Concentrations Of Galactose Research Articles

Hyaluronic acid production by recombinant Streptococcus thermophilus

Generally recognized as safe, Streptococcus thermophilus was transformed using a plasmid expressing endogenous hyaluronic acid (HA) synthase genes. A single expression of hyaluronic acid synthase (hasA), uridine diphosphate-glucose dehydrogenase gene (hasB), or pyrophosphorylase gene (glmU) and double expression of hasA and hasB were attempted. A streptococcus-Escherichia coli shuttle vector, pBE31, was successfully transfected in S. thermophilus. The single expression of hasA or hasB allowed S. thermophilus to produce about 0.5-1.0 g/l HA. The strains coexpressing of hasA and hasB showed a markedly increased HA production (1.2g/l) which was six-fold increase compared with the wild-type strain. The maximum cell concentration and specific growth rate of each recombinant strain were lower than those of the wild-type strain; however, the specific production rate was more than 100-fold higher. Galactose concentration decreased in the coexpressing strain after depletion of lactose. The bacterial metabolism would be altered in order to achieve a higher production by changing the intracellular metabolism. The average molecular weight of HA (1.0 × 10(6) Da) was not affected by the expression of hasA and hasB. HA produced from recombinant strain could be an alternative material for medical, cosmetic and food utilization instead of HA from conventional pathogenic streptococci.

Modulation of antibody galactosylation through feeding of uridine, manganese chloride, and galactose

Through process transfer and optimization for increased antibody production to 3 g/L for a GS-CHO cell line, an undesirable drop in antibody Fc galactosylation was observed. Uridine (U), manganese chloride (M), and galactose (G), constituents involved in the intracellular galactosylation process, were evaluated in 2-L bioreactors for their potential to specifically increase antibody galactosylation. These components were placed in the feed medium at proportionally increasing concentrations from 0 to 20 × UMG, where a 1× concentration of U was 1 mM, a 1× concentration of M was 0.002 mM, and a 1× concentration of G was 5 mM. Antibody galactosylation increased rapidly from 3% at 0× UMG up to 21% at 8× UMG and then more slowly to 23% at 20× UMG. The increase was primarily due to a shift from G0F to G1F, with minimal impact on other glycoforms or product quality attributes. Cell culture performance was largely not impacted by addition of up to 20× UMG except for suppression of glucose consumption and lactate production at 16 and 20× UMG and a slight drop in antibody concentration at 20× UMG. Higher accumulation of free galactose in the medium was observed at 8× UMG and above, coincident with achieving the plateau of maximal galactosylation. A concentration of 4× UMG resulted in achieving the target of 18% galactosylation at 2-L scale, a result that was reproduced in a 1,000-L run. Follow-up studies to evaluate the addition of each component individually up to 12× concentration revealed that the effect was synergistic; the combination of all three components gave a higher level of galactosylation than addition of the each effect independently. The approach was found generally useful since a second cell line responded similarly, with an increase in galactosylation from 5% to 29% from 0 to 8× UMG and no further increase or impact on culture performance up to 12× UMG. These results demonstrate a useful approach to provide exact and specific control of antibody galactosylation through manipulation of the concentrations of uridine, manganese chloride, and galactose in the cell culture medium.

Determination of the transgalactosylation activity of Aspergillus oryzae β-galactosidase: effect of pH, temperature, and galactose and glucose concentrations

