Osmotic response during kidney perfusion with cryoprotectant in isotonic or hypotonic vehicle solution

Organ cryopreservation would revolutionize transplantation by overcoming the shelf-life limitations of conventional organ storage. To prepare an organ for cryopreservation, it is first perfused with cryoprotectants (CPAs). These chemicals can enable vitrification during cooling, preventing ice damage. However, CPAs can also cause toxicity and osmotic damage. It is a major challenge to find the optimal balance between protecting the cells from ice and avoiding CPA-induced damage. In this study, we examined the organ perfusion process to shed light on phenomena relevant to cryopreservation protocol design, including changes in organ size and vascular resistance. In particular, we compared perfusion of kidneys (porcine and human) with CPA in either hypotonic or isotonic vehicle solution. Our results demonstrate that CPA perfusion causes kidney mass changes consistent with the shrink-swell response observed in cells. This response was observed when the kidneys were relatively fresh, but disappeared after prolonged warm and/or cold ischemia. Perfusion with CPA in a hypotonic vehicle solution led to a significant increase in vascular resistance, suggesting reduced capillary diameter due to cell swelling. This could be reversed by switching to perfusion with CPA in isotonic vehicle solution. Hypotonic vehicle solution did not cause notable osmotic damage, as evidenced by low levels of lactate dehydrogenase (LDH) in the effluent, and it did not have a statistically significant effect on the delivery of CPA into the kidney, as assessed by computed tomography (CT). Overall, our results show that CPA vehicle solution tonicity affects organ size and vascular resistance, which may have important implications for cryopreservation protocol design.

[Perioperative Management in Pediatric Neurosurgery]

Appropriate perioperative management can facilitate good outcomes in pediatric neurosurgical patients. This section discusses infusion therapy, prophylactic antibiotics, and antiepileptic drugs in the perioperative management of pediatric neurosurgical patients. Fluid requirements were calculated using the Holiday and Segar formula and the 4-2-1 rule for determining hourly infusion requirements based on metabolic rate and body weight. Recently, the risk of hyponatremia with the use of hypotonic solutions has been reported, and an isotonic electrolyte solution with 1-2.5% glucose is recommended for maintenance infusions in the perioperative period. Pediatric perioperative prophylactic antibiotics have been recommended as follows: application of cephazolin(30 mg/kg)with a redosing interval of 3 h intraoperatively and continuation for 48 h or less postoperatively. However, even for shunt surgery, there are currently no evidence-based protocols regarding specific antibiotic recommendations or the duration of prophylactic antibiotics. Early antiepileptic prophylaxis is recommended in cases of severe head trauma in children, especially infants. Available intravenous antiepileptic drugs should be used with an understanding of their indications, characteristics, and side effects.

Abdominoplasty Panniculus as a Source for Human Acellular Dermis: A Preliminary Report

BACKGROUND

In extensive deep dermal burn injuries, split-thickness skin graft (STSG) has been the most preferred treatment option for resurfacing burn wounds. A thick split-thickness skin graft is ideal for preventing graft contracture but is associated with delayed donor healing and the lack of adequate donor skin. When applied with STSG, the dermal substitutes offer better-reconstructed skin than STSG alone. Human-derived acellular dermal matrix (HADM) obtained from cadaver skin is a dermal equivalent with good clinical outcomes. However, high cost and limited cadaver donor skin availability limit its clinical utility. Developing a low-cost preparation method and finding an alternate source of human donated skin can help reduce the cost. The objective of this study was to explore the feasibility of making HADM from abdominoplasty panniculus skin.

METHODS

Skin samples were collected from the abdominoplasty panniculus of ten eligible donors with their informed consent. A combination of low-cost reagents-sodium chloride and hypotonic solution (water for injection) was used for decellularizing the skin. Characterization of the prepared Acellular Dermis Matrix prototype was done.

