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A B Blase

Publications and source records attributed to A B Blase.

4 recordsLinked to original sources
PubMed1998

Repeat ultrasound guided prostate needle biopsy: use of free-to-total prostate specific antigen ratio in predicting prostatic carcinoma.

PURPOSE: Despite being the most useful tumor marker for the diagnosis of patients with prostate cancer, serum prostate specific antigen (PSA) is still hampered by lack of specificity. A negative prostate biopsy is associated with a 20 to 40% incidence of positive repeat biopsy in men with persistently elevated serum PSA levels. We determine whether the free-to-total PSA ratio could be predictive of prostate cancer in men undergoing repeat biopsy. MATERIALS AND METHODS: Archival sera, drawn before the first biopsy, were gathered from 51 men with a total serum PSA of 2 to 15 ng./ml. who underwent repeat prostate needle biopsy for various indications. The percent free PSA was calculated using the Hybritech Tandem-Rt free and total PSA as well as Dianon Systems freet and Hybritech total PSA assays. The free-to-total PSA ratio results between the cancer and noncancer groups were compared using Student's t test. RESULTS: The median Hybritech free-to-total PSA ratio was significantly lower in patients with positive repeat prostate needle biopsy compared to those with negative biopsy (14.9 versus 19.4%, p=0.05). Total PSA as well as the percent Dianon free-to-Hybritech total PSA ratio were not significantly different between the 2 groups of men. CONCLUSIONS: For total PSA in the range of 2 to 15 ng./ml. Hybritech free-to-total PSA ratio appeared to aid in the prediction of cancer on repeat biopsy.

Aged↗
PubMed1998

Comparison of 3 investigational assays for the free form of prostate specific antigen.

PURPOSE: Measuring percent free/total prostate specific antigen (PSA) versus total PSA alone has been shown to enhance the stratification of cases with and without prostate cancer. We compared the diagnostic performance of 3 free PSA assays when values were interchanged over a common total PSA denominator. MATERIALS AND METHODS: Archival sera from 123 consecutively accrued patients (25 with prostate cancer, 98 with no evidence of malignancy) who had pre-biopsy total PSA levels from 2.0 to 20.0 ng./ml. were obtained from our specimen bank. Serum specimens were analyzed using the Hybritech Tandem R, Dianon Systems and Chiron ACS 180 free PSA assays. Total PSA was measured using the Hybritech Tandem R total PSA assay. Linear regression was performed to evaluate the correlation and agreement among assays. Sensitivity and specificity of cancer detection were calculated to compare diagnostic performance. RESULTS: The required percent free PSA cutoffs were different among the 3 free PSA assays. The cutoffs to ensure a 95% sensitivity of cancer detection were 22, 34 and 34%, and the number of negative biopsies that were prevented at these cutoffs (specificity) was 38, 19 and 33% for the Hybritech, Dianon, and Chiron assays, respectively. CONCLUSIONS: The results among the different assays were not interchangeable. Clinicians should be aware that different percent free PSA cutoffs need to be used based on the type of free and total PSA assays, and that not all assays diagnostically perform the same.

Aged↗
PubMed1997

How many mistakes, how to find them.

The topic of quality control often evokes prolific discussion among those whose business is its administration. Reliable methods for identifying mistakes must be developed in both the manufacture and use of test devices. Unit test devices are uncomplicated to run and provide quick results in a world where speed and simplicity are paramount, yet their very nature as individual assay units introduces questions about the relevance of conventional quality control procedures. Hybritech's ICON QSR CKMB assay is a unit test device that requires daily monitoring according to CLIA'88 regulations. The challenge is to ensure that quality-control testing is value-added, assuring clinicians valid patient sample results although controls are run in a separate "assay." We find that conventional quality-control procedures are indeed valid; however, the fundamental difference of unit test devices must be recognized and accounted for by understanding the capability of the assay in each laboratory.

Chemistry, Clinical↗