The catalytic potential of β-galactosidase is usually determined by its hydrolytic activity over natural or synthetic substrates. However, this method poorly predicts enzyme behavior when transglycosylation instead of hydrolysis is being performed. A system for determining the transgalactosylation activity of β-galactosidase from Aspergillus oryzae was developed, and its activity was determined under conditions for the synthesis of galacto-oligosaccharides and lactulose. Transgalactosylation activity increased with temperature up to 55°C while the effect of pH was mild in the range from pH 2.5 to 5.5, decreasing at higher values. The effect of glucose and galactose on transgalactosylation activity was also assessed both in the reactions for the synthesis of galacto-oligosaccharides and lactulose and also in the reaction of hydrolysis of o-nitrophenyl β-d-galactopiranoside. Galactose was a competitive inhibitor and its effect was stronger in the reactions of transgalactosylation than in the reaction of hydrolysis. Glucose was a mild activator of β-galactosidase in the reaction of hydrolysis, but its mechanism of action was more complex in the reactions of transgalactosylation, having this positive effect only at low concentrations while acting as an inhibitor at high concentrations. This information is relevant to properly assess the effect of monosaccharides during the reactions of the synthesis of lactose-derived oligosaccharides, such as galacto-oligosaccharides and lactulose.

A novel amperometric galactose biosensor based on galactose oxidase-poly(N-glycidylpyrrole-co-pyrrole)

A novel amperometric galactose biosensor was constructed by immobilization of galactose oxidase (GAox) onto poly(N-glycidylpyrrole-co-pyrrole) film. GAox enzyme was immobilized onto the electrochemically prepared novel conducting polymer film by direct one-step covalent attachment without using any coupling agents. The biosensor surface was characterized by FT-IR spectroscopy and atomic force microscopy (AFM). Amperometric response was measured as a function of concentration of galactose, at fixed potential of +0.7 V vs. Ag/AgCl in a phosphate buffered saline (pH 7.5). The mediated hydrogen peroxide biosensor had a fast response of less than 5 s with linear range 2–16 mM. The sensitivity of the biosensor for galactose was 1.75 μA/mM. The factors influencing on the performance of the resulting biosensor were studied in detail.

Acclimation of poplar trees to heavy metals in polluted habitats: l. Carbohydrate metabolism in fine roots of Populus deltoides

Concentrations of total nonstructural carbohydrates (TNC), soluble carbohydrates, starch, sucrose, glucose, fructose, raffinose, galactose, stachyose, mannitol and specific activities of soluble acid (AI) and neutral (NI) invertases, sucrose synthase (SuSy), hexokinase (HK), fructokinase (FK), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and glucose 6-phosphate dehydrogenase (G6PDH) were analyzed in fine roots of <em>Populus deltoides</em> Bartr. ex Marsh growing at a polluted site (near copper smelters) and a control site (free from heavy pollution). Also chemical properties of the soil from both sites were assessed. In comparison with the control, fine roots from the polluted site contained greater concentrations of TNC, soluble sugars, starch and sucrose but less hexoses, so they had higher values of sucrolysis index (sucrose/hexoses). The activity of AI, NI and SuSy declined insignificantly, while specific activities of HK, FK, GAPDH and G6PDH were significantly inhibited. The results suggest that a long-term heavy metal stress leads to an accumulation of carbohydrates and altering activities of glycolysis and the oxidative pentose phosphate pathway in fine roots.

Can One Point-Of-Care Glucose Meter Be Used for All Pediatric and Adult Hospital Patients? Evaluation of Three Meters, Including Recently Modified Test Strips

within hospitals, bedside blood glucose measurements are widely used for investigating suspected hyper- or hypoglycemia, monitoring diabetes, and adjusting glucose-lowering medication. Numerous point-of-care glucose meters are available, but for large hospitals using the same meter in all settings has practical and economic advantages. This investigation sought to identify a meter that was accurate, precise, and free from interferences, making it suitable for use across all ages and diseases. lithium-heparinized whole blood was analyzed, under various conditions, on the HemoCue Glucose 201 (Hemocue AB, Ängelhom, Sweden), Accu-Chek Performa (Roche Diagnostics, Basel Switzerland) (using the newly reformulated maltose-insensitive strips), and Optium (Abbott Diabetes, Alameda, CA, USA) glucose meters and compared with plasma glucose measurements on the Vitros 5,1 FS analyzer (Ortho Clinical Diagnostics, Neckargemund, Germany). biases of 3.2%, -5.8%, and -8% were found with Accu-Chek, Optium, and HemoCue, respectively. Within-run imprecision was 2.5-5.8%. Between-run imprecision was 3.1-6.8%, with the Accu-Chek performing best. All meters measured to 1.3 mmol/L with acceptable precision (coefficient of variation, <14%). Varying hematocrits between 0.2 and 0.7 L/L affected results of all meters. Interference at clinically relevant concentrations of galactose and possibly maltose was demonstrated with the Accu-Chek. all three meters are sufficiently accurate and precise for in-hospital use. Because of possible interference by galactosemia or high hematocrit, the Accu-Chek is not the safest option for neonatal use. Patients receiving high doses of maltose in therapeutic infusions may still be at risk of being falsely classified as euglycemic or hyperglycemic with the reformulated Accu-Chek strips, and clinical evaluation of these strips in patients receiving maltose-containing infusions is urgently needed.

