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PubMed1996

Effects of Euro-Collins, University of Wisconsin, and new extracellular-type trehalase-containing Kyoto solutions in an ex vivo rat lung preservation model.

BACKGROUND: We have previously reported the effects of trehalose-based extracellular-type Kyoto (ET-K) solution in lung preservation. Now, we have developed a new ET-K solution by adding three substances--N-acetyl cysteine, dibutyryl cyclic AMP, and nitroglycerin, to ET-K solution. We studied the effects of new ET-K solution in lung preservation, and compare it with Euro-Collins (EC) and University of Wisconsin (UW) solutions using an ex vivo rat reperfusion model. METHODS: The perfusion circuit was initiated by 30 ml of fresh mixed venous blood obtained from three haparinized rats. By means of a double-head roller pump, the blood passed from the venous blood reservoir through the pulmonary artery to be perfused in the examined lung. The lung effluent was returned at the same flow rate to the deoxygenator fresh lung. Four experimental groups were allocated. In group 1 (fresh group, n=6), lung was flushed with saline and reperfused immediately. In the other groups (group 2: new ET-K group, n=6; group 3: UW group, n=6; and group 4: EC group, n=6), lung was flushed with the new ET-K and prostanglandin E1 (PGE1), UW and PGE1, and EC and PGE1, respectively. After 17-hr preservation, the preserved lung was reperfused. RESULTS: In all six animals of the EC group, ventilation of the experimental lung was discontinued at 20 min after reperfusion because of the exudate in the endotracheal tube that resulted from pulmonary edema. The shunt fraction, pulmonary arterial pressure, and peak inspiratory pressure in the new ET-K and UW groups were significantly better than those in the EC group, but were almost equal to those in the fresh group. CONCLUSION: The postpreservation pulmonary functions with the new ET-K solution were better than those with the EC solution, and were equal to those with the UW solution. This new solution is expected to contribute to the increase in donor lungs for clinical lung transplantation. In addition, this ex vivo rat reperfusion model is simple and highly reliable, and can be widely used in the studies of pulmonary preservation.

Adenosine↗
PubMed1994

A comparison of flushing solutions for liver procurement using an isolated perfused porcine model.

There is no agreement on the best technique of in situ flushing of livers prior to storage. In order to study this, porcine livers were stored in the University of Wisconsin (UW) solution for 18 h and then assessed using an isolated perfused porcine model. Livers flushed in situ with UW solution were compared to livers flushed with a non-preservation solution (Hartmann's solution). No statistically significant differences could be found in bile production (18.7 +/- 4.4 vs 17.9 +/- 3.8mL/1000 g per 2 h), aspartate amino-transferase (AST) levels in the perfusate after 2 h of isolated perfusion (687 +/- 101 vs 724 +/- 114 U/L), potassium levels in the perfusate after 2 h on the circuit (5.4 +/- 1.5 vs 5.5 +/- 2.3 mmol/L), weight gain (15.2 +/- 3.7 vs 17.1 +/- 4.0%) or platelet sequestration (41.6 +/- 11.7 vs 37.4 +/- 9.8%) between livers flushed with UW solution as opposed to those flushed with Hartmann's solution, respectively. Of overriding importance was the solution in which the liver was stored, reconfirming the superiority of UW solution over an extracellular solution for preservation. If extrapolated to the clinical situation, these findings would have substantial cost-saving implications.

Adenosine↗
PubMed1997

Intraocular irrigating solutions and barrier function of retinal pigment epithelium.

AIM: To study the effect of intraocular irrigating solutions on the barrier property of the retinal pigment epithelium (RPE). METHODS: The isolated rabbit RPE-choroid mounted on Ussing-type chambers under short circuit conditions was used. According to a previous study, the inward (from the choroid to the vitreous side) permeability of the tissue to carboxyfluorescein was adopted as a quantitative index of the barrier function of the RPE cells. RESULTS: Of the three solutions tested, Krebs-Ringer solution, a commercially available glucose glutathione bicarbonate solution (BSS plus), and glucose citrate-acetate bicarbonate solution (Opeguard), BSS plus gave a significantly lower permeability (1.1 x 10(-6) cm/s on average) than Krebs-Ringer solution or Opeguard (1.9 or 1.8 x 10(-6) cm/s on average, respectively) (unpaired t test with Bonferroni's correction, p < 0.05). Since the major chemical difference between BSS plus and the other two solutions is the incorporation of oxidised glutathione (GSSG), the effects of GSSG were studied using solutions having an identical composition to BSS plus, but with various concentrations of GSSG. The solution containing 0.3 mM GSSG gave significantly lower permeability than that without GSSG (1.1 x 10(-6) cm/s v 2.0 x 10(-6) cm/s) (unpaired t test with Bonferroni's correction, p < 0.05). CONCLUSION: It was suggested that BSS plus is less harmful to the barrier function of the RPE cells and that GSSG has a beneficial effect on its maintenance.

