Search PubMed⌕ Search

Biomedical subjects

W A Anderson

Publications and source records attributed to W A Anderson.

At least 19 recordsLinked to original sources
PubMed2002

Expression of NK2 homologous transcripts during zebrafish development.

Expression of NK2 homologous transcripts during Zebrafish development was investigated by in situ hybridization technique. NK2 mRNA expression was first detected in a cluster of cells at the embryonic shield stage, and subsequently in the heart field of the 5-8-somite embryo. By the 15-17 somite stages, NK2 expressing cells were revealed in the midline of the developing embryo, and by 48 hpf within the heart tube of the larva. By 72 hpf, NK2 transcripts appeared in the jaw bones, pharyngeal arches, the cranium with minimal expression in striated muscle.

Amino Acid Sequence↗
PubMed2001

A biomarker approach to measuring human dietary exposure to certain phthalate diesters.

Three groups of eight volunteers were administered stable isotope-labelled phthalate diesters in a single dose and the amount of the corresponding phthalate monoesters excreted in the urine was measured. Amongst the phthalates administered were the symmetrical dibutyl-, di-2-ethyl- and diisooctyl- phthalates along with the unsymmetrical benzylbutylphthalate. The control group received no dose, the low dose group received 168-255 microg of each phthalate and the high dose group received 336 to 510 microg of each phthalate. The excreted phthalate monoesters were measured by LC-MS following hydrolysis of conjugates. The bulk of phthalate monoester was excreted in the first 24 hour period following the dose. For dibutylphthalate, 64% and 73% on a mole basis of the low, and high dose respectively was excreted as monobutylphthalate. For dioctylphthalate (sum of the 2-ethylhexyl and the isooctyl species) the yield was 14 and 12% of the low and high dose excreted as monooctylphthalate. For benzylbutylphthalate, 67% and 78% was eliminated as monobenzylphthalate and only 6% (measured for the high dose only) was eliminated as monobutylphthalate. These conversion factors can be used in future studies to assess exposure to phthalate esters via measuring urinary levels of the monoester metabolites.

Biomarkers↗
PubMed2001

A suggested outline for writing curriculum development journal articles: the IDCRD format.

BACKGROUND: During the past decade, medical school and residency faculty have been active in developing and revising curricula for medical education programs. Many of these curriculum development efforts ultimately are published in peer-reviewed professional journals as articles or abstracts. Unlike research publications, no uniform format currently exists for reporting curriculum development efforts in the peer-reviewed literature. SUMMARY: A suggested format for organizing curriculum development manuscripts consists of the introduction, development, curriculum, results, and discussion (IDCRD). Detailed descriptions of each section are discussed herein. CONCLUSIONS: The IDCRD manuscript outline is intended to provide useful guidance to medical educators in publishing their curriculum development efforts. Journal editors are encouraged to recognize the importance of providing uniform descriptions of curricula so that readers can benefit from the experience of others and replicate successful curriculum efforts.

Curriculum↗
PubMed2001

Peptidases affecting recombinant protein production by Streptomyces lividans.

The influence of peptidases on human interleukin-3 (rhIL-3) production by a recombinant Streptomyces lividans strain was investigated. The bacterium produced several general peptidases and tripeptidyl peptidases compromising the authenticity of rhIL-3. The level of peptidases depended on growth morphology. Growing S. lividans as compact pellets successfully reduced peptidase activity. Maximum general peptidase activity in pellet culture was delayed after maximum rhIL-3 concentration was achieved. The activity of the tripeptidyl peptidase was product (rhIL-3) associated.

Aminopeptidases↗
PubMed2001

Cathepsin B and complement C3 are major comigrants in the estrogen-induced peroxidase fraction of rat uterine fluid.

The luminal fluid of estrogen or DES-stimulated uterus of immature rats contains 10-12 isoforms of peroxidase between pI 4.5-6.0. N-terminal amino acid sequencing of diaminobenzidine-peroxidase bands eluted from IEF and SDS-PAGE gels showed the presence of cathepsin B and the complement family of proteins as the major comigrants. Sequential treatment of uterine fluid by cation, anion, and size exclusion chromatography resulted in a five-fold purification of peroxidase having a specific activity of 273 units/mg. Mass spectrometric studies of bands isolated from SDS-PAGE gels from the size-exclusion purified peroxidase fraction showed the presence of complement C3 along with novel previously uncharacterized proteins. Two dimensional electrophoresis followed by N-terminal amino acid sequencing confirmed the presence of cathepsin B isoforms and isoforms of a novel protein at approximately 87 kDa. Identification by mass spectrometry from the database for this novel protein was inconclusive but could most likely be a candidate for estrogen-induced peroxidase. Results conclusively prove that cathepsin B and complement C3 are major proteins in the estrogen-induced peroxidase fraction of uterine fluid.

