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PubMed2005

Separation and characterization of antioxidants from Spirulina platensis microalga combining pressurized liquid extraction, TLC, and HPLC-DAD.

A new procedure has been developed to separate and characterize antioxidant compounds from Spirulina platensis microalga based on the combination of pressurized liquid extraction (PLE) and different chromatographic procedures, such as TLC, at preparative scale, and HPLC with a diode array detector (DAD). Different solvents were tested for PLE extraction of antioxidants from S. platensis microalga. An optimized PLE process using ethanol (generally recognized as safe, GRAS) as extraction solvent has been obtained that provides natural extracts with high yields and good antioxidant properties. TLC analysis of this ethanolic extract obtained at 115 degrees C for 15 min was carried out and the silica layer was stained with a DPPH (diphenyl-pycril-hydrazyl) radical solution to determine the antioxidant activity of different chromatographic bands. Next, these colored bands were collected for their subsequent analysis by HPLC-DAD, revealing that the compounds with the most important antioxidant activity present in Spirulina extracts were carotenoids, as well as phenolic compounds and degradation products of chlorophylls.

Antioxidants↗

PubMed2003

Fast proton spectroscopic imaging using steady-state free precession methods.

Various pulse sequences for fast proton spectroscopic imaging (SI) using the steady-state free precession (SSFP) condition are proposed. The sequences use either only the FID-like signal S(1), only the echo-like signal S(2), or both signals in separate but adjacent acquisition windows. As in SSFP imaging, S(1) and S(2) are separated by spoiler gradients. RF excitation is performed by slice-selective or chemical shift-selective pulses. The signals are detected in absence of a B(0) gradient. Spatial localization is achieved by phase-encoding gradients which are applied prior to and rewound after each signal acquisition. Measurements with 2D or 3D spatial resolution were performed at 4.7 T on phantoms and healthy rat brain in vivo allowing the detection of uncoupled and J-coupled spins. The main advantages of SSFP based SI are the short minimum total measurement time (T(min)) and the high signal-to-noise ratio per unit measurement time (SNR(t)). The methods are of particular interest at higher magnetic field strength B(0), as TR can be reduced with increasing B(0) leading to a reduced T(min) and an increased SNR(t). Drawbacks consist of the limited spectral resolution, particularly at lower B(0), and the dependence of the signal intensities on T(1) and T(2). Further improvements are discussed including optimized data processing and signal detection under oscillating B(0) gradients leading to a further reduction in T(min).

Animals↗

PubMed2003

Isolation and characterization of the plasma membrane biotin transporter from Schizosaccharomyces pombe.

The fission yeast Schizosaccharomyces pombe is auxotrophic for biotin (vitamin H) and growth depends on biotin uptake over the plasma membrane. Here a biotin transport mutant of Saccharomyces cerevisiae is used to identify the vht1(+) gene encoding the Schizosaccharomyces pombe plasma membrane transport protein for biotin. SpVht1p belongs to the family of allantoate transporters and has only little sequence homology to the S. cerevisiae biotin transporter. Although having dissimilar primary structures, the biotin transporters in Sz. pombe and S. cerevisiae share similar biochemical properties and regulation. Like in S. cerevisiae, biotin uptake in Sz. pombe is a high-affinity process, is optimal at acidic pH values and inhibited by protonophores, indicating that SpVht1p acts as a proton-biotin symporter. Desthiobiotin, the metabolic precursor of biotin, is also imported by SpVht1p. Deletion of vht1(+) abolishes growth on low external concentrations of the vitamin, showing that vht1(+) encodes the only protein that mediates biotin uptake in Sz. pombe. Expression of vht1(+) is maximal at low external biotin concentrations, indicating that Sz. pombe can adjust the rate of biotin uptake to meet the requirement for the vitamin.

Biotin↗

PubMed1998

Cell coupling in the retina: patterns and purpose.

Gap junction channels (electrical synapses) are a major component of the central nervous system mediating both electrical and metabolic coupling between neurons and glia. Their roles are as diverse as the cell types in which they are expressed and only some of these are reviewed here. In the adult the plastic nature of the gap junction channel allows for changes in the writing of the retinal circuitry that optimize visual processing to suit ambient lighting conditions. Gap junctional communication has been proposed to play a key role in embryonic development in general and in particular during the development of the retina where its roles may include control of neurogenesis, cell specification, synaptogenesis, and the synchronization of the spontaneous electrical activity required for the sharpening of central visual projections. Here we review gap junctional coupling within the retina and present data correlating gap junction expression with development events in the chick retina.

