Search results for "VITRO"
showing 10 items of 2786 documents
Beyond Biodegradability of Poly(lactic acid): Physical and Chemical Stability in Humid Environments
2017
International audience; Poly(lactic acid) (PLA) is the most traded biodegradable and biobased material. It is largely used as ecofriendly substitute of conventional plastics. Nevertheless, one of the main limiting factors is its water sensitivity. PLA reacts with water and is hydrolyzed during time, which determines its performance. Limited information related to the hydrolysis mechanism driven by water in vapor state is available in scientific literature. Literature is mainly focused on the effects of water in liquid state. This lack of information is of significant importance, since PLA interacts with water in both phases. This work was aimed to give a full depiction of the chemical and p…
Age affects the metabolic rate of insect brain.
1984
Abstract Brains of adult insects can be isolated and studied vitro. In female blowflies the oxygen uptake of the brain is age dependent. A steady increase is followed by a precipitous decrease around the middle of the life span. These changes are accompanied by alterations of mitochondrial structure and deposits of lipofuscin-like material.
Developmental Changes and Daily Rhythm in Melatonin-Induced Inhibition of 3′,5′-Cyclic AMP Accumulation in the Rat Pituitary
1990
Melatonin's transduction mechanisms were investigated using in vitro cultured anterior hemipituitaries. Melatonin inhibited cAMP and 3',5'-cyclic GMP accumulation in neonatal rat anterior pituitary stimulated with LHRH. Maximal inhibitory effect was reached within 25 min and persisted for at least 20 min. Inhibition of cAMP accumulation is specific for melatonin because its analogs N-acetylserotonin and 5-methoxytryptamine are 1000 times less potent. Melatonin effect is age- and time-dependent. Marked inhibition was observed in 5-, 10-, and 14-day-old rats but not in 29-day-old ones. Melatonin was significantly more potent when applied at the end of the light period as compared with the fir…
Pharmacological heterogeneity of γ-aminobutyric acid receptors during development suggests distinct classes of rat cerebellar granule cells in situ
2001
The gamma-aminobutyric acid receptor (GABA(A)R) represents a ligand-gated Cl(-)-channel assembling as heteropentamere from 19 known subunits. Cerebellar granule cells contain a unique subset, namely the alpha1-, alpha6-, beta2-, gamma2- and delta-subunits. We studied their GABAergic pharmacology in situ using whole-cell patch-clamp recordings in brain slices and a modified Y-tube application system. The distribution of the EC50s for GABA in young (P8-P14) and medium aged animals (P15-P28) could be fitted with the sum of two Gaussian distributions with means of 60 and 185 microM and 27 and 214 microM, respectively. In older animals (P29-P48) the observed homogeneous range of sensitivities fi…
Glutamate Activates Phospholipase D in Hippocampal Slices of Newborn and Adult Rats
1993
Phospholipase D (PLD) is activated by many neurotransmitters in a novel signal transduction pathway. In the present work, PLD activity was studied comparatively in hippocampal slices of newborn and adult rats. Basal PLD activity in adult rats was almost three times higher than in newborn rats. In newborn rats, L-glutamate and 1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) time- and concentration-dependently enhanced the formation of [3H]phosphatidylpropanol ([3H]PP) and of [3H]phosphatidic acid in the presence of 2% propanol. N-Methyl-D-aspartate and kainate (both 1 mM) caused small, but significant increases (approximately 50%), whereas alpha-amino-3-hydroxy-5-methylisoxazole…
Phosphatidylserine counteracts physiological and pharmacological suppression of humoral immune response
1990
Phosphatidylserine (PS) is a necessary cofactor for protein kinase C (PKC) activation, and changes in the synthesis of PS have been shown to participate in the mechanism(s) involved in the transmembrane signaling of interleukin 1 (IL-1). In view of the age-associated defects in T-cell functions, in the present study we have addressed the question of whether an in vivo treatment with PS might interfere with such processes. Furthermore, the effect of an in vitro treatment with PS in human peripheral blood monocytes (PBMC) or splenocytes activated with a lectin mitogen, on the expression of IL-2 receptor, was assessed. While the process of ageing was accompanied by a marked decline of humoral …
Relaxation of human isolated mesenteric arteries by vasopressin and desmopressin.
1994
1. The effects of vasopressin and deamino-8-D-arginine vasopressin (DDAVP, desmopressin) were studied in artery rings (0.8-1 mm in external diameter) obtained from portions of human omentum during the course of abdominal operations (27 patients). 2. In arterial rings under resting tension, vasopressin produced concentration-dependent, endothelium-independent contractions with an EC50 of 0.59 +/- 0.12 nM. The V1 antagonist d(CH2)5Tyr(Me)AVP (1 microM) and the mixed V1-V2 antagonist desGly-d(CH2)5D-Tyr(Et)ValAVP (0.01 microM) displaced the control curve to vasopressin to the right in a parallel manner without differences in the maximal responses. In the presence of indomethacin (1 microM) the…
GnRH agonist versus recombinant HCG in an oocyte donation programme: a randomized, prospective, controlled, assessor-blind study.
2009
The use of gonadotrophin-releasing hormone (GnRH) agonists for triggering ovulation remains controversial. The primary objective of this study was to evaluate the incidence of ovarian hyperstimulation syndrome (OHSS) following GnRH agonist versus recombinant human chorionic gonadotrophin (HCG) as methods for triggering ovulation. A second aim was to compare the clinical outcome and embryo quality according to the two procedures. The cycle characteristics of 100 oocyte donors undergoing ovarian stimulation and IVF outcomes of their 100 oocyte recipients were analysed. Donors were prospectively randomized into two groups on the last day of ovarian stimulation: Group I received a single bolus …
Concomitant gonadotropin-releasing hormone agonist and menotropin treatment for the synchronized induction of multiple follicles.
1988
In an effort to overcome possible interference by endogenous gonadotropin-ovarian hormone dynamics, desensitization of the pituitary gonadotropins by a gonadotropin-releasing hormone agonist (GnRHa) was achieved in 12 women with repeatedly failed attempts at multiple follicular stimulation. Eight women were scheduled for in vitro fertilization (IVF) and embryo transfer (ET), and 4 for gamete intrafallopian transfer (GIFT). Stimulation failure was characterized by premature luteinization, poor estradiol (E2) response, or inadequate follicular growth. The agonist was administered by nasal spray 500 to 600 micrograms/day beginning on days 21 to 23 of the menstrual cycle. A rapid desensitizatio…
Similar endometrial development in oocyte donors treated with either high- or standard-dose GnRH antagonist compared to treatment with a GnRH agonist…
2005
Background This descriptive study evaluates the impact on endometrial development of standard and high doses of a GnRH antagonist in stimulated cycles compared with GnRH agonist and natural cycles. Methods Thirty-one oocyte donors were treated with a combination of rFSH and 0.25 mg/day ganirelix (standard dose), 2 mg/day ganirelix (high dose) or 0.6 mg/day buserelin (long protocol). Vaginal progesterone (200 mg/day) was administered in the luteal phase. Endometrial biopsies were performed 2 and 7 days after HCG administration. Additional biopsies were carried out in a subset of 12 subjects, 2 and 7 days following the LH peak of their previous natural cycle. Biopsies were evaluated histologi…