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Biomedical subjects

Michael Sullivan

Publications and source records attributed to Michael Sullivan.

15 recordsLinked to original sources
PubMed2006

Mast cells dysregulate apoptotic and cell cycle genes in mucosal squamous cell carcinoma.

BACKGROUND: Mucosal squamous cell carcinoma of the head and neck is a disease of high mortality and morbidity. Interactions between the squamous cell carcinoma and the host's local immunity, and how the latter contributes to the biological behavior of the tumor are unclear. In vivo studies have demonstrated sequential mast cell infiltration and degranulation during squamous cell carcinogenesis. The degree of mast cell activation correlates closely with distinct phases of hyperkeratosis, dysplasia, carcinoma in-situ and invasive carcinoma. However, the role of mast cells in carcinogenesis is unclear. AIM: This study explores the effects of mast cells on the proliferation and gene expression profile of mucosal squamous cell carcinoma using human mast cell line (HMC-1) and human glossal squamous cell carcinoma cell line (SCC25). METHODS: HMC-1 and SCC25 were co-cultured in a two-compartment chamber, separated by a polycarbonate membrane. HMC-1 was stimulated to degranulate with calcium ionophore A23187. The experiments were done in quadruplicate. Negative controls were established where SCC25 were cultured alone without HMC-1. At 12, 24, 48 and 72 hours, proliferation and viability of SCC25 were assessed with MTT colorimetric assay. cDNA microarray was employed to study differential gene expression between co-cultured and control SCC25. RESULTS: HMC-1/SCC25 co-culture resulted in suppression of growth rate for SCC-25 (34% compared with 110% for the control by 72 hours, p < 0.001), and dysregulation of genes TRAIL, BIRC4, CDK6, Cyclin G2 and CDC6 in SCC25. CONCLUSION: We show that mast cells have a direct inhibitory effect on the proliferation of mucosal squamous cell carcinoma in vitro by dysregulating key genes in apoptosis and cell cycle control.

Journal Article↗
PubMed2006

Beamline X29: a novel undulator source for X-ray crystallography.

A high-flux insertion device and beamline for macromolecular crystallography has been built at the National Synchrotron Light Source (NSLS) that employs a mini-gap undulator source developed by the NSLS. The mini-gap undulator at beamline X29 is a hybrid-magnet device of period 12.5 mm operating at proven gaps of 3.3-10 mm. The beamline provides hard X-rays for macromolecular crystallography experiments from the second and third harmonics over an energy range of 5-15 keV. The X-ray optics is designed to deliver intense and highly collimated X-rays. Horizontal focusing is achieved by a cryogenically cooled sagittally focusing double-crystal monochromator with approximately 4.1:1 demagnification. A vertical focusing mirror downstream of the monochromator is used for harmonic rejection and vertical focusing. The experimental station hosts an Area Detector Systems Quantum 315 CCD detector with 2.2 s readout time between exposures and Crystal Logic goniostat for crystal rotation and detector positioning. An auto-mounter crystal changer has been installed to facilitate the high-throughput data collection required by the major users, which includes structural genomics projects and the Macromolecular Crystallography Research Resource mail-in program. X29 is 10(3) times brighter than any existing bending-magnet beamline at NSLS with an actual flux of 2.5 x 10(11) photons s(-1) through a 0.12 mm square aperture at 11.271 keV.

Crystallography, X-Ray↗
PubMed2006

Sonic hedgehog expression in the development of hindgut in ETU-exposed fetal rats.

Sonic hedgehog (Shh) has been shown to be involved in the morphogenesis of many organ systems including the notochord, floor plate and limbs, as well as in the development of the left-right axis in vertebrates. Recent evidence suggests the Shh cascade plays a crucial role in the development of the foregut and hindgut. We have previously shown that prenatal exposure of fetal rats to ethylenethiourea (ETU) induces hindgut malformations and other abnormalities of the VACTERL association. The aim of this study was to determine the pattern of expression of Shh and its downstream genes during hindgut development in ETU-exposed embryos with anorectal malformations (ARMs). Pregnant Sprague-Dawley rats were mated together overnight and a positive vaginal plug was marked as gD0. On gD10, 1% ETU (125 mg/kg) was given to the experimental group and controls received the same volume of saline. Embryos were collected from both groups at gD12-16. The developing hindgut of each embryo was dissected under magnification and snap frozen. Highly purified RNA was isolated from each hindgut and first strand cDNA was prepared with appropriate negative controls. Reverse transcriptase (RT) polymerase chain reaction (PCR) was done to determine the transcripts of Shh in each sample and quantitative real-time PCR was carried out to show relative quantitative expression of Shh at each time point. Shh was detected in all samples confirming that Shh is active during the process of hindgut development in fetal rats. Relative quantitation demonstrated that Shh expression shows time-dependent changes in the developing hindgut of ETU-exposed rat embryos, and when results were compared with control samples, there was significant decrease in expression on gD14 and 15, when the cloaca normally separates into the rectum and urethra occurs in the rat fetus. The misregulated expression of Shh in the hindgut of ETU-exposed rat embryos suggests that ETU may interfere with Shh signalling. Downregulation at the time of cloacal separation into rectum and urethra indicates that Shh plays a crucial role in the development of hindgut.

