Genotoxicity of bisphenol AF in rats: Detrimental to male reproductive system and probable stronger micronucleus induction potency than BPA.

Bisphenol AF (BPAF), as one of structural analogs of BPA, has been increasingly used in recent years. However, limited studies have suggested its adverse effects similar to or higher than BPA. In order to explore the general toxicity and genotoxicity of subacute exposure to BPAF, the novel 28-day multi-endpoint (Pig-a assay + micronucleus [MN] test + comet assay) genotoxicity evaluation platform was applied. Male rats were randomly distributed into seven main experimental groups and four satellite groups. The main experimental groups included BPAF-treated groups (0.5, 5, and 50 µg/kg·bw/d), BPA group (10 µg/kg·bw/d), two solvent control groups (PBS and 0.1% ethanol/99.9% oil), and one positive control group (N-ethyl-N-nitrosourea, 40 mg/kg bw). The satellite groups included BPAF high-dose recovery group (BPAF-HR), oil recovery group (oil-R), ENU recovery group (ENU-R), and PBS recovery group (PBS-R). All groups received the agents orally via gavage for 28 consecutive days, and satellite groups were given a recovery period of 35 days. Among all histopathologically examined organs, testis and epididymis damage was noticed, which was further manifested as blood-testis barrier (BTB) junction protein (Connexin 43 and Occludin) destruction. BPAF can induce micronucleus production and DNA damage, but the genotoxic injury can be repaired after the recovery period. The expression of DNA repair gene OGG1 was downregulated by BPAF. To summarize, under the design of this experiment, male reproductive toxicity of BPAF was noticed, which is similar to that of BPA, but its ability to induce micronucleus production may be stronger than that of BPA.

Genotoxic mode of action and threshold exploration of 2-methyl furan under 120-day sub-chronic exposure in male Sprague-Dawley rats.

2-Methylfuran (2-MF) is an important member of the furan family generated during food thermal processing. An in-vivo multiple endpoint genotoxicity assessment system was applied to explore the genotoxic mode of action and threshold of 2-MF. Male Sprague-Dawley rats received 2-MF by oral gavage at doses of 0.16, 0.625, 2.5, and 10 mg/kg.bw/day for 120 days. An additional 15 days were granted for recovery. The Pig-a gene mutation frequency of RET and RBC showed significant increases among the 2-MF groups on day 120. After a 15-day recovery period, the Pig-a gene mutation frequency returned to levels similar to those in the vehicle control. The tail intensity (TI) values of peripheral blood cells at a dose of 10 mg/kg.bw/day significantly increased from day 4 and remained at a high level after the recovery period. No statistical difference was found in the micronucleus frequency of peripheral blood between any 2-MF dose group and the corn oil group at any timepoint. 2-MF may not induce the production of micronuclei, but it could cause DNA breakage. It could not be ruled out that 2-MF may accumulate in vivo and cause gene mutations. Hence, DNA, other than the spindle, may be directly targeted. The mode of action of 2-MF may be that it was metabolized by EPHX1 to more DNA-active metabolites, thus leading to oxidative and direct DNA damage. The point of departure (PoD) of 2-MF-induced genotoxicity was derived as 0.506 mg/kg bw/day.

GPI-anchoring disorders and the heart: Is cardiomyopathy an overlooked feature?

Glycosylphosphatidylinositol anchoring disorders (GPI-ADs) are a subgroup of congenital disorders of glycosylation. GPI biosynthesis requires proteins encoded by over 30 genes of which 24 genes are linked to neurodevelopmental disorders. Patients, especially those with PIGA-encephalopathy, have a high risk of premature mortality which sometimes is attributed to cardiomyopathy. We aimed to explore the occurrence of cardiomyopathy among patients with GPI-ADs and to raise awareness about this potentially lethal feature. Unpublished patients with genetically proven GPI-ADs and cardiomyopathy were identified through an international collaboration and recruited through the respective clinicians. We also reviewed the literature for published patients with cardiomyopathy and GPI-AD and contacted the corresponding authors for additional information. We identified four novel and unrelated patients with GPI-AD and cardiomyopathy. Cardiomyopathy was diagnosed before adulthood and was the cause of early demise in two patients. Only one patients underwent cardiac workup after being diagnosed with a GPI-AD. All were diagnosed with PIGA-encephalopathy and three had a disease-causing variant at the same residue. The literature reports five additional children with GPI-AD related cardiomyopathy, three of which died before adulthood. We have shown that patients with GPI-ADs are at risk of developing cardiomyopathy and that regular cardiac workup with echocardiography is necessary.

