Structural Study of SARS-CoV-2 Antibodies Identifies a Broad-Spectrum Antibody That Neutralizes the Omicron Variant by Disassembling the Spike Trimer.

The continuous emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants poses new challenges in the fight against the coronavirus disease 2019 (COVID-19) pandemic. The newly emerging Omicron strain caused serious immune escape and raised unprecedented concern all over the world. The development of an antibody targeting a conserved and universal epitope is urgently needed. A subset of neutralizing antibodies (NAbs) against COVID-19 from convalescent patients were isolated in our previous study. In this study, we investigated the accommodation of these NAbs to SARS-CoV-2 variants of concern (VOCs), revealing that IgG 553-49 neutralizes pseudovirus of the SARS-CoV-2 Omicron variant. In addition, we determined the cryo-electron microscopy (cryo-EM) structure of the SARS-CoV-2 spike (S) protein complexed with three monoclonal antibodies targeting different epitopes, including 553-49, 553-15, and 553-60. Notably, 553-49 targets a novel conserved epitope and neutralizes the virus by disassembling S trimers. IgG 553-15, an antibody that neutralizes all of the VOCs except Omicron, cross-links two S trimers to form a trimer dimer, demonstrating that 553-15 neutralizes the virus by steric hindrance and virion aggregation. These findings suggest the potential to develop 553-49 and other antibodies targeting this highly conserved epitope as promising therapeutic reagents for COVID-19. IMPORTANCE The emergence of the Omicron strain of SARS-CoV-2 caused higher immune escape, raising unprecedented concerns about the effectiveness of antibody therapies and vaccines. In this study, we identified a SARS-CoV-2 neutralizing antibody, 553-49, which neutralizes all variants by targeting a completely conserved novel epitope. In addition, we revealed that IgG 553-15 neutralizes SARS-CoV-2 by cross-linking virions and that 553-60 functions by blocking receptor binding. Comparison of different receptor binding domain (RBD) epitopes revealed that the 553-49 epitope is hidden in the S trimer and keeps a high degree of conservation during SARS-CoV-2 evolution, making 553-49 a promising therapeutic reagent against the emerging Omicron and future variants of SARS-CoV-2.

SlIAA23-SlARF6 module controls arbuscular mycorrhizal symbiosis by regulating strigolactone biosynthesis in tomato.

Auxins are a class of phytohormones with roles involved in the establishment and maintenance of the arbuscular mycorrhizal symbiosis (AMS). Auxin response factors (ARFs) and Auxin/Indole-acetic acids (AUX/IAAs), as two transcription factors of the auxin signaling pathway, coregulate the transcription of auxin response genes. However, the interrelation and regulatory mechanism of ARFs and AUX/IAAs in regulating AMS are still unclear. In this study, we found that the content of auxin in tomato roots increased sharply and revealed the importance of the auxin signaling pathway in the early stage of AMS. Notably, SlARF6 was found to play a negative role in AMF colonization. Silencing SlARF6 significantly increased the expression of AM-marker genes, as well as AMF-induced phosphorus uptake. SlIAA23 could interact with SlARF6 in vivo and in vitro, and promoted the AMS and phosphorus uptake. Interestingly, SlARF6 and SlIAA23 played a contrary role in strigolactone (SL) synthesis and accumulation in AMF-colonized roots of tomato plants. SlARF6 could directly bind to the AuxRE motif of the SlCCD8 promoter and inhibited its transcription, however, this effect was attenuated by SlIAA23 through interaction with SlARF6. Our results suggest that SlIAA23-SlARF6 coregulated tomato-AMS via an SL-dependent pathway, thus affecting phosphorus uptake in tomato plants.

A novel mutation of the RPGRIP1L gene in a Chinese boy with Joubert syndrome with oculorenal involvement.

