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PubMed2006

Crumb rubber filtration: a potential technology for ballast water treatment.

The removal of turbidity, particles, phytoplankton and zooplankton in water by crumb rubber filtration was investigated. A substantial reduction was achieved. Of the three variables, filter depth, media size and filtration rate, media size had the most significant influence. Smaller media size favored higher removal efficiency of all targeted matter. There was no apparent relationship between removal efficiency and filter depth. Higher filtration rate resulted in lower removal efficiency and higher head loss. Compared with conventional granular media filters, crumb rubber filters required less backwash, and developed lower head loss. Consequently crumb rubber filters could be run for a longer time or allow a higher filtration rate. The results also indicate that the crumb rubber filtration alone did not achieve the target removal of invasive species. However, crumb rubber filtration could potentially be used as a primary treatment technology to enhance the efficiency of a secondary treatment process (e.g., disinfection).

Animals↗
PubMed2004

Control of the arteriolar myogenic response by transvascular fluid filtration.

Mechanisms of the myogenic response have not been completely established. We hypothesized that transvascular fluid filtration from plasma across smooth muscle cells (SMC) and into the surrounding interstitium helps regulate arteriolar myogenic tone. Arteriolar diameters in the rat mesentery were monitored before and following vascular occlusion with a glass micropipette. Arteriolar occlusion not only gave an increase in hydrostatic pressure that initiated myogenic constriction upstream of the pipette, but also allowed measurement of fluid filtration rate by monitoring the movement of vascular red blood cells. A statistically significant correlation (P < 0.001) existed between basal myogenic tone and fluid filtration. Additionally, the myogenic response was attenuated by 47% +/- 7% (N = 10) when an osmotic solution of albumin or albumin plus Ficoll was infused into the bloodstream to decrease fluid filtration by 53% +/- 3%. Moreover, the same inhibition of myogenic tone was found in isolated, cannulated rat soleus muscle arterioles when filtration was osmotically attenuated by intravascular dextran. Taken together, these results are consistent with the hypothesis that shear stress on arteriolar smooth muscle, induced by transvascular fluid filtration, is a contributing factor that helps control myogenic tone.

Animals↗
PubMed2006

Scaling filtration time initial dependencies of wastewater sludges.

The filtration time, t(f), during constant pressure dead-end filtration testing of wastewater sludge is dependant on the initial height, h(0), and the initial solids concentration, phi(0). The theoretical dependencies of these initial conditions are explored: t(f) varies with h(0)(2) and cphi(0)(2), where c is a material dependant parameter that is also dependant on phi(0) and the applied pressure. Empirical values for c relative to a given phi(0) are determined from phenomenological filtration theory to give a qualitative scaling method to compare the filtration behaviour of highly compressible materials under differing initial conditions. The method is validated using filtration testing of municipal wastewater sludge. This new scaling method is applied to the filtration results of a range of different wastewater sludges, additives and treatments to illustrate its application for plant comparisons, polyelectrolyte comparisons, dose optimisation of polyelectrolyte and ferric chloride and combinations thereof, and the effects of two physicochemical treatments.

Filtration↗
PubMed1991

Filtration of spermatozoa through L4 membrane: a new method.

OBJECTIVE: To explore the possibility of using the L4 membrane filtration device for processing of spermatozoa for intrauterine insemination and other assisted reproductive techniques. DESIGN, SETTING, PATIENTS: Semen samples from 15 patients attending an infertility clinic of a tertiary referral institution and from seven fertile donors were used for the study. MAIN OUTCOME MEASURES: The effect of L4 membrane filtration was studied on the following semen parameters: sperm motility, velocity, percentage of normal and abnormal sperm forms, and percentage and concentration of round cells in semen. RESULTS: The statistical analysis of data from both the subfertile patient population and the normal fertile donor group showed similar improvement in semen quality after L4 membrane filtration. Therefore, the results for these two groups were combined for statistical purposes. Our findings demonstrate a significant increase in normal sperm forms and a decrease in abnormal forms after filtration of specimens through the L4 membrane. In all subjects, the mean sperm motility increased from 47% to 77% (P less than 0.0001); velocity increased from 30 to 48 microns/seconds (P less than 0.0001); normal sperm forms increased from 53% to 84% (P less than 0.0001); abnormal forms decreased from 28% to 10% (head defects) (P less than 0.0001); neck defects from 3.5% to 1% (P less than 0.0006); tail defects from 8% to 3.5% (P less than 0.005); and undifferentiated round cells decreased from 6% to less than 1% (P less than 0.002) after filtration. The concentration of round cells counted by the Makler chamber (Sefi Medical, Haifa, Israel) decreased significantly from 6 x 10(6)/mL to 0.2 x 10(6)/mL (P less than 0.0003). Similarly, white blood cell counts measured by the Endtz test also decreased from 3.4 x 10(6)/mL to less than 0.1 x 10(6) (P less than 0.043). CONCLUSION: We conclude that the filtration of the semen specimens through L4 membrane results in a significant improvement in semen parameters and should be considered as an adjunct in sperm processing.

