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Biomedical subjects

A Prestigiacomo

Publications and source records attributed to A Prestigiacomo.

5 recordsLinked to original sources
PubMed1996

Effect of flutamide and flutamide plus castration on prostate size in patients with previously untreated prostate cancer.

OBJECTIVES: Transrectal ultrasonography (TRUS) was used in previously untreated men with prostate cancer undergoing hormonal therapy to provide objective observations on the decrease in prostate size and to assess the usefulness of prostate size in estimating treatment response. METHODS: In this retrospective study, 31 patients with previously untreated prostate cancer (Stage T1c to D2) who received hormonal therapy (flutamide, n = 18; flutamide plus castration, n = 13) were followed with serial estimations of prostate size by TRUS and by serum prostate-specific antigen (PSA). RESULTS: In both treatment groups, the major decreases in prostate size were noted within the first 6 months of therapy, whereas further follow-up examinations failed to show statistically significant changes. Prostate size decreased by 48% in men treated with flutamide, whereas those treated with flutamide plus castration showed a statistically significant greater decrease, mean of 56% (P < or = 0.01). Six patients (33%) in the flutamide group and 5 (38%) men in the total androgen deprivation group ultimately failed therapy as indicated by a rising PSA level. Only 55% (n = 6) of the patients who progressed showed an increase in prostate size. CONCLUSIONS: Total androgen deprivation in comparison to flutamide alone caused a larger reduction in prostate size. As a marker of hormonal failure, a rising PSA was more sensitive than an increase in prostate size.

Aged↗
PubMed1996

Addition of purified prostate specific antigen to serum from female subjects: studies on the relative inhibition by alpha 2-macroglobulin and alpha 1-antichymotrypsin.

PURPOSE: Two forms of prostate specific antigen (PSA), 1 complexed to alpha 1-antichymotrypsin and the other a free PSA, are recognized by current commercially available immunoassays. A third form of PSA complexed to alpha 2-macroglobulin also is present in the serum. To study these 3 different molecular forms of PSA in vivo, we simulated leakage of PSA from the prostate into the serum in vitro. MATERIALS AND METHODS: Purified seminal fluid PSA was incubated with fresh sera from female subjects at different concentrations. Following gel filtration chromatography, the 3 forms of PSA were studied by immunoassays and Western blot analysis. RESULTS: Using a commercial immunoassay, 60% of immunoreactivity of seminal fluid PSA was lost after incubation with sera from female subjects. Western blot analysis showed that most of this loss in PSA signal was caused by complexation to alpha 2-macroglobulin. Minimal, if any, complexation to alpha 1-antichymotrypsin occurred even when excess alpha 1-antichymotrypsin was added to the serum. CONCLUSIONS: Our studies demonstrated that alpha 2-macroglobulin is a much stronger inhibitor to PSA than alpha 1-antichymotrypsin. Further studies of these complexes may be important. They clearly explain why spiking PSA into sera from female subjects to be used as quality controls for PSA assays leads only to the free form of enzymatically inactive PSA in the serum, and not to the dominant form of complexed PSA and alpha 1-antichymotrypsin present in human serum.

Female↗
PubMed1995

Purification and characterization of prostate-specific antigen (PSA) complexed to alpha 1-antichymotrypsin: potential reference material for international standardization of PSA immunoassays.

We describe for the first time a protocol to purify to apparent homogeneity an in vitro-prepared complex of prostate-specific antigen (PSA) and alpha 1-antichymotrypsin (ACT) by using a combination of gel filtration and ion-exchange chromatography. The purity of the PSA-ACT complex was confirmed by gel electrophoresis and Western blot. The PSA-ACT complex was stable in the pH range 6.0 to 7.8; it was also stable in various matrices, temperatures, and high concentrations of salt. Purification of the PSA-ACT complex was highly reproducible. An absorptivity of 0.99 L x g-1 x cm-1 at 280 nm was assigned to the PSA-ACT complex, based on amino acid analysis. Because PSA and ACT bind in a 1:1 molar ratio, we determined the molecular mass of the PSA-ACT complex as the mass encoded by the cDNA of ACT (plus 26% carbohydrate) plus the molecular mass of PSA (28,430 Da), which totals 89,280 Da. Using this material, we made two common calibrators, one of 100% PSA-ACT complex and one of 90% PSA-ACT complex plus 10% free PSA by volume (90:10 calibrator). Substitution of these calibrators for the manufacturers' calibrators in nine commercial immunoassays substantially reduced differences between immunoassays, especially for serum PSA values between 4 and 10 micrograms/L. The 90:10 calibrator is recommended as a universal calibrator for international standardization of PSA immunoassays.

Amino Acid Sequence↗
PubMed1994

Serum prostate specific antigen binding alpha 1-antichymotrypsin: influence of cancer volume, location and therapeutic selection of resistant clones.

We examined by gel filtration chromatography (Sephacryl 200) sera from 73 untreated patients with peripheral zone prostatic cancer volumes of 1 to 17 cc as well as patients with clinical stages C and D2 cancer. We also examined the sera from 40 patients who had failed radiation or hormonal therapy to determine if clonal cell selection by these 2 therapies altered the binding of prostate specific antigen (PSA) to alpha 1-antichymotrypsin. Finally, we compared sera from 10 patients with benign prostatic hyperplasia (BPH) and 14 with large transition zone-BPH cancer. Without exception, of the total serum PSA recognized by the Hybritech Tandem-R, Yang Pros-Check, Abbott IMx and Ciba Corning ACS assays, 88 to 98% were complexed with alpha 1-antichymotrypsin in all cancer patients. The 10 patients with BPH showed less complexation (73 to 84%). These studies suggest that much of the quantitative differences among assays is determined more by relative differences in recognition of the free and complex forms of PSA than by calibration differences between assays.

Carrier Proteins↗