Physiological Osmolality Research Articles

Storage Media for Dental Avulsion: A Literature Review

Tooth avulsion is a critical dental emergency where immediate and appropriate management is essential for the successful reimplantation of the tooth. The choice of storage medium during the extra-alveolar period significantly impacts the viability of periodontal ligament (PDL) cells, crucial for the long-term retention of the replanted tooth. This review examines various storage media proposed for avulsed teeth, assessing their pH, osmolality, and overall efficacy in maintaining PDL cell viability. A comprehensive literature search was conducted across databases including PubMed, Scopus, and Google Scholar, identifying media such as Hank’s Balanced Salt Solution (HBSS), milk, saline, propolis, coconut water, and more. Ideal storage media should exhibit antimicrobial properties, maintain physiological osmolality and pH, support PDL cell viability, and be readily available. HBSS is highlighted as the gold standard, with its ability to preserve PDL cells for up to 48 hours. Other effective media like milk, soy milk, and oral rehydration solutions are discussed for their accessibility and performance. Emerging media such as propolis and epigallocatechin-3-gallate show promise but require further research. This review emphasizes the importance of public awareness and accessibility to effective storage media to improve the prognosis of avulsed teeth. Keywords: Storage Media, Dental Avulsion, PDL viability.

Freezing chicken semen: Influence of base medium osmolality, cryoprotectants, cryoprotectant concentration, and cooling rate on post-thaw sperm survival

A classical chicken semen diluent (Lake's 7.1 diluent) was modified to have lowered osmolalities (ranging from 290 to 410 mOsm/kg). The modified medium with physiological osmolality of 325 mOsm/kg allowed cold storage of fresh semen for several days with very little loss of membrane integrity and motility, while high osmolalities inhibited motility. This modified medium was then used as base for freezing medium to test effects of the type and concentration of cryoprotective agent (CPA), and the cooling rate (CR). A number of CPAs (methylformamide, methylacetamide, dimethylformamide (DMF), dimethylacetamide (DMA), diethylformamide, and propylene glycol) were first compared by freezing semen with 0.6 mol/l of the respective CPA at a cooling rate of 250 °C/min. Post-thaw motility and membrane integrity were highest with DMA and DMF. Finally, in more detailed factorial experiments, semen from individual cocks or pooled semen was frozen using CRs of 4, 50, 250, and 440 °C/min and DMA concentrations ([DMA]) of 0.4, 0.6, 1.0, and 1.5 mol/l. Straws from each semen sample x treatment combination were divided for semen assessment at three different research groups for sperm motility, membrane integrity, kinked tails, and DNA fragmentation, using microscopy, computer assisted motility analysis, and flow cytometry. There were clear effects of both CR and [DMA] and their interaction. CRs 50 and 250 °C/min gave best post-thaw sperm performance. Higher DMA concentrations gave better post-thaw membrane integrity, but concentrations above 1.0 mol/l can decrease sperm velocity or even inhibit sperm motility. Therefore [DMA] may best be 0.6–1.0 mol/l at a CR of 50–250 °C/min.

Octanorm [cutaquig®], a new immunoglobulin (human) subcutaneous 16.5% solution for injection (165 mg/mL) – Biochemical characterization, pathogen safety, and stability

Octanorm (marketed as cutaquig® in Canada and US [2018] and registered in several European countries [2019]) is a new immunoglobulin subcutaneous 16.5% liquid for the treatment of patients with primary immune deficiency (PID) and secondary immune deficiency (SID) depending on country's specific indications.Octanorm contains ≥96% human IgG and is characterized by especially low concentrations of polymers and aggregates, IgA and IgM, a physiological osmolality along with a low isoagglutinin titer. The Octanorm manufacturing process is based on the well-established IVIG octagam® 5% and 10% process, but yields a higher immunoglobulin concentration of 16.5% in the final product. Octanorm shows a distribution of immunoglobulin G subclasses closely proportional to native human plasma and comprises a broad spectrum of antibodies against infectious agents. Potential procoagulant activity is not detectable. IgG functionality and physico-chemical integrity have been demonstrated by state-of-the-art-methods.The virus safety of Octanorm is ensured via a combination of three validated independent methods as part of the manufacturing process. Substantial prion depletion during the manufacturing process has also been demonstrated.Compared with other commercially available subcutaneous immunoglobulin (SCIG) 20% products, Octanorm 16.5% shows a lower viscosity, which is a valuable feature that allows for a more comfortable infusion experience.

