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At least 433 records · Page 24Linked to original sources
PubMed2026

In silico analysis of metal resistance genes in Pseudomonas extremaustralis 2E-UNGS: Genomic insights and safety assessment for wastewater biotreatment.

Pseudomonas extremaustralis 2E-UNGS is a non-pathogenic strain isolated from the polluted Reconquista River basin (Buenos Aires Metropolitan Area, Argentina), with a 20-year history of study focused on its survival strategies that have enabled its application in various processes such as waste biotreatment and biosensing. Regarding bacterial-metal interactions, P. extremaustralis 2E-UNGS is capable of biosorbing Cd(II), Zn(II), and Cu(II), and biotransforming Cr(VI) to Cr(III), facilitating both the removal of these metals from aqueous systems and their use in biosensor development. The complete circular chromosome (6,372,594 bp) has been annotated in the NCBI GenBank under accession number NZ_CP091043.1. The aim of this work was to perform an in-depth exploration of the P. extremaustralis 2E-UNGS genome to support the optimization of sustainable bioprocesses within the One Health framework. To this end, the integration of experimental evidence with a detailed in silico analysis of key genes involved in metal-microorganism interactions, antibiotic resistance, and their interconnections provides valuable insights for the optimization of future biotechnological applications. Considering its antibiotic resistance profile, together with the activation of efflux pumps induced by metal stimuli-particularly observed under Zn(II) exposure-P. extremaustralis 2E-UNGS can be regarded as suitable for the design of confined bioreactor processes, minimizing the risk of potential accidental environmental releases. Therefore, modulation of gene expression emerges as a promising approach to enhance the efficiency of metal-loaded wastewater biotreatments.

Pseudomonas↗
PubMed1988

Quantitative analysis of immunological reactions on silicon surfaces by multiple-angle Brewster angle reflectometry.

An optical biosensing instrument has been developed for the quantitative analysis of immunological reactions on biochemically sensitized surfaces. It is based on the measurement of reflectance changes of polarized laser light incident on high refractive index substrates at angles close to the pseudo-Brewster angle. Multiple-angle Brewster angle reflectometry (MABAR) has been used to investigate the binding of anti-human serum albumin (a-HSA) to human serum albumin (HSA) coated silicon surfaces. The concentration dependence and reaction kinetics of antibody-antigen complex formation have been studied using red and green He-Ne laser light. A significant increase in sensitivity has been observed with green light.

Antibodies↗
PubMed1995

Engineered fusion molecules at chelator lipid interfaces imaged by reflection interference contrast microscopy (RICM).

In molecular biology, biotechnology, and protein-engineering, the expression of histidine fusion proteins is a very powerful technique for the identification and one-step purification based on the interaction of the histidine stretch with immobilized metal complexes. By synthesis of a novel class of chelator lipids, this technique was combined with the concept of self-assembly leading to interfaces for immobilization and orientation of histidine-tagged biomolecules (Schmitt et al., 1994). Here, the chelator lipid layers were transferred onto solid substrate by vesicle fusion and Langmuir-Blodgett-techniques. Specific binding of a peptide containing an oligohistidine sequence to these functionalized interfaces was demonstrated by reflection interference contrast microscopy (RICM). Due to the phase separation behaviour of lipid mixtures, the chelator lipid interface could be further structured in two dimensions. Binding and organization of histidine-tagged molecules at these two-dimensional recognition arrays was imaged by RICM with a layer thickness resolution of 0.2 nm, and 0.5 microm laterally. Specific docking can be triggered by adding nickel ions and disrupted by EDTA. This concept opens up possibilities for reversible immobilization, enrichment and organization of histidine fusion proteins at interfaces and their application in biosensing.

Amino Acid Sequence↗
PubMed2005

SocA is a novel periplasmic binding protein for fructosyl amino acid.

