Attachment of Algal Cells to Zwitterionic Self-Assembled Monolayers Comprised of Different Anionic Compounds

The influence of zwitterionic self-assembled monolayers on settlement and removal of algae was studied. The monolayers were constructed either from zwitterionic thiols or from solutions of positively and negatively charged thiols. The cationic component was composed of quaternary ammonium terminated thiols and the anionic component contained sulfate or carboxylate termination. During assembly, all surfaces showed a strong tendency for equilibration of the surface charge. Settlement and adhesion assays with zoospores of Ulva linza and the diatom Navicula incerta, and field tests of the initial surface colonization revealed the relevance of charge equilibration for the biological inertness of the prepared surfaces.

Conditioning of self-assembled monolayers at two static immersion test sites along the east coast of Florida and its effect on early fouling development

Among the first events after immersion of surfaces in the ocean is surface 'conditioning'. Here, the accumulation and composition of the conditioning films formed after immersion in the ocean are analyzed. In order to account for different surface chemistries, five self-assembled monolayers that differ in resistance to microfouling and wettability were used. Water samples from two static immersion test sites along the east coast of Florida were collected at two different times of the year and used for experiments. Spectral ellipsometry revealed that conditioning films were formed within the first 24 h and contact angle goniometry showed that these films changed the wettability and rendered hydrophobic surfaces more hydrophilic and vice versa. Infrared reflection adsorption spectroscopy showed that the composition of the conditioning film depended on both the wettability and immersion site. Laboratory and field assays showed that the presence of a conditioning film did not markedly influence settlement of microorganisms.

Adhesion and motility of fouling diatoms on a silicone elastomer

Recent demands for non-toxic antifouling technologies have led to increased interest in coatings based on silicone elastomers that 'release' macrofouling organisms when hydrodynamic conditions are sufficiently robust. However, these types of coatings accumulate diatom slimes, which are not released even from vessels operating at high speeds (>30 knots). In this study, adhesion strength and motility of three common fouling diatoms (Amphora coffeaeformis var. perpusilla (Grunow) Cleve, Craspedostauros australis Cox and Navicula perminuta Grunow) were measured on a poly-dimethylsiloxane elastomer (PDMSE) and acid-washed glass. Adhesion of the three species was stronger to PDMSE than to glass but the adhesion strengths varied. The wall shear stress required to remove 50% of cells from PDMSE was 17 Pa for Craspedostauros, 24 Pa for Amphora and >>53 Pa for Navicula; the corresponding values for glass were 3, 10 and 25 Pa. In contrast, the motility of the three species showed little or no correlation between the two surfaces. Craspedostauros moved equally well on glass and PDMSE, Amphora moved more on glass initially before movement ceased and Navicula moved more on PDMSE before movement ceased. The results show that fouling diatoms adhere more strongly to a hydrophobic PDMSE surface, and this feature may contribute to their successful colonization of low surface energy, foul-release coatings. The results also indicate that diatom motility is not related to adhesion strength, and motility does not appear to be a useful indicator of surface preference by diatoms.

Roughness-dependent removal of settled spores of the green alga Ulva (syn. Enteromorpha) exposed to hydrodynamic forces from a water jet

Topographic features change the hydrodynamic regime over surfaces subjected to flow. Hydrodynamic microenvironments around topographic structures may have consequences for recruitment and removal of propagules of marine benthic organisms. The settlement and adhesion of zoospores from the green alga Ulva linza (syn. Enteromorpha linza) to defined topographies was investigated. A range of topographic size scales (Rz: 25-100 microm) was manufactured from plankton nets, creating patterns with ridges and depressions. The topographic scales span a roughness similar to that of natural substrata and antifouling coatings. Spores were removed from the surfaces by a calibrated water jet. Fewer spores were removed from the smallest topographic structure tested (Rz: 25 microm) compared to both the smooth (Rz: 1) and the roughest (Rz: 100 microm) structures. Zoospores that settled in depressions were less likely to be removed compared to spores on the ridges. The results in terms of the interaction between surface topography and hydrodynamic forces have implications for both natural substrata exposed to wave action and antifouling surfaces on ships' hulls. The possible effects of topography on increasing zoospore adhesion and offering a refuge from hydrodynamic forces are discussed.

