Preferential distribution of active RNA polymerase II molecules in the nuclear periphery

We have combined immunogold labeling with the Miller spreading technique in order to localize proteins at the electron microscope (EM) level in whole mount nuclei from mouse and human fibroblasts. Anti-histone H1 antibody labels nuclei uniformly, indicating that the nuclear interior is accessible to both antibodies and gold conjugates. Anti-topoisomerase I antibody labels nucleoli intensely, in agreement with previous immunofluorescent and biochemical data. Two different antibodies against the large subunit of RNA polymerase II (pol II) show preferential labeling of the nuclear periphery, as do antibodies against lamin, a known peripheral nuclear protein. Treatment of cells with alpha-amanitin results in loss of virtually all RNA polymerase II staining, supporting the specificity of labeling. Finally, when nuclei are incubated in the presence of biotin-UTP (bio-UTP) under run-off transcription conditions, incorporation is preferentially located at the nuclear periphery. These results support the conclusions that transcriptionally active pol II molecules are non-uniformly distributed in fibroblast nuclei, and that their differential distribution mirrors that of total pol II.

Mechanisms of vasorelaxation induced by total flavonoids of Euphorbia humifusa in rat aorta

Euphorbia humifusa Willd. (EH), rich in flavonoids, has long been used for the treatment of bacillary dysentery and enteritis in China, and is known to have antioxidant, hypotensive and hypolipidemic properties. However, the vasorelaxant effect of total flavonoids of EH (TFEH) and action mechanisms are not clearly defined yet. The aim of the present study was to investigate the effects of TFEH on the vascular tension and its underlying mechanisms. Experiments were performed in rat thoracic aorta using the organ bath system. TFEH (0.01 - 100 μg/ml) caused a concentration-dependent vasorelaxation, which was dependent on a functional endothelium, and were significantly attenuated by inhibitors of endothelial NO synthase, its upstream signaling pathway, PI3K/Akt, and soluble guanylate cyclase, but not by blockade of K_Ca channel, K_ATP channel, cyclooxygenase, muscarinic and β-adrenergic receptors. Extracellular Ca²⁺ depletion, and pre-treatment with modulators of the store-operated Ca²⁺ entry channels, Gd³⁺ and 2-aminoethyl diphenylborinate, significantly attenuated the TFEH-induced vasorelaxation. Our findings suggest that TFEH elicit vasorelaxation via endothelium-dependent NO-cGMP pathway through activation of PI3K/Akt- and Ca²⁺-eNOS-NO signaling. Further, it is suggested that TFEH-induced activation of the NO-soluble guanylate cyclase-cGMP-protein kinase G signaling relaxes vascular smooth muscle cells through an inhibition of the L-type Ca²⁺ channel activity.

Ethical foundations of the radiological protection system

The International Commission on Radiological Protection (ICRP) has established Task Group 94 under Committee 4 to develop a report on the ethical foundations of the system of radiological protection. The aim of this report is to consolidate the basis of ICRP recommendations, to improve understanding of the system, and to provide a basis for communication on radiation risk and its perception. Through a series of workshops organised by the Commission in cooperation with the International Radiation Protection Association and its associate societies involving radiological protection professionals and specialists of ethics around the world, Task Group 94 has identified the key ethical and social values underpinning the system of radiological protection. The purpose of eliciting the ethical principles and values of the radiological protection system is not only to clarify the rationale for recommendations made by the Commission, but also to assist in discussions related to its practical implementation. A clear understanding of the ethical principles will help resolve dilemmas caused by potential conflicts in actions that might be considered, or decisions that must be made.

Rumex acetosa L. induces vasorelaxation in rat aorta via activation of PI3-kinase/Akt- AND Ca(2+)-eNOS-NO signaling in endothelial cells

Rumex acetosa L. (RA) (Polygonaceae) is an important traditional Chinese medicine (TCM) commonly used in clinic for a long history in China and the aerial parts of RA has a wide variety of pharmacological actions such as diuretic, anti-hypertensive, anti-oxidative, and anti-cancer effects. However, the mechanisms involved are to be defined. The purpose of the present study was to evaluate the vasorelaxant effect and define the mechanism of action of the ethanol extract of Rumex acetosa L. (ERA) in rat aorta. ERA was examined for its vascular relaxant effect in isolated phenylephrine-precontracted rat thoracic aorta and its acute effects on arterial blood pressure. In addition, the roles of the nitric oxide synthase (NOS)-nitric oxide (NO) signaling in the ERA-induced effects were tested in human umbilical vein endothelial cells (HUVECs). The phosphorylation levels of Akt and eNOS were assessed by Western blot analysis in the cultured HUVECs. ERA induced endothelium-dependent vasorelaxation. The ERA-induced vasorelaxation was abolished by L-NAME (an NOS inhibitor) or ODQ (a sGC inhibitor), but not by indomethacin. Inhibition of PI3-kinase/Akt signaling pathway markedly reduced the ERA-induced vasorelaxation. In HUVECs, ERA increased NO formation in a dose-dependent manner, which was inhibited by L-NAME and by removing extracellular Ca(2+). In addition, ERA promoted phosphorylation of Akt and eNOS, which was prevented by wortmannin and LY294002, indicating that ERA induces eNOS phosphorylation through the PI3-kinase/Akt pathway. Further, in anesthetized rats, intravenously administered ERA decreased arterial blood pressure in a dose-dependent manner through an activation of the NOS-NO system. In summary, the ERA- induced vasorelaxation was dependent on endothelial integrity and NO production, and was mediated by activation of both the endothelial PI3-kinase/Akt- and Ca(2+)-eNOS-NO signaling and muscular NO-sGC-cGMP signaling.

Effect of Medicinal Plant By-products Supplementation to Total Mixed Ration on Growth Performance, Carcass Characteristics and Economic Efficacy in the Late Fattening Period of Hanwoo Steers

This study was conducted to evaluate the effect of medicinal plant by-products (MPB) supplementation to a total mixed ration (TMR) on growth, carcass characteristics and economic efficacy in the late fattening period of Hanwoo steers. Twenty seven steers (body weight [BW], 573±57 kg) were assigned to 3 treatment groups so that each treatment based on BW contained 9 animals. All groups received ad libitum TMR throughout the feeding trial until slaughter (from 24 to 30 months of age) and treatments were as follows: control, 1,000 g/kg TMR; treatment 1 (T1), 970 g/kg TMR and 30 g/kg MPB; treatment 2 (T2), 950 g/kg TMR and 50 g/kg MPB. Initial and final BW were not different among treatments. Resultant data were analyzed using general linear models of SAS. Average daily gain and feed efficiency were higher (p<0.05) for T1 than control, but there was no difference between control and T2. Plasma albumin showed low-, intermediate- and high-level (p<0.05) for control, T1 and T2, whereas non-esterified fatty acid was high-, intermediate- and high-level (p<0.05) for control, T1 and T2, respectively. Carcass weight, carcass rate, backfat thickness and rib eye muscle area were not affected by MPB supplementation, whereas quality and yield grades were highest (p<0.05) for T1 and T2, respectively. Daily feed costs were decreased by 0.5% and 0.8% and carcass prices were increased by 18.1% and 7.6% for T1 and T2 compared to control, resulting from substituting TMR with 30 and 50 g/kg MPB, respectively. In conclusion, the substituting TMR by 30 g/kg MPB may be a potential feed supplement approach to improve economic efficacy in the late fattening period of Hanwoo steers.

Edge profile measurements using Thomson scattering on the KSTAR tokamak

In the KSTAR Tokamak, a "Tangential Thomson Scattering" (TTS) diagnostic system has been designed and installed to measure electron density and temperature profiles. In the edge system, TTS has 12 optical fiber bundles to measure the edge profiles with 10-15 mm spatial resolution. These 12 optical fibers and their spatial resolution are not enough to measure the pedestal width with a high accuracy but allow observations of L-H transition or H-L transitions at the edge. For these measurements, the prototype ITER edge Thomson Nd:YAG laser system manufactured by JAEA in Japan is installed. In this paper, the KSTAR TTS system is briefly described and some TTS edge profiles are presented and compared against the KSTAR Charge Exchange Spectroscopy and other diagnostics. The future upgrade plan of the system is also discussed in this paper.

