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Solanki A, Korpics M, Small C, Harkenrider M, Mitin T. Variability of Radiation Oncologists’ Chemoradiation Therapy Patterns of Care and the Impact of Multidisciplinary Clinics in Muscle-Invasive Bladder Cancer. Int J Radiat Oncol Biol Phys 2016. [DOI: 10.1016/j.ijrobp.2016.06.1302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Lascelles BG, Taylor PR, Miller MGR, Dias MP, Oppel S, Torres L, Hedd A, Le Corre M, Phillips RA, Shaffer SA, Weimerskirch H, Small C. Applying global criteria to tracking data to define important areas for marine conservation. DIVERS DISTRIB 2016. [DOI: 10.1111/ddi.12411] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Stang K, Alite F, Small C, Sethi A, Emami B, Harkenrider M. Novel Predictors of Esophageal Toxicity With Stereotactic Body Radiation Therapy (SBRT) for Central Lung Tumors. Int J Radiat Oncol Biol Phys 2015. [DOI: 10.1016/j.ijrobp.2015.07.1649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Alite F, Stang K, Shaikh M, Small C, Sethi A, Nagda S, Emami B, Harkenrider M. Local Control Dependence on Consecutive Versus Nonconsecutive Fractionation in Lung SBRT: A Propensity Score Matched Analysis. Int J Radiat Oncol Biol Phys 2015. [DOI: 10.1016/j.ijrobp.2015.07.1676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fisher J, D'amario D, Small C, Stopforth M. Effect of colored lenses on muscular performance. J Sports Med Phys Fitness 2015; 55:549-556. [PMID: 24921621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
AIM The effect of color on physiological parameters appears well documented. However, methodological weaknesses and limitations to practical application suggest it to be substantially under researched with regard to physical performance. The aim of this study was to consider the effects of red, blue and clear (control) colored lens glasses on a muscular endurance task. METHODS Fifteen healthy males (21±1.34 years) were instructed to perform repetitions to failure using their predetermined 25 repetition maximum (RM) on a seated leg press. Participants completed three randomised trials exposed to blue, red and clear lenses. RESULTS A repeated measure ANOVA identified a significant difference in the amount of repetitions performed between the three conditions. A pairwise comparison revealed significantly greater repetitions for the blue lens condition compared to clear lenses (P=0.008). From the data an effect size (ES) of 0.76 was calculated for blue lensed glasses. The red lens condition showed no significant variation from clear lenses in repetitions performed. CONCLUSION The findings of this research suggest that exposure to the color blue improves performance of a muscular endurance based task. Such a simple and inexpensive performance enhancement warrants further investigation to explore different exercise modalities as well as effects of different colored lenses, and the mechanisms as to how color affects performance.
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Aldington D, Small C, Edwards D, Ralph J, Woods P, Jagdish S, Moore RA. A survey of post-amputation pains in serving military personnel. J ROY ARMY MED CORPS 2013; 160:38-41. [DOI: 10.1136/jramc-2013-000069] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kerhet A, Small C, Quon H, Riauka T, Schrader L, Greiner R, Yee D, McEwan A, Roa W. Application of machine learning methodology for PET-based definition of lung cancer. ACTA ACUST UNITED AC 2011; 17:41-7. [PMID: 20179802 PMCID: PMC2826776 DOI: 10.3747/co.v17i1.394] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We applied a learning methodology framework to assist in the threshold-based segmentation of non-small-cell lung cancer (nsclc) tumours in positron-emission tomography–computed tomography (pet–ct) imaging for use in radiotherapy planning. Gated and standard free-breathing studies of two patients were independently analysed (four studies in total). Each study had a pet–ct and a treatment-planning ct image. The reference gross tumour volume (gtv) was identified by two experienced radiation oncologists who also determined reference standardized uptake value (suv) thresholds that most closely approximated the gtv contour on each slice. A set of uptake distribution-related attributes was calculated for each pet slice. A machine learning algorithm was trained on a subset of the pet slices to cope with slice-to-slice variation in the optimal suv threshold: that is, to predict the most appropriate suv threshold from the calculated attributes for each slice. The algorithm’s performance was evaluated using the remainder of the pet slices. A high degree of geometric similarity was achieved between the areas outlined by the predicted and the reference suv thresholds (Jaccard index exceeding 0.82). No significant difference was found between the gated and the free-breathing results in the same patient. In this preliminary work, we demonstrated the potential applicability of a machine learning methodology as an auxiliary tool for radiation treatment planning in nsclc.
