Circulating tumour cells are associated with histopathological growth patterns of colorectal cancer liver metastases

Histopathological Growth Patterns (HGPs) have prognostic and predictive value in patients with Colorectal Liver Metastases (CRLM). This study examined whether preoperative measurement of Circulating Tumour Cells (CTCs) is associated with HGP. CTCs were prospectively enumerated in 7.5 ml of blood using the FDA-approved CellSearch system in patients who underwent local treatment of CRLM with curative intent between 2008 and 2021. All CTC samples were collected on the day of local treatment. Patients treated with neoadjuvant chemotherapy for CRLM or with extrahepatic disease at the time of CTC sampling were excluded. HGP was scored retrospectively following the current consensus guidelines. The association between CTCs and HGP was investigated through multivariable logistic regression. Data were available for 177 patients, desmoplastic HGP (dHGP) was observed in 34 patients (19%). There were no statistically significant differences in patient and tumour characteristics between dHGP and non-dHGP at baseline. Patients with dHGP had longer overall - and disease-free survival (logrank p = 0.003 and 0.003, respectively) compared to patients with non-dHGP. CTCs were not detected in 25(74%) of dHGP patients and in 68(48%) of non-dHGP patients (chi-squared p = 0.006). Preoperative absence of CTCs was the only significant predictor for dHGP in multivariable logistic regression (Odds Ratio 2.7, 95%CI 1.1-6.8, p = 0.028), Table 3. Preoperative absence of CTCs is associated with dHGP in chemo naive CRLM patients without extrahepatic disease. Based on our results, CTC count alone is not sufficient to preoperatively identify HGPs, but integration of CTC count in multivariable prediction models may aid the preoperative identification of HGPs of CRLM.

Prospective Evaluation of a Circulating Tumor Cell Sensitivity Profile to Predict Response to Cisplatin Chemotherapy in Metastatic Breast Cancer Patients

Background

Cisplatin (cDDP) has regained interest for metastatic breast cancer (MBC) patients, given the platinum sensitivity in subtypes and better manageable toxicity. Here, the primary aim was to determine whether molecular characteristics of circulating tumor cells (CTCs) could identify patients responding to cDDP and to describe the outcomes to cDDP monotherapy in a large group of MBC patients pretreated with anthracycline- and taxane-based treatments.

Methods

Based on cell line data, a CTC-cDDP-sensitivity profile was generated. Applying an A’Herns single-stage phase II design, further investigation was considered worthwhile if 5/10 patients with a favorable profile responded to cDDP. Patients received 70mg/m² cDDP every three weeks, CTCs were enumerated and the CTC-cDDP-sensitivity profile was determined. In total, 65 heavily pretreated MBC patients (77% received ≥2 lines of previous chemotherapy for MBC) were eligible for the per-protocol analysis. Primary endpoint was response rate, secondary endpoints included best observed response, progression-free survival (PFS) and overall survival (OS).

Results

The best observed response during cDDP therapy was a partial response in 7% and stable disease in 56% of the patients. None of the patients with a favorable CTC-cDDP-sensitivity profile had a response. The median baseline CTC count was 8 (range 0-3254). Patients with <5 CTCs had a better PFS and OS than patients with ≥5 CTCs (median PFS 4.5 months (95%CI 2.38-6.62) vs. 2.1 months [(95%CI 1.34-2.80)(p=0.009)] and median OS 13.1 months (95%CI 9.89-16.33) vs. 5.6 months [(95%CI 3.60-7.64)(p=0.003)]. No other factors than CTC count were associated with outcome to cDDP therapy, including triple-negative breast cancer versus ER-positive tumors.

Conclusions

The CTC-cDDP-sensitivity profile was unable to select patients responding to cDDP monotherapy. In an unselected group of heavily pretreated MBC patients, cDDP yields outcomes comparable to other chemotherapeutic regimens for heavily pretreated MBC patients. CTC count was the only factor associated with outcome in these patients.

Clinical Trial Registration

(https://www.trialregister.nl/trial/3885, identifier NTR4046)

Prognostic value of circulating tumour cells for early recurrence after resection of colorectal liver metastases

BACKGROUND

Despite good outcomes for many, a substantial group of patients undergoing metastasectomy for isolated liver metastases from colorectal cancer (CRC) experience early recurrence. We have investigated whether circulating tumour cell (CTC) detection can identify patients developing disease recurrence within 1 year after liver metastasectomy.

METHODS

In CRC patients undergoing liver metastasectomy, 30 ml peripheral blood was withdrawn preoperatively. CTCs were detected by the CellSearch system after a density-gradient-based enrichment step.

RESULTS

One hundred and seventy-three samples from 151 individual patients were analysed. In 75 samples (43%), CTCs were detected, 16% had ⩾3 CTCs/7.5 ml of blood. Eighty-two patients (47%) experienced early disease recurrence (<1 year). The 1-year recurrence rate between patients with or without detectable CTCs were similar (47% vs 48%) or with a low or high CTC count (<3 or ⩾3 CTCs/7.5 ml of blood) (50% vs 47%). Also disease-free and overall survival were similar between patients with or without CTCs.

CONCLUSIONS

The presence of CTCs in preoperative peripheral blood samples does not identify patients at risk for early disease recurrence after curative resection of colorectal liver metastases. Other parameters are needed to better identify patients at high risk to relapse after liver metastasectomy for CRC.

A new approach for rapid and reliable enumeration of circulating endothelial cells in patients

BACKGROUND

Mature circulating endothelial cells (CECs) are surrogate markers of endothelial damage/dysfunction. A lack of standardized assays and consensus on CEC phenotype has resulted in a wide variation of reported CEC numbers (4-1300 per mL).

OBJECTIVES

Given the need for a quick, reliable, robust and validated CEC assay at an affordable price, we present a novel approach to enumerate CECs using a multi-parameter flow cytometric (FCM) method without immunological pre-enrichment.

METHODS

CECs were defined as CD34+, CD45neg, CD146+ and DNA+ events based on the immunophenotype of endothelial cells from vein-wall dissections. As CECs express high levels of CD34, we based our assay on absolute CD34 counts after analyzing all CD34 positive events in a total blood volume of 4 mL needed for a precise enumeration of CECs at a frequency of < 1 cell μL(-1).

RESULTS

The endothelial origin of CECs was confirmed by morphology, immunohistochemistry and gene expression. The new FCM assay was tested in parallel with a validated assay (i.e. CellSearch). CEC levels ranged from 4 to 79 CEC mL(-1) in healthy individuals and were significantly higher in patients with advanced solid malignancies (P = 0.0008) and in patients with hematological malignancies (P < 0.0001).

CONCLUSIONS

This flow cytometric method should be useful as a fast and economical assay to enumerate and characterize CECs.

P4-07-14: Circulating Tumor Cells (CTCs) Detection and HER2 Profiling by CellSearch® in Non-Metastatic Breast Cancer: An International Ring Study To Assess Inter-Reader Variability

Background: Preliminary results from the Success and Remagus trials showed that CTC detection by CellSearch® has adverse prognostic value in non-metastatic breast cancer. Moreover, several investigators have characterized HER2 expression on CTCs in early breast cancer. Since the majority of CTC-positive women with non-metastatic breast cancer have only 1 CTC detected / blood volume analyzed, we wanted to evaluate the inter-reader variability in this setting. This is a crucial step before moving forward with multi-lab/multi-center prospective testing of the clinical utility of the CellSearch® technology in non-metastatic breast cancer.

