Biomedical subjects

M Y Chen

Publications and source records attributed to M Y Chen.

At least 19 recordsLinked to original sources

PubMed2007

Oxygen diffusion in active layer of aerobic granule with step change in surrounding oxygen levels.

High biomass density and large size limit the transfer of dissolved oxygen (DO) in aerobic granules. In the literature, the oxygen diffusivity is often employed as an input parameter for modeling transport processes in aerobic granules. The interior of an aerobic granule was observed to be highly heterogeneous. In this work, the distributions of extracellular polymeric substances (EPS) and cells in the interior of phenol-fed and acetate-fed granules were built up using a five-fold staining scheme, combined with the use of a confocal laser scanning microscope (CLSM). The steady-state and transient DO with step changes in surrounding DO levels at various depths were measured in the granules using microelectrodes. Cells were probed in a surface layer of thickness 125-375 microm. A marked fall in DO was also noted over this surface layer. No aerobic oxidation could occur beneath the active layer, indicating the oxygen transfer limit. Fitting the steady-state and transient DO data over the active surface layer yielded apparent diffusivities of oxygen were (9.5+/-3.5)x10(-10)m(2)s(-1) for the phenol-fed granule and (3.5+/-1.0)x10(-10)m(2)s(-1) for the phenol-fed granule. These values were lower than those adopted in models in the literature.

Acetates↗

PubMed2006

A randomised controlled trial comparing computer-assisted with face-to-face sexual history taking in a clinical setting.

AIM: To compare computer-assisted self-interview (CASI) with routine face-to-face interview (FTFI) for sexual history taking from patients in a clinical setting. METHODS: A randomised controlled trial was undertaken at the Melbourne Sexual Health Centre, Melbourne, Victoria, Australia, in 2005. New, walk-in patients triaged into the centre were eligible for the study. Those who consented to the study were randomly allocated (initially at a ratio of 2:1, then 1:1) to either CASI or FTFI. Those randomised to CASI also subsequently undertook FTFI. RESULTS: During the study period, of 713 patients approached, 611 agreed to participate in the study; 356 were randomised to FTFI and 255 to CASI. Overall, the responses to questioning using CASI and FTFI were similar except that women undertaking the CASI reported a significantly higher median number of male partners for the preceding 12 months (3 v 2, p = 0.05) and the CASI participants reported previous hepatitis B vaccination more often (50% v 37%, p = 0.01). Most participants found the CASI either easy (31; 13%) or very easy (193; 82%) to complete; 83 (35%) were comfortable and 121 (51%) were very comfortable with it. CONCLUSIONS: CASI may be a reliable, efficient and highly acceptable method for the screening of sexual risk in clinical sexual health settings and could be used routinely to improve the efficiency of clinical services.

Adult↗

PubMed2006

Distribution of extracellular polymeric substances in aerobic granules.

Extracellular matrix provides an architectural structure and mechanical stability for aerobic granules. Distributions of cells and extracellular polymeric substances (EPS), including proteins, alpha- and beta-D-glucopyranose polysaccharides, in acetate-fed granules and phenol-fed granules were probed using a novel quadruple staining scheme. In acetate-fed granules, protein and beta-D-glucopyranose polysaccharides formed the core, whereas, the cells and alpha-D-glucopyranose polysaccharides accumulated in the granule outer layers. Based on these experimental findings, this study indicated that different conclusions can be obtained regarding EPS distributions when granules were stained differently. The core of phenol-fed granules, conversely, was formed principally by proteins; whereas, the cells and alpha- and beta-D-glucopyranose polysaccharides were accumulated at an outer filamentous layer. Using a series of confocal laser scanning microscope (CLSM) images whose threshold values were determined via Otsu's scheme, the three-dimensional distributions of cells and EPS were produced using a polygonal surface model. Structural information extracted can be applied in further development of comprehensive granule models.

Aerobiosis↗

PubMed2006

Diffusivity of oxygen in aerobic granules.