Early detection of prostate cancer in African-American men through use of multiple biomarkers: human kallikrein 2 (hK2), prostate-specific antigen (PSA), and free PSA (fPSA)

Recent studies have reported enhanced prostate cancer detection in Caucasians with serum human glandular kallikrein 2 (hK2) in combination with total- (tPSA) and free-prostate-specific antigen (fPSA). The purpose of this study is to validate these findings in an African-American patient cohort. A total of 137 African-American men were found by routine screening to have tPSA levels above 2.5 ng/ml or an abnormal digital rectal examination. Sera were drawn prior to biopsy of the prostate and Hybritech PSA, FPSA and hK2 (for research use only, not for use in diagnostic procedures) concentrations were determined on Beckman Coulter's Access immunoanalyzer. These independent variables and the ratios of percent fPSA (%fPSA), hK2/tPSA, hK2/fPSA, and hK2*tPSA/fPSA were compared between cancer and non-cancer groups. In all, 49 of 137 men had prostate cancer. hK2 and its calculated ratios outperformed tPSA on receiver operator characteristic (ROC) analysis, but %fPSA had statistically the highest area under the curve (AUC) at 0.801. When restricting the analysis to only the tPSA range of 4.0-10 ng/ml, hK2/fPSA yielded the highest AUC (0.721). The ratio of hK2/fPSA was also found to increase the positive predictive value (PPV) of the %fPSA ranges less than 10 and 10-25%. %fPSA offered the best performance and highest specificity in prostate cancer detection in African-American males over the entire range of tPSA. hK2/fPSA may offer modest improvement in the tPSA range of 4.0-10 ng/ml. Furthermore, hK2/fPSA can enhance the PPV of low %fPSA values. Therefore, the use of multiple biomarkers may ultimately increase the specificity of prostate cancer screening in African-American men.

Three models to relate detachment of low form fouling at laboratory and ship scale

Since fouling-release coating systems do not prevent settlement, various methods to quantify the tenacity of adhesion of fouling organisms on these systems have been offered. One such method is the turbulent channel flow apparatus. The question remains how the results from laboratory scale tests relate to the self-cleaning of a ship coated with a fouling-release surface. This paper relates the detachment strength of low form fouling determined in the laboratory using a turbulent channel flow to the conditions necessary for detachment of these organisms in a turbulent boundary layer at ship scale. A power-law formula, the ITTC-57 formula, and a computational fluid dynamics (CFD) model are used to predict the skin-friction at ship scale. The results from all three methods show good agreement and are illustrated using turbulent channel flow data for sporelings of the green macrofouling alga Enteromorpha growing on a fouling-release coating.

Reduction of Cr(VI) and bioaccumulation of chromium by gram positive and gram negative microorganisms not previously exposed to Cr-stress

Resistance to Cr(VI) is usually associated with its cellular exclusion, precluding enrichment techniques for the isolation of organisms accumulating Cr(VI) via bioreduction to insoluble Cr(III). A technique was developed to screen for potential Cr(VI) reduction in approx. 2000 isolates from a coastal environment, based on the non-specific reduction of selenite and tellurite to Se0 and Te0, and reduction of tetrazolium blue to insoluble blue formazan. The most promising strains were further screened in liquid culture, giving three, which were identified by 16S rRNA sequence analysis as Bacillus pumilus, Exiguobacterium aurantiacum and Pseudomonas synxantha, all of which reduced 100 microM Cr(VI) anaerobically, without growth. The respective removal of Cr(VI) was 90% and 80% by B. pumilus and E. aurantiacum after 48 h and 80% and by P. synxantha after 192 h. With the gram positive strains Cr(VI) promoted loss of flagella and, in the case of B. pumilus, lysis of some cells, but Cr was deposited as an exocellular precipitate which was identified as containing Cr and P using energy dispersive X-ray microanalysis (EDAX). This prompted the testing of Citrobacter sp. N14 (subsequently re-assigned by 16S rRNA sequence analysis and biochemical studies as a strain of Serratia) which bioprecipitates metal cation phosphates via enzymatically-liberated phosphate. This strain reduced Cr(VI) at a rate comparable to that of P. synxantha but Cr(III) was not bioprecipitated where La(III) was removed as LaPO4, even though a similar amount of phosphate was produced in the presence of Cr(III). Since B. pumilus removed most of the Cr(VI), with the formation of cell-bound CrPO4 implicated, this suggests that this strain could have future bioprocess potential.

Development of a dual monoclonal antibody immunoassay for total human kallikrein 2

BACKGROUND

Human kallikrein 2 (hK2) shares 80% sequence identity with prostate-specific antigen (PSA). Because both hK2 and hK2-alpha(1)-antichymotrypsin (hK2-ACT) complexes have been identified in patient sera, we devised an immunoassay for total hK2 [(thK2); hK2 and hK2-ACT] and evaluated it in healthy subjects and patients with prostate disease.

