Biomedical subjects
G Marechal
Publications and source records attributed to G Marechal.
Superinduction of c-fos gene expression by estrogen in cultured guinea-pig endometrial cells requires priming by a cycloheximide-dependent mechanism.
The c-fos gene expression is rapidly induced by various mitogenic agents and protein synthesis inhibitors in many cell types. Estradiol-17 beta can induce c-fos gene expression in breast cancer cell lines and in the uterus in vivo, but not in cultured guinea-pig endometrial cells. Using this model, we investigated whether a protein synthesis inhibitor, cycloheximide, could induce the c-fos gene and permit a superinduction by estrogens. In the presence of cycloheximide (10 micrograms/ml), protein synthesis was inhibited at 95% within the first hour. From 190 min after the addition of estradiol-17 beta or diethylstilbestrol (10(-8) M) and cycloheximide (10 micrograms/ml), there was a significant increase (ranging from 3- to 5-fold) of the c-fos messenger RNA level (2.2 kilobase in size), compared with the level in cells treated with cycloheximide alone. Nonestrogenic steroid hormones and estradiol-17 alpha were unable to induce c-fos gene expression in the presence of cycloheximide. The effect of estradiol-17 beta observed in the presence of cycloheximide was completely abolished by 4-hydroxy-tamoxifen or by Ly 156758 or by ICI 164384 (10(-6) M). The c-fos mRNAs were rather stable in cells treated with cycloheximide for 2 h (half-life = 51 +/- 6 min) and there was no further increase in the c-fos messenger RNA stability after the addition of cycloheximide plus estradiol-17 beta (half-life = 40 +/- 3 min). The overall results suggest a response at the transcriptional level. In conclusion, cycloheximide transmits activating signals to the c-fos gene which act as priming elements to allow the estrogen action in cultured guinea-pig endometrial cells.
Effects of 17 beta-estradiol and growth factors on c-fos gene expression in endometrial epithelial cells in primary culture.
Primary culture of guinea-pig endometrial cells was made quiescent by serum depletion. When added to quiescent cells, 17 beta-estradiol (E2) alone affected neither c-fos and c-myc gene expression, nor DNA synthesis and cell proliferation. Insulin or epidermal growth factor (EGF) only induced DNA synthesis. An association of both growth factors allowed significant cell proliferation without inducing c-fos or c-myc expression. A response including c-fos induction (maximal expression at 75 min), but not c-myc expression, DNA synthesis and a marked cell proliferation was only obtained when 17 beta-estradiol was associated with insulin plus EGF. In this case, cycloheximide raised the c-fos gene expression. These data suggest that in endometrial epithelial cells, E2 is mitogenic only when it acts in association with EGF plus insulin and the c-fos gene expression may not be correlated with cell proliferation.
Uterine epithelial cells in primary culture: a model system to study cell proliferation.
Guinea-pig uterine glandular epithelial cells were grown in primary culture. During the 4-day initial culture period, a 6.7 fold increase in DNA synthesis and a doubling time of approximately 30 hours were observed. Then the cells were submitted to serum depletion (60 hours) and the quiescent cells were stimulated with 15% fetal calf serum (FCS). The control cells were submitted to 1% heated and dextran-coated charcoal stripped FCS. In stimulated cells, the DNA synthesis increased and peaked between the 12th and 24th hour. In these cells, c-fos mRNAs increased rapidly, within 30 min., peaked at 75 min. (ratio to the control = 2.5), and returned to basal level within 90 min. These results prove that uterine epithelial cells in primary culture are able to respond to unspecific mitogen by both rapid expression of c-fos gene and DNA synthesis, suggesting that this cell culture system will be useful in studying the growth regulation in endometrium.
Force-velocity relation and myosin isozymes of rat muscles.
The proportions of three myosin heavy chains in rat soleus and EDL are used to compute a triple linear regression which predicts correctly the maximal mechanical power and approximately the parameters b and a/Fo of the Hill's equations.
Subunit composition of native myosin isoenzymes of some striated mammalian muscles.
Six "native" isomyosins of characteristic electrophoretic mobility are present in various proportions according to the muscle type (fast, slow or mixed). SM2 and SM1 contain MHC1; IM contains MHC2A; FM1, FM2 and FM3 contain MHC2A and MHC2B. SM2, SM1 and IM contain MLC1s; SM1, IM, FM2 and FM3 contain MLC1f; FM2 and FM1 contain MLC3f. The six isomyosins appear to separate on the base of their myosin light chain content.
Implantation of autologous cells in minced and devitalized rat skeletal muscles.
