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The clinical transfusion of red blood cells (RBCs) has provided the greatest number of cryobiology applications in the case of rare blood groups and antibody problems, as well as civil and military disasters. The main technical difficulty with the current clinical technique is the removal of high concentration glycerol (20% or 40%) after thawing. Reducing the probability of intracellular ice formation (IIF) as well as preventing the solution effect are crucial to ensure RBCs avoid cryoinjury. Here, the non-permeating cryoprotectant trehalose was used to dehydrate RBCs before freezing. Furthermore, with the substitution of the low concentration glycerol (5% or 7.5%) for the intracellular remaining water, the bulk of RBCs were successfully cryopreserved to obtain a nearly 95% high survival rate with rapid cooling via EP tubes. Additionally, the washed RBCs after cryopreservation maintained their morphology, deformability, ATP, and 2-3 DPG levels, and all of them met the clinical standards for transfusion safety. Moreover, the whole addition and washing process was simple and easy to operate and could be completed within 30 min, which is crucial for emergency uses. This method will provide more potential for current clinical RBCs cryopreservation practices.

BackgroundHemoglobin A1c (HbA1c) variability may be a predictor of diabetic complications, but the predictive values of HbA1c trajectories remain unclear. We aimed to classify long-term HbA1c trajectories and to explore their effects on future clinical outcomes in a 10-year cohort with type 2 diabetes mellitus (T2DM).MethodsA total of 2,161 participants with T2DM from the Beijing Community Diabetes Study were included. The 10-year follow-up was divided into two stages for the present data analysis. Stage I (from 2008 to 2014) was used to identify the HbA1c trajectories and to calculate the adjusted SD of HbA1c (HbA1c-adjSD), or the coefficient of variation of HbA1c (HbA1c-CV). Stage II (from 2014 to 2018) was used to collect the records of the new occurrence of diabetes-related clinical outcomes. Latent growth mixture models were used to identify HbA1c trajectories. Cox proportional hazards models were used to explore the relationship between HbA1c trajectories, HbA1c-adjSD, or HbA1c-CV and the future outcomes.ResultsThree HbA1c trajectories were identified, including low stable (88.34%), gradual decreasing (5.83%), and pre-stable and post-increase (5.83%). Either the risk of death or the chronic complications were significantly higher in the latter two groups compared to the low stable group after adjustment for average HbA1c and other traditional risk factors, the adjusted hazard ratios (HRs) for renal events, composite endpoint, and all-cause death for the pre-stable and post-increase group were 2.83 [95%CI: 1.25–6.41, p = 0.013], 1.85 (95%CI: 1.10–3.10, p = 0.020), and 3.01 (95%CI: 1.13–8.07, p = 0.028), respectively, and the adjusted HR for renal events for the gradual decreasing group was 2.37 (95%CI: 1.08–5.21, p = 0.032). In addition, both univariate and multivariate Cox HR models indicated that participants in the fourth and third quartiles of HbA1c-CV or HbA1c-adjSD were at higher risk of renal events compared to participants in the first quartile.ConclusionsHbA1c trajectories, HbA1c-CV, and HbA1c-adjSD could all predict diabetes-related clinical outcomes. HbA1c trajectories could reflect long-term blood glucose fluctuation more intuitively, and non-stable HbA1c trajectories may predict increased risk of renal events, all-cause death, and composite endpoint events, independent of average HbA1c.

The hydraulic permeability of the lipid bilayer membrane of a single cell, a very important parameter in biological and medical fields, has been attracting increasing attention. To date, methods developed to determine this permeability are either operation-complicated or time-consuming. Therefore, we developed a chip for automatically and rapidly determining the permeability of cells that integrates microfluidics and cell impedance analysis. The chip is designed to automatically identify a single cell, capture the cell, and record the volume change in that cell. We confirmed the abilities of single-cell identification and capture with the upper and lower voltage thresholds determined, validated the performance of the differential electrode design for accurate cell volume measurements, deduced the extracellular osmotic pressure change in the presence of a hypertonic solution according to fluorescence intensity, and demonstrated the single-cell volume change recorded by the chip. Then, the accuracy of the permeability determined with the chip was verified using HeLa cells. Finally, the permeability of human-induced pluripotent stem cells (hiPSCs) was determined to be 0.47 ± 0.03 μm/atm/min. Using the chip, the permeability can be determined within 5 min. This study provides insights for the new design of an automatic single-cell identification and capture chip for single cell-related studies. Graphical abstract.

Rapid and accurate clinical assessment of hemostasis is essential for managing patients who undergo invasive procedures, experience hemorrhages, or receive antithrombotic therapies. Hemostasis encompasses an ensemble of interactions between the cellular and non-cellular blood components, but current devices assess only partial aspects of this complex process. In this work, we describe the development of a new approach to simultaneously evaluate coagulation function, platelet count or function, and hematocrit using a carbon nanotube-paper composite (CPC) capacitance sensor. CPC capacitance response to blood clotting at 1.3 MHz provided three sensing parameters with distinctive sensitivities towards multiple clotting elements. Whole blood-based hemostasis assessments were conducted to demonstrate the potential utility of the developed sensor for various hemostatic conditions, including pathological conditions, such as hemophilia and thrombocytopenia. Results showed good agreements when compared to a conventional thromboelastography. Overall, the presented CPC capacitance sensor is a promising new biomedical device for convenient non-contact whole-blood based comprehensive hemostasis evaluation.

In this work, we present a new version of the dilution-filtration system for rapidly deglycerolizing a large volume of cryopreserved blood. In our earlier system, one of the major problems was the damage induced to the red blood cells (RBCs) due to high osmolality change at the dilution point. Therefore, we devised a new system to solve this problem. First, we theoretically simulated the osmolality variation in the new system and the variation of the maximum and minimum volumes of the RBCs at the dilution point to examine the effects of operating parameters/conditions. Next, we experimentally validated the effects of these operating parameters by deglycerolizing porcine blood. The results show that when the initial NaCl concentration in the hypertonic solution is 18%, the volume of the hypertonic solution is 200 mL, and the flow rate of the filtrate is 50 mL/min, the system can effectively remove glycerin from 200 mL of porcine blood in 30 min, with ∼87% RBC survival rate and ∼73% RBC recovery rate. Our results indicated that in the new system the concentration and the volume of the hypertonic solution used to dilute the blood are the important parameters that need to be adjusted to reduce osmotic damage to the RBCs. In addition, a fast filtrate flow rate is highly recommended. This work can significantly contribute to the development of a more efficient and effective system for deglycerolizing large volumes of cryopreserved blood in clinic.