Animals↗
PubMed1985

Short-term effect of 4% hypertonic glucose as compared to 4% mixed hypertonic mannitol solution in conventional peritoneal dialysis.

16 peritoneal dialyses were performed in 14 end-stage kidney disease patients; 6 had diabetic nephropathy, and, of the nondiabetic group, 7 had chronic glomerulonephritis, and 1 had polycystic kidney disease. The peritoneal dialysis performed with conventional 1.5% glucose solution, intervened by four consecutive exchanges using 4% hypertonic glucose solution, was compared to 4% mixed hypertonic mannitol solution in the diabetic and nondiabetic group. There was no significant change of serum glucose, when postdialysis with 1.5% glucose solution was compared to 4% mixed hypertonic mannitol solution; however there was a significant change of serum osmolality in both groups. Postdialysis with both 4% hypertonic solutions showed that there was no significant difference of ultrafiltration volume in both groups of patients, but there was a significant difference in serum glucose in the diabetic group. The transport mechanism of mixed hypertonic mannitol solution as compared to hypertonic glucose solution is discussed. The application of hypertonic mannitol solution for clinical use is not advised.

Adult↗
PubMed1999

Beneficial effects of leukocyte-depleted blood and low-potassium dextran solutions on microvascular permeability in preserved porcine lung.

Modified Euro-Collins (EC) solution, a crystalloid intracellular-type solution, has been commonly used for pulmonary preservation. Several experimental studies have shown the advantages of using extracellular colloid-based solutions. The aim of this study was to compare the quality of preservation of two extracellular colloid solutions, leukocyte-depleted blood (BL) and low-potassium dextran (LPD) solutions, with that of EC solution. Lungs of 22 domestic pigs were flushed and preserved with EC (n = 8), BL (n = 7), or LPD (n = 7) solution. After harvesting, one of the lungs was reperfused immediately in an ex vivo circuit (control lungs), whereas the contralateral lung was reperfused after 8 h of cold (4 degrees C) storage (preserved lungs). Besides the lung function parameters (gas exchange, pulmonary hemodynamics and mechanics), the permeability of the endothelial-epithelial barrier was assessed by determining the transferrin leak index (TLI) using a double radioisotopic method, by measuring the alveolar/arterial protein concentration ratio, and by analyzing histopathologic changes. The functional quality (oxygenation, airway resistance, dynamic compliance [CL, dyn]) of both BL and LPD lungs was slightly but significantly superior to that of EC lungs. However, pulmonary vascular resistance was lower in BL-preserved than in EC- or LPD-preserved lungs. The TLI was increased in EC control and preserved lungs, whereas it was low in BL and LPD control lungs and did not increase after preservation. The alveolar/arterial protein concentration ratio was not different between control groups, but was increased fourfold in EC-preserved compared with BL- or LPD-preserved lungs. Finally, EC-preserved lungs presented a weight gain about twice that of BL- and LPD-preserved lungs. Morphologic analysis confirmed these results, because in the EC-preserved lungs, rupture of alveolar septa and severe alveolar edema and hemorrhage were observed, whereas BL- and LPD-preserved lungs showed a relatively well-preserved structure. The results demonstrate that both BL and LPD flush solutions preserve the endothelial-epithelial barrier better than does EC solution. Although the quality of preservation is similar, pulmonary vascular resistance is higher in LPD-preserved than in BL-preserved lungs.

Animals↗
PubMed1993

Functional integrity of proximal tubule cells: effects of temperature and preservation solutions.

