Earthworms are commonly referred as environmental engineers and their guts are often compared with chemical reactors. However, modeling experiments to substantiate it are lacking. The aim of this study was to use established reactor models, particularly PFR, on the gut of the vermicomposting earthworm Eudrilus eugeniae to understand more on its digestion. To achieve the objective, a mathematical model based on first-order kinetics was framed and used to determine the pattern of digestion rates of nutrient indicators, namely total carbon (%), total nitrogen (%), C/N ratio, 13C (‰), and 15N (‰) at five intersections (pre-intestine, foregut, midgut A, midgut B, and hindgut) along the gut of E. eugeniae. The experimental results revealed that the concentrations of TC, TN, 13C, and 15N decreased during gut transit, whereas C/N ratio increased. The first-order model demonstrated that all the nutrients exhibit a linear pattern of digestion during gut transit, which supports the PFR model. On this basis, the present study concludes that the gut of E. eugeniae functions as PFR.
Understanding the basal gut bacterial community structure and the host metabolic composition is pivotal for the interpretation of laboratory treatments designed to answer questions pertinent to host-microbe interactions. In this study, we report for the first time the underlying gut microbiota and systemic metabolic composition in BALB/c mice during the acclimatisation period. Our results showed that stress levels were reduced in the first three days of the study when the animals were subjected to repetitive handling daily but the stress levels were increased when handling was carried out at lower frequencies (weekly). We also observed a strong influence of stress on the host metabolism and commensal compositional variability. In addition, temporal biological compartmental variations in the responses were observed. Based on these results, we suggest that consistency in the frequency and duration of laboratory handling is crucial in murine models to minimise the impact of stress levels on the commensal and host metabolism dynamics. Furthermore, caution is advised in consideration of the temporal delay effect when integrating metagenomics and metabonomics data across different biological matrices (i.e. faeces and urine).
In this article, modified κ-carrageenan hydrogel nanocomposites were synthesized to increase the release ability of carrageenan hydrogels under gastrointestinal conditions. The effect of MgO nanoparticle loading in a model drug (methylene blue) release is investigated. Characterization of hydrogels were carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Differential Scanning Calorimetry (DSC). Genipin was used to increase the delivery performance in gastrointestinal tract delivery by decreasing release in simulated stomach conditions and increasing release in simulated intestine conditions. It is shown that the amount of methylene blue released from genipin-cross-linked nanocomposites can be 67.5% higher in intestine medium and 56% lower in the stomach compared to κ-carrageenan hydrogel. It was found that by changing the nanoparticle loading and genipin concentration in the composite, the amount of drug released can be monitored. Therefore, applying nanoparticles appears to be a potential strategy to develop controlled drug delivery especially in gastrointestinal tract studies.
To better understand salmon GI tract microbial community dynamics in relation to diet, a feeding trial was performed utilising diets with different proportions of fish meal, protein, lipid and energy levels. Salmon gut dysfunction has been associated with the occurrence of casts, or an empty hind gut. A categorical scoring system describing expressed digesta consistency was evaluated in relation to GI tract community structure. Faster growing fish generally had lower faecal scores while the diet cohorts showed minor differences in faecal score though the overall lowest scores were observed with a low protein, low energy diet. The GI tract bacterial communities were highly dynamic over time with the low protein, low energy diet associated with the most divergent community structure. This included transiently increased abundance of anaerobic (Bacteroidia and Clostridia) during January and February, and facultatively anaerobic (lactic acid bacteria) taxa from February onwards. The digesta had enriched populations of these groups in relation to faecal cast samples. The majority of samples (60-86 %) across all diet cohorts were eventually dominated by the genus Aliivibrio. The results suggest that an interaction between time of sampling and diet is most strongly related to community structure. Digesta categorization revealed microbes involved with metabolism of diet components change progressively over time and could be a useful system to assess feeding responses.
In this study, microbial community dynamics were assessed within a simple in vitro model system in order to understand those changes influenced by diet. The abundance and diversity of bacteria were monitored within different treatment slurries inoculated with salmon faecal samples in order to mimic the effects of dietary variables. A total of five complete diets and two ingredients (plant meal) were tested. The total viable counts (TVCs) and sequencing data revealed that there was very clear separation between the complete diets and the plant meal treatments, suggesting a dynamic response by the allochthonous bacteria to the treatments. Automated ribosomal intergenic spacer analysis (ARISA) results showed that different diet formulations produced different patterns of fragments, with no separation between the complete diets. However, plant-based protein ingredients were clearly separated from the other treatments. 16S rRNA Illumina-based sequencing analysis showed that members of the genera Aliivibrio, Vibrio and Photobacterium became predominant for all complete diets treatments. The plant-based protein ingredient treatments only sustained weak growth of the genus Sphingomonas. In vitro based testing of diets could be a useful strategy to determine the potential impact of either complete feeds or ingredients on major fish gastrointestinal tract microbiome members.
