[Changes in nitric oxide and endothelin on experimental guinea pigs with asthma].
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Animals↗
Biomedical subjects
W Yao
Publications and source records attributed to W Yao.
[Effects of Rg1 on calcium channel of guinea pig ventricular myocytes].
OBJECTIVE: To evaluate the effect of Rg1 (purified saponin of Panax notoginseng) on L-Ca2+ channel of guinea pig ventricular myocytes. METHOD: The whole-cell patch clamp recording technique. RESULT: When the holding potential was kept at -40 mV, and the cell was depolarized to +40 mV for 150 ms at a frequency of 0.5 Hz.Rg1 10 mumol.L-1 and 30 mumol.L-1 could not reduce Bay K 8644 and nifedipine-sensitive L-type Ca2+ inward current (P > 0.05, n = 5). CONCLUSION: Rg1 should not be a Ca2+ channel antagonist.
Animals↗
[Molecular cloning of rat OB gene and its expression in Escherichia coli].
In order to provide rat OB gene product for studying the relationship between obesity and noninfectious diseases, rat OB cDNA was amplified by RT-PCR technique. 460 bp fragment of OB cDNA was subcloned into EcoRI/BamHI site of plasmid pUC 19. Sequence analysis of OB cDNA revealed that the translation reading frame was identical with that reported in the literature. Thereby plasmid pBV220-rOB was constructed and the specific expression of OB gene in E. coli identified by SDS-PAGE electrophoresis was obtained.
Amino Acid Sequence↗
Immunohistochemical evaluation of cholinergic neurons in the rat superior olivary complex.
The cholinergic system in the rat superior olivary complex (SOC) was evaluated by immunohistochemistry for choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) and histochemistry for acetylcholinesterase (AChE). ChAT-positive somata were found mostly in the lateral superior olive (LSO) and ventral nucleus of the trapezoid body (VNTB). In the LSO, there were both rostral-caudal and medial-lateral gradients in concentration of ChAT-positive somata; the highest concentration was in the middle of the rostral-caudal extent and the most medial part. The estimated total number of ChAT-positive neurons in the LSO was similar to previous estimates of the total number of lateral olivocochlear neurons. Two groups of ChAT-positive somata were found in the VNTB: a dorsolateral group of larger, multipolar, and more darkly labeled neurons and a ventromedial group of smaller, oval, and more lightly labeled neurons, which was about 5 times as numerous. There was a caudal-to-rostral increase in number of neurons in each group. VAChT immunoreactivity, predominantly localized in puncta, was seen in LSO, VNTB, and LNTB, and, to a lesser extent, in other parts of the SOC. VAChT-positive somata were also found in the VNTB and medial LSO. This distribution pattern of VAChT was generally similar to that of ChAT. AChE labeling had a similar appearance to ChAT labeling in the VNTB but differed in the LSO, where AChE labeling was lighter and associated more with neuropil than with somata.
Acetylcholinesterase↗
Modulation of receptor and receptor subtype affinities using diastereomeric and enantiomeric monosaccharide scaffolds as a means to structural and biological diversity. A new route to ether synthesis.
We show that carbohydrates constitute an attractive source of readily available, stereochemically defined scaffolds for the facile attachment of side chains contained in genetically encoded and other amino acids. beta-D- and beta-L-glucose, L-mannose, and the 6-deoxy-6-N-analogue of beta-D-glucose have been employed to synthesize peptidomimetics that bind the SRIF receptors on AtT-20 mouse pituitary cells, five cloned human receptor subtypes (hSSTRs), and the NK-1 receptor. The affinity profile of various sugar-based ligands at the hSSTRs is compared with that of SRIF. Compound 19 bound hSSTR4 with a Ki of 100 nM. Subtle structural changes affect affinities. Evidence is presented that suggests that one compound (8) binds both the AtT-20 cell receptors and the five hSSTRs via a unique mode. The SARs of the glycosides at SRIF receptors differ markedly from those at the NK-1 receptor. For example a 4-benzyl substituent is important for SRIF receptor binding, but the 4-desbenzyl analogue 27 was highly potent (IC50 of 27 nM) at the NK-1 receptor. A new, nonbasic method for the synthesis of base-sensitive ethers from primary and secondary alcohols is also described.
Animals↗
Voltage- and use-dependent effect of 7-chlor-benzyltetrahydropalmatine on sodium currents in guinea pig ventricular myocytes.
