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Biomedical subjects

W Yuan

Publications and source records attributed to W Yuan.

At least 163 records · Page 9Linked to original sources
PubMed1995

[Clinical study of the tongue reconstruction with the free gracilis myocutanious flap].

From May 1988 to December 1991, 9 cases of the tongue defect were reconstructed with the free gracilis myocutanious flaps to maintain the tongue motive force. The survival rate was 77.8% (7/9). The follow--up period was 18 months to 5 years. The volume of the flaps didn't obviously atrophy. The shapes of tongue reconstructed were chubby. In their function, the electrokinetic appearance was detected after post--operation 6 months by point electrode electromyography (EMG), and with the time being, the action tended to increase. Compared with the free forearm flap, the gracilis myocutanious flap is better in shape and function, and with muscle and nerve. Therefore, the functional reconstruction of the tongue defect relates not only with neurotropism, but also with the character and volume of the flap. It was confirmed by many experiments and clinical studies that the muscle transplanted can be under control of the nerve by motor never reproducing.

Adult↗
PubMed1995

[Palatoplasty of speech disorders and acoustical characteristics].

Some cleft palate patients suffer from disorders of articulation despite early surgical repair of the cleft and improvement in velopharyngeal function. Some of these articulation disorders involve abnormal palatolingual contact. Fifty-one subjects were investigated acoustically as well as management ranged from 8 years to 36 years with a mean age of 20 years and 1 month. Their speech disorders were analyzed and classified into the follows: Chinese glottal stop, pharyngeal stop, pharyngeal fricative, nasality, palatal articulation and lateral articulation. There were more than two kinds of disorder speech in one case.

Adolescent↗
PubMed1994

Induction of P450 3A by ethylbenzene without altering RNA levels.

Rats were treated with a single intraperitoneal injection of ethylbenzene in corn oil and the effects on cytochrome P450 3A-dependent activities, immunoreactive protein levels and RNA levels were examined. Ethylbenzene increased both P450 3A-dependent 2 beta-hydroxylation of testosterone and immunoreactive protein levels. These levels were maximally induced by 24 hr and diminished thereafter. Despite the increase in P450 3A protein, neither P450 3A1 nor P450 3A2 mRNA levels were altered by treatment with the hydrocarbon. These results clearly demonstrate that this P450 isozyme can be induced by either translational activation or stabilization of P450 3A protein and are suggestive of an elevation of P450 3A2 levels.

Animals↗
PubMed1994

Regulation of the cloned L-type cardiac calcium channel by cyclic-AMP-dependent protein kinase.

Hormones can regulate cardiac L-type Ca2+ channels via cAMP-dependent protein kinase (PKA) phosphorylation. However, regulation of the cloned L-type Ca2+ channel has been difficult to demonstrate conclusively. We stably transfected a human embryonic kidney (HEK-293) cell with the cardiac alpha 1 and beta 2 subunits, then examined PKA modulation of the Ca2+ current. Although forskolin did not increase basal Ca2+ current, the PKA inhibitors, H-89 and Rp-cAMPS, could inhibit basal current. We reversed H-89 inhibition with either forskolin or okadaic acid. We conclude that the channel was phosphorylated under basal conditions, and that inhibition of PKA allowed dephosphorylation. These studies demonstrate that reversible PKA regulation of cloned Ca2+ channels can be studied in HEK-293 cells.

Animals↗
PubMed1994

Luteotropic effects of follicle-stimulating hormone (FSH): I. FSH has in vitro luteotropic and synergistic effects with luteinizing hormone and prolactin on progesterone production by hamster luteal cells during pregnancy.

