Search PubMed⌕ Search

Biomedical subjects

C L Wang

Publications and source records attributed to C L Wang.

At least 145 records · Page 8Linked to original sources
PubMed1992

[Exudative retinal detachment in the pregnancy-induced hypertension syndrome].

22 cases of pregnancy-induced hypertension syndrome with exudative retinal detachment were studied. Fluorescein angiography performed in 5 patients 7-14 days post-parturition revealed choroidal circulatory disturbances and retinal pigment epithelial damages, while the retinal capillaries also showed damages of varying degrees. The authors regarded the former as the primary pathological basis for the retinal detachment, with the latter also playing a pathogenic role. The incidence and the source of fluid of the retinal detachment in relation to general edema, proteinuria, and hypertension were discussed.

Adult↗
PubMed1991

A calmodulin-binding peptide of caldesmon.

Caldesmon is a major actin-binding protein identified in smooth muscle and many non-muscle cells. It also interacts with calmodulin and a number of other acidic proteins. We have shown previously that the polypeptide stretch from Val629 to Ser666 near the C terminus contains a calmodulin binding site (Wang, C.-L. A., Wang, L.-W. C., Xu, S., Lu, R. C., Saavedra-Alanis, V., and Bryan, J. (1991) J. Biol. Chem. 266, 9166-9172). On the other hand, Bartegi et al. (Bartegi, A., Fattoum, A., Derancourt, J., and Kassab, R. (1990) J. Biol. Chem. 265, 15231-15238) reported a cyanogen bromide fragment beginning at Trp659 which is also capable of binding both calmodulin and actin. A comparison of the overlapping sequence between these two peptides suggests that this calmodulin binding site is localized in a 7-residue segment, 659Trp-Glu-Lys-Gly-Asn-Val-Phe665. We have chemically synthesized an 18-residue peptide (GS17C, from Gly651 to Ser667 with an added cysteine at the C terminus) that contains this segment. This peptide was purified by high performance liquid chromatography and labeled with fluorescent probes at the terminal cysteine residue. We found that GS17C indeed binds calmodulin in a Ca(2+)-dependent manner (Kd = 8 x 10(-7) M) and appears to compete with caldesmon. Interestingly, this synthetic peptide also co-sediments with F-actin, binding to actin being displaceable by calmodulin, as in the case of the native caldesmon. But GS17C does not have any effect on the actomyosin ATPase activity, indicating that this peptide segment does not contain the inhibitory region.

Actins↗
PubMed1991

A long helix from the central region of smooth muscle caldesmon.

The central region of smooth muscle caldesmon is predicted to form alpha-helices on the basis of its primary structure. We have isolated a fragment (CT54) that contains this region. The hydrodynamic properties and the electron microscopic images suggest that CT54 is an elongated (35 nm), monomeric molecule. The circular dichroic spectrum yields an overall alpha-helical content of 55-58%. These results are consistent with the model that the middle portion of CT54 forms a long stretch of single-stranded alpha-helix. Such a structure, if it in fact exists, is thought to be stabilized by numerous salt bridges between charged residues at positions i and i + 4. The structural characteristics of this fragment not only represent an unusual protein configuration but also provide information about the functional role of caldesmon in smooth muscle contraction.

Amino Acid Sequence↗
PubMed1991

Localization of the calmodulin- and the actin-binding sites of caldesmon.

Expression of the C-terminal third of chicken gizzard caldesmon in Escherichia coli, using the Nagai vector (Nagai, K., and Thøgersen, H.V. (1987) Methods Enzmol. 153, 461-481), produces a cII-caldesmon fusion protein (27 kDa) with caldesmon sequence beginning at Lys579. Degradation during purification yields five peptides with molecular masses of 24, 22, 19 (two peptides), and 15 kDa. The 24-kDa peptide begins at Phe581; the 22-kDa peptide begins at Leu597, the two 19-kDa peptides begin at Phe581 and Val629, respectively; the 15-kDa peptide also begins at Val629. We estimate that the 15-kDa and one of the 19-kDa peptides end near Leu710. Site-directed mutagenesis was used to produce truncated peptides with known C termini; one peptide (17 kDa) terminates at Asn675. Digestion of the fragments with chymotrypsin generates a second 15-kDa fragment that begins at Ser666 (15K'). All of the peptides, with the exception of 15K', bind Ca(2+)-calmodulin-Sepharose and share a common 37-amino acid peptide between Val629 and Ser666, suggesting this contains the calmodulin binding site. Comparison with published sequences (Takagi, T., Yazawa, M., Ueno, T., Suzuki, S., and Yagi, K. (1989) J. Biochem. (Tokyo) 106, 778-783 and Bartegi, A., Fattoum, A., Derancourt, J., and Kassab, R. (1990) J. Biol. Chem. 265, 15231-15238) for other calmodulin-binding fragments further restricts the binding site to 7 residues, Trp-Glu-Lys-Gly-Asn-Val-Phe, between Trp659 and Ser666. All of the fragments, except the two 15-kDa peptides, co-sediment with F-actin, indicating that there are two segments in the C-terminal third of caldesmon that can interact with F-actin: one between Leu597 and Val629, the other between Arg711 and Pro756. Although separated in the primary sequence, these domains may interact with the calmodulin-binding region in the folded structure.