Electrophysiologic and morphologic changes during cooling and perfusion with preservation solutions in isolated perfused proximal straight tubules from Swiss white mice were investigated. In standard Ringer-substrate solution, cooling from 37 degrees C to 22 and 4 degrees C depolarized both transepithelial potential and basolateral cell membrane potential. Basolateral k+ transference number and cell membrane conductances were also significantly reduced. An increase in intracellular Na+ activity was observed only during cooling from 37 to 4 degrees C. No cell swelling was detected when tubules were perfused with Ringer-substrate solution at all three temperatures up to 1 h. Perfusion with Euro-Collins' (EC) solution at 37 degrees C resulted in rapid cell swelling, associated with rapid deterioration of transepithelial potential. Substitution of glucose with mannitol abolished the damaging effect of EC solution at 37 degrees C. EC perfusion at 22 degrees C also led to cell swelling and deterioration of transepithelial potential, but after a 10-min delay. In comparison, perfusion with University of Wisconsin (UW) solution at 22 or 37 degrees C had no effect on cell volume. Less damage to transepithelial potential was observed after the UW perfusion. It was concluded that EC solution is more damaging than UW solution to kidney tubules at 22 and 37 degrees C. The presence of EC solution in the renal interstitium during the rewarming phase may contribute significantly to reperfusion injuries in kidney transplantation.

Adenosine↗
PubMed1989

Corrosion and tarnish of dental silver-based alloys in 0.1% Na2S and Ringer's solutions. (Part 1) Electrochemical study.

The corrosion behavior of three silver-based alloys, Ag-Sn-Zn, Ag-In, and Ag-Pd-Cu, were investigated by potentiodynamic anodic polarization analysis and the polarization resistance method in 0.1% Na2S and Ringer's solutions. The corrosion activity of the Ag-Sn-Zn alloy was higher in Ringer's solution than in the 0.1% Na2S solution. In contrast, the corrosion rate of the Ag-Pd-Cu alloy was approximately 500 times higher in the 0.1% Na2S solution than in Ringer's solution. The results show that the generally accepted concept that tarnish is merely a surface discoloration due to the deposition of insoluble products is inadequate. The alloy discolors while being severely attacked in the presence of sulfides. For the Ag-In alloy, the corrosion activity in the 0.1% Na2S solution was as high as in Ringer's solution. These silver-based alloys exhibit different electrochemical activities in different solutions. The test solutions for corrosion tests must be carefully chosen for each alloy system through a screening test to replicate the predominant corrosion reaction proceeding in the oral environment.

Corrosion↗
PubMed1992

Hypertonic solutions in the treatment of hypovolemic shock: a prospective, randomized study in patients admitted to the emergency room.

BACKGROUND: The infusion of small volumes of hypertonic saline solution or hypertonic saline plus dextran 70 is remarkably effective in restoring adequate hemodynamic conditions after hypovolemic shock. This prospective double-blind study compares the immediate hemodynamic effects of a bolus infusion of 7.5% NaCl or 7.5% NaCl plus 6% dextran 70 (both 2400 mOsm/L) in severe hypovolemia. METHODS: One hundred five adult patients admitted in hypovolemic shock (systolic blood pressure less than 80 mm Hg) were revived on arrival to the emergency room and administration of a 250 ml intravenous bolus of hypertonic saline solution (n = 35), hypertonic saline plus dextran (n = 35), or isotonic saline solution (n = 35). This infusion was immediately followed by standard crystalloid and blood replacement until systolic pressure reached 100 mm Hg. Mean arterial pressure (MAP) was measured every 5 minutes, and all intravenous infusions were registered. Plasma volume expansion was calculated from plasma protein concentration measurements. Patients were followed up throughout their hospital course, and results of treatment were recorded. RESULTS: At the end of the infusion period, and 5 and 10 minutes after infusion, MAP was significantly higher in patients receiving either hypertonic solution, compared with the group receiving isotonic solution. All groups showed similar trends toward restoration of hemodynamic parameters thereafter. The calculated plasma volume expansion, immediately after the bolus infusion, was significantly higher (24.1% +/- 1.8% and 24.9% +/- 1.1%) in the hypertonic groups, compared with isotonic groups (7.9% +/- 1.3%). Significantly greater volumes of fluids were required to restore systolic pressure in the patients receiving isotonic saline solution than in the groups receiving hypertonic solution. There were no significant differences between the groups receiving hypertonic solutions. The incidence of complications was low, and the mortality rate was similar in all groups. CONCLUSIONS: Infusion of 250 ml hypertonic saline solution in patients with severe hypovolemia was not related to any complications, nor did it affect mortality rates; it improved MAP significantly, acutely expanded plasma volume by 24%, and reduced significantly the volumes of crystalloids and blood required in their resuscitation.

