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Analytical solutions are widely used as screening tools for estimating the potential for contaminant transport in groundwater, or for interpreting tracer tests or groundwater quality data. A solution for three-dimensional solute migration from a plane-source source that is frequently used in practice is the approximate solution of Domenico [J. Hydrol. 91 (1987) 49-58]. A more rigorous solution to the same problem was provided by Sagar [ASCE, J. Hydraul. Div. 108, no. HY1 (1982) 47-62]. A comprehensive and unambiguous comparison between these two solutions is provided using dimensionless analysis. The solutions are first cast in terms of dimensionless parameters and then used to provide type curves covering a wide range of dimensionless parameter values. Results show that while discrepancies between the two solutions are relatively negligible along the plume centreline (for flow regimes dominated by advection and mechanical dispersion), large concentration differences can be observed as lateral distance from the centreline increases, especially in the presence of solute decay.
Effects of organic solutes properties, including Henry's law constant (H), molecular weight (M), molar volume at normal boiling point (Vb), and solubility (S), on the usefulness of rate estimation by reference to a reference substance (i.e., reference substance concept) and on the evaporation rate were investigated by measuring the volatilization rate constant of organic solutes under different environmental conditions, including mixing and surfactants. It was found that if benzene was used as a reference substance, the ratio of the solute rate to that of benzene (F) becomes insensitive to water mixing, whether the solute possessed high or low Henry's law constant. In the presence of surfactants, however, the F value changes sharply as the solute solubility decreases. For benzene, toluene, ethylbenzene, and xylenes (BTEX), the F values are essentially constant irrespective of the presence of other chemicals (including organic compounds, surfactants, and salinity) and of the variation in temperature. On the other hand, the volatilization rates are closely related to molecular weight (solubility) in the existence of mixing (surfactants). Three different approaches, i.e., mass-transport theory, modified Knudsen equation, and reaction rate concept, were used to evaluate the dependence of solute volatilization rates on solute properties. It was concluded that the interaction between solute properties and environmental parameters might play a key role in the volatilization process of organic solutes under different environmental conditions.
BACKGROUND: Elective colonoscopy is used increasingly to screen at risk patients for colonic malignancy. Bowel preparation quality is a critical factor for successful screening. Preparations used include high doses of potent laxatives, e.g. sodium phosphate solution or high volume polyethylene glycol. Because of constraints and limited patient acceptability, there remains a need for a more acceptable bowel preparation with at least equivalent cleansing to existing preparations. AIM: To determine if a 2-L polyethylene glycol solution with electrolytes and ascorbic acid (polyethylene glycol + ascorbic acid) produces equivalent bowel cleansing to sodium phosphate solution, and is acceptable to patients and well tolerated. METHODS: This was a single blind, parallel group, equivalence study comparing polyethylene glycol + ascorbic acid with sodium phosphate solution in 352 patients undergoing elective colonoscopy. A blinded, independent expert scored a video recording of each colonoscopy. Patients completed a questionnaire reporting acceptability of the bowel preparation process. RESULTS: Clinically successful bowel preparation was reported in 72.5% of cases prepared using polyethylene glycol + ascorbic acid and in 63.9% of cases prepared using sodium phosphate solution (treatment difference +8.6%, 95% confidence interval -2.3%, +19.4%). The new solution was well accepted and better tolerated than sodium phosphate solution. CONCLUSIONS: The new 2-L solution of polyethylene glycol + ascorbic acid was at least as efficacious as sodium phosphate solution with comparable efficacy and a better tolerability profile.