Cell Count↗
PubMed1992

Preparation of human frozen-thawed seminal specimens using the SpermPrep filtration method: improvements over the conventional swim-up method.

OBJECTIVE: To examine the qualitative and quantitative characteristics of frozen-thawed spermatozoa recovered through the SpermPrep (ZBL, Inc., Lexington, KY) filtration method or the swim-up technique for the purpose of intrauterine insemination (IUI) or other techniques for assisted reproduction. DESIGN, SETTING, PATIENTS: Thirty pairs of frozen specimens purchased from three commercial semen suppliers were used in this study. Each pair consisted of two aliquots from the same semen specimen. MAIN OUTCOME MEASURES: Spermatozoa recovered via the SpermPrep filtration and swim-up processes were evaluated for sperm numbers recovered, sperm motility, grade of sperm motility, percentage of morphologically normal spermatozoa, the response of spermatozoa to a hypo-osmotic environment (hypo-osmotic swelling test), and the amount of debris present. RESULTS: Application of the SpermPrep filtration method resulted in recovery of significantly greater numbers of spermatozoa (P less than 0.01) than were recovered with the swim-up method (31.1 +/- 3.2 x 10(6) versus 10.2 +/- 1.8 x 10(6) spermatozoa, respectively). This represents a mean recovery of approximately one half (49%) of all spermatozoa applied to the filter, whereas for the swim-up method, it was only 15%. The overall quality of recovered spermatozoa was virtually identical between the two methods (P greater than 0.05). The percent motile sperm improved by a mean of 18% to 20%, the grade of motility improved by a mean of 0.4 points (scale 0 to 4), the percent of morphologically normal spermatozoa increased by a mean of approximately 10%, the percent of spermatozoa reactive to a hypo-osmotic medium test increased by a mean of approximately 9%, and the debris score decreased by a mean of 0.2 to 0.3 points (scale 0 to 4). Most importantly, the mean total number of motile, morphologically normal spermatozoa after filtration through the SpermPrep column was 20.2 +/- 1.1 x 10(6), representing a mean recovery of 73% of the normal spermatozoa originally applied to the column. This was 316% greater than the yield obtained with the swim-up method (6.4 +/- 0.8 x 10(6)), which was significantly greater (P less than 0.01) than that recovered via the swim-up method. Also, the time required to harvest sperm through SpermPrep filtration was 20 to 25 minutes versus 80 minutes required for the swim-up method (P less than 0.05). CONCLUSION: Considering that the effectiveness of frozen-thawed semen is already limited when compared with fresh semen, SpermPrep filtration is the method of choice over the swim-up technique of sperm selection because the former provides significantly greater numbers of high quality sperm. It should be considered as an adjunct in semen preparation for IUI or other forms of assisted reproduction.

Evaluation Studies as Topic↗
PubMed2003

Impact of portable air filtration units on exposure of haematology-oncology patients to airborne Aspergillus fumigatus spores under field conditions.

