TNFalpha stimulates NKG2D-mediated lytic activity of acute myeloid leukemic cells.

The mechanism by which leukemic cells interfere with normal hematopoiesis remains unclear. We show here that, whereas the leukemic KG1a cells are naturally devoid from cellular cytotoxicity, once activated by TNFalpha, they display cytolytic activity toward various cellular targets including CFU-GM. This mechanism is dependent on stimulation of the granzyme B/perforin system. In addition, KG1a cells expressed the NKG2D receptor and its signal-transducing adaptator DAP 10, which were functional as confirmed by redirected lysis experiments. Interestingly, flow cytometry analysis of 20 samples of patients with acute myeloid leukemia (AML) (FAB M0-M5) revealed the expression of NKG2D (40%) and other natural cytotoxicity receptors (40% for NKp30, 74% for NKp44, 39% for NKp46) by a pool >15% of leukemic cells. Furthermore, CD34+ hematopoietic progenitors undergoing granulomonocytic differentiation expressed NKG2D ligands. Altogether, we propose a model in which, upon stimulation by TNFalpha, leukemic cells may exert cytotoxicity against myeloid progenitors. This finding may have important clinical implications in the context of diseases characterized by TNFalpha accumulation, such as AML or myelodisplasic syndromes.     

An Investigation of Oral Exposure Variability and Formulation Strategy: A Case Study of PI3Kδ Inhibitor and Physiologically Based Pharmacokinetic Modeling in Beagle Dogs

It is well acknowledged that drugs with poor aqueous solubility are often associated with poor oral absorption. Fortunately, drugs with a basic pKa can take advantage of solubilization in the stomach under the acidic environment to improve exposure. Consequently, high in vivo variability is often observed when stomach pH is altered. When issue encountered, enabling formulations are often used to solve the problem. However, each enabling formulation has its limitations and the situation can be further complicated by other absorption distribution metabolism elimination parameters. Therefore, formulation strategies need to consider various scenarios in order to be effective. Compound 1 is a potent phosphoinositide 3-kinase delta inhibitor with poor intrinsic solubility and 2 basic pKas. It was dosed as a suspension in dogs and found to have mediocre oral bioavailability with high variability. It was hypothesized that this variability was caused by their stomach pH variability. Pharmacokinetic modeling suggested that the issue could be improved with particle size reduction. Meanwhile, it was found that although the Madin-Darby canine kidney permeability was reasonable, Madin-Darby canine kidney transfected with human MDR1 gene (MDCK-MDR1) suggested that Compound 1 is an efflux transporter substrate. Findings were integrated into the design for in vivo studies in dogs. Data obtained from those studies allowed us to quickly narrow down the formulation approaches.     

Probing binding requirements of type I and type II isoforms of inosine monophosphate dehydrogenase with adenine-modified nicotinamide adenine dinucleotide analogues

Novel tiazofurin adenine dinucleotide (TAD) analogues 25-33 containing a substituent at C2 of the adenine ring have been synthesized as inhibitors of the two isoforms of human IMP-dehydrogenase. The 2-ethyl TAD analogue 33 [Ki = 1 nM (type I), Ki = 14 nM (type II)] was found to be the most potent. It did not inhibit three other cellular dehydrogenases up to 50 microM. Mycophenolic adenine bis(phosphonate)s containing a 2-phenyl (37) or 2-ethyl group (38), were prepared as metabolically stable compounds, both nanomolar inhibitors. Compound 38 [Ki = 16 nM (type I), Ki = 38 nM (type II)] inhibited proliferation of leukemic K562 cells (IC50 = 1.1 microM) more potently than tiazofurin (IC50 = 12.4 microM) or mycophenolic acid (IC50 = 7.7 microM).     

