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Biomedical subjects

F Cheng

Publications and source records attributed to F Cheng.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Studies on hereditary deficiency of coagulation factor V].

OBJECTIVE: To explore the mechanisms of hereditary deficiency of coagulation factor V (FV). METHODS: The amount of FV in plasma and platelets was assayed by immunological and biochemical method, FV gene analysis by PCR product sequencing and restriction enzyme analysing, and the biostructural pathology of the identified mutation by molecular modeling. RESULTS: No detectable FV fragments and FV activity were found in the plasma and platelets from the proband of the affected family. His gene analysis revealed a 1763A-->C substitution in a FV allele gene. The mutation might cause the loss of the hydrogen bond between conservative Tyr530 and Glu330, and form a cavity in the protein core. CONCLUSION: The 1763A-->C mutation might cause the instability of FV and be the important mechanism for the hereditary deficiency of FV.

Adult↗
PubMed2001

[High performance liquid chromatographic determination of domoic acid in shellfish samples].

Domoic acid in shellfish samples was determined by HPLC with DAD/UV detector at 242 nm. Samples were extracted with methanol-water followed by clean-up of the extracts with strong anion exchange solid phase extraction cartridge(3 mL LC-SAX). Zorbax SB-C18 column, 150 mm x 4.6 mm i.d., and mobile phase of acetonitrile-0.1% aqueous trifluoroacetic acid(13:87, V/V) were used for the assay. The quantitative analysis was performed with external standard. The calibration curve of domoic acid was linear in the range of 1.0 m/L-25.0 mg/L and the detection limit was ca. 0.2 microgram/g.

Animals↗
PubMed2000

Structural characterization of the catalytic active site in the latent and active natural gelatinase B from human neutrophils.

Matrix metalloproteinases are endopeptidases that have a leading role in the catabolism of the macromolecular components of the extracellular matrix in a variety of normal and pathological processes. Human gelatinase B is a zinc-dependent proteinase and a member of the matrix metalloproteinase family that is involved in inflammation, tissue remodeling, and cancer. We have conducted x-ray absorption spectroscopy, atomic emission, and quantum mechanics studies of natural and activated human gelatinase B. Our results show that the natural enzyme contains one catalytic zinc ion that is central to catalysis. In addition, upon enzyme activation, the catalytic zinc site exhibits a conformation change that results in the expansion of the bond distances around the zinc ion and the replacement of one sulfur with oxygen. Interestingly, quantum mechanics calculations show that oxygen ligation at the catalytic zinc ion exhibits a greater affinity to the binding of an oxygen from an amino acid residue rather than from an external water molecule. These results suggest that the catalytic zinc ion plays a key role in both substrate binding and catalysis.

Binding Sites↗
PubMed2000

Increasing uptake rates of cervical cancer screening amongst Hong Kong Chinese women: the role of the practitioner.

Women's attendance for regular cervical screening has been identified as a significant factor in the prevention of cervical cancer. Evidence suggests, however, that both extrinsic and intrinsic factors influence women's attendance patterns for screening. Extrinsic factors, in particular the practitioner undertaking the screening procedure, have been shown to influence women's return rates for further screening. In Hong Kong, where uptake rates amongst Chinese women remain comparatively low, a study was undertaken to examine Chinese women's experiences and perceptions of cervical screening undertaken by either a female doctor or nurse. A multiple case study design using both qualitative and quantitative methods of data collection was employed. This paper reports the findings from the qualitative data obtained from 52 women participating in 12 focus group interviews held in the two case studies. Thematic analysis of the data demonstrated the importance of the caring nature, communication skills, experience and expertise of the practitioner to women's attendance pattern for screening. The experience and expertise of the practitioner, described by women as teaching, minimizing pain and discomfort and being considerate, were considered more influential to uptake rates than the professional discipline of the practitioner. Findings such as these indicate the importance of the influence of the practitioner in determining uptake rates for cervical screening amongst this population group.

Adult↗
PubMed2000

Distribution of a common methylenetetrahydrofolate mutation in six Chinese population groups.