We undertook a one-year study to investigate the impact of the NSA model 7100A/B portable air filtration unit on exposure of haematology-oncology patients to airborne Aspergillus fumigatus spores under field conditions. Weekly measurements for airborne A. fumigatus were conducted in indoor and outdoor air, and surveillance for invasive aspergillosis was based on a combination of ward liaison, targeted chart review and consultation with the medical staff. The mean indoor A. fumigatus counts (8.1 cfu/m3; range, <0.8 to 42 cfu/m3) reflected the fungal load of outdoor air (9.4 cfu/m3; range, <0.8 to 50 cfu/m3), and were reduced by only about one third in rooms with portable air filtration units (5.3 cfu/m3; range, <0.8 to 41 cfu/m3). During the study period, a total of five cases (incidence density, 0.8 per 1000 patient-days) of invasive aspergillosis (one proven case, four suspected cases; case fatality rate 40%) were recorded. None of these five patients was allocated to a room with portable air filtration unit, however, the difference between incidence densities in rooms with and without portable air filtration units was non-significant (Fisher's exact test, P=0.33). Due to the noise level and thermal discomfort, patient compliance with the air filtration units was poor. We conclude that under field conditions this air filtration unit cannot be recommended for prevention of invasive aspergillosis in neutropenic haematology-oncology patients.

Adult↗
PubMed1990

Utility of radioisotopic filtration markers in chronic renal insufficiency: simultaneous comparison of 125I-iothalamate, 169Yb-DTPA, 99mTc-DTPA, and inulin. The Modification of Diet in Renal Disease Study.

Assessment of glomerular filtration rate (GFR) with inulin is cumbersome and time-consuming. Radioisotopic filtration markers have been studied as filtration markers because they can be used without continuous intravenous (IV) infusion and because analysis is relatively simple. Although the clearances of 99mTc-diethylenetriamine-pentaacetic acid (DTPA), 169Yb-DTPA, and 125I-iothalamate have each been compared with inulin, rarely has the comparability of radioisotopic filtration markers been directly evaluated in the same subject. To this purpose, we determined the renal clearance of inulin administered by continuous infusion and the above radioisotopic filtration markers administered as bolus injections, simultaneously in four subjects with normal renal function and 16 subjects with renal insufficiency. Subjects were studied twice in order to assess within-study and between-study variability. Unlabeled iothalamate was infused during the second half of each study to assess its effect on clearances. We found that renal clearance of 125I-iothalamate and 169Yb-DTPA significantly exceeded clearance of inulin in patients with renal insufficiency, but only by several mL.min-1.1.73m-2. Overestimation of inulin clearance by radioisotopic filtration markers was found in all normal subjects. No differences between markers were found in the coefficient of variation of clearances either between periods on a given study day (within-day variability) or between the two study days (between-day variability). The true test variability between days did not correlate with within-test variability. We conclude that the renal clearance of 99mTc-DTPA, 169Yb-DTPA, or 125I-iothalamate administered as a single IV or subcutaneous injection can be used to accurately measure GFR in subjects with renal insufficiency; use of the single injection technique may overestimate GFR in normal subjects.

Creatinine↗
PubMed1999

A fluid filtration and clearing technique to assess microleakage associated with three dentine bonding systems.

OBJECTIVES: The aims of this in vitro study were to (a) measure fluid flow through teeth restored with one of three dentine bonding systems and a resin composite restoration; (b) measure the distribution of a silver tracer through the same teeth, and make a comparison with fluid flow; and (c) investigate the effect of thermocycling on both measurement types. METHODS: Coronal segments of 30 premolars, randomly allocated to three equal groups, were assessed by fluid filtration. Each group was restored with a resin composite restoration in conjunction with Fuji Bond LC (FBLC), Scotchbond Multi-Purpose Plus (SMP+) or Prime&Bond 2.1 (P&B2.1). Fluid filtration rates were measured in the intact crown and then after cavity preparation, conditioning, dentine bonding, restoration and at 2 and 24 h, 1 week and 1 month following restoration. Six specimens from each group were thermocycled at 1 week. After final filtration measurements the specimens were perfused with silver nitrate and cleared before scoring tracer penetration. RESULTS: No significant differences (P > 0.05) in fluid filtration rates were found amongst the different bonding systems or at any restoration stage. Thermocycling was not associated with any significant (P > 0.05) increase in fluid filtration. Final fluid filtration and tracer distribution showed a weak and not statistically significant correlation (P > 0.05). The penetration of silver stain indicated a failure of the restorations to seal the cavity and demonstrated a possible pathway by which in vivo post-operative sensitivity could occur. CONCLUSIONS: Although not statistically significant, conditioning of the cavity increased the dentinal permeability but this effect was variable. Thermocycling had no statistically significant effect on microleakage.

