Abstract: A method for calculating gene expression ratios that comprises the steps of spotting a target nucleic acid sequence onto a first area and a second area of a substrate, contacting under hybridization conditions the target nucleic acid contained on the first area and second area of the substrate with a sample containing a mixture of nucleic acids labeled with at least two different labels, measuring a first signal that corresponds to a first label from the first area and second signal corresponding to a second label from the first area of the substrate, determining the log ratio of the first and second signals, fitting a nonlinear relationship relating the uncorrected log ratio to the logarithmic value of a function of the first signal, subtracting the nonlinear relationship from the uncorrected log ratio to obtain a normalized log ratio, and calculating the normalized gene expression ratio as the anti-log of the normalized log ratio.

Abstract: This invention is to a method for detecting an amphiphilic antigen in a biological sample suspected of containing the amphiphilic antigen, which method comprises providing in combination a hydrophilic solid support modified to have a hydrophobic surface and an assay medium suspected of containing an amphiphilic antigen, incubating the combination under conditions sufficient for the amphiphilic antigen to bind to the hydrophobic surface, and determining the presence or amount of the amphiphilic antigen bound to the hydrophobic surface.

Abstract: Methods are disclosed for detecting an antigen in a biological sample. The methods involve providing in combination a solid support, which is substantially free of specific binding proteins, and a medium comprising an antigen from the sample and an antibody for the antigen. The combination is incubated under conditions sufficient for the antibody when bound to the antigen to bind to the support. The presence or amount of antibody on the support or in the medium is determined and is related to the presence of antigen in the sample. The methods have particular application to the detection of gram-negative bacteria.

Abstract: A device and a method for producing the device for use in a chromatographic system wherein a component of a mixture is partitioned is comprised of a chromatographic material. In the chromatographic system the component traverses at least a portion of the chromatographic material. The device generally has at least one longitudinal edge substantially corresponding to the direction of traverse of the component. The longitudinal edge is modified to control the shape of the fron t of the traversing component by introducing along the edge either a plurality of indentations or a chemical substance.

Abstract: A device is disclosed for use in a chromatographic system wherein a component of a mixture is paritioned between a liquid phase and an immobile phase. The device is comprised of a chromatographic material. In the chromatographic system the component traverses at least a portion of the chromatographic material. The device generally has at least one longitudinal edge substantially corresponding to the direction of traverse of the component. The longitudinal edge includes means for controlling the shape of the front of the traversing component.

Abstract: Vitamin B.sub.12 in liquid samples, such as human serum or human plasma, is assayed by a competitive binding technique using intrinsic factor and certain labelled vitamin B.sub.12 derivatives. The labelled derivatives are formed from the (d)-monocarboxylic acid isomer of vitamin B.sub.12, which isomer is free from other monocarboxylic acid isomers (and derivatives thereof) of vitamin B.sub.12, by binding to the (d)-isomer, via the carboxylic group, a compound which is itself a label (e.g. an enzyme) or which comprises a label (e.g. a fluorophore), or to which a label is attached (e.g. a histidine ester to which .sup.125 I is attached). The labelled derivatives of the (d)-monocarboxylic acid of vitamin B.sub.12, free from other isomeric monocarboxylic acids and derivatives, are novel and constitute one aspect of the invention.