Artificial cells, blood substitutes, and immobilization biotechnology最新文献

The aim of the study presented here is to develop a biosensor based on mushroom (Agaricus bisporus) tissue homogenate for sensitive and economical determination of sulfite in foods. The working principle of the biosensor is based on an inhibition effect of sulfite on polyphenol oxidases in mushroom. Mushroom tissue homogenate was immobilized by gelatin and glutaraldehyde on a Clark-type oxygen electrode. Some optimization studies related to the bioactive layer components and working conditions were identified. The biosensor was applied to the food samples. The biosensor reported here was successfully allowed to analyze sulfite, which was a food additive in real food samples.

Polyhemoglobin-superoxide dismutase-catalase-carbonic anhydrase (PolyHb-SOD-CAT-CA) is a therapeutic antioxidant that also transports both oxygen and carbon dioxide. This is formed by crosslinking Hb with SOD, CAT, and CA using glutaraldehyde. Crosslinking stroma-free Hb from red blood cell (RBC) reduces CA activity to 55%. Addition of more CA resulted in a preparation with the same CA activity as RBC. PolyHb in the complex acts as a buffer to prevent large pH changes as carbon dioxide is converted to carbonic acid. We then prepare and optimize a novel PolyHb-SOD-CAT-CA, a therapeutic antioxidant that also transports both oxygen and carbon dioxide.

PEG-Alb represents a new class of low viscogenic plasma expanders that achieve super perfusion in vivo by mimicking the vasodilatory influence of high viscogenic plasma expanders. PEGylation-engineered structure of PEG albumin can be envisaged as a deformable molecular domain around the rigid central protein core. The correlation between the structure of PEG-shell in terms of packing of the PEG inside the PEG shell and PEGylation induced plasma expander (PE)-like properties of albumin has been investigated as a function of the number and length of the PEG-chain. The increase in molecular radius of albumin on PEGylation is non-linear as a function of the number of PEG chains conjugated. The packing density of PEG within the PEG-shell is an inverse correlate of PEG-chain size; i.e. the shorter chains pack more compactly than the longer ones. The PEGylation induced increase in the viscosity and COP of albumin is an exponential correlation of the number of ethylene oxide units (-CH(2)-CH(2)-O-) conjugated and is also a function of the PEG-chain length. At equivalence of PEG mass conjugated, the viscosity and COP of PEG-albumin adducts correlate inversely with packing density of PEG. All PEGylated albumins are not equivalent on the basis of total PEG mass conjugated. Accordingly, the structure of PEG albumin and its solution properties can be engineered to optimize a given total PEG mass for the application of PEG albumin as a resuscitation fluid. The extension arms minimize the influence of PEG shell on the structure of the protein core. We speculate that EAF-PEGylation is a preferable platform for PEGylation of protein therapeutics and is expected to generate products with better therapeutic efficacy.

Objectives: To investigate the cardioprotective effect of polymerized human placenta hemoglobin (PolyPHb) for acute myocardial ischemia rat heart.

Methods: Myocardial infarcts (MI) model was set up in SD rats by permanent ligation of the left anterior descending coronary artery (LDA). The rats were divided randomly into 3 groups with each group of 20 rats: (A) the control group with the administration of Ringer's lactated solution at a dose of 2.5ml/kg); (B) PolyPHb group, PolyPHb solution at a dose of 0.16g Hb/kg and (C), PolyPHb+CAT+SOD group, PolyPHb solution at a dose of 0.16g Hb/kg and catalase (CAT) solution and superoxide dismutase (SOD) solution at a dose of 1681 U/kg and 528000 U/kg, respectively. Each rat received treatments via caudal vein, once a day for 7 days. Qualitative evaluations were made based on the reading of cardiac troponin T (cTnT), the myocardial infarction size (MIS) derived from the staining of myocardium tissue, and the pathological changes in infarct area. The ischemia changes of cardiomyocytes were determined by haematoxylin - basic fuchsin - picric acid (HBFP) staining and the apoptosis of cardiomyocytes were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay (TUNEL).

Results: Compared to the control group, PolyPHb greatly decreased the cTnT (p < 0.05), MIS (p < 0.05), and the size of myocardial ischemia (p < 0.05). PolyPHb + CAT + SOD decreased the △ST change (P < 0.05), cTnT (P < 0.01), MIS (p < 0.05), the pathological scores (p < 0.01), the size of myocardial ischemia (p < 0.01), and the apoptosis level (p < 0.01).

Conclusion: Our study demonstrated that adding PolyPHb improves cardiac functional recovery and reduces myocardial infarction of rat heart.

