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At least 829 records · Page 46Linked to original sources

PubMed2000

Myocardial efficiency in stunned myocardium. Comparison of Ca(2+)-sensitization and PDE III-inhibition on energy consumption.

OBJECTIVE: In stunned myocardium oxygen consumption is relatively high compared with the reduced ventricular function. On the other hand, inotropic stimulation is frequently required to improve postischemic ventricular dysfunction. However, inotropic agents which act via intracellular increased calcium result in a higher oxygen demand. Therefore Ca(2+)-sensitization might be a favorable alternative. METHODS: The effects of a novel Ca(2+)-sensitizer (EMD 60263, 10 microM, group 1) were compared with a phosphodiesterase (PDE) III-inhibitor (enoximon, 20 microM, group 2) on 14 isolated, blood-perfused rabbit hearts during reperfusion after a global ischemia of 20 min. Ventricular function, the pressure-volume area (PVA, a measure of total mechanical work), and total myocardial oxygen consumption (MVO(2)) were assessed. Contractile efficiency (EF(cont)), derived from the reciprocal of the slope of the MVO(2)-PVA relation, and external efficiency (EF(ex), stroke work/MVO(2)), were calculated. RESULTS: At matched heart rate (group 1: 141+/-10 min(-1) group 2: 151+/-28 min(-1)) and end-diastolic volume (1.3+/-0.2 ml) systolic variables were significantly decreased in stunned myocardium: LVP(max) to 57+/-13% of control value in group 1 and to 76+/-7% in group 2, aortic flow to 20+/-4 vs. 25+/-8%. PVA was decreased to 57+/-13 and 67+/-11%, MVO(2) was non-significantly decreased to 73+/-22 and 88+/-14%. After administration of either inotropic agent LVP(max) was significantly improved to 96+/-12 vs. 90+/-8% compared with preischemic levels, aortic flow to 103+/-24 vs. 88+/-9%, and PVA 99+/-11 vs. 89+/-16%, respectively. EMD 60263 increased MVO(2) to control levels (107+/-9%), and enoximon raised MVO(2) even more significantly above control (139+/-13%). Both myocardial efficiency indices were significantly diminished during reperfusion: EF(ex) to 14+/-9 vs. 23+/-7% and EF(cont) to 71+/-7 vs. 65+/-9% compared with preischemic levels. EF(ex) (109+/-21%) was significantly, but EF(cont) only slightly (84+/-11%) increased after administration of EMD 60263, whereas EF(ex) (57+/-13%) and EF(cont) (71+/-12%) remained depressed after enoximon. CONCLUSIONS: In stunned myocardium, the decreased efficiency indices show that energy utilization is disturbed. Both agents recruited an inotropic reserve, whereas Ca(2+)-sensitization seemed to be more favorable in terms of myocardial efficiency indices. These results indicate that alteration of myocardial calcium sensitivity contributes a major part to postischemic dysfunction. Therefore, Ca(2+)-sensitization may potentially be a superior method for inotropic support in the postischemic heart.

Animals↗

PubMed1998

Enhancement of the efficiency of photodynamic therapy of tumours by t-butyl-4-hydroxyanisole.

The effects of photodynamic therapy (PDT) alone and in combination with 3(2)-t-butyl-4-hydroxyanisole (BHA) on Ehrlich ascites carcinoma (EAC) cells have been investigated. BHA, a widely used food antioxidant, administered to the cells prior to light exposure is found to cause concentration-dependent alterations of the haematoporphyrin derivative (HpD)-based PDT. BHA (0.15 mM) causes a small (about 10%) inhibition in the rate of HpD-photosensitized injury of EAC cells. In contrast, upon increasing the concentration of BHA from 0.15 to 0.5 mM, a 1.3-fold enhancement in HpD-PDT efficiency is achieved. The cytotoxic effect on the cells treated with HpD-PDT and a higher concentration of BHA (0.5 mM) is additive. When BHA (0.5 mM) is given immediately after HpD-PDT, the combination is found to be three to four times more effective than when BHA is added to EAC cells before phototherapy. In this treatment regimen BHA acts synergistically with HpD-PDT. Such a difference in the action of BHA on the efficiency of HpD-PDT might be explained by the ability of BHA to inhibit the HpD-photosensitized destruction of some biomolecules. An enhancing action of BHA on the intensity of HpD-photosensitized death of tumour cells is also observed in vivo. Even a single dose of BHA (0.6 mM kg-1, 15 min after irradiation) causes (in an additive manner) an approximately two-fold increase in the efficiency of HpD-PDT of mice bearing Ehrlich ascites tumour (intraperitoneal transplantation). The results obtained indicate that the potentiating effect of BHA on the HpD-PDT could be caused by the impairment of the mitochondrial respiration, since there is a good correspondence between the concentration of BHA that increases the efficiency of PDT and the concentration that inhibits the oxygen consumption and dehydrogenase activity of EAC cells. The influence of BHA on the efficiency of PDT does not depend on the nature of the photosensitizer used; the effects with chlorin-e6 trimethyl ester are similar to that seen for HpD.

