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Biomedical subjects

S Wong

Publications and source records attributed to S Wong.

At least 73 records · Page 4Linked to original sources
PubMed2000

Photodynamic therapy-mediated oxidative stress as a molecular switch for the temporal expression of genes ligated to the human heat shock promoter.

Oxidative stress associated with photodynamic therapy (PDT) is a transcriptional inducer of genes encoding stress proteins, including those belonging to the heat shock protein (hsp) family. The efficiency of PDT to function as a molecular switch by initiating expression of heterologous genes ligated to the human hsp promoter was examined in the present study. Selective and temporal reporter gene expression was documented after PDT in mouse radiation-induced fibrosarcoma cells stably transfected with recombinant vectors containing an hsp promoter ligated to either the lac-z or CAT reporter genes and in transfected radiation-induced fibrosarcoma tumors grown in C3H mice. Hyperthermia treatments were included as a positive control for all experiments. Expression vectors containing either human p53 or tumor necrosis factor (TNF)-alpha cDNA under the control of an hsp promoter were also constructed and evaluated. A p53 null and TNF-alpha-resistant human ovarian carcinoma (SKOV-3) cell line was stably transfected with either the p53 or TNF-alpha constructs. Inducible expression and function of p53 as well as inducible expression, secretion, and biological activity of TNF-alpha were documented after PDT or hyperthermia in transfected SKOV cells. These results demonstrate that PDT-mediated oxidative stress can function as a molecular switch for the selective and temporal expression of heterologous genes in tumor cells containing expression vectors under the control of an hsp promoter.

Animals↗
PubMed2000

Simultaneous quantitation of two orchid viruses by the TaqMan real-time RT-PCR.

Simultaneous quantitation of two orchid viruses, cymbidium mosaic potexvirus (CymMV) and odontoglossum ringspot tobamovirus (ORSV), were carried out using the TaqMan((R)) real-time RT-PCR, a novel detection technique that combines RT-PCR with the power of fluorescent detection. Four TaqMan((R)) probes were synthesized, targeting at the RNA-dependent RNA polymerase (RdRp) and coat protein (CP) genes of both viruses. The reporter dye FAM (6-carboxyfluorescein) was used to label the 5' terminus of probes specific to CymMV, while TET (tetrachloro-6-carboxyfluorescein) was used for the ORSV probes. TAMRA (6-carboxy-tetramethyl-rhodamine), which was attached at the 3' terminus of each probe, was used as the universal quencher. With increasing amounts of standard RNA templates, the respective threshold cycle (C(T)) values were determined and a linear relationship was established between these C(T) values and the logarithm of initial template amounts. The amounts of starting templates in mixed-infected Oncidium flowers and leaves were estimated from the standard curves. As little as 10(4) copies or 5 fg each of CymMV and ORSV could be detected simultaneously with either the RdRp or CP gene as the target. This system offers a sensitive, high throughput and rapid method for plant virus detection.

Capsid↗
PubMed2000

Digital measurement of torsional eye movement due to postural change and its effect on reading performance.

PURPOSE: Posture induced torsional eye movements have rarely been investigated. The current study made use of digital imaging technology to measure the cycloduction resulting from postural change. The effect of cycloduction on reading performance was also investigated. METHODS: Thirty subjects were recruited and pictures of the right eye were captured using a digital camera at three postures, i.e. sitting, 90 degrees tilted to the right and 90 degrees tilted to the left. With the identification of a conjunctival landmark, torsional eye movement was measured. The subjects were then required to read a custom designed near chart while in those three postures, the reading card being rotated 90 degrees clockwise or 90 degrees anti-clockwise, to match with the tilting of the head. The reproducibility of the torsional eye movement and reading performance measure was determined in 12 of those 30 subjects. RESULTS: Incycloduction was induced when tilting to the right and excycloduction when tilting to the left. This method was found to be reproducible with the 95% confidence limits of 0.80 degrees between visits. The mean incycloduction induced was 6.50 degrees (SD 1.51 degrees ) and 6.41 degrees (SD 1.46 degrees ) for excycloduction. No significant difference in amount was demonstrated (paired t-test: t = 0.624, P = 0.538). No significant difference was found in the reading scores at various postures (Repeated measures ANOVA: df = 2, F = 1.881, P = 0.162). CONCLUSIONS: The results presented here demonstrate that we have developed an objective and instantaneous method with good precision, which could be applied in other studies that require the measurement of torsional eye movements. The induced cycloduction did not affect the reading performance.

