Long-term outcome of patients receiving haematopoietic allogeneic stem cell transplantation as first transplant for high-risk Hodgkin lymphoma: a retrospective analysis from the Lymphoma Working Party-EBMT

We analysed long-term outcome of patients receiving haematopoietic allogeneic stem cell transplantation (allo-HSCT) as a first transplant for high-risk Hodgkin lymphoma (HL). One hundred and ninety patients were included in this study, 63% of them had previously received brentuximab vedotin and/or checkpoint inhibitors. Seventy patients (37%) received an unrelated donor allo-HSCT, 99 (51%) had myeloablative conditioning (MAC) and 60% had in vivo T-cell/depleted grafts (TCD). The 100-day cumulative incidence (CI) of grade II-IV acute graft-versus-host disease (GVHD) was 25% and the 3-year CI of chronic GVHD was 38%. The 3-year CI of non-relapse mortality (NRM) and relapse rate were 21% and 38% respectively. After a median follow-up of 58 months, 3-year overall survival (OS) and progression-free survival (PFS) were 58% and 41% respectively. Multivariate analysis showed that, in comparison to reduced-intensity conditioning regimens with or without TCD, MAC using TCD had similar NRM and a lower risk of relapse leading to significantly better OS and PFS. MAC without TCD was associated with higher NRM and worse survival outcomes. These results suggest that in patients with high-risk HL and candidates of allo-HSCT, a MAC strategy with TCD might be the best option.

Impact of patient: donor HLA disparity on reduced-intensity-conditioned allogeneic stem cell transplants from HLA mismatched unrelated donors for AML: from the ALWP of the EBMT

Patients with acute myeloid leukaemia (AML) who lack a matched sibling or unrelated donor commonly undergo transplantation from a donor matched at 9/10 HLA-A, -B, -C, -DRB1, -DQB1 alleles, and it is unclear if a specific locus mismatch is preferable to any other. We therefore studied 937 patients with AML in complete remission transplanted using a reduced intensity conditioning regimen from an unrelated donor mismatched at a single allele. In a multivariate analysis, patient age, adverse karyotype and patient cytomegalovirus (CMV) seropositivity were correlated with decreased leukaemia free survival (LFS) and overall survival (OS). There was no significant difference in LFS or OS between patients transplanted from donors mismatched at HLA-A, -B, -C or -DRB1 in comparison to a HLA-DQB1 mismatched transplant. In a multivariate analysis, patients transplanted with a HLA-A mismatched donor had higher rates of acute graft-versus-host disease (GVHD) and non-relapse mortality (NRM) than patients transplanted with a HLA-DQB1 mismatched donor. Patient CMV seropositivity was associated with an increase in NRM and acute GVHD and reduced LFS and OS, regardless of donor CMV status. For CMV seropositive patients lacking a fully matched donor, alternative GVHD and CMV prophylaxis strategies should be considered.

Postremission Consolidation by Autologous Hematopoietic Cell Transplantation (HCT) for Acute Myeloid Leukemia in First Complete Remission (CR) and Negative Implications for Subsequent Allogeneic HCT in Second CR: A Study by the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

After autologous hematopoietic cell transplantation (HCT) in the first complete remission (CR1), patients with acute myeloid leukemia (AML) may relapse and undergo allogeneic HCT in the second complete remission (CR2). The aim of this study was to analyze the outcome of allogeneic HCT performed in CR2 comparing patients with prior consolidation by autologous HCT versus patients with chemotherapy consolidation. Included were 2619 adults with allogeneic HCT in CR2 from 2000 to 2017 with (n = 417) or without (n = 2202) prior autologous HCT. Patient groups were not entirely comparable; patients with prior autologous HCT were younger, had less often a favorable cytogenetic profile, had more commonly donors other than matched siblings, and more often received reduced-intensity conditioning. In multivariate analysis, nonrelapse mortality risks in patients with prior autologous HCT were 1.34 (1.07 to 1.67; P = .01) after adjustment for age, cytogenetic risk, transplant year, donor, conditioning intensity, sex matching, interval diagnosis-relapse, and relapse-allogeneic HCT as compared with chemotherapy consolidation. Similarly, risks of events in leukemia-free survival and graft-versus-host disease, relapse-free survival were higher with prior autologous HCT, 1.17 (1.01 to 1.35), P = .03 and 1.18 (1.03 to 1.35), P = .02, respectively. Risk of death was also higher, 1.13 (0.97 to 1.32), P = .1, but this was not significant. Postremission consolidation with autologous HCT for AML in CR1 increases toxicity of subsequent allogeneic HCT in CR2.

Improved health-related quality of life, participation, and autonomy in patients with treatment-resistant chronic pain after an intensive social cognitive intervention with the participation of support partners

Despite the availability of various specific treatments, most patients with chronic pain (CP) consider their pain problem as undertreated. Recently, multiple sclerosis (MS) patients who were given an intensive 3-day social cognitive treatment with the participation of support partners experienced lasting improvements in health-related quality of life (HRQoL) and self-efficacy. In this study, a similar intervention was given to treatment-resistant CP patients with stressors, relational problems with support partner, and distress, anxiety or depression. Before and 1, 3, and 6 months after the intervention, patients completed the Euro-Qol 5 Dimensions 5 Levels (EQ-5D-5L) and Impact on Participation and Autonomy (IPA) questionnaires (primary outcomes), and the Survey Of Pain Attitudes (SOPA), the Four-Dimensional Symptom Questionnaire (4DSQ) (distress, depression, anxiety, and somatization), and Visual Analog Scale for pain intensity, whereas the support partners completed the Caregiver Strain Index (CSI) questionnaire. Differences between baseline and post-treatment were tested via paired t-tests (significance level 0.05). Of the 39 patients who were included, 34 (87.2%) completed the 3-day treatment. At 1, 3, and 6 months, improvements were seen in EQ-5D-5L-Index (+40.6%; +22.4%; +31.7%), Health Today (+61.8%; +36.3%; +46.8%), Control attitude (+45.8%; not significant [NS]; +55.0%) and decreases in IPA-Problems (−14.8%; NS; −20.4%), Harm attitude (−18.9%; −15.0%; −17.7%), Distress (−17.7%; −31.8%; −37.1%), and Depression (−37.4%; −31.4%; −35.7%) scores. The CSI score had decreased by −29.0%, −21.4%, and −25.9%, respectively. In conclusion, after an intensive 3-day social cognitive intervention, treatment-resistant CP patients experienced substantial and lasting improvements in HRQoL and in problematic limitations to participation and autonomy, in association with improvements in pain attitudes, depression, and distress. To assess whether this innovative approach may be an effective treatment for this subgroup of CP patients, future randomized controlled studies are needed.

