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Biomedical subjects

L Weng

Publications and source records attributed to L Weng.

At least 55 records · Page 3Linked to original sources
PubMed1995

[A study on the optimal regimen of mifepristone with prostaglandin for termination of early pregnancy].

One thousand and thirty-five women in early pregnancy (< or = 49 days), who requested medical abortion were randomly allocated into 8 groups. Mifepristone and 15-methyt-PGF2 alpha vaginal suppository (PG05) and misoprostol oral (tablets) were given as the following 8 regimens: group 1 (n = 195): a single dose of mifepristone 200 mg + PG05 1 mg on the 3rd or 4th day; group 2 (n = 249): mifepristone 25 mg b.i.d. (total amount of 150mg) + PG05 1mg on the 3rd or 4th day; group 3 (n = 67): mifepristone 25 mg b.i.d. (total amount of 125mg) + PG05 1mg in the morning of the 3rd day; group 4 (n = 108): a single dose of mifepristone 200mg + misoprostol 600 micrograms on the 3rd day; group 5 (n = 199): a single dose of mifepristone 150mg + misoprostol 600 micrograms on the 3rd day; group 6 (n = 60): mifepristone 50 mg was given immediately, then 25 mg b.i.d. (total amount of 150mg + misoprostol 600 micrograms; group 7 (n = 123): mifepristone 50 mg in the morning and 25mg in the evening for two days (total amount of 150 mg) + misoprostol 600 micrograms; group 8 (n = 34): mifepristone 25 mg b.i.d. (total amount of 125mg) + misoprostol 400 micrograms. As a result, the complete abortion rate of each group was 92.8%, 95.2%, 92.5%, 93.5%, 87.4%, 98.4%, 92.7% and 94.1% successively. The rate of group 5 was significantly lower than that of group 2 and 6 (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Induced↗
PubMed1995

[Histological study of uterine cervix during termination of early pregnancy by mifepristone and prostaglandins].

OBJECTIVE: To study the histological changes of uterine cervix during termination of early pregnancy by mifepristone and prostaglandins (PG). METHODS: A total of 24 women who requested medical abortion was recruited. For each woman, 3 cervical biopsies were taken: before mifepristone treatment; 48 hours after mifepristone 150 mg single dose treatment (i.e. immediately before PG administration); and 1 hour after gestational sac expulsion. Specimens were studied by optical and electron microscopy. RESULTS: Significant collagenolysis as demonstrated by marked reduction and irregularity of collagen fibers, abundant accumulation of an amorphorous material of ground substance, and infiltration of neutrophilic polymorphonuclear leukocytes were shown in stroma as well as in the deep portion of cervix after mifepristone as compared to the samples of early pregnant cervix before treatment. These changes presented to a further extent after the expulsion of gestational sac. CONCLUSION: The changes observed were similar to previous reports during cervical dilatation in term delivery. The present study confirmed the histological cervical ripening effect by mifepristone and suggested it may be used as cervical ripening agent before induction of labor as well.

Abortifacient Agents, Nonsteroidal↗
PubMed1994

An epidemiological study on the relationship of ectopic pregnancy and the use of contraceptives in Beijing--the incidence of ectopic pregnancy in the Beijing area. Beijing Collaborating Study Group for Ectopic Pregnancy.

The incidence of ectopic pregnancy (EP) was studied through a 3-level monitoring network of maternal and child health care (MCH) in the entire Beijing area, including 82 hospitals, 19 MCH centers and 2 institutes for family planning. A total of 1,420 cases of EP were collected in a sample of 2.7 million women of reproductive age (15-49) during a one-year period from January 1 to December 31, 1990. The cases were confirmed by pathological examination or laparoscopy. In addition, epidemiological surveillance method was used. The results showed that the overall incidence of EP was 0.52 per thousand women of reproductive age (W = Women of reproductive age (15-49)) in the Beijing area, 0.6/1000W in the urban districts and 0.41/1000 in the rural area; 0.67/1000W married women, and 0.05/1000W in the unmarried. For married women, 0.54/1000W for those women using various contraceptive measures and 1.80/1000W for women using no contraceptives. The incidence of EP varies with different contraceptive methods. Female sterilization had the lowest incidence (0.18/1000W) and natural contraceptive measures (rhythm or withdrawal method) had the highest (2.43/1000W). It was 0.65/1000W in IUD users, 0.21/1000W in OC users and 0.57/1000W in couples using condoms or spermicides.

Adolescent↗
PubMed1994

[Experimental study on the effect of ipriflavone against osteoporosis in ovariectomized rats].