Methods: Five galleries of CellSearch® images from 3 European and one US institution (a total of 307 images) were mailed to 22 independent readers from 14 European and US academic laboratories and 8 readers from two CellSearch® Veridex laboratories in a blinded fashion. These images came mainly from studies on CTC and/or HER2−positive CTC detection in breast cancer and included healthy women (negative controls), women with metastatic (positive controls) and non-metastatic disease (Pierga et al SABCS 2010, Pierga et al ASCO 2011, Riedthorf et al CCR 2010, Ignatiadis et al PLoS ONE 2011). Each reader reported the images as either CTC-negative or CTC-positive/HER2−negative or CTC-positive/HER2−positive. Kappa statistics were used to assess inter-reader agreement. The 8 Veridex readers were summarized by a majority voting system to derive a gold standard in order to compare each independent reader using discordance rates.

Results: Kappa statistics showed moderate to good agreement between independent readers depending on the gallery evaluated (gallery 1 K: 0.55, gallery 2 K:0.57 gallery 3 K:0.64, gallery 4 K:0.72, gallery 5 K:0.85). These differences were attributed to differences in scoring difficulty of each gallery. Discordances in CTC-positive vs CTC-negative events between each reader and the gold standard ranged from 2.3%-31.3% with 7 readers showing discordance rates &lt;5%, 11 readers between 5–10%, 10 readers between 10–14% and only 2 readers showing discordance rates &gt;14% as compared to the gold standard (median discordance rate: 9.3%). Image analysis showed that investigators with high discordance rates compared to the Veridex gold standard were not always taking into account “morphological characteristics” for defining an event as CTC-positive. Discordant results between readers were mainly due to discordance in CTC definition and to a lesser extent in the definition of HER2−positivity. Indeed, discordances in assigning a CTC-positive event as either HER2−negative or HER2−positive ranged from 0.3−13.7% with 19 readers showing discordance rates &lt;5%, 7 readers between 5–10% and 4 readers with discordance rates &gt;10% (median discordance rate: 3.9%).

Conclusion: In non-metastatic breast cancer, we observed low discordance between most independent readers and the gold standard for defining a CellSearch® event as CTC with very few readers showing high discordance rates. Concordance can be improved through appropriate training and the use of all the tools provided by the CellSearch® system for image interpretation.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-07-14.

Abstract P3-02-05: Evaluation of Gene Transcripts in Primary Tumors at Time of Diagnosis and Circulating Tumor Cells (CTCs) at Time of Metastatic Disease

Introduction: The enumeration of CTCs has already shown to bear clinical relevance as a prognostic and predictive factor in metastatic breast cancer. In addition to enumeration, isolation of CTCs enables their molecular characterization and thus holds great promise to establish association of their genetic profile with patient outcome and to identify potential drugable targets. In this study we established epithelial-specific mRNA and microRNA profiles in CTCs of patients with metastatic breast cancer, compared these profiles to the profiles measured in corresponding primary tumors, and determined their association with clinical parameters.

Study design:

For this study we included 50 breast cancer patients, of which 32 presented themselves with over 5 CTCs at the time of metastatic disease. From 14 of these patients with more than 5 CTCs at the time of metastatic disease also the primary tumor at time of breast cancer diagnosis was evaluated. Total RNA was extracted 1) from blood of the 50 patients with metastatic disease after EpCAM-based enrichment of 7.5 mL whole blood with the CellSearch™ Profile Kit [Veridex LCC], 2) from 14 unprocessed whole blood preparations from healthy blood donors, and 3) from 14 primary tumors. Gene transcript levels of CTC-specific and potentially clinically relevant mRNAs and microRNAs were compared in CTCs isolated at time of metastatic disease and the corresponding primary tumors. In addition, the association of these transcript levels with clinical data was assessed.

Results:

We identified 24 mRNA and 14 microRNAs more abundantly expressed in CellSearch-enriched fractions from patients with at least 5 CTCs compared with those without CTCs and/or compared with unprocessed whole blood prior to CellSearch enrichment (Mann-Whitney U-test P&lt;0.05). In addition, when comparing transcript levels present in CTCs during metastatic disease and those measured in the corresponding primary tumor, potentially clinically relevant discrepancies were observed. Findings of interest included changes in transcript levels of genes such as ESR1, ERBB2, TOP2A and MGB1, and in genes associated with proliferation and EMT. Finally, associations were observed between transcript levels measured in CTC preparations and clinical data like nodal status and size of the primary tumor.

Conclusion:

Our results show that molecular characterization of CTCs is feasible and has potential for a more tailored clinical approach above CTC enumeration in the treatment of metastatic breast cancer patients.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-02-05.

Circulating endothelial cells in oncology: pitfalls and promises

Adequate blood supply is a prerequisite in the pathogenesis of solid malignancies. As a result, depriving a tumour from its oxygen and nutrients, either by preventing the formation of new vessels, or by disrupting vessels already present in the tumour, appears to be an effective treatment modality in oncology. Given the mechanism by which these agents exert their anti-tumour activity together with the crucial role of tumour vasculature in the pathogenesis of tumours, there is a great need for markers properly reflecting its impact. Circulating endothelial cells (CEC), which are thought to derive from damaged vasculature, may be such a marker. Appropriate enumeration of these cells appears to be a technical challenge. Nevertheless, first studies using validated CEC assays have shown that CEC numbers in patients with advanced malignancies are elevated compared to healthy controls making CEC a potential tool for among other establishing prognosis and therapy-induced effects. In this review, we will address the possible clinical applications of CEC detection in oncology, as well as the pitfalls encountered in this process.

Imbalances in circulating lymphocyte subsets in Hu antibody associated paraneoplastic neurological syndromes

In paraneoplastic neurological syndromes (PNS) associated with small cell lung cancer (SCLC) and Hu antibodies, neuron-specific Hu antigens expressed by the tumour hypothetically trigger an immune response that cross-reacts with Hu antigens in the nervous system, resulting in tumour suppression and neuronal damage. To gain more insight into the hypothesized cell-mediated immune pathogenesis of these syndromes, we analysed the circulating lymphocyte subsets in untreated patients with SCLC, PNS and Hu antibodies (n = 18), SCLC without PNS (n = 19) and controls (n = 29) using flow cytometry. SCLC patients with PNS had a variety of imbalances within their circulating lymphocyte subsets as compared with SCLC patients without PNS and healthy controls: (i) a lymphopenia of the major subsets (i.e. B, CD4+ and CD8+ T lymphocytes); (ii) increased proportions of activated CD4+ and CD8+ T cells; (iii) reduced numbers of terminally differentiated effector CD8+ T cells and cells with a cytotoxic T-cell phenotype (CD56+ and CD57+). Although indirect, our data provide further support for the involvement of T cells in the pathogenesis of Hu antibody associated PNS.

CSF flow cytometry greatly improves diagnostic accuracy in CNS hematologic malignancies

OBJECTIVE

To assess the diagnostic accuracy of flow cytometric immunophenotyping in comparison with classic cytomorphology for diagnosing CNS localizations of hematologic malignancies, and to evaluate the implications of CSF pleocytosis and protein content in this context.

METHODS

We reviewed the results of diagnostic evaluations of all CSF samples analyzed for localization of a hematologic malignancy between 2001 and 2004 at our center.

