Undue increase in insulin resistance during pregnancy may manifest pregnancy-induced hypertension and gestational diabetes.
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Diabetes, Gestational↗
Biomedical subjects
J T Lau
Publications and source records attributed to J T Lau.
Size-dependent magnetism of deposited small iron clusters studied by x-ray magnetic circular dichroism.
The size-dependent magnetic properties of small iron clusters deposited on ultrathin nickel films have been studied with circularly polarized synchrotron radiation. With the use of sum rules, orbital and spin magnetic moments have been extracted from x-ray magnetic circular dichroism spectra. The ratio of orbital to spin magnetic moments varies considerably with cluster size, reflecting the dependence of magnetic properties on cluster size and geometry. These variations can be explained in terms of enhanced orbital moments in small clusters.
Journal Article↗
Risk behaviours of Hong Kong male residents travelling to mainland China: a potential bridge population for HIV infection.
The objective was to assess levels of high-risk sexual behaviour, condom use, sexually transmitted disease (STD) history and AIDS-related perceptions among Hong Kong men returning from China by land; 1,254 systematically sampled subjects were interviewed. Of respondents, 32.5% had sexual intercourse with a commercial sex worker (CSW) in China in the past six months; 11.2% have done so on this trip. A third of those who reported having sex with CSWs did so without a condom. A fifth had a history of STDs: seventy per cent of respondents who did not use a condom with a CSW would not use a condom with their regular sexual partner. Less educated respondents, 31-40-year-olds and non-business and frequent travellers were more likely to have sex with a CSW. Those who practice high-risk sex fear AIDS more, are aware that their own risk of HIV infection is not negligible, but think that chances of HIV infection from CSWs in China are small. Although Hong Kong's estimated HIV prevalence among adults is low (0.06%), the huge volume of cross-border travel between Hong Kong and China and the common practice of high-risk sex by Hong Kong male travellers provide a bridge for emerging epidemics to spread.
Acquired Immunodeficiency Syndrome↗
Behavioural surveillance of sexually-related risk behaviours of the Chinese male general population in Hong Kong: a benchmark study.
The objective of the study was to establish a behavioural surveillance system (BSS) for sexually-related risk behaviours of the Hong Kong adult male general population. Benchmark data were obtained by interviewing 1,020 male respondents, age 18 to 60. The results showed that: (1) 14% of the respondents had engaged in commercial sex in the past six months, (2) 27% of the male commercial sex clients did not always use condoms when having sexual intercourse with commercial sex workers (CSWs), (3) 1.5% of the respondents had contracted sexually transmitted diseases (STDs) in the past six months, (4) 6.1% of respondents had only ever had sex with a man, (5) 0.8% of the respondents had practised unprotected anal intercourse with a man in a six-month period, (6) 4.4% of respondents practised sexually-related high risk behaviours, defined as unprotected sex with a CSW or unprotected anal intercourse with a man, and (7) 36.4% of those who engaged in commercial sex had not used condoms with their regular sex partners. Commercial sex was often practised outside Hong Kong, very commonly in Mainland China or Macau, and was often practised at multiple locations by the same client. Effective programmes have to be able to reduce the size of the at-risk population. This study together with future ones, will form the first BSS in Hong Kong for the general male population and will provide a relevant yardstick for programme evaluation.
Adult↗
AIDS-related discrimination in the workplace--the results of two evaluative surveys carried out during a three-year period in Hong Kong.
Two longitudinal surveys were carried out in 1996 and 1999 aimed at describing the situations of AIDS-related discrimination in the workplace and evaluating the effectiveness of some social interventions against discrimination towards HIV-positive employees. Two hundred and ninety-nine and 212 companies completed a questionnaire in 1996 and 1999, respectively. The results are mixed. Although most of the sampled companies had no HIV/AIDS-related policy, their awareness of related legislation increased over the three-year period. Over the three-year study period, more companies indicated they would disclose information of their HIV-positive employees if known to the company; however, fewer companies indicated they would dismiss an employee because of his or her HIV-positive status. Only a few companies indicated that they would provide counselling and support to an HIV-positive employee.
HIV Seropositivity↗
Mouse ST6Gal sialyltransferase gene expression during mammary gland lactation.