METHODS

We developed monoclonal antibodies (mAbs) with high specificity for hK2 and hK2-ACT and minimal cross-reactivity to PSA. Using these mAbs, a sandwich assay was developed and its specificity for forms of hK2 was assessed. Serum samples (n = 1035) from healthy volunteers, patients with increased PSA, and men who had undergone radical prostatectomy were assayed for thK2. We also measured thK2 in samples before and after storage under common laboratory conditions.

RESULTS

The minimum detectable concentration in the thK2 assay was 0.008 microg/L, and PSA cross-reactivity was <0.001%. The assay detected prohK2 and three different hK2-serum protease complexes. The median serum concentration of thK2 in control samples (0.013 microg/L) was significantly lower than the median in samples from patients with increased PSA concentrations (0.085 microg/L). Immunoreactive hK2 changed little in samples stored for up to 1 month at -70 degrees C.

CONCLUSIONS

The thK2 assay recognizes all forms of hK2 that have been found in bodily fluids to date.

Brefeldin A affects adhesion of zoospores of the green alga Enteromorpha

Primary adhesion of zoospores of the green macroalga Enteromorpha to substrata involves a massive release of adhesive glycoproteins from Golgi-derived, membrane-bounded vesicles in the anterior region of the spore, followed by rapid curing. This process is sensitive to low concentrations (5-10 microg x ml(-1)) of the secretion-inhibiting antibiotic, brefeldin A (BFA). The proportion of cells that settled in BFA was reduced by approximately 50%, but the effect was fully reversed by washing in seawater to remove the BFA. Ultrastructural observations showed that BFA caused the breakdown of Golgi stacks in the majority of cells examined. When settled cells were subjected to shear stress, a greater proportion of those settled in the presence of BFA were detached, compared with controls, indicating reduced adhesion strength in the presence of the antibiotic. The most likely reason for this is that strong adhesion to substrata either requires the synthesis of extra adhesive materials beyond those present in the swimming spore, or the secretion of an additional component required for adhesive curing. The novel use of atomic force microscopy in force modulation mode demonstrated that the adhesive secreted by most spores in the presence of BFA did not undergo the rapid curing process typical of control spores. However, some variation between zoospores was observed, with some cells showing no ultrastructural changes and normal adhesive curing. These results are discussed in relation to variations observed in the propensity and competence of spores to settle, which may be reflected in differential requirements for de novo synthesis and secretion of materials needed for full adhesion.

Microbial reduction of technetium by Escherichia coli and Desulfovibrio desulfuricans: enhancement via the use of high-activity strains and effect of process parameters

Escherichia coli and Desulfovibrio desulfuricans reduce Tc(VII) (TcO(4)(-)) with formate or hydrogen as electron donors. The reaction is catalyzed by the hydrogenase component of the formate hydrogenlyase complex (FHL) of E. coli and is associated with a periplasmic hydrogenase activity in D. desulfuricans. Tc(VII) reduction in E. coli by H(2) and formate was either inhibited or repressed by 10 mM nitrate. By contrast, Tc(VII) reduction catalyzed by D. desulfuricans was less sensitive to nitrate when formate was the electron donor, and unaffected by 10 mM or 100 mM nitrate when H(2) was the electron donor. The optimum pH for Tc(VII) reduction by both organisms was 5.5 and the optimum temperature was 40 degrees C and 20 degrees C for E. coli and D. desulfuricans, respectively. Both strains had an apparent K(m) for Tc(VII) of 0.5 mM, but Tc(VII) was removed from a solution of 300 nM TcO(4)(-) within 30 h by D. desulfuricans at the expense of H(2). The greater bioprocess potential of D. desulfuricans was shown also by the K(s) for formate (>25 mM and 0.5 mM for E. coli and D. desulfuricans, respectively), attributable to the more accessible, periplasmic localization of the enzyme in the latter. The relative rates of Tc(VII) reduction for E. coli and D. desulfuricans (with H(2)) were 12.5 and 800 micromol Tc(VII) reduced/g biomass/h, but the use of an E. coli HycA mutant (which upregulates FHL activities by approx. 50%) had a similarly enhancing effect on the rate of Tc reduction. The more rapid reduction of Tc(VII) by D. desulfuricans compared with the E. coli strains was also shown using cells immobilized in a hollow-fiber reactor, in which the flow residence times sustaining steady-state removal of 80% of the radionuclide were 24.3 h for the wild-type E. coli, 4.25 h for the upregulated mutant, and 1.5 h for D. desulfuricans.

