Search results for "VITRO"
showing 10 items of 2786 documents
Dopaminergic modulation of evoked vasopressin release from the isolated neurohypophysis of the rat
1982
1. Neurointermediate lobes of rat pituitaries were incubated in Locke or Krebs solution, and the vasopressin released into the medium was assayed on the blood pressure of the pithed rat or by a radioimmunological procedure. Release of vasopressin over resting levels was evoked either by incubation with 60 mM KCl (high K) solution or by electrical stimulation of the pituitary stalk. Two different kinds of electrical stimulation were carried out. Procedure A (1 ms, 10 Hz, 5 times for 1 min within 10 min) induced a vasopressin overflow which was greatly calcium-dependent but only insignificantly sensitive to tetrodotoxin (TTX). Procedure B (0.2 ms, 15 Hz, 10 s trains with 10 s intervals for 10…
The toxic and lethal effects of the trehalase inhibitor trehazolin in locusts are caused by hypoglycaemia
2003
SUMMARY The main blood sugar of locusts is trehalose, which is hydrolysed to two glucose units by trehalase. Homogenates of locust flight muscles are rich in trehalase activity, which is bound to membranes. A minor fraction of trehalase is in an overt form while the remainder is latent, i.e. active only after impairing membrane integrity. Trehazolin, an antibiotic pseudosaccharide,inhibits locust flight muscle trehalase with apparent Ki-and EC50 values of 10–8 mol l–1and 10–7 mol l–1, respectively. Trehazolin is insecticidal: 50 μg injected into locusts completely and selectively blocked the overt form of muscle trehalase (with little effect on latent activity) and killed 50% of the insects…
Presence of thyroid hormones in ascidian larvae and their involvement in metamorphosis
2001
In this study we investigated the presence and localization of thyroxine in Ciona intestinalis larvae and its involvement in metamorphosis. To date, the mechanisms regulating the metamorphosis of ascidians remain largely unknown. In vivo treatment of swimming larvae with exogenous L-thyroxine and thiourea, and in vitro experiments utilizing high performance liquid chromatography, radioimmunoassay, and immunoperoxidase staining demonstrate the presence of thyroxine at the larval stage. This suggests that this hormone may participate in the control of metamorphosis and thus play a different role from that observed in adults.
In vitro evaluation of the biocompatibility of contaminated implant surfaces treated with an Er : YAG laser and an air powder system
2004
Abstract: Titanium platelets with a sand-blasted and acid-etched surface were coated with bovine serum albumin and incubated with a suspension of Porphyromonas gingivalis (ATCC 33277). Four groups with a total of 48 specimens were formed. Laser irradiation of the specimens (n=12) was performed on a computer-controlled XY translation stage at pulse energy 60 mJ and frequency 10 pps. Twelve specimens were treated with an air powder system. After the respective treatment, human gingival fibroblasts were incubated on the specimens. The proliferation rate was determined by means of fluorescence activity of a redox indicator (Alamar Blue® Assay) which is reduced by metabolic activity related to c…
Social control of testicular steroidogenic capacities in the Siamese fighting fishBetta splendens Regan
1987
Male Siamese fighting fish (Betta splendens Regan) of the veiltail variety were raised. At the age of 4 ½ months they were either isolated or community-housed for 2 ½ months. After that time the relative fin lengths were determined, and the in vitro metabolism of testosterone by the testes of the fishes was investigated. Community-housed specimens had shorter fins than the isolated males. Their testes formed less 11-oxy- and more 5β-steroids than those of the isolated males. This difference was even larger when high- and low-ranking community-based specimens were compared. The appearance of low-ranking males resembled that of females, and the main products of their testes were 5β-reduced st…
Product of aromatase activity in intact LNCaP and MCF-7 human cancer cells
1997
We investigated conversion rates of androgens to estrogens in cultured, hormone-responsive prostate (LNCaP) and breast (MCF-7) human cancer cells. For this purpose, we adopted an intact cell analysis, whereby cells were incubated for different incubation times in the presence of close-to-physiological (1 nM) or supraphysiological (1 μM) concentrations of labelled androgen precursors, i.e. testosterone (T) and androstenedione (Δ4Ad). The aromatase activity, as measured by estrogen formation, was detected in LNCaP cells (0.5 pmol/ml), even though to a significantly lower extent than in MCF-7 cells (5.4 pmol/ml), using 1 μM T after 72 h incubation. Surprisingly, LNCaP cells displayed a much hi…
Cardiac arrhythmia induced by hypothermia in a cardiac model in vitro
2013
The neurological damage after cardiac arrest (CA) constitutes a big challenge of hospital discharge since years. The therapeutic hypothermia therapy (34°C-32°C) has shown its benefit to reduce cerebral oxygen demand and improve neurological outcomes after the cardiac arrest. Despite the fact that induced hypothermia after CA has been shown to increase the hospital survival rate, it can have many adverse effects, among which the cardiac arrhythmia generation represents an important part (up to 34%, according different clinical studies). Compared to studies in vivo, cardiac culture in vitro provides a better spatial resolution at cellular level, which could bring some insights of the mechanis…
In vitro evaluation of the efficacy of two bleaching procedures
2010
Objective: In vitro comparison of the efficacy of two bleaching procedures, one based on carbamide peroxide (CP) and the other on hydrogen peroxide (HP), simulating clinical conditions. Study Design: Two groups of 20 teeth in each group were selected. Group A: 22% CP, one hour a day for 21 consecutive days. Group B: 37.5% HP, in 2 treatment sessions with an one week interval between each session. At each session the product was applied three successive times for eight minutes. Colour was recorded before treatment, when it was finished and one week after finishing it, with the Vita EasyShade spectrophotometer. CIEL*a*b* and ΔE were established at each moment in the study. Intra-group data wa…
In vitro effects of oil's fatty acids on T cell function in gestational diabetic pregnant women and their newborns 油类脂肪酸在体外对妊娠期糖尿病孕妇及其新生儿的T细胞功能的影响
2014
Background The aim of this investigation was to determine the in vitro effects of linseed, olive and Nigel oils on T cell proliferation and function in gestational diabetes. Methods Blood samples were collected from 40 control healthy and 32 gestational diabetic mothers and their newborns. Peripheral blood lymphocytes were isolated using a density gradient of Ficoll. T cell proliferation, interleukin-2 and -4 (IL-2, IL-4) secretion, fatty acid composition and intracellular oxidative status were investigated. Results Mitogen (Concanavalin A) stimulated lymphocyte proliferation, IL-2 secretion, intracellular reduced glutathione levels, superoxide dismutase (SOD) and catalase activities were l…
Right ventricular volume determination in isolated human hearts
1986
For right ventricular volume determination a new method was developed that took into account right ventricular imaging by apical two-dimensional echocardiography in the four- and two-chamber views. Right ventricular volume was calculated by subtraction of the partial volume of the left ventricle and interventricular septum from the total heart volume of the right and left ventricles including the interventricular septum. Accuracy of the subtraction method was evaluated in isolated human hearts by two-dimensional echocardiography and radiography. Regression analysis indicated that for both the echocardiographic and radiologic procedures, the subtraction method gave the best correlation with …