Efficacy of universal preoperative decolonization with Polyhexanide in primary joint arthroplasty on surgical site infections. A multicenter before-and after-study.

BACKGROUND: Surgical site infections (SSI) are rare but severe complications after total joint arthroplasty (TJA). Decolonization measures prior to elective orthopedic surgeries have shown to reduce the risk of SSI with Staphylococcus aureus (S. aureus). OBJECTIVE: To determine the efficacy of universal decolonization with Polyhexanide on SSI rates with a focus on Staphylococcus aureus in patients with TJA. METHODS: Patients scheduled for elective hip or knee TJA in 5 participating certified orthopedic centers were included between 2015 and 2018 into this before and after study. Data on patients, surgeries and infections were prospectively collected. CDC-criteria were used to define and categorize Infections within 90 days after surgery. From January 2017 on, patients received decolonization sets containing Polyhexanide. Patients performed a 5 day decolonization regimen starting 4 days prior to surgery which included wipes, nasal decontamination and oral solution. RESULTS: Thirteen thousand, three hundred fifteen patients received TJA. During intervention 4437 decolonization sets were distributed among 7175 patients. Overall SSI rates increased from 0.68 /100 surgeries to 0.91/ 100 surgeries after implementation of the intervention (IRR 1.32; 95% CI 0.90-1.96). Time series analysis identified an increasing trend of SSI prior to the intervention. After implementation overall SSI rates plateaued. Regression analysis revealed surgery during intervention period to be an independent risk factor for developing a SSI (OR 1.34; 95%CI 1.18-1.53). Initial SSI rates due to S. aureus were 0.24/100 surgeries and decreased to 0.14/100 surgeries (IRR 0.57; 95% CI 0.25-1.22) after introduction of decolonization. Regression analysis revealed surgery during intervention period to be an independent protective factor for developing a SSI with S. aureus (OR 0.57, 95% CI: 0.33-0.99). Overall deep S. aureus SSI decreased significantly from 0.22/100 surgeries to 0.00/100 surgeries in patients adherent to protocol (IRR 0.00, 95% CI 0.00-.85). CONCLUSION: Universal decolonization with Polyhexanide did not reduce overall surgical site infections, but was effective in reducing Staphylococcus aureus - surgical site infections following elective joint arthroplasty. Polyhexanide could extend the list of alternatives to already established decolonization strategies. TRIAL REGISTRATION: The trial was registered at the German Registry for clinical studies www.drks.de ( DRKS00011505 ).

Real-world non-interventional long-term post-authorisation safety study of ruxolitinib in myelofibrosis.

Primary objective of this non-interventional, post-authorisation safety study was to provide real-world safety data [incidence of adverse drug reactions (ADRs)/serious adverse events (SAEs)] on adult patients with myelofibrosis exposed/or not exposed to ruxolitinib. Key secondary objectives included the incidence/outcome of events of special interest (bleeding events, serious/opportunistic infections, second primary malignancies, and deaths). Overall, 462 patients were included [prevalent users = 260, new users = 32, non-exposed = 170 (inclusive of ruxolitinib-switch, n = 57)]. The exposure-adjusted incidence rates (per 100 patient-years) of ADRs (19·3 vs. 19·6) and SAEs (25·2 vs. 25·0) were comparable amongst new-users versus prevalent-users cohorts, respectively; most frequent ADRs across all cohorts included thrombocytopenia, anaemia, epistaxis, urinary tract infection, and herpes zoster. Anaemia, pneumonia, general physical health deterioration, sepsis, and death were the most frequent SAEs across all cohorts. Incidence rates of bleeding events (21·6) and serious/opportunistic infections (34·5) were higher in ruxolitinib-switch cohort versus other cohorts. The incidence rate of second primary malignancies was higher in the prevalent-users cohort (10·1) versus other cohorts. The observed safety profile of ruxolitinib in the present study along with the safety findings from the COMFORT/JUMP/EXPAND studies support the use of ruxolitinib for long-term treatment of patients with myelofibrosis.

Inhibition of PLK1 by capped-dose volasertib exerts substantial efficacy in MDS and sAML while sparing healthy haematopoiesis.

