Reaction of acylated homoserine lactone bacterial signaling molecules with oxidized halogen antimicrobials.

Oxidized halogen antimicrobials, such as hypochlorous and hypobromous acids, have been used extensively for microbial control in industrial systems. Recent discoveries have shown that acylated homoserine lactone cell-to-cell signaling molecules are important for biofilm formation in Pseudomonas aeruginosa, suggesting that biofouling can be controlled by interfering with bacterial cell-to-cell communication. This study was conducted to investigate the potential for oxidized halogens to react with acylated homoserine lactone-based signaling molecules. Acylated homoserine lactones containing a 3-oxo group were found to rapidly react with oxidized halogens, while acylated homoserine lactones lacking the 3-oxo functionality did not react. The Chromobacterium violaceum CV026 bioassay was used to determine the effects of such reactions on acylated homoserine lactone activity. The results demonstrated that 3-oxo acyl homoserine lactone activity was rapidly lost upon exposure to oxidized halogens; however, acylated homoserine lactones lacking the 3-oxo group retained activity. Experiments with the marine alga Laminaria digitata demonstrated that natural haloperoxidase systems are capable of mediating the deactivation of acylated homoserine lactones. This may illustrate a natural defense mechanism to prevent biofouling on the surface of this marine alga. The Chromobacterium violaceum activity assay illustrates that reactions between 3-oxo acylated homoserine lactone molecules and oxidized halogens do occur despite the presence of biofilm components at much greater concentrations. This work suggests that oxidized halogens may control biofilm not only via a cidal mechanism, but also by possibly interfering with 3-oxo acylated homoserine lactone-based cell signaling.     

Metabolic vulnerability of cisplatin‐resistant cancers

Cisplatin is the most widely used chemotherapeutic agent, and resistance of neoplastic cells against this cytoxicant poses a major problem in clinical oncology. Here, we explored potential metabolic vulnerabilities of cisplatin‐resistant non‐small human cell lung cancer and ovarian cancer cell lines. Cisplatin‐resistant clones were more sensitive to killing by nutrient deprivation in vitro and in vivo than their parental cisplatin‐sensitive controls. The susceptibility of cisplatin‐resistant cells to starvation could be explained by a particularly strong dependence on glutamine. Glutamine depletion was sufficient to restore cisplatin responses of initially cisplatin‐resistant clones, and glutamine supplementation rescued cisplatin‐resistant clones from starvation‐induced death. Mass spectrometric metabolomics and specific interventions on glutamine metabolism revealed that, in cisplatin‐resistant cells, glutamine is mostly required for nucleotide biosynthesis rather than for anaplerotic, bioenergetic or redox reactions. As a result, cisplatin‐resistant cancers became exquisitely sensitive to treatment with antimetabolites that target nucleoside metabolism.     

Pulsed field gradient electrophoresis of DNA digested in agarose allows the sizing of the large duplication unit of a surface antigen gene in trypanosomes

Intact chromosome-sized DNA molecules from eukaryotes may be prepared by performing lysis and enzymic deproteinization on cells embedded in agarose [Schwartz and Cantor, Cell 37 (1984), 67-75]. Here we show that DNA prepared by this method may be cut with restriction enzymes, or modified with site-specific methylases and cut by DpnI. As the DNA remains incorporated in the gel matrix, shear degradation of large fragments is avoided. The fragments can then be sized by conventional or pulsed field gradient gel electrophoresis. Phage lambda genomic oligomers are used as size markers, allowing the estimation of fragment sizes up to about 1200 kb. We apply these techniques to show that activation of the telomeric gene encoding variant surface antigen 1.3 in Trypanosoma brucei strain 427, involves the duplication of a DNA segment that starts between 29 and 42 kb upstream of the gene and to assign a chromosomal fragment into which the duplicated 1.3 gene may have transposed.     

Primidone blocks RIPK1-driven cell death and inflammation

The receptor-interacting serine/threonine protein kinase 1 (RIPK1) is a key mediator of regulated cell death and inflammation. Recent studies suggest that RIPK1 inhibition would fundamentally improve the therapy of RIPK1-dependent organ damage in stroke, myocardial infarction, kidney failure, and systemic inflammatory response syndrome. Additionally, it could ameliorate or prevent multi-organ failure induced by cytokine release in the context of hyperinflammation, as seen in COVID-19 patients. Therefore, we searched for a RIPK1 inhibitor and present the aromatic antiepileptic and FDA-approved drug primidone (Liskantin®) as a potent inhibitor of RIPK1 activation in vitro and in a murine model of TNFα-induced shock, which mimics the hyperinflammatory state of cytokine release syndrome. Furthermore, we detected for the first time RIPK1 activation in the respiratory tract epithelium of hospitalized patients who tested positive for SARS-CoV-2 infection. Our data provide a strong rationale for evaluating the drug primidone in conditions of hyperinflammation in humans.Subject terms: Cell death and immune response, Translational research     

Locked patellar dislocation: a case report

Fertility is markedly reduced in patients with chronic renal failure. For women with pre-existing renal disease, pregnancy is associated with an increased rate of fetal complications and a considerable risk of renal disease progression. Due to substantial improvements in antenatal and neonatal care, fetal outcome has improved considerably in the last two decade. A Saudi survey which examined the frequency of pregnancy among women in end stage renal disease (ESRD) and undergoing regular hemodialysis (HD), showed an incidence of 7% over a five year period (1.4 per year). This may reflect the cultural endorsement of having offspring. We hereby report 2 cases of successful pregnancy managed at the Prince Salman Center for Kidney Diseases (PSCKD).