Artemether is one of the most effective drugs for the treatment of chloroquine-resistant and Plasmodium falciparum strains of malaria. However, its therapeutic potency is hindered by its poor bioavailability. To overcome this limitation, we have encapsulated artemether in poly(lactic-co-glycolic) acid (PLGA) core-shell microparticles (MPs) using the coaxial electrospray method. With optimized process parameters including liquid flow rates and applied electric voltages, experiments are systematically carried out to generate a stable cone-jet mode to produce artemether-loaded PLGA-MPs with an average size of 2 μm, an encapsulation efficiency of 78 ± 5.6%, and a loading efficiency of 11.7%. The in vitro release study demonstrates the sustained release of artemether from the core-shell structure in comparison with that of plain artemether and that of MPs produced by single-axial electrospray without any relevant cytotoxicity. The in vivo studies are performed to evaluate the pharmacokinetic characteristics of the artemether-loaded PLGA-MPs. Our study implies that artemether can be effectively encapsulated in a protective shell of PLGA for controlled release kinetics and enhanced oral bioavailability.

We developed an integrated microfluidic platform for instantaneous flow and localized temperature control. The platform consisted of a flow-focusing region for sample delivery and a cross-junction region embedded with a microheater for cell trapping and localized temperature control by using an active feedback control system. We further used it to measure the membrane transport properties of Jurkat cells, including the osmotically inactive cell volume (Vb) and cell membrane permeabilities to water (Lp) and to cryoprotective agent (CPA) solutions (dimethyl sulfoxide (DMSO) in this study) (PS) at various temperatures (room temperature, 30 °C, and 37 °C). Such characteristics of cells are of great importance in many applications, especially in optimal cryopreservation. With the results, the corresponding activation energy for water and CPA transport was calculated. The comparison of the results from the current study with reference data indicates that the developed platform is a reliable tool for temperature-dependent cell behavior study, which provides valuable tools for general cell manipulation applications with precise temperature control.

Cell survival rate (CSR) is a very important parameter in biological and medical fields. Today, the routine method to determine this parameter is time-consuming; it also makes the labeled cells no longer useable for subsequent experiments. Here, we developed an on-chip label-free method for determining the CSR. For the method, a hypertonic stimulus was designed to create volume differences between living and dead cells, and then, the differences were characterized with measurements of impedance as the cells flowed through two electrodes. Based on the method, a microfluidic hypertonic stimulus-based impedance flow cytometry chip (HSIFC) was designed, and the localized function of the HSIFC was verified. Finally, the performance of the HSIFC was confirmed by measuring the different CSRs for the different types of cells. The results show that the HSIFC can accurately determine the CSR, and the accuracy is comparable to that of flow cytometry. This work paves the way for the label-free evaluation of CSR after various cell manipulations and treatments on the chip and promotes the versatility of lab-on-a-chip devices.

It is well known that the warming process is a critical step in cell cryopreservation, affecting the survival rate of the cryopreserved cells. However, there is a lack of understanding and optimization of the warming process for the cryopreserved human peripheral blood mononuclear cells (PBMCs) that are greatly needed for the cellular/immune therapies worldwide. In this study, the effect of the warming process on cryosurvival of the PBMCs was investigated, resulting in a recommendation of an optimal warming method. In the experiments, all PBMC samples were cooled by a fixed slow cooling process and stored in a liquid nitrogen tank. The frozen samples were then warmed in water baths with stirring at various temperatures, 37°C, 42°C, and 65°C, respectively. After thawing, PBMC's viability as well as phenotypic and functional analyses were performed and evaluated. It was shown that a relatively rapid warming process at 65°C in a water bath with stirring generated a significant improvement of cell viability, recovery, and functionality of the cryopreserved PBMCs. In addition, interferon-γ and interleukin-2 secretion were much higher in PBMCs thawed at 65°C than that in 42°C and 37°C, respectively. This study suggests that a rapid warming process at 65°C in a water bath should be used to replace the current conventional warming approach at 37°C.

HighlightsHuman-centric boundary extraction criteria and new boundary model.A novel boundary visualization method though a what material you pick is what boundary you see approach.Point-to-material distance measure.A complete application. Transfer function design is a key issue in direct volume rendering. Many sophisticated transfer functions have been proposed to visualize boundaries in volumetric data sets such as computed tomography and magnetic resonance imaging. However, it is still conventionally challenging to reliably detect boundaries. Meanwhile, the interactive strategy is complicated for new users or even experts. In this paper, we first propose the human-centric boundary extraction criteria and our boundary model. Based on the model we present a boundary visualization method through a what material you pick is what boundary you see approach. Users can pick out the material of interest to directly convey semantics. In addition, the 3-D canny edge detection is utilized to ensure the good localization of boundaries. Furthermore, we establish a point-to-material distance measure to guarantee the accuracy and integrity of boundaries. The proposed boundary visualization is intuitive and flexible for the exploration of volumetric data.

Cancer is a serious threat to human health. Although numerous anti-cancer drugs are available clinically, many have shown toxic side effects due to poor tumor-selectivity, and reduced effectiveness due to cancers rapid development of resistance to treatment. The development of new highly efficient and practical methods to quantify cell viability and its change under drug treatment is thus of significant importance in both understanding of anti-cancer mechanism and anti-cancer drug screening. Here, we present an approach of utilizing a nanomechanical fluctuation based highly sensitive microcantilever sensor, which is capable of characterizing the viability of cells and quantitatively screening (within tens of minutes) their responses to a drug with the obvious advantages of a rapid, label-free, quantitative, noninvasive, real-time and in-situ assay. The microcantilever sensor operated in fluctuation mode was used in evaluating the paclitaxel effectiveness on breast cancer cell line MCF-7. This study demonstrated that the nanomechanical fluctuations of the microcantilever sensor are sensitive enough to detect the dynamic variation in cellular force which is provided by the cytoskeleton, using cell metabolism as its energy source, and the dynamic instability of microtubules plays an important role in the generation of the force. We propose that cell viability consists of two parts: biological viability and mechanical viability. Our experimental results suggest that paclitaxel has little effect on biological viability, but has a significant effect on mechanical viability. This new method provides a new concept and strategy for the evaluation of cell viability and the screening of anti-cancer drugs.