RESULTS

The skin was deepidermized with one molar NaCl treatment at 37 °C for 24 h. The deepidermized dermis became acellular with hypotonic solution treatment at 4 °C for two weeks. The hematoxylin and eosin staining and cytotoxicity test confirmed the acellularity and non-cytotoxicity of the prepared HADM prototype. The HADM prototype also facilitated the formation of neo-epithelium in the 3D cell co-culture model.

CONCLUSION

This study confirms that abdominoplasty panniculus can be a viable alternative for HADM preparation. Further characterization studies are required to prove the concept.

Three-Phase Coexistence in Binary Charged Lipid Membranes in a Hypotonic Solution

We investigated the phase separation of dioleoylphosphatidylserine (DOPS) and dipalmitoylphosphatidylcholine (DPPC) in giant unilamellar vesicles in a hypotonic solution using fluorescence and confocal laser scanning microscopy. Although phase separation in charged lipid membranes is generally suppressed by the electrostatic repulsion between the charged headgroups, osmotic stress can promote the formation of charged lipid domains. Interestingly, we observed a three-phase coexistence even in the DOPS/DPPC binary lipid mixtures. The three phases were DPPC-rich, dissociated DOPS-rich, and nondissociated DOPS-rich phases. The two forms of DOPS were found to coexist owing to the ionization of the DOPS headgroup, such that the system could be regarded as quasi-ternary. The three formed phases with differently ionized DOPS domains were successfully identified experimentally by monitoring the adsorption of positively charged particles. In addition, coarse-grained molecular dynamics simulations confirmed the stability of the three-phase coexistence. Attraction mediated by hydrogen bonding between protonated DOPS molecules and reduction of the electrostatic interactions at the domain boundaries stabilized the three-phase coexistence.

Controllable Fabrication of Inhomogeneous Microcapsules for Triggered Release by Osmotic Pressure

Inhomogeneous microcapsules that can encapsulate various cargo for controlled release triggered by osmotic shock are designed and reported. The microcapsules are fabricated using a microfluidic approach and the inhomogeneity of shell thickness in the microcapsules can be controlled by tuning the flow rate ratio of the middle phase to the inner phase. This study demonstrates the swelling of these inhomogeneous microcapsules begins at the thinnest part of shell and eventually leads to rupture at the weak spot with a low osmotic pressure. Systematic studies indicate the rupture fraction of these microcapsules increases with increasing inhomogeneity, while the rupture osmotic pressure decreases linearly with increasing inhomogeneity. The inhomogeneous microcapsules are demonstrated to be impermeable to small probe molecules, which enables long-term storage. Thus, these microcapsules can be used for long-term storage of enzymes, which can be controllably released through osmotic shock without impairing their biological activity. The study provides a new approach to design effective carriers to encapsulate biomolecules and release them on-demand upon applying osmotic shock.

Characterization of carrier erythrocytes for biosensing applications

Erythrocyte abundance, mobility, and carrying capacity make them attractive as a platform for blood analyte sensing as well as for drug delivery. Sensor-loaded erythrocytes, dubbed erythrosensors, could be reinfused into the bloodstream, excited noninvasively through the skin, and used to provide measurement of analyte levels in the bloodstream. Several techniques to load erythrocytes, thus creating carrier erythrocytes, exist. However, their cellular characteristics remain largely unstudied. Changes in cellular characteristics lead to removal from the bloodstream. We hypothesize that erythrosensors need to maintain native erythrocytes’ (NEs) characteristics to serve as a long-term sensing platform. Here, we investigate two loading techniques and the properties of the resulting erythrosensors. For loading, hypotonic dilution requires a hypotonic solution while electroporation relies on electrical pulses to perforate the erythrocyte membrane. We analyze the resulting erythrosensor signal, size, morphology, and hemoglobin content. Although the resulting erythrosensors exhibit morphological changes, their size was comparable with NEs. The hypotonic dilution technique was found to load erythrosensors much more efficiently than electroporation, and the sensors were loaded throughout the volume of the erythrosensors. Finally, both techniques resulted in significant loss of hemoglobin. This study points to the need for continued development of loading techniques that better preserve NE characteristics.