The sialyltransferase ST6Gal mediates the biosynthetic addition of sialic acid, via an alpha2,6 linkage, to the nonreducing end of terminal lactosamine structures. Transcription of the murine ST6Gal gene, Siat1, is regulated by the selective use of multiple promoters in a tissue- and development-specific manner. Here we report that Siat1 mRNA expression is dramatically elevated in lactating (relative to virgin) mouse mammary gland. The predominant ST6Gal mRNA species expressed in lactating mammary gland is a heretofore undocumented isoform containing a unique 5'-untranslated region originating from the mouse Siat1 genetic region, now defined as Exon L, residing 549-bp 5' of the previously characterized Exon X(2). Thus, the novel ST6Gal mRNA form initiates transcription from the region designated as p4 and incorporates the unique sequence from Exon L in 5'-juxtaposition to commonly shared sequences encoded on Exon I to Exon VI. In contrast, cells derived from virgin mammary tissue expressed only the housekeeping mRNA form derived from p3, with Exon O sequence preceding Exons I-VI. The Exon L-containing, p4 class of mRNA was also not detected in a survey of eight other mouse tissues. Previous reports have indicated a strong correlation between mammary cancers and elevated ST6Gal expression in rats and in human patients. However, we uncovered neither elevated expression of ST6Gal mRNA nor appearance of p4 class in mouse breast carcinomas experimentally induced by transformation with the polyoma-middle T oncogene. A number of established breast carcinoma cell lines were also examined, with ST6Gal mRNA and activity generally low. Moreover, with the exception of the Shionogi cell line, p4 class of ST6Gal mRNA was not expressed in any of the mouse breast carcinoma specimens examined. Taken together, our data indicate that murine ST6Gal induction during lactation is achieved by de novo recruitment of a normally silent promoter. Furthermore, the data provide no support for elevated Siat1 expression on the mRNA level in association with murine mammary gland carcinogenesis. With the single exception of the Shionogi cell line, the p3 class remains the predominant ST6Gal mRNA expressed in all other murine mammary carcinoma cells examined.
5' Untranslated Regions↗
Predicting traditional Chinese medicine's use and the marginalization of medical care in Hong Kong.
The study examined the importance of socio-demographic factors, health conditions, health beliefs and health seeking behaviors in predicting the use of Traditional Chinese Medicine (TCM) in Hong Kong. A sample of 4,339 respondents was randomly selected and interviewed. Among the 1,651 respondents who had consulted a doctor in the three months prior to the survey, 8.6% consulted a TCM doctor. Besides, 13.5% of the entire sample reported that they had been using TCM drugs frequently or occasionally. Socio-demographic factors, health conditions, health beliefs and health seeking behaviors were all found predictive of the use of TCM. In particular, those who were older, female, new immigrants, unemployed, retired, had chronic disease such as rheumatism, bronchitis, asthma, and those taking non-prescribed medication and not seeking treatment when falling ill were more likely to use TCM. Perceived difficulty in obtaining medical services and high medical cost also predicted TCM use. In sum, the findings suggest that TCM users are likely to be those who have been marginalized in obtaining medical care.
Chronic Disease↗
Outcomes following cheilectomy and interpositional arthroplasty in hallux rigidus.
Surgical management of hallux rigidus remains controversial. Arthrodesis is considered the gold standard. However, many patients are reluctant to undergo fusion. This paper reviews two commonly used procedures that are reasonable alternatives. A retrospective review of 19 patients (24 feet) with grade 2 osteoarthritis and 11 patients (11 feet) with grade 3 osteoarthritis was performed. The patients with grade 2 osteoarthritis were managed with a cheilectomy and the patients with grade 3 osteoarthritis with an interpositional arthroplasty. All patients were individually assessed with a subjective questionnaire, physical exam, AOFAS hallux scale, SF-36 and pedobarographic analysis. Cheilectomy patients (51.9 years) were younger than interpositional arthroplasty (59 years). Follow up between the interpositional arthroplasties (2.0 years) and cheilectomies (2.1 years) were comparable. Postoperative motion, visual analogue pain scale and SF-36 scores were comparable between groups. Cheilectomies had a higher mean AOFAS score (77.3) than interpositional arthroplasties (71.6). Weakness of the great toe was reported in 72.7% of interpositional arthroplasty patients compared to only 16.7% of patients with a cheilectomy. Patient satisfaction was 87.5% in cheilectomies and 72.7% in interpositional arthroplasties. Pedobarographic analysis demonstrated a decreased load under the great toe with increased weight transfer to the lesser metatarsal heads in all patients. The weight transfer to the lesser metatarsal heads was greatest in patients with interpositional arthroplasty. Management of moderate hallux rigidus with a cheilectomy and phalangeal osteotomy is a reliable method of relieving pain and improving function. Management of severe osteoarthritis of the joint with an interpositional arthroplasty should be considered a salvage procedure with less reliable results.
Adult↗
Attitudes about organ and tissue donation among the general public and blood donors in Hong Kong.