The distribution of the C677T polymorphism was analyzed by the PCR-RFLP technique in the Northeast Han, the Oroqen, the Ewenki, the Daur as well as in Koreans and Mongolians. The results were compared with each other. They revealed that the frequencies of the T allele are quite different (17-47%) among the tested groups and are much higher in Chinese population groups than in others.

Asian People↗
PubMed2000

[Investigation on E. coli O157 in Fujian, China].

OBJECTIVES: To understand the distribution of Escherichia coli O157 (E. coli O157) in human beings, livestock and fowls in Fujian Province, and biological features of the isolated strains. METHODS: Fecal specimens from diarrheal patients, livestock and fowls and meat specimens in Putian and Fuzhou were collected for detection of E. coli O157 during 1997 - 1998. RESULTS: A total of 2,725 specimens were detected, and 76 strains of E. coli O157 were isolated from pigs, pigeons, cattle, chickens, ducks, et al., as well as from the diarrheal patients. These strains could be classified into three types according to their serological tests, including 33 strains of O157: H7, 21 strains of O157: NM, and 22 strains of O157: H?. Detecting rate of E. coli O157 from pigs was the highest. The isolated strains could cause diarrhea in human and obvious pathological changes in the intestines of mice, but could not produce cytotoxin Vero, or heat-stable or heat-liable enterotoxin LT or ST. CONCLUSIONS: There were three types of E. coli O157 in Fujian. But, pathogenic factors of O157: H7 and O157: NM were different from those reported abroad. It suggested that there possibly existed some new pathogenic factors.

Animals↗
PubMed2000

[GC-MS analysis of essential oil components of Alpinia oxphylla].

Essential oil Components of Alpinia oxphylla were analyzed by way of applying gas chromatography, mass spetrography and computer interpretation; essential oil was abtained by supercritical CO2 fluid, thus we got 193 peaks in oil from Pot I and 210 peaks in oil from Pot II as well as identify 139 and 155 compounds respectively.

Alpinia↗
PubMed2000

The changes of TGF-alpha, TGF-beta 1 and basic FGF messenger RNA expression in rabbit cornea after photorefractive keratectomy.

OBJECTIVE: To study the mechanism of haze formation and investigate the expression changes of transforming growth factor-alpha (TGF-alpha), transforming growth factor-beta 1(TGF-beta 1) and basic fibroblast growth factor (bFGF) mRNA in corneal epithelium and stroma after photorefractive keratectomy (PRK). METHODS: Sixteen white rabbits were randomly divided into 4 groups, and PRK was performed on each eye of 12 rabbits. The haze formation was examined under a slit-lamp microscope at the 1st, 2nd and 3rd month after PRK, and the expressions of TGF-alpha, TGF-beta 1 and bFGF mRNA were detected with in situ hybridization. RESULTS: The corneal haze formed at the 1st month after PRK. The most prominent haze formation was observed at the 2nd month, and declined gradually at the 3rd month after ablation. TGF-alpha mRNA expression was presented on the normal corneal epithelium and not on the corneal stroma. TGF-beta 1 and bGFG mRNA were expressed by both corneal epithelium and stroma. The capacities for cornea tissue expression of three growth factors mRNA increased after PRK, and the peaks appeared on the 1st, 2nd month. The extent for expressions of three growth factors related proportionally to the haze formation. CONCLUSION: Three growth factors took part in promoting corneal wound healing after PRK, and might contribute to corneal haze formation and development.

Animals↗
PubMed2000

[Development of multi-function ECG signal generator].

This paper describes the development of a portable multi-function ECG signal generator, which is based on micro-controller. It uses technique of LCD screen, and realizes man-machine interaction by keyboard. In constructing and disposing data module of the ECG signal, Eigen-heartbeat Code mapping method gets ROM saved greatly. Therefore it can generate all kinds of user-defined ECG signal sequence with no extension of on-board memory chips. This system can also simulate kinds of ECG signals, which have various heart rates and symptoms. It can meet the needs of researching and maintenance of kinds of ECG instruments.

Analog-Digital Conversion↗
PubMed2000

[ICP-AES analysis of trace elements in human hair of chronic hepatitis].