Analysis of Variance↗
PubMed1997

Peripheral blood neutrophil rheology measured by micropore filtration reflects Behçet's disease activity well.

Activated neutrophils take a long time to pass through a narrow lumen like a micropore, and are supposed to play a deteriorating effect on microcirculation. Although the activation of neutrophils has been demonstrated in Behçet's disease, nobody analyzes the clinical activity of the disease by means of the rheological measure of neutrophils activity. Using a micropore (pore diameter 5 microns) filtration technique, we measured the filtration time of peripheral blood neutrophils, as a rheological measure of their activity, in order to determine the clinical activity of Behçet's disease. Twenty-one patients with Behçet's disease and 14 healthy control individuals were enrolled in the study. Symptoms and signs exhibited in the patients led us to distinguish the Behçet's disease into inactive and active cases. The latter were further differentiated into cases with absent symptoms and with present symptoms. Neutrophil filtration times were 11.5 +/- 4.8 s in the active cases with present symptoms, which were significantly (P < 0.05) larger than those (7.4 +/- 1.9 s) in the active cases with absent symptoms. The latter filtration times were further significantly (P < 0.001) larger than values (3.7 +/- 1.3 s) in the inactive cases and also those (4.8 +/- 1.2 s) in control subjects. Furthermore, increases in the filtration time obtained immediately after the exposure of cells to the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP: 10 nM) were significantly (P < 0.01) larger in the active cases with present symptoms than those in the active cases with absent symptoms. The latter were also larger, but not significantly, than those in the inactive cases, and were significantly (P < 0.01) larger than those in control subjects. The present results demonstrate that the micropore filtration method reflects well the rheological activity of neutrophils as well as the clinical status of Behçet's disease. This method is much better than the measurement of O2 production to differentiate between active cases with absent symptoms and inactive patients or even control individuals. Furthermore, it is more sensitive and useful than laboratory data like the CRP value or the number of peripheral blood neutrophils.

Adolescent↗
PubMed1999

The flow rate significantly influences the leukocyte depletion rate during prestorage in-line filtration of platelet concentrates.

BACKGROUND: White cell reduction of blood products minimizes the risks of alloimmunization against HLA-antigens, the transmission of viral diseases and the incidence of platelet transfusion reactions. One modern strategy is leukocyte depletion with an integrated filter system immediately after preparation and prior to storage. STUDY DESIGN AND METHODS: We evaluated the efficiency of a novel in-line filter system Sepacell PLX-5 BPS for leukocyte reduction of platelet concentrates (PC) from pooled buffy-coats. A total of 44 PCs were investigated with regard to different filtration flow rates (25-110 ml/min) and leukocyte depletion and thrombocyte recovery rates were analysed. Furthermore, we studied the influence of filtration on PCs over a storage period of 6 days (n = 12) by investigation of pH, lactate and glucose. Platelet function was determined by means of hypotonic shock response, external shape change and expression of CD62p. RESULTS: The mean leukocyte depletion rate was > log 5. After filtration the mean leukocyte count was 0.12 +/- 0.21 x 10(6). In 60% of the PCs the leukocyte count lay below the detection level of the Nageotte chamber, which is < 0.3 x 10(5). The flow rate correlates significantly with the leukocyte count in the PCs (r = 0.325; p = 0.033) and therefore with the leukocyte depletion rate (r = -0.422; p = 0.01). Flow rates under 40 ml lead to a significantly lower leukocyte contamination. Only in one PC, at a flow rate of 84 ml/min, was the leukocyte threshold of 1 x 10(6) exceeded. We did not find a significant correlation between filtration flow rate and thrombocyte recovery (r = 0.315; p = 0.069). The mean platelet count in the PC was 2.88 +/- 0.47 x 10(11). Compared with the thrombocyte count in the pooled buffy coat, the recovery was 68.6%. We observed a decrease of pH, glucose, external shape change and hypotonic shock response over the storage period while lactate and the expression of CD62p increased. CONCLUSION: The filter system Sepacell PLX-5 BPS proved to be suitable for in-line filtration of platelet concentrates prior to storage. Filtration flow rates of up to 40 ml/min allowed efficient leukocyte depletion without significant loss in the quality of the platelet concentrates and the platelet function in vitro.

