Biomedical subjects

S Kato

Publications and source records attributed to S Kato.

At least 523 records · Page 29Linked to original sources

PubMed1998

Promotion of follicular antrum formation by pig oocytes in vitro.

Pig oocyte-cumulus-granulosa cell complexes (OCG complexes) from pig early antral follicles reorganise an antrum under the stimulation of FSH. The purpose of this study was to examine the role of the oocytes in antrum formation. In the first experiment, oocyte-cumulus complexes were removed from pig OCG complexes, and the antrum formation of parietal granulosa cells themselves (PGs) was examined. Antrum formation by sham-operated OCG complexes (OC/G complexes), in which the connections between the oocytes-cumulus complexes and the parietal granulosa cells had been disrupted, was also examined. The complexes were cultured for 8 days in collagen gels in the presence of 10 ng/ml FSH. Antra were formed in about 60% of the intact OCG complexes and the sham-operated OCG complexes, while only 20% of the PGs formed antra. In the second experiment, oocyte-cumulus complexes in the OCG complexes were replaced by denuded oocytes (O/G complexes) or Sephadex G-25 beads (B/G complexes) similar in diameter to the oocytes, and the two types of complexes were cultured under the same conditions. The O/G complexes formed antra to a similar extent as the OC/G complexes, whereas the B/G complexes scarcely formed any antra. The histological sections showed that the granulosa cells in the OC/G and O/G complexes were in intimate contact with each other and retained a shape similar to those in the ovarian follicles, while the granulosa cells in the PGs and B/G complexes became quite irregular in shape. These results suggest that pig oocytes promote contact between the granulosa cells to induce antrum formation in a physiological manner.

Animals↗

PubMed1998

Condensation pattern (CP) analysis of plant chromosomes by an improved chromosome image analysing system, CHIAS III.

The third-generation chromosome image analysing system (CHIAS III) was developed by using an ordinary personal computer with public domain imaging software, the NIH Image. An uneven condensation pattern (CP) appearing on small sugarcane chromosomes at the mitotic prometaphase stage was analysed and a quantitative chromosome map or idiogram was developed by using CHIAS III. The analysis consists of three major steps as follows: (1) manipulation of original chromosome images and measurement of CP or numerical data of the CP; (2) calculation of an averaged CP for homologous chromosomes; and (3) development of an idiogram based on the averaged CP. The CP has been analysed quantitatively by using the first- and the second-generation chromosome image analysing systems with hard- and software specific to the systems. The data obtained using CHIAS III are consistent with those obtained with the chromosome image analysing systems previously developed.

Chromosomes↗

PubMed1998

Effects of cyclooxygenase-2 selective and nitric oxide-releasing nonsteroidal antiinflammatory drugs on mucosal ulcerogenic and healing responses of the stomach.

Effects of selective cyclooxygenase-2 (COX-2) inhibitors (NS-398) and nitric oxide (NO) -releasing aspirin (NO-ASA) on gastric ulcerogenic and healing responses were examined in comparison with nonselective COX inhibitors such as indomethacin and aspirin (ASA). Hypothermic stress (28-30 degrees C, 4 hr) induced gastric lesions in anesthetized rats with an increase of acid secretion. The lesions induced by hypothermic stress were markedly worsened by subcutaneous administration of both indomethacin and ASA but were not affected by either NS-398 or NO-ASA, although the increased acid secretion during hypothermia was not affected by any of the drugs. On the other hand, the healing of gastric ulcers induced in mice by thermal cauterization (70 degrees C, 15 sec) was significantly delayed by daily subcutaneous administration of indomethacin and ASA as well as NS-398, but not by NO-ASA. COX-2 mRNA was not detected in the intact mucosa but was positively expressed in the ulcerated mucosa, most potently on day 3 after ulceration. Prostaglandin contents in the intact mouse stomach were reduced by indomethacin, ASA, and NO-ASA, while the increased prostaglandin generation in the ulcerated mucosa was inhibited by all drugs including NS-398. After subcutaneous administration of NO-ASA to pylorus-ligated rats and mice, high amounts of NOx were detected in both the gastric contents and serum. In addition, both NS-398 and NO-ASA showed an equipotent antiinflammatory effect against carrageenan-induced paw edema in rats as compared with indomethacin and ASA. These results suggest that both indomethacin and ASA not only increased the mucosal ulcerogenic response to stress but impaired the healing response of gastric ulcers as well. The former action was due to inhibition of COX-1, while the latter effect was accounted for by inhibition of COX-2 and was mimicked by the COX-2-selective inhibitor NS-398. NO-ASA, although it inhibited both COX-1 and COX-2 activity, had no deleterious effects on gastric ulcerogenic and healing responses.