© 2018 Hughes et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background Cryopreservation of leukocytes isolated from the cervicovaginal and colorectal mucosa is useful for the study of cellular immunity (see Hughes SM et al. PLOS ONE 2016). However, some questions about mucosal biology and sexually transmitted infections are better addressed with intact mucosal tissue, for which there is no standard cryopreservation protocol. Methods and findings To find an optimal preservation protocol for mucosal tissues, we tested slow cooling (1C/ min) with 10% dimethylsulfoxide (designated “cryopreservation”) and fast cooling (plunge in liquid nitrogen) with 20% dimethylsulfoxide and 20% ethylene glycol (“vitrification”). We compared fresh and preserved human cervicovaginal and colorectal tissues in a range of assays, including metabolic activity, human immunodeficiency virus infection, cell phenotype, tissue structure by hematoxylin-and-eosin staining, cell number and viability, production of cytokines, and microbicide drug concentrations. Metabolic activity, HIV infectability, and tissue structure were similar in cryopreserved and vitrified vaginal tissues. However, vitrification led to poor cell recovery from the colorectal mucosa, with 90% fewer cells recovered after isolation from vitrified colorectal tissues than from cryopreserved. HIV infection rates were similar for fresh and cryopreserved ectocervical tissues, whereas cryopreserved colorectal tissues were less easily infected than fresh tissues (hazard ratio 0.7 [95% confidence interval 0.4, 1.2]). Finally, we compared isolation of cells before and after cryopreservation. Cell recoveries were higher when cells were isolated after freezing and thawing (71% [59–84%]) than before (50% [38–62%]). Cellular function was similar to fresh tissue in both cases. Microbicide drug concentrations were lower in cryopreserved explants compared to fresh ones. Conclusions Cryopreservation of intact cervicovaginal and colorectal tissues with dimethylsulfoxide works well in a range of assays, while the utility of vitrification is more limited. Cell yields are higher from cryopreserved intact tissue pieces than from thawed cryopreserved single cell suspensions isolated before freezing, but T cell functions are similar.

For continuous renal replacement therapy (CRRT), the extracorporeal filter provides solute depuration, fluid removal, and control of electrolyte and acid-base balance in critically ill patients with acute kidney injury (AKI). The membranes comprising CRRT filters are almost exclusively based on hollow fiber designs and, while adapted from the chronic hemodialysis field, have features that are specific to the requirements of CRRT nevertheless. In addition, these devices have evolved through the 40 years of CRRT in response to changes in clinical practice and the desire to extend the solute removal spectrum. For some critically ill patients, more targeted removal of specific compounds poorly cleared by standard CRRT can be attempted with techniques based on adsorption. Sorbent hemoperfusion is now being applied more broadly in critically ill patients, especially in those with sepsis and systemic inflammation. In this review, the manner in which CRRT membranes and extracorporeal sorbents have evolved over the past 40 years for the treatment of critically ill patients with AKI and other disorders is described.

In vitro engineering of liver tissue is a rapidly developing field for various biomedical applications. However, liver tissue culture is currently performed on only a small scale with a low density of hepatocytes. In this study, a simple design was introduced in a liver microsystem to enhance the transport of nutrients (e.g., oxygen and glucose) for the three-dimensional large-scale, high-density culture of hepatocytes. In this design, convection across the cell culture zone was generated to mimic sinusoid blood flow (SBF) based on the pressure difference between two fluids flowing in a countercurrent manner on either side of the cell culture zone. First, the distributions of living and dead cells in different culture subzones under various perfusion flow rates were observed, analysed, and compared. Then, the enhanced transport of nutrients was experimentally validated in relation to the viability of cells and theoretically explained by comparing the fluid velocity and oxygen concentration distribution in the cell culture zone in counterflow and coflow modes. Finally, the functions of the SBF-mimicked liver microsystem were assessed on the basis of specific metabolites, synthesized proteins, and bilirubin detoxification of hepatocytes, with collagen and alginate as extracellular matrices. Under this design, the density of hepatocytes cultured at the 3-mm-thickness scale reached ~7 × 107 cells/ml on Day 7, and the metabolism and detoxification functions of the cells worked well. In addition, a liver rope-like structure and sphere-like clusters of cells were observed. This work provides insight for the design of a bionic liver microsystem.

This article first discusses some fundamentals of cryobiology and challenges for cell and tissue cryopreservation. Then, the results of cryopreservation of adipose cells and tissues, including adipose-derived stem cells, in the last decade are reviewed. In addition, from the viewpoint of cryobiology, some desired future work in fat cryopreservation is proposed that would benefit the optimization, standardization, and better application of such techniques.

Extracorporeal therapy for end-stage renal disease is now provided to more than three million patients globally. Nearly all treatments are performed with filters containing hollow fiber membranes, removing solutes and water by diffusion, convection, and ultrafiltration. In this review, we will provide a detailed quantitative analysis of the transport processes involved in different hemodialysis (HD) therapies. We will also report some technical aspects of hollow fiber membranes and filters composed of them along with the mechanisms of solute and water removal for such devices. Diffusive mass transfer will be assessed according to the three major aspects of a hollow fiber filter (blood compartment, membrane, and dialysate compartment). With regard to convective transport, the importance of internal filtration as a solute removal mechanism in high-flux HD will be highlighted, along with the critical role that blood/membrane interactions assume in filtration-based therapies.

In the process of removing cryoprotectants from cryopreserved blood, the theoretically optimal operating condition, which is based on the assumption that the distribution of red blood cells is uniform, is often used to reduce or even avoid the hypotonic damage to cells. However, due to the polydispersity of cells, the optimal condition is actually not reliable. In this study, based on the discrete concept developed in our previous work, the effect of the polydispersity on the recovery rate of cells in the dilution-filtration system was statistically investigated by assigning three random parameters, isotonic cell volume, cell surface area, and osmotically inactive cell volume, to cells in small units of blood. The results show that, due to the polydispersity, the real recovery rate deviates from the ideal value that is based on uniform distribution. The deviation significantly increases with the standard errors of cell parameters, and it can be also magnified by high cryoprotectant concentrations. Under the effect of polydispersity, the uniform distribution-based optimized blood or diluent flow rate is not perfect. In practice, one should adopt a more conservative blood or diluent flow rate so that the hypotonic damage to cells can be further reduced.

© 2017 Nature America, Inc. The ability to replace organs and tissues on demand could save or improve millions of lives each year globally and create public health benefits on par with curing cancer. Unmet needs for organ and tissue preservation place enormous logistical limitations on transplantation, regenerative medicine, drug discovery, and a variety of rapidly advancing areas spanning biomedicine. A growing coalition of researchers, clinicians, advocacy organizations, academic institutions, and other stakeholders has assembled to address the unmet need for preservation advances, outlining remaining challenges and identifying areas of underinvestment and untapped opportunities. Meanwhile, recent discoveries provide proofs of principle for breakthroughs in a family of research areas surrounding biopreservation. These developments indicate that a new paradigm, integrating multiple existing preservation approaches and new technologies that have flourished in the past 10 years, could transform preservation research. Capitalizing on these opportunities will require engagement across many research areas and stakeholder groups. A coordinated effort is needed to expedite preservation advances that can transform several areas of medicine and medical science.

