A Review of L-Asparaginase Hypersensitivity in Paediatric Acute Lymphoblastic Leukaemia Patients with Regard to the Measurement of Anti-Asparaginase Antibodies and Their Genetic Predisposition

L-asparaginase is effective as part of the first line childhood acute lymphoblastic leukaemia (ALL) treatment regimen but suffers the risk of antibody production causing immune-mediated sequelae. This article aimed to describe the clinical implication of L-asparaginase hypersensitivity and review the types of antibodies and genetic polymorphisms contributing to it. Clinical or subclinical L-asparaginase hypersensitivity may lead to suboptimum therapeutic effect and jeopardise the clinical outcome in ALL children. Anti-asparaginase antibodies immunoglobulin (Ig)G, IgM and IgE were identified in the L-asparaginase hypersensitivities. Enzyme-linked immunosorbent assay (ELISA) is commonly used to quantify the IgG and IgM levels. The role of IgE in mediating L-asparaginase hypersensitivity is contradictory. Moreover, the presence of antibodies may not necessarily correlate inversely with the L-asparaginase efficacies in some studies. Patients with specific genetic variants have been shown to be more susceptible to clinical hypersensitivity of L-asparaginase. With the advance of technology, gene polymorphisms have been identified among Caucasians using whole-genome or exon sequencing, but the evidence is scanty among Asians. There is lack of pre-clinical study models that could help in understanding the pathophysiological pathway co-relating the gene expression and anti-asparaginase antibody formation. In conclusion, future research studies are required to fill the current gap in understanding the immune mediated reactions towards L-asparaginase upon its administration and its potential impact to the disease outcome.

P-524 Bi-allelic CFAP61 variants cause male infertility in humans and mice with severe oligoasthenoteratozoospermia

Study question

Are mutations in cilia and flagella-associated protein 61 (CFAP61) associated with human male infertility?

Summary answer

Bi-allelic variants ([NM_015585.4: c.1654C>T (p.R552C) and c.2911G>A (p.D971N), c.144-2A>G and c.1666G>A (p.G556R)] in CFAP61 were identified as contributory genetics factor in severe oligoasthenoteratozoospermia (OAT).

What is known already

Cfap61 knockout mice were infertile due to multiple morphological abnormalities of the sperm flagella (MMAF). However, so far there is no direct evidence that mutations of CFAP61 cause OAT and male infertility.

Study design, size, duration

Variant screening was performed by whole-exome sequencing (WES) from 325 infertile patients with OAT and 392 fertile individuals. A knockout mouse model was generate to confirm the candidate disease-causing gene, intracytoplasmic sperm injection (ICSI) was used to evaluate the efficiency of clinical treatment.

Participants/materials, setting, methods

A total 325 OAT-affected patients and 392 men with normal fertility were recruited from China. WES was performed, followed by Sanger sequencing validation. In silico bioinformatics predictions and in vitro functional analyses were performed to evaluate the impacts of candidate disease-causing variants. Hematoxylin and eosin (H&E) staining, electron microscopy, and immunofluorescence assays were performed to evaluate the sperm morphology. Two OAT-affected men with CFAP61 variants were treated by ICSI, and pregnancy outcomes were followed.

Main results and the role of chance

We identified bi-allelic CFAP61 variants [NM_015585.4: c.1654C>T (p.R552C) and c.2911G>A (p.D971N), c.144-2A>G and c.1666G>A (p.G556R)] in two (0.62%) of the 325 OAT-affected men. In silico bioinformatics analysis predicted that all four variants were deleterious, and in vitro functional analysis confirmed the deleterious effects of the mutants. Notably, H&E staining and electron microscopy analyses of the spermatozoa revealed multiple morphological abnormalities of sperm flagella, the absence of central pair microtubules, and mitochondrial sheath malformation in sperm flagella from man with CFAP61 variants. Further immunofluorescence assays revealed markedly reduced CFAP61 staining in the sperm flagella. In addition, Cfap61-deficient mice showed the OAT phenotype, suggesting that loss of function of CFAP61 was the cause of OAT. Two individuals accepted ICSI therapy using their own ejaculated sperm, and one of them succeeded in fathering a healthy baby.