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Graham J, Morrissey D, Small C, Twycross-Lewis R, Woledge R. Muscle activation patterns in football code athletes with chronic groin pain: a case control study. Br J Sports Med 2011. [DOI: 10.1136/bjsm.2010.081554.9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Kumar P, DeJesus E, Huhn G, Sloan L, Garcia F, Small C, Edelstein H, Felizarta F, Hao R, Ha B, Stancil B, Ross L, Oie K, Pappa K. SUPPORT: 48-week results of fosamprenavir/ritonavir vs efavirenz with abacavir/lamivudine in under-represented, antiretroviral-naïve patients. J Int AIDS Soc 2010. [PMCID: PMC3113075 DOI: 10.1186/1758-2652-13-s4-p7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Kerhet A, Small C, Quon H, Riauka T, Schrader L, Greiner R, Yee D, McEwan A, Roa W. 186 APPLICATION OF MACHINE LEARNING METHODOLOGY FOR PETBASED DEFINITION OF LUNG CANCER. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)72573-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Severin D, Joseph K, Tankel K, Nijjar T, Pedersen J, Small C, Usmani N, Gaetz E, de Gara C, Hennig R, Mihai A. 171 PILOT STUDY OF PRE OPERATIVE INVOLVED FIELD RADIOTHERAPY FOR RECTAL CANCER. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)72558-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Severin D, Joseph K, Usmani N, Tankel K, Nijjar T, Small C, Hennig R, Gaetz E, Field C, Mihai A. 6038 Pilot study of preoperative involved field radiotherapy in rectal cancer. EJC Suppl 2009. [DOI: 10.1016/s1359-6349(09)71133-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Small C, McEwan A, Kerhet A, Riauka T, Postema E, Roa W. 157 THE ROLE OF 18F-FAZA COMBINED WITH 18F-FDG IN ASSESSING RESPONSE IN PATIENTS WITH INOPERABLE NON-SMALL CELL LUNG CANCER UNDERGOING RADIOTHERAPY OR CHEMORADIOTHERAPY. Radiother Oncol 2009. [DOI: 10.1016/s0167-8140(12)72544-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Small C, Chowdhury R, Mackenzie M, Fallone G, Pearcey R, Pervez N. Is the Dose We See the Dose We Get? Analysis of DVHs using Daily Tomotherapy Based MVCT Contouring of Prostate, Bladder and Rectum, to Assess the Actual Dose Received during Treatment as Opposed to Planned DVH. Int J Radiat Oncol Biol Phys 2008. [DOI: 10.1016/j.ijrobp.2008.06.1139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Chowdhury R, Small C, Mackenzie M, Pearcey R, Pervez N. Changes in 3T-MRI Prostate Volumes in High Risk Prostate Cancer Treated with Hypofractionated Radiation using Dynamic IMRT and Varying Hormonal Therapy Duration. Int J Radiat Oncol Biol Phys 2008. [DOI: 10.1016/j.ijrobp.2008.06.1173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Itman CM, Small C, Griswold M, Nagaraja AK, Matzuk MM, Ernst M, Jans DA, Loveland KA. 232. Developmentally regulated activin A signal transduction by Sertoli cells is required for normal mouse testis development. Reprod Fertil Dev 2008. [DOI: 10.1071/srb08abs232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Activin A, a TGF-β superfamily ligand, is critical for normal mouse testis development and quantitatively normal sperm production. Testicular activin production changes during development, being substantially higher in the immature testis relative to the adult [1, 2]. Activin influences the Sertoli cell, the nurse cell to developing sperm, enhancing proliferation during its immature phase, but not following terminal differentiation [3]. In the Inha−/− mouse, chronic excessive activin production results in Sertoli cell-derived tumours [4] whereas reduced activin bioactivity, in the InhbaBK/BK mouse, delays fertility [5]. Activin signals are transduced by the phosphorylation and nuclear accumulation of the transcription factors SMAD2 and SMAD3. By comparing activin signal transduction in immature v. terminally differentiated Sertoli cells, using quantitative confocal microscopy and western blot analysis of total and phosphorylated SMAD2 and SMAD3, we discovered that mouse Sertoli cells exhibit developmentally regulated activin responses. Activin induces nuclear accumulation of SMAD3, but not SMAD2, in immature cells, although both proteins are phosphorylated. In contrast, terminally differentiated cells exhibit nuclear accumulation of both SMAD2 and SMAD3. We observed that this shift coincides with decreased SMAD3 production at puberty and changes in FSH-induced Smad transcription, which favours Smad3 in immature cells but promotes Smad2 synthesis in terminally differentiated cells. Furthermore, whereas removal of SMAD3 from the Inha−/− mouse rescues the tumour phenotype [6], we demonstrated that insufficient SMAD3 production impairs testis growth. We hypothesised that this developmentally regulated SMAD utilisation drives specific transcriptional outcomes. Using microarray and quantitative PCR, we identified novel activin target genes displaying developmental stage-specific expression patterns coinciding with differential SMAD usage, including Gja1 and Serpina5 which are required for male fertility. These mRNAs are also modulated in vivo, increased 1.5–2 fold in Inha−/− testes and decreased by half in InhbaBK/BK testes, confirming that normal testis development requires carefully regulated activin production and responsiveness.