This study was designed to evaluate the in vitro ability of FSH, LH, and prolactin (PRL) to stimulate progesterone (P4) production by enzymatically dispersed CL cells from pregnant hamsters. In light of previous in vivo findings [1], we were especially interested in determining whether FSH is a luteotropin. The CL were collected and pooled on Days 4, 8, 12, and 16 of gestation (Day 1 = sperm-positive vaginal smear). After enzymatic dissociation, combined large and small luteal cells (LC+SC) were incubated in the presence of 10 ng ovine (o) FSH, oLH, and oPRL, alone or in various combinations, for a total of 144 h with the first medium change at 24 h and other changes every 48 h thereafter. FSH and LH alone significantly increased P4 production on Days 4, 8, and 12, while PRL alone increased P4 only on Day 12 (p < 0.05). The combination oFSH+oLH+oPRL significantly stimulated P4 production on Day 4 to a greater extent than the combination of any two hormones (p < 0.05). Ovine FSH+oLH enhanced P4 production on Days 12 and 16 at 48, 96, and 144 h of incubation, to an extent greater than either hormone alone (p < 0.05). When recombinant human FSH (r-hFSH), which is devoid of LH activity, was added (1-100 ng) to dispersed luteal cells from Day 4 pregnant hamsters, a dose-response increase in P4 was evident (p < 0.05); even 1 ng r-hFSH stimulated P4 production at 96 h (p < 0.05). On Day 2 of the cycle, oFSH or oLH, but not oPRL, also significantly stimulated P4 production (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Luteotropic effects of follicle-stimulating hormone (FSH): II. FSH luteinizing hormone, and prolactin effects on second messenger systems in the corpus luteum of the pregnant hamster.

We have recently shown that FSH, LH, and prolactin (PRL)--alone or combined--act as luteotropins when incubated with luteal cells from pregnant hamsters (Yuan and Greenwald, Biol Reprod 1994; 51:43-49). The purpose of the present study was to determine which second messenger systems are affected by these hormones with progesterone (P4) synthesis as the principal endpoint after 4 h of incubation with 100,000 luteal cells. Luteal cells on Days 4, 10, or 12 of pregnancy were incubated with the following reagents: 10 ng of recombinant human FSH (r-hFSH), ovine (o) FSH, oLH, oPRL, forskolin, db-cAMP, protein kinase A inhibitor (PKI), protein kinase C activator (phorbol 12-myristate 13-acetate; PMA), or various combinations of the reagents. Forskolin and db-cAMP each stimulated P4 in a dose-dependent manner, while PKI significantly inhibited forskolin-, r-hFSH-, oFSH-, and oLH-stimulated P4 on Day 4 of pregnancy. PMA (0.001-1.0 microM) did not affect basal P4 on Day 4, 10, or 12 of pregnancy; however, 100 nM PMA inhibited db-cAMP-, forskolin-, oFSH-, and oLH-stimulated P4 synthesis on Days 4 and 12. The antagonistic effects of PMA were reversed in all cases by concurrent incubation with a PKC inhibitor, H-7. On Day 4 of pregnancy, P4 was stimulated by oFSH and oLH with the highest levels observed in medium stimulated by the luteotropic complex of oFSH, oLH, and oPRL. Recombinant hFSH enhanced P4 production in a dose-dependent manner; doses of 10 ng and above resulted in statistically significant differences from the control values (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Ca-dependent facilitation of cardiac Ca current is due to Ca-calmodulin-dependent protein kinase.