Adult↗
PubMed1991

[Multicenter study on the efficacy of leukocyte depletion by filtration of red cells. The Labile Blood Products Group].

To determine the actual efficacy of red cells filtration technique, the "Labile Blood Component Production" french study group, including 21 blood centers, realized a large study on more than 1,400 filtrations and 3,000 controls. 745 units of red cell concentrates (RCC) and 690 units of buffy-coat poor red blood cells (BC PRBC) were filtered through 6 commercialized leukocytes depleting filters: not less than 170 experiments per filter, tested by 3 different blood centers. Pre-filtration controls prove that buffy-coat removal, done manually or with automated equipment, involves a first leukocytes depletion about 63% and an hemoglobin loss equal to 4 g (7%). After filtration, residual leukocytes counts were performed manually in a Nageotte counting chamber. In this study, we evaluated the reliability of this simple method which accurately measures very low leukocytes counts. The variation coefficient was 25% for 2.5 leukocytes/microliter concentration (O.6 x 10(6) per filtered unit). The results, obtained from 1200 evaluated filtrations, confirm that buffy-coat removal obviously improves the filtration performances (residual leukocytes level is lower than 1 x 10(6) per unit for 78% filtered BC PRBC versus 43% filtered RCC). Furthermore, 90% of overall filtered units are containing less than 5 x 10(6) leukocytes.

Cell Separation↗
PubMedDate not supplied

Sterilizing filtration of plasmid DNA: effects of plasmid concentration, molecular weight, and conformation.

Plasmid DNA purification development has been driven by the increased need for large quantities of highly purified, sterile plasmid DNA for clinical studies. Detailed characterization and development of the terminal sterile filtration process step is often limited due to time constraints and the scarcity of sufficient quantities of purified plasmid. However, the large size of the plasmid molecule and variations in conformation can lead to significant yield losses if this process step is not optimized. In this work, the gradual pore-plugging model of flow decay was found to be valid for plasmid DNA by using an ultra scaledown apparatus (1-4 cm(2) filter area). Filtration capacity was found to be insensitive to pressure. Multiple filter types were screened and both source and composition of materials were found to affect filter capacity dramatically. The filter capacity for plasmid was improved by increasing plasmid concentrations as well as by modifying buffer conditions to reduce the apparent size of the plasmid. Filtration capacities varied over a greater than 2 log range when plasmids with sizes ranging from 5.5 to 11 kb and supercoiled plasmid content of 55-95% were explored. Larger plasmids and feeds with lower supercoiled contents led to reduced capacities. These results can be used to define conditions for scale-up of plasmid sterile filtration, as evidenced by processing a 30 g lot using a filtration area of 1,000 cm(2), with a 96% yield, based on filtration capacity data from 4 cm(2) test filters.

Buffers↗
PubMedDate not supplied

Modeling and analysis of the affinity filtration process, including broth feeding, washing, and elution steps.

Affinity filtration is a developing protein purification technique that combines the high selectivity of affinity chromatography and the high processing speed of membrane filtration. In this work a lumped kinetic model was developed to describe the whole affinity filtration process, including broth feeding, contaminant washing, and elution steps. Affinity filtration experiments were conducted to evaluate the model using bovine serum albumin as a model protein and a highly substituted Blue Sepharose as an affinity adsorbent. The model with nonadjustable parameters agreed fairly to the experimental results. Thus, the performance of the affinity filtration in processing a crude broth containing contaminant proteins was analyzed by computer simulations using the lumped model. The simulation results show that there is an optimal protein loading for obtaining the maximum recovery yield of the desired protein with a constant purity at each operating condition. The concentration of a crude broth is beneficial in increasing the recovery yield of the desired protein. Using a constant amount of the affinity adsorbent, the recovery yield can be enhanced by decreasing the solution volume in the stirred tank due to the increase of the adsorbent weight fraction. It was found that the lumped kinetic model was simple and useful in analyzing the whole affinity filtration process.

