Gel Tubes Research Articles

Depletion of hemoglobin and carbonic anhydrase from erythrocyte cytosolic samples by preparative clear native electrophoresis

Proteomic analysis of red cells is compromised by the presence of high-abundance proteins (hemoglobin and carbonic anhydrase-1), which completely obscure low-abundance species. The depletion method presented here involves performing native gel electrophoresis in a polyacrylamide gel tube using a modified electroelution cell. The electrophoretic run is interrupted intermittently to allow the recovery of at least three different liquid fractions, which can be analyzed by both native PAGE and 2D isoelectric focusing SDS-PAGE, or by shotgun mass spectrometry analysis after trypsin in-solution protein digestion. This low-cost, reproducible technique can be used to process large amounts of sample, and it increases the likelihood of detecting low-abundance proteins, thereby resulting in greater proteome coverage. The separation procedure takes approximately 6-7 h.

Integration of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in blood culture diagnostics: a fast and effective approach

Sepsis is a major cause of mortality in hospitalized patients worldwide, with lethality rates ranging from 30 to 70 %. Sepsis is caused by a variety of different pathogens, and rapid diagnosis is of outstanding importance, as early and adequate antimicrobial therapy correlates with positive clinical outcome. In recent years, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) fingerprinting has become a powerful tool in microbiological diagnostics. The direct identification of micro-organisms in a positive blood culture by MALDI-TOF MS can shorten the diagnostic procedure significantly. Therefore, the aim of the present study was to evaluate whether identification rates could be improved by using the new Sepsityper kit from Bruker Daltonics for direct isolation and identification of bacteria from positive blood cultures by MALDI-TOF MS compared with the use of conventional separator gel columns, and to integrate the MALDI-TOF MS-based identification method into the routine course of blood culture diagnostics in the setting of a microbiological laboratory at a university hospital in Germany. The identification of Gram-negative bacteria by MALDI-TOF MS was significantly better using the Sepsityper kit compared with a separator gel tube-based method (99 and 68 % correct identification, respectively). For Gram-positive bacteria, only 73 % were correctly identified by MALDI-TOF with the Sepsityper kit and 59 % with the separator gel tube assay. A major problem of both methods was the poor identification of Gram-positive grape-like clustered cocci. As differentiation of Staphylococcus aureus from coagulase-negative staphylococci is of clinical importance, a PCR was additionally established that was capable of identifying S. aureus directly from positive blood cultures, thus closing this diagnostic gap. Another benefit of the PCR approach is the possibility of directly detecting the genes responsible for meticillin resistance in staphylococci and for vancomycin resistance in enterococci, which is of high importance for early adequate treatment. Both of the described methods were finally integrated into a protocol for fast and effective identification of bacteria from positive blood cultures.

Binding of the plant hormone kinetin in the active site of Mistletoe Lectin I from Viscum album

The crystal structure of the ribosome inhibiting protein Mistletoe Lectin I (ML-I) derived from the European mistletoe, Viscum album, in complex with kinetin has been refined at 2.7Å resolution. Suitably large crystals of ML-I were obtained applying the counter diffusion method using the Gel Tube R Crystallization Kit (GT-R) on board the Russian Service Module on the international space station ISS within the GCF mission No. 6, arranged by the Japanese aerospace exploration agency (JAXA). Hexagonal bi-pyramidal crystals were grown during three months under microgravity. Before data collection the crystals were soaked in a saturated solution of kinetin and diffraction data to 2.7Å were collected using synchrotron radiation and cryogenic techniques. The atomic model was refined and revealed a single kinetin molecule in the ribosome inactivation site of ML-I. The complex demonstrates the feasibility of mistletoe to bind plant hormones out of the host regulation system as part of a self protection mechanism.

Comparability of two different polyacrylamide gel electrophoresis methods for the classification of LDL pattern type

BackgroundThe measurement of small dense low-density lipoprotein (sdLDL) particles is relevant when assessing cardiovascular risk. However, there is as yet no referenced method for the determination of LDL subfractions or a standardized comparison of the methods currently available.Therefore, the aim of this study was to compare the pattern of LDL particles measured by polyacrylamide tube gel electrophoresis (PTGE) and polyacrylamide gradient gel electrophoresis (PGGE) and to correlate the results with triglyceride concentration. Materials and methodsSerum samples were collected from 177 patients. Lipid profile and LDL particle size were assessed using PTGE and PGGE. ResultsPearson correlation and kappa index revealed a very good agreement between the methods. There was 81.3% concordance for classification of sdLDL particles and 97.2% concordance for classification of large LDL when PTGE and PGGE were compared. LDL size correlated with triglyceride in subjects with triglyceride levels >116mg/dl, pointing to a high CAD risk, as reflected by their higher prevalence of pattern B. ConclusionsPTGE correlates favourably and is in very good agreement with PGGE. The determination of LDL particle size may be an appropriate analytical procedure to estimate CAD risk in patients with high triglyceride levels.

