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Biomedical subjects

Y L Yang

Publications and source records attributed to Y L Yang.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Synthesis and analgesic activity of non-aryl analogues of 4-methoxycarbonyl fentanyl].

In this paper, the synthesis and analgesic activities of some derivatives of 4-methoxycarbonyl fentanyl are reported, in which the 4-N-phenyl group or both the 4-N-phenyl group and the 1-beta-phenyl group were replaced by some nonaromatic groups. In the last case, some compounds showed very strong analgesic activity. For example, the analgesic activities of compounds 4 and 6 were shown to be 695 and 818 times more potent than that of morphine respectively. The structure-analgesic activity relationships were discussed.

Analgesics, Opioid↗
PubMed1993

[Diagnosis of subclinical hepatic encephalopathy: a parallel and comparative study between the evoked potentials and the performance psychometric tests].

The authors report the results of a parallel study between the three kinds of evoked potentials (EP) i.e. visual, brainstem auditory and somatosensory evoked potentials (VEP, BAEP and SEP) and psychometric tests in 30 posthepatitic cirrhotic patients. The results were compared with those from 20 peptic ulcer patients in healing stage. Psychometric tests were abnormal in 65.5% of the cirrhotic and in none of the peptic ulcer patients. The three kinds of evoked potentials were abnormal in 58.6% of the cirrhotic patients and in 5% of the peptic ulcer patients. The VEP, BAEP and SEP was abnormal in 13.3%, 10% and 50% of the cirrhotics respectively. The results of this study showed: of the three kinds of evoked potentials, SEP is the most sensitive one. The evoked potentials and the performance psychometric tests are complementary in the diagnosis of subclinical hepatic encephalopathy.

Adult↗
PubMed1992

Mutations affecting RNA-DNA hybrid formation of the ColE1 replication primer RNA. Restoration of RNA I sensitivity to a copy-number mutant by second-site mutations.

Certain high copy-number mutants of the ColE1 plasmid produce a primer RNA that, unlike the wild-type, is resistant to inhibition by the plasmid-encoded replication inhibitor RNA I. We show that this resistance is associated with the ability of mutant primer RNA to hybridize to the DNA template strand more efficiently than does the wild-type transcript in vitro. We have isolated two second-site intramolecular suppressor mutations that partially restore wild-type copy number behavior to the high copy-number mutant in vivo. Each of these mutations alters a second base in primer RNA near the original mutation. We show that the primer RNA made by the pseudo-revertants regained wild-type-like sensitivity to RNA I in vitro. Also, the efficiency of RNA-DNA hybrid formation by the pseudo-revertant primer RNAs is restored to a level similar to that of wild-type primer. Using non-denaturing gel electrophoresis as an indication of RNA conformation, we identified two primer RNA conformers, each of 550 nucleotides, whose equilibrium distribution differs between wild-type and the mutant plasmid. The pseudo-revertant plasmids have a conformer distribution similar to that of wild-type, indicating that these primer sequence changes have long-range effects on primer conformation. An oligonucleotide complementary to the primer domain containing the mutation reduced hybrid formation when present during primer elongation. These results indicate that the copy-number behavior of these plasmids is a consequence of conformational alterations in primer RNA that alter its hybridization efficiency with the DNA template strand and its sensitivity to inhibition by RNA I.

Bacteriocin Plasmids↗
PubMed1992

[Effects of naphthylmethyl isoquinoline on contraction and calcium flux of rabbit vascular strips in vitro].

Naphthylmethyl isoquinoline (NI) 1-30 mumol.L-1 inhibited the contraction of rabbit vascular smooth muscle in vitro induced by KCl, CaCl2, and norepinephrine (NE). NI 0.3-30 mumol.L-1 blocked 45Ca2+ influx process in vascular smooth muscle of aorta, mesenteric and femoral arteries by addition of KCl and NE. NI 3-10 mumol.L-1 had no effect on 45Ca2+ efflux from aorta at resting state. These results suggest that the relaxing effect of NI on rabbit blood vessels may be relevant to the inhibition of Ca2+ influx into vascular smooth muscle.

