Filtration manifolds

Horizontal pre.s.sure leaf filters. In these filters the leaves may be rectangular leaves which run parallel to the axis and are of varying sizes since they form chords of the shell or they may be circular or square elements parallel to the head of the shell, and aU of the same dimension. The leaves may be supported in the sheU from an independent rack, individuaUy from the shell, or from a filtrate manifold. Horizontal filters are particiilarly suited to diy-cake discharge. 

Vertical pre.s.sure leaf filters. These filters have vertical, paraUel, rec tangular leaves mounted in an upright cylindrical pressure tank. The leaves usually are of such different widths as to aUowthem to conform to the curvature of the tank and to fill it without waste space. The leaves often rest on a filtrate manifold, the connec tion being sealed by an O ring, so that they can be lifted individuaUy from the top of the fil-... 

Transfer the solution to a centrifuge tube and centrifuge down to a loose 5 mL pellet. We recommend a medium speed for 10 min. Decant off excess liquid. (Note Miller and Scholin [6] developed a system using a filter tube and filtration manifold that reduces sample processing time and causes less cell damage than centrifuging.)... 

The filters are mounted in the filtration manifold, vacuum is applied and an aliquot of the first sample is applied to the first filter. Once the sample compartment drains, the filter is washed immediately by the... 

Sterile filtration units, 47-mm size, with filtration manifold... 

Aseptically unwrap four sterile filter funnels and place in filtration manifold. 

Tween 80 in WFI in appropriately sized containers Sterile filtration units, 47-mm size, with filtration manifold Sterile 0.45- am, 47-mm, mixed esters of cellulose (MEG), tortuous path filter membranes... 

Figure 5. Filtrate flow paths. Key 1 and 2, filtrate manifolds ...

RNA preparations from ten control and ten VPA-treated rats were separately combined. Three serially diluted amounts (4, 2, and 1of each total RNA preparation were applied to nylon membranes using a microsample filtration manifold and were hybridized with a radiolabelled cDNA probe. Quantitation of each slot was performed by densitometric scanning of X-ray film. We first carried out preliminary slot-blot hybridization experiment to confirm that each species of mRNA is specifically detected by its cDNA probe. The accuracy of quantitation of mRNA amounts was dso tested. ITie result for SCAD mRNA is shown in Figure 2. The slot blots of SCAD mRNA in the heart were more intensely labeled than those of the liver. Hybridization signals of each slot were comparable to the amount of total RNA applied. There was no hybridization to yeast tRNA at all. The same e qieriments using other cDNA probes (MCAD, LCAD, and IVD) also demonstrated the specificity and accuracy of quantitation (data not shown). 

RNA dot hybridizations were first described by Kafatos et [.( ). They allow rapid detection of transcription from a number of mRNA populations and are particularly useful in the initial characterization of clones derived from differentially expressed genes. Where accurate quantification of transcription is necessary, or many samples have to be handled, filtration manifold systems are available, such as the Millipore (Bedford, MA) MilliBlot system, that use a vacuum source to transfer nucleic acid to filter. 

In operating a pressure leaf filter, the sludge is fed under pressure from the bottom and equally distributed. The clear filtrate from each leaf is collected in a common manifold and carried away. In filters with an external filtrate manifold (refer to the sketch in Figure 12), the filtrate from each leaf is visible through a respective sightglass. This is not possible when the leaves are mounted on a hollow shaft that serves as an internal filtrate collecting manifold. Tlie filter cakes are built on each side... 

An alternative arrangement of vertical leaf pressure filter has the leaves supported on the filtrate manifold from below, with the whole enclosed in a vertical cylindrical shell, as shown in Figure 3.63. The leaves are now of different widths, according to the chord of the cross-sectional circle that they occupy. This version of the vertical leaf pressure filter is the least expensive of the pressure leaf and plate filters. 

Vacuum leaf filters are less common, although cheaper than the pressurized version, because of the lack of a pressure vessel. They consist of an open tank full of the liquid to be filtered, into which the array of vertical leaves is submerged. Vacuum is applied through the filtrate manifold, and cake builds up on the leaves until cake removal becomes due. This kind of filter is mostly used with precoat as a clarifying filter, which is not only cheaper but also more easily inspected and maintained. 

Fig. 2 Increasing content recovery by coupling luciferase-based assays with high-throughput biochemical readouts. The same cell line subjected to the luciferase-based assay protocol (HCT116 cells) is evaluated here for its reliability In reporting a biochemical readout (p53 expression) by dot blot analysis. Cells transfected with indicated expression construct and pathway reporters in a 96-well culture plates were lysed 48 h posttransfection. Following luciferase activity measurements (data not shown), protein from spent lysates was immobilized on nitrocellulose using a liquid handler and filtration manifold, (a) p53 and p-actin protein levels detected using protein-specific antibodies, infrared fluorescent dye-coupled secondary antibodies (with emissions at 680 and 800 nM), and the Li-COR imaging system. Columns of lysate corresponding to cells transfected with p53 DNA are boxed, (b) Quantification of the p53 to p-actin protein ratio...

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