Abstract: A density gradient medium for the isolation and enrichment of rare cells, including fetal nucleated erythrocytes from a peripheral blood sample is described. The medium comprises a colloidal density gradient medium dispersed in a meltable gel. In one aspect of the invention, the density gradient medium is hypertonic to facilitate separation of maternal red blood cells from fetal blood cells.

Abstract: A method for isolating and enriching rare cells, including fetal nucleated erythrocytes from a peripheral blood sample is described. The method includes two centrifugation steps, the first a bulk separation step to enrich erythrocytes from other blood components. The second centrifugation comprises a colloidal density gradient medium dispersed in a hypertonic meltable gel. In one aspect of the invention, maternal erythrocytes may be hemolyzed prior to the second density gradient centrifugation to provide additional enrichment for fetal nucleated erythrocytes.

Abstract: A centrifuge tube and adaptor apparatus is provided which facilitates separation of biological materials and permits easy extraction of a fraction after centrifugation. The tube is a deformable tube with a wide upper chamber and a narrowed lower portion. The tube is supported within the centrifuge rotor or within another container within the centrifuge by a liquid support medium, which surrounds and supports the narrow portion of the tube, and thus prevents the tube from collapsing during high speed centrifugations.

Abstract: A historical time series analysis is obtained from a single sample of blood by measurement of hemoglobin and an altered hemoglobin, for example, glycohemoglobin, on a cell-by-cell basis. The results are compared by ratio of glycohemoglobin to hemoglobin on a cell-by-cell basis. Since the alteration of hemoglobin is continuous and irreversible, the ordered set of ratios represents a time-series of the cells, and any deviation from normal will be readily apparent A time-series can also be derived for other constituents, the time-series representing historical data of the other constituents in the person from whom the blood sample was taken.

Abstract: Apparatus and method for obtaining a concentration gradient in a liquid sample analyzer including flowing a first liquid in a stream to fill a conduit, and continuing the flow of the first liquid along the conduit subsequent to the filling step. Combined with these steps is the step of changing the concentration of the first liquid by removing from the stream a predetermined varying volume of the first liquid and adding to the stream a predetermined proportional varying volume of a second liquid. There is also provided a method of serial dilutions of a liquid stream in a conduit by removal of a portion of the stream prior to each diluent addition for the purpose of conserving diluents which may be reagents.

Abstract: Apparatus is described for treating substances carried or affixed to a surface of a continuous substrate, e.g., a ribbon or tape, with successive treating fluids including liquids contained in a series of treating chambers, adjacent chambers being separated by a high surface tension liquid, e.g., mercury. The chambers may be defined by hollow walls having slots located below the level of the treating fluids in the adjacent treating chambers, such slots being dimensioned to allow passage of the tape between the adjacent treating chambers and to prevent dislocation of the high-surface tension liquid, which is located in the hollow walls and serves to wipe excess treating fluid from the tape during passage between the adjacent treating chambers, so as to prevent carryover therebetween.