Animals↗

PubMed2000

TLD efficiency of 7LiF for doses deposited by high-LET particles.

The efficiency of 7 LiF TLDs (TLD-700) in registering dose from high-LET (> or = 10 keV/micrometers) charged particles (relative to 137Cs gamma rays) has been measured for a number of accelerated heavy ions at various particle accelerator facilities. These measured efficiency values have been compared with similar results obtained from the open literature and a dose efficiency function has been fitted to the combined data set. While it was found that the dose efficiency is not only a function of LET, but also of the charge of the incident particle, the fitted function can be used to correct the undermeasured value of dose from exposures made in mixed radiation fields where LET information is available. This LET-dependent dose efficiency function is used in our laboratory in determining total absorbed dose and dose equivalent from combined TLD and CR-39 plastic nuclear track detector measurements.

Calibration↗

PubMed1999

Integrase-mediated nonviral gene transfection with enhanced integration efficiency.

Retroviruses efficiently integrate their genome into the host chromosome. Two elements of the retrovirus genome are needed for the integration: long terminal repeats (LTRs) and integrase protein. We attempted to incorporate the retrovirus integration machinery in lipid vesicle-mediated gene transfection with the aim of achieving efficient stable transfection in a nonviral gene transfection system. A DNA fragment, in which a neomycin-resistant gene was flanked between partial LTR sequences derived from the Rous sarcoma virus (RSV), was constructed. This DNA fragment was transfected together with purified recombinant RSV integrase or integrase expression vectors by means of lipid vesicle-mediated gene transfection. The integrase-mediated transfection enhanced the stable transfection efficiency. The length and the end structure of the LTR sequences were important in achieving high efficiency. Under optimal conditions, the stable transfection efficiency showed a 16-fold improvement over that without integrase.

Journal Article↗

PubMed2003

Identification of human plasma proteins that bind to cationic lipid/DNA complex and analysis of their effects on transfection efficiency: implications for intravenous gene transfer.

Interaction of cationic lipid/DNA complex with the plasma is a limiting step for the cationic lipid-mediated intravenous gene transfer and expression process. Most of the plasma components that interact with the complex and inhibit its transfection efficiency are still unknown. In the present work, human plasma proteins and lipoproteins that bind to a cationic lipid/DNA complex were isolated on a sucrose density gradient and identified by 2-D gel electrophoresis. Protein binding did not result in complex dissociation or DNA degradation. The effects of several complex-binding plasma components on the transfection efficiency were studied using lung endothelial cells cultured in vitro. Lipoprotein particles caused a drastic loss of the transfection efficiency of the complex. Surprisingly, fibrinogen was found to activate the transfection process. The roles of these complex-binding plasma components on the complex uptake efficiency were quantitatively assessed using radiolabeled plasmid DNA and qualitatively evaluated using fluorescence microscopy. A good correlation was found between the effects of the complex-binding plasma components on the transfection and on cell uptake efficiencies. In contrast to what was generally believed, our data suggest that disruption of the complex does not occur when it is in contact with the plasma and therefore could not be responsible for the loss of transfection activity. Instead, coating of complexes with plasma components seems to be responsible for reduced uptake by cells, which in turn results in reduced transfection.

Amidines↗

PubMed2005

Processing efficiency and sustained attention in bipolar disorder.