BACKGROUND: Joubert syndrome (JS) is a rare genetically heterogeneous primary ciliopathy characterized by a pathognomonic cerebellar and brainstem malformation, the "molar tooth sign", and variable organ involvement (such as eye, kidney, liver, and skeleton). Here, we present a case of JS in a Chinese boy. CASE PRESENTATION: An 11-year-old Chinese boy presented with neonatal asphyxiation and hypoxia, strabismus, subsequent developmental delay, ataxia and end-stage kidney disease (ESKD). Routine blood tests showed severe anemia, increasing blood urea nitrogen and creatinine, elevated parathyroid hormone, hypocalcemia, hypokalemia and metabolic acidosis. Urine tests showed mild proteinuria. Ultrasound showed two small kidneys. Brain magnetic resonance imaging (MRI) showed dysplasia of the cerebellar vermis and extension of the upper cerebellar feet with the "molar tooth sign". Genetic analysis showed novel compound heterozygous mutations in the RPGRIP1L gene [p.L447fs*7(p.Leu447fsTer7) and p.G908V (p.Gly908Val)]. CONCLUSION: In the present study, we identified novel compound heterozygous mutations in the RPGRIP1L gene in a Chinese boy. The clinical and genetic findings of this study will expand the understanding of JS.

Sesquiterpenes from two Compositae plants as promising inhibitors to nuclear hormone receptor 3 of Tribolium castaneum.

Essential oils (EOs) and their volatile secondary metabolites have been proved to be effective on storage pests control, while restricted on the application due to unclear mechanism. Molecular dynamics (MD) simulations and binding free energies analysis provided an effective approach to reveal mechanism on conformational calculation. In this work, the insecticidal and repellent capacities of Praxelis clematidea and Ageratum houstonianum oils and their main components identified by gas chromatography-mass spectrometry (GC-MS) were scientifically measured. Interestingly, P. clematidea oil exhibited strong fumigant toxicity against Tribolium castaneum (LC50 = 7.07 mg/L air). Moreover, two EOs exhibited over 80% repellent rate against T. castaneum at the highest concentration of 78.63 nL/cm2. Furthermore, hundreds of enzymes related to the regulation of biological processes of T. castaneum were screened to explore the underlying molecular mechanism and develop promising insecticides. Besides, top hits were subjected to MD simulations and binding free energies analysis to elucidate complex inter-molecular stability and affinity over simulated time. The results demonstrated that isolongifolene, δ-cadinene, ß-caryophyllene and caryophyllene oxide were prioritized as they were establishing conserved and stable interactions with residues of nuclear hormone receptor 3 (TcHR3) of T. castaneum, which suggested that the four sesquiterpenes have potential to be promising insecticides on storage pests control.

A phase 1b study of isatuximab plus pomalidomide/dexamethasone in relapsed/refractory multiple myeloma.

This phase 1b dose-escalation study evaluated isatuximab plus pomalidomide/dexamethasone in patients with relapsed/refractory multiple myeloma (RRMM). Patients who had received ≥2 prior MM therapies, including lenalidomide and a proteasome inhibitor (PI), were enrolled and received isatuximab at 5, 10, or 20 mg/kg (weekly for 4 weeks, followed by every 2 weeks), pomalidomide 4 mg (days 1-21), and dexamethasone 40 mg (weekly) in 28-day cycles until progression/intolerable toxicity. The primary objective was to determine the safety and recommended dose of isatuximab with this combination. Secondary objectives included evaluation of pharmacokinetics, immunogenicity, and efficacy. Forty-five patients received isatuximab (5 [n = 8], 10 [n = 31], or 20 [n = 6] mg/kg). Patients received a median of 3 (range, 1-10) prior lines; most were refractory to their last regimen (91%), with 82% lenalidomide-refractory and 84% PI-refractory. Median treatment duration was 9.6 months; 19 patients (42%) remain on treatment. Most common adverse events included fatigue (62%), and upper respiratory tract infection (42%), infusion reactions (42%), and dyspnea (40%). The most common grade ≥3 treatment-emergent adverse event was pneumonia, which occurred in 8 patients (17.8%). Hematologic laboratory abnormalities were common (lymphopenia, leukopenia, anemia, 98% each; neutropenia, 93%; and thrombocytopenia, 84%). Overall response rate was 62%; median duration of response was 18.7 months; median progression-free survival was 17.6 months. These results demonstrate potential meaningful clinical activity and a manageable safety profile of isatuximab plus pomalidomide/dexamethasone in heavily pretreated patients with RRMM. The 10 mg/kg weekly/every 2 weeks isatuximab dose was selected for future studies. This trial was registered at www.clinicaltrials.gov as #NCT02283775.

