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Biomedical subjects

C C Wan

Publications and source records attributed to C C Wan.

At least 19 recordsLinked to original sources
PubMed2001

Inhibition of human immunodeficiency virus type 1 reverse transcriptase, protease and integrase by bovine milk proteins.

Different proteins have been isolated from bovine milk including lactoferrin, lactoperoxidase, glycolactin, angiogenin-1, lactogenin, alpha-lactalbumin, lactoglobulin and casein. These proteins have been assayed for inhibitory activity against human immunodeficiency virus type 1 (HIV-1) reverse transcriptase, protease and integrase, enzymes crucial to the HIV-1 life cycle. It was found that different milk proteins inhibited the three aforementioned HIV enzymes to different extents. Lactoferrin strongly inhibited HIV-1 reverse transcriptase but only slightly inhibited HIV-1 protease and integrase. On the other hand, alpha-lactalbumin, beta-lactoglobulin and casein inhibited HIV-1 protease and integrase to an appreciable extent but did not inhibit HIV-1 reverse transcriptase. Glycolactin and angiogenin-1 suppressed the activity of HIV-1 reverse transcriptase by a moderate extent but more powerfully inhibited HIV-1 protease and integrase. In comparison with the other milk proteins glycolactin was a strong inhibitor of HIV-1 protease and integrase and a moderate inhibitor of HIV-1 reverse transcriptase. Lactogenin was a strong inhibitor of HIV-1 integrase, a moderate inhibitor of HIV-1 reverse transcriptase and a weak inhibitor of HIV-1 protease.

Animals↗
PubMed2000

Use of PCR with universal primers and restriction endonuclease digestions for detection and identification of common bacterial pathogens in cerebrospinal fluid.

We have designed a universal PCR capable of amplifying a portion of the 16S rRNA gene of eubacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecium, Enterococcus faecalis, Mycobacterium tuberculosis, Legionella pneumophila, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Enterobacter cloacae, Pseudomonas aeruginosa, Acinetobacter baumannii, Proteus mirabilis, Haemophilus influenzae, and Neisseria meningitidis. The sizes of the amplified products from various bacteria were the same (996 bp), but the restriction patterns of most PCR products generated by HaeIII digestion were different. PCR products from S. aureus and S. epidermidis could not be digested by HaeIII but yielded different patterns when they were digested with MnlI. PCR products from S. pneumoniae, E. faecium, and E. faecalis yielded the same HaeIII digestion pattern but could be differentiated by AluI digestion. PCR products from E. coli, K. pneumoniae, S. marcescens, and E. cloacae also had the same HaeIII digestion pattern but had different patterns when digested with DdeI or BstBI. This universal PCR could detect as few as 10 E. coli or 250 S. aureus organisms. Compared with culture, the sensitivity of this universal PCR for detection and identification of bacteria directly from 150 cerebrospinal fluids was 92.3%. These results suggest that this universal PCR coupled with restriction enzyme analysis can be used to detect and identify bacterial pathogens in clinical specimens.

Aged↗
PubMed1999

Isolation of a trypsin inhibitor with deletion of N-terminal pentapeptide from the seeds of Momordica cochinchinensis, the Chinese drug mubiezhi.

A trypsin inhibitor, MCCTI-1, with a molecular weight of 3479 Da as determined by mass spectrometry, was isolated from Momordica cochinchinensis seeds with a procedure involving extraction with 5% acetic acid, ammonium sulfate precipitation, ion exchange chromatography on CM-Sepharose and reverse-phase high performance liquid chromatography. The sequence of its first 13 N-terminal amino acid residues was ILKKCRRDSDCPG which was about 85% identical with the sequence of trypsin inhibitor MCTI-1 from Momordica charantia Linn. When compared with the sequences of most other squash family trypsin inhibitors, the sequence of MCCTI-1 was characterized by the deletion of a pentapeptide from the N-terminus. Trypsin inhibitors also existed in seeds of some hitherto uninvestigated Cucurbitaceae species.

Amino Acid Sequence↗
PubMed1999

Ureaplasma urealyticum infection and apoptosis of spermatogenic cells.

AIM: To study the relationship between Ureaplasma urealyticum (UU) infection and apoptosis of human spermatogenic cells. METHODS: Spermatogenic cells were observed under light microscope with Wright-Giemsa staining and by means of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP)-biotin nick-end labeling (TUNEL) technique. RESULTS: Apoptotic rate of UU-infected males (15.5% +/- 6.8%) was significantly higher than that of controls (5.2% +/- 2.3%). CONCLUSION: Apoptosis of spermatogenic cells can be caused by UU infection, which provides further evidence for UU-induced male infertility.

Adult↗
PubMed1997

A comparison of human immunodeficiency virus type 1 inhibition by partially purified aqueous extracts of Chinese medicinal herbs.