Bacterial periplasmic proteins (bPBPs) undergo drastic conformational changes upon binding substrate, making them appealing as novel molecular recognition tools for biosensing. A putative bPBP-encoding gene, socA, belongs to the soc operon responsible for santhopine (fructosyl glutamine, FQ) catabolism of Agrobacterium tumefaciens. The socA gene was isolated and expressed in Escherichia coli as a soluble 28.8kDa periplasmic protein to investigate its properties as a potential bPBP for fructosyl amino acid (FA). The autofluorescence of SocA was used to monitor the protein's conformational change resulting from substrate binding. The fluorescence intensity changed upon binding FQ in a concentration dependent manner with a calculated K(d) of 2.1muM, but was unaffected by the presence of sugars or amino acid. Our results demonstrate that SocA is a novel FA bPBP that can be utilized as a novel molecular recognition element for the monitoring of FA.

Agrobacterium tumefaciens↗
PubMed2006

Assemblies of dendrimers and proteins on carbon and gold electrodes.

Dendritic macromolecules of two adjacent (G3.5 and G4) generations have been used to modify gold or carbon electrodes. The structure and stability of deposited films have been explored by quartz crystal microbalance (QCM), Surface Plasma Resonance (SPR) and electrochemistry. Dendrimers have been shown to adsorb spontaneously on electrode materials as compressed macromolecular films. They are able to inhibit (G3.5) or promote (G4) electroactive anionic species such as Fe(CN)(6)(3-/4-) used as a probe system. Mixed protein/dendrimer assemblies have been constructed with proteins differing in charge, nature of the prosthetic groups and sizes such as lysozyme, cytochrome c, polyhemic cytochrome c(3) or glucose oxidase. Generally, the stability of adsorbed films seems to be limited to one dendrimer/protein bilayer. Owing to the satisfactory stability of composite cytochrome c(3)/G3.5 or glucose oxidase/G4 films, biosensing applications are described for metal bioremediation and glucose detection, respectively.

Adsorption↗
PubMed2006

An AFM investigation of oligonucleotides anchored on unoxidized crystalline silicon surfaces.

Carboxylic terminated monolayers have been covalently attached on phosphorous doped crystalline (100) silicon surfaces using a cathodic electro grafting technique. The functionalization concentration and efficiency have been evaluated with different techniques. In particular, topographic images, performed with an atomic force microscope, were used to optimize the protocol in order to obtain a surface whose characteristics of uniformity and reproducibility are ideal for a bio-electronic device. Phase lag images of the functionalized surfaces were also performed, and show non-topographic structures that have been interpreted as areas of different molecule self-orientation. Poly-thymine oligonucleotides have been anchored on such a surface to form a nano-biosensing device capable to react selectively with a specific target molecule, a poly-adenine oligonucleotide. AFM images of high density (approximately 3x10(12) mol/cm2) single strand and double strand covered samples show toroidal shaped structures formed by the self-assembly of the oligonucleotides on the silicon surface.

Coated Materials, Biocompatible↗
PubMed2004

Electrochemical study of the XNA on Gold microarray.

A novel electrode array was developed based on the XNA on Gold trade mark microarray platform. The platform combines self-assembling monolayers, thick film patterning and streptavidin based immobilization to provide a robust, versatile platform capable of analysing virtually any biomolecule including nucleic acids, proteins, carbohydrates and lipids. Electrochemical analysis of the self-assembling monolayer/streptavidin (SAMS) XNA on Gold coating revealed that the ferrocene redox current for the SAMS modified electrode was greater than that with a bare Gold electrode. The electrochemical reaction of K4Fe(CN)6 was inhibited by the SAMS coating, but was reactivated upon addition of ferrocene. These results indicate that ferrocene is involved as a mediator in the electron transfer of K4Fe(CN)6 to the SAMS modified electrode. Addition of DNA to the SAMS resulted in only a minor change in the electrochemical signal, indicating that XNA on Gold can be used for electrochemical based bioanalysis. After cycling a SAMS electrode 50 times, no signs of deterioration were detected showing that coating has excellent stability. In addition to the biosensing applications, the scheme provides a non-invasive method for accessing the quality of the SAMS coatings which is of industrial interest. These studies show that the XNA on Gold microarray platform can be used for electrochemical studies, thus providing an additional alternative for developing multianalyte biosensors as well as expanding the range of detection methods available for microarray analysis.

