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R L Wolfert

Publications and source records attributed to R L Wolfert.

34 records · Page 2Linked to original sources
PubMed1996

Evaluation and comparison of two new prostate carcinoma markers. Free-prostate specific antigen and prostate specific membrane antigen.

BACKGROUND: Two new prostate cancer markers, free-prostate specific antigen (f-PSA) and prostate specific membrane antigen (PSMA) were recently introduced. This report summarizes a prospective two-year multicenter test of their diagnostic or prognostic capabilities. Total PSA was also measured. METHODS: There were four clinical groups studied: (1) 226 individuals from a screening project undergoing ultrasound and biopsy evaluation had markers obtained: (2) 68 patients suspected of having prostate cancer and undergoing 2 or more biopsies had the markers obtained on multiple occasions: (3) 100 patients undergoing radical prostatectomy had markers obtained pre- and post-operatively: and (4) 31 patients with metastatic prostate cancer each had multiple samples for marker assay obtained over a 2-year period. In all, 465 patients had one or more samples obtained and studied. RESULTS: Free-PSA affords little additional diagnostic advantage compared with total PSA in the screening population. The receiver operating characteristic curves for diagnostic accuracy were ranked: (1) PSA density; (2) total PSA; (3) f-PSA; and (4) PSMA, PSMA showed the best correlation with stage of the primary tumor in the screened group. In the multiple negative biopsy group, f-PSA varied from 12 to 21%. PSMA values were evaluated in all histologic categories. PSA density was > or = 0.15 in all categories. In the prostatectomy cases PSA values postoperatively were quite low in Stage II; f-PSA was of no value. Later, f-PSA was increased in association with elevated total PSA values. Mean PSMA values were above normal in all postoperative time periods except in Stage III patients at 6 months to 1 year postoperatively. PSA densities were all > or = 0.15. In patients with metastatic carcinoma, elevated PSMA values correlated best with a poor prognosis (clinical progression), as has been described. CONCLUSIONS: These data suggest that f-PSA values do not provide additional diagnostic benefit compared with total PSA in screening populations, in the presence of suspected cancer, postprostatectomy, or in metastatic disease. PSMA is of prognostic significance, especially in the presence of metastatic disease, and correlates well with the stage of disease in cancers detected in a screened population.

Antigens, Neoplasm↗
PubMed1996

Dual monoclonal antibody immunoassay for free prostate-specific antigen.

Prostate-specific antigen (PSA) is the most important tumor marker for early detection and monitoring of prostate cancer (PCa) patients. PSA is also elevated in many patients with benign prostatic hyperplasia (BPH). The study of the serum PSA forms, free PSA (f-PSA) and PSA complexed with alpha 1-antichymotrypsin (PSA-ACT), may improve the discrimination between PCa and BPH. An immunoassay specific for f-PSA is reported with very low cross-reactivity (0.7%) to PSA-ACT. Serum specimens from BPH and PCa patients (determined by biopsy) with PSA levels from < 1 to > 100 ng/ml were tested. No f-PSA was detected in serum specimens from normal females (N = 50). Low levels (0-0.3 ng/ml) were detected in specimens from healthy males (N = 60). In specimens from PCa and BPH patients, the f-PSA to total PSA ratio (f/t) was found to range from 1% to higher than 60%. While maintaining an 80% sensitivity for cancer, the f/t ratio improved specificity to approximately 80%, as compared to 55% for total PSA alone. The receiver operating characteristics (ROC) curve analysis of the f/t ratio displayed a greater area under the plot (0.84) compared to total PSA alone (0.745). The results demonstrate that the f/t ratio significantly increases specificity for PCa detection compared to total PSA alone, showing the potential clinical value of the f-PSA immunoassay.

Adult↗
PubMed1996

A comparison of the free fraction of serum prostate specific antigen in men with benign and cancerous prostates: the best case scenario.