Amino Acid Sequence↗
PubMed2001

Ultrastructural differentiation of cardiomyocytes of the zebrafish during the 8-26-somite stages.

We report cellular hypertrophy, mitochondrial proliferation and differentiation, myofibrillogenesis, and junctional maturation in cardiac progenitor cells between the 8 and 26-somite stages of the zebrafish, Danio rerio. However, coordinated contraction in embryonic cardiomyocytes did not occur until 26-somite stage when 'developed' intercalated discs, rooted sarcomeres, and a well-established sarcoplasmic reticulum had differentiated.

Animals↗
PubMed2000

The future relationship between the media, the food industry and the consumer.

The relationship between the media, the food industry and the consumer is probably at its lowest point as we start the new millennium. The frequency of food scares appears to be increasing and news reports sometimes seem both sensational and polarised. High profile issues like the development of bovine spongiform encephalopathy in the UK and the dioxin contamination of poultry products in Belgium have undermined consumer confidence in the food industry. The recent genetically modified foods' debate has served to demonstrate the gulf that has grown between the food industry, food safety experts and the public. This is a rift that has been exploited by environmental pressure groups and fuelled by the media. This paper examines some of the underlying causes of the current air of mistrust that seems to exist between the media, the food industry and the consumer. Also, by examining the projected trends in these root causes, it draws some conclusions for the future relationship between the parties involved and suggests some changes that may improve the present situation.

Consumer Product Safety↗
PubMed2000

Bacterial thermal death kinetics based on probability distributions: the heat destruction of Clostridium botulinum and Salmonella Bedford.

Despite the long history and excellent record of inactivation models used in thermal processing, there are relatively few approaches that attempt to describe the kinetics commonly observed. There are even fewer examples of models that allow the user to deal with the environmental conditions that influence these kinetics. We describe an approach that assumes a distribution of inactivation times within a population of bacterial cells. The concept allows for alternative interpretations of death kinetics and provides excellent descriptions of data generated with two important foodborne pathogens, Clostridium botulinum and Salmonella Bedford. The Salmonella Bedford data set used is unusual and perhaps unique in that it provides information where more than 50% of the population survival has been measured. These measurements are often overlooked or missed in experimental work but are essential when using a vitalistic approach, enabling calculation of a 50% lethal dose for destruction of bacteria. Use of the normal or Prentice distribution provided better fits to the data than other models commonly used to describe thermal death. There was no obvious bias in the fits even though significant tailing was evident. In addition, the procedure described allows data from all the conditions to be fitted rather than individual independent series. This enables a single equation to be derived that can be judged against the whole domain of the data. Approaches that provide accurate and unbiased descriptions of thermal death are likely to become increasingly important to ensure the safety of more marginal heat processes.

Clostridium botulinum↗
PubMed2000

Fibronectin/fibroblast growth factor/cell matrix signaling pathways and reciprocal membrane interaction may be the regulators of cell growth and apoptosis in Trypanosoma musculi in co-cultures with fibroblasts.

Trypanosoma musculi cultivated in medium containing serum alone or in the absence of fibroblasts in vitro were transformed into rounded, immotile cells, incapable of division and infectivity. Only in close contact with fibroblasts could the parasites survive and grow indefinitely. This report established the identity of the splenic 'sustentacular' cells as fibroblasts and utilized immunocytochemistry to demonstrate the putative cytoskeletal and membrane-associated molecules that may be involved in the control of growth and division, and apoptosis of T. musculi in vitro. The results indicated that cells that reacted intensely for fibroblast growth factor (FGF) also displayed a complex cytoskeletal system of F-actin bands underlying the plasma membrane of the fibroblast cell body and its numerous processes. Among the cytoskeletal and membrane glycoproteins, fibronectin, I-CAM, laminin, occludin, vinculin and desmin were most prominent. Fibronectin was most highly enhanced on the cell membrane and deposited as 'finger prints or tracks' on the extracellular culture surfaces. Transmission and scanning electron microscopy confirmed the intimate contact between trypanosomes and fibroblasts, however, neither membrane fusion or junctions were apparent. Our results suggested that a fibroblast-derived, membrane-associated factor appeared to be the putative growth regulator and apoptosis inhibitor in co-cultures of spleen-derived fibroblasts and T. musculi.

