X-Ray Absorption Spectrum of the N_{2}^{+} Molecular Ion

The x-ray absorption spectrum of N_{2}^{+} in the K-edge region has been measured by irradiation of ions stored in a cryogenic radio frequency ion trap with synchrotron radiation. We interpret the experimental results with the help of restricted active space multiconfiguration theory. Spectroscopic constants of the 1σ_{u}^{-1} ^{2}Σ_{u}^{+} state, and the two 1σ_{u}^{-1}3σ_{g}^{-1}1π_{g} ^{2}Π_{u} states are determined from the measurements. The charge of the ground state together with spin coupling involving several open shells give rise to double excitations and configuration mixing, and a complete breakdown of the orbital picture for higher lying core-excited states.

Large orbital magnetic moments of small, free cobalt cluster ions Co[Formula: see text] with n [Formula: see text]

The size dependent electronic structure and separate spin and orbital magnetic moments of free Co[Formula: see text] ([Formula: see text]) cluster ions have been investigated by x-ray absorption and x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap. A very large orbital magnetic moment of [Formula: see text] per atom was determined for Co[Formula: see text], which is one order of magnitude larger than in the bulk metal. Large orbital magnetic moments per atom of  ≈1 [Formula: see text] were also found for Co[Formula: see text], Co[Formula: see text], and Co[Formula: see text]. The orbital contribution to the total magnetic moment shows a non-monotonic cluster size dependence: The orbital contribution increases from a local minimum at n  =  2 to a local maximum at n  =  5 and then decreases with increasing cluster size. The 3d spin magnetic moment per atom is nearly constant and is solely defined by the number of 3d holes which shows that the 3d majority spin states are fully occupied, that is, 3d hole spin polarization is 100%.

Electronic ground state of Ni2. J Chem Phys 2016;145:194302. [PMID: 27875883 DOI: 10.1063/1.4967821]

The Φ9/24 ground state of the Ni₂⁺ diatomic molecular cation is determined experimentally from temperature and magnetic-field-dependent x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap, where an electronic and rotational temperature of 7.4±0.2 K was reached by buffer gas cooling of the molecular ion. The contribution of the spin dipole operator to the x-ray magnetic circular dichroism spin sum rule amounts to 7T_z=0.17±0.06μ_B per atom, approximately 11% of the spin magnetic moment. We find that, in general, homonuclear diatomic molecular cations of 3d transition metals seem to adopt maximum spin magnetic moments in their electronic ground states.

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.

Magnetic moments of chromium-doped gold clusters: the Anderson impurity model in finite systems

The magnetic moment of a single impurity atom in a finite free electron gas is studied in a combined x-ray magnetic circular dichroism spectroscopy, charge transfer multiplet calculation, and density functional theory study of size-selected free chromium-doped gold clusters. The observed size dependence of the local magnetic moment can be understood as a transition from a local moment to a mixed valence regime. This shows that the Anderson impurity model essentially describes finite systems even though the discrete density of states introduces a significant deviation from a bulk metal, and the free electron gas is only formed by less than 10 electrons. Electronic shell closure in the gold host minimizes the interaction of localized impurity states with the confined free electron gas and preserves the magnetic moment of 5 μ_{B} fully in CrAu_{2}^{+} and almost fully in CrAu_{6}^{+}. Even for open-shell species, large local moments are observed that scale with the energy gap of the gold cluster. This indicates that an energy gap in the free electron gas stabilizes the local magnetic moment of the impurity atom.

Spin coupling and orbital angular momentum quenching in free iron clusters

Magnetic spin and orbital moments of size-selected free iron cluster ions Fe{n}{+} (n=3-20) have been determined via x-ray magnetic circular dichroism spectroscopy. Iron atoms within the clusters exhibit ferromagnetic coupling except for Fe{13}{+}, where the central atom is coupled antiferromagnetically to the atoms in the surrounding shell. Even in very small clusters, the orbital magnetic moment is strongly quenched and reduced to 5%-25% of its atomic value while the spin magnetic moment remains at 60%-90%. This demonstrates that the formation of bonds quenches orbital angular momenta in homonuclear iron clusters already for coordination numbers much smaller than those of the bulk.

