The Global Epidemic of Metabolic Fatty Liver Disease.

PURPOSE OF REVIEW: The objective of this manuscript is to examine the current literature on the epidemiology of metabolic dysfunction-associated steatotic liver disease (MASLD), its correlation with cardiovascular disease (CVD) outcomes, as well as to evaluate the update in nomenclature from non-alcoholic liver disease (NAFLD). RECENT FINDINGS: The update of diagnostic criteria from NAFLD to MASLD reduces the stigma associated with alcohol consumption and poor health choices. It also shines a light on the crucial role of cardiometabolic risk factors in disease pathophysiology. The incidence and prevalence of MASLD are projected to increase significantly in the future as the population burden of cardiometabolic risk factors rises. MASLD is also a potent risk factor for developing CVD that should be tackled by using a multi-disciplinary team with a holistic approach. As the new nomenclature for metabolic liver disease is adopted on a global scale, more research is needed to investigate the applicability of findings from previous trials focusing on NAFLD. It is anticipated that the epidemic of MASLD will continue to increase globally, hence the urgent need for therapeutic approaches to reverse this trend.

Case Report of a Child with Colocolic Intussusception with a Primary Lead Point.

Intussusception is the telescoping of bowel into an adjacent segment of bowel and has an associated risk for bowel ischemia and perforation. The classic triad of abdominal pain, blood in stool, and an abdominal mass is present in less than 40% of pediatric cases and is less common in older children.1 Ultrasound has a high sensitivity and specificity for the diagnosis of intussusception, and once diagnosed, treatment modalities include reduction by either ultrasound or fluoroscopic guided air or hydrostatic enema. The risk of recurrence after successful reduction occurs in up to 12% of pediatric patients and occurs more frequently in older children and children with a pathologic lead point.2 We present a case of a 6-year-old child with colocolic intussusception that was successfully reduced and recurred within five days due to a large colonic polyp. Topics: Intussusception, lead point, pediatrics.

SELENOP modifies sporadic colorectal carcinogenesis and WNT signaling activity through LRP5/6 interactions.

Although selenium deficiency correlates with colorectal cancer (CRC) risk, the roles of the selenium-rich antioxidant selenoprotein P (SELENOP) in CRC remain unclear. In this study, we defined SELENOP's contributions to sporadic CRC. In human single-cell cRNA-Seq (scRNA-Seq) data sets, we discovered that SELENOP expression rose as normal colon stem cells transformed into adenomas that progressed into carcinomas. We next examined the effects of Selenop KO in a mouse adenoma model that involved conditional, intestinal epithelium-specific deletion of the tumor suppressor adenomatous polyposis coli (Apc) and found that Selenop KO decreased colon tumor incidence and size. We mechanistically interrogated SELENOP-driven phenotypes in tumor organoids as well as in CRC and noncancer cell lines. Selenop-KO tumor organoids demonstrated defects in organoid formation and decreases in WNT target gene expression, which could be reversed by SELENOP restoration. Moreover, SELENOP increased canonical WNT signaling activity in noncancer and CRC cell lines. In defining the mechanism of action of SELENOP, we mapped protein-protein interactions between SELENOP and the WNT coreceptors low-density lipoprotein receptor-related proteins 5 and 6 (LRP5/6). Last, we confirmed that SELENOP-LRP5/6 interactions contributed to the effects of SELENOP on WNT activity. Overall, our results position SELENOP as a modulator of the WNT signaling pathway in sporadic CRC.

High-throughput drug screening of fine-needle aspiration-derived cancer organoids.

Generation of fine-needle aspiration (FNA)-derived cancer organoids has allowed us to develop a number of downstream applications. In this protocol, we start with organoids cultured in a semi-solid format. We dissociate organoids into single cells and then plate in a 384-well format for high-throughput drug screening. While this method must be fine-tuned for each individual organoid culture, it offers a format well suited for rapidly screening medium-sized drug/compound libraries (500-5,000 molecules) and generating dose-response curves to measure relative efficacy. For complete details on the use and execution of this protocol, please refer to Lee et al. (2020) and Vilgelm et al. (2020).