Beta-klotho in type 2 diabetes mellitus: From pathophysiology to therapeutic strategies.

Type 2 diabetes mellitus (T2DM) has become a global health problem with no cure. Despite lifestyle modifications and various pharmaceutical options, the achievement of stable and durable glucose control along with effective prevention of T2DM-related cardiovascular complications remains a challenging task in clinical management. With its selective high abundance in metabolic tissues (adipose tissue, liver, and pancreas), ß-Klotho is the essential component of fibroblast growth factor (FGF) receptor complexes. It is essential for high-affinity binding of endocrine FGF19 and FGF21 to evoke the signaling cascade actively involved in homeostatic maintenance of glucose metabolism and energy expenditure. In this Review, we discuss the biological function of ß-Klotho in the regulation of glucose metabolism and offer mechanistic insights into its involvement in the pathophysiology of T2DM. We review our current understanding of the endocrine axis comprised of ß-Klotho and FGFs (FGF19 and FGF21) and its regulatory effects on glucose metabolism under physiological and T2DM conditions. We also highlight advances in the development and preclinical validation of pharmacological compounds that target ß-Klotho and/or the ß-Klotho-FGFRs complex for the treatment of T2DM. Given the remarkable advances in this field, we also discuss outstanding research questions and the many challenges in the clinical development of ß-Klotho-based therapies.

The HY5 and MYB15 transcription factors positively regulate cold tolerance in tomato via the CBF pathway.

The induction of C-repeat binding factors (CBFs) is crucial for plant survival at low temperatures. Therefore, understanding the mechanisms that regulate CBF transcription is vital for the future development of crops with increased cold tolerance. Here, we provide evidence for the existence of a LONG HYPOCOTYL 5 (HY5)-MYB15-CBFs transcriptional cascade that plays a crucial role in the cold response in tomato. The exposure of tomato plants to cold (4°C) increased the levels of HY5, MYB15 and CBFs transcripts. Moreover, mutations in HY5 or MYB15 decreased the levels of CBF transcripts. In contrast, overexpression of HY5 or MYB15 increased CBF transcript abundance. Crucially, the HY5 transcription factor activated the expression of MYB15 by directly binding to the promoter region, while both HY5 and MYB15 activated the expression of CBF1, CBF2 and CBF3. Taken together, these data show that HY5 can directly regulate CBF transcript levels, and also influence CBF expression indirectly via MYB15. The coordinated action of HY5 and MYB15 allows precise regulation of CBF expression and subsequent cold tolerance. These findings provide an improved understanding of the molecular mechanisms affording transcriptional regulation of CBFs, which can be exploited in the future to enhance cold tolerance in crops.

A meta-analysis approach with filtering for identifying gene-level gene-environment interactions.

There is a growing recognition that gene-environment interaction (G × E) plays a pivotal role in the development and progression of complex diseases. Despite a wealth of genetic data on various complex diseases/traits generated from association and sequencing studies, detecting G × E via genome-wide analysis remains challenging due to power issues. In genome-wide G × E studies, a common strategy to improve power is to first conduct a filtering test and retain only the genetic variants that pass the filtering step for subsequent G × E analyses. Two-stage, multistage, and unified tests have been proposed to jointly consider the filtering statistics in G × E tests. However, such G × E tests based on data from a single study may still be underpowered. Meanwhile, large-scale consortia have been formed to borrow strength across studies and populations. In this work, motivated by existing single-study G × E tests with filtering and the needs for meta-analysis G × E approaches based on consortia data, we propose a meta-analysis framework for detecting gene-based G × E effects, and introduce meta-analysis-based filtering statistics in the gene-level G × E tests. Simulations demonstrate the advantages of the proposed method-the ofGEM test. We apply the proposed tests to existing data from two breast cancer consortia to identify the genes harboring genetic variants with age-dependent penetrance (i.e., gene-age interaction effects). We develop an R software package ofGEM for the proposed meta-analysis tests.