RESULTS

A total of 1,054 samples from 219 patients were available for analysis. Sixty patients had a CSF localization diagnosed by positive flow cytometry, cytomorphology, or both. The first sample was positive by flow cytometry in 44 (73%) patients, by cytomorphology in 19 (32%). Four first samples were positive by cytomorphology but negative by flow cytometry. Patients with positive cytomorphology had more frequent clinical symptomatology (95% vs 58%) and CSF pleocytosis (84% vs 25%), and tended to a poorer progression-free survival than patients with positive flow cytometry only. OR for CNS localization in case of CSF pleocytosis was 10.1 (95% CI 4.9 to 20.8); OR for CNS localization in case of elevated protein content was 2.9 (95% CI 1.5 to 5.4). Nevertheless, 26 of 137 (19%) patients with normal cell count and protein concentration had a CNS localization.

CONCLUSIONS

The diagnostic value of flow cytometry is more than twice that of cytomorphology. However, cytomorphologic examination of the CSF has additional diagnostic and possibly prognostic value, and should still be performed in conjunction with flow cytometry.

Discriminant function analysis as decision support system for the diagnosis of acute leukemia with a minimal four color screening panel and multiparameter flow cytometry immunophenotyping

Despite several recommendations for standardization of multiparameter flow cytometry (MFC) the number, specificity and combinations of reagents used by diagnostic laboratories for the diagnosis and classification of acute leukemias (AL) are still very diverse. Furthermore, the current diagnostic interpretation of flow cytometry readouts is influenced arbitrarily by individual experience and knowledge. We determined the potential value of a minimal four-color combination panel of 13 monoclonal antibodies (mAbs) with a CD45/sideward light scatter-gating strategy for a standardized MFC immunophenotyping of the clinically most relevant subgroups of AL. Bone marrow samples from 155 patients with acute myeloid leukemia (AML, n=79), B-cell precursor acute lymphoblastic leukemia (BCP-ALL, n=29), T-cell precursor acute lymphoblastic leukemia (T-ALL, n=12) and normal bone marrow donors (NBMD, n=35) were analyzed. A knowledge-based learning algorithm was generated by comparing the results of the minimal panel with the actual diagnosis, using discriminative function analysis. Correct classification of the test sample according to lineage, that is, BCP-ALL, T-ALL, AML and differentiation of NBMD was achieved in 97.2% of all cases with only six of the originally applied 13 mAbs of the panel. This provides evidence that discriminant function analysis can be utilized as a decision support system for interpretation of flow cytometry readouts.

Parallel Detection of Transduced T Lymphocytes After Immunogene Therapy of Renal Cell Cancer by Flow Cytometry and Real-Time Polymerase Chain Reaction: Implications for Loss of Transgene Expression

We have started a phase I/II immunogene therapy study of metastatic renal cell cancer (RCC), using autologous T lymphocytes transduced ex vivo with a gene encoding a single-chain receptor based on the monoclonal antibody (mAb) G250 [scFv(G250)]. G250 recognizes carbonic anhydrase IX, which is overexpressed by RCC cells. We have developed and validated flow cytometric and real-time polymerase chain reaction (PCR) assays to quantitatively detect transduced T cells in patient blood. The flow assay was based on staining with the anti-G250 idiotype mAb NuH82 and showed a sensitivity of 0.06% scFv(G250)(1) cells within CD3(1) T cells. The real-time PCR method showed a sensitivity of 14 copies of scFv(G250) DNA per 100 ng of total DNA, which enabled detection of 0.008% scFv(G250)(1) T cells within leukocytes. Both assays were further validated for their specificity and reproducibility. When applied to blood samples from three RCC patients treated with intravenous infusions of scFv(G250)(1) T cells, the kinetics of scFv(G250)(1) T cell counts as detected by flow cytometry were similar to those detected by real-time PCR, although PCR allowed detection of transduced T cells over a longer period of time (i.e., for patient 3, 7 versus 32 days, respectively). Interestingly, follow-up studies of patient 3 demonstrated that the number of circulating scFv(G250)(1) T cells remained fairly constant during the first 7 days posttreatment, whereas the number of gene copies increased during the same period of time. These results suggest loss of scFv(G250) membrane expression on adoptive transfer, which would have important implications for the antitumor efficacy of this form of immunogene therapy.

Three-color flowcytometric analysis of mature and immature hematological malignancies. A guideline of the Dutch Foundation for Immunophenotyping of Hematological Malignancies (SIHON)

Multiparameter flowcytometry offers an insight into differentiation pathways, maturation stages and abnormal features of cell (sub)populations thus helping to establish and classify hematological malignancies. The Dutch Foundation for Immunophenotyping of Hematological Malignancies (SIHON) has formulated a guideline for a rapid screening followed by confirmation and classification in a standardized way. For this aim seven carefully composed monoclonal antibody combinations are elucidated for screening the test sample in a first phase. In this phase a relative frequency distribution of the cells will be established and a decision will be made about abnormal cells present, as well as their mature or immature state and the cell lineage they belong to. In a second phase, panels with cell lineage dependent monoclonal antibody combinations may be used to confirm and classify the abnormal cell population indicated in phase 1, as well as to establish the presence or absence of an abberant immunophenotype.

Validation of the single-platform ISHAGE method for CD34(+) hematopoietic stem and progenitor cell enumeration in an international multicenter study

BACKGROUND

Flow cytometric enumeration of CD34+ hematopoietic sterm and progenitor cells (HPC) is the reference point for undertaking apheresis and evaluation of adequacy for PBSC engraftment. An external quality assurance (EQA) scheme for CD34+ HPC enumeration has been operational in Belgium, Netherlands and Luxemburg (Benelux) since 1995. Within this group, a multicenter survey was held to validate the state-of-the-art methodology, i.e., multiparametric definition of HPC based on light scatter, expression of CD34 and CD45, and counting beads (i.e., 'single platform ISHAGE' method).

METHODS

'Real-time' EQA was used to monitor the application of the single-platform ISHAGE method by 36 participants. Three send-outs of stabilized blood with CD34+ cell counts 35-60 cells/microl were distributed to 36 participants, who were required to assay the samples on three occasions using the standard assay and their local techniques. These results were compared with thosed obtained by 111-116 UK NEQAS participants testing the same specimens.

RESULTS

Using the single platform ISHAGE methods, between-laboratory coefficients of variations (CVs) as low as 10% were achieved. Intra-laboratory CVs were < 5% for approximately 50% of the participants. Local single-platform techniques yielded between-laboratory CVs as low as 9% in both Benelux and UK NEQAS cohorts. In contrast, the lowest between-laboratory CVs using dual-platform techniques were 17% (Benelux) and 21% (UK NEQAS), respectively.

CONCLUSION

The single-platform ISHAGE method for CD34+ cell enumeration has been validated by an international group of 36 laboratories. The observed varation between laboratories allows a meaningful comparison of CD34+ cell enumeration.