Variation in phlebotomy techniques in emergency medicine and the incidence of haemolysed samples

Phlebotomy is a potential cause of preanalytical errors. We have observed phlebotomy in routine practice in a busy Emergency Department, to see how current practice compares with optimal blood sampling. Phlebotomy episodes were audited and compared with standard procedures. A computer-based search of the number of haemolysed samples from Emergency Medicine and hospital inpatients was reviewed. Four different ways of taking blood were observed: cannulation and a syringe (38%), cannula with evacuated tube and adaptor (42%), syringe and needle into vein (14%) and evacuated tube system used conventionally (6%). Where a syringe was used, two methods of transfer into the sample tube were observed; needle kept on with cap piercing (77%) and needle and evacuated cap both removed (23%). On 20 out of 50 phlebotomy episodes (40%), the potassium-EDTA tube was filled prior to the biochemistry serum gel tube. A search of the laboratory computer records for ward-based phlebotomy found 30 of 1034 samples were haemolysed (2.9%). In the 50 phlebotomy episodes in the Majors area of the Emergency Department, 24% produced a haemolysed sample (P < 0.0001). For samples taken from all areas of Emergency Medicine over a seven-day period, 52 of 485 were haemolysed (10.7%; P < 0.0001). This study has shown that phlebotomy techniques in the Emergency Department deviate from standard practice significantly. This may well be a reason for the much higher frequency of haemolysed samples and with the wrong order of collection the possibility of potassium-EDTA-contaminated samples.

Agreement of Two Different Laboratory Methods Used to Measure Electrolytes

Aim:The aim of our study was to do an agreement analysis of two different laboratory methods used to measure electrolytes i.e., between the ISE based Beckman Coulter Synchron CX9 PRO Biochemistry analyzer and RAL's Ion3 Flame Photometer (Técnica para el Laboratorio, Barcelona, Spain), in serum samples.Materials and Methods:This cross sectional study was done over a period of three months from September’09 through December’09 on routine biochemistry samples. A total of 6492 samples were received for routine biochemistry analysis from those 630 blood samples were randomly processed for this study. Two ml of sample was taken in a plain gel tube (LABTECH Disposables, Ahmedabad, India), centrifuged and further processed using both systems within one hour of the sampling to obtain the Na and K concentrations in the samples. The bias and variability of differences in measured values were analyzed according to Bland and Altman method.Results:Flame photometry method has drawbacks such as low throughput, requires manual operation, is a time consuming procedure. Ion selective electrodes technique is a more universal method for the high throughput determination of electrolytes in physiological samples; Beckman Coulter Synchron CX9 PRO is an example of such a system. The mean difference between the two methods (standard minus test) and 95% limits of agreement for sodium in serum was -7.8±17.3 (-42.2 to 26.6) and in urine was -22±41 (-104 to 60). Similarly, the mean difference between the two methods for potassium values in serum was found to be -0.25±0.75 (-1.75 to 1.25) and in urine was -5.3±38.9 (-83.1 to 72.5). With 95% confidence interval, the value of sodium and potassium as determined by both the methods lie between the upper and lower limit showing 95% limits of agreement.Conclusion:Good degree of agreement was seen on comparing the two methods for measuring the electrolytes; the use of Synchron CX9 in place of Flame photometer for electrolyte analysis in serum and urine is justified or use the two interchangeably.