Animals↗

PubMed1998

Role of nitric oxide in regulation of gastric acid secretion in rats: effects of NO donors and NO synthase inhibitor.

1. The role of nitric oxide (NO) in the regulation of acid secretion was examined in the anaesthetized rat. 2. A rat stomach was mounted in an ex vivo chamber, instilled with 2 ml of saline every 15 min, and the recovered sample was titrated at pH 7.0 against 0.1 N NaOH by use of an automatic titrator for acid secretion. Gastric mucosal blood flow (GMBF) was measured simultaneously by laser Doppler flowmeter. 3. Intragastric application of NO donors such as FK409 (3 and 6 mg ml[-1]) and sodium nitroprusside (SNP; 6 and 12 mg ml[-1]) as well as i.p. administration of cimetidine (60 mg kg[-1]), a histamine H2-receptor antagonist, significantly inhibited the increase in acid secretion in response to pentagastrin (60 microg kg(-1) h(-1), i.v.), in doses that increased gastric mucosal blood flow (GMBF). 4. Intragastric application of FK409 (6 mg ml[-1]) increased both basal and stimulated acid secretion induced by YM-14673 (0.3 mg kg(-1), i.v.), an analogue of thyrotropin-releasing hormone (TRH), but had no effect on the acid secretory response induced by histamine (4 mg kg(-1) h(-1), i.v.). 5. Pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME; 10 mg kg(-1), i.v.) did not affect basal acid secretion, but significantly potentiated the increase in acid secretion induced by YM-14673 and slightly augmented the acid secretory response to pentagastrin. 6. Both pentagastrin and YM-14673 increased the release of nitrite plus nitrate (NOx), stable NO metabolites, into the gastric lumen, and these changes were completely inhibited by prior administration of L-NAME (10 mg kg(-1), i.v.). 7. Pentagastrin caused an increase in luminal release of histamine and this response was significantly suppressed by intragastric application of FK409 (6 mg ml[-1]). 8. These results suggest that either exogenous or endogenous NO has an inhibitory action on gastric acid secretion through suppression of histamine release from enterochromaffin-like (ECL) cells.

Animals↗

PubMed1998

Desensitization and resensitization of delta-opioid receptor-mediated Ca2+ channel inhibition in NG108-15 cells.

1. To approach the mechanisms underlying desensitization of the opioid receptor-mediated Ca2+ channel inhibition, the effects of prolonged application of [D-Ala2, D-Leu5]enkephalin (DADLE) on Ba2+ currents (I(Ba)) through Ca2+ channels were analysed in NG108-15 neuroblastoma x glioma hybrid cells. 2. Inhibition of I(Ba) by 100 nM DADLE desensitized by 57% with a time constant of 4.4 min. 3. Maximal desensitization of the delta-opioid receptor-Ca2+ channel coupling was attained by 1 microM DADLE. The EC50 value for desensitization was estimated to be 78 nM. 4. RNA blot hybridization analysis and immunoblot analysis revealed the expression of beta-adrenoceptor kinase-1 (betaARK1) in NG108-15 cells. 5. Heparin, an inhibitor of betaARK, significantly reduced the magnitude and rate of desensitization, whereas Rp-cyclic AMPS and PKI (14-24)amide, inhibitors of cyclic AMP-dependent protein kinase (PKA), or long-term treatment with phorbol 12-myristate 13-acetate to induce down-regulation of protein kinase C (PKC) had no significant effect. 6. Recovery from desensitization (resensitization) proceeded with a time constant of 6.7 min. Okadaic acid, an inhibitor of serine/threonine phosphatases 1 and 2A, significantly attenuated the degree of resensitization. 7. In summary, we have characterized the time course and concentration-dependence of the desensitization of DADLE-induced I(Ba) inhibition in NG108-15 cells. This desensitization was reversible after removal of DADLE. It is suggested that betaARK, but neither PKA nor PKC, is involved in desensitization, while serine/threonine phosphatases mediate resensitization.