Adolescent↗
PubMed2000

Effects of LPS and IL-6 on oxytocin receptor in non-pregnant and pregnant rat uterus.

PROBLEM: Little is known regarding the regulation of the timing of parturition. Recent evidence suggests an interaction between the immune system and uterine contractility in late gestation. METHOD: Pregnant rats were treated with LPS in vivo in attempts to establish a model of premature parturition induced by the pro-inflammatory response. Uterine explants were incubated in vitro to determine the effects of IL-6 on uterine synthesis of oxytocin (OT) and its receptor (OTR). RESULTS: LPS injection was quite toxic to pregnant rats and gave extremely variable results. In animals that delivered, there was a marked increase in the uterine concentrations of OTR and OTR mRNA. There was no consistent effect regarding the timing of parturition. IL-6 caused a significant increase in the concentration of OTR mRNA in uterine explants from pregnant rats but not in tissues from non-pregnant animals. CONCLUSION: Rat uterine concentrations of OTR are regulated by IL-6. Pro-inflammatory cytokines may stimulate uterine contractility in late gestation rat uterine tissues through a mechanism involving stimulation of OTR.

Animals↗
PubMed2000

Acoustic characteristics of English fricatives.

This study constitutes a large-scale comparative analysis of acoustic cues for classification of place of articulation in fricatives. To date, no single metric has been found to classify fricative place of articulation with a high degree of accuracy. This study presents spectral, amplitudinal, and temporal measurements that involve both static properties (spectral peak location, spectral moments, noise duration, normalized amplitude, and F2 onset frequency) and dynamic properties (relative amplitude and locus equations). While all cues (except locus equations) consistently serve to distinguish sibilant from nonsibilant fricatives, the present results indicate that spectral peak location, spectral moments, and both normalized and relative amplitude serve to distinguish all four places of fricative articulation. These findings suggest that these static and dynamic acoustic properties can provide robust and unique information about all four places of articulation, despite variation in speaker, vowel context, and voicing.

Adult↗
PubMed2000

Extended analysis of the in vitro tropism of porcine endogenous retrovirus.

We previously reported that mitogenic activation of porcine peripheral blood mononuclear cells resulted in production of porcine endogenous retrovirus(es) (PERV[s]) capable of productively infecting human cells (C. Wilson et al., J. Virol. 72:3082-3087, 1998). We now extend that analysis to show that additional passage of isolated virus, named here PERV-NIH, through a human cell line yielded a viral population with a higher titer of infectious virus on human cells than the initial isolate. We show that in a single additional passage on a human cell line, the increase in infectivity for human cells is accounted for by selection against variants carrying pig-tropic envelope sequences (PERV-C) as well as by enrichment for replication-competent genomes. Sequence analysis of the envelope cDNA present in virions demonstrated that the envelope sequence of PERV-NIH is related to but distinct from previously reported PERV envelopes. The in vitro host range of PERV was studied in human primary cells and cell lines, as well as in cell lines from nonhuman primate and other species. This analysis reveals three patterns of susceptibility to infection among these host cells: (i) cells are resistant to infection in our assay; (ii) cells are infected by virus, as viral RNA is detected in the supernatant by reverse transcription-PCR, but the cells are not permissive to productive replication and spread; and (iii) cells are permissive to low-level productive replication. Certain cell lines were permissive for efficient productive infection and spread. These results may prove useful in designing appropriate animal models to assess the in vivo infectivity properties of PERV.