Abnormalities, Multiple↗
PubMed2006

Sonic hedgehog, BMP4, and Hox genes in the development of anorectal malformations in Ethylenethiourea-exposed fetal rats.

BACKGROUND: shh signaling pathway has been shown to be involved in the morphogenesis of many organ systems. In this study, we investigated the expression of shh and its targets, BMP4 and Hox genes, in the development of anorectal malformations in Ethylenethiourea (ETU)-exposed embryos. METHODS: We used ETU murine model of the vertebral, anal, cardiac, tracheoesophageal, renal, and limb association. Ethylenethiourea 1% (125 mg/kg) was given to the pregnant females via gavage feeding on gestational day (gD) 10 and saline to control animals. Embryos were collected at gD12 to gD16 and gD21; hindguts were dissected and snap frozen. Highly purified RNA was isolated, and expression of shh, BMP4, Hoxa13, and Hoxd13 genes was confirmed with RT-PCR. Relative quantitative expression of shh and target genes at each time point was done with SYBR Green I qPCR. Normalized gene of interest expression was calculated by geNorm, and data analysis was done with 2-tail Student t test. RESULTS: shh, BMP4, Hoxa13, and Hoxd13 transcripts were detected in all samples, confirming that shh cascade is active during the process of hindgut development in fetal rats. Relative quantitation demonstrated that shh cascade expression shows time-dependent changes in the developing hindgut. CONCLUSION: This study shows that ETU disturbs the expression of shh signaling pathway during the development of hindgut. We provide evidence that shh plays a pivotal role in the hindgut morphogenesis, and its misexpression affect the expression of targets, BMP4 and Hox genes.

Anal Canal↗
PubMed2006

TANF policy: past, present, and future directions.

The purpose of this article is to offer a brief and concise history of relevant public welfare policies for a discussion of the effects of public welfare reform, and how it impacts families in ways not comprehensively understood. Social scientists' concerns about the potential for the families to be thrust into an "extreme poverty" status due to the forced workforce participation requirement and expiration of time limited benefits is discussed. A second concern regarding a "one size fits all" approach to work requirements for TANF recipients being unrealistic and insensitive is also discussed. The authors recommend a comprehensive multi-system analysis to determine the impact of welfare reform. There is also a recommendation that the workforce requirements should correlate to an assessment score based on the ability of welfare recipients to function in identified areas. Implications of maintaining a welfare reform policy status quo are identified.

Employment↗
PubMed2005

Identification and characterization of PDE4A11, a novel, widely expressed long isoform encoded by the human PDE4A cAMP phosphodiesterase gene.

PDE4A11 is a novel cAMP-specific phosphodiesterase that is conserved in humans, mouse, rat, pig, and bat. Exon-1(4A11) encodes its unique, 81 amino acid N-terminal region. Reverse-transcriptase polymerase chain reaction performed across the splice junction, plus identification of expressed sequence tags, identifies PDE4A11 as a long isoform possessing UCR1 and UCR2 regulatory domains. Transcript analysis shows that PDE4A11 is widely expressed compared with PDE4A10 and PDE4A4B long isoforms. Truncation analysis identifies a putative promoter in a 250-base pair region located immediately upstream of the start site in Exon-1(4A11). Recombinant PDE4A11, expressed in COS-7 cells, is a 126-kDa protein localized predominantly around the nucleus and in membrane ruffles. PDE4A11 exhibits a K(m) for cAMP hydrolysis of 4 microM, with relative V(max) similar to that of PDE4A10 and PDE4A4B. PDE4A11 is dose-dependently inhibited by rolipram, 4-[(3-butoxy-4-methoxyphenyl)-methyl]-2-imidazolidinone (Ro 20-1724), cilomilast, roflumilast, and denbufylline, with IC(50) values of 0.7, 0.9, 0.03, 0.004, and 0.3 microM, respectively. Soluble and particulate PDE4A11 exhibit distinct rates of thermal inactivation (55 degrees C; T((0.5)) = 2.5 and 4.4 min, respectively). Elevating cAMP levels in COS-7 cells activates PDE4A11 concomitant with its phosphorylation at Ser119 by protein kinase A (PKA). PDE4A11 differs from PDE4A4 in sensitivity to cleavage by caspase-3, interaction with LYN SH3 domain, redistribution upon long-term rolipram challenge, and sensitivity to certain PDE4 inhibitors. PDE4A11, PDE4A10, and PDE4A4 all can interact with betaarrestin. PDE4A11 is a novel, widely expressed long isoform that is activated by PKA phosphorylation and shows a distinct intracellular localization, indicating that it may contribute to compartmentalized cAMP signaling in cells in which it is expressed.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2005