Adsorption↗
PubMed2004

Transport of Cryptosporidium oocysts in porous media: role of straining and physicochemical filtration.

The transport and filtration behavior of Cryptosporidium parvum oocysts in columns packed with quartz sand was systematically examined under repulsive electrostatic conditions. An increase in solution ionic strength resulted in greater oocyst deposition rates despite theoretical predictions of a significant electrostatic energy barrier to deposition. Relatively high deposition rates obtained with both oocysts and polystyrene latex particles of comparable size at low ionic strength (1 mM) suggest that a physical mechanism may play a key role in oocyst removal. Supporting experiments conducted with latex particles of varying sizes, under very low ionic strength conditions where physicochemical filtration is negligible, clearly indicated that physical straining is an important capture mechanism. The results of this study indicate that irregularity of sand grain shape (verified by SEM imaging) contributes considerably to the straining potential of the porous medium. Hence, both straining and physicochemical filtration are expected to control the removal of C. parvum oocysts in settings typical of riverbank filtration, soil infiltration, and slow sand filtration. Because classic colloid filtration theory does not account for removal by straining, these observations have important implications with respect to predictions of oocyst transport.

Animals↗
PubMed1991

White cell depletion of red cell and pooled random-donor platelet concentrates by filtration and residual lymphocyte subset analysis.

This study comparing the relative white cell (WBC)-depleting efficiency of single and double filtration used two filters and new, sensitive, and reliable methods for performing WBC counts on WBC-depleted blood products. A single filtration of red cell (RBC) concentrates with a cotton-wool filter reduced WBC content by 98.64 percent, but the range of residual WBCs was wide, and many filtered units still contained more than the theoretical immunizing dose of 5 to 10 x 10(6) WBCs. A second filtration, however, always produced RBC units that had less than 5 x 10(6) WBCs. Although the degree of WBC depletion observed after a single filtration of a 6-unit pool of random-donor platelet concentrates was greater with a polyester filter than with the cotton-wool filter (98.92 vs. 98.14% reduction, respectively, when mean prefiltration WBC count was less than 600 x 10(6], in both cases, 25 percent of filtered products still contained greater than 5 x 10(6) WBCs; a second filtration (with the cotton-wool filter), however, produced units that were always below the immunizing dose. All double-filtered platelet concentrates had less than 10(6), and one-half had less than 10(4) residual WBCs. Platelet loss was similar with both filters (+/- 16% loss with one filtration). The effectiveness of the filters in producing products that were WBC-depleted below the immunizing dose was dependent on the prefiltration WBC content (but not on the age of the units), and it may be worthwhile to employ methods to ensure that total prefiltration WBC count of the product is less than 400 x 10(6).(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, CD↗
PubMed1996

Factors influencing white cell removal from red cell concentrates by filtration.

BACKGROUND: The preparation of blood components by hard centrifugation results in red cell concentrates with a small amount of plasma. The influence of various plasma factors, temperature, and storage time on white cell reduction by filtration was studied. STUDY DESIGN AND METHODS: Red cell concentrates were suspended in 100 mL of saline-adenine-glucose-mannitol (SAGMAN) solution or in SAGMAN solution in which 5 or 10 mL had been replaced with an equal amount of fresh plasma, albumin (4%), or heat-inactivated plasma. After overnight storage at 4 degrees C, filtration at a slow flow rate (2 hours) was performed. The effect of temperature was studied by filtration at 4 degrees C and 37 degrees C. To study the influence of storage time, red cell concentrates were stored for 4 to 8 hours or 14 to 20 hours at 4 degrees C and filtered through another model of filter. The number of white cells was counted microscopically or by flow cytometry. RESULTS: When 5 or 10 mL of plasma was added, a significantly smaller number of white cells were found after filtration than were found in the SAGMAN control (the median difference between pairs: 23.6 x 10(6) for 5 mL [p = 0.006] and 14.9 x 10(6) for 10 mL [p = 0.003]). The number of white cells was significantly higher with 10 mL of albumin than with 10 mL of plasma (difference, 15.0 x 10(6); p = 0.006). When heat-inactivated plasma was used, the number of white cells was significantly lower than when fresh plasma was used (difference, 0.3 x 10(6); p = 0.009). Filtration at 37 degrees C resulted in a 64-percent reduction in white cells and that at 4 degrees C led to a 99.7-percent reduction (p = 0.006). When the second filter was used, a slight but significantly lower number of white cells was found in the red cell concentrate stored for 14 to 20 hours than in that stored for 4 to 8 hours (difference, 0.03 x 10(6); p < 0.001). CONCLUSION: The amount of plasma in the red cell concentrate and the storage time and temperature are important factors in the outcome of white cell reduction by filtration. The effect of plasma does not seem to be due to a general influence of protein or to the activity of complement or fibrinogen.