The NK-2 receptor antagonist SR 48968C does not improve adenosine hyperresponsiveness and airway obstruction in allergic asthma

When stimulated, excitatory nonadrenergic noncholinergic (e-NANC) nerves locally release tachykinins like Neurokinin (NK) A and Substance P, causing neurogenic inflammation and airway obstruction via activation of specific NK-1 and NK-2 receptors. The recently developed nonpeptide NK-2 receptor antagonist SR 48968C has a high affinity for the NK-2 receptor, and is a strong and selective antagonist of NK-2 receptor mediated airway obstruction. In a placebo-controlled cross-over study, we investigated the effect of SR 48968C, administrated orally once-daily in a dosage of 100 mg during 9 days, on airway responsiveness to adenosine 5'-monophosphate (AMP) in 12 allergic asthmatic patients. Furthermore, we assessed its effect on airway obstruction, by measuring FEV1 on the first and last day of each treatment period and by peak flow registration at home throughout the study period. SR 48968C had no significant effect on PC20AMP or on FEV1 measured on day 1 and 9, and morning and evening peakflow measured at home on day 2-8. Thus, although SR 48968C was administrated in a dosage that might cause a demonstrable blocking effect on airway NK-2 receptors in asthma, it did not have a significant bronchodilatory or bronchoprotective effect against adenosine hyperresponsiveness in this study. Further studies are needed to assess the value of SR 48968C and other NK receptor antagonists in the treatment of asthma

Inspiratory muscle training in patients with cystic fibrosis

Little information is available about the effects of inspiratory muscle training in patients with cystic fibrosis (CF). In this study the effects of inspiratory-threshold loading in patients with CF on strength and endurance of the inspiratory muscles, pulmonary function, exercise capacity, dyspnoea and fatigue were evaluated. Sixteen patients were assigned to one of two groups using the minimization method: eight patients in the training group and eight patients in the control group. The training was performed using an inspiratory-threshold loading device. Patients were instructed to use the threshold trainer 20 min a day, 5 days a week for 6 weeks. Patients in the training group trained at inspiratory threshold loads up to 40% of maximal static inspiratory pressure (Pimax) and patients in the control group got 'sham' training at a load of 10% of Pimax. No significant differences were found among the two groups in gender, age, weight, height, pulmonary function, exercise capacity, inspiratory-muscle strength and inspiratory-muscle endurance before starting the training programme. Mean (SD) age in the control group was 19 (5.5) years, mean (SD) age in the training group was 17 (5.2) years. Mean FEV1 in both groups was 70% predicted, mean inspiratory-muscle strength in both groups was above 100% predicted. All patients except one, assigned to the training group, completed the programme. After 6 weeks of training, mean inspiratory-muscle endurance (% Pimax) in the control group increased from 50% to 54% (P = 0.197); in the training group mean inspiratory muscle endurance (% Pimax) increased from 49% to 66% (P = 0.003). Statistical analysis showed that the change in inspiratory-muscle endurance (% Pimax) in the training group was significantly higher than in the control group (P = 0.012). After training, in the training group there was a tendency of improvement in Pimax with an increase from 105 to 123% predicted, which just fell short of statistical significance (P = 0.064). After training no significant differences were found in changes from baseline in pulmonary function, exercise capacity, dyspnoea and fatigue. It is concluded that low-intensity inspiratory-threshold loading at 40% of Pimax was sufficient to elicit an increased inspiratory-muscle endurance in patients with CF.

Increased vascular expression of iNOS at day but not at night in asthmatic subjects with increased nocturnal airway obstruction

Nitric oxide production by endothelial cells may have important consequences for the development of airway inflammation as well as for airway obstruction. The present study investigated whether the expression of vascular inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) in human bronchi differs between asthmatic and healthy subjects, and whether it shows a circadian rhythm, especially in subjects with increased nocturnal airway obstruction. Bronchial biopsy samples were taken at 16:00 and 04:00 h from 13 healthy and 25 asthmatic subjects, 18-45 yrs. Biopsy samples were snap-frozen and double-immunostained for iNOS and eNOS in combination with a common vascular antigen (CD31). The degree of immunopositivity was expressed as a percentage of CD31-positive vessels encountered in complete biopsy sections. Asthmatic subjects showed greater iNOS expression than healthy controls: 23+/-15 versus 7+/-17% (mean+/-SD) at 16:00 h (p<0.001) and 19+/-15 versus 8+/-11% at 04:00 h (p<0.05). Asthmatic subjects with a fall in forced expiratory volume in one second of >10% of the predicted value between 16:00 and 04:00 h showed greater iNOS expression at 16:00 than at 04:00 h: 32+/-16 versus 20+/-13% (p<0.05). eNOS expression did not differ between healthy controls and asthmatic patients, nor did it differ between 16:00 and 04:00 h. It is suggested that asthmatic subjects with increased nocturnal airway obstruction demonstrate increased activation of inducible nitric oxide synthase during the day. The resulting nitric oxide production might protect against airway obstruction during the day. However, at night, nitric oxide production is probably insufficient to counterbalance the bronchoconstricting forces.

Loss of CD34(+) hematopoietic progenitor cells due to washing can be reduced by the use of fixative-free erythrocyte lysing reagents

Current protocols for sample preparation before flow cytometric enumeration of CD34(+) hematopoietic progenitor cells (HPC) include both lyse-non-wash and lyse and wash methods. Erythrocyte lysis without washing is the method of choice when absolute cell counts are to be assessed, whilst a washing step is recommended for immunological subtyping of CD34(+) cells in order to reduce background fluorescence. Here, we analyzed the effect of the interaction between type of erythrocyte lysis reagent and washing on the outcomes of (i) CD34(+) cell enumeration and (ii) expression of CD38 by CD34(+) cells in a single-platform, whole-blood staining assay [Gratama, J.W., Keeney, M., Sutherland, D.R., 1999. Enumeration of CD34(+) hematopoietic stem cell and progenitor cells. Curr. Protocols Cytometry 6(4), 1-22.]. We studied seven commercially available lysing reagents (five containing fixative and two fixative-free) using 12 samples from cord blood (n=4), mobilized peripheral blood (n=4) and apheresis products (n=4). Using the lyse and wash technique, significant reductions of absolute and relative numbers of CD34(+) cells, as well as in the numbers of lymphocytes and leukocytes, were observed on samples that had been lysed using fixative-containing buffers as compared to the lyse-no-wash technique. Cell losses due to washing could be significantly reduced when samples were lysed using fixative-free buffers. 'Postfixation' using PBS+1% paraformaldehyde of samples that had been lysed using fixative-free buffers and then washed did not result in additional loss of CD34(+) cells or other cell types. Finally, washing unfixed samples led to a slight decrease of CD38 monoclonal antibody bound to CD34(+) cells as compared to samples that had been fixed during erythrocyte lysis. These results indicate that fixation renders (CD34(+)) cells sticky and leads to their loss from the cell suspension upon centrifugation and resuspension. We conclude that all seven lysing reagents can be used with confidence in a lyse-no-wash technique, but that only fixative-free lysing reagents should be used when a washing step is considered necessary.

