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Soulage C Perrin D Cottet-Emard JM Pequignot J Dalmaz Y Pequignot JM 《Neurochemistry international》2004,45(7):979-986
We investigated in rat the effects of ozone exposure (0.7 ppm) for 5 h on the catecholamine biosynthesis and turnover in sympathetic efferents and various brain areas. For this purpose, the activity of tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, was assessed in superior cervical ganglia and in two major noradrenergic cell groups, A2 and A6 (locus coeruleus). Tyrosine hydroxylase activity was estimated in vivo by measuring the accumulation of l-dihydroxyphenylalanine after pharmacological blockade of L-aromatic acid decarboxylases by NSD-1015 (100 mg/kg i.p.). The catecholamine turnover rate was measured after inhibition of tyrosine hydroxylase by alpha-methyl-para-tyrosine (AMPT, 250 mg/kg, i.p., 2.5 h) in peripheral sympathetic target organ (heart and lungs) as well as in some brain catecholamine terminal areas (cerebral cortex, hypothalamus and striatum). Ozone caused differential effects according to the structure. Catecholamine biosynthesis was stimulated in superior cervical ganglia (+44%, P < 0.05) and caudal A2 subset (+126%, P < 0.01), whereas catecholamine turnover was increased in heart (+183%, P < 0.01) and cortex (+22%, P < 0.05). On the other hand, catecholamine turnover was inhibited in lungs (-53%, P < 0.05) and striatum (-24%, P < 0.05). A brief exposure to ozone, at a concentration chosen to mimic pollution level encountered in urban areas, can modulate catecholamine biosynthesis and utilization rate in the sympathetic and central neurones. 相似文献
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Abdelmelek H Ben Hamouda Ael-M Ben Salem M Pequignot JM Sakly M 《The Chinese journal of physiology》2003,46(3):137-141
The aim of the present study was to analyse electric resistivity at different ambient temperatures between 300 to 20K in the frog sciatic nerve and salmon sperm DNA. When the electrical contacts were leaned just into the sciatic nerve, an increase of the sciatic nerve resistivity was observed for 240 K < T < 300 K and a rise of electrical conductivity was apparent below 240 K. This dependence is generally associated with a semiconductor behaviour. Once the sciatic nerve temperature was driven below 250K, the resistivity abruptly decreased and then at temperatures lower than 234 K, it remained constant and close to one tenth of its ambient temperature value. By contrast, when the electrical contacts were leaned into Salmon sperm DNA, the resistivity remained constant between 300K to 20K, showing a high electrical stability at low temperature. Thus, we report the existence of a new form of electric conductivity in the sciatic nerve at low ambient temperature, which in turn has many electric similarities with inorganic or organic superconductors, whereas temperature failed to alter DNA electrical properties until 20K. 相似文献
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Chater S Abdelmelek H Pequignot JM Sakly M Rhouma KB 《Electromagnetic biology and medicine》2006,25(3):135-144
This study investigated the effects of a static magnetic field (SMF) on hematopoiesis and biochemical parameters in female rats. Pregnant rats were exposed to SMF (128 mT-1 hour/day from day 6 to day 19 of pregnancy). At 25 degrees C, the exposure of rats 1 hour/day for 13 consecutive days to SMF induced an increase in hematocrit (Ht) level (+6%, p < 0.05), hemoglobin (Hb) concentration (+12%, p < 0.05) and LDH levels (67%, p < 0.05 ), suggesting an hypoxia-like state. Moreover, exposure to SMF increased blood glucose and decreased insulin release, leading to a diabetic-like state in pregnant rats. 相似文献
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Vincent E. Sollars Ed Pequignot Jay L. Rothstein Arthur M. Buchberg 《Mammalian genome》2006,17(8):808-821
The myeloid progenitor cell compartment (MPC) exhibits pronounced expansion in human myeloid leukemias. It is becoming more
apparent that progression of myelodysplastic syndromes and myeloproliferative diseases to acute myelogenous leukemia is the
result of defects in progenitor cell maturation. The MPC of bone marrow was analyzed in mice using a cell culture assay for
measuring the relative frequency of proliferative myeloid progenitors. Response to the cytokines SCF, IL-3, and GM-CSF was
determined by this assay for the leukemic mouse strain BXH-2 and ten other inbred mouse strains. Significant differences were
found to exist among ten inbred mouse strains in the nature of their MPC in bone marrow, indicating the presence of genetic
polymorphisms responsible for the divergence. The SWR/J and FVB/J strains show consistently low frequencies of myeloid progenitors,
while the DBA/2J and SJL/J inbred strains show consistently high frequencies of myeloid progenitors within the bone marrow
compartment. In addition, in silico linkage disequilibrium analysis was conducted to identify possible chromosomal regions responsible for the phenotypic variation.