Osmotic Separation of Pancreatic Exocrine Cells from Crude Islet Cell Preparations

A novel approach is introduced here to selectively lyse exocrine cells in an islet preparation by hypoosmotic treatment. Time to hypotonic cell lysis required for the islet cells was much longer than that for the exocrine cells, which permits a possibility of selectively killing the exocrine cells by hypotonic treatment. The first set of experiments was designed to select an appropriate osmolality for the hypotonic treatment. Kinetic changes in cell volume in response to extracellular anisosmolalities (30 to 90 mOsm/kg) were recorded using an electronic particle counter. The results indicated that, when exposed to a 30 mOsm/kg solution, islet cells swelled slowly to reach volumetric equilibrium in approximately 3 min. There was no significant hypotonic cell lysis observed even at the end of 4 min (n = 4). In contrast, pancreatic exocrine cells, when exposed to the same solution, expanded rapidly to the lytic volume and burst within 30 s. Significant exocrine cell lysis was invariably achieved within 30 s when cells were exposed to the osmolalities below 60 mOsm/kg. For osmolalities between 70 to 80 mOsm/kg, exocrine cell lysis was highly variable. When cells were exposed to 80 to 90 mOsm/kg, no significant cell lysis was observed. Thus, an osmolality of 50 mOsm/kg is recommended for hypotonic treatment, as it maximizes the lysis of exocrine cells without unnecessarily stressing (osmotically) the islet cells. The second set of experiments (time-course experiments, 20 to 120 s) was designed to determine the length of exposure time for which the exocrine cells were irreversibly damaged but the islet cells had only swollen to such a degree that cell function is restored upon returning to an isotonic condition. Viability of the hypotonic treated cells was evaluated at two different levels: membrane integrity, measured by combined fluorescent dye staining with propidium iodide (PI) and carboxyfluorescein diacetate (CFDA), and mitochondrial function, measured by colorimetric MTT assay. The results showed that hypotonic treatment in a 50 mOsm/kg solution for 30 s resulted in over 85% loss of the membrane integrity for the exocrine cells. About 90% of these membrane lysed cells lost mitochondrial function (n = 3). By contrast, under the same treatment, less than 15% of the islet cells lost membrane integrity and mitochondrial function (n = 3). In conclusion, hypotonic treatment with a 50 mOsm/kg solution for 20 to 30 s at room temperature is sufficient to lyse the majority of the contaminating exocrine cells in an islet cell preparation, while maintaining function in the islet cells.

Enema ion compositions for enhancing colorectal drug delivery

Delivering drugs to the colorectum by enema has advantages for treating or preventing both local and systemic diseases. However, the properties of the enema itself are not typically exploited for improving drug delivery. Sodium ions are actively pumped out of the lumen of the colon, which is followed by osmotically-driven water absorption, so we hypothesized that this natural mechanism could be exploited to drive nanoparticles and drugs to the colorectal tissue surface. Here, we report that sodium-based, absorption-inducing (hypotonic) enemas rapidly transport hydrophilic drugs and non-mucoadhesive, mucus penetrating nanoparticles (MPP), deep into the colorectal folds to reach virtually the entire colorectal epithelial surface. In contrast, isotonic and secretion-inducing (hypertonic) vehicles led to non-uniform, poor surface coverage. Sodium-based enemas induced rapid fluid absorption even when moderately hyper-osmolal (~350 mOsm) compared to blood (~300 mOsm), which suggests that active sodium absorption plays a key role in osmosis-driven fluid uptake. We then used tenofovir, an antiretroviral drug in clinical trials for preventing HIV, to test the effects of enema composition on local and systemic drug delivery. We found that strongly hypotonic and hypertonic enemas caused rapid systemic drug uptake, whereas moderately hypotonic enemas with ion compositions similar to feces resulted in high local tissue levels with minimal systemic drug exposure. Similarly, moderately hypotonic enemas provided improved local drug retention in colorectal tissue, whereas hypertonic and isotonic enemas provided markedly reduced drug retention in colorectal tissue. Lastly, we found that moderately hypotonic enema formulations caused little to no detectable epithelial damage, while hypertonic solutions caused significant damage, including epithelial sloughing; the epithelial damage caused increased systemic drug absorption and penetration of MPP into colorectal tissue, a potential advantage in certain drug delivery applications. In summary, we illustrate that enema composition can be adjusted to maximize local versus systemic drug delivery, and that mildly hypotonic, sodium-based vehicles can provide uniform drug and MPP delivery in the colon that maximizes local drug concentrations.

