Contaminants in fine sediments and their consequences for biota of the Severn Estuary

When the first MPB special issue was published 25 years ago it was suggested that high body burdens of metals and selected organic pollutants in the Severn Estuary were the result of anthropogenic loadings from a variety of sources. The objective of this synopsis is to illustrate recent trends for contaminants (metals, PAHs, PCBs) in sediments and benthic biota and to consider the evidence for improved environmental quality over the last quarter of a century. Contaminants in sediments and sediment-dwelling fauna such as Hediste(=Nereis)diversicolor are, generally, evenly distributed over the estuary - which is the consequence of extensive re-suspension and redistribution of fine sediment by strong tidal currents. Such dispersal tends to mask the influences of individual discharges and physical characteristics are considered to be the major drivers affecting biodiversity in the Severn Estuary, often overshadowing contaminant concerns. Following the closure of major industries and the introduction of stricter pollution control, many inputs have ceased or been reduced and there are indications that environmental concentrations are now lower. Bioaccumulation of most contaminants has declined accordingly (with the possible exception of Cr). Intuitively, better environmental quality should be linked to ecological improvements. However, due to the dynamic nature of the system (and a lack of biological-effects data) it is difficult to establish direct relationships between inputs, body burdens and biological/ecological consequence. Uniquely, the long-term integrated monitoring program of AstraZeneca (Avonmouth) indicates that recovery of faunal diversity and abundance has occurred in mid-sections of the estuary in recent years implying that contaminants have indeed been a forcing feature for Severn biota. In this context, we highlight contaminant issues and biogeochemical changes which may need to be addressed in connection with the development of proposals for tidal energy schemes.

Summary report of the TD-3 workshop: characterization of 83 antibodies against prostate-specific antigen

Twelve research groups participated in the ISOBM TD-3 Workshop in which the reactivity and specificity of 83 antibodies against prostate-specific antigen (PSA) were investigated. Using a variety of techniques including cross-inhibition assays, Western blotting, BIAcore, immunoradiometric assays and immunohistochemistry, the antibodies were categorized into six major groups which formed the basis for mapping onto two- and three-dimensional (2-D and 3-D) models of PSA. The overall findings of the TD-3 Workshop are summarized in this report. In agreement with all participating groups, three main antigenic domains were identified: free PSA-specific epitopes located in or close to amino acids 86-91; discontinuous epitopes specific for PSA without human kallikrein (hK2) cross-reactivity located at or close to amino acids 158-163; and continuous or linear epitopes shared between PSA and hK2 located close to amino acids 3-11. In addition, several minor and partly overlapping domains were also identified. Clearly, the characterization of antibodies from this workshop and the location of their epitopes on the 3-D model of PSA illustrate the importance of selecting appropriate antibody pairs for use in immunoassays. It is hoped that these findings and the epitope nomenclature described in this TD-3 Workshop are used as a standard for future evaluation of anti-PSA antibodies.

Reactivity of anti-PSA monoclonal antibodies with recombinant human kallikrein-2

Seventy-nine monoclonal antibodies submitted to the ISOBM TD-3 PSA Workshop were tested for their reactivity with recombinant human kallikrein-2 (rhK2). A sandwich immunofluorometric assay using polyclonal anti-prostate-specific antigen (PSA) antiserum-coated plates was used to capture rhK2 and subsequently the test antibody. The response of each test antibody was compared with 3 reference antibodies (H50, H117 and 5E4) known to react with hK2. Nine antibodies from the workshop panel failed to react with purified PSA and rhK2 in this assay and were subsequently excluded. From the remaining panel of antibodies, 11/70 showed strong reactivity with rhK2, 9/70 showed weak reactivity with rhK2, while 50/70 antibodies did not react with rhK2 in this assay format. All antibodies binding to rhK2 recognized both free and complexed PSA.