INTRODUCTION: Targeting the cell cycle machinery represents a rational therapeutic approach in myelodysplastic syndromes (MDS) and secondary acute myeloid leukemia (sAML). Despite substantial response rates, clinical use of the PLK inhibitor volasertib has been hampered by elevated side effects such as neutropenia and infections. OBJECTIVES: The primary objective was to analyse whether a reduced dose of volasertib was able to limit toxic effects on the healthy haematopoiesis while retaining its therapeutic effect. METHODS: Bone marrow mononuclear cells (BMMNCs) of patients with MDS/sAML (n = 73) and healthy controls (n = 28) were treated with volasertib (1 µM to 1 nM) or vehicle control. Short-term viability analysis was performed by flow cytometry after 72 hours. For long-term viability analysis, colony-forming capacity was assessed after 14 days. Protein expression of RIPK3 and MCL-1 was quantified via flow cytometry. RESULTS: Reduced dose levels of volasertib retained high cell death-inducing efficacy in primary human stem and progenitor cells of MDS/sAML patients without affecting healthy haematopoiesis in vitro. Interestingly, volasertib reduced colony-forming capacity and cell survival independent of clinical stage or mutational status. CONCLUSIONS: Volasertib offers a promising therapeutic approach in patients with adverse prognostic profile. RIPK3 and MCL-1 might be potential biomarkers for sensitivity to volasertib treatment.

Venetoclax with azacitidine targets refractory MDS but spares healthy hematopoiesis at tailored dose.

Patients with Myelodysplastic Syndromes (MDS) and secondary Acute Myeloid Leukemia (sAML) have a very poor prognosis after failure of hypomethylating agents (HMA). Stem cell transplantation is the only effective salvage therapy, for which only a limited number of patients are eligible due to age and comorbidity. Combination therapy of venetoclax and azacitidine (5-AZA) seems to be a promising approach in myeloid malignancies, but data from patients with HMA failure are lacking. Furthermore, a considerable concern of combination regimens in elderly AML and MDS patients is the toxicity on the remaining healthy hematopoiesis. Here, we report in vitro data showing the impact of venetoclax and 5-AZA, alone or in combination, in a larger cohort of MDS/sAML patients (n = 21), even after HMA failure (n = 13). We especially focused on the effects on healthy hematopoiesis and the impact on colony forming capacity as a parameter for long-term effects. To the best of our knowledge, we show for the first time that venetoclax in combination with capped dose of 5-AZA targets cell malignancies, while sparing healthy hematopoiesis.

Calcification of the acetabular labrum of the hip: prevalence in the general population and relation to hip articular cartilage and fibrocartilage degeneration.

BACKGROUND: Meniscal calcification is considered to play a relevant role in the pathogenesis of osteoarthritis of the knee. Little is known about the biology of acetabular labral disease and its importance in hip pathology. Here, we analyze for the first time the calcification of the acetabular labrum of the hip (ALH) and its relation to hip cartilage degeneration. METHODS: In this cross-sectional post-mortem study of an unselected sample of the general population, 170 ALH specimens and 170 femoral heads from 85 donors (38 female, 47 male; mean age 62.1 years) were analyzed by high-resolution digital contact radiography (DCR) and histological degeneration grade. The medial menisci (MM) from the same 85 donors served as an intra-individual reference for cartilage calcification (CC). Scanning electron microscopy (SEM), energy dispersive analysis (ED) and Raman spectroscopy were performed for characterization of ALH CC. RESULTS: The prevalence of CC in the ALH was 100% and that in the articular cartilage of the hip (ACH) was 96.5%. Quantitative analysis revealed that the amount of ALH CC was higher than that in the ACH (factor 3.0, p < 0.001) and in the MM (factor 1.3, p < 0.001). There was significant correlation between the amount of CC in the fibrocartilage of the left and right ALH (r = 0.70, p < 0.001). Independent of age, the amount of ALH CC correlated with histological degeneration of the ALH (Krenn score) (r = 0.55; p < 0.001) and the ACH (Osteoarthritis Research Society International (OARSI), r = 0.69; p < 0.001). Calcification of the ALH was characterized as calcium pyrophosphate dihydrate deposition. CONCLUSION: The finding that ALH fibrocartilage is a strongly calcifying tissue is unexpected and novel. The fact that ALH calcification correlates with cartilage degeneration independent of age is suggestive of an important role of ALH calcification in osteoarthritis of the hip and renders it a potential target for the prevention and treatment of hip joint degeneration.

Selective inhibition of BCL-2 is a promising target in patients with high-risk myelodysplastic syndromes and adverse mutational profile.