Comparative methodological studies of L-asparaginase encapsulation into erythrocytes

Background. L-asparaginase is an enzyme, widely used in the therapy of acute lymphoblastic leukemia in children and adults, but its use is limited due to a wide range of side effects and anaphylactic reactions. L-asparaginase loaded into erythrocytes can solve these problems. This enzyme is protected from the immune system and plasma proteases due to erythrocyte membrane, but continues to work inside the cell because its membrane is permeable to L-asparagine. Thus, the half-life of the drug increases and anaphylactic reactions reduce. The encapsulation of L-asparaginase into erythrocytes can be performed by various osmotic methods. Each of them is characterized by the amount of encapsulated enzyme, the cell yield, as well as by the quality indices of the survived erythrocytes. An important parameter of each method is the possibility to provide sterility of this dosage form for the clinical use.The aim of the study was the comparing of three osmotic methods of L-asparaginase encapsulation into erythrocytes (hypo-osmotic lysis, dialysis and flow dialysis) to select the most promising method for clinical use.Materials and methods. A suspension of erythrocytes of healthy donors (hematocrit 60–70%) was mixed with L-asparaginase from E. сoli. The procedures of hypotonic reversible lysis, dialysis in dialysis bags, or flow dialysis using pediatric dialyzers were performed. The physiological osmolality was restored in suspensions after the procedure by the addition of a hypertonic solution, and they were incubated for 30 min at 37 °C. Then the cells were washed in isotonic phosphate-buffered saline with pH 7.4. Activity of L-asparaginase, volume, hematocrit, hematological indices and osmotic cell fragility of erythrocytes were measured in the suspensions of erythrocytes before and after the enzyme encapsulation procedure.Results. An optimal osmolality of the hypotonic buffer for each method was selected and was equal to 90–110 mOsm/kg. The yields of encapsulation were 4.2 ± 2.0, 6.0 ± 2.3 and 16.2 ± 2.2 % for hypotonic lysis, dialysis and flow dialysis, respectively. The hematological indices of the obtained erythrocyte-carriers differed from the corresponding parameters of the initial erythrocytes, but did not differ significantly for different methods.Conclusion. Comparative investigation of mentioned above parameters allowed choosing the method of flow dialysis as the most promising for clinical use.

Inhibitory effect of K+ ions and influence of other ions and osmolality on the spermatozoa motility of European burbot (Lota lota L.).

BackgroundIn fish with external fertilization, two main start-up mechanisms of the path that blocks or activates the spermatozoan motility apparatus are known. The main factor managing the path is osmolality or potassium ion. In burbot from the European and North American population, contradictory findings regarding the factors influencing the onset of spermatozoa motility were reported. The objective of the current study was to determine the effect of potassium and osmolality on the spermatozoa activation of European burbot, Lota lota (Actinopterygii, Gadiformes, Lotidae). Moreover, the influence of pH, as well as sodium ion concentrations on spermatozoa motility was investigated. Seven parameters characterising motility were traced by means of computer-assisted sperm analysis (CASA).Principal findingsThe spermatozoa of European burbot are K+ ion-sensitive. A 6-mM KCl solution significantly decreased motility, and above 12-mM (50 mOsm kg-1) totally ceased spermatozoa movement. Sucrose and Na+ solutions inhibited spermatozoa movement only at concentrations > 450–480 mOsm kg-1. Greater differences in the percentage of motile sperm between individuals were noted in solutions containing high concentrations of chemicals triggering sperm motility. The optimum osmolality for spermatozoa motility is in the range of 100–200 mOsm kg-1. The burbot spermatozoa were motile over a wide range of pH values with the best activation at pH 9.ConclusionIt was demonstrated that the spermatozoa of European burbot are inhibited by K+ ions similarly as in North American burbot. Other electrolyte and non-electrolyte solutions inhibit spermatozoa movement only if their osmolality is greater than that of the physiological osmolality of seminal plasma. The data provided on basic knowledge of burbot spermatozoa allow to ensure appropriate conditions during artificial reproduction and scientific research.