This work for the first time estimated apparent oxygen diffusivity (D(app)) of two types of aerobic granules, acetate-fed and phenol-fed, by probing the dissolved oxygen (DO) level at the granule center with a sudden change in the DO of the bulk liquid. With a high enough flow velocity across the granule to minimize the effects of external mass transfer resistance, the diffusivity coefficients of the two types of granules were estimated with reference to a one-dimensional diffusion model. The carbon source has a considerable effect on the granule diameter (d) and the oxygen diffusivity. The diffusivity coefficients were noted 1.24-2.28 x 10(-9) m2/s of 1.28-2.50 mm acetate-fed granules, and 2.50-7.65 x 10(-10) m2/s of 0.42-0.78 mm phenol-fed granules. Oxygen diffusivity declined with decreasing granule diameter, in particular, the diffusivity of acetate-fed granules is proportional to the size, whereas the diffusivity of phenol-fed granules is proportional to the square of granule diameter. The existence of large pores in granule, evidenced by FISH-CLSM imaging, was proposed to correspond to the noted size-dependent oxygen diffusivity. The phenol-fed granules exhibited a higher excellular polymer (ECP) content than the acetate-fed granules, hence yielding a lower oxygen diffusivity.

Acetates↗

PubMed2006

Heat shock protein 72 overexpression protects against hyperthermia, circulatory shock, and cerebral ischemia during heatstroke.

This study extends our earlier studies in rats by applying our heatstroke model to a new species. Additionally, transgenic mice are used to examine the role of heat shock protein (HSP) 72 in experimental heatstroke. Transgenic mice that were heterozygous for a porcine HSP70i gene ([+]HSP72), transgene-negative littermate controls ([-]HSP72), and normal Institute of Cancer Research strain mice (ICR) under pentobarbital sodium anesthesia were subjected to heat stress (40 degrees C) to induce heatstroke. In [-]HSP72 or ICR, the values for mean arterial pressure, the striatal blood flow, and the striatal PO2 after the onset of heatstroke were significantly lower than those in preheat controls. The core and brain temperatures, the extracellular concentrations of ischemic and injury markers in the striatum, and the striatal neuronal damage scores were significantly greater than those in the preheat controls. In [-]HSP72 or ICR, the body temperatures, cell ischemia content, and injury marker in the striatum were significantly higher, and the mean arterial pressure, striatal blood flow, and striatal PO2 concentration were significantly lower during heatstroke than in [+]HSP72. Accordingly, the latency and the survival times for [+]HSP72 significantly exceeded those of [-]HSP72 or ICR. These results demonstrate that the overexpression of HSP72 in multiple organs improves survival during heatstroke by reducing hyperthermia, circulatory shock, and cerebral ischemia and damage in mice.

Animals↗

PubMed2006

Effects of internal medicine residency training in AIDS care in Taiwan.

Having contact and interacting with HIV/AIDS patients has long been recognized as a means for improving AIDS-related knowledge and attitudes among physicians and hence for increasing their intention to provide AIDS care. To investigate the impact of one-month residency training in an AIDS inpatient unit on internal medicine residents, this quasi-experimental, pre-post, two-group study, conducted from April 2000 to April 2001, used questionnaires. At follow-up, residents who received training in the AIDS unit (experimental group) were significantly more knowledgeable about HIV/AIDS, had more positive attitudes and greater intention to care for HIV-infected patients than residents who did not receive this training (control group). Results suggest that a one-month AIDS residency training intervention can effectively enhance residents' HIV-related knowledge, attitudes and intention to care for patients infected with HIV.

Adult↗

PubMed2006

Are patient responses to sensitive sexual health questions influenced by the sex of the practitioner?

