scholarly journals Amphiphilic azopolymers capable to generate photo-sensitive micelles

2011 ◽  
Vol 9 (6) ◽  
pp. 1117-1125 ◽  
Author(s):  
Ioana Moleavin ◽  
Constanta Ibanescu ◽  
Anca Hodorog-Rusu ◽  
Ecaterina Peptu ◽  
Florica Doroftei ◽  
...  
Keyword(s):  
Targeted Delivery ◽  
Critical Concentration ◽  
Fluorescence Emission ◽  
Good Control ◽  
Fluorescence Emission Spectrum ◽  
Long Term Stability ◽  
Micellar Aggregates ◽  
Preliminary Study ◽  
And Control

AbstractAmphiphilic macromolecular micelles are advantageous for drug delivery applications due to the decrease of side-effects, ease of screening drugs against degradation, long-term stability, targeted delivery and control of the amount of the released drug. A series of amphiphilic azo-polymers having a flexible or rigid main-chain were synthesized and characterized. The presence of chlorobenzyl side-groups allowed both the easy bonding of photo-sensitive or hydrophilic groups and good control of the degree of substitution. The chemical structure was confirmed by 1H-NMR. The critical concentration of aggregation (CCA) was calculated using the fluorescence emission spectrum of pyrene. The interest was focused on a preliminary study concerning the disaggregation capacity of micelles under UV irradiation. The presence of micellar aggregates was confirmed by DLS and SEM and different organization of the amphiphilic polymers was evidenced depending on polymers concentration and polymers structure. In low polymer concentrations in water predominantly globular aggregates were formed. The increase in concentration increased the polydispersity index due to the fusion of micelles and formation of associates of globular aggregates, inter-micellar associates (clusters) and vesicles.

scholarly journals Apoferritin/Vandetanib Association Is Long-Term Stable but Does Not Improve Pharmacological Properties of Vandetanib

2021 ◽  
Vol 22 (8) ◽  
pp. 4250
Author(s):  
Kateřina Jáklová ◽  
Tereza Feglarová ◽  
Simona Rex ◽  
Zbyněk Heger ◽  
Tomáš Eckschlager ◽  
...  
Keyword(s):  
Cell Lines ◽  
Targeted Delivery ◽  
Medullary Thyroid Cancer ◽  
Kinase Inhibitor ◽  
Medullary Thyroid ◽  
Long Term Stability ◽  
Carcinoma Cell Lines ◽  
Average Size ◽  
Thyroid Carcinoma Cell

A tyrosine kinase inhibitor, vandetanib (Van), is an anticancer drug affecting the signaling of VEGFR, EGFR and RET protooncogenes. Van is primarily used for the treatment of advanced or metastatic medullary thyroid cancer; however, its usage is significantly limited by side effects, particularly cardiotoxicity. One approach to minimize them is the encapsulation or binding of Van in- or onto a suitable carrier, allowing targeted delivery to tumor tissue. Herein, we constructed a nanocarrier based on apoferritin associated with Van (ApoVan). Based on the characteristics obtained by analyzing the average size, the surface ζ-potential and the polydispersive index, ApoVan nanoparticles exhibit long-term stability and maintain their morphology. Experiments have shown that ApoVan complex is relatively stable during storage. It was found that Van is gradually released from its ApoVan form into the neutral environment (pH 7.4) as well as into the acidic environment (pH 6.5). The effect of free Van and ApoVan on neuroblastoma and medullary thyroid carcinoma cell lines revealed that both forms were toxic in both used cell lines, and minimal differences between ApoVan and Van were observed. Thus, we assume that Van might not be encapsulated into the cavity of apoferritin, but instead only binds to its surface.

scholarly journals Targeted Release of Probiotics from Enteric Microparticulated Formulations

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1668 ◽  
Author(s):  
Cristina Yus ◽  
Ruben Gracia ◽  
Ane Larrea ◽  
Vanesa Andreu ◽  
Silvia Irusta ◽  
...  
Keyword(s):  
Targeted Delivery ◽  
Target Tissue ◽  
Release Formulation ◽  
Long Term Stability ◽  
Pharmaceutical Ingredients ◽  
Efficient Delivery ◽  
Synthesized Materials ◽  
First Time ◽  
Targeted Release