Somatic mutations in genes such as ASXL1, RUNX1, TP53 or EZH2 adversely affect the outcome of patients with myelodysplastic syndromes (MDS). Since selective BCL-2 inhibition is a promising treatment strategy in hematologic malignancies, we tested the therapeutic impact of ABT-199 on MDS patient samples bearing an adverse mutational profile. By gene expression, we found that the level of pro-apoptotic BIM significantly decreased during MDS disease progression in line with an acquired resistance to cell death. Supporting the potential for ABT-199 treatment in MDS, high-risk MDS patient samples specifically underwent cell death in response to ABT-199 even when harbouring mutations in ASXL1, RUNX1, TP53 or EZH2. ABT-199 effectively targeted the stem- and progenitor compartment in advanced MDS harbouring mutations in ASXL1, RUNX1, TP53 or EZH2 and even proved effective in patients harbouring more than one of the defined high-risk mutations. Moreover, we utilized the protein abundance of BCL-2 family members in primary patient samples using flow cytometry as a biomarker to predict ABT-199 treatment response. Our data demonstrate that ABT-199 effectively induces apoptosis in progenitors of high-risk MDS/sAML despite the presence of adverse genetic mutations supporting the notion that pro-apoptotic intervention will hold broad therapeutic potential in high-risk MDS patients with poor prognosis.

Tolerability and efficacy of deferasirox in patients with transfusional iron overload: results from a German 2-year non-interventional study.

BACKGROUND: Iron overload (IOL) due to repetitive transfusions of packed red blood cells (pRBC) has a major impact on morbidity and mortality in patients with inherited bone marrow failure syndromes and hemoglobinopathies such as thalassemia and sickle cell disease. However, whether IOL influences the outcome of elderly patients with myeloid malignancies is not yet clear. Moreover, clinical trials have reported high drop-out rates during treatment with the oral iron chelator deferasirox (DFX). AIM: Here we report the results of a 2-year prospective observational study that aimed at describing the routine use of DFX in patients with hematological malignancies with regard to safety, efficacy and handling of the drug in a routine setting. RESULTS: A total of 406 patients were included. 58% of the patients were male. Most of the patients had myelodysplastic syndromes (MDS) (68%) and myeloproliferative neoplasms (MPN) (14%). Median time from first transfusion to study enrollment was 1.1 years (0-25.5 years) and most patients were chelation naive (91%) at enrollment. With regard to transfusion burden, most of the patients were moderately or mildly transfusion-dependent with 53% receiving 2-4 and 27% receiving less than 2 units of pRBC per month. Serum ferritin decreased from a mean of 2305 µg/l (± 1449 µg/l) to a mean of 1910 µg/l (± 1529 µg/l) at 24 months. There was no substantial change in transfusion-dependence during the observation period. Dose adjustments were reported in 48% of the patients with dose-escalation strategies being the most frequent reason for dosage increases (49%). The median observation time was 355 days (5-1080 days). Median duration of exposure to DFX was 322 days (2-1078 days). Two-hundred and ninety (72%) patients discontinued the trial prematurely after a median time of 235 days (1-808 days). Death (29%) and adverse events (23%) were the main reasons for discontinuation. Eleven percent of the patients discontinued treatment due to sufficient decrease in serum ferritin. Most frequent adverse events were decrease in creatinine clearance (22%), increase in serum creatinine (18%) and diarrhea (16%). CONCLUSION: This descriptive trial confirms the efficacy of DFX in decreasing the serum ferritin. Moreover, the high drop-out rates seen in prospective trials are recapitulated in this study, which can be attributed to adverse events in a substantial proportion of patients.

Lack of supportive leadership behavior predicts suboptimal self-rated health independent of job strain after 10 years of follow-up: findings from the population-based MONICA/KORA study.