OBJECTIVE: To determine whether a patient's responses to sensitive questions about their sexual behaviour are influenced by the sex of their treating practitioner. METHODS: An audit was conducted on the computerised medical records of all patients attending the Melbourne Sexual Health Centre through the walk-in triage system between January 2003 and July 2005. Patient responses to sensitive questions about their sexual behaviour were analysed according to patient group (based upon the sex of their sexual partners) and the sex of the treating practitioner. RESULTS: There was no significant difference in the reported number of sexual partners, condom use, sex overseas, injecting drug use, or commercial sex work based on the sex of the treating practitioner for the different patient groups. This held true whether clients were homosexual men (n = 1609, p>0.07), heterosexual men (n = 4847, p>0.11), or women (n = 4910, p>0.08). CONCLUSIONS: The sex of the practitioner did not significantly influence patient responses to sensitive questions about their sexual behaviour.

Ambulatory Care↗

PubMed2006

Is routine vaginal examination necessary for asymptomatic women attending sexual health services?

The aim of this study was to determine whether our sexual health service could be streamlined by dispensing with routine vaginal examination of asymptomatic women, without missing important diagnoses. This was an audit of asymptomatic women presenting to the centre who had had a Papanicolaou (PAP) smear in the previous two years. Of the 421 women who were eligible, no abnormalities were found on genital inspection in 392 (93%) individuals. Abnormalities detected on clinical examination included one case (0.2%) with mucopurulent cervicitis that tested positive for Chlamydia trachomatis, four (1%) with warts or molluscum contagiosum, and one with an asymptomatic genital ulcer of unknown cause. Dispensing with the vaginal examination in asymptomatic women who have had a speculum examination as part of biennial cervical screening may be appropriate in settings where sensitive non-invasive testing for sexually transmitted infections (STI) is in use and STI prevalence is low.

Chlamydia Infections↗

PubMed2006

Biodegradation of a variety of bisphenols under aerobic and anaerobic conditions.

There is a group of compounds structurally similar to bisphenol-A (BPA), namely bisphenols (BPs), and some of them are considered to be able to partially replace BPA. In order to assess their biodegradability in the aquatic environment, a variety of BPs; BPA, bis(4-hydroxyphenyl)methane (BPF), bis(4-hydroxyphenyl)ethane (BPE), 2,2-bis(4-hydroxy-phenyl)butane (BPB), 2,2-bis(4- hydroxy-3-methylphenyl)propane (BPP), bis(4-hydroxyphenyl)sulfone (BPS), thiodiphenol (TDP) and 4,4'-dihydroxybenzophenone (HBP); were subjected to biodegradation tests under both aerobic and anaerobic conditions. For the aerobic degradation test, a kind of river-die-away method using several river water samples was used, while pond sediments were used for the anaerobic degradation tests in sealed anoxic bottles. As a whole, the examined BPs could be ranked by their biodegradability under aerobic conditions; BPF, HBP > > BPA > BPP > BPE > BPB > TDP > > BPS. On the other hand, the tendency for the anaerobic biodegradability was; BPF > HBP > BPS, BPA, TDP > BPE > BPB. From the viewpoint of biodegradability, BPF seems to be more environmentally-friendly than BPA and, therefore, may be a candidate to replace BPA for reducing the environmental risks.

Bacteria, Aerobic↗

PubMed2005

Discordance between trends in chlamydia notifications and hospital admission rates for chlamydia related diseases in New South Wales, Australia.

BACKGROUND: In Australia, notification rates for chlamydia have increased fourfold since the early 1990s. An increasing incidence of genital Chlamydia trachomatis infection would be expected to lead to a rise in the incidence of chlamydia related diseases. OBJECTIVES: To determine trends in hospital admission rates for pelvic inflammatory disease (PID), ectopic pregnancy, and epididymo-orchitis in New South Wales. METHODS: Age specific admission rates from 1992 to 2001 were ascertained using inpatient data from all hospitals within the state. RESULTS: Among women aged 15-34 years, hospital admission rates for PID fell from 165 per 100,000 population in 1992 to 64 per 100,000 population in 2001 (p for trend<0.0001). 15% of PID cases in women aged 15-24 years were chronic, compared with 32% in those aged 25-34 years, and 46% in the 35-44 year age group. The incidence of ectopic pregnancy and admission rates for epididymo-orchitis remained constant. CONCLUSIONS: On a population level, trends in the incidence of chlamydia related diseases do not necessarily parallel those of reported chlamydia rates and ecological associations between the two need to be interpreted with caution.