In patients older than 55 years with AML in first CR, should we search for a matched unrelated donor when an old sibling donor is available?

Allogeneic hematopoietic transplantation is increasingly used in patients aged 55 years or more with AML. The question of whether outcomes can be improved with an allele-level 8/8 HLA-matched unrelated donor (MUD) rather than an older HLA-matched sibling (MSD, more than 55 years) is still unanswered. We thus analyzed outcomes in 714 patients aged 55 years and older with AML in first CR (CR1) who received PBSCs after a reduced-intensity conditioning hematopoietic cell transplant from a MUD (n=310) or a MSD (n=404) in a recent period (2005-2010). The 3-year cumulative incidences (CIs) of non-relapse mortality were 17% and 23% with MSD and MUD, respectively (P=0.17). The 3-year CIs of relapse were 37% and 30%, respectively (P=0.12), resulting in a 3-year CI of leukemia-free survival of 46% and 47%, respectively (P=0.51). The 3-year overall survival was 49% with both MSD and MUD. In conclusion, HLA-identical sibling donors aged 55 years or more should not be excluded because of age for patients aged 55 years and older with AML in CR1.

Intense T cell depletion followed by autologous bone marrow transplantation for severe multiple sclerosis

BACKGROUND

Certain stem cell transplantation procedures might slow down inflammatory pathology in multiple sclerosis (MS).

AIMS

To halt disease progression in aggressive MS by a bone marrow transplantation (BMT) protocol aimed at maximum T cell suppression.

METHODS

Autologous BMT was performed in 14 patients with rapid secondary progressive MS (median EDSS score at baseline, 6; median disease duration, five years). To accomplish rigorous T cell ablation, a strong conditioning protocol was chosen--cyclophosphamide, total body irradiation, and antithymocyte globulin. To minimise the possibility of reinfusing mature T cells in the graft, bone marrow, not peripheral blood, was used as the CD34+ stem cell source.

RESULTS

Median follow up was 36 months (range, 7-36). Post-transplant haemopoietic recovery was successful in all patients. Early toxicity included Epstein-Barr virus related post-transplantation lymphoproliferative disorder. Longterm effects were development of antithyroid antibodies (three) and myelodysplastic syndrome (one). One patient died of progressive disease five years after transplantation. Treatment failure, defined by EDSS increase sustained for six months or more, was seen in nine patients and stabilisation or improvement in five. Other clinical parameters generally showed the same outcome. No gadolinium enhanced lesions were seen on post-treatment magnetic resonance imaging, in either cerebral or spinal cord scans. However, cerebrospinal fluid oligoclonal bands remained positive in most cases.

CONCLUSIONS

This strong immunosuppressive regimen did not prevent clinical progression in patients with aggressive secondary MS. The lack of efficacy, together with some serious side effects, does not favour the use of similar rigorous T cell depleting protocols in the future.

Isolated HLA-C mismatches in unrelated donor transplantation for CML

HLA-incompatibility is a major factor associated with outcome of allogeneic stem cell transplantation, but little is known on the impact of isolated HLA-C mismatches. We analyzed the outcome of 114 CML patients transplanted with marrow from unrelated donors of whom 24 were mismatched for HLA-C only (9/10 match). Univariate estimates of 5-year survival (SRV) (median follow-up: 47 months) in the HLA-matched group were 68+/-12 vs 42+/-20% (P=0.03) for the patients mismatched for HLA-C only and 33+/-33% in the mismatched group (non-HLA-C single mismatches and multiple mismatches) (P=0.0004). Disease stage, GVHD-prophylaxis (T-cell depletion), CMV-status and HLA-incompatibility were the risk factors associated (all P< or =0.005) with poor outcome. In the multivariate analysis, patients mismatched for loci other than HLA-C were at high risk of an adverse outcome (death: RR, 2.9; CI, 1.6-5.4, P=0.008, transplant-related mortality (TRM): RR, 3; CI, 1.5-5.9, P=0.0015). For patients mismatched for HLA-C only, the increased risk was of borderline significance (death: RR, 1.9; CI, 1-3.9, P=0.06, TRM: RR, 2.1; CI, 1-4.5, P=0.07). In spite of their lower expression, HLA-C antigens still represent relevant transplantation barriers that should be considered when searching for an unrelated donor.

The impact of donor gender on outcome of allogeneic hematopoietic stem cell transplantation for multiple myeloma: reduced relapse risk in female to male transplants

The impact of the donor gender on outcome in HLA-identical sibling donor hematopoietic stem cell transplantation for multiple myeloma was studied in a retrospective registry study of 1312 patients (476 male to male (M --> M); 334 female to male (F --> M); 258 male to female (M --> F); 244 female to female (F --> F) reported to the European Group for Blood and Marrow Transplantation (EBMT). The best overall survival (OS) from the time of transplantation was found in F --> F (median 41 months) with no significant difference between other groups (median 25 months in M --> M, 18 months in F --> M, 19 months in M --> F) despite a significantly higher nonrelapse mortality in F --> M. This was due to a significantly lower relapse rate (REL) in F --> M compared to all other groups. Before 1994, OS was poorer in F --> M than in M --> M, which improved to similarity from 1994 onwards (median 29 months in M --> M and 25 months in F --> M). The reduced REL contributed to this improvement in F --> M indicting a gender-specific graft vs myeloma effect. Therefore, a female donor is as good as a male one for male patients, while for female patients gender disparity is a negative factor for outcome.

Progress in allogeneic bone marrow and peripheral blood stem cell transplantation for multiple myeloma: a comparison between transplants performed 1983-93 and 1994-98 at European Group for Blood and Marrow Transplantation centres

Out of 690 allogeneic matched sibling donor transplants for multiple myeloma reported to the European Group for Blood and Marrow Transplantation (EBMT) registry, 334 were performed during the period 1983-93 (all with bone marrow) and 356 during 1994-98 [223 with bone marrow and 133 with peripheral blood stem cells (PBSCs)]. The median overall survival was 10 months for patients transplanted during the earlier time period and 50 months for patients transplanted with hone marrow during the later period. The use of PBSCs was associated with earlier engraftment but no significant survival benefit compared to bone marrow transplants during the same time period. The improvement in survival since 1994 with the result of a significant reduction in transplant-related mortality, which was 38%, 21% and 25% at 6 months and 46%, 30% and 37% at 2 years during the earlier period, and the later period with bone marrow and PBSCs respectively. Reasons for the reduced transplant-related mortality appeared to be fewer deaths owing to bacterial and fungal infections and interstitial pneumonitis, in turn a result of earlier transplantation and less prior chemotherapy. Better supportive treatment and more frequent use of cytokines may also play a role. The improvement in survival was not directly related to the increased use of PBSCs.