Reduction of intra- and interlaboratory variation in CD34+ stem cell enumeration using stable test material, standard protocols and targeted training. DK34 Task Force of the European Working Group of Clinical Cell Analysis (EWGCCA)

The European Working Group on Clinical Cell Analysis (EWGCCA) has, in preparation for a multicentre peripheral blood stem cell clinical trial, developed a single-platform flow cytometric protocol for the enumeration of CD34+ stem cells. Using this protocol, stabilized blood and targeted training, the EWGCCA have attempted to standardize CD34+ stem cell enumeration across 24 clinical sites. Results were directly compared with participants in the UK National External Quality Assessment Scheme (NEQAS) for CD34+ Stem Cell Quantification that analysed the same specimens using non-standardized methods. Two bead-counting systems, Flow-Count and TruCount, were also evaluated by the EWGCCA participants during trials 2 and 3. Using Flow-Count, the intralaboratory coefficient of variation (CV) was </= 5% in 39% of the laboratories (trial 1), increasing to 65% by trial 3. Interlaboratory variation was reduced from 23.3% (trial 1) to 10.8% in trial 3. In trial 2, 70% of laboratories achieved an intralaboratory CV </= 5% using TruCount, increasing to 74% for trial 3; the interlaboratory CV was reduced from 23.4% to 9.5%. Comparative analysis of the EWGCCA and the UK NEQAS cohorts revealed that EWGCCA laboratories, using the standardized approach, had lower interlaboratory variation. Thus, the use of a common standardized protocol and targeted training significantly reduced intra- and interlaboratory CD34+ cell count variation.

Comparison of single and dual-platform assay formats for CD34+ haematopoietic progenitor cell enumeration

Most techniques for CD34+ cell enumeration are dual platform assays. That is, they derive absolute numbers of CD34+ cells from either the flow cytometrically assessed per cent (%) CD34+ cells within the nucleated cells and/or the white blood cell count from a haematology cell analyser. Recently, so-called single-platform assays have been developed, in which the absolute number of CD34+ cells is directly derived from a single flow cytometric measurement. The present study aims to compare the variation between eight laboratories in CD34+ cell counts from paired assays of 15 samples using a common single (ProCOUNT) and the local dual-platform method. Six laboratories used the 'SIHON' and two the 'ISHAGE' protocol for CD34+ cell enumeration. Use of the single-platform method reduced the inter-laboratory variation in per cent and absolute numbers of CD34+ cells, as measured by interquartile ranges, by half but did not lead to an appreciable reduction of the inter-laboratory variation in white blood cell counts. Thus, part of the reduced inter-laboratory variation obtained with ProCOUNT may have been a result of the use of standardized procedures and reagents to detect CD34+ cells. In order to eliminate any variation arising from the use of different local protocols for percentage of CD34+ cell assessments, a comparison was made of the ProCOUNT-derived absolute CD34+ cell numbers (i.e. single platform) with the dual-platform absolute CD34+ cell numbers calculated by multiplying ProCOUNT-derived percentage of CD34+ cells and with the corresponding haematology analyser-derived white blood cell count. Regardless, the interquartile ranges of absolute CD34+ cell numbers remained almost a factor of two smaller with the use of the single platform method. Thus, these results suggest that single-platform methodology can reduce the variation in absolute CD34+ cell numbers between laboratories.

Detection of muscarinic receptors in the human lung using PET

The characterization of pulmonary muscarinic receptors with PET is still in its infancy. Because approximately 70% of the lungs consists of air and pulmonary muscarinic receptor densities are low, ligands with high receptor affinity are required to obtain reasonable signal-to-noise ratios on PET images. Therefore, the potent 11C-labeled muscarinic antagonist N-methyl-piperidin-4-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate methiodide ([R]-VC-002) was developed. We administered this radioligand to four healthy human volunteers to examine its suitability for studying pulmonary muscarinic receptors in vivo.

METHODS

[11C]VC-002 (185 MBq, specific activity > 7.4 TBq/mmol) was intravenously injected on 2 separate days, with an interval of at least 1 wk. On the first day the volunteers were not pretreated, but on the second day they received the anticholinergic glycopyrronium bromide (Robinul; 2 x 0.1 mg intravenous) 25 and 30 min before the injection of the radiopharmaceutical. C[15O]O scans (approximately 740 MBq [20 mCi] by inhalation) were acquired before the receptor scan to calculate pulmonary blood volume.

RESULTS

On PET images of the thorax, the lungs were clearly visible. After the volunteer was pretreated with glycopyrronium bromide, pulmonary uptake of the radioligand was reduced to 32%+/-12% of the control value at 60 min postinjection and the lungs could no longer be seen. (R)-[11C]-VC-002 was rapidly cleared from plasma and was slowly metabolized during the time course (60 min) of the PET scan. The fraction of radioligand representing parent compound decreased from 99.9% at the time of injection to 82% at 40-60 min postinjection, both in the presence and absence of Robinul. Pulmonary tissue-to-plasma ratios, calculated on a count-per-minute-per-gram basis, reached a plateau value of 17.8+/-1.2 at 40-50 min postinjection.

CONCLUSION

[11C]VC-002 appears to be suitable for in vivo studies of pulmonary cholinoceptors.

Smoking and airway hyperresponsiveness especially in the presence of blood eosinophilia increase the risk to develop respiratory symptoms: a 25-year follow-up study in the general adult population

Airway hyperresponsiveness (AHR) constitutes a risk for development of respiratory symptoms. We assessed whether blood eosinophilia (>/= 275 eosinophils/microliters), skin test positivity (sum score >/= 3) and cigarette smoking (never, ex-smoker, 1-14 cig/d, 15-24 cig/d, >/= 25 cig/d) at the first of two successive surveys are related to the development of respiratory symptoms (chronic cough or phlegm, bronchitis, persistent wheeze, dyspnea, and asthma) at the second survey, and whether these relations are the same in subjects with (PC10 </= 8 mg/ml histamine) and without AHR. We analyzed data of the longitudinal Vlagtwedde-Vlaardingen Study (1965 to 1990) using logistic regression analyses with paired observations, taking multiple measurements within a person into account. In total, 995 men and 792 women contributed 4,403 paired observations. Eosinophilia in hyperresponsive subjects significantly increased the risk to develop one or more respiratory symptoms (odds ratio [OR] = 3.67, 95% confidence interval [CI] = 1.79 to 7.52), wheeze (OR = 5. 06, 95% CI = 2.11 to 12.13), and dyspnea (OR = 2.73, 95% CI = 1.13 to 6.60), independent of smoking, age, sex, area of residence, and time between two successive surveys. Smoking at the first of two successive surveys increased the risk to develop symptoms in a dose-dependent relation. Subjects with positive skin tests in the past were less likely to develop one or more respiratory symptoms (OR = 0.64, 95% CI = 0.46 to 0.88) and chronic phlegm (OR = 0.65, 95% CI = 0.42 to 1.00), independent of AHR. This longitudinal study in the general adult population shows that cigarette smoking and hyperresponsive subjects are at increased risk to develop respiratory symptoms, and especially so when eosinophilia is present in hyperresponsive persons.

The relationship of skin test positivity, high serum total IgE levels, and peripheral blood eosinophilia to symptomatic and asymptomatic airway hyperresponsiveness

The relationships of skin test positivity, high serum total IgE levels (> 100 kU/L), and peripheral blood eosinophilia (>/= 275 cells/microliter) to symptomatic (either chronic cough, chronic phlegm, bronchitis episodes, dyspnea, wheeze, or asthma) and asymptomatic bronchial hyperresponsiveness (BHR) were studied cross-sectionally in 620 adult subjects who participated in the Vlagtwedde-Vlaardingen Study of 1989 and 1990. Eosinophilia (OR = 2.06, 95% CI = 1.28 to 3.31) and skin test positivity (OR = 1.66, 95% CI = 1.02 to 2.71) were both significantly associated with BHR independent of age, sex, smoking, and urban area of residence. High serum total IgE levels were not associated with BHR (OR = 1.29, 95% CI = 0.81 to 2.03). Separate analyses for symptomatic and asymptomatic subjects showed that the higher risk of BHR with skin test positivity applied only to symptomatic subjects (OR = 5.78, 95% CI = 1.63 to 20.51), independent of eosinophilia and high serum total IgE levels. The higher risk of BHR with eosinophilia was not different between symptomatic and asymptomatic subjects, and independent of skin test positivity and high serum total IgE levels. The results of this study show that, in the general adult population, eosinophilia is associated with BHR both in symptomatic and asymptomatic persons, whereas skin test positivity is associated with BHR only in symptomatic subjects.