Amino Acid Sequence↗
PubMed2000

Oxoproline kinetics and oxoproline urinary excretion during glycine- or sulfur amino acid-free diets in humans.

L-5-oxoproline (L-5-OP) is an intermediate in glutathione synthesis, possibly limited by cysteine availability. Urinary 5-OP excretion has been proposed as a measure of glycine availability. We investigated whether 5 days of dietary sulfur amino acid (SAA-free) or glycine (Gly-free) restriction affects plasma kinetics of 5-OP and urinary excretion of L- and D-5-OP in 6 healthy men. On day 6, L-5-[1-(13)C]oxoproline and [3,3-(2)H(2)]cysteine were infused intravenously for 8 h (3 h fast/5 h fed). In a control study (adequate amino acid mixture), plasma oxoproline fluxes were 37.8 +/- 13.8 (SD) and 38.4 +/- 14.8 micromol x kg(-1) x h(-1); oxidation accounted for 85% of flux. Cysteine flux was 47.9 +/- 8.5 and 43.2 +/- 8.5 micromol x kg(-1) x h(-1) for fast and fed phases, respectively. Urinary excretion of L- and D-5-OP was 70 +/- 34 and 31.1 +/- 13.3 micromol/mmol creatinine, respectively, during days 3-5, and 46.4 +/- 13.9 and 22.4 +/- 8.3 micromol/mmol over the 8-h tracer study. The 5-OP flux for the Gly-free diet was higher (P = 0. 018) and tended to be higher for the SAA-free diet (P = 0.057) when compared with the control diet. Oxidation rates were higher on the Gly-free (P = 0.005) and SAA-free (P = 0.03) diets. Cysteine fluxes were lower on the the Gly-free (P = 0.01) and the SAA-free diets (P = 0.001) compared with the control diet. Rates of L-5-OP excretion were unchanged by withdrawal of SAA or Gly for 5 days but increased on day 6 (P = 0.005 and P = 0.019, respectively). Thus acute changes in the dietary availability of SAA and Gly alter oxoproline kinetics and urinary 5-OP excretion.

Adult↗
PubMed2000

Outcome of an institutional sexual offender treatment program: a comparison between treated and matched untreated offenders.

Data from a sexual offender treatment program operated by the Correctional Service of Canada at the Regional Psychiatric Center (Saskatoon) supported the conclusion that cognitive behavioral treatment can reduce sexual offense recidivism. The study compared 296 treated and 283 untreated offenders followed for a mean of 6 years after their release. An untreated comparison subject was located for each treated offender on three dimensions: (a) age at index offense, (b) date of index offense, and (c) prior criminal history. Data were analyzed using tests of proportion, survival analysis, and analysis of offender Criminal Career Profiles. Over a mean follow-up period of almost 6 years, convictions for new sexual offenses among treated offenders were 14.5% versus 33.2% for untreated offenders. During the follow-up period, 48% of treated offenders remained out of prison compared to 28.3% of untreated offenders. Time series comparisons of treated and comparison samples also showed that treated men reoffended at significantly lower rates after 10 years. A Criminal Career Profile (CCP) was constructed by taking the Age at First Conviction and plotting the offender's successive lengths of time free against time incarcerated. Pre- and posttreatment slopes of the CCP were lower for both groups posttreatment; however, the degree of change was significantly greater for the treated group, indicating a greater reduction in criminal activity among these offenders. Taken together, the results of all three analytic techniques supported the efficacy of appropriate correctional treatment for effective reduction of recidivism.

Adult↗
PubMed2000

Recalls of foods and cosmetics due to microbial contamination reported to the U.S. Food and Drug Administration.