We hypothesized that patterns of sustained attention performance in bipolar disorder were consistent with processing efficiency theory--a theory of the relationship between central processing capacity and performance. We predicted (1) sustained attention deficits during mania because symptoms interfere with limited-capacity executive control processes resulting in decreased performance effectiveness; and (2) decreased processing efficiency during euthymia, as indicated by speed/accuracy tradeoffs, consistent with a stable phenotypic abnormality. Twenty-five manic bipolar, 23 euthymic bipolar, and 28 healthy comparison participants were compared on a continuous performance task and administered symptom-rating scales. The manic group was significantly impaired on overall perceptual sensitivity and demonstrated a significant linear decrease in performance over time, consistent with impaired sustained attention. The euthymic group evidenced significantly slower overall hit reaction time (RT), but when RT was controlled they performed similarly to the healthy group over time. Two discriminant functions combined to separate the groups on manic symptom severity and on-task effort/strategy use. These findings are consistent with processing efficiency theory. They suggest that euthymic patients sustain attention through effortful control at the expense of processing efficiency, while acute mania reduces the capacity for control and impairs sustained attention. Problems with processing efficiency are viewed as trait characteristics of bipolar disorder that may be overlooked by traditional error-based assessments.

Adult↗

PubMed2001

High-throughput proteomics using high-efficiency multiple-capillary liquid chromatography with on-line high-performance ESI FTICR mass spectrometry.

We report on the design and application of a high-efficiency multiple-capillary liquid chromatography (LC) system for high-throughput proteome analysis. The multiple-capillary LC system using commercial LC pumps was operated at a pressure of 10,000 psi to deliver mobile phases through a novel passive feedback valve arrangement that permitted mobile-phase flow path switching and efficient sample introduction. The multiple-capillary LC system uses several serially connected dual-capillary column devices. The dual-capillary column approach eliminates the time delays for column regeneration (or equilibration) since one capillary column was used for a separation while the other was being washed. Several serially connected dual-capillary columns and electrospray ionization (ESI) sources were operated independently and can be used either for "backup" operation or for parallel operation with other mass spectrometers. This high-efficiency multiple-capillary LC system utilizes switching valves for all operations, enabling automated operation. The separation efficiency of the dual-capillary column arrangement, optimal capillary dimensions (column length and packed particle size), capillary regeneration conditions, and mobile-phase compositions and their compatibility with electrospray ionization were investigated. A high magnetic field (11.4 T) Fourier transform ion cyclotron resonance (FTICR) mass spectrometer was coupled on-line with this high-efficiency multiple-capillary LC system using an ESI interface. The capillary LC provided a peak capacity of approximately 650, and the 2-D capillary LC-FTICR analysis provided a combined resolving power of > 6 x 10(7) components. For yeast cytosolic tryptic digests > 100,000 polypeptides were detected, and approximately 1,000 proteins could be characterized from a single capillary LC-FTICR analysis using the high mass measurement accuracy (approximately 1 ppm) of FTICR, and likely more if LC retention time information were also exploited for peptide identification.

Chromatography, Liquid↗

PubMed1996

Matrix-assisted laser desorption ion trap mass spectrometry: efficient trapping and ejection of ions.

The present paper explores the coupling of a matrix-assisted laser desorption/ionization (MALDI) ion source with an ion trap mass analyzer, with particular emphasis on the development of methods for improving the efficiency of ion trapping and ejection. A technique is described for directly measuring, for the first time, the trapping efficiency of peptide ions produced in a remote external MALDI ion source. The technique was used to devise an improved scheme for trapping, which yielded efficiencies as high as 39%. An improved understanding of the resonant ejection process led us to a new resonant ejection parameter set that increased the ejection efficiency by 1 order of magnitude over more conventionally used parameter sets and allowed for marked improvements in the mass resolution of ions with m/z > 2500. The presently described improvements in the efficiencies of ion trapping and ejection together with improved methods for isolating and fragmenting ions (Qin, J.; Chait, B.T.Anal. Chem., following article in this tissue) lay the foundation for highly sensitive MALDI ion trap mass spectrometry of proteins (Qin, J.; et al. Anal. Chem. 1996, 68, 1784-1791).

Amino Acid Sequence↗

PubMed2000

Modifier effects on column efficiency in packed-column supercritical fluid chromatography

We investigate the effects on column efficiency of methanol, acetonitrile, ethanol, and 1-propanol used as modifiers in packed-column SFC. C-18, phenyl, and cyano columns were used with both nonpolar and polar solutes. For highly retained nonpolar solutes, addition of modifier significantly increased apparent column efficiency, especially for the C-18 column. For polar solutes, the presence of modifier dramatically improved retention and efficiency with an apparent efficiency dependence on modifier type and amount. Temperature and pressure effects on efficiency were also studied.

Journal Article↗

PubMedDate not supplied

A degradable polyethylenimine derivative with low toxicity for highly efficient gene delivery.