Animals↗
PubMed1992

[Synthesis, analgesic activity and structure-activity relationship of 4-N-propionyl analogs of cis-3-methyl fentanyl].

The synthesis of some 4-N-propionyl analogs of cis-3-methyl fentanyl by acyl chloride method. anhydride method, mixed anhydride method and DCC method is reported. The ethyl group in 4-N-propionyl portion of cis-3-methyl fentanyl was substituted by some groups with different electronic property. In mouse hot plate test, all compounds showed typical morphine-like action with analgesic potency corresponding to 49-1963 times that of morphine. Compound 3 was found to exhibit higher analgesic activity than cis-3-methyl fentanyl. Semiempirical INDO calculations have been undertaken for 4 typical compounds and it was found that as a result of introduction of chlorovinyl, compound 3 exhibited characteristics of electronic structure different from that of cis-3-methyl fentanyl. The relationships between analgesic activity and the electronic structure of these compounds were discussed.

Analgesics, Opioid↗
PubMed1991

Clinical evaluation of three occlusal registration methods for guided closure contacts.

This clinical study compared two occlusal registration methods (Occlusal Indicator Wax and Accufilm) with the T-Scan system for the identification of guided closure contacts. The patients were divided into two groups according to the centric relation-maximum intercuspation (CR-MIP) discrepancy and comparisons of guided closure contacts were performed with the paired methods. Wax and Accufilm materials were significantly different in their agreement on guided closure contacts. The T-Scan system demonstrated less of a disparity with both methods but more closely resembled the Occlusal Indicator Wax material. The CR-MIP slide also significantly affected the agreement between methods during identification of guided closure contacts.

Bite Force↗
PubMed1991

[Synthesis and analgesic activity of analogs of U-50488, an opiate kappa-agonist].

In this paper, we report the synthesis and analgesic activities in mouse hot plate test and writhing test of some analogs of U-50488, a kappa-agonist. Results showed that compounds in which the amino group was pyrrolinyl had higher kappa-agonist activity and the substitution of two chlorine atoms in 3 and 4-positions of the benzene nucleus was very important to kappa-activity. Furthermore, all of compounds in which the amino group was piperidyl, piperazinyl or morpholinyl exhibited very weak kappa-agonist activity.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1991

[Synthesis and analgesic activity of analogs of 4-methoxymethyl fentanyl].

In this paper, the synthesis and analgesic activities of some derivatives of N-[1-(2-phenylethyl)-4-methoxymethyl-4-piperidinyl]-N-propionylanilin e (4-methoxymethyl fentanyl) are reported. In mouse hot plate test, most compounds in this series showed strong narcotic analgesic activities but their activities were lower than those of compounds in the series of 4-methoxycarbonyl fentanyl.

Analgesics, Opioid↗
PubMed1991

Cloning of GL-7-ACA acylase gene from Pseudomonas sp. 130 and its expression in Escherichia coli.

Using BamHI digested and dephosphorylated pBR322 as vector, a GL-7-ACA acylase gene from Pseudomonas sp. 130 chromosomal DNA was cloned and expressed in Escherichia coli C600. Seven positive clones were detected from 3205 recombinant plasmids with 32P-labeled oligonucleotide probes in situ hybridization. Out of them, three clones which produced active GL-7-ACA acylase were identified by radio-immunological assay, chemical test and chromatographic analysis of reaction mixture. The plasmid DNAs of recombinant pMR5, pMR6 and pMR7 were extracted. Analysis of gel electrophoresis indicated that pMR5 and pMR7 contained the same 6.8kb fragment and the size of the insert in pNR6 was 5.7 kb. The effects of various E. coli hosts on the expression of cloned GL-7-ACA acylase gene is also presented.

Amidohydrolases↗
PubMed1991

Stress-induced regulation of glucocorticoid receptor gene expression in the rat.