Cytosolic Transport of Nanoparticles through Pressurized Plasma Membranes for Molecular Delivery and Amplification of Intracellular Fluorescence.

Transporting nanoparticles into live cells is important for drug delivery and other related applications. We found that cells exposed to hypoosmotic pressures can internalize substantial quantities of gold nanoparticles. Importantly, these nanoparticles can circumvent normal intracellular traffic and be transported directly into the cytosol, without the need for surface functionalization. In contrast, nanoparticles endocytosed at physiological osmolality are segregated inside endocytic organelles and are not able to reach the cytosol. Cytosolic internalization was observed for nanoparticles of various sizes and materials, with minimal short- or long-term damage induced by the internalized particles. Thus, our strategy can be used as a delivery platform for a range of applications from therapeutics to medical imaging. As examples, we demonstrated rapid delivery of membrane-impermeable molecules to the cytosol by using nanoparticles as carriers and the use of nanoparticles assembled within the cytosol as plasmonic nanoantenna to enhance intracellular fluorescence. We propose a model for the mechanisms behind nanoparticle internalization through pressurized plasma membranes via the release of lateral pressures. Such characterizations may constitute a foundation for developing new technologies, including nanoparticle-based drug delivery.

Medios de almacenamiento y transporte para dientes avulsionados

Se realizó una revisión de la literatura con respecto a los medios de almacenamiento para dientes avulsionados. Se utilizó el buscador Medline, incluyendo aquellas publicaciones entre 1980 - 2007 en las que apareciesen como palabra clave: “viability”, “storage medium”, “storage media”, “tooth avulsion” y “avulsion”. Los mejores medios son aquellos que tienen las siguientes características: pH y osmolalidad fisiológica, contengan nutrientes, sean líquidos estériles y estén disponibles en el lugar del accidente. Los resultados de estos estudios muestran que la leche fresca descremada pasteurizada fue mejor que la saliva, el agua, las soluciones para lentes de contacto y el Gatorade®. El HBSS y el Viaspan fueron mejores que la leche, el propóleo y el agua de coco. El Viaspan fue igual a, o mejor que, el HBSS para preservar las células del ligamento periodontal. A pesar de su efectividad en mantener la viabilidad celular, el Viaspan y el HBSS son costosos y no están disponibles rápidamente en el lugar del accidente a diferencia de la leche.

The importance of implementing proper selection of excipients in lupus clinical trials

Peptide therapeutics hold attractive potential. However, the proper stabilization of such therapeutics remains a major challenge. Some peptides are marginally stable and are prone to degradation. Therefore, in addition to chemical modifications that can be introduced in their sequence, a wide variety of excipients are added in the formulation to stabilize them, as is also done routinely for protein therapeutics. These substances are supposed to suppress peptide/protein aggregation and surface adsorption, facilitate their dispersion and additionally to provide physiological osmolality. Particular attention has to be paid to the choice of such excipients. Here we highlight the observation that in certain clinical situations, an excipient that is not totally inert can play a highly damaging role and mask (or even reverse) the beneficial effect of a molecule in clinical evaluation. This is the case, for instance, of trehalose, a normally safe excipient, which notably has proven to act as an activator of autophagy. This excipient, although used efficiently in several therapeutics, adversely impacted a phase IIb clinical trial for human and murine lupus, a systemic autoimmune disease in which it has been recently discovered that at the base line, autophagy is already abnormally enhanced in lymphocytes. Thus, in this particular pathology, while the peptide that was tested was active in lupus patients when formulated in mannitol, it was not efficient when formulated in trehalose. This observation is important, since autophagy is enhanced in a variety of pathological situations, such as obesity, diabetes, certain neurological diseases, and cancer.