Congenital diaphragmatic hernia in siblings with PIGA-related congenital disorder of glycosylation.

There are over 150 proteins involved in glycosylphosphatidylinositol (GPI)-anchored protein biosynthesis, a class within the larger category of congenital disorders of glycosylation (CDG). Pathogenic variants identified in phosphatidylinositol glycan class A protein (PIGA) are associated with X-linked PIGA-CDG, a GPI-anchor defect. The disease has primarily been characterized by hypotonia, epilepsy, and global developmental delay; however, only 89 known cases are reported, so the phenotypic spectrum has likely not yet been fully delineated. Congenital diaphragmatic hernia (CDH) has been reported in patients with various GPI-anchor related defects but has only been described in one prior individual with PIGA-CDG. Here, we describe the second and third reported cases of CDH in two brothers with PIGA-CDG caused by a pathogenic missense variant in PIGA: c.355C > T, p.R119W. Chromosomal microarray and whole exome sequencing did not reveal another plausible explanation for the CDH. We relate our patients' clinical features to the single previously reported individual with CDH and PIGA-CDG. We then compare this case series with the subset of individuals with CDH and other GPI-anchor defects. These findings suggest that CDH should be considered in the phenotypic disease spectrum of PIGA-CDG.

Induction of clastogenesis and gene mutations by carbamazepine (at its therapeutically effective serum levels) in mammalian cells and the dependence on human CYP2B6 enzyme activity.

Carbamazepine (CBZ, an antiepileptic) is metabolized by multiple CYP enzymes to its epoxide and hydroxides; however, whether it is genotoxic remains unclear. In this study, molecular docking (CBZ to CYPs) and cytogenotoxic toxicity assays were employed to investigate the activation of CBZ for mutagenic effects, in various mammalian cell models. Docking results indicated that CBZ was valid as a substrate of human CYP2B6 and 2E1, while not for CYP1A1, 1A2, 1B1 or 3A4. In the Chinese hamster (V79) cell line and its derivatives genetically engineered for the expression of human CYP1A1, 1A2, 1B1, 2E1 or 3A4 CBZ (2.5 ~ 40 µM) did not induce micronucleus, while in human CYP2B6-expressing cells CBZ significantly induced micronucleus formation. In a human hepatoma C3A cell line, which endogenously expressed CYP2B6 twofold higher than in HepG2 cells, CBZ induced micronucleus potently, which was blocked by 1-aminobenzotriazole (inhibitor of CYPs) and ticlopidine (specific CYP2B6 inhibitor). In HepG2 cells CBZ did not induce micronucleus; however, pretreatment of the cells with CICTO (CYP2B6 inducer) led to micronucleus formation by CBZ, while rifampicin (CYP3A4 inducer) or PCB126 (CYP1A inducer) did not change the negative results. Immunofluorescent assay showed that CBZ selectively induced centromere-free micronucleus. Moreover, CBZ induced double-strand DNA breaks (γ-H2AX elevation, by Western blot) and PIG-A gene mutations (by flowcytometry) in C3A (threshold being 5 µM, lower than its therapeutic serum concentrations, 17 ~ 51 µM), with no effects in HepG2 cells. Clearly, CBZ may induce clastogenesis and gene mutations at its therapeutic concentrations, human CYP2B6 being a major activating enzyme.

Analysis and Suppression of Nonlinear Error of Pendulous Integrating Gyroscopic Accelerometer at Instrument Level.

