Bird community response to filter strips in Maryland

Filter strips are strips of herbaceous vegetation planted along agricultural field margins adjacent to streams or wetlands and are designed to intercept sediment, nutrients, and agrichemicals. Roughly 16,000 ha of filter strips have been established in Maryland through the United States Department of Agriculture's Conservation Reserve Enhancement Program. Filter strips often represent the only uncultivated herbaceous areas on farmland in Maryland and therefore may be important habitat for early-successional bird species. Most filter strips in Maryland are planted to either native warm-season grasses or cool-season grasses and range in width from 10.7 m to 91.4 m. From 2004 to 2007 we studied the breeding and wintering bird communities in filter strips adjacent to wooded edges and non-buffered field edges and the effect that grass type and width of filter strips had on bird community composition. We used 5 bird community metrics (total bird density, species richness, scrub-shrub bird density, grassland bird density, and total avian conservation value), species-specific densities, nest densities, and nest survival estimates to assess the habitat value of filter strips for birds. Breeding and wintering bird community metrics were greater in filter strips than in non-buffered field edges but did not differ between cool-season and warm-season grass filter strips. Most breeding bird community metrics were negatively related to the percent cover of orchardgrass (Dactylis glomerata) in ≥1 yr. Breeding bird density was greater in narrow (<30 m) compared to wide (>60 m) filter strips. Our results suggest that narrow filter strips adjacent to wooded edges can provide habitat for many bird species but that wide filter strips provide better habitat for grassland birds, particularly obligate grassland species. If bird conservation is an objective, avoid planting orchardgrass in filter strips and reduce or eliminate orchardgrass from filter strips through management practices. © 2011 The Wildlife Society.     

Application of the membrane filter technique to bromodeoxyuridine immunochemistry for exfoliative cytology

The membrane filter technique for smear specimens of tumors in bromodeoxyuridine (BrdU) immunochemistry is described. The staining results of Raji cells processed using the filter technique was compared with that obtained by the conventional cytospin method. Although the BrdU mean labeling index (LI) for in cytospin specimens was almost the same as the LI in membrane filter specimens, filter specimens showed excellent staining and less cell destruction compared with those processed by cytospin. Small amounts of tumor specimens such as squamous cell carcinoma and polymorphous low-grade adenocarcinoma also were processed using the membrane filter appliance. For squamous cell carcinoma, the LI for the filter specimens was 5.36 ± 0.38 and that of the paraffin sections was 5.56 ± 0.38. The membrane filter technique provided relatively undamaged specimens for exfoliative cytology and will be useful for immunohistochemical evaluation of tumor cells and for routine, noninvasive cytological screening.     

Adhesion of Clostridium cellulolyticum spores to filter paper

The adhesion of Clostridium cellulolyticum spores and cells to Whatman No. 1 filter paper was studied. A suspension of vegetative cells in exponential phase from a culture on cellobiose adhered at 60% whereas spores at the same initial concentration were bound to the Whatman filter paper at 90%. Adhesion of vegetative cellulolytic cells occurs on specific cellulosic sites and reveals a sigmoid type II curve. Non-cellulolytic vegetative cells from Clostridium butyricum do not adhere to the cellulose. Spore adhesion is a non-specific process since non-cellulolytic spores from Clostridium butyricum adhered almost in the same range to filter paper than cellulolytic spores.     

Multilayer immobilized-enzyme filter reactors: urease bound to nylon fabric filters.

Urease was bound to commercially available nonwoven nylon fabric filters. Multilayer immobilized-enzyme filter reactors were constructed by packing varying numbers of urease-nylon filters in a column. Owing to the relatively open structure and high mechanical strength of the filter fabric, compaction and pressure drop effects were minimal. The reactors could be operated in a wide range of substrate concentrations and flow rates under conditions where mass-transfer limitations could be neglected. The kinetic behavior of the immobilized-enzyme filter reactors could be described by a linear form of the integrated Michaelis-Menten equation using a model based on the sequential action of the enzyme filters.     

Adsorption of dissolved organic matter to the inorganic filter substrate and its implications for C uptake measurements

Inorganic carbon uptake rates for glass fiber-filtered samples are higher than those for membrane-filtered samples because of adsorption of dissolved organic matter to the filter substrate. Experimentally derived values for adsorption onto filters were as follows (relative units): GF/F filter, 1, quartz filter, 1.1, GF/C filter, 0.6; GN-6 Gelman filter, 0.1; Nuclepore and Poretics filter, 0.0; Anodisc filter, 0.4 to 1.9.     

