Biomedical subjects

J C Wong

Publications and source records attributed to J C Wong.

At least 19 recordsLinked to original sources

PubMed2001

Temporal trends and molecular epidemiology of HIV-1 infection in Taiwan from 1988 to 1998.

Eight hundred and seventy-nine HIV-1-infected patients (comprising 46% of reported HIV-1/AIDS cases in Taiwan) were recruited for this study of the molecular epidemiology of HIV-1 in Taiwan from 1988 to 1998. HIV-1 subtypes were determined using a modified peptide-enzyme immunoassay complemented with DNA sequencing and phylogenetic analysis. Of the 807 HIV-1 infected men, 68.2% were infected with HIV-1B, 29.5% with HIV-1 circulating recombinant form (CRF)01_AE and 2.3% with other subtypes. Of the 72 HIV-1-infected women, 72.2% were infected with HIV-1 CRF01_AE, 13.9% with HIV-1B, and 13.9% with other subtypes. All of 8 foreign-born, Southeast Asian women and 6 of 7 (85.7%) Taiwan-native female commercial sex workers were infected with HIV-1 CRF01_AE. Fourteen of the 33 (42.4%) heterosexual married men with CRF01_AE had transmitted HIV-1 to their wives, whereas only 1 of 17 (5.9%) men with HIV-1 B had transmitted HIV-1 to their spouses (p < .01). Of 18 heterosexual male injecting drug users, 1 of 12 (8.5%) with HIV-1B and 5 of 6 (83.3%) with HIV-1 CRF01_AE had had sexual contact with female commercial sex workers (p < .01). Therefore, in this population, CRF01_AE was preferentially associated with heterosexual risk groups, a finding compatible with differences in transmission capability between B and non-B subtypes.

Adult↗

PubMed2001

Split--pool synthesis of 1,3-dioxanes leading to arrayed stock solutions of single compounds sufficient for multiple phenotypic and protein-binding assays.

Diversity-oriented organic synthesis offers the promise of advancing chemical genetics, where small molecules are used to explore biology. While the split--pool synthetic method is theoretically the most effective approach for the production of large collections of small molecules, it has not been widely adopted due to numerous technical and analytical hurdles. We have developed a split--pool synthesis leading to an array of stock solutions of single 1,3-dioxanes. The quantities of compounds are sufficient for hundreds of phenotypic and protein-binding assays. The average concentration of these stock solutions derived from a single synthesis bead was determined to be 5.4 mM in 5 microL of DMSO. A mass spectrometric strategy to identify the structure of molecules from a split--pool synthesis was shown to be highly accurate. Individual members of the 1,3-dioxane library have activity in a variety of phenotypic and protein-binding assays. The procedure developed in this study allows many assays to be performed with compounds derived from individual synthesis beads. The synthetic compounds identified in these assays should serve as useful probes of cellular and organismal processes.

Animals↗

PubMed2001

Bone mineral density in adolescent females with recently diagnosed anorexia nervosa.

UNLABELLED: Anorexia nervosa (AN) can lead to osteoporosis and fractures. OBJECTIVE: This study evaluated adolescent females with AN diagnosed within the previous 12 months to determine whether there is bone mass reduction and to investigate relationships between nutritional indices (weight, body mass index [BMI], lean mass, fat mass, and percentage fat) and total body (TB) and lumbar spine (LS) bone mineral densities (BMD) and content (BMC). METHOD: TB and LS BMD and BMC and body composition were measured in 24 adolescent females with AN. RESULTS: There was no significant reduction in TB or LS BMD. Regression analysis shows significant correlation (p < 0.001) between lean mass and TB BMD (r = +0.83), TB BMC (r = +0.92), LS BMD (r = +0.81), and LS BMC (r = +0.92). There was also a significant relationship between weight percentile and LS BMD z score (p < 0.005; r = +0.60). DISCUSSION: Adolescent females with early AN do not appear to have reduced bone mass. Lean mass is correlated to BMD and BMC.

Adolescent↗

PubMed2001

Intracytoplasmic sperm injection increased fertilization and good-quality embryo formation in patients with non-male factor indications for in vitro fertilization: a prospective randomized study.