An EBMT registry matched study of allogeneic stem cell transplants for lymphoma: allogeneic transplantation is associated with a lower relapse rate but a higher procedure-related mortality rate than autologous transplantation

The role of allogeneic bone marrow transplantation in lymphoma remains uncertain. We have analyzed 1185 allogeneic transplants for lymphoma reported to the EBMT registry between 1982 and 1998 and compared the results with those of 14687 autologous procedures performed over the same period. Patients receiving allogeneic transplants were subdivided according to histology: low-grade non-Hodgkin's lymphoma (NHL) 231 patients; intermediate-grade NHL 147 patients; high-grade NHL 255 patients; lymphoblastic NHL 314 patients; Burkitt's lymphoma 71 patients; and Hodgkin's disease 167 patients. These patients received allogeneic transplants as their first transplant procedure. Actuarial overall survival (OS) at 4 years from transplantation was: low-grade NHL 51.1%; intermediate-grade NHL 38.3%; high-grade NHL 41.2%; lymphoblastic lymphoma 42.0% years; Burkitt's lymphoma 37.1%; and Hodgkin's disease 24.7% years. These outcomes are relatively poor because of the high procedure-related mortality associated with these procedures, particularly in patients with Hodgkin's disease (51.7% actuarial procedure-related mortality at 4 years). Multivariate analysis showed that for all lymphomas apart from Hodgkin's disease, status at transplantation significantly affected outcome. A matched analysis was performed: for all categories of lymphoma, OS was better for autologous than for allogeneic transplantation. Relapse rate was better in the allogeneic group for low-, intermediate- and high-grade, and lymphoblastic NHL. It was equivalent for Burkitt's lymphoma and worse in the allogeneic group for Hodgkin's disease. Allogeneic transplantation appears to be superior to autologous procedures in terms of producing a lower relapse rate. The toxicity of allogeneic procedures must however be reduced before this translates into an improvement in OS.

Plasma concentration of ropivacaine after intercostal blocks for video-assisted thoracic surgery

BACKGROUND

Absorption of local anaesthetics following intercostal blocks is rapid. Therefore, plasma concentrations of ropivacaine during intercostal blocks with ropivacaine 2, 5, 7.5 and 10 mg ml-1 (ropivacaine 5 ml injected into each of four intercostal spaces) in patients undergoing video-assisted thoracic surgery were determined.

METHODS

After informed consent and ethics committee approval, 64 patients were randomly allocated to four groups for intercostal nerve block (ropivacaine 2, 5, 7.5 or 10 mg ml-1 at the end of surgery). Central (mixed) venous and arterial plasma samples were collected before the start of intercostal application, and 2, 5, 10, 15, 20, 30, 45, 60 and 90 min afterwards. Plasma concentrations of ropivacaine were measured by high performance liquid chromatography.

RESULTS

Maximum venous plasma concentrations occurred after the mean times of 10.7 (range, 5-15), 10.8 (5-20), 11.3 (5-20) and 12.2 (5-45) min, respectively for each group. The groups had mean concentrations of 1.3 (SD, 0.6; range, 0.3-2.3), 2.1 (1.0; 0.5-4.5), 2.4 (1.0; 1.2-5.1) and 2.5 (0.9; 1.7-5.6) micrograms ml-1, respectively. Maximum arterial plasma concentration following 1.0% ropivacaine occurred after 16 (5-45) min with a mean of 2.3 (0.6; 1.5-3.6) micrograms ml-1. No signs of central nervous system or cardiac toxicity were observed.

CONCLUSIONS

After intercostal blocks the absorption of ropivacaine is rapid compared with other techniques for regional anaesthesia and results in relatively high venous and arterial plasma concentrations, especially if a dose of 100 mg or more is used.

[Postoperative pain therapy in minimally invasive direct coronary arterial bypass surgery. I.v. opioid patient-controlled analgesia versus intercostal block]

OBJECTIVE

Lately introduced cardiosurgical procedures such as MIDCAB enable an early extubation immediately after surgery. This also requires an adequate anesthesia regime and especially a sufficient postoperative analgesia. Patient controlled analgesia (PCA) and intercostal nerve blockade (ICB) were evaluated for their suitability for postoperative pain relief in patients undergoing a MIDCAB procedure.

MATERIAL AND METHODS

After approval by the local ethic committee and obtaining written informed consent 43 patients were included in this study. Anesthesia was induced and maintained in a total intravenous standardised manner with propofol, remifentanil, cisatracurium and additionally glyceroltrinitrate, clonidine and esmolol were given as needed. After revascularisation patients were randomly assigned to one of two groups receiving either 7.5 mg piritramid i.v. before extubation and continuing a PCA with 2 mg boli and a 10 min lockout, or an ICB with ropivacaine 1% (4 times 5 ml). Additionally all patients received 1 g paracetamol rectally before induction of anesthesia and 1 g metamizol i.v. at the end of surgery. A rescue medication of 3.75 mg piritramid i.v. was allowed. A pain score (NRS 0-10), the Aldrete score (AS 0-12) and oxygen saturation were obtained 1, 4, and 8 h after extubation.

RESULTS

The ICB group showed a significantly greater pain reduction in the first (5.8 +/- 1.8 vs. 7.3 +/- 1.9; P < 0.02) and fourth h (3.6 +/- 1.3 vs. 4.6 +/- 1.4; P < 0.02), respectively. Transfer to an intermediate care ward one hr after extubation was achieved more often in the ICB group according to the AS (ICB 9.6 +/- 1.5 vs. PCA 8.9 +/- 1.2; P < 0.05), too. There was no difference with respect to the oxygen saturation. The additional piritramid demand was 9.3 mg in the ICP group and 5 mg in the PCA group in the first 8 hours postoperative.

CONCLUSION

ICB gives a better pain relief in the early postoperative phase after MIDCAB procedures compared to a PCA. Both regimes are adequate in order to provide a sufficient pain relief and help to avoid prolonged postoperative mechanical ventilation. These will enable an early transfer of patients to an intermediate care station and save ICU capacity.

