Optimization and Application of Metabolomic Assays for Analyzing Diet-induced and Gut Microbiota-derived Short-chain Fatty Acids in Mice and Humans

Introduction: In recent decades, the obesity epidemic worldwide has prompted the need for research targeting disease prevention, treatment, and maintenance. Dietary interventions are one of the primary methods to instill positive nutrition habits into one’s lifestyle. Thus, resistant starch type 4 (RS4), a prebiotic dietary fiber, has been proposed to induce beneficial immunometabolic health outcomes. Currently there is a lack of knowledge on the health outcomes of RS4 in adults with metabolic syndrome (MetS). Goal: The goal of this research was to optimize a metabolomic assay to quantify fecal short chain fatty acids (SCFAs), a byproduct of microbial fermentation in the gut, and to apply this assay to health outcomes of RS4 intervention in an adult population with MetS as well as genetically induced obese mice. Methods: An assay was optimized to extract and derivatize fecal SCFA from human stool samples followed by quantification using gas chromatography – mass spectrometry (GC-MS). Retrospective analysis of fecal samples from adults including both men (n=4) and women (n=12) with signs of MetS, collected at four time points throughout an ad libitum dietary intervention of RS42, were processed and quantified. This method was also retrospectively applied to cecum samples of KK.Cg-Ay/a, genetically induced obese mouse model, to quantify the effects of RS4 on cecum SCFA concentrations. 16S rRNA sequencing was performed to study the effect of RS4 on gut microbial composition. Blood biomarkers, glycemic, and lipid viariables, anthropometric measurements, and diet nutrient composition were also studied. Results: GC-MS analysis revealed significantly increased SCFAs following RS4 consumption including butyrate, propionate, valerate, isovallerate, and hexanoate. 16S-rRNA gene sequencing revealed a differential abundance of 71 bacterial operational taxonomic units, including the enrichment of three Bacteroides species and one each of Parabacteroides, Oscillospira, Blautia, Ruminococcus, Eubacterium, and Christensenella species in the RS4 group. RS4-specific associations were found between gut microbial composition and SCFA concentrations. Cholesterols, fasting glucose, glycosylated haemoglobin, and proinflammatory markers in the blood as well as waist circumference and % body fat were lower post intervention in the RS4 group compared with the control group. In KK.Cg-Ay/a mice, butyrate was significantly enriched in RS4 fed mice intestinal tissue. Discussion: An optimized method to quantify intestinal and fecal SCFA was created. The biological function of RS4 on gut microbiota in inidividuals with MetS was also identified. Larger studies are needed to fully understand the mechanistic action of RS4 in individuals with metabolic dysfunction for future implications on dietary guidelines

Strongly correlated one-dimensional Bose-Fermi quantum mixtures: symmetry and correlations

We consider multi-component quantum mixtures (bosonic, fermionic, or mixed) with strongly repulsive contact interactions in a one-dimensional harmonic trap. In the limit of infinitely strong repulsion and zero temperature, using the class-sum method, we study the symmetries of the spatial wave function of the mixture. We find that the ground state of the system has the most symmetric spatial wave function allowed by the type of mixture. This provides an example of the generalized Lieb-Mattis theorem. Furthermore, we show that the symmetry properties of the mixture are embedded in the large-momentum tails of the momentum distribution, which we evaluate both at infinite repulsion by an exact solution and at finite interactions using a numerical DMRG approach. This implies that an experimental measurement of the Tan's contact would allow to unambiguously determine the symmetry of any kind of multi-component mixture.Comment: 19 pages, 6 figure

Alternative Macroautophagic Pathways

Macroautophagy is a bulk degradation process that mediates the clearance of long-lived proteins, aggregates, or even whole organelles. This process includes the formation of autophagosomes, double-membrane structures responsible for delivering cargo to lysosomes for degradation. Currently, other alternative autophagy pathways have been described, which are independent of macroautophagic key players like Atg5 and Beclin 1 or the lipidation of LC3. In this review, we highlight recent insights in indentifying and understanding the molecular mechanism responsible for alternative autophagic pathways

