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Patent US4355018A successfully refreshed from Google Patents.
US4355018A
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US
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Assay for vitamin B12
Assignee: Ideal Wilson Medical Center
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Filing: 1980-05-21
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Granted: 1982-10-19
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Expires: 2000-05-21
Abstract
Abstract A highly specific assay for plasma vitamin B12 levels in humans is disclosed. The assay employs intrinsic factor preparations obtained from mouse or rat stomachs, which intrinsic factors are free of R-protein and thus react specifically with vitamin B12 in a competitive binding assay. Detection of vitamin B12 levels is utilized in the diagnosis of several clinical disorders, such as pernicious anemia, a disease state which results in reduced circulating levels of vitamin B12 in the blood.
Inventors
- 👤 Hans J. Hansen
- 👤 Gustavo Reynoso
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:38
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/82
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
108 words
In a radioassay for vitamin B 12 wherein a serum or tissue extract sample is mixed with a known amount of radiolabeled vitamin B 12 and an intrinsic factor preparation, the intrinsic factor bound radiolabeled vitamin B 12 is separated from the unbound radiolabeled vitamin B 12 , the amount of radiolabeled vitamin B 12 in the bound or unbound form is determined and compared to a standard curve obtained with samples of known, varying amounts of vitamin B 12 whereby the amount of vitamin B 12 in the sample can be determined, the improvement comprising using as said intrinsic factor preparation mouse or rat derived intrinsic factor.
Claim 2
Dependent Claim
108 words
In a radioassay for vitamin B 12 wherein a serum or tissue extract sample is mixed with a known amount of radiolabeled vitamin B 12 and an intrinsic factor preparation, the intrinsic factor bound radiolabeled vitamin B 12 is separated from the unbound radiolabeled vitamin B 12 , the amount of radiolabeled vitamin B 12 in the bound or unbound form is determined and compared to a standard curve obtained with samples of known, varying amounts of vitamin B 12 whereby the amount of vitamin B 12 in the sample can be determined, the improvement comprising using as said intrinsic factor preparation mouse or rat derived intrinsic factor.
Claim 3
Dependent Claim
14 words
The improved radioassay of claim 1 wherein said intrinsic factor preparation is mouse derived.
Claim 4
Dependent Claim
28 words
The improved radioassay of claim 1 wherein serum extract sample is obtained by extraction at about pH 4.5, and said assay is carried out at about pH 7.2.
Claim 5
Dependent Claim
15 words
The improved radioassay of claim 1 wherein said radiolabeled vitamin B 12 is 57 Co-cyanocobalamin.
Claim 6
Dependent Claim
53 words
In a kit useful for carrying out radioassays for vitamin B 12 which kit comprises individual vials containing a solution of radiolabeled vitamin B 12 , solutions of vitamin B 12 standards and an intrinsic factor preparation, the improvement comprising providing as said intrinsic factor preparation a mouse or rat derived intrinsic factor.
Claim 7
Dependent Claim
53 words
In a kit useful for carrying out radioassays for vitamin B 12 which kit comprises individual vials containing a solution of radiolabeled vitamin B 12 , solutions of vitamin B 12 standards and an intrinsic factor preparation, the improvement comprising providing as said intrinsic factor preparation a mouse or rat derived intrinsic factor.
Claim 8
Dependent Claim
16 words
The improved kit of claim 5 wherein said intrinsic factor preparation is mouse derived intrinsic factor.
Claim 9
Dependent Claim
28 words
The improved kit of claim 5 wherein said kit contains as additional vials, a vial of cyanide extraction buffer pH 4.5 and a vial of phosphate buffer 7.2.
Claim 10
Dependent Claim
115 words
In a radioassay for vitamin B 12 , wherein a serum or tissue extract sample is mixed with a known amount of radiolabeled vitamin B 12 and an intrinsic factor preparation, the intrinsic factor bound radiolabeled vitamin B 12 is separated from the unbound radiolabeled vitamin B 12 , the amount of radiolabeled vitamin B 12 in the bound or unbound form is determined and compared to a sample curve obtained with samples of known, varying amounts of vitamin B 12 , whereby the amount of vitamin B 12 in the sample can be determined, the improvement comprising using as said intrinsic factor preparation an extract derived from mammalian tissue which is free of R-protein.
Claim 11
Dependent Claim
115 words
In a radioassay for vitamin B 12 , wherein a serum or tissue extract sample is mixed with a known amount of radiolabeled vitamin B 12 and an intrinsic factor preparation, the intrinsic factor bound radiolabeled vitamin B 12 is separated from the unbound radiolabeled vitamin B 12 , the amount of radiolabeled vitamin B 12 in the bound or unbound form is determined and compared to a sample curve obtained with samples of known, varying amounts of vitamin B 12 , whereby the amount of vitamin B 12 in the sample can be determined, the improvement comprising using as said intrinsic factor preparation an extract derived from mammalian tissue which is free of R-protein.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-18 | 1986-04-19 | 1986-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-18 | 1990-04-19 | 1990-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-18 | 1994-04-19 | 1994-10-19 | $7700.00 | Window Closed / Lapsed |