Routine clinical implementation of human gene therapy awaits safe and efficient gene delivery methods. Polymeric vectors hold promise due to the availability of diverse chemistries, potentially providing targeting, low immunogenicity, nontoxicity, and robustness, but lack sufficient gene delivery efficiency. We have synthesized a versatile group of degradable polycations, through addition of 800-Da polyethylenimine (PEI) to small diacrylate cross-linkers. The degradable polymers reported here are similar in structure, size (14-30 kDa), and DNA-binding properties to commercially available 25-kDa PEI, but mediate gene expression two- to 16-fold more efficiently and are essentially nontoxic. These easily synthesized polymers are some of the most efficient polymeric vectors reported to date and provide a versatile platform for investigation of the effects of polymer structure and degradation rate on gene delivery efficiency.

Cell Line, Tumor↗

PubMed2000

Efficient translesion replication past oxaliplatin and cisplatin GpG adducts by human DNA polymerase eta.

Platinum anticancer agents form bulky DNA adducts which are thought to exert their cytotoxic effect by blocking DNA replication. Translesion synthesis, one of the pathways of postreplication repair, is thought to account for some resistance to DNA damage and much of the mutagenicity of bulky DNA adducts in dividing cells. Oxaliplatin has been shown to be effective in cisplatin-resistant cell lines and less mutagenic than cisplatin in the Ames assay. We have shown that the eukaryotic DNA polymerases yeast pol zeta, human pol beta, and human pol gamma bypass oxaliplatin-GG adducts more efficiently than cisplatin-GG adducts. Human pol eta, a product of the XPV gene, has been shown to catalyze efficient translesion synthesis past cis, syn-cyclobutane pyrimidine dimers. In the present study we compared translesion synthesis past different Pt-GG adducts by human pol eta. Our data show that, similar to other eukaryotic DNA polymerases, pol eta bypasses oxaliplatin-GG adducts more efficiently than cisplatin-GG adducts. However, pol eta-catalyzed translesion replication past Pt-DNA adducts was more efficient and less accurate than that seen for previously tested polymerases. We show that the efficiency and fidelity of translesion replication past Pt-DNA adducts appear to be determined by both the structure of the adduct and the DNA polymerase active site.

Base Sequence↗

PubMed1994

Efficiency of ATP hydrolysis and DNA unwinding by the RecBC enzyme from Escherichia coli.

We have measured the rates and efficiencies of DNA unwinding (the number of ATP molecules hydrolyzed per DNA base pair unwound) catalyzed by the RecBC,RecBCD-K177Q (a site-directed mutant in the putative ATP-binding site in the RecD subunit), and RecBCD enzymes from Escherichia coli. The DNA unwinding rate was measured with a coupled assay in which unwound DNA is degraded by the combined action of the RecJ enzyme and exonuclease I. The rates of DNA unwinding by the RecBC and RecBCD-K177Q enzymes are reduced by about 4-fold compared to the case of the RecBCD enzyme. The efficiency of ATP hydrolysis was determined in two ways. First, it was calculated from the ratio of the ATP hydrolysis rate to the rate of DNA unwinding. In the second method, ATP hydrolysis was measured under conditions where all of the DNA substrate becomes completely unwound. The efficiency is the ratio of the total amount of ATP hydrolyzed to the amount of DNA substrate present in the reaction. The average efficiencies measured kinetically and by the complete unwinding experiment are as follows: 2.30 and 1.74 ATP/base pair (RecBCD enzyme); 1.44 and 1.28 (RecBC); and 1.20 and 1.07 (RecBCD-K177Q). The RecBC and RecBCD-K177Q enzymes are therefore able to couple ATP hydrolysis to DNA unwinding at least as efficiently as the RecBCD holoenzyme. The lower ATP per base pair ratios found for RecBC and RecBCD-K177Q indicate that the RecD subunit hydrolyzes ATP during DNA unwinding by the RecBCD enzyme.

Adenosine Triphosphate↗

PubMed1989

Highly efficient DNA delivery mediated by pH-sensitive immunoliposomes.