DNA↗
PubMed2005

Development of a gas chromatography silicon-based microsystem in clinical diagnostics.

The accurate determination of biological parameters by means of rapid, on-line measurements at low-concentrations is an important task within the fields of pharmaceutical screening and medical diagnostic. Nevertheless, in biological samples, the analytes of interest are present as minor components in complex mixtures and with interfering species. Biosensors are the best candidates for these applications providing a direct solution to this need of accuracy, but their intrinsic selectivity often excludes all the other components in the sample. A separation step introduced prior to the sensing component could allow both the increase of selectivity with respect the interfering species and the identification of a large spectrum of molecular components in the sample. This work reports the development of a silicon-based integrated separation microsystem for gas chromatography aimed to biomedical applications, with particular emphasis to monitor the homovanillic acid (HVA) and vanillylmandelic acid (VMA) ratios in mass population screening for neuroblastoma diagnosis and prognosis. The miniaturised system consists of two main modules: (i) a metal oxide semiconductor detector and (ii) a micromachined separation capillary column. As first step, the metal oxide semiconductor capability to detect HVA and VMA has been demonstrated. Then, a technology for a silicon separation capillary microcolumn including the on-chip gas sensor housing has been proposed and a first prototype has been developed. The proposed microsystem is an analytical device with biosensing capabilities for diagnostic and biomedical applications, which yield an electronic signal proportional to the concentration of a specific analyte or group of analytes.

Biomarkers, Tumor↗
PubMed2006

Sensing capability of the localized surface plasmon resonance of gold nanorods.

We demonstrate the feasibility of using the longitudinal component of gold nanorod's surface plasmon resonance in biomolecular sensing. The sensitive dependence of the absorption maximum on the dielectric constant of the particle interfacial region makes gold nanorods a promise for constructing a biomolecular sensing scheme. The sensor containing gold nanorods, with a mean aspect ratio of 5.2, exhibits a sensitivity of ca. 366 nm/RIU (refractive index unit), which increases accordingly with the increase of the particle mean aspect ratios. Such a biosensor was further modified to demonstrate its effectiveness in quantitative detection for selective binding events, such as biotin/streptavidin pairs, through a process in which biotin molecules were chemically attached to the gold nanorods' surface prior to detection measurements. Results showed that the spectral lambda(max) shifts linearly to the concentrations of the streptavidin. The results from both experiment and model calculations strongly indicate the efficacy of the longitudinal surface plasmon absorption band in biosensing.

Biopolymers↗
PubMed2005

Enzyme association with lipidic Langmuir-Blodgett films: interests and applications in nanobioscience.

This review presents the recent advances in the achievement of organized proteo-lipidic nanostructures based on Langmuir-Blodgett technology and their potential applications in the nanobioscience area. By using the self-assembled properties of amphiphilic biomolecules at the air-water interface, the Langmuir-Blodgett (LB) technique offers the possibility to prepare ultrathin layers suitable for biomolecule immobilization at the molecular level. This review will provide a general overview of the enzyme association with preformed Langmuir-Blodgett films in connection with their potential applications in biosensing device developments, and then introduce the design of a new functionalised biomimetic nanostructure with oriented recognition site. The potential applications of such an organized proteo-lipidic nanostructure for biocatalysis investigations of an immobilised enzyme in a biomimetic situation and for the development of bioelectronic devices are finally discussed.

Enzymes↗
PubMed2005

Advances in synthetic biology: on the path from prototypes to applications.

Synthetic biology combines knowledge from various disciplines including molecular biology, engineering, mathematics and physics to design and build novel proteins, genetic circuits and metabolic networks. Early efforts aimed at altering the behavior of individual elements have now evolved to focus on the construction of complex networks in single-cell and multicellular systems. Recent achievements include the development of sophisticated non-native behaviors such as bi-stability, oscillations, proteins customized for biosensing, optimized drug synthesis and programmed spatial pattern formation. The de novo construction of such systems offers valuable quantitative insight into naturally occurring information processing activities. Furthermore, as the techniques for system design, synthesis and optimization mature, we will witness a rapid growth in the capabilities of synthetic systems with a wide-range of applications.