Given the importance of this cell compartment in leukemia progression and the soon to be released genomic sequence of 15 mouse
strains, these differences may provide a valuable tool for research into leukemia. 相似文献
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B. Melin C. Jimenez G. Savourey J. Bittel J. M. Cottet-Emard J. M. Pequignot A. M. Allevard C. Gharib 《European journal of applied physiology and occupational physiology》1997,76(4):320-327
The effects of hydromineral hormones and catecholamines on renal concentrating ability at different hydration states were
examined in five male volunteers while they performed three trials. Each of these trials comprised a 60-min exercise bout
on a treadmill (at 50% of maximal oxygen uptake) in a warm environment (dry bulb temperature, 35°C; relative humidity, 20–30%).
In one session, subjects were euhydrated before exercise (C). In the two other sessions, after thermal dehydration (loss of
3% body mass) which markedly reduced plasma volume (PV) and increased plasma osmolality (osmpl), the subjects exercised either not rehydrated (Dh) or rehydrated (Rh) by drinking 600 ml of mineral water before and 40 min
after the onset of exercise. During exercise in the Dh compared to C state, plasma renin, aldosterone, arginine vasopressin
(AVP), noradrenaline and adrenaline concentrations were increased (P < 0.05). A reduction in creatinine clearance and urine flow was also observed (P < 0.05) together with a decrease in urine osmolality, osmolar clearance and sodium excretion, while free water clearance
increased (P < 0.05). However, compared to Dh, Rh partially restored PV and osmpl and induced a marked reduction in the time courses of both the plasma AVP and catecholamine responses (P < 0.05). Values for renal water and electrolyte excretion were intermediate between those of Dh and C. Plasma atrial natriuretic
peptide presented similar changes whatever the hydration state. These results demonstrate that during moderate exercise in
the heat, renal concentrating ability is paradoxically reduced by prior dehydration in spite of high plasma AVP levels, and
might be the result of marked activation of the sympatho-adrenal system. Rehydration, by reducing this activation, could partially
restore the renal concentrating ability despite the lowered plasma AVP.
Accepted: 23 April 1997 相似文献
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Bedu E Desplanches D Pequignot J Bordier B Desvergne B 《Biochemical and biophysical research communications》2007,357(4):877-881
The peroxisome proliferator-activated receptors (PPARs) are involved in the regulation of most of the pathways linked to lipid metabolism. PPARalpha and PPARbeta isotypes are known to regulate muscle fatty acid oxidation and a reciprocal compensation of their function has been proposed. Herein, we investigated muscle contractile and metabolic phenotypes in PPARalpha-/-, PPARbeta-/-, and double PPARalpha-/- beta-/- mice. Heart and soleus muscle analyses show that the deletion of PPARalpha induces a decrease of the HAD activity (beta-oxidation) while soleus contractile phenotype remains unchanged. A PPARbeta deletion alone has no effect. However, these mild phenotypes are not due to a reciprocal compensation of PPARbeta and PPARalpha functions since double gene deletion PPARalpha-PPARbeta mostly reproduces the null PPARalpha-mediated reduced beta-oxidation, in addition to a shift from fast to slow fibers. In conclusion, PPARbeta is not required for maintaining skeletal muscle metabolic activity and does not compensate the lack of PPARalpha in PPARalpha null mice. 相似文献