Size dependence of L2,3 branching ratio and 2p core-hole screening in x-ray absorption of metal clusters

Resonant 2p x-ray absorption spectra of size-selected transition metal ions and clusters consisting of 1<or=n<or=200 atoms are reported. Remnants of atomic multiplet splitting in L(2,3)-edge x-ray absorption can be resolved up to the trimer, above which the overall line shape is already bulklike. A strong cluster size dependence of the L(2,3) branching ratio was found for titanium, vanadium, and cobalt clusters. While 3d electron delocalization increases with cluster size, the apparent 2p spin-orbit splitting remains constant within the error bars. The size dependence of the L(2,3) branching ratio can be attributed to cluster size specific screening of the 2p-3d Coulomb interaction by 3d/4s valence electrons.

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.

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.

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-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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Effect of increasing distal medial closing wedge metatarsal osteotomies on the distal metatarsal articular angle

The recognition, definition, and management of the congruent hallux valgus deformity continue to evolve. To correct the skeletal deformity and maintain joint congruity, many authors have emphasized the importance of extra-articular procedures. One such procedure is a distal medial closing wedge osteotomy of the first metatarsal. Unfortunately, there are few guidelines to help determine the pre- and intraoperative size of the medial wedge to obtain the desired correction of the distal metatarsal articular angle (DMAA). The purpose of this study was to quantify the effects of increasing distal medial closing wedge osteotomies on the DMAA in an in vitro cadaver model. In this study, a closing wedge osteotomy was performed 2 cm proximal to the articular surface, removing wedges measuring 2 mm, 4 mm, and 6 mm in width. The mean preoperative DMAA was 8.5 degrees, and the mean postoperative DMAAs after 2-mm, 4-mm, and 6-mm closing wedge osteotomies were -2.6 degrees, -10.2 degrees, and -20.2 degrees, respectively. The data showed that for every 1 mm of closing wedge osteotomy, the DMAA decreased by 4.7 degrees +/- 0.6 degrees. These results can be used for pre- and intraoperative planning when surgically correcting a congruent hallux valgus deformity with a distal medial closing wedge osteotomy of the first metatarsal. Additional information obtained from this cadaver study includes (1) increased shortening of the first metatarsal and (2) incongruity produced at the joint after the medial-based osteotomy. The amount of shortening of the first metatarsal correlated directly with the size of the medial-based wedge. The second point indicates that a lateral soft-tissue release may still be required when using this method of reorienting the DMAA.

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.

Conceptualization, reporting and underreporting of child abuse in Hong Kong

OBJECTIVE

To understand the conceptualization of child abuse and attitudes on reporting behaviors of Hong Kong adults.

METHODS

Cross-sectional telephone survey of 1,001 randomly selected subjects.

MAIN RESULTS

There is a discrepancy between perceived prevalence and the ability to name different child abuse types without prompting: 79.9% named physical abuse, while 41.2% felt it was common: 21.0% named child neglect, while 76.9% felt it was common; 13.4% named psychological abuse, while 47.4% felt it was common; 6.8% named sexual abuse, while 23.5% felt it was common. Most respondents classified severe physical abuse situations as abusive (e.g., "severely injuring a child"). Other scenarios such as "mildly injuring a child" and neglect and psychological abuse scenarios (e.g., "leaving a young child alone at home" and "shouting at a child often") were often not classified as abusive. As regards case-reporting behavior, only about 40% would report abuse cases to authorities. Those who would not report abuse were less likely to classify abuse situations as abusive and more likely to think that seeking help is difficult, troublesome and unhelpful.

CONCLUSIONS

The official reported prevalence figures for child abuse in Hong Kong should be interpreted with care, because underreporting is likely to be serious. Hong Kong people's conceptualization and awareness of what comprises child abuse is found to differ from official definitions. They are reluctant to report abuse cases, due to their perceived low efficacy of case reporting. Both the difference in conceptualization and the reluctance to report might partly be attributable to Chinese culture.