Quantitative and Qualitative Analysis of Dynamic Cavernosographies in Erectile Dysfunction due to Venous Leakage

Of 521 patients with erectile dysfunction in whom a multidisciplinary approach was used, 145 (27.8%) showed venous leakage as (concomitant) etiology of the impotence in dynamic cavernosography. The rate of the maintenance flow corresponded well with the response to a standardized intracavernosal injection of vasoactive drugs (p < 0.05) in patients with venous leakage. The maintenance flow increased with the age in secondary impotent men. It was not statistically different in patients with or without concomitant arterial insufficiency (p = 0.19). Fifty-one of 145 patients (32.2%) presented a pathologic cavernosal drainage via a single venous system; 94/145 (64.8%) showed a combined venous leakage. The type of leakage corresponded neither to the maintenance flow nor to the response to intracavernosal injections. Our findings show that standardized intracavernosal testing and Doppler have a high predictive value for the status of the venous occlusive system. Exact evaluation of the type of leakage can be made by bidimensional cavernosography only

Erectile dysfunction due to ectopic penile vein

A total of 86/260 patients with erectile dysfunction had venous leakage as (joint) etiology. In 5 of 86 patients cavernosography showed pathologic cavernosal drainage only via an ectopic penile vein into the femoral vein. After ligation of this pathologic draining vessel, 4 of 5 patients regained spontaneous erectability. One patient with pathologic bulbocavernosus reflex latencies needed intracavernosal injection of vasoactive drugs for full rigidity

Topological data analysis approaches to uncovering the timing of ring structure onset in filamentous networks

Improvements in experimental and computational technologies have led to significant increases in data available for analysis. Topological data analysis (TDA) is an emerging area of mathematical research that can identify structures in these data sets. Here we develop a TDA method to detect physical structures in a cell that persist over time. In most cells, protein filaments (actin) interact with motor proteins (myosins) and organize into polymer networks and higher-order structures. An example of these structures are ring channels that maintain constant diameters over time and play key roles in processes such as cell division, development, and wound healing. The interactions of actin with myosin can be challenging to investigate experimentally in living systems, given limitations in filament visualization \textit{in vivo}. We therefore use complex agent-based models that simulate mechanical and chemical interactions of polymer proteins in cells. To understand how filaments organize into structures, we propose a TDA method that assesses effective ring generation in data consisting of simulated actin filament positions through time. We analyze the topological structure of point clouds sampled along these actin filaments and propose an algorithm for connecting significant topological features in time. We introduce visualization tools that allow the detection of dynamic ring structure formation. This method provides a rigorous way to investigate how specific interactions and parameters may impact the timing of filamentous network organization.Comment: 20 pages, 9 figure

Modulation of Mutant Huntingtin N-Terminal Cleavage and Its Effect on Aggregation and Cell Death

Huntington’s disease (HD) is a neurodegenerative disorder caused by a polyglutamine expansion near the N-terminus of huntingtin. A neuropathological hallmark of Huntington’s disease is the presence of intracellular aggregates composed of mutant huntingtin N-terminal fragments in human postmortem brain, animal models, and cell culture models. It has been found that N-terminal fragments of the mutant huntingtin protein are more toxic than the full-length protein. Therefore, proteolytic processing of mutant huntingtin may play a key event in the pathogenesis of HD. Here, we present evidence that the region in huntingtin covering amino acids 116 to 125 is critical for N-terminal proteolytic processing. Within this region, we have identified mutations that either strongly reduce or enhance N-terminal cleavage. We took advantage of this effect and demonstrate that the mutation Δ121–122 within the putative cleavage region enhances N-terminal cleavage of huntingtin and the aggregation of N-terminal fragments. Furthermore, this particular deletion increased the activation of apoptotic processes and decreased neuronal cell viability. Our data indicate that the N-terminal proteolytic processing of mutant huntingtin can be modulated with an effect on aggregation and cell death rate