Animals↗
PubMed1999

Apoptosis and differentiation in the crypt-villus unit of the rat small intestine.

This investigation utilized immunocytochemical and fluorescent protocols to analyze the roles of cellular proliferation and apoptosis in the regulation of differentiation and senescence of the rat small intestinal mucosa. Specifically, the study localized apoptotic zones of the villus through the use of enzymatic tags; established the transition point between cell growth and differentiation, i.e. the point of no return where crypt cells differentiate into absorptive cells with barrier functions; and the role that plasmalemmal, cytoskeletal, junctional and extracellular matrix (ECM) elements may play in the regulation of differentiation and migration of epithelial cells from crypt to villus. Apoptosis was relegated to the villus tip forming a prominent 'apoptotic cuff' of cells. Close scrutiny of these cuffs reveals the presence of apoptotic cells adjacent to non-apoptotic (healthy) cells. Mid-villus epithelial cells were non-apoptotic and all cells in the crypt-villus unit expressed Bcl-2 activity. Intestinal lactase expression was prominent in post-mitotic cells along the villus, while cells in the crypt and base were negative for lactase activity. In contrast, all the cells of the crypt-villus unit were intensely reactive for F-actin. Close scrutiny of isolated cells and frozen sections indicates specific localization of actin in the microvillus region, apical cytoplasm, basolateral and lateral plasmalemma which was in close proximity to fibronectin in the basement lamina. Occludin positive junctional networks were prominent at villus tips, where senescent and apoptotic cells were also most prominent, suggesting that tight junctional integrity was essential to barrier, digestive and absorptive functions in all regions of the mucosa.

Actins↗
PubMed1998

Androgen-dependent gene expression of bone morphogenetic protein 7 in mouse prostate.

BACKGROUND: What is the molecular basis of the osteotrophic action of prostatic metastases? Demineralized bone matrix has the potential to induce new bone formation. The identification of bone morphogenetic proteins (BMPs) as the primary inducers of new bone formation in demineralized bone matrix has set the stage for studying prostate cancer-bone interrelationships. We have hypothesized that BMPs may be expressed in prostate and may be involved in the osteotrophic actions of metastatic prostate cancer cells. METHODS: Using polymerase chain reaction (PCR)-based quantitation, this study examined the presence of BMPs in mouse prostate and their potential regulation by orchidectomy and androgen replacement. RESULTS: BMP-7 and BMP-4 genes were expressed in mouse prostate. Quantitative PCR analysis showed that the BMP-7 mRNA level was significantly decreased following orchidectomy and increased by testosterone and dihydrotestosterone. Therefore, the BMP-7 mRNA level is androgen-dependent. On the other hand, BMP-4 was expressed constitutively in the prostate. CONCLUSIONS: The regulated expression of BMP-7 mRNA in the prostate suggests that BMP-7 may explain in part the stimulation of bone formation and osteosclerosis by metastatic prostate adenocarcinoma.

Animals↗
PubMed1998

The analysis of cyhexatin residues in apples, pears and kiwi fruit using inductively coupled plasma mass spectrometry as an initial screen for total tin, with confirmation by gas chromatography-mass spectrometry.

Inductively coupled plasma-mass spectrometry (ICP-MS) has been used to determine concentrations of total tin in samples of apples, pears and kiwi fruit, following acid digestion. It was found that the background levels of tin in these fruits were normally below 0.06 mg/kg, which was equivalent to the target reporting limit for cyhexatin for this work of 0.2 mg/kg. The procedure was used to screen a total of 72 retail samples. Three apple samples contained tin at concentrations greater than 0.06 mg/kg. These three samples were re-analysed by a second confirmatory method using gas chromatography-mass spectrometry (GC-MS) as the determinative step. Results obtained by this method demonstrated that in fact, none of the samples contained cyhexatin residues at or above a reporting limit of 0.1 mg/kg. The use of ICP-MS as a preliminary screen substantially reduced the number of samples requiring analysis by GC-MS, thus reducing the cost of the survey (in terms of staff hours) by approximately 30%. The screening method could potentially be applied to other organometallic pesticide residues.