This paper is a report regarding a dermaerosion case dealing with a leakage of a chemically irrigable solution in a 3 year old boy. We are continuing to observe the dermal changes during as he grows. Also, we carried out a pathological experiment on a rabbit and a patch test of the derm of seven people. The following conclusions were obtained. 1. We observed the dermaerosion of an epithelium repair after a complete elapse of one year. The dermaerosion of the corium could not be repaired but changed the color of the derma of the patient who recovered after a lapse of 2 years and 8 months. 2. We recognized in the rabbit experiment that a 12% H2O2 solution damaged the corium of the rabbit over a period of 24 hours. The 12% H2O2 solution was four times higher, for we normally used a 3% H2O2 solution. 3. When we used a 10% NaOCl solution (which we usually use in the widening of the root canal) for 20 minutes on the derma of the rabbit, the derma damaged the epithelium but over a period of 40 minutes the solution we used on the derma of the rabbit damaged the corium. 4. When we used a NaOCl and H2O2 solution the reaction on the skin of the rabbit is weaker than when only one solution was used. 5. We used 0.5% NaOCl and 0.3% H2O2 solutions for the biceps of 2 atopic diseased people and 5 normal people for 48 hours, with no change noticed in their biceps. 6. The results may be summarized as follows.(ABSTRACT TRUNCATED AT 250 WORDS)
The renal preservation ability of a flushing solution (F-M) with fructose-1,6-diphosphate (1 g/dl) and mannitol (2 g/dl) during cold ischaemia was studied with the isolated perfused rat kidney model and compared with the Euro-Collins (EC) and University of Wisconsin (UW) solutions. Kidneys were stored in hypothermia for 4 and 18 h after initial flushing with the solution being tested, and then reperfused at 37 degrees C in an isolated perfusion circuit for 90 min with a Krebs-Henseleit solution containing 4.5% albumin. Forty-four kidneys were studied and divided in a control group and six study groups according to the cold ischaemia time and flushing solution used. Renal functional parameters of plasma flow rate (PFR), renal vascular resistance (RVR), urine flow rate (UFR) glomerular filtration rate (GFR), fractional (FRNa) and net (TNa) sodium reabsortion were assessed during reperfusion. Conventional histology and malondialdehyde tissue levels (MDA) were also evaluated. Our results show that PFR, RVR, and UFR were similar in all study groups. After 4 and 18 h of cold ischaemia, GFR, FRNa and TNa were better, and conventional histology worse in F-M than in EC flushed kidneys. After 4 and 18 h of cold ischaemia, GFR, FRNa and TNa, in fact, were not different between F-M and UW flushed kidneys. After 4 h of cold ischaemia, conventional histology was similar in F-M and UW flushed kidneys. Nevertheless, after 18 h of cold ischaemia, UW flushed kidneys showed worse histological parameters than F-M flushed kidneys. After 4 h of cold ischaemia, MDA was similar in kidneys flushed with three solutions. After 18 h of cold ischaemia MDA was higher in EC than in F-M or UW flushed kidneys. In summary, our newly developed cold storage solution shows promising results in renal preservation and its ability to preserve is at least as good as UW solution assessed in the isolated perfused rat kidney.
BACKGROUND: University of Wisconsin (intracellular) solution has been shown to offer some distinct benefits of myocardial preservation over Stanford (extracellular) solution, including a more rapid functional recovery, improved adenosine triphosphate preservation, and a tendency for less postoperative inotropic agents. However intracellular solutions with high potassium content have been reported to cause a functional if not structural endothelial injury in laboratory experiments. METHODS: Because of this information we retrospectively viewed our follow-up angiographic data for the development of the cardiac allograft vasculopathy in a consecutive series of 195 heart transplant recipients. These patients were treated in identical fashion, with the same immunosuppression regimen, except for the type of cardioplegia used--Stanford solution (group I n = 95) and University of Wisconsin solution (group II n = 100). RESULTS: With a mean follow-up of 24 months after transplantation, a significant difference was seen in the development of cardiac allograft vasculopathy in group II (22%) versus group I (14%, p < 0.03). Although significant differences were observed with univariate analysis with respect to donor age and ischemic time favoring group I and with multivariate statistical analysis with respect to overall rejections favoring group II, the only significant variable for the difference in the development of allograft vasculopathy was University of Wisconsin cardioplegic solution (p < 0.003). A subgroup of 30 patients previously randomized for a functional study comparing the two cardioplegic agents showed a tendency for statistical significance with a freedom from allograft vasculopathy of 93% in group I, as compared with 83% in group II, after 13 months follow-up (p = 0.09). The overall probability of being free of vasculopathy at 24 months was 86% for group I and 70% for group II. CONCLUSIONS: The data support the conclusion that University of Wisconsin intracellular solution is associated with an increased incidence of vasculopathy versus Stanford solution and warrants investigation for modification of this preservation agent in heart transplantation.