The concentration of Al, Ba, Ca, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, Zn and other trace elements in human hair of chronic hepatitis(college students) were determined by ICP-AES. RSD of the method was 1.4%-4.9%, recovery was 94%-129%. Analysis results were compared with that of healthy. There are remarkable differences between concentration of Al, Cu, Fe, Ni, Zn and Mn. Correlation between trace elements and chronic hepatitis were also discussed.

Aluminum↗
PubMed1999

Should adolescents be vaccinated against hepatitis A: the Hong Kong experience.

Hong Kong is a well developed city in the center of an endemic region for hepatitis A. The age at which hepatitis A occurs has shifted from childhood and adolescence to adults like many western countries. There is a high chance of outbreaks with the introduction of infection from neighbouring countries. Reducing the susceptibility of a population by vaccination can eliminate the diseases but updated sero-epidemiological data is needed to analyse the level of natural immunity, and identify those susceptible to infection for preventive measures. This study conducted amongst secondary school children seeks to identify those who are at risk and to obtain data on the present sero-prevalence of anti-HAV. Overall prevalence of anti-HAV in this age group was 7% increasing with age. Analysed by multiple regression model, those students living in mainland China over 3 years had odds ratio of 31.6 (95% c. i. 17.4-57.3) compared with those born in Hong Kong. Students with a father in a skilled occupation and an education level of secondary school or above, and both parents with secondary education or above, had an odds ratio of 0.22 (95% c.i. 0.07-0.7) and 0.35 (95% c.i. 0. 17-0.72) associated with presence of anti-HAV, respectively. Improved socio-economic state exposes higher proportion of the population at risk. Immunisation is worthwhile to be considered for the adolescents in Hong Kong. Prevaccination screening is cost effective only for those adolescents who are most likely to have natural immunity.

Adolescent↗
PubMed1999

Organization of the inter-alpha-inhibitor heavy chains on the chondroitin sulfate originating from Ser(10) of bikunin: posttranslational modification of IalphaI-derived bikunin.

Inter-alpha-inhibitor-derived bikunin was purified and the molecular mass was determined to be approximately 8.7 kDa higher than the prediction based on the protein sequence, suggesting extensive posttranslational modifications. These modifications were identified and characterized by a combination of protein and carbohydrate analytical techniques. Three modifications were identified: (i) glycosylation of Ser(10), (ii) glycosylation of Asn(45), and (iii) a heterogeneous truncation of the C-terminus. The Asn(45) associated glycan was shown to be a homogenous "complex type" biantennary structure. The chondroitin-4-sulfate (CS) chain attached to Ser(10) was analyzed by both matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and acrylamide gel electrophoresis after partial chondroitin ABC lyase digestion. The analyses showed that the CS chains were composed of 15 +/- 3 [GlcUA-GalNAc] disaccharide units. On average, every forth disaccharide was sulfated, and these sulfated disaccharides appeared to be more common near the reducing end. Anion exchange chromatography at pH 3. 4 of intact bikunin resulted in the isolation of four isotypes shown to differ only in the amount of sulfation. Heavy chain 1 (HC1) and heavy chain 2 (HC2) are attached to the CS by a novel cross-link [Enghild, J. J., Salvesen, G., Hefta, S. A., Thogersen, I. B., Rutherfurd, S., and Pizzo, S. V. (1991) J. Biol. Chem. 266, 747-751], and the order in which the two heavy chains are positioned on the CS was examined. The results indicate that HC1 is in close proximity to HC2 and both are near the less sulfated nonreducing end of the CS. Taken together, the data show the following organization of the IalphaI molecule: [GlcUA-GalNAc](a)-HC1-[GlcUA-GalNAc](b)-HC2-[GlcUA-GalNAc](c)-Gal -Gal-Xyl-Ser(10)-bikunin, (a + b + c = 12-18 disaccharides).

Alpha-Globulins↗
PubMed1999

Experimental study of the protection of ischemic preconditioning to spinal cord ischemia.