OBJECTIVE: To compare the fertilization rate and formation of good-quality embryos with conventional IVF and ICSI in patients with non-male factor infertility. DESIGN: Prospective controlled study. SETTING: Infertility clinic. PATIENT(S): Thirty-five patients with non-male factor infertility. INTERVENTION(S): Retrieved sibling oocytes were randomly assigned to conventional IVF or ICSI. Of sibling oocytes assigned to ICSI, only metaphase II oocytes were injected with sperm. MAIN OUTCOME MEASURE(S): Fertilization rate and formation of good-quality embryos per retrieved oocyte. RESULT(S): Per retrieved oocyte, ICSI resulted in better fertilization rate compared with conventional IVF (71.3% [134 of 188] vs. 57.2% [107 of 187]). Per retrieved oocyte, ICSI also resulted in better formation of good-quality embryos at 48 hours after retrieval compared with conventional IVF (64.4% [121 of 188] vs. 47.1% [88 of 187]). CONCLUSION(S): In IVF patients with non-male factor infertility, subjecting some sibling oocytes to ICSI increased the fertilization rate and formation of good-quality embryos per retrieved oocyte. It also avoided the problem of total fertilization failure in almost all cases.

Adult↗

PubMed2001

Performing ICSI using an injection pipette with the smallest possible inner diameter and a long taper increases normal fertilization rate, decreases incidence of degeneration and tripronuclear zygotes, and enhances embryo development.

PURPOSE: To compare the efficacy of two types of injection pipette used for ICSI, one with a larger (5-7 microns) inner diameter and a shorter taper with that inner diameter, and another with the smallest (3-5 microns) possible inner diameter and a longer taper with that inner diameter. METHODS: Retrieved oocytes at metaphase II stage were injected using one of two types of injection pipette, in 33 and 94 cycles, respectively, in a total of 127 cycles in 108 patients. RESULTS: In comparison to the injection pipette with a larger (5-7 microns) inner diameter and a shorter taper with that inner diameter, the injection pipette with the smallest (3-5 microns) possible inner diameter and a longer taper with that inner diameter increased normal fertilization rate ((70 +/- 3.6)% vs. (86 +/- 2.2)%; P = .001; mean +/- SEM); decreased the incidence of degeneration ((14 +/- 2.4)% vs. (5 +/- 1.4)%; P = .001) and tripronuclear zygotes ((1.0 +/- 0.35)% vs. (0.1 +/- 0.21)%; P = .03); increased Day-2 diploid embryos ((69 +/- 3.7)% vs. (85 +/- 2.2)%; P = .001) and good-quality Day-2 diploid embryos ((67 +/- 4.0)% vs. (79 +/- 2.4)%; P = .03), all per injected oocyte; and increased the number of blastomeres per good-quality Day-2 diploid embryo ((3.0 +/- 0.21 vs. 3.8 +/- 0.12; P = .0003). CONCLUSIONS: Performing ICSI using an injection pipette with the smallest (3-5 microns) possible inner diameter and a longer taper with that inner diameter maximizes normal fertilization rate, minimizes the incidence of postinjection degeneration and tripronuclear zygotes, and enhances embryo development.

Adult↗

PubMed2001

Exposure of human oocytes to endometrioma fluid does not alter fertilization or early embryo development.

BACKGROUND: Extensive endometriosis causes a mechanical disturbance in the pelvis leading to obstructive-type infertility. However, minimal or mild endometriosis is suspected to cause infertility, possibly through a humoral agent. Previous studies reported the presence of a factor in the serum of patients with endometriosis which reduced fertilization and early embryo formation in a rat IVF model. METHODS: In the present article, we report a comparison of oocytes exposed to endometrioma fluid and oocytes not exposed (controls) in the context of a human IVF setting. We have been in the practice of aspirating oocytes into prewarmed 60-ml syringes containing culture medium. We have shown previously that this technique reduces the length of oocyte retrieval without compromising success. In 14 women undergoing oocyte retrieval, we inadvertently entered an endometrioma. This resulted in retrieved oocytes that were either exposed or not exposed to endometrioma fluid. RESULTS: In contrast to previous reports, we found no difference in fertilization or early embryo development between the two groups. The fertilization rate for oocytes exposed to an endometrioma was 60%, versus 56% for controls. The good-quality embryo formation rate for oocytes exposed to an endometrioma was 45%, versus 46% for controls.

Adult↗

PubMed2001

Comparison between seasons of the ultraviolet environment in the shade of trees in Australia.