Animals↗

PubMed1998

Role of p300, a transcriptional coactivator, in signalling of TGF-beta.

BACKGROUND: Smad proteins are novel transcriptional regulators mediating the signalling of the transforming growth factor-beta (TGF-beta) superfamily. Coactivators such as p300/CBP promote transactivation by various transcription factors through a direct interaction with them. Adenoviral oncoprotein E1A, which binds p300, was shown to inhibit the signalling of TGF-beta. These findings raise the possibility that p300 may be involved in TGF-beta signalling. RESULTS: We investigated whether p300 is involved in transactivation by Smads. p300 enhanced the Smad-induced transactivation of p3TP-Lux, a TGF-beta responsive reporter. E1A inhibited this enhancement, and the inhibition required its ability to bind p300/CBP. p300 and Smad3, as well as Smad2, interacted in vivo in a ligand-dependent manner. The binding region in Smad3 was its C-terminal half that was previously shown to possess an intrinsic transactivation activity. The binding region in p300 was mapped to its C-terminal 678 amino acids. The minimal Smad2/3-interacting region, as well as the rest of the p300, inhibited the transactivation of p3TP-Lux in a dominant-negative fashion. CONCLUSION: p300 interacted with Smad2 and Smad3 in a ligand-dependent manner, and enhanced the transactivation by Smads. Our results present the molecular basis of the transactivation by Smad proteins.

Adenovirus E1A Proteins↗

PubMed1998

T-cell clonal change after allo-kidney transplantation in humans.

Whether T cells circulating peripherally express changes at a clonal level after renal transplantation is uncertain. To clarify this issue, we analyzed T-cell clonality of peripheral blood lymphocytes (PBLs) in 12 renal transplant recipients by a novel polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method that can discriminate T-cell clones with different T-cell receptor (TCR) Vbeta motifs. The PCR-SSCP study showed that after transplantation, only a few distinct T-cell clonotypes accumulated in the absence of clinical episodes, irrespective of the compatibility of HLA antigens. In contrast, various T-cell clones appeared in cases of acute rejection (AR) and infection. These subsided immediately after the AR was resolved; however, they remained long after the resolution of the infection. In a case of AR followed by an infectious episode, distinct T-cell clones appeared concomitantly with each episode. Several of them disappeared or remained thereafter. In one case, significant numbers of accumulating bands were observed by in-vitro stimulation by mixed lymphocyte reaction (MLR); several were identical to those found in vivo. However, some of those that did not appear in vitro were apparent in vivo. In conclusion, the appearance of T-cell clonotypes at a peripheral level indicates the existence of immunologically activated T-cell clones, which were significantly affected by immunosuppressive therapy. It was also determined that the T-cell immune system is much more complicated in vivo than in vitro.

Abscess↗

PubMed1998

Activation of phospholipase A2 by the nociceptin receptor expressed in Chinese hamster ovary cells.