The development of advanced probiotic delivery systems, which preserve bacteria from degradation of the gastrointestinal tract and achieve a targeted release mediated by pH-independent swelling, is of great interest to improve the efficient delivery of probiotic bacteria to the target tissue. Gram-positive and Gram-negative bacteria models (Lactobacillus acidophilus (Moro) Hansen and Mocquot (ATCC® 4356™) and Escherichia coli S17, respectively) have been successfully encapsulated for the first time in pH-independent microparticulate polymethacrylates (i.e., Eudraguard biotic) used for the targeted delivery of nutraceuticals to the colon. These bacteria have also been encapsulated within the mucoadhesive polymethacrylate Eudragit RS 100 widely used as targeted release formulation for active pharmaceutical ingredients. The enteric microparticles remained unaltered under simulated gastric conditions and released the contained viable microbial cargo under simulated intestinal conditions. Buoyancies of 90.2% and 57.3% for Eudragit and Eudraguard microparticles, respectively, and long-term stability (5 months) for the encapsulated microorganisms were found. Cytotoxicity of the microparticles formulated with both polymers was evaluated (0.5–20 mg/mL) on Caco-2 cells, showing high cytocompatibility. These results underline the suitability of the synthesized materials for the successful delivery of probiotic formulations to the target organ, highlighting for the first time the potential use of Eudraguard biotic as an effective enteric coating for the targeted delivery of probiotics.

A Few Aspects on Lubricant Selection for Stepless Chain Coverters: Efficiency and Service Life

1992 ◽  
Author(s):  
G. Schönnenbeck
Keyword(s):  
Friction Coefficient ◽  
Service Life ◽  
Standardized Test ◽  
Test Methods ◽  
Long Term Stability ◽  
Friction Disk ◽  
The Individual ◽  
And Control ◽  
Selection Of

Abstract Stepless vehicle drives will assume their place next to automatic switching units throughout the world if they meet their expected fuel-saving potential. This necessitates optimizing the individual components of the CVT as regards their efficiency. The main source of losses are the hydraulic supply units and the losses which result specifically from non-positive transmission. In the case of stepless chain conveners, these result mainly from friction disk deformation. These losses account for 50 to 70 % of total CVT losses. Both loss components are influenced by the lubricant to a significantly greater extent than it would appear at first sight: In the case of fully-hydraulic clamping and control systems, the viscosity and its long-term stability determines the degree of leakage losses and therefore the size of the pump or pump combinations. This applies to pressure levels between 20 and 40 bar. This in turn is directly proportional to the hydraulic losses on the CVT. The friction coefficient of the lubricant determines the level of the necessary clamping forces. These are responsible for friction-disk deformation. Also of importance as far as the selection of lubricant is concerned is its influence on the CVT service life. The critical service life limits for chain converters are chain breakage (not the subject of this report) and evidence of wear, i.e. grey staining, sheave-grooving, pitting, scoring and rocker pin wear. Standardized test methods exist at P.I.V. for both wear manifestations and for the friction coefficient, these tests allowing a targeted selection of lubricants.

scholarly journals Team Incentives and Performance: Evidence from a Retail Chain

2017 ◽  
Vol 107 (8) ◽  
pp. 2168-2203 ◽  
Author(s):  
Guido Friebel ◽  
Matthias Heinz ◽  
Miriam Krueger ◽  
Nikolay Zubanov
Keyword(s):  
Field Experiment ◽  
Treatment Effect ◽  
Peer Pressure ◽  
Long Term Stability ◽  
Retail Chain ◽  
Sales Teams ◽  
And Performance ◽  
And Control ◽  
Number Of Customers

In a field experiment with a retail chain (1,300 employees, 193 shops), randomly selected sales teams received a bonus. The bonus increases both sales and number of customers dealt with by 3 percent. Each dollar spent on the bonus generates $3.80 in sales, and $2.10 in profit. Wages increase by 2.2 percent while inequality rises only moderately. The analysis suggests effort complementarities to be important, and the effectiveness of peer pressure in overcoming free-riding to be limited. After rolling out the bonus scheme, the performance of the treatment and control shops converges, suggesting long-term stability of the treatment effect. (JEL D22, J31, J33, L25, L81, M53, M54)

Production and Control of Reference Materials for Water Microbiology

1991 ◽  
Vol 24 (2) ◽  
pp. 53-56 ◽  
Author(s):  
K. A. Mooijman ◽  
A. H. Havelaar ◽  
J. A. Hoekstra ◽  
N. G. W. N. van Strijp-Lockefeer
Keyword(s):  
Reference Materials ◽  
Milk Powder ◽  
Contamination Level ◽  
Long Term Stability ◽  
Collaborative Studies ◽  
Water Microbiology ◽  
Challenge Tests ◽  
Short Time ◽  
And Control

Reference materials for water microbiology were prepared by spray-drying milk, artificially contaminated with a known test strain. The resulting highly contaminated milk powder was mixed with sterile milk powder to a contamination level of 2000-3000 cfu/g. Gelatin capsules were filled with the mixture (0.2 g/capsule) to produce the reference materials. Test strains used were: WR1 Escherichia coli, WR3 Enterobacter cloacae, WR63 Enterococcus faecium and WR51 Staphylococcus spec. Optimalization of the mixing procedure and aging of the highly contaminated milk powder resulted in relatively homogeneous and stable reference materials. Short-time challenge tests at “high” temperatures (30 and 37 °C) may be predictive for long-term stability at “low” temperatures (4-6 °C). Reference materials with strain WR3 were stable for one week at 30 °C and for at least 6 months at 4-6 °C. Possible applications of the reference materials are: quality control of routine measurements, comparison of the efficiency of different culturing methods and as a standardized sample in collaborative studies.