To study mucosal immunity and conduct HIV vaccine trials, it is important to be able to cryopreserve mucosal specimens and recover them in functional viable form. Obtaining a good recovery depends, in part, on cooling the cells at the appropriate rate, which is determined by the rate of water transport across the cell membrane during the cooling process. In this study, the cell membrane permeabilities to water at subzero temperatures of human vaginal mucosal T cells and macrophages were measured using the differential scanning calorimetry method proposed by Devireddy et al. in 1998. Thermal histograms were measured before and after cell lysis using a Slow-Fast-Fast-Slow cooling program. The difference between the thermal histograms of the live intact cells and the dead lysed cells was used to calculate the temperature-dependent cell membrane permeability at subzero temperatures, which was assumed to follow the Arrhenius relationship, \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $$L_p ( T ) = L_ { pg } * e^ { - \frac { E_a } { R } \left( \frac { 1 } { T } - \frac { 1 } { T_r } \right) } $$ \end{document}, where Lpg is the permeability to water at the reference temperature (273.15 K). The results showed that Lpg = 0.0209 ± 0.0108 μm/atm/min and Ea = 41.5 ± 11.4 kcal/mol for T cells and Lpg = 0.0198 ± 0.0102 μm/atm/min and Ea = 38.2 ± 10.4 kcal/mol for macrophages, respectively, in the range 0°C to −40°C (mean ± standard deviation). Theoretical simulations predicted that the optimal cooling rate for both T cells and macrophages was about −3°C/min, which was proven by preliminary immune cell cryopreservation experiments.

Author(s): Hughes, Sean M; Shu, Zhiquan; Levy, Claire N; Ferre, April L; Hartig, Heather; Fang, Cifeng; Lentz, Gretchen; Fialkow, Michael; Kirby, Anna C; Adams Waldorf, Kristina M; Veazey, Ronald S; Germann, Anja; von Briesen, Hagen; McElrath, M Juliana; Dezzutti, Charlene S; Sinclair, Elizabeth; Baker, Chris AR; Shacklett, Barbara L; Gao, Dayong; Hladik, Florian | Abstract: BackgroundUnderstanding how leukocytes in the cervicovaginal and colorectal mucosae respond to pathogens, and how medical interventions affect these responses, is important for developing better tools to prevent HIV and other sexually transmitted infections. An effective cryopreservation protocol for these cells following their isolation will make studying them more feasible.Methods and findingsTo find an optimal cryopreservation protocol for mucosal mononuclear leukocytes, we compared cryopreservation media and procedures using human vaginal leukocytes and confirmed our results with endocervical and colorectal leukocytes. Specifically, we measured the recovery of viable vaginal T cells and macrophages after cryopreservation with different cryopreservation media and handling procedures. We found several cryopreservation media that led to recoveries above 75%. Limiting the number and volume of washes increased the fraction of cells recovered by 10-15%, possibly due to the small cell numbers in mucosal samples. We confirmed that our cryopreservation protocol also works well for both endocervical and colorectal leukocytes. Cryopreserved leukocytes had slightly increased cytokine responses to antigenic stimulation relative to the same cells tested fresh. Additionally, we tested whether it is better to cryopreserve endocervical cells on the cytobrush or in suspension.ConclusionsLeukocytes from cervicovaginal and colorectal tissues can be cryopreserved with good recovery of functional, viable cells using several different cryopreservation media. The number and volume of washes has an experimentally meaningful effect on the percentage of cells recovered. We provide a detailed, step-by-step protocol with best practices for cryopreservation of mucosal leukocytes.

Vasculature is an interface between the circulation and the hematopoietic tissue providing the means for hundreds of billions of blood cells to enter the circulation every day in a regulated fashion. The precise mechanisms that control the interactions of hematopoietic cells with the vessel wall are largely undefined. Here, we report on the development of an in vitro 3D human marrow vascular microenvironment (VME) to study hematopoietic trafficking and the release of blood cells, specifically platelets. We show that mature megakaryocytes from aspirated marrow as well as megakaryocytes differentiated in culture from CD34+ cells can be embedded in a collagen matrix containing engineered microvessels to create a thrombopoietic VME. These megakaryocytes continue to mature, penetrate the vessel wall, and release platelets into the vessel lumen. This process can be blocked with the addition of antibodies specific for CXCR4, indicating that CXCR4 is required for megakaryocyte migration, though whether it is sufficient is unclear. The 3D marrow VME system shows considerable potential for mechanistic studies defining the role of marrow vasculature in thrombopoiesis. Through a stepwise addition or removal of individual marrow components, this model provides potential to define key pathways responsible for the release of platelets and other blood cells.

In extracorporeal renal replacement therapies, the dialyzer is not only the site at which solute removal occurs but also the extracorporeal circuit component having the largest surface area exposed to blood. Therefore, it is not surprising that interactions between blood components and the dialyzer membrane influence the dialysis procedure in several ways. Based on engineering principles, fluid flow along a surface such as membrane results in the development of a boundary layer which can influence solute removal. Furthermore, the exposure of blood to any extracorporeal artificial surface results in the activation of several pathways within the body, including those involving coagulation and complement activation. One of the byproducts of this generalized activation process is protein adsorption to the membrane surface, another phenomenon which can have a significant impact on solute removal. In this article, a detailed review of the ways in which blood-membrane interactions influence solute removal during hemodialysis and related therapies is provided. The influences of secondary membrane formation and boundary layer/concentration polarization effects on solute removal are specifically discussed. Furthermore, the importance of adsorption as a specific removal mechanism for low-molecular weight proteins by highly permeable synthetic membranes is highlighted.

Renal replacement therapy (RRT) is required in a significant percentage of patients developing acute kidney injury (AKI) in an intensive care unit (ICU) setting. One of the foremost objectives of continuous renal replacement therapy (CRRT) is the removal of excess fluid and blood solutes that are retained as a consequence of decreased or absent glomerular filtration. Because prescription of CRRT requires goals to be set with regard to the rate and extent of both solute and fluid removal, a thorough understanding of the mechanisms by which solute and fluid removal occurs during CRRT is necessary. The following provides an overview of solute and water transfer during CRRT and this information is placed in the appropriate clinical context with a discussion of recent clinical trials assessing the relationship between CRRT dose and patient survival. Moreover, the differences between solute removal in CRRT and other dialysis modalities, especially sustained low-efficiency dialysis (SLED) and extended daily dialysis (EDD), along with the potential clinical implications are discussed.

Scientific studies on cryopreservation of adipose tissues have seldom been performed. The purpose of our present study is conducted both in vitro and in vivo to develop a novel cryopreservation method that can be used successfully for long-term preservation of human adipose tissues for possible future clinical application. In this study, samples of adipose aspirates were obtained from 36 adult white female patients after liposuction and collected from the middle layer after centrifugation. In the in vitro study, suitable cryoprotectant agents (CPAs) and their concentrations and possible combinations were selected from our preliminary experiment. A combination of dimethyl sulfoxide (Me(2)SO) and trehalose as CPA with the optimal concentration (0.5M Me(2)SO and 0.2M trehalose) was chosen and then used throughout the study. In addition, maximal recovery of adipose tissues was achieved after cryopreservation using slow cooling without seeding (1-2 degrees C/min to -30 degrees C, followed by plunging to -196 degrees C for storage) and fast warming (in 40 degrees C water bath, averaging 35 degrees C/min). Fresh adipose aspirates (Group 1), cryopreserved adipose aspirates without CPAs (Group 2), or cryopreserved adipose aspirates with CPAs (Group 3) were evaluated by integrated adipocyte counts and histology. In the in vivo study, fresh adipose aspirates (Group 1), cryopreserved adipose aspirates without CPAs (Group 2), or cryopreserved adipose aspirates with CPAs (Group 3) were injected into a nude mouse. The retained adipose aspirates (fat grafts) were harvested in each animal at 4 months and their weight, volume, and histology was assessed. In the in vitro study, significantly higher integrated viable adipocyte count (2.06+/-0.54 x 10(6)mL(-1) vs. 1.07+/-0.41 x 10(6)mL(-1), p

