[Childhood acute promyelocytic leukemia complicated with thrombosis: four cases and literatures review].

Objective: To investigate the clinical characteristics and prognosis of children with acute promyelocytic leukemia (APL) complicated with thrombosis. Methods: The clinical profiles of four APL patients complicated with thrombosis treated at the First Affiliated Hospital of Zhengzhou University between January 2012 and December 2019 were reviewed. Literature search and review covered the China national knowledge infrastructure, Wanfang database, China biology medicine disc and PubMed using the key words of "acute promyelocytic leukemia" and "thrombosis" up to June 2020. Results: Four patients included one male and three females with an age range of 4-13 years. In two patients, thrombosis occurred intracranially, both patients presented with seizure and hemiplegia. In one patient, thrombosis occurred in spleen, the patient presented with severe abdominal pain. In the last patient, thrombosis occurred in liver, the patient presented with abdominal pain, distension and ascites. Thrombosis occurred during the course of retinoic acid treatment in three patients, it occurred before the initiation of the treatment in one patient. Thrombosis was confirmed by imaging examination in all four patients. After thrombolytic and anticoagulation treatment, the vessels were recanalized and the symptoms were alleviated in 3 cases, the fourth patient died of hepatic venous thrombosis. Literature search identified no similar reports in Chinese journals, 11 case reports were found in English journals. In these 15 patients, 9 were male and 6 females with an age range of 3-16 years. Thrombus located in brain in 6 cases, in lower limbs for 3 cases, in liver for 3 cases, in spleen in 2 cases and in coronary artery for 1 case. In 10 cases thrombosis occurred before the induce treatment and in 5 cases occurred during the induction treatment. After surgery, thrombolytic and anticoagulation treatment vascular recanalization was observed in 10 patients, and in those patients, the symptoms were relieved, death occurred in 5 patients, including three patients with hepatic venous thrombosis. Conclusions: Thrombosis may occur before or during the treatment for APL. Both arterial and venous thrombosis may occur in patients with APL. Imaging examination is a reliable method for its diagnosis. After treatment, most patients had good prognosis with recanalization of blood vessels, but the mortality rate was high for patients with hepatic venous thrombosis.

[Heterologous extracellular expression and initial characterization of the peroxisomal catalase from the methylotrophic yeast Hansenula polymorpha in Pichia pastoris].

Catalase is well known to eliminate H2O2 in cells and reduces the toxicity of peroxide compounds. A catalase gene HpCat1 of methylotrophic yeast Hansenula polymorpha without the part coding the native signal peptide was cloned into expression vector pYM3165 and then integrated into genome of Pichia pastoris GS115 by electroporation. The result of the enzyme activity assay and SDS-PAGE demonstrated that the recombinant protein (HpCAT1) of H. polymorpha was extracellularly expressed in P. pastoris. The expressed catalase was recovered from the culture supernatant of P. pastoris GS 115 and purified by (NH4) 2SO4 fractionation and Ni-NTA affinity chromatography. The main biochemical properties of the recombinant protein HpCAT1, such as thermodependence and thermostability, pH optimum and pH stability, as well as the effect of metal ions and chemicals, were characterized. With H2O2 as the substrate, HpCAT1 displayed pH and tem- perature optima of approximately 2.6 and 45°C,respectively. The recombinant HpCAT1 activity was inhibited by 1 mM Hg2+ and Cu2+, but was highly enhanced by 1.0 mM Fe2+.

High level expression of a recombinant acid phytase gene in Pichia pastoris.

AIMS: To achieve high phytase yield with improved enzymatic activity in Pichia pastoris. METHODS AND RESULTS: The 1347-bp phytase gene of Aspergillus niger SK-57 was synthesized using a successive polymerase chain reaction and was altered by deleting intronic sequences, optimizing codon usage and replacing its original signal sequence with a synthetic signal peptide (designated MF4I) that is a codon-modified Saccharomyces cerevisiae mating factor alpha-prepro-leader sequence. The gene constructs containing wild type or modified phytase gene coding sequences under the control of the highly-inducible alcohol oxidase gene promoter with the MF4I- or wild type alpha-signal sequence were used to transform Pichia pastoris. The P. pastoris strain that expressed the modified phytase gene (phyA-sh) with MF4I sequence produced 6.1 g purified phytase per litre of culture fluid, with the phytase activity of 865 U ml(-1). The expressed phytase varied in size (64, 67, 87, 110 and 120 kDa), but could be deglycosylated to produce a homogeneous 64 kDa protein. The recombinant phytase had two pH optima (pH 2.5 and pH 5.5) and an optimum temperature of 60 degrees C. CONCLUSIONS: The P. pastoris strain with the genetically engineered phytase gene produced 6.1 g l(-1) of phytase or 865 U ml(-1) phytase activity, a 14.5-fold increase compared with the P. pastoris strain with the wild type phytase gene. SIGNIFICANCE AND IMPACT OF THE STUDY: The P. pastoris strain expressing the modified phytase gene with the MF4I signal peptide showed great potential as a commercial phytase production system.

Study of urinary 8-hydroxydeoxyguanosine as a biomarker of oxidative DNA damage in diabetic nephropathy patients.

Increased oxidative stress induced by hyperglycemia may contribute to the pathogenesis of diabetic complications. Urinary 8-hydroxydeoxyguanosine (8-OHdG) has been reported to serve as a sensitive biomarker of oxidative DNA damage and also of oxidative stress. This article studied oxidative DNA damage in patients with diabetic nephropathy and in healthy control subjects by urinary 8-OHdG evaluations. Contents of 8-OHdG in urine were analyzed by capillary electrophoresis with end-column amperometric detection (CE-AD) after a single-step solid-phase extraction (SPE). Levels of urinary 8-OHdG in diabetic nephropathy patients with macroalbuminuria was significant higher than in control subjects (5.72 +/- 6.89 micromol/mol creatinine versus 2.33 +/- 2.83 micromol/mol creatinine, P = 0.018). A significant difference of 24 h urinary 8-OHdG excretions exists between the patients with macroalbuminuria and the patients with normoalbuminuria (19.2 +/- 16.8 microg/24 h versus 8.1 +/- 1.7 microg/24 h, P = 0.015). There was a positive correlation between urinary excretion of 8-OHdG and glycosylated hemoglobin (HbA1c) (r = 0.287, P = 0.022). A weak correlation exists between the levels of 8-OHdG and triglyceride (r = 0.230, P = 0.074). However, the urinary 8-OHdG contents are not correlated with blood pressure and total cholesterol. The increased excretion of urinary 8-OHdG is seen as indicating an increased systemic level of oxidative DNA damage in diabetic nephropathy patients.