CONTEXT: The cadaveric organ and tissue donation rate in Hong Kong is not satisfactory; 1 million blood donors are registered and more than 300,000 are active. However, the current attitudes toward organ and tissue donation in the general public and blood donors of Hong Kong are unknown. METHODS: Random general public (n = 1018) and blood donors (n = 1227) of Chinese origin, with age ranging from 16 to 60 years, were interviewed using a standard verified questionnaire that examines attitudes and knowledge of organ and tissue donation. RESULTS: The mean age of the general public and blood donors were 32.6 and 28.9 years, respectively. Of the general public, 44.4% were men and among blood donors, 60% were men. About 56% of both groups thought that organ donation is an obligation of citizens. Blood donors were more aware than the general public about the types of organs that can be donated. When compared with the general public, a significantly higher percentage of blood donors were willing to donate their organs (81% vs 53%), had heard about organ donation cards (98.3% vs 89.5%), and had signed the cards (49.9% vs 22.6%). About 70% of both groups who had signed a card were carrying it. Thirty-nine percent of the general public and 17% of blood donors had not decided whether they would donate. For blood donors, 49.7% were willing to donate their relatives' organs, compared with 41.8% of the general public. Most individuals in both groups would not object to their relatives' decision to donate. About two thirds of individuals in both groups disagreed with the concept of an opt-out law, though only 20% of the general public and 14.4% of blood donors would refuse donation if an opt-out law were in practice. CONCLUSIONS: This study shows that blood donors have better knowledge of organ donation and are more willing to donate their organs and sign an organ donation card than the general public. However, a substantial proportion of blood donors have not signed a donor card. It would be useful to design promotion programs to facilitate blood donors' participation in organ donation.
Adolescent↗
HIV antibody testing among the Hong Kong mainland Chinese cross-border sex networking population in Hong Kong.
The present study reports the results of 2 surveys examining the likelihood of performing HIV antibody test among the Hong Kong mainland China traveller population. The 2 studies interviewed 1325 and 2074 male adult Hong Kong residents. Among those who had had sexual intercourse with a female sex worker (FSW) in the past 6 months, 31.1% in the first sample indicated that they intended to take an HIV antibody test in the future, whereas 16.4% in the second sample reported they had actually taken a blood test for HIV antibody. In both samples, no association was found between demographic variables, attitudinal/knowledge-related variables and intention to do a blood test for HIV antibody and actual testing behaviour. Moreover, in both samples, those who had more female sexual partners in the past 6 months were more likely to report an intention for HIV test or to have taken an HIV test.
AIDS Serodiagnosis↗
Mobile phone and interactive computer interviewing to measure HIV-related risk behaviours: the impacts of data collection methods on research results.
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Data Collection↗
Studies on common illnesses and medical care utilization patterns of adolescents in Hong Kong.
PURPOSE: To estimate the prevalences of common illnesses in Hong Kong adolescents, the sociodemographic and selected risk factors associated with these illnesses, and their health care utilization behavior and attitudes. METHODS: A cross-sectional questionnaire survey of 3355 participating secondary school students (response rate = 98%). RESULTS: Self-reported 3-month prevalences were obtained for cough/cold/influenza (55.2%), digestive disorders (34.6%), accidental injuries (29.5%), headache/dizziness (23.6%), chronic anxiety/insomnia (20.1%), skin problems (9.5%), asthma (3.8%), liver disease (1.3%), and menstrual pain (13.8% of female students). Self-perceived poor health, smoking, and alcohol consumption were associated with many of these illnesses. Treatment choice depended on the illness suffered (e.g., most students with respiratory problems consulted medical practitioners, whereas most with chronic anxiety/insomnia did not). Many students lacked trust in their doctors, doctor-shopped, relied heavily on self-medication, did not comply with prescribed treatments, would not seek help about medical problems, felt they had insufficient access to health information, and wanted confidential health care. CONCLUSIONS: This study examined for the first time the common illnesses and health care utilization patterns of Hong Kong adolescents. Students with chronic anxiety/insomnia were much less likely to seek care, indicating a need for better education on mental health. Efforts to prevent smoking and alcohol consumption among adolescents need to be strengthened. The students' attitudes, poor compliance and help-seeking behaviors suggest suboptimal use of the health care system. Our findings are useful for international comparisons by medical practitioners, health care managers, and researchers.
Adolescent↗
Murine B cell differentiation is accompanied by programmed expression of multiple novel beta-galactoside alpha2, 6-sialyltransferase mRNA forms.
