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PubMed1976

The influence of Seitz filtration on the activity of hydatid fluid antigen.

Filtration of hydatid fluid through Seitz EK filter pads results in an initial retention of a part of sensitizing proteins on the filter disc. Filtration through membrane filters allows the passage of most of the proteins of the fluid and may be considered as a more satisfactory procedure for the preparation of antigen for Casoni skin tests. Membrane filtrates are likewise reactive in indirect haemagglutination tests.

Animals↗
PubMed2004

Final decontamination of the filtrates obtained after interaction of two ligand-containing Cu2+ and Zn2+ electroplating solutions.

A cheap and simple way to decontaminate two ligand-containing rinsing waters of metal finishing has been previously suggested. Both the copper diphosphate-containing rinsing wastewater and acidic zinc ammonium-containing rinsing wastewater may be decontaminated by mixing them which results in precipitation of solid solutions of copper-zinc-potassium-ammonium diphosphates. This way of decontamination requires no expensive reagents since only a small amount of H2SO4, is needed for pH adjustment. 80-99.5 % of environmentally dangerous substances, viz. zinc, copper and diphosphate, are removed from the mixture. However, Cu2+ and Zn2+ amounts in filtrates significantly exceed the discharge consent level (DCL). Besides, high concentrations of undesirable diphosphate and ammonium ions, which cause the eutrophication of natural water reservoirs, are present in the filtrates. There are relatively small concentrations of heavy metals: Cu2+ (approximately 0.4 mM dm-3) and Zn2+ (approximately 1 mM dm-3), and relatively large quantities of ligands: P2O7(4-) (approximately 20 mM dm-3) and NH4+/NH3 (approximately 500 mM dm-3) in these filtrates. Our investigation has shown, that decontamination may be easily achieved in industry by using cheap materials or industrial by-products: lime, MgO, phosphogypsum, extractive phosphoric acid and spent steel etching solution. Using lime, Cu2+ and Zn2+ ions may be removed below their DCL. After that, diphosphate ion concentration may be reduced approximately 1000 fold by addition of spent steel etching solution or continuous mixing with phosphogypsum. The amount of NH4+/NH3 may be reduced 20 to 30 fold, the concentration of soluble phosphates -- 5 to 40 fold and both c Cu2+ and c Zn2+ -- lower than their DCL by precipitating barely soluble fine crystalline MgNH4PO46H2O (struvite).

Copper↗
PubMed2004

Evaluation of natural coagulants for direct filtration.

In the present study surjana (Moringa oleifera) seed, maize (Zea mays) and chitosan were used in direct filtration of Bilaoli lake water and evaluated for their efficiency in removing turbidity and microorganisms from water. The experiments with these natural coagulants gave filtered water turbidity less than or almost equal to 1NTU and thereby met the turbidity criteria for drinking water as per WHO guidelines. Bilaoli lake water had low ionic strength and low turbidity which represents one of the most difficult raw waters to treat, but natural coagulants in direct filtration achieved good filtrate quality. The head loss development across the filter bed with chitosan was more than that of alum, while with maize it was comparable to that of alum. With M. oleifera seeds the head loss was much less in comparison to alum. The average most probable number (MPN) reductions obtained with M. oleifera seeds, maize and chitosan were 97.35%, 95.4% and 87.1% respectively, whereas, with alum it was only 7.7%.

Chitin↗
PubMed2006

The efficiency of an air filtration system in the hospital ward.

A study was conducted to ascertain the efficiency and effectiveness of an air filtration system (Electromedia Model 100C, Clean Air UK, UK) in the hospital ward. The sampling was conducted using a portable Surface Air Sampler (Cherwell Laboratories, Bicester, UK) in conjunction with settle plates. Samples were taken two days before and two days following activation of the filtration system and results compared. A clear, demonstrable, statistically significant reduction in microbial organisms following the activation of the filtration systems is evident (81% settle plates; 24% Surface Air Sampler). This study has implications for the improved health and welfare of patients and healthcare workers who may benefit through the implementation of such a system.

Air Microbiology↗
PubMed2000

A study of the nonsteady-state filtration process in a fibrous material in conditions of real dust loading.