Repetitive membrane potential (Em) depolarization from -90 to 0 mV in rabbit and ferret ventricular myocytes induces a facilitation or "staircase" of Ca current (ICa), which is Ca (not Em) dependent and takes several seconds to accumulate and dissipate. That is, ICa at the tenth pulse at 1-2 Hz exceeds that at the first pulse (I10 > I1). The ICa staircase was completely abolished by dialysis with either of two inhibitory peptides of Ca-calmodulin-dependent protein kinase (CaMKII) CaMKII(290-309) and CaMKII(273-302)], implicating this kinase. Inclusion of ATP gamma S in the patch pipette gradually increased ICa but also abolished the staircase implicating phosphorylation. KN-62, a nonpeptide CaMKII inhibitor, reversed the ICa staircase (I1 > I10). However, this effect of KN-62 was largely attributed to a slower recovery from inactivation and a gating shift to more negative Em (not seen with CaMKII peptides). Similar results were obtained with H-89 and staurosporine (inhibitors of adenosine 3',5'-cyclic monophosphate and phospholipid-/Ca-dependent protein kinase, respectively). The reversal of the ICa staircase with H-89 and KN-62 could be prevented by more negative interpulse Em or elevation of extracellular [Ca] (which could counteract changes in channel gating due to a reduction in internal negative surface potential). That is, these kinase inhibitors might decrease phosphorylation at the inner membrane surface. In approximately 30% of the cells studied with H-89 and staurosporine the characteristic kinetic difference in ICa inactivation (faster at I1 than I10) was also diminished. This might be due to a relatively nonspecific inhibition of the same protein kinase inhibited by the CaMKII peptides. We conclude that the Ca-dependent ICa facilitation is due to activation of CaMKII and phosphorylation of a site on or near the Ca channel. KN-62, H-89, and staurosporine shifted ICa gating to more negative potentials and slowed recovery from inactivation, effects that could be due to reduction in phosphorylation at the inner membrane surface. Thus the reversal of the ICa staircase by KN-62, H-89, and staurosporine may not be Ca channel specific.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Development of selective tight-binding inhibitors of leukotriene A4 hydrolase.

Leukotriene A4 hydrolase is a zinc-containing enzyme which exhibits both epoxide hydrolase and aminopeptidase activities. Since the enzyme product leukotriene B4 is an inflammatory mediator, it is of interest to develop selective inhibitors of leukotriene A4 hydrolase as potential antiinflammatory agents and as mechanistic probes. A systematic study on the enzyme specificity and the inhibition of its amidase activity with more than 30 synthetic inhibitors has led to the development of an alpha-keto-beta-amino ester (26) and a thioamine (27) as tight-binding, competitive type transition-state analog inhibitors of the aminopeptidase activity, with Ki values of 46 and 18 nM, respectively. Both compounds also inhibit the epoxide hydrolase activity, with the IC50 values of 1 microM and 0.1 microM for 26 and 27, respectively.

Amino Acids↗
PubMed1993

Analysis of multivariate parallel-line bioassay with composite responses and composite doses, using canonical correlations.

The use of a composite response to estimate the relative potency in a multivariate parallel-line bioassay is described by Finney. Occasionally a multivariate bioassay has multiple drugs also. Such a situation arises, for example, when a treatment contains several drugs. A procedure for combining multiple responses and combining multiple drugs is proposed in this paper, in order to obtain point and interval estimates of the relative potency. A composite response and a composite dose level for this purpose are obtained by using canonical analysis.

Biological Assay↗
PubMed1993

A mutational hot spot induced by N-hydroxy-aminofluorene in dihydrofolate reductase mutants of Chinese hamster ovary cells.

Eighteen mutants deficient in dihydrofolate reductase (DHFR) activity were induced with 0.5 microM N-hydroxy-aminofluorene in four separate experiments. This carcinogen dose killed approximately 80% of the treated cells and resulted in a mutational frequency approximately 3 x 10(-6). The nature of the induced changes in each of the mutants was determined by direct sequencing following polymerase chain reaction amplification, or in one instance, by Southern blot analysis. Nearly all (15/17) of the mutations were single base changes. Consistent with the binding specificity of this chemical, all mutations were targeted to guanine bases. The predominant change was G:C-->T:A transversion which was evident in 11/15 mutants. A single dG-AF mutational hotspot was noted at a site in the DHFR coding sequence of exon 4; one-third of the induced point mutations arose at this position. These results are compared with our previous analyses of mutants induced with the related aromatic amine, N-2-acetoxy-2-acetyl-aminofluorene.

Acetoxyacetylaminofluorene↗
PubMed1993

Responsiveness of porcine large and small luteal cells to luteotropic or luteolytic hormones and cell morphologic changes during the estrous cycle and pregnancy.