The error coefficients of the pendulous integrating gyroscopic accelerometer (PIGA) mainly include the bias, scale factor, and nonlinear error. Previous works have fully studied and suppressed the bias and scale factor of PIGAs. At present, the nonlinear error is the most critical factor restricting the measurement accuracy of PIGAs. To address this barrier, a study on the analysis and suppression of the nonlinear error of PIGAs at the instrument level was carried out. Firstly, the error model of a PIGA is established by kinematics and dynamics analyses. Then, nonlinear error is analyzed based on the established model. Finally, a suppression method for the nonlinear error is proposed based on the analysis results. The nonlinear error analysis found that (1) the nonlinear error includes a quadratic term error caused by unequal inertia and the inertia product, cross-coupling error is caused by lateral accelerations, and error is caused by unequal stiffness; (2) unequal inertia and the inertia product were the most critical factors resulting in nonlinear error. Based on the results in the nonlinear error analysis, the suppression method for error focuses on unequal inertia and the inertia product. The proposed method of analysis and suppression was validated experimentally as the quadratic term coefficient was reduced by an order of magnitude from 1.9 × 10-6/g0 to 1.91 × 10-7/g0.

Precise Measurement and Compensation of the Micro Product of Inertia for Float Assembly in Pendulous Integrating Gyroscopic Accelerometers.

Nonlinear error has become the most critical factor restricting the measurement accuracy of pendulous integrating gyroscopic accelerometers (PIGA) during their improvement. The key to nonlinear error suppression for PIGA is the precise measurement and compensation of the micro product of inertia (MPOI) of the float assembly. However, the existing equipment and procedure for product of inertia (POI) measurement and compensation do not meet the accuracy requirements for MPOI. To solve this problem, novel equipment and procedures are proposed for the measurement and compensation of MPOI. The principle of the proposed measurement method is to simulate the error produced by MPOI in PIGA by using a single-axis turntable to rotate the float assembly along the eccentric axis to generate a centrifugal moment due to MPOI. The principle of the proposed compensation method is to remove the asymmetric mass to reduce the MPOI to zero. Through experimental validation, it is concluded that: (1) the measurement and compensation accuracy of the proposed method are better than 1 × 10-10 kg·m2 and 3 × 10-10 kg·m2, respectively; (2) the proposed method is validated as the MPOI is reduced from 7.3 × 10-9 kg·m2 to 3 × 10-10 kg·m2 for a real float assembly in PIGA, and the quadratic error of PIGA is reduced from 10-5/g0 to 3 × 10-7/g0.

Characterization of benzo[a]pyrene and colchicine based on an in vivo repeat-dosing multi-endpoint genotoxicity quantitative assessment platform.

Two prototypical genotoxicants, benzo[a]pyrene (B[a]P) and colchicine (COL), were selected as model compounds to deduce their quantitative genotoxic dose-response relationship at low doses in a multi-endpoint genotoxicity assessment platform. Male Sprague-Dawley rats were treated with B[a]P (2.5-80 mg/kg bw/day) and COL (0.125-2 mg/kg bw/day) daily for 28 days. The parameters included were as follows: comet assay in the peripheral blood and liver, Pig-a gene mutation assay in the peripheral blood, and micronucleus test in the peripheral blood and bone marrow. A significant increase was observed in Pig-a mutant frequency in peripheral blood for B[a]P (started at 40 mg/kg bw/day on Day 14, started at 20 mg/kg bw/day on Day 28), whereas no statistical difference for COL was observed. Micronucleus frequency in reticulocytes of the peripheral blood and bone marrow increased significantly for B[a]P (80 mg/kg bw/day on Day 4, started at 20 mg/kg bw/day on Days 14 and 28 in the blood; started at 20 mg/kg bw/day on Day 28 in the bone marrow) and COL (started at 2 mg/kg bw/day on Day 14, 1 mg/kg bw/day on Day 28 in the blood; started at 1 mg/kg bw/day on Day 28 in the bone marrow). No statistical variation was found in indexes of comet assay at all time points for B[a]P and COL in the peripheral blood and liver. The dose-response relationships of Pig-a and micronucleus test data were analyzed for possible point of departures using three quantitative approaches, i.e., the benchmark dose, breakpoint dose, and no observed genotoxic effect level. The practical thresholds of the genotoxicity of B[a]P and COL estimated in this study were 0.122 and 0.0431 mg/kg bw/day, respectively, and our results also provided distinct genotoxic mode of action of the two chemicals.