Cyadox regulates the transcription of different genes by activation of the PI3K signaling pathway in porcine primary hepatocytes.

Cyadox, a new derivative of quinoxalines, has been ascertained as an antibiotic with significant growth promoting, low poison, quick absorption, swift elimination, brief residual period, and noncumulative effect. Seven differential expressed genes, including Insulin-like Growth Factor-1 ( IGF-1), Epidermal Growth Factor ( EGF), Poly ADP-ribose polymerase ( PARP), the Defender Against Apoptotic Death 1 ( DAD1), Complement Component 3 ( C3), Transketolase ( TK) and a New gene, were induced by cyadox in swine liver tissues by messenger RNA differential display reverse transcription polymerase chain reaction (DDRT-PCR) in our laboratory. However, the signal mechanism that cyadox altered these genes expression is not completely elucidated. The signaling pathways involved in the expressions of seven genes induced by cyadox were determined in porcine primary hepatocytes by RT-qPCR and the application of various signal pathway inhibitors. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that cyadox could stimulate proliferation of porcine primary hepatocytes in a time-dependent manner. In porcine primary cultured hepatocytes, phosphoinositide 3-kinase (PI3K) and transforming growth factor-ß (TGF-ß) signal pathways were the main signal pathways involved in the expressions of seven genes induced by cyadox. Taken together, these results demonstrate for the first time that seven cyadox-related genes expressions in porcine primary hepatocytes treated with cyadox are mediated mainly through the PI3K signaling pathway, potentially leading to enhanced cell growth and cell immunity. EGF might be the early response gene of cyadox, and a primary regulator of the other gene expressions such as IGF-1 and DAD1, playing an important role in cell proliferation promoted by cyadox.

Astrocyte activation in the periaqueductal gray promotes descending facilitation to cancer-induced bone pain through the JNK MAPK signaling pathway.

Descending nociceptive modulation from the supraspinal structures has an important role in cancer-induced bone pain (CIBP). Midbrain ventrolateral periaqueductal gray (vlPAG) is a critical component of descending nociceptive circuits; nevertheless, its precise cellular and molecular mechanisms involved in descending facilitation remain elusive. Our previous study has shown that the activation of p38 MAPK in vlPAG microglia is essential for the neuropathic pain sensitization. However, the existence of potential connection between astrocytes and c-Jun N-terminal kinase (JNK) pathway in CIBP has not yet been elucidated. The following study examines the involvement of astrocyte activation and upregulation of p-JNK in vlPAG, using a CIBP rat model. Briefly, CIBP was mimicked by an intramedullary injection of Walker 256 mammary gland carcinoma cells into the animal tibia. A significant increase in expression levels of astrocytes in the vlPAG of CIBP rats was observed. Furthermore, stereotaxic microinjection of the astrocytic cytotoxin L-α-aminoadipic acid decreased the mechanical allodynia as well as established and reversed the astrocyte activation in CIBP rats. A significant increase in expression levels of p-JNK in astrocytes in vlPAG of CIBP rats was also observed. Moreover, the intrathecal administration of JNK inhibitors SP600125 reduced the expression of glial fibrillary acidic protein, while microinjection of the SP600125 decreased the mechanical allodynia of CIBP rats. These results suggested that CIBP is associated with astrocyte activation in the vlPAG that probably participates in driving descending pain facilitation through the JNK MAPK signaling pathway. To sum up, these findings reveal a novel site of astrocytes modulation of CIBP.

A Pilot, Exploratory, Randomized, Phase II Safety Study Evaluating Tumor Cell Mobilization and Apheresis Product Contamination in Patients Treated with Granulocyte Colony-Stimulating Factor Alone or Plus Plerixafor.