Gene Expression Regulation↗
PubMed2004

Recombinant Escherichia coli for the biomonitoring of benzene and its derivatives in the air.

For protection against environmental deterioration, pollutants should be reduced as much as possible. Therefore, a sensitive detection method for air pollutants is required, particularly for benzene, a compound with mutagenic, teratogenic, and carcinogenic properties. Some microorganisms have a number of enzymes that degrade organic compounds. The genetic information for many of these enzymes is codified in plasmids that usually comprise some elements such as proteins and RNA for their replication, and proteins for cell division control. Some plasmids have been obtained from Pseudomonas putida, a ubiquitous microorganism that is able to degrade biologic and inorganic compounds. P. putida contains the TOL plasmid, responsible for the degradation of benzene and its derivatives. The TOL plasmid has been fused with the gene for firefly luciferase (pTNS316 plasmid) to produce a luminescent bacterium (Escherichia coli HB101), which can be applied to the environmental monitoring of these chemicals. The recombinant E. coli transformed with the plasmid (E. coli HB101-pTNS316) was applied to the environmental biosensing of benzene and its derivatives. Measurement of bacteria-generated photons was done using a color-coded device to estimate quantitatively the pollutant concentration. The expression of luciferase was induced in the presence of aromatic compounds but the E. coli sensitivity has a detection limit: this bacterium dies if the benzene concentration is higher than 0.5 ppm and at this concentration the luminescence decreases so it is impossible to detect. Another limit for this biodevice is that the microorganism, very likely, accumulates the benzene and its derivatives, and therefore it is very important to consider the time of exposure. This biomonitor potentially offers a rapid, inexpensive, and sensitive technique for environmental detection of aromatic pollutant compounds.

Animals↗
PubMed2006

Percutaneous endocardial injection of erythropoietin: assessment of cardioprotection by electromechanical mapping.

BACKGROUND: Apart from its well-known stimulation of erythropoiesis, erythropoietin (EPO) exhibits angiogenic and anti-apoptotic effects. These cellular protective effects have also been described in experimental acute myocardial infarction models. We investigated the effects of EPO in a porcine model of chronic progressive myocardial ischaemia. METHODS: At weeks 2 and 6 after implantation of a circumflex ameroid constrictor, endocardial electromechanical NOGA system (Biosense Webster, Inc., California, USA) mapping of the left ventricle, coronary and ventricular angiography, as well as echocardiography were performed. Two weeks after ameroid placement, 13 pigs were randomized with 7 pigs receiving 10.000 U EPO and 6 pigs receiving placebo into the ischaemic region using a NOGA guided percutaneous transendocardial injection catheter, MYOSTAR. After 6 weeks, histology (Masson's Trichrome) was analyzed. RESULTS: Endocardial electromechanical mapping showed an increase of mean unipolar voltage (UV) amplitude in the ischaemic myocardial segments in the EPO-treated animals (8.5 mV pre and 10.6 mV post treatment) and a significantly reduced ischaemic surface area compared to the control group (19% vs. 41%) suggesting a decline in ischaemic injury. Echocardiography revealed 2,2 hypokinetic segments of the lateral wall in the EPO group vs. 3,3 in the control groups. The mean ejection fraction was 64% in the EPO group and 55% in the placebo group. Quantitative histological analysis of the ischaemic regions revealed a reduction of myocardial fibrosis (8% vs. 28%) in the EPO group. CONCLUSION: Endocardial EPO injection may induce cardioprotective effects in hibernating myocardium and may attenuate the progression of ischaemic tissue damage.

Animals↗
PubMed2005

Microfabricated drug delivery devices.