PURPOSE: In most previous studies of free-to-total serum prostate specific antigen (PSA) ratios, the specimens from patients with prostate cancer or those with benign prostatic hyperplasia (BPH) have not been highly characterized. We compared preoperative sera from post-radical prostatectomy patients with clinically significant cancers of at least 2 cm.3 to sera from those with BPH and large, biopsy negative prostates. MATERIALS AND METHODS: We used 2 different time resolved immunofluorometric assays for free and total PSA, and a combination of a chemoluminescent immunoassay for free PSA detection with an immunoradiometric assay for total PSA to measure free and total PSA. The serum ratios of free-to-total PSA in these assays were compared to those obtained previously from gel filtration studies. Sera from 51 men with prostate cancer volumes of 2 to 18 cm.3 were compared to those from 48 men with BPH and a mean prostate volume of 78 +/- 7 cm.3. The respective mean serum PSA levels plus or minus standard deviation were 10.0 +/- 6.3 and 8.9 +/- 7.2 ng./ml. RESULTS: Monoclonal assays for free PSA confirmed the previous study with gel filtration. For PSA 4 to 10 ng./ml., 94 to 95% of the men with prostate cancer were correctly diagnosed, with a cutoff of less than 15% for free-to-total PSA on immunofluorometric assay and less than 14% for chemoluminescent immunoassay with immunoradiometric assay. However, 46% (immunofluorometric assay) and 36% (chemoluminescent immunoassay and immunoradiometric assay) of men with BPH did not have enough free PSA for diagnosis of BPH (that is 36 to 46% false-positive rate). CONCLUSIONS: For total PSA 4 to 10 ng./ml., the sensitivity of approximately 15% free-to-total PSA for prostate cancer is high (94 to 95%) but 36 to 46% of men with BPH and a large gland will not be correctly identified. For PSA 2 to 4 ng./ml., no ratio of percent free-to-total PSA discriminated BPH from prostate cancer.

Antibodies, Monoclonal↗
PubMed1996

Clearance rate of serum-free and total PSA following radical retropubic prostatectomy.

BACKGROUND: Our objective was to determine the clearance rate of free and total serum PSA following radical retropubic prostatectomy. METHODS: Sera were obtained from 10 men with localized prostate cancer prior to and 1, 4, 8, 24, 48, and 72 hr after radical prostatectomy. No patient received any postoperative blood transfusion. Free and total PSA were measured using the Hybritech Tandem-R (total PSA) and radioimmunometric free PSA assay. Postsurgery serum-free and total PSA concentrations were modeled using a "two-compartment" pharmacokinetic model. RESULTS: The pharmacokinetic model with an initial constant "infusion" suggests that, following release from the prostate, both free and total PSA are taken up into a second compartment for metabolism. The movement of PSA between these compartments was accurately modeled. Following surgery, there is a shift of both free and total PSA best modeled as a constant infusion into the serum at a rate of 1.97 and 1.60 ng/ml, respectively, for a period of approximately 1 hr. Following this initial constant infusion, the half-life estimations for free and total PSA are initially 1.2 and 0.75 hr, respectively, which then increase to 22 and 33 hr, respectively. CONCLUSIONS: Serum free and total PSA are cleared from the circulation following a "two-compartment" model with an initial constant "infusion." The constant "infusion" is most likely a consequence of surgical manipulation. The initial half-life estimates are < 2 hr for both free and total PSA, and later increase to 22 and 33 hr, respectively.

Aged↗
PubMed1995

Evaluation of percentage of free serum prostate-specific antigen to improve specificity of prostate cancer screening.