Use of human glandular kallikrein 2 for the detection of prostate cancer: preliminary analysis

OBJECTIVES

Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of a multigene family of serine proteases that share approximately 80% sequence homology. Both are expressed in the prostate epithelium, are under androgen regulation, are present in serum and seminal fluid, and can form complexes with endogenous protease inhibitors (eg, alpha2-macroglobulin and alpha1-antichymotrypsin). Differences in immunohistochemistry and substrate specificity suggest hK2 may provide unique information for early detection and characterization of prostate cancer.

METHODS

Nine hundred thirty-seven archived serum samples from men treated at two academic institutions were studied. All men underwent biopsy, had a histologically confirmed diagnosis of cancer or noncancer, and a total PSA level greater than 2 ng/mL. Samples were tested in Hybritech's Tandem-R PSA and Tandem-R free PSA (fPSA) assays and a research prototype assay for total hK2 (thK2).

RESULTS

The thK2/fPSA ratio provided additional specificity for cancer detection over PSA and the percentage of fPSA (%fPSA). A model for cancer detection using %fPSA and the thK2/fPSA ratio when PSA is 2 to 4 ng/mL is proposed that would identify as many as 40% of the cancers and would require biopsy in only 16.5% of the men in this PSA range.

CONCLUSIONS

In this study, %fPSA and thK2/fPSA provided unique information for prostate cancer detection and increased the specificity of cancer detection.

Use of percentage of free prostate-specific antigen to identify men at high risk of prostate cancer when PSA levels are 2.51 to 4 ng/mL and digital rectal examination is not suspicious for prostate cancer: an alternative model

OBJECTIVES

Currently, many clinicians do not recommend prostate biopsy for men with digital rectal examination (DRE) results that are not suspicious for cancer and prostate-specific antigen (PSA) values between 2.51 and 4 ng/mL. We propose a new model for the detection of prostate cancer using the percentage of free PSA (%FPSA) in the limited range of PSA values between 2.51 and 4 ng/mL that maximizes clinical specificity (ie, minimizes false-positive results). This model identifies higher risk patients in this relatively low-risk population.

METHODS

Three hundred sixty-eight archived serum samples from men evaluated and treated at two academic institutions were reviewed. All men had a histologic diagnosis, findings not suspicious for cancer on DRE, and PSA levels between 2.51 and 4 ng/mL. Samples were tested in Hybritech's Tandem-R PSA and Tandem-R free PSA (FPSA) assays in the same laboratory at each institution.

RESULTS

Various models for cancer detection using %FPSA when PSA is 2.51 to 4 ng/mL and DRE is not suspicious for cancer are proposed. These models recommend biopsy for only 10% to 36% of the men in this population and would identify as many as 30% to 54% of the detectable cancers. There is evidence that the cancers that would be detected are the most aggressive cancers in this population.

CONCLUSIONS

Our models identified men with a higher risk of prostate cancer in a relatively low-risk population that currently does not routinely undergo biopsy. This may allow for a more cost-effective way to increase cancer detection when PSA values are between 2.51 and 4 ng/mL and DRE is not suspicious for cancer. This model has the potential to detect a greater number of clinically important and potentially curable cancers than would be detected with current practice.

Highly sensitive automated chemiluminometric assay for measuring free human glandular kallikrein-2

BACKGROUND

Human glandular kallikrein (hK2) is a serine protease that has 79% amino acid identity with prostate-specific antigen (PSA). Both free hK2 and hK2 complexed to alpha1-antichymotrypsin (ACT) are present in the blood in low concentrations. We wished to measure hK2 in serum with limited contribution from hK2-ACT for the results.

METHODS

We developed an automated assay for hK2 with use of a select pair of monoclonal antibodies. The prototype assay was implemented on a Beckman Coulter ACCESS(R) analyzer.

RESULTS

The detection limit of the assay was 1.5 ng/L, the "functional sensitivity" (day-to-day CV <15%) was <4 ng/L, cross-reactivity with PSA and PSA-ACT was negligible, and cross-reactivity with hK2-ACT was 2%. After surgical removal of prostate glands, serum hK2 was <7 ng/L and was <15 ng/L in most healthy women. The median serum concentration of hK2 in healthy men without prostate cancer was 26 ng/L. The median concentration of hK2 was 72 ng/L for men having prostate cancer with lower Gleason scores compared with 116 ng/L for men with more advanced cancer. The concentration of hK2 correlated weakly with PSA, with the mean hK2 concentrations generally 30- to 80-fold lower than PSA concentrations.