The correlation between multiple congenital anomalies hypotonia seizures syndrome 2 and PIGA: a case of novel PIGA germline variant and literature review.

BACKGROUND: PIGA (PIG class A) gene codes for the PIG-A protein, which is a catalytic subunit of GPI-GlcNAc transferase. GPI-anchored proteins play an important role in the metabolism of mammals. Somatic variants of PIGA genes in bone marrow hematopoietic stem cells often result in paroxysmal nocturnal haemoglobinuria, and the germline PIGA variants cause multiple congenital anomalies hypotonia seizures syndrome 2 (MCAHS2) because of glycosylphosphatidylinositol metabolic abnormalities. METHODS: Whole exome sequencing was performed on peripheral blood sample of the patient with MCAHS2. A novel germline PIGA variant was found, and Sanger sequencing was performed as verification for the variant. After that, we used the keywords to retrieve relevant reports and provided a literature review. RESULTS: A novel hemizygous germline PIGA variant (NM_002641.3:c.971G > A) at exon4 was identified through whole exome sequencing. And it was a highly probable pathogenic variant. Sanger sequencing yielded consistent results. The missense variant cause change of p.(Cys324Tyr) in the transcription product according to the predicted outcomes. CONCLUSION: We reported a case of MCAHS2 caused by a novel PIGA variant. Following a review of the literature, we suggested that MCAHS2 should be considered as a disorder spectrum consisting of core symptoms, multi-system impairment, and premature death. The core symptoms include hypotonia, psychomotor delay, epilepsy (intractable epilepsy mostly) and early death. Core symptoms nearly happened to almost all patients. Meanwhile, MCAHS2 involves a wide range of organ and system impairments with changeable form.

General toxicity and genotoxicity of altertoxin I: A novel 28-day multiendpoint assessment in male Sprague-Dawley rats.

The mycotoxin altertoxin I (ATX-I) is one of secondary metabolites produced by Alternaria fungi and is frequently detected as food and feed contaminants. Little is known about the genotoxicity of the ATX-I. In order to evaluate potential genotoxicity and general toxicity of ATX-I, the novel 28-day multiendpoint (Pig-a assay + micronucleus [MN] test + comet assay) genotoxicity platform was applied. Male Sprague-Dawley (SD) rats were randomized to five groups (six rats per group), that is, a positive control group (N-ethyl-N-nitrosourea [ENU], 40 mg/kg.bw/d), two solvent control groups (PBS and corn oil), and two ATX-I-treated groups (low-dose group [1.10 µg/kg.bw/d] and high-dose group [5.51 µg/kg.bw/d]). Treatments were administered by oral gavage to male SD rats for 28 consecutive days. Histopathological damages in the liver, kidney, and spleen were observed, but without significant changes in hematological and serum biochemical parameters. Genotoxic endpoints indicated that ATX-I could cause DNA damage. To summarize, in a relatively low-dose range, ATX-I may not have direct genotoxicity in vivo but could induce liver, kidney, and spleen damage.

An Improved Online Self-Calibration Method Utilizing Angular Velocity Observation for Ultra High Accuracy PIGA-Based IMU.

In the field of ultra high accuracy inertial measurement unit (IMU), pendulous integrating gyroscopic accelerometer (PIGA) has become a research hot spot due to its high-end performance. However, PIGA is sensitive to angular velocity, and the calibration process of PIGA-based IMU will be very complicated, which makes online self-calibration difficult to implement. To solve the above problems, we proposed an online self-calibration method utilizing angular velocity observation. The main contributions of this study are twofold: (1) An error analysis of PIGA is conducted in this paper, and the error model has also been simplified to suit the self-calibration model. (2) An improved online self-calibration method utilizing angular observation based on a simplified PIGA error model is proposed in this study. Experimental results show that the self-calibration method proposed in this study can improve the PIGA online calibration accuracy effectively (with the accuracy within 0.02 m/s/pulse), which can improve the dynamic accuracy of the PIGA.

Pancytopenia in a Case of Aplastic Anaemia/Paroxysmal Nocturnal Haemoglobinuria Unmasked by SARS-CoV-2 Infection: A Case Report.

