Clara Martínez

Methylene blue-photoinactivated plasma versus quarantine fresh frozen plasma in thrombotic thrombocytopenic purpura: a multicentric, prospective cohort study

Plasma exchange (PE) with plasma infusion is the treatment of choice for thrombotic thrombocytopenic purpura (TTP) but doubts remain as to whether all kinds of plasma are equally effective. A multicentric cohort study was conducted to compare methylene blue‐photoinactivated plasma (MBPIP) with quarantine fresh frozen plasma (qFFP) in the treatment of TTP. One hundred and two episodes of idiopathic TTP were included; MBPIP was used in 63 and qFFP in 39. The treatment schedule consisted of daily PE and costicosteroids, and the main end‐point was remission status on day 8. Patients treated with MBPIP required more PEs (median: 11 vs. 5, P = 0·002) and a larger volume of plasma (median: 485 ml/kg vs. 216 ml/kg, P = 0·007) to achieve a remission, and presented more recrudescences while on PE therapy (29 of 63 vs. 8 of 39, P = 0·02) than those receiving qFFP. After adjustment for possible confounding factors, the use of MBPIP was associated with a lower likelihood of remission on day 8 [Odds ratio (OR): 0·17; 95% confidence interval (CI): 0·06–0·47] and a higher risk of recrudescence while on treatment (OR: 4·2; 95% CI: 1·6–10·8). In conclusion, MBPIP is less effective than qFFP in the treatment of TTP.

Molecular and Insecticidal Characterization of a Cry1I Protein Toxic to Insects of the Families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae

ABSTRACT The most notable characteristic of Bacillus thuringiensis is its ability to produce insecticidal proteins. More than 300 different proteins have been described with specific activity against insect species. We report the molecular and insecticidal characterization of a novel cry gene encoding a protein of the Cry1I group with toxic activity towards insects of the families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae. PCR analysis detected a DNA sequence with an open reading frame of 2.2 kb which encodes a protein with a molecular mass of 80.9 kDa. Trypsin digestion of this protein resulted in a fragment of ca. 60 kDa, typical of activated Cry1 proteins. The deduced sequence of the protein has homologies of 96.1% with Cry1Ia1, 92.8% with Cry1Ib1, and 89.6% with Cry1Ic1. According to the Cry protein classification criteria, this protein was named Cry1Ia7. The expression of the gene in Escherichia coli resulted in a protein that was water soluble and toxic to several insect species. The 50% lethal concentrations for larvae of Earias insulana, Lobesia botrana, Plutella xylostella, and Leptinotarsa decemlineata were 21.1, 8.6, 12.3, and 10.0 μg/ml, respectively. Binding assays with biotinylated toxins to E. insulana and L. botrana midgut membrane vesicles revealed that Cry1Ia7 does not share binding sites with Cry1Ab or Cry1Ac proteins, which are commonly present in B. thuringiensis-treated crops and commercial B. thuringiensis-based bioinsecticides. We discuss the potential of Cry1Ia7 as an active ingredient which can be used in combination with Cry1Ab or Cry1Ac in pest control and the management of resistance to B. thuringiensis toxins.

Characterization of a Bacillus thuringiensis strain with a broad spectrum of activity against lepidopteran insects

The insect pathogen Bacillus thuringiensis is suitable for use in biological control, and certain strains have been developed as commercial bioinsecticides. The molecular and biological characterization of a Bacillus thuringiensis subsp. aizawai strain, named HU4‐2, revealed its potential as a bioinsecticide. The strain was found to contain eight different cry genes: cry1Ab, cry1Ad, cry1C, cry1D, cry1F, cry2, cry9Ea1, and a novel cry1I‐type gene. Purified parasporal crystals from strain HU4‐2 comprised three major proteins of 130–145 kDa, which were tested for their insecticidal potency to four species of Lepidoptera (Helicoverpa armigera, Spodoptera exigua, S. littoralis, and S. frugiperda) and three species of mosquito (Culex pipiens pipiens, Aedes aegypti, and Anopheles stephensi). The crystal proteins were highly toxic against all the species of Lepidoptera tested, moderately toxic against two of the mosquito species (C. pipiens and Ae. aegypti), but no toxicity was observed against a third species of mosquito (An. stephensi) at the concentrations used in our study. The LC50 values of the HU4‐2 Bt strain against H. armigera larvae (5.11 µg/ml) was similar to that of HD‐1 Bt strain (2.35 µg/ml), the active ingredient of the commercial product Dipel®. Additionally, the LC50 values of the HU4‐2 Bt strain against S. littoralis, S. frugiperda, and S. exigua (2.64, 2.22, and 3.38 µg/ml, respectively) were also similar to that of the Bt strain isolated from the commercial product Xentari® for the same three species of Spodoptera (1.94, 1.34, and 2.19 µg/ml, respectively). Since Xentari® is significantly more toxic to Spodoptera spp. than Dipel® and, reciprocally, Dipel® is significantly more toxic against H. armigera than Xentari®, we discuss the potential of the HU4‐2 strain to control all these important lepidopteran pests.