BACKGROUND: Since the advent of ischemic preconditioning in myocardium, more and more attention has been paid to ischemic preconditioning in the central nervous system (CNS). This study was designed to evaluate the protective effect of ischemic preconditioning on spinal cord ischemia. METHODS: Interventional neuroradiological techniques were used to induce spinal cord ischemia in a rabbit model. Hydrogen electrode technique was used to determine the regional blood flow of the spinal cord. Catecholamines and their metabolites were measured by high performance liquid chromatography (HPLA). Spinal cord evoked potentials were recorded to show spinal cord neurofunction. RESULTS: After 5 minutes ischemic preconditioning with 20 minutes reperfusion, the regional spinal cord blood flow (rSCBF) was increased, as may be seen by the slight increase of catecholamine, especially NE. This is in positive proportion to the cAMP and indicates the enhancement of the metabolic activities of the spinal cord. After 30 minutes of irreversible ischemia, the great increase in catecholamine caused vascular spasm, endotheliocyte fissure, multiple hemorrhagic suffusion, and necrosis, which would injure the spinal cord as a result. The slight increase of the rSCBF and the maintenance of the rSCBF after irreversible ischemia may enhance the protection of ischemic preconditioning to the spinal cord neurofunction, which was proved by spinal cord evoked potentials (SCEPs). CONCLUSIONS: Our study showed that 5 minutes of ischemic preconditioning can increase the rSCBF, enhance the tolerance of the spinal cord to irreversible ischemia, and protect the neurofunction of the spinal cord. The biological mechanism of the protective effect of ischemic preconditioning to spinal cord ischemia should be further studied.

Animals↗
PubMed1999

A case study of the effectiveness of nurse-led screening programmes for cervical cancer among Hong Kong Chinese women.

Cervical cancer remains a cause of morbidity and mortality among women despite the efficacy of Pap smear screening. Uptake rates for Papanicolaou (Pap) smears among Hong Kong Chinese women remain low and evidence suggests that both intrinsic and extrinsic factors influence women's attendance for Pap smear screening, particularly the practitioner taking the smear. This study examined the experiences and perceptions of Hong Kong Chinese women of having a Pap smear taken by a female doctor or a female nurse using a case study design. A convenience sample of 50 women was selected from the two case study settings. Data collection involved a confidential structured interview, followed by focus group interviews with a sample of women participating in the structured interview. The findings relating to the technical quality and outcome of care provide the focus for this paper. Although women were highly satisfied with the care provided by both practitioners, women were more satisfied with the information given about the procedure by the nurse (P = 0.0130) and had more confidence in the nurse (P = 0.024). One of the five criteria used to assess the quality of smears demonstrated the doctor achieved a statistically significant higher number of smears containing the required percentage of endocervical cells (P = 0. 0180). Nevertheless, none of the smears taken by the nurse required repeating due to an inadequate specimen. These findings suggest, despite the need for audit of Pap smears, that appropriately qualified nurses can make an important contribution to the uptake of Pap smears among this population.

Adult↗
PubMed1999

Changing hepatitis A epidemiology among Hong Kong Chinese adolescents: what are the implications?

OBJECTIVE: To study the sero-epidemiology of hepatitis A virus (HAV) among adolescents in Hong Kong and analyse the changing patterns of the infection rates. DESIGN: Cross sectional study. SETTING: Secondary school students. SUBJECTS: One thousand, five hundred and eighty students were randomly selected from 12 schools in four regions of Hong Kong. MAIN OUTCOME MEASURES: Anti-HAV status. RESULTS: The overall prevalence of anti-HAV is 7%. The sero-prevalence for age group 11-20 y has fallen compared with 44.8% in 1978, 17.1% in 1987 and 11.2% in 1989. Those adolescents born in mainland China, who are frequent travellers and had a longer period of residence in mainland China were shown to have a higher prevalence of anti-HAV. CONCLUSION: The changing epidemiology of HAV indicates that Hong Kong will have a large proportion of susceptible young adults. Because of its geographic situation and import of most its food supplies from less developed countries, for epidemiological purposes the inhabitants can be compared to western travellers staying in a five star hotel in a less developed country. The risk of an outbreak of HAV is to be expected. Vaccination has the potential to serve as an effective prevention for adolescents living in countries whose circumstances are similar to Hong Kong.

Adolescent↗