Bacteria Boost Mammalian Host NAD Metabolism by Engaging the Deamidated Biosynthesis Pathway.

Nicotinamide adenine dinucleotide (NAD), a cofactor for hundreds of metabolic reactions in all cell types, plays an essential role in metabolism, DNA repair, and aging. However, how NAD metabolism is impacted by the environment remains unclear. Here, we report an unexpected trans-kingdom cooperation between bacteria and mammalian cells wherein bacteria contribute to host NAD biosynthesis. Bacteria confer resistance to inhibitors of NAMPT, the rate-limiting enzyme in the amidated NAD salvage pathway, in cancer cells and xenograft tumors. Mechanistically, a microbial nicotinamidase (PncA) that converts nicotinamide to nicotinic acid, a precursor in the alternative deamidated NAD salvage pathway, is necessary and sufficient for this protective effect. Using stable isotope tracing and microbiota-depleted mice, we demonstrate that this bacteria-mediated deamidation contributes substantially to the NAD-boosting effect of oral nicotinamide and nicotinamide riboside supplementation in several tissues. Collectively, our findings reveal an important role of bacteria-enabled deamidated pathway in host NAD metabolism.

Chemical Screening Using Cell-Free Xenopus Egg Extract.

Most drug screening methods use purified proteins, cultured cells, and/or small model organisms such as Xenopus, zebrafish, flies, or nematodes. These systems have proven successes in drug discovery, but they also have weaknesses. Although purified cellular components allow for identification of compounds with activity against specific targets, such systems lack the complex biological interactions present in cellular and organismal screens. In vivo systems overcome these weaknesses, but the lack of cellular permeability, efflux by cellular pumps, and/or toxicity can be major limitations. Xenopus laevis egg extract, a concentrated and biologically active cytosol, can potentially overcome these weaknesses. Drug interactions occur in a near-physiological milieu, thereby functioning in a "truer" endogenous manner than purified components. Also, Xenopus egg extract is a cell-free system that lacks intact plasma membranes that could restrict drug access to potential targets. Finally, Xenopus egg extract is readily manipulated at the protein level: Proteins are easily depleted or added to the system, an important feature for analyzing drug effects in disease states. Thus, Xenopus egg extract offers an attractive media for screening drugs that merges strengths of both in vitro and in vivo systems.

Small-molecule high-throughput screening utilizing Xenopus egg extract.

Screens for small-molecule modulators of biological pathways typically utilize cultured cell lines, purified proteins, or, recently, model organisms (e.g., zebrafish, Drosophila, C. elegans). Herein, we describe a method for using Xenopus laevis egg extract, a biologically active and highly tractable cell-free system that recapitulates a legion of complex chemical reactions found in intact cells. Specifically, we focus on the use of a luciferase-based fusion system to identify small-molecule modulators that affect protein turnover.

Screening for small molecule inhibitors of embryonic pathways: sometimes you gotta crack a few eggs.

Extract prepared from Xenopus eggs represents a cell-free system that has been shown to recapitulate a multitude of cellular processes, including cell cycle regulation, DNA replication/repair, and cytoskeletal dynamics. In addition, this system has been used to successfully reconstitute the Wnt pathway. Xenopus egg extract, which can be biochemically manipulated, offers an ideal medium in which small molecule screening can be performed in near native milieu. Thus, the use of Xenopus egg extract for small molecule screening represents an ideal bridge between targeted and phenotypic screening approaches. This review focuses on the use of this system for small molecules modulators of major signal transduction pathways (Notch, Hedgehog, and Wnt) that are critical for the development of the early Xenopus embryo. We describe the properties of Xenopus egg extract and our own high throughput screen for small molecules that modulate the Wnt pathway using this cell-free system. We propose that Xenopus egg extract could similarly be adapted for screening for modulators of the Notch and Hedgehog pathways.