The study concerns ways to describe filtration efficiency and gas flow resistance while particles are deposited in fibrous respiratory protective filters under conditions characteristic for their use. The performance of fibrous filter materials of varied structure and electrostatic properties was studied, using polydisperse coarse-grained aerosols and submicron aerosols of sodium chloride. Evidence was found that changes in airflow resistance depended to a large extent on air humidity and the concentration of the aerosol. A relationship was also found between the electrostatic properties of filter media and their decreasing efficiency with time. A numerical model was developed to simulate the phenomenon of nonsteady-state filtration for 2 mechanisms of deposition, which permitted assessment of the filtration characteristics of filter media of any design and in any conditions.

Aerosols↗
PubMedDate not supplied

Test methods for evaluating the filtration and particulate emission characteristics of vacuum cleaners.

The overall filtration efficiency of a vacuum cleaner traditionally has been tested by placing the vacuum cleaner in a test chamber and measuring aerosol concentrations at the chamber inlet and outlet. The chamber test method was refined and validated in this study. However, this chamber test method shows an overall filtration efficiency of close to 100% for most of the industrial vacuum cleaners and for most of the newly developed household vacuum cleaners of midprice range or higher because all these vacuum cleaners have a high-efficiency particulate air (HEPA) or other highly efficient filter installed at the exhaust. A new test method was therefore developed through which the vacuum cleaner was probed in various internal locations so that the collection efficiency of the individual components could be determined. For example, the aerosol concentration upstream of the final HEPA filter can thus be measured, which permits one to estimate the life expectancy of this expensive component. The probed testing method is particularly suitable for field evaluations of vacuum cleaners because it uses compact, battery-operated optical particle size spectrometers with internal data storage. Both chamber and probed tests gave the same results for the aerosol filtration efficiency. The probed testing method, however, also gives information on the performance of the individual components in a vacuum cleaner. It also can be used to determine the dust pickup efficiency and the degree of reaerosolization of particles collected in the vacuum cleaner.

Air Pollution, Indoor↗
PubMed2004

Basic study on anaerobic biological filtration using a floating filter media.

An experiment of anaerobic filtration using a floating media was carried out in this study. In the present system, a bench-scale column of 50 mm in diameter and of 1500 mm in height and a floating media consisting of S-shaped polystyrene pieces were employed. The purpose of this study was to collect the basic data of anaerobic biological filtration using a floating media. Under the laboratory conditions, it was found that the start-up of an anaerobic biological filter took about half month at 20 degrees C and a lower BOD loading was favorable for this start-up. The BOD removal efficiency over 60% could be achieved at a BOD volumetric loading of the filter bed under 6 kg/m3/d. An effluent BOD concentration became high when the flow rate was high, especially with circulation of treated water, which afforded a large effect on an effluent BOD concentration. As for the mechanism of BOD removal by anaerobic filtration, it was evident that long retention time worked in favor for organic acid generation, and the circulation of treated water promoted decomposition of organic acids.

Bacteria, Anaerobic↗
PubMed2005

Alkaline hydrothermal conversion of fly ash filtrates into zeolites 2: utilization in wastewater treatment.

Filtrates were collected using a codisposal reaction wherein fly ash was reacted with acid mine drainage. These codisposal filtrates were then analyzed by X-ray Fluorescence spectrometry for quantitative determination of the SiO2 and Al2O3 content. Alkaline hydrothermal zeolite synthesis was then applied to the filtrates to convert the fly ash material into zeolites. The zeolites formed under the experimental conditions were faujasite, sodalite, and zeolite A. The use of the fly ash-derived zeolites and a commercial zeolite was explored in wastewater decontamination experiments as it was applied to acid mine drainage in different dosages. The concentrations of Ni, Zn, Cd, As, and Pb metal ions in the treated wastewater were investigated. The results of the treatment of the acid mine drainage with the prepared fly ash zeolites showed that the concentrations of Ni, Zn, Cd, and Hg were decreased as the zeolite dosages of the fly ash zeolite (FAZ1) increased.

Carbon↗
PubMed2004

Serum cystatin C for assessment of glomerular filtration rate in hypertensive disorders of pregnancy.

