During the electroporation cell membrane conductivity increases dramatically, so the analytical model for calculating the transmembrane voltage (TMV) induced on an unpermeabilized cell membrane in suspensions can not be used in this case. An analytical model for the TMV induced on a permeabilized cell membrane in suspensions exposed to a high voltage DC pulse field was built. First, a permeabilized cell was replaced by a sphere cell having the equivalent conductivity. Then the average field inside the permeabilized cell suspensions was calculated according to the effective medium theory. Finally, based on the analytical solution for the TMV on a single unpermeabilized cell, an analytical model for the TMV on a permeabilized cell in suspensions was derived. The model shows that the TMV depends on parameters such as the external electric field, critical angle of electroporation, cell radium, conductivity of the cytoplasm, membrane and external medium, cell arrangement and cell volume fraction.
Cell Membrane Permeability ; Electric Conductivity ; Electromagnetic Fields ; Electrophysiology ; Electroporation ; Humans ; Membrane Potentials ; Models, Biological ; Pulse

The main characteristics of molecular structures of the yeast Saccharomyces cerevisiae cell wall are now elucidated. The cell wall of Saccharomyces cerevisiae is composed of inner layer and outer layer and is the structure that plays an important role of providing physical and chemical protection and deciding the morphology of the cell. The inner layer of the cell wall is responsible for the mechanical strength of the wall and also providing the attachment sites for the proteins that form the outer layer of the cell wall. The outer protein layer limits the permeability of the cell wall, therefore, shields the plasma membrane from perturbation stimuli by foreign material such as enzymes and other chemicals. The molecular composition and organization of the cell wall may vary according to the environmental circumstances. The formation and genetic control of the specific cell wall protein-polysaccharide complexes is influenced by external conditions and stimuli. Cell wall construction is tightly controlled and strictly coordinated with progression of the cell cycle. This is reflected in the usage of specific cell wall proteins during consecutive phases of the cell cycle and in the recent discovery of a cell wall integrity checkpoint.
Cell Cycle ; Cell Membrane ; Cell Wall* ; Molecular Structure* ; Permeability ; Saccharomyces cerevisiae* ; Saccharomyces* ; Yeasts*

OBJECTIVETo explore the appropriate acoustic parameters for augmenting the permeability of tumor cells using microbubble-enhanced ultrasound.

METHODSNinety intramuscular VX2 tumors grown in New Zealand white rabbits were randomly divided into 4 parts by 4 factors, namely sound intensity, pulse width, insonation time and microbubble dose, each at different levels. Therapeutic ultrasound was delivered directly to the tumor surface during intravenous infusion of microbubbles. The tumor was excised after the treatment and sliced to investigate the change in tumor cell permeability using lanthanum nitrate electron microscopy. The appropriate acoustic parameters of the 4 factors were investigated.

RESULTSSonoporation induced by microbubble-enhanced ultrasound augmented the permeability of the tumor cells, and the appropriate sound intensity, pulse width, insonation time and microbubble dose were 0.43 W/cm(2), 2.42 ms, 10 min, and 0.50 ml/kg, respectively.

CONCLUSIONSonoporation induced by microbubble-enhanced ultrasound can induce pores in tumor cell membrane, which may potential increase the efficacy of tumor chemotherapy.

Acoustics ; Animals ; Cell Line, Tumor ; Cell Membrane Permeability ; Microbubbles ; Neoplasms ; therapy ; Rabbits ; Ultrasonic Therapy ; Ultrasonics