Direct volume rendering is widely used for three-dimensional medical data visualization such as computed tomography and magnetic resonance imaging. Distinct visualization of boundaries is able to provide valuable and insightful information in many medical applications. However, it is conventionally challenging to detect boundaries reliably due to limitations of the transfer function design. Meanwhile, the interactive strategy is complicated for new users or even experts. In this paper, we build a generalized boundary model contaminated by noise and prove boundary middle value (M) has a good statistical property. Based on the model we propose a user-friendly strategy for the boundary extraction and transfer function design, using M, boundary height (Δh), and gradient magnitude (|∇f|). In fact, it is a dynamic iterative process. First, potential boundaries are sorted orderly from high to low according to the value of their height. Then, users iteratively extract the boundary with the highest value of Δh in a newly defined domain, where different boundaries are transformed to disjoint vertical bars using M-|∇f| histogram. In this case, the chance of misclassification among different boundaries decreases.

In this work, the three-dimensional velocity and concentration fields on both the blood and dialysate sides in an artificial kidney were simulated, taking into account the effects of the flow profiles induced by the inlet and outlet geometrical structures and the interaction between the flows of blood and dialysate. First, magnetic resonance imaging experiments were performed to validate the mathematical model. Second, the effects of the flow profiles induced by the blood and dialysate inlet and outlet geometrical structures on mass transfer were theoretically investigated. Third, the clearance of toxins was compared with the clearance value calculated by a simple model that is based on the ideal flow profiles on both the blood and dialysate sides. Our results show that as the blood flow rate increases, the flow field on the blood side becomes less uniform; however, as the dialysate flow rate increases, the flow field on the dialysate side becomes more uniform. The effect of the inlet and outlet geometrical structures of the dialysate side on the velocity and concentration fields is more significant than that of the blood side. Due to the effects of the flow profiles induced by the inlet and outlet geometrical structures, the true clearance of toxins is lower than the ideal clearance, especially when the dialysate flow rate is low or the blood flow rate is high. The results from this work are significant for the structural optimization of artificial kidneys and the accurate prediction of toxin clearance.

The purpose of this study was to test the authors' hypothesis that previously cryopreserved adipose aspirates collected from conventional liposuction could still be a reliable source of human processed lipoaspirate cells.Adipose aspirates were collected from 12 adult female patients after conventional liposuction of the abdomen and were then preserved by an optimal cryopreservation method with added cryoprotective agents (0.5 M dimethyl sulfoxide and 0.2 M trehalose). Cryopreservation of the adipose tissues was subsequently conducted with controlled slow cooling and then stored in liquid nitrogen (-196 degrees C). One gram of fresh or cryopreserved (after fast rewarming) adipose aspirates was processed in vitro and the resulting cell pellet, consisting of processed lipoaspirate cells, was cultured separately. The length of time until processed lipoaspirate cells became adherent to the culture plate was recorded and the number of processed lipoaspirate cells after a 2-week culture was counted.Flat, spindle-shape processed lipoaspirate cells from the cryopreserved group became adherent to the plate within 48 to 72 hours after initial culture compared with the fresh group, where the cells became adherent by 24 hours. After a 2-week culture, the cryopreserved aspirates yielded an average of 3.7 +/- 1.4 x 10(5) processed lipoaspirate cells per milliliter, equal to 90 percent of the yielded number of cells obtained from the fresh aspirates (4.1 +/- 1.4 x 10(5) cells/ml).The authors' results indicate that although there is a latency of cell growth after an optimal cryopreservation, cryopreserved adipose aspirates can yield a significant number of processed lipoaspirate cells compared with fresh aspirates and may be a reliable source of human processed lipoaspirate cells because they can still be processed later after long-term preservation.

The novel differential scanning calorimetry method as a technique for determining human red cell volume during freezing process has been reexamined and has been shown to provide a final erythrocyte volume to be 53% of its isotonic value after freezing from 0 to −40 °C. A new type of electronic particle counter (Multisizer™ 3, Beckman Coulter Inc., USA) was used to measure cell volume changes in response to equilibration in anisotonic media, and which gave out an equilibrated volume to be 57% of cell isotonic value in solution of 3186 mOsm. Both of these results indicate that 34–40% of intracellular water is trapped and is unavailable for participation in osmotic shifts. These findings are consistent with the published data that at least 20–32% (v/v) of the isotonic cell water is retained within RBCs. Then the application of trapped water in both simulation of freezing models and freezing-drying control was pointed out.

This paper outlines a new method for measuring multilayer tissue conductivity and structure by using divided electrodes, in which current electrodes are divided into several parts. Our purpose is to estimate the multilayer tissue structure and the conductivity distribution in a cross section of the local tissue by using bioresistance data measured noninvasively. The effect of the new method is assessed by computer simulations using a typical two-dimensional (2-D) model. In this paper, the conductivity distribution in the model is analyzed based on a finite difference method (FDM) and a steepest descent method (SDM). Simulation results show that the conductivity values of skin, fat, and muscle layers can be estimated with an error of less than 0.1%. When random noise at various levels is added to the measured resistance values, estimates of the conductivity values for skin, fat, and muscle layers are still reasonably precise: their root mean square errors are about 1.06%, 1.39%, and 1.61% for 10% noise. In a 2-D model, increasing the number of divided electrodes permits simultaneous estimates of tissue structure and conductivity distribution. Optimal configuration for divided electrodes is examined in terms of dividing pattern.

Recent clinical data indicate both ultrafiltration rate (Qf) and timing of treatment initiation in continuous renal replacement therapy (CRRT) and therapy frequency in intermittent hemodialysis (HD) influence survival in critically ill patients with acute renal failure (ARF). In this study, kinetic modeling is used to compare effective dose delivery by three acute dialysis therapies: continuous venovenous hemofiltration (CVVH), daily HD, and sustained low-efficiency dialysis (SLED). A modified equivalent renal clearance (EKR) approach to account for the initial unsteady-state stage during dialysis is employed. Effective small solute clearance in CVVH is found to be 8% and 60% higher than in SLED and daily HD, respectively. Differences are more pronounced for middle and large solute categories, and EKR in CVVH is approximately 2-fold and 4-fold greater than the corresponding values in daily HD and SLED, respectively. The superior middle and large solute removal for CVVH is due to the powerful combination of convection and continuous operation. In CVVH, a decrease in the initial BUN from 150 to 50 mg/dL is predicted to decrease TAC and, therefore, increase EKR by approximately 35%. After clinical validation, the quantification method presented in this article could be a useful tool to assist in the dialytic management of critically ill ARF patients.