BACKGROUND/PURPOSE: This paper has considered the erythemal UV (UVery), UVA and visible irradiances in the shade of Australian trees for each season at a sub-tropical southern hemisphere site. METHODS: The irradiances in tree shade have been measured with radiometers as a percentage of the irradiances in the sun for each season of the year. RESULTS: Although the solar irradiances are lower in winter, the percentages of the UV in tree shade compared to the UV in full sun are marginally higher (by up to 7%) in the winter compared to summer. The range of percentages for UVery was up to double that of the percentages of the visible waveband. The percentages for UVery were also higher than for the UVA waveband. The percentages of the irradiances in the tree shade compared to full sun are 8-14% lower at noon compared to the morning and afternoon for the UVery waveband. The ratio of UVA to UVery is lower in the tree shade compared to the full sun. CONCLUSIONS: The UVA to UVery ratio is expected to be even lower in the tree shade as a result of ozone depletion. This, combined with the visible irradiances in the tree shade not being a reliable indication of the biologically damaging UV irradiances, has consequences for public health and skin cancer prevention.

Australia↗

PubMed2001

The influence of homologous blood transfusion on immunity and clinical outcome in aortic surgery.

OBJECTIVES: To evaluate the influence of homologous blood transfusion on immune responses and post-operative morbidity in aortic surgery. DESIGN: Analysis of the effects of homologous blood transfusion in 128 patients in a prospective randomised trial evaluating homologous and autologous blood transfusion in aortic surgery. MATERIALS AND METHODS: Blood sampled before and at five times after surgery was assayed for C-reactive protein (CRP), neutrophil elastase, TNF-alpha and IL-6. Transfusions, morbidity and mortality were recorded; factors associated with poor outcome were identified by logistic regression. RESULTS: homologous transfusion during surgery was required in 32 patients and precipitated an increase in neutrophil elastase (p=0.008) and TNF-alpha (p=0.015) but not IL-6 and CRP. Elastase peaked early in transfused patients at 41.27 (13.92-52.11) Deltang/ml by 2 h compared to a peak of 21.51 (10.64-31.13) Deltang/ml by 24 h in those who were not transfused. TNF-alpha peaked at 1.2 (0-4.33) Deltapg/ml by wound closure in transfused patients and at -0.1 (-2.05-2.52) Deltapg/ml by 2 h without transfusion. Intra-operative homologous transfusion was associated with increased mortality (p=0.01) and prolonged intensive care stay (p=0.03). Mortality increased with age (p=0.003) and was inversely related to the CRP peak (p=0.007). Prolonged surgery predicted post-operative complications (p=0.025). CONCLUSION: Homologous transfusion increased the inflammatory response to aortic surgery and was associated with mortality.

Aged↗

PubMed2001

Solar ultraviolet exposures at ground level in tree shade during summer in south east Queensland.

Data are presented on the effect of the tree canopy transmittance in the visible waveband (VT), canopy width, height and height of the start of the tree canopy (CH) on the solar UV in tree shade on a horizontal plane at ground level during a Southern Hemisphere summer. Of these factors, the VT and CH have an influence on the UV irradiances in the tree shade. The shade ratios (UV in tree shade to that in full sun) for erythemal UV ranged from 0.71 to 0.42, 0.54 to 0.29 and 0.63 to 0.41 for morning, noon and afternoon, respectively, for the VT range of 0.4-1.0. Over the same VT range, the shade ratios for UVA ranged from 0.61 to 0.28, 0.50 to 0.22 and 0.49 to 0.29 for morning, noon and afternoon, respectively. The UV exposures in the tree shade decreased with the VT with a marginally higher decrease in the irradiances for the UVA compared to the erythemal UV. Despite the protection by the tree shade, significant UV in the tree shade of approximately 4 MED (minimum erythemal dose) were received for the latitude in this research on a cloud free summer day on a horizontal plane over a 2-h period centred about solar noon.

Environmental Exposure↗

PubMed2001

Annual occupational exposure to ultraviolet radiation in central Queensland.

The purpose of this study was to determine annual occupational exposure to UV radiation by measurement and derive ambient exposure fractions for an entire year that could be applied in the human exposure model. Using polysulphone the daily occupational erythema effective solar ultraviolet radiation exposure at selected body sites of Australia Post mail delivery personnel and physical education teachers were measured over an 18-mo period on a daily basis in the Rockhampton (lat. 23.5 degrees S) region. The daily exposures were summed to estimate an annual exposure for these occupations in this region. For the Australia Post mail delivery personnel, who had very little change to the posture or route during delivery, the annual mean estimates of exposure to erythema effective solar irradiance for the chest, hands, and back were in the range of 192+/-27 kJ m(-2), 388+/-45 kJ m(-2), and 283+/-32 kJ m(-2), respectively. Physical education teachers had varied duties on a day-to-day basis and many changes in their posture and outdoor locations where the exposure occurred. Their annual mean exposure on the vertex (hat), chest, shoulder, thigh, and back were in the range 340+/-71 kJ m(-2), 140+/-28 kJ m(-2), 180+/-40 kJ m(-2), 129+/-24 kJ m(-2), and 212+/-42 kJ m(-2), respectively. The annual exposure range for erythema effective solar irradiance at different body sites during the experimental period was between 120 and 440 kJ m(-2) for the two occupational groups. These exposures greatly exceed the National Health and Medical Research Council occupational standard limit of 30 J m(-2) for daily exposure, which indicates the need for additional protective measures. The ambient exposure was also measured and used to compute ambient exposure fractions for the different body sites over an entire year, which are useful for model calculations on human exposure and assess increase in risk of n on melanoma skin cancer.