During an acute SARS-CoV-2 infection, a diagnosis of Aplastic Anaemia associated with Paroxysmal Nocturnal Haemoglobinuria (AA/PNH) was made in a 78-year-old woman who had presented to the emergency department with severe pancytopenia. It is possible that she had subclinical AA/PNH that was unmasked during the acute COVID-19 infection, but we can also suspect a direct role of the virus in the pathogenesis of the disease, or we can hypothesize that COVID-19 infection changed the phosphatidylinositol glycan class A (PIGA) gene pathway.

Elevated Endostatin Expression Is Regulated by the pIgA Immune Complex and Associated with Disease Severity of IgA Nephropathy.

BACKGROUND/AIMS: Renal vascular injury accounts for the poor outcomes of patients with IgA nephropathy (IgAN). In this study, we investigated whether endostatin, a potent inhibitor of angiogenesis, is associated with IgAN. METHODS: Serum endostatin levels were detected in patients with IgAN, disease controls, and healthy controls, and the correlation among endostatin and clinicopathologic manifestations, as well as prognosis in patients with IgAN, was analyzed. In addition, serum endostatin levels were compared in patients "before" and "after" treatment. Data on endostatin expression in the renal interstitium of patients with IgAN were downloaded and analyzed from the GSE35489 array in the GEO database. The poly-IgA1 (pIgA) immune complex is widely recognized as the "trigger" of IgAN initiation. pIgA in the plasma of patients was extracted and used to stimulate human glomerular endothelial cells (GECs). Endostatin, IL-6, and CXCL1 in the cell supernatant were detected by ELISA kits. RESULTS: We found that serum endostatin levels were significantly increased in patients with IgAN, as was endostatin expression in the renal interstitium. Patients with IgAN were divided into 2 groups according to the median value. The high endostatin expression group had significantly higher levels of serum creatinine and BUN and more severe tubular/interstitial damage. Moreover, patients with arteriolar injury and endothelial cell proliferation had higher serum endostatin levels. Patients with high serum endostatin levels had poor prognosis. According to the in vitro experiment, the GEC apoptosis rate and the supernatant levels of endostatin, IL-6, and CXCL1 were significantly increased following pIgA stimulation. CONCLUSION: Our study found that elevated endostatin expression was associated with disease severity and poor prognosis in patients with IgAN and can be upregulated by pIgA, but how it participates in the pathogenesis of IgAN deserves further exploration.

Rab11-FIP1 and Rab11-FIP5 Regulate pIgR/pIgA Transcytosis through TRIM21-Mediated Polyubiquitination.

Polymeric immunoglobulin receptor (pIgR)-mediated polymeric immunoglobulin A (pIgA) transcytosis across mucosal epithelial cells plays an essential role in mucosal immunity. The general trafficking process has been well investigated, yet the elaborate regulatory mechanisms remain enigmatic. We identified a new pIgR interacting protein, the Rab11 effector Rab11-FIP1. Rab11-FIP1 and Rab11-FIP5 knockdown additively impaired pIgA transcytosis in both polarized and incompletely polarized cells. Moreover, Rab11-FIP1 and Rab11-FIP5 knockdown exhibited more significant inhibitory effects on pIgA transcytosis in incompletely polarized cells than in polarized cells. Interestingly, the trafficking process of pIgA in incompletely polarized cells is distinct from that in polarized cells. In incompletely polarized cells, the endocytic pIgR/pIgA was first transported from the basolateral plasma membrane to the vicinity of the centrosome where Rab11-FIP1 and Rab11-FIP5 bound to it, before the Rab11a-positive endosomes containing pIgR/pIgA, Rab11-FIP1 and Rab11-FIP5 were further transported to the apical plasma membrane via Golgi apparatus. During the trafficking process, TRIM21 mediated the K11-linked polyubiquitination of Rab11-FIP1 and the K6-linked polyubiquitination of Rab11-FIP5 to promote their activation and pIgA transcytosis. This study indicates that polyubiquitinated Rab11-FIP1 and Rab11-FIP5 mediated by TRIM21 cooperatively facilitate pIgA transcytosis and provides new insights into the intracellular trafficking process of pIgA in incompletely polarized cells.

Lessons learned from 40 novel PIGA patients and a review of the literature.