Vascular adhesion molecules in nocturnal asthma: a possible role for VCAM-1 in ongoing airway wall inflammation

BACKGROUND

Increased airway inflammation at night is thought to be one of the underlying mechanisms in nocturnal asthma. Vascular adhesion molecules may be important for the recruitment of inflammatory cells in the process of asthmatic airway inflammation.

OBJECTIVE

To determine the possible role of vascular adhesion molecules in increased airway inflammation at night in subjects with nocturnal asthma.

METHODS

Bronchial biopsies were obtained at 16.00 h and 04.00 h from 13 healthy controls, 15 asthmatic patients with PEF variation < or = 15% and 10 asthmatic patients with PEF variation > 15%. Biopsies were snap-frozen and double-immunostained for CD31 in combination with P-selectin, E-selectin, ICAM-1 or VCAM-1.

RESULTS

No significant day-night differences in expression of adhesion molecules were found in any of the three groups. The percentage of VCAM-1 positive vessels in biopsies of asthmatic patients was higher than in biopsies of healthy controls: 5.8 vs 2.5% (P < 0.05) at 16.00h and 11 vs 0% (P<0.05) at 04.00 h. In asthma, VCAM-1 expression was correlated with the number of EG2 positive cells: at 16.00 h (rho = 0.57, P < 0.01) as well as at 04.00 h (rho = 0.64, P< 0.01). Moreover, VCAM-1 expression was correlated with the number of CD25 positive cells at 16.00 h (rho = 0.43, P < 0.05) and at 04.00 h (rho = 0.41, P < 0.05).

CONCLUSION

Increased nocturnal airway obstruction in asthma is not associated with an increased nocturnal expression of vascular E-selectin, P-selectin, ICAM-1 or VCAM-1. The relationship between vascular VCAM-1 expression and sub-mucosal EG2 and CD25 positive cells, both at 16.00 h and 04.00 h, suggests a role for VCAM-1 in the ongoing airway wall inflammation of asthma.

Characterisation of beta2-adrenoceptors, using the agonist [11C]formoterol and positron emission tomography

The agonist radioligand N-[2-hydroxy-5-[1-hydroxy-2-[[2-(4-[11C]-methoxyphenyl)-1-methylethyl]am ino]ethyl]phenyl]formamide ([11C]formoterol) was synthesised in order to test its ability to visualise pulmonary beta2-adrenoceptors in vivo, with positron emission tomography (PET). Formoterol was labelled via reaction of a dibenzyl-protected precursor with [11C]CH3I. Subsequent deprotection with Pd/C and H2 yielded [11C]formoterol in 5-15% (corrected for decay) and the specific activity ranged from 5.5-22.2 TBq mmol (150-600 Ci mmol(-1)), 60-70 min after end of bombardment. Biodistribution studies with [11C]formoterol were performed in male Wistar rats which were either untreated or predosed with (D,L)-propranolol hydrochloride (2.5 mg kg(-1), beta-adrenoceptor antagonist), erythro-DL-1-(7-methylindan-4-yloxy)-3-isopropylaminobuta n-2-ol hydrochloride (ICI 118551, 0.15 mg kg(-1), beta2-adrenoceptor antagonist), isoprenaline (15 mg kg(-1), non-subtype selective beta-adrenoceptor agonist) or (+/-)-(2-hydroxy-5-[2-((2-hydroxy-3-(4-((1-methyl-4-trifluoromethyl)1H-i midazol-2-yl-)phenoxy)propyl)amino)ethoxy]benzamide)monomethane sulfonate (CGP 20712A, 0.15 mg kg(-1), beta1-adrenoceptor antagonist). Lungs, heart, liver and plasma were analysed for radioactive metabolites. The kinetics of [11C]formoterol in the lungs of male Wistar rats were investigated by means of a dynamic PET study. The biodistribution studies showed significant specific binding in tissues known to contain beta2-adrenoceptors (lungs, spleen, and heart). Binding in these organs was blocked by ICI 118551 and isoprenaline, but not by CGP 20712A. [11C]Formoterol was rapidly metabolised in rats but lungs and heart did not substantially take up the labelled metabolites. The binding of [11C]formoterol in various tissues of rats is consistent with the beta2-selectivity of formoterol. Whether [11C]formoterol selectively binds to the high affinity state of beta2-adrenoceptors remains to be elucidated. [11C]Formoterol is potentially useful for studying beta2-adrenoceptors with PET and this radioligand may provide new insights in the mechanisms underlying prolonged sympathomimetic action.

Increased peak expiratory flow variation in asthma: severe persistent increase but not nocturnal worsening of airway inflammation

Asthma at night is characterized by a nocturnal increase in airway obstruction. It has been hypothesized that nocturnal asthma results from an increase in airway wall inflammation at night. However, studies on inflammatory cells in bronchoalveolar lavage (BAL) fluid and bronchial biopsies have produced conflicting data. This study assessed inflammatory cell numbers at 16:00 h and 04:00 h in bronchial biopsies of 13 healthy controls, 15 asthmatic patients with peak expiratory flow (PEF) variation < or =15% and 10 asthmatic patients with PEF variation >15%. There was no significant increase at night in the number of CD3, CD4, CD8, CD25, AAI (tryptase) and EG2-immunopositive cells in the submucosa in both groups. Numbers of EG2-positive cells in the two asthmatic groups were significantly higher than in healthy controls, both at 16:00 h (p<0.05) and 04:00 h (p<0.01). The number of EG2, CD4 and CD25-positive cells at 04:00 and 16:00 h tended to be higher in asthmatics with a PEF variation >15% than in asthmatics with PEF variation < or =15%. At 04:00 h the median numbers of EG2-positive cells (per mm basement membrane) in subjects with PEF variation >15% and < or =15% were 6 and 3 cells, respectively, and at 16:00 h 4 and 25 cells respectively. Increased nocturnal airway obstruction is not associated with increased numbers of inflammatory cells in the bronchial submucosa at night. Apparently, asthmatic patients with a peak expiratory flow variation >15% suffer from a higher overall severity of bronchial inflammation at night and during the day.

Submucosa 1.0 x 0.1 mm in size is sufficient to count inflammatory cell numbers in human airway biopsy specimens

Counting of inflammatory cells in human airway biopsy specimens is difficult because immunopositive cells are present in varying density in lung tissue. The goal of our study was to assess the minimal amount of tissue that is necessary for the counting of constant cell numbers. In bronchial biopsy specimens from 5 healthy controls and 5 patients with asthma, we evaluated 20 successive areas of submucosa 0.1 x 0.1 mm in size. We recorded positive and negative changes of more than 10% in the counted numbers of CD4-, CD8-, and EG2-positive cells. We demonstrated that tissue 1.0 x 0.1 mm in size, along 1-mm basement membrane, is sufficient to obtain constant cell numbers.

