Search PubMed⌕ Search

Biomedical subjects

J T Wu

Publications and source records attributed to J T Wu.

At least 19 recordsLinked to original sources
PubMed2006

Occurrence of pathogens in raw and ready-to-eat meat and poultry products collected from the retail marketplace in Edmonton, Alberta, Canada.

A total of 800 meat and poultry products were purchased from the retail marketplace in Edmonton, Alberta, Canada. The products consisted of raw ground beef, chicken legs, pork chops, and ready-to-eat fermented sausage, roast beef, processed turkey breast, chicken wieners, and beef wieners. The samples were analyzed to determine the prevalence of Shiga toxin-producing Escherichia coli, Salmonella, Campylobacter spp., and Listeria monocytogenes. Shiga toxin-producing E. coli 022: H8 was found in one raw ground beef sample. Salmonella and Campylobacter were found in 30 and 62% of raw chicken legs, respectively. L. monocytogenes was found in 52% of raw ground beef, 34% of raw chicken legs, 24% of raw pork chops, 4% of fermented sausages, 3% of processed turkey breast, 5% of beef wieners, and 3% of chicken wieners. The occurrence of pathogens in this study is similar to that in retail products in many other international locales.

Alberta↗
PubMed2003

Syngeneic hematopoietic stem cell transplantation for women with metastatic breast cancer.

Metastatic breast cancer has been a common indication for autologous hematopoietic stem cell transplantation (HSCT). Previous reports indicate 3-year survival and progression-free survival (PFS) rates after autotransplant to be about 30 and 15%, respectively. Most deaths are from recurrent disease. One potential cause for high relapse rates is graft contamination with tumor. We describe 14 women with metastatic breast cancer transplanted between 1991 and 1998 with hematopoietic cells from identical twins. Median age was 41 y (range 34-50). Most women (12 of 14) were treated with mastectomy, and all received anthracycline-based regimens in their pretransplant course; nine women also received a taxane, seven radiotherapy and three hormonal therapy. Four women were in complete remission (one CR, three CRU) at transplant, five were in partial remission, two had stable disease and two had progressive disease. Eight women have died, one of treatment-related causes and seven of progressive breast cancer. Three-year survival was 48% (21-71%) and 3-year PFS was 21% (5-45%). Although the number of patients is small, outcomes for women transplanted with syngeneic grafts are similar to those of women receiving autologous grafts. This suggests that residual cancer in the patient is the major contributor to relapse after transplantation for breast cancer.

Adult↗
PubMed2002

Annual variation in semen characteristics of pigeons (Columba livia).

The purpose of this study was to evaluate annual semen characteristics of pigeons (Columba livia). Ten selected male pigeons, aged 2 to 5 yr were housed under natural environmental conditions, and semen collection was conducted via a digital massage twice weekly throughout the year. The success rate of semen collection in a total of 920 attempts was 40% (371/920) over the whole year. The highest success rate was 69% (55/80) in March followed by 66% (53/80) in November, whereas the lowest rates were in August (13%,10/80) and September (13%, 8/60) (P < 0.01). Volume of the ejaculate averaged 11.0 +/- 0.9 microL (mean +/- SEM). The greatest volume was obtained in November (13.5 +/- 1.0 microL), whereas the least was obtained in August (7.0 +/- 1.0 microL). The average sperm motility was 72 +/- 2% of all ejaculates, of which the highest motility (82 +/- 2%) was observed in March, whereas the least motility (48 +/- 3%) was in August. Sperm viability and sperm motility were positively correlated (r = 0.91; P < 0.01). Maximum sperm concentration was 4.9 +/- 0.4 x 10(9) sperm/mL noted in March, whereas the minimum was 3.8 +/- 0.2 x 10(9) sperm/mL observed in October. Donors generally exhibited susceptible (54%) or dull submission (43%), whereas resistance to handling was rarely observed (3%). During collections, a red (47%) or pink (44%) cloacal membrane was often observed, whereas during only 9% of the collections, the cloacal membrane was pale. When the ambient temperature decreased below 15 C, semen could not be obtained (0/80). A high amount of semen (>10 microL) was obtained when the temperature ranged between 19 and 24 C. Optimal sperm motility (approximately 80%) and viability (>85%) was observed when the temperature was between 18 and 24 C. At temperatures greater than 28 C, sperm motility and viability decreased. Sperm concentration was not significantly influenced by temperature fluctuations. In summary, annual variation in semen characteristics exhibited two peaks per year with mean motility and viability reaching peak annual values in March and November. Both of these months had mean ambient temperatures between 19 and 24 C, a range associated with maximal ejaculatory volumes.