Acute Disease↗

PubMed2005

Impact of chronic hepatitis C infection on outcomes of patients with an advanced stage of HIV-1 infection in an area of low prevalence of co-infection.

To ascertain whether hepatitis C (HCV) co-infection affects the progression of HIV infection, we initiated an eight-year prospective observational study at a university hospital in Taiwan where seroprevalences of HCV antibody and HIV antibody were low. Fifty-three (12.0%) consecutive non-haemophiliac HIV1-infected patients with HCV co-infection and 387 (88.0%) patients without HCV and hepatitis B co-infection were enrolled between June 1994 and June 2002 and observed until December 2002. Outcomes evaluated included the risk for acute hepatitis, hepatic decompensation, HIV disease progression and mortality, and changes of CD4+ count and plasma viral load (PVL) after initiation of highly active antiretroviral therapy (HAART) at the end of the study. The baseline CD4+ count, PVL and proportion of patients with AIDS-defining opportunistic illnesses (OI) at study entry were similar between patients with HCV co-infection and those without co-infection, but HCV-co-infected patients were older (39 versus 35 years, P = 0.01) and had a higher proportion of intravenous drug use (17.0% versus 0.8%, P < 0.001). After a total observation duration of 1137 patient-years (PY) (median, 791 days; range, 3-3053 days), the incidence of acute hepatitis in HCV-co-infected patients was 13.89 per 100 PY (95% confidence interval [CI], 13.31-14.49) and that in patients without co-infection was 6.39 per 100 PY (95% CI, 6.24-6.55 per 100 PY), with an adjusted odds ratio (OR) of 2.769 (95% CI, 1.652-4.640). At the end of the study, CD4+ count increased by 137 x 10(6) and 157 x 10(6)/L in patients with and without HCV co-infection, respectively, (P = 0.47). The proportions of achieving undetectable PVL (<400 copies/mL) after HAART was similar (76.7% versus 74.9%, P = 0.79). The adjusted OR for development of new AIDS-defining OI was 1.826 (95% CI, 0.738-4.522) in HCV-co-infected patients as compared with HCV- uninfected patients. The adjusted hazards ratio for death of HCV-co-infected patients when compared with those without co-infection was 0.781 (95% CI, 0.426-1.432). Our findings suggested that HCV co-infection was associated with a significantly higher risk for acute hepatitis in HIV-infected patients receiving antiretroviral therapy, but it had no adverse impact on virological, immunological and clinical responses to HAART and survival when compared with patients without HCV and HBV co-infection.

AIDS-Related Opportunistic Infections↗

PubMed2005

Prevalence of Toxoplasma gondii infection and incidence of toxoplasma encephalitis in non-haemophiliac HIV-1-infected adults in Taiwan.

We assessed the seroprevalence of Toxoplasma gondii infection and incidence of toxoplasma encephalitis (TE) in 844 non-haemophiliac HIV-infected patients in Taiwan between June 1994 and April 2003. Approximately 70% (69.3%) of them had a baseline CD4+ lymphocyte count of 200 x 10(6)/L or less, and more than 70% (73.9%) having initiated highly active antiretroviral therapy. The seroprevalence of T. gondii infection was 10.2%, which did not differ with sex,age,route of transmission, birth inside or outside of Taiwan, or CD4+ lymphocyte stratifications. After a median observation duration of 603 days (range, 1-3264 days), 10 (1.2%) patients developed 11 episodes of TE after a median interval of 30 days (range, 1-941 days) between enrolment and diagnosis of TE, with an incidence of 0.59 per 100 person-years (PY) (95% confidence interval, 0.56-0.63 per 100 PY). We concluded that the incidence of TE of HIV-infected patients in Taiwan was lower than that reported in western countries because of a lower seroprevalence of T. gondii infection and use of antimicrobial prophylaxis and antiretroviral therapy, although most of the patients were at the late stage of HIV infection.

