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Biomedical subjects

D C Zhang

Publications and source records attributed to D C Zhang.

At least 19 recordsLinked to original sources
PubMed2006

Determination of microstickies in recycled whitewater by headspace gas chromatography.

This study proposed a novel headspace gas chromatographic (HS-GC) method for determination of adhesive contaminants (microstickies) in recycled whitewater, a fiber containing process stream, in the paper mill. It is based on the adsorption behavior of toluene (as a tracer) on the hydrophobic surface of microstickies, which affects the apparent vapor-liquid equilibration partitioning of toluene. It was found that the equilibrium concentration of toluene in the vapor phase is inversely proportional to the apparent effective surface area of microstickies that remain in the corresponding solution. Thus, the amount of microsticky materials in the recycled whitewater can be quantified by HS-GC via indirect measurement of the toluene content in the vapor phase of the sample without any pretreatment. The presented method is simple, rapid and automated.

Adhesives↗
PubMed2001

Dantaxusins A and B, two new taxoids from Taxus yunnanensis.

Two new taxane diterpenes, dantaxusin A [5 alpha-cinnamoyloxy-2 alpha,7 beta,13 alpha-triacetoxy-2(3-->20)abeo-taxa-4(20),11-diene-9,10-dione (1)] and dantaxusin B [5 alpha-cinnamoyloxy-9 alpha-hydroxy-10 beta,13 alpha-diacetoxytaxa-4(20),11-diene (2)], were isolated from an ethanol extract of the aerial parts of Taxus yunnanensis along with taxuspine B, 2-deacetoxytaxinine J, taxuyunnanine C, taxinine B, taxuspine C, and taxinine NN-4. The structures of 1 and 2 were established on the basis of 1D and 2D NMR and HRMS spectroscopic methods.

China↗
PubMed2000

Cytotoxity of non-alkaloidal taxane diterpenes from Taxus chinensis against a paclitaxel-resistant cell line.

Seven taxane diterpenes were isolated from the EtOH extract of the aerial parts of Taxus chinensis, and evaluated for cytotoxicity against nine human cell lines, including a beta-tublin mutant resistant to paclitaxel. Compound 2, a non-alkaloid-type taxane diterpene, showed significant cytotoxicity in most cell lines, and notably, equipotent against both parental and beta-tublin mutant tumor cell lines.

Cell Survival↗
PubMed2000

[Surgical treatment for mitral valve prolapse].

OBJECTIVE: To determine the excellent operative procedure to treat mitral valve prolapse (MVP). METHODS: Fifty seven patients with MVP were divided into three groups: Group I received traditional chordal reconstruction; Group II underwent chordal replacement using expanded polytetrafluorethylene(e-PTFE) sutures and artificial ring valvuloplasty reconstruction; Group III submitted mitral valve replacement. RESULTS: Mitral regurgitation volume was reduced significantly in Group II [(1.3 +/- 3.8) ml] and Group III [(1.2 +/- 3.4) ml] than that in Group I [(4.7 +/- 7.7) ml] (P < 0.05). CONCLUSION: The utilization of e-PTFE sutures as artificial chordae and artificial ring valvuloplasty for MVP is a more reliable and safe procedure than traditional mitral valve reconstruction, and can avoid the complications of long term anticoagulant therapy after mechanical valve replacement.

Adolescent↗
PubMed1997

[Studies on sultamicillin hydrolysis].

Sultamicillin is an oral mutual pro-drug composed of double esters of formaldehyde hydrate in which one of the hydroxyl groups is esterified with ampicillin and the other with sulbactam. It is hydrolyzed fast in neutral or weakly alkaline condition. When hydrolyzed, it forms ampicillin and hydroxylmethyl sulbactam or sulbactam and hydroxylmethyl ampicillin by different routes. Usually, the former has priority as the two ester bonds have different activities. The ratio of ampicillin to sulbactam in the products is about 3:1. Both the hydroxylmethyl sulbactam and the hydroxylmethyl ampicillin can be further catalyzed by esterase to produce formaldehyde.

Ampicillin↗
PubMed1995

The isolation and structural elucidation of three new neolignans, piperulins [corrected] A, B, and C, as platelet activating factor receptor antagonists from Piper puberulum.