Cardiovascular effects of ethanol extract of Rubus chingii Hu (Rosaceae) in rats: an in vivo and in vitro approach

Rubus chingii Hu (Rosaceae) is an important traditional Chinese medicine that has been used to improve function of the kidney and treat excessive polyuria. However, the effects of Rubus chingii on the cardiovascular system and its pharmacological mechanisms of action have not been studied. The aim of the present study was to evaluate the cardiovascular effects of ethanol extract of Rubus chingii (ERC) in rats. The changes in systolic blood pressure and heart rate of rats and vascular tone of aortic rings in in vitro were measured using pressure transducer and force transducer, respectively, connected to a multichannel recording system. ERC decreased systolic blood pressure and heart rate in a concentration-dependent manner. ERC induced vasorelaxation in a concentration-dependent manner. The ERC-induced vasorelaxation was not observed in the absence of the endothelium. The vasorelaxant effect of ERC was significantly attenuated by inhibition of endothelial NO synthase (eNOS), soluble guanylyl cyclase (sGC), or Ca(2+) entry from extracellular sources with L-NAME, ODQ, diltiazem, or extracellular Ca(2+) depletion, respectively. Similarly, an inhibition of Akt with wortmannin attenuated the ERC-induced vasorelaxation. Modulators of the store-operated Ca(2+) entry, thapsigargin, Gd(3+), and 2-aminoethyl diphenylborinate markedly attenuated the ERC-induced vasorelaxation. Furthermore, 4-aminopyridine an inhibitor of voltage-dependent K(+) (KV) channel, significantly attenuated the ERC-induced vasorelaxation. However, tetraethylammonium and glibenclamide, had no significant effect on the ERC-induced vasorelaxation. Indomethacin, atropine, and propranolol had no effects on the ERC-induced vasorelaxation. The present study demonstrates that ERC induces vasorelaxation via endothelium-dependent two-step signaling: an activation of the Ca(2+)-eNOS-NO signaling in the endothelial cells and then subsequent stimulation of the NO-sGC-cGMP-KV channel signaling in the vascular smooth muscle cells. The Akt-eNOS pathway is also suggested to be involved in this relaxation. Also, the findings suggest that the ERC-induced vasorelaxation is closely related to the hypotensive action of the agent.

Evaluation of Chest Compression Depth during Nine Minutes of Hands-Only Cardiopulmonary Resuscitation Performed by a Lone Rescuer and its Effect by Age Group: A Pilot Simulation Study Using a Manikin

Objective

There have been few studies on the use of long-standing hands-only cardiopulmonary resuscitation (CPR) by a lone rescuer. This study aimed to evaluate the long-standing (nine minutes) hands-only CPR by a lone rescuer, and the change of chest compression depth over time. The effect of age of rescuer on chest compression depth was also studied.

Methods

From a total of 404 adult lay-persons who participated in CPR training, 91 subjects were enrolled in the simulation trial of nine minutes of hands-only CPR using a manikin with a Skill-Reporter™. The quality of the chest compression over time and the effects of rescuer age were analysed.

Results

Of the 91 participants, 74 (81%) fully completed the nine minutes of CPR. No significant differences of incomplete CPR rate between each age group were observed. No significant differences in the degree of reduction in effective chest compressions were observed based on the time course among the different age groups. The total number of compressions decreased abruptly from the six-minute time point onwards (five minutes vs. six minutes, p=0.038).

Conclusions

Most trained lay-persons could complete the 9 minutes of hands-only CPR. The rate of chest compression shows a significant decrease after 6 minute. We do not find a significant difference in the decrease of adequate chest compressions over time among various age groups in this pilot simulation study.

Infiltrating Foxp3+ regulatory T cells and histopathological features in canine classical and spermatocytic seminomas

In humans, regulatory T (T reg) cells are known to play a critical role in both the regulation of immune homoeostasis and the progression of cancer. However, there is little information about the identification, characterization and the function of T reg cells in canine tumours. We identified T reg cells in 28 canine seminoma samples using a Forkhead box P3 (Foxp3) antibody and investigated the relationship between T reg cell infiltration and histopathological features of classical and spermatocytic seminomas (SE and SS, respectively). The Foxp3 protein showed nuclear immunostaining in infiltrating lymphocytes, and Foxp3+ cells were diffused or focally distributed in seminoma tissues. Foxp3+ cells were frequently present in the SS histotype, in seminomas that showed no evidence of tumour cell invasion into the vessels and in seminomas showing a diffuse growth pattern with three cell types. Neither the SE/SS histotype nor the histopathological features of the tumour correlated with Foxp3+ cell counts. These results indicate that Foxp3+ T reg cells may be associated with a less malignant histological phenotype or may not play a critical role in the immune response of canine seminomas. Moreover, Foxp3+ T reg cells may be associated with SS seminoma, but further studies, involving a larger number of samples, are required to better understand whether these cells play a critical role in the immune response in canine seminomas. This is the first report to demonstrate the characteristics of T reg cell infiltration in canine seminoma.

Feasibility of electroflotation to separate solids and liquid in an activated sludge process

In this study, electroflotation (EF) has been applied as a secondary clarification in the activated sludge process to improve the efficiency of the solids-liquid separation, which is essential in maintaining effluent quality. The effects of sludge settleability were examined through a series of batch and semi-continuous experiments. The results of the batch experiments revealed that thickening efficiencies using EF were 2.6 to 9.2 times higher than those with gravity settling (GS). In addition, clarification efficiencies were not significantly influenced by sludge settling properties, as compared with GS as a control. In the semi-continuous EF experiments, the concentrations of solids in the float layer were maintained above 10 g L(-1) during flotation, regardless of variations in sludge settleability. Furthermore, the volumetric gas proportion in the float layer increased as the gas to solids (G/S) ratio rose. This allowed the float layer to be more stably suspended against gravity at the top of the reactor. Based on the results obtained from these batch and semi-continuous experiments, an anoxic/oxic (AO) reactor combined with EF clarifier remained in successful continuous operation for four months. In comparison with conventional AO processes using a GS clarifier, enhanced clarification and thickening efficiencies were achieved through the EF-AO system. In addition, higher mixed liquor suspended solids concentrations (averaging 5300 mg L(-1)) in the bioreactor (EF-AO) were maintained via the return of highly concentrated sludge (averaging 16,400 mg L(-1)) from the EF clarifier. These findings suggest that EF could be a promising and effective alternative for the solids-liquid separation of poorly settling sludge.

Semen characteristics of genetically identical male cats cloned via somatic cell nucleus transfer

We investigated the sperm characteristics of four cloned male cats (Felis catus) to assess their reproductive potential. Fresh and frozen-thawed sperm were assessed for motility, viability, and morphology, and their functional competence was evaluated by in vitro fertilization (IVF) of domestic cat oocytes. All fresh semen characteristics varied among cats and collection times. Sperm concentration (x 10(6)/mL) of Cat A (512+/-140, range 368 to 685) was significantly higher, whereas that of Cat C (335+/-92, range 274 to 469) was significantly lower than that of Cloned B (459+/-159, range 336 to 510) and control cats (680+/-452, range 360 to 479). After thawing, motility and progressive motility of sperm from Cat B were significantly lower than that of the other cloned and control cats. The curvilinear, straight line, and average path velocities of sperm from Cat B were significantly higher, whereas the straightness was lower, than that of the other cloned and control cats. Frozen sperm from Cats A, B, and C successfully fertilized oocytes (cleavage=74.4%, 71.4%, and 86.2%, respectively) and produced embryos that developed to the blastocyst stage after IVF/In vitro culture (IVC) (34.4%, 26.7%, and 48.0%) at frequencies similar to the cleavage rate (82.0%) and blastocyst rate (43.9%) obtained with sperm from the control male. In conclusion, seminal characteristics of cloned male cats did not differ markedly from those of our noncloned, control male cats.