Genotypically nonidentical related donors for transplantation of patients with myelodysplastic syndromes: comparison with unrelated donor transplantation and autologous stem cell transplantation

Transplantation with histocompatible identical siblings is a curative treatment for patients with myelodysplastic syndromes (MDS). Alternative treatments, such as transplantation with other family donors, are an option for patients without HLA-identical siblings. This study evaluated transplantation with genotypically nonidentical family donors and compared the results to those obtained with unrelated donors and autologous stem cell transplantation. Overall 3-year survival was 35% for the 79 patients transplanted using genotypically nonidentical donors, DFS was 31%, relapse risk 16%, and the treatment-related mortality (TRM) 62%. Patients transplanted using phenotypically identical family donors had a significantly superior survival and a lower TRM than patients transplanted with mismatched family donors. Age had no influence on the outcome of transplantation. The DFS of patients transplanted in early stage of the disease was 42% compared to 28% in patients transplanted with more advanced disease (P = 0.03). The results of transplantation with mismatched family donors were comparable to those obtained with unrelated donor transplantation. This suggests that nonidentical family donors may be considered if a fully matched unrelated donor is not available. The TRM of patients transplanted with nonidentical family donors is significantly higher than the TRM of patients transplanted with autologous stem cells. The disease-free survival of ASCT is not inferior to allogeneic transplantation using nonidentical family donors, and the intensity of the treatment is much lower. The choice of ASCT or alternative donor transplantation must be influenced by the age of the patient and the risk of relapse. For patients under the age of 20 years the treatment of choice may indeed be an alternative donor transplantation.

Carbon cycling traits of plant species are linked with mycorrhizal strategy

Ecosystem carbon cycling depends strongly on the productivity of plant species and the decomposition rates of the litter they produce. We tested the hypothesis that classifying plant functional types according to mycorrhizal association explains important interspecific variation in plant carbon cycling traits, particularly in those traits that feature in a hypothesized feedback between vegetation productivity and litter turnover. We compared data from standardized 'screening' tests on inherent potential seedling relative growth rate (RGR), foliar nutrient concentrations, and leaf litter decomposability among 83 British plant species of known mycorrhizal type. There was important variation in these parameters between mycorrhizal plant types. Plant species with ericoid mycorrhiza showed consistently low inherent RGR, low foliar N and P concentrations, and poor litter decomposability; plant species with ectomycorrhiza had an intermediate RGR, higher foliar N and P, and intermediate to poor litter decomposability; plant species with arbuscular-mycorrhiza showed comparatively high RGR, high foliar N and P, and fast litter decomposition. Within the woody species subset, differentiation in RGR between mycorrhizal types was mostly confounded with deciduous versus evergreen habit, but the overall differentiation in litter mass loss between mycorrhizal types remained strong within each leaf habit. These results indicate that, within a representative subset of a temperate flora, ericoid and ectomycorrhizal strategies are linked with low and arbuscular-mycorrhizal species with high ecosystem carbon turnover. The incorporation of mycorrhizal association into current functional type classifications is a valuable tool in the assessment of plant-mediated controls on carbon and nutrient cycling.

Rapid emergence of ciprofloxacin-resistant enterobacteriaceae containing multiple gentamicin resistance-associated integrons in a Dutch hospital

In a hematology unit in the Netherlands, the incidence of ciprofloxacin-resistant Enterobacter cloacae and Escherichia coli increased from from 1996 to 1999. Clonal spread of single genotypes of both ciprofloxacin-resistant E. coli and Enterobacter cloacae from patient to patient was documented by pulsed-field gel electrophoresis and random amplification of polymorphic DNA. In addition, genetically heterogeneous strains were isolated regularly. Integrons associated with gentamicin resistance were detected in Enterobacter cloacae and E. coli strains. Integron-containing E. coli were detected in all hematology wards. In contrast, in Enterobacter cloacae strains two integron types were encountered only in the isolates from one ward. Although in all patients identical antibiotic regimens were used for selective decontamination, we documented clear differences with respect to the nosocomial emergence of ciprofloxacin-resistant bacterial strains and gentamicin resistance-associated integrons.

Haematopoietic stem cell transplantation for patients with myelo-dysplastic syndromes and secondary acute myeloid leukaemias: a report on behalf of the Chronic Leukaemia Working Party of the European Group for Blood and Marrow Transplantation (EBMT)

Allogeneic stem cell transplantation from an HLA-identical sibling donor is a curative treatment option for a young patient with myelodysplastic syndrome, limited by age and lack of sibling donors. Alternative stem cell sources have been used more recently, such as unrelated donors, non-identical family members or autologous transplants. This analysis of 1378 transplants reported to the European Group for Blood and Marrow Transplantation (EBMT) addresses the outcome of the varying procedures according to the known risk factors. The estimated disease-free survival (DFS) and estimated relapse risk at 3 years were both 36% for 885 patients transplanted with stem cells from matched siblings. In the multivariate analysis, age and stage of disease had independent prognostic significance for DFS, survival and treatment-related mortality. Patients transplanted at an early stage of disease had a significantly lower risk of relapse than patients transplanted at more advanced stages. The estimated DFS at 3 years was 25% for the 198 patients with voluntary unrelated donors, 28% for the 91 patients with alternative family donors and 33% for the 126 patients autografted in first complete remission. The non-relapse mortality was 58% for patients with unrelated donors, 66% for patients with non-identical family donors and 25% for autografted patients. The relapse rate of 18% was relatively low for patients with non-identical family donors, 41% for patients with unrelated donors and 55% for patients treated with autologous stem cell transplantation. Both allogeneic and autologous stem cell transplantation have emerged as treatment options for patients with myelodysplastic syndromes. Transplantation with an HLA-identical sibling donor is the preferred treatment option. Patients without an HLA-identical sibling donor may be treated with either autologous stem cell transplantation or an alternative donor transplantation. Patients younger than 20 years may be treated with an unrelated donor transplantation. Patients older than 40 years, and probably also patients between 20 and 40 years, may benefit most from an autologous stem cell transplantation.

No impact of high-dose cytarabine on the outcome of patients transplanted for acute myeloblastic leukaemia in first remission. Acute Leukaemia Working Party of the European Group for Blood and Marrow Transplantation (EBMT)

High-dose cytarabine is currently used in combination with anthracycline in the treatment of acute myeloblastic leukaemia (AML). Moreover, high-dose cytarabine has been reported to produce long-term disease-free survival in a proportion of patients, especially in certain subtypes of AML. However, it remains unknown whether the outcome of patients undergoing allogeneic or autologous stem cell transplantation is influenced by previous treatment with high-dose cytarabine. To this end, 1672 patients with AML in first remission who were reported to the Acute Leukaemia Working Party registry of the European Group for Blood and Marrow Transplantation (EBMT) and who were transplanted between 1980 and 1995 were analysed according to the dose intensity of cytarabine given at induction and/or consolidation. Autologous stem cell transplantation (ABMT) was performed in 846 patients and allogeneic bone marrow transplantation (BMT) in 826 patients. This study shows that the dose of cytarabine (Ara-C) given at induction and/or consolidation did not influence the relapse incidence in patients subsequently allografted or autografted. In addition, it did not give any advantage in terms of overall outcome. Therefore, high-dose (HD) Ara-C may not be needed for patients who have a planned stem cell transplantation (SCT) as post-remission therapy. Nevertheless, HD Ara-C may be utilized in certain subtypes of AML that are believed to be curable by chemotherapy alone.

