Biomedical subjects

D Zhong

Publications and source records attributed to D Zhong.

64 records · Page 4Linked to original sources

PubMed1994

First epidermal growth factor-like domain of human blood coagulation factor IX is required for its activation by factor VIIa/tissue factor but not by factor XIa.

Factor IX consists of a gamma-carboxyglutamic acid-rich domain followed by two epidermal growth factor (EGF)-like domains and the C-terminal protease domain. To delineate the function of EGF1 domain in factor IX, we constructed three mutants: an EGF1 domain-deleted mutant (IX delta EGF1), a point mutant (IXQ50P) with a Gln-50-->Pro change, and a replacement mutant (IXPCEGF1) in which the EGF1 domain of factor IX was replaced by that of protein C. These mutants and wild-type (WT) factor IX (IXWT) were expressed in 293 kidney cells by using pRc/CMV vector. The purified proteins had the same gamma-carboxyglutamic acid content as the normal plasma factor IX (IXNP) and were activated normally by factor XIa-Ca2+. In contrast, IX delta EGF1 could not be activated by factor VIIa-tissue factor-Ca2+, and the activation of IXPCEGF1 in this system was markedly slow; however, IXQ50P was activated at a normal rate. In additional studies, both IXWT and IX delta EGF1 were rapidly converted to their respective IX alpha forms by factor Xa-phospholipid-Ca2+. Since this reaction has an absolute requirement for phospholipid, it indicates that the mutants under study are not impaired in their interactions with phospholipid. Relative coagulant activities of factor XIa-activated proteins were IXNP, 100%; IXWT, 75-85%; IX delta EGF1, < or = 1%; IXPCEGF1, < or = 2%; and IXQ50P, 6-10%. We conclude that the EGF1 domain of factor IX is required for its activation by factor VIIa-tissue factor and that the Gln-50 residue is not critical for this activation. Further, the EGF1 domain of factor IX is not essential for phospholipid binding and for its activation by factor XIa. In addition, the low coagulant activities of the activated mutants indicate that the EGF1 domain is also important in factor X activation by factor IXa-factor VIIIa-Ca(2+)-phospholipid complex.

1-Carboxyglutamic Acid↗

PubMed1994

[HPLC-determination of loratadine and its active metabolite descarboethoxyloratadine in human plasma].

The quantitative determination of loratadine (1) and its active metabolite descarboethoxyloratadine (2) is described. Because of the high difference in polarity between 1 and 2, the two analytes were determined in two HPLC-systems separately. As internal standards propyl-4-(8-chloro-5,6-dihydro-11H-benzo-[5,6]-cyclohepta-[1,2-b]- pyridin-11-ylidin)-1-piperidincarboxylate (3) and 1-ethyl-4-(8-chloro-5,6-dihydro-11H-benzo-[5,6]-cyclohepta- [1,2-b]-pyridine-11-ylidin)-piperidine (4) were used for 1 and 2, respectively. After extraction with organic solvents from 1 ml plasma, 1 and 2 were reextracted with diluted phosphoric acid from the organic phase. Chromatographic separation on a RP-18 column and fluorescence detection allowed a sufficiently sensitive determination of 1 and 2 in plasma with a lower limit of quantitation of 0.5 ng/ml for both analyts. The method was successfully applied to human plasma samples from 16 subjects after oral administration of 20 mg 1.

Chromatography, High Pressure Liquid↗

PubMed1994

[HPLC determination of diprafenone and its active metabolite 5-hydroxydiprafenone in human plasma].

A simple, specific and sensitive HPLC method is described, which allows the quantitation of diprafenone and its active metabolite 5-hydroxydiprafenone in human plasma. Propafenone is used as internal standard. After extraction by diethyl ether from plasma, the analytes are reextracted with 5% phosphoric acid from the organic phase. Chromatographic separation on a RP-18 column and UV detection (220 nm) allows the sensitive determination of diparafenone and 5-hydroxydiprafenone in plasma with a lower limit of quantitation of 5.0 ng/ml for both substances. The method was successfully applied to human plasma samples from 24 subjects after oral or i.v. administration of 300 mg or 50 mg diprafenon hydrochloride, respectively.

Administration, Oral↗

PubMed1993

A PCR-based method for site-specific domain replacement that does not require restriction recognition sequences.

We describe a PCR-based method for domain replacement that does not require restriction site sequences. We illustrate the technique in which the first epidermal growth factor (EGF1)-like domain of factor IX (FIX) is replaced by the EGF1-like domain of protein C. The method employs four oligonucleotide primers. Two are external primers (forward primer A and inverse primer B) and contain sequences flanking the FIX cDNA nucleotides. The other two primers (forward primer C and inverse primer D) direct the PCR amplification of the EGF1-like domain of protein C, and they are hybrid primers that contain sequences of protein C gene at the 3' end and of FIX gene at the 5' end. Thus the amplified fragment of EGF1-like domain of protein C (PCEGF1 fragment) is flanked by FIX gene sequences on both ends. When this fragment is mixed with FIX cDNA and subjected to one cycle of PCR, two products are obtained: one containing PCEGF1 fragment linked to FIX cDNA sequence upstream and the other containing PCEGF1 fragment linked to FIX cDNA sequence downstream of its EGF1-like domain. The first product is amplified using primers A and D, and the second product is amplified using primers B and C. Both products contain overlapping sequences, which allow annealing upon mixing. The annealed product is amplified by PCR using primers A and B. The final product contains FIX cDNA in which its EGF1 sequence has been replaced by the PCEGF1 sequence.