Metalloproteomics: high-throughput structural and functional annotation of proteins in structural genomics.

A high-throughput method for measuring transition metal content based on quantitation of X-ray fluorescence signals was used to analyze 654 proteins selected as targets by the New York Structural GenomiX Research Consortium. Over 10% showed the presence of transition metal atoms in stoichiometric amounts; these totals as well as the abundance distribution are similar to those of the Protein Data Bank. Bioinformatics analysis of the identified metalloproteins in most cases supported the metalloprotein annotation; identification of the conserved metal binding motif was also shown to be useful in verifying structural models of the proteins. Metalloproteomics provides a rapid structural and functional annotation for these sequences and is shown to be approximately 95% accurate in predicting the presence or absence of stoichiometric metal content. The project's goal is to assay at least 1 member from each Pfam family; approximately 500 Pfam families have been characterized with respect to transition metal content so far.

Binding Sites↗
PubMed2005

Monocarboxylate transporter MCT1 is a target for immunosuppression.

Current immunosuppressive therapies act on T lymphocytes by modulation of cytokine production, modulation of signaling pathways or by inhibition of the enzymes of nucleotide biosynthesis. We have identified a previously unknown series of immunomodulatory compounds that potently inhibit human and rat T lymphocyte proliferation in vitro and in vivo in immune-mediated animal models of disease, acting by a novel mechanism. Here we identify the target of these compounds, the monocarboxylate transporter MCT1 (SLC16A1), using a strategy of photoaffinity labeling and proteomic characterization. We show that inhibition of MCT1 during T lymphocyte activation results in selective and profound inhibition of the extremely rapid phase of T cell division essential for an effective immune response. MCT1 activity, however, is not required for many stages of lymphocyte activation, such as cytokine production, or for most normal physiological functions. By pursuing a chemistry-led target identification strategy, we have discovered that MCT1 is a previously unknown target for immunosuppressive therapy and have uncovered an unsuspected role for MCT1 in immune biology.

Animals↗
PubMed2004

Expression, intracellular distribution and basis for lack of catalytic activity of the PDE4A7 isoform encoded by the human PDE4A cAMP-specific phosphodiesterase gene.

PDE4A7 is an isoform encoded by the human PDE4A cAMP-specific phosphodiesterase gene that fails to hydrolyse cAMP and whose transcripts are widely expressed. Removal of either the N- or C-terminal unique portions of PDE4A7 did not reconstitute catalytic activity, showing that they did not exert a chronic inhibitory effect. A chimera (Hyb2), formed by swapping the unique N-terminal portion of PDE4A7 with that of the active PDE4A4C form, was not catalytically active. However, one formed (Hyb1) by swapping the unique C-terminal portion of PDE4A7 with that common to all active PDE4 isoforms was catalytically active. Compared with the active PDE4A4B isoform, Hyb1 exhibited a similar K(m) value for cAMP and IC50 value for rolipram inhibition, but was less sensitive to inhibition by Ro-20-1724 and denbufylline, and considerably more sensitive to thermal denaturation. The unique C-terminal region of PDE4A7 was unable to support an active catalytic unit, whereas its unique N-terminal region can. The N-terminal portion of the PDE4 catalytic unit is essential for catalytic activity and can be supplied by either highly conserved sequence found in active PDE4 isoforms from all four PDE4 subfamilies or the unique N-terminal portion of PDE4A7. A discrete portion of the conserved C-terminal region in active PDE4A isoforms underpins their aberrant migration on SDS/PAGE. Unlike active PDE4A isoforms, PDE4A7 is exclusively localized to the P1 particulate fraction in cells. A region located within the C-terminal portion of active PDE4 isoforms prevents such exclusive targeting. Three functional regions in PDE4A isoforms are identified, which influence catalytic activity, subcellular targeting and conformational status.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2004

High-contrast, fast-switching liquid-crystal-on-silicon microdisplay with a frame buffer pixel array.

