Tissue-gel electrophoresis enhances antigen removal from porcine aortic valve and bovine pericardium

BACKGROUND AND AIM OF THE STUDY

A tissue-engineered heart valve could provide a living prosthesis with characteristics of an ideal valve replacement. One approach to scaffolding a tissue-engineered heart valve is through the 'decellularization' of xenogeneic tissues. Concerns regarding the completeness of antigen removal associated with current detergent-based decellularization treatments have been raised. The study aim was to evaluate antigen removal from candidate xenogeneic bioscaffolds using a novel tissue-gel electrophoresis (TGE) method.

METHODS

Porcine aortic valve (PAV) conduit and bovine pericardium (BP) were treated sequentially with hypotonic lysis, sodium dodecyl sulfate (SDS), and TGE. The completeness of antigen removal was evaluated by immunoblot analysis of extractable soluble proteins using rabbit anti-PAV or anti-BP serum. Tissues were also evaluated by hematoxylin and eosin histology.

RESULTS

TGE enhanced antigen removal from both the PAV and BP. The effects of TGE were shown to depend on the SDS concentration and voltage (60 versus 120 V), but to be independent of time after 4 h. The effects of TGE were detectable both before and after 96 h aqueous washout. Treatment with 1.0% SDS with TGE (120 V for 4 h) resulted in complete acellularity and no detectable soluble protein antigens from the PAV conduit.

CONCLUSION

TGE is a promising adjunctive decellularization method for generating non-immunoreactive bioscaffolds from xenogeneic tissues.

Improving intravenous fluid therapy in children with gastroenteritis

Gastroenteritis is one of the most common medical conditions seen by pediatricians. The standard approach to intravenous fluid therapy for these children has been to administer a 0.9% sodium chloride (NaCl) bolus followed by a hypotonic solution ranging from 0.2-0.45% NaCl to replace the remaining deficit plus maintenance. We have questioned the safety of this approach as there have been reports of death or permanent neurologic impairment from hyponatremic encephalopathy. Hanna and Saberi (Pediatr Nephrol. doi: 10.1007/s00467-009-1428-y ) found the incidence of hospital-acquired hyponatremia (sodium < 135 mEq/L) to be 18.5% for patients presenting with isonatremic dehydration from gastroenteritis. This confirms that the current approach of using hypotonic fluids results in a high incidence of hyponatremia. Hypotonic fluids are not appropriate for rehydration in patients with gastroenteritis as it is a state of arginine vasopressin (AVP) excess due to both hemodynamic stimuli from volume depletion and non-hemodynamic stimuli such as nausea and vomiting. Free water will be retained until the volume deficit is corrected and the hemodynamic stimulus for AVP production abates. A safer and more effective approach is the administration of 0.9% NaCl in a continuous infusion following bolus therapy. 0.9% NaCl not only serves as prophylaxis against hyponatremia, but it is superior to hypotonic fluids as an extracellular volume expander and corrects the volume deficit more rapidly.

P2X4 activation modulates volume-sensitive outwardly rectifying chloride channels in rat hepatoma cells

Volume-sensitive outwardly rectifying (VSOR) Cl(-) channels are critical for the regulatory volume decrease (RVD) response triggered upon cell swelling. Recent evidence indicates that H(2)O(2) plays an essential role in the activation of these channels and that H(2)O(2) per se activates the channels under isotonic isovolumic conditions. However, a significant difference in the time course for current onset between H(2)O(2)-induced and hypotonicity-mediated VSOR Cl(-) activation is observed. In several cell types, cell swelling induced by hypotonic challenges triggers the release of ATP to the extracellular medium, which in turn, activates purinergic receptors and modulates cell volume regulation. In this study, we have addressed the effect of purinergic receptor activation on H(2)O(2)-induced and hypotonicity-mediated VSOR Cl(-) current activation. Here we show that rat hepatoma cells (HTC) exposed to a 33% hypotonic solution responded by rapidly activating VSOR Cl(-) current and releasing ATP to the extracellular medium. In contrast, cells exposed to 200 microm H(2)O(2) VSOR Cl(-) current onset was significantly slower, and ATP release was not detected. In cells exposed to either 11% hypotonicity or 200 microm H(2)O(2), exogenous addition of ATP in the presence of extracellular Ca(2+) resulted in a decrease in the half-time for VSOR Cl(-) current onset. Conversely, in cells that overexpress a dominant-negative mutant of the ionotropic receptor P2X4 challenged with a 33% hypotonic solution, the half-time for VSOR Cl(-) current onset was significantly slowed down. Our results indicate that, at high hypotonic imbalances, swelling-induced ATP release activates the purinergic receptor P2X4, which in turn modulates the time course of VSOR Cl(-) current onset in a extracellular Ca(2+)-dependent manner.