The whole-cell patch-clamp technique was employed to obtain information about the voltage-dependence and kinetics of interaction of 7-chlor-benzyltetrahydropalmatine (7-Cl-BTHP) with cardiac sodium channels. 7-Cl-BTHP (30 mol/L) significantly decreased the peak sodium current (from 7.8 +/- 1.8 nA to 5.3 +/- 1.4 nA, P < 0.01, n = 5), without producing a shift of the current-voltage curve. It shifted the inactivation curves of sodium current to hyperpolarized potentials, and the V0.5 was shifted from -(82.5 +/- 2.5) mV to -(95 +/- 2.4) mV (P < 0.05, n = 4). 7-Cl-BTHP produced a significant use-dependent effect that was proportional to the duration of the voltage step. In addition, 7-Cl-BTHP slowed the recovery of sodium channel from inactivation, which could explain its use-dependent effects on sodium current. The characteristics of 7-Cl-BTHP blockage suggest that this agent binds preferentially to inactivated sodium channels.
Animals↗
Transport characteristics of peptidomimetics. Effect of the pyrrolinone bioisostere on transport across Caco-2 cell monolayers.
PURPOSE: To compare the permeation characteristics of amide bond-containing HIV-1 protease inhibitors and their pyrrolinone-containing counterparts across Caco-2 cell monolayers, a model of the intestinal mucosa. METHODS: Transepithelial transport and cellular uptake of three pairs of amide bond-containing and pyrrolinone-based peptidomimetics were assessed in the presence and absence of cyclosporin A using the Caco-2 cell culture model. The potential of the peptidomimetics to interact with biological membranes was estimated by IAM chromatography. RESULTS: In the absence of cyclosporin A, apical (AP) to basolateral (BL) flux of all compounds studied was less than the flux determined in the opposite direction (i.e., BL-to-AP). The ratio of the apparent permeability coefficients (Papp) calculated for the BL-to-AP and AP-to-BL transport (P(BL-->AP)/P(AP-->BL)) varied between 1.7 and 36.2. When individual pairs were ompared, P(BL-->AP)/P(AP-BL) ratios of the pyrrolinone-containing compounds were 1.5 to 11.5 times greater than those determined for the amide bond-containing analogs. Addition of 25 microM cyclosporin A to the transport buffer reduced the P(BL-->AP)/P(AP-->BL) ratios for all protease inhibitors to a value close to unity. Under these conditions, the amide bond-containing peptidomimetics were at least 1.6 to 2.8 times more able to permeate Caco-2 cell monolayers than were the pyrrolinone-containing compounds. The intrinsic uptake characteristics into Caco-2 cells determined in the presence of 25 microM cyclosporin A were slightly greater for the amide bond-containing protease inhibitors than for the pyrrolinone-containing analogs. These uptake results are consistent with the transepithelial transport results determined across this in vitro model of the intestinal mucosa. CONCLUSIONS: The amide bond-containing and pyrrolinone-based peptidomimetics are substrates for apically polarized efflux systems present in Caco-2 cell monolayers. The intrinsic permeabilities of the amide bond-containing protease inhibitors are slightly greater than the intrinsic permeabilities of the pyrrolinone-based analogs through Caco-2 cell monolayers.
Biological Transport↗
Aberrant internal carotid artery causing erosion of the otic capsule: an unusual cause of pulsatile tinnitus.
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Bone Resorption↗
Separate bisphosphatase domain of chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: the role of the C-terminal tail in modulating enzyme activity.
The separate bisphosphatase domain (amino acid residues 243-468) of the chicken liver bifunctional enzyme 6-phosphofructo-2-kinase-fructose-2,6-bisphosphatase was expressed in Escherichia coli and purified to homogeneity. The fructose-2, 6-bisphosphatase activity of the separate domain was 7-fold higher than that of the native bifunctional enzyme, and exhibited substrate inhibition characteristic of the native enzyme. The inhibition of the enzymes by fructose 2,6-bisphosphate could be overcome by Pi, glycerol 3-phosphate and GTP. Deletion of 30 amino acid residues from the C-terminus of the separate domain resulted in around a 5-fold increase in the Vmax of the bisphosphatase. Also, the truncated form was more accessible to chemical modification by diethyl pyrocarbonate and N-ethylmaleimide, suggesting a more open structure than the wild-type form. In addition, the mutation of cysteine-389 to alanine increased bisphosphatase activity by 20% and the Km value for fructose 2,6-bisphosphate by 3-fold, and both the point mutation at cysteine-389 and the deletional mutation led to the predominantly insoluble expression of the enzyme. The results indicated that the C-terminal tail plays a role in modulating the enzyme activity and suggested that the difference in the C-terminal tail sequence is responsible for the difference in activity of the chicken and rat liver fructose-2,6-bisphosphatases. It is postulated that an interaction between the C-terminal tail and the active site might be present.