Actins↗
PubMed1991

Electron microscopic studies of chicken gizzard caldesmon and its complex with calmodulin.

Caldesmon samples mounted on a stage rotating about a horizontal axis were shadowed keeping the shadow angle at about 3 degrees. This technique minimizes background metal deposits compared with the conventional method. The identity of caldesmon was confirmed by comparing the images of caldesmon alone with those of the caldesmon-calmodulin complex. In these samples the caldesmon molecules appeared to be elongated; most were between 30 and 80 nm in length. The maximum length was in good agreement with the earlier estimate of 74 nm based on hydrodynamic studies. Our observations also suggested the presence of a rather rigid 30-40 nm stretch in the middle of the caldesmon molecule, which was always visible under rotary shadowing, and a flexible structure of about 20 nm in length at each end of the molecule, which may or may not be visible depending on their orientation on the mica surface. In the samples of caldesmon crosslinked with calmodulin, we noticed the existence of complexes containing two calmodulin molecules per caldesmon molecule, separated by a distance of 60 nm, consistent with the suggestion that each end of caldesmon can interact with calmodulin.

Animals↗
PubMed1991

Ewing's sarcoma: metastatic tumor to the jaw.

Metastatic tumors to the jaw are a rare occurrence. The incidence of metastatic Ewing's sarcoma to the jaw has been reported to be less than 2% of all cases of Ewing's sarcoma. Early detection of such lesions is difficult because the signs and symptoms do not appear until the lesion has progressed considerably. The treatment options are therefore limited to palliative care of the patient rather than cure. This article reports a case of Ewing's sarcoma that had metastasized to the mandible and reviews the literature.

Carboplatin↗
PubMed1991

Evaluation of 110 consecutive patients with dementias: a prospective study.

We prospectively investigated 131 consecutive cases (both in- and outpatients) of suspected dementia to evaluate the relative frequency of different types of dementia in Chinese patients. Dementia was confirmed in 110 cases (84.0%). In contrast to the Western series, vascular dementia (39.1%) was slightly more frequent than the Alzheimer's disease (36.4%). Twelve cases (10.9%) of potentially treatable dementia were found. Careful clinical observation was the most useful part of the evaluation. CT scan of brain was the most useful laboratory test.

Aged↗
PubMed1991

Four-year experience in the treatment of upper gastrointestinal strictures with balloon dilatation.

One hundred and sixty-four cases of upper gastrointestinal tract stricture were treated by balloon dilatation in 4 years. A total of 682 procedures were performed. One hundred and forty cases (anastomosis stenosis 95, caustic stenosis 33 and other stenoses of the esophagus 12) were followed up with an effective rate of 90% (126/140) and a long-term effective rate of 71.4% (100/140). Fourteen cases (10%) failed, and 11 of them were due to tumor recurrence. The concept about the short-term and long-term effects, the criteria for evaluation of the results, the factors influencing the effectiveness, and the time suitable for dilatation are described. For the dilatation, indications are anastomosis stricture of the upper gastrointestinal tract, esophageal web and caustic stenosis of the esophagus. This method is also indicated for cicatricial stricture of the upper gastrointestinal tract of various causes.

Adolescent↗
PubMed1991

[Changes in parameters of hemorheology and circulation 6-keto-PGF1 alpha and TXB2 in dilated cardiomyopathy].

The changes in 12 parameters of hemorheology were observed and the levels of peripheral plasma 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TXB2) measured in 35 cases of dilated cardiomyopathy (DCM), including 6 peripartum cardiomyopathy (PCM). We found that there is of hyperviscosity in DCM, the causes were decrease of erythrocyte deformability, increase of red blood cell aggregation, increase of plasma fibrinogen and TXA2 level and decrease of plasma 6-keto-PGF1 alpha level.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

[Evaluation of administrative practices for the registration of outpatients with pulmonary tuberculosis].

