43 research outputs found
Infection with Toxoplasma gondii does not Alter TNFα and IL-6 Secretion by A human Astrocytoma Cell Line
The secretion of tumour necrosis factor-α (TNFα),
interleukin-1α (IL-α) and interleukin-6 (IL-6) by a
human astrocytoma cell fine was studied 1 h, 3 h, 6 h and 24 h after
infection with tachyzoites from three Toxoplasma gondii
strains (virulent, RH; cystogentc, 76K and Prugniaud strains). The
astrocytoma cell fine constitutively secreted TNFα and IL-6,
but no IL-1α. A positive control was obtained by stimulation
with phorbol esters inducing a significant increase (p < 0.05) in TNFα and IL- 6 secretion but not in IL-1α, while
lipopolysaccharide (alone and after priming), interferon gamma,
ionophore A 23187 and sera positive to T. gondii did
not induce any increase in cytokine levels. None of the tachyzoites,
whatever their virulence, induced a significant increase in cytokine
production at any time in the study. Tachyzoites did not inhibit the
secretion induced by phorbol esters
Independent validation of the Enhanced Liver Fibrosis (ELF) score in the ANRS HC EP 23 Fibrostar cohort of patients with chronic hepatitis C
BACKGROUND: The Enhanced Liver Fibrosis (ELF) score combining serum hyaluronan, N-terminal peptide of type III procollagen and tissue inhibitor of metalloproteinase-1, was reported as relevant in predicting liver fibrosis in chronic liver disease and proposed as an alternative to liver biopsy. METHODS: We evaluated the ELF score in a cohort of chronic hepatitis C (CHC) patients included in a multicenter prospective study (ANRS HC EP 23 Fibrostar) using commercial reagents, different from those developed by the manufacturer of the Siemens ELF test. RESULTS: In 512 CHC, the ELF score, using ROC curves, showed good predictive performances for severe fibrosis [AUROC=0.82; 95% confidence interval (CI) 0.78-0.86]and for cirrhosis (AUROC=0.85; 95% CI 0.81-0.90), but slightly lower for significant fibrosis (AUROC=0.78; 95% CI 0.74-0.82). The Obuchowski measure (0.81) showed that the ELF score globally performed as a marker of liver fibrosis. The ELF score predicted significant fibrosis (cut-off=9.0) with a sensitivity of 0.86, a specificity of 0.62, a positive predictive value (PPV) of 0.80 and a negative predictive value (NPV) of 0.70. For extensive fibrosis (cut-off=9.33), sensitivity was 0.90, specificity was 0.63, PPV was 0.73 and NPV was 0.85. For cirrhosis (cut-off=9.35), sensitivity was 0.83, specificity was 0.75, PPV was 0.44 and NPV was 0.95. CONCLUSIONS: This study confirms the ELF score performance as an index to predict liver fibrosis or cirrhosis in CHC. The ELF test, using validated reagents, could be added to the health authorities approved non-invasive tests in assessing fibrosis as surrogate to liver biopsy
Period-adding bifurcations and chaos in a periodically stimulated excitable neural relaxation oscillator
This is a pre-print. The definitive version: COOMBES, S. and OSBALDESTIN, A.H., 2000. Period-adding bifurcations and chaos in a periodically stimulated excitable neural relaxation oscillator. Physical Review E, 62(3), pp.4057-4066 Part B.The response of an excitable neuron to trains of electrical spikes is relevant to the understanding
of the neural code. In this paper we study a neurobiologically motivated relaxation oscillator, with
appropriately identified fast and slow coordinates, that admits an explicit mathematical analysis.
An application of geometric singular perturbation theory shows the existence of an attracting
invariant manifold which is used to construct the Fenichel normal form for the system. This
facilitates the calculation of the response of the system to pulsatile stimulation and allows the
construction of a so-called extended isochronal map. The isochronal map is shown to have a single
discontinuity and be of a type that can admit three types of response: mode-locked, quasi-periodic
and chaotic. The bifurcation structure of the system is seen to be extremely rich and supports
period-adding bifurcations separated by windows of both chaos and periodicity. A bifurcation
analysis of the isochronal map is presented in conjunction with a description of the various routes
to chaos in this system
The emergence of profit and interest in the monetary circuit
Efficient progress of the monetary theory of production (MTP) is hampered
by an unsatisfactory account of how profit and interest emerge in the monetary
circuit. As matter of fact, this question puzzled already the classics. It seems
evident that it cannot be answered by applying the usual tools. The present
paper’s purpose is to overcome the deadlock. This is done by setting the
circulation approach on general structural axiomatic foundations