Increasing attention is being paid to quantifying the dose of dialysis prescribed and delivered to critically ill patients with acute renal failure (ARF). Recent trials in both the intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT) realms have suggested that a direct relationship between dose and survival exists for both of these therapies. The purpose of this review, first, is to analyze critically the above-mentioned dose/outcome studies in acute dialysis. Subsequently, the factors influencing dose prescription and delivery are discussed, with the focus on continuous venovenous hemofiltration (CVVH). Specifically, differences between postdilution and predilution CVVH will be highlighted, and the importance of blood flow rate in dose delivery for these therapies will be discussed.

The hydrogel poly(2-methacryloyloxyethylphosphorylcholine-co-butyl methacrylate), or poly(MPC-co-BMA), was used as a coating for polyurethane- and poly(vinyl chloride)-based membranes to develop ion-selective electrodes (ISEs) with enhanced blood compatibility. Adverse interactions of poly(MPC-co-BMA) with blood were diminished due to the phosphorylcholine functionalities of the hydrogel, which mimic the phospholipid polar groups present on the surface of many cell membranes. As demonstrated by immunostaining, hydrogel-coated PVC membranes soaked in platelet-rich plasma showed less adhesion and activation of platelets than uncoated PVC membranes, indicating an improvement in biocompatibility owing to the hydrogel. Furthermore, little differences in the potentiometric response characteristics, e.g., slope, detection limit, and selectivity, of ISEs employing uncoated and coated membranes were observed.

Water permeability of the plasma membrane plays an important role in making optimal cryopreservation protocols for different types of cells. To quantify water permeability effectively, automated cell volume segmentation during freezing is necessary. Unfortunately, there exists so far no efficient and accurate segmentation method to handle this kind of image processing task gracefully. The existence of extracellular ice and variable background present significant challenges for most traditional segmentation algorithms. In this paper, we propose a novel approach to reliably extract cells from the extracellular ice, which attaches to or surrounds cells. Our method operates on temporal image sequences and is composed of two steps. First, for each image from the sequence, a greedy search strategy is employed to track approximate locations of cells in motion. Second, we utilize a localized competitive active contour model to obtain the contour of each cell. Based on the first step's result, the initial contour for level set evolution can be determined appropriately, thus considerably easing the pain of initialization for an active contour model. Experimental results demonstrate that the proposed method is efficient and effective in segmenting cells during freezing.

Adipose-derived stem cells (ADSCs), which are an accessible source of adult stem cells with capacities for self-renewal and differentiation into various cell types, have a promising potential in tissue engineering and regenerative medicine strategies. To meet the clinical demand for ADSCs, cryopreservation has been applied for long-term ADSC preservation. To optimize the addition, removal, freezing, and thawing of cryoprotective agents (CPAs) applied to ADSCs, we measured the transport properties of porcine ADSCs (pADSCs). The cell responses of pADSCs to hypertonic phosphate-buffered saline and common CPAs, dimethyl sulfoxide, ethylene glycol, and glycerol were measured by a microperfusion system at temperatures of 28, 18, 8, and -2°C. We determined the osmotically inactive cell volume (Vb), hydraulic conductivity (Lp), and CPA permeability (Ps) at various temperatures in a two-parameter model. Then, we quantitatively analyzed the effect of temperature on the transport properties of the pADSC membrane. Biophysical parameters were used to optimize CPA addition, removal, and freezing processes to minimize excessive shrinkage of pADSCs during cryopreservation. The biophysical properties of pADSCs have a great potential for effective optimization of cryopreservation procedures.

In this work, the mechanism of cell bleb formation upon the addition of cryoprotectants (CPAs) was investigated, and the role of cell blebs in protecting cells was determined. The results show that after adding CPAs, the hyperosmotic stress results in the breakage of the cortical cytoskeleton and the detachment of the cell membrane from the cortical cytoskeleton, causing the formation of cell blebs. Multiple blebs decrease the intracellular hydrostatic pressure induced by the extracellular hyperosmotic shock and alleviate the osmotic damage to cells, which reduces the cell mortality rate. In the presence of a low concentration of CPAs, cell blebs can effectively protect cells. In contrast, in the presence of a high concentration of CPAs, the protective effect is limited because of severe disruption in the cortical cytoskeleton. To determine the relationship between blebs and the mortality rate of cells, we defined a bleb index and found that the bleb index of 0.065 can be regarded as a reference value for the safe addition of DMSO to HeLa cells. The bleb index can also explain why the stepwise addition of CPAs is better than the single-step addition of CPAs. Moreover, the mechanism of the autophagy of cells induced by the hyperosmotic stress was studied, and the protective effect associated with the autophagy was compared with the effect of the blebbing. The findings reported here elucidate a self-protection mechanism of cells experiencing the hyperosmotic stress in the presence of CPAs, and they provide significant evidence for cell tolerance in the field of cryopreservation.

BACKGROUND: Functional analysis of mononuclear leukocytes in the female genital mucosa is essential for understanding the immunologic effects of HIV vaccines and microbicides at the site of HIV exposure. However, the best female genital tract sampling technique is unclear. Methods and FINDINGS: We enrolled women from four sites in Africa and the US to compare three genital leukocyte sampling methods: cervicovaginal lavages (CVL), endocervical cytobrushes, and ectocervical biopsies. Absolute yields of mononuclear leukocyte subpopulations were determined by flow cytometric bead-based cell counting. Of the non-invasive sampling types, two combined sequential cytobrushes yielded significantly more viable mononuclear leukocytes than a CVL (p

The objective was to test the hypothesis that the optimal cryoprotective agent for cryopreservation of human spermatozoa would be a solute for which cells have the highest plasma membrane permeability, resulting in the least amount of volume excursion during its addition and removal. To test this hypothesis, theoretical simulations were performed using membrane permeability coefficients to predict optimal procedures for the addition and removal of a cryoprotectant. Simulations were performed using data from four different cryoprotectants: (i) glycerol, (ii) dimethyl sulphoxide, (iii) propylene glycol and (iv) ethylene glycol. Thermodynamic formulations were applied to determine approaches for the addition and removal of 1 M and 2 M final concentrations of cryoprotectant, allowing the spermatozoa to maintain a cell volume within their osmotic tolerance limits. Based on these data, ethylene glycol was predicted to be optimal for minimizing volume excursions among the solutes evaluated. These predictions were then experimentally tested using glycerol as the control cryoprotectant and ethylene glycol as the experimental cryoprotectant. The results indicate that there was a higher (P < 0.05) recovery of motile spermatozoa after cryopreservation when using 1 M ethylene glycol than with 1 M glycerol, supporting the hypothesis that use of the cryoprotectant for which the cell has the highest permeability will result in higher cell survival.