Microbubble contrast agent for ultrasound imaging has come of age, adding entirely new capabilities to real time ultrasound imaging. These new ultrasound imaging techniques exploit the nonlinear echoes that result from the unique interaction between ultrasound and microbubbles, which are readily distinguishable from the echoes of tissues. Contrast enhanced ultrasound can be used to quantify both flow rate and relative vascular volume of the microvasculature in solid lesions or organs, which makes it possible for it to be one of the modalities in molecular imaging. Angiogenesis is one of the important processes contributing to new blood vessel growth that occurs in a variety of physiologic and pathophysiologic states. It is essential for spread and growth of malignant tumors. The advantages of contrast enhanced ultrasound are that it is a noninvasive method for observing tumor angiogenesis. Sonoporation utilizes the interaction of ultrasound with ultrasound contrast agents to temporarily permeabilize the cell membrane allowing for the uptake of DNA, drugs, and other therapeutic compounds from the extracellular environment. Thus, sonoporation is a promising drug delivery and gene therapy technique, limited only by lack of understanding regarding the biophysical mechanism that results in the cell membrane permeability change. In conclusion, ultrasound contrast agent could have a role not only in the molecular imaging field with the advantage of noninvasive quantification of angiogenesis, but also in the field of drug treatment of cells using sonoporation.
Blood Vessels ; Cell Membrane ; Cell Membrane Permeability ; Contrast Media ; DNA ; Genetic Therapy ; Glycosaminoglycans ; Imidazoles ; Microbubbles ; Microvessels ; Molecular Imaging ; Nitro Compounds

Vasopressin, a neurohypophyseal peptide hormone, is the endogenous agonist at V1a, V1b, and V2 receptors. The most important physiological function of vasopressin is the maintenance of water homeostasis through interaction with V2 receptors in the kidney. Vasopressin binds to V2 receptor and increases the number of aquaporin-2 at the apical plasma membrane of collecting duct principal cells. That induces high water permeability across the membrane. Several non-peptide vasopressin receptor antagonists have been developed and are being studied primarily for treating conditions characterized by hyponatremia and fluid overload. Further studies are needed to determine how they are best used in these situations.
Aquaporin 2 ; Cell Membrane ; Homeostasis ; Hyponatremia ; Kidney ; Membranes ; Permeability ; Receptors, Vasopressin ; Vasopressins

AIMTo compare sonoporation effect of two phospholipids-based vectors-liposomes and microbubbles on cultured cell membrane.

METHODSA breast cancer cell line SK-BR-3 was exposed to ultrasound alone, 2% or 5% liposome + ultrasound and 2% or 5% microbubble + ultrasound, separately. Immediately after the experiment and 24 h after ultrasound exposure, atomic-force microscopy (AFM) scanning was used to observe the membrane change of SK-BR-3 cells.

RESULTSAfter ultrasound exposure, normal SK-BR-3 cells more or less lost their natural shape, showing elliptic outline with obtuse curved boundary. In groups added with phospholipids-based microbubbles, more obtuse curved boundary of cells was observed. The membrane pores of SK-BR-3 cells had apparent changes after ultrasound exposure. With AFM technique, membrane pores under ultrasound alone or ultrasound with liposomes conditions were enlarged, the diameter of some pores exceeding 1 microm. But all the membrane pores in these conditions returned to normal appearance after 24 hours. In ultrasound with 2% microbubble condition, most membrane pores were about 1 - 3 microm in size and returned to normal appearance after 24 h. In ultrasound with 5% microbubble condition, however, pores of most cell membrane porosity was about 2 - 4 pm and did not totally return to normal appearance after 24 h.

CONCLUSIONAt 2% concentration, phospholipids-based microbubble could enhance ultrasonic sonoporation effect and produce reparable membrane pores on SK-BR-3 cells, which appeared to be a promising vehicle for drug and gene delivery.