Adult↗
PubMed1987

Calcium and phosphate solubility in neonatal parenteral nutrient solutions containing Aminosyn PF.

Factors affecting the solubility of calcium and phosphate in neonatal total parenteral nutrient (TPN) solutions containing a new amino acid formulation were studied. Six TPN solutions containing various concentrations of Aminosyn PF, an amino acid solution for infants and children, were prepared in 10% dextrose injection. Some of the solutions also contained cysteine hydrochloride 40 mg per gram of protein. Various concentrations of calcium gluconate and monobasic and dibasic potassium phosphate were added to 20-mL samples of the TPN solutions. A total of 27 samples of each TPN solution was prepared. Samples were visually inspected after 18 hours at 25 degrees C and again after 30 minutes in a water bath at 37 degrees C. Clear samples at this time were also examined microscopically. Solubility curves were prepared by plotting the concentrations at which either visual or microscopic precipitation occurred. Solubility curves for TPN formulations containing Aminosyn PF revealed a decrease in calcium solubility of 5 to 15 meq/L and a decrease in phosphate solubility of 5 to 15 mmol/L compared with previously published calcium-phosphate solubility curves for another similar amino acid solution, TrophAmine. Calcium and phosphate solubilities were also influenced by temperature and the time after solution preparation. In these TPN formulations containing Aminosyn PF as the amino acid source, the solubilities of calcium and phosphate were substantially less than reported in a previous study of solutions containing TrophAmine.

Amino Acids↗
PubMed1993

Sodium lactobionate sucrose solution for canine liver and kidney preservation.

With 24-hour preservation of canine liver, SLS solution showed inferior animal survival to UW solution. The lactobionate, raffinose, glutathione, and hydroxyethyl starch in UW solution have been shown to be important for liver preservation. However, our results suggest that sucrose should not be substituted for raffinose for the preservation of livers. In contrast to the liver, SLS solution performed the same or even better than UW solution for kidney preservation. The substitution of sucrose for raffinose, along with the addition of CPZ has either no effect or a slightly positive effect on kidney preservation. In conclusion, SLS solution may be a suitable solution for preserving canine kidneys, but is not suitable for liver preservation. These findings suggest that future development of preservation solutions should be focused on the needs of specific organs and not toward a generic, all encompassing preservation solution.

Animals↗
PubMed1995

Effect of sodium concentration in a carbohydrate-electrolyte solution on intestinal absorption.

Intestinal absorption during infusion (15 ml.min-1) of a 6% carbohydrate (2% glucose and 4% sucrose) solution containing either 0, 25 or 50 mEq.l-1 Na+ was measured by segmental perfusion with a triple lumen tube in males (age 24.3 +/- 1.6) at rest in a neutral environment (22 degrees C). Infusion of the 25 and 50 mEq.l-1 Na+ solutions was performed using a balanced design on the same day, separated by a 1-hr period of no infusion. Infusion of 0 mEq.l-1 Na+ solution was performed on a separate day. A 45-min equilibration period preceded a 90-min test session. Water and solute fluxes were determined from differences in concentration of polyethylene glycol and solute across a 40-cm intestinal segment of the duodenojejunum. A two-factor repeated measures ANOVA indicated no differences (P > 0.1) over time for water, Na+, or glucose flux for all solutions. Plasma volume increased (P < 0.01) approximately 5% over time for all solutions. We conclude that Na+ concentrations of 0, 25, or 50 mEq.l-1 in a 6% carbohydrate solution have similar effects on the absorption of water, Na+, and glucose from the duodenojejunum. Glucose in the infusion solution is the more important factor determining intestinal water absorption than Na+. This study suggests that adding Na+ to fluid replacement beverages may not be a factor in fluid absorption.

Adult↗
PubMed1994

Effect of several electrolyte preservation solutions on the water permeability of isolated cortical collecting ducts perfused in vitro.

