Properties of thiamin transport in isolated perfused hearts of chronically alcoholic guinea pigsThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet.

2008 ◽  
Vol 86 (4) ◽  
pp. 160-165 ◽  
Author(s):  
Milos M. Petrovic ◽  
Ljiljana Scepanovic ◽  
Gvozden Rosic ◽  
Dusan M. Mitrovic
Keyword(s):  
Cellular Uptake ◽  
Chronic Alcoholism ◽  
Metabolic Inhibitors ◽  
Dilution Method ◽  
Compensatory Mechanism ◽  
Thiamin Deficiency ◽  
Tracer Dilution ◽  
Energy Dependent ◽  
Perfused Hearts ◽  
Selection Of

The aim of this study was to determine the mechanism of transport of 14C-thiamin in the hearts of healthy (nonalcoholic) and chronically alcoholic guinea pigs. We used the single-pass, paired-tracer dilution method on isolated and retrogradely perfused guinea pig hearts. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of 14C-thiamin were determined under control conditions and under influence of possible modifiers. We tested how the presence of unlabeled thiamin, metabolic inhibitors, or absence of sodium ions influence the transport of 14C-thiamin. The results of our experiments show that the transport of 14C-thiamin is specific and energy-dependent and that its properties are significantly changed under the influence of chronic alcoholism. The latter effect occurs by increase in both Umax and Utot, as a manifestation of a compensatory mechanism in thiamin deficiency.

scholarly journals Nona-Arginine Facilitates Delivery of Quantum Dots into Cells via Multiple Pathways

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Yi Xu ◽  
Betty Revon Liu ◽  
Han-Jung Lee ◽  
Katie B. Shannon ◽  
Jeffrey G. Winiarz ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Cellular Uptake ◽  
Metabolic Inhibitors ◽  
Cellular Internalization ◽  
Caveolin 1 ◽  
Dependent Process ◽  
A Cell ◽  
Low Efficiency ◽  
Rnai Technique ◽  
Energy Dependent

Semiconductor quantum dots (QDs) have recently been used to deliver and monitor biomolecules, such as drugs and proteins. However, QDs alone have a low efficiency of transport across the plasma membrane. In order to increase the efficiency, we used synthetic nona-arginine (SR9), a cell-penetrating peptide, to facilitate uptake. We found that SR9 increased the cellular uptake of QDs in a noncovalent binding manner between QDs and SR9. Further, we investigated mechanisms of QD/SR9 cellular internalization. Low temperature and metabolic inhibitors markedly inhibited the uptake of QD/SR9, indicating that internalization is an energy-dependent process. Results from both the pathway inhibitors and the RNA interference (RNAi) technique suggest that cellular uptake of QD/SR9 is predominantly a lipid raft-dependent process mediated by macropinocytosis. However, involvement of clathrin and caveolin-1 proteins in transducing QD/SR9 across the membrane cannot be completely ruled out.

scholarly journals Evaluation of Commercial Disinfectants against Staphylococcus lentus and Micrococcus spp. of Poultry Origin

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Otun Saha ◽  
Nadira Naznin Rakhi ◽  
Arif Istiaq ◽  
Israt Islam ◽  
Munawar Sultana ◽  
...  
Keyword(s):  
Micrococcus Luteus ◽  
Bacterial Species ◽  
16S Rrna Gene Sequencing ◽  
Average Diameter ◽  
Diffusion Method ◽  
Dilution Method ◽  
Rrna Gene ◽  
Poultry Farms ◽  
Rrna Gene Sequencing ◽  
Selection Of