Coatings of hydroxyapatite–bioactive glass microparticles for adhesion to biological tissues

Adsorption of particles across interfaces has been proposed as a way to create adhesion between hydrogels and biological tissues. Here, we explore how this particle bridging approach can be applied to attach a soft polymer substrate to biological tissues, using bioresorbable and nanostructured hydroxyapatite–bioactive glass microparticles. For this, microparticles of aggregated flower-like hydroxyapatite and bioactive glass (HA–BG) were synthesized via a bioinspired route. A deposition technique using suspension spreading was developed to tune the coverage of HA–BG coatings at the surface of weakly cross-linked poly(beta-thioester) films. By varying the concentration of the deposited suspensions, we produced coatings having surface coverages ranging from 4% to 100% and coating densities ranging from 0.02 to 1.0 mg cm⁻². The progressive dissolution of these coatings within 21 days in phosphate-buffered saline was followed by SEM. Ex vivo peeling experiments on pig liver capsules demonstrated that HA–BG coatings produce an up-to-two-fold increase in adhesion energy (9.8 ± 1.5 J m⁻²) as compared to the uncoated film (4.6 ± 0.8 J m⁻²). Adhesion energy was found to increase with increasing coating density until a maximum at 0.2 mg cm⁻², well below full surface coverage, and then it decreased for larger coating densities. Using microscopy observations during and after peeling, we show that this maximum in adhesion corresponds to the appearance of particle stacks, which are easily separated and transferred onto the tissue. Such bioresorbable HA–BG coatings give the possibility of combining particle bridging with the storage and release of active compounds, therefore offering opportunities to design functional bioadhesive surfaces.

Coatings of hydroxyapatite–bioactive glass microparticles are proposed as a way to create adhesion between hydrogels and biological tissues using adsorption of the microparticles across the interface.     

Role of size and composition of traffic and agricultural aerosols in the molecular responses triggered in airway epithelial cells

The increased levels of fine particles in the atmosphere are suspected of aggravating cardiopulmonary diseases, but the determinants of particle toxicity are poorly understood. This work aims at studying the role of composition and size in the toxicity of size-segregated particulate matter (PM) collected at different sites on human bronchial epithelial cells. PM were sampled at a traffic urban site (Urb S) and a rural site (Rur S) during the pesticide-spreading period. Ultrafine (UF), fine (F), and coarse (C) PM were characterized by their shape and chemical composition. Whatever the site, the finest PM (UF and F) induced the mRNA expression of CYP1A1, a biomarker of polyaromatic hydrocarbons (PAH) exposure, NQO-1 and heme HO-1, two antioxidant responsive element-driven genes; and two effect biomarkers, GM-CSF, a proinflammatory cytokine and amphiregulin (AR), a growth factor. C PM have a low or no effect. Interestingly, AR is more strongly induced by rural PM at the same mass exposure. These discrepancies suggest involvement of PM chemical composition: rural PM bearing the characteristics of aged aerosols with a high content of water-soluble components, and PM at urban kerbside sites containing mainly water-insoluble components. To conclude, we provide evidence that the finest PM fractions, whatever their origin, are more prone to induce exposure and effect biomarkers. The AR differential expression suggests a source-dependent effect requiring further investigation because of the role of this growth factor in airway remodeling, a characteristic feature of chronic lung respiratory diseases exacerbated by particulate pollution.     

Ciguatera risk management in French Polynesia: The case study of Raivavae Island (Australes Archipelago)

Based on epidemiological data available through long-term monitoring surveys conducted by both the Public Health Directorate and the Louis Malardé Institute, ciguatera is highly endemic in French Polynesia, most notably in Raivavae (Australes) which appears as a hot spot of ciguatera with an average incidence rate of 140 cases/10,000 population for the period 2007-2008. In order to document the ciguatera risk associated with Raivavae lagoon, algal and toxin-based field monitoring programs were conducted in this island from April 2007 to May 2008. Practically, the distribution, abundance and toxicity of Gambierdiscus populations, along with the toxicity levels in 160 fish distributed within 25 distinct species, were assessed in various sampling locations. Herbivores such as Scarids (parrotfish) and Acanthurids (unicornfish) were rated as high-risk species based on receptor-binding assay toxicity data. A map of the risk stratification within the Raivavae lagoon was also produced, which indicates that locations where both natural and man-made disturbances have occurred remained the most susceptible to CFP incidents. Our findings also suggest that, locally, the traditional knowledge about ciguatera may not be scientifically complete but is functionally correct. Community education resulted in self-regulating behaviour towards avoidance of high-risk fish species and fishing locations.     