Host range and gene contents of Bacillus thuringiensis strains toxic towards Spodoptera exigua

Thirty‐five strains of the entomopathogenic bacterium Bacillus thuringiensis active on Spodoptera exigua, were characterized by means of serological identification and determination of cry gene contents by PCR. The insecticidal activity of these 35 strains was further confirmed against S. exigua and tested against two other species of the same genus: S. littoralis and S. frugiperda. The results indicate that serovars aizawai, thuringiensis, and kurstaki were the most frequent within S. exigua ‐active strains and that serovar aizawai had the highest number of strains exhibiting toxicity against the three species bioassayed. The presence in cry genes as determined by PCR suggests a non random distribution of some cry genes among serovars. Genes cry1C, cry1D, and cry1E, which are known to code for proteins toxic against Spodoptera species, were very common within S. exigua‐active strains, specially in those belonging to serovar aizawai. However, some strains harbouring one or more of these genes were not toxic to S. littoralis or S. frugiperda; and some strains lacking all of the Spodoptera‐active genes were found to be toxic to all three species. This suggests differences in the expression levels among strains bearing toxic genes and the involvement of other genes toxic to Spodoptera species. Since strains sharing the same cry genes exhibited different host ranges, the results indicate the need to perform toxicity bioassays in addition to other tests (serological identification and PCR) in order to determine the insecticidal activity of B. thuringiensis strains.

Risk of thrombosis according to need of phlebotomies in patients with polycythemia vera treated with hydroxyurea.

Hematocrit control below 45% is associated with a lower rate of thrombosis in polycythemia vera. In patients receiving hydroxyurea, this target can be achieved with hydroxyurea alone or with the combination of hydroxyurea plus phlebotomies. However, the clinical implications of phlebotomy requirement under hydroxyurea therapy are unknown. The aim of this study was to evaluate the need for additional phlebotomies during the first five years of hydroxyurea therapy in 533 patients with polycythemia vera. Patients requiring 3 or more phlebotomies per year (n=85, 16%) showed a worse hematocrit control than those requiring 2 or less phlebotomies per year (n=448, 84%). There were no significant differences between the two study groups regarding leukocyte and platelet counts. Patients requiring 3 or more phlebotomies per year received significantly higher doses of hydroxyurea than the remaining patients. A significant higher rate of thrombosis was found in patients treated with hydroxyurea plus 3 or more phlebotomies per year compared to hydroxyurea with 0–2 phlebotomies per year (20.5% vs. 5.3% at 3 years; P<0.0001). In multivariate analysis, independent risk factors for thrombosis were phlebotomy dependency (HR: 3.3, 95%CI: 1.5–6.9; P=0.002) and thrombosis at diagnosis (HR: 4.7, 95%CI: 2.3–9.8; P<0.0001). The proportion of patients fulfilling the European LeukemiaNet criteria of resistance/intolerance to hydroxyurea was significantly higher in the group requiring 3 or more phlebotomies per year (18.7% vs. 7.1%; P=0.001) mainly due to extrahematologic toxicity. In conclusion, phlebotomy requirement under hydroxyurea therapy identifies a subset of patients with increased proliferation of polycythemia vera and higher risk of thrombosis.

ADAMTS‐13 activity and von Willebrand factor levels in methylene blue photo‐inactivated plasma processed by either the Springe method or an ‘in house’ system

Background and Objectives  Methylene blue photo‐inactivated plasma (MBPIP) has been reported to be less effective than fresh‐frozen plasma (FFP) in the treatment of thrombotic thrombocytopenic purpura, which suggests a reduced content of the von Willebrand factor metalloprotease ADAMTS‐13 in MBPIP.

Essential thrombocythaemia with mutation in MPL: clinicopathological correlation and comparison with JAK2V617F-mutated and CALR-mutated genotypes

Aim To characterise the clinical and histological features of MPL-mutated essential thrombocythaemia (ET). Patients and methods Bone marrow biopsies of 175 patients with ET were centrally reviewed according to the 2016 WHO classification, including 42 cases with MPL mutation, 98 JAK2V617F-mutated and 35 CALR-mutated. Clinical and histological features were compared among the three genotypes included in the current 2016 WHO classification and among the different types of MPL mutations. Results Patients with MPL-mutated ET were significantly older than those with the other genotypes. Haematological values at diagnosis were similar among MPL-mutated and CALR-mutated ET, with both genotypes showing higher platelet counts and lower haemoglobin values than ET with JAK2V617F genotype. In the bone marrow, the median number of megakaryocytes was higher in MPL and CALR than in JAK2V617F genotype (16, 19 and 14 megakaryocytes per ×20 power field, respectively, p=0.004). Histological features of prefibrotic myelofibrosis were rarely observed in MPL genotype, whereas sinusoidal hyperplasia, dense clusters of megakaryocytes and reticulin fibrosis were more frequent in CALR-mutated ET, with 11% of such cases fulfilling WHO 2016 histological criteria of prefibrotic myelofibrosis. With a median follow-up of 3.5 years, no significant differences were seen among genotypes regarding survival, vascular complications or myelofibrotic transformation. There were no significant differences in the clinical data or in the histological characteristics depending on the type of MPL mutation. Conclusion MPL and CALR ET genotypes share clinical and histological characteristics. In contrast to CALR genotype, features of prefibrotic myelofibrosis are uncommon in MPL-mutated ET.