Limitations, reasons for caution

Limitations include the lack of in vivo data from the one of patients, and the exact molecular mechanism should be further investigated.

Wider implications of the findings

Our findings indicate that CFAP61 is essential for spermatogenesis and that bi-allelic CFAP61 variants lead to OAT and male infertility in humans and mice. In addition, our results show that ICSI treatment can be recommended for CFAP61-related OAT.

Trial registration number

not applicable

Boron carbide composites with highly aligned graphene nanoplatelets: light-weight and efficient electromagnetic interference shielding materials at high temperatures

B₄C-based ceramic composites containing 0-2 vol% highly aligned graphene nanoplatelets (GNPs) are fabricated. The electromagnetic interference (EMI) shielding properties of the obtained composites are investigated at X-band (8.2-12.4 GHz) frequency range from room-temperature up to 800 °C. All composites exhibit outstanding EMI shielding properties with satisfactory frequency- and thermal-stability. The shielding effectiveness (SE) of GNP/B₄C composites increases monotonically with increasing GNP loading. Superior room-temperature SE close to 40 dB is achieved with only 2 vol% GNPs and high SE around 35 dB still persists at 800 °C. Considering their relatively low density, GNP/B₄C composites possess a high specific shielding effectiveness (SSE) of 16 dB cm³ g^-1 which is among the highest values in reported ceramic-based shielding composites. Especially, the GNP/B₄C composite with 2 vol% GNPs exhibits the highest SSE/t (SSE divided by thickness) values at temperatures above 200 °C for all reported shielding composites, indicating that GNP/B₄C composites belong to the most promising high-temperature shielding composites. The excellent shielding properties of GNP/B₄C composites arise mainly from the high electrical conductivity, high dielectric loss and the multiple reflections by the highly aligned and large-sized GNP layers.

Effect of temperature on endogenous hormone levels and opposite phyllotaxy in maize leaf primordial

Newly identified maize (Zea mays) mutants with opposite leaf phyllotaxy are important in the study of the maize crop. Previous studies have revealed the developmental mechanism of opposite phyllotaxy on the physiological, cellular, and molecular levels. However, there have been few reports regarding the effects of changes in endogenous hormone levels in maize leaf primordia under different conditions. We conducted field studies to examine the influence of different environmental factors on leaf primordia differentiation. Our results indicated that compared with other major environmental factors, temperature was significantly positively correlated with the ratio of maize plants with opposite phyllotaxy. We examined endogenous hormone levels in maize at different temperatures using an enzyme-linked immunosorbent assay. The results showed that the ratio of maize plants with opposite phyllotaxy was mainly influenced by the cytokinin/auxin ratio. In addition, at the same temperature, the ratio of cytokinin/auxin in maize with opposite phyllotaxy was significantly higher than that near isogenic lines with alternate phyllotaxy.

Using SNP array to identify aneuploidy and segmental imbalance in translocation carriers

Translocation is one of the more common structural rearrangements of chromosomes, with a prevalence of 0.2%. The two most common types of chromosomal translocations, Robertsonian and reciprocal, usually result in no obvious phenotypic abnormalities when balanced. However, these are still associated with reproductive risks, such as infertility, spontaneous abortion and the delivery of babies with mental retardation or developmental delay.

In recent years, array-based whole-genome amplification (WGA) technologies, including microarray comparative genomic hybridization (array CGH; aCGH) and single-nucleotide polymorphism (SNP) micro-arrays, have enabled the screening of every chromosome for whole-chromosome aneuploidy and segmental imbalance. These techniques have been shown to have clinical application for translocation carriers. Promising studies have indicated that array-based PGD of translocation carriers can lead to transfer pregnancy rates of 45–70% [2].

In addition to genetic testing techniques, the embryo biopsy stage (polar body, cleavage embryo or blastocyst) and the mode of embryo transfer (fresh or frozen embryos) can affect the outcome of PGD. It is now generally recommended that blastomere biopsy should be replaced by blastocyst biopsy to avoid a high mosaic rate and biopsy-related damage to cleavage-stage embryos, which might affect embryo development. However, more clinical data are required to confirm that the technique of SNP array-based PGD (SNP-PGD) combined with trophectoderm (TE) biopsy and frozen embryo transfer (FET) is superior to traditional FISH-PGD combined with Day 3 (D3) blastomere biopsy and fresh embryo transfer.

