Near-IR dyes in three-color volumetric capillary cytometry: cell analysis with 633- and 785-nm laser excitation

Surface-enhanced Raman spectroscopy of serum accurately detects prostate cancer in patients with prostate-specific antigen levels of 4-10 ng/mL

The surface-enhanced Raman spectroscopy (SERS) of blood serum was investigated to differentiate between prostate cancer (PCa) and benign prostatic hyperplasia (BPH) in males with a prostate-specific antigen level of 4-10 ng/mL, so as to reduce unnecessary biopsies. A total of 240 SERS spectra from blood serum were acquired from 40 PCa subjects and 40 BPH subjects who had all received prostate biopsies and were given a pathological diagnosis. Multivariate statistical techniques, including principal component analysis (PCA) and linear discriminant analysis (LDA) diagnostic algorithms, were used to analyze the spectra data of serum from patients in control (CTR), PCa and BPH groups; results offered a sensitivity of 97.5%, a specificity of 100.0%, a precision of 100.0% and an accuracy of 99.2% for CTR; a sensitivity of 90.0%, a specificity of 97.5%, a precision of 94.7% and an accuracy of 98.3% for BPH; a sensitivity of 95.0%, a specificity of 93.8%, a precision of 88.4% and an accuracy of 94.2% for PCa. Similarly, this technique can significantly differentiate low- and high-risk PCa with an accuracy of 92.3%, a specificity of 95% and a sensitivity of 89.5%. The results suggest that analyzing blood serum using SERS combined with PCA-LDA diagnostic algorithms is a promising clinical tool for PCa diagnosis and assessment.

Symmetrical and asymmetrical cyanine dyes. Synthesis, spectral properties, and BSA association study

New cyanines were prepared by an efficient and practical route with satisfactory overall yield from low-cost starting materials. The photophysical behavior of the cyanines was investigated using UV-vis and steady-state fluorescence in solution, as well as their association with bovine serum albumin (BSA) in phosphate buffer solution (PBS). No cyanine aggregation was observed in organic solvents or in phosphate buffer solution. The alkyl chain length in the quaternized nitrogen was shown to be fundamental for BSA detection in PBS in these dyes.

Synthesis and validation of cyanine-based dyes for DIGE

The application of difference gel electrophoresis (DIGE), in particular its most common "minimal labeling" variety, utilizes N-hydroxysuccinimide esters of Cy2, Cy3, and Cy5 dyes, which are commercially available. We describe methods for the efficient synthesis of all three dyes from relatively inexpensive and commercially available precursors in only a few steps and with relatively high yields. In model DIGE experiments, the newly synthesized dyes proved to be indistinguishable from commercially available ones and have been shown to be stable for years while stored under argon as dry solids or after being dissolved in N,N-dimethylformamide.

Bacterial risk reduction by improved donor arm disinfection, diversion and bacterial screening

The Interventions of improved donor arm disinfection, diversion and bacterial screening have been implemented by blood services and shown to have substantial benefit. The major source of bacterial contamination is donor arm derived. Blood services are now introducing best practice donor arm disinfection techniques. Diversion has been shown to substantially reduce bacterial contamination in the order of 40-88%. Diversion, together with improved donor arm disinfection, has shown to improve the percentage of reduction in contamination from 47% to 77%. Residual contamination levels after the Introduction of diversion and improved donor arm disinfection may be in the order of 30-40%. Numerous countries have now implemented screen testing programmes for platelet concentrates, which are the major source of bacterial transfusion transmission. Pathogen reduction systems have been developed and are under development. At present, concerns remain with these systems regarding cost, process control, ability to inactivate high titres of viruses, killing of bacterial spores, product damage, genotoxicity and mutagenicity. The interventions of diversion, improved donor arm disinfection and bacterial screen testing are currently available, As such they can be implemented now to increase blood safety with no associated patient risk.

Practical syntheses of dyes for difference gel electrophoresis

The three dyes (two indocyanine and one benzoxazolium) useful in difference gel electrophoresis-methyl Cy5 1, propyl Cy3 2, and the benzoxazolium dye Cy2 3--and their NHS esters have been prepared by efficient routes in good overall yield from inexpensive precursors.

Bacterial contamination of blood products: factors, options, and insights

Transfusion of bacterially contaminated blood products remains an overlooked problem. However, the risk of receiving a bacterially contaminated unit is greater than the combined risk of HIV-1/2, HCV, HBV, and HTLV I/II [American Association of Blood Banks Bulletin, no. 294, 1996]. Topics covered in this article include: the current incidence, clinical presentation and outcome, effective methods of detection, and ways to reduce bacterial contamination of blood products. There is no one existing strategy that can completely eliminate the risk of bacterial contamination. It is inevitable that partial solutions or combinations of methods will be implemented in the near future.