Dose-Response Relationship, Radiation↗

PubMed2001

Quantitative assessment of diffusion abnormalities in posterior reversible encephalopathy syndrome.

BACKGROUND AND PURPOSE: Previous studies have shown that lesions in posterior reversible encephalopathy syndrome are often isointense on diffusion-weighted MR images. We hypothesized that 1) apparent diffusion coefficient (ADC) maps using various thresholds would show larger abnormalities in posterior white matter (WM) and 2) isointense appearance of lesions on isotropic diffusion-weighted images results from a balance of T2 prolongation effects and diffusibility effects. METHODS: T2-weighted MR images from 11 patients were reviewed. Hyperintense lesions were located in both anterior and posterior WM in eight patients and solely in posterior WM in three patients. The ADC maps were produced by use of ADC values > or = 3 SD and > or = 10 SD above the mean value of normal WM. Lesions on diffusion-weighted images were classified as isointense or hypointense. ADC values within lesions (ADC(L)) were compared with those of normal WM (ADC(N)), and compared for isointense lesions and hypointense lesions. RESULTS: The distribution of lesions with ADC values > or = 3 SD was essentially identical to that on T2-weighted images. Regions with ADC values > or = 10 SD were found in both anterior WM and posterior WM in two patients and solely in posterior WM in nine patients. On diffusion-weighted images, lesions appeared isointense in seven patients and hypointense in four patients. Mean ADC(L)/ADC(N) for all lesions was 1.81; for hypointense lesions, 2.30. CONCLUSION: Vasogenic edema was more severe in posterior WM. Isointense lesions result from a balance of T2 effects and increased water diffusibility. Hypointense lesions have higher ADC values, which are not balanced by T2 effects.

Adult↗

PubMed2000

Cloning and analysis of the mouse Fanconi anemia group A cDNA and an overlapping penta zinc finger cDNA.

Despite the cloning of four disease-associated genes for Fanconi anemia (FA), the molecular pathogenesis of FA remains largely unknown. To study FA complementation group A using the mouse as a model system, we cloned and characterized the mouse homolog of the human FANCA cDNA. The mouse cDNA (Fanca) encodes a 161-kDa protein that shares 65% amino acid sequence identity with human FANCA. Fanca is located at the distal region of mouse chromosome 8 and has a ubiquitous pattern of expression in embryonic and adult tissues. Expression of the mouse cDNA in human FA-A cells restores the cellular drug sensitivity to normal levels. Thus, the expression pattern, protein structure, chromosomal location, and function of FANCA are conserved in the mouse. We also isolated a novel zinc finger protein, Zfp276, which has five C(2)H(2) domains. Interestingly, Zfp276 is situated in the Fanca locus, and the 3'UTR of its cDNA overlaps with the last four exons of Fanca in a tail-to-tail manner. Zfp276 is expressed in the same tissues as Fanca, but does not complement the mitomycin C (MMC)-sensitive phenotype of FA-A cells. The overlapping genomic organization between Zfp276 and Fanca may have relevance to the disease phenotype of FA.

Adult↗

PubMed2000

Diffuse component of solar ultraviolet radiation in tree shade.

The first set of quantitative data of diffuse erythemal UV and UV-A radiation in tree shade at a sub-tropical Southern Hemisphere latitude is presented. Over the summer, approximately 60% of the erythemal UV radiation in tree shade is due to the diffuse component. Similarly, approximately 56% of the UV-A radiation in tree shade is due to the diffuse component. In tree shade these diffuse UV percentages are relatively constant from the morning to noon to afternoon periods. In comparison, in full sun, there is a decrease in the percentage of diffuse UV from morning to noon to afternoon. The exposures to diffuse UV on a horizontal plane in tree shade between 9:00 EST and 15:00 EST are of the order of 4 MED (minimum erythemal dose) and 14 J cm(-2) for erythemal UV and UV-A, respectively. The high diffuse UV component in the shade may result in high UV exposures not only to unprotected parts of the body on a horizontal plane, but also in equally high UV irradiances to parts of the body, including the eyes and face, that are not UV protected.

