In vitro,in vivo studies of a new amphiphilic adsorbent for the removal of low-density lipoprotein

A new amphiphilic adsorbent for the removal of low-density lipoprotein (LDL) was prepared according to the literature (Artif. Cells Blood Subs., Immob. Biotechnol. 30 (4) (2002) 285). The effects of sulfonation and grafting time of cholesterol on the swelling property of adsorbent were studied. When sulfonation and grafting time of cholesterol was 3 and 5 h, respectively, the amphiphilic adsorbent had a high adsorption capacity for LDL without significantly adsorbing high-density lipoprotein. The adsorption capacity of the adsorbent for the removal of LDL, total cholesterol (TC) and TG was 1.916, 2.132, 1.349 mg/ml, respectively. Hyperlipidemia rabbits were developed by feeding with fodder containing high content of cholesterol or yolk, which was then perfused with an optimal amount of amphiphilic adsorbent. After 2 h hemoperfusion, the LDL levels decreased from 3.619+/-0.354 to 0.724+/-0.07 mmol/l, which showed that the adsorbent could effectively remove LDL without side effect.     

In vitro study of odor-evoked behavior in a terrestrial mollusk

To explore neural mechanisms how olfactory information is processed in the brain and finally converted into behavior, it would be useful to have isolated whole brains that include both olfactory organs and motor output. In the present study, we identified an in vitro index of odor-evoked behavior in the terrestrial mollusk Limax and also studied the modulation of this in vitro index of the behavior. We determined that shortening of the mantle muscles is one of the withdrawal responses selectively induced by aversive odors and that the shortening is mediated by a pair of parietal nerves. We also identified a motoneuron (named the posterior visceral neuron, p-VN) that projects to the parietal nerve and innervates the mantle muscles. When we applied various odors to the nose in these isolated molluscan brains, only aversive odors induced discharges in the p-VN. These results indicate that p-VN discharges can serve as an in vitro index of odor-induced aversive behavior. We also identified a novel serotonergic neuron (named the posterior cerebral serotonergic cell, p-CSC). Discharges in the p-CSC released serotonin to the tentacle ganglion (TG); serotonin in the TG then inhibited odor-induced discharges in the p-VN, the in vitro index of aversive behavior. These results suggest that the serotonergic system is involved in the regulation of approach and avoidance behavior in Limax.     

In vitro models to study hepatotoxicity

Drug discovery and development consists of a series of processes starting with the demonstration of pharmacological effects in experimental cell and animal models and ending with drug safety and efficacy studies in patients. A main limitation is often the unacceptable level of toxicity with the liver as the primary target organ. Therefore, approaches to study hepatic toxicity in the early phase of drug discovery represent an important step towards rational drug development. A variety of in vitro liver models have been developed in the past years. Next to their use in drug development, they can also be applied to study environmental toxins and their hepatotoxicity. The 3 main approaches are ex vivo isolated and perfused organ models, precision-cut liver slices and cell culture models. Although the advantage of whole organ perfusions is based on the assessment of physiologic parameters such as bile production and morphologic parameters such as tissue histology, cell culture models can be efficiently used to assess cellular metabolism, cytotoxicity and genotoxicity. The advantage of precision-cut liver slices is based on the juxtaposition of cellular assays and tissue morphology. None of these models can be compared as they all focus on different fields of hepatoxicology. For the future, the ideal setup for testing the hepatic toxicity of a new compound could of primary studies in cell or slice cultures to assess cellular effects and secondary studies using ex vivo perfused organs to examine gross organ function parameters and histology.     

In vitro study of cell-promoting multiple-armed peptides

The purpose of this study was to compare the effectiveness of several linear and branch cell-binding peptides to promote cell growth in prosthetic vascular grafts. In this in vitro study, the peptides were covalently immobilized onto expanded polytetrafluoroethylene (ePTFE) vascular grafts. Cell-growth properties were studied using primary human umbilical vein endothelial cells (HUVECs) and primary human umbilical artery smooth muscle cells (HUASMCs). Linear peptides (P15 and P15') and multiple-armed peptides (MAP4-I and MAP4-II) were covalently bonded onto ePTFE grafts by an atmospheric plasma coating method. X-ray photoelectron spectroscopy and amino acid analysis were used to analyze the surface characteristics of the peptide-coated samples. Cell adhesion, proliferation, and morphology were evaluated by culturing HUVECs and HUASMCs onto the surfaces of different samples: ePTFE control, chemically activated ePTFE, P15-coated ePTFE, and MAP4-coated ePTFE. The cell culture experiments were repeated several times to obtain statistically reliable cell-growth data. Cell-growth data were statistically analyzed by the two-way statistical analysis of variance. The study showed that multiple-armed MAP4 peptides were significantly more effective in promoting endothelial cells than the structurally similar linear P15 peptides. There were 800% more HUVECs proliferated on the MAP4-coated ePTFE samples compared with the ePTFE control. MAP4 peptides were 80% more effective for promoting HUVECs than P15 peptides. In contrast, MAP4 peptides were significantly less effective for promoting HUASMCs than HUVECs. There were only about 100% more HUASMCs proliferated on the MAP4-coated ePTFE samples compared with the ePTFE control. MAP4 and P15 peptides had similar cell-promoting characteristics for SMCs.     