We have previously shown that pH-sensitive immunoliposomes can mediate a target-specific delivery of plasmid DNA to tumor cells grown in a mouse model [Wang, C.-Y., & Huang, L. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 7851-7855]. The efficiency of delivery in terms of the target cell transformation frequency has now been characterized for both short- and long-term gene expression in a tissue culture system. Herpes simplex virus thymidine kinase (TK) gene was used as a reporter gene. It was placed under the control of the promoter for the rat phosphoenolpyruvate carboxykinase gene, which contains a cAMP regulatory element. Therefore, the expression of the exogenous gene in the target cell, mouse Ltk- cells, can be regulated by cAMP drugs. The plasmid DNA was encapsulated in liposomes using a detergent dialysis method. The efficiency of gene delivery was optimized with respect to the time course and dose of liposome-associated DNA. The existence of antibody of the liposomes was essential for the maximal level of DNA delivery. Delivery was also dependent on the lipid composition of the liposome. The pH-sensitive lipid composition gave 8-fold higher efficiency than the corresponding pH-insensitive composition. The transformation efficiency of the target cell also depended on the regulation of gene expression; cells incubated with dibutyryl-cAMP and theophylline showed a much higher level of transformation frequency than cells incubated without the drugs. When all liposome and incubation parameters are optimized, the Ltk- cells showed a 47% efficiency for the short-term transformation, and 2% for the long-term transformation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1997

Replication of M13 single-stranded viral DNA bearing single site-specific adducts by escherichia coli cell extracts: differential efficiency of translesion DNA synthesis for SOS-dependent and SOS-independent lesions.

In order to characterize mutagenic translesion DNA synthesis in UVM-induced Escherichia coli, we have developed a high-resolution DNA replication system based on E. coli cell extracts and M13 genomic DNA templates bearing mutagenic lesions. The assay is based on the conversion of M13 viral single-stranded DNA (ssDNA) bearing a single site-specific DNA lesion to the double-stranded replicative form (RF) DNA, and permits one to quantitatively measure the efficiency of translesion synthesis. Our data indicate that DNA replication is most strongly inhibited by an abasic site, a classic SOS-dependent noninstructive lesion. In contrast, the efficiency of translesion synthesis across SOS-independent lesions such as O6-methylguanine and DNA uracil is around 90%, very close to the values obtained for control DNA templates. The efficiency of translesion synthesis across 3,N4-ethenocytosine and 1, N6-ethenoadenine is around 20%, a value that is similar to the in vivo efficiency deduced from the effect of the lesions on the survival of transfected M13 ssDNA. Neither DNA polymerase I nor polymerase II appears to be required for the observed translesion DNA synthesis because essentially similar results are obtained with extracts from polA- or polB-defective cells. The close parallels in the efficiency of translesion DNA synthesis in vitro and in vivo for the five site-specific lesions included in this study suggest that the assay may be suitable for modeling mutagenesis in an accessible in vitro environment.

Bacteriophage M13↗

PubMedDate not supplied

Experimental collision efficiencies of polymer-flocculated animal cells.

The determination of particle collision kinetics is useful to decouple the effects of process parameters on individual events in flocculation. This paper discusses the effects of flocculation conditions on the collision efficiency of ATCC strain CRL 1606 hybridomas flocculated with poly-L-histidine. Experimental determinations of the collision efficiency of cells in Couette flow are presented over a range of experimental conditions. The collision efficiency correlates with the cell zeta potential to the -2.4 power at high surface coverage, consistent with literature results in latex systems. At low coverage, accounting for the distribution of polymer on the cells corrects for deviation from the high-coverage behavior. Collision is dependent on the hydrodynamic environment as well. At high surface coverage, collision efficiency is weakly dependent on hydrodynamic conditions and follows a dependency on the shear rate and viscosity to the -0.32 power. This is consistent with ionic coagulation theory. At low surface coverage, the collision efficiency is strongly dependent on the viscous fluid forces. The results versus both dose and shear rate over the entire range of surface coverages are consistent with weak intercell bonding. Collision kinetics in the presence of high molecular weight dextrans show steric hindrance to cell collision.

Animals↗

PubMedDate not supplied

High efficiencies of gene transfer with immobilized recombinant retrovirus: kinetics and optimization.

We used a combination of mathematical modeling and experiments to investigate the rate-limiting steps of retroviral transduction on surface-bound fibronectin (FN) and identify the conditions that maximize the efficiency of gene transfer. Our results show that fibronectin-assisted gene transfer (FAGT) is a strong function of the time and temperature of virus incubation in FN-coated plates. Gene transfer increases sharply at short times, reaches a maximum at intermediate times, and eventually declines as a result of loss of retroviral activity. The maximum transduction efficiency and the time at which this is attained increase with decreasing temperature of virus incubation. Depending on the temperature and the type of target cells, the initial rate of gene transfer increases by 3- to 10-fold and the maximum transduction efficiency increases by 2- to 4-fold as compared to traditional transduction (TT). Interestingly, Polybrene (PB) inhibits FAGT in a dose-dependent manner by inhibiting binding of retrovirus to FN. In contrast to traditional transduction, FAGT yields higher than 10-fold transduction efficiencies with concentrated retrovirus stocks. Gene transfer is directly proportional to the concentration of the virus-containing medium with no sign of saturation for the range of concentrations tested. These results suggest that immobilization of recombinant retrovirus can be rationally optimized to yield high efficiency of gene transfer to primary cells and improve the prospect of gene therapy for the treatment of human disease.