Animals↗

PubMed1999

Suppressive influences of methotrexate on the generation of CD14(+) monocyte-lineage cells from bone marrow of patients with rheumatoid arthritis.

An adequate supply of peripheral blood monocytes, granulocytes, and platelets is necessary for an optimal inflammatory process. We have previously demonstrated that the generation of CD14(+) monocyte lineage cells from the bone marrow is accelerated in patients with rheumatoid arthritis (RA). The current studies examined the influences of methotrexate (MTX), a potent disease modifying antirheumatic drug (DMARD), on the capacity of bone marrow progenitor cells to generate CD14(+) cells in patients with RA, in order to delineate its mechanism of action. CD14(-) cells purified from bone marrow specimens of 14 patients with active RA were cultured in the presence or the absence of pharmacologically attainable concentrations of MTX (0.2 microM). After incubation for 14 days, the cells were analyzed by flow cytometry for expression of CD14 and HLA-DR. The generation of CD14(+) cells from RA bone marrow CD14(-) progenitor cells was significantly suppressed by MTX. However, the expression of HLA-DR on bone marrow-derived CD14(+) cells was not significantly influenced by MTX. There was no significant difference in the effect of MTX on the generation of CD14(+) cells between patients with prednisolone and those without prednisolone. The production of IL-12 in bone marrow cell cultures was not inhibited, but was rather enhanced, by MTX, suggesting that the suppression of the generation of CD14(+) cells might not be due to the inhibition of cytokine production. The results are consistent with the hypothesis that one of the effects of DMARDs may involve the interference with monocyte differentiation in the bone marrow. Moreover, the data suggest that the generation of CD14(+) cells and the expression of HLA-DR on such marrow-derived CD14(+) cells are regulated by different mechanisms.

Adult↗

PubMed1997

Differential influences of gold sodium thiomalate and bucillamine on the generation of CD14+ monocyte-lineage cells from bone marrow of rheumatoid arthritis patients.

An adequate supply of peripheral blood monocytes, granulocytes, and platelets is necessary for an optimal inflammatory process. We have previously demonstrated that the generation of CD14(+) monocyte-lineage cells from the bone marrow is accelerated in patients with rheumatoid arthritis (RA). The current studies examined the influences of gold sodium thiomalate (GST) and bucillamine (BUC), two potent disease-modifying antirheumatic drugs (DMARDs), on the capacity of bone marrow progenitor cells to generate CD14(+) cells in patients with RA, in order to delineate their mechanisms of action. CD14(-) cells purified from bone marrow specimens of 13 patients with active RA who were not taking DMARDs were cultured in the presence or absence of pharmacologically attainable concentrations of GST (25 microM) or intramolecular disulfide form of bucillamine (BUC-ID, 3 microM), a major metabolite of BUC. After incubation for 14 days, the cells were analyzed by flow cytometry for expression of CD14, HLA-DR, and CD54. The generation of CD14(+) cells from RA bone marrow CD14(-) progenitor cells was significantly suppressed by GST, but not by BUC-ID. The expression of HLA-DR on the bone marrow-derived CD14(+) cells was also significantly inhibited by GST, but not by BUC-ID. Of note, neither GST nor BUC-ID influenced the expression of CD54 on the bone marrow-derived CD14(+) cells, indicating that the expression of HLA-DR and CD54 on the bone marrow-derived CD14(+) cells is regulated by different mechanisms. The results are consistent with the hypothesis that one of the effects of DMARDs may involve the interference with monocyte differentiation in the bone marrow. Moreover, the data emphasize that in contrast with BUC, GST is a potent inhibitor of monopoiesis in RA patients.

Adult↗

PubMed1995

Role of processing and intracellular transport for optimal toxicity of Shiga toxin and toxin mutants.

Cleavage of Shiga toxin A-fragment at a highly trypsin-sensitive site increases its enzymatic activity. To investigate the role of this cleavage site in intoxication of cells, we studied the routing, cleavage, and toxicity of mutant toxin where the trypsin-sensitive site had been eliminated. Ultrastructural analysis of toxin tagged with horseradish peroxidase demonstrated that wild-type and mutant toxins were transported from endosomes to the trans-Golgi network and further through the Golgi cisterns to the endoplasmic reticulum. Wild-type toxin was much more efficient than the mutants in provoking rapid intoxication, but after prolonged incubation time also mutants were highly toxic. The cells were able to cleave both wild-type Shiga toxin and the mutants, but the cellular location for cleavage appears to differ. Wild-type toxin was cleaved in the presence of brefeldin A, which disrupts the Golgi cisterns. This indicates that the cleavage occurs in the endosomes or in the trans-Golgi network. In contrast, the mutant Shiga-His (R248H/R251H) was not cleaved in the presence of brefeldin A, indicating that the cleavage can occur only after the toxin has left the trans-Golgi network. In vitro experiments showed that the cytosolic enzyme calpain is able to cleave Shiga-His, and results from in vivo experiments are consistent with the possibility that cleavage is carried out by calpain after the mutant A-fragment has reached the cytosol.