Sodium bicarbonate in preventing contrast nephropathy in patients at risk for volume overload: a randomized controlled trial

BACKGROUND

Sodium bicarbonate has been recently proposed as a prophylactic measure for the prevention of contrast-induced nephropathy (CIN). We aimed to compare the efficacy of the combination of sodium bicarbonate with half saline, and half saline alone in preventing CIN in patients having uncontrolled hypertension, compensated severe heart failure or a history of pulmonary edema.

METHODS

Seventy-two patients undergoing elective coronary angiography with a serum creatinine level > or =1.5 mg/dL who had uncontrolled hypertension, compensated severe heart failure or a history of pulmonary edema were prospectively enrolled in a single-center, double-blind, randomized, controlled trial from August 2007 to July 2008 and were assigned to either an infusion of sodium bicarbonate plus half saline (n=36) or half saline alone (n=36). The primary end point was an absolute (> or =0.5 mg/dL) or relative (> or =25%) increase in serum creatinine 48 hours after the procedure (CIN).

RESULTS

There were no significant differences between the groups regarding their baseline demographic and biochemical characteristics, as well as the underlying disease. A total of 6.1% of the patients receiving sodium bicarbonate plus half saline developed CIN as opposed to 6.3% of the patients in the half saline group, which was not statistically different (odds ratio = 0.97; 95% confidence interval, 0.13-7.3; p=1.0).

CONCLUSION

The combination therapy of sodium bicarbonate plus half saline does not offer additional benefits over hydration with half saline alone in the prevention of CIN.

[Intrapleural hypotonic cisplatin treatment for carcinomatous pleuritis in cases of primary lung cancer]

Intrapleural hypotonic cisplatin treatment, which was introduced by Ichinose and colleagues, was performed for 5 cases of primary lung cancer with carcinomatous pleuritis: one case intraoperatively, one case postoperatively and 3 unresected cases. Fifty microg/mL of cisplatin distilled water solution was administered into pleural cavity and drained 10 minutes later in the intraoperative case or 30 minutes later in the bedside cases. No adverse effect was observed. For 2 dissemination- dominant cases, 2 regimens of single cytotoxic agent followed by gefitinib were administered, and the two patients died in 26 and 69 months, respectively. For one case with dissemination and effusion, 5 regimens including combination chemotherapy were administered, and the patient died in 41 months. For 2 effusion-dominant cases, gefitinib was administered and one case is still in PR status for 21 months, and the other was alive for 19 months. Ipsilateral pleural effusion was controlled in all 5 cases. This therapy is helpful for systemic chemotherapy as a main therapeutic means in cases of lung cancer with carcinomatous pleuritis by controlling malignant pleural effusion and relieving dyspnea.

The potassium chloride cotransporter KCC-2 coordinates development of inhibitory neurotransmission and synapse structure in Caenorhabditis elegans

Chloride influx through GABA-gated chloride channels, the primary mechanism by which neural activity is inhibited in the adult mammalian brain, depends on chloride gradients established by the potassium chloride cotransporter KCC2. We used a genetic screen to identify genes important for inhibition of the hermaphrodite-specific motor neurons (HSNs) that stimulate Caenorhabditis elegans egg-laying behavior and discovered mutations in a potassium chloride cotransporter, kcc-2. Functional analysis indicates that, like mammalian KCCs, C. elegans KCC-2 transports chloride, is activated by hypotonic conditions, and is inhibited by the loop diuretic furosemide. KCC-2 appears to establish chloride gradients required for the inhibitory effects of GABA-gated and serotonin-gated chloride channels on C. elegans behavior. In the absence of KCC-2, chloride gradients appear to be altered in neurons and muscles such that normally inhibitory signals become excitatory. kcc-2 is transcriptionally upregulated in the HSN neurons during synapse development. Loss of KCC-2 produces a decrease in the synaptic vesicle population within mature HSN synapses, which apparently compensates for a lack of HSN inhibition, resulting in normal egg-laying behavior. Thus, KCC-2 coordinates the development of inhibitory neurotransmission with synapse maturation to produce mature neural circuits with appropriate activity levels.

