Teaching blood pressure measurement: CD-ROM versus conventional classroom instruction.
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Adolescent↗
Biomedical subjects
M Huynh
Publications and source records attributed to M Huynh.
Evaluation of the somatogenic activity of bovine placental lactogen with cell lines transfected with the bovine somatotropin receptor.
Studies have shown that bovine placental lactogen (bPL) has partial somatogenic activity in vivo even though binding results clearly indicate bPL does not cause homodimerization of the bovine somatotropin receptor (bST-R). To help understand the receptor binding versus biological activity of bovine somatotropin (bST) and bPL we have developed a homologous model system. Full length bST-R was stably transfected into a murine lymphoid cell line, Ba/F3 and a hamster kidney cell line, BHK. From both transfected cell lines, clones were isolated (Ba/F3-C1 and BHK-24) which demonstrated specific binding of bST and, or bPL. Bovine ST stimulated proliferation of the Ba/F3-C1 clonal line over a dose range of 10 to 3000 pM with an EC50 of 100 pM. A bST variant (des 1-4 bST) and porcine ST (pST) which both have approximately 10% of the binding affinity for bST-R as native bST were 1 and 10% as potent as bST in this bioassay, respectively. This suggests that affinity and biological activity are correlated for this system. Proliferation was initiated through the bST-R because addition of a monoclonal antibody which recognizes the extracellular domain of bST-R and inhibits binding of bST to its receptor, inhibited bST-stimulated mitosis. However, even though the affinity of bPL for the bST-R is similar to that of bST, bPL antagonized the proliferative action of bST with an IC50 of 1 nM. Components of the somatogenic signal transduction pathway were also evaluated in both cell lines. Addition of bST to the cell cultures increased phosphorylation of JAK2 in Ba/F3-C1 and BHK-24 cells in a dose-responsive manner but bPL failed to increase phosphorylation of JAK2 in either cell line. In summary, these data support the hypothesis that ST-R homodimerization is necessary for bioactivity in this model system but fail to explain apparent somatogenic activity of bPL in vivo.
Animals↗
Attenuation of IL-5-mediated signal transduction, eosinophil survival, and inflammatory mediator release by a soluble human IL-5 receptor.
A soluble form of the human IL-5R alpha-chain (IL-5Ra) that contains the extracellular IL-5 binding domain has been evaluated for its effect on IL-5 binding to and activation of human eosinophils and basophils. The truncated receptor was expressed in Escherichia coli and recovered in biologically active form following renaturation and anion exchange chromatography. The soluble receptor formed a 1/1 complex with IL-5 in solution and bound IL-5 with affinity comparable to that of cell-associated IL-5Ra. Soluble IL-5Ra also competed with IL-5 for binding to the native alpha beta IL-5R on human cells and inhibited IL-5-mediated receptor activation and inflammatory mediator production. In this regard, the soluble receptor prevented IL-5-induced tyrosine phosphorylation of JAK2 kinase and IL-5R beta-chain and inhibited IL-5 priming of leukotriene C4 release by human basophils. However, the E. coli-derived receptor failed to inhibit IL-5 in longer term assays, including eosinophil survival and TF-1 cell proliferation, possibly due to its propensity to aggregate in a time- and temperature-dependent manner. In contrast, we observed that a soluble IL-5Ra derived from baculovirus-infected cells was less prone to aggregate and effectively antagonized IL-5-induced cell proliferation and survival. These findings indicate that the extracellular portion of the human IL-5Ra chain can prevent association of IL-5 with cell surface receptors and can attenuate signal transduction, mediator release, and survival of inflammatory cells. As such, soluble IL-5R may be useful in treating diseases such as human asthma, in which pulmonary injury is associated with the activity of IL-5R-bearing cells.
Basophils↗
TGF-alpha, EGF, and their cognate EGF receptor are co-expressed with desmin during embryonic, fetal, and neonatal myogenesis in mouse tongue development.
The developing mouse tongue provides a model for discrete patterns of morphogenesis during short periods of embryonic development. Occipital somite-derived myogenic cells interact with cranial neural crest-derived ecto-mesenchymal cells to form the musculature of the tongue. The biochemical signals that control close range autocrine and/or paracrine signaling processes required to establish the fast-twitch complex tongue musculature are not known. The present study was designed to test the hypothesis that desmin, epidermal growth factor (EGF), and transforming growth factor-alpha (TGF alpha) and their cognate receptor, epidermal growth factor receptor (EGFr), are co-expressed during tongue myogenesis and define specific developmental stages of tongue muscle cell differentiation. To test this hypothesis, we performed studies to analyze the timing, position, and concentration of desmin, TGF alpha, EGF, and EGFr from embryonic day 9 (E9) through birth in Swiss Webster mouse tongue development. Desmin, TGF alpha, EGF, and EGFr co-localized to cells of myogenic lineage in the four occipital somites and subsequently in myoblasts and myotubes from E9 through E17. By newborn stage, desmin is localized to discrete regions in myofibers corresponding to Z-line delimiting sarcomeres, and A-band within sarcomeres; immunostaining for desmin, TGF alpha, and EGF persisted in differentiated myotubes and striated skeletal muscle. Desmin increased from 0.01% at E11 to 0.51% of the total protein by E17 and at birth. Concomitantly, the patterns and increases in TGF alpha, EGF, and EGFr showed significant increases during the same developmental period. The temporal and positional co-localization of TGF alpha, EGF, and EGFr support the hypothesis that autocrine and paracrine regulation of desmin by actions of growth factor ligand and receptor defines critical stages of tongue myogenesis.