The extent of nephron injury after long-term preservation is unknown. An experimental protocol was designed to study the effects of 1 and 24 h of cold storage in preservation solution on renal slices of rabbit cortical collecting duct (CCD) isolated and perfused in vitro and evaluated by water hydraulic conductivity. The preservation solutions were Ringer-bicarbonate, Collins, Euro-Collins, and University of Wisconsin (UW). Under these experimental preservation conditions, the following results were observed: after 1 h of preservation, the CCDs obtained from slices incubated in Ringer-bicarbonate, Collins, and Euro-Collins solutions at 4 degrees C presented a high basal hydraulic conductivity compared to the control group and responded well to arginine-vasopressin (AVP) water permeability stimulation. The CCDs derived from renal slices stored for 24 h in Ringer-bicarbonate solution at 4 degrees C showed no function, while those preserved in Collins and Euro-Collins solutions showed a lack of responsiveness to AVP water permeability stimulation. The CCDs preserved in UW solution showed better values than those preserved in the other solutions, although there was a decrease in hydraulic conductivity after 24 h of preservation. These data show that long-term cold preservation with flushed solutions impairs the cortical collecting duct response to AVP.

Adenosine↗
PubMed1990

Intraocular irrigating solutions and permeability of the blood-aqueous barrier.

The effects of intraocular irrigating solutions on the blood-aqueous barrier were studied using rabbits injected with fluorescein isothiocyanate-labeled rabbit albumin. Two days after the injection, the anterior chamber was perfused for 121 minutes with one of the following solutions: normal saline, a commercially available citrate-acetate bicarbonate solution, or a glucose glutathione bicarbonate solution; the amount of fluorescein isothiocyanate-labeled rabbit albumin collected in the outflowing perfusate standardized to its plasma concentration was adopted as a blood-aqueous barrier permeability index. Of the three solutions, normal saline showed the highest permeability index and glucose glutathione bicarbonate solution showed the lowest. The effects of oxidized glutathione on the blood-aqueous barrier were also studied, using solutions containing various concentrations of oxidized glutathione. The permeability index for the solution containing 0.3 mmol/L of oxidized glutathione was significantly smaller than that for the solution without oxidized glutathione, suggesting that oxidized glutathione has a beneficial effect on the integrity of the blood-aqueous barrier.

Acetates↗
PubMed1990

Sclerosing cholangitis induced by formaldehyde solution injected into the biliary tree of rats.

Sclerosing cholangitis has been reported after surgical treatment of hydatid disease of the liver and has been hypothetically attributed to the caustic effect of the parasiticide solution injected into the cyst and diffusing into the biliary tree through a cystic-biliary fistula. In this experimental study, we showed that, in rats, injection into the biliary tract of 20% hypertonic saline solution or 2% formaldehyde solution, the most commonly used scolicidal solutions, was followed by lesions of the biliary epithelium. As compared with 20% hypertonic saline solution, the 2% formaldehyde solution caused more severe lesions of the biliary epithelium and, in addition, induced the development of sclerosis. This experimental study confirms the deleterious effect of scolicidal solutions to the biliary epithelium, shows that their effect is mainly related to the causticity of the scolicidal solution, and indicates that intracystic injection of 2% formaldehyde solution should be abandoned.

Animals↗
PubMed1997

Surface modifications of titanium in calcium-ion-containing solutions.

The surface of titanium was modified in calcium-ion-containing solutions to improve bone conductivity. Three kinds of aqueous solutions for the modification were prepared using calcium nitrate, calcium chloride, and calcium oxide. The pH values of the solutions were 3.9, 7.4, and 12.6, respectively. At first, anatase powder was immersed in the solutions of 7 days to confirm the effect of the solutions on the modification. As a result, calcium titanate was formed on the anatase powder, indicating that the titanium surface was possibly modified by the solutions. Titanium plates were then immersed in the solutions at ambient temperature for 7 days, washed by deionized water, and dried. X-ray photo-electron spectroscopy of surface-modified titanium revealed that the surface-modified layer contained calcium hydroxide and/or calcium titanate. The surface-modified layer in which titanium was modified was thickest in this order: calcium oxide, calcium chloride, and calcium nitrate solutions. Apatite was formed on the surface-modified titanium in Hanks' solution while apatite was undetected on unmodified titanium. Therefore, the surface modification of titanium may improve bone conductivity. The amount of apatite corresponded to the thickness of the surface-modified layer and the amount of calcium in the layer.

Apatites↗
PubMed1997

Oxygen-free radical-mediated injury to cultured rat hepatocytes during cold incubation in preservation solutions.