Lysozyme from T4 bacteriophage is comprised of two domains that are both involved in binding substrate. Although wild-type lysozyme has been exclusively crystallized in a closed form that is similar to the peptidoglycan-bound conformation, a more open structure is thought to be required for ligand binding. To determine the relative arrangement of domains within T4 lysozyme in the solution state, dipolar couplings were measured in several different dilute liquid crystalline media by solution NMR methods. The dipolar coupling data were analyzed with a domain orientation procedure described previously that utilizes high- resolution X-ray structures. The cleft between the domains is significantly larger in the average solution structure than what is observed in the X-ray structure of the ligand-free form of the protein (approximately 17 degrees closure from solution to X-ray structures). A comparison of the solution domain orientation with X-ray-derived structures in the protein data base shows that the solution structure resembles a crystal structure obtained for the M6I mutant. Dipolar couplings were also measured on the lysozyme mutant T21C/T142C, which was oxidized to form an inter-domain disulfide bond (T4SS). In this case, the inter-domain solution structure was found to be more closed than was observed in the crystal (approximately 11 degrees). Direct refinement of lysozyme crystal structures with the measured dipolar couplings using the program CNS, establishes that this degree of closure can be accommodated whilst maintaining the inter-domain cystine bond. The differences between the average solution conformations obtained using dipolar couplings and the crystal conformations for both forms of lysozyme investigated in this study illustrate the impact that crystal packing interactions can have on the arrangement of domains within proteins and the importance of alternative methods to X-ray crystallography for evaluating inter-domain structure.
The gelation in situ of polymers may be a method for temporarily containing organic solvents and other petroleum derived products, which may enter the subsurface. In order to create gels that are neither toxic to humans nor to the ecosystem, we have investigated on the use of the biopolymer xanthan gum with aluminum as a crosslinking agent. Firstly we have considered xanthan/sodium aluminate solutions, which upon preparation are strongly basic and do not gel. The gelation takes place in acid solutions so that Al(III) ions are released, and is instantaneous. Therefore, a special technique must be used for generating the gel structure in situ. The un-gelled solution must be injected and an acid must be added afterwards. We have investigated on the gelling reaction induced by gaseous carbon dioxide, which is an acid gas. The insufflation of CO(2) above the solution generates a layer of gel whose thickness progressively increases as CO(2) diffuses in the polymer solution. Secondly we have investigated on the use of aluminum chloride as the source of Al(III) ions. Also in this case, due to the full availability of Al(III) ions, the gelling reaction would be instantaneous. Therefore, the solution of AlCl(3) must be added on the top of the xanthan solution after its injection. For both gelling systems we have studied both theoretically and experimentally the rate of formation of the gel layer which progressively thickens after the insufflation of CO(2) or after the addition of the AlCl(3) solution.
The phenomenological solute permeability (omega p) of a membrane measures the flux of solute across it when the concentrations of the solutions on the two sides of the membrane differ. The relationship between omega p and the the conventionally measured tracer permeability (omega T) is examined for homoporous and heteroporous (parallel path) membranes in nonideal, nondilute solutions and in the presence of boundary layers. In general, omega p and omega T are not equal; therefore, predictions of transmembrane solute flux based on omega T are always subject to error. For a homoporous membrane, the two permeabilities become equal as the solutions become ideal and dilute. For heteroporous membranes, omega p is always greater than omega T. An upper bound on omega p- omega T is derived to provide an estimate of the maximum error in predicted solute flux. This bound is also used to show that the difference between omega P and omega T demonstrated earlier for the sucrose-Cuprophan system can be explained if the membrane is heteroporous. The expressions for omega P developed here support the use of a modified osmotic driving force to describe membrane transport in nonideal, nondilute solutions.
We present a joint theoretical and experimental study on the effects of competition for ligand between receptors in solution and receptors on cell surfaces. We focus on the following experiment. After ligand and cell surface receptors equilibrate, solution receptors are introduced, and the dissociation of surface bound ligand is monitored. We derive theoretical expressions for the dissociation rate and compare with experiment. In a standard dissociation experiment (no solution receptors present) dissociation may be slowed by rebinding, i.e., at high receptor densities a ligand that dissociates from one receptor may rebind to other receptors before separating from the cell. Our theory predicts that rebinding will be prevented when S much greater than N2Kon/(16 pi 2D a4), where S is the free receptor site concentration in solution, N the number of free surface receptor sites per cell, Kon the forward rate constant for ligand-receptor binding in solution, D the diffusion coefficient of the ligand, and a the cell radius. The predicted concentration of solution receptors needed to prevent rebinding is proportional to the square of the cell surface receptor density. The experimental system used in these studies consists of a monovalent ligand, 2,4-dinitrophenyl (DNP)-aminocaproyl-L-tyrosine (DCT), that reversibly binds to a monoclonal anti-DNP immunoglobulin E (IgE). This IgE is both a solution receptor and, when anchored to its high affinity Fc epsilon receptor on rat basophilic leukemia (RBL) cells, a surface receptor. For RBL cells with 6 x 10(5) binding sites per cell, our theory predicts that to prevent DCT rebinding to cell surface IgE during dissociation requires S much greater than 2,400 nM. We show that for S = 200-1,700 nM, the dissociation rate of DCT from surface IgE is substantially slower than from solution IgE where no rebinding occurs. Other predictions are also tested and shown to be consistent with experiment.