BACKGROUND: Assessment of renal function is important in the evaluation of the pregnant hypertensive patient. The aim of this study was to evaluate the diagnostic utility of cystatin C as a marker of glomerular filtration rate in hypertensive disorders of pregnancy and to correlate this with serum creatinine and creatinine clearance. METHODS: For our study, 198 women who presented with hypertension during pregnancy were recruited at the antenatal clinic of King Edward VIII Hospital in Durban, South Africa, a tertiary referral centre. Exclusion criteria included women with eclampsia, urinary tract infection and chronic renal disease. Routine dipstick urinalysis (Bayer) was performed by midwives to classify patients suffering from the different forms of hypertensive disorders of pregnancy and venous blood samples for determination of serum cystatin C and serum creatinine were collected. The 24-hour urine creatinine clearance was used as the "gold standard" for evaluation of glomerular filtration rate due to concerns of radiation exposure to pregnant women with the use of radio nucleotide markers. RESULTS: The results of testing the 198 women, 72 of whom had preeclampsia, were analyzed. Serum cystatin C showed a significant correlation with creatinine clearance at the 0.01 level (2-tailed) with an r-value of -0.311. Serum creatinine showed a significant correlation with creatinine clearance at the 0.01 level (2-tailed) with an r-value of -0.486. CONCLUSION: Serum cystatin C seems to reflect glomerular filtration rate reliably in hypertensive pregnant women and avoids the inaccuracy associated with the 24-hour urine collection, which is time consuming and subject to improper collection.

Adult↗
PubMed1969

The renal handling of hemoglobin. I. Glomerular filtration.

The glomerular filtration of hemoglobin (alpha(2)beta(2)) was studied under conditions in which its dissociation into alphabeta dimers was experimentally altered. Rats receiving hemoglobin treated with the sulfhydryl reagent bis(N-maleimidomethyl) ether (BME) showed a much lower renal excretion and prolonged plasma survival as compared with animals injected with untreated hemoglobin. Plasma disappearance was also prolonged in dogs receiving BME hemoglobin. Gel filtration data indicated that under physiological conditions, BME hemoglobin had impaired subunit dissociation. In addition, BME hemoglobin showed a very high oxygen affinity and a decreased rate of auto-oxidation. Glomerular filtration was enhanced under conditions which favor the dissociation of hemoglobin into dimers. Cat hemoglobin, which forms subunits much more extensively than canine hemoglobin, was excreted more readily by the rat kidney. The renal uptake of (59)Fe hemoglobin injected intra-arterially into rabbits varied inversely with the concentration of the injected dose.

Animals↗
PubMed2006

A fit method for the determination of inherent filtration with diagnostic x-ray units.

A method for the determination of total inherent filtration for clinical x-ray units using attenuation curves was devised. A model for the calculation of x-ray spectra is used to calculate kerma values which are then adjusted to the experimental data in minimizing the sum of the squared relative differences in kerma using a modified simplex fit process. The model considers tube voltage, voltage ripple, anode angle and additional filters. Fit parameters are the thickness of an additional inherent Al filter and a general normalization factor. Nineteen sets of measurements including attenuation data for three tube voltages and five Al-filter settings each were obtained. Relative differences of experimental and calculated kerma using the data for the additional filter thickness are within a range of -7.6% to 6.4%. Quality curves, i.e. the relationship of additional filtration to HVL, are often used to determine filtration but the results show that standard quality curves do not reflect the variety of conditions encountered in practice. To relate the thickness of the additional filter to the condition of the anode surface, the data fits were also made using tungsten as the filter material. These fits gave an identical fit quality compared to aluminium with a tungsten filter thickness of 2.12-8.21 microm which is within the range of the additional absorbing layers determined for rough anodes.

Algorithms↗
PubMed2004

Detection of Cryptosporidium parvum oocysts in experimentally contaminated lettuce using filtration, immunomagnetic separation, light microscopy, and PCR.

Recovery of Cryptosporidium parvum oocysts in a fecal suspension that experimentally contaminated onto lettuce leaves was investigated. Material recovered from the lettuce samples by washing in detergent solutions were concentrated by filtration using the Envirochek Sampling Capsule. Oocysts were concentrated by immunomagnetic separation (IMS) and detected by microscopy following modified Ziehl-Neelsen (MZN) staining. Cryptosporidal DNA was detected using a nested-PCR assay for amplification of a fragment of the Cryptosporidium oocyst wall protein (COWP) gene, which was applied to DNA extracted from both filtrates, and material recovered from MZN stained smears on glass slides after microscopy. No Cryptosporidium were detected by microscopy or by PCR of un-inoculated lettuce leaves. After IMS, means of 0-6.5% of the total numbers of oocysts inoculated were recovered and detected by microscopy. Detection by PCR was less sensitive than microscopy. There was a strong association between successful PCR amplification, the numbers of oocysts detected by microscopy and the numbers of oocysts in the inoculum. This study confirms that C. parvum oocysts can be recovered from contaminated lettuce using filtration and IMS, and detected by microscopy and PCR. However, further developments are required to improve recovery of this parasite.