Three differentially expressed survivin cDNA variants encode proteins with distinct antiapoptotic functions

Survivin is a member of the inhibitor of apoptosis protein (IAP) family that is believed to play a role in oncogenesis. To elucidate further its physiologic role(s), we have characterized the murine survivin gene and complementary DNA (cDNA). The structural organization of the survivin gene, located on chromosome 11E2, is similar to that of its human counterpart, both containing 4 exons. Surprisingly, 3 full-length murine survivin cDNA clones were isolated, predicting the existence of 3 distinct survivin proteins. The longest open reading frame, derived from all 4 exons, predicts a 140-amino acid residue protein, survivin(140), similar to human survivin, which contains a single IAP repeat and a COOH-terminal coiled-coil domain that links its function to the cell cycle. A second cDNA, which retains intron 3, predicts the existence of a 121-amino acid protein, survivin(121) that lacks the coiled-coil domain. Removal of exon 2-derived sequences by alternative pre-messenger RNA (mRNA) splicing results in a third 40-amino acid residue protein, survivin(40), lacking the IAP repeat and coiled-coil structure. Predictably, only recombinant survivin(140) and survivin(121) inhibited caspase-3 activity. All 3 mRNA species were variably expressed during development from 7.5 days postcoitum. Of the adult tissues surveyed, thymus and testis accumulated high levels of survivin(140) mRNA, whereas survivin(121)-specific transcripts were detected in all tissues, while those representing survivin(40) were absent. Human counterparts to the 3 survivin mRNA transcripts were identified in a study of human cells and tissues. The presence of distinct isoforms of survivin that are expressed differentially suggests that survivin plays a complex role in regulating apoptosis. (Blood. 2000;95:1435-1442)

Development of a real-time quantitative assay for detection of Epstein-Barr virus

With the use of real-time PCR, we developed and evaluated a rapid, sensitive, specific, and reproducible method for the detection of Epstein-Barr virus (EBV) DNA in plasma samples. This method allowed us to screen plasma and serum samples over a range between 100 and 10(7) copies of DNA per ml using two sample preparation methods based on absorption. A precision study yielded an average coefficient of variation for both methods of less than 12%, with a coefficient of regression for the standard curve of a minimum of 0. 98. We detected EBV DNA in 19.2% of plasma samples from immunosuppressed solid-organ transplant patients without symptoms of EBV infections with a mean load of 440 copies per ml. EBV DNA could be detected in all transplant patients diagnosed with posttransplant lymphoproliferative disorder, with a mean load of 544,570 copies per ml. No EBV DNA could be detected in healthy individuals in nonimmunosuppressed control groups and a mean of 6,400 copies per ml could be detected in patients with infectious mononucleosis. Further studies revealed that the inhibitory effect of heparinized plasma could be efficiently removed by use of an extraction method with Celite as the absorbent.

Increased incidence of neurological complications in patients receiving an allogenic bone marrow transplantation from alternative donors

OBJECTIVE

To compare the frequency and type of neurological complications after bone marrow transplantation (BMT) with an HLA identical unrelated donor or a mismatched related donor (alternative donors) to the neurological complications after matched sibling BMT for standard and high risk leukaemia or myelodysplastic syndromes.

METHODS

Retrospective analysis of consecutively treated patients with (a) BMT from alternative donors (n=39), (b) treated with matched sibling BMT for standard risk leukaemia, myelodysplastic syndromes, or aplastic anaemia (n=53), and (c) treated with matched sibling BMT for high risk leukaemia, myelodysplastic syndromes, or aplastic anaemia (n=49).

RESULTS

A total of 72 neurological complications were found. Most of these occurred within the first 6 months after transplant. Thirty six patients developed a severe neurological complication: 17 Alternative donor patients (44%) by contrast with six standard risk patients (11%) and 13 high risk patients (27%; p<0.005). The most frequent complication was a metabolic encephalopathy occurring in 18% of patients. Most of the encephalopathies were caused by either the transplant procedure, cyclosporin, systemic infections, microangiopathic thrombopathy, or by complications induced by graft versus host disease. Infections of the CNS developed in 9% of patients, cerebrovascular lesions in 3%.

CONCLUSIONS

Severe neurological complications are more frequent after BMT from alternative donors. This is mainly due to increased treatment related morbidity and to more profound immunosuppression after BMT from alternative donors.

Structure-function analyses of thrombomodulin by gene-targeting in mice: the cytoplasmic domain is not required for normal fetal development

Thrombomodulin (TM) is a widely expressed glycoprotein receptor that plays a physiologically important role in maintaining normal hemostatic balance postnatally. Inactivation of the TM gene in mice results in embryonic lethality without thrombosis, suggesting that structures of TM not recognized to be involved in coagulation might be critical for normal fetal development. Therefore, the in vivo role of the cytoplasmic domain of TM was studied by using homologous recombination in ES cells to create mice that lack this region of TM (TMcyt/cyt). Cross-breeding of F1 TMwt/cyt mice (1 wild-type and 1 mutant allele) resulted in more than 300 healthy offspring with a normal Mendelian inheritance pattern of 25.7% TMwt/wt, 46.6% TMwt/cyt, and 27.7% TMcyt/cyt mice, indicating that the tail of TM is not necessary for normal fetal development. Phenotypic analyses showed that the TMcyt/cyt mice responded identically to their wild-type littermates after procoagulant, proinflammatory, and skin wound challenges. Plasma levels of plasminogen, plasminogen activator inhibitor 1 (PAI-1), and alpha2-antiplasmin were unaltered, but plasmin:alpha2-antiplasmin (PAP) levels were significantly lower in TMcyt/cyt mice than in TMwt/wt mice (0.46 +/- 0.2 and 1.99 +/- 0.1 ng/mL, respectively; P <.001). Tissue levels of TM antigen were also unaffected. However, functional levels of plasma TM in the TMcyt/cyt mice, as measured by thrombin-dependent activation of protein C, were significantly increased (P <.001). This supported the hypothesis that suppression in PAP levels may be due to augmented activation of thrombin-activatable fibrinolysis inhibitor (TAFI), with resultant inhibition of plasmin generation. In conclusion, these studies exclude the cytoplasmic domain of TM from playing a role in the early embryonic lethality of TM-null mice and support its function in regulating plasmin generation in plasma.