To investigate the mechanism of the changes in glucocorticoid receptor (GR) under various stress conditions, experiments were carried out on normal and partial adrenalectomized rats by utilizing radioligand binding assay and molecular hybridization. It was found that hepatic GR binding capacity and GR mRNA in intact rats decreased significantly after the scalding stress, but the changes in GR binding capacity is mainly owing to the decrease in GR mRNA levels, and other mechanisms at protein level are also involved. In partial adrenalectomized rats, hepatic GR binding capacity and GR mRNA were increased instead of decreased, whereas serum corticosterone did not rise in response to the scalding stress. Therefore, it may be concluded that the decrease in GR binding capacity and GR mRNA in intact rats after the scalding stress is mainly the result of the increased concentration of serum corticosterone. Our further studies did demonstrate that there exists downregulation of GR mRNA in rats by exogenous administration of hydrocortisone. It is also suggested that there might be factors that can upregulate GR and GR mRNA in intact rats after the scalding stress.

Adrenal Glands↗
PubMed1990

Human dopamine D1 receptor encoded by an intronless gene on chromosome 5.

Receptors for dopamine have been classified into two functional types, D1 and D2. They belong to the family of receptors acting through G (or guanine nucleotide-binding) proteins. D2 receptors inhibit adenylyl cyclase, but D1 receptors stimulate adenylyl cyclase and activate cyclic AMP-dependent protein kinases. Dopamine D1 and D2 receptors are targets of drug therapy in many psychomotor disorders, including Parkinson's disease and schizophrenia, and may also have a role in drug addiction and alcoholism. D1 receptors regulate neuron growth and differentiation, influence behaviour and modify dopamine D2 receptor-mediated events. We report here the cloning of the D1 receptor gene, which resides on an intronless region on the long arm of chromosome 5, near two other members of the G-linked receptor family. The expressed protein, encoded by 446 amino acids, binds drugs with affinities identical to the native human D1 receptor. The presence of a D1 receptor gene restriction fragment length polymorphism will be helpful for future disease linkage studies.

Amino Acid Sequence↗
PubMed1990

Reflectance as an indirect measurement of the extent of laser-induced coagulation.

Two-dimensional reflectance images and surface thermal distributions were recorded during argon laser induced coagulation. During laser irradiation, coagulated egg yolk formed a white lesion. The whiteness, or reflectance caused by backscattering of light from the forming lesion, would be measured after a short delay from the onset of laser irradiation. In the experiments which covered exposure time from 4.5 to 17.0 s, we found that it started slowly, the reflectance increased rapidly once the surface temperature of the lesion reached approximately 90 degrees C. After this rapid rise, the reflectance began to taper off until no change in reflectance was recorded. There was a 0.98 correlation between lesion diameter measured from a two dimensional reflectance image and the lesion diameter that was measured microscopically. There was a 0.92 correlation between reflectance at the center of the lesion and microscopically measured depth of coagulation at the same point. However, the correlation between microscopically measured coagulation depth and width was only 0.88.

Egg Yolk↗
PubMed1990

[Synthesis and analgesic activity of 1-substituted derivatives of 4-methoxycarbonyl-4-N-propionylanilinepiperidine].

In this paper, the synthesis and analgesic activities of a series of 1-substituted derivatives of N-[1-(2-phenylethyl)-4-methoxycarbonyl-4-piperidinyl]-N-propionylanil ine (4-methoxycarbonyl fentanyl) are reported. Preliminary pharmacological results showed that most compounds in this series exhibited typical morphine-like action and that replacement of beta-phenyl group in the 1-position of piperidine ring of 4-methoxycarbonyl fentanyl by some substituents e.g., some substituted vinyl groups, heterocyclic (or alcyclic) radicals, alkyl groups or N-methyl-anilino groups, can keep strong analgesic activity. Especially, some substituted vinyl groups were found to be effective groups which could replace 1-beta-phenyl group of 4-methoxycarbonyl fentanyl. Compounds N-[1-(3, 4-dimethyl-3-pentenyl)-4-methoxycarbonyl-4-piperidinyl]-N- propionylaniline(1321) and N-[1-(4-methyl-3-pentenyl)-4-methoxycarbonyl-4-piperidinyl]-N- propionylaniline(1302) exhibited higher analgesic activity than that of 4-methoxycarbonyl fentanyl.

Analgesics, Opioid↗
PubMed1990

[Effect of naphthylmethyl isoquinoline on the isolated guinea pig myocardium].

