Biomedical subjects

L H Chiu

Publications and source records attributed to L H Chiu.

12 recordsLinked to original sources

PubMed2005

Motivation for nurses undertaking a post-registration qualification in Malaysia.

AIM: To present several key factors that motivated Malaysian registered nurses to undertake a post-registration degree through an Australian university. The overall research study, from which this paper is drawn, looked at the professional learning of Malaysian registered nurses and the subsequent impact on their careers. BACKGROUND: In Malaysia, the demand for a degree for Malaysian nurses provided the impetus for this offshore post-registration nursing programme, developed as a twinning venture between an Australian university and a Malaysian private institution. The degree programme was conducted largely in Malaysia with a 4-week residential block in Australia. METHODS: As this larger research study investigated the graduates' personal perspectives of their experiences of this post-registration degree programme, the case study approach was the appropriate methodological choice. Twelve Malaysian graduate nurses were recruited voluntarily from the first cohort of students who completed the Bachelor of Health Science-Nursing (post-registration) 5 years post graduation. Ethical procedures were observed. The data were collected through individual, semi-structured and focus interviews, which took place in Malaysia and were personally tape-recorded and transcribed by the researcher. FINDINGS: The motivation for formal learning emanated from the participants' personal and professional lives. Within these two domains, four separate but interrelated reasons emerged: work-related stimulation and self-growth; compliance with management requirements; professional advancement and keeping up with the profession; and availability and accessibility. However, in a culture where higher education is highly priced and yet scarce, the programmes' availability and accessibility were ultimate factors.

Australia↗

PubMed1998

Molecular characterization of hprt mutations from Chinese hamster ovary cells treated with 1-, 3-, and 6-nitrosobenzo[a]pyrene.

1-, 3-, and 6-nitrobenzo[a]pyrene (nitro-BaP) are environmental contaminants that can be metabolized to genotoxic derivatives by either nitroreduction or ring-oxidation. In this study, we examined the types of mutations produced by the primary nitroreduced metabolites, 1-, 3-, and 6-nitroso-BaP (NO-BaP) in the hprt gene of Chinese hamster ovary cells. RNA from 6-thioguanine-resistant mutants was reverse-transcribed to cDNA and the hprt coding sequence was amplified and sequenced. The mutational patterns produced by the three compounds exhibited extensive similarities: 1) base pair substitutions accounted for 67% (28/42) of 1-NO-BaP, 51% (26/51) of 3-NO-BaP, and 50% (11/22) of 6-NO-BaP mutations; 19-36% of the mutations were exon deletions and 14-18% were frameshifts; 2) most (64-84%) of the simple base pair substitutions occurred at G:C, mainly G:C-->T:A and G:C-->C:G transversions; 3) 98% (46/47) of the simple base pair substitutions at G:C had the mutated dG on the non-transcribed strand and 81% (38/47) were located with the mutated dG flanked 3' by at least one purine; and 4) most simple base pair substitutions (48/62, 77%) occurred in exons 2, 3, and 8 of the hprt gene. Although there were no significant differences among the mutation profiles of the NO-BaPs, a significant difference did exist between the mutation pattern produced by 3-NO-BaP and the mutation pattern previously determined for the ring-oxidized product of 3-nitro-BaP metabolism, trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9, 10-tetrahydro-3-nitrobenzo[a]pyrene. This observation indicates that differences in the structures of closely related adducts can be important enough to have an effect on mutation profiles.

Animals↗

PubMed1998

Structure, tumorigenicity, microsomal metabolism, and DNA binding of 7-Nitrodibenz[a,h]anthracene.

