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Kirby Klausen posted an update 3 weeks, 3 days ago
This study aims to compare the bacterial killing of once- versus twice-daily nebulized amikacin against Pseudomonas aeruginosa and to determine the optimal duration of therapy. Three clinical P. aeruginosa isolates (amikacin MICs 2, 8, and 64 mg/L) were exposed to simulated epithelial lining fluid exposures of nebulized amikacin with dosing regimens of 400 mg and 800 mg once- or twice-daily up to 7-days using the in vitro hollow-fiber infection model. Quantitative cultures were performed. Simulated amikacin dosing regimens of 400 mg twice-daily and 800 mg once-daily achieved ≥2-log reduction in the bacterial burden within the first 24-hours of therapy for all isolates tested. No dosing regimen suppressed the emergence of amikacin resistance. No difference in bacterial killing or regrowth was observed between 3- and 7-days of amikacin. Amikacin doses of 800 mg once-daily for up to 3-days may be considered for future clinical trials.Triclocarban (TCC), an antibacterial agent widely used in personal care products, can affect embryonic development. However, the specific molecular mechanism of TCC-induced embryonic developmental damage remains unclear. In this study, TCC exposure was found to increase the expression of tmbim4 gene in zebrafish embryos. The tmbim4 mutant embryos are more susceptible to TCC exposure than wild-type (WT) embryos, with tmbim4 overexpression reducing TCC-induced embryonic death in the former. Exposure of tmbim4 mutant larvae to 400 μg/L TCC substantially increased apoptosis in the hindbrain and eyes. RNA-sequencing of WT and tmbim4 mutant larvae indicated that knockout of the tmbim4 gene in zebrafish affects the autophagy pathway. Abnormalities in autophagy can increase apoptosis and TCC exposure caused abnormal accumulation of autophagosomes in the hindbrain of tmbim4 mutant zebrafish embryos. LY3295668 mouse Pretreatment of TCC-exposed tmbim4 mutant zebrafish embryos with autophagosome formation inhibitors, substantially reduced the mortality of embryos and apoptosis levels. These results indicate that defects in the tmbim4 gene can reduce zebrafish embryo resistance to TCC. Additionally, apoptosis induced by abnormal accumulation of autophagosomes is involved in this process.Sex determination is a complex process that can be influenced by environment in various taxa. Disturbed environments can affect population sex ratios and thus threaten their viability. Emerging evidences support a role of epigenetic mechanisms, notably DNA methylation, in environmental sex determination (ESD). In this work, using zebrafish as model and a transgenerational experiment comprising 4 successive generations, we report a strength link between the promotor methylation level of three genes in female gonads and population sex ratio. One generation of zebrafish was exposed throughout its lifetime to cadmium (Cd), a non-essential metal, at an environmentally relevant concentration. The subsequent generations were not exposed. At the first and the third generation a subset of individuals was exposed to an elevated temperature, a well-known masculinizing factor in zebrafish. While heat was associated to an increase in the methylation level of cyp19a1a gene and population masculinization, foxl2a/dmrt1 methylation levels appeared to be influenced by Cd and fish density leading to offspring feminization. Ancestral Cd exposure indeed led to a progressive feminization of the population over generations and affected the sex plastic response of zebrafish in response to heat. The effect of Cd on the methylation level of foxl2a was observed until the third generation, supporting potential transgenerational inheritance. Our results support (i) a key role of cyp19a1a methylation in SD in zebrafish in response to environmental cues and (ii) the fact that the environment experienced by parents, namely mothers in the present case, can affect their offspring sex ratio via environment-induced DNA methylation changes in gonads.In this work, the ammonium-tolerant duckweed Landoltia punctata 0202 was used to study the effect of ammonium stress on carbon and nitrogen metabolism and elucidate the detoxification mechanism. The growth status, protein and starch content, and activity of nitrogen assimilation enzymes were determined, and the transcriptional levels of genes involved in ion transport and carbon and nitrogen metabolism were investigated. Under high ammonium stress, the duckweed growth was inhibited, especially when ammonium was the sole nitrogen source. Ammonium might mainly enter cells via low-affinity transporters. The stimulation of potassium transport genes suggested sufficient potassium acquisition, precluding cation deficiency. In addition, the up-regulation of ammonium assimilation and transamination indicated that excess ammonium could be incorporated into organic nitrogen. Furthermore, the starch content increased from 3.97% to 16.43% and 26.02% in the mixed-nitrogen and ammonium-nitrogen groups, respectively. And the up-regulated starch synthesis, degradation, and glycolysis processes indicated that the accumulated starch could provide sufficient carbon skeletons for excess ammonium assimilation. The findings of this study illustrated that the coordination of carbon and nitrogen metabolism played a vital role in the ammonium detoxification mechanism of duckweeds.Breast cancer is the most commonly diagnosed female cancer and the second leading cause of death in women in the US, including Hawaii. Accumulating evidence suggests that aminomethylphosphonic acid (AMPA), the primary metabolite of the herbicide glyphosate-a probable human carcinogen, may itself be carcinogenic. However, the relationship between urinary AMPA excretion and breast cancer risk in women is unknown. In this pilot study, we investigated the association between pre-diagnostic urinary AMPA excretion and breast cancer risk in a case-control study of 250 predominantly postmenopausal women 124 cases and 126 healthy controls (individually matched on age, race/ethnicity, urine type, date of urine collection, and fasting status) nested within the Hawaii biospecimen subcohort of the Multiethnic Cohort. AMPA was detected in 90% of cases and 84% of controls. The geometric mean of urinary AMPA excretion was nearly 38% higher among cases vs. controls (0.087 vs 0.063 ng AMPA/mg creatinine) after adjusting for race/ethnicity, age and BMI.