OBJECTIVE: To evaluate measurement of percentage of free prostate-specific antigen (PSA) in serum to improve the specificity of prostate cancer screening in men with serum PSA levels between 4.1 and 10.0 ng/mL. DESIGN: Retrospective, nonrandomized analysis using a research assay for measuring free PSA in frozen serum from men with a spectrum of prostate sizes and digital rectal examination results. SETTING: General community outpatient prostate cancer screening program at a university center. PATIENTS: One hundred thirteen men aged 50 years or older, 99% of whom were white, with serum PSA concentrations of 4.1 to 10.0 ng/mL, including 63 men with histologically confirmed benign prostatic hyperplasia, 30 with prostate cancer with an enlarged gland, and 20 with cancer with a normal-sized gland. All study volunteers had undergone prostatic ultrasonography and biopsy. MAIN OUTCOME MEASURES: Percentage of free PSA in serum and percentage of free PSA cutoff that maintained at least 90% sensitivity for prostate cancer detection. RESULTS: Median percentage of free PSA was 9.2% in men with cancer and a normal-sized gland, 15.9% in men with cancer and an enlarged gland, and 18.8% in men with benign prostatic hyperplasia (P < .001). The percentage of free PSA cutoff was higher in men with an enlarged gland and in those with a palpably benign gland. In men with an enlarged, palpably benign gland, a free PSA cutoff of 23.4% or lower detected at least 90% of cancers and would have eliminated 31.3% of negative biopsies. CONCLUSIONS: Measurement of percentage of free serum PSA improves specificity of prostate cancer screening in selected men with elevated total serum PSA levels and can reduce unnecessary prostate biopsies with minimal effects on the cancer detection rate; however, further studies are needed to define optimal cutoffs. Final evaluation of PSA screening also must consider the ability of current treatments to improve the prognosis of screen-detected prostate cancer.

Aged↗
PubMed1995

Molecular forms of prostate-specific antigen and the human kallikrein gene family: a new era.

Without question, much has been learned about the glycoprotein PSA in recent years. By increasing our understanding of this tumor marker's biochemical and physiologic properties, we will be able to improve its clinical utility. The discovery of the various molecular forms of PSA represents a significant advancement. Knowing the concentration and ratio of these PSA forms will be valuable in deciding which patients require further evaluation with transrectal ultrasound and prostate biopsy and which men can be monitored safely without undergoing further invasive testing. This information will be most valuable in treating the patient with a mildly elevated serum PSA level. Although assays are not yet available to detect specifically hK2, the striking similarities of hK2 to PSA, including selective expression in the prostate, suggest that this marker may also prove useful in prostate cancer management. Indeed, a new era of PSA testing has been entered, and the entire field of prostate cancer will benefit.

Amino Acid Sequence↗
PubMed1994

Enhanced immunogenicity of leucine enkephalin following coupling to anti-immunoglobulin and anti-CD3 antibodies.

Leucine enkephalin (Leu-enk) was coupled to both T and B cell antibodies in order to investigate the possibility of enhanced immunogenicity via targeted immunization. The two antibodies used were Hm x Mo CD3 and Gt x Mo Ig, respectively. The data indicate that while both antibody carriers enhanced the immunogenicity of Leu-enk, the use of the Hm x Mo CD3 antibody resulted in a greater number of mice with positive Leu-enk specific serum titers. 12 Leu-enk cell lines were produced and one, LE4H8, was chosen for characterization.

Amino Acid Sequence↗
PubMed1992

Two-site assays of bone gla protein (osteocalcin) demonstrate immunochemical heterogeneity of the intact molecule.

We developed a panel of monoclonal antibodies to human bone gla protein (BGP; osteocalcin) peptides that span the linear sequence of the molecule, specifically BGP 1-12 (N-terminal), BGP 15-30 (midregion), and BGP 38-49 (C-terminal). These antibodies were evaluated in various combinations of two-site formats in studies of serum BGP concentrations. For clinical studies, we selected from a panel of antibodies the two most sensitive antibody pairs for the intact molecule (N-C); we also used a polyclonal RIA based on BGP-C. For the two-site format, we used two N-terminal antibodies, 029 and 052, adsorbed to polystyrene beads, and radioiodinated a C-terminal antibody, 663. The standard for each of the assays was purified human BGP. The following BGP serum concentrations (microgram/L, mean +/- SE) were measured with the various assays: by the 029-663 assay, results for normal subjects were 7 +/- 3, for patients with renal failure 25 +/- 8, and for patients with Paget disease 12 +/-4; by the 052-663 assay, the respective results were 22 +/- 4, 44 +/- 12, and 31 +/- 7; by the polyclonal assay, the results were 3 +/- 0.2, 13 +/- 2, and 5 +/- 1. The two intact (N-C) assays were significantly (P < 0.01) correlated (r = 0.94), but their serum values differed by more than twofold in terms of the same BGP standard. The polyclonal assay significantly correlated with each of the intact assays (r = 0.83, 0.77), but it, too, gave different serum values for BGP. These studies demonstrate the immunochemical heterogeneity of circulating BGP, heterogeneity that is manifest even in immunoassays specific for the same region of the molecule.