Techniques in human airway inflammation: quantity and morphology of bronchial biopsy specimens taken by forceps of three sizes

BACKGROUND

In recent years, fiberoptic bronchoscopy has been introduced successfully in the research of bronchial asthma. Bronchial biopsy specimens obtained by this procedure are small, and an optimal biopsy technique is necessary to obtain high-quality tissue samples, as sufficient length of intact basement membrane and sufficient depth of submucosal tissue are required.

METHODS

We compared size and qualitative aspects of bronchial biopsy specimens from nonasthmatic subjects, obtained by forceps of three different sizes, types FB-19C, FB-21C, and FB-35C (Olympus; Tokyo, Japan).

RESULTS AND CONCLUSIONS

We conclude from this study that the hypothesis that the bigger the biopsy forceps, the larger the biopsy specimen and the better the quality of the tissue does not hold. Bronchial biopsy specimens obtained with forceps type FB-35C and FB-21C were equal in size, but the FB-35C biopsy specimens showed more damage and crush artifacts, whereas biopsy specimens obtained with forceps type FB-21C had more intact basement membrane, more submucosal depth, and well-preserved morphology.

Techniques in human airway inflammation: differences in plastic-embedded and snap-frozen sections for CD3, CD4, and CD8 immunostaining of bronchial biopsy specimens

Today, the quantification of inflammatory cells in human airway biopsies might be facilitated by better morphologic resolution provided by special resin (plastic)-embedding techniques. The present study compares the numbers of CD3-, CD4-, and CD8-positive cells in glycolmethacrylate-embedded versus snap-frozen biopsy specimens of normal bronchial mucosa in 10 patients with various pulmonary diseases. In general, larger numbers of CD3-, CD4-, and CD8-positive cells were counted in snap-frozen specimens than in plastic-embedded ones. Loss of antigenic properties during storage of plastic-embedded tissue (blocks) might have contributed to the weak correlation between both methods. An additional study showed that the number of CD3-, CD4-, and CD8-positive cells decreased significantly within a few months after embedding in glycolmethacrylate. Therefore, we recommend processing glycolmethacrylate-embedded specimens as soon as possible. For standard evaluation of established inflammatory cell parameters such as CD3, CD4, CD8, and EG2, frozen tissue is preferable because of the ease of the method and its reliable cell counting. Because glycolmethacrylate-embedded tissue shows superior morphologic resolution, under strict rules, this method seems attractive for the study, in particular, of cell-cell and cell-matrix relationships.

Analysis of variation in results of flow cytometric lymphocyte immunophenotyping in a multicenter study

Fifty-five laboratories participated in a send-out study of four peripheral blood samples comparing a standard protocol vs. local protocols for flow cytometric lymphocyte immunophenotyping. The standard protocol included centrally provided reagents, instrument setup using triple-fluorescent microbeads and a three-color, whole-blood immunostaining technique based on fluorescein isothiocyanate and phycoerythrin-labeled monoclonal antibodies, erythrocyte lysis, washing, fixation, and identification of nucleated cells by the DNA/RNA stain LDS-751. Data analysis guidelines included lymphocyte selection using CD45,CD14-assisted "backgating" on forward (FSC) and sideward (SSC) light scatter and placement of fluorescence (FL) markers on the basis of the isotype control staining. Most (i.e., 77%) of the variation in results of percentage lymphocyte subset assessments using the standard protocol was explained by laboratory, sample, background FL, and the interaction between laboratory and sample. Purity and completeness of the FSC,SSC lymphogate, background FL, flow cytometer type, and flow cytometer setup (which were either partly or entirely determined by laboratory) contributed significantly to the variation. The effect of the leukocyte differential count on the variation in absolute numbers of lymphocyte subsets was particularly large in lymphopenic samples. The use of this standard protocol vs. local protocols did not reduce the interlaboratory variation. Instrument incompatibility with the standard protocol (e.g., incompatible filter combinations for LDS-751 detection) and lack of experience of many participants with three-color flow cytometry (in particular with the use of LDS-751) may have contributed to that result. We suggest that training and experience in a universally applicable standard protocol are critical for minimization of interlaboratory variation in flow cytometric immunophenotyping.

Analysis of variation in results of CD34+ hematopoietic progenitor cell enumeration in a multicenter study

A workshop was held in The Netherlands and Belgium with the aim of investigating whether or not the use of a standard protocol vs. local protocols for flow cytometric enumeration of CD34+ hematopoietic progenitor cells would reduce interlaboratory variation. The standard protocol consisted of a three-color, whole-blood staining technique based on fluorescein isothiocyanate (FITC)-labeled CD34, and phycoerythrin (PE)-labeled CD14 and CD66e monoclonal antibodies (reactive with monocytic and myeloid cells, respectively), followed by erythrocyte lysis, washing, fixation, and selection of nucleated cells during data acquisition on the basis of their positivity for LDS-751 (staining DNA and RNA). Data analysis guidelines included the elimination of nonspecific antibody binding by monocytes and myeloid cells by gating on the CD14-, 66e- cells, followed by setting a window on a CD34 vs. sideward light scatter (SSC) plot around the CD34+, SSClow cells. The FITC-labeled isotype control was analyzed with the same gate and window settings, and the false-positive events were subtracted from CD34 result. Four samples (i.e., peripheral blood and apheresis product from two patients) were sent out. Results were received on patient 1 (2) from 36 (38) laboratories. Data obtained by 24 (26) laboratories after correct application of the standard protocol revealed that the median percentage of CD34+ cells of the four samples ranged between 1.1% and 3.7% and the CVs between 18% and 30%. Incorrect performance of the standard protocol by 12 laboratories, mainly resulting from gating errors, yielded a larger variation (CVs ranging between 50% and 82%). CD34 enumeration using local protocols by 29 (34) laboratories yielded median percentage of CD34+ cells ranging between 1.2% and 3.9% and CVs ranging between 34% and 106%. We conclude that correct application of this standard protocol was effective in reducing the interlaboratory variation in percentage of CD34+ cells assessments.

Imaging beta-adrenoceptors in the human brain with (S)-1'-[18F]fluorocarazolol

We evaluated the suitability of fluorocarazolol for in vivo studies of cerebral beta-adrenoceptors because (S)-1'-[18F]fluorocarazolol has a higher affinity to beta-adrenoceptors than to serotonergic receptors (pKi beta 1 9.4, beta 2 10.0, 5HT1A 7.4, 5HT1B 8.1) and rapidly crosses the blood-brain barrier.

METHODS

The (S)-[18F]fluorocarazolol (74 MBq, > 37 TBq/mmol) was intravenously administered to healthy volunteers on two separate occasions with an interval of at least 1 wk. The initial injection was without pretreatment, but before the second injection, the volunteers received the beta blocker (+/-)-pindolol (3 x 5 mg orally, during 18 hr). The brain was studied with a PET camera in dynamic mode.

RESULTS

Uptake of radioactivity delineated gray matter and was particularly high in the posterior cingulate, precuneus and striatum. Low uptake occurred in the thalamus, whereas the lowest uptake was observed in the white matter of the corpus callosum. After pindolol pretreatment, uptake was reduced and its distribution became homogeneous throughout the brain. The ratio of total-to-nonspecific binding was about 2 at 60 min, increasing to 2.5-2.75 at longer intervals.