Immunological grouping of 53 antibodies against prostate-specific antigen

Microtiter immunoassays were used to determine whether a panel of 53 monoclonal antibodies submitted to the ISOBM TD-3 PSA Workshop could form assay combinations with free prostate-specific antigen (PSA) and the PSA complex with alpha1-antichymotrypsin. A panel of 6 known anti-PSA antibodies (H117, H50, H179, H164, 2E9 and 5A10) was used as labelled tracers. Epitope groups were proposed based on the ability of the Workshop antibodies to form good assay combinations with these 6 known anti-PSA antibodies. Nine of the TD-3 Workshop antibodies were found to react only with free PSA. Two additional epitope clusters were identified with 8 antibodies showing similar reactivity to antibody H117, while 11 antibodies formed a different cluster showing similar reactivity to antibody H50. Defining the nature of these immunodominant regions will be valuable in the development of more appropriate immunoassays for PSA.

Determination and analysis of antigenic epitopes of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2) using synthetic peptides and computer modeling

Prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), produced essentially by the prostate gland, are 237-amino acid monomeric proteins, with 79% identity in primary structure. Twenty-five anti-PSA monoclonal antibodies (Mabs) were studied for binding to a large array of synthetic linear peptides selected from computer models of PSA and hK2, as well as to biotinylated peptides covering the entire PSA sequence. Sixteen of the Mabs were bound to linear peptides forming four independent binding regions (I-IV). Binding region I was localized to amino acid residues 1-13 (identical sequence for PSA and hK2), II (a and b) was localized to residues 53-64, III (a and b) was localized to residues 80-91 (= kallikrein loop), and IV was localized to residues 151-164. Mabs binding to regions I and IIa were reactive with free PSA, PSA-ACT complex, and with hK2; Mabs binding to regions IIb, IIIa, and IV were reactive with free PSA and PSA-ACT complex, but unreactive with hK2; Mabs binding to region IIIb detected free PSA only. All Mabs tested (n = 7) specific for free PSA reacted with kallikrein loop (binding region IIIb). The presence of Mabs interacting with binding region I did not inhibit the catalytic activity of PSA, whereas Mabs interacting with other binding regions inhibited the catalysis. Theoretical model structures of PSA, hK2, and the PSA-ACT complex were combined with the presented data to suggest an overall orientation of PSA with regard to ACT.

PSA standardization: a review of NCCLS, Stanford and Abbott efforts

The wide variances between prostate specific antigen (PSA) values for various assays and the demonstration that many of these differences are due to calibration differences has resulted in efforts to develop standards for PSA. Two major efforts are underway in the USA. The National Committee for Clinical Laboratory Standards (NCCLS) has published proposed guidelines for the purification and characterization of PSA and PSA-ACT (alpha-1-antichymotrypsin) complexes for primary standards. Furthermore, the Second Stanford PSA Conference proposed a mixture of 90% PSA-ACT and 10% PSA (90:10 standard) with a biochemically defined concentration to calibrate total PSA assays. Significant improvements in agreement between assays was observed with the 90:10 standard as compared to results with kit calibrators. The NCCLS has reviewed and adopted the 90:10 proposal. Thus, biochemically defined standards are preferred over immunoassay defined standards due to differences in assays and laboratory methods. The use of the 90:10 standard will be a major step towards improving the agreement between PSA immunoassays.

Development of the Abbott AxSYM Free PSA assay: performance characteristics and preliminary clinical evaluation

The AxSYM Free PSA assay was demonstrated to have good analytical sensitivity and reproducibility. The F/T ratio determinations for 385 men tested during the Prostate Awareness Week who had biopsies due to an elevated total PSA value and/or a suspicious DRE demonstrated that the percentage of free PSA was lower in patients found to have prostate cancer than those that were biopsy negative for the overall group and for all patient categories examined. The optimal strategy for combining PSA values, F/T ratios, DRE and other clinical and diagnostic parameters to improve the early detection of prostate cancer requires additional clinical studies.