Introduction. Effective sanitation strategies for poultry farms require an appropriate selection of the disinfectant based on the contaminants present and their sensitivity to the disinfectants. Aim. The current study investigated the prevalence of streptococci/micrococci in poultry farms of Bangladesh and the efficacy of commercial disinfectants (Savlon, Lysol, Quatovet, Virkon S, and Virocid) along with alcohol against these pathogens to adopt appropriate strategies. Materials and Methods. Conventional approaches and the 16S rRNA gene sequencing were performed to confirm the isolates at the species level along with microtiter biofilm assay to determine their biofilm-forming ability. Efficacy of the disinfectants was tested against those isolates using agar well diffusion and minimum inhibitory concentration (MIC) test by broth dilution method using different dilutions of the disinfectants. Results. Staphylococcus lentus (n = 32), Micrococcus luteus (n = 7), and Micrococcus aloeverae (n = 4) were confirmed among 102 presumptively screened streptococci/micrococci isolates from 43 samples. No single disinfectant showed equally high efficacy against all three bacterial species in agar well diffusion test, although Virocid showed the lowest MIC against all three of them. Lysol was least effective among the commercial disinfectants by both MIC and diffusion method, although each commercial disinfectant was more effective than alcohol. Considering both the average diameter of the inhibition zones and the MIC values, efficacy can be interpreted as Virocid > Quatovet > Savlon > Virkon S > Lysol. Although the efficacy decreased with decreasing concentration, the disinfectants retained a satisfactory level of efficacy at 50% concentration. Among test pathogens, M. aloeverae was the most sensitive to the disinfectants and the weakest biofilm producers, whereas 4/14 S. lentus and 1/5 M. luteus were strong biofilm producers, which may cause more reduction in the efficacy in environmental conditions. Conclusion. As no ideal disinfectant was found in the study, the efficacy of the disinfectants should be routinely evaluated and validated to ensure the sanitation standards in the poultry sector.

scholarly journals Elucidating the mechanism of cellular uptake of fullerene nanoparticles

2021 ◽  
Vol 27 (2) ◽  
pp. 200658-0
Author(s):  
Yeonjeong Ha ◽  
Xianzhe Wang ◽  
Howard M. Liljestrand ◽  
Jennifer A. Maynard ◽  
Lynn E. Katz
Keyword(s):  
Active Transport ◽  
Cellular Uptake ◽  
Lipid Membranes ◽  
Culture Media ◽  
Passive Diffusion ◽  
Engineered Nanoparticles ◽  
Metabolic Inhibitors ◽  
Representative Cell ◽  
Fullerene Concentration ◽  
Microtubule Transport

Understanding the molecular interactions between biological cells and engineered nanoparticles is a key to evaluating potential toxicities to humans and the environment. This study developed a method to determine the mechanisms by which fullerene aggregates are distributed into a representative cell line, human intestinal Caco-2 cells. First, we determined that the presence of fetal bovine serum (FBS) in the cell culture media changes the particle characteristics and inhibits particle adsorptions onto cell surfaces. Second, significantly lower amounts of fullerene were internalized at 4°C, a temperature at which active transport mechanisms are effectively impeded, than at 37°C. Third, metabolic inhibitors of active transport and a microtubule transport inhibitor decreased fullerene uptake at 37°C. Fourth, cellular uptake of fullerene increased with increasing fullerene concentration, suggesting that passive diffusion into lipid membranes contributed to uptake over the broad concentration range used in this study. Together, these results indicate fullerene transport into cells occurs via two mechanisms: passive diffusion across the lipid bilayer and active transport including microtubule involved endocytosis. The results also suggest that simple physical-chemical partitioning models do not fully describe fullerene uptake, and instead, active transport models are also required to estimate the cellular uptake and toxicity of fullerene.

Effect of Prewetting Brines and Mixing on Ice-Melting Rate of Salt at Cold Temperatures: New Tracer Dilution Method

2017 ◽  
Vol 2613 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Scott Koefod
Keyword(s):  
Freezing Point ◽  
Melting Rate ◽  
Test Method ◽  
Dilution Method ◽  
Ice Melting ◽  
Cold Temperatures ◽  
Ice Melt ◽  
Solid Salt ◽  
Different Temperatures ◽  
Tracer Dilution