Production of Ethanol from Sugars Fermentation By Yeasts Using Bioreactor

Two yeast isolates of C.kefyr-T and C.kefyr-S, were isolated from crude whey, the optimum pH value was 5, and S.cerevisiae was significantly best in ethanol and Biomass production from all glucose concentrations compared to C.kefyr-T and C.kefyr-S which were significantly best ethanol and biomass production from all galactose concentrations comparing with S.cerevisiae. C.kefyr-T which was best in production compared to C.kefyr-S. Best ethanol production was 8.7% Ethanol from 10% sugar mixture, by mixed culture of (S. cerevisiae+ C.Kefyr-T), and best ethanol production was 4.6% from 8% synthetic lactose by mixed culture of (C.kefyr-T+C.kefyr-S). There is a significant decrease in ethanol and biomass production from all mixtures by using mixed culture of (C.kefyr-T+ C.kefyr-S+ S. cerevisiae) than using mixed culture of (C. kefyr + S. cerevisiae) and mixed culture of (C.kefyr-T + C.kefyr-S). Different period of times at (24, 36, 48, and 60) hof fermentation in bioreactor are presented. The initial sugar mixture concentration was 10% in all cases. The ethanol production during the 48 h gave a maximum value of 15.5 % by mixed culture of (C. kefyr + S. cerevisiae), but it remains at low levels within other periods, whereas the highest biomass16% gained at the same bioreactor conditions.

Quantitative ultramicrotest for newborn screening of galactosemia in Cuba

To describe a simple, rapid, quantitative ultramicrotest (UMTEST) based on the fluorometric method introduced by Fujimura et al. adapted to an Ultra Micro Analytic System (SUMA) for the detection of total galactose (GAL) in dried blood specimens. The assay uses 3 mm discs of dried blood on Whatman 903 filter paper and small volumes of each reagent. A methanol/acetone/water solution is used for deproteination, and a specially designed 96-well polystyrene opaque ultramicroplates, with a maximum capacity of 30 μL per well, are used for the reading. The UMTEST GAL is completed in 2 h, with measuring range of 0.28-3.92 mmol/L. The intra- and inter-assay coefficients of variation were 2.3%-8.9% and 6.8%-11.1%, respectively, depending on the total GAL concentrations. Percentage recovery ranged from 97.7% to 103%. Limit of detection and limit of quantitation were 0.06 and 0.16 mmol/L, respectively. The mean GAL concentration, in 2510 dried blood samples from the National Neonatal Screening Program was 0.23 mmol/L. Our assay showed high concordance correlations with the commercially available ICN Immuno-Chem™ GAL-MW EA kit. The analytical performance characteristics of this assay is suitable for mass newborn screening of galactosemia in Cuba.