Chromatography, Gas↗
PubMed1998

Biphasic thermal inactivation kinetics in Salmonella enteritidis PT4.

The thermal inactivation kinetics of Salmonella enteritidis PT4 between 49 and 60 degrees C were investigated. Using procedures designed to eliminate methodological artifacts, we found that the death kinetics deviated from the accepted model of first-order inactivation. When we used high-density stationary-phase populations and sensitive enumeration, the survivor curves at 60 degrees C were reproducibly biphasic. The decimal reduction time at 60 degrees C (D60 degrees C) of the tail subpopulation was more than four times that of the majority population. This difference decreased with decreasing temperature; i.e., the survivor curves became more linear, but the proportion of tail cells remained a constant proportion of the initial population, about 1 in 10(4) to 10(5). Z plots (log D versus temperature) for the two populations showed that the D values coincided at 51 degrees C, indicating that the survivor curves should be linear at this temperature, and this was confirmed experimentally. Investigations into the nature of the tails ruled out genotypic differences between the populations and protection due to leakage from early heat casualties. Heating of cells at 59 degrees C in the presence of 5 or 100 micrograms of chloramphenicol per ml resulted in reductions in the levels of tailing. These reductions were greatest at the higher chloramphenicol concentration. Our results indicate that de novo protein synthesis of heat shock proteins is responsible for the observed tailing. Chemostat-cultured cells heated at 60 degrees C also produced biphasic survivor curves in all but one instance. Cells with higher growth rates were more heat sensitive, but tailing was comparable with batch cultures. Starved cells (no dilution input) displayed linear inactivation kinetics, suggesting that during starvation a rapid heat shock response cannot be initiated.

Chloramphenicol↗
PubMed1997

Perioperative risk factors affecting hospital stay and hospital costs in open heart surgery for patients > or = 65 years old.

OBJECTIVE: Demographic changes, associated with increased demands for open heart surgery in the elderly, place increased burden on financial resources. To evaluate perioperative risk factors affecting incidence of hospital events and estimation of hospital charges, 2577 patients > or = 65 years (range 65-91), operated on from January 1991 to December 1994, were compared with a concurrent cohort of 2642 younger patients. METHODS: Statistical analysis, by surgical procedure, focused on hospital mortality, key postoperative complications affecting length of hospital stay and hospital charges. RESULTS: Overall hospital mortality was 4.7%, 3.5% in younger patients versus 6.1% in the older group (P << 0.01). Mortality was significantly lower in patients less than 65 years undergoing coronary artery bypass grafting (3% versus 5%, P < 0.01) and valve replacement (4% versus 9%, P = 0.01). Significant risk factors for hospital death in the elderly: diabetes (P < 0.01), hypertension (P < 0.01), myocardial infarction (P < 0.01) and congestive heart failure (P < 0.01). Significant postoperative events, more common in older patients, included prolonged ventilation (P << 0.01), congestive heart failure (P << 0.01), infection (P << 0.01), cerebrovascular accident (P < 0.01), and intra aortic balloon pump (P < 0.01). Incremental risk factors for morbidity in the elderly were: higher New York Heart Association class, congestive heart failure, emergent operation, and female gender. Mean length of hospital stay for the < 65 group was 15.3 versus > 19.5 days for the > 65 group (P << 0.01). Length of stay over 18 days positively correlated with increased morbidity in both age groups. For patients > or = 65 years of age, the average hospital charge for open heart surgery was 172% higher for patients with a length of stay greater than 18 days compared with 165% for patients less than 65 years of age. CONCLUSIONS: Higher operative mortality and longer length of stay in elderly patients, resulting in increased health care costs, was associated with more co-morbidities. These results suggest interventions designed to reduce congestive heart failure and other co-morbidities may improve patient's recovery and reduce costs.