Effects of salinity changes on the growth of Dunaliella salina and its isozyme activities of glycerol-3-phosphate dehydrogenase

Dunaliella salina could survive in media containing a wide range of NaCl concentrations ranging from about 0.05 M to saturation (around 5.5 M). Glycerol is an important osmolyte when Dunaliella survive in various salt environments, and G3pdh is a key enzyme in glycerol metabolism. The osmotic response of D. salina was investigated by studying its cell growth, glycerol content change, and isozyme activity of glycerol-3-phosphate dehydrogenase (G3pdh) in different salinities. Results showed that 2.0 M NaCl was the optimal salinity for the growth of D. salina, in which condition the highest glycerol content of 64.02 +/- 3.21 (mean +/- SD) microg/mL was detected. D. salina could rapidly increase or decrease glycerol contents to adapt to hypoosmotic or hyperosmotic environments. The glycerol content declined 52.05% when salinity was changed from 2.0 to 0.5 M NaCl, and the glycerol content increased 43.61% when salinity was increased from 2.0 to 5.0 M NaCl. In the isozyme electrophoresis assay two kinds of isozymes, G3pdh and superoxide dismutase (Sod), were detected synchronously. Interestingly, it was first found that there are five isozymes of G3pdh in D. salina. G3pdh-2 mainly takes effect in moderate to high salinities, whereas the other four isozymes take effect in low salinities, which may provide an important clue for future research on osmoregulation mechanisms.

ROS activate KCl cotransport in nonadherent Ehrlich ascites cells but K+ and Cl- channels in adherent Ehrlich Lettré and NIH3T3 cells

Addition of H(2)O(2) (0.5 mM) to Ehrlich ascites tumor cells under isotonic conditions results in a substantial (22 +/- 1%) reduction in cell volume within 25 min. The cell shrinkage is paralleled by net loss of K(+), which was significant within 8 min, whereas no concomitant increase in the K(+) or Cl(-) conductances could be observed. The H(2)O(2)-induced cell shrinkage was unaffected by the presence of clofilium and clotrimazole, which blocks volume-sensitive and Ca(2+)-activated K(+) channels, respectively, and is unaffected by a raise in extracellular K(+) concentration to a value that eliminates the electrochemical driving force for K(+). On the other hand, the H(2)O(2)-induced cell shrinkage was impaired in the presence of the KCl cotransport inhibitor (dihydro-indenyl)oxyalkanoic acid (DIOA), following substitution of NO(3)(-) for Cl(-), and when the driving force for KCl cotransport was omitted. It is suggested that H(2)O(2) activates electroneutral KCl cotransport in Ehrlich ascites tumor cells and not K(+) and Cl(-) channels. Addition of H(2)O(2) to hypotonically exposed cells accelerates the regulatory volume decrease and the concomitant net loss of K(+), whereas no additional increase in the K(+) and Cl(-) conductance was observed. The effect of H(2)O(2) on cell volume was blocked by the serine-threonine phosphatase inhibitor calyculin A, indicating an important role of serine-threonine phosphorylation in the H(2)O(2)-mediated activation of KCl cotransport in Ehrlich cells. In contrast, addition of H(2)O(2) to adherent cells, e.g., Ehrlich Lettré ascites cells, a subtype of the Ehrlich ascites tumor cells, and NIH3T3 mouse fibroblasts increased the K(+) and Cl(-) conductances after hypotonic cell swelling. Hence, H(2)O(2) induces KCl cotransport or K(+) and Cl(-) channels in nonadherent and adherent cells, respectively.