Determination of four acids in the air of workplace by gas chromatography

Four kinds of acids (acetic acid, propionic acid, acrylic acid and methylacrylic acid) in the air in a workplace were quantitatively determined by gas chromatography synchronously. Four acids in the air were adsorbed by silica gel tube sampling and solvent desorption using acetone, then analyzed by GC with FFAP capillary column. To acetic acid, propionic acid, acrylic acid and methylacrylic acid, the linear regression equations were respectively y = -4.3+1.46x (r = 0.999), y = 0.4+2.37x (r = 0.999), y = 10.4+1.73x (r = 0.999) and y = -2.3+3.21x (r = 0.999). The detection limits were respectively 3.4 microg/mL, 2.1 microg/mL, 2.9 microg/mL and 1.6 microg/mL. The average desorption efficiencies were respectively 92.2%-92.8%, 94.1%-97.4%, 94.8%-95.4% and 94.1%-98.3%. The relative standard deviations were 1.1%-4.0%, 1.2%-7.8%, 0.9%-4.0% and 1.6%-4.8%. The method is suitable to determine four kinds of acids in the air in a workplace.

A modified coaxial electrospinning for preparing fibers from a high concentration polymer solution

A new process technology modified from conventional coaxial electrospinning process has been developed to prepare polymer fibers from a high concentration solution. This process involves a pure solvent concentrically surrounding polymer fluid in the spinneret. The concentric spinneret was constructed simply by inserting a metal needle through a high elastic silica gel tube. Two syringe pumps were used to drive the core polymer solution and the sheath solvent. Using polyvinylpyrrolidone (PVP) as the polymer model, which normally has an electrospinnable concentration of 10% w/v in ethanol, it was possible to electrospin 35% w/v of PVP in the same solvent, when pure N, N-dimethylacetamide (DMAc) was used as sheath fluid. The resultant fibers have a smooth surface morphology and good structural uniformity. The diameter of the fibers was 2.0±0.25 µm when the DMAc-to-polymer-solution flow rate ratio was set as 0.1. The process technology reported here opens a new window to tune the polymer fibers obtained by the electrospinning, and is useful for improving productivity of the electrospinning process.

Smaller Mean LDL Particle Size and Higher Proportion of Small Dense LDL in Korean Type 2 Diabetic Patients

BackgroundSmall dense low density lipoprotein (sdLDL) has recently emerged as an important risk factor of coronary heart disease.MethodsThe mean LDL particle size was measured in 203 patients with type 2 diabetes mellitus (T2DM) and 212 matched subjects without diabetes using polyacrylamide tube gel electrophoresis. Major vascular complications were defined as stroke, angiographically-documented coronary artery disease or a myocardial infarction. Peripheral vascular stenosis, carotid artery stenosis (≥50% in diameter) or carotid artery plaque were considered minor vascular complications. Overall vascular complications included both major and minor vascular complications.ResultsDiabetic patients had significantly smaller mean-LDL particle size (26.32 nm vs. 26.49 nm) and a higher percentage of sdLDL to total LDL compared to those of subjects without diabetes (21.39% vs. 6.34%). The independent predictors of sdLDL in this study were serum triglyceride level and body mass index (odds ratio [OR], 1.020 with P<0.001 and OR 1.152 with P<0.027, respectively). However, no significant correlations were found between sdLDL and major vascular complications (P=0.342), minor vascular complications (P=0.573) or overall vascular complications (P=0.262) in diabetic subjects.ConclusionDiabetic patients had a smaller mean-LDL particle size and higher proportion of sdLDL compared to those of subjects without diabetes. Obese diabetic patients with hypertriglyceridemia have an increased risk for atherogenic small dense LDL. However, we could not verify an association between LDL particle size and vascular complications in this study.

High-density collagen gel tubes as a matrix for primary human bladder smooth muscle cells

Tissue-engineered grafts for the urinary tract are being investigated for the potential treatment of several urologic diseases. These grafts, predominantly tubular-shaped, usually require in vitro culture prior to implantation to allow cell engraftment on initially cell-free scaffolds. We have developed a method to produce tubular-shaped collagen scaffolds based on plastic compression. Our approach produces a ready cell-seeded graft that does not need further in vitro culture prior to implantation. The tubular collagen scaffolds were in particular investigated for their structural, mechanical and biological properties. The resulting construct showed an especially high collagen density, and was characterized by favorable mechanical properties assessed by axial extension and radial dilation. Young modulus in particular was greater than non-compressed collagen tubes. Seeding densities affected proliferation rate of primary human bladder smooth muscle cells. An optimal seeding density of 10 6 cells per construct resulted in a 25-fold increase in Alamar blue-based fluorescence after 2 wk in culture. These high-density collagen gel tubes, ready seeded with smooth muscle cells could be further seeded with urothelial cells, drastically shortening the production time of graft for urinary tract regeneration.