A filter assay for binding of labeled ligands to membrane-bound receptors

A filter assay was developed for the specific binding of labeled ligands to the acetylcholine receptor in an unpurified suspension of membrane fragments from Torpedo californica. Binding to the filter membrane and the standard deviation of replicates were studied, and it was possible to reduce relative standard deviation to about 3% by accounting for the variable weight of the particles dispensed, stopping the loss of particles to the filter apparatus, regulating the transmembrane pressure during filtration, controlling the time the filter remains subject to suction after all the liquid has passed through the filter, and correcting for variable counting efficiency. A method for dispensing equal aliquots of suspended particulates is also described.     

Flagellar adhesion ofCrithidia fasciculata to Millipore filters

Summary Millipore filters composed of mixed cellulose esters have been used to investigate the adhesion of flagella ofCrithidia fasciculata to a non-living substrate. After 4 days on the surface of a culture of the flagellate, one side of the filter was covered with a monolayer of cells. In most cases the flagella penetrated the pores of the filter and at one or more points along their length presumed sites of adhesion were marked by the presence of hemidesmosomes, characterized by a thickened inner leaflet of the flagellar membrane and the presence of large numbers of fine filaments. If the interstitial space of the filter was sufficiently large, the hemidesmosomes occurred at the apex of an evagination of the flagellar membrane. These evaginations are believed to arise by movement of the flagellum relative to the point of adhesion. The addition of distilled water causes de-adhesion of the flagellum and its withdrawal from the filter. The hypothesis that cells adhere to one another and to non-living substrates by different mechanisms is discussed in the light of the results obtained here.     

Adsorption of Dissolved Organic Matter to the Inorganic Filter Substrate and Its Implications for 14C Uptake Measurements

Inorganic carbon uptake rates for glass fiber-filtered samples are higher than those for membrane-filtered samples because of adsorption of dissolved organic matter to the filter substrate. Experimentally derived values for adsorption onto filters were as follows (relative units): GF/F filter, 1, quartz filter, 1.1, GF/C filter, 0.6; GN-6 Gelman filter, 0.1; Nuclepore and Poretics filter, 0.0; Anodisc filter, 0.4 to 1.9.     

Baseline susceptibility of western corn rootworm (Coleoptera: Chrysomelidae) to clothianidin

Abstract:  Western corn rootworm, Diabrotica virgifera virgifera LeConte, neonate susceptibility to clothianidin, a contact and systemic neonicotinoid insecticide, was determined from both laboratory and field-collected populations. Neonates were exposed to filter paper treated with increasing clothianidin concentrations and mortality was evaluated after 24 h. Additionally, two populations were exposed to an artificial diet which was surface treated with clothianidin. Although larvae were five- to six-fold more sensitive to treated diet, results with treated filter paper were more reliable in terms of control mortality and required much less manipulation of rootworm larvae. Therefore, initial baseline comparisons were conducted using the filter paper assays. The variation among populations exposed to treated filter paper was generally low, 4.4-fold among laboratory populations tested; however, there was a 14.5-fold difference in susceptibility among all populations tested. In general, clothianidin was very toxic to rootworm neonates, with LC₅₀ values ranging from 1.5 to 21.9 ng/cm². These results indicate the practicability and sensitivity of the paper filter disc assay to establish baseline susceptibility levels, which is an essential first step in resistance management. A baseline response provides a reference for tracking shifts in susceptibility following commercialization of a control agent so that early changes in susceptibility can be detected.     

A simple and rapid method to measure cholesterol binding to P450s and other proteins

Cholesterol plays an important role in cellular function and membrane compartmentalization and is involved in the interaction with more than a dozen of different proteins. Using three cholesterol-metabolizing cytochrome P450s (P450s 7A1, 46A1, and 11A1), we have developed a rapid and simple assay for measurements of nanomolar to micromolar cholesterol affinities. In this assay, the P450 is incubated with a fixed amount of radiolabeled cholesterol and varying concentrations of cold cholesterol followed by separation of free and protein-bound cholesterol via filtration through a membrane. Free cholesterol is found in the flow-through fraction, whereas P450 binds to the membrane. The radioactivity of the membranes is then measured, and a saturation curve is generated after correction for nonspecific binding of cholesterol to the filter. The validity of the filter assay was confirmed by spectral assay, a traditional method to evaluate the interaction of the P450 enzymes with their substrates. Two types of membranes, one binding positively charged proteins and another binding negatively charged proteins, were identified. These membranes were also found to hold proteins through hydrophobic interactions. Thus, the cholesterol binding properties of a wide variety of proteins could be characterized using this filter assay.     