Measurement of the nonlinear elasticity of red blood cell membranes.

The membranes of human red blood cells (RBCs) are a composite of a fluid lipid bilayer and a triangular network of semiflexible filaments (spectrin). We perform cellular microrheology using the dynamic membrane fluctuations of the RBCs to extract the elastic moduli of this composite membrane. By applying known osmotic stresses, we measure the changes in the elastic constants under imposed strain and thereby determine the nonlinear elastic properties of the membrane. We find that the elastic nonlinearities of the shear modulus in tensed RBC membranes can be well understood in terms of a simple wormlike chain model. Our results show that the elasticity of the spectrin network can mostly account for the area compression modulus at physiological osmolality, suggesting that the lipid bilayer has significant excess area. As the cell swells, the elastic contribution from the now tensed lipid membrane becomes dominant.

Intrakranieller Druck und hypotone Infusionslösungen

The physiological osmolality of plasma is 288+/-5 mosmol/kgH2O when measured by freezing-point depression. The theoretical osmolarity (290 mosmol/l) calculated from composition, osmotic coefficient (0.93) and water content (0.94) is practically identical. Saline (0.9% NaCl) has an osmolarity of 308 mosmol/l and an osmolality of 286 mosmol/kgH2O (water content ca. 1.0). The osmolality in vivo is more important than that measured in vitro. A 5% dextrose solution in water (D5W) is isotonic in vitro, but the in vivo effect is that of pure water because the glucose is rapidly metabolized. Every infusion fluid should be isotonic (290+/-10 mosmol/kgH2O). Hypotonic solutions must move water from the extracellular space to the intracellular space. Typical examples are Ringer's lactate and acetate solutions (256 instead of 290 mosmol/kgH2O). The brain (central nervous system, CNS) is the critical organ: The rigidly shaped skull contains three incompressible compartments, only blood and cerebrospinal fluid (CSF) can be partially, but limitedly shifted outside the skull. The consequence of a volume load is an increasing intracranial pressure (ICP). A decrease in plasma osmolality by only 3% produces an increase in ICP of about 15 mmHg. Therefore, infusion of larger volumes of hypotonic solutions should be avoided at all costs.

PhgABC , a Three-Gene Operon Required for Growth of Streptococcus pneumoniae in Hyperosmotic Medium and In Vivo

To cause disease, bacterial pathogens need to be able to adapt to the physiological conditions found within the host, including an osmolality of approximately 290 mosmol kg(-1). While investigating Streptococcus pneumoniae genes contained within pneumococcal pathogenicity island 1, we identified a three-gene operon of unknown function termed phgABC. PhgC has a domain with similarity to diacylglycerol kinases of eukaryotes and is the first described member of a family of related proteins found in many gram-positive bacteria. phgA and phgC mutant strains were constructed by insertional duplication mutagenesis and found to have impaired growth under conditions of high osmotic and oxidative stress. The compatible solutes proline and glycine betaine improved growth of the wild-type and the phgA mutant strains in hyperosmolar medium, and when analyzed by electron microscopy, the cellular morphology of the phgA mutant strain was unaffected by osmotic stress. The phgA and phgC mutant strains were reduced in virulence in models of both systemic and pulmonary infection. As the virulence of the phgA mutant strain was not restored in gp91phox(-/-) mice and the phgA and phgC mutant strains had reduced growth in both blood and serum, the reduced virulence of these strains is unlikely to be due to increased sensitivity to the respiratory burst of phagocytes but is, instead, due to impaired growth at physiological osmolality.