CONCLUSION

The availability of a robust, high sensitivity automated assay for hK2 should facilitate further investigations of the role of hK2 measurements in the management of patients with prostate disease.

Phosphate release and heavy metal accumulation by biofilm-immobilized and chemically-coupled cells of a Citrobacter sp. pre-grown in continuous culture

A heavy metal-accumulating Citrobacter sp. was grown in carbon-limiting continuous culture in an air-lift fermentor containing raschig rings as support for biofilm development. Planktonic cells from the culture outflow were immobilized in parallel on raschig rings by chemical coupling (silanization), for quantitative comparison of phosphatase activity and uranyl uptake by both types of immobilized cell. The flow rate giving 50% conversion of substrate to product (phosphate) in flow-through reactors was higher, by 35-40%, for the biofilm-immobilized cells, possibly exploiting a pH-buffering effect of inorganic phosphate species within the extracellular polymeric material. Upon incorporation of uranyl ions (0.2 mM UO22+), both types of cell removed more than 90% of the input UO22+ at slow flow rates, but the chemically-coupled cells performed better at higher flow rates. The deposited material (HUO2PO4) subsequently removed Ni2+ from a second flow via intercalative ion exchange of Ni2+ into the crystalline HUO2PO4.4H2O lattice. This occurred irrespective of the method of coupling of the biomass to the support and suggested that uranyl phosphate accumulated by both types of cell has potential as a bio-inorganic ion exchanger-a potential use for the uranium recoved from primary waste treatment processes.

Polyclonal and monoclonal antibodies to prostate-specific antigen can cross-react with human kallikrein 2 and human kallikrein 1

OBJECTIVES

The human tissue kallikrein family contains three closely related proteases: human kallikrein 1 (hK1), human kallikrein 2 (hK2), and prostate-specific antigen (PSA). The structural homology between these three proteins suggests potential cross-reactivity interference when different immunologic techniques are used. This study evaluated PSA and hK2 monoclonal antibody (mAb) and polyclonal antibody (pAb) reactivities to hK1, hK2, and PSA.

METHODS

mAbs and pAbs to hK2 and PSA were evaluated using Western blot analysis on hK1, hK2, PSA, and seminal plasma.

RESULTS

pAbs to PSA and hK2 recognized all three human kallikreins, as well as fragments of hK2 and PSA. An mAb with minimal (less than 0.4%) cross-reactivity between PSA and hK2 and a cross-reactive mAb were found. mAbs specific to PSA or hK2 did not cross-react with the less homologous hK1 protein. A PSA mAb raised specifically to PSA fragments recognized both PSA and hK2 but did not cross-react with hK1. pAbs to hK1 cross-reacted slightly with PSA and not at all with hK2.

CONCLUSIONS

Both pAbs and mAbs to hK2 and PSA may exhibit immunocross-reactivity. pAbs to PSA or hK2 react with all three human tissue kallikreins. The potential for cross-reactivity should be considered in any clinical or research procedures that use hK1, hK2, and PSA antibodies.

Human Kallikrein 2 (hK2) and prostate-specific antigen (PSA): two closely related, but distinct, kallikreins in the prostate

Recent studies on human kallikrein 2 (hK2) have revealed striking similarities and significant differences with the closely related kallikrein PSA. Both PSA and hK2 are primarily localized to the prostate and share close structural similarities. Although both kallikreins are produced by the same secretory epithelial cells in the prostate, hK2 is associated more with prostate tumors than PSA and is highly expressed in poorly differentiated cancer cells. The potent trypsin-like activity of hK2 contrasts with the weak chymotrypsin-like activity of PSA. The inactive precursor form of PSA, proPSA, is converted rapidly to active PSA by hK2, suggesting an important in vivo regulatory function by hK2 on PSA activity. The high homology between hK2 and PSA results in significant cross-reactivity to hK2 by polyclonal and some monoclonal antibodies to PSA. Future studies on both PSA and hK2 need to take into account this potential for cross-reactivity. Specific monoclonal antibodies to hK2 have now demonstrated that serum levels of hK2, like PSA, are correlated with prostate cancer. The production of hK2 protein in active protease form and specific monoclonal antibodies to the hK2 antigen will allow extensive future studies delineating the physiological and clinical utility of this new prostate antigen.