We review newest developments in the design and fabrication of drug delivery devices based on micropatterned structures. Electronic devices have now reached a stage of dimensions comparable to those of biological macromolecules. This raises exciting possibilities for combining microelectronics and biotechnology to develop new technologies with unprecedented power and versatility. While molecular electronics use the unique self-assembly, switching and dynamic capabilities of molecules to miniaturize electronic devices, nanoscale biosystems use the power of microelectronics to design ultrafast/ultrasmall biocompatible devices, including implants, that can revolutionize the field of bioengineering. Thus, in recent years we have seen an explosion in the field of novel microfabricated and nanofabricated devices for drug delivery. Such devices seek to develop a platform of well controlled functions in the micro- or nano-level. They include nanoparticulate systems, recognitive molecular systems, biosensing devices, and microfabricated and microelectronic devices.

Biocompatible Materials↗
PubMed2003

Catheter-based intramyocardial injection of autologous skeletal myoblasts as a primary treatment of ischemic heart failure: clinical experience with six-month follow-up.

OBJECTIVES: We report on the procedural and six-month results of the first percutaneous and stand-alone study on myocardial repair with autologous skeletal myoblasts. BACKGROUND: Preclinical studies have shown that skeletal myoblast transplantation to injured myocardium can partially restore left ventricular (LV) function. METHODS: In a pilot safety and feasibility study of five patients with symptomatic heart failure (HF) after an anterior wall infarction, autologous skeletal myoblasts were obtained from the quadriceps muscle and cultured in vitro for cell expansion. After a culturing process, 296 +/- 199 million cells were harvested (positive desmin staining 55 +/- 30%). With a NOGA-guided catheter system (Biosense-Webster, Waterloo, Belgium), 196 +/- 105 million cells were transendocardially injected into the infarcted area. Electrocardiographic and LV function assessment was done by Holter monitoring, LV angiography, nuclear radiography, dobutamine stress echocardiography, and magnetic resonance imaging (MRI). RESULTS: All cell transplantation procedures were uneventful, and no serious adverse events occurred during follow-up. One patient received an implantable cardioverter-defibrillator after transplantation because of asymptomatic runs of nonsustained ventricular tachycardia. Compared with baseline, the LV ejection fraction increased from 36 +/- 11% to 41 +/- 9% (3 months, p = 0.009) and 45 +/- 8% (6 months, p = 0.23). Regional wall analysis by MRI showed significantly increased wall thickening at the target areas and less wall thickening in remote areas (wall thickening at target areas vs. 3 months follow-up: 0.9 +/- 2.3 mm vs. 1.8 +/- 2.4 mm, p = 0.008). CONCLUSIONS: This pilot study is the first to demonstrate the potential and feasibility of percutaneous skeletal myoblast delivery as a stand-alone procedure for myocardial repair in patients with post-infarction HF. More data are needed to confirm its safety.

Aged↗
PubMed2004

Mode of initiation and ablation of ventricular fibrillation storms in patients with ischemic cardiomyopathy.

OBJECTIVES: We report on the initiation of ventricular fibrillation (VF) storm in patients with ischemic cardiomyopathy (ICM) and the results of targeted ablation to treat VF storm. BACKGROUND: Monomorphic premature ventricular contractions (PVCs) have been shown to initiate VF in patients without structural heart disease. METHODS: A total of 29 patients with ICM and documented VF initiation were identified. In 21 patients, VF storm was controlled with antiarrhythmic drugs and/or treatment of heart failure. Eight patients with VF (mean 52 +/- 25 episodes) refractory to medical management required ablation. All patients underwent three-dimensional electroanatomical mapping using CARTO (Biosense-Webster Inc., Diamond Bar, California), and PVCs were mapped when present. Scarred areas were identified using voltage mapping. RESULTS: Monomorphic PVCs initiated VF in all 29 identified patients. Five of eight patients requiring ablation had frequent PVCs that allowed PVC mapping. The earliest activation site was consistently located in the scar border zone. The PVCs were always preceded by a Purkinje-like potential (PLP). Ablation was successfully performed at these sites. In three patients, infrequent PVCs prevented mapping, but PLPs were recorded around the scar border. Ablation targeting these potentials along the scar border was successfully performed. During follow-up (10 +/- 6 months), one patient had a single VF episode and another developed sustained, monomorphic ventricular tachycardia. There was no recurrence of VF storm. CONCLUSIONS: Ventricular fibrillation in ICM is triggered by monomorphic PVCs originating from the scar border zone with preceding PLPs; targeting these PVCs may prevent VF recurrence. In the absence of PVCs, both substrate mapping and ablation appear to be equally effective.