Liposomal amphotericin B compared with amphotericin B deoxycholate in the treatment of documented and suspected neutropenia-associated invasive fungal infections

It has been suggested that a better outcome of neutropenia-associated invasive fungal infections can be achieved when high doses of lipid formulations of amphotericin B are used. We now report a randomized multicentre study comparing liposomal amphotericin B (AmBisome, 5 mg/kg/d) to amphotericin B deoxycholate (AmB, 1 mg/kg/d) in the treatment of these infections. Of 106 possible patients, 66 were enrolled and analysed for efficacy: nine had documented fungaemia, 17 had other invasive mould infections and 40 had suspected pulmonary aspergillosis. After completion of the course medication, in the AmBisome group (n = 32) 14 patients had achieved complete response, seven a partial response and 11 were failures as compared to 6, 13 and 15 patients (n = 34) treated with AmB (P=0.09); P=0.03 for complete responders. A favourable trend for AmBisome was found at day 14, in patients with documented infections and in patients with pulmonary aspergillosis (P=0.05 and P=0.096 respectively). Mortality rates were lower in patients treated with AmBisome (adjusted for malignancy status, P=0.03). More patients on AmB had a >100% increase of their baseline serum creatinine (P<0.001). The results indicate that, in neutropenic patients with documented or suspected invasive fungal infections AmBisome 5 mg/kg/d was superior to AmB 1 mg/kg/d with respect to efficacy and safety.

Validation of a WHO algorithm with risk assessment for the clinical management of vaginal discharge in Mwanza, Tanzania

OBJECTIVES

(i) To determine the microbial aetiologies of vaginal discharge in STD clinic and antenatal clinic (ANC) attenders; (ii) to evaluate the performance and costs of a new WHO algorithm for the detection of gonococcal and chlamydial infections in women complaining of vaginal discharge and/or genital itching, using a risk assessment.

METHODS

Two groups were enrolled: (i) 395 consecutive female patients attending a hospital outpatient clinic complaining of genital discharge or itching; and (ii) 628 consecutive pregnant women reporting at an urban ANC these symptoms. Patients were interviewed by a nurse, who applied the WHO risk score. They were then referred to the study room for interview concerning the same and other risk factors, examined, and sampled for Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT), Trichomonas vaginalis (TV), and Candida albicans (CA). Sensitivity, specificity, positive predictive value, overtreatment and correct treatment rates, and cost of drugs per true case treated were estimated.

RESULTS

The prevalence of NG and/or CT infections was 11.4% and 8% at the STD clinic and the ANC respectively. The most prevalent pathogens were CA (38% at both clinics) and TV (25% at the STD clinic and 34% at the ANC). The sensitivity of the WHO algorithm for NG and/or CT was 62% at the STD clinic and 46% at the ANC, and the specificities were 64% and 84% respectively. The operational feasibility of the method was good. The cost of drugs per true case treated in applying the risk assessment approach was $3.5 among nonpregnant women and $5.0 among pregnant women. This compared favourably with respective costs of $8.8 and $25.0 in applying the syndromic management alone.

CONCLUSIONS

The WHO risk assessment algorithm for the diagnosis of NG and/or CT infections among women complaining of genital discharge can considerably reduce overtreatment of NG and/or CT in both pregnant and non-pregnant women, but in this study it failed to identify 38% of non-pregnant and 54% of pregnant women with these infections. The elements of the risk score may need adjustment in different settings.

Risk scores to detect cervical infections in urban antenatal clinic attenders in Mwanza, Tanzania

BACKGROUND

Detection and management of gonococcal and/or chlamydial infections in women is a challenge, particularly in developing countries where laboratory tests are not always available. The World Health Organisation (WHO) has developed a risk assessment approach to identify cervical infections among women complaining of vaginal discharge. We have evaluated this approach as a screening strategy among women attending an urban antenatal clinic (ANC) in Tanzania.

OBJECTIVES

(i) To measure the prevalence of pathogens associated with sexually transmitted diseases (STD) and reproductive tract infections (RTI) in an urban population of ANC attenders in Tanzania; (ii) to examine characteristics of pregnant women associated with cervical infections; and (iii) to evaluate the performance of a WHO risk assessment algorithm and alternative risk scores for the detection of cervical infections in pregnant women.

METHODS

A systematic sample of 660 pregnant women reporting for routine antenatal care at an urban clinic was enrolled. Women were interviewed by a nurse, who applied the WHO risk score. They were referred to a study room for interview about sociodemographic and behavioural factors, examination, and sampling for Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, Candida albicans, and bacterial vaginosis. Sensitivity, specificity, positive predictive value (PPV), and theoretical cost per true case treated were estimated for the diagnosis of cervical infection with N gonorrhoeae and/or C trachomatis for the WHO and other risk scores.

RESULTS

The prevalence of any vaginal or cervical infection was 68%. Prevalence rates of various pathogens were: C albicans 39%, T vaginalis 16%, bacterial vaginosis 24%, N gonorrhoeae 2.3%, C trachomatis 5.9%, any cervical infection (N gonorrhoeae and/or C trachomatis) 7.4%. The WHO score identified only five of 49 women with N gonorrhoeae and/or C trachomatis (sensitivity 10.2%). The specificity and the PPV were 92% and 9.8% respectively. The theoretical cost per true case treated on the basis of the WHO score was over $18. Several risk factors were associated with cervical infection on univariate analysis, but only six remained significant at the 10% level after multivariate analysis. These were: never use of contraceptives (OR 3.09), more than one partner in the past 3 months (OR 3.32), partner with symptoms of genital discharge syndrome (GDS) (OR 7.55), frothy vaginal discharge (OR 1.88), 5-19 polymorphonucleocytes per high power field on cervical smear (OR 3.28), or more than 20 polymorphonucleocytes per high power field (OR 16.08), and wet preparation showing evidence of T vaginalis infection (OR 1.96). Scores based on these variables failed to attain high sensitivities or PPVs (all below 40%) although the costs per true case treated were cheaper than for the WHO score.