Seroprevalence of canine dirofilariosis in South Korea

Eight-hundred and forty eight dogs (480 females and 368 males) not on chemoprophylaxis were examined for Dirofilaria immitis infection from 2001 to 2002. Three-hundred and thirty nine (40.0%) of 848 samples tested with antigen detecting ELISA kits showed positive reaction for D. immitis antigen. More male (43.5%) than female (37.3%) dogs were affected in this study, although there was no significant difference between both groups. Chi2 analysis showed that female and male dogs of shoreline areas had higher significant prevalence than other areas (P<0.001), respectively. The mean overall positive rates of heartworm infection were 10.4% in dogs <2-year-old group, 46.5% in 2-4-year-old group, 48.4% in 4-6-year-old group and 50.3% in >6-year-old group. The older the age, the higher the prevalence of D. immitis infection in this study. Chi2 analysis revealed a significant higher prevalence in 4-6-year-old group (100%) of shoreline areas and in 2-4-old-year group (51.2%) of urban areas (Chungnam province), respectively (P<0.001), and also revealed that the over 6-year-old group (50.3%) in mean overall prevalence had the significant higher prevalence than other age group (P<0.001). In climate comparison, our data showed that shoreline areas (69.5%) had the significant higher prevalence than urban areas and mountain areas (P<0.001). This survey confirms that the prevalence of canine heartworm infection increases, and also that the prevalence in shoreline areas is higher than in other areas in South Korea.

Role of rho-kinase activity in angiotensin II-induced contraction of rabbit clitoral cavernosum smooth muscle

Isometric tension measurement using a selective Rho-kinase inhibitor (+)- (R)-trans4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide (Y-27632) and a selective myosin light chain kinase (MLCK) inhibitor 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML7) were used in rabbit clitoral cavernosum smooth muscle (CSM). N(G)-nitro-L-arginine methyl ester (L-NAME) was used to evaluate the relationship between NO release and Rho-kinase. Y-27632 significantly attenuated contractions induced by ANG II, dose-dependently. However, ML7 did not affect the contractile response to ANG II except in the high concentrations of ML7. Y-27632 inhibited contraction with phenylephrine (PhE), but ML7 did not inhibit contraction with PhE. Nitric oxide synthase inhibitor (NAME) did not affect the Y-27632-induced relaxation in the pre-contracted strip with PhE. The present study demonstrates that G-protein-coupled increase in myofilament Ca(2+) sensitivity mediated through the RhoA/Rho-kinase signal pathway is involved in the control by ANG II of the clitoral CSM tone. RhoA/Rho-kinase pathway acts in the ANG II-induced contraction independently of the NO pathway.

High glucose dialysis solutions increase synthesis of vascular endothelial growth factors by peritoneal vascular endothelial cells

OBJECTIVE

Increased peritoneal vasculature has been reported in long-term peritoneal dialysis (PD), and vascular endothelial growth factors (VEGFs) have been found in dialysate. High concentrations of glucose or lactate, glucose degradation products (GDPs), and low pH of dialysis solutions are all possible factors in increased peritoneal VEGF synthesis. In this study, we investigated the effects of high glucose dialysis solutions on VEGF synthesis by peritoneal vascular endothelial cells (PVECs).

METHODS

The PVECs were isolated from rat omentum and were incubated for 4 hours in three different culture media [M199 media (control), conventional dialysis solutions containing 4.25% glucose diluted with an equal volume of M199 media (HGD), and M199 media containing 118 mmol/L mannitol as an osmolar control (mannitol)]. Levels of VEGF protein in the culture supernatant were measured by ELISA, and mRNA expression was determined by Northern blot analysis. Data are presented as percent of control.

RESULTS

After incubation for 4 hours, the number of cells did not differ between the 3 groups. Levels of VEGF in culture supernatant were significantly higher in the HGD group (124% +/- 19%, p = 0.006) as compared with the control and mannitol (85% +/- 10%) groups. The mRNA expression of VEGF appeared to be higher in the HGD group (128% +/- 49%) than in the control and mannitol (94% +/- 18%) groups.

CONCLUSION

High glucose dialysis solutions increased VEGF synthesis by PVECs. The relationship between VEGF synthesis by PVECs and neovascularization of the peritoneum observed in long-term peritoneal dialysis patients has to be studied further.

Comparison of effects of angiotensin peptides in the regulation of clitoral cavernosum smooth muscle tone

The isometric tension measurement and in vitro autoradiography were used in clitoral cavernosum smooth muscle (CSM). Angiotensin ANG III, ANG IV, ANG II and ANG I induced contractions in clitoral CSM strips. ANG III and ANG I- induced contraction was five times less active than ANG II, whereas ANG IV-induced contraction was 1181-fold less potent than ANG II. Contractile responses to ANG III, ANG IV, ANG II and ANG I were significantly inhibited by type 1 ANG II (AT 1) receptor antagonist Dup 753 but not by type 2 ANG II (AT2) receptor antagonist PD 123,319. Pre-treatment with Nomega-nitro-L-arginine methyl ester, nitric oxide (NO) synthase inhibitor accentuated force of contraction induced by ANG III, ANG IV and ANG II. Amastatin, an aminopeptidase inhibitor enhanced ANG III- and ANG IV-induced contractions. Specific binding sites for 125I-ANG II were found in the clitoral CSM. Specific binding of 125I-ANG II was displaced by unlabeled ANG peptides. This study suggests that the contractile responses to all four peptides of the ANG family are mediated via AT1 receptors but not AT2 receptors. Further, the rank order of potency of contraction was as follows, ANG II> ANG I>ANG III>ANG IV. It is also suggested that peptides of the ANG family have a cross-talk with the NO system and aminopeptidase is involved in the modulation of the tone of clitoral CSM by ANG III and ANG IV.

New farnesylhydroquinone glycosides from the gorgonian Euplexaura anastomosans

Euplexides F (3) and G (4), novel farnesylhydroquinone glycosides, have been isolated as minor constituents of the gorgonian Euplexaura anastomosans. The structures of these compounds have been determined by combined spectroscopic methods. These compounds exhibited moderate cytotoxicity and inhibitory activity against PLA2.

Nociceptin/orphanin FQ increases ANP secretion in neonatal cardiac myocytes

Nociceptin (N/OFQ) is a novel heptadecapeptide with an amino acid sequence similar to that of endogenous opioid peptide dynorphin A. Dynorphin have been reported to increase the secretion of atrial natriuretic peptide (ANP) via selective activation of kappa-opioid receptor in cultured atrial cardiocytes. The present study was designed to investigate the direct effect of N/OFQ on the ANP secretion in cultured neonatal rat cardiac myocytes via N/OFQ receptor (NOP) activation. The secretion of ANP from cultured neonatal cardiac myocytes was increased in terms of incubation time. N/OFQ, at a dose of 0.3, 1, 3, and 10 microM, caused increases in ANP secretion in a dose-dependent manner. The N/OFQ-induced ANP secretion was completely antagonized by antagonists of NOP, 1 microM each of [Phe1 (CH2-NH) Gly2] nociceptin (1-13)-NH2 ([FG]N/OFQ(1-13)NH2) or naloxone benzoylhydrazone. In contrast, naloxone (1 microM), the non-selective opioid receptor antagonist, did not alter ANP response to N/OFQ. N/OFQ at 3 microM inhibited basal and forskolin-stimulated cAMP production, which was partially antagonized with the pretreatment of [FG]N/OFQ(1-13)NH2. An increase in ANP secretion by N/OFQ was also partially blocked by the pretreatment of forskolin. Homologous competition studies in neonatal cardiomyocyte membranes revealed the presence of two distinct sites. The high affinity site (10.9 +/- 1.6 nM) was far less abundant than the low affinity site. Therefore, these results suggest that N/OFQ causes an increase in ANP secretion in cultured neonatal cardiac myocytes by decreasing cAMP through its binding sites.