Differential proteome analysis of Mycobacterium avium subsp. paratuberculosis grown in vitro and isolated from cases of clinical Johne's disease

Bovine Johne's disease (paratuberculosis), caused by Mycobacterium avium subspecies paratuberculosis, poses a significant economic problem to the beef and dairy industry worldwide. Despite its relevance, however, pathogenesis of Johne's disease is still only partially resolved. Since mycobacterial membrane proteins expressed during infection are likely to play an important role in pathogenesis, membrane-enriched fractions, namely mucosa-derived membranes (MDM) and culture-derived membranes (CDM), of M. avium subsp. paratuberculosis from three cows with clinical paratuberculosis were investigated. An initial analysis by 2D difference gel electrophoresis (2D DIGE) and MALDI-TOF-MS analysis revealed four differentially expressed proteins with only one predicted membrane protein. Due to this limited outcome, membrane preparations were subjected to a tube-gel trypsin digestion and investigated by using nanoflow-liquid-chromatography-coupled tandem MS. Based on this approach a total of 212 proteins were detected in MDM including 32 proteins of bovine origin; 275 proteins were detected in CDM; 59 % of MDM and CDM proteins were predicted to be membrane-associated. A total of 130 of the proteins were detected in both MDM and CDM and 48 predicted membrane proteins were detected in MDM from at least two cows. Four of these proteins were not detected in CDM, implying differential expression in the host. All membrane-associated proteins, especially the four identified as being differentially expressed, might be relevant targets for further analyses into the pathogenesis of bovine paratuberculosis.

Tube gel isotachophoresis: A method for quantitative isolation of nucleic acids from diluted solutions

The technique of isotachophoresis is intended for separation of molecules having different electrophoretic mobilities in a nonhomogeneous electric field. Since the mobility of nucleic acids in water solutions is uniform and does not depend on their size (because of a uniform distribution of negatively charged phosphate groups along the molecule), isotachophoresis will concentrate rather than separate them in the mobile borderline zone between the rapid (Cl −) and the slow (β-alanine −) anions. This idea served as the basis for elaboration of a novel method for isolation of nucleic acids from diluted solutions. Advantages of the method include quantitative yield (regardless of molecule size), high degree of concentration, and the ability to visually monitor the process. The method may find applications in nucleic acid isolation from highly degraded forensic and clinical samples, from bodily fluids in particular, and thereby promote development of this important direction of diagnostics.

Immune‐mediated pancytopenia induced by oxaliplatin: a case report

Drug-induced immune pancytopenia is considered an uncommon disorder. A 76-year-old woman with metastatic gastric adenocarcinoma received 15 cycles of FOLFOX-6 (oxaliplatin/folinic acid/fluorouracil) with a complete response. Upon disease progression, she was restarted on FOLFOX; during the seventh cycle of treatment, 1 hour after completing her oxaliplatin infusion, she presented oral bleeding, petechiae and generalized hematomas. Her platelet (PLT) count decreased from 164 x 10(9)/L to less than 5 x 10(9)/L within a 3-hour period and her white blood cells (WBCs) decreased from 5 x 10(9) to 1.5 x 10(9)/L. One day later she presented a decrease in hemoglobin level (from 11.4 to 10 g/dL, reaching 8.9 g/dL after 5 days). The patient's PLT and lymphocyte count started to recover after 3 days of immunosuppressive treatment. PLT, red blood cell (RBC), and WBC antibody detection tests were performed in the presence and absence of oxaliplatin. PLT-associated antibodies were evaluated by monoclonal antibody immobilization of PLT antigen assay and flow cytometry; WBC antibodies were tested by flow cytometry; and RBC antibodies were evaluated by gel and indirect antiglobulin test tube testing drug-treated RBCs and untreated RBCs in the presence of drug. Positive reactions were obtained only in the presence of the drug (1 mg/mL) for all tests performed (PLTs, RBCs, and WBCs). Our case convincingly demonstrates that oxaliplatin led to the production of drug-dependent PLT, RBC, and WBC antibodies inducing pancytopenia in the patient. The oxaliplatin was discontinued and patient's hematologic values recovered to normal levels.