Because of the potential risk of tumor cell mobilization with granulocyte colony-stimulating factor (G-CSF), it is crucial to evaluate any potential effect of plerixafor treatment in the presence of G-CSF on multiple myeloma (MM) cell mobilization. This was an open-label, multicenter, randomized, exploratory, safety study (NCT01753453) that investigated the extent of MM cell mobilization after treatment with G-CSF + plerixafor in patients who were deemed poor mobilizers of hematopoietic stem cells. The primary efficacy outcome was the number of MM cells in peripheral blood and apheresis product after G-CSF + plerixafor treatment versus G-CSF alone. Key secondary efficacy outcomes included overall survival and disease status up to 2 years after the first G-CSF dose. Twenty patients were randomized and received at least 1 dose of study treatment. There were no patients with MM cells in peripheral blood up to day 8 G-CSF administration in either treatment group. Up to day 8 no patient in the G-CSF + plerixafor arm and only 1 patient in the G-CSF arm mobilized at least 4.5 × 105 MM cells in the apheresis product. Nine of 10 patients from each treatment arm proceeded to transplantation. MM cells were detected in 5 patients from each treatment arm before and after transplantation. Adverse events observed in the G-CSF + plerixafor arm were consistent with the known safety profile of plerixafor. No MM cells were detected in peripheral blood of either treatment group up to day 8 of mobilization. Only 1 patient in the G-CSF alone group mobilized at least 4.5 × 105 MM tumor cells in apheresis product up to day 8. However, 50% of patients in both treatment arms had detectable amounts of MM cells in their peripheral blood pre- and post-transplantation. There were no new safety concerns with plerixafor.

Crosstalk between NFκB-dependent astrocytic CXCL1 and neuron CXCR2 plays a role in descending pain facilitation.

BACKGROUND: Despite accumulating evidence on the role of glial cells and their associated chemicals in mechanisms of pain, few studies have addressed the potential role of chemokines in the descending facilitation of chronic pain. We aimed to study the hypothesis that CXCL1/CXCR2 axis in the periaqueductal gray (PAG), a co-restructure of the descending nociceptive system, is involved in descending pain facilitation. METHODS: Intramedullary injection of Walker 256 mammary gland carcinoma cells of adult female Sprague Dawley rats was used to establish a bone cancer pain (BCP) model. RT-PCR, Western blot, and immunohistochemistry were performed to detect pNfkb, Cxcl1, and Cxcr2 and their protein expression in the ventrolateral PAG (vlPAG). Immunohistochemical co-staining with NeuN, GFAP, and CD11 were used to examine the cellular location of pNFκB, CXCL1, and CXCR2. The effects of NFκB and CXCR2 antagonists and CXCL1 neutralizing antibody on pain hypersensitivity were evaluated by behavioral testing. RESULTS: BCP induced cortical bone damage and persistent mechanical allodynia and increased the expression of pNFκB, CXCL1, and CXCR2 in vlPAG. The induced phosphorylation of NFκB was co-localized with GFAP and NeuN, but not with CD11. Micro-injection of BAY11-7082 attenuated BCP and reduced CXCL1 increase in the spinal cord. The expression level of CXCL1 in vlPAG showed co-localization with GFAP, but not with CD11 and NeuN. Micro-administration of CXCL1 neutralizing antibody from 6 to 9 days after inoculation attenuated mechanical allodynia. Furthermore, vlPAG application of CXCL1 elicited pain hypersensitivity in normal rats. Interestingly, CXCR2 was upregulated in vlPAG neurons (not with CD11 and GFAP) after BCP. CXCR2 antagonist SB225002 completely blocked the CXCL1-induced mechanical allodynia and attenuated BCP-induced pain hypersensitivity. CONCLUSION: The NFκB-dependent CXCL1-CXCR2 signaling cascade played a role in glial-neuron interactions and in descending facilitation of BCP.

Resistant cutoff values and optimal scheme establishments for florfenicol against Escherichia coli with PK-PD modeling analysis in pigs.