The objective of this study is to determine the cryobiological characteristics of human embryonic kidney (HEK293T) cells. The cell membrane hydraulic conductivity ( L pg ) and the activation energy of water transport ( E Lp ) were determined in the absence/presence of cryoprotectant agent (CPA), while the nucleation rate kinetic and thermodynamic parameters ( Ω o SCN and κ o SCN ) were determined in the absence of CPA. Since dehydration and intracellular ice formation (IIF) are two factors that may cause damage to cells during the freezing process, systematical freezing experiments were carried out at different cooling rates (5, 10, 15, 20, 30, and 60 °C/min) under the commercial available cryomicroscopy (FDCS 196, Linkham, Waterfield, UK) to further explore the cryoinjury mechanism for HEK293T cells. By simultaneously fitting the water transport equation to the experimentally measured volumetric shrinkage data at 5, 10, and 15 °C/min, the “combined best fit” membrane permeability parameters for HEK293T cells in both phosphate buffer saline (PBS) and CPA media (0.75M Me 2 SO in PBS) are determined. They are L pg = 2.85 × 10 −14 m/s/Pa (0.17 μm/min/atm), E Lp = 142.91 kJ/mol (34.13 kcal/mol) ( R 2 = 0.990), and L pg [ cpa ] = 2.73 ± 0.44 × 10 −14 m/s/Pa (0.16 ± 0.03 μm/min/atm), E Lp [ cpa ] = 152.52 ± 27.69 kJ/mol (36.42 ± 6.61 kcal/mol) ( R 2 = 0.993), respectively. An optimal cooling rate B opt (the highest cooling rate without IIF) was determined to be 14.24 °C/min in the absence of CPA. Additionally, the ice nucleation parameters ( Ω o SCN and κ o SCN ) were averaged to be 1.31 ± 0.11 × 10 8 m −2 s −1 and 7.67 ± 2.55 × 10 9 K 5 for the cooling rates 20, 30, and 60 °C/min.

An occupationally safe (biosafe) sputum liquefaction protocol was developed for use with a semi-automated antibody-based microtip immunofluorescence sensor. The protocol effectively liquefied sputum and inactivated microorganisms including Mycobacterium tuberculosis, while preserving the antibody-binding activity of Mycobacterium cell surface antigens. Sputum was treated with a synergistic chemical-thermal protocol that included moderate concentrations of NaOH and detergent at 60°C for 5 to 10 min. Samples spiked with M. tuberculosis complex cells showed approximately 10(6)-fold inactivation of the pathogen after treatment. Antibody binding was retained post-treatment, as determined by analysis with a microtip immunosensor. The sensor correctly distinguished between Mycobacterium species and other cell types naturally present in biosafe-treated sputum, with a detection limit of 100 CFU/mL for M. tuberculosis, in a 30-minute sample-to-result process. The microtip device was also semi-automated and shown to be compatible with low-cost, LED-powered fluorescence microscopy. The device and biosafe sputum liquefaction method opens the door to rapid detection of tuberculosis in settings with limited laboratory infrastructure.

Simple and rapid extraction of human genomic DNA remains a bottle neck for genome analysis and disease diagnosis. Current methods using microfilters require cumbersome, multiple handling steps in part because salt conditions must be controlled for attraction and elution of DNA in porous silica. We report a novel extraction method of human genomic DNA from buccal swab- and saliva samples. DNA is attracted on to a gold-coated microchip by an electric field and capillary action while the captured DNA is eluted by thermal heating at 70 °C. A prototype device was designed to handle 4 microchips, and a compatible protocol was developed. The extracted DNA using microchips was characterized by qPCR for different sample volumes, using different lengths of PCR amplicon, and nuclear and mitochondrial genes. In comparison with a commercial kit, an equivalent yield of DNA extraction was achieved with fewer steps. Room-temperature preservation for one month was demonstrated for captured DNA, facilitating straightforward collection, delivery and handling of genomic DNA in an environment-friendly protocol.

A rapid, accurate tuberculosis diagnostic tool that is compatible with the needs of tuberculosis-endemic settings is a long-sought goal. An immunofluorescence microtip sensor is described that detects Mycobacterium tuberculosis complex cells in sputum in 25 minutes. Concentration mechanisms based on flow circulation and electric field are combined at different scales to concentrate target bacteria in 1 mL samples onto the surfaces of microscale tips. Specificity is conferred by genus-specific antibodies on the microtip surface. Immunofluorescence is then used to detect the captured cells on the microtip. The detection limit in sputum is 200 CFU mL(-1) with a success rate of 96%, which is comparable to PCR.

In most cryopreservation applications, the final concentrations of cryoprotective agents (CPAs) must be reduced to biocompatible levels. However, traditional methods for removing CPAs usually have disadvantages of operation complexity, time consumption, and ease of contamination, especially for the applications involving large volumes of cell suspensions. A dilution-filtration system, which involves pure ultrafiltration for separation, was developed for continuous, automatic, and closed process of removing CPAs. To predict the optimal protocols under given experimental conditions, a theoretical model was established first. Cell-free experiments were then conducted to investigate the variation in CPA concentration during the process, and the experimental data were compared with the theoretical values for the validation of the model. Finally, ten units (212.9 ml/unit±9.5 ml/unit) of thawed human red blood cells (cryopreserved with 40% (w/v) glycerol) were deglycerolized using the theoretically optimal operation protocols to further validate the effectiveness and advantage of the system. In the cell-free experiments, glycerol was continuously removed and the concentration variations fitted the simulated results quite well. In the in-vitro experiments, glycerol concentration in RBC suspension was reduced to 5.57 g/l±2.81 g/l within an hour, and the cell count recovery rate was 91.19%±3.57%, (n=10), which proves that the system is not only safe for removing CPAs, but also particularly efficient for processing large-scale samples. However, the operation parameters must be carefully controlled and the optimal protocols should be specialized and various from case to case. The presented theoretical model provides an effective approach to find out the optimal operation protocols under given experimental conditions and constrains.

Background/Aims: In pre-dilution hemofiltration (HF), solute clearance is less than the HF rate. While the amount of this loss is predictable, it has not been validated in high-volume HF associated with high blood flow rates. Methods: Using isovolemic pre-dilution HF, we studied small solute clearances using combinations of blood flow (QB; 150, 250, 350, 450 ml/min) and replacement fluid (RF) flow (QRF; 2, 4, 6 l/h) to determine clearance losses we entitled ‘measured efficiency’ (EM). EM was compared to predicted efficiency (EP) = (QB/QB + QRF). Results: Pre-dilution produced EM values of 61–93%. Increases in QB for any QRF and decreases in QRF for any QB increased EM over a wide range of QB and QRF. EP was equivalent to EM. Conclusion: In high-volume pre-dilution HF, EP can be used to determine EM across a broad range of QB and QRF values. Higher QRF requires higher QB to minimize the attenuating effects of pre-dilution on clearance.