(1) Buzzard J et al. 2004. Endocrinology 145(7): 3532–3541
(2) Barakat et al. 2008. Reproduction 2008 Epub ahead of print
(3) Boitani C et al. 1995. Endocrinology 136(12): 4538–4544
(4) Matzuk M et al. 1992. Nature 360: 313–319
(5) Brown C et al. 2000. Nature Genetics 25(4): 453–457
(6) Li Q et al. 2007. Molecular Endocrinology 21(10: 2472–2486
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Allen EG, Sullivan AK, Marcus M, Small C, Dominguez C, Epstein MP, Charen K, He W, Taylor KC, Sherman SL. Examination of reproductive aging milestones among women who carry the FMR1 premutation. Hum Reprod 2007; 22:2142-2152. [PMID: 17588953 DOI: 10.1093/humanrep/dem148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023] Open
Abstract
BACKGROUND The fragile X premutation is characterized by a large CGG repeat track (55-199 repeats) in the 5' UTR of the FMR1 gene. This X-linked mutation leads to an increased risk for premature ovarian failure; interestingly, the association of repeat size with risk is non-linear. We hypothesize that the premutation-associated ovarian insufficiency is due to a diminished oocyte pool and examined reproductive aging milestones by repeat size group to determine if the same non-linear association is observed. METHODS We analyzed cross-sectional reproductive history questionnaire data from 948 women with a wide range of repeat sizes. RESULTS We have confirmed the non-linear relationship among premutation carriers for ovarian insufficiency. The mid-range repeat size group (80-100 repeats), not the highest group, had an increased risk for: altered cycle traits (shortened cycle length, irregular cycles and skipped cycles), subfertility and dizygotic twinning. Smoking, a modifiable risk, decreased the reproductive lifespan of women with the premutation by about 1 year, similar to its effect on non-carriers. As expected, premutation carriers were found to be at an increased risk for osteoporosis. CONCLUSIONS Possible molecular mechanisms to explain the non-linear repeat size risk for ovarian insufficiency are discussed.
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Allen EG, Sullivan AK, Marcus M, Small C, Dominguez C, Epstein MP, Charen K, He W, Taylor KC, Sherman SL. Examination of reproductive aging milestones among women who carry the FMR1 premutation. Hum Reprod 2007; 22:2142-52. [PMID: 17588953 DOI: 10.1093/humrep/dem148] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The fragile X premutation is characterized by a large CGG repeat track (55-199 repeats) in the 5' UTR of the FMR1 gene. This X-linked mutation leads to an increased risk for premature ovarian failure; interestingly, the association of repeat size with risk is non-linear. We hypothesize that the premutation-associated ovarian insufficiency is due to a diminished oocyte pool and examined reproductive aging milestones by repeat size group to determine if the same non-linear association is observed. METHODS We analyzed cross-sectional reproductive history questionnaire data from 948 women with a wide range of repeat sizes. RESULTS We have confirmed the non-linear relationship among premutation carriers for ovarian insufficiency. The mid-range repeat size group (80-100 repeats), not the highest group, had an increased risk for: altered cycle traits (shortened cycle length, irregular cycles and skipped cycles), subfertility and dizygotic twinning. Smoking, a modifiable risk, decreased the reproductive lifespan of women with the premutation by about 1 year, similar to its effect on non-carriers. As expected, premutation carriers were found to be at an increased risk for osteoporosis. CONCLUSIONS Possible molecular mechanisms to explain the non-linear repeat size risk for ovarian insufficiency are discussed.