OBJECTIVE: To define the phenotypic spectrum of phosphatidylinositol glycan class A protein (PIGA)-related congenital disorder of glycosylation (PIGA-CDG) and evaluate genotype-phenotype correlations. METHODS: Our cohort encompasses 40 affected males with a pathogenic PIGA variant. We performed a detailed phenotypic assessment, and in addition, we reviewed the available clinical data of 36 previously published cases and assessed the variant pathogenicity using bioinformatical approaches. RESULTS: Most individuals had hypotonia, moderate to profound global developmental delay, and intractable seizures. We found that PIGA-CDG spans from a pure neurological phenotype at the mild end to a Fryns syndrome-like phenotype. We found a high frequency of cardiac anomalies including structural anomalies and cardiomyopathy, and a high frequency of spontaneous death, especially in childhood. Comparative bioinformatical analysis of common variants, found in the healthy population, and pathogenic variants, identified in affected individuals, revealed a profound physiochemical dissimilarity of the substituted amino acids in variant constrained regions of the protein. SIGNIFICANCE: Our comprehensive analysis of the largest cohort of published and novel PIGA patients broadens the spectrum of PIGA-CDG. Our genotype-phenotype correlation facilitates the estimation on pathogenicity of variants with unknown clinical significance and prognosis for individuals with pathogenic variants in PIGA.

Mutations in PIGA cause a CD52-/GPI-anchor-deficient phenotype complicating alemtuzumab treatment in T-cell prolymphocytic leukemia.

OBJECTIVE: Infusional alemtuzumab followed by consolidating allogeneic hematopoietic stem cell transplantation in eligible patients is considered a standard of care in T-cell prolymphocytic leukemia (T-PLL). Antibody selection against CD52 has been associated with the development of CD52-negative leukemic T cells at time of relapse. Clinical implications and molecular mechanisms underlying this phenotypic switch are unknown. METHODS: We performed flow cytometry and real-time-PCR for CD52-expression and next generation sequencing for PIGA mutational analyses. RESULTS: We identified loss of CD52 expression after alemtuzumab treatment in two of 21 T-PLL patients resulting from loss of GPI-anchor expression caused by inactivating mutations of the PIGA gene. One patient with relapsed T-PLL exhibited a single PIGA mutation, causing a CD52-negative escape variant of the initial leukemic cell clone, preventing alemtuzumab-retreatment. The second patient with continued complete remission after alemtuzumab treatment harbored three different PIGA mutations that affected either the non-neoplastic T cell or the mononuclear cell compartment and resulted in symptomatic paroxysmal nocturnal hemoglobinuria. Next generation sequencing of T-PLL cells collected before the initiation of treatment revealed PIGA wild-type sequence reads in all 16 patients with samples available for testing. CONCLUSION: These data indicate that PIGA mutations were acquired during or after completion of alemtuzumab treatment.

In vitro genotoxicity study of silver nanoparticles and titanium dioxide nanoparticles.

Nanoparticles are widely used in cosmetic, pharmaceutical, and food industries, but their safety and genetic toxicity are still unclear. In this study, the genotoxicity of silver nanoparticles (AgNPs) and titanium dioxide nanoparticles (titanium dioxide nanoparticles) were evaluated by in vitro comet assay and PIG-A assay in TK6 cells. We exposed TK6 cells to two types of nanoparticles at the highest concentration of 200 µmol/L for 4 h and conducted the in vitro comet assay. We examined the mutation results of PIG-A gene in vitro after 4 h, 24 ho and 10 days of exposure, respectively. We also examined the endocytosis of nanoparticles in TK6 cells exposed to nanoparticles for 24 h. In the endocytosis assay, with the increase of nano-material concentration, the side scatter (SSC) of TK6 cells in flow cytometry showed a concentration-dependent and time-dependent increase, indicating that TK6 cells could uptake both types of nanoparticles. In the comet assay, AgNPs could induce a concentration-dependent increase in DNA tail intensity. However, titanium dioxide NPs could not induce the concentration-dependent increase of DNA fluorescence intensity of comet tail. In the PIG-A assay, both AgNPs and TiO2NPs did not induce PIG-A gene mutation frequency in TK6 cells. The results showed that AgNPs could induce DNA damage in TK6 cells, but could not induce increase of PIG-A gene mutation frequency. TiO2NPs neither induce DNA damage in TK6 cells nor increase PIG-A mutation frequency. Further tests are needed to determine whether TiO2NPs are genotoxic.