CONCLUSION

Risk assessment for the screening and management of N gonorrhoeae and/or C trachomatis among women presenting at routine antenatal services appears feasible and acceptable, but of limited value in this population because of its low sensitivity. The optimal risk score may vary considerably from one place to another. The quest for simple, cheap, and reliable tests to diagnose N gonorrhoeae and C trachomatis infections still remains a high priority on the international STD technology research agenda.

Association between blood eosinophil counts and acute cardiac and pulmonary allograft rejection

BACKGROUND

Peripheral blood eosinophilia is a particularly early and specific marker of both renal and hepatic allograft rejection. Therefore we evaluated the relationship between blood eosinophil counts and cardiac and pulmonary allograft rejection.

METHODS

Differential blood counts were available within 3 days before 383 endomyocardial biopsy specimens in 56 heart transplant recipients. Blood counts were also available before 84 treated rejection episodes and 28 transbronchial biopsy specimens showing no rejection in 58 lung transplant recipients.

RESULTS

Cardiac allograft rejection: There was a significant association between the mean maximum blood eosinophil count and treated acute rejection (p < 0.01) and a linear relationship between this eosinophil count and the histologic grade of rejection (p < 0.01). The first increase in eosinophils occurred at a median of 4 days before treated rejection. Pulmonary allograft rejection: The mean maximum blood eosinophil count was 0.14 x 10(9)/L (95% confidence interval = 0.10, 0.18) preceding treated rejection, and this was significantly greater than the mean maximum blood eosinophil count of 0.07 x 10(9)/L (confidence interval = 0.05, 0.09) measured when there was no rejection or during infection (p = 0.01). The first increase in eosinophil occurred at a median of 5 days before treated rejection. There was no relationship between blood neutrophil counts and either cardiac or pulmonary allograft rejection.

CONCLUSIONS

An increase in peripheral blood eosinophils but not neutrophils is a specific and early marker of clinically significant rejection of both cardiac and pulmonary allografts. Furthermore, the maximum blood eosinophil count measured in the 3 days before rejection is linearly related to the severity of cardiac allograft rejection.

Color-flow imaging sonography of portal and hepatic vein flow to monitor fibrinolytic therapy with r-TPA for veno-occlusive disease following myeloablative treatment

Veno-occlusive disease (VOD) is a serious complication of myeloablative therapy and stem cell transplantation. We here describe a case of VOD in a patient with acute myeloid leukemia (AML), who received an autologous peripheral blood stem cell graft after busulphan/cyclophosphamide conditioning in first complete remission and who developed severe VOD at day 17. Color-flow sonography of the portal and hepatic veins revealed hepatofugal blood flow in the portal vein and an absence of flow in the hepatic vein. Treatment with recombinant tissue plasminogen activator (t-PA) was started at a dose of 10 mg/day and increased to 20 mg/day because color-flow sonography indicated no change of blood flow. Daily sonography was continued to monitor the portal and hepatic blood flow in order to assess the need for continuation of t-PA. Once an objective sonographic improvement was observed, t-PA treatment was tapered and stopped. This case demonstrates that color-flow sonography can be used to confirm the clinical diagnosis of VOD. Furthermore this technique provides a way for easily and reliably evaluating the effect in relation to dose of thrombolytic therapy needed. It improves the quality of clinical monitoring which is needed for effective treatment of VOD while minimizing the risk of serious bleeding complications.

MIBG causes oxidative stress and up-regulation of anti-oxidant enzymes in the human neuroblastoma cell line SK-N-BE(2c)

We report the effects of meta-iodobenzylguanidine (MIBG), a neuroblastoma-seeking agent, on cell proliferation and several oxidative stress-related parameters in the human neuroblastoma cell line SK-N-BE(2c). MIBG inhibited the proliferation of this cell line in micromolar concentrations. Measurements of the malondialdehyde (MDA) concentrations (a measure of the extent of lipid peroxidation) of cells treated with MIBG showed that increasing concentrations of MIBG led to an increase in MDA levels of the cells. This effect was most pronounced after one day of cellular exposure to MIBG and disappeared after 3 days. Disappearance of the elevated MDA levels caused by MIBG is probably the result of increased activity of the H2O2 detoxifying enzymes, catalase and glutathion peroxidase (GPx). The catalase- and GPx-enzyme activity of cells exposed to MIBG steadily increased with time, reaching a maximum after 4 days. Oxidative stress caused by MIBG thus at first leads to cellular damage (lipid peroxidation) but over a longer period does not lead to decreased proliferation rate of the cells, most likely because of cellular adaptation to increased oxidative stress by up-regulation of the H2O2 detoxifying enzymes catalase and GPx.

HBO and the uptake and retention of [125I] MIBG in human platelets and two neuroendocrine cell lines

In this paper we report the effects of Hyperbaric Oxygen (HBO) exposure on the uptake and retention of meta-Iodobenzylguanidine (MIBG) in human platelets and two neuroendocrine cell lines. The combination of [131I] MIBG and HBO is used for therapy of neuroblastoma. Exposure to HBO can cause oxidative stress, which is potentially capable of affecting uptake and storage of MIBG in both neuroendocrine cells and platelets. Oxidative stress generated by menadione decreased both the uptake and retention of MIBG in the platelets and the cell lines. HBO did not affect these processes, indicating that the HBO induced oxidative stress is not high enough to affect the MIBG uptake and storage pathways in these cells. This suggests that the positive effects observed by the treatment of neuroblastoma patients with the combination of HBO and [131I] MIBG are most likely not due to improved uptake or retention of MIBG in the neuroblastoma. Neither can reduced cytotoxicity (trombocytopenia) be expected due to decreased uptake/retention of [131I] MIBG in platelets or their precursor cells.

The effect of the neuroblastoma-seeking agent meta-iodobenzylguanidine (MIBG) on NADH-driven superoxide formation and NADH-driven lipid peroxidation in beef heart submitochondrial particles

In this paper we report the effects of the neuroblastoma-seeking agent meta-iodobenzylguanidine (MIBG) on NADH-driven superoxide formation and NADH-driven lipid peroxidation in beef heart submitochondrial particles. MIBG is a structural analogue of noradrenaline and is capable of inhibiting complex I and complex III of the respiratory chain. The results of our studies show that MIBG enhanced both NADH-driven superoxide formation and NADH-driven lipid peroxidation at concentrations that are likely to exist inside mitochondria of the target cells of neuroblastoma patients treated with [131I]MIBG. The effect of MIBG is comparable to that of rotenone (an inhibitor of complex I) rather than that of antimycin (an inhibitor of complex III). These results suggest that the formation of superoxide and lipid peroxidation contributes to the cytotoxicity of [131I]MIBG.