Isolated porcine luteal cells from d 10 and 15 of the estrous cycle (estrus = d 0) were incubated with or without combinations of FSH (0, 10, 10(2), 10(3) ng), LH (0, 10, 10(3) ng), oxytocin, or prostaglandin F2 alpha (PGF2 alpha) (each at 0, 10, 10(3), and 10(5) pg). Progesterone (P4) content was determined after overnight incubation (0 h) then at 2 and 24 h of incubation. The basal (0 h) P4 production of large cells (LC) from d 10 corpora lutea (CL) was 31-fold higher than that by small cells (SC) at 0 h. The LC and SC from d 10 but not those from d 15, were stimulated to a small extent by LH (P < .05). The FSH inhibited P4 production (P < .05) by SC at 24 h on d 10 and by LC after 2 or 24 h of incubation on d 15. There was no interaction between LH and FSH on P4 production. Oxytocin and PGF2 alpha decreased P4 production by d 15 LC at 2 h of incubation (P < .05) and by d 15 SC after 2 or 24 h of incubation (P < .05 and P < .01). The morphology of cells from CL of the cycle or early or mid pregnancy were examined using scanning and transmission electron microscopy (EM). Freshly isolated LC (using scanning EM) from d 10 contained many microvilli arranged in apparent networks on their membranes, but SC had smooth surfaces and contained only a few microvilli. Internally, LC had more small mitochondria than did SC and a different organization of smooth endoplasmic reticulum (SER). The SC from CL of pregnant (d 30 to 60) gilts contained more mitochondria than SC from CL of cyclic gilts. The results indicate that FSH, oxytocin, and PGF2 alpha can have a direct cellular luteolytic effect in the late luteal phase in pigs. The FSH influenced LC, whereas oxytocin and PGF2 alpha effected a more pronounced decrease in P4 from SC. The lower amount of P4 produced overall by SC may be associated with fewer microvilli, mitochondria, and SER in SC.

Animals↗
PubMed1993

Extended Kalman filter (EKF) application in vitamin C two-step fermentation process.

Based on kinetic model study of vitamin C two-step fermentation, the extended Kalman filter (EKF) theory is conducted for studying the process which is disturbed by white noise to some extent caused by the model, the fermentation system and operation fluctuation. EKF shows that calculated results from estimated process parameters agree with the experimental results considerably better than model prediction without using estimated parameters. Parameter analysis gives a better understanding of the kinetics and provides a basis for state estimation and state prediction.

Ascorbic Acid↗
PubMed1993

[Changes in renal cortical thromboxane A2, prostaglandin F1 alpha and effects of dazoxiben, chuan xiong on in situ immune complex glomerulonephritis in rats].

We investigated the relation between the changes of TXA2-PG1 alpha balance and glomerular injury, and the effects of Dazoxiben, Chuan Xiong on in situ immune complex glomerulonephritis (ISICGN) produecd by C-BSA in rats. After two weeks of immunization, the level of renal cortical TXB2 and urine protein was increased, while that of 6-keto-PGF1 alpha was decreased. Four weeks later, the changes as mentioned above were more significant, and platelet aggregation revealed an increase of maximal aggregation. Positive correlation was seen between urine protein and renal cortical TXA2, and negative correlation between urine protein and 6-keto-PGF1 alpha. Histological examination showed morphological changes. Two treated-groups showed significant reduction of urine protein and renal cortical TXB2, but increase of 6-keto-PGF1 alpha. Besides the changes like worm-eaten in electron-dense deposits, foot process fusion disappeared. The thickened GBM and mesangial proliferation were lessened, especially in Dazoxiben group. These results suggests that there is a TXA2-PG1 alpha imbalance in ISICGN, and TXA2 plays an important pathogenetic role in the onset and progression of glomerulonephritis. Dazoxiben and Chuan Xiong might improve TXA2-PG1 alpha imbalance and attenuate glomerular injury to some extent in ISICGN.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Studies on kinetic model of vitamin C two-step fermentation process.

This paper aims at analyzing the bioconversion process from L-sorbose to 2-Keto-L-gulonic acid with the aid of the growth factor assumption. Fermentation mechanism is discussed after making necessary simplifications. A model is established for this second step fermentation process. Nonlinear optimization together with Runge-Kutta method, are used to obtain model parameters. Results of computer simulation agree with experimental data to show the reliability of the kinetic model.