Immunoreactivity of recombinant human glandular kallikrein using monoclonal antibodies raised against prostate-specific antigen

The gene encoding human glandular kallikrein (KLK2) was expressed in Escherichia coli, and the corresponding protein (hK2) was produced by fermentation. The hK2 was characterized by Western blotting and epitope map using monoclonal antibodies (MAbs) specific for another protease, prostate-specific antigen (PSA) with high structural identity (80%). MAbs that recognized three different epitopes were bound to hK2, representing 7 out of 23 MAbs tested. One epitope was localized to the sequence region around amino acid position 78, which is believed to be glycosylated in hK2. The affinities of MAbs recognizing hK2 were similar to those for PSA, suggesting that common epitopes seem to contain very conserved structures. The results may help in designing specific diagnostic assays for the assessment of prostate cancer.

Immunofluorometric assay for sensitive and specific measurement of human prostatic glandular kallikrein (hK2) in serum

Prostate-specific antigen (PSA) and human prostatic glandular kallikrein (hK2) have 79% identity with the primary structure. When we used recombinant hK2 protein, only 7 of 23 monoclonal anti-PSA IgGs (monoclonal antibodies, MAbs) cross-reacted with hK2, which enabled us to design a novel immunofluorometric MAb-MAb assay for the specific detection of hK2. In the first incubation, an excess of MAb 2H11, which does not cross-react with hK2, is added to prevent both free and complexed PSA from reacting in subsequent immunoreactions. In the second incubation, biotinylated MAb H50, which cross-reacts with hK2 by an epitope overlapping with MAb 2H11, served to bind only hK2 to the microtitration wells coated with streptavidin. In the third step, Eu-labeled MAb H117, which cross-reacts with hK2, detected the immobilized hK2. The hK2 assay was calibrated with recombinant hK2. The detection limit of the assay was 0.1 microgram/L, and the cross-reactivity with recombinant PSA was < or = 0.7%. The concentration of hK2 was measured in serum samples from 334 males with total PSA concentrations ranging from 1 to 3400 microgram/L. Most of the samples (57%) had hK2 concentrations below the detection limit. The proportions of hK2 relative to total PSA were 0-2% in 79%, 2-5% in 14%, 5-10% in 4%, and >10% in 3% of the samples. Gel filtration of 10 serum samples with increased hK2 concentrations showed a single peak of hK2 immunoreactivity with an apparent molecular size of approximately 30 kDa, corresponding to that of recombinant hK2 and free PSA.

Immunofluorometric assay for sensitive and specific measurement of human prostatic glandular kallikrein (hK2) in serum

Prostate-specific antigen (PSA) and human prostatic glandular kallikrein (hK2) have 79% identity with the primary structure. When we used recombinant hK2 protein, only 7 of 23 monoclonal anti-PSA IgGs (monoclonal antibodies, MAbs) cross-reacted with hK2, which enabled us to design a novel immunofluorometric MAb-MAb assay for the specific detection of hK2. In the first incubation, an excess of MAb 2H11, which does not cross-react with hK2, is added to prevent both free and complexed PSA from reacting in subsequent immunoreactions. In the second incubation, biotinylated MAb H50, which cross-reacts with hK2 by an epitope overlapping with MAb 2H11, served to bind only hK2 to the microtitration wells coated with streptavidin. In the third step, Eu-labeled MAb H117, which cross-reacts with hK2, detected the immobilized hK2. The hK2 assay was calibrated with recombinant hK2. The detection limit of the assay was 0.1 microgram/L, and the cross-reactivity with recombinant PSA was &lt; or = 0.7%. The concentration of hK2 was measured in serum samples from 334 males with total PSA concentrations ranging from 1 to 3400 microgram/L. Most of the samples (57%) had hK2 concentrations below the detection limit. The proportions of hK2 relative to total PSA were 0-2% in 79%, 2-5% in 14%, 5-10% in 4%, and &gt;10% in 3% of the samples. Gel filtration of 10 serum samples with increased hK2 concentrations showed a single peak of hK2 immunoreactivity with an apparent molecular size of approximately 30 kDa, corresponding to that of recombinant hK2 and free PSA.