In this paper, the register state, regular therapy rate and sputum conversion rate for outpatients have been analysed. 30.5% of outpatients from other region were not registered. In these patients, regular therapy rate and sputum conversion rate were 10.9% and 53.7%, respectively. Comparing with above data, there were 97.3% and 96.8% for above 2 parameters in outpatients of Changhun region, 40.2% and 61.7% in outpatients of other region with register, under the management or control by hospital.

China↗
PubMed1991

[Chemical studies of coumarins from Glycyrrhiza uralensis Fisch].

This paper reports the isolation and identification of eight crystalline substances (I, II, III, IV, V, VI, VII, VIII) from the root of Glycyrrhiza uralensis Fisch. Besides the known compounds liquiritin, hexacosance, beta-sitosterol, licoricone liquiritigenin and etc, a new constituent, named neoglycyrol was obtained by sillica gel and polyamide column chromatographic method. Its chemical structure was elucidated by means of chemical and spectrometric analysis (UV, IR, NMR and MS). Neoglycyrol, C21H18O6, yellow needles with mp 263.5-265 degrees C, possesses one methoxyl, one isopentenyl and two hydroxyls. Its diacetate derivative is C25H22O8 with mp 202-203.5 degrees C. Its dimethyl ether derivative is C23H22O6 with mp 207-208.5 degrees C. Its structure was found to be VII.

Coumarins↗
PubMed1990

Distance measurements in cardiac troponin C.

Intramolecular distance measurements were made in cardiac troponin C (cTnC) by fluorescence energy transfer using Eu3+ or Tb3+ as energy donors and Nd3+ or an organic chromophore as acceptors. The laser-induced luminescence of bound Eu3+ is quenched in Eu1Nd1cTnC with a lifetime of 0.328 ms, compared with 0.43 ms for Eu2cTnC. The enhanced decay corresponds to an energy transfer efficiency of 0.25, or a distance of 1.1 nm between the two high affinity sites. We have also labeled cTnC with 4-dimethylaminophenylazophenyl-4'-maleimide (DAB-Mal) at the two cysteine residues (Cys-35 and Cys-84). Energy transfer measurements were carried out between Tb3+ bound to the high affinity sites and the labels attached to the domain containing the low affinity site. Upon uv irradiation at pH 6.7, Tb1cTnCDAB emits tyrosine-sensitized Tb3+ luminescence that decays bioexponentially with lifetimes of 1.29 and 0.76 ms. The shorter lifetime is ascribed to energy transfer from Tb3+ to the DAB labels, yielding an average distance of 3.4 nm between the donor and the acceptors. At pH 5.0, however, the luminescence decays exclusively with a single lifetime of 1.31 ms, suggesting that under these conditions all Tb3+ ions are more than 5.2 nm away from the label. Thus cTnC, like skeletal TnC, undergoes a pH-dependent conformational transition which converts an elongated structure at lower pH's to a rather compact conformation in a more physiological medium.

Affinity Labels↗
PubMed1990

Antibacterials. Synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 2. The "A" group.

The synthesis and structure-activity relationship (SAR) studies of the effect of varying the "A" group in a series of 5-(acetamidomethyl)oxazolidonone antibacterials (2) are described. Compounds 2 were principally prepared either by the six-step synthesis described previously (J. Med. Chem. 1989, 32, 1673) or by elaboration of the synthetic intermediate 2 (A = H) via electrophilic aromatic substitution or elaboration of the intermediate 2 (A = I) by transition metal catalyzed carbon-carbon bond-forming reactions. Antibacterial evaluation of compounds 2 with A = alkyl, ethenyl, ethynyl, hydroxyalkyl, aldo and keto, oximinoakyl, carboalkoxy, nitro, amino, halo and psi-halo, alkylthio, alkylsulfinyl, and alkysulfonyl against Staphylococcus aureus and Enterococcus faecalis led to the identification of several SAR trends. In several series of homologues (alkyl, ketyl, aximinoalkyl, amino, halo and psi-halo, and alkythio), antibacterial activity increased with increasing lipophilicity. But in series with where A is a substituent with a trior tetrasubstituted (substituent larger than H) quaternary atom attached directly to the aromatic ring (hydroxyalkyl, alkylsulfinyl, alkylsufonyl), the activity peaked at the member of the series with the "tert-butyl" connectivity pattern. Conjugated electron-withdrawing substituents also had increased activity relative to nonconjugated analogues of comparable lipophilicity.