In the U.S., food product recalls serve as an important intervention in stemming the consumption of food products contaminated with infectious disease agents. We summarize the number and nature of foods and cosmetics recalled as a result of microbial contamination reported to the U.S. Food and Drug Administration (FDA) for the period 1 October 1993 through 30 September 1998. During this period, microbial contamination of food and cosmetic products was the leading cause for recalls, accounting for a total of 1,370 recalls (36% of all products recalled). Listeria monocytogenes accounted for the greatest number of food products recalled because of microbial contamination, whereas Pseudomonas aeruginosa was the most common microbe associated with recalls of cosmetic products. Dairy products, followed by seafood and pastry items, were the types of products most often associated with recalls due to microbial contamination. The FDA was the entity most often responsible for detecting microbial contamination of foods and cosmetics (33% of all such recalls), followed by state regulatory agencies (24%), and manufacturers/retailers (21%). Nineteen percent of recalls were associated with at least one reported case of illness. Salmonella was the pathogen most often implicated in reports of illness associated with these recalled products.

Animals↗
PubMed2000

The unmet health needs of America's children.

OBJECTIVE: Unmet need for health care is a critical indicator of access problems. Among children, unmet need for care has special significance inasmuch as the failure to obtain treatment can affect health status and functioning in the near- and long-term. The purpose of this study was to present current prevalence estimates and descriptive characteristics of children with unmet health needs using nationally representative household survey data. METHODS: We analyzed 4 years of National Health Interview Survey data spanning 1993 through 1996. Our analysis included 97 206 children <18 years old. Measures of unmet need for medical care, dental care, prescription medications, and vision care were obtained from an adult household member (usually the mother) responding for the child. Bivariate and multivariate analyses were used to assess the degree to which unmet need was related to the demographic and socioeconomic characteristics of the child and family. RESULTS: Overall, 7.3% (4.7 million) of US children experienced at least 1 unmet health care need. Dental care was the most prevalent unmet need. After adjustment for confounding factors, near-poor and poor children were both about 3 times more likely to have an unmet need as nonpoor children (adjusted odds ratio [95% confidence interval] = 2.89 [2.52, 3.32], 3.0 [2.53, 3.56], respectively). Uninsured children were also about 3 times more likely to have an unmet need as privately insured children (adjusted odds ratio [95% confidence interval] = 2. 92 [2.58, 3.32]). CONCLUSIONS: Despite the nation's great wealth, unmet health needs remain prevalent among US children. A combined public policy that addresses financial and nonfinancial barriers to care is required to reduce the prevalence of unmet need for health care.

Adolescent↗
PubMed1999

Synthesis and structure activity relationships of novel small molecule cathepsin D inhibitors.

Cathepsin D, a lysosomal aspartyl protease, has been implicated in the pathology of Alzheimer's disease as well as breast and ovarian cancer. A weakly active cathepsin D inhibitor was identified by high throughput screening. Subsequent optimization led to the discovery of a new class of small molecule inhibitors of this enzyme, culminating with the sulfonamide 13 (IC50 = 250 nM).

Cathepsin D↗
PubMed1999

Increased generation of CD8+ T cell clones in p53 mutant mice.

Very few cultured CD8+ T cell clones can normally be obtained from a single mouse and maintained in long-term culture. To improve the yield, we immunized p53 mutant mice with peptides of Sendai virus (FAPGNYPAL) and influenza virus (ASNENMETM) origin. Substantially more clones could be derived from p53-/- mice than from similarly treated wild-type mice (p53+/+); an intermediate yield was obtained from heterozygous mice (p53+/-). CTL lines or clones from p53-/- mice exhibited greater proliferative activity and resistance to gamma-irradiation than those from p53+/+ mice, and were cytolytically potent.

Animals↗
PubMed1999

Is physical activity as effective in reducing risk of cardiovascular disease as estrogen replacement therapy in postmenopausal women?