A novel test method has been developed to measure the ice-melting rate of deicers. The ice-melting rates of prewetted salt were determined by measuring the change in the concentration of chloride (Cl−) or magnesium or calcium cations (Mg2+ or Ca2+, respectively) in the ice melt as tracers. The method is substantially more precise than the SHRP H205.1 standard and has the further advantage of measuring ice-melting and salt dissolution rates simultaneously. Brines were preequilibrated with ice at −19.3°C (−2.7°F) and blended with solid salt to determine the effect of different prewetting brines on the ice-melting rate of the solid salt component only. The measured equilibrium ice-melting capacity of sodium chloride (NaCl) agreed well with the theoretical value calculated from the NaCl freezing point curve. Under a condition of no mixing, solid salt yielded 0.87% of its total available ice-melting capacity after 60 min when wetted with NaCl brine and 9.7% when wetted with calcium chloride (CaCl2) brine. Mixing raised the yield of ice melt to 27.1% and 50.5% after 60 min when wet with NaCl and CaCl2 brines, respectively. The CaCl2 brine was slightly more effective than the magnesium chloride (MgCl2) brine at enhancing the ice-melting rate of salt. The test method promises to be a useful tool for permitting a more precise optimization of prewetting brine composition, concentration, and brine-to-salt ratio at different temperatures. The method may also permit better determination of the cost-effectiveness of different prewetting strategies and provide deeper insights into the mechanism of chemical ice melting.

Vesicle Trafficking, Autophagy and Nanoparticles: A Brief Review

2020 ◽  
Vol 10 (1) ◽  
pp. 3-19
Author(s):  
Tianzhong Li ◽  
Mengsu Yang
Keyword(s):  
Clinical Trials ◽  
Signaling Pathways ◽  
Cellular Uptake ◽  
Vesicle Trafficking ◽  
Endocytic Pathway ◽  
Proton Sponge ◽  
Intracellular Release ◽  
Molecular Machinery ◽  
Delivery Vehicles ◽  
Selection Of

Background: Nanomedicine shows a huge promise for incurable diseases. So far, more than 50 nanoparticles have been approved by FDA and around 80 nanoformulations are currently in clinical trials. Nanoparticles possess several advantages over traditional drugs, including higher biocompatibility and bioavailability. One of the challenges for their wide application is insufficient understanding of the molecular network related to internalization of particles and intracellular release of cargos. Objective: This article aims to review the interactions between nanoparticles, vesicle transportation and autophagy pathways. The underlying molecular machinery is also discussed. Methods: For each step of the vesicle trafficking and autophagy, details of signaling pathways are described for a better understanding of the interactions between delivery vehicles and biomolecules within the cell. Conclusion: The selection of cellular uptake route mainly depends on physical characteristics of nanoparticles. For nanoparticles modified with ligands, they undergo receptormediated endocytic pathway. Once residing within the cells, cargos are released after disruption of endosomes, a mechanism called ‘proton sponge effect’. Besides, internalized nanoparticles either can be exocytosized, or they initiate the autophagy response, affecting the intracellular distribution of drugs.

Secretion of tetraethylammonium by proximal tubules of rabbit kidneys

1983 ◽  
Vol 245 (2) ◽  
pp. F238-F246 ◽  
Author(s):  
C. Schali ◽  
L. Schild ◽  
J. Overney ◽  
F. Roch-Ramel
Keyword(s):  
Membrane Permeability ◽  
Cellular Uptake ◽  
Incubation Medium ◽  
Proximal Tubules ◽  
Tissue Water ◽  
Secretory Rate ◽  
Luminal Membrane ◽  
Secretory Transport ◽  
Energy Dependent

The secretory transport of tetraethylammonium (TEA) was investigated in perfused and nonperfused isolated S1, S2, and S3 segments of proximal tubules from rabbit kidneys. In the perfused tubules the transepithelial net secretory flux and in nonperfused tubules the TEA cellular uptake were saturable (Km = 67 microM, Vmax = 2,480 fmol X min-1 X mm-1 in perfused S2 segments), energy dependent, and inhibited by mepiperphenidol. The net secretory flux of TEA (J b leads to j TEA) at a bath TEA concentration of 40 microM differed for the three segments and decreased in the order S1 greater than S2 greater than S3. The concentration of TEA in the perfusate leaving the tubule was approximately twice as great and the intracellular TEA concentration approximately 40 times as great as that in the bath. In nonperfused segments (40 microM TEA in the incubation medium) the TEA tissue water-to-medium ratio reached 100. In the three segments the ability to accumulate TEA across the peritubular membrane, thus, was similar, but the transepithelial secretory flux differed significantly. The differences in secretory rate between the three segments presumably result from differences in the luminal membrane permeability.