Cell Membrane Permeability ; Drug Carriers ; Liposomes ; Microbubbles ; Phospholipids ; chemistry ; Porosity ; Sonication ; instrumentation ; Technology, Pharmaceutical

The successful cryopreservation of reproductive cells has important practical significance in many fields. In order to improve the recovery rate and viability of cryopreserved cells, it is necessary to study the permeability characteristics of cell membrane to both water and cryoprotectant. In this paper we review the studies on membrane permeability of animal reproductive cell for the recent years. We firstly list the typical permeability data of spermatozoa and oocyte membrane for water and cryoprotectant. We then analyze the effects of these characteristics on the design of cryopreservation protocol. We also introduce the latest experimental methods to measure the cell membrane permeability.
Animals ; Cell Membrane Permeability ; physiology ; Cryopreservation ; methods ; Female ; Humans ; Male ; Oocytes ; cytology ; Spermatozoa ; cytology

OBJECTIVETo investigate the intestinal absorption mechanism of swertiamain metabolite {(Z)-5-ethylidene-8-hydroxy-3,4,5,6,7,8-hexahydro-1H-pyrano [3,4-c]pyridine-1-one, EHPO}.

METHODThe time depended hi-directional transport of EHPO in Caco-2 monolayer model was investigated with the factors of concentration, pH and verapamil. EHPO concentration was measured by HPLC assay and the apparent permeability coefficients (Papp) were calculated.

RESULTIn the this cell model, EHPO could be absorbed through Caco-2 soon. The P(app AP-BL) was equal to the P(app BL-AP), and Papp keep almost constant with the selected concentration investigated. But the Papp could be influenced by pH and verapamil (100 mg x L(-1)).

CONCLUSIONThe absorption of EHPO in Caco-2 cell model is a passive one. And absorption of EHPO in the intestines is quite good.

Biological Transport ; Caco-2 Cells ; Cell Membrane Permeability ; Drugs, Chinese Herbal ; chemistry ; pharmacokinetics ; Humans ; Models, Biological

This is our first time report of S-180 cell handled with various voltages, capacity and pulse number. Many pores on the S-180 cell membrane can be observed under scanning electron microscope. By the stains of trypan blue, we have known the influence of electric parameters on the ratio of poration. The results show that the ratio of electroporation has positive correlation with the voltages and the pulse number while negative correlation with the capacity.
Animals ; Cell Membrane Permeability ; Electromagnetic Fields ; Electroporation ; methods ; Mice ; Sarcoma 180 ; ultrastructure ; Tumor Cells, Cultured

Aims: Skin burns remain a noteworthy general medical issue throughout the world, as it boosts a condition of immuno-suppression. The present research aimed to evaluate the efficacy of Syzygium aromaticum extracts, silver sulphadiazine ointment, and different commercially available topical antibiotics against pathogenic bacteria, isolated from the skin of burn patients. Methodology and results: A total of 124 clinical pus samples were collected from the skin of burn patients, admitted to two different tertiary care burn units at Peshawar, Pakistan. From these pus samples, 6 bacterial isolates from burned skin (Staphylococcus epidermidis, Streptococcus, Klebsiella, Enterobacter, Bacillus and Pseudomonas spp.) were isolated, while 4 different bacterial isolates (Staphylococcus epidermidis, Staphylococcus aureus, Bacillus and Streptococcus spp.) were isolated from unburned skin via conventional culturing techniques. Further, antibacterial assays were performed to compare the efficacy of S. aromaticum extracts (methanolic and aqueous extract), silver sulphadiazine ointment, and different commercially available antibiotics against tested bacteria. It was observed that both methanolic and aqueous extracts of S. aromaticum were effective at all concentrations against all the tested bacteria. In addition, all the tested antibiotics expressed substantial activity against most of the bacterial isolates. While silver sulphadiazine ointment was observed to be less potent against isolated bacteria as compared to S. aromaticum extracts. Conclusion, significance and impact of study It was concluded that both aqueous and methanolic extracts of S. aromaticum were effective antimicrobial agents and could be used as an alternative to control bacterial infections of burn patients. This study would help to distinguish the risk factors of bacterial pathogenicity in burn patients and would also provide a guideline to utilize medicinal plants and their extracts to minimize the chances of antibiotic resistance phenomenon in burn patients.
Anti-Bacterial Agents ; Cell Membrane ; Oxidative Stress ; Permeability ; Plant Extracts ; Syzygium