Radionuclide imaging using (111)In, (99m)Tc and (153)Sm is commonly undertaken for the clinical investigation of gastric emptying, intestinal motility and whole gut transit. However the documented evidence concerning internal radiation dosimetry for such studies is not readily available. This communication documents the internal radiation dosimetry for whole gastrointestinal transit studies using (111)In, (99m)Tc and (153)Sm labeled formulations. The findings were compared to the diagnostic reference levels recommended by the United Kingdom Administration of Radioactive Substances Advisory Committee, for gastrointestinal transit studies.
Woody (lignocellulosic) plant biomass is an abundant renewable feedstock, rich in polysaccharides that are bound into an insoluble fiber composite with lignin. Marine crustacean woodborers of the genus Limnoria are among the few animals that can survive on a diet of this recalcitrant material without relying on gut resident microbiota. Analysis of fecal pellets revealed that Limnoria targets hexose-containing polysaccharides (mainly cellulose, and also glucomannans), corresponding with the abundance of cellulases in their digestive system, but xylans and lignin are largely unconsumed. We show that the limnoriid respiratory protein, hemocyanin, is abundant in the hindgut where wood is digested, that incubation of wood with hemocyanin markedly enhances its digestibility by cellulases, and that it modifies lignin. We propose that this activity of hemocyanins is instrumental to the ability of Limnoria to feed on wood in the absence of gut symbionts. These findings may hold potential for innovations in lignocellulose biorefining.
This study aimed to formulate floating gastroretentive tablets containing metformin hydrochloric acid (HCl), using various grades of hydrogel such as tamarind powders and xanthan to overcome short gastric residence time of the conventional dosage forms. Different concentrations of the hydrogels were tested to determine the formulation that could provide a sustained release of 12 h. Eleven formulations with different ratios of tamarind seed powder/tamarind kernel powder (TKP):xanthan were prepared. The physical parameters were observed, and in vitro drug-release studies of the prepared formulations were carried out. Optimal formulation was assessed for physicochemical properties, thermal stability, and chemical interaction followed by in vivo gamma scintigraphy study. MKP3 formulation with a TKP:xanthan ratio of 3:2 was found to have 99.87% release over 12 h. Furthermore, in vivo gamma scintigraphy study was carried out for the optimized formulation in healthy New Zealand White rabbits, and the pharmacokinetic parameters of developed formulations were obtained. 153Sm2O3 was used to trace the profile of release in the gastrointestinal tract of the rabbits, and the drug release was analyzed. The time (Tmax) at which the maximum concentration of metformin HCl in the blood (Cmax) was observed, and it was extended four times for the gastroretentive formulation in comparison with the formulation without polymers. Cmax and the half-life were found to be within an acceptable range. It is therefore concluded that MKP3 is the optimal formulation for sustained release of metformin HCl over a period of 12 h as a result of its floating properties in the gastric region.
Pharmacophagy of methyl eugenol (ME)--a highly potent male attractant, by Bactrocera papayae results in the hydroxylation of ME to sex pheromonal components, 2-ally-4,5-dimethoxyphenol (DMP) and (E)-coniferyl alcohol (CF). These compounds, which are also male attractants, are then sequestered and stored in the rectal gland prior to their release during courtship at dusk. Chemical analyses of the digestive tract (excluding the crop and rectal gland) showed the absence of the sex pheromonal components and their precursor, ME. However, B. papayae males were attracted to and fed on the ME-fed male hemolymph extracts but not on hemolymph extracts of ME-deprived males. After thin layer chromatography in a hexane:ethyl acetate solvent system, flies were attracted to and fed on the original point on the TLC plate where the hemolymph extract had been spotted, suggesting that the pheromone components were bound in polar complexes. Chemical analyses of the ME-fed male hemolymph and crop extracts revealed the presence of the sex pheromonal components. The presence of the ME-derived pheromonal components and the absence of ME in the hemolymph suggest that the hemolymph is involved in the transportation of sex pheromonal components from the crop to the rectal gland.
Aedes aegypti is a principal vector responsible for the transmission of dengue viruses (DENV). To date, vector control remains the key option for dengue disease management. To develop new vector control strategies, a more comprehensive understanding of the biological interactions between DENV and Ae. aegypti is required. In this study, a cDNA library derived from the midgut of female adult Ae. aegypti was used in yeast two-hybrid (Y2H) screenings against DENV2 envelope (E) protein. Among the many interacting proteins identified, carboxypeptidase B1 (CPB1) was selected, and its biological interaction with E protein in Ae. aegypti primary midgut cells was further validated. Our double immunofluorescent assay showed that CPB1-E interaction occurred in the endoplasmic reticulum (ER) of the Ae. aegypti primary midgut cells. Overexpression of CPB1 in mosquito cells resulted in intracellular DENV2 genomic RNA or virus particle accumulation, with a lower amount of virus release. Therefore, we postulated that in Ae. aegypti midgut cells, CPB1 binds to the E protein deposited on the ER intraluminal membranes and inhibits DENV2 RNA encapsulation, thus inhibiting budding from the ER, and may interfere with immature virus transportation to the trans-Golgi network.