A fast bilateral filter with application to artefact reduction

Elastography in medical ultrasound is an imaging technique that displays information about tissue stiffness. However, elastography suffers from artefact noise that may come from two dominant sources: decorrelation error and amplitude modulation error. In order to reduce artefact and improve the quality of ultrasonic elastography, a fast bilateral filter is proposed in this study based on local histogram. The presented filter is derived from a conventional bilateral filter, and a local histogram is introduced to speed up the filter. The proposed algorithm can reduce artefact noise and, at the same time, maintain the tissue structure. Both simulation and phantom testing show that the proposed method can improve the quality of ultrasonic elastography in terms of tissue elastographic signal-to-noise ratio and elastographic contrast-to-noise ratio values.     

Alcian Blue and Colloidal Iron Staining Methods Adapted to Filter Paper Electrophoresis

Filter paper moistened with solutions used in electro-chromatography was spotted with 0.5-1.0μl of solutions of mucopolysaccharides and allowed to air dry. Substances tested with respect to their staining reaction were as follows: (a) From commercial sources: hyaluronic acid, heparin, chondroitin sulfate, ovomucoid and gastric mucin, (b) From natural sources: blood serum, saliva, tears, vitreous filtrate and aqueous humor. Alcian blue was found to be a good general stain for mucopolysaccharides and for locating such material on filter paper, especially when more specific means were used subsequently for identifying the kind of mucopolysaccharide present. Staining by colloidal iron of materials on filter paper was similar to that by the periodic acid-Schiff reaction. However, heparin and chondroitin sulfate were not stained by iron when on filter paper but were stained when placed on glass slides.     

Adapting virus filtration to enable intensified and continuous monoclonal antibody processing

Ongoing efforts in the biopharmaceutical industry to enhance productivity and reduce manufacturing costs include development of intensified, linked, and/or continuous processes. One approach to improve productivity and process economics of the polishing step (i.e., anion exchange chromatography) is to preconcentrate the product intermediate using a single-pass tangential flow filtration step before loading on the resin. This intensification of the polishing step consequently leads to changes in product intermediate concentration for subsequent virus filtration operations, potentially impacting filter performance and methods for evaluating viral clearance. The filtrate flux performance of a virus filtration operation was evaluated with monoclonal antibody (mAb) solutions of varying concentrations. These data were used to evaluate the effect on filter sizing for a hypothetical mAb perfusion process. The optimum mAb concentration to minimize the area of the virus filter was a function of the filtration step duration and reflected the competing effects of increasing concentration and decreasing volumetric flux on the membrane productivity. mAb solutions at high and low concentrations were used to evaluate viral clearance with extended filtration times (e.g., 24–72 h) simulating continuous processing conditions. Modifications to more traditional filtration viral clearance study methods were required to avoid experimental artifacts associated with the extended filtration time. No virus passage through the filter was observed under these conditions, similar to previous results for batch processes. These data demonstrate the feasibility of obtaining effective virus removal even when mAb concentration and filtrations times are increased by up to an order of magnitude from current common practices.     

Hybrid filtering to rescue stable oscillations from noise-induced chaos in continuous cultures of budding yeast

In large-scale fermentations with oscillating microbial cultures, noise is commonly present in the feed stream(s). As this can destabilize the oscillations and even generate chaotic behavior, noise filters are employed. Here three types of filters were compared by applying them to a noise-affected continuous culture of Saccharomyces cerevisiae with chaotic oscillations. The aim was to restore the original noise-free stable oscillations. An extended Kalman filter was found to be the least efficient, a neural filter was better and a combined hybrid filter was the best. In addition, better filtering of noise was achieved in the dilution rate than in the oxygen mass transfer coefficient. These results suggest the use of hybrid filters with the dilution rate as the manipulated variable for bioreactor control.     

Factors affecting transfer frequency of pAM beta 1 from Streptococcus faecalis to Lactobacillus plantarum.

Conjugal transfer of streptococcal plasmid pAM beta 1 to Lactobacillus plantarum by a filter mating method was examined under various conditions. The transfer frequency depended greatly on the type, pore size, and side (front or back) of the membrane filter. The passage of sterilized water through the membrane under reduced pressure after donor and recipient cells were trapped on it increased the transfer frequency about 10-fold.     

Factors influencing the ability of Listeria monocytogenes to pass through a membrane filter by active infiltration

Listeria monocytogenes infiltrated the reticulate structure of a membrane filter and passed through a filter with pore sizes of 0.45 microm and 0.2 microm in 6 to 24 h and 5 to 6 days, respectively. Flagellar motility and expansive pressure generated by the growing bacterial population were indicated as the driving forces of infiltration.     