Base Sequence↗

PubMed1993

[Development of an HPLC method for determination of chloroquine in plasma].

A simple, rapid and sensitive ion-pair high-performance liquid chromatographic method is described, which allows the quantification of chloroquine in human plasma. 7-Chloro-4-(4-ethylpropylamino-1-methyl-butylamino)quinoline was synthesized and used as internal standard. After extraction by toluene from 1 ml plasma, chloroquine was reextracted with 15% phosphoric acid from the organic phase. Chromatographic separation on a RP-18 column and UV-detection (343 nm) allows sensitive determination of chloroquine in plasma with a lower limit of quantification of 2.5 ng/ml. The method was successfully applied to human plasma samples from 16 subjects after oral administration of 250 mg chloroquine diphosphate.

Chloroquine↗

PubMed1992

[Synthesis of metabolites and enantiomers of prolintane].

The synthesis of 15 possible metabolites of prolintane (1) (Katovit) which is used in the treatment of blood pressure disregulations is described. Furthermore, the preparation of the enantiomers of 1 is reported, starting with R-(+)- and S-(-)-phenylalaninol respectively.

Pyrrolidines↗

PubMed1992

Study on the metabolism of racemic prolintane and its optically pure enantiomers.

1. Asian and European volunteers were given racemic prolintane, and the metabolites in the 24 h urine were identified and quantified by g.l.c. mass spectroscopy using synthetic reference compounds. 2. R-(+)- and S-(-)-prolintane were synthesized from optically active phenylalanine. The metabolism of the enantiomers differs mainly in the quantitative amounts of metabolites.

Adult↗

PubMed1992

[Hepatic carcinoma treated by hepatic arterial embolization using 131I and chemotherapeutic agent gelatin microspheres: report of 9 cases].

Nine patients with inoperable hepatoma were treated by using hepatic arterial embolization 131I and chemotherapeutic agent gelatin microsphere (131I-CA-GM). The emission CT after operation detected that the microspheres were concentrated on tumor area. The ratio between the radioactivity in tumor and that in liver was 4.1:1. A case died of ictopic embolization; the others survived 3, 4, 5, 19, 24, 7, 8, and 12 months respectively. Three of them were still alive. 131I-CA-GM has triple anticarcinogenic actions, including the arterial occlusion, targeting chemotherapy and internal radiation. The microspheres can selectively accumulate in the tumor artery and can be easily traced by gamma-camera or emission CT. 131I-CA-GM is a hopeful embolic agent for the treatment of liver cancer, but some problems about ectopic arterial embolization should be further studied.

Carcinoma, Hepatocellular↗

PubMed1991

[An experimental study on hepatic arterial embolization with 131I-MMC-GM].

We designed a new gelatin microsphere (GM, 65 micron in diameter), which could combine with mitomycin C and 131I. The test in vitro showed that the GM had excellent drug release effect. Hepatic arterial embolization was carried out in 6 dogs with 131I-MMC-GM. The dogs survived from 4 to 28 days before being killed. Scintigraphy indicated that high radioactivity was concentrated in the liver, but was very low in the blood and thyroid. Pathologic study found that the GM was trapped in hepatic arterioles. The GM was eliminated by foreign body giant cells and the lumen of arterioles was occupied by granulations 14-28 days after operation. 131I-MMC-GM is a multiple anticancer agent which can exert triple action of targeting chemotherapy, internal radiotherapy and arterial embolization.

Animals↗

PubMedDate not supplied

AFLP-based genetic linkage map for the red flour beetle (Tribolium castaneum).

The red flour beetle (Tribolium castaneum) is a major pest of stored grain and grain products and a popular model species for a variety of ecological, evolutionary, and developmental biology studies. Development of a linkage map based on reproducible and highly polymorphic molecular markers would greatly facilitate research in these disciplines. We have developed a genetic linkage map using 269 amplified fragment length polymorphism (AFLP) markers. Ten previously known random amplified polymorphic DNA (RAPD) markers were used as anchor markers for linkage group assignment. The linkage map was constructed through genotyping two independent F(2) segregating populations with 48 AFLP primer combinations. Each primer combination generated an average of 4.6 AFLP markers eligible for linkage mapping. The length of the integrated map is 573 cM, giving an average marker resolution of 2.0 cM and an average physical distance per genetic distance of 350 kb/cM. A cluster of loci on linkage group 3 exhibited significant segregation distortion. We have also identified six X-linked and two Y-linked markers. Five mapped AFLP fragments were sequenced and converted to sequence-tagged site (STS) markers.

Animals↗