Animals↗
PubMed1979

Airway closure and fluid filtration in the lung.

We have investigated the effect of airway closure on fluid balance in the isolated, perfused rabbit lung in which the alveolar, pleural and vascular pressures could be regulated independently. The rate of filtration into the interstitial space was monitored by continuous weighing. A reduction in pleural pressure of 0.5 kPa with open airways increased fluid filtration by 0.11 g min-1. Reduction in pleural pressure of 0.5 kPa with the main airways closed reduced the alveolar pressure by 0.4 kPa and increased fluid filtration by 0.86 g minp1. We concluded that the pleural pressure is transmitted poorly to the alveolar interstitial space in the normal lung with open airways. However, airway closure allows the pleural pressure to be transmitted almost completely to this interstitium, with interstitial oedema as a possible consequence.

Airway Obstruction↗
PubMed1988

Effects of inhalation anaesthetics on filtration of venous gas emboli by the pulmonary vasculature.

Venous gas emboli are prevented from reaching the systemic circulation by filtration in the pulmonary vasculature. This filtration can be overwhelmed by exceeding certain critical rates of venous air infusion. To characterize further these filtration phenomena, the effects of pentobarbitone, isoflurane and halothane anaesthesia on the incidence of spillover of venous bubbles into the arteries were studied in groups of nine dogs. Venous air was infused at rates of 0.25, 0.30, and 0.35 ml kg-1 min-1. Spillover of venous bubbles into the arteries was detected with a Doppler ultrasonic probe located over the suprarenal aorta. At the lowest venous air dose (0.25 ml kg-1 min-1), no bubbles were detected in the systemic circulation in the pentobarbitone- or halothane-anaesthetized dogs, while arterial bubbles were detected in two with isoflurane anaesthesia. At 0.30 ml kg-1 min-1 air, one, four and two dogs had arterial bubbles detected with pentobarbitone, halothane or isoflurane anaesthesia, respectively, while at 0.35 ml kg-1 min-1 spillover of bubbles occurred in four, five and three, respectively. The spillover of venous bubbles into the arteries was dose-related for the pentobarbitone- and halothane-anaesthetized dogs.

Anesthesia, Inhalation↗
PubMed1978

Filtration and immunoprecipitation in the elimination of DNA polymerase activity associated with bacterial contamination of sera positive for hepatitis B e antigen and its corresponding antibody.

Samples of serum inoculated with Escherichia coli and serum that became contaminated with bacteria after exposure to a laboratory atmosphere demonstrated elevated DNA polymerase activity. The levels of activity were well within the range of values found in hepatitis B e antigen (HBeAg)-positive samples. The bacterial polymerase activity was markedly reduced by a single passage of serum samples through a 0.22-micron Millipore filter prior to analysis. Repeated filtration did not result in a substantial further decrease in polymerase activity. In sera that were heavily contamined with E. coli, however, filtration was not successful in reducing bacteria-associated polymerase activity to a base-line uncontaminated level. In such instances double antibody immunoprecipitation proved effective in elimination of bacterial activity. When bacterial contamination of serum samples is a possibility, specimens should be subjected to either Millipore filtration or immunoprecipitation prior to analysis, particularly when correlation of DNA polymerase activity with HBeAg and its corresponding antibody is attempted.

Antibodies, Viral↗
PubMed1996

Internal filtration--advantage in haemodialysis?

Internal filtration is defined as the total water flux across the membrane within the closed blood and dialysate compartment of a dialyser. The aim of our study was to increase convection by increasing the amount of internal filtration and to study the effect on elimination of high and low molecular weight uraemic toxins during regular haemodialysis. Three high-flux polysulfone dialysers with identical type of membrane (Fresenius Sps600) and same number of fibres but with different inner diameters () and therefore different surface areas [] (175 microns [0.55 m2], 200 microns [0.65 m2] and 250 microns [0.79 m2]) were tested in routine haemodialysis sessions (10 patients). At a blood flow of 250 ml/min and a dialysate flow of 500 ml/min hydrostatic pressures at dialysate-in/outlet (PD(in), PD(out) and blood-in/outlet (PBin, PBout), mTMP, clearances (Cl) and mass balances of creatinine, urea, phosphate and beta-2-microglobulin (beta 2-M) at 30 and 180 min were measured at net ultrafiltration rate of 0 ml/min. Clearances of all three dialysers were matched for small toxins (urea: 180 +/- 4.83 ml/min). The 175 microns diameter dialyser achieved a significantly better removal of beta 2M (Cl beta 2-M 57.4 +/- 9.43 ml/min) than the two other filters (200 microns: 29.9 +/- 8.4 ml/min; 250 microns: 11.1 +/- 6.79 ml/min) although the surface area of the 175 microns filter was smallest. Hydrostatic pressure analysis revealed that at the same median transmembrane pressures (mTMP) internal filtration increased with decreasing inner fibre diameter. Longitudinal flow resistance and thereby local transmembrane pressure difference increased with narrowing the inner fibre diameter.