The use of erythrocytes for delivery of chemotherapeutic agents to the reticuloendothelial system

The object of our work is to define the possible role of hypotonically loaded erythrocytes as carriers to target drugs to the reticuloendothelial system. We have examined choices of drugs for loading into the erythrocytes and have considered methods of altering potentially useful agents so that they will load. We have demonstrated that the delivery of bleomycin to the reticuloendothelial system of mice, inside erythrocyte carriers, potentiates the effect of this drug on phagocytosis. We speculate, that this targeted delivery of bleomycin to phagocytes could be beneficial in the treatment of diseases characterized by an important phagocytic component.

[THE ROLE OF HYDROGEN SULFIDE IN VOLUME-DEPENDENT MECHANISMS OF REGULATION OF VASCULAR SMOOTH MUSCLE CELLS CONTRACTILE ACTIVITY]

The hydrogen sulfide (H2S) influence on the contractile activity of vascular smooth muscle cells (SMC) was studied on endothelium-denuded aortic ring segments of male Wistar rats with method of mechanography. Contractions of SMS were induced by incubation in high potassium solution as well as in hyper-, hypo- and isosmotic solutions. 5-100 LM of H2S donor--sodium hydrosulfide (NaHS) increased mechanical tension of SMC precontracted with high potassium solution that was abolished by bumetanide--the inhibitor of Na+, K+, 2Cl(-) -cotransporter (NKCC), but 100-1000 microM of NaHS relaxed SMS. NaHS (10 microM) increased the amplitude of hyper- and isosmotic contraction, but not of hyposmotic contraction. NaHS (ImM) decreased the amplitude of hyper-, iso-, and hyposmotic contractions. The direct measurements of NKCC activity with radionuclide method showed an increase in NKCC activity under the action of 5-100 microM of NaHS. These findings suggest that low concentrations of H2S participate in the NKCC activation. This mechanism underlines constrictive action of H2S on smooth muscle cells.

140 mmol/L of sodium versus 77 mmol/L of sodium in maintenance intravenous fluid therapy for children in hospital (PIMS): a randomised controlled double-blind trial

BACKGROUND

Use of hypotonic intravenous fluid to maintain hydration in children in hospital has been associated with hyponatraemia, leading to neurological morbidity and mortality. We aimed to assess whether use of fluid solutions with a higher sodium concentration reduced the risk of hyponatraemia compared with use of hypotonic solutions.

METHODS

We did a randomised controlled double-blind trial of children admitted to The Royal Children's Hospital (Melbourne, VIC, Australia) who needed intravenous maintenance hydration for 6 h or longer. With an online randomisation system that used unequal block sizes, we randomly assigned patients (1:1) to receive either isotonic intravenous fluid containing 140 mmol/L of sodium (Na140) or hypotonic fluid containing 77 mmol/L of sodium (Na77) for 72 h or until their intravenous fluid rate decreased to lower than 50% of the standard maintenance rate. We stratified assignment by baseline sodium concentrations. Study investigators, treating clinicians, nurses, and patients were masked to treatment assignment. The primary outcome was occurrence of hyponatraemia (serum sodium concentration <135 mmol/L with a decrease of at least 3 mmol/L from baseline) during the treatment period, analysed by intention to treat. The trial was registered with the Australian New Zealand Clinical Trials Registry, number ACTRN1260900924257.