Antibiotic-labeled probes and microvolume fluorimetry for the rapid detection of bacterial contamination in platelet components: a preliminary report

BACKGROUND

Approximately 1 platelet in 2000 components is bacterially contaminated. Most commonly, contaminating organisms are gram positive skin saprophytes (such as Staphylococcus sp. or Bacillus sp.). A novel approach to the rapid diagnosis of gram positive contamination by the use of a fluorescence-labeled antibiotic probe with affinity for the gram positive cell was investigated.

STUDY DESIGN AND METHODS

Two isolates of Staphylococcus epidermidis were inoculated into bags of Day 0 platelets. Quantitative cultures along with a semi-automated screening assay on a microvolume fluorimeter employing a fluorescence-conjugated vancomycin probe was performed for each day of storage. In addition, serial dilutions of the bacteria were added to sterile platelets to achieve a range spanning 10(1) to 10(8) CFUs per mL.

RESULTS

All samples with a bacterial contamination of > or =10(5) CFU per mL were detected. Sterile samples were nonreactive. The entire procedure requires three pipetting steps and took less than 1 hour to perform.

CONCLUSION

These preliminary results with the use of fluorescence-labeled antibiotics as probes combined with microvolume fluorimetry for the rapid detection of bacterial contamination of platelet components suggest that this is a promising approach. Further studies with additional organisms and alternative conjugates, bacteria, and antibiotics are underway.

Comparison of volumetric capillary cytometry with standard flow cytometry for routine enumeration of CD34+ cells

BACKGROUND

This study assesses the feasibility of a new volumetric cytometry system for the enumeration of CD34+ cells in apheresis components, peripheral blood, and cord blood samples in routine laboratory work. This system is compared with the following flow cytometry protocols: Milan, ISHAGE, ISHAGE with 7-AAD, and flow-count fluorospheres.

STUDY DESIGN AND METHODS

Correlation, linearity, and reproducibility studies were performed for the various methods. Clonogenic cultures were performed, as an external control, to assess the correlation between the number of CD34+ cells per microL and the number of colony-forming units per microL.

RESULTS

The linear regression analysis demonstrated that the five methods were comparable (R2 ranged from 0.86 to 0.96 and slopes were close to 1). The CD34+ assay and the flow-count methods showed poor linearity for CD34+ cell counts below 10 cells per microL (R2 = 0.46 and 0.47). The reproducibility assay for a CD34+ count of 10 cells per microL showed a CV of 12 percent and 25 percent for the Milan and CD34+ assay methods, respectively. The mean CV among all five methods for the 46 evaluated samples was 20 percent. There was a strong correlation between the number of CD34+ cells per microL and colony-forming units per microL in cord blood and apheresis samples (r = 0.71-0.81).

CONCLUSION

The CD34+ assay is useful in CD34 enumeration in cord blood, leukapheresis samples, and peripheral blood samples and provides comparable results to the Milan, ISHAGE, ISHAGE with 7-AAD, and flow-count methods. Nevertheless, peripheral blood samples with low CD34 absolute counts (below 10 cells/microL) should be analyzed by alternative flow cytometry protocols. Even though the same operator performed the study in a single laboratory, the high inter-method CV suggests that differences in sample preparation and gating strategy are factors that increase variability. Protocols with fewer intermediate steps or fully automated protocols such as the CD34+ assay are expected to reduced intra- and inter-laboratory variability.

Enumeration of CD34-positive stem cells: evaluation and comparison of three methods

Accurate enumeration of CD34+ stem cells is important in assessing the need for continued mobilization and subsequent apheresis collections. We compared two new analysis systems, ProCOUNT (Becton Dickinson Immunocytometry Systems) and IMAGN 2000 STELLer (Biometric Imaging, Inc.) with our current (3-Color) flow cytometry-based method. The ProCOUNT system uses an absolute counting tube, which contains reference beads and a specific (multiple) gating strategy to determine an absolute count. The STELLer assay combines microvolume fluorimetry and automated analysis software to determine an absolute count. To evaluate linearity and reproducibility, peripheral blood was spiked with CD34+ cells (KG1a cell line). Three dilution series (measured at approximately equal to 0, 5, 10, 25, 50, and 100 CD34+ cells/microliter) were analyzed by each method. Analysis of predicted versus actual CD34+ concentration showed excellent correlation with all methods (r2 > or = 0.97, slope 0.98-1.04). To further assess precision, two PBSC samples, at approximately 200 and 800 CD34+ cells/microliter, respectively, were analyzed 10 times by each method. Coefficients of variation for the precision analysis of these samples were 5.1%-6.4% and 5.4%-12.3%, respectively. To assess overall performance, 75 patient specimens were analyzed. Excellent correlation (r2 values of 0.89-0.98) was observed among all three methods. We conclude that the three methods provide comparable linearity and reproducibility.