Coronary heart disease (CHD) is known as a disease of postmenopausal women. While hormone replacement therapy is recommended increasingly to postmenopausal women for the prevention of CHD, the potential impact of non-pharmacologic interventions on cardiovascular disease reduction has been largely unexplored. The purpose of this article is to develop the understanding of the research literature on three risk factors by which estrogen and physical activity, a non-pharmacologic intervention, may confer cardiovascular protection in postmenopausal women. Three risk factors are lipoproteins, systolic pressure, and changes in the vascular endothelial functions. Effects of estrogen and physical activity on these biological factors are compared.

Cardiovascular Diseases↗
PubMed1999

Contribution of basic sciences to academic success in nursing education.

The present study set out to examine the contribution of basic sciences to academic success in nursing education. A number of regression analysis models were used to analyze the relationships among predictor and criterion variables. Data analyses showed that basic sciences and grade point average of nursing courses in year 3 and 4 contributed significantly to student success in the program (p < 0.001). The cumulative grade point average was the only significant predictor of the licensure examination success. These results suggested that the content in science courses may have unique relevance to nursing and, therefore, may have a factor in their predictive value.

Achievement↗
PubMed1999

Chinese migrants' mental health and adjustment to life in New Zealand.

OBJECTIVE: The purpose of this study was to identify and assess the relative importance of predictors of the self-rated adjustment and psychiatric morbidity of recent Chinese migrants. METHOD: Chinese migrants (n = 271) living in Auckland and aged 15 years or older completed a postal questionnaire that included the Chinese Health Questionnaire (CHQ). The majority of respondents came from Hong Kong and Taiwan. RESULTS: Most respondents did not report major adjustment problems. The psychiatric morbidity rate was 19%. Major predictors of experiencing problems included rejection by locals, being aged 26-35 years or over 45 years and low English proficiency. Major predictors of poor adjustment included unemployment, low English proficiency, lack of university education, younger age, shorter residency, expectations not met and regrets about coming to New Zealand. Predictors of minor mental disorder included regretting coming, female gender and younger age. For migrants resident 2 years or less, unemployment and underemployment were additional risk factors. Mothers with absent husbands and young people with absent parents also had elevated rates of mental disorder. CONCLUSIONS: Although the overall prevalence of mental disorder for this sample of recent migrants appears to be similar to that of the general population, significant risk factors were identified. The findings extend knowledge of the adjustment and the mental health of migrants and provide potential focal points for primary and secondary prevention interventions.

Adolescent↗
PubMed1999

Australia's breast surgery workload is changing: comparison of a metropolitan and a rural hospital.

BACKGROUND: Breast cancer is a common disease in our community and its incidence is increasing. As a result of the improvements in community awareness and introduction of screening, patients are being diagnosed with earlier breast cancer and with a higher incidence of pre-invasive disease. Improvements in radiology, often coupled with minimally invasive diagnostic modalities, have lessened the requirement for open diagnostic biopsies and also reduced the number of operations for benign breast disease. METHODS: An audit of the surgical workload at Prince of Wales/Prince Henry Hospitals and Tamworth Base Hospital was conducted to document and compare the above changes in the metropolitan and rural settings. This study was conducted between 1987 and 1996 to assess the effect of screening and improved technology over a 10-year period. RESULTS: The study found that a high percentage of malignant lesions are being diagnosed by fine-needle aspiration biopsy (FNAB) with a corresponding reduction in open biopsy rate at the Prince of Wales Hospital. There is a smaller percentage of benign operations in both settings with a reduction of equal proportion. The reporting of the pathology specimens has markedly improved at both institutions. There has been a reduction in the number of patients having modified radical mastectomy and there has been a corresponding increase in breast conservation surgery especially at the Prince of Wales/Prince Henry Hospitals, although there was an unexpectedly high incidence of breast conservation surgery at Tamworth Base Hospital in 1987. In 1996 the rates of breast conservation surgery were the same in both hospitals. CONCLUSIONS: There are minimal differences in the quality of surgical care being offered to patients at the Tamworth Base Hospital compared with the Prince of Wales Hospital and both institutions are within reach of the accepted best management practices available.

Australia↗