Florfenicol, a structural analog of thiamphenicol, has broad-spectrum antibacterial activity against gram-negative and gram-positive bacteria. This study was conducted to investigate the epidemiological, pharmacokinetic-pharmacodynamic cutoff, and the optimal scheme of florfenicol against Escherichia coli (E. coli) with PK-PD integrated model in the target infectious tissue. 220 E. coli strains were selected to detect the susceptibility to florfenicol, and a virulent strain P190, whose minimum inhibitory concentration (MIC) was similar to the MIC50 (8 µg/ml), was analyzed for PD study in LB and ileum fluid. The MIC of P190 in the ileum fluid was 0.25 times lower than LB. The ratios of MBC/MIC were four both in the ileum and LB. The characteristics of time-killing curves also coincided with the MBC determination. The recommended dosages (30 mg/kg·body weight) were orally administrated in healthy pigs, and both plasma and ileum fluid were collected for PK study. The main pharmacokinetics (PK) parameters including AUC24 hr , AUC0-∞ , Tmax , T1/2 , Cmax , CLb, and Ke were 49.83, 52.33 µg*h/ml, 1.32, 10.58 hr, 9.12 µg/ml, 0.50 L/hr*kg, 0.24 hr-1 and 134.45, 138.71 µg*hr/ml, 2.05, 13.01 hr, 16.57 µg/ml, 0.18 L/hr*kg, 0.14 hr-1 in the serum and ileum fluid, respectively. The optimum doses for bacteriostatic, bactericidal, and elimination activities were 29.81, 34.88, and 36.52 mg/kg for 50% target and 33.95, 39.79, and 42.55 mg/kg for 90% target, respectively. The final sensitive breakpoint was defined as 16 µg/ml. The current data presented provide the optimal regimens (39.79 mg/kg) and susceptible breakpoint (16 µg/ml) for clinical use, but these predicted data should be validated in the clinical practice.

N-O Reduction and ROS-Mediated AKT/FOXO1 and AKT/P53 Pathways Are Involved in Growth Promotion and Cytotoxicity of Cyadox.

Cyadox is a novel derivative of quinoxaline-1,4-dioxides (QdNOs) with the potential to be developed as a feed additive. However, the pharmacological and toxicological bioactive molecules of cyadox and the molecular mechanism of its pharmacological and toxic actions remain unclear. In the present study, cyadox and its main metabolites of cy1, cy4, cy6, and cy12 were selected; the growth promotion characteristic was indicated by the mRNA level of EGF; and the cytotoxicity of cyadox was determined by methylthiazol tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) release, and Annexin V-FITC/PI apoptosis detection kit with flow cytometry. The intracellular ROS, cyclin D1, and Akt/P53/FOXO1 signaling pathway were also investigated. Our data suggested that cyadox showed relatively higher activity than its metabolites, and the ROS was generated from N-O reduction of cyadox. Moreover, cyadox (2 µM) activated the Akt and increased the EGF, cyclin D1, and FOXO1 expression levels. Cyadox (100 µM) induced cytotoxicity in L02 cells in a concentration- and time-dependent manner. Additionally, the activated P53 pathway, hyperactivated Akt, and apoptosis were found in L02 cells after incubation with 100 µM cyadox. Our data demonstrated that Akt promoted cell survival when it was mildly activated by cyadox at 2 µM, and Akt leads to apoptosis when it was severely activated by cyadox at 100 µM. Thus, the present study revealed that N-O reduction of cyadox and ROS-mediated AKT/FOXO1 and AKT/P53 pathways were involved in growth promotion and cytotoxicity of cyadox.

Trichothecenes: immunomodulatory effects, mechanisms, and anti-cancer potential.