Uptake and asymmetric efflux of amino acids at maternal and fetal sides of placenta

1981 ◽  
Vol 241 (3) ◽  
pp. C106-C112 ◽  
Author(s):  
B. M. Eaton ◽  
D. L. Yudilevich
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Guinea Pig ◽  
Cellular Uptake ◽  
Transport Systems ◽  
Acid Transport ◽  
Dilution Technique ◽  
Acidic Amino Acids ◽  
Tracer Dilution ◽  
Paired Tracer Dilution

Unidirectional uptake of eighteen amino acids into the syncytiotrophoblast was measured from both the maternal and fetal circulations of isolated dually perfused guinea pig placentas using a single-circulation, paired-tracer dilution technique. A bolus containing a tritiated amino acid and L-[14C]glucose (extracellular marker) was injected intra-arterially into one circulation, and both venous outflows were sequentially sampled. The maximal cellular uptake (Umax) on the injection side was determined from (1-[3H]/[14C]) values and used to calculate the unidirectional influx. Umax values for neutral and basic amino acids ranged between 15 and 58% and were similar on both sides of the trophoblast. Uptake of the acidic amino acids and taurine was minimal. Amino acid influx from either circulation was followed by rapid tracer backflux and transplacental transfer. Tracer efflux was asymmetric and preferentially directed towards the fetal side. It is suggested that amino acid transport systems are present on both surfaces of the placenta and that net transfer from mother to fetus is the result of asymmetric efflux from the trophoblast.

Energy dependence of RNA degradation in rabbit reticulocytes

1984 ◽  
Vol 247 (5) ◽  
pp. C390-C395 ◽  
Author(s):  
E. A. Park ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Rna ◽  
Rna Degradation ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Atp Content ◽  
Bicarbonate Buffer ◽  
Ribosomal Subunits ◽  
Energy Dependent ◽  
Rabbit Reticulocytes

RNA degradation in rabbit reticulocytes was partially energy dependent. Reticulocytes were incubated for 10 h in Krebs-Henseleit bicarbonate buffer that was gassed with 95% O2-5% CO2 and contained glucose (30 mM) or 2-deoxyglucose (20 mM) and 2,4-dinitrophenol (0.2 mM). The rate of RNA degradation was reduced 41% in the presence of the metabolic inhibitors. When the buffer was gassed with 95% N2-5% CO2 and no substrate was added, the disappearance of RNA was decreased 55%. The cellular ATP content was depleted either by addition of the metabolic inhibitors or by incubation under anoxic conditions. ATP depletion did not modify the ratio of ribosomal subunits + monomers to polysomes. Puromycin and cycloheximide, which increased or decreased, respectively, the proportion of ribosomal RNA in subunits + monomers, blocked protein synthesis but did not alter the rate of RNA degradation. These experiments indicated that energy depletion inhibited RNA degradation by a mechanism that did not depend on the inhibition of protein synthesis. No evidence was obtained to indicate that the ratio of subunits + monomers to polysomes affected RNA degradation.

scholarly journals Cellular uptake of protic ruthenium complexes is influenced by pH dependent passive diffusion and energy dependent efflux

2020 ◽  
Vol 203 ◽  
pp. 110922
Author(s):  
Seungjo Park ◽  
Jessica L. Gray ◽  
Sarah D. Altman ◽  
Angela R. Hairston ◽  
Brianna T. Beswick ◽  
...  
Keyword(s):  
Cellular Uptake ◽  
Ruthenium Complexes ◽  
Passive Diffusion ◽  
Ph Dependent ◽  
Energy Dependent
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