Simultaneous determination of phoxim and its photo-transformation metabolite residues in eggs using liquid chromatography coupled with electrospray ionization tandem mass spectrometry

The principal objective of this study was to develop an appropriate, sensitive, and selective method for the simultaneous quantitative determination of phoxim and its photo-transformation product, O, O-diethyl α-cyanobenzylideneamino-thiophosphonate (DCTP) in both chicken and quail eggs. Eggs (1 g) were blended with anhydrous magnesium sulfate (1 g) for sample pretreatment and extracted with acetonitrile. The extracts were then further purified with SPE silica gel tubes deactivated with trimethylamine. Residues were analyzed via a reversed phase-liquid chromatography–tandem mass spectrometry (RP-LC–MS/MS) in positive-ion electrospray ionization (ESI) mode. Tebufenozide was utilized as an internal standard for the quantification of phoxim and its metabolite residues. The identification and quantification of analytes were based on ion transitions monitored by multiple reaction monitoring (MRM). LC–MS/MS analysis was performed from 0.02 to 1 mg kg −1 and correlation coefficients ( r 2 ) ranging from 0.998 to 0.999 were obtained for both analytes in blank egg extracts. The relative standard deviations (RSDs) of intra- and inter-day variations ranged from 2.1% to 6.7% and from 2.8% to 6.4% for phoxim and DCTP in chicken and quail eggs. At all levels of fortification (0.02, 0.05, and 0.125 mg kg −1), the recoveries fell within a range of 81.3% to 93.6% for phoxim and 83.3% to 90.1% for DCTP. The matrix effect was <2%, due to the partial dilution of the sample. Decision limits (CC α) and detection capabilities (CC β) were in the range of 0.0005–0.0044 and 0.0054–0.0224 mg kg −1, respectively. The method was evaluated further by analyzing real samples purchased from markets. All chicken and quail egg samples were free from residues of the target compounds.

Candidate Urinary Biomarker Discovery in Ureteropelvic Junction Obstruction: A Proteomic Approach

Ureteropelvic junction obstruction may either worsen and require surgery, improve or remain stable. It may take upward of 3 years for the natural history to unfold. Urinary proteome analysis using capillary electrophoresis mass spectrometry has been shown to differentiate between normal infants and those with ureteropelvic junction obstruction. We sought to confirm these findings using liquid chromatography/nano-spray mass spectrometry to examine the urinary proteome in patients with unilateral grade IV ureteropelvic junction obstruction compared to age matched healthy infants. Urine specimens were obtained from 21 healthy infants with normal maternal/fetal ultrasound and 25 infants with grade IV unilateral ureteropelvic junction obstruction. Specimens were prepared using standard methods and subjected to liquid chromatography/tandem mass spectrometry analysis. Normalized data were annotated using the IPA(R) knowledge platform. There were 31 proteins significantly different in their level of abundance at 1 to 6 months, and 18 at 7 to 12 months compared to age matched controls. These proteins clustered into major functional networks. All of the biomarkers previously reported in clinical studies of ureteropelvic junction obstruction were observed with the notable exception of transforming growth factor-beta1. These results confirm the presence of significant differences in the urinary proteome in unilateral ureteropelvic junction obstruction compared to age matched normal individuals. This study adds new information about levels of abundance of specific proteins and peptides in ureteropelvic junction obstruction, which may allow for better classification of disease subgroups and help to establish improved indications for the early selection of surgical candidates based on urinary protein biomarkers.

Estimation of the low-density lipoprotein (LDL) subclass phenotype using a direct, automated assay of small dense LDL-cholesterol without sample pretreatment