Blood Preservation↗
PubMed2000

Longitudinal monitoring of WBC subsets in packed RBC units after filtration: implications for transfusion transmission of infections.

BACKGROUND: Specific subsets of peripheral blood WBCs are reservoirs for infectious agents, such as CMV and EBV, and can serve as vectors for transfusion transmission of these agents. While filter WBC reduction has been used to prevent transfusion transmission of infections, its effectiveness has not been documented for many infectious agents and in some instances may be difficult to demonstrate in clinical trials. Because the effectiveness of filtration depends on the number of infected WBCs remaining at transfusion, WBC subpopulations in packed RBC units were quantitated after filtration and storage. STUDY DESIGN AND METHODS: Packed RBC units (n = 14) were filtered and stored at 4(o)C for 42 days or were stored without filtration. Serial samples were subjected to flow cytometric immunophenotyping of WBC subsets: neutrophils, monocytes, CD4+ and CD8+ T cells, B cells, and NK cells. RESULTS: Filtration produced a mean reduction in total WBCs of 3.2 log. Monocytes, lymphocytes, and neutrophils were reduced by 4.1, 3.8, and 2.5 log, respectively. Lymphocyte subsets also demonstrated differential reduction with filtration. All WBC subsets showed ongoing loss during storage. CONCLUSIONS: Monocyte and lymphocyte subsets are removed most effectively by prestorage filtration. Postfiltration storage leads to further significant reductions in WBC subsets. The implications of these findings for the mitigation of transfusion transmission of infection are discussed.

Antibodies↗
PubMed2003

Development of floating plastic media filtration system for water treatment and wastewater reuse.

Floating plastic media coupled with sand filtration system was applied for treating surface water and secondary effluent from municipal sewage treatment plant. The system employed floating plastic media for the removal of suspended solids in surface water and precipitated phosphorus from secondary effluent of sewage treatment plant. Sand filtration was then used to remove further the suspended solids. For the purposes of wastewater reuse, a zeolite layer was used instead of sand filter to absorb ammonium nitrogen. Application of system for surface water treatment suggested appropriate filtration rate of 5 m3/m2 h. Polyaluminum chloride was found to be the best coagulant with an appropriate plastic and sand bed depth of 40 cm. The system could produce average effluent turbidity and suspended solids of 0.71 NTU and 0.94 mg/L respectively. Average turbidity and suspended solids removal efficiencies were 96.26% and 95.48% with low headloss development of 40.4 cm at the end of 6 h operation period. When applying 1.50 m. floating plastic media bed for the treatment of synthetic raw water, short and long-term turbidity removal efficiencies were 96.79-97.72% and 81.81-94.61% for raw water containing turbidity of 20 and 40 NTU. It could produce the effluent with turbidity less than 5NTU while having less than 1.0 m. headloss. The system was also applied for the secondary effluent treatment. An optimum filtration rate of 5 m3/m2 h was obtained when using plastic and sand bed depth of 60 and 20cm under direct filtration mode. Average turbidity removal was 60.3% and 59.6% after 6 and 48 h of operation. It was also found that 1 m3/m2 h filtration rate and 50:30 cm of plastic:zeolite bed could be used to achieve both ammonium nitrogen and phosphate removal. Suspended solids, turbidity, BOD5, NH4+, and PO4(3-) removal efficiencies were 91.9, 94.6, 95.4, 97.3, and 99.5% respectively after 24 h. As a result, the effluent from the system had average NH4+ and PO4(3-) of 0.5 mg N/L and 0.02 mg P/L.

Absorption↗