Diffusion↗

PubMed2000

An estimation of biological hazards due to solar radiation.

A spectrum evaluator based on four different dosimeter materials has been employed to estimate the spectral irradiances of solar radiation for exposed humans. The result is used to calculate the biologically effective irradiance using the erythemal action spectrum and a fish melanoma action spectrum. Measurements are made in winter at a sub-tropical site on the chest and shoulder of subjects during normal daily activities. Up to 95% of the total UV exposure received is in the UV-A waveband (320-400 nm). The UV-A waveband is found to contribute approximately 14% of the erythemal UV and 93% of the biologically effective UV for fish melanoma. Extrapolation to humans suggests that exposure to the UV-A band will contribute to photodamage in human skin during exposure to solar radiation.

Animals↗

PubMed2000

The status of controlled prospective clinical trials for efficacy of intracytoplasmic sperm injection in in vitro fertilization for non-male factor infertility.

PURPOSE: Intracytoplasmic sperm injection (ICSI) of some sibling oocytes may have a beneficial effect in couples going through in vitro fertilization for causes of infertility not related to the male factor. Our purpose was to critically appraise the randomized controlled studies done in this area and arrive at some recommendations. METHODS: The four controlled trials done so far have utilized similar methodology, i.e., they randomly allotted sibling oocytes to ICSI versus standard insemination in patients going through in vitro fertilization and embryo transfer. RESULTS: In the first trial reported in 1995 there was no difference in fertilization rate, whereas the later trials reported in 1997, 1999, and 2000 showed improvement with ICSI that reached statistically significant level in the last two studies. CONCLUSIONS: Total fertilization failure of an in vitro fertilization cycle can be prevented and fertilization can be improved if half of sibling oocytes are subjected to ICSI.

Controlled Clinical Trials as Topic↗

PubMed2000

Effect of childhood and adolescent ultraviolet exposures on cumulative exposure in South East Queensland schools.

Quantitative estimates of the childhood and adolescent erythemal ultraviolet (UV) exposure received in South East Queensland schools are provided in this paper for age groups 0 to 6, 7 to 12 and 13 to 19 years. For the neck, hand and lower arm, sites of high UV exposure that are generally not covered by clothing, 13 to 19 year olds received the highest exposure of the three age groups, followed by 7 to 12 year olds. Exposure for 13 to 19 year olds contributed up to 44% of cumulative exposure to 20 years of age, and exposures for the 7 to 12 year olds contributed up to 31%. If the annual UV exposure for these two age groups were reduced to the average of all the age groups, cumulative erythemal UV exposure from 0 to 20 years would be reduced by up to 16%. On the other hand, if mothers can protect their babies by reducing the level of annual exposure to 30% of the annual UV exposure of the 7 to 12 year olds for the first four years then cumulative exposure to UV to age 20 would be reduced by up to 19%. These data confirm the importance of targeting young age groups in public campaigns for sun protection.

Adolescent↗

PubMed2000

Nuclear medicine imaging in early vertebral osteomyelitis: still of clinical utility.

A case is presented of vertebral osteomyelitis in an elderly confused patient with poorly localizing signs. The lesion was not diagnosed on the initial MRI study of the spine due to poor targeting. The abnormality was detected on a bone scan the following day. This was confirmed with a gallium scan 3 days later, and also a repeat MRI study 11 days after the first MRI, using an optimized protocol over the region of interest established by the bone scan.

Aged↗

PubMed2000

Personal exposure distribution of solar erythemal ultraviolet radiation in tree shade over summer.

The personal radiant exposure distribution of solar erythemal UV in tree shade for an upright posture was measured, with measurements over the whole summer for a total of 17 trees. For each tree, the personal radiant exposure distribution was measured for both the morning and afternoon periods. The exposure ratios averaged over all the trees and over the morning and afternoon periods ranged from 0.16 to 0.49 for the different anatomical sites. A numerical model was employed to estimate the UV radiant exposure to humans in tree shade over the entire summer. The body sites with the higher exposure ratios in the tree shade were the vertex of the head, shoulders and forearms with radiant exposures over the summer of 1300 MED to the vertex of the head and 1100 MED to the shoulders and forearms. These radiant exposures in the shade are substantially higher than the ambient erythemal UV measured in full sun on a horizontal plane over a full summer at a more temperate northern hemisphere latitude. The average radiant exposures per day to each anatomical site for a complete day in the tree shade ranged from 4.6 to 14.6 MED. This research has provided new data that is essential to quantify human UV exposure during outdoor activities.

Australia↗