Specification of the inhibitory action of MIBG on the respiratory chain by EPR scanning

In this paper we report EPR studies on the effects of meta-Iodobenzylguanidine (MIBG), a structural analogue of norepinephrine capable of inhibiting complex I and III of the respiratory chain, on the reduction state of the various complexes of the respiratory chain in beef heart submitochondrial particles. The EPR spectrum of SMPs incubated with MIBG showed completely reduced prosthetic groups of complex I, but oxidised prosthetic groups of complex IV. This indicates that complex I is inhibited by MIBG at the end of the complex (i.e. at the Q binding site). Determination of the exact site of inhibition of MIBG on complex III yielded no conclusive results, but did confirm that complex III is indeed inhibited by MIBG.

Hyperbaric oxygen enhances the effects of meta-iodobenzylguanidine (MIBG) on energy metabolism and lipid peroxidation in the human neuroblastoma cell line SK-N-BE(2C)

In this paper we report the effects of the combination of MIBG (a structural analogue of norepinephrine, used in its radio iodinated form for the diagnosis and therapy of neuroblastoma) and hyperbaric oxygen on the human neuroblastoma cell line SK-N-BE(2c). Exposure of the neuroblastoma cells to hyperbaric oxygen conditions enhanced the effects of MIBG on cell proliferation, lipid peroxidation and energy metabolism of the cell line. Cell proliferation and energy metabolism were further decreased and lipid peroxidation further increased. Enhancement of the effects of MIBG by HBO may provide an explanation for the positive effects on the cumulative survival curve observed when stage IV neuroblastoma patients were treated with the combination of [131I] MIBG and HBO.

Menadione inhibits MIBG uptake in two neuroendocrine cell lines

In this paper we report on our studies of the effect of menadione on the uptake of MIBG in the neuroendocrine cell lines PC12 and SK-N-SH. Menadione inhibits the uptake of MIBG in both cell lines in a dose-dependent manner. Inhibition of MIBG uptake is most pronounced in the PC12 cell line. Comparison of the inhibitory action of menadione on the uptake and retention of MIBG with that of imipramine and reserpine suggests that menadione inhibits uptake 1 mediated uptake as well as granular storage.

Meta-iodobenzylguanidine inhibits complex I and III of the respiratory chain in the human cell line Molt-4

In this paper we report the effects of meta-iodobenzylguanidine (MIBG), a structural analogue of norepinephrine, on cell proliferation and several parameters related to mitochondrial respiration in Molt-4 cells. In micromolar concentrations, MIBG completely inhibited the proliferation of Molt-4 cells. In intact Molt-4 cells, a progressive increase in the lactate to pyruvate ratio was observed after incubation of these cells with glucose and increasing concentrations of MIBG. In Molt-4 cells permeabilized with digitonin, MIBG inhibited mitochondrial ATP synthesis when malate was used as a substrate. Succinate-driven synthesis of ATP was also inhibited by MIBG, although higher concentrations were required. These results indicate that apart from inhibition of complex I, MIBG inhibits at least one other complex of the respiratory chain. Measurement of the activities of the individual enzyme complexes in the presence of MIBG revealed that complex III is the other enzyme complex susceptible to inhibition by MIBG. Although maximal inhibition of ATP synthesis was observed at a concentration of 10 microM, maximal inhibition of cell proliferation was observed at a concentration of 50 microM of MIBG. This suggests that MIBG also influences other cellular processes apart from mitochondrial oxidative phosphorylation, resulting in additional inhibition of cell proliferation.

Meta-iodobenzylguanidine (MIBG) inhibits malate and succinate driven mitochondrial ATP synthesis in the human neuroblastoma cell line SK-N-BE(2c)

In this paper, we report on our studies of the effects of MIBG, a structural analogue of norepinephrine, on SK-N-BE(2c) cells. In micromolar concentrations, MIBG caused almost complete inhibition of the proliferation of SK-N-BE(2c) cells. In intact SK-N-BE(2c) cells, addition of MIBG led to a decrease of the ATP to ADP ratio. A progressive increase of the lactate to pyruvate ratio (due to increased lactate production) was observed after incubation of the cells with glucose and increasing concentrations of MIBG. In cells treated with digitonin, MIBG inhibited malate driven ATP synthesis. Comparable inhibition of ATP synthesis with succinate as a substrate required higher concentrations of MIBG. These results indicate that, apart from inhibition of complex I, MIBG was capable of inhibiting at least one other complex of the respiratory chain. Although maximal inhibition of ATP synthesis was observed at a concentration of 10 microM, optimal inhibition of cell proliferation occurred at a MIBG concentration > 25 microM. This suggests that MIBG also influences other cellular processes apart from mitochondrial ATP synthesis, resulting in additional inhibition of cell proliferation.

Molecular analysis of selection for benzimidazole resistance in the sheep parasite Haemonchus contortus

The molecular basis for the resistance of the sheep parasitic nematode Haemonchus contortus to the benzimidazole (BZ) group of anthelmintics was investigated. Three BZ-susceptible and three resistant populations from different geographical locations were characterized with respect to the egg-hatch assay with thiabendazole (TBZ), mebendazole (MBZ) binding tests and restriction fragment length polymorphism (RFLP) after Southern blotting. Cloned H. contortus alpha- and beta-tubulin genes were used as probes to analyze the RFLPs of genomic DNA prepared from mixtures of infectious larvae (L3) or adults. The susceptible populations showed, with both alpha- and beta-tubulin probes, 2 to 6 different fragments, depending on the restriction enzyme used. The three resistant populations showed as many fragments with the alpha-tubulin probe as the susceptible populations, but when probed with beta-tubulin only 1 or 2 fragments were visible, but always less than in the susceptible populations. An in vitro selection experiment was carried out using a susceptible population that was isolated in the laboratory before BZ came on the market. The results showed that after two selections with increasing amounts of TBZ, the population had become resistant, according to the egg-hatch assay values and MBZ binding assay. Using RFPL, the number of beta-tubulin probe reactive DNA fragments was reduced from 5 to 1. Analysis of the DNA of individual male adults of susceptible populations indicated a heterogeneity among the individual worms regarding the number of beta-tubulin probe reactive fragments (1 to 4) and frequency of the specific fragments. Usually, only one specific fragment (9 kb) was found in the resistant individuals. This 9-kb fragment was already present in some individuals in the susceptible population although it was in combination with other fragments. This would imply that genes conferring BZ resistance were present in H. contortus populations before BZ came on the market, and could explain the fast selection for BZ resistance in the field.