Polissacarídeos extraídos da gabiroba (Campomanesia xanthocarpa Berg): propriedades químicas e perfil reológico

A Campomanesia xanthocarpa Berg (Myrtaceae) é uma frutífera nativa brasileira, com ampla distribuição natural na região Sul. Embora apresente frutificação abundante, produza frutos com características sensoriais e nutricionais atrativas, esses não são coletados e se perdem nos campos. Neste trabalho, a polpa do fruto sem semente (1500 g) foi triturada em etanol / água na proporção de 1:4 (v/v), refluxada por 15 minutos em temperatura de ebulição. O resíduo obtido foi submetido a extrações sequenciais. As extrações foram otimizadas utilizando um planejamento fatorial 2², tendo como variáveis a concentração do ácido cítrico (0,5 e 5%) e a temperatura (50 e 100 ºC). Os polissacarídeos provenientes de diferentes extrações foram caracterizados quanto à composição química e perfil reológico. Os altos teores de ácidos urônicos, arabinose e galactose detectados em todas as frações, indicam que estas são constituídas por polissacarídeos pécticos. Os polissacarídeos extraídos da polpa da gabiroba apresentaram um comportamento pseudoplástico. Todas as frações apresentaram como característica resistência frente às variações de temperatura. Quando submetidas a ciclos de aquecimento e posterior resfriamento estes géis retornam à sua estrutura original.

Age-dependency of galactose elimination capacity in healthy children and children with chronic liver disease

Objective. Galactose elimination capacity (GEC) is used as a quantitative measure of liver metabolic function with prognostic value in adults with acute and chronic liver failure. Almost no data are available regarding GEC in children, however. This study thus aims to meet the previously unmet clinical need for age-related data on GEC in children. Material and methods. We studied galactose elimination in 10 healthy children (median age 10.7 years; range 7 months to 16 years) and 30 children with chronic liver disease (median age 8.6 years; range 3 months to 16 years). GEC was estimated from the linear decrease in concentration of galactose in arterialized capillary blood from the ear following intravenous infusion of galactose. Results. In both groups of children, GEC (μmol/min/kg body weight) was highest in the youngest children and decreased with age, although at a significantly lower level in the children with liver disease (p = 0.05). GEC was significantly higher in healthy children than in healthy adults, diminishing to the adult level by the age of 16 years. Conclusions. GEC was found to be higher in children than in adults until the age of 16 years. Moreover, GEC was significantly lower in children with chronic liver disease than in healthy children, underlining that GEC testing also has potential clinical usefulness as a quantitative measure of liver metabolic function in children.

Isolation and Purification of Jacalin from Artocarpus Heterophyllus Lam

This paper presents investigation results of saturation conditions needed for purification of jacalin lectin from the extract seeds of Artocarpus heterophyllus by ammonium precipitation and affinity chromatography on Galactose-Affi gel Hz. Three different aspects of parameters encompassing the percentage of saturation of ammonium sulfate precipitation, the presence of ammonium sulfate on Lowry method and the suitable galactose concentration for optimum elution of the protein from Galactose-Affi gel Hz were investigated. With three different sets of fractional saturation of jacalin purification using ammonium sulfate precipitation, the maximum yield of 0.463 g/g was achieved at 0-90% saturation range in the absence of dialysis. Maximum yield of 0.425 g/g was obtained at 30-60% and 0-90% saturation range in the presence of dialysis. The result from this work also indicates that excessive quantity of NH4SO4 interferes with Lowry method for protein determination substantially. The 0-90% saturation range was found to be more potentially appropriate for large scale application than 30-60% saturation, since the former involves only 1 step NH4SO4 addition. From the affinity chromatography, elution of 0.2 M galactose (in 0.15 M NaCl) from Galactose-Affi gel Hz produced the maximum peak profile and jacalin concentration. A reduction or increase in galactose concentration of more than 0.2 M did not increase concentration of purified jacalin purified using this method.