In order to evaluate the effect of Ipriflavone (BO, synthesized for the first time by the School of Pharmaceutical Sciences of WCUMS) against osteoporosis in ovariectomized (OVX) rats, 98 female Wistar rats were divided into 7 groups: bilateral OVX, sham operated (S), and 5 treatment groups after OVX, of which 3 groups were given domestic BO-25, 100, and 400 mg/kg BW (L, M, H), respectively, and the remaining two groups, BO (made in Japan)-100 mg/kg BW (J) and 17 beta-estradiol-4 mg/kg BW (E). One day after operation, BO and E were given daily and twice a week, respectively, by gavage to the animals, while S and OVX groups were treated with vehicles alone. On the 14th and 6th day prior to the sacrifice 0.25% tetracycline hydrochloride was administered i.p. to 6 rats of each group at a dosage of 25 mg/kg BW. The rats were sacrificed after 12 wks and blood samples were collected for serum Ca, P, and AkP activity. The uterines were removed and weighed. Undecalcified sections of the left proximal tibia were processed for bone histomorphometry, and HE sections of the right tibia were processed for bone pathology. The weights per unit bone length, the calcium and phosphorus contents of the left femur were measured. The results showed that in the OVX animals trabecular bone volume, trabecular thickness, and the ash content of bone were all significantly reduced. This bone loss was associated with increase in osteoclast index, osteoblast index, osteoid surface and serum AkP activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1993

Effects of cholinergic agonists on diacylglycerol and intracellular calcium levels in pancreatic beta-cells.

We have studied the effects of cholinergic agonists on the rates of insulin release and the concentrations of diacylglycerol (DAG) and intracellular free Ca2+ ([Ca2+]i) in the beta-cell line MIN6. Insulin secretion was stimulated by glucose, by glibenclamide and by bombesin. In the presence of glucose, both acetylcholine (ACh) and carbachol (CCh) produced a sustained increase in the rate of insulin release which was blocked by EGTA or verapamil. The DAG content of MIN6 beta-cells was not affected by glucose. Both CCh and ACh evoked an increase in DAG which was maximal after 5 min and returned to basal after 30 min; EGTA abolished the cholinergic-induced increase in DAG. ACh caused a transient rise in [Ca2+]i which was abolished by omission of Ca2+ or by addition of devapamil. Thus, cholinergic stimulation of beta-cell insulin release is associated with changes in both [Ca2+]i and DAG. The latter change persists longer than the former and activation of protein kinase C and sensitization of the secretory process to Ca2+ may underlie the prolonged effects of cholinergic agonists on insulin release. However, a secretory response to CCh was still evident after both [Ca2+]i and DAG had returned to control values suggesting that additional mechanisms may be involved.

Acetylcholine↗
PubMed1993

[The research on instant treatment of apical periodontitis with porous hydroxyapatite ceramic]

This paper described how to use hemorheology to observe the oral and maxillofacial inflammation.60 cases were reported,and 60 normal cases as control group.It revealed that etap of the oral maxillofacial inflammation were much higher than that of normal person(P<0.01),etab,etab-1/H,ESR,FA of the oral maxillofacial inflammation were higher than that of normal person(P<0.05).Because the disease belongs to the spectrum of blood stasis.The treatment method of the promoting blood circulation and removing blood stasis can be used in additional to the normal remedy.

Journal Article↗
PubMed1993

[Synthesis of protected active peptide analogues of cholecystokinin and study of their biological activities].

A number of protected active peptide analogues of Cholecystokinin were prepared in solution by N-end stretching method with active esters. In the synthesis t-butoxycarbonyl (Boc-) and benzyloxycarbonyl (Z-) were applied as protecting groups. Six oligopeptides which contained protecting groups have not yet been reported in literature. Their structures were identified by amino acid analysis, opticity, IR and FAB-MS. The results of preliminary pharmacological tests show all the samples have biological activities in various degrees.

Amino Acid Sequence↗
PubMed1993

[Analysis of estrogen receptors in normal bone and bone tumor tissues].

Thirteen human normal bone and fifteen bone tumor tissues were assayed for estrogen receptor (ER) by Dextran-coated Charcoal method (Scatchard plot). The results showed that the concentrations of ER in normal bone tissues (15.12 +/- 14.68 fmol/mg pro) were higher than that of bone malignant tumors (8.04 +/- 6.71 fmol/mg pro) P < 0.05). The binding dissociation constants (Kd) of ER in bone tumors (18.46 +/- 27.10 x 10(-11) mol/L) was lower than those in normal ones (39.91 +/- 20.13 x 10(-11) mol/L) (P < 0.025). The percentages for positive score of ER in normal and tumor ones (23.1%, 26.7%) were not significantly different (P > 0.05). Our study indicated that the variations of concentration and affinity of ER in bone related to the tumor incidence. That cytosol ER content was decreased in malignant bone tumors whereas that of affinity increase suggests an impairment or change of an intact receptor mechanism in this tissues.

