THE ROLE OF POLYETHYLENIMINE IN ENHANCING PERFORMANCE OF GLUTAMATE BIOSENSORS

2018 ◽  
Vol 8 (3) ◽  
pp. 36-41
Author(s):  
Diep Do Thi Hong ◽  
Duong Le Phuoc ◽  
Hoai Nguyen Thi ◽  
Serra Pier Andrea ◽  
Rocchitta Gaia
Keyword(s):  
First Generation ◽  
Good Reproducibility ◽  
Complex Matrices ◽  
Long Term Stability ◽  
In Vitro Characterization ◽  
Glutamate Oxidase

Background: The first biosensor was constructed more than fifty years ago. It was composed of the biorecognition element and transducer. The first-generation enzyme biosensors play important role in monitoring neurotransmitter and determine small quantities of substances in complex matrices of the samples Glutamate is important biochemicals involved in energetic metabolism and neurotransmission. Therefore, biosensors requires the development a new approach exhibiting high sensibility, good reproducibility and longterm stability. The first-generation enzyme biosensors play important role in monitoring neurotransmitter and determine small quantities of substances in complex matrices of the samples. The aims of this work: To find out which concentration of polyethylenimine (PEI) exhibiting the most high sensibility, good reproducibility and long-term stability. Methods: We designed and developed glutamate biosensor using different concentration of PEI ranging from 0% to 5% at Day 1 and Day 8. Results: After Glutamate biosensors in-vitro characterization, several PEI concentrations, ranging from 0.5% to 1% seem to be the best in terms of VMAX, the KM; while PEI content ranging from 0.5% to 1% resulted stable, PEI 1% displayed an excellent stability. Conclusions: In the result, PEI 1% perfomed high sensibility, good stability and blocking interference. Furthermore, we expect to develop and characterize an implantable biosensor capable of detecting glutamate, glucose in vivo. Key words: Glutamate biosensors, PEi (Polyethylenimine) enhances glutamate oxidase, glutamate oxidase biosensors

A Novel Injectable Collagen Matrix: In Vitro Characterization and In Vivo Evaluation

2000 ◽  
Vol 122 (3) ◽  
pp. 231-235 ◽  
Author(s):  
Damien Laude ◽  
Kevin Odlum ◽  
Stewart Rudnicki ◽  
Nathaniel Bachrach
Keyword(s):  
Collagen Matrix ◽  
Porous Matrix ◽  
In Vivo Evaluation ◽  
Long Term Stability ◽  
In Vitro Characterization ◽  
Essential Properties ◽  
Novel Material

We present here a unique engineered collagen formulation that is injectable and compacts into a porous viscoelastic solid after implantation, achieving completely focal application without cross-linking. This implant provides a cohesive continuously porous matrix, as demonstrated by permeability and compression experiments. Those experiments also provide initial mechanical characterization of the material and establish the ability to modify these essential properties by design. Further, the short-term compaction and long-term stability of the implant in vivo in terms of both physical and histological responses are assessed in an animal model to demonstrate the mechanism of action and long-term persistence of this novel material. [S0148-0731(00)00403-9]

Correlation between magnesium and potassium contents in muscle: role of Na(+)-K+ pump

1993 ◽  
Vol 264 (2) ◽  
pp. C457-C463 ◽  
Author(s):  
I. Dorup ◽  
T. Clausen
Keyword(s):  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Deficient Diet ◽  
Young Rats ◽  
Wide Range ◽  
86Rb Influx

In young rats fed a Mg(2+)-deficient diet for 3 wk, Mg2+ and K+ contents in soleus and extensor digitorum longus muscles were significantly reduced and closely correlated. In isolated soleus muscles, Mg2+ depletion induced an even more pronounced loss of K+, and Mg2+ and K+ contents were correlated over a wide range (r = 0.95, P < 0.001). Extracellular Mg2+ (0-1.2 mM) caused no change in total or ouabain-suppressible 86Rb influx. After long-term incubation in Ca(2+)-Mg(2+)-free buffer with EDTA and EGTA, cellular Mg2+ and K+ contents were reduced by 35 and 15%, respectively, without any reduction in ATP and total or ouabain-suppressible 86Rb influx. In Mg(2+)-depleted muscles 42K efflux was increased by up to 42%, and repletion with Mg2+ produced a graded decrease. We conclude that Mg2+ and K+ contents are closely correlated in muscles Mg2+ depleted in vivo or in vitro and that neither extracellular nor moderate intracellular Mg2+ depletion affects total or Na(+)-K+ pump-mediated K+ influx. The reduced K+ content may rather be related to increased K+ efflux from the muscles.