ST6Gal I (beta-galactoside alpha2,6-sialyltransferase, ST6N) elaborates the ubiquitously expressed alpha2,6-sialyl linkage. A number of ST6Gal I mRNA isoforms, differing only in their 5'-UT regions, is transcribed from a single mouse gene, Siat1. In B-lineage cells, alpha2,6-sialic acid serves as extracellular ligand for CD22, a participant in cell activation via an intracellular signaling network of tyrosine kinases and SHP phosphastase. Activation and terminal differentiation of mature B cells into plasma cells is accompanied by the appearance of at least four distinct ST6Gal I mRNA isoforms. Resting splenic B-lymphocytes isolated from 8-12 wk C56Bl/6 mice expressed almost exclusively the Exons Q+O-containing form, which is the likely homolog to the previously documented human Y+Z and rat -1+0 forms. In vitro activation using recombinant CD40-ligand and conditioned media from T-helper cells resulted in a 2- to 3-fold elevation of overall ST6Gal I mRNA abundance by Day 3. This coincided with repression of the Q+O form, and appearance of three new isoforms containing 5'-untranslated sequences X(1), X(2), or X(3). The X(1)form persisted through Day 10, when the transition of B cells to plasma cells was completed as evidence by disappearance of CD22 mRNA. In contrast, the X(2)form only transiently appeared at Day 3 and declined to barely detectable levels by Day 7. Expression of the X(3)form, a minor mRNA form, paralleled the X(2)form. The divergent 5'-UT exons are dispersed over 69 kb of linear genomic space of Siat1. Mutually exclusive utilization of these 5'-UT exons in transcripts predicts separate and distinct promoter regulatory regions for each mRNA isoform.
Animals↗
The choice between Chinese medicine and Western medicine practitioners by Hong Kong adolescents.
A survey of 3,355 Hong Kong adolescent students showed that the prevalence of TCM clinic consultation in a three-month period was 8.6%. Among students who sought doctor consultation in a three-month period, 17.8% consulted a TCM doctor. Students who sought doctor consultation for fall-related injuries were more likely to have consulted TCM doctors only, while those for skin disease were more likely to have consulted both TCM and western doctors. Perceived cost, efficacy, trust of western doctors and socioeconomic factors were not associated with choice of doctor type. Our findings are different from those on Hong Kong adults' use of health care services as reported in other studies.
Adolescent↗
Behavioural surveillance of sexually-related risk behaviours for the cross-border traveller population in Hong Kong: the evaluation of the overall effectiveness of relevant prevention programmes by comparing the results of two surveillance surveys.
The present study reports the results of 2 surveys of the first behavioural surveillance system (BSS) set up to monitor sexually-related risk behaviours practised by Hong Kong-China cross-border travellers. The 2 studies interviewed 1263 and 1448 male adult Hong Kong residents in 1997 and 1998 respectively. About one-third of the respondents had had sexual intercourse with a commercial sex worker (CSW) in the past 6 months; about 20% had had sexual intercourse with a CSW or a non-regular sex partner in a single trip; about 35-40% of the CSW clients had not used a condom during the intercourse and about 20% of the respondents reported that they had contracted STD. When the results of the 2 surveys were compared, no significant changes in the outcomes of the surveillance indicators were detected; instead, some unfavourable changes in terms of condom use were observed. The effectiveness of the relevant prevention programmes in Hong Kong is not evident.
Acquired Immunodeficiency Syndrome↗
Overexpression of the alpha2,6-sialyltransferase, ST6Gal I, in a low metastatic variant of a murine lymphoblastoid cell line is associated with appearance of a unique ST6Gal I mRNA.
Multiple mRNA isoforms are generated from Siat1, the gene encoding ST6Gal I (beta-galactoside alpha2,6-sialyltransferase, SiaT-1, ST6N, alpha2,6ST). These isoforms, transcriptionally initiated from a number of physically distinct promoter regions, differ only in the 5'-most untranslated region and share an identical ST6Gal I coding region. W16 cells, a spontaneous mutant from MDAY-D2, the highly metastatic murine lymphoid tumor cell line, is considerably less metastatic and exhibits significantly slower tumor growth characteristics [R. Takano, E. Muchmore, and J. W. Dennis (1994) Glycobiology 4, 665-674]. Takano et al. further reported that ST6Gal I mRNA in W16 is elevated 40-fold compared to the parental cells. Here, by means of 5'-RACE analysis, we demonstrate a heretofore undocumented ST6Gal I mRNA form expressed in W16 cells. This ST6Gal I mRNA contains a novel 5'-most untranslated region with 96% sequence similarity to the retroviral-like transposable element, intracisternal particle A (IAP). This observation suggests the notion that elevated ST6Gal I expression in W16 cells is the result of DNA rearrangement in the Siat1 locus. Atypical transcriptional activation of Siat1 is the result of this IAP transposition.