Novel use for a predator scent: preliminary data suggest that wombats avoid recolonising collapsed burrows following application of dingo scent

2016 ◽  
Vol 64 (3) ◽  
pp. 192 ◽  
Author(s):  
Elisa E. Sparrow ◽  
Michael H. Parsons ◽  
Daniel T. Blumstein
Keyword(s):  
Repeated Measures ◽  
A Value ◽  
Sum Score ◽  
Fisher Method ◽  
Preliminary Study ◽  
Negative Controls ◽  
And Control ◽  
Active Controls ◽  
Generalised Estimating Equations

Southern hairy-nosed wombats (Lasiorhinus latifrons) are fossorial marsupials that live in large burrow systems where their digging behaviour brings them into conflict with agriculture. In the absence of any available control options, non-selective culling is the primary mode of wombat management. This approach is contentious and has unknown implications for long-term wombat conservation. Predator scents, however, have been effective in altering behaviours of some herbivores and may offer a non-lethal alternative to culling if they discourage wombats from burrowing in perceived problem areas. Therefore, we trialled two dingo scents (faeces, urine) over 75 days to determine whether these scents would deter wombats from repopulating collapsed burrows. Ten inhabited single-entrance burrows were excavated over three days (to allow time for inhabitants to exit), collapsed and then filled in. Five burrows, separated by at least 200 m, were used for dingo scent treatments (three urine; two faeces) and three burrows, separated by the same distance, served as negative controls (unscented), along with two ‘farmer-monitored’ active controls (dog urine and a dingo carcass). We used a rank-sum score to assess wombat activity: scratching was scored with a value of (1), digging (2), and recolonisation (5), with each value reflecting total energy and time spent in the vicinity of the treatment. We fitted Generalised Estimating Equations (repeated-measures, Fisher Method) to explain variation within, and across, treatment and control burrows. Within 20 days, all 10 sites had signs of wombat activity that ranged from fresh digging, to fully functional burrows. Among the five treatment sites, scratching and tracks identified wombats as being present, but they did not dig. After 75 days, the five sites treated with dingo scents had minimal activity and no new burrows, while wombats recolonised all control burrows. Though we used only 10 burrows for this preliminary study, our findings suggest the need for further testing of dingo scents as a tool for dissuading wombats from digging and recolonisation of collapsed burrows. This represents a novel use for a predator scent, in that prey may remain in the vicinity near the deterrent, but curb problematic behaviours of economic consequence.

Preliminary Study on the Long-term Stability of Fiber-Optic Sensors

2009 ◽  
Vol 96 (8) ◽  
pp. 52-61
Author(s):  
Roman Wendner ◽  
Alfred Strauss ◽  
Konrad Bergmeister ◽  
Michael Reiterer
Keyword(s):  
Fiber Optic ◽  
Fiber Optic Sensors ◽  
Term Stability ◽  
Long Term Stability ◽  
Preliminary Study

Ultrastructural observations of the aorta of calves implanted with a mechanical left ventricular assist device

1990 ◽  
Vol 48 (3) ◽  
pp. 834-835
Author(s):  
J P Cassella ◽  
V Salih ◽  
T R Graham
Keyword(s):  
Left Ventricular Assist Device ◽  
Ventricular Assist Device ◽  
Left Ventricular ◽  
Aortic Tissue ◽  
Assist Device ◽  
Ventricular Assist ◽  
Transmission Electron ◽  
Left Ventricular Assist ◽  
Preliminary Study

Left ventricular assist systems are being developed for eventual long term or permanent implantation as an alternative to heart transplantation in patients unsuitable for or denied the transplant option. Evaluation of the effects of these devices upon normal physiology is required. A preliminary study was conducted to evaluate the morphology of aortic tissue from calves implanted with a pneumatic Left Ventricular Assist device-LVAD. Two 3 month old heifer calves (calf 1 and calf 2) were electively explanted after 128 days and 47 days respectively. Descending thoracic aortic tissue from both animals was removed immediately post mortem and placed into karnovsky’s fixative. The tissue was subsequently processed for transmission electron microscopy (TEM). Some aortic tissue was fixed in neutral buffered formalin and processed for routine light microscopy.

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