A new method (sLDL-EX "SEIKEN") is commercially available for the direct quantification of small dense LDL-cholesterol (sd-LDL) on automated chemistry analyzers, without manual sample pretreatment. We evaluated the performance of this direct assay to estimate the small dense LDL subclass phenotype ("non-A"), defined by polyacrylamide gel tube electrophoresis. Fasting serum samples from 189 healthy subjects (age 18-75y, 96 females) were collected. The direct sd-LDL assay (from Randox Laboratories) was applied on a Roche Modular P analyzer. The Quantimetrix Lipoprint(TM) LDL System was used to define LDL subclass phenotypes (A and non-A). ROC curve analysis was performed for sd-LDL and other lipids and apolipoproteins (apo) with respect to phenotype non-A. sd-LDL concentrations (40.4+/-18.6mg/dl) in the total group correlated (P<0.0001) with apoB (r=0.831), apoB/A-I ratio (r=0.757), non-HDL-cholesterol (r=0.821), triglycerides (r=0.439), and LDL-cholesterol (r=0.641). Higher sd-LDL concentrations (P<0.0001) were measured in subjects with LDL phenotype non-A (53.6+/-17.0mg/dl, n=92) than in those with phenotype A (27.9+/-8.9mg/dl, n=97). In logistic regression analysis, sd-LDL and apoA-I were independently associated with LDL subclass phenotype non-A. Highest areas under ROC curves were obtained for sd-LDL (0.943), triglycerides (0.833), triglyceride/HDL-cholesterol (0.838) and apoB/A-I ratio (0.826) to predict phenotype non-A. The sd-LDL cut-off point for optimal sensitivity (87.9%) and specificity (92.8%) was >38.5mg/dl. The direct, homogeneous sd-LDL method is easily applicable on an automated chemistry analyzer and shows acceptable performance to estimate the electrophoretic LDL subclass phenotype.

Lipoprotein Subclass Patterns in Women with Polycystic Ovary Syndrome (PCOS) Compared with Equally Insulin-Resistant Women without PCOS

Women with polycystic ovary syndrome (PCOS) are more insulin resistant and display an atherogenic lipid profile compared with normal women of similar body mass index (BMI). Insulin resistance (IR) at least partially underlies the dyslipidemia of PCOS, but it is unclear whether PCOS status per se confers additional risk. Using a case-control design, we compared plasma lipids and lipoprotein subclasses (using polyacrylamide gel tube electrophoresis) in 70 women with PCOS (National Institutes of Health criteria) and 70 normal women pair matched for age, BMI, and IR (homeostasis model assessment-IR, quantitative insulin sensitivity check index, and the Avignon Index). Subjects were identified as having a (less atherogenic) type A pattern consisting predominantly of large low-density lipoprotein (LDL) subfractions or a (more atherogenic) non-A pattern consisting predominantly of small-dense LDL subfractions. Total, high-density lipoprotein, or LDL cholesterol, or triacylglycerol did not differ between the groups, but very low-density lipoprotein levels (P<0.05) were greater in women with PCOS, whereas a non-A LDL profile was seen in 12.9% compared with 2.9% of controls (P<0.05, chi2). Multiple regression analysis revealed homeostasis model assessment-IR and waist circumference to be independent predictors of very low-density lipoprotein together explaining 40.2% of the overall variance. Logistic regression revealed PCOS status to be the only independent determinant of a non-A LDL pattern (odds ratio 5.48 (95% confidence interval 1.082-27.77; P<0.05). Compared with women matched for BMI and IR, women with PCOS have potentially important differences in lipid profile with greater very low-density lipoprotein levels and increased rates of a more atherogenic non-A LDL pattern.

Stability of Ribavirin Concentrations Depending on the Type of Blood Collection Tube and Preanalytical Conditions

Ribavirin pharmacokinetic and exposure effect trials based on either plasma or serum concentrations have yielded diverging results. This study aimed to compare ribavirin concentrations in serum and plasma and to investigate the influence of blood collection and preanalytical conditions on ribavirin concentration stability. Blood samples from patients with hepatitis virus C and receiving ribavirin were collected in plain (dry) tubes, in tubes containing ethylenediaminetetra-acetic acid or lithium-heparinate, in Type II Serum Separating Tubes with clot activator, or Type II lithium heparinate Plasma Separating Tubes. Different time and temperature conditions were tested before and after blood centrifugation. Ribavirin was determined using liquid chromatography-dual mass spectroscopy. Multiple-way analysis of variance was used for statistical analyses. Ribavirin concentrations showed a higher interlaboratory variability in serum than in plasma. Results were fairly stable over 2 hours in whole blood collected in dry or ethylenediaminetetra-acetic acid tubes and very stable up to 24 hours in serum or plasma kept in gel-containing tubes after immediate centrifugation. When Plasma Separating II gel tubes were kept at +4 degrees C or at ambient temperature for up to 24 hours before centrifugation, ribavirin concentrations decreased by 1% to 8% and 12% to 18%, respectively. These results suggest that blood samples should be collected in gel-containing tubes and centrifuged immediately, after which the tubes can be kept at ambient temperature for the next 24 hours. In case of clinical constraints, Plasma Separating II gel tubes can be kept at +4 degrees C for a maximum of 2 hours before centrifugation with limited impact on the measured concentrations.

