Electricity: measuring and testing – Determining nonelectric properties by measuring electric... – Particle counting
Reexamination Certificate
1999-11-01
2004-05-04
Cuneo, Kamand (Department: 2829)
Electricity: measuring and testing
Determining nonelectric properties by measuring electric...
Particle counting
C324S637000
Reexamination Certificate
active
06731100
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and a system for the determination or assessment of the number of somatic cells (or fragments thereof, the fragments to be understood to be included whenever somatic cells are mentioned in the following) in a milk or a milk product analyte material. The present invention relates to the assessment of somatic cells in milk product analyte such as, raw milk collected at cow side, raw milk collected during milking, bulk milk delivered by the dairy farmer, milk and milk products produced by dairies and milk samples being measured in central laboratories.
DESCRIPTION OF THE RELATED ART
Determinations or assessments of the number of somatic cells in a milk or a milk product analyte have been performed by various methods. One of these methods is flow cytometry; instrument for performing flow cytometry is available, e.g., from Becton, Dickinson and Company, Franklin Lakes, USA.
For example, EP 0 556 971 describes a flow cytometric method for assessing the number of particles in a fluid. The fluid is passed by a sensor which detects light signal emitted from the sample. When the sensor detects a change in the light signal, a particle detection is triggered. The particle detection involves generating a pulse of excitation light and hence an intermittent light emission. Light emitted from the flow cell is then focused onto a CCD camera which can produce an image of the particle.
Flow cytometry requires rather elaborate and high cost equipment, partly because of the high accuracy of flow rate necessary to give reliable results, and partly because of the high sensitivity needed to detect the weak signals from the particles in question during the relative short period of time the particle is present in the detector.
Another example of flow cytometry is described in U.S. Pat. No. 5,428,451 wherein particles in a fluid are counted by passing the fluid through an optical cell and allowing an image of the particles to be projected onto an array of charge coupled devices (CCDs). Several arrays of CCDs may be arranged after each other to obtain several pictures of the cells during the flow through the flow cell.
Another known method for the determination of somatic cells in milk is based on the detection of signals from particles which are dispersed on the rim of a polished rotating disc, one such instrument being available from Foss Electric, Hillerød, Denmark. The accuracy in the assessment of the number of particles using this method is dependent on the physical shape of the thin film of sample dispersed on the disk, and high sensitivity is needed to detect the weak signals from the particles in question in the course of the relative short period of time the particle is present in the detector.
One known method for the determination of somatic cells in milk is based on spreading a film of milk onto a ribbon-like film which is then analysed by the means of a microscope, cf. European patent 0 683 395'. This method appears to require a complex mechanical solution in order to work reliably.
Yet another method of assessing the number of particles in milk is described in WO 96/31764 wherein quantitative determination of particles in fluid is carried out by the use of an apparatus comprising an emitter set of light emitters in combination with a detector set of light detectors. Light scattering due to the particles in the sample gives rise to a plurality of signal paths between the emitter and detector sets and these data are gathered and analysed. Thereby information regarding the particle content is obtained, however distinction between the various particles in the same size distribution, such as distinction between cells and fat particles, is not possible.
Due to the relative high complexity and cost of the instruments used today, most of the assessments of the number of somatic cells in a milk or a milk product analyte are carried out in a laboratory where skilled operators operate the instruments.
DESCRIPTION OF THE INVENTION
The present invention offers substantial simplification of the assessment of the number of somatic cells in a milk or a milk product analyte material and therefore makes it possible for operators without any particular skill in this fields of technique to perform the assessment. In particular, the invention makes it possible to perform the assessment on the farm where the sample is taken, thus making the results of the assessment available for the user substantially immediately after the sample material has been collected.
The physical dimension of an instrument based on the present invention is also such that the instrument will be well suited for transport, thus making it possible for e.g. veterinarians to transport the instrument to or on a location where the analysis is needed. The principle of measurement of the present invention provides a major improvement in the assessment of DNA-containing particles, e.g. somatic cells in a milk or a milk product analyte material, compared to the methods hitherto used for this purpose.
This invention extends the capabilities of prior devices and methods to enable more simple and reliable assessment of biological particles in liquid analyte material. The properties which can be assessed are the number of somatic cells in a milk or a milk product analyte material.
At the same time, this invention allows these analyses to be carried out with the use of considerably smaller amounts of chemicals than normally required to do these analyses. These chemicals are often considered hazardous, either to humans and other living organisms or to the environment. Furthermore, this invention presents a solution which minimises the exposure of any hazardous sample or chemicals used for the analysis by either allowing the analysis to be performed in a closed flow system or by the use of a sealed and disposable sample compartment which contains all sample material and chemicals used for the assessment and allows safe transport of the sample and any chemicals.
The high cost as well as the mechanical complexity of the instruments hitherto used for the routine assessment of the number of somatic cells in a milk or a milk product analyte material have made the instruments impractical to use routinely under condition such as are normally present on dairy farms, on milk dairies, or in veterinary clinics. Such analyses are of great interest; for instance, a dairy farmer can monitor the somatic cell count or bacterial count of an individual animal in order to follow the course of clinical or subclinical mastitis or infection, and to control the cell count of the bulk milk delivered to the dairy, thereby minimising the use of antibiotics and preventing the economical penalty which is often a consequence when the cell count of bulk milk exceeds predefined limits.
This invention is particularly suited for the assessment of the number of somatic cells in milk from human, cow, goat, sheep, buffalo or other animal. In particular, this invention is suited for the assessment of the number of somatic cells in milk during milking by integrating the system with the milking equipment, either in-line where the measurement is taken substantially from the milking system and analysed by an instrument which is operated synchronised with the milking, or at-line where the sample is taken before, during or after milking and measured on an instrument in manual operation. In particular it is well suited to obtain an estimate of the number of somatic cells when the purpose of the analysis is to control the number of somatic cells in the bulk of milk delivered to the dairy, for instance by directing any milk which is found to have high cell count to a separate container or outlet.
Methods according to the invention are suited for the on-line or at-line assessment of the number of somatic cells in milk when the purpose is to establish information about the health status of animals, such as cows, goats, sheep or buffaloes, especially in connection with clinical or sub-clinical mastitis.
The method according to the inventio
Arnvidarson Borkur
Glensbjerg Martin
Hansen Frans Ejner Rvan
Jeppesen Jesper Myron
ChemoMetec A/S
Cuneo Kamand
Merchant & Gould P.C.
Patel Paresh
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