Paradoxically, trichothecenes have both immunosuppressive and immunostimulatory effects. The underlying mechanisms have not been fully explored. Early studies show that dose, exposure timing, and the time at which immune function is assessed influence whether trichothecenes act in an immunosuppressive or immunostimulatory fashion. Recent studies suggest that the immunomodulatory function of trichothecenes is also actively shaped by competing cell-survival and death-signaling pathways. Autophagy may also promote trichothecene immunosuppression, although the mechanism may be complicated. Moreover, trichothecenes may generate an "immune evasion" milieu that allows pathogens to escape host and vaccine immune defenses. Some trichothecenes, especially macrocyclic trichothecenes, also potently kill cancer cells. T-2 toxin conjugated with anti-cancer monoclonal antibodies significantly suppresses the growth of thymoma EL-4 cells and colon cancer cells. The type B trichothecene diacetoxyscirpenol specifically inhibits the tumor-promoting factor HIF-1 in cancer cells under hypoxic conditions. Trichothecin markedly inhibits the growth of multiple cancer cells with constitutively activated NF-κB. The type D macrocyclic toxin Verrucarin A is also a promising therapeutic candidate for leukemia, breast cancer, prostate cancer, and pancreatic cancer. The anti-cancer activities of trichothecenes have not been comprehensively summarized. Here, we first summarize the data on the immunomodulatory effects of trichothecenes and discuss recent studies that shed light on the underlying cellular and molecular mechanisms. These mechanisms include autophagy and major signaling pathways and their crosstalk. Second, the anti-cancer potential of trichothecenes and the underlying mechanisms will be discussed. We hope that this review will show how trichothecene bioactivities can be exploited to generate therapies against pathogens and cancer.

A two-year dietary carcinogenicity study of cyadox in Sprague-Dawley rats.

To investigate the potential carcinogenicity of cyadox, an antimicrobial agent, four groups of Sprague-Dawley rats (50 rats/sex/group) were fed diets containing cyadox (0, 200, 600 or 2000 mg/kg) for up to two years. There were significant decreases in body weight, feed intake and feed efficiency in both genders during most of the period in the 2000 mg/kg group. Significant decreases in serum ALT were observed in the 2000 mg/kg group at weeks 52, 78 and 104. For the control, 200, 600, and 2000 mg/kg groups, the tumor incidence in females was 33.3%, 37.2%, 40.0% and 19.0%, while it in males it was 18.9%, 2.6%, 17.1% and 13.6%, respectively. At histopathology, no increases in tumor incidence were attributed to treatment with cyadox. The mild swelling and fatty degeneration in hepatocytes, and mild swelling and tubular necrosis in the kidney were observed in 2000 mg/kg group. The no-observed-effect-level (NOEL) for carcinogenicity of cyadox fed to rats was 2000 mg/kg diet (132.18-156.28 mg/kg b.w./day). In conclusion, cyadox was not carcinogenic to rats with the liver and kidney as the target organs, and the side chain may be involved in toxicity and carcinogenicity mediated by QdNOs.

A unified set-based test with adaptive filtering for gene-environment interaction analyses.

In genome-wide gene-environment interaction (GxE) studies, a common strategy to improve power is to first conduct a filtering test and retain only the SNPs that pass the filtering in the subsequent GxE analyses. Inspired by two-stage tests and gene-based tests in GxE analysis, we consider the general problem of jointly testing a set of parameters when only a few are truly from the alternative hypothesis and when filtering information is available. We propose a unified set-based test that simultaneously considers filtering on individual parameters and testing on the set. We derive the exact distribution and approximate the power function of the proposed unified statistic in simplified settings, and use them to adaptively calculate the optimal filtering threshold for each set. In the context of gene-based GxE analysis, we show that although the empirical power function may be affected by many factors, the optimal filtering threshold corresponding to the peak of the power curve primarily depends on the size of the gene. We further propose a resampling algorithm to calculate P-values for each gene given the estimated optimal filtering threshold. The performance of the method is evaluated in simulation studies and illustrated via a genome-wide gene-gender interaction analysis using pancreatic cancer genome-wide association data.

Fumonisins: oxidative stress-mediated toxicity and metabolism in vivo and in vitro.