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.

Development of monoclonal antibodies specific for human glandular kallikrein (hK2): development of a dual antibody immunoassay for hK2 with negligible prostate-specific antigen cross-reactivity

OBJECTIVES

Human glandular kallikrein (hK2) is a protein that is 80% homologous to prostate-specific antigen (PSA), and, like PSA, is localized to the prostate. We developed a specific immunoassay for hK2 that can be used to evaluate its clinical diagnostic utility.

METHODS

We developed monoclonal antibodies (mAbs) specific for hK2 by immunizing with hK2 and screening for clones reactive with hK2 and not PSA. Prototype sandwich assays using these mAbs were tested, and the optimum pair selected. Purified hK2 was used as standard and PSA cross-reactivity was assessed in the assay. Both hK2 and hK2-alpha1-antichymotrypsin (ACT) complexes have been identified in sera of patients with prostate cancer (PCa). Serum samples (n = 671) from healthy volunteers and patients with prostate disease were assayed for hK2 and PSA levels.

RESULTS

The assay had a detection limit of less than 0.12 ng/mL and a less than 0.5% cross-reactivity with PSA. The assay preferentially detected free hK2 with a 3.5-fold higher molar response than with hK2-ACT. The mean serum concentration of hK2 in normal control samples was low (0.33 and 0.37 ng/mL for normal healthy men and women, respectively) but was elevated in patients with prostate disease (0.86 and 6.77 ng/mL for patients with benign prostatic hyperplasia and PCa, respectively). Negligible cross-reactivity to hK2 was measured by Tandem PSA assays (Hybritech).

CONCLUSIONS

Significant concentrations of hK2, relative to PSA, were detected in human serum, especially in patients with prostate disease. Serum hK2 concentrations were not proportional to PSA concentration. Therefore, hK2 has the potential to be an independent and clinically useful marker for PCa.

Molecular forms of prostate-specific antigen and human kallikrein 2 (hK2) in urine are not clinically useful for early detection and staging of prostate cancer

OBJECTIVES

Prostate-specific antigen (PSA), a member of the human kallikrein (hK) family, is the most important tumor marker for early detection, staging, and monitoring of men with prostate cancer today. However, the sensitivity of serum PSA is not sufficient to be used alone for prostate cancer screening. Recently, it was reported that the serum-to-urinary total PSA ratio improves the detection of men with prostate cancer, especially in men with a serum total PSA level between 4.0 and 10.0 ng/mL. We tested this hypothesis by evaluating the clinical usefulness of this PSA ratio as well as the use of the different molecular forms of PSA and human kallikrein 2 (hK2) in urine for detection and staging of prostate cancer.

METHODS

One hundred ten fresh, midstream urine specimens (prostate cancer 62, benign prostatic hyperplasia [BPH] 38, healthy male control 5, women 5) were collected. Serum total PSA, urine total PSA, urinary free PSA, urinary alpha 1-antichymotrypsin-bound PSA, and urinary hK2 levels were determined by monoclonal antibody assays (Hybritech Inc.). The serum-to-urinary total PSA ratio was calculated.

RESULTS

The serum-to-urinary total PSA ratio did not accurately distinguish between men with BPH and men with prostate cancer. There was no significant difference between the urinary levels of any of the molecular forms of PSA or hK2 between men with prostate cancer and men with BPH. Among men with prostate cancer, neither urinary hK2 nor urinary levels of any of the molecular forms of PSA correlated with age, pathologic stage, or Gleason grade.

CONCLUSIONS

In our study, the serum-to-urinary total PSA ratio did not improve the detection of men with prostate cancer. Furthermore, measurement of the molecular forms of PSA and hK2 in urine did not improve the detection or staging of prostate cancer over serum PSA alone.

Detection of a prostate-specific protein, human glandular kallikrein (hK2), in sera of patients with elevated prostate-specific antigen levels

OBJECTIVES

Messenger ribonucleic acid for human glandular kallikrein (hK2), a protein similar to prostate-specific antigen (PSA), is expressed in the prostate. Quantitative tests for the relative amounts of PSA in serum have become important in the diagnosis and management of patients with prostate cancer. Measurement of hK2 in serum may also serve as a diagnostic indicator of disease. The object of this study was to determine if hK2 is present in the serum of patients with high serum concentrations of PSA.