FINDINGS

Between Feb 2, 2010, and Jan 29, 2013, we randomly assigned 690 patients. Of these patients, primary outcome data were available for 319 who received Na140 and 322 who received Na77. Fewer patients given Na140 than those given Na77 developed hyponatraemia (12 patients [4%] vs 35 [11%]; odds ratio [OR] 0·31, 95% CI 0·16-0·61; p=0·001). No clinically apparent cerebral oedema occurred in either group. Eight patients in the Na140 group (two potentially related to intravenous fluid) and four in the Na77 group (none related to intravenous fluid) developed serious adverse events during the treatment period. One patient in the Na140 had seizures during the treatment period compared with seven who received Na77.

INTERPRETATION

Use of isotonic intravenous fluid with a sodium concentration of 140 mmol/L had a lower risk of hyponatraemia without an increase in adverse effects than did fluid containing 77 mmol/L of sodium. An isotonic fluid should be used as intravenous fluid for maintenance hydration in children.

FUNDING

National Health and Medical Research Council, Murdoch Childrens Research Institute, The Royal Children's Hospital, and the Australian and New Zealand College of Anaesthetists.

[Hypotonic Versus Isotonic Electrolyte Solution for Perioperative Fluid Therapy in Infants]

BACKGROUND

This study was designed to evaluate the effects of perioperative administration of an isotonic electrolyte solution with 1% glucose (IT) on blood sodium (Na+) and blood glucose (BG) concentrations in pediatric patients < 1-year-old undergoing plastic surgery in comparison with a conventional hypotonic electrolyte solution with 2.6% glucose (HT).

METHODS

Fifty Patients were randomly allocated to HT group and IT group. Na+ and BG were measured at induction of anesthesia (Tind), the end of surgery (Tend), and 4 hours after surgery (T4h).

RESULTS

Patient characteristics were similar for the 2 groups. In the HT group, Na+ at Tend insignificantly dropped compared with that at Tind, whereas in the IT group Na+ was significantly elevated. Na+ at T4h significantly increased compared with that at Tend in each group. No cases developed new dysnatremia or dysglycemia in IT group. The incidence of hyponatremia at Tend was significantly lower in the IT group. A positive correlation between intraoperative Na+ concentration changes and the infusion duration was observed in the IT group.

CONCLUSIONS

Isotonic solution with 1% glucose is suggested to be safe in infants during and after surgery.

Characterizing osmotic lysis kinetics under microfluidic hydrodynamic focusing for erythrocyte fragility studies

The biomechanics of erythrocytes, determined by the membrane integrity and cytoskeletal structure, provides critical information on diseases such as diabetes mellitus, myocardial infarction, hypertension, and sickle cell anemia. Here we demonstrate a simple microfluidic tool for examining erythrocyte fragility based on characterizing osmotic lysis kinetics. Hydrodynamic focusing is used for generating rapid dilution of the buffer and producing lysis of erythrocytes during their flow. The lysis kinetics are tracked by monitoring the release of intracellular contents from cells via recording the light intensity of erythrocytes at various locations in the channel. Such release profile reflects sensitively the changes in erythrocyte fragility induced by chemical, heating, and glucose treatment. Our tool provides a simple approach for probing red blood cell fragility in both basic research and clinical settings.

