474 research outputs found
Weak-Hamiltonian dynamical systems
A big-isotropic structure is an isotropic subbundle of ,
endowed with the metric defined by pairing. The structure is said to be
integrable if the Courant bracket ,
. Then, necessarily, one also has
, \cite{V-iso}. A weak-Hamiltonian dynamical system is a vector field
such that . We obtain the
explicit expression of and of the integrability conditions of under
the regularity condition We show that the
port-controlled, Hamiltonian systems (in particular, constrained mechanics)
\cite{{BR},{DS}} may be interpreted as weak-Hamiltonian systems. Finally, we
give reduction theorems for weak-Hamiltonian systems and a corresponding
corollary for constrained mechanical systems.Comment: 19 pages, minor improvement
Singular reduction of implicit Hamiltonian systems
This paper develops the reduction theory of implicit Hamiltonian systems
admitting a symmetry group at a singular value of the momentum map. The results
naturally extend those known for (explicit) Hamiltonian systems described by
Poisson brackets.Comment: 29 pages, no figures, submitte
Expression of tumor necrosis factor by different tumor cell lines results either in tumor suppression or augmented metastasis
Tumor necrosis factor (TNF) produced by tumor cells after gene transfer can effectively suppress the growth of locally growing tumors. We wanted to test the effects of "local" TNF on the growth of a highly metastatic cell line. Therefore, a recombinant retrovirus allowing expression of the TNF gene by the beta-actin promotor has been constructed and used to infect the two tumor cell lines EB and ESB, which grow as solid tumor or metastasize, respectively. Expression of TNF by EB cells resulted in their rapid and dose-dependent rejection. In sharp contrast, mice injected with ESB cells producing similar amounts of TNF showed no signs of tumor suppression, but rather had reduced survival rates that correlated with enhanced hepatic metastases. The accelerated formation of liver metastases by ESB TNF cells could be reversed by an anti-TNF mAb. These results demonstrate the opposite effects TNF may have on tumor growth: suppression of a locally growing tumor and promotion of metastasis formation
Peritonitis following endoscopic polypectomy in a peritoneal dialysis patient: The need for antibiotic prophylaxis
Expression of interleukin 10 in human melanoma.
The expression of interleukin 10 (IL-10) mRNA in human malignant melanoma was investigated by reverse transcriptase polymerase chain reaction analysis. Selective expression of IL-10 mRNA in tissues of primary melanomas and melanoma metastases was found in comparison with normal skin. In addition, strong expression of IL-10 mRNA and of biologically active IL-10 was detected in 3 out of 13 melanoma cell lines. Normal melanocytes consistently expressed low levels of IL-10 mRNA but did not produce detectable IL-10 protein, nor did keratinocytes or fibroblasts. The production of biologically active IL-10 by melanoma cell lines suggests that IL-10 mRNA in melanoma lesions may derive at least in part from the tumour cells themselves. Tumour-infiltrating cells, however, could also be a source of IL-10 in melanoma tissues. The presence of IL-10 in melanoma lesions may contribute to the postulated 'paralysis' of an anti-melanoma immune response
Heritability of reproductive hormones in adult male twins
Background: Proper functioning of the male reproductive axis depends on complex feedback systems between several hormones. In this study, the genetic contribution of various endocrine components of the hypothalamic-pituitary-testicular axis is evaluated and previously observed differences in FSH and inhibin B levels between mono- (MZ) and dizygotic (DZ) twins are re-investigated. Methods: Inhibin B, FSH, LH, sex hormone-binding globulin (SHBG) and testosterone levels were assayed in 128 adult males (20 MZ twin pairs, 7 single MZ twins, 10 DZ twin pairs, 27 single DZ twins and 34 siblings of twins, constituting 10 sibling pairs), aged 15.6-68.7 years. Hormone levels were compared across zygosity groups and heritability estimates were obtained using maximum likelihood variance component analysis. Results: Heritability estimates ranged from 56% (testosterone) to 81% (inhibin B and SHBG). For LH and FSH, the heritability was estimated at 68% and 80% respectively. No mean differences in hormone levels were observed across groups. Conclusions: All measured hormones are highly heritable. A difference in the FSH-inhibin B feedback system between DZ twin males and MZ twin males could not be confirmed. © The Author 2007. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved
Intracellular expression of FLT3 in Purkinje cells: implications for adoptive T-cell therapies
Association Between Modifiable Risk Factors and Pharmaceutical Expenditures Among Adults With Atherosclerotic Cardiovascular Disease in the United States: 2012â2013 Medical Expenditures Panel Survey
Background Atherosclerotic cardiovascular disease (ASCVD) causes most deaths in the United States and accounts for the highest healthcare spending. The association between the modifiable risk factors (MRFs) of ASCVD and pharmaceutical expenditures are largely unknown. Methods and Results We examined the association between MRFs and pharmaceutical expenditures among adults with ASCVD using the 2012 and 2013 Medical Expenditure Panel Survey. A 2âpart model was used while accounting for the survey\u27s complex design to obtain nationally representative results. All costs were adjusted to 2013 US dollars using the gross domestic product deflator. The annual total pharmaceutical expenditure among those with ASCVD was 519 [95% confidence interval (CI), 631 [95% CI, 1078 [95% CI, 2006 [95% CI, 1184 (95% CI, 2823 (95% CI, $2338â3307; P\u3c0.001) more. Conclusions Worsening MRFs were proportionally associated with higher annual pharmaceutical expenditures among patients with established ASCVD regardless of nonâASCVD comorbidity. Inâdepth studies of the roles played by other factors in this association can help reduce medicationârelated expenditures among ASCVD patients
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