[Osmotic behavior of mouse embryonic cells subjected to hypotonic shock]

Osmotic adaptation in a blastomere of mouse embryo has been studied by the direct measurement of the cell volume using laser scanning microscopy microtomography followed by quantitative 3D reconstruction. Embryonic cells subjected to hypotonic shock first swelled and then returned to the initial size. At the beginning of osmotic stress, the swelling occurred by the van't Hoff equation with the water permeability coefficient (L(p)) of 0.4 micro x min(-1) atm(-1). The phase of the regulatory volume decrease was not abolished by Na+/K(+)-ATPase inhibition.

Pancreatic affection after acute hypotonic hemodialysis

Four male outpatients, all on stable long-term hemodialysis, were by accident simultaneously exposed to hypotonic dialysate. Three of them developed increased serum amylase values and one died from the consequences of a fulminant pancreatitis, which had been verified by laparatomy.

Hypotonic activation of volume-sensitive outwardly rectifying anion channels (VSOACs) requires coordinated remodeling of subcortical and perinuclear actin filaments

Cell volume regulation requires activation of volume-sensitive outwardly rectifying anion channels (VSOACs). The actin cytoskeleton may participate in the activation of VSOACs but the roles of the two major actin pools remain undefined. We hypothesized that structural reorganization of both subcortical and perinuclear actin filaments (F-actin) contributes to the hypotonic activation of VSOACs. Hypotonic stress of pulmonary artery smooth muscle cells (PASMCs) was associated with reorganization of both peripheral and perinuclear F-actin, and with activation of VSOACs. Preincubation with cytochalasin D caused prominent dissociation of perinuclear, but not of subcortical F-actin. Cytochalasin D failed to induce isotonic activation and delayed the hypotonic activation of VSOACs. F-actin stabilization by phalloidin delayed both the hypotonic stress-induced dissociation of membrane-associated actin filaments and the activation kinetics of VSOACs. PKCepsilon, which was proposed to phosphorylate and inhibit VSOACs, colocalized primarily with F-actin and the net kinase activity remained unchanged during hypotonic cell swelling. In conclusion, normal hypotonic activation of VSOACs requires disruption of peripheral F-actin but intact perinuclear F-actin; interference with this pattern of actin reorganization delays the activation kinetics of VSOACs. The cell swelling-induced peripheral actin dissociation may underlie the observed translocation of PKCepsilon, which leads to a net decrease of PKCepsilon inhibitory activity in submembranous sites. Thus, reorganization of actin and PKCepsilon may establish conditions for mechano- and/or signal transduction-mediated activation of VSOACs.

Changes in osmolality modulate voltage-gated sodium channels in trigeminal ganglion neurons

Voltage-gated sodium channels (VGSCs) are important channels which participate in many physiological functions. Whether VGSCs can be modulated by changes in osmolality in trigeminal ganglion (TG) neurons remains unknown. In this study, by using whole-cell patch clamp techniques, we tested the effects of hypo- and hypertonicity on VGSCs in cultured TG neurons. Our data show that tetrodotoxin-resistant sodium current (TTX-R current) was inhibited in the presence of hypo- and hypertonic solutions. In hypertonic solutions both voltage-dependent activation and inactivation curves shifted to the hyperpolarizing direction, while in hypotonic solutions only inactivation curve shifted to the hyperpolarizing direction. Transient Receptor Potential Vanilloid 4 (TRPV4) receptor activator mimicked the inhibition of TTX-R current by hypotonicity and the inhibition by hypotonicity was markedly attenuated by TRPV4 receptor blocker and in TRPV4(-/-) mice TG neurons. We also demonstrate that the inhibition of PKA selectively attenuated hypotonicity-induced inhibition, whereas antagonism of PLC and PI3K selectively attenuated hypertonicity-induced inhibition. We conclude that although hypo- and hypertonicity have similar effect on VGSCs, receptor and intracellular signaling pathways are different for hypo- versus hypertonicity-induced inhibition of TTX-R current.