Public evaluation of an announcement of public interests communicated by an AIDS patient

Announcements of public interests (APIs) on television (TV) have been an important means of AIDS prevention. Recently in Hong Kong, the first API on TV which was communicated by a male AIDS patient, named J.J., was displayed on the screen from April to December, 1995. The objective of this study is to examine the effectiveness of this API, as compared with other APIs previously shown in Hong Kong. Collecting data from a random sample of 1,275 residential respondents in Hong Kong through a telephone survey, this study demonstrated that the public gave very favorable evaluation on J.J.'s API, when compared with other APIs. Remarkable impacts of J.J.'s API on the public included increasing concern for AIDS, condom use, and testing blood for HIV infection, and reducing the number of sex partners. The impacts tended to be more salient on male than female viewers. Some of these impacts also appeared to vary by different levels of education and family income.

Hepatic acute phase induction of murine beta-galactoside alpha 2,6 sialyltransferase (ST6Gal I) is IL-6 dependent and mediated by elevation of exon H-containing class of transcripts

Hepatic expression of CMP-NeuAc:Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase (ST6Gal I) is induced as part of the acute phase response in mammals by mechanisms that remain poorly understood. Previous work suggests that murine liver ST6Gal I mRNA contains an additional and novel region that is not found on ST6Gal I mRNA from human HepG2 hepatoma cells and from rat liver. This novel region, residing 5' of the common Exon I sequence, is encoded by a discrete upstream exon, Exon H. Here we provide evidence that the Exon H-containing transcript is the murine counterpart of the human and rat ST6Gal I mRNAs transcribed from the hepatic-specific promoter, P1. Exon H-containing ST6Gal I mRNA is expressed in all three mice strains examined: balb/c, C57B46, and 129Sv. Furthermore, murine RNA tissue survey indicates that presence of Exon H-containing transcripts is restricted to the liver. When mice are subjected to subcutaneous injection of turpentine to elicit the hepatic acute phase response, greater than 4-fold elevation in liver ST6Gal I mRNA was observed. Consistent with the view that Exon H-containing transcripts is regulated by the murine P1 promoter, 5'-RACE analysis indicates that the majority of these transcripts contains the Exon H sequence. This is consistent with the view that Exon H-containing transcripts are regulated by the murine P1 region. To assess the mechanism of ST6Gal I response in the hepatic acute phase reaction, mice harboring lesions in both alleles of the IL-6 gene were examined. IL-6(-/-) animals expressed normal levels of ST6Gal I mRNA in liver, with Exon H-containing transcripts remaining the predominant mRNA isoform. However, hepatic ST6Gal I is not elevated upon turpentine injection in the IL-6(-/-) animals. These results indicate that ST6Gal I induction in mouse liver during the acute phase reaction is mediated predominantly by the IL-6 pathway, and results in the induction of the Exon H-containing class of ST6Gal I mRNA that is specific to the liver.

Transcription of the beta-galactoside alpha2,6-sialyltransferase gene (SIAT1) in B-lymphocytes: cell type-specific expression correlates with presence of the divergent 5'-untranslated sequence

A single gene, SIAT1, encodes ST6Gal I, the sialyltransferase that mediates transfer of alpha2,6-linked sialic acids to Galbeta1, 4GlcNAc termini of N-linked glycoproteins. In vivo, multiple SIAT1 mRNA forms, differing only in the 5'-untranslated region, are expressed in a tissue-specific manner. This mRNA heterogeneity has been attributed, at least in part, to transcription from a number of physically distinct promoter regions. In mature B-lymphocytes, SIAT1 transcription initiates at P2, a regulatory region known to function only in B-lineage cells. Bacterial chloramphenicol acetyltransferase (CAT) under the control of the P2 region encompassing 415 bp 5'- and 125 bp 3' of the transcriptional initiation site is efficiently expressed in Louckes, a mature B-lymphoblastoid cell line. In contrast, CAT expression in Reh, a T-null/B-null precursor line, and in HepG2, a hepatoma line, are 14-fold and >25-fold less than in Louckes, respectively. The data is consistent with the presence of cis -acting regulatory elements residing both 5' and 3' of the P2 transcriptional initiation site. At least 370 bp of 5'-flanking sequence, coinciding with the inclusion of AP2 and NF-kappaB sites, is necessary for high level expression in Louckes. Exon sequences 3' of the transcription start site are also important for expression. A segment from(+)32 to(+)125 (position(+)1 is transcription start site) is capable of exerting promoter-like activity in Louckes, but not in Reh or HepG2. CAT expression by P2 is negligible in Reh cells. However, enhanced CAT activity is not accompanied by elevated mRNA levels. This observation is consistent with the relief of translational restraints imposed by the(+)32 to(+)125 region. Together, the data demonstrate that efficient and cell-specific transcription regulation in mature B lymphocytes is contained in a 495 bp P2 segment that is comprised of 370 bp of 5'-flanking region and 125 bp of transcribed region of Exon X.