A 64 x 32 liquid-crystal-on-silicon (LCOS) microdisplay with a frame buffer pixel architecture is described. The advantage of frame buffer pixel circuits is an increase in brightness and image contrast ratio. The increase in brightness is attributed to maximizing the overall image viewing time, allowing an image to be displayed at full contrast while the next image is loaded onto the pixels. The LCOS microdisplay employs a fast-switching optically compensated birefringence mode that operates at a 720-Hz frame frequency with a potentially high contrast ratio.

Journal Article↗
PubMed2004

Non-conventional therapies in childhood cancer: guidelines for distinguishing non-harmful from harmful therapies: a report of the SIOP Working Committee on Psychosocial Issues in Pediatric Oncology.

This is the 11th official document of the SIOP Working Committee on Psychosocial Issues in Pediatric Oncology, instituted in 1991. There is a tendency for some physicians to make blanket statements against the use of non-proven, non-conventional therapies, even when these therapies are not harmful. There is an equal and opposite tendency on the part of many parents to do all that they possibly can for their children, including using any non-conventional therapy they feel might do some good. The health care team must open a healthy dialogue with parents that will lead to a clear distinction between those complementary therapies that are harmful and those that are not, indeed, might even be helpful psychologically if not therapeutically.

Child↗
PubMed2002

A positive-strand RNA virus replication complex parallels form and function of retrovirus capsids.

We show that brome mosaic virus (BMV) RNA replication protein 1a, 2a polymerase, and a cis-acting replication signal recapitulate the functions of Gag, Pol, and RNA packaging signals in conventional retrovirus and foamy virus cores. Prior to RNA replication, 1a forms spherules budding into the endoplasmic reticulum membrane, sequestering viral positive-strand RNA templates in a nuclease-resistant, detergent-susceptible state. When expressed, 2a polymerase colocalizes in these spherules, which become the sites of viral RNA synthesis and retain negative-strand templates for positive-strand RNA synthesis. These results explain many features of replication by numerous positive strand RNA viruses and reveal that these viruses, reverse transcribing viruses, and dsRNA viruses share fundamental similarities in replication and may have common evolutionary origins.

Bromovirus↗
PubMed2002

The long-term effect of specific type II 5alpha-reductase inhibition with finasteride on bone mineral density in men: results of a 4-year placebo controlled trial.

PURPOSE: We determine the effect of long-term suppression of dihydrotestosterone with finasteride, a specific type II 5alpha-reductase inhibitor, on bone mineral density. MATERIALS AND METHODS: As part of a large (3,040 cases) 4-year, double-blind, placebo controlled trial designed to assess the long-term effects of finasteride in men with benign prostatic hyperplasia, 157 men 46 to 76 years old who were randomized to receive either 5 mg. finasteride or placebo underwent dual energy x-ray absorptiometry of the lumbar spine at baseline and at years 2, 3 and 4. RESULTS: Of 117 patients who had a baseline measurement and at least 1 additional measurement during the study baseline mean plus or minus standard deviation bone mineral density values were 1.12 +/- 0.17 gm./cm.2 in the finasteride group (63) and 1.10 +/- 0.17 gm./cm.2 in the placebo group (54). After 4 years bone mineral density was not different between treatment groups (finasteride 1.14 +/- 0.17 gm./cm.2 and placebo 1.13 +/- 0.18 gm./cm.2). Similar results were obtained for the 33 finasteride and 25 placebo treated patients who completed the study with year 4 bone mineral density measurements. CONCLUSIONS: These data demonstrate that long-term inhibition of type II 5alpha-reductase with finasteride does not adversely affect bone mineral density.

5-alpha Reductase Inhibitors↗
PubMedDate not supplied

Effect of systemic hormonal cyclicity on skin.

Fluctuations in estrogen and progesterone during the menstrual cycle can cause changes in body systems other than the reproductive system. We conducted several studies to determine a possible correlation between phases of the menstrual cycle and specific skin properties. Healthy Caucasian women (ages 21-48), who had a typical 26-29 day menstrual cycle, participated in the studies. Measurements of skin barrier strength, dryness, response to lactic acid stinging, skin surface lipids, and microflora were obtained every week for two to three months. Ultraviolet B susceptibility in terms of minimal erythemal dose was also studied. The skin barrier was the weakest between days 22 and 26 of the cycle. Elevated neuronal response (lactic acid sting) was not observed to vary much with the cycle. Skin was driest between day 1 and day 6, while skin surface lipid secretion appeared to be highest on days 16-20 of the hormonal cycle. The highest microbial count was around days 16-22, and there was a high UV-B susceptibility between days 20 and 28 of the menstrual cycle.

Adult↗