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Free PSA



96 Wells
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Product Name: Free PSA

# of Samples: 1 x 96 Assays

Intended Use: Free PSA kit is a direct solid phase enzyme immunoassay for quantitative determination of free Prostatic Specific Antigen (fPSA) in human serum.

Introduction: Prostate Specific antigen (PSA) is a serine protease with chymotrypsin-like activity. The protein is a single chain glycoprotein with a molecular weight of 28.4 kDA. PSA derives its name from the observation that it is a normal antigen of the prostrate but is not found in any other normal or malignant tissue. PSA is released from the normal prostate and appears at low serum concentrations in healthy men. Studies with reverse transcription-PCR have shown that PSA also is expressed at a low concentration in peripheral blood cells and other tissues. High serum concentrations can be detected in patients with advanced prostate cancer (PCA). Therefore PSA is applied as a tumor marker for the clinical management of PCA. However, increased PSA concentrations in serum also occur in patients with benign prostate hyperplasia (BPH). Hence the goal is to discriminate clearly between BPH and PCA in the clinical laboratory to spare the patient invasive diagnostic procedures, such as a prostate biopsy.
In human serum PSA occurs in two forms: free PSA (f-PSA) and complexed PSA. The major form is a complex of PSA and α1-antichymotrypsin (ACT). The fraction of f-PSA was shown to be substantially smaller in patients with untreated PCA than in patients with BPH. Therefore combined measurements of f-PSA and total PSA (t-PSA) may lead to a better discrimination between BPH and PCA. Some recent studies have already shown that the f-PSA/t-PSA ratio is helpful in the differential diagnosis of BPH and PCA.
PSA is found in benign, malignant and metastatic prostrate cancer. Since prostate cancer is the second most prevalent form of male malignancy, the detection of elevated PSA levels plays an important role in the early diagnosis. Serum PSA levels have been found to be more useful than prostatic acid phosphatase (PAP) in the diagnosis and management of patients due to increased sensitivity.

Principles of the assay: In this method, standards, patient specimens and/or controls (containing the native fPSA antigen) are first added to streptavidin coated wells. Biotinylated monoclonal and enzyme labelled antibodies are then added and the reactants are mixed: these antibodies have high affinity and specificity and are directed against distinct and different epitopes of fPSA.

Storage and Stability: The closed reagents are stable up to the expiry date stated on the label when stored at +2…+8 °C in the dark.
Opened reagents are stable for 60 days when stored at +2…+8°C.

Limitations of the Test: Bacterial contamination or repeated freeze-thaw cycles of the specimen may affect the absorbance values.

References Christensson A, Laurell CB, Lilja H., Eur J Biochem, 194, 755- 63 (1990).Watt KW, et. al., Proc Nat Acad Sci USA, 83, 3166-70 (1986).Chen Z, Prestiglacomo A, Stamey T., Clin Chem,, 41, 1273-82 (1995).Wild D, The Immunoassay Handbook., Stockton Press p452 (1994).Junker R, Brandt B, Zechel C, Assmann G, Clin Chem, 43, 1588- 94 (1997).Prestigiacomo AF, Stamey TA, ‘ Physiological variations of serum prostate antigen in the (4-10 ng/ml) range in male volunteers.’ J. Urol (1996); 155:1977-80.Stamey TA, McNeal JE, Yemoto CM, Sigal BM, Johnstone IM,‘Biological determinants of cancer progression in men with prostate cancer.’ JAMA (19999;281:1395-1400.Chen Z, Prestigiacomo A, Stamey T, ‘Purification and characterization of Prostate Specific Antigen (PSA) Complexed to a1- Anticymotrypsin:Potential reference Material for International Standardization of PSA Immunoassays.’ Clin Chem. (1995);41/9:1273-1282.Horton GL, Bahnson RR, Datt M, Cfhan KM, Catalona WJ and Landenson JH.’Differences in values obtained with two assays of Prostate Specific Antigen.’ J. Urol. (1988);139:762-72.Stenman UH, Leinonen J, Alfthan H, Rannikko S, Tuhkanen Kand Alfthan O.’A complex between prostate specific antigen anda1-anticymotrypsin is the major form of prostate specific antigenin serum of patients with prostate cancer:assay of complex improves clinical sensitivity for cancer.’ Cancer Res.(1991);51:222-26.

Additional Information

Name Free PSA
Related Product Names Free PSA
Molecular Weight 0.5
Datasheets / Downloads GWB-2E3483 Datasheet
Storage The closed reagents are stable up to the expiry date stated on the label when stored at +2…+8 °C in the dark.
Opened reagents are stable for 60 days when stored at +2…+8°C.
Intended Use Research Use Only