Biphasic culture strategy based on hyperosmotic pressure for improved humanized antibody production in Chinese hamster ovary cell culture.

Hyperosmotic pressure increased specific antibody productivity (q(Ab)) of recombinant Chinese hamster ovary (rCHO) cells (SH2-0.32) and it depressed cell growth. Thus, the use of hyperosmolar medium did not increase the maximum antibody concentration substantially. To overcome this drawback, the feasibility of biphasic culture strategy was investigated. In the biphasic culture, cells were first cultivated in the standard medium with physiological osmolality (294 mOsm/kg) for cell growth. When cells reached the late exponential growth phase, the spent standard medium was replaced with the fresh hyperosmolar medium (522 mOsm/kg) for antibody production. The q(Ab) in growth phase with the standard medium was 2.1 microg per 10(6) cells/d, whereas the q(Ab) in antibody production phase with the hyperosmolar medium was 11.1 microg per 10(6) cells/d. Northern blot analysis showed a positive relationship between the relative contents of intracellular immunoglobulin messenger ribonucleic acid and q(Ab). Because of the enhanced q(Ab) and the increased cell concentration in biphasic culture, the maximum antibody concentration obtained in biphasic culture with 522 mOsm/kg medium exchange was 161% higher than that obtained in batch culture with the standard medium. Taken together, the simple biphasic culture strategy based on hyperosmotic culture is effective in improving antibody production of rCHO cells.

Effect of hypoosmotic pressure on cell growth and antibody production in recombinant Chinese hamster ovary cell culture.

To determine the response of recombinant Chinese hamster ovary (rCHO) cells subjected to hypoosmotic pressure, rCHO cells (CS13*-1.0) producing a chimeric antibody were cultivated in the hypoosmolar medium resulting from NaCl subtraction. At hypoosmotic pressure, CS13*-1.0 cells displayed decreased specific growth rate (mu) and increased specific antibody productivity (q (Ab)).When the medium osmolality was decreased from 300 mOsm kg(-1)(physiological osmolality) to 150 mOsm kg(-1), mu was decreased by 68% and q (Ab) was increased by 128%. To understand the mechanism of enhanced q (Ab) resulting from hypoosmotic pressure, cellular responses of cells in the exponential phase of growth were observed at the transcription level. Total cytoplasmic RNA content per cell at 150 mOsm kg(-1) was increased by 140%, compared with that at 300 mOsm kg(-1). On a per mug RNA basis, immunoglobulin (Ig) mRNA levels at 150 mOsm kg(-1) were comparable to those at 300 mOsm kg(-1), indicating that hypoosmotic pressure did not lead to the preferential transcription of Ig mRNAs. Taken together, the data obtained here suggest that the increase in total RNA pool is primarily responsible for the enhanced q (Ab) of CS13*-1.0 cells subjected to hypoosmotic pressure.

Osmoprotective Effect of Glycine Betaine on Thrombopoietin Production in Hyperosmotic Chinese Hamster Ovary Cell Culture: Clonal Variations

When 23 recombinant Chinese hamster ovary (rCHO) cell clones were cultivated in hyperosmolar medium resulting from NaCl addition (533 mOsm/kg), their specific thrombopoietin (TPO) productivity (q(TPO)) was increased. However, due to depressed cell growth at elevated osmolality, no enhancement in the maximum TPO titer was made in batch cultures of all 23 clones. To test the feasibility of using glycine betaine, known as a strong osmoprotective compound, for improved TPO production in hyperosmotic rCHO cell cultures, hyperosmotic batch cultures of 23 clones were performed in the presence of 15 mM glycine betaine. Glycine betaine was found to have a strong osmoprotective effect on all 23 clones. Inclusion of 15 mM glycine betaine in hyperosmolar medium enabled 22 clones to grow at 542 mOsm/kg, where most clones could not grow in the absence of glycine betaine, but at a cost of reduced q(TPO). However, the relative decrease in q(TPO) varied significantly among clones. Thus, efficacy of the simultaneous use of hyperosmotic pressure and glycine betaine as a means to improve foreign protein production was variable among clones. Six out of 23 clones displayed more than a 40% increase in the maximum TPO titer in the hyperosmolar medium containing glycine betaine, compared with that in the standard medium with a physiological osmolality. Taken together, the results obtained here emphasize the importance of selection of clones for the successful use of hyperosmotic pressure and glycine betaine as an economical means to improve TPO production.

