US5432097A
Expired / Lapsed
US
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Method for recovery of blood cells from dried blood spots on filter paper
Assignee: Schmeiser Morelle and Watts
•
Filing: 1993-11-09
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Granted: 1995-07-11
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Expires: 2013-11-09
Abstract
Abstract White blood cells (WBC) were recovered from dried blood spots on Guthrie cards by a simple and efficient prototypic method. The mummified formed elements of dried blood on filter paper are first fixed, then the red blood cells laked in-situ. Last, the paper matrix is itself digested away with cellulase in acid buffer, releasing the partially rehydrated, mummified WBC and other cellular materials into suspension for collection and examination.
Inventors
- 👤 Joseph Yourno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:25
CPC Classifications
G; G01; G01N; G01N1/00; G01N1/28; C; C12; C12N; C12N1/00; C12N1/06; C12N15/00; C12N15/09; C12N15/10; C12N15/1003; C12N15/1017; C12Q; C12Q1/00; C12Q1/68; C12Q1/6806; Y; Y10; Y10T; Y10T436/00; Y10T436/25; Y10T436/25125; Y10T436/25375; Y10T436/255
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
83 words
A method for recovery of blood cells from dried blood on a degradable cellulosic medium comprising: providing a degradable cellulosic medium; placing blood cells on said degradable cellulosic medium; allowing said blood cells to dry; fixing said dried blood cells on said cellulosic medium; degrading said medium with an enzyme specific for said degradable cellulosic medium in a buffer; and releasing intact blood cells into a suspension for subsequent analysis wherein said intact blood cells contain at least a cell membrane and cytoplasm.
Claim 2
Independent Claim
83 words
A method for recovery of blood cells from dried blood on a degradable cellulosic medium comprising: providing a degradable cellulosic medium; placing blood cells on said degradable cellulosic medium; allowing said blood cells to dry; fixing said dried blood cells on said cellulosic medium; degrading said medium with an enzyme specific for said degradable cellulosic medium in a buffer; and releasing intact blood cells into a suspension for subsequent analysis wherein said intact blood cells contain at least a cell membrane and cytoplasm.
Claim 3
Dependent Claim
15 words
The method of claim 1, wherein said intact blood cells are white blood cells (WBC).
Claim 4
Dependent Claim
27 words
The method of claim 2, before the step of degrading, including the further step of: laking red blood cells (RBC) to reduce RBC background on said medium.
Claim 5
Dependent Claim
10 words
The method of claim 3, wherein said medium is paper.
Claim 6
Dependent Claim
30 words
The method of claim 4, wherein the step of degrading further comprises: degrading said medium with cellulase in an acid buffer, thereby releasing the intact blood cells into said suspension.
Claim 7
Dependent Claim
20 words
The method of claim 1, further comprising after the step of releasing: spotting said intact blood cells on a slide.
Claim 8
Independent Claim
74 words
A method for recovery of intact white blood cells from cellulosic filter paper comprising: providing dried white blood cells on cellulosic filter paper; fixing said dried white blood cells on said filter paper; degrading said filter paper using cellulase in acid buffer; and releasing intact white blood cells into a suspension for subsequent analysis of the intact white blood cells wherein said intact white blood cells contain at least a cell membrane and cytoplasm.
Claim 9
Independent Claim
74 words
A method for recovery of intact white blood cells from cellulosic filter paper comprising: providing dried white blood cells on cellulosic filter paper; fixing said dried white blood cells on said filter paper; degrading said filter paper using cellulase in acid buffer; and releasing intact white blood cells into a suspension for subsequent analysis of the intact white blood cells wherein said intact white blood cells contain at least a cell membrane and cytoplasm.
Claim 10
Dependent Claim
30 words
The method of claim 7, before the step of degrading, including the further step of: laking red blood cells (RBC) to reduce the RBC background on said cellulosic filter paper.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-07-10 | 1999-01-09 | 1999-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-10 | 2003-01-09 | 2003-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-10 | 2007-01-09 | 2007-07-11 | $7700.00 | Window Closed / Lapsed |