METHODS

Recombinant prohK2 with an alanine to valine mutation at aa217 (phK2v217) was expressed in a hamster tumor cell line, AV12. The propeptide was treated with trypsin to yield the mature form of hK2 (hK2v217). Using a monoclonal antibody, HK1G586.1, which recognized wild type and mutant forms of pro- and mature hK2, an hK2-specific radioimmunoassay was developed.

RESULTS

PSA cross-reactivity in the radioimmunoassay (RIA) was 0.23%. hK2 was detected in the sera of 51 of 76 patients with PSA levels above 100 ng/mL. The dose-response curve of hK2-positive samples was linear, and recovery of phK2v217-spiked serum samples was close to 100%. The correlation between PSA and hK2 values in the patient sera was low (r = 0.168).

CONCLUSIONS

Given the importance of the role of PSA as a serologic indicator of prostate cancer, the demonstration that hK2 is also circulating in the blood of patients in different relative proportions to PSA suggests that it may be a significant novel marker for prostate cancer.

Two-dimensional gel electrophoresis detects prostate-specific antigen-alpha1-antichymotrypsin complex in serum but not in prostatic fluid

We investigated the interaction between prostate-specific antigen (PSA) and 1-antichymotrypsin (ACT) in prostatic secretions, identifying PSA and ACT in human serum, prostatic fluid, and seminal plasma by two-dimensional gel electrophoresis (2-D PAGE). Both PSA and ACT were detected in all three body fluids, but PSA-ACT complex was detected only in serum. Moreover, the 2-D PAGE Western blot staining profile for ACT from serum differed from that for prostatic fluid or seminal plasma. Incubation of prostatic fluid with purified ACT led to formation of PSA-ACT complex. Incubation of prostatic fluid with purified PSA, however, failed to form the complex, suggesting that the ACT in prostatic fluid was inactive or inhibited. Given that physiological concentrations of zinc inhibited the formation of PSA-ACT complex, we consider zinc a possible physiological inhibitor of the formation of the PSA-ACT complex. These results indicate that the failure to detect the PSA-ACT complex in prostatic fluid could be related to the inactivation of ACT, the presence of inhibitors (e.g., zinc), or simply the PSA:ACT ratio in the fluid.

Identification of human glandular kallikrein hK2 from LNCaP cells

Based on studies indicating that human glandular kallikrein (hK2) mRNA is present in the prostate, we prepared a monoclonal antibody to a synthetic peptide corresponding to the 41-56 region of hK2 to try to identify the hK2 protein. Although prostate-specific antigen (PSA) and hK2 share 80% homology, the 41-56 amino acid sequence of hK2 is only 50% homologous with PSA. A monoclonal antibody, HK1A523, was identified that demonstrates high specificity for hK2. In western blot analysis, the antibody has a 1,000-fold greater sensitivity for the detection of hK2 than for PSA. The antibody was used to probe spent media from the prostate carcinoma cell line, LNCaP. An immunoreactive species was N-terminally sequenced and identified as mature hK2. HK1A523 was also utilized to probe prostate tumor cytosols and seminal fluid where putative forms of hK2 were also identified. The hK2 protein therefore is expressed and secreted from prostate carcinoma cells.

Outcome prediction in open bite cases

Some anterior open bites close spontaneously, others do not. It would be advantageous if the orthodontist had some means of predicting the spontaneous outcome in open bite patients. One-hundred-and-twenty-seven patients having open bite were recorded longitudinally for a minimum period of 3 years using cephalometric radiographs. The open bite closed spontaneously in 50 per cent of a prepuberal group aged between 7 and 10 years, in 49 per cent of a puberal group aged 11-14 years, and in 44 per cent of a post-puberal group aged between 14 and 21 years when first seen. Data from cephalometric analysis of the first film in each case was analysed using discriminant function analysis. The analysis correctly predicted the outcome in 88 per cent of the prepuberal group, in 74 per cent of the puberal group, and in 94 per cent of the post-puberal group. The accuracy of the prediction equation was checked in a new sample of 35 subjects with open bite observed over at least 2 years so that the spontaneous outcome was known. The equation correctly predicted the outcome in 79 per cent of prepuberal, in 80 per cent of puberal, and in 100 per cent of post-puberal patients in the second sample.

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.