Determination of hepatic galactose elimination capacity using 2-[18F]fluoro-2-deoxy-d-galactose PET/CT: reproducibility of the method and metabolic heterogeneity in a normal pig liver model

Objective. A PET method is developed for non-invasive measurement of regional metabolic liver function using the galactose analog 2-[18F]fluoro-2-deoxy-d-galactose, FDGal. The aim of the present study was to determine the reproducibility of the method in pigs before translating it to human studies. Material and methods. Five anesthetized pigs were studied twice within an interval of three days. A dynamic PET recording was performed with an injection of 100 MBq FDGal. Non-radioactive galactose was administered throughout the PET recordings to achieve near-saturated elimination kinetics. Arterial blood samples were collected for determination of blood concentrations of FDGal and galactose (cgal). Net metabolic clearance of FDGal, KFDGal, was calculated from linear representation of data. The approximate maximal hepatic removal rate, Vmax, of galactose (mmol/l tissue/min) was calculated as KFDGal cgal. The estimates from Day 1 and Day 2 were compared and the coefficient of variation, COV, of the estimates calculated. Functional heterogeneity in normal pig liver was evaluated as COV of the tissue concentration of radioactivity during quasi steady-state metabolism. Results. There was no significant difference between Vmax from Day 1 and Day 2 (p = 0.38), and the reproducibility was good with a COV of 14% for the whole liver. In normal pig liver tissue, mean COV after an injection of FDGal was on average 15.6% with no day-to-day variation (p = 0.7). Conclusions. The novel FDGal PET method for determination of hepatic metabolic function has a good reproducibility and is promising for future human studies of regional liver function.

Monitoring of Biochemical Status in Children with Duarte Galactosemia: Utility of Galactose, Galactitol, Galactonate, and Galactose 1-Phosphate

Duarte galactosemia (DG) is frequently detected in newborn-screening programs. DG patients do not manifest the symptoms of classic galactosemia, but whether they require dietary galactose restriction is controversial. We sought to assess the relationships of selected galactose metabolites (plasma galactose, plasma galactitol, erythrocyte (RBC) galactitol, RBC galactonate, and urine galactitol and galactonate) to RBC galactose 1-phosphate (Gal-1-P), dietary galactose intake, and neurodevelopmental/clinical outcomes in DG children. We studied 30 children 1-6 years of age who had DG galactosemia and were on a regular diet. All participants underwent a physical and ophthalmologic examination and a neurodevelopmental assessment. RBC galactitol, RBC galactonate, RBC Gal-1-P, plasma galactose, plasma galactonate, and urine galactitol and galactonate concentrations were measured. RBC galactitol and galactonate concentrations were about 2 and 6 times higher, respectively, than control values. Plasma galactose and galactitol concentrations were also about twice the control values. The mean values for RBC Gal-1-P and urine galactitol were within the reference interval. We found a relationship between plasma and urine galactitol concentrations but no relationship between RBC galactose metabolites and urine galactitol. There was a significant relationship between galactose intake and RBC galactose metabolites, especially RBC galactitol (P < 0.0005) and RBC galactonate (P < 0.0005). Galactose intake was not related to the urine galactitol, plasma galactose, or plasma galactitol concentration. RBC galactitol, RBC galactonate, plasma galactose, plasma galactitol, and urine galactonate concentrations showed no relationship with clinical or developmental outcomes. DG children on a regular diet have RBC Gal-1-P concentrations within the reference interval but increased concentrations of other galactose metabolites, including RBC galactitol and RBC galactonate. These increased concentrations correlate with galactose intake and neither cause any developmental or clinical pathology during early childhood nor oblige a lactose-restricted diet.

Gastric emptying of hexose sugars: role of osmolality, molecular structure and the CCK1 receptor

It is widely reported that hexose sugars slow gastric emptying (GE) via osmoreceptor stimulation but this remains uncertain. We evaluated the effects of a panel of hexoses of differing molecular structure, assessing the effects of osmolality, intra-individual reproducibility and the role of the CCK(1) receptor, in the regulation of GE by hexoses. Thirty one healthy non-obese male and female subjects were studied in a series of protocols, using a (13) C-acetate breath test to evaluate GE of varying concentrations of glucose, galactose, fructose and tagatose, with water, NaCl and lactulose as controls. GE was further evaluated following the administration of a CCK(1) receptor antagonist. Three subjects underwent repeated studies to evaluate intra-individual reproducibility. At 250 mOsmol, a hexose-specific effect was apparent: tagatose slowed GE more potently than water, glucose and fructose (P < 0.05). Fructose (P < 0.05) also slowed GE, but with substantial inter-, but not intra-, individual differences. As osmolality increased further the hexose-specific differences were lost. At 500 mOsmol, all hexoses slowed GE compared with water (P < 0.05), whereas lactulose and saline did not. The slowing of GE by hexose sugars appeared to be CCK(1) receptor-dependent. The effects of hexose sugars on GE appear related to their molecular structure rather than osmolality per se, and are, at least in part, CCK(1) receptor-dependent.