Fumonisins (FBs) are widespread Fusarium toxins commonly found as corn contaminants. FBs could cause a variety of diseases in animals and humans, such as hepatotoxic, nephrotoxic, hepatocarcinogenic and cytotoxic effects in mammals. To date, almost no review has addressed the toxicity of FBs in relation to oxidative stress and their metabolism. The focus of this article is primarily intended to summarize the progress in research associated with oxidative stress as a plausible mechanism for FB-induced toxicity as well as the metabolism. The present review showed that studies have been carried out over the last three decades to elucidate the production of reactive oxygen species (ROS) and oxidative stress as a result of FBs treatment and have correlated them with various types of FBs toxicity, indicating that oxidative stress plays critical roles in the toxicity of FBs. The major metabolic pathways of FBs are hydrolysis, acylation and transamination. Ceramide synthase, carboxylesterase FumD and aminotransferase FumI could degrade FB1 and FB2. The cecal microbiota of pigs and alkaline processing such as nixtamalization can also transform FB1 into metabolites. Most of the metabolites of FB1 were less toxic than FB1, except its partial (pHFB1) metabolites. Further understanding of the role of oxidative stress in FB-induced toxicity will throw new light on the use of antioxidants, scavengers of ROS, as well as on the blind spots of metabolism and the metabolizing enzymes of FBs. The present review might contribute to reveal the toxicity of FBs and help to protect against their oxidative damage.

Safety assessment of aditoprim acute, subchronic toxicity and mutagenicity studies.

Aditoprim (ADP), a new developed dihydrofolate reductase (DHFR) inhibitor, has great potential in clinical veterinary medicine because of its greater pharmacokinetic properties than structural analogs. Preclinical toxicology studies were performed to assess the safety of ADP including an acute oral toxicity test, a subchronic toxicity test and five mutagenicity tests. In the acute oral toxicity test, ADP was administered singly by oral gavage to Wistar rats and Kunming mice. The LD50 calculated was 1400 mg kg(-1) body weight (BW) day(-1) in rats and 1130 mg kg(-1) BW day(-1) in mice. In a subchronic study, Wistar rats were administered ADP at dose levels of 0, 20, 100 and 1000 mg kg(-1) diet for 90 days. Significant decreases were observed on body weight and food efficiency in the high-dose group. Treatment-related changes in clinical serum biochemistry were found in the medium- and high-dose groups. Significant increases in the relative weights of livers and kidneys in females and testis in males in the 1000 mg kg(-1) diet, and significant decrease in relative weights of livers in males in the 100 mg kg(-1) diet were noted. Histopathological observations revealed that the 1000 mg kg(-1) ADP diet could induce lymphocytic infiltration and hepatocytic necrosis near the hepatic portal area. The genotoxicity of ADP was negative in tests, such as the bacterial reverse mutation assay, mice bone marrow erythrocyte micronucleus assay, in vitro chromosomal aberration test, in vitro cho/hgprt mammalian cell mutagenesis assay and mice testicle cells chromosome aberration. Based on the subchronic study, the no-observed-adverse-effect level for ADP was a 20 mg kg(-1) diet, which is about 1.44-1.53 mg kg(-1) BW day(-1) in rats.

Marbled inflation from population structure in gene-based association studies with rare variants.

Accurate genetic association studies are crucial for the detection and the validation of disease determinants. One of the main confounding factors that affect accuracy is population stratification, and great efforts have been extended for the past decade to detect and to adjust for it. We have now efficient solutions for population stratification adjustment for single-SNP (where SNP is single-nucleotide polymorphisms) inference in genome-wide association studies, but it is unclear whether these solutions can be effectively applied to rare variation studies and in particular gene-based (or set-based) association methods that jointly analyze multiple rare and common variants. We examine here, both theoretically and empirically, the performance of two commonly used approaches for population stratification adjustment-genomic control and principal component analysis-when used on gene-based association tests. We show that, different from single-SNP inference, genes with diverse composition of rare and common variants may suffer from population stratification to various extent. The inflation in gene-level statistics could be impacted by the number and the allele frequency spectrum of SNPs in the gene, and by the gene-based testing method used in the analysis. As a consequence, using a universal inflation factor as a genomic control should be avoided in gene-based inference with sequencing data. We also demonstrate that caution needs to be exercised when using principal component adjustment because the accuracy of the adjusted analyses depends on the underlying population substructure, on the way the principal components are constructed, and on the number of principal components used to recover the substructure.