Mobility of erythrocyte from sedimentation rate at different osmotic pressures

Mobility of swine red blood cells has been obtained by measuring the erythrocyte sedimentation rate in saline solutions, together with hyper- and hypo-tonic conditions. Results in infinite dilution are compared with theoretical mobilities for oblate ellipsoid versus the axial ratio determined from the non-sphericity index by using Coulter Counter at different osmotic pressures. Although experimental data locate approximately around the theoretical mobility for oblate ellipsoids with random orientation, they seem to scatter somewhat lower than the above theory. It may reflect the slow sedimentation due to flickering of erythrocytes with deformability. Erythrocyte mobility has the maximum value near physiological osmolality.

Osmoprotective effect of glycine betaine on foreign protein production in hyperosmotic recombinant Chinese hamster ovary cell cultures differs among cell lines

When three recombinant Chinese hamster ovary (rCHO) cell lines, CHO/dhfr-B22-4, CS13-1.00*, and CS13-0.02*, were cultivated in hyperosmolar media resulting from NaCl addition, their specific foreign protein productivity increased with medium osmolality. However, due to a simultaneous suppression of cell growth at elevated osmolality, no enhancement in the maximum foreign protein titer was made in batch cultures. To test the feasibility of using glycine betaine, known as a strong osmoprotective compound, for improved foreign protein production in hyperosmotic rCHO cell cultures, hyperosmotic batch cultures were carried out in the presence of 15 mM glycine betaine. Glycine betaine was found to have a strong osmoprotective effect on all three rCHO cell lines. Inclusion of 15 mM glycine betaine in hyperosmolar medium enabled rCHO cell lines to grow at 557 to 573 mOsm/kg, whereas they could not grow in the absence of glycine betaine. However, effect of glycine betaine inclusion in hyperosmolar medium on foreign protein production differed among rCHO cell lines. CHO/dhfr-B22-4 cells retained enhanced specific human thrombopoietin (hTPO) productivity in the presence of glycine betaine, and thereby the maximum hTPO titer obtained at 573 mOsm/kg was increased by 72% over that obtained in the control culture with physiological osmolality (292 mOsm/kg). On the other hand, enhanced specific antibody productivity of CS13-1.00* and CS13-0.02* at elevated osmolality was decreased significantly in the presence of glycine betaine. As a result, the maximum antibody titer at 557 mOsm/kg was similar to that obtained in the control culture with physiological osmolality. The mRNA contents per cell determined by northern blot hybridization correlated with q in all three rCHO cell lines, indicating that transcriptional regulation is responsible in part for q enhancement at hyperosmolality in the absence as well as the presence of glycine betaine. Taken together, efficacy of the simultaneous use of hyperosmotic pressure and glycine betaine as a means to improve foreign protein production was variable among different rCHO cell lines.

Inner medullary external osmotic driving force in a 3-D model of the renal concentrating mechanism