[Assessment of the genotoxicity of 2-methylfuran based on a multi-endpoint genotoxicity test system in vivo].

OBJECTIVE: This study was designed to determine the genotoxicity of 2-methylfuran based on a multi-endpoint genotoxicity test system. METHODS: The SPF-grade male SD rats(n = 30) were randomized to six treatment groups, i. e. 4 treatment groups(25, 50, 100 and 150 mg/kg), a control group(vegetable oil) and a positive groups(N-ethyl-N-nitrosourea, 80 mg/kg). All treatments were administrated by gavage for continuous 3 days. Tail vein blood for comet assay was collected at 3 h after the final administration. Pig-a gene mutation assays were performed on days 0(one day before gavage), 14 and 28. Micronucleus tests in peripheral blood using flow cytometry were performed on days 0 and 4. RESULTS: A statistically significant increase in tail intensity was observed at 150 mg/kg for peripheral blood in comet assay. There was no significant difference among the groups in mutant cell frequency of erythrocytes and reticulocytes at 2 timepoints in Pig-a gene mutation assay, and no significant difference among the groups in the frequency of micronucleus in micronucleus test. CONCLUSION: The result of genotoxicity tests suggested that 2-methylfuran was probably not mutagenic in vivo after acute exposure.

[Recommendations for design and statistical analysis of the rat Pig-a gene mutation assay].

OBJECTIVE: To make recommendations on the design and analysis of Piga gene mutation assay on the basis of the historical control data. METHODS: All negative historical control data( total: 128) were collected to create the historical control data base, and descriptive statistics was used to determine the distribution of the data. The power of the number of animals per group, number of measured cells per animal and number of groups were discussed through simulation test based on historical data base. RESULTS: The group mean of mutant red blood cells( RBCs~(CD59-)) and mutant reticulocytes ( RETs~(CD59-)) were 26. 63 × 10~(-6) and 35. 85 × 10~(-6), respectively, and the standard deviation were 27. 71 × 10~(-6) and 31. 06 × 10~(-6), respectively. By mapping the frequencies of data, the variables had skewed distributions and translated to normal distributions after logarithmic transformation. The confidence level for population means were 100% and 92% for RBCs( 1 × 10~6 cells per animal) and RETs( 0. 3 × 10~6 cells per animal), and it increased to 100% when 1 × 10~6 cells was scored for RETs. Group sizes of 5 had low statistical power while the minimal detectable difference was 2 times. The power had increased to > 80% when 4- or 5- fold of minimal detectable difference was employed. CONCLUSION: In brief, the recommendations include:① A log( 10) transformation of mutant frequencies often has been found satisfactory for data when parametric method such as an analysis of variance are used. ② Young adult animals( approximately 6 weeks of age rats) are recommended in this assay. ③ The recommended number of RETs and RBCs are > 1 × 10~6 and > 5 × 10~7, respectively. ④ Based on power calculations, 3 treatment groups and 1 negative control group are appropriate when fourfold increase was employed. ⑤ Group sizes of 6 or 7 are recommended but 5 analyzable animals per group may be acceptable when 4 test groups were used.

Development of clinical paroxysmal nocturnal haemoglobinuria in children with aplastic anaemia.

The clinical significance of paroxysmal nocturnal haemoglobinuria (PNH) in children with aplastic anaemia (AA) remains unclear. We retrospectively studied 57 children with AA between 1992 and 2010. During the follow-up, five patients developed clinical PNH, in whom somatic PIGA mutations were detected by targeted sequencing. The 10-year probability of clinical PNH development was 10·2% (95% confidence interval, 3·6-20·7%). Furthermore, the detection of minor PNH clones by flow cytometry at AA diagnosis was a risk factor for the subsequent development of clinical PNH. These patients with PNH clones at AA diagnosis should undergo periodic monitoring for potential clinical PNH development.