To gain insight into the molecular mechanism for nociceptin function, functional coupling of the nociceptin receptor expressed in Chinese hamster ovary (CHO) cells with phospholipase A2 (PLA2) was examined. In the presence of A23187, a calcium ionophore, activation of the nociceptin receptor induced time- and dose-dependent release of arachidonate, which was abolished by pretreatment of the cells with pertussis toxin (PTX). Immunoblot analysis using anti-Ca2+-dependent cytosolic PLA2 (cPLA2) monoclonal antibody demonstrates that activation of the nociceptin receptor induces a time- and dose-dependent electrophoretic mobility shift of cPLA2, suggesting that phosphorylation of cPLA2 is induced by the nociceptin receptor. Pretreatment of the cells with PD98059, a specific mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 inhibitor, or staurosporine, a potent inhibitor of serine/threonine protein kinases and tyrosine protein kinases, partially inhibited the nociceptin-induced cPLA2 phosphorylation and arachidonate release. These results indicate that the nociceptin receptor expressed in CHO cells couples with cPLA2 through the action of PTX-sensitive G proteins and suggest that cPLA2 is activated by phosphorylation induced by the nociceptin receptor via mechanisms partially dependent on p44 and p42 mitogen-activated protein kinases.

Animals↗

PubMed1998

Actions of hepatocyte growth factor as a local modulator in the kidney: potential role in pathogenesis of renal disease.

Endothelial cells are known to secrete various vasoactive substances that may control mesangial cell growth, whereas mesangial cells also secrete various growth factors and cytokines that may regulate endothelial cells. Therefore, it is apparent that cell-cell interactions among renal cells are important in the control of renal function. Indeed, co-culture of endothelial cells with mesangial cells resulted in a significant decrease in mesangial cell growth. However, the exact mechanisms of maintaining the cell-cell interactions are not yet understood. We have focused on the role of hepatocyte growth factor (HGF) in the regulation of cell-cell interactions, since HGF has been reported to have many organ protective functions in the kidney. Our present data demonstrated that addition of recombinant HGF (rHGF) stimulated DNA synthesis and growth of endothelial cells in a dose-dependent manner. However, there was no stimulatory effect of rHGF on the growth of mesangial cells in the time and dose-dependent manner. Therefore, we examined the presence of the local renal HGF system and its potential role in renal disease. The presence of secreted local HGF was observed in the conditioned medium from endothelial and mesangial cells. The presence of HGF mRNA was also detected in endothelial and mesangial cells. Interestingly, the specific receptor of HGF, c-met, was also expressed in both cells. Next, regulation of local HGF secretion was studied under stimulation with rHGF, angiotensin (Ang) II, and transforming growth factor (TGF)-beta. Of importance, rHGF significantly stimulated local HGF secretion from mesangial cells by positive feedback. In contrast, TGF-beta significantly decreased HGF secretion in mesangial cells and endothelial cells. Angiotensin II also significantly decreased local HGF production in mesangial cells in a dose-dependent manner. Finally, the effect of local HGF production from mesangial cells was studied using a co-culture system. Co-culture of mesangial cells with endothelial cells resulted in a significant increase in number of endothelial cells, which was abolished by co-incubation with neutralizing anti-HGF antibody. Overall, these results demonstrated the local production of HGF, which has stimulatory effects on growth of endothelial cells, but not mesangial cells. Local HGF secretion from mesangial cells may maintain the growth of endothelial cells. Negative regulation of local HGF production by Ang II and TGF-beta may play an important role in the pathogenesis of renal disease. Taken together, dysfunction of cell-cell regulation in the kidney due to decreased local HGF production may be an initial trigger for the development of renal disease such as glomerulonephritis.

Angiotensin II↗

PubMed1998

Safety and efficacy of one-week triple therapy for eradicating Helicobacter pylori in children.