Ascorbic Acid↗
PubMed1992

[Clinical and experimental study of xiao er ke cuan ling oral liquid in the treatment of infantile bronchopneumonia].

UNLABELLED: Xiao Er Ke Chuan Ling Oral Liquid (KCL) is a Chinese herbal preparation consisted of 10 herbs such as Prunus armeniacae, Scutelaria baicalensis, Lonicera japonica etc. 30 children suffering from bronchopneumonia and/or acute bronchitis were treated with KCL (treated group) and another 30 cases were treated with penicillin and aminophylline (control group). RESULTS: cure rate and effective rate in treated group was 26.6%, and 93.3% respectively. While in control group was 30% and 96.6% respectively. No significant differences were seen between them(P > 0.05). The pharmacodynamic experiment showed KCL had potent pharmacological action. The experiment on tracheal fragment of Guinea pig in vitro showed it caused moderately strong smooth muscle relaxation, through inhibition the effect of histamine and acetylcholine. Asthma induction experiment of Guinea pig in vivo showed KCL could significantly prolong the latent period of asthma and alleviate asthmatic symptom. Ammonium water cough induction experiment in mice showed it may apparently prolong cough latent period and reduce times of cough relapse and alleviate cough symptom. KCL had potent antipyretic effect on fever model induced by triple vaccine in rabbits. Bacteriostatic and antiviral experiment in vitro showed the drug had quite strong inhibitory effects for Streptococcus hemolyticus, Staphylococcus aureus, Flexners Dysentery bacillus, Diplococcus pneumoniae and Pseudomonas aeruginosa, and it could potently inhibit the respiratory syncytial virus. KCL is an effective drug in treating bronchopneumonia and acute bronchitis.

Animals↗
PubMed1991

Phosphonate-phospholipid analogues inhibit human phospholipase A2.

A phosphonate-containing phospholipid (PL) analogue (Compound 1) designed as a transition-state inhibitor competively inhibits non-human extracellular PLA2 at a mole fraction of 0.003 in the kinetic "scooting mode" (Jain et al., Biochem 28:4135 (1989]. To further profile the activity of Compound 1, we examined its activity with purified human enzyme and in whole cell systems. Compound 1 effectively inhibited a 14 kDa human PLA2 purified from joint synovial fluid of patients with rheumatoid arthritis using 3H-AA labeled E. coli as substrate (IC50 = 1.7 microM) and a high MW PLA2 (110 kDa) isolated from the cytosol of a human monocytic cell line, U-937, which selectively hydrolyzes AA-containing PL (IC50 = 165 microM). It failed to reduce A23187-induced PGE2 or LTC4 production by human adherent monocytes or LTB4 release from human neutrophils which may be due, in part, to poor membrane partitioning.

Arthritis, Rheumatoid↗
PubMed1990

Interfacial catalysis: the mechanism of phospholipase A2.

A chemical description of the action of phospholipase A2 (PLA2) can now be inferred with confidence from three high-resolution x-ray crystal structures. The first is the structure of the PLA2 from the venom of the Chinese cobra (Naja naja atra) in a complex with a phosphonate transition-state analogue. This enzyme is typical of a large, well-studied homologous family of PLA2S. The second is a similar complex with the evolutionarily distant bee-venom PLA2. The third structure is the uninhibited PLA2 from Chinese cobra venom. Despite the different molecular architectures of the cobra and bee-venom PLA2s, the transition-state analogue interacts in a nearly identical way with the catalytic machinery of both enzymes. The disposition of the fatty-acid side chains suggests a common access route of the substrate from its position in the lipid aggregate to its productive interaction with the active site. Comparison of the cobra-venom complex with the uninhibited enzyme indicates that optimal binding and catalysis at the lipid-water interface is due to facilitated substrate diffusion from the interfacial binding surface to the catalytic site rather than an allosteric change in the enzyme's structure. However, a second bound calcium ion changes its position upon the binding of the transition-state analogue, suggesting a mechanism for augmenting the critical electrophile.

Bee Venoms↗