OBJECTIVES: Emerging cross-sectional research has identified lack of supportive leadership behavior (SLB) as a risk factor for workforce health. However, prospective evidence is hitherto lacking. SLB denotes support in difficult situations, recognition and feedback on work tasks. This study aims to determine the effect of SLB on suboptimal self-rated health (SRH) after 10 years considering potential moderators such as ages, sex, occupation and job strain. METHODS: The sample included 884 employed participants drawn from the population-based prospective MONICA/KORA Study. SLB, SRH, as well as job strain were assessed by questionnaire. Logistic regressions estimated odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the effect of SLB at baseline on suboptimal SRH at follow-up. Analyses were adjusted for age, gender, lifestyle (alcohol, smoking, physical activity), socioeconomic status as well as for SRH and job strain at baseline. RESULTS: Lack of SLB was associated with suboptimal SRH at baseline [OR 2.00, (95% CI 1.19-3.46)] and at follow-up [OR 2.33, (95% CI 1.40-3.89)]. Additional adjustment for job strain did not substantially alter this association [OR 2.06, (95% CI 1.20-3.52)]. However, interactions between SLB and job strain as well as gender became evident, indicating moderating influences on the association between SLB and SRH. CONCLUSION: Lack of supportive leadership was associated with suboptimal SRH at 10 years' follow-up in men, even if SRH at baseline and other risk factors were taken into account. This effect is likely to be moderated by job strain.

Familial hypercholesterolemia in primary care in Germany. Diabetes and cardiovascular risk evaluation: Targets and Essential Data for Commitment of Treatment (DETECT) study.

BACKGROUND AND AIMS: Familial hypercholesterolemia (FH) is an inherited disorder of lipoprotein metabolism characterised by impaired removal of low-density lipoproteins (LDL) from the circulation, which leads to an increased risk of cardiovascular disease (CVD). This risk can be significantly lowered by early diagnosis and treatment. In Germany, reliable estimates of the prevalence of FH are lacking. We therefore examined the prevalence rate of FH in Germany in a primary care based cohort. METHOD: We utilized records of 4722 participants in the DETECT study, in whom complete data on blood lipids and medical history were available. Prevalence rates were assessed using the Dutch Lipid Clinics Network (DLCN) and the US-MEDPED criteria. We stratified for gender and age. Group differences were analyzed using Chi2 and ANOVA tests. RESULTS: Using the DLCN (probable or definite FH) and the US.MEDPED criteria yielded prevalence rates of 1:278 and 1:295, respectively. The established diagnostic scores used in this analysis identify different patients. In women below 50 years of age, the LDL-C concentration is lower than in men, leading to the possibility of under-diagnosing FH in this group because women under the age of 50 are less likely to reach a higher DLCN-Score. CONCLUSIONS: FH has a higher than expected prevalence in Germany. Clinical diagnostic algorithms may not be concordant.

Low-dose fludarabine with or without darbepoetin alfa in patients with chronic lymphocytic leukemia and comorbidity: primary results of the CLL9 trial of the German CLL Study Group.

This study was planned as a phase 3 trial to investigate low-dose fludarabine with or without darbepoetin alfa in older patients with previously untreated or treated chronic lymphocytic leukemia (CLL) and comorbidity. Due to slow recruitment, the study was terminated prematurely after accrual of 97 patients who, on average, were 74 years old and had a cumulative illness rating scale (CIRS) total score of 5. We report toxicity and efficacy of the study treatment. Grade 3-5 neutropenia and infection were observed in 25% and 10% of patients, respectively. Response was seen in 73% (5% complete remissions). Median event-free and overall survival was 12.2 and 44.8 months, respectively. No differences in outcome were found for patients treated with versus without darbepoetin alfa. In subjects with progressive/recurrent CLL during or after study treatment, overall survival was similar for patients receiving chemotherapy versus chemoimmunotherapy as salvage treatment.

Metabolism of the14C-labeled herbicide clodinafop-propargyl in plant cell cultures of wheat and tobacco.