BACKGROUND: Proton pump inhibitor-based eradication therapy of Helicobacter pylori has been widely studied in adults, but there have been only a few reports about this therapy in children. The purpose of this study was to investigate the safety and efficacy of 1-week triple therapy for eradication of H. pylori and ulcer healing in children. PATIENTS AND METHODS: We prospectively studied 15 patients aged 2-17 years (5 with gastric ulcers, 8 with duodenal ulcers, and 2 with nodular gastritis alone). Three patients had H2 blocker-resistant duodenal ulcers. Patients received 0.75 mg/kg of lansoprazole b.i.d., 25 mg/kg of amoxicillin b.i.d., and 10 mg/kg of clarithromycin b.i.d. for 7 days. No additional therapy (including antisecretory drugs) was administered to any patients following eradication therapy. Patients underwent endoscopy to obtain antral biopsies (culture, urease test and histology) and to evaluate the mucosal status, and underwent a 13C-urea breath test before and 4-8 weeks after the completion of a 1-week course of therapy. RESULTS: All patients received the full drug regimen. Endoscopy showed complete healing of ulcers in 12 of 13 patients with peptic ulcer disease (92%). H. pylori was eradicated in 13 of 15 patients (87%). Diarrhea and/or an altered taste sensation occurred in 5 patients (33%). There were no hematological or biochemical abnormalities related to therapy. CONCLUSION: The 1-week triple therapy was safe and effective for eradicating H. pylori. The present study showed that ulcer healing in juveniles is closely associated with eradication of H. pylori, and that no additional therapy is required when H. pylori is eradicated. A shorter course of eradication therapy than 2 weeks may be suitable for children with H. pylori infection.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed1998

Small advanced colorectal adenocarcinomas: report on three cases.

Small advanced cancers (less than 10 mm in size) have rarely been described in the literature, mainly due to their difficult endoscopic diagnosis. A total of 5120 colonoscopic examinations were performed at the National Cancer Center Hospital East; three cases (0.05%) of small advanced cancer were found. The indigo carmine dye spraying technique with magnifying endoscopy was used for diagnosis. All cases were flat and depressed lesions (8, 9 and 9 mm in size respectively) with V type pit pattern at the magnifying observation. Histology showed three cancers with invasion to the proper muscle layer and two cases of lymph node metastasis. K-ras point mutation was negative in all cases, while p53 stained in two out of the three cases (one diffuse and one focal). It is concluded that small advanced colorectal adenocarcinomas are a reality. Our data on their macroscopic appearance and histology confirm their high malignant potential.

Adenocarcinoma↗

PubMed1998

Beneficial effect of long-term combined treatment with voglibose and pioglitazone on pancreatic islet function of genetically diabetic GK rats.

Effects of voglibose (an alpha-glucosidase inhibitor) and pioglitazone (an insulin sensitizer) on glycemic control and on the function of pancreatic islets were evaluated using Goto-Kakizaki (GK) rats with non-insulin-dependent diabetes mellitus (NIDDM). Five week administration (8-13 weeks of age in GK rats) of voglibose alone (added to the chow at a concentration of 10 ppm), pioglitazone alone (10 mg/kg daily p.o.), or both of the agents together significantly improved fasting plasma glucose levels and those at 120 min in oral glucose tolerance tests. Insulin secretory capacity in response to glucose of the isolated islets, assessed by batch incubation, was significantly improved in the voglibose and in the voglibose plus pioglitazone groups. Eight-week administration (5-13 weeks of age) of voglibose and voglibose plus pioglitazone successfully lowered the fasting levels of plasma glucose and triglyceride. The glucose-responsiveness in insulin release from the islets was also significantly recovered by the therapy. The treatment increased the insulin content of the islets to almost twice that in untreated controls. Thus, treatment by these drugs can not only effectively ameliorate the metabolic derangement of NIDDM in GK rats, but it can also restore the deteriorated islet function, possibly through protection from glucose toxicity.

Animals↗

PubMed1998

Effects of calcium and bicarbonate on head-to-head agglutination in ejaculated boar spermatozoa.