Purinergic receptors and regulatory volume decrease in seabream (Sparus aurata) hepatocytes: a videometric study

The response of isolated hepatocytes of Sparus aurata to hypotonic stress was studied by the aid of videometric methods with the aim to investigate the possible involvement of ATP in the regulatory volume decrease (RVD). This study confirms our previous observations showing the ability of these cells to undergo RVD. In addition, it shows that the homeostatic response was inhibited by apyrase, an ATP scavenger, thus suggesting the involvement of extracellular ATP in the RVD response. Experiments performed in the presence of ATPγS or adenosine, agonists of P(2) and P(1) receptors respectively, and in the presence of suramin or 8-PT, antagonists of P(2) and P(1) receptors respectively, suggest that ATP exerts its stimulatory effect on the homeostatic response by interacting with P(2) receptors. On the other hand, the activation of P(1) receptors by ATP metabolites produces opposite effects. In an attempt to clarify the mechanisms involved in ATP release from the cell, we performed some experiments with known inhibitors of the possible mechanisms of regulated ATP release. The results we obtained let us to suppose that the mechanism allowing the exit of ATP from the cell is verapamil sensitive suggesting the involvement of the P-glycoprotein.

Regulation of colon cancer cell migration and invasion by CLIC1-mediated RVD

The metastasis of colorectal cancer is one of the most common causes of death in the world. In this investigation, we used the human colon cancer cell lines LOVO and HT29 as model systems to determine the role of the chloride intracellular channel 1 (CLIC1) in the metastasis of colonic cancer. In the present study, we found that regulatory volume decrease (RVD) capacity was markedly up-regulated in LOVO cells, which are characterized by a high metastatic potential. Functionally suppressing CLIC1 using the specific chloride intracellular channel 1 blocker Indanyloxyacetic acid 94 inhibited RVD and decreased the migration and invasion of colon cancer cells. Moreover, these effects occurred in a dose-dependent manner. The migration and invasion abilities in two cell lines also were inhibited by the knockdown of CLIC1 using small interfering RNA transfection. The mRNA and protein expression of CLIC1 is up-regulated in LOVO cells. In human colon cancer cells, CLIC1 is primarily located in the plasma membrane, where it functions as a chloride channel. Taken together, the results suggest that CLIC1 modulates the metastasis of colon cancer through its RVD-mediating chloride channel function. This study demonstrates, for the first time, that CLIC1 regulates the migration and invasion of colon cancer.

Isotonic versus hypotonic fluid supplementation in term neonates with severe hyperbilirubinemia - a double-blind, randomized, controlled trial

AIM

To compare the incidence of hyponatremia in full-term neonates with severe hyperbilirubinemia, receiving intravenous fluid supplementation with 0.2% saline in 5% dextrose versus 0.9% saline in 5% dextrose, to prevent blood exchange transfusion (BET).

METHODS

In this double-blind, randomized, controlled trial, full-term newborns (≥37 weeks), appropriate for gestational age, with severe non-haemolytic hyperbilirubinemia (serum bilirubin ≥ 20 mg/dL) were enrolled. Eligible neonates were randomized to receive either 0.2% saline in 5% dextrose (hypotonic fluid group) or 0.9% saline in 5% dextrose (isotonic fluid group) over 8 hrs, in addition to phototherapy. The primary outcome was proportion of neonates developing hyponatremia (serum Na < 135 mmol/L) after 8 h.

RESULTS

Forty-two neonates were analysed in each group. Proportion of neonates developing hyponatremia after 8 h was higher in hypotonic fluid group as compared to isotonic fluid group (48.8% vs. 10.5%, p < 0.001). However, a larger proportion in isotonic fluid group developed hypernatremia (39.5% vs. 12.2%, p < 0.001). The rate of BET was similar in both groups.

CONCLUSION

In full-term neonates with severe hyperbilirubinemia, administration of hypotonic fluid to prevent BET was associated with a higher incidence of hyponatremia while isotonic fluid was associated with an increased incidence of hypernatremia.