The mechanism by which the renal medulla establishes and maintains a gradient of osmolarity along the corticomedullary axis, especially in the inner medulla, where there is no active transmural flux out of the ascending limbs of Henle, remains a source of controversy. We show here that, if realistic values of urea permeability in the inner medullary descending limbs and water permeability in the upper inner medullary section of the collecting ducts are taken into account, even a model including the three-dimensional vascular bundle structures [A. S. Wexler, R. E. Kalaba, and D. J. Marsh. Am. J. Physiol. 260 (Renal Fluid Electrolyte Physiol. 29): F368-F383, 1991] fails to explain the experimentally observed inner medullary osmolality gradient. We show here that this failure can be overcome by application of an external osmotic driving force, an idea recently revived by J. F. Jen and J. L. Stephenson (Bull. Math. Biol. 56: 491-514, 1994) in the context of a single-solute, single-loop central core model. We show that inclusion of such an external driving force with a value equivalent to at least 100 mosM of inner medullary interstitial osmolytes in the three-dimensional model of Wexler et al. accounts for a physiological osmolality gradient, even in the face of realistic permeability values. Furthermore, inclusion of the external driving force makes the model less dependent on the positions of descending and ascending limbs of Henle with respect to the collecting ducts. In an effort to assess whether there is any experimental basis for osmolytes, we show that a significant amount of extra inner medullary interstitial osmolytes is plausible, based on extrapolation from existing experimental data.

Hyperosmotic hbridoma cell cultures: Increased monoclonal antibody production with addition of glycine betaine

When mouse hybridoma cells were grown in culture media which were made hyperosmotic through the addition of NaCl or sucrose, the specific rate of antibody production increased with medium osmolality, reaching approx. 1.9 times the level obtained at physiological osmolality. However, due to a simultaneous reduction of the maximal cell density in the hyperosmotic media, the effect of the increased production rate did not give significant increases in the maximum antibody titer obtained in the cultures. When the osmoprotective compound, glycine betaine, was included in the NaCl- or sucrose-stressed cultures, the specific antibody production rate wasincreased up to 2.6-fold and maximum antibody titer up to twofold over that obtained in the control culture (physiological osmolality). A similar pattern of response was observed when other osmoprotective compounds (sarcosine, proline, glycine) were added to NaCl-stressed hybridoma cell cultures. For the present experiments, the results suggest that medium osmolality, rather than growth rate, will determine the specific antibody production rate by hybridoma cell line 6H11 growing in hyperosmotic culture media. (c) 1994 John Wiley & Sons, Inc.

DNA, protein, and plasma-membrane incorporation by arrested mammalian cells.

Incorporation of DNA, protein, and plasma membrane during blockage by aphidicolin or by doxorubicin was studied by flow cytometry and electrorotation of three cell lines (mouse-myeloma Sp2/0-Ag14, hybridoma H73C11, and fibroblast-like L929 cells). Drug-mediated arrest at the G1-S boundary (aphidicolin) or in G2/M (doxorubicin) did not arrest synthesis of either protein or total membrane area, the increases in which outstripped growth in cell volume and apparent cell area, respectively. Measurements of membrane capacity in normal and hypo-osmotic media showed that the drugs had not changed the fundamental bilayer, but that an increase in the number or size of microvilli must have occurred. Aphidicolin-arrested cells withstood hypo-osmotic stress better than untreated cells could, indicating that the membrane excess can be utilized as a reserve during rapid cell expansion. Hypo-osmotically treated cell populations exhibited only about half the coefficient of variance (CV) in membrane properties of cells at physiological osmolality. Populations of arrested cells exhibited the same high CV as asynchronous cells, indicating that chemical arrest does not give uniformly villated cell populations. However, the lowest CV values were given by some synchronized (aphidicolin-blocked, then released) populations. Removal of aphidicolin allowed most cells to progress through S and G2, and then divide. During these processes, the membrane excess was reduced. After removal of doxorubicin, the cells did not divide: some continued protein synthesis, grew abnormally large, and further increased their membrane excess. Membrane breakdown by electric pulsing (3 x 5kV/cm, 40 microseconds decay time) of aphidicolin-synchronized L cells in G2/M led to a 22% loss of plasma membrane (both the area-specific and the whole-cell capacitance were reduced), presumably via endocytosis-like vesiculation.

Physiological responses, feed intake, urine volume and serum osmolality of aardi goats deprived of water during spring and summer

Physiological responses, feed intake, urine volume and serum osmolality of aardi goats deprived of water during spring and summer