The metabolism of 14C-clodinafop-propargyl (CfP) was examined in cell cultures of wheat (Triticum aestivum L. cv. 'Heines Koga II') and tobacco (Nicotiana tabacum L.). Besides the non-transgenic tobacco culture, cultures transformed separately with cDNA of human cytochrome P450-monooxygenases (P450s) CYP1A1, CYP1A2, CYP3A4, CYP2B6 and CYP2C19 were examined. Experiments with wheat were executed in the presence and absence of safener cloquintocet-mexyl (CqM). After 48 h of incubation, only about 10% of applied 14C was found in media (both tobacco and wheat). Non-extractable residues of 14C-CfP in wheat cells were 16.54% (without CqM) and 30.87% (with CqM). In all tobacco cultures, 82.41-92.46% of applied radioactivity was recovered in cell extracts. In contrast to wheat, non-extractable residues amounted only to 1.50-2.82%. As determined by radio-thin layer chromatography (TLC) and -high-performance liquid chromatography (HPLC), the parent CfP was not found in the cell extracts of wheat; in tobacco cell extracts, only traces of CfP were detected. After a hydrolysis of assumed carbohydrate conjugates of CfP derived polar 14C-labeled compounds, TLC and HPLC analysis showed that in wheat, a more complex pattern of metabolites of CfP were observed as compared to all tobacco cultures. In hydrolysates resulting from wheat, the identity of three primary products was confirmed by means of GC-EI-MS: free acid clodinafop (Cf), hydroxy-Cf hydroxylated at the pyridinyl moiety, and 4-(5-chloro-3-fluoropyridin-2-yloxy)phenol. In hydrolysates derived from all tobacco cultures, main metabolite was Cf besides only traces of further unidentified products. Differences among the different tobacco cultures (non-transgenic, transgenic) did not emerge. According to kinetics of disappearance of primary metabolite Cf as well as formation of polar soluble products and non-extractable residues, metabolization of CfP proceeded at a noticeably higher rate in wheat cells treated with safener CqM than in cells without CqM treatment. Thus, these results indicated a stimulation of CfP's metabolism by CqM, although metabolic profiles observed in CqM treated and non-treated cells (after hydrolysis) were qualitatively similar. The findings obtained from all tobacco cultures suggested that with the exception of ester cleavage to Cf, CfP cannot be metabolized by tobacco itself or by the human P450s examined.

Myeloablative anti-CD20 radioimmunotherapy +/- high-dose chemotherapy followed by autologous stem cell support for relapsed/refractory B-cell lymphoma results in excellent long-term survival.

BACKGROUND: Radioimmunotherapy (RIT) has been used to treat relapsed/refractory CD20+ Non-Hodgkin lymphoma (NHL). Myeloablative anti-CD20 RIT followed by autologous stem cell infusion (ASCT) enables high radiation doses to lymphoma sites. We performed a phase I/II trial to assess feasibility and survival. METHODS: Twenty-three patients with relapsed/refractory NHL without complete remission (CR) to salvage chemotherapy were enrolled to evaluate RIT with Iodine-131 labelled rituximab (131I-rituximab) in a myeloablative setting. Biodistribution and dosimetric studies were performed to determine 131I activity required to induce a total body dose of 21-27Gy to critical organs. In 6/23 patients RIT was combined with high-dose chemotherapy. 8/23 patients received a sequential high-dose chemotherapy with a second ASCT. The median follow-up is 9.5 years. RESULTS: 6.956-19.425GBq of 131I was delivered to achieve the limiting organ dose to lungs or kidneys. No grade III/IV non-hematologic toxicity was seen with RIT alone. Significant grade III/IV toxicity (mucositis, fever, infection, one therapy related death) was observed in patients treated with RIT combined with high-dose chemotherapy. The overall response rate was 87% (64% CR). The median progression-free (PFS) and overall survival (OS) is 47.5 and 101.5 months. An international prognostic index score >1 was predictive for OS. CONCLUSION: Myeloablative RIT with 131I-rituximab followed by ASCT is feasible, well-tolerated and effective in high risk CD20+ NHL. Combination of RIT and high-dose chemotherapy increased toxicity significantly. Long-term results for PFS and OS are encouraging.

Molecular cytogenetic monitoring from CD34+ peripheral blood cells in myelodysplastic syndromes: first results from a prospective multicenter German diagnostic study.

The gold standard of cytogenetic analysis in myelodysplastic syndromes (MDS) is conventional chromosome banding (CCB) analysis of bone marrow (BM) metaphases. Most aberrations can also be detected by fluorescence-in situ-hybridization (FISH). For this prospective multicenter German diagnostic study (www.clinicaltrials.gov: #NCT01355913) 360 patients, as yet, were followed up to 3 years by sequential FISH analyses of immunomagnetically enriched CD34+ peripheral blood (PB) cells using comprehensive FISH probe panels, resulting in a total number of 19,516 FISH analyses. We demonstrate that CD34+ PB FISH correlates significantly with CCB analysis and represents a feasible method for a reliable non-invasive cytogenetic monitoring from PB.

Peptide salt bridge stability: from gas phase via microhydration to bulk water simulations.