[Nucleoplasmic viscosity of living cells investigated by fluorescence correlation spectroscopy]

In order to non-invasively investigate nucleoplasmic viscosity in real time with good temporal resolution, the present study firstly introduced a new method based on fluorescence correlation spectroscopy (FCS). FCS is a kind of single-molecule technique with high temporal and spatial resolution to analyze the dynamics of fluorescent molecules in nanomolar concentration. Through a time correlation analysis of spontaneous intensity fluctuations, this technique in conjunction with EGFP as a probe is capable of determining nucleoplasmic viscosity in terms of Stokes-Einstein equation as well as its corresponding analysis of the diffusion coefficient for EGFP in the nucleus. The results showed that nucleoplasmic viscosity of ASTC-a-1 cells and HeLa cells were respectively (2.55 +/- 0.61) cP and (2.04 +/- 0.49) cP at pH 7.4 and 37 degrees C, consistent with the results by traditional methods, and nucleoplasmic viscosity was found to be larger than cytoplasmic viscosity. Meanwhile, the real-time analysis of nucleoplasmic viscosity in living cells exposed to hypotonic media proved that FCS could be used to track the changing rheological characteristics of the nucleoplasm in living cells. Taken together, this study suggests that FCS provides an accurate and non-invasive method to investigate the microenvironment in living cells on the femtoliter scale and it can be used as a powerful tool in researches on the dynamical processes of intracellular molecules.

Effect of oviductal proteins on structural and functional characteristics of cryopreserved sperm in Murrah buffaloes

The present study was undertaken to elucidate the effect of non-luteal oviductal proteins on sperm characteristics in Murrah buffaloes. Oviducts from healthy buffaloes were collected immediately after slaughter and the oestrous cycle phase was determined as either luteal or non-luteal based on ovarian morphology. Non-luteal oviducts (n = 80) were flushed from the isthmic end of the oviduct with PBS, fluid was centrifuged at 10,000 g at 4 degrees C for 20 min and then dialysed and clarified. The supernatant obtained was lyophilized to concentrate the protein and stored at -20 degrees C till use. Sixteen good quality ejaculates from four Murrah buffalo bulls were collected using an artificial vagina. After fresh semen analysis, each ejaculate was split into two parts and extended in Tris-citrate-egg yolk glycerol dilutor. Part I of the split ejaculate was treated with non-luteal oviductal proteins at the dose rate of 1 mg/ml of diluted semen, while part II remained as control. The extended semen was equilibrated for 4 h at 5 degrees C, filled in 0.5 ml French straws, exposed to LN(2) vapour, plunged into LN(2) and then stored at -196 degrees C. The equilibrated and frozen-thawed semen was evaluated for sperm motility, viability, acrosomal integrity, cervical mucus penetration test and hypo-osmotic sperm swelling test (HOST). In frozen-thawed semen, the percentage of sperm motility, viability and acrosomal integrity was significantly (p < 0.05) higher in the treatment group compared to the control group. The incorporation of non-luteal oviductal proteins in the extender increased the ability of sperm to penetrate cervical mucus both after equilibration and the freeze-thaw process. Similarly, the proportion of sperm with intact plasma membrane, as revealed by HOST values, was also significantly (p < 0.05) higher in the treatment group (32.6%) than the control group (27%) in frozen-thawed semen. It was inferred that incorporation of non-luteal whole oviductal fluid proteins improved the sperm quality in frozen-thawed semen in Murrah buffaloes.

Preparation and Validation of Carrier Human Erythrocytes Loaded by Bovine Serum Albumin as a Model Antigen/Protein

Erythrocytes as the most readily available and abundant cells within the body have been studied extensively for their potential application as drug delivery carries. In this study, human erythrocytes were loaded by bovine serum albumin (BSA) as a model antigen/protein using hypotonic preswelling method for targeted delivery of this antigen-to antigen-presenting cells. The average loaded amount, efficiency of entrapment, and cell recovery upon loading procedure were 1979.25 +/- 9.4 microg, 30.06 +/- 0.20%, and 87.53 +/- 0.66%, respectively. The total BSA recovery upon loading procedure was 97.20 +/- 4.90%. The apparent mechanism of entrapment was simple concentration-based gradient in/out the cells with some minor limiting factors against protein entry into the cells. We have shown that the intra- and intersubject variations of the method were interestingly low (i.e., less than 5% in all cases).