Prevalence and correlates of physical abuse in Hong Kong Chinese adolescents: a population-based approach

OBJECTIVE

The objectives were to estimate the prevalence and correlates of physical abuse-related outcomes in the family setting in Hong Kong's adolescent population.

METHOD

A cross-sectional study design was used. A randomly selected sample of 3,355 secondary school students in Kwai Tsing District of Hong Kong was surveyed. The response rate was 98%.

RESULTS

The prevalence rates of corporal punishment, being beaten by parents for no apparent reason, being beaten to injury by family members in the past 3 months and any one of the above three were 4.9% (95% CI, 4.2% to 5.6%), 2.0% (95% CI, 1.5% to 2.5%), 1.1% (95% CI, .98% to 1.2%) and 6.6% (95% CI, 5.7% to 7.5%), respectively. Students who had experienced the above physical abuse-related outcomes were at a significant disadvantage for a wide range of morbidity indicators, including self-perceived bad health, anxiety and stress, somatic illnesses (such as asthma and epigastric pain), injuries and accidents, and hospitalization. They were more likely to have poor familial relations and coping skills, and to take up habits which potentially put their health at risk, such as smoking, alcohol consumption, and fighting with others.

CONCLUSIONS

Our prevalence estimates of physical abuse in the family setting for a student population in Hong Kong is an improvement over previous local estimates of physical abuse occurrence, which were mainly based on case notifications and clinical samples. The results also show that the abused adolescents are growing up in an environment filled with physical, psychological, and familial adversities.

Axial and peripheral bone mineral acquisition: a 3-year longitudinal study in Chinese adolescents

We performed a 3-year longitudinal study of a group of 179 healthy Chinese adolescents (92 boys and 87 girls) aged from 12 to 16 years to determine the effects of puberty, physical activity, physical fitness, and calcium intake on the acquisition of bone mass. At yearly intervals for 3 consecutive years we recorded nutrition, calcium intake and anthropometric measurements, and assessed pubertal status according to Tanner. Bone mass of the lumbar spine was determined by dual-energy X-ray absorptiometry and radial bone mass by single-photon absorptiometry. Physical fitness and level of physical activity were assessed and muscle strength and power determined by isokinetic testing. Peripheral bone mass correlated with axial skeleton bone mass. Age, pubertal staging, physical fitness and muscle strength were significantly associated with bone mass increments on cross-sectional univariate and regression analysis. Longitudinal regression analysis showed that the most important factor affecting bone mass accretion in adolescents in both sexes was their pubertal stage. In boys, bone mass increment throughout the study was greater in children who were already in the advanced pubertal stages on entering the study than in those who started puberty in year 2 or 3 of the study. The percentage change in bone mineral content of the forearm and in bone mineral density of the lumbar spine was greater than 25% in the advanced pubertal group as compared to around 20% in the less mature group. For girls, the reverse was true. The increment of bone mass during the study period was significantly greater in those who presented in the earlier pubertal stages than in those who were at the more advanced stage of puberty on entry into the study. There was no significant effect of calcium intake and physical activities on the bone mass accretion.

CONCLUSION

In Chinese adolescents, bone mineral accretion at adolescence is not influenced by exercise, level of physical fitness and calcium intake. In both sexes, and especially in girls, to optimally increase bone mass, regular physical exercise programmes should be instituted well before the onset of puberty rather than at or after it. Once puberty starts, these interventions may have no or only limited effect.

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.

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.

Tarsal tunnel syndrome: a review of the literature

Tarsal tunnel syndrome is an uncommon clinical entity. This article will review the published reports on tarsal tunnel syndrome with respect to its anatomy, cause, pathophysiology, clinical presentation, diagnosis, treatment, and results of treatment in an attempt to improve understanding of this problem.