Animals↗
An orally bioavailable pyrrolinone inhibitor of HIV-1 protease: computational analysis and X-ray crystal structure of the enzyme complex.
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Administration, Oral↗
Densitometric evaluation of markers for cholinergic transmission in rat superior olivary complex.
Cholinergic transmission in the rat superior olivary complex (SOC) was assessed by densitometric measurements of labeling with several markers: acetylcholinesterase (AChE) histochemistry, choline acetyltransferase (ChAT) immunohistochemistry, and muscarinic acetylcholine receptor (M35) immunohistochemistry and N-methylscopolamine (NMS) binding autoradiography, as well as its subtype 2 (m2) immunohistochemistry. The markers which may occur in cholinergic neurons (ChAT, m2 receptor and AChE) showed dense labeling in the ventral nucleus of the trapezoid body (VNTB), in line with other evidence that it contains cholinergic neuron somata. The markers which are predominantly in cholinoceptive neurons (M35 and NMS) showed less labeling in the SOC, suggesting few muscarinic cholinergic inputs. These results are compared with those for the cochlear nucleus.
Acetylcholinesterase↗
In vitro selection of packaging sites in a double-stranded RNA virus.
The Saccharomyces cerevisiae double-stranded RNA virus ScVL1 recognizes a small sequence in the viral plus strand for both packaging and replication. Viral particles will bind to this viral binding sequence (VBS) with high affinity in vitro. An in vitro selection procedure has been used to optimize binding, and the sequences isolated have been analyzed for packaging and replication in vivo. The selected sequence consists of a stem with a bulged A residue topped by a loop of several bases. Four residues of the 18 bases are absolutely conserved for tight binding. These all fall in regions that appear to be single stranded. Eight more residues have preferred identities, and six of these are in the stem. The VBS is similar to the R17 bacteriophage coat protein binding site. Packaging and replication require tight binding to viral particles.
Binding Sites↗
[Studies on the pharmacognosy of Cortex Illicii and its adulterants].
The traditional Chinese Medicine Cortex Illicii and its adulterants were studied on textual identification, botanical origin, morphological and histological characters. The TLC and UV spertra methods were established to separate and estimate Difengpin, Magnolol and beta-sitosterol in Cortex Illicii and its products.
Chromatography, Thin Layer↗
[Effects of inhalated isosorbide dinitrate on endothelin and nitric oxide and its therapeutic efficacy for experimental guinea-pigs with asthma].
To probe into the correlation between the changes of endothelin and nitric oxide in bronchial alveolar lavage fluid (BALF) and the treatment of inhaling isosorbide dinitrate on experimental guinea pigs with asthma, we divided 25 guinea pigs randomly into three groups (Control group, Asthma group, Isosorbide dinitrate group), and induced some subjects by inhalation of aerosolized ovalbumin as the model of asthma to investigate the endothelin (ET) and nitric oxide (NO) level in BALF as well as the pathological change of the respiratory tract. We found that the level of endothelin and nitric oxide in BALF were all elevated in experimental guinea pigs with asthma, but the degree of increase of NO in BALF was lower than that of ET. The NO and the ET levels in BALF were negative correlation (r = -0.8050, P < 0.01). After having been treated with aerosolized isosorbide dinitrate, the NO level in BALF was significantly elevated and the ET level in BALF was decreased in comparison with the asthma group (P < 0.001, respectively). Moreover, the eosinophile infiltration, exoserosis, and epithalaxia of the respiratory tract of the guinea-pigs were all lightened. The results suggest that inhaled isosoratory dinitrate could be used for treating asthma, and its mechanism may be elevation of NO level and decrease of ET level in BALF.
Administration, Inhalation↗
The effect of neuropeptides on vessel tone and cAMP production.
The effect of VIP, PHM, PHV, PACAP-27, and PACAP-38 on vessel tone and cAMP production was investigated in rabbit ovarian arteries in vitro. The peptides (10(-7)M) induced a significant relaxation on NA-precontracted vessels and displayed similar potencies. The cAMP accumulation induced by PACAP-27 and PACAP-38 was five times higher than the cAMP content induced by VIP, PHM, and PHV. NPY (10(-7)M) markedly reversed the relaxations induced by VIP, PHM, PHV, PACAP-27, and PACAP-38 but did not at all affect the cAMP production induced by these peptides. We conclude that the relaxation induced by VIP, PHM, PHV, PACAP-27, and PACAP-38 and the contraction evoked by NPY are not solely related to the changes of cAMP contents, and that in addition to cAMP, another intracellular signal transduction pathway may be involved.