By measuring the freezing-point depression for dilute, aqueous solutions of all water-soluble amino acids, we test the hypothesis that nonideality in aqueous solutions is due to solute-induced water structuring near hydrophobic surfaces and solute-induced water destructuring in the dipolar electric fields generated by the solute. Nonideality is expressed with a single solute/solvent interaction parameter I, calculated from experimental measure of delta T. A related parameter, I(n), gives a method of directly relating solute characteristics to solute-induced water structuring or destructuring. I(n)-values correlate directly with hydrophobic surface area and inversely with dipolar strength. By comparing the nonideality of amino acids with progressively larger hydrophobic side chains, structuring is shown to increase with hydrophobic surface area at a rate of one perturbed water molecule per 8.8 square angstroms, implying monolayer coverage. Destructuring is attributed to dielectric realignment as described by the Debye-Hückel theory, but with a constant separation of charges in the amino-carboxyl dipole. By using dimers and trimers of glycine and alanine, this destructuring is shown to increase with increasing dipole strength using increased separation of fixed dipolar charges. The capacity to predict nonideal solution behavior on the basis of amino acid characteristics will permit prediction of free energy of transfer to water, which may help predict the energetics of folding and unfolding of proteins based on the characteristics of constituent amino acids.
We developed a new solution, ET-Kyoto (ET-K) solution, and compared its efficacy in 20 h lung preservation with that of Euro-Collins (EC) solution in a canine left lung transplantation model. The lungs were flushed with ET-K solution (ET-K group, n = 5), with EC solution plus prostaglandin E1 (PGE1) pretreatment (EC + PGE1 group, n = 6) or with EC solution (EC group, n = 6), and were stored at 4 degrees C for 20 h. The function of left lung grafts was assessed 40, 70, and 130 min after transplantation. The arterial pressure of oxygen (PaO2) in the ET-K group was significantly greater than in the EC + PGE1 group (p < 0.05 or p < 0.01) and in the EC group (p < 0.01). The peak inspiratory pressure and wet to dry weight ratio in the ET-K group were significantly lower than in the EC + PGE1 group and in the EC group (p < 0.05 or p < 0.01). Pulmonary vascular resistance in the ET-K group 130 min after reperfusion was significantly lower than in the EC group (p < 0.05). All the transplanted lungs in the EC + PGE1 group and the EC group showed histological evidence of pulmonary edema, whereas all in the ET-K group showed no signs of edema. We concluded that ET-K solution is superior to EC solution with or without PGE1 pretreatment in 20 h canine lung preservation.
We assessed the physical and chemical stability of docetaxel infusion solutions. Stability of the antineoplastic drug was determined 1.) after reconstitution of the injection concentrate and 2.) after further dilution in two commonly used vehicle-solutions, 0.9% sodium chloride and 5% dextrose, in PVC bags and polyolefine containers. Chemical stability was measured by using a stability-indicating HPLC assay with ultraviolet detection. Physical stability was determined by visual inspection. The stability tests revealed that reconstituted docetaxel solutions (= premix solutions) are physico-chemically stable (at a level > or = 95% docetaxel) for a minimum of four weeks, independent of the storage temperature (refrigerated, room temperature). Diluted infusion solutions (docetaxel concentration 0.3 mg/ml and 0.9 mg/ml), with either vehicle-solution, proved physico-chemically stable (at a level > or = 95% docetaxel) for a minimum of four weeks, when prepared in polyolefine containers and stored at room temperature. However, diluted infusion solutions exhibited limited physical stability in PVC bags, because docetaxel precipitation occurred irregularly, though not before day 5 of storage. In addition, time-dependent DEHP-teaching from PVC infusion bags by docetaxel infusion solutions must be considered.