scholarly journals Development and test for long-term stability of a synthetic standard for a quantitative Cryptosporidium parvum LightCycler™ PCR assay

2005 ◽  
Vol 3 (1) ◽  
pp. 15-25 ◽  
Author(s):  
Renata Filkorn-Kaiser ◽  
Konrad Botzenhart ◽  
Albrecht Wiedenmann
Keyword(s):  
Cryptosporidium Parvum ◽  
Surrogate Marker ◽  
Target Sequence ◽  
Positive Trend ◽  
Long Term Stability ◽  
Synthetic Standard ◽  
One Year

A recently described quantitative rapid cycle real time PCR (LightCycler™) assay detects Cryptosporidium parvum after in vitro excystation, which is a surrogate marker for the viability of the organisms. In the original assay the quantification standard is a dilution series of C. parvum oocysts with a microscopically determined excystation rate. The need to keep suspensions of viable oocysts in stock and to continuously monitor their excystation rate, however, renders the assay impracticable for routine application. A synthetic standard was developed to replace the in vivo standard and was calibrated using oocysts with known excystation rates. The standard consists of a 486 bp DNA segment ranging from 229 bp upstream to 79 bp downstream of the actual PCR target site. Aliquots of the standard were frozen and stored at −20 °C and at −70 °C or lyophilised and stored at room temperature in the dark. For a period of one year samples preserved with each of the three methods were restored every four or five weeks. They were amplified in the LightCycler™ and the crossing points (CP) were monitored. No significant trend in the raw CP values could be observed for any of the three storage methods. However, when the methods were compared to each other by calculating the CP ratios (−20 °C/−70 °C; −20 °C/lyophilised; −70 °C/lyophilised) at the 10 monitoring dates, the CP ratios −20 °C/−70 °C and −20 °C/lyophilised showed a highly significant positive trend (p&lt;0.0001) while the CP ratio −70 °C/lyophilised did not differ from the null hypothesis (p=0.53). It can be concluded that the latter two preservation methods are both appropriate, while storage at −20 °C is less advisable. Calculations based on the molecular weight of the standard and on the assumption of an average yield of three sporozoites per oocyst led to the conclusion that the target sequence is probably located on a double copy gene

scholarly journals Requirement of the C-terminal proline residue for stability of the Ca2+-activated photoprotein aequorin

1993 ◽  
Vol 293 (1) ◽  
pp. 181-185 ◽  
Author(s):  
N J Watkins ◽  
A K Campbell
Keyword(s):  
Light Emission ◽  
Specific Activity ◽  
In Vitro Transcription ◽  
Wild Type ◽  
Proline Residue ◽  
Long Term Stability ◽  
Recombinant Aequorin

cDNA coding for the Ca(2+)-activated photoprotein aequorin from the jellyfish Aequorea victoria has been engineered to investigate the role of the C-terminal proline residue in bioluminescence. Recombinant aequorin proteins were synthesized by PCR followed by in vitro transcription/translation, and characterized by specific activity, stability, and affinity for coelenterazine. The C-terminal proline residue of aequorin was shown to be essential for the long-term stability of the bound coelenterazine. Aequorin minus proline had only 1% of the specific activity of the wild-type after 2 h, and was virtually inactive after 18 h. The instability of this variant was further demonstrated by re-activating with a coelenterazine analogue (epsilon-coelenterazine), where maximum reactivation was reached in 15 min, and the luminescent activity was almost completely abolished within 3 h. Replacement of the C-terminal proline residue with histidine or glutamic acid decreased the specific activity to 10 and 19% of that of the wild-type respectively. However these variants were also unstable, having t1/2 values of 2.4 h and 2.3 h respectively. Enhancement of the Ca(2+)-independent light emission when proline was replaced by histidine confirmed the stabilizing role of the C-terminal proline. No significant effect of removal of the C-terminal proline was detected on the affinity for coelenterazine.