It has been previously proposed that a nitropolycyclic aromatic hydrocarbon (nitro-PAH) with its nitro functional group perpendicular or nearly perpendicular to the aromatic moiety exhibits lower tumorigenicity than the corresponding parent aromatic hydrocarbon. We also hypothesized that reduction of the nitro group is not involved, or contributed less significantly in the metabolic activation of this class of nitro-PAHs. To verify this hypothesis, we selected 7-nitrodibenz[a,h]anthracene (7-NDB[a,h]A) for study. The X-ray crystallographic structure of 7-NDB[a,h]A was determined and indicated that the dihedral angle between the nitro functional group and the aromatic dibenz[a,h]anthracenyl moiety was 80.6 degrees, indicating the nitro group preferentially adopts a nearly perpendicular orientation. The tumorigenicity of 7-NDB[a,h]A and dibenz[a,h]anthracene (DB[a,h]A) was determined in the male B6C3F1 neonatal mouse. Mice were administered ip injections of 1/7, 2/7, and 4/7 of the total dose of 7-NDB[a,h]A (400 nmol in 35 microL of DMSO per mouse) within 24 h of birth and at 8 and 15 days of age, respectively, and sacrificed at 12 months of age. DB[a,h]A induced 78 and 96% hepatocellular adenomas and carcinomas, respectively. However, 7-NDB[a,h]A induced only 50 and 8% hepatocellular adenomas and carcinomas compared with the 8 and 4% hepatocellular adenomas and carcinomas induced by the solvent vehicle, DMSO. Aerobic metabolism of 7-NDB[a,h]A by liver microsomes of 15-day old male B6C3F1 neonatal mice resulted in trans-3,4-dihydroxy-3, 4-dihydro-7-nitrodibenz[a,h]anthracene (7-NDB[a,h]A trans-3, 4-dihydrodiol) and trans-10,11-dihydroxy-10, 11-dihydro-7-nitrodibenz[a,h]anthracene (7-NDB[a,h]A trans-10, 11-dihydrodiol) as predominant metabolites. Under anaerobic conditions, 7-NDB[a,h]A was not metabolized (nitroreduced). The DNA adduct levels in liver and lung tissues of male B6C3F1 mice treated with 7-NDB[a,h]A and sacrificed 24 h and 6 days after final dosing were determined by 32P-postlabeling/TLC. In all cases, the DNA adducts derived from 7-NDB[a,h]A trans-3,4-dihydrodiol and 7-NDB[a, h]A trans-10,11-dihydrodiol were formed. These results suggest that both of the metabolites, 7-NDB[a,h]A trans-3,4-dihydrodiol and 7-NDB[a,h]A trans-10,11-dihydrodiol, are involved in the metabolic activation of 7-NDB[a,h]A, leading to tumor induction in the neonatal mouse. Thus, our results described in this paper support our hypotheses that a nitro-PAH with a perpendicular nitro orientation exhibits lower tumorigenicity than the corresponding parent PAH and that nitroreduction contributes less significantly in the metabolic activation.

Animals↗

PubMed1998

Teenage attempted suicide in Hong Kong.

We examined the epidemiological profiles and characteristics of suicide attempters admitted to the Accident and Emergency Department of a regional hospital in Hong Kong (Princess Margaret Hospital) in the period from January to December 1995. These consisted of 101 adolescents (16 males and 85 females) aged between 10 to 24 years. There were significantly more female attempters than males, especially in the group aged 10-19, which had a male-to-female ratio of suicide rates of 1:11. Most of the methods used were nonlethal; the attempters were not serious enough and had no real intention to die. The use of painkillers and sleeping pills was most common. The main precipitating factor was interpersonal problems, for example, relationships, spousal and parental problems, especially among teenage girls. More than 90% of the cases stayed at the hospital for further observation, the mean length of stay in the hospital being 3.3 days. The potential health cost to the hospital system was around HK $11.7 million. Underestimating the prevalence of attempted suicides in Hong Kong could be a serious matter.

Adolescent↗

PubMed1997

Characterization of DNA adducts in Chinese hamster ovary cells treated with mutagenic doses of 1- and 3-nitrosobenzo[a]pyrene and the trans-7,8-diol-anti-9,10-epoxides of 1- and 3-nitrobenzo[a]pyrene.

The environmental contaminants 1- and 3-nitrobenzo[a]pyrene (1- and 3-nitro-BaP) are mutagens in Chinese hamster ovary (CHO) cells with exogenous metabolic activation. Previous studies demonstrated the potent direct-acting mutagenicity of the oxidized metabolites, trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydro-1-nitrobenzo[a] pyrene (1-NBaPDE) and trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9, 10-tetrahydro-3-nitrobenzo[a]pyrene (3-NBaPDE), and the partially nitroreduced metabolites, 1- and 3-nitrosobenzo[a]pyrene (1- and 3-NO-BaP). In this study, we have identified the major adduct formed by incubation of calf thymus DNA with 1-NBaPDE and used this standard in conjunction with other adduct standards to characterize the 32P-postlabeled DNA adducts produced by 1- and 3-nitro-BaP metabolites in CHO cultures. The major adduct from 1-NBaPDE exposure was 10-(deoxyguanosin-N2-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-1- nitrobenzo[a]pyrene; from 3-NBaPDE, 10-(deoxyguanosin-N2-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-3- nitrobenzo[a]pyrene; from 1-NO-BaP, 6-(deoxyguanosin-N2-yl)-1-aminobenzo[a]pyrene; and from 3-NO-BaP, 6-(deoxyguanosin-N2-yl)-3-aminobenzo[a]pyrene. For comparison, the adducts formed by trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene and the related nitroreduced derivative 6-nitrosobenzo[a]pyrene were also examined. The nitrobenzo[a]pyrene DNA adducts described in this study are proposed to be involved in the mutagenicity of 1- and 3-nitro-BaP upon either oxidative or reductive metabolism.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed1990

The relationship of career goal and self-esteem among adolescents.

The purpose of this study was to investigate the relationship of career goal and self-esteem among adolescents. A sample of 221 high school sophomores and juniors was administered the Rosenberg Self-Esteem Scale (RSE). Their teachers also were asked to rate the students' self-esteem using the Self-Esteem Rating Scale for Children (SERSC). It was found that, on both the RSE and SERSC, adolescents with some career goals had significantly higher self-esteem than did those without any career goal.

Adolescent↗

PubMed1988