Search filters for finding prognostic and diagnostic prediction studies in Medline to enhance systematic reviews

Background

The interest in prognostic reviews is increasing, but to properly review existing evidence an accurate search filer for finding prediction research is needed. The aim of this paper was to validate and update two previously introduced search filters for finding prediction research in Medline: the Ingui filter and the Haynes Broad filter.

Methodology/Principal Findings

Based on a hand search of 6 general journals in 2008 we constructed two sets of papers. Set 1 consisted of prediction research papers (n = 71), and set 2 consisted of the remaining papers (n = 1133). Both search filters were validated in two ways, using diagnostic accuracy measures as performance measures. First, we compared studies in set 1 (reference) with studies retrieved by the search strategies as applied in Medline. Second, we compared studies from 4 published systematic reviews (reference) with studies retrieved by the search filter as applied in Medline. Next – using word frequency methods – we constructed an additional search string for finding prediction research. Both search filters were good in identifying clinical prediction models: sensitivity ranged from 0.94 to 1.0 using our hand search as reference, and 0.78 to 0.89 using the systematic reviews as reference. This latter performance measure even increased to around 0.95 (range 0.90 to 0.97) when either search filter was combined with the additional string that we developed. Retrieval rate of explorative prediction research was poor, both using our hand search or our systematic review as reference, and even combined with our additional search string: sensitivity ranged from 0.44 to 0.85.

Conclusions/Significance

Explorative prediction research is difficult to find in Medline, using any of the currently available search filters. Yet, application of either the Ingui filter or the Haynes broad filter results in a very low number missed clinical prediction model studies.     

Identifying sites of attachment of UV filters to proteins in older human lenses

Recent results indicate that covalent modification of proteins by tryptophan-derived UV filters may explain the age-dependent coloration of human lenses, and play a role in age-related cataract. The sites of attachment of the UV filters to the lens crystallins, however, have not been determined. This study utilized a database of predicted masses of UV filter-modified tryptic peptides to target sites of UV filter attachment. Proteins were isolated from old normal lenses and digested with trypsin at pH 6, in order to preserve the integrity of the sites of modification. Peptides were separated by high-performance liquid chromatography and characterized by mass spectrometry. Major colored and fluorescent peaks in the digest were found to correspond to cysteine-containing peptides in which the sulfur atom of the sidechain was linked to the major UV filter compound, 3-hydroxykynurenine glucoside. Three of the peptides originated from gammaS-crystallin and one from betaB1-crystallin. These results show that a predicted mass database can be used to facilitate the identification of sites of UV filter modification in human lens crystallins. Furthermore, this work represents the first evidence that UV filters bind to specific residues on lens proteins in vivo, and suggests that sulfhydryl groups may be important sites for the attachment of UV filters.     

Binding of prolactin and monoclonal antibody to prolactin receptors immobilized on a nitrocellulose membrane filter

Mammary prolaction (PRL) receptors in 3-[(3-cholamidopropyl)dimethylammonio]propanesulfonic acid (Chaps) extract were immobilized on a nitrocellulose (NC) filter, and a binding assay using the filter-bound receptors was carried out in the absence of detergent. PRL binding to the receptors was dependent on the quantity of the receptors and the PRL added to the filters. The filter-bound receptors retained the specificity of binding to peptide hormones. Scatchard analysis showed that the number of PRL receptors and the dissociation constant for PRL binding are essentially unchanged after immobilization on a NC filter, indicating that the PRL binding site does not participate in the binding to the NC filter and is equally available for PRL binding. The monoclonal antibody (MAb) against the PRL receptor was able to bind specifically to the Chaps-solubilized and filter-bound PRL receptors, as shown by curvilinear Scatchard plots. Immobilization on NC filters permits direct detection and characterization of the soluble PRL receptor using labeled PRL or MAb.     

Evaluation of Recovery Methods to Detect Coliforms in Water

Various recovery methods used to detect coliforms in water were evaluated by applying the membrane filter chamber technique. The membrane filter chambers, containing pure-culture suspensions of Escherichia coli or natural suspensions of raw sewage, were immersed in the stream environment. Samples were withdrawn from the chamber at regular time intervals and enumerated by several detection methods. In general, multiple-tube fermentation techniques gave better recovery than plating or membrane filtration procedures. The least efficient method of recovery resulted when using membrane filtration procedures, especially as the exposure period of the organisms to the stream environment increased. A 2-h enrichment on a rich, nonselective medium before exposure to selective media improved the recovery of fecal coliforms with membrane filtration techniques. Substantially enhanced recoveries of E. coli from pure-culture suspensions and of fecal coliforms from raw-sewage suspensions were observed when compared with recoveries obtained by direct primary exposure to selective media. Such an enrichment period appears to provide a nontoxic environment for the gradual adjustment and repair of injured cells.