Roles of extracellular lactose hydrolysis in cellulase production by Trichoderma reesei Rut C30 using lactose as inducing substrate

Lactose, an inexpensive, soluble substrate, offers reasonably good induction for cellulase production by Trichoderma reesei. The fungus does not uptake lactose directly. Lactose is hydrolyzed to extracellular glucose and galactose for subsequent ingestion. The roles of this extracellular hydrolysis step were investigated in this study. Batch and continuous cultures were grown on the following substrates: lactose, lactose–glycerol mixtures, glucose, galactose, and glucose–galactose mixtures. Cell growth, substrate consumption, lactose hydrolysis, and lactase and cellulase production were followed and modeled. Cells grew much faster on glucose than on galactose, but with comparable cell yields. Glucose (at >0.3 g/L) repressed the galactose consumption. Cellulase synthesis was growth-independent while lactase synthesis was growth-dependent, except at D < ∼0.065 h −1 where a basal level lactase production was observed. For cellulase production the optimal D was 0.055–0.065 h −1 where the enzyme activity and productivity were both near maxima. The model suggested that lactase synthesis was subject to weak galactose repression. As the galactose concentration increased at high D (>0.1 h −1), lactase synthesis became repressed. The insufficient lactase synthesis limited the lactose hydrolysis rate. Extracellular lactose hydrolysis was concluded to be the rate-limiting step for growth of T. reesei Rut C30 on lactose.

Short communication: Presence of galactose and glucose promotes browning of sweet whey powder

This research examined the role of sugar type on the browning of sweet whey powder during accelerated storage. Two model systems, a lactose-lysine system and a sweet whey powder system, were selected. Within each model system experiment were samples containing equimolar concentrations of lactose, galactose, and glucose, and model systems were studied at 3 pH values: 6.5, 6.0, and 5.5. Samples were analyzed for changes in color after accelerated browning at 80°C for 24h. The results showed that the samples containing galactose and glucose browned to a greater degree than those containing lactose. Browning in the control and lactose-enriched samples was more susceptible to changes in pH. This study indicates that the processing conditions of liquid whey in which the lactose monomers glucose and galactose accumulate may predispose SWP to brown more readily.

Bacterial chemotaxis and entropy production

Entropy production is calculated for bacterial chemotaxis in the case of a migrating band of bacteria in a capillary tube. It is found that the speed of the migrating band is a decreasing function of the starting concentration of the metabolizable attractant. The experimentally found dependence of speed on the starting concentration of galactose, glucose and oxygen is fitted with power-law functions. It is found that the corresponding exponents lie within the theoretically predicted interval. The effect of the reproduction of bacteria on band speed is considered, too. The acceleration of the band is predicted due to the reproduction rate of bacteria. The relationship between chemotaxis, the maximum entropy production principle and the formation of self-organizing structure is discussed.