C-type natriuretic peptide system in rabbit colon

C-type natriuretic peptide (CNP) is mainly distributed in the brain and vascular endothelium and is considered to act as a local regulator in many tissues. The present study was aimed to determine the presence of CNP system and its biological function in rabbit colon. The serial dilution curves of tissue extracts were parallel to the standard curve of CNP-22. With gel permeation chromatography and reverse-phase HPLC, the major immunoreactive peak of CNP was observed at the same elution time corresponding to the synthetic CNP-53. The concentration of CNP in the mucosal layer of colon was 212.49 +/- 30.44 pg/g tissue wet weight (n = 7), which was significantly higher than that in the muscular layer. The presence of CNP mRNA was also detected by RT-PCR and Southern blot analysis. Production of cGMP by the activation of particulate guanylyl cyclase stimulated by BNP and CNP was higher in membranes obtained from the muscular layer than from mucosal layer. More cGMP was produced by CNP than by ANP. Both natriuretic peptide receptor-A and -B mRNAs were detected by RT-PCR and specific binding sites to 125I-[Tyr(0)]-CNP-22 were mainly localized to the muscular layer. Synthetic CNP inhibited basal tension, frequency and amplitude of basal motility of taenia coli of the right colon. This study showing the presence of CNP system and its biological function in colon suggests that endogenous CNP synthesized in the mucosal layer may have a paracrine function as a local regulator of colonic motility.

Attenuation of inhibitory effect of CNP on the secretion of ANP from hypertrophied atria

It has been shown that atrial natriuretic peptide (ANP) influences proliferation of cardiac cells. To define the possible role of C-type natriuretic peptide (CNP) in cardiac hypertrophy, the influence of CNP on the secretion of ANP was studied with the use of perfused nonbeating atria from monocrotaline-treated rats. Increases in atrial volume caused proportional increases in ANP secretion that were markedly suppressed by CNP (10(-6) M) in nonhypertrophied left atria and control right atria but not in hypertrophied right atria. However, increases in atrial volume and mechanically stimulated extracellular fluid (ECF) translocation by CNP were similar to those in the control group. Therefore, the secretion of ANP in terms of ECF translocation was decreased by CNP in nonhypertrophied left and control right atria but not in hypertrophied atria. However, the inhibitory effect of 8-bromo-cGMP on the secretion of ANP was observed in both atria. The cGMP productions from perfused hypertrophied atria and their membranes exposed to CNP were significantly lower than those from nonhypertrophied atria. No significant difference in natriuretic peptide receptor-B transcript was found. Therefore, attenuation of the inhibitory effect of CNP on the ANP secretion in hypertrophied atria may be due to lack of cGMP production. The results showing the relief of CNP-induced negative inhibition of ANP secretion by atrial hypertrophy suggest that CNP may be a contributing factor to delay the development of cardiac hypertrophy.

Intracellular BMP signaling regulation in vertebrates: pathway or network?

Bone morphogenetic proteins (BMPs), members of the TGF-beta superfamily of secreted signaling molecules, have important functions in many biological contexts. They bind to specific serine/threonine kinase receptors, which transduce the signal to the nucleus through Smad proteins. The question of how BMPs can have such diverse effects while using the same canonical Smad pathway has recently come closer to an answer at the molecular level. Nuclear cofactors have been identified that cooperate with the Smads in regulating specific target genes depending on the cellular context. In addition, the pivotal role BMP signaling plays is underscored by the identification of factors that regulate members of this pathway at the cell surface, in the cytoplasm, and in the nucleus. Many of these factors are BMP-inducible and inhibit the BMP pathway, thus establishing negative feedback loops. Members of the BMP-Smad pathway can also physically interact with components of other signaling pathways to establish crosstalk. Finally, there is accumulating evidence that an alternative pathway involving MAP kinases can transduce BMP signals. The evidence and implications of these findings are discussed with an emphasis on early embryonic development of Xenopus and vertebrates.

Accentuation of ANP secretion to endothelin-1 in hypertrophied atria

To investigate modulation of ANP secretion by atrial hypertrophy, the secretion of ANP in response to stretch and endothelin-1 was studied using isolated perfused quiescent atria from rats treated with monocrotaline (MCT). Male Sprague-Dawley rats were given a single subcutaneous injection of 50 mg/kg MCT or saline and were sacrificed at 6 weeks. Rats with right heart hypertrophy showed an increase in ANP mRNA and decrease in tissue concentration of ANP in hypertrophied atria and a marked increase in plasma concentration of ANP. In isolated perfused hypertrophied right atria from MCT rats, changes in atrial volume induced by increased atrial pressure caused proportional increases in mechanically stimulated extracellular fluid (ECF) translocation and stretch-activated ANP secretion. Changes in atrial volume and mechanically stimulated ECF translocation in hypertrophied right atria were not different from those in control right atria. The stretch-activated ANP secretion was suppressed without significant difference in basal ANP secretion, as compared to control right atria. Therefore, the stretch-activated ANP secretion from hypertrophied right atria into the atrial lumen in relation to the ECF translocation (ANP concentration in the interstitium) was lower than that from control atria. A positive correlation between the stretch-activated ANP secretion in relation to the ECF translocation and tissue ANP content was found in control atria but not in hypertrophied atria. Endothelin-1 caused increases in stretch-activated ANP secretion in a dose-dependent manner, which were accentuated in hypertrophied right atria. Therefore, we suggest that atrial hypertrophy causes an attenuated response to stretch and accentuated response to endothelin-1 of ANP secretion.

C-type natriuretic peptide system in rabbit oviduct

C-type natriuretic peptide (CNP), a third member of the natriuretic peptide family, is known to be distributed mainly in brain and vascular endothelium and is considered to act as a local regulator in many tissues. The purpose of this study was to determine the presence of CNP system and its biological function in rabbit oviduct. The serial dilution curve of tissue extracts was parallel to the standard curve of CNP((1-22)) and a major peak of molecular profile of tissue extracts by HPLC was CNP((1-53)). mRNA of CNP which was the same size as positive control was also detected by Southern blot analysis. CNP increased the production of 3',5'-cyclic guanosine monophosphate (cGMP) in the purified membrane of oviduct, which was more in membranes derived from the isthmic portion than in the ampullar portion. The presence of mRNAs of natriuretic peptide receptor-A (NPR-A) and NPR-B was demonstrated by RT-PCR. Synthetic CNP((1-22)) inhibited both frequency and amplitude of basal motility of oviduct in a dose-dependent manner. The inhibitory effect of CNP on the basal motility was more potent in the isthmic portion than in the ampullar portion. These results demonstrate the presence of CNP system in the oviduct and regional differences in motility inhibition by CNP between isthmic and ampullar portions. Therefore, these findings suggest the possible existence of a CNP system that may exert a local regulator of basal motility, either alone or in concert with other hormones.

Data mining approach to policy analysis in a health insurance domain

This study examined the characteristics of the knowledge discovery and data mining algorithms to demonstrate how they can be used to predict health outcomes and provide policy information for hypertension management using the Korea Medical Insurance Corporation database. Specifically, this study validated the predictive power of data mining algorithms by comparing the performance of logistic regression and two decision tree algorithms, CHIAD (Chi-squared Automatic Interaction Detection) and C5.0 (a variant of C4.5) using the test set of 4588 beneficiaries and the training set of 13,689 beneficiaries. Contrary to the previous study, the CHIAD algorithm performed better than the logistic regression in predicting hypertension, and C5.0 had the lowest predictive power. In addition, the CHIAD algorithm and the association rule also provided the segment-specific information for the risk factors and target group that may be used in a policy analysis for hypertension management.