Animals↗
Dietary retinoic acid inhibits mouse skin carcinogenesis irrespective of age at initiation.
In the two-stage protocol of skin carcinogenesis, the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) is applied to the skin of mice at around seven weeks of age. We previously performed DMBA initiation at three weeks of age to study the effect of pharmacological (30 micrograms/g diet) dietary retinoic acid (RA) on skin carcinogenesis. In this study we asked whether dietary pharmacological RA is equally effective against skin carcinogenesis when mice are initiated with (DMBA) at 7 weeks of age and then subjected to weekly applications of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) or mezerein (MEZ) for 20 weeks. Similar to the three-week initiation protocol, high dietary RA inhibited papilloma incidence and yield in MEZ- but not in TPA-promoted female SENCAR mice. In addition, carcinoma incidence and yield were decreased by high dietary RA in TPA- as well as MEZ-treated mice. These data demonstrate that the high dietary RA diet is as effective in inhibiting papilloma and carcinoma formation when the DMBA is applied at seven weeks of age as at three weeks.
9,10-Dimethyl-1,2-benzanthracene↗
High dietary retinoic acid inhibits tumor promotion and malignant conversion in a two-stage skin carcinogenesis protocol using 7,12-dimethylbenz[a]anthracene as the initiator and mezerein as the tumor promoter in female SENCAR mice.
We studied the effect of dietary retinoic acid (RA) in a two-stage protocol of skin carcinogenesis in female SENCAR mice. At 3 weeks of age mice were initiated with 7,12-dimethylbenz[a]anthracene (DMBA, 20 micrograms) and promoted with either 12-O-tetradecanoylphorbol-13-acetate (TPA, 2 micrograms) once per week or mezerein (MEZ, 4 micrograms) twice per week for 20 weeks. At the week of DMBA initiation mice were also put on a purified diet containing either 3 (physiological dose) or 30 micrograms (pharmacological dose) of RA/g of diet. High dietary RA significantly inhibited papilloma yield but not incidence in the MEZ-promoted group. Papilloma incidence and yield were also lower in the MEZ- than in the TPA-treated groups. Cumulative carcinoma incidence and yield, and conversion efficiency (= (carcinomas/maximal papillomas) x 100%), were all decreased by high dietary RA in both MEZ- and TPA-treated groups. These results demonstrate that high dietary RA inhibited skin carcinogenesis in MEZ-promoted mice at the stages of tumor promotion and malignant conversion, while this inhibition occurred only at the malignant conversion stage in TPA-promoted mice.
9,10-Dimethyl-1,2-benzanthracene↗
Purification and kinetic parameters of bovine liver N-acetylglucosamine-1-phosphodiester alpha-N-acetylglucosaminidase.
The enzyme N-acetylglucosamine phosphodiester alpha-N-acetylglucosaminidase (phosphodiester alpha-GlcNAcase) catalyzes the second step in the formation of the mannose 6-phosphate targeting signal on lysosomal enzyme oligosaccharides by removing GlcNAc residues from GlcNAc-alpha-P-mannose moieties, which are formed in the first step by UDP-N-acetyl-glucosamine:glycoprotein N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase). Phosphodiester alpha-GlcNAcase, a membrane-bound enzyme, has been purified about 3,000-fold from bovine liver to apparent homogeneity using detergent solubilization, fractionation on DEAE-cellulose, affinity chromatography on lectin-Sepharose columns, gel filtration, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme migrated as 129- and 121-kDa species on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Since both bands had the same amino-terminal sequence, the smaller species is presumed to be derived from the larger by proteolysis. Kinetic analysis of bovine phosphodiester alpha-GlcNAcase with enzymatically synthesized artificial and biological substrates indicates that phosphodiester alpha-GlcNAcase requires GlcNAc-alpha-P R for substrate and that when R contains the Man alpha 1,2Man linkage the substrate binding is most effective. Unlike GlcNAc-phosphotransferase, bovine phosphodiester alpha-GlcNAcase does not require a protein recognition determinant on lysosomal enzyme substrates.
Amino Acid Sequence↗
A CD-ROM tutorial for physical examination.