CONCLUSION

Fluorocarazolol is the first radioligand that can visualize cerebral beta-adrenoceptors and may enable monitoring of these binding sites during disease.

Reduction of interlaboratory variability in flow cytometric immunophenotyping by standardization of instrument set-up and calibration, and standard list mode data analysis

Two workshops addressed the question to which degree standardization of instrument set-up and calibration, and standard list mode data analysis would reduce interlaboratory variability of flow cytometric results on prestained peripheral blood mononuclear cells (PBMC). Standard instrument set-up included uniform positioning of the "windows of analysis" for the forward and sideward light scatter and fluorescence (FL) 1 (i.e., fluorescein isothiocyanate [FITC]) and 2 (i.e., phycoerythrin [PE]) parameters. Reference standards and PBMC, double-stained with FITC- and PE-conjugated monoclonal antibodies covering a wide range of FL intensities and coexpression patterns, were sent out to 25 laboratories in Workshop 1 and to 35 laboratories in Workshop 2 with the following requests: a) to set up instruments according to local and standard protocols, b) to acquire list mode data on the PBMC with both instrument settings, and c) to analyze both datasets according to local protocols. Standard analysis of the list mode data acquired with uniform instrument settings was performed centrally using so-called "latent class model" software (Van Putten et al., Cytometry 14:86-96, 1993). This software provides an automated, "no-gating" analytical method of lymphocyte immunophenotypes and employs fixed FL marker settings as defined prior to each analytical run. In Workshop 1, these markers were set in identical histogram channels for all instruments based on results obtained with a reference instrument. Standard analysis of list mode data acquired after uniform instrument set-up led only to a 13% reduction of interlaboratory variability of results as compared to data analysis using local protocols. The standard protocol for instrument set-up led to uniform positioning of relatively strong FL signals but variable positioning of unstained cells on the FL histogram scales. Hence, standard FL marker settings were inappropriate for some instruments. Therefore, instrument responses to FITC and PE signals in Workshop 2 were calibrated using microbeads labeled with FITC or PE in a range of predefined FL intensities expressed in MESF units (molecules of equivalent soluble fluorochrome). That approach allowed the positioning of the FL markers for the standard analysis on the basis of identical FL1 and FL2 intensities, expressed in MESF units, for all instruments. Standard analysis of list mode data acquired after uniform instrument set-up and calibrated FL marker settings led to a 43% reduction of interlaboratory variability as compared to data analysis to local protocols. We conclude that standard list mode data analysis using fixed FL marker settings reduces the interlaboratory variability of flow cytometric results on prestained PBMC, provided that the instruments have been set up in a uniform way and that FL markers have been standardized on the basis of calibration of each instrument's response to the corresponding FL signals.

Characterization of pulmonary and myocardial beta-adrenoceptors with S-1'-[fluorine-18]fluorocarazolol

S-1'-[18F]fluorocarazolol was administered to healthy volunteers to assess its potential for noninvasive measurement of regional pulmonary and myocardial beta-adrenoceptor densities.

METHODS

High-specific activity fluorocarazolol was intravenously injected on two separate occasions within a 1-wk interval. The initial injection was without pretreatment, but before the second injection, the volunteers either inhaled salbutamol (2 x 200 micrograms aerosol) or they ingested pindolol (3 x 5 mg during a 12-hr interval). Twenty-eight PET time frames of 31 planes were acquired over a period of 60 min after each injection. Blood samples were drawn and analyzed for the presence of fluorocarazolol and radioactive metabolites.

RESULTS

Uptake of fluorocarazolol in the target tissues was hardly affected by salbutamol but was strongly depressed by pindolol. Pulmonary and myocardial tissue-to-plasma concentration ratios of fluorocarazolol reached plateau values of 11.6 +/- 0.6 (lungs) and 18.1 +/- 1.0 (heart) at 45-50 min postinjection. These values were reduced to 2.0 +/- 0.4 and 2.0 +/- 0.6 after treatment with pindolol.

CONCLUSION

These data indicate that: 1. Pulmonary and myocardial uptake of radioactivity after intravenous administration of S-1'-[18F]fluorocarazolol represents radioligand binding to beta-adrenoceptors. 2. Pulmonary binding occurs mainly in alveoli rather than in airway smooth muscle under these conditions. 3. Binding kinetics do not preclude quantification of receptors with compartment models.

Stereoselective synthesis and biodistribution of potent [11C]-labeled antagonists for positron emission tomography imaging of muscarinic receptors in the airways

Quantitation of muscarinic receptors in the lungs in vivo with positron emission tomography (PET) is of clinical interest. For that purpose we decided to develop [11C]-labeled ligands with a high affinity (KD < 0.1 nM). Three quaternary muscarinic antagonists, racemic N-methylpiperidin-4-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate methiodide 1a (pKB = 10.39), its (R)-isomer 1b (pKB = 11.08), and (R,R)-quinuclidin-3-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate methiodide 2 (pKB = 11.28), were labeled by reacting [11C]CH3I with their tertiary amine precursors. The enantiomerically pure tertiary amine precursors were prepared by stereoselective synthesis starting from (R)-(-)-mandelic acid. In vitro binding assay of 1b and 2 demonstrated that both ligands bind with very high affinity to the muscarinic receptor subtypes M1, M2, and M3. They are more potent than the muscarinic antagonist (R)-N-methylquinuclidinyl benzilate ((R)-MQNB). Distribution studies with 1a, 1b, and 2 in control and atropine-treated male Wistar rats demonstrated significant specific binding (90-99% of total issue uptake) in tissues containing cholinoceptors (heart, intestine, lung, pancreas, spleen, stomach, submandibular gland). Because the tissue/plasma concentration ratios of 1b are most favorable, this ligand was used for further evaluation. Analysis of plasma samples showed a very rapid clearance (t1/2 = 0.3 min) of the radioligand 1b and a relatively slow appearance of a hydrophilic metabolite. At 15 min postinjection of 1b, analysis of heart, lungs, and liver showed that respectively 99%, 88%, and 8% of the tissue radioactivity corresponded with the parent compound. Ligand 1b appears to be an excellent candidate for PET studies of mAChR receptors in heart and lungs.

Long-term effects of home rehabilitation on physical performance in chronic obstructive pulmonary disease

A pilot study was set up to assess the long-term effects of once weekly versus once monthly follow-up of pulmonary rehabilitation after a comprehensive home rehabilitation program on physical performance in patients with chronic obstructive pulmonary disease (COPD) during an 18-mo period. Thirty-six patients with a mean FEV1 of 1.3 +/- 0.4 L (43% pred) were included in the study. Groups A and B (n = 23) visited the physical therapist twice weekly for 3 mo. Thereafter, 11 patients (Group A) had a follow-up of pulmonary rehabilitation once a week, and 12 patients (Group B) had a follow-up once a month. Thirteen patients received no rehabilitation at all (Group C). Long-term home rehabilitation does not appear to improve exercise tolerance; however, on the other hand, there is a deterioration in vital capacity (p < 0.01), walking distance (p < 0.01), and maximal work load (p < 0.05), as shown in the control group. A small improvement in exertional dyspnea (p < 0.01) after 18 mo and inspiratory muscle function (p < 0.05) after 12 mo was shown only in Group A. Because of the insufficient number of patients enrolled in this pilot study, no clear benefit on physical performance of long-term home rehabilitation with either weekly or monthly supervision could be demonstrated.