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Druce MR, Wren AM, Park AJ, Milton JE, Patterson M, Frost G, Ghatei MA, Small C, Bloom SR. Ghrelin increases food intake in obese as well as lean subjects. Int J Obes (Lond) 2006; 29:1130-6. [PMID: 15917842 DOI: 10.1038/sj.ijo.0803001] [Citation(s) in RCA: 279] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To investigate whether effects on food intake are seen in obese subjects receiving exogenous administration of ghrelin. DESIGN Randomised, double-blind, placebo-controlled study of intravenous ghrelin at doses 1 pmol/kg/min and 5 pmol/kg/min. SUBJECTS In all, 12 healthy lean subjects (mean body mass index (BMI) 20.5+/-0.17 kg/m(2)) and 12 healthy overweight and obese subjects (mean BMI 31.9+/-1.02 kg/m(2)). MEASUREMENTS Food intake, appetite and palatability of food, ghrelin and other obesity-related hormones, growth hormone. RESULTS Low-dose infusion of ghrelin increased ad libitum energy intake at a buffet meal in the obese group only (mean increase 36.6+/-9.4%, P<0.01.) High-dose ghrelin infusion increased energy intake in both groups (mean increase 20.1+/-10.6% in the lean and 70.1+/-15.5% in the obese, P<0.01 in both cases.) Ghrelin infusion increased palatability of food in the obese group. CONCLUSION Ghrelin increases food intake in obese as well as lean subjects. Obese people are sensitive to the appetite-stimulating effects of ghrelin and inhibition of circulating ghrelin may be a useful therapeutic target in the treatment of obesity.
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Carbotte SM, Small C, Donnelly K. The influence of ridge migration on the magmatic segmentation of mid-ocean ridges. Nature 2004; 429:743-6. [PMID: 15201906 DOI: 10.1038/nature02652] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Accepted: 05/13/2004] [Indexed: 11/09/2022]
Abstract
The Earth's mid-ocean ridges display systematic changes in depth and shape, which subdivide the ridges into discrete spreading segments bounded by transform faults and smaller non-transform offsets of the axis. These morphological changes have been attributed to spatial variations in the supply of magma from the mantle, although the origin of the variations is poorly understood. Here we show that magmatic segmentation of ridges with fast and intermediate spreading rates is directly related to the migration velocity of the spreading axis over the mantle. For over 9,500 km of mid-ocean ridge examined, leading ridge segments in the 'hotspot' reference frame coincide with the shallow magmatically robust segments across 86 per cent of all transform faults and 73 per cent of all second-order discontinuities. We attribute this relationship to asymmetric mantle upwelling and melt production due to ridge migration, with focusing of melt towards ridge segments across discontinuities. The model is consistent with variations in crustal structure across discontinuities of the East Pacific Rise, and may explain variations in depth of melting and the distribution of enriched lavas.
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Cohen RM, Small C, Lalonde F, Friz J, Sunderland T. Effect of apolipoprotein E genotype on hippocampal volume loss in aging healthy women. Neurology 2001; 57:2223-8. [PMID: 11756601 DOI: 10.1212/wnl.57.12.2223] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To determine whether the presence of a single epsilon4 allele of the APOE gene is associated with an increased rate of hippocampal volume loss or decline in cognition in healthy women in their sixth decade of life. METHODS Nine APOE-epsilon4 allele-negative (mean age +/- SD, 60.6 +/- 10.2 years) and 16 APOE-epsilon4 allele-positive (mean age +/- SD, 55.1 +/- 6.0 years) healthy women underwent neurocognitive testing and MRI at the time of entry into the study (baseline) and 2 years later. Neurocognitive testing consisted of the Buschke-Fuld Free Recall, verbal fluency tests, the Rey Figure Test, the Wechsler Memory Scale-Revised, and the Wechsler Adult Intelligence Survey-Revised Block Design. Hippocampal volume determinations were based on manual outlining of sagittal slices aided by axial, coronal, and three-dimensional views of high-resolution 124-slice whole-brain scans; the scans were obtained with a 1.5-tesla scanner using a T1-weighted three-dimensional gradient echo sequence with RF spoiling (TR/TE/flip angle, 24 msec/3 msec/30 degrees ). RESULTS The percent change in hippocampal volume per year was greater in the APOE-epsilon4 allele-positive group (mean +/- SD, 2.32 +/- 1.75%) than in the APOE-epsilon4 allele-negative group (mean +/- SD, 0.77 +/- 1.02%; t = 2.41; p < 0.03, two-tailed test). There were no significant differences between the two groups in terms of any of the cognitive measures, and hippocampal volume loss was not correlated with changes in any of the above-mentioned cognitive measures. CONCLUSIONS The presence of a single APOE-epsilon4 allele is associated with an increased rate of hippocampal volume loss in healthy women in their sixth decade of life that is not related to any detectable memory changes.