Purification and characterization of different molecular forms of prostate-specific antigen in human seminal fluid

We have developed a new procedure for purifying prostate-specific antigen (PSA) from human seminal fluid. The method is based on ammonium sulfate precipitation, hydrophobic interaction chromatography, gel filtration, and anion-exchange chromatography. It can be completed within 2 days with a recovery of intact PSA of 30%. By anion-exchange chromatography, five isoforms of PSA (A, B, C, D, and E) can be separated. The major form (PSA-B) consists of the intact enzyme, as shown by the occurrence of only one band of 33 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing or nonreducing conditions, and by amino acid sequencing, which reveals only one amino-terminal sequence corresponding to the reported amino-terminal sequence of intact PSA. The specific absorbance of 1 g/L PSA-B at 280 nm was 1.61, and 80% of the PSA-B formed a complex with alpha 1-antichymotrypsin, indicating that it is enzymatically active. Three cleaved forms of PSA with different nicking sites and low enzymatic activity were separated from intact PSA by ion-exchange chromatography. In addition, we isolated a glycosylation variant, PSA-A, which showed a higher isoelectric point (pI = 7.2) than PSA-B (pI = 6.9) but similar enzymatic activity; this form accounts for 5-10% of total PSA. After treatment with sialidase, PSA-A and B had the same isoelectric point value (pI = 7.7).

Purification and characterization of different molecular forms of prostate-specific antigen in human seminal fluid

We have developed a new procedure for purifying prostate-specific antigen (PSA) from human seminal fluid. The method is based on ammonium sulfate precipitation, hydrophobic interaction chromatography, gel filtration, and anion-exchange chromatography. It can be completed within 2 days with a recovery of intact PSA of 30%. By anion-exchange chromatography, five isoforms of PSA (A, B, C, D, and E) can be separated. The major form (PSA-B) consists of the intact enzyme, as shown by the occurrence of only one band of 33 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing or nonreducing conditions, and by amino acid sequencing, which reveals only one amino-terminal sequence corresponding to the reported amino-terminal sequence of intact PSA. The specific absorbance of 1 g/L PSA-B at 280 nm was 1.61, and 80% of the PSA-B formed a complex with alpha 1-antichymotrypsin, indicating that it is enzymatically active. Three cleaved forms of PSA with different nicking sites and low enzymatic activity were separated from intact PSA by ion-exchange chromatography. In addition, we isolated a glycosylation variant, PSA-A, which showed a higher isoelectric point (pI = 7.2) than PSA-B (pI = 6.9) but similar enzymatic activity; this form accounts for 5-10% of total PSA. After treatment with sialidase, PSA-A and B had the same isoelectric point value (pI = 7.7).

Free, complexed and total serum prostate specific antigen: the establishment of appropriate reference ranges for their concentrations and ratios

PURPOSE

Prostate specific antigen (PSA) exists in the serum in several molecular forms that can be measured by immunodetectable assays: free PSA, PSA complexed to alpha 1-antichymotrypsin (complexed PSA) and total PSA, which represents the sum of the free and complexed forms. We determined the normal distribution of values and established the appropriate reference ranges for these 3 molecular forms of PSA and their ratios (free-to-total, complexed-to-total and free-to-complexed PSA). Knowing the amount and ratio of these molecular forms appears to be useful in enhancing the ability of PSA to distinguish potentially curable prostate cancer from benign prostatic hyperplasia and in decreasing the number of unnecessary prostate biopsies.

MATERIALS AND METHODS

A total of 422 healthy men 40 to 79 years old was randomly chosen from the male population of Olmsted County, Minnesota and underwent a detailed clinical examination that included digital rectal examination, serum PSA determination and transrectal ultrasound to exclude the presence of prostate cancer. Using newly developed, monoclonal-monoclonal immunofluorometric assays for each molecular form, the free, complexed and total PSA, and the ratios of these 3 forms were determined for each study participant.