Effects of tarsal tunnel release and stabilization procedures on tibial nerve tension in a surgically created pes planus foot

An in vitro study was performed on 11 cadaver legs to study the effects of tarsal tunnel release, distraction calcaneocuboid arthrodesis, and triple arthrodesis on tibial nerve tension in surgically created pes planus feet. Baseline tibial nerve tension was measured during maximal dorsiflexion, eversion, combined dorsiflexion-eversion, and cyclical load with varying degrees of internal rotation. These measurements were repeated on the same leg after each surgical procedure. This study demonstrated that a tarsal tunnel release significantly increased nerve tension during eversion, dorsiflexion-eversion, and cyclical load compared with the pes planus foot. Both triple arthrodesis and distraction calcaneocuboid arthrodesis were effective at decreasing tibial nerve tension; the former was more effective than the latter. Procedures producing skeletal instability, such as ligament release producing a pes planus deformity and a tarsal tunnel release, increased tibial nerve tension. Procedures that corrected deformity and increased stability decreased tibial nerve tension. If increased tibial nerve tension plays a role in the pathophysiology of tarsal tunnel syndrome, then this needs to be considered for treatment of patients with this syndrome.

Determinants of axial and peripheral bone mass in Chinese adolescents

OBJECTIVE

To determine the relation of puberty, physical activity, physical fitness, and calcium intake with bone mineral content (BMC) of the distal radius, and on bone mineral density (BMD) of the L2 to L4 vertebrae in a group of healthy Chinese adolescents.

DESIGN

Cross sectional survey.

SUBJECTS

A group of 179 healthy Chinese adolescents (92 boys and 87 girls) aged 12 to 13 years enrolled in the first year of the Tii Junior High School in Shatin, Hong Kong. Ninety four of the pupils enrolled were in the physical education major class (PE), and the other 85 were in the art major class (ARTS).

MAIN OUTCOME MEASURES

Correlation of BMC of the distal radius and BMD of the L2 to L4 vertebrae with level of physical activity, physical fitness (isometric and isokinetic), muscle strength of the upper and lower limb, and calcium intake.

RESULTS

BMC of the distal radius and BMD of the L2 to L4 vertebrae were significantly positively correlated. Univariate and regression analysis showed that age, pubertal staging, physical fitness, and muscle strength were significantly associated with bone mass in a positive way. Calcium intake and type of sport practised did not exert a significant influence on BMC of the distal radius and BMD of the L2 to L4 vertebrae in boys. The results for the BMD of the L2 to L4 vertebrae were similar in girls and boys; however, in girls, the BMC of the distal radius had a negative correlation with calcium intake. Physical fitness was a significant positive predictor of BMD of the L2 to L4 vertebrae.

CONCLUSIONS

Among Chinese adolescents bone mass was positively influenced by certain measures of physical fitness as well as by age, weight, and pubertal stage.

A new look at the sequential development of elbow-ossification centers in children

The pattern and sequence of ossification of the six secondary ossification centers around the elbow in the child were mainly derived from studies done >30 years ago. This series reexamined the sequence and pattern based on a cross-sectional study of the elbow radiographs of 1,577 Chinese children with elbow injuries; age range, from newborn to 17 years. The ratio of girls to boys was 1:2. Each child had a radiograph of the normal and the injured elbow giving a total of 3,154 radiographs. A percentile chart of ossification was constructed for each of the ossification centers in both sexes for easy reference. No differences in the timing and ossification pattern were found between the right and left elbow or between the normal and injured elbow in this study. The sequence of ossification in both boys and girls was found to be the same (i.e., the capitulum first, followed by the radial head, medial epicondyle, olecranon, trochlea, and last, the lateral epicondyle). The ages at which 50% of the girls were found to have positive radiologic ossification for each of these centers were ages 1, 5, 5, 9, 9, and 10 years, respectively. In boys, with the exception of the capitulum, an average delay of 2 years was found in each of the ossification centers, although the sequence remained similar.