Adolescent↗

PubMed2005

False-positive fluorine-18 fluorodeoxy-D-glucose positron emission tomography imaging caused by retained gauze in a woman with recurrent ovarian cancer: a case report.

We report a case of a 47-year-old woman with a false-positive [18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) result caused by retained gauze during resection of liver metastasis for a Stage IV ovarian cancer at primary cytoreductive surgery. She achieved complete remission and remained free of progression for seven years. Owing to elevation of CA-125, computed tomography and PET studies were performed, and both showed two potentially resectable lesions. One was located ventral to the diaphragmatic surface of the left hepatic lobe and the other was around the gauze at the right hepatorenal fossa. During surgical intervention, the left supraheptic tumor was excised and the gauze with surrounding granulation was removed. However, the former proved to be recurrent ovarian cancer with the latter proven false-positive. This case demonstrates that PET results should be interpreted with caution in differentiating a benign inflammatory process from malignant abnormalities, especially in regions with a high probability of granulomatous lesions.

Adenocarcinoma, Papillary↗

PubMed2004

Fatal lactic acidosis associated with highly active antiretroviral therapy in patients with advanced human immunodeficiency virus infection in Taiwan.

Lactic acidosis (LA), a rare but life-threatening adverse effect associated with antiretroviral therapy, has been reported with an increasing frequency since the mid-1990s. From June 1994 to June 2002, a total of six patients, four males and two females with a median age of 43 years (range, 30 to 74 years), had been diagnosed with LA. The estimated incidence of LA was 5.1 per 1000 patient-years (PYs) on highly active antiretroviral therapy (HAART) (95% confidence interval [95% CI], 4.5-5.5 per 1000 PYs) and 4.4 per 1000 PY on nucleoside analogues (NAs) (95% CI, 3.9-4.7 per 1000 PYs). Their median body mass index at diagnosis of LA was 17.6 kg/m(2) (range 16.3 to 22.6 kg/m(2)). The median CD4+ lymphocyte count at the initial diagnosis of HIV infection and at the onset of LA was 38 cells/ micro L (range, 4 to 103 cells/ micro L) and 108 cells/ micro L (range, 79 to 224 cells/ micro L), respectively. The most common symptoms were nausea, vomiting, and dyspnoea. All of the patients had findings suggestive of NA-related mitochondrial toxicity, such as myositis, pancreatitis, fatty hepatitis, peripheral neuropathy or lipodystrophy. The prescribed NA related to LA were stavudine in six patients, lamivudine, five, and didanosine, one. Despite treatment, all patients died of persistent circulatory collapse following LA. The median duration from diagnosis to death was eight days (range, 4-17 days). Our report highlights that clinicians caring for patients with AIDS should be alerted to the potentially fatal LA associated with antiretroviral therapy when patients present with low body mass index, lipodystrophy, unexplained abdominal symptoms, dyspnoea, or elevated aminotransferases.

Acid-Base Imbalance↗

PubMed2004

Effects of heat, acid, and freeze-thaw challenges on survival of starved Vibrio parahaemolyticus in minimal salt medium, tryptic soy broth, and filtered oyster homogenate medium.

Vibrio parahaemolyticus is a ubiquitous gram-negative enteropathogenic bacterium. To evaluate the risk of stress-adapted V. parahaemolyticus cells in food, we investigated the survivability of starvation-adapted and starvation-low salinity-adapted cells of this pathogen in different media against different stresses. Logarithmically grown bacterial cells were starved at 25 degrees C in a minimal salt medium with 0.5 or 3.0% NaCl for 24 h. Resistances against challenges of heat, acid, and freeze-thaw treatment exhibited by the starvation-adapted cells were similar to those exhibited by the starvation-low salinity-adapted cells but substantially higher than those of the unadapted control cells. The increased stress resistance of the adapted cells against freeze-thaw challenge was lower in tryptic soy broth than in the starving medium. Resistance of the adapted bacteria against heat and freeze-thaw treatment was completely eliminated in filter-sterilized oyster homogenate medium. Practically, these results help to assess the risk of stress-adapted V. parahaemolyticus in food.