The Saccharomyces cerevisiae APS1 gene encodes a homolog of the small subunit of the mammalian clathrin AP-1 complex: evidence for functional interaction with clathrin at the Golgi complex

Clathrin-associated protein (AP) complexes have been implicated in the assembly of clathrin coats and the selectivity of clathrin-mediated protein transport processes. We have identified a yeast gene, APS1, encoding a homolog of the small (referred to herein as sigma) subunits of the mammalian AP-1 complex. Sequence comparisons have shown that Aps1p is more similar to the sigma subunit of the Golgi-localized mammalian AP-1 complex than Aps2p, which is more related to the plasma membrane AP-2 sigma subunit. Like their mammalian counterparts, Aps1p and Aps2p are components of distinct, large (> 200 kDa) complexes and a significant portion of the Aps proteins co-fractionate with clathrin-coated vesicles during gel filtration chromatography. Unexpectedly, even though the evolutionary conservation of AP small subunits is substantial (50% identity between mammalian and yeast proteins), disruptions of APS1 (aps1 delta) and APS2 (aps2 delta), individually or in combination, elicit no detectable mutant phenotypes. These data indicate that the Aps proteins are not absolutely required for clathrin-mediated selective protein transport in cells expressing wild type clathrin. However, aps1 delta accentuated the slow growth and alpha-factor pheromone maturation defect of cells carrying a temperature-sensitive allele of clathrin heavy chain (Chc) (chc1-ts). In contrast, aps1 delta did not influence the effects of chc1-ts on vacuolar protein sorting or receptor-mediated endocytosis. The aps2 delta mutation resulted in a slight effect on chc1-ts cell growth but had no additional effects. The growth defect of cells completely lacking Chc was compounded by aps1 delta but not aps2 delta. These results comprise evidence that Aps1p is involved in a subset of clathrin functions at the Golgi apparatus. The effect of aps1 delta on cells devoid of clathrin function suggests that Aps1p also participates in clathrin-independent processes.

Regulation of cellular retinol binding protein type II by 1,25-dihydroxyvitamin D3

Previously we purified and sequenced an 18-kDa chick duodenal protein that was modulated by 1,25-dihydroxyvitamin D3. The N-terminus of this protein has striking sequence homology to cellular retinol binding protein type II (CRBP II). Furthermore, this purified chick protein binds retinol. Antibodies have now been generated to the chick protein and used for immunoblot analysis to demonstrate that the chick protein has molecular weight, tissue distribution, and subcellular localization similar to rat CRBP II. These antibodies also cross-reacted with rat CRBP II. Antibodies to rat CRBP II cross-react with the chick protein. Northern analysis using a cDNA probe for rat CRBP II showed a single 860 base pair mRNA in both chick and rat intestinal RNA preparations. These results demonstrate that the 1,25-dihydroxyvitamin D3 modulated protein in chick embryonic organ culture is chick CRBP II. Pulse-chase experiments in chick embryonic duodenal organ culture strongly suggest that 1,25-dihydroxyvitamin D3 markedly decreases the synthesis of CRBP II, while not changing the degradation rate. The concentration of 1,25-dihydroxyvitamin D3 required for the decrease in CRBP II synthesis is approximately that required to stimulate calcium uptake into embryonic chick duodenal organ cultures.

Purification and properties of an 18-kilodalton, 1,25-dihydroxyvitamin D3 modulated protein from embryonic chick intestine

An 18,000-dalton protein (pI = 5.1) shown previously to be modulated by 1,25-dihydroxyvitamin D3 was purified to allow its further characterization. This protein from embryonic chick intestine was shown to comigrate during two-dimensional electrophoresis with an abundant protein from the intestine of 4-week-old chickens. The protein was purified from 4-week chick intestine and analyzed for amino acid composition, and 28 amino acids of its N-terminal sequence were determined. The N-terminal amino acid sequence had significant homology to cellular retinol binding protein II, an intestinal protein that has been recently sequenced. The purified 18-kilodalton protein was shown to bind retinol by fluorescence spectrophotometry. This 18-kilodalton protein is dramatically changed by 1,25-dihydroxyvitamin D3 in the chick embryonic organ culture system. Therefore, further study of it may lead to a better understanding of vitamin A and D interaction and how 1,25-dihydroxyvitamin D3 acts through proteins to stimulate intestinal calcium and phosphate transport.

Retrospective conversion: a survey of UNYOC/MLA members

The Upstate New York and Ontario MLA surveyed its members to determine which libraries are conducting retrospective conversion projects and their reasons and methods. All academic and medical school libraries that responded are converting, but only 16 of 39 hospital libraries and 14 of 23 other libraries have such plans. The majority of respondents intend to do the work themselves instead of contracting with a vendor. They highly recommend that a written plan be drawn up before proceeding with retrospective conversion.