Triceps surae of 3 week-old female Wistar rats were minced and orthotopically autografted. Thirty days later, the regenerates developed a force of 314 +/- 58 mN during an isometric maximal tetanus and the maximal area of the muscle tissue was 3.2 +/- 0.5 mm2 (n = 9) in a cross-section. At 60 days, their mean maximal isometric force was increased (1159 +/- 367 mN) as also were their maximal muscle cross-section area (6.8 +/- 0.7 mm2;n = 6). If the minces were devitalized by a freeze and thaw procedure, the regenerates neither contracted under electrical stimulation nor contained any muscle fibre. If devitalized minces were seeded with myogenic cells isolated from the contralateral triceps surae, orthotopically autografted and allowed to regenerate for 30 days, the regeneration was weak: 46 +/- 14 mN of force, 1.2 +/- 0.3 mm2 of muscle area in minces devitalized by cold (n = 7) and 23 +/- 8 mN of force, 0.2 +/- 0.1 mm2 of muscle area in minces devitalized by cold supplemented by heat (n = 8). If viable minces were seeded with myogenic cells, there was no improvement in the extent of regeneration: 275 +/- 83 mN of force, 2.0 +/- 0.6 mm2 of muscle area at 30 days (n = 7) and 738 +/- 191 mN of force, 5.6 +/- 0.9 mm2 of muscle area at 60 days (n = 5). Consequently, although it is possible to induce regeneration by grafting myogenic cells into a devitalized mince, this procedure has no effect when applied to a viable mince.
Regeneration of mammalian striated muscle.
Six main factors limit the regeneration of mammalian striated muscles: the myogenic cells, the basal membranes, the vascular supply, the innervation, the mechanical forces and the functional utilization. Their rôle is shortly discussed.
The mobility of smooth muscle isomyosins.
The two isomyosins of smooth muscles, G1 and G2, were extracted from various visceral organs of chicken, mice, rats, rabbits and dogs. They were separated by electrophoresis in pyrophosphate polyacrylamide gels. Their mobility was the same for all samples, being higher than the mobility of several isomyosins of striated muscles obtained from leg, eye, middle ear, heart ventricle or newborn rat leg.
[Behçet's syndrome or Crohn's disease?].
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Chemical energy usage during isometric twitches of frog sartorius muscle intoxicated with an isomer of creatine, beta-guanidinopropionate.
Frogs were injected for several weeks with beta-guanidinopropionate, an isomer of creatine. Their sartorius muscles were isolated, poisoned with iodoacetate and stimulated isometrically with 75 shocks/min in nitrogen until rigor. In comparison with sartorius muscles of untreated frogs, they contained more free creatine and less phosphocreatine, but the same content in total creatine and ATP. They also contained beta-guanidinopropionate both free and phosphorylated. However, muscles in rigor contained the same concentration of the phosphorylated form as resting muscles, i.e., phospho-beta-guanidinopropionate was not split during contraction. The number of twitches performed before rigor was decreased. There was no change in the chemical energy usage (sum of phosphocreatine breakdown and twice ATP breakdown) per twitch.
[Congenital malaria in mice and adenosine triphosphate (ATP)].
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Bioluminescence of bathypelagic fish from the Strait of Messina.
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The striated muscles in a slow-mover, Perodicticus potto (Prosimii, Lorisidae, Lorisinae).
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Effects of dobutamine and sulmazol (AR-L115 BS) on myocardial metabolism and coronary, femoral, and renal blood flows: a comparative study in normal dogs and in dogs with chronic volume overload.
We compared the hemodynamic and metabolic effects of dobutamine and sulmazol (AR-L115 BS) in normal dogs and in dogs with chronic volume overload. In both cases, the doses of dobutamine and sulmazol were adapted to produce comparable increases in two indices of inotropic state, peak (+) left ventricular dP/dt and dP/dt normalized by a developed pressure of 40 mm Hg. In normal dogs, both drugs had similar effects on myocardial oxygen consumption, myocardial high-energy phosphate stores, and renal or femoral blood flows; in addition, mean aortic pressure (129 +/- 8 to 114 +/- 10 mm Hg; p less than 0.002), the renal vascular resistance (--18%; p less than 0.005), and the coronary vascular resistance (--30%; p less than 0.05) were all decreased significantly during sulmazol administration. In chronic volume overload, the changes in renal and femoral blood flows and in myocardial high-energy phosphate stores induced by dobutamine or sulmazol were again similar. However, sulmazol still decreased mean aortic pressure (--20 +/- 5 mm Hg; p less than 0.002) and markedly reduced the left ventricular filling pressure (--40%; p less than 0.006), while these parameters were not significantly modified after dobutamine. Myocardial oxygen consumption was unchanged after sulmazol but increased slightly with dobutamine. Finally, the frequency of ventricular premature beat was unchanged by sulmazol but increased after dobutamine. In conclusion, sulmazol is likely to be superior to dobutamine to stimulate a failing left ventricle when clinical status is characterized by markedly elevated filling pressures. It might also be superior when the coronary vascular reserve is reduced or in the presence of ventricular arrhythmias.