The present study was conducted to reveal the effects of calcium and bicarbonate on the occurrence of head-to-head agglutination in ejaculated boar spermatozoa in vitro. Boar spermatozoa were washed and incubated in a modified Krebs-Ringer bicarbonate (mKRB) in a 37 degrees C CO2 incubator (5% CO2 in air) for 1-5 h. Before and after the incubation, aliquots of each sperm sample were fixed, smeared on glass slides, and stained with a phosphate-buffered solution of Giemsa to assess the percentages of head-to-head agglutinated spermatozoa. Before the incubation, only 5-12% of the spermatozoa were agglutinated. After the 1-h incubation, however, the percentage of head-to-head agglutinated spermatozoa rose to approximately 50%, followed by only minor increases thereafter. This rise was dependent on the concentrations of calcium chloride contained in the mKRB and was attenuated by the addition of 2 mM [ethylenebis(oxyethylenenitrilo)]tetra-acetic acid (EGTA) to the medium. Moreover, the replacement of sodium bicarbonate with 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (Hepes) in the medium and treatment with ruthenium red, which have both been shown previously to inhibit calcium uptake by boar spermatozoa, significantly reduced the rise. Based on these findings, it was concluded that extracellular calcium and bicarbonate are key factors regulating head-to-head agglutination in boar spermatozoa. The possible relationship between agglutinability and the fertilizing ability of boar spermatozoa is also discussed.

Animals↗

PubMed1998

Astrocytoma and B-cell lymphoma development in a man with a p53 germline mutation.

We report a case with a germline mutation of the p53 gene develpoing both a non-Hodgkin's lymphoma and an astrocytoma. The astrocytoma could be cured by two operations and combined chemotherapy but 33 months after the onset of the disease, he suffered from a diffuse, large cell centroblastic malignant lymphoma of B-cell lineage. In spite of clear rearranged fragments observed with IgH and c-MYC gene probes, we could not diagnose a Burkitt's lymphoma morphologically. The malignant lymphoma was chemoresistant and the patient died of multi-organ failure. He was confirmed to have a germline mutation of the p53 gene by analysis of c-DNA from peripheral lymphocytes and loss of heterozygosity (LOH) of p53 was evident in the lymphoma. The results were suggestive of the Li-Fraumeni syndrome (LFS), a rare autosomal dominantly inherited syndrome with a germline mutation of p53 gene and diverse malignancies, but this could not be confirmed in the present case. Alternatively, a de novo mutation could have been involved.

Abdominal Neoplasms↗

PubMed1998

Growth patterns and genetic changes of colorectal carcinoma.

BACKGROUND: Recent Japanese studies have shown that histogenesis of small colorectal carcinomas can be divided into two groups: polypoid growth arising from polypoid neoplasia, and nonpolypoid growth arising from flat or depressed neoplasia. This classification should be verified with genetic as well as morphologic characteristics. SUBJECTS AND METHODS: In order to classify our subject into polypoid growth and nonpolypoid growth types both histologically and endoscopically, we selected 42 colorectal carcinomas < 2 cm in size (35 submucosal and seven more advanced). Clinicopathological findings, presence or absence of Ki-ras gene mutation and overexpression of p53 protein were compared between the two types. RESULTS: Histologically, the cases were divided into 27 of the polypoid growth type and 15 of the nonpolypoid growth type. None of the nonpolypoid growth cases contained adenomatous remnant, wheras this was found in 75% of the polypoid growth cases. No Ki-ras mutation was observed in any of the nonpolypoid growth cases, although it appeared in 44% of the polypoid growth cases. Regarding the overexpression of p53 protein, no significant difference was observed between the two types. The histological and the colonoscopic polypoid growth-nonpolypoid growth classifications correlated well with each other (agreement rate 98%), except for one lesion, which was classified as polypoid growth type endoscopically but as nonpolypoid growth type histologically. CONCLUSIONS: The histologically defined polypoid growth-nonpolypoid growth classification may indicate a difference in pathway of colorectal carcinogenesis. Also, colonoscopic polypoid growth-nonpolypoid growth classification is available for preoperative estimation of the genetic characteristics of small carcinomas.

Adenoma↗

PubMed1998

Cloning of human polyubiquitin cDNAs and a ubiquitin-binding assay involving its in vitro translation product.