A novel bioreactor containing viable APA microencapsulated yeast cells was designed. Rat plasma was used for perfusion. Yeast cell loading and perfusion flow rate were studied to maximize urea removal. An increase in column loading from 25% to 100%, increased urea removal from 5.67 ± 1.34% to 30.45 ± 0.48%. An increase in flow rate from low to high, increased urea removal from 30.46% to 40.4%. At 100% column loading and high flow rate, the creatinine and phosphate concentrations decreased by 22% and 10%, respectively, while ammonia concentrations increased by 58.9% (p < 0.05). Our in-vitro perfusion study demonstrates that microencapsulated yeast cells can remove urea efficiently.

We cultured isolated islets from human or porcine origin in the presence or absence of IL1 and TNFα and studied cytoprotective effects of two structurally different PBR ligands. Storage of pig or human islets in the presence of cytokines significantly lowered the fraction of vital beta-cells. Compared with cytokine incubations PK11195 alone or in combination with cytokines was effective to prevent cytokine induced cell death. The data indicate that cold storage in the presence of PK11195 may further protect beta-cells from cytokine induced cell death. This ligand may be helpful to preserve beta-cell survival before transplantation.

A low-cost and sensitive amperometric biosensor was developed for the determination of α-amylase activity. The biosensor was constructed by immobilizing glucose oxidase-gelatin via glutaraldehyde on the Au electrode surface. Measurements were carried out chronoamperometrically at -0.7 V. Several parameters such as glucose oxidase activity, gelatin amount, and glutaraldehyde percentage for cross-linking were optimized. Optimum pH, optimum temperature, repeatability, and storage stabilities of the biosensor were identified. Under the optimum experimental conditions, a linear calibration curve was obtained for α-amylase between 0.819 and 13.110 U/ml. Sample analyses were carried out by detecting α-amylase activities in baker's yeast samples.

We prepared the sirolimus liposome by rapid expansion of supercritical solution (RESS) technology of supercritical fluid, and studied the effects of temperature, pressure, and equilibrium time on the average particle size and envelop rate of liposome. The conditions of the minimal average particle size of liposome were 328K of temperature (35MPa), 35MPa of pressure (333K), and 50 minutes of equilibrium (343K) time, respectively. The conditions of the maximal envelop rate of liposome were 333K of temperature (30MPa), 35MPa of pressure (343K), and 50 minutes of equilibrium (323K) time, respectively.

Resuscitation of hemorrhagic shock requires volume replacement and restoration of oxygen metabolism. Artificial oxygen carriers that can both expand blood volume and deliver oxygen have been developed as resuscitation fluids. We employed hemoglobin vesicles (HbV), a cellular-type artificial oxygen carrier, in a Beagle dog hemorrhagic shock model to prove the efficacy of HbV. Hemorrhagic shock was introduced in splenectomized Beagle dogs by withdrawing 50% of circulating blood from the femoral artery. Shock was maintained for 60 minutes before isovolemic resuscitation with HbV dispersed in 5% albumin in saline (HbV), lactated Ringer's solution (LR), 5% human serum albumin in saline (HSA), or autologous shed blood (ASB). One animal in the LR group died 150 min after resuscitation. All other animals survived 4 h of the experiment. The mean arterial pressure remained significantly lower in the LR group than in the HbV group but did not differ significantly among the HbV, Alb, and ASB groups. Immediately after resuscitation, the HbV group showed a significantly higher mean pulmonary arterial pressure, which decreased within 10 minutes to the baseline level. The cardiac output was significantly higher in the Alb group than in the others, indicating compensation for low oxygen delivery per unit blood. The post-resuscitation hematocrit was 36% in the ASB group and decreased in the other groups (20-22%). Serum chemistry data from the HbV group were unremarkable. HbV contributed 32% of the post-resuscitation oxygen delivery. Collectively, HbV is comparable to ASB and HSA as a resuscitation fluid and is an effective oxygen carrier.

Targeted and simultaneous delivery VEGF165b and IFN alpha in anti-angiogenic and other applications could offer several advantages. For this a system was design using artificial cell alginate-poly-L-lysine- alginate (APA) microcapsules. Result confirms the ability of this system for simultaneous production of these proteins for 28-days. The IFN alpha on a 3 days period increased from 8 ± 0.36 μg/ml at day 10 to 27 ± 2.4 μg/ml at day 16 and then dropped to 6.5 ± 0.5 μg/ml. The VEGF165b on a 3 days period increased from 2.7 ± 0.7 μg/ml at day 10 to 6.9 ± 1 μg/ml at day 16.