New triterpenoid saponins from the sponge Erylus nobilis

Erylosides G--J (1--4), four new triterpenoid saponins, were isolated from the sponge Erylus nobilis collected from Jaeju Island, Korea. On the basis of the results of combined chemical and spectral analyses, the structures of the aglycones were determined to be lanostane-based, modified penasterols. The oligosaccharide portions were composed of one unit each of L-arabinose, D-galactose, and 2-N-acetyl-D-glucosamine (1 and 3) or two units of L-arabinose and one unit of 2-N-acetyl-D-glucosamine (2 and 4). These compounds exhibited moderate cytotoxicty against a human leukemia cell line.

New lactone-containing metabolites from a marine-derived bacterium of the genus Streptomyces

Six novel metabolites containing a lactone moiety as a common structural feature, along with the previously described (-)-blastmycinolactol, have been isolated from the cultivation broth of a bacterium of the genus Streptomyces isolated from marine sediment. On the basis of the results of combined spectroscopic analysis, the structures of the new compounds have been determined as butenolides and 3-hydroxy-gamma-butyrolactones.

Detection of canine distemper virus (CDV) through one step RT-PCR combined with nested PCR

A one step reverse transcription PCR (RT-PCR) combined nested PCR was set up to increase efficiency in the diagnosis of canine distemper virus (CDV) infection after developement of nested PCR. Two PCR primer sets were designed based on the sequence of nucleocapsid gene of CDV Onderstepoort strain. One-step RT-PCR with the outer primer pair was revealed to detect 10(2) PFU/ml. The sensitivity was increased hundredfold using the one-step RT-PCR combined with the nested PCR. Specificity of the PCR was also confirmed using other related canine virus and peripheral blood mononuclear cells (PBMC) and body secretes of healthy dogs. Of the 51 blood samples from dogs clinically suspected of CD, 45 samples were revealed as positive by one-step RT-PCR combined with nested PCR. However, only 15 samples were identified as positive with a single one step RT-PCR. Therefore approximately 60% increase in the efficiency of the diagnosis was observed by the combined method. These results suggested that one step RT-PCR combined with nested PCR could be a sensitive, specific, and practical method for diagnosis of CDV infection.

New xenicane diterpenoids from the gorgonian Acalycigorgia inermis

Eight diterpenes and norditerpenes including five new xenicane metabolites (4--8) have been isolated from the gorgonian Acalycigorgia inermis. The structures of these compounds have been determined by combined spectroscopic analysis. The new compounds exhibited significant cytotoxicity against a human leukemia cell-line.

Homologues of Twisted gastrulation are extracellular cofactors in antagonism of BMP signalling

Twisted gastrulation (TSG) is involved in specifying the dorsal-most cell fate in Drosophila embryos, but its mechanism of action is poorly understood. TSG has been proposed to modify the action of Short gastrulation (SOG), thereby increasing signalling by the bone morphogenetic protein (BMP) Decapentaplegic. SOG, an inhibitor of BMP signalling, is in turn inactivated by the protease Tolloid. Here we identify Tsg gene products from human, mouse, Xenopus, zebrafish and chick. Expression patterns in mouse and Xenopus embryos are consistent with in vivo interactions between Tsg, BMPs and the vertebrate SOG orthologue, chordin. We show that Tsg binds both the vertebrate Decapentaplegic orthologue BMP4 and chordin, and that these interactions have multiple effects. Tsg increases chordin's binding of BMP4, potentiates chordin's ability to induce secondary axes in Xenopus embryos, and enhances chordin cleavage by vertebrate tolloid-related proteases at a site poorly used in Tsg's absence; also, the presence of Tsg enhances the secondary axis-inducing activity of two products of chordin cleavage. We conclude that Tsg acts as a cofactor in chordin's antagonism of BMP signalling.

Distinct roles for L- and T-type Ca(2+) channels in regulation of atrial ANP release

Atrial secretion of atrial natriuretic peptide (ANP) has been shown to be regulated by atrial workload. Although modulating factors for the secretion of ANP have been reported, the role for intracellular Ca(2+) on the secretion of ANP has been controversial. The purpose of the present study was to define roles for L- and T-type Ca(2+) channels in the regulation of ANP secretion in perfused beating rabbit atria. BAY K 8644 (BAY K) increased atrial stroke volume and pulse pressure. BAY K suppressed ANP secretion and ANP concentration in terms of extracellular fluid (ECF) translocation concomitantly with an increase in atrial dynamics. BAY K shifted the relationship between ANP secretion and ECF translocation downward and rightward. These results indicate that BAY K inhibits myocytic release of ANP. In the continuous presence of BAY K, diltiazem reversed the effects of BAY K. Diltiazem alone increased ANP secretion and ANP concentration along with a decrease in atrial dynamics. Diltiazem shifted relationships between ANP secretion and atrial stroke volume or ECF translocation leftward. The T-type Ca(2+) channel inhibitor mibefradil decreased atrial dynamics. Mibefradil inhibited ANP secretion and ANP concentration in contrast with the L-type Ca(2+) channel inhibitor. These results suggest that activation of L- and T-type Ca(2+) channels elicits opposite effects on atrial myocytic release of ANP.

Cyclosporine impairs the guanylyl cyclase activity of the natriuretic peptide receptor in the glomerulus

In order to elucidate the involvement of the atrial natriuretic peptide (ANP) and its receptor (natriuretic peptide receptor; NPR) system in cyclosporine-induced nephrotoxicity, we investigated the cyclosporine A (CsA)-induced changes in characteristics of the NPR/guanylyl cyclase system in the glomerulus and inner medulla of the rat kidney. CsA was administered intramuscularly to rats for 2 weeks (CsA group). Particulate guanylyl cyclase activity was measured in glomerular and inner medullary membranes. For receptor characteristics, quantitative in vitro receptor autoradiography was performed. The guanylyl cyclase activity in the glomerulus from the CsA group was attenuated compared with that from the control. However, the activity in the inner medulla was not affected by CsA treatment. Direct application of CsA to normal glomerular membrane completely abolished the ANP-induced guanylyl cyclase activation. Binding studies, using(125)I-ANP, revealed that B(max)was decreased in the CsA group, while K(d)was not affected in the glomerulus. However, in the inner medulla, neither B(max)nor K(d)was affected by CsA treatment. CsA did not displace the(125)I-ANP bindings to NPRs in the normal rat kidney. Local tissue ANP as well as plasma ANP concentration in both groups was not significantly different. These results indicate that CsA impairs the guanylyl cyclase activity mainly in the glomerulus by the decrease in NPR population and/or by direct inhibition, suggesting that the ANP/NPR system might be involved in CsA-induced nephrotoxicity.

Natriuretic peptide system in the rat lacrimal gland

The presence and characteristics of the natriuretic peptides and their receptors in the rat exorbital lacrimal gland were investigated. Serial dilution curves of the gland extracts were parallel to the standard curves of synthetic atrial natriuretic peptide (ANP) or C-type natriuretic peptide (CNP). Immunoreactive ANP or CNP in the gland extracts co-eluted with authentic ANP or CNP, and their contents were 4.95 +/- 0.60 and 2.87 +/- 0.53 pg mg(-1)protein (quadruplicate), respectively. By immunohistochemistry, strong immunoreactivities of ANP and CNP were co-localized in the tubules and excretory ducts of the gland, and moderate immunoreactivities were found in the myoepithelial cells and acini. Productions of guanosine 3',5'-cyclic monophosphate by particulate guanylyl cyclase in the gland membranes were stimulated by natriuretic peptides in a dose-dependent manner, and that by CNP was larger than by ANP. Messenger RNAs for ANP, CNP and their receptors were detected by reverse transcription-polymerase chain reaction. These results indicate that natriuretic peptides and their specific receptors are found in the rat lacrimal gland. Therefore, it is suggested that natriuretic peptide system may play physiological roles in the rat lacrimal gland.