RESULTS

All 3 molecular forms correlated directly with patient age (r = 0.45, r = 0.43 and r = 0.45, respectively). Using the 95th percentile, the recommended age-specific reference ranges for the free, complexed and total PSA forms, respectively, are 0.5, 1.0 and 2.0 ng./ml. for men 40 to 49 years old; 0.7, 1.5 and 3.0 ng./ml. for men 50 to 59 years old; 1.0, 2.0 and 4.0 ng./ml. for men 60 to 69 years old, and 1.2, 3.0 and 5.5 ng./ml. for men 70 to 79 years old. With regard to each of the ratios (free-to-total, complexed-to-total and free-to-complexed PSA) none correlated with patient age. As a result, the appropriate upper limit of normal (95th percentile) for all 3 ratios is constant for men of all ages. These reference ranges are greater than 0.15 for free-to-total PSA ratio, less than 0.70 for complexed-to-total PSA ratio and greater than 0.25 for free-to-complexed PSA ratio. The free-to-total PSA ratio will have its greatest value for men with a serum PSA value between 2 and 10 ng./ml.

CONCLUSIONS

The establishment of appropriate reference ranges for free, complexed and total PSA as well as the ratios will allow the practicing urologist to incorporate these new parameters into the diagnostic evaluation of men at risk for early, potentially curable prostate cancer.

Production of recombinant PSA and HK2 and analysis of their immunologic cross-reactivity

Measurements of prostate-specific antigen (PSA) in serum are widely used to monitor patients with prostate cancer, but the attenuation of the assay response by PSA complexed to protease inhibitors has been shown to affect the results in certain assay designs. Moreover, the human glandular kallikrein-2 (hK2), a kallikrein-like serine protease that is 80% similar to PSA, might interfere with the specific detection of PSA by immunological cross-reactivity. We have expressed hK2 and PSA in eucaryotic cells using the Semliki Forest Virus expression system and studied the reactivity of 18 monoclonal anti-PSA IgGs. Five of them cross-reacted with identical affinities to recombinant hK2 whereas 13 recognized PSA alone. The antibodies that recognized both PSA and hK2 bind to a region of the protein that is exposed when PSA is complexed to alpha-1-antichymotrypsin.

Acute lymphoid leukemia in adolescents: clinical and biologic features predict a poor prognosis--a Pediatric Oncology Group Study

Analysis of remission induction rates for 1,768 children (1.5 to 11 years) and 425 adolescents (greater than or equal to 11 years) with acute lymphoid leukemia (ALL), and of event-free survival times for 570 children and 147 adolescents, disclosed that adolescents fared significantly worse by both measures of treatment outcome (P = .0001). Adolescents with either T cell or non-T cell ALL entered remission significantly less often than did children (P = less than .02 and P = less than .001, respectively). Within each of the major immunophenotypes of ALL, adolescents had shorter duration of continuous complete remission: early pre-B (non-B, non pre-B, non-T) (P = .001), pre-B (P = .05), and T (P = .027). We compared the clinical characteristics of adolescents and children, and lymphoblast characteristics present at diagnosis to account for the inferior prognosis of adolescent patients. Adolescents had a higher incidence of T cell ALL (P = .0001) and thus a higher incidence of all T cell-associated characteristics. Adolescents with non-T, non-B ALL were more likely to be male (P = .044), and to have higher leukocyte counts (P = .002) and lower levels of IgG (P = .0003), IgA (P = .0001), and IgM (P = .002). Their leukemic cells had lower PAS scores (P = .0001), a higher incidence rate of L2 morphology by French-American-British (FAB) criteria (P = .001), common ALL antigen negativity (P = .0001), and hypodiploid or pseudodiploid karyotypes (P = .004). These findings clearly indicate an increased incidence of prognostically unfavorable clinical and biologic features in adolescents with ALL, providing a biologic explanation for their poor prognosis.