In this double-blind clinical trial 429 patients (217 terbinafine and 212 clotrimazole) were randomized to receive twice daily terbinafine 1% topical solution for 1 week followed by a vehicle application for 3 weeks, or 1% clotrimazole solution for 4 weeks. Patients were evaluated clinically and mycologically at baseline and then at weeks one, two, four (end of treatment), and eight (end of follow-up). To be evaluable the patient needed to have a positive culture for a dermatophyte and positive KOH microscopy and a clinical diagnosis of tinea pedis (interdigital type) at baseline. Effective treatment of tinea pedis was recorded in 181 of 217 (83%) of patients treated for 1 week with terbinafine 1% solution and 174 of 212 (82%) of patients treated for 4 weeks with clotrimazole 1% solution. Mycological cure and disappearance of signs and symptoms were similar at each assessment visit in the two groups. In the subgroup of patients without any protocol violation the mycological cure rate was 95% (164 of 173) with terbinafine solution and 91% (159 of 174) with clotrimazole solution (P = 0.05). Adverse events believed to be drug-related occurred in 13 patients in the terbinafine group and 11 in the clotrimazole group (4 to 5% in each group). The events were primarily local skin reactions of mild to moderate intensity. It can be concluded that terbinafine 1% solution used for 1 week to treat tinea pedis is well tolerated and at least as effective as clotrimazole 1% solution used for 4 weeks.
Extraneal peritoneal dialysis (PD) solution (Baxter Healthcare, Deerfield, Illinois, U.S.A.) contains glucose polymer (icodextrin) as an osmotic agent in place of dextrose. We investigated the ability of Extraneal to form advanced glycation end products (AGEs) in vitro compared to standard PD solutions containing dextrose. Extraneal, Dianeal PD-2 [1.5%, 2.5%, or 4.25% dextrose (Baxter Healthcare)], or phosphate buffered saline (PBS) were incubated for 45 days with human serum albumin (HSA) or type IV collagen. AGE formation was measured by spectrofluorometry using excitation at 350 nm and emission at 430 nm. Solutions were also incubated with collagen affixed to plastic, simulating matrix collagen in the peritoneal membrane. In addition, AGE formation was assessed using icodextrin metabolites (maltose, maltotriose, and maltotetraose) at concentrations normally found in the plasma of patients treated using icodextrin. For PD solutions incubated with albumin, the relative order of AGE formation was: 4.25% dextrose > 2.5% dextrose > 1.5% dextrose > Extraneal. For incubations with collagen (in solution or affixed to plastic), AGE formation was greatest for 4.25% dextrose, intermediate for Extraneal and 2.5% dextrose, and lowest for 1.5% dextrose. Incubation of icodextrin metabolites with albumin for 45 days did not result in appreciable AGE formation. These results confirm that solutions containing icodextrin result in less in vitro AGE formation than do high dextrose solutions. The results also suggest that Extraneal may lead to improved solution biocompatibility in vivo.
BACKGROUND: Celsior is a new extracellular-type preservation solution which has been developed to act not only as a storage medium but also as a perfusion fluid during initial donor heart arrest, poststorage graft reimplantation and early reperfusion. We designed this experimental study to evaluate the effect of the Celsior solution in comparison with the University of Wisconsin solution from the viewpoint of energy depletion. METHODS: Adult mongrel dogs weighing 9 to 13 kg were divided into two groups. In the UW group (n=7), a 4 degrees C University of Wisconsin solution was used for coronary vascular washout and storage following cardiac arrest using a glucose-insulin-potassium solution. In the Celsior group (n=7), the Celsior solution was used to obtain cardiac arrest, coronary vascular washout and storage. High energy phosphate levels and myocardial pH were measured using (31)P-nuclear magnetic resonance spectroscopy immediately after preservation and at 3, 6 and 12 hours after preservation. After 12-hour cold storage, left ventricular free wall tissues were harvested for histological examination. RESULTS: High energy phosphate levels and myocardial pH were significantly better preserved in the Celsior group than in the UW group. In the histological findings, glycogen granules were preserved well in the Celsior group. CONCLUSIONS: We conclude from our study that the Celsior solution is comparable to the University of Wisconsin solution for use in 12-hour heart preservation in canine models.