In vitro encystation of Blastocystis hominis : a kinetics and cytochemistry study

The kinetics of in vitro encystation of Blastocystis hominis was studied over 9 days. The differentiation between trophic (TF) and cyst forms (CF) was determined by differential counts before and after treatment with distilled water. A cytochemistry study using acridine orange and Calcofluor white wet-mount preparations of CF was carried out. The growth curves of TF and CF were related because the decrease in TF was followed by an increase in CF, and vice versa. The maximum of CF counts was obtained on the 6th or 7th day. Using the differential acridine orange stain, two subpopulations of CF, yellow-orange fluorescent cells or precysts and green fluorescent cells or cysts, were detected and their curves were also related. CF was stained by Calcofluor white, which suggested the existence of β-(1-4)-glycosyl residues in the wall cysts of B. hominis. Received: 27 May 1997 / Accepted: 15 July 1997     

In vitro study of ceftriaxone binding to blood

Binding of ceftriaxone, a new third generation cephalosporin, to blood was studied in vitro. Steady state dialysis with 14C-ceftriaxone was used. Percentages of ceftriaxone bound to plasma within the range of therapeutic concentrations (10 to 1,000 microM) varied widely (80 to 50%). Indicating that the binding process is saturable, investigations performed with various isolated plasma proteins in physiologic concentrations show that ceftriaxone binds mainly to albumin, and marginally or not at all to alpha-1-acid glycoprotein, gammaglobulins, transferrin, haptoglobin, and lipoproteins. Albumin has a single binding site (n = 0.7) with moderate affinity (Ka = 72,000 M-1) for ceftriaxone. The presence of this site explains why ceftriaxone binds to plasma according to a saturable process. Only a small proportion (5%) of ceftriaxone (75-450 microM) binds to red blood cells in whole blood with a 50% hematocrit. A strongly significant inhibition of ceftriaxone (520 microM) binding to plasma was found with high bilirubin levels (230 microM) (24% decrease; p less than 0.01). A small but significant decrease in ceftriaxone (380 microM) binding to plasma was found with high serum oleic acid (1014 microM) or uric acid (1,800 microM) concentrations (2% decrease; p less than 0.05).     

In vitro synthesis of human IgE: reappraisal of a 5-year study

In the last 5 years some models of human IgE production in vitro have been investigated in our laboratory. Spontaneous IgE synthesis was found in cultures of B cells from most patients with atopic dermatitis or atopic patients with multiple sensitivities and from some patients with pollenosis, but only during the pollination period. A small and variable increase of the spontaneous IgE synthesis was induced by soluble factor(s) produced by T cells from patients with severe atopy. Selected helper T cell clones were also able to induce IgE synthesis in vitro by both atopic and normal B cells.     

In vitro study of biodegradation of a Co-Cr alloy using a human cell culture model

—The evaluation of a potential biomaterial is based on two approaches: firstly, the study of the local and systemic effects of the biomaterial implanted in the host; and secondly the study of the behaviour of the biomaterial itself with increasing time. The progress achieved in human cell culturing allows in vitro evaluation of a new biomaterial using the human cell(s) system(s) characteristic of the tissue which it will be exposed to in vivo. This kind of approach permits the assessment of the biodegradation of a biomaterial whatever it is: metal; alloy; ceramic; glass; polymer; with or without specialized coating.... The experimental approach is as follows: discs representative of the biomaterial (surface state, cleaning, sterilization process) are manufactured in order to cover the bottom of the culture wells. Thereafter, they are either brought in the presence of complete culture medium alone, or in the presence of a subconfluent cell layer. A kinetic analysis is performed using various incubation periods at 37°C. Released biodegradation products are identified and quantified, in both the medium and cell compartment, and on the other hand cytotoxicity is assessed. A Co-Cr alloy was studied over a 9-day period according to the experimental schedule, and showed a higher corrosion rate in the presence of osteoblasts in the range of 25-30%. Moreover, an intracellular uptake of both Cr and Co was detected, which will have physiological importance.     