Effects of pituitary adenylate cyclase activating polypeptide27 on cyclic AMP efflux and atrial dynamics in perfused beating atria

Although pituitary adenylate cyclase activating polypeptide (PACAP) has been shown to increase cardiac force of contraction and to change the heart rate, the effect of PACAP on cyclic (c) AMP production in the atrium still has to be defined. In the present experiments, a simple protocol was developed for the evaluation of cAMP production in real-time base in the perfused beating left atria. The PACAP27-induced cAMP efflux in the atrial perfusate reflected changes in the production of cAMP in the atrial tissue. cAMP efflux was measured as an indicator of cAMP production in beating perfused rabbit atria. PACAP27 increased cAMP production in a dose- and time-dependent manner with a minor effect on atrial dynamics. These results suggest that PACAP27 has other roles besides control of force of contraction through cAMP production in the atrium.

Xlim-1 and LIM domain binding protein 1 cooperate with various transcription factors in the regulation of the goosecoid promoter

The homeobox genes Xlim-1 and goosecoid (gsc) are coexpressed in the Spemann organizer and later in the prechordal plate that acts as head organizer. Based on our previous finding that gsc is a possible target gene for Xlim-1, we studied the regulation of gsc transcription by Xlim-1 and other regulatory genes expressed at gastrula stages, by using gsc-luciferase reporter constructs injected into animal explants. A 492-bp upstream region of the gsc promoter responds to Xlim-1/3m, an activated form of Xlim-1, and to a combination of wild-type Xlim-1 and Ldb1, a LIM domain binding protein, supporting the view that gsc is a direct target of Xlim-1. Footprint and electrophoretic mobility shift assays with GST-homeodomain fusion proteins and embryo extracts overexpressing FLAG-tagged full-length proteins showed that the Xlim-1 homeodomain or Xlim-1/Ldb1 complex recognize several TAATXY core elements in the 492-bp upstream region, where XY is TA, TG, CA, or GG. Some of these elements are also bound by the ventral factor PV.1, whereas a TAATCT element did not bind Xlim-1 or PV.1 but did bind the anterior factors Otx2 and Gsc. These proteins modulate the activity of the gsc reporter in animal caps: Otx2 activates the reporter synergistically with Xlim-1 plus Ldb1, whereas Gsc and PV.1 strongly repress reporter activity. We show further, using animal cap assays, that the endogenous gsc gene was synergistically activated by Xlim-1, Ldb1, and Otx2 and that the endogenous otx2 gene was activated by Xlim-1/3m, and this activation was suppressed by the posterior factor Xbra. Based on these data, we propose a model for gene interactions in the specification of dorsoventral and anteroposterior differences in the mesoderm during gastrulation.

Coexistence of C-type natriuretic peptide and atrial natriuretic peptide systems in the bovine cornea

PURPOSE

To determine whether the cornea synthesizes natriuretic peptides and contains their receptors.

METHODS

The synthesis of the natriuretic peptides, C-type natriuretic peptide (CNP) and atrial natriuretic peptide (ANP), in the bovine cornea was determined by high-performance liquid chromatography (HPLC) with radioimmunoassay and Southern blot analysis. The presence of natriuretic peptide receptor (NPR)-A and -B and their localizations were measured by reverse transcription-polymerase chain reaction (RT-PCR), in vitro autoradiography, and the activation of particulate guanylyl cyclase by natriuretic peptides in the corneal membrane.

RESULTS

The serial dilution curves of corneal extracts were parallel to the standard curves of CNP and ANP. With reversed-phase HPLC, a major immunoreactive peak of CNP or ANP was observed at the elution time corresponding with synthetic CNP(1-53) or atriopeptin III (APIII), respectively. The presence of mRNAs of CNP and ANP was also detected in the cornea by RT-PCR and/or Southern blot analysis. Production of 3',5'-cyclic guanosine monophosphate (cGMP) by the activation of particulate guanylyl cyclase in the corneal membrane was stimulated by ANP, BNP, and CNP. More cGMP was produced by CNP than by the other natriuretic peptides. Specific 125I-[Tyr0]-CNP(1-22) binding sites were localized in the endothelial cell layer of cornea. The apparent dissociation constant (Kd) value of the cornea was 3.06 +/- 0.73 nM and the maximum binding capacity was 3.40 +/- 0.63 femtomoles/mm2. Both NPR-A and NPR-B mRNAs were detected by RT-PCR.

CONCLUSIONS

The cornea synthesizes CNP and ANP and contains their receptors. These results suggest that the CNP and ANP systems coexist in the bovine cornea.

Renin angiotensin system of rabbit clitoral cavernosum: interaction with nitric oxide

PURPOSE

Angiotensin (ANG) II has been known to be a potent modulator for the maintenance of smooth muscle tone of the penile cavernosum. However, its role in clitoral cavernosum is unknown. The clitoris is the homologue of the penis arising from the embryological genital tubercle. We investigated the presence of ANG II receptors, the function of ANG II, and its interaction with nitric oxide (NO) in rabbit clitoral cavernosum.

MATERIALS AND METHODS

The isometric tension was measured in the strips of clitoral cavernosum. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to evaluate expression of AT1a and AT1b ANG II receptor subtype mRNAs. In vitro autoradiography was used to localize ANG II receptors in the clitoral cavernosum.

RESULTS

The clitoral cavernosum was contracted dose-dependently by the addition of ANG II. Dup 753 (ANG II type 1 receptor antagonist) inhibited significantly ANG II induced contraction. PD 123,319 (ANG II type 2 receptor antagonist) did not affect the ANG II response. Pretreatment with NG-nitro-L-arginine methyl ester (NO synthase inhibitor) accentuated contractions induced by ANG II. Specific binding sites for 125I-ANG II were found in the clitoral cavernosum. The dissociation constant (Kd) was 0.58 + or - 0.05 nM. Specific binding of 125I-ANG II was displaced by Dup 753 (10-5 M) but not by PD 123,319 (10-5 M). The inhibitory constant (Ki) for Dup 753 was 23. 4 + or - 9.73 nM and mRNAs for AT1a and AT1b receptor subtypes were detected by RT-PCR.

CONCLUSION

The present study shows that ANG II is involved in the regulation of clitoral cavernosum smooth muscle tone via ANG II receptor subtype AT1, and that ANG II has cross-talk with NO.

Is chordin a long-range- or short-range-acting factor? Roles for BMP1-related metalloproteases in chordin and BMP4 autofeedback loop regulation

Diffusible morphogen models have been used widely to explain regional specification of tissues and body axes during animal development. The three-signal model for patterning the dorsal-ventral axis of the amphibian embryo proposes, in part, that a factor(s) secreted from Spemann's organizer is responsible for converting lateral marginal zone into more dorsal cell fates. We examine the possibility that chordin, a secreted inhibitor of bone morphogenetic protein (BMP) signaling and candidate "dorsalizing signal," is a long-range-acting factor. We show that chordin can, when overexpressed, act directly over distances of at least 450 microm in the early Xenopus embryo to create a gradient of BMP signaling. However, since lower levels of chordin can still induce secondary axes and these amounts of chordin act only locally to inhibit a BMP target gene, we suggest that chordin likely acts as a short-range signal in vivo. Furthermore, BMP1, a secreted metalloprotease that cleaves chordin protein in vitro, inhibits chordin's axis-inducing effects, suggesting that BMP1 functions to negatively regulate chordin's action in vivo. A dominant-negative mutant BMP1 blocks the in vitro cleavage of chordin protein by wild-type BMP1 and induces secondary axes when injected ventrally. We argue that BMP1 and Xolloid are probably functionally redundant metalloproteases and may have two roles in the early Xenopus embryo. One role may be to inhibit the action of low-level chordin protein expressed throughout the entire embryo and a possible second role may be to inhibit activation of a juxtacrine cell relay, thereby confining chordin's action to the organizer region preventing chordin from functioning as a long-range-acting factor.