Animals↗
Differential expression of the hepatic transcript of beta-galactoside alpha2,6-sialyltransferase in human colon cancer cell lines.
The activity of beta-galactoside alpha2,6-sialyltransferase (ST6Gal.1), the enzyme responsible for the addition of sialic acid in alpha2,6-linkage to N-acetyllactosaminic (Gal beta1,4GlcNAc) units of glycoconjugates, is increased in the vast majority of colon cancer specimens, and a positive correlation with an invasive phenotype has been suggested by several studies. In many tissues, ST6Gal.1 is regulated mainly at the transcriptional level through the use of different cell-specific promoters which generate transcripts differing in their 5'-untranslated regions. With the aim of understanding the molecular bases of the increased ST6Gal.1 expression in colon cancer, we investigated the expression of mRNA species in colon cancer cell lines and the relationship with enzyme activity and extent of alpha2,6-sialylation of cell glycoproteins. All cell lines examined express the form containing the 5'-untranslated exons Y and Z, typical of the "basal" expression of the gene, while others express also the liver transcript. This indicates that colon cancer cell lines can be grouped according to expression of the liver transcript of ST6Gal.1. The cell lines expressing only the Y+Z form display, in general, a lower activity:mRNA ratio, which might indicate reduced translational efficiency. The level of alpha2,6-sialylation of cell glycoproteins, as determined by reactivity with the Sambucus nigra lectin, is closely associated with the level of enzyme activity.
Blotting, Northern↗
Cell surface n-acetylneuraminic acid alpha2,3-galactoside-dependent intercellular adhesion of human colon cancer cells.
Sialoglycans on the cell surface of human colon cancer (HCC) cells have been implicated in cellular adhesion and metastasis. To clarify the role of N-acetylneuraminic acid (NeuAc) linked alpha2,3 to galactose (Gal) on the surface of HCC cells, we studied the intercellular adhesion of HCC cell lines expressing increasing NeuAcalpha2,3Gal-R. Our model system consisted of the HCC SW48 cell line, which inherently possesses low levels of cell surface alpha2,3 and alpha2,6 sialoglycans. To generate SW48 clonal variants with elevated cell surface NeuAcalpha2,3Gal-R linkages, we transfected the expression vector, pcDNA3, containing either rat liver cDNA encoding Galbeta1,3(4)GlcNAc alpha2,3 sialyltransferase (ST3Gal III) or human placental cDNA encoding Galbeta1,3GalNAc/Galbeta1,4GlcNAc alpha2,3 sialyltransferase (ST3Gal IV) into SW48 cells. Selection of neomycin-resistant clones (600 microgram G418/ml) having a higher percentage of cells expressing NeuAcalpha2,3Gal-R (up to 85% positive Maackia amurenis agglutinin staining compared with 30% for wild type cells) was performed. These ST3Gal III and ST3Gal IV clonal variants demonstrated increased adherence to IL-1beta-activated human umbilical vein endothelial cells (HUVEC) (up to 90% adherent cells compared with 63% for wild type cells). Interestingly, ST3Gal III and ST3Gal IV clonal variants also bound non-activated HUVEC up to 4-fold more effectively than wild type cells. Cell surface NeuAcalpha2,3Gal-R expression within the various SW48 clonal variants correlated directly with increased adhesion to HUVEC (r=0.84). Using HCC HT-29 cells, which express high levels of surface NeuAcalpha2,3Gal-R, addition of synthetic sialyl, sulfo or GalNAc Lewis X structures were found to specifically inhibit intercellular adhesion. At 1.0mM, NeuAcalpha2,3Galbeta1,3(Fucalpha1, 4)GlcNAc-OH and Galbeta1,4(Fucalpha1,3)GlcNAcbeta1,6(SE-6Galbeta1++ +, 3)GalNAcalpha1-O-methyl inhibited HT-29 cell adhesion to IL-1beta-stimulated HUVEC by 100% and 68%, respectively. GalNAcbeta1, 4(Fucalpha1,3)GlcNAcbeta1-O-methyl and GalNAcbeta1,4(Fucalpha1, 3)GlcNAcbeta1,6Manalpha1,6Manbeta1-0-C30H61, however, did not possess inhibitory activity. In conclusion, these studies demonstrated that cell surface NeuAcalpha2,3Gal-R expression is involved in HCC cellular adhesion to HUVEC. These specific carbohydrate-mediated intercellular adhesive events may play an important role in tumor angiogenesis, metastasis and growth control.
Agglutinins↗