Amino Acid Sequence↗

PubMed2025

Identification of Plant Chromatin Interaction Networks Using IP-MS and co-IP.

Proteins often act in concert to perform their function. Thus, the identification of protein complexes is crucial if we want to understand how they work. In this chapter, we present a highly sensitive protocol for the immunoprecipitation of nuclear chromatin-linked proteins in Arabidopsis thaliana that does not rely on time-consuming nuclei extraction. Interaction partners are identified using mass spectrometry and confirmed by co-immunoprecipitation. To help solubilize chromatin-bound proteins and eliminate nonspecific interactions of proteins binding the same DNA stretch, we include an enzymatic digestion step to remove DNA before immunoprecipitation. Our protocol offers a simplified process using optimized buffers, which facilitates quick and effective immunoprecipitation. The outcome is high-quality eluates that are ideal for identifying proteins through MS.

Chromatin↗

PubMed1993

Cultivation of Escherichia coli to high cell densities in a dialysis reactor.

High cell density cultivation of Escherichia coli on a glycerol-based mineral medium was studied. The cultivation was done in a dialysis reactor composed of two chambers. The inner chamber is formed and separated from an outer chamber by a membrane. Fresh medium was continuously exchanged with medium in the outer chamber so that both glycerol and other components of the medium were supplied to the inner chamber through the membrane. Inhibitory substances diffused from the inner to the outer chamber and were subsequently removed with effluent from the outer chamber. Initially, mathematical models were used to describe the process. The optimal cultivation parameters, such as the initial glycerol concentrations in the two chambers, the desired transport rate across the membrane, glycerol concentration in the feed/dialysing medium, and the time to start the medium exchange, were determined from preliminary experiments and calculations. The actual cultivation results agreed very well with the model predictions. A very high cell concentration of 174 g dry weight/l was obtained. This cell concentration is within the range of the maximum theoretical concentration of E. coli in culture broth (160-200 g/l).

Cell Division↗

PubMed1995

Telemedicine protocols and standards: development and implementation.

Telemedicine is likely to adopt rather than create most of its protocols and standards as it becomes an integral part of medical practice. To optimize this process, it will be necessary to understand how to use existing protocols and standards, and influence the development, evaluation, and modification of new ones. We have identified key participants in standards setting activities under the titles of international government, United States government, professional certifying organizations, and independent institutes. We have reviewed their roles in establishing standards for identification of patients and providers, content and structure of patient records, terminology and codes of medical information and records, and transfer of messages and data. We have addressed requirements for storing and viewing images, the impact of image resolution on accuracy of clinical interpretation, the choice of communications protocols to satisfy transmission requirements, the need to link images and text data, and the evaluation of telemedicine systems.

Computer Communication Networks↗

PubMed2006

Use of the industrial yeast Candida utilis for cadmium sorption.

The sorption ability of Candida utilis biomass for cadmium ions with accumulating competence of dried cells and cells in alginate was compared. After an optimization of process conditions (pH 5.5, biomass concentration 1 g/L and c0 50 mg/L), the cadmium sorption capacity of dried yeast biomass was perceptibly higher than that of the other tested adsorbents. Considering the sorption of the dried yeast biomass equal to 100 %, the cells in alginate reached 86 % while native cells showed only 42 %.

Adsorption↗

PubMed2006

Drug targeting to lungs by way of microspheres.

In many conventional drug delivery systems in vogue, failure to deliver efficient drug delivery at the target site/organs; is evident as a result, less efficacious pharmacological response is elicited. Microspheres can be derived a remedial measure which can improve site-specific drug delivery to a considerable extent. As an application, Lung-targeting Ofloxacin-loaded gelatin microspheres (GLOME) were prepared by water in oil emulsion method. The Central Composite Design (CCD) was used to optimize the process of preparation, the appearance and size distribution were examined by scanning electron microscopy, the aspects such as in vitro release characteristics, stability, drug loading, loading efficiency, pharmacokinetics and tissue distribution in albino mice were studied. The experimental results showed that the microspheres in the range of 0.32-22 microm. The drug loading and loading efficiency were 61.05 and 91.55% respectively. The in vitro release profile of the microspheres matched the korsmeyer's peppas release pattern, and release at 1h was 42%, while for the original drug, ofloxacin under the same conditions 90.02% released in the first half an hour. After i.v. administration (15 min), the drug concentration of microspheres group in lung in albino mice was 1048 microg/g, while that of controlled group was 6.77 microg/g. GLOME found to release the drug to a maximum extent in the target tissue, lungs.