Fatal acute methamphetamine (MA) poisoning in cases of internal drug trafficking is rarely described in the literature. This case study reports an MA 'body packer' who died from fatal methamphetamine intoxication due to leaking drug packages in the alimentary tract. The deceased was examined by postmortem computed tomography (PMCT), and the results were correlated to subsequent autopsy and toxicological findings. The deceased was arrested by the police when he was found disoriented in the city of Kuala Lumpur. He was transferred to the emergency department on suspicion of drug abuse. The initial drug screening was reactive for amphetamines. Shortly after admission to the hospital, he died despite rigorous resuscitation attempts. The postmortem plain chest and abdominal radiographs revealed multiple suspicious opacities in the gastrointestinal tract attributable to body packages. An unenhanced whole body PMCT revealed twenty-five drug packages, twenty-four in the stomach and one in the transverse colon. At least two were disintegrating, and therefore leaking. The autopsy findings were consistent with the PMCT results. Toxicology confirmed the diagnosis of fatal methamphetamine intoxication.
Fenestrations are pores within the liver sinusoidal endothelial cells (LSECs) that line the sinusoids of the highly vascularized liver. Fenestrations facilitate the transfer of substrates between blood and hepatocytes. With pseudocapillarization of the hepatic sinusoid in old age, there is a loss of fenestrations. LSECs are uniquely exposed to gut-derived dietary and microbial substrates delivered by the portal circulation to the liver. Here we studied the effect of 25 diets varying in content of macronutrients and energy on LSEC fenestrations using the Geometric Framework method in a large cohort of mice aged 15 mo. Macronutrient distribution rather than total food or energy intake was associated with changes in fenestrations. Porosity and frequency were inversely associated with dietary fat intake, while fenestration diameter was inversely associated with protein or carbohydrate intake. Fenestrations were also linked to diet-induced changes in gut microbiome, with increased fenestrations associated with higher abundance of Firmicutes and reduced abundance of Bacteroidetes Diet-induced changes in levels of several fatty acids (C16:0, C19:0, and C20:4) were also significantly inversely associated with fenestrations, suggesting a link between dietary fat and modulation of lipid rafts in the LSECs. Diet influences fenestrations and these data reflect both the key role of the LSECs in clearing gut-derived molecules from the vascular circulation and the impact these molecules have on LSEC morphology.
In this study, four different selected wall materials (namely gelatin, soy protein isolate, maltodextrin and Arabic gum) were applied for blueberry anthocyanin extract encapsulation. The effect of these wall material types on the release and degradation of anthocyanin and the modulation of gut microbiota during in vitro simulated gastrointestinal digestion and colonic fermentation were investigated. It was found that the encapsulation of anthocyanin extract using appropriate wall material could significantly enhance the colonic accessibility of anthocyanins. Soy protein isolate and gelatin delayed the release of anthocyanins, whereas the other two wall materials displayed no significant effect on the release time of anthocyanins. Gut microbiota mainly metabolized some phenolic compounds such as 4-hydroxycinnamic acid and chlorogenic acid. Meanwhile, different fermented anthocyanin extract microcapsule broth could significantly decrease the composition and abundance of Firmicutes and increase that of Bacteroidetes. Furthermore, the presence of anthocyanin extract microcapsules, especially those encapsulated with soy protein isolate, promoted the biosynthesis of short-chain fatty acids by gut microbiota. It is concluded that, amongst the wall materials studied, soy protein isolate appeared to be a functional and suitable candidate to delay anthocyanin release and prevent disease through the promotion of gut health.
Cellulose acetate phthalate-based pH-responsive hydrogel was synthesized for fabrication of polymeric matrix tablets for gastro-protective delivery of loxoprofen sodium. Cellulose acetate phthalate (CAP) was cross-linked with methacrylic acid (MAA) using free radical polymerization technique. Fourier transform infrared (FTIR) spectra confirmed the formation of cross-linked structure of CAP-co-poly(methacrylic acid). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed the thermal stability of polymeric networks, and scanning electron microscopy (SEM) and energy-dispersive X-ray spectrum (EDS) images unveiled that the prepared formulations were porous in nature and thus the developed formulations had shown better diffusibility. Swelling and in vitro drug release was performed at various pHs and maximum swelling and release was obtained at pH 7.4, while swelling and release rate was very low at pH 1.2 which confirmed the pH-responsive behavior of CAP-co-poly(MAA). CAP-co-poly(MAA) copolymer prevents the release of loxoprofen sodium into the stomach due to reduced swelling at gastric pH while showing significant swelling and drug release in the colon. Cytotoxicity studies revealed higher biocompatibility of fabricated hydrogel. Acute oral toxicity studies were performed for the evaluation and preliminary screening of safety profile of the developed hydrogels. Matrix tablets were evaluated for release behavior at simulated body pH. The investigations performed for analysis of hydrogels and fabricated matrix tablets indicated the controlled drug release and gastro-protective drug delivery of CAP-co-poly(MAA) hydrogels and pH-sensitive matrix tablets for targeted delivery of gastro-sensitive/irritative agents. Graphical abstract.