Animals↗

PubMedDate not supplied

Determination of size distribution and encapsulation efficiency of liposome-encapsulated hemoglobin blood substitutes using asymmetric flow field-flow fractionation coupled with multi-angle static light scattering.

In this study, we investigated the size distribution, encapsulation efficiency, and oxygen affinity of liposome-encapsulated tetrameric hemoglobin (LEHb) dispersions and correlated the data with the variation in extruder membrane pore size, ionic strength of the extrusion buffer, and hemoglobin (Hb) concentration. Asymmetric flow field-flow fractionation (AFFF) in series with multi-angle static light scattering (MASLS) was used to study the LEHb size distribution. We also introduced a novel method to measure the encapsulation efficiency using a differential interferometric refractive index (DIR) detector coupled to the AFFF-MASLS system. This technique was nondestructive toward the sample and easy to implement. LEHbs were prepared by extrusion using a lipid combination of dimyristoyl-phosphatidylcholine, cholesterol, and dimyristoyl-phosphatidylglycerol in a 10:9:1 molar ratio. Five initial Hb concentrations (50, 100, 150, 200, and 300 mg Hb per mL of buffer) extruded through five different membrane pore diameters (400, 200, 100, 80, and 50 nm) were studied. Phosphate buffered saline (PBS) and phosphate buffer (PB) both at pH 7.3 were used as extrusion buffers. Despite the variation, extrusion through 400-nm pore diameter membranes produced LEHbs smaller than the pore size, extrusion through 200-nm membranes produced LEHbs with diameters close to the pore diameter, and extrusion through 100-, 80-, and 50-nm membranes produced LEHbs larger than the pore sizes. We found that the choice of extrusion buffer had the greatest effect on the LEHb size distribution compared to either Hb concentration or extruder membrane pore size. Extrusion in PBS produced larger LEHbs and more monodisperse LEHb dispersions. However, LEHbs extruded in PB generally had higher Hb encapsulation efficiencies and lower methemoglobin (metHb) levels. The choice of extrusion buffer also affected how the encapsulation efficiency correlated with Hb concentration, extruder pore size, and the metHb level. The most optimum encapsulation efficiency and amount of Hb entrapped were achieved at the highest Hb concentration and the largest pore size for both extrusion buffers (62.38% and 187.14 mg Hb/mL of LEHb dispersion extruded in PBS, and 69.98% and 209.94 mg Hb/mL of LEHb dispersion extruded in PB). All LEHbs displayed good oxygen-carrying properties as indicated by their P(50) and cooperativity coefficients. LEHbs extruded in PB had an average P(50) of 23.04 mmHg and an average Hill number of 2.29, and those extruded in PBS had average values of 27.25 mmHg and 2.49. These oxygen-binding properties indicate that LEHbs possess strong potential as artificial blood substitutes. In addition, the metHb levels in PB-LEHb dispersions are significantly low even in the absence of antioxidants such as N-acetyl-L-cysteine.

Blood Substitutes↗

PubMed2004

Correlation equation for predicting single-collector efficiency in physicochemical filtration in saturated porous media.

A new equation for predicting the single-collector contact efficiency (eta0) in physicochemical particle filtration in saturated porous media is presented. The correlation equation is developed assuming that the overall single-collector efficiency can be calculated as the sum of the contributions of the individual transport mechanisms--Brownian diffusion, interception, and gravitational sedimentation. To obtain the correlation equation, the dimensionless parameters governing particle deposition are regressed against the theoretical value of the single-collector efficiency over a broad range of parameter values. Rigorous numerical solution of the convective-diffusion equation with hydrodynamic interactions and universal van der Waals attractive forces fully incorporated provided the theoretical single-collector efficiencies. The resulting equation overcomes the limitations of current approaches and shows remarkable agreement with exact theoretical predictions of the single-collector efficiency over a wide range of conditions commonly encountered in natural and engineered aquatic systems. Furthermore, experimental data are in much closer agreement with predictions based on the new correlation equation compared to other available expressions.

Colloids↗