Animals↗

PubMed2005

The influence of assay error weight on gentamicin pharmacokinetics using the Bayesian and nonlinear least square regression analysis in appendicitis patients.

The purpose of this study was to determine the influence of weight with gentamicin assay error on the Bayesian and nonlinear least squares regression analysis in 12 Korean appendicitis patients. Gentamicin was administered intravenously over 0.5 h every 8 h. Three specimens were collected at 48 h after the first dose from all patients at the following times, just before regularly scheduled infusion, at 0.5 h and 2 h after the end of 0.5 h infusion. Serum gentamicin levels were analyzed by fluorescence polarization immunoassay technique with TDxFLx. The standard deviation (SD) of the assay over its working range had been determined at the serum gentamicin concentrations of 0, 2, 4, 8, 12, and 16 microg/mL in quadruplicate. The polynominal equation of gentamicin assay error was found to be SD (microg/mL) = 0.0246 - (0.0495C) + (0.00203C2). There were differences in the influence of weight with gentamicin assay error on pharmacokinetic parameters of gentamicin using the nonlinear least squares regression analysis but there were no differences on the Bayesian analysis. This polynominal equation can be used to improve the precision of fitting of pharmacokinetic models to optimize the process of model simulation both for population and for individualized pharmacokinetic models. The result would be improved dosage regimens and better, safer care of patients receiving gentamicin.

Anti-Bacterial Agents↗

PubMed2005

[An open wedge tibial head osteotomy using continuous callus distraction. An alternative method for the treatment of of varus arthrosis].

High tibial osteotomy is an accepted method for treatment of medial osteoarthritis. An alternative technique is an open-wedge osteotomy and consecutive callotasis (CO) using an external fixator. The purpose of this study was to evaluate the clinical and radiological results and the efficiency of this technique for precise correction. This prospective study included 41 patients (44 knees) evaluated by the HSS score, radiological stage of osteoarthritis, bone healing, and complications after a follow-up period of 49 (36-61) months. The HSS score increased from median 67 preoperatively to 82 points at the time of follow-up (p<0.001). Of 44 knees, excellent/good results were found in 70.5% and fair/poor in 29.5%. The median preoperative femorotibial anatomical angle was 3.6 degrees varus and 9.4 degrees valgus at the latest follow-up examination. The total time in external fixation was median 80 (61-125) days. We observed one early collapse of the new bone wedge, one complete corticotomy, and pin tract infections in ten cases. Furthermore, two hematomas required revision surgery. Hemicallotasis with external fixators allows constant manipulation of alignment during the healing process to optimize alignment. The disadvantage of the external fixation is the risk of pin track infection. Therefore, CO may constitute an important contribution to our algorithm in the treatment of varus gonarthrosis.

Adult↗

PubMed2004

Infective endocarditis in the intensive care unit: clinical spectrum and prognostic factors in 228 consecutive patients.

OBJECTIVE: To identify factors associated with in-hospital outcome of adult patients admitted to the ICU with infective endocarditis (IE). DESIGN AND SETTING: Retrospective study performed in the two medical ICUs of a teaching hospital. PATIENTS AND PARTICIPANTS: The charts of all 228 consecutive patients aged 18 years or older admitted with infective IE between January 1993 and December 2000 were reviewed. All patients satisfied the modified Duke's criteria for definite IE. MEASUREMENTS AND RESULTS: There were 146 episodes of native valve endocarditis and 82 of prosthetic valve endocarditis. Staphylococcus aureus was the predominant causative micro-organism. Most complications occurred early during the course of IE. One-half of the patients underwent cardiac surgery during the same hospitalization and had a better outcome than nonoperated patients. The overall in-hospital mortality rate was 45% (102/228). Multivariate analysis revealed the following clinical factors in patients with native valve IE as independently associated with outcome: septic shock (odds ratio 4.81), cerebral emboli (3.00), immunocompromised state (2.88), and cardiac surgery (0.475); in patients with prosthetic valve IE the factors were: septic shock (4.07), neurological complications (3.1), and immunocompromised state (3.46). CONCLUSIONS: IE still carries high morbidity and mortality rates for the subset of patients requiring ICU admission. Most complications occur early making the decision process for optimal medical and surgical management more difficult. Surgical treatment appears to improve in-hospital outcome.