Adolescent↗
PubMed1992

Apparent first-order behavior under second-order kinetic conditions: a general concept illustrated by the reversible binding of hydrogen peroxide to cytochrome c oxidase.

The theory of the second-order reversible reaction, A + B<-->A.B, has been extensively discussed. Apparent first-order behavior is observed when, for example, [B] >> [A]. If the reaction exhibits second-order behavior then it is presumed that the concentrations of A and B were initially equal and that they remain equal during the reaction. However, in the case of hydrogen peroxide binding to cytochrome c oxidase, Weng & Baker (1991, Biochemistry 30, 5727-5733) showed that the observed rate was rigorously first order over a broad concentration range of ligand, including the stoichiometric case. It was further shown that kobs increased linearly with [H2O2], precluding the possibility of a rate-limiting, unimolecular pre-step. The current work examines the theoretical rate equation for the bimolecular, reversible reaction when [A] = [B]. Simulations show that this equimolar condition resulted in rigorous exponential binding as kd, the equilibrium dissociation constant for the A.B complex, approached the initial concentration of A (or B). In particular, the second-order simulation was rigorously exponential when [A]o/Kd = 0.5, and showed only minor deviations when the ratio was increased to 25. These results demonstrate that a reversible, bimolecular reaction can appear first order even under second order conditions, without the need for more complicated mechanisms.

Electron Transport Complex IV↗
PubMed1991

Ultrasound speckle analysis based on the K distribution.

The departure of speckle magnitude from Rayleigh statistics was applied to examine insonated phantoms with both low and high concentrations of scatterers. A mathematical model, the K distribution of Jakeman, was used to characterize non-Rayleigh statistics. This model contains a parameter, alpha, which characterizes the clustering of the scattering sites in a medium. It is shown from phantom experiments that alpha is linearly proportional to the log-scaled scatterer concentration in a range from about 1 to 30 scatterers per sample volume.

Mathematics↗
PubMed1984

Ultrasound-accelerated immunoassay, as exemplified by enzyme immunoassay of choriogonadotropin.

The rate-limiting step in many solid-phase immunoassays is associated with the slow kinetics of binding of macro-molecular antigen and conjugate to the immobilized phase. We demonstrate that the use of ultrasonic energy to enhance mass transport across liquid/solid interfaces can dramatically accelerate antigen binding to immobilized antibodies. We use an ultrasound-accelerated procedure with an enzyme-channelling test strip containing glucose oxidase and specific antibody to the alpha-subunit of human choriogonadotropin (HCG) co-immobilized onto a cellulose support. A horseradish peroxidase conjugate of monospecific antibody to the beta-subunit of HCG is used in the liquid phase to complete the immune "sandwich." Use of ultrasound to accelerate binding and of enzyme channelling to eliminate wash steps result in a simple two-incubation protocol by which 25 int. units of urinary HCG per liter can be detected visually in less than 20 min of assay time.

Chorionic Gonadotropin↗
PubMed1980

Amino acid sequence at the allosteric site of sheep heart phosphofructokinase.

Covalent modification of sheep heart phosphofructokinase with the affinity labeling reagent p-fluorosulfonyl[14C]benzoyl-5'-adenosine caused a loss of allosteric properties. This modification appears to occur at the binding site that is specific for the allosteric activators AMP, cAMP, and ADP (Mansour, T.E., and Colman, R.F. (1978) Biochem. Biophys. Res. Commun. 81, 1370-1376). In the current study, the site of modification has been demonstrated to be a lysine residue. A nonapeptide containing a covalently bound [14C]carboxybenzenesulfonyl group attached to alysine residue has been isolated following tryptic digestion. The amino acid sequence of the peptide is Asn-Phe-Ala-Thr-Lys-Met-Gly-Ala-Lys. The fifth residue in this sequence, lysine, contained the covalently bonded reagent.

Allosteric Site↗
PubMed1978

The covalent structure of bovine liver rhodanese. NH2-terminal sequence and partial structural analysis of tryptic peptides from the citraconylated protein.