During large-scale in vitro translation analysis of a human full-length cDNA bank, we found a clone producing a remarkably smaller translation product than that expected from the open reading frame. The cDNA encodes a polyubiquitin, UbC, composed of nine tandem repeats of the ubiquitin unit. The bank contained twelve UbC cDNAs including four full-length ones. Sequencing analysis of these clones showed that UbC cDNAs can be classified into two types, UbC1 and UbC2, in each of which there are six polymorphic nucleotide variations. The present UbC cDNA was in vitro translated in a rabbit reticulocyte or wheat germ extract to produce a free ubiquitin labeled with [35S]methionine. The labeled ubiquitin could be used as a substrate for thiol ester formation with ubiquitin-activating enzyme E1 or ubiquitin-conjugating enzyme E2.

Amino Acid Sequence↗

PubMed1998

Effects of glycosaminoglycans on the development of in vitro-matured and -fertilized porcine oocytes to the blastocyst stage in vitro.

We examined the effects of four glycosaminoglycans (GAGs) on the development of in vitro-matured (IVM) and -fertilized (IVF) porcine oocytes to the blastocyst stage. IVM and IVF oocytes were cultured in Whitten's medium supplemented with hyaluronic acid, chondroitin sulfate A, dermatan sulfate, or heparin at 38.5 degrees C in an atmosphere of 5% CO2 in humidified air for up to 6 days. After 2 days in culture, 28-34% of the inseminated oocytes cleaved to the 2- to 8-cell stage, and the GAGs showed no significant effect on development. After 6 days in culture, blastocysts were observed in all groups. The percentage of blastocysts was significantly higher in hyaluronic acid-supplemented medium (14%) than in dermatan sulfate-supplemented (5%), heparin-supplemented (2%), or nonsupplemented (2%) media. In addition, the percentage of blastocysts was significantly higher in chondroitin sulfate A-supplemented medium (11%) than in heparin-supplemented and nonsupplemented media, although the number of blastocysts in chondroitin sulfate A was not significantly different from that in hyaluronic acid- and dermatan sulfate-supplemented media. There were no significant differences in the mean number of nuclei per blastocyst cultured in any group. The effects of hyaluronic acid and chondroitin sulfate A on development to the blastocyst stage was examined at various concentrations. After 6 days in culture, development of IVM and IVF oocytes to the blastocyst stage was best supported in 0.5 mg/ml hyaluronic acid-supplemented (17%) and in 0.1 or 0.5 mg/ml chondroitin sulfate A-supplemented (10% or 9%, respectively) media. It is concluded from these results that hyaluronic acid and chondroitin sulfate A supported the development of porcine oocytes matured and fertilized in vitro to the blastocyst stage.

Animals↗

PubMed1998

Partial agonistic activity of naloxone on the opioid receptors expressed from complementary deoxyribonucleic acids in Chinese hamster ovary cells.

UNLABELLED: Naloxone is a widely used opioid antagonist. To analyze the cellular responses induced by naloxone in the absence of opioid agonists, Chinese hamster ovary (CHO) cells, which do not endogenously express the opioid receptors, have been permanently transfected with the cloned complementary DNAs to produce the mu-, delta-, and kappa-opioid receptors. Naloxone dose-dependently reduced forskolin-stimulated cyclic adenosine monophosphate (cAMP) formation in the cells expressing the mu- and kappa-opioid receptors, although the effect was less than that of opioid agonists [D-Ala2, N-Me-Phe4, Gly-ol5]enkephalin and U50,488, respectively. The naloxone-induced cAMP reduction was abolished by pretreatment of the cells with pertussis toxin, which suggests that pertussis toxin-sensitive G proteins (Gi and/or Go) are involved in the response. Cellular guanosine triphosphatase activity was significantly increased by naloxone in the cells expressing the mu- and kappa-opioid receptors, which suggests that the application of naloxone to these receptors induces activation of the G proteins. We conclude that naloxone possesses partial agonistic activity on the mu- and kappa-opioid receptors expressed from complementary DNAs in CHO cells. IMPLICATIONS: In this study, we examined whether naloxone has agonistic activity on the opioid receptors by using cultured cells transfected with delta-, mu-, and kappa-opioid receptor complementary DNAs. Our data indicate that naloxone is a partial agonist on the mu- and kappa-opioid receptors.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