Sodium and potassium intakes and blood pressure in Chinese adults in Hong Kong: A comparison with southern China

The ranges of sodium and potassium intake and their relationship to blood pressure were studied in 126 healthy Chinese subjects (42 men, 84 women) aged between 20 and 65 years living in Hong Kong. An average of three blood pressure measurements and one to three 24-hour urinary sodium and potassium outputs were used to characterize an individual's blood pressure, and sodium and potassium intake, respectively. The average sodium and potassium intakes were 145 and 40 mmol/day in men and 135 and 41 mmol/day in women. When compared with subjects of similar age in southern China, Chinese in Hong Kong excreted 20% less sodium but 40% more potassium and had a lower systolic blood pressure (113 vs 118 mmHg in men, 106 vs 112 mmHg in women). It should be remembered that the Hong Kong subjects were heavier and were under more urban stress, both of which would be expected to be associated with higher blood pressure. The findings from this pilot study are compatible with a positive association between sodium intake and blood pressure and/or an inverse association between potassium intake and blood pressure.

Body mass index reference curves for Chinese children

The Hong Kong Growth Survey 1993 provided data for the construction of reference curves for body mass index (BMI) of Chinese children from birth to 18 years. Data on weight and height was obtained from 11797 boys and 12168 girls. The LMS method was used to smooth the percentile curves. These curves showed a definite physiological rising pattern to a peak at 6 months, then fell to a trough at 6 years, before another rise towards adulthood. Compared to published reports from the US, Britain, France and Sweden, Hong Kong Chinese children, particularly the girls, were less obese. In the first 2 years median curves of Hong Kong Chinese were similar to those of the Japanese.

The effects of foot position and load on tibial nerve tension

Patients with tarsal tunnel syndrome of unknown etiology do poorly after surgical decompression. Although surgical decompression addresses the soft tissue constraints, it ignores the role of osseous support. Some authors have suggested that a pes planus deformity (i.e., valgus hindfoot and abducted forefoot) is an unrecognized cause of tarsal tunnel syndrome due to increased tibial nerve tension. An in vitro study was performed on nine cadaveric feet to determine the effects of foot position and load on tibial nerve tension. Tensile forces placed through the tibial nerve were measured when the foot was placed in dorsiflexion, eversion, combined dorsiflexion-eversion, and then under cyclical load and increasing internal rotation at 5 degrees increments from 0 degrees to 20 degrees. The nerve tension was reassessed after the creation of a pes planus deformity under the previous conditions. Tibial nerve tension in the stable and unstable foot was significantly increased by eversion, dorsiflexion, and combined dorsiflexion-eversion. Tibial nerve tension was significantly greater in an unstable foot when compared with a stable foot during eversion, dorsiflexion, and combined dorsiflexion-eversion. In the stable foot, tibial nerve tension was significantly increased during axial loading with increasing internal rotation when compared with 0 degrees rotation. The increased tibial nerve tension in the stable foot was significant with increasing internal rotation when 0 degrees was compared with 10 degrees, 15 degrees, and 20 degrees. In the unstable foot, the tibial nerve tension was significantly increased with increasing internal rotation compared with the nerve tension at 0 degrees of rotation. The increased tibial nerve tension in the unstable foot was significant with increasing internal rotation when 0 degrees was compared with 5 degrees, 10 degrees, 15 degrees, and 20 degrees. When stability of the foot and internal rotation were compared independently, each factor increased tibial nerve tension. However, these factors acting together did not significantly compound the increase in nerve tension. This study demonstrates that tibial nerve tension is increased in an unstable foot compared with a stable foot during eversion, dorsiflexion, combined dorsiflexion-eversion, and cyclical load with increasing internal rotation.

Secular trend in the sexual maturation of southern Chinese girls

In 1993, a cross-sectional study of sexual maturation of normal Chinese schoolgirls was performed in Hong Kong. The aim of the study was to obtain an up-to-date reference for normal pubertal development in Chinese girls. Breast development was assessed in 3749 girls aged 7-19 y, and pubic hair rating was assessed in 3745 girls. Menstrual status was recorded in 6467 girls over 6 y of age. The median age of onset of puberty as indicated by breast stage II or above was 9.78 (95% CI 9.70-9.85) y. The median age of onset of pubic hair development was 11.64 (95% CI 11.56-11.72) y. The median age of menarche was 12.38 (95% CI 11.98-12.78) years. Percentile values for the age at which each puberty staging appeared were constructed and incorporated into the height-for-age charts. When comparison is made with similar studies done in 1962 and 1979, a significant downward secular trend in sexual maturation is observed (p < 0.01). Except for breast development the downward secular trend in sexual maturation appears to be diminishing and may be coming to a halt in the Chinese girls in Hong Kong. Their median ages of sexual maturation are now among one of the earliest medians recorded in the world population studied.