[Cyto B dependent and ouabain insensitive regulatory volume decrease in bicellular mouse embryo]

Mouse single-cell embryos exhibit robust Regulatory Volume Decrease (RVD). In what manner the very early mammalian embryo following zygote stage is appreciably altered by the anisotonic extracellular solution is, as yet, totally unclear. Little attention was paid to this direction since there was no way to determine the blastomere volume. This work has served to quantitatively investigate the osmotic response of bicellular mouse embryos employing Laser Scanning Microtomography (LSM) followed with three-dimensional reconstruction (3 DR). We have shown that bicellular mouse embryos in hypotonic Dulbecco's experience RVD. Embryonic cells subjected to hyposmolar exhibit rapid osmotic swelling followed by gradual shrinking back toward their original volume. The van't Hoff law defines swelling phase with the effective hydraulic conductivity of 0.3 micron x min(-1) x atm(-1). Water release during RVD in bicellular mouse embryos is abolished by Cytochalasin B (Cyto B) and the volume recovery is insensitive to ouabain treatment.

Regulatory volume response following hypotonic stress in Atlantic salmon erythrocytes

The purpose of this study was to examine regulatory volume decrease (RVD) in Atlantic salmon red blood cells (RBCs). Osmotic fragility was determined optically, mean cell volume was measured electronically, and changes in intracellular Ca(2+) concentration were visualized using fluorescence microscopy and fluo-4-AM. Cells displayed an increase in osmotic fragility and an inhibition of volume recovery following hypotonic shock when they were exposed to a high taurine Ringer or when placed in a high K(+) medium. Interestingly, RVD in cells from fish collected during the summer depended more on taurine efflux, whereas fall cells relied more on the loss of K(+). In addition, RVD in fall cells was prevented with the K(+) channel inhibitor quinine, whereas the ionophore gramicidin decreased osmotic fragility and potentiated volume recovery. Further, hypotonic shock (0.5X Ringer) for both summer and fall cells caused an increase in cytosolic Ca(2+), which resulted from influx of this ion because it was not observed when extracellular Ca(2+) was chelated with EGTA (10 nM free Ca(2+)). Cells exposed to a low Ca(2+) hypotonic Ringer also had a greater osmotic fragility and failed to recover from hypotonic swelling. Finally, inhibition of phospholipase A(2) with ONO-RS-082 blocked volume recovery. In conclusion, Atlantic salmon RBCs displayed volume decrease in response to hypotonic shock, which depended on a swelling-induced influx of Ca(2+) and an increase in the efflux of K(+) and taurine.

Problem-solving test: submitochondrial localization of proteins

Terms to be familiar with before you start to solve the test: mitochondria, outer membrane, inner membrane, intermembrane space, mitochondrial matrix, mitochondrial fraction, cell fractionation by differential centrifugation, pellet, supernatant, detergents, phenol, cytosolic fraction, integral and peripheral membrane proteins, hypotonic solution, SDS-polyacrylamide gel electrophoresis, Western blotting.

Effects of acute low doses of gamma-radiation on erythrocytes membrane

It is believed that any dose of ionizing radiation may damage cells and that the mutated cells could develop into cancer cells. Additionally, results of research performed over the past century on the effects of low doses of ionizing radiation on biological organisms show beneficial health effects, called hormesis. Much less is known about the cellular response to low doses of ionizing radiation, such as those typical for medical diagnostic procedures, normal occupational exposures or cosmic-ray exposures at flight altitudes. Extrapolating from the effects observed at higher doses to predict changes in cells after low-dose exposure is problematic. We examined the biological effects of low doses (0.01-0.3 Gy) of γ-radiation on the membrane characteristics of erythrocytes of albino rats and carried out osmotic fragility tests and Fourier transform infrared spectroscopy (FTIR). Our results indicate that the lowest three doses in the investigated radiation range, i.e., 0.01, 0.025 and 0.05 Gy, resulted in positive effects on the erythrocyte membranes, while a dose of 0.1 Gy appeared to represent the limiting threshold dose of those positive effects. Doses higher than 0.1 Gy were associated with the denaturation of erythrocyte proteins.

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.