Renal function and clinical outcome of patients with cancer-associated venous thromboembolism randomized to receive apixaban or dalteparin. Results from the Caravaggio trial

The effect of renal impairment (RI) on risk of bleeding and recurrent thrombosis in cancer patients treated with direct oral anticoagulants for venous thromboembolism (VTE) is undefined. We ran a prespecified analysis of the randomized Caravaggio study to evaluate the role of RI as a risk factor for bleeding or recurrence in patients treated with dalteparin or apixaban for cancer-associated VTE. RI was graded as moderate (creatinine clearance between 30-59 mL/minute; 275 patients) and mild (between 60-89 mL/minute; 444 patients). In the 1142 patients included in this analysis, the incidence of major bleeding was similar in patients with moderate vs. no or mild RI (HR 1.06-95% CI: 0.53-2.11), with no difference in the relative safety of apixaban and dalteparin. Recurrent VTE was not different in moderate vs. no or mild RI (HR=0.67, 95% CI: 0.38-1.20); in moderate RI, apixaban reduced recurrent VTE compared to dalteparin (HR=0.27, 95% CI: 0.08-0.96; P for interaction 0.1085). At multivariate analysis, no association was found between variation of renal function over time and major bleeding or recurrent VTE. Advanced or metastatic cancer was the only independent predictor of major bleeding (HR=2.84, 95% CI: 1.20-6.71), with no effect of treatment with apixaban or dalteparin. In our study, in cancer patients treated with apixaban or dalteparin, moderate RI was not associated with major bleeding or recurrent VTE. In patients with moderate renal failure, the safety profile of apixaban was confirmed with the potential for improved efficacy in comparison to dalteparin. ClinicalTrials.gov identifier: {"type":"clinical-trial","attrs":{"text":"NCT03045406","term_id":"NCT03045406"}}NCT03045406.     

First imaging results of an intraindividual comparison of 11C-acetate and 18F-fluorocholine PET/CT in patients with prostate cancer at early biochemical first or second relapse after prostatectomy or radiotherapy

Purpose

¹⁸F-Fluorocholine (FCH) and ¹¹C-acetate (ACE) PET are widely used for detection of recurrent prostate cancer (PC). We present the first results of a comparative, prospective PET/CT study of both tracers evaluated in the same patients presenting with recurrence and low PSA to compare the diagnostic information provided by the two tracers.

Methods

The study group comprised 23 patients studied for a rising PSA level after radical prostatectomy (RP, 7 patients, PSA ≤3 ng/ml), curative radiotherapy (RT, 7 patients, PSA ≤5 ng/ml) or RP and salvage RT (9 patients, PSA ≤5 ng/ml). Both FCH and ACE PET/CT scans were performed in a random sequence a median of 4 days (range 0 to 11 days) apart. FCH PET/CT was started at injection (307?±?16 MBq) with a 10-min dynamic acquisition of the prostate bed, followed by a whole-body PET scan and late (45 min) imaging of the pelvis. ACE PET/CT was performed as a double whole-body PET scan starting 5 and 22 min after injection (994?±?72 MBq), and a late view (45 min) of the prostate bed. PET/CT scans were blindly reviewed by two independent pairs of two experienced nuclear medicine physicians, discordant subgroup results being discussed to reach a consensus for positive, negative end equivocal results.

Results

PET results were concordant in 88 out of 92 local, regional and distant findings (Cohen’s kappa 0.929). In particular, results were concordant in all patients concerning local status, bone metastases and distant findings. Lymph-node results were concordant in 19 patients and different in 4 patients. On a per-patient basis results were concordant in 22 of 23 patients (14 positive, 5 negative and 3 equivocal). In only one patient was ACE PET/CT positive for nodal metastases while FCH PET/CT was overall negative; interestingly, the ACE-positive and FCH-negative lymph nodes became positive in a second FCH PET/CT scan performed a few months later.

Conclusion

Overall, ACE and FCH PET/CT showed excellent concordance, on both a per-lesion and a per-patient basis, suggesting that both tracers perform equally for recurrent prostate cancer staging.