Stability analysis of the GAL regulatory network in Saccharomyces cerevisiae and Kluyveromyces lactis

BackgroundIn the yeast Saccharomyces cerevisiae, interactions between galactose, Gal3p, Gal80p, and Gal4p determine the transcriptional status of the genes required for the galactose utilization. Increase in the cellular galactose concentration causes the galactose molecules to bind onto Gal3p which, via Gal80p, activates Gal4p, which induces the GAL3 and GAL80 gene transcription. Recently, a linear time-invariant multi-input multi-output (MIMO) model of this GAL regulatory network has been proposed; the inputs being galactose and Gal4p, and the outputs being the active Gal4p and galactose utilization. Unfortunately, this model assumes the cell culture to be homogeneous, although it is not so in practice. We overcome this drawback by including more biochemical reactions, and derive a quadratic ordinary differential equation (ODE) based model.ResultsWe show that the model, referred to above, does not exhibit bistability. We establish sufficiency conditions for the domain of attraction of an equilibrium point of our ODE model for the special case of full-state feedback controller. We observe that the GAL regulatory system of Kluyveromyces lactis exhibits an aberration of monotone nonlinearity and apply the Rantzer multipliers to establish a class of stabilizing controllers for this system.ConclusionFeedback in a GAL regulatory system can be used to enhance the cellular memory. We show that the system can be modeled as a quadratic nonlinear system for which the effect of feedback on the domain of attraction of the equilibrium point can be characterized using linear matrix inequality (LMI) conditions that are easily implementable in software. The benefit of this result is that a mathematically sound approach to the synthesis of full-state and partial-state feedback controllers to regulate the cellular memory is now possible, irrespective of the number of state-variables or parameters of interest.

Development of a Disposable Microfluidic Biochip for Multiparameter Cell Population Measurements

An under recognized cause of preventable mortality is healthcare-associated (nosocomial) infections such as biofilms found on implants and catheters. About 5% of U.S. and E.U. patients acquire nosocomial infections leading to prolonged hospitalization, increased patient suffering, and mortality rates. To date, no satisfactory solutions are available to monitor biofilm formation under near-native conditions. As a consequence, in the present work, we report the development of a disposable microfluidic biochip capable of continuously monitoring cell population dynamics under physiological shear force conditions. We demonstrate the simultaneous application of contactless bioimpedance spectroscopy and amperometric measurements to monitor fungal biofilm growth rates and metabolic activities. Quantitative cell analysis is accomplished by the use of high-density interdigitated capacitors (microIDC) isolated by a 700 nm epoxy (SU-8 resist) based passivation layer to noninvasively assess biofilm formation in predefined proliferation chambers. Additionally, biofilm respiration activity is measured using redox-mediators oxidized at band electrodes located downstream within microchannels. The disposable biofilm analysis platform is used to continuously monitor the dynamic responses of C. albicans to different glucose and galactose concentrations.

Effects of pre-freeze incubation of human red blood cells with various sugars on postthaw recovery when using a dextran-rapid cooling protocol

Polymer has been used as substitute to replace glycerol for cryopreservation of red blood cells (RBCs). But polymer can not penetrate cell membrane, it can not efficiently protect the inner membrane. In this study, RBCs were incubated with glucose, fructose, galactose or trehalose and frozen in liquid nitrogen for 24h using dextran as the extracellular protectant. The postthaw quality was assessed by RBC hemolysis, RBC morphology, PS distribution, osmotic fragility, and the 4°C stability. The results indicated the loading efficiency of monosaccharide was significantly higher than that of trehalose. Adding trehalose and 40% dextran caused more serious hemolysis before freezing. The percent hemolysis of RBCs loaded with high concentration of trehalose was approximately 16% and significantly more than that of RBCs loaded with glucose (approximately 5%, P<0.05). Intracellular trehalose can not increase the postthaw recovery of RBCs compared with cells frozen without sugar. However, low concentration of intracellular glucose or galactose can reduce the percent hemolysis to less than 5% and significantly less than that of RBCs frozen without sugar (P<0.05). Finally, the ability of galactose or fructose to maintain the 4°C stability was significantly more than that of glucose. In conclusion, the injuries caused by trehalose loading may directly lead to postthaw hemolysis and poor quality of RBCs. However, monosaccharide can enhance the recovery of frozen RBCs. The cryoprotective effect of galactose may be better than that of glucose or fructose. In the future, we will continue to look for a safe and efficient trehalose loading process and try to decrease the osmotic fragility of RBCs frozen with polymers and sugars.