Adult↗
PubMed1997

Decreasing glomerular filtration rate--an indicator of more advanced diabetic glomerulopathy in the early course of microalbuminuria in IDDM adolescents?

BACKGROUND: Overt diabetic nephropathy is accompanied by a progressive decline in glomerular filtration rate (GFR). In this study we have investigated if a reduction of GFR already during the transition from normo- to microalbuminuria is associated with glomerular structural changes. METHODS: Seventeen adolescents (11 girls/6 boys) with 10.5 (3.3) (mean, SD) years of IDDM were studied. GFR was previously measured in the normoalbuminuric stage 2-5 years prior to the renal biopsy, and measured again at the time for the biopsy, after in mean 1.8 years of microalbuminuria (15-200 micrograms/min). HbAlc and albumin excretion rate were measured 3 or 4 times yearly and blood pressure 1-4 times yearly between the GFR examinations. The associations between the yearly rate of fall in GFR and basement membrane (BM) thickness, mesangial and matrix volume fractions, matrix star volume, mean capillary diameter (CAPD), area of filtration surface (peripheral BM) per glomerulus, total capillary length per glomerulus, the ratio of peripheral BM to capillary surface, glomerular volume, and interstitial volume fraction were analysed. RESULTS: BM thickness and matrix star volume were increased in patients with, as compared to those without, a decline in GFR > or = 6 ml/min per year (P < 0.005 respectively). Patients with previous glomerular hyperfiltration (> or = 135 ml/min per 1.73 m2) showed the steepest decline in GFR; 11 ml/min per year versus -0.8 ml/min per year in previously normofiltering patients, P < 0.001. The rate of fall in GFR was positively correlated to BM thickness (P < 0.001), interstitial volume fraction (P = 0.02) and CAPD (P = 0.04), mean HbAlc (P = 0.01), but not to the change in HbAlc between GFR examinations. CONCLUSION: A decreasing glomerular filtration rate in the early stage of microalbuminuria may be due to more advanced diabetic glomerulopathy than in IDDM patients with stable GFR.

Adolescent↗
PubMed1997

Stabilization of glomerular filtration rate over 2 years in patients with diabetic nephropathy under intensified therapy regimens. Diabetes Treatment and Teaching Programmes Working Group.

OBJECTIVES: We investigated the effect of achieved continuous tight blood pressure control and intensified insulin therapy on the rate of progression of renal failure in patients with overt diabetic nephropathy and already impaired renal function. DESIGN AND SETTING: Prospective, randomized, multicentre, follow-up study. PATIENTS AND INTERVENTIONS: From a screened group of the 66 hypertensive type 1 diabetic patients (IDDM) with overt diabetic nephropathy and reduced glomerular filtration rate who participated in two intensified treatment programmes, 39 patients fulfilled the study inclusion criteria and were enrolled into the 2-year follow-up period. The choice of antihypertensive drugs was based on a randomized allocation to open antihypertensive treatments starting with felodipine, metoprolol, or ramipril. OUTCOME MEASURES: Progression of renal failure was assessed by measurement of glomerular filtration rate (GFR) on insulin clearance every 6 months. MAIN RESULTS: During the study period mean HbA1c was 8.1 +/- 1.6% and the office blood pressure 143 +/- 14/88 +/- 8 mmHg. The change in GFRinulin (mean and 95% CI) was +1.9 (-2.2; +6.1) ml/min/year. GFR improved in 51%, deteriorated in 39%, and remained stable in 10% of the patients. CONCLUSION: This study shows that stabilization of glomerular filtration rate, as assessed by inulin clearance, is possible in patients with overt diabetic nephropathy who reach the goals of intensified antihypertensive treatment even if kidney function is already impaired.

Adult↗