Evaluation of human sperm membrane integrity using the water test and the hypoosmotic test

The objective of the study was to compare the water test and the hypoosmotic test (HOS) in the assessment of the human sperm membrane. A total of 686 semen samples from human male donors were subjected to water and HOS tests after routine semen evaluation. The mean percentage of swollen spermatozoa was 71.8 +/- 9.6% in the HOS test and 67.8 +/- 9.4% for the water test; these values were not statistically different. The correlation of coefficients between the water test and the HOS test was highly significant whether the values for the HOS test were higher or lower than 60% (P < 0.001). A poor correlation was obtained when the two tests were compared for sperm counts either higher or lower than 20 x 6 ml-1 and when the results for both tests were compared with the percentage of eosin-Y staining spermatozoa. A poor correlation was also obtained when the results of each test were compared with eosin-Y staining spermatozoa in normal and abnormal semen samples. The coefficient of regression between the two tests showed a high correlation (P < 0.001). In conclusion, even though a high correlation between the HOS test and water test was observed in this study, it is not possible to recommend assessment of sperm membrane integrity using the water test and the consequent replacement of the HOS test in routine practice. Further studies are necessary to establish the best test for sperm vitality.

Hypotonicity and peptide discharge from a single vesicle

Neuroendocrine secretory vesicles discharge their cargo in response to a stimulus, but the nature of this event is poorly understood. We studied the release of the pituitary hormone prolactin by hypotonicity, because this hormone also contributes to osmoregulation. In perfused rat lactotrophs, hypotonicity resulted in a transient increase followed by a sustained depression of prolactin release, as monitored by radioimmunoassay. In single cells imaged by confocal microscopy, hypotonicity elicited discharge of the fluorescently labeled atrial natriuretic peptide cargo from approximately 2% of vesicles/cell. In contrast, KCl-induced depolarization resulted in a response of approximately 10% of vesicles/cell, with different unloading/loading time course of the two fluorescent probes. In cell-attached studies, discrete changes in membrane capacitance were recorded in both unstimulated and stimulated conditions, reflecting single vesicle fusion/fissions with the plasma membrane. In stimulated cells, the probability of occurrence of full fusion events was low and unchanged, whereas over 95% of fusion events were transient, with the open fusion pore probability, the average pore dwell-time, the frequency of occurrence, and the fusion pore conductance increased. Hypotonicity only rarely elicited new fusion events in silent membrane patches. The results indicate that, in hypotonicity-stimulated lactotrophs, transient vesicle fusion mediates hormone release.

[Ion channel mechanism of regulatory volume decrease in human epithelial cells]

AIM

To observe the regulatory volume decrease (RVD) process of human intestine cells and investigate its ion channel mechanism.

METHODS

Cultured human intestine cells were exposed to hypotonic solution and the cell volume was measured using Coulter Counter System. RT-PCR was explored to detect the mRNA expression of Ca(2+) -activated K+ channel.

RESULTS

Human intestine cells showed a RVD process and this process could be blocked by Cl- channel blocker NPPB and K+ channel blocker TEA. Further results demonstrated the subtype of K+ channel involved in RVD was an intermediate-conductance, Ca(2+) -activated K+ channel (IK) because of its high sensitivity to clotrimazole. RT-PCR results also showed the expression of IK in this cell line.

CONCLUSION

The RVD process of intestine cell was dependent on the parallel activation of Cl- channel and K+ channel. The subtype of K+ channel in volved in the RVD process was IK channel.

Five-day storage of platelet concentrates. I. In-vitro studies

Platelet concentrates have been prepared in standard PVC (PL-146) packs and polyolefin (PL-732) packs. Comparison of pH and hypotonic stress of the platelet concentrates has shown that significantly improved values are obtained after storage of the concentrates at 22 C in PL-732 packs for 5 days than after storage for 3 days in PL-146 packs. There was no significant difference under conditions of the test between vertical and horizontal agitation of the concentrates. Since both pH and hypotonic stress recovery have shown a relationship to post-transfusion recovery and viability, evidence is presented to support the 5-day storage period of concentrates prepared and stored in PL-732 packs.

Cotransport systems in the brush border membrane of the human placenta

The cotransport systems present in the brush border membrane of the human placental syncytiotrophoblast are reviewed. Attention is focused on the systems that are powered by the electrochemical gradient of Na+ (for example, for neutral amino acids but not for glucose), and on recently described systems in which K+ flux is coupled to C1- flux or to that for Na+ and C1-. These systems are similar to those found in other tissues and may be significant for net trans-placental transport and its control, as well as for the regulation of placental trophoblast volume.