The effect of naphthylmethyl isoquinoline on amplitude of contraction and automaticity of guinea pig atria were investigated. The compound was found to markedly inhibit the force of contraction and automaticity in a concentration-dependent way. Propranolol competitively antagonized the effect of isoproterenol with pA2 of 7.5. Naphthylmethyl isoquinoline and verapamil antagonized isoproterenol, but in a noncompetitive manner with the pD2' of 5.4 and 5.8, respectively. The effect of the compound on action potential and contractile force of guinea pig papillary muscles were also studied. It was shown to produce negative inotropic effects and shorten the fast action potential duration, but the maximal upstroke (Vmzx) and amplitude of action potential were not affected. Thus, an excitation-contraction uncoupling was observed. It also depressed the amplitude. Vmax and duration of Ca2(+)-mediated slow action potential induced by high K+. Elevation of the CaCl2 concentration from 2 to 5 mmol/L reversed its inhibition partially. These results indicate that naphthylmethyl isoquinoline has a blocking effect on calcium channels.

Action Potentials↗
PubMed1990

[Hypotensive effect of naphthylmethyl isoquinoline].

Naphthylmethyl isoquinoline (NI), a modified structure of tetrandrine, was synthesized by the China Pharmaceutical University. The effects of NI on blood pressure of animals and its possible mechanism were studied. In anesthetized rats and cats, iv NI lowered the mean arterial pressure. Meanwhile, the total peripheral vascular resistance was reduced markedly, but the heart rate, cardiac output and cardiac index showed no noticeable change. In rats its hypotensive effect was stronger than tetrandrine when equal toxic doses were compared. In conscious normotensive rats, renal hypertensive rats and SHR, oral administration of this compound resulted in a marked fall of systolic blood pressure which remained at a steady low level. It decreased the pressor response of adrenaline in rats. Intra-arterial injection of NI into the perfusing system decreased the posterior limb and renal vascular resistance immediately in constant-rate perfusion of the posterior limb and renal blood vessel of rats. It shifted the cumulative dose-response curves of noradrenaline, KCl and CaCl2 to the right in isolated rabbit aortic rings and depressed their maximal responses with IC50 9.7, 7.2 and 1.6 mumol/L, respectively, which were 2.9, 9.1 and 1.8 times stronger than that of tetrandrine, correspondingly. These results suggest that the hypotensive effect of naphthylmethyl isoquinoline is mainly attributable to its arteriolar dilatation by inhibiting calcium influx.

Animals↗
PubMed1990

[Synthesis and analgesic activity of 4-N-propionyl analogs of 4-methoxycarbonyl fentanyl].

In the present paper, the synthesis and analgesic activities of some 4-N-propionyl analogs of 4-methoxycarbonyl fentanyl are reported. In mouse hot plate test, most of these compounds showed strong narcotic analgesic activity. The analgesic activities of compounds 1379, 1385 and 1387 were found to be more potent than that of 4-methoxycarbonyl fentanyl.

Analgesics↗
PubMed1989

Down-regulation of glucocorticoid receptor and its relationship to the induction of rat liver tyrosine aminotransferase.

Administration of polyvinyl alcohol containing hydrocortisone (F-PVA) to rats twice caused a rapid increase of plasma glucocorticoids (GCs) around 30 micrograms/dl for 3 days. This rise led to decrease of glucocorticoid receptor (GR) in rat liver cytosol and spleen cells 1 h post F-PVA and remained at low level for more than 10 days. Two hours after administration of hydrocortisone 5 mg/100 g b. wt, the liver tyrosine aminotransferase (TAT) activity in normal rats increased from 13.5 +/- 2.9 to 50.7 +/- 8.9 units, while in rats injected with F-PVA 3 days ago it increased only from 13.9 +/- 2.3 to 21.0 +/- 6.3 U. The inductivity of rat liver remained low at 7, 11 and 20 days after the injection of F-PVA and recovered 30 days later. This study demonstrates the presence of down-regulation of GR in intact animal, and shows that the decrease of GR is accompanied by reduction of target organ response to GCs.

Adrenalectomy↗