In vitro study of the Norwood palliation: a patient-specific mock circulatory system

The aim of this study was to build a mock circulatory system replicating in vitro the hemodynamics following the Norwood procedure and testing patient-specific anatomies focusing on the effect of aortic coarctation. Three anatomies were reconstructed from magnetic resonance images and rapid prototyped with transparent rigid resin. The models presented varying degrees of coarctation (none, moderate, and severe). A Blalock-Taussing (BT) shunt was modeled in all phantoms, which were inserted into a mock circulation. The single ventricle was simulated using a Berlin Heart driven with a PC-controlled piston. Resistive and compliant elements were implemented, creating a lumped parameter network. Pressure was measured at three locations: the transverse aortic arch, just after the aortic isthmus, and further downstream in the thoracic aorta. Volume distribution was derived from the instantaneous flow measurements at three outlets: upper body, lower body, and BT shunt. The combination of three-dimensional (3D) detailed anatomy and lumped parameter network effectively renders the circuit a multiscale in vitro model that successfully reproduces physiologic pressure signals. The pressure results highlight the larger pressure drop caused by coarctation and show the effect of pressure recovery. Results also suggest a reduction of flow to the lower body with increasing severity of coarctation, to the advantage of upper body and pulmonary circulation.     

Bostrycin作为肺癌分子靶向药物的体外研究

目的 观察海洋真菌新结构先导化合物Bostrycin对A549细胞增殖和凋亡的影响,并探讨其作用机制.方法 A549细胞完全随机分为实验组和对照组,实验组用不同浓度不同作用时间的Bostrycin进行处理,而对照组未经Bostrycin处理.用MTT法检测A549细胞增殖率的变化;电镜、流式细胞术检测凋亡;实时定量PCR和免疫印迹法探讨其作用机制.结果 Boatrycin浓度≥10μmol/L时对A549细胞增殖有明显的抑制作用,其24、48和72 h的半数抑制浓度(IC_(50))分别为20.20、14.36和9.42μmol/L.Bostrycin干预后,电镜观察到A549细胞典型的凋亡形态;流式细胞术结果显示其G_0/G_1期比例升高、S期和G_2/M期比例下降,凋亡率增加.实时定量PCR检测到微小RNA(miRNA)一638和miRNA.923的表达较对照组上调.免疫印迹结果显示p110α、p-Akt蛋白表达量下降,p27蛋白表达量升高.结论 Bostrycin对A549细胞增殖有显著抑制作用,该作用可能通过miRNA抑制磷脂酰肌醇3-激酶/蛋白激酶B(P13K/Akt)通路进行.     

In vitro study of the antimutagenic activity of alphahederin

Authors have studied the antimutagenic power of alphahederin (a saponin extracted from Hedera helix) versus a clastogenic agent, doxorubicin and an aneugenic agent, carbendazim. We have applied a protocol of incorporation of alphahederin (pretreatment, simultaneous treatment and post treatment) to determine a mechanism of action. According to this protocol, alphahederin induces a significant diminution of the rate of micronuclei wathever the phases of the protocol. These results demonstrate the antimutagenic activity of alphahederin with a mechanism of action, both desmutagenic and bioantimutagenic.     

In vivo-in vitro study of biodegradable methadone delivery systems

Three one-week controlled-release methadone formulations: polylactic acid microspheres (F-PLA) and poly(lactide-co-glycolide) microspheres (F-PLGA) with 24 and 30% methadone content, respectively, and an implant of 50:50 poly(lactide-co-glycolide): methadone, were evaluated in vitro and in vivo. The implant released the total amount of methadone in vitro while microsphere formulations released the methadone incompletely, 63% from F-PLA and 85% from F-PLGA in a week. Methadone release in vivo was estimated by deconvolution, F-PLGA giving a bioavailability >99% (methadone was totally released in 48h), while the estimated bioavailability of F-PLA was lower than expected. The bioavailability of the implant by deconvolution was around 60%, but absence of methadone in the implant indicated its complete release. These differences are due to an increase in methadone clearance after 72 h of the in vivo experimental period had passed, disturbing a good in vivo-in vitro correlation. A linear correlation between in vitro methadone release and in vivo release calculated from the amount of drug remaining within the implant, was found until the drug was completely released.     

In vitro study of Fc-receptor function in autoimmune diseases

A simple test for studying in vitro Fc-receptor function of mononuclear phagocytes is described. Immune phagocytosis is analyzed as a dynamic phenomenon by using nearly pure suspensions of monocytes incubated for diverse times with autologous erythrocytes sensitized with highly purified IgG. In a series of normal volunteers and patients with vasculitis a strict correlation has been found between this in vitro assay and the measure of splenic clearance of IgG-coated red blood cells (RBC), the classical approach for studying in vivo macrophage Fc-receptor function by using sodium chromate 51Cr as tag. The use of this in vitro assay appears to be valuable mainly in cases requiring repeated measurements of Fc-receptor function for monitoring the course of disease or the effects of therapy.     