The salt bridge formation and stability in the terminated lysine-glutamate dipeptide is investigated in water clusters of increasing size up to the limit of bulk water. Proton transfer dynamics between the acidic and basic side chains is described by DFT-based Born-Oppenheimer molecular dynamics simulations. While the desolvated peptide prefers to be in its neutral state, already the addition of a single water molecule can trigger proton transfer from the glutamate side chain to the lysine side chain, leading to a zwitterionic salt bridge state. Upon adding more water molecules we find that stabilization of the zwitterionic state critically depends on the number of hydrogen bonds between side chain termini, the water molecules, and the peptidic backbone. Employing classical molecular dynamics simulations for larger clusters, we observed that the salt bridge is weakened upon additional hydration. Consequently, long-lived solvent shared ion pairs are observed for about 30 water molecules while solvent separated ion pairs are found when at least 40 or more water molecules hydrate the dipeptide. These results have implications for the formation and stability of salt bridges at partially dehydrated surfaces of aqueous proteins.

The cytotoxicity of anti-CD22 immunotoxin is enhanced by bryostatin 1 in B-cell lymphomas through CD22 upregulation and PKC-ßII depletion.

BACKGROUND: In spite of potent first-line therapies for chronic lymphocytic leukemia, treatment remains palliative and all patients frequently relapse. Treatment options for these patients are more limited. BL22 is a recombinant protein composed of the variable region of a monoclonal antibody that binds to CD22 and of PE38, a truncated Pseudomonas exotoxin. BL22 is a very potent drug already used in patients with hairy cell leukemia, whereas in chronic lymphocytic leukemia its cytotoxicity is limited by a lower expression of CD22. Here we demonstrate that this limitation can be overcome by pre-activation of chronic lymphocytic leukemia cells with bryostatin 1. DESIGN AND METHODS: Primary malignant B cells from chronic lymphocytic leukemia and mantle cell lymphoma patients were used in vitro to assess the therapeutic impact of drug combinations using BL22 and bryostatin 1. RESULTS: We demonstrate that bryostatin 1 sensitizes chronic lymphocytic leukemia cells for the cytotoxic effects of BL22 through activation of protein kinase C and subsequently increased CD22 surface expression. Dose and time response analysis reveals that activation of protein kinase C further activates an autocrine feedback loop degrading protein kinase C-ßII protein. Depletion of protein kinase C-ßII and upregulation of CD22 persist for several days following pre-stimulation with bryostatin 1. Therefore, our data provide a rationale for the sequential administration of BL22 following bryostatin 1 treatment. In addition to primary chronic lymphocytic leukemia cells, bryostatin 1 also sensitizes diffuse large B-cell lymphoma and mantle cell lymphoma cells to BL22 induced apoptosis. CONCLUSIONS: Our data suggest that the combination of bryostatin 1 with antibodies directed against CD22 is a potent drug combination for the treatment of low- and high-grade B-cell lymphoma.

Chlorinated isomers of nonylphenol differ in estrogenic and androgenic activity.

Technical mixtures of nonylphenol (NP) contain over 20 p-substituted isomers. Mono- and di-chlorinated derivatives are generated during the chlorination process in water treatment. Four NP isomers (i.e. 4n-, p353-, p33-, p363-NP) and their mono- (MCl) and di-chlorinated (DCl) derivatives were tested for their estrogenic and androgenic potency using yeast estrogenic and androgenic assay. The p353-NP and 4n-MClNP isomers showed the highest and the lowest estrogenic potency, respectively. The p363-MClNP exhibits estrogenic potency comparable to the parent isomer, whereas all p-DClNP compounds displayed a decrease in the estrogenic potency. In the anti-androgenic screen, all substances exhibited a positive response; the mono- and di-chlorinated derivatives exhibit lower potency than the parent isomers. The isomer p363-NP and its corresponding mono- and di-chlorinated derivatives were almost inactive. Furthermore, all compounds were tested for anti-estrogenic and androgenic assays, but none of them showed a positive response. These results indicate that for assessing the xeno-hormone potency of chlorinated derivatives of NP, the use of pure compounds is essential because the mixtures are not representative. In fact the concentrations of NP isomers differ in technical mixtures according to the producers; after chlorination different technical mixtures can generate dissimilar ratios of chlorinated derivatives. Finally, the chlorinated derivatives of NP didn't show an increase in xeno-hormone potency compared to the parent isomers, and for this reason the many oxidized by-products generated during chlorination process mask the xeno-hormone potency of the pure chlorinated isomers of NP.