Abstract: A method of separating cell nuclei from cells comprises: treating a fluid containing whole cells so as to selectively lyse the cytoplasmic membrane together with a small proportion of the nuclear membranes but leaving a large proportion of the cell nuclei intact; applying the treated fluid to a membrane whereby a mesh of DNA from the lysed nuclei is formed on the surface and captures intact cell nuclei. A device for use in the method is described.

Abstract: A method of making a radiopharmaceutical composition by mixing an aqueous solution of pertechnetate with a reducing agent comprising tin metal or stannous ion to reduce the pertechnetate and a complexing agent to form a complex with the reduced technetium, is characterized by incorporating nitrate and/or nitrite in an amount to diminish oxidation of Sn.sup.2+ to Sn.sup.4+, and hence to prevent re-oxidation of technetium to pertechnetate, during preparation and storage of the complex. Nitrate and nitrite are superior to organic antioxidants previously proposed.A reagent for the purpose comprises the reducing agent, the complexing agent and the nitrate and/or nitrite usually in a sterile freeze-dried state.

Abstract: Novel amides of an iodothyronine compound such as tri-iodothyronine (T3) or thyroxine (T4) with an aminoacetic acid compound such as nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) or diethylenetriamine pentaacetic acid (DTPA) may be labelled, e.g. radioactively labelled with I-125, to give labelled derivatives useful in assays of a free thyroid hormone in a biological fluid which also contains the thyroid hormone bound to one or more natural binders. The novel compound T4 EDTA is shown to bind much more strongly to antibodies to T4 than to the natural protein binders in the biological fluid.

Abstract: A method of assaying for vitamin B12 achieves denaturation of serum binding proteins which normally bind the vitamin B12 by treatment with alkali at ambient temperature. The assay is characterized by the use, in the alkali denaturation step, of a dithiopolyol and cyanide, and by the use, during the intrinsic factor assay step, of a vitamin B12 analogue such as cobinamide to bind with any remaining serum proteins. The invention also includes a kit, in which the dithiopolyol is provided in admixture with the alkali.