Antibodies, Monoclonal↗
PubMed1991

Bone alkaline phosphatase in Paget's disease.

The measurement of bone proteins and peptides and their derived products has been very useful in the diagnosis and management of patients with skeletal disease. This group of assays includes alkaline phosphatase (AP) and bone Gla protein (BGP). We here describe the comparison of a new immunoassay that is specific for bone alkaline phosphatase (BAP) to measurements of total alkaline phosphatase (TAP) and BGP in Paget's disease. In our studies, we demonstrated that BAP was increased in the serum of patients with Paget's disease. Comparisons with the other measurements revealed that BAP correlated better with total AP (r = 0.92) than with BGP (r = 0.51); the lowest correlation occurred between BGP and total AP (r = 0.26). In patients with liver disease, the BAP was indistinguishable from normal whereas the TAP was elevated. These studies indicate that BAP assesses different aspects of bone cell function than BGP in Paget's disease. This discordancy also exists between BGP and total serum AP activity. BAP measurements by immunoassay offer a novel method of assessing skeletal status. Thus, the information that measurement of different bone-specific proteins provides should be separately useful in assessing the skeleton for a variety of metabolic bone diseases.

Alkaline Phosphatase↗
PubMed1985

Molecular associations of class II MHC antigens in mitogen-stimulated B cells.

Previously, we showed that murine B cell membrane proteins undergo rearrangements in the plasma membrane to form new molecular associations in response to mitogenic stimulation. These complexes were covalently stabilized by photoreactive cross-linking agents and were analyzed by SDS PAGE. We have now identified certain complexes that involve class II MHC products, the Ia antigens. Upon stimulation of B cells with LPS, Ia surface molecules (as identified by radioimmunoprecipitation with polyclonal anti-Ia antiserum) enter into a molecular complex with a 95-kd membrane-associated protein (p95) to form a 200-kd complex that may be stabilized by the cross-linking agent dithiobisphenylazide (DTPA). This molecular association is not observed upon stimulation with mitogenic anti-Ig reagents, nor with the polyclonal B cell activator 8-bromoguanosine. p95 is not a disulfide-linked molecule itself, and by separate immunoprecipitation experiments we have established that it is not a component of surface Ig, transferrin receptor, the B cell Fc receptor, or CR1, the receptor for complement component C3b. Further analysis of the association of Ia antigens with surface proteins, with the use of monoclonal antibodies directed against I-A or I-E, has demonstrated that each subregion gene product forms a unique molecular association. Precipitation of radiolabeled lysates from LPS-activated B cells with anti-I-A reveals the aforementioned association with p95. In contrast, the I-E antigen apparently forms complexes with a multimer of a 15-kd protein to give complexes of 45, 60, 75, and 90 kd. When analyzed by two-dimensional diagonal gels (nonreducing/reducing), only the I-E bands are revealed by autoradiography, indicating that the putative p15 that associates with I-E may not be accessible to surface labeling. The disparate molecular associations for I-A and I-E suggest that the formation of these distinct protein complexes may be functionally related to a different role in the process of cellular activation for each of these Ia subregion gene products.

Animals↗
PubMed1984

Demonstration of activation-specific interactions among B lymphocyte membrane proteins by a photoreactive cross-linking agent.