In vitro activity of ceftizoxime on hospital bacteria. Results of a multicenter study

The susceptibility to ceftizoxime of all bacterial strains isolated from seven university-affiliated hospitals over one month was tested with disk-diffusion technique. Additionally, the MIC of 1937 strains selected at random was evaluated by the agar dilution method. The majority of Enterobacteriaceae are inhibited at a concentration of less than 1 microgram/ml with a mode MIC varying from 0.008 to 0.12 among the various groups. A few Enterobacter and Citrobacter strains are resistant. Little activity was demonstrated by ceftizoxime on Pseudomonas aeruginosa and Acinetobacter sp. (mode MIC 32 and 8 micrograms/ml respectively). Haemophilus sp. (MIC 0.01-0.03) and Neisseria (MIC less than 0,008-0,016) are very susceptible to the drug. The MIC of methicillin-sensitive strains of Staphylococcus aureus varies from 1 to 4 micrograms/ml ; Enterococci are less susceptible, whereas other Streptococci and Pneumococci have low MICs (less than 0.008-0.025). The susceptibility of anaerobic pathogens varies widely between species, and within species ; MIC ranges from 0.008 to 32 micrograms/ml for Clostridium sp. and 0.25 to 128 micrograms/ml for Bacteroides sp.     

In vitro antibacterial activity of a new macrolide, miokamycin. Results of a multicenter study

Minimal inhibitory concentration (MIC) of miokamycin (M) were evaluated by agar dilution for 1,024 bacterial strains isolated in 6 hospitals and classed as a function of susceptibility and resistance to macrolides, lincosamides, streptogramins group (MLS). MIC of M ranged from 0.25 to 4 micrograms/ml (mode MIC 1-2) on Staphylococcus susceptible to MLS and on MLSB inducible strains; M was inactive on MLSB constitutive strains. MIC of M ranged from 0.016 to 4 micrograms/ml (mode MIC 0.12 to 0.5) for Streptococci and Pneumococci susceptible to erythromycin (E) and from 0.12 to greater than 128 for strains resistant to E. Enterococci susceptible to E were inhibited by 0.5 to 2 micrograms/ml (mode MIC 1) and strains resistant to E by 4 to greater than 128. Haemophilus were inhibited by 2 to 64 micrograms/ml (mode MIC 32), Neisseria by 0.12 to 4 (mode MIC 0.5-1) and B. catarrhalis by 0.12 to 8 (mode MIC 1). L. pneumophila was very susceptible to M: MIC 0.016 to 0.12 (mode MIC 0.06). MIC of M ranged generally from 0.5 to 2 micrograms/ml (mode MIC 1) for C. perfringens and from 0.03 to 2 (mode MIC 1) for B. fragilis. Thus, M was shown to be among macrolide antibiotics of resistance non-inducing type on MLSB inducible resistance strains. Its activity was similar to that of spiramycin slightly superior on Staphylococci, slightly inferior on Streptococci and Enterococci, similar on Pneumococci, very superior on Neisseria, Legionella and anaerobes. M had a good activity on Branhamella and, as others macrolides, was poorly active on Haemophilus.     

In vitro and in vivo assessment of bone-implant interface: a comparative study.

The present in vitro and in vivo comparison of three bioactive (HA, AP40, RKKP) and three bioinert (Ti6-Al4-V, Al2O3, ZrO2) materials was undertaken to identify which of them provide(s) the most suitable coating for prostheses implanted in patients with altered metabolic status. The experimental design included in vitro tests with human osteoblasts and morphological observations by scanning electron microscopy. For the in vivo evaluation, the materials were implanted in the femoral condyle of ovariectomised and intact female rats, and two months after surgery an X-ray microanalytical study was performed. The in vitro study showed good biocompatibility with all materials. Microanalysis evidenced a similar behaviour with all materials except the two biological glasses. The differences in Ca and P content observed between intact and ovariectomised rats can be explained by the intrinsic capability of biological glasses to undergo surface modifications in the presence of alterations of the bone metabolism. Thus, their use seems to be indicated in recipients with osteoporotic pathologies.     

In vitro corrosion study by EIS of a nickel-free stainless steel for orthopaedic applications

The electrochemical impedance spectroscopy (EIS) technique was used for the study of the electrochemical behaviour of Ni-free austenitic stainless steel for orthopaedic applications. Experiments were carried out using four different test solutions: (i) phosphate-buffered saline (PBS), (ii) minimum essential medium (MEM), (iii) MEM + 10% fetal calf serum (FCS), (iv) MEM + 10% fetal calf serum + L929 fibroblast cell line (Cell). Bode-phase spectra showed the presence of two maxima and were fitted with an equivalent circuit characterized by two parallel combinations (Resistance, Constant Phase Element). The (R(1), CPE(1)) branch was assigned to the inner compact passive film and the (R(2), CPE(2)) branch to the external porous film. The resistance of the inner film R(1), here directly related to the material's uniform corrosion resistance, raised with the immersion time and increased in the following order: PBS相似文献