Method of sampling bodily fluids

Chemistry: analytical and immunological testing – Including sample preparation

Reexamination Certificate

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Reexamination Certificate

active

06171868

ABSTRACT:

BACKGROUND OF THE INVENTION
The ease with which small amounts of blood can be collected onto a filter paper and processed for testing has been of interest in utilizing dried-blood specimens in screening tests for blood-borne diseases such as acquired immunodeficiency syndrome. This technique provides distinct advantages over conventional techniques where access to refrigeration, centrifuges for blood separation, and large supplies of expensive disposal items are limited. Specimens of whole blood collected onto filter paper and dried are also easier and safer to ship than specimens collected by venipuncture.
Nationwide, human immunodeficiency virus type
1
(HIV-
1
) seroprevalence surveys using dried neonatal blood specimens are critical to estimating HIV-
1
seroprevalence among childbearing women. However, the noninclusion of blood specimens deemed “quantity not sufficient” (QNS) for HIV-
1
antibody testing potentially introduces bias. In HIV-
1
seroprevalence surveys which utilize dried neonatal blood specimens, QNS rates can be reduced by the use of multiple ⅛ inch DBS to analyze specimens which are of insufficient quantity to test using a standard ¼ inch punch. By lowering QNS rates, the use of multiple ⅛ inch blood spots can be an effective way of assuring the accuracy of HIV-
1
seroprevalence estimates. Redus et al. (“Use of the ⅛ inch Punch Method to Reduce QNS Rates and Improve Seroprevalence Estimates in the Survey in Childbearing Women”, Centers for Disease Control and Prevention, Atlanta, Ga.), Hoxie et al. (“Improving Estimates of HIV-
1
Seroprevalence Among Childbearing Women: Use of Smaller Blood Spots”,
Am. J. Pub. Health,
October 1992, Vol. 82, No. 10, pgs 1370-1373) and Tappin et al. (“Prevalence of Maternal HIV Infection in Scotland on Unlinked Anonymous Testing of Newborn Babies”,
The Lancet,
Vol. 337, Jun. 29, 1991, pgs 1565-1567) have described the use of DBS less than ¼ inch and the use of four ⅛ inch diameter punches in place of one ¼ inch diameter punch when one ¼ inch punch cannot be obtained.
The immunoassays designed to perform testing on patient samples are generally optimized for maximum detection of a minimal amount of a specific antibody in a given sample. Because of standard practice, these assays require a significant fraction, a ¼ inch or multiple ¼ inch punches of the DBS sample provided by a lay person. Therefore, more samples are required than can be provided by the standard-sized punch. Complete testing is not always possible using standard punch sizes. For example, enzyme immunoassays require elutions from separate DBS punches for testing and subsequent confirmatory assays require additional elutions from separate DBS punches.
The requirement of a ¼ inch punch is a limitation on the rate of compliance as most lay people are only able to provide a DBS which would yield a smaller size punch than the required ¼ inch punch. Moreover, because of the geometry of a circle, in order to obtain four ⅛ inch spots from one DBS, one would need at least one complete ½ inch DBS, or a mix of spots with varying diameters greater than ⅛ inch. In a clinical or hospital laboratory setting, this may be possible when obtaining samples from neonates. However, it is an impractical requirement from a lay person. Therefore, a method is required to punch a multitude of substandard size DBSs from the same DBS which would collectively be equivalent to the standard punch size required by a particular assay.
SUMMARY OF THE INVENTION
It is an object of this invention to provide for a method of obtaining more than one punch from a single dried blood spot.
It is another object of this invention to provide for a method of making a first punchout in a single dried blood spot and sequentially making at least a second punchout in the same dried blood spot with boundaries at least partly outside the boundaries of the first punchout.
It is yet another object of this invention to provide for a method of making at least a first and second punchout having together the minimum surface area required for testing of the dried blood spot.
These and other objects will be apparent from a reading of a remainder of this specification and claims.


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patent: 5204267 (1993-04-01), Sangha et al.
patent: 5413761 (1995-05-01), Dulaney
patent: 5427953 (1995-06-01), Yee
patent: 5432092 (1995-07-01), Yourno
Tappin et al. “Prevalence of maternal HIV infection in Scotland based on unlinked anonymous testing of newborn babies” Lancet, 337, 1991, 1565-1567.
Fortes et al Evaluation of Blood Collected on Filter Paper for Detection of Antibodies to Human Immunodeficiency Virus Type I-J of Clinical Microbiology, 6, 1989, 1380-1381, 27.
Bell et al. Neonatal Thyroxine Screening by Use of a Single-Tube Solid-Phase Radioimmunoassay Clin. Chem, 24/10, 1978, 1755-58.
Jinks et al. “Molecular genetic diagnosis of sickle cell disease using dried blood specimens on blotters used for newborn screening” Human Genetics 81, 1989, 363-366.
Orfanos et al. “Fluorometric Micromethod for Determination of Arginase Activity in Dried Blood Spots” Clin. Chem, 26/8, 1980, 1198-1200.
Standing et al. “Phenylalanine: application of a simple HPLC technique to its measurement in dried blood spots” Ann Clin Biochem. 1992, 29, 668-670.
Mizejewski et al Commercial Radioimmunoassay Kit for Measurement of Alpha-Fetoprotein Adapted for Use w/ Dried Blood Specimens from Newborns, Clin. Chem. 28/5, 1207-1210, 1982.
Konarska et al. (“A simple quantitative micromethod of arginase assay in blood spots dried on filter paper”). Clinica Chimica Acta, 154, 1986, 7-18.
Ho et al. “Quantitative determination of porphyrins, their precursors, and zinc protoporphyrin in whole blood and dried blood by high-performance liquid chromatography with Fluorimetric detection” J. Chrom. 417 1987, 269-276.
Sadler et al. “Blood-Spot Thyrotropin Radioimmunoassay in a Screening Program for Congenital Hypothyroidism”; Clin. Chem 25/6, 933-938, 1979.
Varnier et al. “Whole Blood Collection on Filter Paper Is an Effective Means of Obtaining Samples for Human Immunodeficiency Virus Antibody Assay”. Aids Research and Human Retroviruses, vol. 4, 2 1988, pp. 131-136.
Maeda et al. “An Enzyme Linked Immunosorbent Assay for Thyroxine in Dried Blood Spotted on Filter Paper.” J. Immunological Methods, 82, 1985, 83-89.*

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