Constitutive TGF-β1 Deficiency Induces a Defect in Hematopoietic Stem/Progenitor Cell Compartment in Fetus and Neonate.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1397-1397
Author(s):  
Claude Capron ◽  
Catherine Lacout ◽  
Yann Lecluse ◽  
Valérie Jalbert ◽  
Elisabeth Cramer Bordé ◽  
...  
Keyword(s):  
Fetal Liver ◽  
Hematopoietic Cells ◽  
Type I ◽  
Activated T Cells ◽  
Hematopoietic Stem ◽  
Tgf Β1

Abstract TGF-β1 is a cytokine with pleiotropic effects. It has been considered that TGF-β1plays a major role on hematopoietic stem cells (HSC) based on in vitro experiment. Achieving in vivo experiments proved to be difficult because constitutive TGF-β1 knock-out (KO) in mice leads to lethality during the first 4 weeks of life from a wasting syndrome related to tissue infiltration by activated T cells and macrophages. For this reason, hematopoiesis of TGF-β1−/− mice has not been studied in details. In contrast the role of TGF-β1 has been recently extensively studied in conditional TGF-β type I receptor (TβRI) KO mice. No clear effect was observed on HSC functions, suggesting that TGF-β1 was not a key physiological regulator of hematopoiesis in the adult. However, these experiments have some limitations. They do not exclude a putative role for TGF-β1 during fetal hematopoiesis and they do not specifically address the role of TGF-β1 on hematopoiesis because KO of TGF-β receptor leads to signaling arrest for all TGF-βs. In addition, other receptors may be involved in TGF-β1 signaling. For these reasons, we have investigated the hematopoiesis of constitutive TGF-β1 KO mice with a mixed Sv129 × CF-1 genetic background allowing the birth of a high proportion of homozygotes. In 2 week-old neonate mice, we have shown a decrease of bone marrow (BM) and spleen progenitors and a decrease of immature progenitors colony forming unit of the spleen (CFU-s). Moreover this was associated with a loss in reconstitutive activity of TGF-β1−/− HSC from BM. However, although asymptomatic, these mice had an excess of activated lymphocytes and an augmentation of Sca-1 antigen on hematopoietic cells suggesting an excess of γ-interferon release. Thus we studied hematopoiesis of 7 to 10 days-old neonate mice, before phenotypic modification and inflammatory cytokine release. Similar results were observed with a decrease in the number of progenitors and in the proliferation of TGF-β1−/− BM cells along with an increased differentiation but without an augmentation in apoptosis. Moreoever, a loss of long term reconstitutive capacity of BM Lineage negative (Lin−) TGF-β1−/− cells along with a diminution of homing of TGF-β1−/− progenitors was found. These results demonstrate that TGF-β1 may play a major role on the HSC/Progenitor compartment in vivo and that this defect does not seem to be linked to the immune disease. To completely overpass the risk of the inflammatory syndrome, we analyzed hematopoiesis of fetal liver (FL) of TGF-β1−/− mice and still found a decrease in progenitors, a profound defect in the proliferative capacities, in long term reconstitutive activity and homing potential of primitive FL hematopoietic cells. Our results demonstrate that TGF-β1 plays an important role during hematopoietic embryonic development. Altogether these findings suggest that TGF-β1 is a potent positive regulator for the in vivo homeostasis of the HSC compartment.

Nontoxic Silicon Nanocrystals and Nanodiamonds as Substitution for Harmful Quantum Dots

2009 ◽  
Vol 1241 ◽  
Author(s):  
Anna Fucikova ◽  
Jan Valenta ◽  
Ivan Pelant ◽  
Vitezslav Brezina
Keyword(s):  
Quantum Dots ◽  
Chemical Composition ◽  
Silicon Nanocrystals ◽  
Nanocrystalline Silicon ◽  
Semiconductor Quantum Dots ◽  
In Vivo Studies ◽  
Long Term Stability

AbstractThe commercially available semiconductor quantum dots have been proven to be slightly to significantly toxic by recent publications depending on the chemical composition. We are developing new non-toxic fluorescent labels based on (i) nanocrystalline silicon, suitable for in vivo studies due to their biodegrability, and on (ii) nanodiamonds, intended mainly for in vitro use due to their long-term stability and nondegradilibity.

Unravelling some mysteries of porcine respiratory and reproductive syndrome virus (PRRSV) infections: new insights from modelling studies

2009 ◽  
Vol 2009 ◽  
pp. 30-30
Author(s):  
A Doeschl-Wilson ◽  
I Kyriazakis ◽  
L Galina-Pantoja
Keyword(s):  
Immune Response ◽  
Host Immune Response ◽  
Growing Pigs ◽  
Modelling Studies ◽  
Porcine Respiratory ◽  
Insight Into

Porcine reproductive and respiratory syndrome (PRRS) is an endemic pig disease in most European countries, causing respiratory distress, fever and growth reductions in growing pigs and increased litter mortality in sows. The disease is characterised by exceptionally long-term viral persistence within the host, a weak innate host immune response and delayed adaptive host immune response, and large between animal variation in the immune response (Murtaugh et al., 2004). Although numerous in-vitro and in-vivo studies produced valid insight into the fine details of the virus dynamics and its interaction with the host’s immune response, several fundamental questions concerning the role of diverse immune components and host genetics remain unanswered. In this study mathematical models were developed to investigate the role of diverse processes caused by the virus or the immune response on the infection characteristics.