Animals↗
Immunolocalization of muscarinic acetylcholine subtype 2 receptors in rat cochlear nucleus.
It has been suggested that cholinergic effects in the rat cochlear nucleus (CN) are mediated by muscarinic acetylcholine receptors. In this study, immunohistochemistry for muscarinic subtype 2 (m2) receptors using a monoclonal subtype-specific antibody (Levey et al. [1995] J. Comp. Neurol. 351:339-356) revealed an m2-like system in the rat CN. A prominent lamina of m2-immunoreactive fibers and puncta was located in a subgranular layer of the caudal anteroventral cochlear nucleus (AVCN) and the posteroventral cochlear nucleus (PVCN). The superficial granular layer of the rostral AVCN and the medial sheet region also contained notable immunoreactivity for m2. Some labeled somata and their processes were found in magnocellular regions of the ventral CN. A network of neurites and puncta was located in the fusiform soma and deep layers of the dorsal CN. The olivocochlear bundle and its branches to the CN were also m2 immunoreactive and possibly contributed m2-labeled fibers and terminals to the CN. Some similarities and some differences were found between this m2 receptor distribution pattern and previous results for choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and muscarinic acetylcholine receptor immunohistochemistry and binding in the CN. The results suggest that m2 receptors that are located both pre- and postsynaptically mediate many cholinergic effects in the rat CN.
Acetylcholinesterase↗
Synthesis of potent cyclic hexapeptide NK-1 antagonists. Use of a minilibrary in transforming a peptidal somatostatin receptor ligand into an NK-1 receptor ligand via a polyvalent peptidomimetic.
The endogenous peptides somatostatin (SRIF) and substance P comprise very different structures. Although both bind G-protein-coupled receptors, the SRIF receptors (SSTR 1-5) recognize SRIF and related peptides which retain its beta-turn such as the potent cyclic hexapeptide SRIF agonist L-363,301 (6a), but not substance P. Conversely the NK-1 receptor binds substance P but not the above ligands. In contrast, the beta-D-glucosides 1 and 2, designed to mimic the beta-turn of 6a, bind both receptors. This observation led us to attempt the conversion of 6a into the first potent, selective cyclic hexapeptide ligand for the NK-1 receptor. To this end, we combined design with a minilibrary approach. The goal was accomplished with surprising ease, leading to the NK-1 receptor antagonist 9 (IC50 2.0 +/- 0.4 nM). This demonstrates that peptidomimetics, incorporating in this case the promiscuous beta-D-glucose scaffold, can provide valuable clues about receptor similarities not revealed by their endogenous ligands. In addition, this work suggests that the use of libraries and rational design need not be mutually exclusive approaches to lead discovery.
Amino Acid Sequence↗
Vascular effects and cyclic AMP production produced by VIP, PHM, PHV, PACAP-27, PACAP-38, and NPY on rabbit ovarian artery.
The relationship between vessel tone and cAMP production induced by vasoactive intestinal polypeptide (VIP), peptide histidine methionine (PHM), peptide histidine valine (PHV), pituitary adenylate cyclase activating polypeptide (PACAP-27 and PACAP-38), and neuropeptide Y (NPY) was investigated in rabbit ovarian arteries in vitro. VIP, PHM, PHV, PACAP-27, and PACAP-38 added in single-dose experiments (10(-9), 10(-8), 10(-7), and 10(-6) M) induced all a significant dose-related relaxation of noradrenaline (NA)-precontracted vessels and displayed similar potencies. VIP, PHM, PHV, PACAP-27, and PACAP-38 all increased cyclic adenosine monophosphate (cAMP) accumulation. The cAMP accumulation induced by PACAP-27 and PACAP-38 was five times higher than the cAMP content induced by the other three peptides. The peptide-induced smooth muscle relaxation did not correlate to the cAMP accumulation. NPY (10(-7) M) markedly reversed the relaxations induced by VIP, PHM, PHV, PACAP-27, and PACAP-38, but did not influence the cAMP production induced by these peptides. In conclusion, the relaxation induced by VIP, PHM, PHV, PACAP-27, and PACAP-38 and the contraction induced by NPY are not solely related to the changes of cAMP contents. These findings indicate that in addition to cAMP, another intracellular signal transduction pathway may be involved in the relaxation and contraction induced by these peptides in rabbit ovarian artery.
Animals↗