A multiple screening approach to detect compounds inhibitory to various aspects of the human immunodeficiency virus type 1 (HIV-1) life-cycle has been applied to aqueous extracts of 19 herbs traditionally used in Chinese medicine as anti-viral agents. The extracts were tested for their ability to inhibit HIV-1 in a series of in vitro assays. The extracts were tested for inhibition of the interaction between HIV-1 gp120 and immobilized CD4 receptor, inhibition of recombinant HIV-1 reverse transcriptase and for inhibition of three glycohydrolase enzymes that contribute to viral protein glycosylation. Six of the herb extracts (30%) were potent inhibitors of the interaction between HIV-1 gp120 and the CD4 receptor (ID50 5.6 - 79.4 microg/ml), two extracts (10%) contained potent reverse transcriptase inhibitors (ID50 16.9 - 26.0 microg/ml) and 14 extracts (75%) were able to inhibit at least one of the glycohydrolase enzymes.

CD4 Antigens↗
PubMed1997

Inhibition of glycohydrolase enzymes by aqueous extracts of Chinese medicinal herbs in a microplate format.

A microplate assay, for use with a variety of glycohydrolase enzymes, was developed to aid the screening of Chinese medicinal herb extracts for the presence of potential anti-viral and anti-lymphoma compounds. The microplate assay method described offers greater convenience, speed and reproducibility over existing methods. The enzymes tested were alpha-glucosidase, beta-glucosidase and beta-glucuronidase. The assay can be easily adapted for use with other glycohydrolase enzymes. Of the 12 herb extracts examined four did not inhibit any of the enzymes (< 50% inhibition), one inhibited alpha-glucosidase only (> 50% inhibition), six inhibited beta-glucuronidase only, and one inhibited both alpha-glucosidase and beta-glucuronidase. None of the extracts were capable of inhibiting beta-glucosidase to any significant extent.

Antineoplastic Agents↗
PubMed1989

A versiconal hemiacetal acetate converting enzyme in aflatoxin biosynthesis.

Conversion of the aflatoxin biosynthetic intermediate versiconal hemiacetal acetate (VHA) in a cell free extract of Aspergillus parasiticus ATCC 15517 is investigated. The enzymatic reaction is monitored by a method using high performance liquid chromatography (HPLC). The major product of the enzymatic reaction is a water soluble compound not chloroform-extractable at pH 7.5. The product becomes chloroform extractable upon acidification of the reaction medium and is separated and quantitated by reversed-phase HPLC. It is tentatively identified as 'versiconal hemiacetal alcohol,' which is converted to versicolorin C (VC) upon acid treatment.

Aflatoxins↗
PubMed1985

Preconcentration of cadmium, chromium, copper and lead in drinking water on the polyacrylic ester resin, XAD-7.

The conditions (e.g. pH, resin, particle size, foreign ions) affecting the uptake of Cd(II), Cr(III), Cu(II) and Pb(II) from aqueous solution by the SM-7 (also called XAD-7) resin, were studied. Based on these studies, a two-column method was developed to overcome the effect of complexation by humic substances. The method was successfully tested with the NBS multielement water standard, SRM 1643a, and was subsequently applied to enrich Cd(II), Cr(III), Cu(II) and Pb(II) in 15 drinking water samples from Hamilton, Ontario. The metals were determined using graphite furnace atomic absorption spectrometry. The results for the drinking water samples showed that leaching of copper and lead occurred from the distribution system.

Acrylic Resins↗
PubMed1980

Analysis of various indefinite self-associations of the AK type.

Although we and others have developed equations to analyze for some indefinite self-associations that might be encountered, it is felt in some cases that these models, known as the sequential, equal equilibrium constant (SEK) models, might overestimate the size of aggregates encountered at higher solute concentrations. Thus, Garland and Christian proposed two attenuated equilibrium constant (AK) models that might overcome this problem. Their methods were restricted to ideal solutions and to osmometric procedures. We have removed these restrictions, and we have developed equations for analyzing four AK models that might be encountered. Various tests to aid in distinguishing these models are presented. These procedures have been tested with two simulated examples of a Type III AK indefinite self-association.

Journal Article↗
PubMed1978

Occurrence of glycosphingolipids in chicken egg yolk.

Chicken egg yolk was found to contain a unique glycosphingolipid pattern not seen in other types of tissue or cell. These glycosphingolipids were isolated in pure form and their structures established by sequential enzymic hydrolysis and permethylation analysis. The major gangliosides in chicken egg yolk are N-acetylneuraminosylgalactosylceramide, N-acetylneuraminosyl-lactosylceramide and di-N-acetylneuraminosyl-lactosylceramide. The only neutral glycosphingolipid found in chicken egg yolk is galactosylceramide.

Animals↗