scholarly journals Triggering DTH and CTL Activity by fd Filamentous Bacteriophages: Role of CD4+ T Cells in Memory Responses

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Giovanna Del Pozzo ◽  
Dina Mascolo ◽  
Rossella Sartorius ◽  
Alessandra Citro ◽  
Pasquale Barba ◽  
...  
Keyword(s):  
T Cells ◽  
Cd4 T Cells ◽  
Long Term Memory ◽  
Short Term ◽  
Filamentous Bacteriophages ◽  
Ctl Responses

The ability of fd bacteriophage particles to trigger different arms of the immune system has been previously shown by us with particular emphasis on the ability of phages to raise CTL responses in vitro and in vivo. Here we show that fd virions in the absence of adjuvants are able to evoke a DTH reaction mediated by antigen specific CD8+ T cells. In addition, we analyzed the induction of CTL responses in mice depleted of CD4+ T cells, and we observed that short-term secondary CTL responses were induced in the absence of CD4+ T cells while induction of long-term memory CTLs required the presence of CD4+ T lymphocytes. These results examine the cellular mechanism at the basis of fd efficiency and provide new elements to further validate the use of fd particles for eliciting and monitoring antigen-specific CTLs.

Effect of toremifene and ospemifene, compared to acolbifene, on estrogen-sensitive parameters in rat and human uterine tissues

2010 ◽  
Vol 1 (3) ◽  
Author(s):  
Fernand Labrie ◽  
Céline Martel ◽  
Sylvain Gauthier ◽  
Georges Pelletier ◽  
Jean-Yves Sancéau
Keyword(s):  
First Generation ◽  
Estrogenic Activity ◽  
Female Rats ◽  
Receptor Modulator ◽  
Ishikawa Cells ◽  
Estrogen Antagonist ◽  
Sensitive Parameters

Abstract: Although the first generation selective estrogen receptor modulator (SERM) tamoxifen (TAM) is well known for its uterotrophic activity, this study compares the stimulatory effect of the TAM derivatives toremifene (TORE) and ospemifene (OSPE) on estrogen-sensitive parameters in rat and human uterine tissues.: Ovariectomized female rats were treated daily orally for 10 days with 0.75 mg/rat of TORE, OSPE or acolbifene (ACOL, a pure estrogen antagonist in the uterus and mammary gland), which was used for comparison. Human endometrial carcinoma Ishikawa cells were incubated for 5 days with increasing doses of compounds, in the absence or presence of 1 nM estradiol (E: TORE and OSPE revealed 52% and 56% increases, respectively, in uterine weight, whereas ACOL had no effect. Similar effects were observed on vaginal weight. Endometrial epithelial height increased from 15.82±0.20 to 48.94± 2.12 and 42.14±1.95 μm with TORE and OSPE, respectively, whereas ACOL had no effect. Alkaline phosphatase activity, an estrogen-sensitive parameter in Ishikawa cells, was increased by 144% and 135% with OH-TORE and OH-OSPE, respectively. Owing to their intrinsic estrogenic activity, at maximal concentrations, OH-TORE and OH-OSPE blocked the stimulatory effect of E: The present in vitro and in vivo data show similar stimulatory effects of 4-hydroxytoremifene (OH-TORE) and OH-OSPE on estrogen-sensitive parameters. ACOL, a third generation SERM, has no effect on any of these parameters. Such data add to the potential uterine safety limitations of triphenylethylene-derived SERMs for long-term use in humans.

Robust oil-core nanocapsules with hyaluronate-based shells as promising nanovehicles for lipophilic compounds

Nanoscale ◽  
2017 ◽  
Vol 9 (47) ◽  
pp. 18867-18880 ◽  
Author(s):  
Joanna Szafraniec ◽  
Agnieszka Błażejczyk ◽  
Edyta Kus ◽  
Małgorzata Janik ◽  
Gabriela Zając ◽  
...  
Keyword(s):  
Lipophilic Compounds ◽  
Term Stability ◽  
Long Term Stability ◽  
Free Process

Biocompatible hyaluronate-based nanocapsules with liquid oil cores exhibiting long-term stability and tunable size were obtained in a versatile surfactant-free process and their biodistribution was studied in vivo and in vitro.

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