Nineteen tryptic peptides produced by cleavage at 18 of the 20 arginyl residues in citraconylated S-carboxymethylcysteinyl-rhodanese have been isolated by a combination of gel filtration and high voltage paper electrophoresis. These Tc fragments account for all of the 293 residues in the parent polypeptide and their partial or complete sequences have been determined by automated and manual Edman degradation. In some cases, sequence analyses were completed by degradation of peptides derived by secondary cleavages of the decitraconylated Tc fragments with trypsin, chymotrypsin, or the protease from Staphylococcus aureus. Automated Edman degradation of intact S-carboxymethylcysteinyl-rhodanese was performed for 60 cycles; the information thus obtained permitted the alignment of seven of the Tc fragments and gave the sequence of the first 79 residues in the polypeptide chain. The Tc peptide at the COOH terminus of rhodanese was placed by virtue of the fact that it contained no arginine. Structural analysis of the Tc peptides provided the sequences surrounding all five of the methionyl residues in the enzyme. One of the methionines was found in a 19-residue Tc fragment which also contained the cysteinyl residue essential for catalysis.

Amino Acid Sequence↗
PubMed1978

The covalent structure of bovine liver rhodanese. Isolation and partial structural analysis of cyanogen bromide fragements and the complete sequence of the enzyme.

Cyanogen bromide fragments from reduced and carboxymethylated rhodanese have been isolated by gel filtration and ion exchange chromatography on columns of Sephadex G-50 and sulfoethyl-Sephadex C-25, respectively. Partial or complete structural analysis of these fragments has permitted the ordering in sequence of all eleven of the nonaligned tryptic peptides from citraconylated, S-carboxymethylcysteinyl-rhodanese and has thus provided the complete covalent structure of the enzyme. Rhodanese is a single polypeptide of 293 residues and the molecule weight calculated from the covalent structural analysis is about 32,900. The cysteinyl residue implicated in the catalytic function of rhodanese is at position 247. In some preparations of the enzyme the NH2-terminal dipeptide Val-His is missing and the sequence begins with the glutamine at position 3. The rhodanese thus obtained contains 291 amino acid residues and possesses full enzymic activity. X-ray crystallographic analysis of rhodanese has shown that the halves of the molecule (Domains I and II) are nearly identical in conformation. Comparative analysis of the sequences in Domains I and II containing residues with conformationally equivalent alpha C atoms has revealed some degree of homology between the halves of the rhodanese polypeptide. Nethertheless, the structural equivalence of the rhodanese domains is reflected much more by their similarity in tertiary structural than by their sequence homology, even when the sequence comparisons are optimized with reference to the crystallographic results.

Amino Acid Sequence↗
PubMed1978

Active site cysteinyl and arginyl residues of rhodanese. A novel formation of disulfide bonds in the active site promoted by phenylglyoxal.

Chemical modification studies of bovine liver rhodanese have underscored important distinctions between free rhodanese and the catalytic intermediate in which the sulfane atom of the sulfur donor is bound covalently to the enzyme (sulfur-rhodanese). Treatment of free rhodanese with near-stoichiometric quantities of either iodoacetate or phenylglyoxal results in the rapid modification of the essential sulfhydryl group of Cys-247 and the consequent inactivation of the enzyme. Analysis of rate data for the iodoacetate reaction showed that the apparent pK of this group is 7.8 in free rhodanese and 6.7 to 7.0 in complexes of the enzyme with analogs of sulfur donor substrates, in agreement with the previous inference from steady state kinetic observations. Inactivation of free rhodanese by phenylglyoxal in the presence of cyanide was shown to be caused by a novel reaction in which disulfide bonds are formed between Cys-247 and either Cys-254 or Cys-263. In contrast to these results with free rhodanese, the sulfur-substituted enzyme is not inactivated by iodoacetate and is only relatively slowly inactivted by treatment with substantial excesses of phenylglyoxal. The loss of enzyme activity in sulfur-rhodanese does not involve cysteinyl residues but can be correlated with the modification of guanidino groups, notably that of Arg-186, the side chain of which may play a role in substrate binding. These chemical modification studies have implications with respect to the chemical mechanism of rhodanese catalysis and the interpretation of the x-ray crystallographic analysis of this enzyme.

Aldehydes↗
PubMed1978

The covalent and tertiary structure of bovine liver rhodanese.

Bovine liver rhodanese is a single polypeptide of 293 amino acids in which the halves of the molecule assume analogous tertiary structures in the absence of substantial sequence homology. The sulphur atom transferred during catalysis is bound in persulphide linkage to Cys-247. Substrate binding seems to involve Arg-186 and Lys-249.

Amino Acid Sequence↗