does not contain NHE4 or NHE5. Basolateral Na(+)-dependent H(+) efflux in the microperfused duct was inhibited by 1.5 microM of the amiloride analogue HOE 694, consistent with expression of NHE1, whereas the luminal activity required 50 microM HOE 694 for effective inhibition, suggesting that the efflux might be mediated by NHE2. However, disruption of NHE2 had no effect on luminal transport, while disruption of the NHE3 gene reduced luminal Na(+)-dependent H(+) efflux by approximately 45%. Notably, the remaining luminal Na(+)-dependent H(+) efflux in ducts from NHE3(-/-) mice was inhibited by 50 microM HOE 694. Hence, approximately 55% of luminal H(+) efflux (or HCO(3)(-) influx) in the pancreatic duct is mediated by a novel, HOE 694-sensitive, Na(+)-dependent mechanism. H(+) transport by NHE3 and the novel transporter is inhibited by cAMP, albeit to different extents. We propose that multiple Na(+)-dependent mechanisms in the luminal membrane of the pancreatic duct absorb Na(+) and HCO(3)(-) to produce a pancreatic juice that is poor in HCO(3)(-) and rich in Cl(-) during basal secretion. Inhibition of the transporters during stimulated secretion aids in producing the HCO(3)(-)-rich pancreatic juice.

Animals↗

PubMed1999

Pyrithione, a zinc ionophore, inhibits NF-kappaB activation.

Pyrrolidine dithiocarbamate (PDTC) suppresses NF-kappaB activity and exhibits cytotoxic effects in bovine cerebral endothelial cells (BCECs), and we have previously reported that these PDTC effects were accompanied by an increase in intracellular zinc levels. To further explore the role of zinc in the modulation of NF-kappaB activation, we studied the effect of pyrithione, a zinc ionophore, on NF-kappaB activation in BCECs. Pyrithione inhibited NF-kappaB activity in a time- and dose-dependent manner. Ca-EDTA, but not Zn-EDTA, prevented pyrithione inhibition of NF-kappaB activity. Pyrithione increased the intracellular zinc level within 15 min. This effect was also abolished by Ca-EDTA, but not by Zn-EDTA. The potency of pyrithione on NF-kappaB inhibition and zinc influx was approximately one order of magnitude more potent than PDTC. These findings establish the regulatory role of intracellular zinc levels on NF-kappaB activity in BCECs.

Animals↗

PubMed1999

Monoacetyldiglycerides as new Ca2+ mobilizing agents in rat pancreatic acinar cells.

Several monoacetyldiglycerides were synthesized from glycerol in search for new Ca2+ mobilizing agent in vitro. All monoacetyldiglycerides except linolenoyl and phenlycyclopropylcarbonyl derivatives showed activity toward Ca2+ release in pancreatic acinar cells. Linoleoyl and docosahexaenoyl derivatives were chosen for further test and exhibited unique activity.

Acetylcholine↗

PubMed1999

Octanol blocks fluid secretion by inhibition of capacitative calcium entry in rat mandibular salivary acinar cells.

The aliphatic alcohol octanol is thought to modulate enzyme secretion from the exocrine pancreas by the inhibition of gap junction permeability. We have now investigated the effects of octanol on salivary secretion and intracellular calcium concentration ([Ca2+]i), measured in isolated perfused rat mandibular glands and in isolated mandibular acinar cells respectively. Stimulation of perfused glands with 10 microM carbachol (CCh) evoked a rapid increase in fluid secretion followed by a decrease to a sustained elevated level. Application of 1 mM octanol during CCh stimulation inhibited fluid secretion reversibly. In isolated acini, the CCh-induced [Ca2+]i increase was reversibly inhibited by the same concentration of octanol. However, octanol also inhibited the increase in [Ca2+]i in single acinar cells where gap junctions were no longer functional, indicating that octanol directly affected the intracellular Ca2+ signalling pathway. The initial increase in [Ca2+]i induced by 0.5-10 microM CCh, which is due to Ca2+ release from IP3-sensitive Ca2+ stores, was not affected by pretreatment with octanol. In contrast, CCh-, phenylephrine- or thapsigargin-induced Ca2+ entry was almost completely and reversibly inhibited by octanol. Octanol also blocked agonist-evoked Ca2+ entry in pancreatic acinar cells, and thapsigargin-evoked Ca2+ entry in fibroblasts. These data strongly suggest that octanol blocks salivary secretion from mandibular gland by the inhibition of capacitative Ca2+ entry, and raise the possibility that octanol may be a useful tool for inhibiting agonist-evoked Ca2+ entry pathways.

Animals↗

PubMed1999

Caffeine does not inhibit substance P-evoked intracellular Ca2+ mobilization in rat salivary acinar cells.

We used the Ca2+-sensitive fluorescent dye fura 2, together with measurements of intracellular D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], to assess the inhibitory effects of caffeine on signal transduction via G protein-coupled receptor pathways in isolated rat mandibular salivary acinar cells. ACh, norepinephrine (NE), and substance P (SP) all evoked substantial increases in the intracellular free Ca2+ concentration ([Ca2+]i). Responses to ACh and NE were markedly inhibited by prior application of 20 mM caffeine. The inhibitory effect of caffeine was not reproduced by phosphodiesterase inhibition with IBMX or addition of cell-permeant dibutyryl cAMP. In contrast to the ACh and NE responses, the [Ca2+]i response to SP was unaffected by caffeine. Despite this, SP and ACh appeared to mobilize Ca2+ from a common intracellular pool. Measurements of agonist-induced changes in Ins(1,4,5)P3 levels confirmed that caffeine inhibited the stimulus-response coupling pathway at a point before Ins(1,4,5)P3 generation. Caffeine did not, however, inhibit [Ca2+]i responses evoked by direct activation of G proteins with 40 mM F-. These data show that caffeine inhibits G protein-coupled signal transduction in these cells at some element that is common to the muscarinic and alpha-adrenergic signaling pathways but is not shared by the SP signaling pathway. We suggest that this element might be a specific structural motif on the G protein-coupled muscarinic and alpha-adrenergic receptors.