High Density Collagen Tubes for Tissue Engineering of Ureteral and Urethral Structures

Purpose Ureteral and urethral structures need to be replaced in several congenital and acquired diseases. Tissue engineered structures might be a solution for replacing diseased or missing tubular structures of the urinary tract. Collagen, the most abundant protein in mammals, gives structure, consistency and resistance to soft tissues and might act as adequate scaffold to engineer such tissue constructs. Material and Methods We designed a novel method to obtain a cell-seeded tubular scaffold, based on collagen gel submitted to a process of plastic compression. We specifically investigated their mechanical properties, and their aptitude for human bladder smooth muscle cell growth was evaluated by histology and electron microscopy. Results The resulting construct has a particularly high collagen density and is characterized by very promising mechanical properties regarding burst pressure and water tightness, which makes it an attractive candidate for tissue engineering of ureteral and urethral structures. Seeding density of 106 smooth muscle cells per 300ml gel gives a more than 25-fold increase of the cell population within the tubes after two weeks in culture. The histology of the three-dimensional smooth muscle cell growth within the tubular matrix is demonstrated and electron microscopy analysis of the construct discussed. The results of such tubes, further seeded with human urothelial cells and cultured in a flow bioreactor system, will be discussed. Conclusions The plastic compressed collagen gel tubes are easy-to-produce, readily cell-seeded matrices. The reported results clearly set plastic compressed collagen gel tubes as suitable scaffolds for tissue engineering of tubular structures of the human urinary tract. Ureteral and urethral structures need to be replaced in several congenital and acquired diseases. Tissue engineered structures might be a solution for replacing diseased or missing tubular structures of the urinary tract. Collagen, the most abundant protein in mammals, gives structure, consistency and resistance to soft tissues and might act as adequate scaffold to engineer such tissue constructs. We designed a novel method to obtain a cell-seeded tubular scaffold, based on collagen gel submitted to a process of plastic compression. We specifically investigated their mechanical properties, and their aptitude for human bladder smooth muscle cell growth was evaluated by histology and electron microscopy. The resulting construct has a particularly high collagen density and is characterized by very promising mechanical properties regarding burst pressure and water tightness, which makes it an attractive candidate for tissue engineering of ureteral and urethral structures. Seeding density of 106 smooth muscle cells per 300ml gel gives a more than 25-fold increase of the cell population within the tubes after two weeks in culture. The histology of the three-dimensional smooth muscle cell growth within the tubular matrix is demonstrated and electron microscopy analysis of the construct discussed. The results of such tubes, further seeded with human urothelial cells and cultured in a flow bioreactor system, will be discussed. The plastic compressed collagen gel tubes are easy-to-produce, readily cell-seeded matrices. The reported results clearly set plastic compressed collagen gel tubes as suitable scaffolds for tissue engineering of tubular structures of the human urinary tract.

Degradation of volatile organic compounds in a non-thermal plasma air purifier

The degradation of volatile organic compounds in a commercially available non-thermal plasma based air purifying system was investigated. Several studies exist that interrogate the degradation of VOCs in closed air systems using a non-thermal plasma combined with a heterogeneous catalyst. For the first time, however, our study was performed under realistic conditions (normal indoor air, 297.5 K and 12.5 g m −3 water content) on an open system, in the absence of an auxiliary catalyst, and using standard operating air flow rates (up to 320 L min −1). Cyclohexene, benzene, toluene, ethylbenzene and the xylene isomers were nebulized and guided through the plasma air purifier. The degradation products were trapped by activated charcoal tubes or silica gel tubes, and analyzed using gas chromatography mass spectrometry. Degradation efficiencies of 11 ± 1.6% for cyclohexene, <2% for benzene, 11 ± 2.4% for toluene, 3 ± 1% for ethylbenzene, 1 ± 1% for σ-xylene, and 3 ± 0.4% for m-/ρ-xylene were found. A fairly wide range of degradation products could be identified. On both trapping media, various oxidized species such as alcohols, aldehydes, ketones and one epoxide were observed. The formation of adipaldehyde from nebulized cyclohexene clearly indicates an ozonolysis reaction. Other degradation products observed suggests reactions with OH radicals. We propose that mostly ozone and OH radicals are responsible for the degradation of organic molecules in the plasma air purifier.