Clinical and biologic features predict a poor prognosis in acute lymphoid leukemias in infants: a Pediatric Oncology Group Study

Analysis of remission induction rates for 1,117 children 18 months to 10 years of age (group 1) and 90 infants less than 18 months of age (group 2) with acute lymphoid leukemia (ALL) and of duration of continuous complete remission (CCR) for 454 in group 1 and 33 in group 2 revealed that infants fared significantly worse in both measures of outcome (P = .03 and P less than .0001). To examine potential reasons for the poor prognosis of affected infants, clinical and biologic features of their ALL were compared. Infants had higher WBC counts (P less than .001), a higher incidence of massive splenomegaly (P less than .001), massive hepatomegaly (P less than .001), more central nervous system (CNS) disease at diagnosis (P less than .01), and lower platelet counts (P less than .001). Also, their blasts were less often PAS+ (P = .02). The incidence of non(T, B, pre-B), T and pre-B immunophenotypes of ALL did not differ significantly between the two groups. However, in patients with non(T, B, pre-B) ALL, the majority (51%) of infants had common ALL antigen (CALLA)-negative blasts, as compared with only 7% in group 1 (P less than .001). Furthermore, infants with non(T, B, pre-B) cell ALL who were less than 12 months of age were almost always CALLA- (18 of 21). The blasts of children from both groups usually expressed Ia-like antigens. These data illustrate that infants with ALL have extensive and bulky disease more often than do older children and are more often affected with a prognostically unfavorable phenotype of acute leukemia (AL) which expresses Ia-like antigens but is more often PAS- and CALLA-. We believe that these clinical and biological differences predict and explain in part the observed poor response to treatment of infants with ALL.

Pediatric oncology group utilization of immunologic markers in the designation of acute lymphocytic leukemia subgroups: influence on treatment response

The clinical application of blast cell immunophenotype testing is important in childhood ALL for the following reasons. (1) Knowledge of the immunologic group is important in predicting prognosis. Prognostic grouping may prove to be accomplished best by using a combination of traditional risk factors and immunologic phenotyping. However, definition of traditional risk factors may vary within the immunologic groups of ALL. (2) In assessing the relative effectiveness of different treatment regimens for children with ALL it is important to make comparisons among patients within the same major immunologic groups of ALL. (3) Identification of specific immunologic groups of patients within ALL may help in designing therapy for each group. The POG has already made preliminary attempts in this direction for T-ALL and B-ALL. However, leukemia species-specific therapy is still only a long-range goal. Laboratory research must endeavor to identify additional biologic characteristics peculiar to each major immunologic group of ALL. These characteristics may dictate therapeutic maneuvers in the future.

An analysis of clinical and laboratory features of acute lymphocytic leukemias with emphasis on 35 children with pre-B leukemia

In 35 of 191 patients with acute lymphocytic leukemia (ALL) malignant cells were similar in phenotype to B-lymphocyte precursors. Both these patients' lymphoblasts and normal pre-B-cells contain cytoplasmic immunoglobulin (Ig) mu heavy chains, but have no surface Ig. In patients with pre-B leukemias, lymphoblasts containing cytoplasmic mu chains alone were often accompanied by cells of identical morphology that expressed no Ig and less frequently by lymphoblasts bearing scant amounts of surface mu. This spectrum of cellular Ig expression suggests that "null," pre-B, and intermediate pre-B/B ALLs represent closely related malignancies with complete or partial arrests at different stages of maturation. When pre-B, B, T, and "null" cell categories of ALL were compared for 22 different clinical and laboratory features, including remission rate and short-term remission duration, no statistical differences were observed between the pre-B and "null" groups. These early results suggest that pre-B-cell leukemias represents a relatively good prognostic subclass of ALL, do not require more intensive treatment than that proven to be effective for "null" cell ALL, and should be distinguished from the less common, but more clinically aggressive, B-cell subclass of ALL. Longer follow-up will be required to confirm these preliminary conclusions.

Wireless microphone for studies of animal vocalizations

A microphone collar for obtaining good quality recordings of animal vocalizations is described. An inexpensive, commercially available wireless microphone was modified and mounted on a collar with a hearing-aidbattery pack. The complete assembly weighs 25 g, and is readily accepted by domestic cats.