An optimal cooling rate is one of the critical factors influencing the survival of cells during cryopreservation. In this paper we describe a novel device, named the box-in-box, which was developed for optimal cryopreservation of human hematopoietic stem cells (HSC). This work presents the design of the device, a mathematical formulation describing the expected temperature histories of samples during the freezing process, along with actual experimental results of thermal profile tests. In experiments, when the box-in-box device was transferred from room temperature to a −80 °C freezer, a cooling rate of −1~−3.5 °C/min, which has been widely used for the cryopreservation of HSC, was achieved. In order to further evaluate this device, HSC cryopreservation was compared between the box-in-box device and a commercially available controlled rate freezer (CryoMed). The experimental data, including total cell population and CD34+ hematopoietic progenitor cell recovery rates, viability, and cell culture colony assays, showed that box-in-box worked as well as CryoMed instrument. There was no significant difference in either survival rate or the culture/colony outcome between the two devices. In conclusion, the box-in-box device can work as a cheap, durable, reliable and maintenance-free instrument for the cryopreservation of HSC. This concept of a box-in-box may also be adapted to other cooling rates to support cryopreservation in a wide variety of tissues and cells.

The correlations between various formation conditions and the membrane pore characterizations of the anodic alumina membrane were investigated for seeking the optimal conditions for the formation of anodic alumina membrane. High purity aluminum foils were used as the starting materials. The anodizations were conducted under three types of electrolytes, 3% sulfuric acid, 5% sulfuric acid and 2.7% oxalic acid, respectively, with different voltages at 0 degrees C for 48 hours. The characterizations of the pore size, the effective porosity and the pore porosity were observed and determined by scanning electron microscopy. The hydraulic conductance of the membranes was measured to confirm that the pores were open and to evaluate the permselectivity of the membranes. The experimental results showed that the ordered pore arrays were obtained for oxidation under our experimental conditions. While the forming voltage was increasing, the pore size and pore porosity increased significantly (P0.05), and the effective porosity decreased significantly (P0.05). The pore size formed with 3% sulfuric acid or 5% sulfuric acid was much smaller than that with 2.7% oxalic acid as an electrolyte. The hydraulic conductance of anodic alumina membrane that formed under our experimental condition was high than those of the membranes currently available in clinical procedures. The results suggested that the optimal conditions for the formation of anodic alumina membrane to be used in hemodialysis should be 3% or 5% sulfuric acid with 12.5 V to 17.5 V at 0 degrees C for 48 hours.

The relationship between delivered urea Kt/V and survival has raised concerns in recent outcome trials in chronic dialysis patients. Nevertheless, measurement of delivered small solute clearance remains the most common approach to quantify therapy. The purpose of this review is to provide an overview of the numerous factors influencing small solute clearance during hemodialysis. Although the focus of the review is on the manner in which dialyzer characteristics influence small solute clearances, factors related to other aspects of the extracorporeal circuit and to the patient will also be discussed.

An electromagnetic (EM) heating system is developed to achieve the rapid and uniform warming of cryopreserved biomaterials. Using the heating system, a rectangular resonant cavity is excited in TE101 mode at frequencies near 434 MHz. In experiments, a spherical phantom of biomaterial with a diameter of 36 mm is placed at the center of the cavity. The phantom is first cooled down to about −80 °C within the cavity and then thawed by EM absorption. Results show that EM warming can produce much higher warming rate than conventional water-bath warming method. The spatial temperature distribution in the phantom during EM warming is also more uniform than that during the water-bath warming.

Cryosurgery has been recently accepted as a treatment option for eradicating undesirable tissues, especially tumor tissues, due to its minimally invasive nature and low hospitalization needs. A multidimensional, finite element analysis (FEA) for the cooling, holding and rewarming processes of biological tissues during cryosurgery is presented. The tissues were treated as non-ideal materials with temperature dependent thermophysical properties. The enthalpy method has been applied to solve the non-linear problem. The influence of heating effect due to blood flow and metabolism was studied, and furthermore, the effect of pre-injecting solutions with particular thermal properties into the target tissues was also numerically studied. It was found that the heat source term due to blood flow and metabolism in the bioheat transfer equation has a significant influence on the thermal and thermal gradient histories of the target tissues, and that the method of injection of solutions with particular thermal properties into the target tissues before cryosurgery may be a possible way to optimize the treatment process. However, in vitro experiments have not fully supported this viewpoint.

Two methods used in artery deep cryopreservation, "Cryopreservation in Medium" and "Cryopreservation in Air", were studied. For the former method, samples were frozen together with a certain amount of cryoprotectants (CPA) in the cryovial or cryobag, while for the other method the arteries were first exposed to CPA and then frozen without the CPA medium surrounding in the cryovial. Study of the cryopreserved arteries using these two methods found that "cryopreservation in air" could substantially reduce the fracture rate of the arteries. To explain the difference theoretically, a two-compartment model is presented to study the thermal stresses generated during the freezing and thawing processes. The properties were measured as inputs to the model. Numerical results showed that the thermal stresses occurring in the "cryopreservation in air" process were much smaller than in the other method. The maximum thermal stress during cryopreservation occurs in the thawing process. The theoretical results could well explain published experimental results.

HELAs (Hela cells, passed cells of human cervical carcinoma) were heat or cold treated (named heat or cold shock) and then resumed normal culture for 2, 4 or 8 hours respectively. The expressions of heat shock protein 70 (HSP70) and 90 (HSP90) of the HELAs were measured by Northern and Western blotting. HELAs after 4-hour culture were exposed to or cryopreserved with different concentration of dimethyl sulfoxide (Me2SO, 2.5%, 5%, 10%, 15% and 20% respectively, V/V). Meanwhile, the HELAs after different culture time (2, 4 and 6 hours of culture) were cryopreserved with 5% Me2SO. After exposure or cryopreservation, the number of live HELAs was counted and the survival rate was calculated. The results showed that heat shock increased the expression of HSP70 and HSP90 of HELAs, while cold shock decreased the expression of the two proteins. When the concentrations of Me2SO were 10%, 15% and 20%, the survival rates of HELAs after exposure to Me2SO or cryopreservation were much lower than those when the concentrations were small. The survival rates of the heat shocked HELAs were significantly higher than those of the cold shocked and control HELAs. After cryopreservation with 5% Me2SO, the survival rate of heat shocked HELAs group with 2 hours culture time was the lowest among all the groups of HELAs with different cultural time. From the results of this study, we conclude that the expressions of HSP70 and HSP90 in HELAs increased significantly after heat shock, while cold shock decreased the expressions of these two proteins. The over-expressions of HSPs in the heat shocked HELAs could protect the cells from both injury caused by potential toxicity of high concentrations of Me2SO and cryoinjury caused by the freeze-thawing/cryopreservation procedure.