Cardiac Surgical Procedures↗

PubMed2026

Plant-derived and microbial biostimulants in sustainable agriculture: mechanisms, applications, and challenges.

Plant biostimulants have emerged as transformative and sustainable tools for improving crop productivity, resource-use efficiency, and resilience under rapidly intensifying environmental stresses. Unlike conventional agrochemicals, biostimulants function by activating physiological, biochemical, and molecular processes that optimize plant performance without directly supplying nutrients or exerting pesticidal effects. This review comprehensively examines the integrated roles of plant-derived and microbial biostimulants in sustainable agriculture, with particular emphasis on microbial-mediated mechanisms underlying plant stress adaptation and rhizosphere functioning. Plant-derived biostimulants, including seaweed extracts, humic substances, protein hydrolysates, amino acids, and chitosan, enhance nutrient acquisition, root architecture, hormonal regulation, and antioxidant defense systems. More importantly, microbial biostimulants, such as plant growth-promoting rhizobacteria (PGPR), endophytic microorganisms, mycorrhizal fungi, actinomycetes, yeasts, and cyanobacteria, exert multifunctional effects through biological nitrogen fixation, mineral solubilization, phytohormone biosynthesis, volatile signaling, osmolyte accumulation, pathogen suppression, and modulation of stress-responsive genes. These beneficial microorganisms reshape rhizosphere microbial communities, improve nutrient cycling, and enhance plant tolerance to drought, salinity, heat, and heavy metal toxicity. Emerging evidence from genomics, transcriptomics, metabolomics, and microbiome-based investigations has further revealed the molecular networks and signaling pathways governing biostimulant-induced resilience and plant-microbe interactions. Despite their substantial promise, inconsistent field performance, formulation instability, regulatory limitations, and inadequate mechanistic understanding continue to restrict their large-scale adoption. This review highlights recent advances in microbial and plant-derived biostimulants while identifying critical knowledge gaps and future opportunities for precision biostimulant engineering, microbiome manipulation, and climate-resilient crop management. The integration of next generation biostimulant technologies into sustainable agricultural systems may significantly reduce dependence on agrochemicals while improving crop productivity, environmental sustainability, and global food security.

Agriculture↗

PubMed2003

Molecularly imprinted polymers for on-line clean up and preconcentration of chloramphenicol prior to its voltammetric determination.

The performance of a molecularly imprinted polymer (MIP) as a selective solid-phase extraction sorbent for the clean-up and preconcentration of the antibiotic chloramphenicol is described. The MIP was prepared using chloramphenicol as the template, (diethylamino)ethyl methacrylate as the functional monomer, and ethylene glycol dimethacrylate as the cross-linking monomer, and using tetrahydrofuran as the solvent. Detection of chloramphenicol was carried out by square-wave voltammetry at electrochemically activated carbon fiber microelectrodes. Chloramphenicol was eluted from the MIP microcolumn with methanol. Different experimental variables (sample pH, eluent volume, analyte and eluent flow rates and sample volume) associated with the rebinding/elution process were optimized. For a 250 mL sample, a nominal enrichment factor of 500 was attained, and for a chloramphenicol concentration of 3.0x10(-8) mol L(-1) (9.7 microg L(-1)) a recovery of 96+/-4% was obtained. A range of linearity for chloramphenicol between 3.0x10(-8) and 1.0x10(-5) mol L(-1) was obtained by loading 17 mL of analyte solutions of different concentration, eluting with 0.5 mL methanol, evaporating under a stream of nitrogen and dissolving the residue in phosphate buffer of pH 7.8. The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of chloramphenicol. The applicability of the MIP for both clean up and preconcentration was demonstrated by determining chloramphenicol in ophthalmic solutions and spiked milk at different concentration levels.

Animals↗

PubMed2003

Extracellular potassium alters frequency and profile of retinal spreading depression waves.

The phenomenon of spreading depression (SD) was observed in chicken retina by means of optical registration via a microscope and a CCD camera applying modern methods of image processing for optimized evaluation of the wave profiles. The propagation dynamics of SD waves was investigated as a function of extracellular potassium. Two main findings were obtained. Firstly, the frequency of spontaneous wave generation increased with the increase of K+ concentration. Secondly, there was an effect of potassium on the wave profile. In particular, the recovery zone of SD waves was shortened at increased K+. This effect was not only due to the dispersion relation of waves in excitable media as shown by the result of the mechanically induced wave trains. Applying the basic principles of chemical excitability for the interpretation of the data led us to the conclusion that these potassium effects are due to perturbations of an autocatalytic reaction to be further explored.

Animals↗