New triterpenoid saponins from the sponge Melophlus isis

Four new triterpenoid saponins were isolated, along with two known 30-norlanostane-type saponins- sarasinosides A(1) (1) and A(3) (2)-from the sponge Melophlus isis collected from Guam. The structures of these new compounds (3-6) proved to be 30-norlanosta-8(14),24-dien-23-ones bearing two hydroxyl groups or the corresponding methoxy groups at the 9alpha,15alpha- and 9alpha, 15beta-positions and the pentasaccharide portion identical with those of 1 and 2 at the 3beta position, by spectral, chemical, and GC analyses.

Immunohistochemical localization of C-type natriuretic peptide in the rat submaxillary salivary gland

To define the localization and characteristics of C-type natriuretic peptide (CNP) in the rat submaxillary gland, immunohistochemistry and gel permeation-high-performance liquid chromatography were used. Immunoreactive (IR)-CNP was localized in cells of the granular convoluted tubule, striated duct and endothelial cells of the capillary, where atrial natriuretic peptide (ANP) was colocalized in consecutive sections, but not in acini. Gland extracts co-eluted with synthetic CNP and its content was 60.3+/-4.9 pg/mg protein (n=4). Molecular profiles of immunoreactive material showed two peaks corresponding to synthetic CNP((1-53)) and CNP((1-22)). These results indicate that CNP is colocalized with ANP in the duct and endothelial cells of the rat submaxillary gland. Therefore, CNP may have a physiological role in the submaxillary gland by interacting with ANP and/or other biologically active substances in the ducts and granular convoluted tubule cells.

Localization of receptors for natriuretic peptide and endothelin in the duct of the epididymis of the freshwater turtle

The presence of receptor subtypes for natriuretic peptides (NPs) and endothelin (ET) in the epididymis of the freshwater turtle, Amyda japonica, was examined by quantitative in vitro autoradiography using iodinated mammalian-type atrial NP ((125)I-ANP((1-28))), phylogenically conserved C-type NP ((125)I-[Tyr(0)]-CNP((1-22))), and ET-1 ((125)I-ET-1) as radiolabeled ligands. To characterize NP receptor (NPR) subtypes, we also performed an activation of particulate guanylyl cyclase (GC) in membranes of the epididymis by NPs. Specific (125)I-ANP((1-28)) and (125)I-[Tyr(0)]-CNP((1-22)) bindings were localized in surrounding smooth muscle cell layer of the duct of the epididymis with an apparent dissociation constant (K(d)) of 0.84+/-0.15 and 1.74+/-0.39 nM and a maximal binding capacity (B(max)) of 0.47+/-0.11 and 0.08+/-0.01 fmol/mm(2), respectively. Bindings of (125)I-ANP((1-28)) and (125)I-[Tyr(0)]-CNP((1-22)) to these sites were also displaced by des[Gln(18),Ser(19),Gly(20), Leu(21),Gly(22)]ANF((4-23)), a specific ligand of the NP clearance receptor. Production of 3',5'-cyclic guanosine monophosphate by particulate GC in membranes of the epididymis was stimulated by ANP((1-28)), BNP((1-26)), and CNP((1-22)). Receptor subtypes for ET in the epididymis were characterized by competition with BQ 123 and BQ 788 as specific antagonists for ET receptors, type A (ET(A)) and type B (ET(B)) subtypes, respectively. Specific (125)I-ET-1 bindings were localized in the smooth muscle cell layer of the duct of the epididymis with K(d) and B(max) of 0.21+/-0.03 nM and 0.52+/-0.05 fmol/mm(2), respectively. These specific bindings were potently inhibited in a dose-dependent manner by BQ 123, whereas BQ 788 (10 microM) was not in competing for specific (125)I-ET-1 bindings in this structure. Therefore, these results indicate that specific NP and ET receptors are localized in surrounding smooth muscle cells of the duct of the epididymis of the freshwater turtle. It is also suggested that biological and clearance NPR-like subtypes coexist in these cells, and the predominant ET receptor subtype in this tissue is the ET(A)-like receptor. The localization of specific receptors for NPs and ET in the epididymis may be involved in the control of the transport of sperm in the freshwater turtle.

Diminished adenylate cyclase activity and aquaporin 2 expression in acute renal failure rats

BACKGROUND

The present study was aimed at investigating the changes of aquaporin 2 (AQP2) expression and its underlying mechanisms in ischemic acute renal failure (ARF).

METHODS

ARF was induced by clamping the both renal arteries for 60 minutes in rats. Two or seven days later, AQP2 expression and trafficking were determined in the kidney by Western blot analysis and immunohistochemistry. The activity of adenylate cyclase was also measured.

RESULTS

The urinary flow rates in ARF-2 and ARF-7 day were significantly increased in association with decreases of urine osmolality. While there was decreased expression of AQP2 in the cortex, outer medulla, and inner medulla in ARF, it was most pronounced in the outer medulla. The AQP2 expression was reduced in the apical membrane-enriched fraction as well the subapical vesicle-enriched fraction in ARF; however, the degree was greater in the former than in the latter. Immunohistochemical study also showed a markedly decreased expression of AQP2 in the collecting duct in ARF. cAMP generation in response to arginine vasopressin (AVP) in the kidney was attenuated in ARF, most prominently in the outer medulla. cAMP generation in the outer medulla in response to forskolin was not affected, but sodium fluoride was significantly blunted in ARF.

CONCLUSIONS

The AVP-stimulated adenylate cyclase activity is impaired in ARF, secondary to a defect at the level of the G protein. The expression of AQP2 was reduced as a consequence, which may in part account for urinary concentration defect in ARF.

Dishevelled phosphorylation, subcellular localization and multimerization regulate its role in early embryogenesis

Dishevelled (Dsh) induces a secondary axis and can translocate to the membrane when activated by Frizzleds; however, dominant-negative approaches have not supported a role for Dsh in primary axis formation. We demonstrate that the Dsh protein is post-translationally modified at the dorsal side of the embryo: timing and position of this regulation suggests a role of Dsh in dorsal-ventral patterning in Xenopus. To create functional links between these properties of Dsh we analyzed the influence of endogenous Frizzleds and the Dsh domain dependency for these characteristics. Xenopus Frizzleds phosphorylate and translocate Xdsh to the membrane irrespective of their differential ectopic axes inducing abilities, showing that translocation is insufficient for axis induction. Dsh deletion analysis revealed that axis inducing abilities did not segregate with Xdsh membrane association. The DIX region and a short stretch at the N-terminus of the DEP domain are necessary for axis induction while the DEP region is required for Dsh membrane association and its phosphorylation. In addition, Dsh forms homomeric complexes in embryos suggesting that multimerization is important for its proper function.

Interaction between Wnt and TGF-beta signalling pathways during formation of Spemann's organizer

Members of the Wnt and TGF-beta superfamilies regulate both cell fate and proliferation during development and tissue maintenance. In the early amphibian embryo, the Wnt and TGF-beta superfamily signalling cascades are required for the establishment of a dorsal signalling centre, Spemann's organizer. Intracellular proteins of both pathways, upon activation, translocate to the nucleus to participate in transcription. Here we show that beta-catenin and Lef1/Tcf, which are downstream components of the Wnt signalling cascade, form a complex with Smad4, an essential mediator of signals initiated by members of the TGF-beta growth factor superfamily. In Xenopus, this interaction directly and synergistically affects expression of the twin (Xtwn) gene during formation of the organizer. This is, to our knowledge, the first demonstration of a physical interaction between TGF-beta and Wnt signalling components in vivo.