Stigmata of hemorrhage in bleeding peptic ulcers: an interobserver agreement study among international experts

BACKGROUND

Stigmata of hemorrhage predict rebleeding and outcome of patients with bleeding peptic ulcers. There are variabilities in reported incidences of stigmata and their respective rebleeding risks. We sought to study the interobserver agreement among experts.

METHODS

Between June 1994 and July 1994, 100 consecutive patients with bleeding peptic ulcers underwent videoendoscopy within 24 hours of their admissions. An edited videotape of these ulcers was compiled and sent to an international panel of 14 experts. They independently rated these ulcers exclusively into one of the six categories: spurting, oozing, nonbleeding visible vessel, adherent clot, flat pigmented spot, or clean based. Agreement between any two experts was expressed by a kappa estimate (kappa). Agreements over individual stigmata and a composite kappa estimate (kappa(w)) signifying overall agreement were also computed.

RESULTS

Out of the possible 91 pairwise kappa estimates among 14 experts, 35 (38.5%) were less than or equal to 0.40, indicating poor agreement. None of the kappa estimates was greater than 0.75. Composite kappa estimates for individual stigmata were as follows: spurting kappa = 0.664, oozing kappa = 0.420, nonbleeding visible vessel kappa = 0.342, adherent clot kappa = 0.426, flat pigmented spot kappa = 0.393, and clean-based ulcer kappa = 0.371. The weighted kappa estimate was 0.426.

CONCLUSION

Agreement between experts was poor in more than a third of occasions. Although the overall interobserver agreement was fair (0.4 < kappa < 0.75), agreements for nonbleeding visible vessels, flat pigmented spots, and clean-based ulcers were poor.

Expression of beta-galactoside alpha 2,6-sialyltransferase does not alter the susceptibility of human colon cancer cells to NK-mediated cell lysis

The extent of processing of N-linked oligosaccharides and the sialylation of the target cell membranes has been positively correlated with resistance to lysis mediated by NK cells, but a conclusive evidence has never been reached. Colon cancer tissues express an increased activity of beta-galactoside alpha 2,6-sialyltransferase (EC 2.4.99.1, alpha 2,6ST), which catalyzed the addition of sialic acid in alpha 2,6-linkage to Gal beta 1,4GlcNAc (N-acetyllactosamine) sequences of glycoprotein N-linked chains. The resulting increased level of membrane alpha 2,6-sialylation appears to be related with a more invasive behavior of cancer cells. This phenomenon may depend on a decreased sensitivity of colon cancer cells to NK cells. To obtain conclusive evidence on the role played by sialylation of N-linked chains in determining the target cell susceptibility to NK-mediated lysis, human colon cancer cell lines not expressing sialyltransferases acting on N-linked chains were transfected with a rat alpha 2,6ST cDNA. Stable transfectants expressed different levels of alpha 2,6ST activity, were reactive with the Sambucus nigra lectin, specific for alpha 2,6-linked sialic acid, and compared with control transfectants, showed a remarkable decrease in the number of unsubstituted Gal beta 1,4GlcNAc terminal sequences. The NK susceptibility of these clones was found to be identical to that of control transfectants, either when unstimulated- or IL-2-stimulated lymphocytes were used as effectors. Neuraminidase treatment of target cells does not result in significant changes to NK susceptibility. Our data demonstrate that sialic acid alpha 2,6-linked to N-linked chains of target cell glycoproteins does not play a major role in recognition of the target by human NK cells.