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Taheri S, Gardiner J, Hafizi S, Murphy K, Dakin C, Seal L, Small C, Ghatei M, Bloom S. Orexin A immunoreactivity and preproorexin mRNA in the brain of Zucker and WKY rats. Neuroreport 2001; 12:459-64. [PMID: 11234746 DOI: 10.1097/00001756-200103050-00008] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The primary role of the orexins was originally believed to be appetite regulation, but is now believed to be the regulation of sleep, arousal and locomotor activity. Orexin A immunoreactivity (orexin A-IR) and prepro-orexin mRNA were measured in the CNS of obese and lean Zucker rats. There were no differences in orexin A-IR or prepro-orexin mRNA levels between obese and lean Zucker rats. The orexins are therefore unlikely to be important in this model of obesity. Levels of orexin A-IR and prepro-orexin mRNA were measured in the CNS of Wistar-Kyoto (WKY) rats, which are hypoactive and have abnormal sleep architecture. Compared to Wistar rats, WKY rats had significantly lower orexin A-IR (with differences of up to 100% in some brain regions) and prepro-orexin mRNA levels. These observations suggest that the sleep and activity phenotype of the WKY strain may be related to orexin deficiency and that this strain may be a useful model of partial orexin deficiency.
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Gillessen S, Mach N, Small C, Mihm M, Dranoff G. Overlapping roles for granulocyte-macrophage colony-stimulating factor and interleukin-3 in eosinophil homeostasis and contact hypersensitivity. Blood 2001; 97:922-8. [PMID: 11159518 DOI: 10.1182/blood.v97.4.922] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Studies of mice rendered deficient in granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3) have established unique roles for these cytokines in pulmonary homeostasis, resistance to infection, and antigen-specific T- and B-cell responses. In addition to these distinctive properties, however, GM-CSF and IL-3 also stimulate the development and activation of hematopoietic cells in many similar ways, raising the possibility that each factor might partially compensate for the other's absence in singly deficient mice. To test whether endogenous GM-CSF and IL-3 mediate redundant functions in vivo, we generated mice lacking both cytokines through sequential gene targeting experiments in embryonic stem (ES) cells. Surprisingly, doubly deficient animals, but not single knockouts, showed increased numbers of circulating eosinophils. Doubly deficient mice, moreover, developed weaker contact hypersensitivity reactions to haptens applied epicutaneously than mice deficient in either factor alone. Together, these findings delineate overlapping roles for GM-CSF and IL-3 in hematopoiesis and immunity. (Blood. 2001;97:922-928)
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Gamer LW, Cox KA, Small C, Rosen V. Gdf11 is a negative regulator of chondrogenesis and myogenesis in the developing chick limb. Dev Biol 2001; 229:407-20. [PMID: 11203700 DOI: 10.1006/dbio.2000.9981] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
GDF11, a new member of the TGF-beta gene superfamily, regulates anterior/posterior patterning in the axial skeleton during mouse embryogenesis. Gdf11 null mice display skeletal abnormalities that appear to represent anterior homeotic transformations of vertebrae consistent with high levels of Gdf11 expression in the primitive streak, presomitic mesoderm, and tail bud. However, despite strong Gdf11 expression in the limb throughout development, this structure does not appear to be affected in the knockout mice. In order to understand this dichotomy of Gdf11 expression versus Gdf11 function, we identified the chicken Gdf11 gene and studied its role during limb formation. In the early limb bud, Gdf11 transcripts are detected in the subectodermal mesoderm at the distal tip, in a region overlapping the progress zone. At these stages, Gdf11 is excluded from the central core mesenchyme where precartilaginous condensations will form. Later in development, Gdf11 continues to be expressed in the distal most mesenchyme and can also be detected more proximally, in between the forming skeletal elements. When beads incubated in GDF11 protein were implanted into the early wing bud, GDF11 caused severe truncations of the limb that affected both the cartilage elements and the muscle. Limb shortening appeared to be the result of an inhibition of chondrogenesis and myogenesis and using an in vitro micromass assay, we confirmed the negative effects of GDF11 on both myogenic and chondrogenic cell differentiation. Analysis of molecular markers of skeletal patterning revealed that GDF11 induced ectopic expression of Hoxd-11 and Hoxd-13, but not of Hoxa-11, Hoxa-13, or the Msx genes. These data suggest that GDF11 may be involved in controlling the late distal expression of the Hoxd genes during limb development and that misregulation of these Hox genes by excess GDF11 may cause some of the observed alterations in skeletal element shape. In addition, GDF11 induced the expression of its own antagonist follistatin, indicating that the activity of GFD11 may be limited by a negative feedback mechanism. The data from our studies in the chick suggest that Gdf11 plays a role in the formation and development of the avian limb skeleton.
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