Animals↗
PubMed2001

The development of a staggered parallel separation liquid chromatography/tandem mass spectrometry system with on-line extraction for high-throughout screening of drug candidates in biological fluids.

A new parallel liquid chromatography/tandem mass spectrometry (LC/MS/MS) system has been developed, in which the mass detector was shared between two staggered parallel chromatographic runs. Since the chromatography for biofluids assay generally requires good analyte retention and thus tends to leave large blank chromatographic windows, this parallel system allowed the efficient use of the mass detector during these blank windows, resulting in significantly improved sample throughput. Also, in order to remove the bottleneck in sample extraction for this parallel separation system, a high-flow extraction device was used to perform on-line extraction. This allowed for the direct injection of biofluids onto the system. The performance and capability of this system was evaluated in tests that contained a single analyte (oxazepam) and multiple analytes (12-in-1). The results indicated that the data generated from this system were comparable to those obtained on a conventional single-column system. An application of the system for high-throughput pharmacokinetic screening of drug candidates was also demonstrated.

Chromatography, Liquid↗
PubMed2001

Development of two ELISA for estrogen and progesterone receptor with sufficient sensitivity for fine needle aspirate and core biopsy.

The quantitative determination of estrogen and progesterone receptors (PR and ER) in breast tumor cytosol has been routinely performed in clinical laboratories to aid in the selection between hormonal and chemotherapy and also to predict prognosis. However, the small amount of tissue available from the increasingly popular fine-needle aspiration and core biopsies from breast cancer patients requires more sensitive immunoassays for receptor quantification. We have developed two sensitive immuno-assays for ER and PR on microplate with the use of recently available anti-ER and anti-PR antibodies of higher affinity and a powerful signal magnification agent, namely Amdex. The calibrator was a pooled breast tumor cytosol used as calibrator and calibrated against Abbott kits. The protein concentration of the cytosol and the upper normal cutoffs for our assays were reduced to approximately 0.2 mg/mL and 3 fmol/0.2 mg/mL, respectively. Both assays have sensitivities close to 1 fmol/mL, which are sufficiently sensitive for the receptor quantification in fine-needle aspiration biopsies and cord biopsies of breast tumor.

Antibodies, Monoclonal↗
PubMed2001

Characterization of serum and urinary chromogranin A by size exclusion chromatography: impact on calibrator selection and urinary assay.

Serum chromogranin A (CgA) is a useful marker for neuroendocrine tumors and is detectable in carcinomas at advanced stages. Elevated serum CgA is also an indicator of poor prognosis in prostate cancer and is useful for predicting the failure of hormonal therapy for prostate cancer patients. We found that CgA molecules with three different sizes could be detected in normal human serum. However, only the largest CgA molecule appears in patients with liver disease. Serum taken from cancer patients is composed predominantly of the middle-sized molecule, whereas the smallest CgA molecule was elevated in serum drawn from renal patients. Moreover, only the smallest CgA molecule was found in urine. We believe that the largest CgA molecule is metabolized by the liver, whereas the smallest CgA molecule is removed from the blood circulation via the kidney. Because the medium-sized CgA is the dominant molecule in both the cell medium of the tumor cell line SK-N-AS and sera from patients with malignant diseases, CgA from the cell medium was selected as the calibrator for the CgA ELISA assay. Our findings also suggest that it would not be possible to measure the urinary CgA to reflect the serum CgA concentration in order to detect pheochromocytoma among patients with hypertension.

Calibration↗
PubMed2001

High-speed liquid chromatography/tandem mass spectrometry using a monolithic column for high-throughput bioanalysis.

With the ever-increasing workload from a variety of in vitro and in vivo screening procedures, new analytical methodologies to perform bioanalysis in an accurate and high-throughput manner are in great demand. In this work, monolithic columns were used instead of conventional particulate HPLC columns to perform chromatographic separations. Because the pressure drop on a monolithic column was considerably lower than that on a particulate column, a high flow rate (6 mL/min) was used for a 4.6 x 50 mm monolithic column with a total backpressure of about 61 bar measured using acetonitrile/water (50:50). The capability of using a regular column length at high flow rates, combined with the extremely small dependency of separation efficiency on linear flow velocity, allowed for the generation of sufficient chromatographic resolving power in a significantly reduced runtime. As demonstrated in this work, a plasma extract of a mixture of tempazepam, tamoxifen, fenfluramine, and alprozolam were baseline separated within a total analysis time of one minute. An average peak width at half maximum of approximately one second was noted using a generic broad gradient. It was also found that the separation efficiency and signal/noise (S/N) ratios for this separation remained almost constant at flow rates of 1, 3, and 6 mL/min, respectively. The ruggedness of the separation was evaluated by injecting 600 plasma extracts containing the replicates of a standard curve of the above mixture during an overnight run. The chromatographic retention time, separation quality, peak response and sensitivity were highly reproducible throughout the run. This high-speed liquid chromatography/tandem mass spectrometry (LC/MS/MS) system has been used routinely in the authors' laboratory to support drug discovery programs.