The formation of plasma membrane protein complexes during B cell activation was examined by covalently stabilizing these complexes with a photolabile, cleavable, cross-linking reagent, dithiobisphenylazide (DTPA). Analysis by SDS polyacrylamide gel electrophoresis indicates that LPS induces a time-dependent rearrangement in membrane proteins of splenic B cells. These rearrangements were localized to the plasma membrane by examination of surface-labeled detergent lysates and purified plasma membrane preparations. DTPA-stabilized rearrangements could be detected as early as 15 min and were stable between 3 and 24 hr after mitogen addition. These changes are consistent with the formation of different functional protein complexes during B cell activation. LPS does not induce membrane protein rearrangement in thymocytes, nor does Con A do so in B cells. Therefore, the changes appear to be correlated with the transmission of a relevant activation signal. Activation of B cells with 8- bromoguanosine ( 8BrGuo ), an intracellular mitogen, did not result in protein rearrangement until 12 hr after mitogen addition, suggesting that initial stages of signal transduction by 8BrGuo and LPS follow separate pathways. A common "activated state" of the membrane is established by 12 hr. Inhibition of de novo protein synthesis by cycloheximide did not interfere with formation of new protein complexes during early stages of activation (15 min and 3 hr). These data indicate that covalent cross-linking with DTPA can be used to demonstrate activation-specific interactions among proteins on the surface membrane of B cells.

Animals↗
PubMedDate not supplied

Tau protein in cerebrospinal fluid as an aid in the diagnosis of Alzheimer's disease.

Neurofibrillary tangles and dystrophic neurites are characteristic pathological features found in the brains of Alzheimer's disease (AD) patients. A major constituent of these lesions is the cytoskeletal protein tau. This study examined whether the measurement of tau in cerebral spinal fluid (CSF) has value in the diagnosis of AD. Seventy-seven subjects were enrolled in this prospective study: These included AD (N = 24), Neurological Controls (dementing diseases/syndromes, N = 26), Normal Controls (N = 14), and Others (N = 13). CSF was obtained by lumbar puncture, and tau concentrations (pg/mL) were determined using a dual monoclonal antibody microplate immunoassay. The mean tau value for AD subjects (1,430 +/- 739) was significantly different from Neurological Control subjects (790 +/- 579) (p < 0.001) and Normal Control subjects (816 +/- 355) (p < 0.001). Tau values were elevated in two Neurological Control subjects, one with Binswanger's disease (age 75) and one with depression (age 90). Tau values were also elevated in three Normal Control subjects; two were subjects with a family history of AD. Tau concentrations did not correlate significantly with age in AD subjects (r = 0.05, p = 0.82) or in Normal Control subjects (r = -0.49, p = 0.08). Tau also did not correlate with severity of cognitive impairment in AD subjects (r = -0.03, p = 0.91) or duration of AD symptoms (r = 0.16, p = 0.52). Based on these results and others, CSF levels of tau protein may provide a useful biochemical marker to aid in the clinical diagnosis of AD.

Adolescent↗
PubMedDate not supplied

Detection of human glandular kallikrein, hK2, as its precursor form and in complex with protease inhibitors in prostate carcinoma serum.

Forms of human glandular kallikrein (kK2) in prostate carcinoma serum were identified using monoclonal antibodies specific for hK2 and prohK2. Recombinant mammalian hK2, prohK2, and prostate = specific antigen (PSA) were utilized to confirm the specificity of monoclonal antibodies for hK2 and the lack of reactivity with PSA. In prostate cancer patient sera containing high levels of hK2 (>100 ng/ml), hK2 exists as a complex with alpha1-antichymotrypsin with a molecular weight of 90 kDa. The kallikrein also exists as a 32-kDa free form, which includes the precursor pro form of hK2. The relative amount of complex and free hK2 varied, but in most sera examined the 32-kDa form predominated. Recombinant hK2 readily formed complexes with alpha2-macroglobulin when the two proteins were incubated together as well as when hK2 was spiked into female serum.

Antibodies, Monoclonal↗