Adaptation, Physiological↗

PubMed2003

Film analysis of activated sludge microbial discs by the Taguchi method and grey relational analysis.

A biofilm model with substrate inhibition is proposed for the activated sludge growing discs of rotating biological contactor (RBC); this model is different from the steady-state biofilm model based on the Monod assumption. Both deep and shallow types of biofilms are examined and discussed. The biofilm models based on both Monod and substrate inhibition (Haldane) assumptions are compared. In addition, the relationships between substrate utilization rate, biofilm thickness, and liquid phase substrate concentration are discussed. The influence order of the factors that affect the biofilm thickness is studied and discussed by combining the Taguchi method and grey relational analysis. In this work, a Taguchi orthogonal table is used to construct the series that is needed for grey relational analysis to determine the influence priority of the four parameters S(B), kX(f), K(s), and K(i).

Bacteria↗

PubMed2002

Effects of single nucleotide polymorphisms in the 5'-flanking region of heat shock protein 70.2 gene on semen quality in boars.

This study aims to elucidate the effects of single nucleotide polymorphisms (SNPs) in the 5'-flanking region of porcine heat shock protein 70.2 gene (HSP70.2) on semen quality in boars. Genomic DNA isolated from 55 boars (41 Duroc, nine Landrace, and five Yorkshire) was subjected to PCR amplification of the 5'-flanking region of HSP70.2. The nucleotide sequences were determined by automated sequencing. Five SNPs (sites 44, 232, 250, 345, and 393) were detected in this region. Semen quality was evaluated in terms of sperm motility, percentage of normal sperm, percentage of sperm with proximal plasma droplet, percentage of abnormal sperm, sperm concentration, semen volume per ejaculate and total sperm number per ejaculate. The effect of the SNPs on semen quality was evaluated based on breed-corrected data within a season. During the cool season, the sperm motility of boars with AA genotype at the 232 site was significantly higher than that of boars with CC genotype (P<0.05). Meanwhile, boars with AC genotype at the 232 site had higher total sperm number per ejaculate than did those with CC genotype. In the hot season, heterozygotes at both the 232 and 250 sites had significantly higher total sperm number of per ejaculate than AA homozygotes (P<0.05). Semen volume of boars with TT and TC genotypes at the 345 site was significantly larger than that of those with CC genotype (P<0.05). Meanwhile, semen quality for boars with TT genotype at the 345 site was significantly higher than that of boars with TC or CC genotype (P<0.05), that is the semen contained higher percentages of normal sperm and lower percentages of abnormal sperm or sperm with proximal plasma droplets. Results herein suggest that the SNPs in the 5'-flanking region of porcine HSP70.2 are associated with semen quality traits in the hot season.

Animals↗

PubMed2002

Validation of the World Health Organization quality of life instrument in patients with HIV infection.

We studied the reliability and validity of the World Health Organization quality of life (WHOQOL) assessment instrument in patients with human immunodeficiency virus (HIV) infection. WHOQOL-BREF was used to assess 136 HIV-infected outpatients. The results were analyzed and compared with data from 213 healthy persons. The Cronbach's alpha for internal consistency ranged from 0.74 to 0.85 across domains in HIV-infected patients. The test-retest reliability ranged from 0.64 to 0.79 across domains at average 4-week retest interval. Factor analysis identified four major factors: social, psychological, environment, and physical, consistent with the four domains of the instrument. The scores of all four domains correlated positively with self-evaluated health status and happiness (r range: 0.52-0.60 and 0.55-0.73 across domains, respectively), and correlated negatively with the number and severity of symptoms (r range: -0.40 to -0.47 and -0.41 to -0.52, respectively). The scores of physical, psychological and social domains, but not the environment domain, discriminated between healthy persons and HIV-infected patients (all p < 0.01). We conclude that the WHOQOL-BREF can be a useful quality-of-life instrument in patients with HIV infection.

Adult↗