We have previously shown that the injury to cultured liver endothelial cells during cold incubation in University of Wisconsin (UW) solution is energy-dependent and is mediated by reactive oxygen species. Here we demonstrate that this reactive oxygen-mediated injury is specific neither to endothelial cells nor to UW solution: cultured hepatocytes incubated in cold (4 degrees C) UW solution or histidine-tryptophan-ketoglutarate (HTK) solution were injured under normoxic conditions (loss of viability, 63% +/- 10% after 48 hours of cold incubation in UW solution and 82% +/- 11% after 24 hours of cold incubation in HTK solution), whereas hypoxia was protective (loss of viability, 29% +/- 12% [UW] and 13% +/- 3% [HTK] after the same cold incubation times). The injury under normoxic conditions was also largely decreased by adding either the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) or the flavonoid silibinin to the solutions, or by preincubating the cells with the iron chelator deferoxamine before the hypothermic incubation. Marked lipid peroxidation was observed during cold incubation in both preservation solutions. These results suggest that the injury to cultured hepatocytes during cold incubation in UW and HTK solutions is mediated by reactive oxygen species as is the injury to cultured liver endothelial cells.

Adenosine↗
PubMed2006

Application of high-frequency rheology measurements for analyzing protein-protein interactions in high protein concentration solutions using a model monoclonal antibody (IgG2).

The purpose of this work was to explore the utilization of high-frequency rheology analysis for assessing protein-protein interactions in high protein concentration solutions. Rheology analysis of a model monoclonal immunoglobulin G2 solutions was conducted on indigenously developed ultrasonic shear rheometer at frequency of 10 MHz. Solutions at pH 9.0 behaved as most viscous and viscoelastic whereas those at pH 4.0 and 5.4 exhibited lower viscosity and viscoelasticity, respectively. Intrinsic viscosity, hydrophobicity, and conformational analysis could not account for the rheological behavior of IgG2 solutions. Zeta potential and light scattering measurements showed the significance of electroviscous and specific protein-protein interactions in governing rheology of IgG2 solutions. Specific protein-protein interactions resulted in formation of reversible higher order species of monomer. Solution storage modulus (G'), and not loss modulus or complex viscosity, was the more reliable parameter for predicting protein-protein interactions. Predictions about the nature of protein-protein interactions made on the basis of solution G' were found to be consistent with observed effect of pH and ionic strength on zeta potential and scattered intensity of IgG2 solutions. Results demonstrated the potential of high-frequency storage modulus measurements for understanding behavior of proteins in solutions and predicting the nature of protein-protein interactions.

Algorithms↗
PubMed1990

Mechanism and kinetics of secretion degradation in aqueous solutions.

In order to clarify the mechanism of secretin degradation in aqueous solutions, the formation of degradation products from secretin, aspartoyl3 secretin and beta-aspartyl3 secretin was investigated; the stabilities of these three peptides were investigated as well. Aspartoyl3 secretion and beta-aspartyl3 secretin, degradation peptides produced during the storage of secretin in aqueous solutions, were isolated by preparative reversed-phase HPLC (RP-HPLC). The amounts of secretin and its two degradation peptides resulting from storage of secretin in various buffer solutions (pH 2.3 to 10.0, mu = 0.5 M, 60 degrees C) were determined by analytical RP-HPLC. Secretin and the isolated degradation peptides were stored separately in various aqueous buffer solutions resulting in the degradation of each peptide. A mixture of secretin and its degradation or cleavage peptides was formed in each solution. The observed degradation rates for each peptide approximately followed first-order kinetics. The pH-rate profiles for conversion of secretin and beta-aspartyl3 secretin were similar, while that for aspartoyl3 secretin was different from these two. Aspartoyl3 secretin was more stable than the others at pH 2.3 to 4.0, but it was easily degraded between pH 5.0 and 10.0. Investigation of aspartoyl3 secretin degradation showed that its degradation was related to the pH value of the solution, and that hydroxide ion catalyzes the ring opening of the aspartoyl peptide. Secretin was most stable in pH 7.0 buffer solution and more stable in acidic solutions than in alkaline solutions. Secretion was mainly degraded through the following pathways: cleavage peptides reversible secretin in equilibrium aspartoyl peptide in equilibrium beta-aspartyl peptide vector cleavage peptides.

Buffers↗