Adult↗
PubMed1997

Enhancement of the biodegradability of model wastewater containing recalcitrant or inhibitory chemical compounds by photocatalytic pre-oxidation.

m-Dinitrobenzene, diphenylamine and resorcinol, three aromatic compounds found inhibitory or recalcitrant to biological treatments, were chosen as model chemicals for this study on the integration of photocatalytic-biological treatments. The degradation of each of these compounds was achieved by ultraviolet photocatalytic oxidation, leading to the formation of intermediate compounds. The photocatalytic treatment was performed in a TiO2 slurry reactor containing an aqueous solution of one of the three chemicals. The biodegradability of model wastewater treated photocatalytically was measured in terms of BOD1/TOC. Intermediate compounds that appeared at early stages of the photocatalytic degradation of m-dinitrobenzene or diphenylamine seemed to be more inhibitory than the parent compounds but this was not the case for resorcinol. A substantial improvement in BOD1/TOC could be achieved, but it required the mineralization of at least 80% of the organic carbon originally in the water. Microtox toxicity results confirmed the BOD1/TOC trends for diphenylamine.

Biodegradation, Environmental↗
PubMed1997

Faculty development for ambulatory care education.

Faculty play an important role in the delivery of quality instruction in the ambulatory setting. As medical schools and residency programs move more clinical training to ambulatory care settings, more faculty must be recruited and trained. Medical educators have attempted to prepare faculty to teach in ambulatory care settings by conducting faculty development programs. This study documents the current practices of a sample of 14 peer-nominated medical educators who conduct this type of faculty development program. The authors conducted telephone interviews to learn what these educators taught, how they conducted and evaluated their programs, and the theoretical framework guiding their selection of program content and format. Results show that these faculty development programs were delivered almost exclusively in the workshop format, and that there was remarkable similarity in the topics and strategies used. Evaluation was generally limited to satisfaction ratings. Based on the results of this study, the authors recommend that faculty development programs that now emphasize the teaching encounter itself should give equal emphasis to (1) the importance of pre-instructional planning; (2) teaching faculty how to employ post-instructional techniques such as reflection; and (3) training learners and clinic staff to collaborate with faculty in the learning process.

Ambulatory Care↗
PubMed1997

Estrogen receptor, growth factor receptor and protooncogene protein activities and possible signal transduction crosstalk in estrogen dependent and independent breast cancer cell lines.

Binding of estrogen to its receptor (ER) activates early genes that drive responsive cells through the proliferative phase. Earlier studies to evaluate the expression of protooncogenes, growth factors, growth factor receptor and steroid hormone receptor gene activities in the rat uterine system indicated complex pathways that involve significant 'crosstalk' between ER-systems and signal transduction pathways (Bhattacharyya et al., 1994). To analyze the interactions between these factors, we examined two well characterized estrogen dependent (MCF-7) and estrogen independent (MDA-MB-231) human breast cancer cell lines. Antibodies to estrogen receptor, epidermal growth factor receptor, c-Fos, c-Jun, and Ras proteins, protein kinases involved in receptor tyrosine kinase signal transduction pathway, MEK1 and phosphotyrosine were utilized in immunocytochemical localization experiments to evaluate temporal expression of these factors in response to estrogen treatment. ER, which was diminished in MCF-7 cells grown in estrogen-stripped medium, increased 9-fold in estrogen-reconstituted medium by 120 min. Fos and Jun appeared at nuclear and perinuclear cytoplasmic sites within 60 min after estrogen treatment in MCF-7 cells. Fos/Jun proteins were prominent in MDA-MB-231 cells, especially in association with actin filaments. Immunolabeling studies revealed no EGF-r in MCF-7 cells, while MDA-MB-231 cells contained intense EGF-r labeling in the plasma membrane. Ras protein was prominent in the cytoplasm and at the cell surface within 60 min after treatment of MCF-7 cells with estrogen. Ras was intense in MDA cells. Similarly, MCF-7 and MDA cells contained high concentrations of MEK1 and phosphotyrosine (pTyr) containing proteins in their cytoplasm and immunolabeling remained high as long as MCF-7 cells were grown in medium containing estrogen. It is speculated that MEK1 (cytoplasmic) functioning through Fos/Jun or Myc/Max (nuclear) may regulate the activity of AP-1 transcription factor. In all cases however, MEK1 and pTyr protein labeling was more intense in the highly metastatic and hormone independent MDA-MB-231 breast cancer cells. Results revealed signal transduction pathway proteins in ER+ estrogen dependent cells suggesting possible crosstalk between both receptor pathways during the proliferative phase of MCF-7 cells.

Actins↗