Aged↗
PubMed2005

Electrogram characteristics in postinfarction ventricular tachycardia: effect of infarct age.

OBJECTIVES: The purpose of this study was to correlate infarct age with characteristics of the endocardial electrograms (EGM) obtained in patients undergoing mapping procedures for postinfarction ventricular tachycardia (VT). BACKGROUND: Experimental studies have demonstrated that infarct age influences EGM duration in the subepicardial left ventricle (LV). The relationship between infarct age and endocardial EGM characteristics has not been investigated in patients with postinfarction VT. METHODS: In a consecutive series of 23 patients with a history of remote infarction (range 1 to 31 years) and VT, endocardial LV mapping was performed with an electroanatomical mapping system (CARTO, Biosense Webster Inc., Diamond Bar, California) during sinus rhythm. Electrogram morphology and width were analyzed and correlated with infarct age. Isthmus sites of the VT re-entry circuits were identified by entrainment mapping and related to the results of substrate mapping. RESULTS: There was a significant correlation between infarct age and width of the bipolar endocardial EGM during baseline rhythm in the peri-infarct zone (r = 0.84; p < 0.0001). Increasing infarct age was associated with progressive activation delays in the scar and with isolated potentials separated by an isoelectric interval, the duration of which also correlated with infarct age (r = 0.77; p < 0.001). Among all endocardial sites, the VT isthmus sites displayed the most delay and broadest EGMs during sinus rhythm. CONCLUSIONS: The presence of broad, fractionated EGMs and isolated potentials indicates a healed myocardial infarction; the older the infarction, the broader the EGM width. Remodeling over time alters the electrophysiologic properties of the peri-infarct tissue.

Aged↗
PubMed2006

The effects of carbenoxolone on human myocardial conduction: a tool to investigate the role of gap junctional uncoupling in human arrhythmogenesis.

OBJECTIVES: This study assessed the effects of carbenoxolone on human myocardial conduction and refractoriness. BACKGROUND: Carbenoxolone, an antipeptic ulcer drug, has been shown to reduce gap junctional coupling without affecting cellular ion channels. Gap junctions (GJ) are considered to be determinants of cardiac action potential propagation. The effects of GJ uncoupling in the human heart are unknown. METHODS: Right atrial (RA) and ventricular (RV) activation mapping (Carto, Biosense Webster Inc., Diamond Bar, California) was performed during sinus rhythm. Right atrial and RV wavefront propagation velocity (WPV), specifically in the direction of propagation, was determined from these maps using a triangulation method. Refractoriness at multiple RA and RV sites, sinus rhythm cycle length, and AH, PR, QRS, and QT intervals were measured. The protocol was repeated 1 h after oral administration of 100 mg of carbenoxolone. RESULTS: In 11 patients, WPV was reduced from 79.6 +/- 13.3 cm/s to 57.2 +/- 9.1 cm/s (-27.1 +/- 12.8%, p < 0.001) in RA and from 98.7 +/- 19.8 cm/s to 76.5 +/- 21.7 cm/s (-22.7 +/- 14.1%, p < 0.01) in RV after carbenoxolone. Conduction slowing was more marked in 6 older patients with ischemic heart disease compared with younger subjects with normal hearts (RA -35.1 +/- 5.5% vs. -17.5 +/- 12.7%, p = 0.03; RV -33.8 +/- 5.1% vs. -9.3 +/- 7.7%, p < 0.001). Refractoriness and electrocardiogram parameters remained unchanged. CONCLUSIONS: Carbenoxolone causes a 27% reduction in human RA WPV and 23% in the RV without affecting refractoriness. The slowing of myocardial conduction by carbenoxolone demonstrates the significance of GJ in regulating human myocardial conduction and provides a tool for investigating the effects of GJ uncoupling on human arrhythmogenesis.

Action Potentials↗