Molecular mapping of genes for opposite leafing in maize using simple-sequence repeat markers

Maize with opposite phyllotaxy (OP) and also initiating ears in opposite pairs is an aberrant mutant and also precious material for maize breeding and plant evolution studies. Mapping and identifying the markers closely linked to genes for the OP trait are essential for cloning the gene and marker-assisted selection in breeding. We established H14D, a near-isogenic line of the OP trait with H53 genetic background. We found that the OP trait is regulated by two independent dominant genes with mutually complementary relations, named Opp-1 and Opp-2. Screening of seven simple-sequence repeat (SSR) markers among the 105 pairs of SSR primers showed polymorphism between the inbred lines H14D and H53. The polymorphic SSR markers were then used to determine linkage with the trait in an F(2) population with 441 progeny, suggesting that SSR marker umc2094 in the Bin2.01 region is linked with Opp-1 at 6.7 cM, and bnlg1831 in Bin2.06 is linked with Opp-2 at 6.1 cM. Further investigation showed that bnlg1092 and umc1028 are linked to Opp-1 and Opp-2 genes, with genetic distances of 12.2 and 1.9 cM. It was also found that the four SSR markers flank the two OP genes, respectively. These results will be useful for marker-assisted selection breeding of OP maize and will also strengthen the basis for cloning of the opposite leafing gene.

Activation of a protease cascade involved in patterning the Drosophila embryo

Dorsoventral patterning of the Drosophila embryo is initiated by a ventralizing signal. Production of this signal requires the serine proteases Gastrulation Defective (GD), Snake, and Easter, which genetic studies suggest act sequentially in a cascade that is activated locally in response to a ventral cue provided by the pipe gene. Here, we demonstrate biochemically that GD activates Snake, which in turn activates Easter. We also provide evidence that GD zymogen cleavage is important for triggering this cascade but is not spatially localized by pipe. Our results suggest that a broadly, rather than locally, activated protease cascade produces the ventralizing signal, so a distinct downstream step in this cascade must be spatially regulated to restrict signaling to the ventral side of the embryo.

[Effect of BSAP/Pax-5 on the development, proliferation and differentiation of B lymphocyte cell]

BSAP, a B cell lineage-specific activator protein, is a nucleus transcription factor and is encoded by the Pax-5 gene. It is a critical modulator of B cell development, proliferation and differentiation. BSAP also influences B cell immunoglobulin secretion at later stages of B cell differentiation.

[Effect and mechanism of active fraction A guizhi decoction on dual-directional thermoregulation: effect on heat shock protein in hypothalamus of rats]

OBJECTIVE

To investigate the effect of active fraction A in Guizhi Decoction (Fr.A) on dual-directional thermoregulation and its mechanism of influencing heat shock protein (HSP) in hypothalamus.

METHOD

Using Western blot method to measure HSP of hypothalamus in febrile and hypothermal rats.

RESULTS

Regulating the body temperature in dual-direction, Fr.A could antagonize the decrease of HSP contents of hypothalamus in hypothermal rats induced by aminopyrine, and abate the HSP content in febrile rats induced by yeast.

CONCLUSION

Fr.A adjusts the body temperature through regulating the contents of HSP of hypothalamus in febrile and hypothermal rats.

Gastrulation defective is a serine protease involved in activating the receptor toll to polarize the Drosophila embryo

The dorsoventral axis of the Drosophila embryo is induced by a ventrally restricted ligand for the receptor Toll. The Toll ligand is generated by a proteolytic processing reaction, which occurs at the end of a proteolytic cascade and requires the gastrulation defective (gd), nudel, pipe, and windbeutel genes. Here we demonstrate that the GD protein is a serine protease and that the three other genes act to restrict GD activity to the ventral side of the embryo. Our data support a model in which the GD protease catalyzes the ventral activation of the proteolytic cascade that produces the Toll ligand.