Three new neolignans, piperulins [corrected] A [1], B [2], and C [3], were isolated from Piper puberulum. Their structures and relative stereochemistries were determined from spectral data and the X-ray crystallographic analysis of 1. Compounds 1 and 3 inhibit specific platelet activating factor receptor binding with IC50 values of 7.3 and 5.7 microM, respectively.

Animals↗
PubMed1994

Inhibition of IL-1 release from human monocytes and suppression of streptococcal cell wall and adjuvant-induced arthritis in rats by an extract of Tripterygium wilfordii Hook.

1. It was investigated whether an extract of Tripterygium wilfordii Hook f (TW) inhibits IL-1 production by monocytes and suppresses the development of IL-1-dependent arthritis induced in rats with streptococcal cell wall and adjuvant. 2. TW preferentially inhibited IL-1 alpha and IL-1 beta production by bacterial lipopolysaccharide (LPS)-stimulated human monocytes with IC50 of approximately 1 microgram/ml. 3. Oral administration of TW dose-dependently suppressed joint swelling and structural damage in streptococcal cell wall-induced arthritis (ED50 = 20 mg/kg/day) and in adjuvant-induced arthritis (ED50 = 46 mg/kg/day for developing and 8 mg/kg/day for established arthritis).

Animals↗
PubMed1994

Antitumor agents--CLI. Bis(helenalinyl)glutarate and bis(isoalantodiol-B)glutarate, potent inhibitors of human DNA topoisomerase II.

Evaluation of a number of cytotoxic antitumor sesquiterpene lactones and their derivatives has led to the discovery of bis(helenalinyl)glutarate (4) and bis(isoalantodiol-B)glutarate (10) as potent inhibitors of human-derived topoisomerase II. Unlike etoposide, which inhibits by preventing the DNA rejoining process, compounds 4 and 10 inhibit topoisomerase II without causing DNA breakage. The structure-activity relationships of 4, 10, and related compounds are discussed.

Cell Line↗
PubMed1993

The sartorius myocutaneous island flap.

The vascular supply to the distal part of sartorius m. was studied in 37 limbs by dissection under magnification and after black ink and latex injections. The muscle or myocutaneous island flap pedicled on the saphenous artery (SA) is supplied by a retrograde circulation through anastomoses of the SA with the perforating branches of the posterior tibial artery and the medial inferior genicular artery. Three different vascular patterns were defined. Retrograde injection also showed good perfusion of the SA. The flap is useful for covering around the knee, the proximal and middle thirds of the lower leg, and the end of the amputation stump. Raising of the flap has not resulted in any functional or cosmetic defect. Eighteen operations have so far been performed, six using the muscle island flap and twelve using the myocutaneous island flap, and all survived completely.

Humans↗
PubMed1993

Antitumor agents, 145. Cytotoxic asprellic acids A and C and asprellic acid B. new p-coumaroyl triterpenes, from Ilex asprella.

Three new p-coumaroyl triterpenes, asprellic acids A [1], B [2], and C [3], were isolated from the EtOH extract of dried leaves of Ilex asprella. The structures for 1-3 have been established as 3,27-di-O-trans-p-coumaroyl [1], 3-O-trans-p-coumaroyl-27-O-cis-p-coumaroyl- [2], and 3-O-cis-p-coumaroyl-27-O-trans-p-coumaroyl- [3] 3 beta,27-dihydroxyolean-12-en-28-oic acid, respectively, by spectral and chemical examinations. Asprellic acid A [1] exhibited potent cytotoxicity against the RPMI-7951 cell line with an ED50 value of 0.62 micrograms/ml, while the cytotoxicity of asprellic acid C [3] against RPMI-7951 was marginal (ED50 5.5 micrograms/ml). Compounds 1 and 3 also showed cytotoxicity against KB cells with ED50 values of 3.75 and 2.86 micrograms/ml, respectively. Asprellic acid B [2] did not show cytotoxicity (> 10 micrograms/ml) against KB or RPMI-7951 cell lines.

Adenocarcinoma↗
PubMed1993

Yuanhuacin A is a selective antagonist of phorbol ester receptor in protein kinase C.