Acetonitriles↗
PubMed2001

Multiple-sprayer tandem mass spectrometry with parallel high flow extraction and parallel separation for high-throughput quantitation in biological fluids.

In this work, an on-line four-column high-flow parallel extraction device was set up and interfaced to a four-column parallel separation system with a four-sprayer tandem mass spectrometric detector. This system allowed for the direct and simultaneous sampling, extraction, separation, and detection of four samples in biological fluids, resulting in significantly increased throughput. The performance of this system was evaluated using rat plasma samples spiked with methotrexate as a test compound. The results showed that the relative standard deviation for responses across the four parallel channels was less than 10% for a concentration range from 10 to 2500 nM, resulting in comparable sensitivity (slope of curve) for the analyte on all channels. A ruggedness test was performed using a mixed set of new and used extraction columns and the relative standard deviation in analyte response was found to be below 15%. The inter-channel crosstalk was measured to be about 0.1%. A comparison between the data generated on this system and on a conventional system for a rat pharmacokinetic study showed no more than 20% difference in measured concentrations. This parallel system is a viable tool for high-throughput bioanalysis in a drug discovery environment.

Animals↗
PubMed2001

Modeling and analysis of a virus that replicates selectively in tumor cells.

Replication-competent viruses have shown considerable promise in overcoming the inefficient gene transduction experienced by traditional gene therapy approaches to cancer treatment. The viruses infect tumor cells and replicate inside them, eventually causing lysis. Virus particles released during lysis are then able to infect other tumor cells, and, in this way, continuous rounds of infection and lysis allow the virus to spread throughout the tumor. Motivated by this novel cancer treatment, we formulate and analyse a system of partial differential equations that is essentially a radially-symmetric epidemic model embedded in a Stefan problem. We compare three, alternative virus-injection strategies: a fixed fraction of cells pre-infected with the virus are introduced throughout the entire tumor volume, within the tumor core, or within the tumor rim. For all three injection methods, simple and accurate conditions that predict whether the virus will control the tumor are derived.

Animals↗
PubMed2001

Development of an ELISA for the detection of serum chromogranin A (CgA) in prostate and non-neuroendocrine carcinomas.

INTRODUCTION: Chromogranin A (CgA) is a glycoprotein found in neuroendocrine cells and may be useful as a tumor marker for neuroendocrine tumors. METHODS: We developed an enzyme-linked immunosorbent assay (ELISA) for serum CgA on a microtiter plate. RESULTS: We established a reference range for both women and men of different age groups ranging from 20 to 80 years. Men appeared to have a slightly higher serum CgA concentration than women. This slight increase in serum CgA concentration was also found in both gender groups with advancing age. We also detected increased serum CgA in a variety of cancers and non-endocrine carcinomas: the majority of the increased serum CgA was associated with specimens containing highly increased concentration of tumor markers. In other words, increased serum CgA was found at later, more advanced stages of the disease in these patients. For patients with prostate cancer, serum CgA was increased much earlier than serum PSA in approximately one-third of prostate cancer patients developing resistance to hormonal therapy. CONCLUSIONS: The early rise of serum CgA provides an early signal for prostate cancer patients who developed resistance to hormonal therapy: this advance signal could create a critical window for therapy changes to be made before diseases progress to a fatal stage.

Adult↗
PubMed2001

Estimation of replicative senescence via a population dynamics model of cells in culture.

A simple mathematical model is developed for determining the time-varying fraction of senescent cells in culture in terms of the underlying probability distribution of the number of population doublings until senescence. This functional relationship is inverted, which allows for the estimation of the probability distribution of the number of population doublings until senescence given experimental data on the time-varying fraction of senescent cells. The relationship - in particular, the lag - between these two quantities is analyzed under the assumption that the number of population doublings until senescence follows the Weibull distribution. If the number of population doublings until senescence is geometrically distributed (i.e. the Weibull with shape parameter equal to one) then the cell culture appears immortal.

Cell Division↗