Anti-Bacterial Agents↗
PubMed1990

[Clinical study and immunological observation on potenlini treatment of epidemic hemorrhage fever].

439 cases of epidemic hemorrhagic fever (EHF) in the febrile stage of the disease were randomly divided into two groups. 226 cases in therapeutic group were treated with daily intravenous drip of 60-100 ml potenlini for 3 days. Other measures of treatment in this group was just the same as those in the control group. The results showed that the duration of both the febrile stage and the hypotensive shock stage were shorter and the rate of recovering from hypotensive shock stage and oliguric stage in the therapeutic group (P less than 0.01) was higher as compared with the control group. BUN, ALT, urinary protein, white blood cells and platelets returned to normal level earlier than expected (P less than 0.01). The occurrence rate of complication and case fatality rate in therapeutic group were lower. The research showed that potenlini in the treatment of EHF has effects. But it has not remarkable effects on immune adjustment.

Adolescent↗
PubMed1989

Caldesmon has two calmodulin-binding domains.

Chicken gizzard caldesmon was cleaved with chymotrypsin or CNBr, and the calmodulin-binding fragments were isolated using an affinity column. Limited chymotryptic digestion gives rise to a 38 kDa calmodulin-binding fragment (CT40) as described previously (Szpacenko, A. & Dabrowska, R., FEBS Lett. 202, 182-186, 1986; Fujii, T., Imai, M., Rosenfeld, G. C. & Bryan, J., J. Biol. Chem. 261, 16155-16160, 1987; Yazawa, M., Yagi, K. & Sobue, K., J. Biochem. 102, 1065-1073, 1987). In the case of CNBr cleavage a 37 kDa calmodulin-binding fragment (CB40) was obtained. Both CT40 and CB40 contain a reactive thiol group, but these thiols are apparently in different environments as judged by the responses of attached fluorescent labels to calmodulin-binding. A comparison of the N-terminal sequences of CB40 and CT40 with the complete sequence of caldesmon shows that the two calmodulin-binding fragments in fact originate from different parts of the parent molecule. Thus there exist two calmodulin-binding sites in caldesmon, one in the N-terminal half and the other in the C-terminal half of the molecule. This is consistent with the recent finding that up to two calmodulin molecules can be crosslinked to each caldesmon molecule (Wang, C.-L.A., Biochem. Biophys. Res. Commun., 156, 1033-1038, 1988).

Actins↗
PubMed1989

pH-dependent conformational changes of wheat germ calmodulin.

Fluorescence energy transfer measurements were carried out between landmarks on wheat germ calmodulin to measure the interdomain distance. Tb3+ ions bound at the four Ca2+-binding sites were used as energy donors, and an organic chromophore, [4-(dimethylamino)-phenyl-4'-azophenyl]maleimide, attached to the single cysteine residue at position 27, was used as the acceptor. At pH's near neutrality all bound Tb3+ ions emit luminescence with shortened lifetimes as a result of energy transfer to the acceptor; at pH 5, however, part of the metal emission becomes unquenched. When the protein is subjected to limited digestion with trypsin in the presence of Ca2+, resulting in the formation of two fragments, each corresponding to half of the molecule, the decay of Tb3+ emission is no longer pH sensitive. These results suggest that, like rabbit skeletal troponin C [Wang, C.-L. A., Zhan, Q., Tao, T., & Gergely, J. (1987) J. Biol. Chem. 257, 8372-8375], wheat germ calmodulin exists in a relatively compact conformation at neutral pH's, but becomes more elongated at pH 5.

Binding Sites↗
PubMed1989

Antibacterials. Synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 1. The "B" group.

The synthesis and structure/activity studies of the effect of varying the "B" group in a series of oxazolidinone antibacterials (I) are described. Two synthetic routes were used: (1) alkylation of aniline with glycidol followed by dialkyl carbonate heterocyclization to afford I (A = H, B = OH), whose arene ring was further elaborated by using electrophilic aromatic substitution methodology; (2) cycloaddition of substituted aryl isocyanates with epoxides to give A and B with a variety of values. I with B = OH or Br were converted to other "B" functionalities by using SN2 methodology. Antibacterial evaluation of compounds I with A = acetyl, isopropyl, methylthio, methylsulfinyl, methylsulfonyl, and sulfonamido and a variety of different "B" groups against Staphylococcus aureus and Enterococcus faecalis concluded that the compounds with B = aminoacyl, and particularly acetamido, were the most active of those examined in each A series, possessing MICs in the range of 0.5-4 micrograms/mL for the most active compounds described.

Anti-Bacterial Agents↗