Murine hepatic beta-galactoside alpha 2,6-sialyltransferase gene expression involves usage of a novel upstream exon region

ST6Gal I (beta-galactoside alpha 2,6-sialyltransferase, SiaT-1, ST6N, EC 2.4.99.1) mediates the attachment of the alpha 2,6-sialyl linkage common on N-linked glycans. Previous work suggests substantial inter-species conservation in SIAT1, the gene encoding ST6Gal I. In human and in rat, hepatic-specific SIAT1 transcription is initiated at Exon I. Here we report a surprising departure in the structural organization of the murine ST6Gal I gene. By a combination of primer extension analysis, 5'-RACE analysis, and analysis of genomic sequences, we show that the murine hepatic ST6Gal I mRNA contains a novel region 5' of Exon I. This novel sequence is encoded on a discrete upstream exon, Exon H. In contrast to human and rat hepatic ST6Gal I, the murine mRNA is transcriptionally initiated at the start of Exon H. Differential mRNA blot analysis indicates that transcripts containing Exon H sequences are preferentially expressed in liver.

Novel heterogeneity exists in the 5'-untranslated region of the beta-galactoside alpha 2,6-sialytransferase mRNAs in the human B-lymphoblastoid cell line, louckes

Multiple mRNA isoforms are generated from SIAT1, the gene encoding the beta-galactoside alpha 2,6-sialyltransferase (ST6Gal I, SiaT-1, ST6N, alpha 2,6ST). These isoforms are transcriptionally initiated from a number of physically distinct promoter regions. In human B-lymphocytic cells, two SIAT1 mRNA isoforms have been identified. In order to determine if additional SIAT1 mRNA isotypes exist, RNA from Louckes, a human cell line with the mature B-phenotype, was subjected to 5'-RACE analysis. In addition to the two previously characterized mRNA forms, three additional SIAT1 mRNA forms were identified. The new mRNA isoforms incorporate novel sequence blocks into their 5'-UT regions. The data strongly suggest that these novel sequence blocks originate from previously undocumented 5'-noncoding exons and are incorporated into mRNA by alternative splicing events and/or usage of additional transcriptional promoter regions. BLAST analysis reveals no similarity of these novel regions, Exons U, V, and W, to sequences in GenBank. The only exception is Exon V, which contains a portion of Alu, a repetitive element. The data suggest that two of these novel mRNA isotypes are likely to be minor components. However, one form may contribute significantly to the SIAT1 mRNA pool in Louckes cells.

Relationship between myopia and optical components--a study among Chinese Hong Kong student population

PURPOSE

To establish the prevalence and severity of myopia among the Chinese Hong Kong students and to study the relationship between myopia and optical components.

METHODS

One thousand and seventy-five freshmen of the 1993-1994 academic year in the Chinese University of Hong Kong underwent the eye examination including evaluation of refractive error, keratometry, and A-scan ultrasonic biometry. The data were analyzed with the SPSS/PC+4.01 statistical package.

RESULTS

The prevalence of myopia was 91.7% with the mean refraction being -4.00 +/- 2.64D in this young adult population. The statistical analyses demonstrated a significant correlation between refractive value and axial length of the globe (r = -0.78), vitreous length (r = -0.76), anterior chamber depth (r = -0.33), lens thickness (r = 0.13) and corneal curvature (r = 0.19).

CONCLUSION

The refractive status is mainly dependent on the axial length. In general, the higher the myopia was, the longer the eyeball, the deeper the anterior chamber, the steeper the cornea, and the thinner the lens would be.

Secular changes in standing height, sitting height and sexual maturation of Chinese--the Hong Kong Growth Study, 1993

In 1993 a territory-wide cross-sectional growth survey on 25,000 Chinese children from birth to 18 years was performed in Hong Kong. Compared to the last growth survey in 1963, definite secular changes were observed. There was an increase of final adult standing height of 3.6 cm in boys and 2.7 cm in girls, in which 1.8 cm and 0.5 cm respectively for boys and girls was accounted for by the sitting height. Thus most of the height increase had occurred in the leg length in girls, but in boys only half of it. The height difference was more marked during the pubertal years because secular change had brought about an earlier sexual maturation, including an advancement of median menarcheal age by 0.5 year, coupled with an earlier growth spurt. This paper also provides the first growth standards for Chinese from birth to 18 years, with percentile charts on both standing height and sexual maturation in boys and girls.