New xenicane diterpenoids from the gorgonian Acalycigorgia inermis

Acalycixeniolides D-G [corrected] (1-4), four new diterpenoids of the xenicane class, have been isolated from the gorgonian Acalycigorgia inermis. The structures of these compounds have been determined by combined spectroscopic methods. These compounds exhibited cytotoxicity against a human leukemia cell-line.

C-type natriuretic peptide inhibits ANP secretion and atrial dynamics in perfused atria: NPR-B-cGMP signaling

The purpose of the present experiments was to define the role of C-type natriuretic peptide (CNP) in the regulation of atrial secretion of atrial natriuretic peptide (ANP) and atrial stroke volume. Experiments were performed in perfused beating and nonbeating quiescent atria, single atrial myocytes, and atrial membranes. CNP suppressed in a dose-related fashion the increase in atrial stroke volume and ANP secretion induced by atrial pacing. CNP caused a right shift in the positive relationships between changes in the secretion of ANP and atrial stroke volume or translocation of the extracellular fluid (ECF), which indicates the suppression of atrial myocytic release of ANP into the paracellular space. The effects of CNP on the secretion and contraction were mimicked by 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP). CNP increased cGMP production in the perfused atria, and the effects of CNP on the secretion of ANP and atrial dynamics were accentuated by pretreatment with an inhibitor of cGMP phosphodiesterase, zaprinast. An inhibitor of the biological natriuretic peptide receptor (NPR), HS-142-1, attenuated the effects of CNP. The suppression of ANP secretion by CNP and 8-BrcGMP was abolished by a depletion of extracellular Ca(2+) in nonbeating atria. Natriuretic peptides increased cGMP production in atrial membranes with a rank order of potency of CNP > BNP > ANP, and the effect was inhibited by HS-142-1. CNP and 8-BrcGMP increased intracellular Ca(2+) concentration transients in single atrial myocytes, and mRNAs for CNP and NPR-B were expressed in the rabbit atrium. From these results we conclude that atrial ANP release and stroke volume are controlled by CNP via NPR-B-cGMP mediated signaling, which may in turn act via regulation of intracellular Ca(2+).

Modulation of endocardial natriuretic peptide receptors in right ventricular hypertrophy

Natriuretic peptide (NP) receptors (NPRs) located at the endocardial endothelium are suggested to be involved in regulating myocardial contractility. However, the characteristics and modulation of NPRs in relation to cardiac failure are not well defined. This study examined the properties of NPRs in ventricular endocardium using quantitative receptor autoradiography, RT-PCR, Southern blot analysis, and activation of particulate guanylyl cyclase (GC) by NPs. In control rats, specific 125I-labeled rat atrial NP (rANP)(1-28) binding sites were localized in right (RV) and left ventricular (LV) endocardium. Binding affinities of 125I-rANP(1-28) were remarkably higher in RV than LV endocardium. Radioligand binding at these sites was mostly inhibited by des[Gln18,Ser19,Gly20,Leu21, Gly22]ANP(4-23), a specific NP clearance receptor ligand. mRNAs for all three recognized NPRs were detected in endocardial cells by RT-PCR and confirmed by Southern blot analysis. Production of cGMP by particulate GC in endocardial cell membranes was stimulated by NPs with a rank order of potency of C-type NP(1-22) >> brain NP (BNP)(1-26) > ANP(1-28). We also examined the modulation of these NPRs during cardiac hypertrophy induced by monocrotaline (MCT). In MCT-treated rats with pulmonary hypertension, specific (125)I-rANP(1-28) binding to hypertrophied RV endocardium almost disappeared and cGMP production by NPs was significantly decreased. In rats with pulmonary hypertension, plasma levels of ANP and BNP were increased by fivefold compared with controls. The results indicate that there is a differential distribution of NPRs in the cardiac chambers, with the most abundant binding sites in RV endocardium, that NPR-B is the predominant GC-coupled NPR in ventricular endocardium, and that endocardial NPRs are downregulated with ventricular hypertrophy. Downregulation of NPRs may be associated with an increment of endogenous NP production caused by mechanical overload in hypertrophied ventricle.

Involvement of the small GTPases XRhoA and XRnd1 in cell adhesion and head formation in early Xenopus development

The Rho family of small GTPases regulates a variety of cellular functions, including the dynamics of the actin cytoskeleton, cell adhesion, transcription, cell growth and membrane trafficking. We have isolated the first Xenopus homologs of the Rho-like GTPases RhoA and Rnd1 and examined their potential roles in early Xenopus development. We found that Xenopus Rnd1 (XRnd1) is expressed in tissues undergoing extensive morphogenetic changes, such as marginal zone cells involuting through the blastopore, somitogenic mesoderm during somite formation and neural crest cells. XRnd1 also causes a severe loss of cell adhesion in overexpression experiments. These data and the expression pattern suggest that XRnd1 regulates morphogenetic movements by modulating cell adhesion in early embryos. Xenopus RhoA (XRhoA) is a potential XRnd1 antagonist, since overexpression of XRhoA increases cell adhesion in the embryo and reverses the disruption of cell adhesion caused by XRnd1. In addition to the potential roles of XRnd1 and XRhoA in the regulation of cell adhesion, we find a role for XRhoA in axis formation. When coinjected with dominant-negative BMP receptor (tBR) in the ventral side of the embryo, XRhoA causes the formation of head structures resembling the phenotype seen after coinjection of wnt inhibitors with dominant-negative BMP receptor. Since dominant-negative XRhoA is able to reduce the formation of head structures, we propose that XRhoA activity is essential for head formation. Thus, XRhoA may have a dual role in the embryo by regulating cell adhesion properties and pattern formation.

Mammalian BMP-1/Tolloid-related metalloproteinases, including novel family member mammalian Tolloid-like 2, have differential enzymatic activities and distributions of expression relevant to patterning and skeletogenesis

Vertebrate bone morphogenetic protein 1 (BMP-1) and Drosophila Tolloid (TLD) are prototypes of a family of metalloproteases with important roles in various developmental events. BMP-1 affects morphogenesis, at least partly, via biosynthetic processing of fibrillar collagens, while TLD affects dorsal-ventral patterning by releasing TGFbeta-like ligands from latent complexes with the secreted protein Short Gastrulation (SOG). Here, in a screen for additional mammalian members of this family of developmental proteases, we identify novel family member mammalian Tolloid-like 2 (mTLL-2) and compare enzymatic activities and expression domains of all four known mammalian BMP-1/TLD-like proteases [BMP-1, mammalian Tolloid (mTLD), mammalian Tolloid-like 1 (mTLL-1), and mTLL-2]. Despite high sequence similarities, distinct differences are shown in ability to process fibrillar collagen precursors and to cleave Chordin, the vertebrate orthologue of SOG. As previously demonstrated for BMP-1 and mTLD, mTLL-1 is shown to specifically process procollagen C-propeptides at the physiologically relevant site, while mTLL-2 is shown to lack this activity. BMP-1 and mTLL-1 are shown to cleave Chordin, at sites similar to procollagen C-propeptide cleavage sites, and to counteract dorsalizing effects of Chordin upon overexpression in Xenopus embryos. Proteases mTLD and mTLL-2 do not cleave Chordin. Differences in enzymatic activities and expression domains of the four proteases suggest BMP-1 as the major Chordin antagonist in early mammalian embryogenesis and in pre- and postnatal skeletogenesis.

New Bis(Indole) alkaloids of the topsentin class from the sponge spongosorites genitrix

Four bis(indole) alkaloids of the topsentin class, including two new brominated compounds (1 and 2), have been isolated from the sponge Spongosorites genitrix collected from Jaeju Island, Korea. The structures of the novel compounds were determined by spectroscopic methods. These compounds exhibited moderate cytotoxicity against a human leukemia cell-line (K-562).