In 1998 the Committee for University Teaching and Staff Development (CUTSD) awarded a grant of $47,975 to develop an interactive CD-ROM tutorial program to facilitate teaching the process of physical examination of the abdomen, lungs and thorax, to students of nursing. This program was developed to complement current teaching methods and make it possible for tutors to use the available class time to further address students' individual learning needs. It was developed to enable flexible delivery of content, to provide a front seat view of the demonstration of the procedures, and simulated practice opportunities in the safety and privacy of computer simulation. The program was not intended to replace hands-on practice as this learning medium does not address the kinaesthetic component of performing physical examination but it is expected to hasten the development of confidence in practice by strengthening the user's knowledge of the techniques and the sequence of physical examination. Through providing the opportunity to elicit inspection, palpation, percussion and auscultation examination findings in the context of 10 case studies of patients with health problems, it is also expected to facilitate recognition of abnormalities and their significance for health care students who have little clinical experience. The program has been evaluated by senior nursing students for technical problems, effectiveness as a learning aid and user friendliness. Over all, 92% (n=38) of the students considered that the program assisted them to learn physical examination of the abdomen, thorax and lungs and 95% were satisfied with the quality of the product and found that the sounds and images helped their understanding. The content of the program was considered to be logically sequenced, to have assisted understanding, and the case studies were a valuable learning aid. The evaluation data from this trial also indicates that students would like to learn about physical examination of other body systems using this medium.
Attitude of Health Personnel↗
Modeling SSI financial eligibility and simulating the effect of policy options.
This article simulates eligibility for Supplemental Security Income (SSI) among the elderly, analyzes factors affecting participation, and looks at the potential effects of various options to modify financial eligibility standards for the federal SSI program. We find that in the estimated noninstitutional elderly population of 30.2 million in the United States in 1991, approximately 2 million individuals aged 65 or older were eligible for SSI (a 6.6 percent rate of eligibility). Our overall estimate of the rate of participation among eligible elderly is approximately 63 percent, suggesting that more than a third of those who are eligible do not participate in the program. The results of our analysis of factors affecting participation among the eligible elderly show that expected SSI benefits and a number of demographic and socioeconomic variables are associated with the probability of participation. We also simulate the effects of various policy options on the poverty rate, poverty gap, annual program cost, the number of participants, and the average estimated benefits among participants. The simulations consider the potential effects of five policy alternatives: Increase the general income exclusion (GIE) from $20 to $80. Increase the earned income exclusion (EIE) from $65 to $260. Increase the federal benefit rate (FBR) by $50 for individuals and $75 for couples and eliminate the GIE. Increase the asset threshold to $3,000 for individuals and $4,500 for couples. Increase the asset threshold to $6,000 for individuals and $9,000 for couples. Using 1991 microdata from the Survey of Income and Program Participation (SIPP) matched to Social Security Administration administrative records and making adjustments reflecting aggregate program statistics, we present the results of our simulations for December 1999. The results show substantial variation in the simulated effects of the five policy alternatives along the various outcome dimensions considered. The simulated effects on the poverty gap of the elderly population range from a 7.9 percent reduction ("Increase the GIE from $20 to $80") to a 0.1 percent reduction ("Increase the EIE from $65 to $260"). All simulated interventions are expected to increase the rate of SSI participation among the elderly from a high of 20.3 percent ("Increase the GIE from $20 to $80") to a low of 0.5 percent ("Increase the EIE from $65 to $260"). We also find that the interventions that have greater estimated effects in terms of increased participation and reduced poverty tend to cost more. At the high end, we estimate that increasing the GIE from $20 to $80 could raise annual federal SSI cash benefit outlays by about 46 percent, compared with only 0.9 percent for increasing the EIE from $65 to $260. Similar to the EIE intervention, raising the resource thresholds by 50 percent would reduce the overall poverty gap of the elderly by only 0.2 percent, would increase SSI participation only modestly (by 1.3 percent), but would entail slightly higher program costs (by 1.4 percent). Increasing the asset threshold by 200 percent would have higher estimated effects on all three outcomes, but it would still be associated with relatively low increases in both costs and benefits. Finally, the simulated effects on the three key outcomes of increasing the FBR by $50 for individuals and $75 for couples, combined with eliminating the GIE, are relatively large but are clearly less substantial than increasing the GIE from $20 to $80. This work relies on data from the SIPP matched to administrative data on federal SSI benefits that provide a more accurate picture of SSI participation than has been feasible for previous studies. We simulate eligibility for federal SSI benefits by applying the program rules to detailed information on the characteristics of individuals and couples based on the rich array of demographic and socioeconomic data in the SIPP, particularly the comprehensive information SIPP provides on assets and monthly income. A probit model is estimated to analyze factors affecting participation among the eligible elderly. Finally, we conduct the policy simulations using altered program rules represented by the policy alternatives and predicted participation probabilities to estimate outcomes under simulated program rules. We compare those simulated outcomes to observed outcomes under current program rules. The results of our simulations are conditional on the characteristics of participants and eligibles in 1991, but they also reflect aggregate adjustments capturing substantial changes in overall participation and program benefit levels between 1991 and 1999.
Age Factors↗