Protein kinase C with a molecular weight of 82 kD has been purified to electrophoresis homogeneous from rat brain through a series of chromatography columns including DE-52, Sepharose G-200 and phenyl-Sepharose. The enzyme possessed autophosphorylation activity. Yuanhuacin A inhibited the 3H-phorbol-12, 13-dibutyrate (3H-PdBu) binding of PKC with an IC50 value of 1.48 +/- 0.28 x 10(-8) mol/L when the concentration of 3H-PdBu was 1.5 x 10(-9) mol/L (Ki = 1.2 x 10(-8) mol/L). Yuanhuacin A inhibited the PdBu-stimulated PKC activity in the catalysis of the phosphorylation of Histone III-S with an IC50 of 2.82 +/- 0.37 x 10(-9) mol/L (PdBu = 10(-6) mol/L), while it had no effect on the basal and Ca(2+)-stimulated PKC activity in the same assay system. This result suggests that Yuanhuacin A is a selective antagonist of the phorbol ester receptor in protein kinase C.

Animals↗
PubMed1992

Anti-AIDS agents, 4. Tripterifordin, a novel anti-HIV principle from Tripterygium wilfordii: isolation and structural elucidation.

A new kaurane-type diterpene lactone, tripterifordin [1], has been isolated from the roots of Tripterygium wilfordii. The structure of 1 was elucidated by spectroscopic methods, including the concerted application of a number of 2D nmr techniques that involved the 1H-1H COSY, heteronucleus-detected variants of the heteronuclear chemical shift correlation (HETCOR), phase-sensitive NOESY, and long-range HETCOR. Compound 1 shows anti-HIV replication activity in H9 lymphocyte cells with an EC50 of 1 microgram/ml.

Antiviral Agents↗
PubMed1992

Anti-aids agents, 6. Salaspermic acid, an anti-HIV principle from Tripterygium wilfordii, and the structure-activity correlation with its related compounds.

Salaspermic acid [1], an inhibitor of HIV reverse transcriptase and HIV replication in H9 lymphocyte cells, was isolated from the roots of Tripterygium wilfordii for the first time. The structure of 1 derived from spectral data was established unequivocally by an X-ray analysis of crystals of the monohydrate. A structure-activity correlation of 1 with ten related compounds indicated that the acetal linkage in ring A and the carboxyl group in ring E of 1 may be required for the anti-HIV activity.

Antiviral Agents↗
PubMed1991

[Hassab's procedure with or without lower esophageal transection in the treatment of portal hypertension. A prospective controlled study].

Seventy-three patients of portal hypertension were treated with Hassab's procedure or the procedure combined with lower esophageal transection during 1982-1986. All were followed up to 25-74 months (average of 48.8 months). The results revealed that Hassab's procedure was effective in maintaining hepatic function, no encephalopathy, good quality of life (excellent and fair in 83.3%). low incidence of upper GI rebleeding within two years after operation (3.1%), and easy manipulation. However, the accumulated late rebleeding rate was rather high (18.8%). The long-term results of combined procedure, including rebleeding rate, was no significantly difference from those of the simple Hassab's procedure, and the early postoperative serious complications were more frequently seen in patients receiving combined procedure than in those receiving Hassab's procedure.

Adolescent↗
PubMed1989

Impedance cardiography-dipyridamole test in detecting coronary artery disease.

Thallium-201 dipyridamole test (Tl-201DT) has high sensitivity and specificity in the assessment of coronary disease (CAD), but is not always available. We proposed impedance cardiography DT (IDT)instead. To determine the characteristic changes of impedance cardiogram (ICG) in patients with typical angina and to compare with those in normal subjects, 37 subjects undergoing IDT were divided into 3 groups: typical angina (15), suspected chest pain (11) and normals (11). Dipyridamole (DP) was infused intravenously for over 10 minutes at a total dose of 0.75 mg/kg. Simultaneous recording of ECG, PCG, and ICG were repeated immediately 2 minutes and 4 minutes after infusion of DP, and immediately and 5 minutes after intravenous infusion of aminophylline. Eleven parameters, HR, SPRP, QZ/ZA2, HI, SV, CO, A wave, A/C, O wave, O/C, A + O/C were observed. Only in O/C and A + O/C there were changes of significant differences (P less than 0.01) between groups. Specificity was 100% (0/11 positive) in normals. Sensitivity was 80% (12/15 positive) in the angina group, but only 46.7% (7/15) with ECG. The characteristic changes in CAD patients during IDT were angina induced by DP, abnormal O wave on ICG and change from deep A wave to abnormal O wave. No serious complication occurred after IDT. Our results indicate that IDT is a simple, practical and valuable method for detecting CAD.

Cardiography, Impedance↗