1-Methyl-3-isobutylxanthine↗

PubMed1999

Phagocytic activity of ethyl alcohol fraction of deer antler in murine peritoneal macrophage.

The mechanism of phagocytic activity of the ethyl alcohol fraction of Cervus nippon (CN-E) was investigated in vivo. The administration of CN-E (100 mg/kg, p.o.) enhanced lucigenin chemiluminescence and the engulfment of fluorescein-conjugated E. coli particles in murine peritoneal macrophages. Phagocytic activity was suppressed by the treatment of S-nitrosoglutathione (GSNO) which is an exogenous nitric oxide donor depending on the concentration of dose. CN-E suppressed the production of nitric oxide and enhanced the concentration in [Ca2+]i. The enhancement in [Ca2+]i was diminished by the treatment of EGTA. These results indicate that CN-E enhances the phagocytic activity of murine peritoneal macrophage via a suppression of nitric oxide production and an increase in [Ca2+]i.

Animals↗

PubMed1998

Regulation of cell volume and diffusion of intracellular water in salivary acinar cells.

The regulation of acinar cell volume and the properties of intracellular water were investigated in perfused rat mandibular salivary glands by proton nuclear magnetic resonance (NMR) spectroscopy. Using an inversion-recovery pulse sequence, and an extracellular relaxation reagent (10 mM Gd-DTPA) to suppress the proton NMR signal from extracellular water, acinar cell volume (intracellular water content) in unstimulated glands was shown to depend upon Cl- uptake by basolateral Na+-K+-2Cl- cotransport. Muscarinic and beta-adrenoceptor stimulation induced shrinkage and swelling respectively. In pulsed-field-gradient NMR experiments, the diffusion coefficient of intracellular water was found to be more than an order of magnitude smaller than that of extracellular water. Using this intrinsic difference in diffusivity between the two compartments, cell volume regulation was investigated in intact, perfused glands in the absence of relaxation reagents. Using both NMR techniques, acinar cells in perfused glands were observed to behave like simple osmometers in response to anisosmotic media, and did not show the volume regulatory responses described in dissociated acinar cells.

Animals↗

PubMed1998

Staurosporine-induced Ca2+ mobilization in rat mandibular salivary acini.

The effect of the protein kinase C inhibitor, staurosporine, on intracellular Ca2+ homeostasis was investigated in rat mandibular salivary acinar cells loaded with fura-2. Fura-2 fluorescence was measured at 510 nm while the excitation wavelength was alternated between 340 nm and 380 nm. The ratio of fluorescence intensity (F(340/380)) was used as an index of [Ca2+]i. Stimulation of acinar cells with 10 microM carbachol (CCh) induced a rapid increase in F(340/380) followed by a slow decrease to a sustained elevated level. Addition of 1 microM staurosporine in the presence of CCh caused a further increase in F(340/380). In order to examine whether the staurosporine-induced increase in F(340/380) could be attributed either to the Ca2+ entry pathway or to the mobilization of Ca2+ from intracellular Ca2+ stores, 1 microM staurosporine was added in the presence of CCh after Ca2+ had been omitted from the perfusate. Even in the absence of extracellular Ca2+, F(340/380) still increased slowly from 0.75 +/- 0.05 to 1.57 +/- 0.24 after a delay ranging between 5 min and 10 min. However, the IP3-sensitive intracellular Ca2+ stores did not seem to play a major role in this phenomenon because staurosporine still increased F(340/380) by 0.6 +/- 0.10 after the complete depletion of IP3-sensitive Ca2+ stores by the exposure of cells to 1 microM thapsigargin, a microsomal Ca2+ ATPase inhibitor, in Ca2+-free conditions. These results suggest that staurosporine mobilizes Ca2+ from IP3-insensitive intracellular Ca2+ stores in rat mandibular salivary acinar cells.

Animals↗

PubMed1997

Role of anions in the regulation of cell volume and intracellular pH in perfused rat mandibular salivary gland.

To investigate the role of Cl- in the regulation of the basolateral transporters of salivary acinar cells, we have measured cell volume and intracellular pH (pHi) in perfused rat mandibular glands using proton NMR spectroscopy and BCECF fluorometry respectively. When perfusate Cl- was replaced by glucuronate, isethionate, methylsulphate, nitrate or thiocyanate, cell volume decreased slowly by about 15% over a 10-min period. Replacement with bromide, which substitutes for Cl- on the Na+-K+-2Cl- cotransporter, caused only a small (4%) reduction in cell volume. Replacement of Cl- by glucuronate, isethionate or methylsulphate evoked a biphasic increase in pHi consisting of a rapid initial increase followed by a slower secondary rise whose time course was similar to that of cell shrinkage. As judged by the effects of HCO3- omission, 100 microM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and 1 mM amiloride, the initial rise in pHi was due to Cl-/HCO3- exchange while the secondary rise resulted from activation of Na+/H+ exchange. Although replacement of Cl- by nitrate or thiocyanate also caused cell shrinkage, these substituting anions were less effective in activating the exchanger. Therefore, while the upregulation of the exchanger following Cl- replacement may be due in part to cell shrinkage, there is also evidence for the involvement of an anion-sensitive regulatory mechanism. This would be consistent with the hypothesis that both changes in cell volume and in intracellular Cl- concentration contribute to the up-regulation of the exchanger following muscarinic stimulation.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