Viscoelastic RNA entanglement and advective flow underlie nucleolar form and function

The nucleolus facilitates transcription, processing, and assembly of ribosomal RNA (rRNA), the most abundant RNA in cells. Nucleolar function is facilitated by its multiphase liquid properties, but nucleolar fluidity and its connection to ribosome biogenesis remain unclear. Here, we used quantitative imaging, mathematical modeling, and pulse-chase nucleotide labelling to map nucleolar rRNA dynamics. Inconsistent with a purely diffusive process, rRNA steadily expands away from the transcriptional sites, moving in a slow (~1 Å/s), radially-directed fashion. This motion reflects the viscoelastic properties of a highly concentrated gel of entangled rRNA, whose constant polymerization drives steady outward flow. We propose a new viscoelastic rRNA release model, where nucleolar rRNA cleavage and processing reduce entanglement, fluidizing the nucleolar periphery to facilitate release of mature pre-ribosomal particles.

São Paulo’s 2013 water crisis: a socially constructed disaster risk

Frequent cases of water scarcity in Brazil reveal a water governance and administration crisis. During the water crisis (2013-2016), the São Paulo Metropolitan Region experienced a disaster scenario. This article analyses how it was constituted as a socially constructed disaster episode. A case study was carried out in the Novo Recreio neighbourhood (Guarulhos, SP) through ethnographic observations, interviews, and newspaper articles. The results were analysed based on the Pressure and Release Model (PAR). It was concluded that the water crisis period in SPMR has disproportionately affected the Guarulhos population, especially in Novo Recreio. Furthermore, the study demonstrated that public policies and the neighbourhood's territorial formation are related to its population's current frail living conditions and increased socio-environmental vulnerability in the face of continuous water scarcity, thus corroborating the social construction of the risk of water scarcity.

MELOXICAM SELF-NANOEMULSIFYING DRUG DELIVERY SYSTEM: FORMULATION AND RELEASE KINETICS ANALYSIS

Objective: This study aimed to find the best SNEDDS meloxicam formula and analyze the release kinetics of meloxicam SNEDDS and non-SNEDDS using DDSolver. Methods: Meloxicam SNEDDS was prepared using sunflower seed oil, Cremophor RH 40 as a surfactant, and polyethylene glycol (PEG) 400 as a co-surfactant. Results: The best formula obtained subjected to the in vitro dissolution study was analyzed using DDSolver. The study shows one selected formula consists of 10% sunflower seed oil, 70% cremophor RH 40, and 20% PEG 400 with a 20.5 nm±12 nm droplet size. The dissolution study showed that SNEDDS could significantly increase the meloxicam release compared to the non-SNEDDS formulation. The kinetics of meloxicam release from SNEDDS formulations follow the Weibull release model (β = 1.00). Conclusion: This study concludes that SNEDDS best prepared in sunflower seeds oil: Chremophor RH 40: PEG 400 ratio of 1: 7: 2 and has the potency to increase the solubility and dissolution of meloxicam.

An opinion on the interpretation of social release in rats

This commentary concerns a controversial animal model in rodent social release research wherein one rat releases another rat from entrapment in a plastic tube. Release from the plastic tube has been proposed as a model to study empathically motivated behaviour. However, empathic motivations have been contested by others who have provided evidence for social reinforcement motivating release behaviour. Furthermore, helping, or other forms of pro-social behaviour could exist independent of empathy or empathetic motivation and the stimuli occasioning this helping behaviour are not known. In addition, there is a dearth in the citations of published studies whose results fail to support this model. In other words, the controversial aspect of the rodent social release model is often overlooked. This controversy is described in the current opinion piece.

Study and Evaluation of the release of Flavonoids extracted from various Eggplant cones from Semisolid Pharmaceutical Forms (In vitro)

Various semisolid pharmaceutical forms have been prepared from eggplant calyx extract which rich in flavonoids and antioxidants. These ingredients were titrated in the prepared extracts, and then incorporated into the prepared pharmaceutical forms. Eggplant calyxes were used for three varieties cultivated in Syria. The flavonoids were extracted from them by using several aqueous and organic solutions. Three types of extracts were prepared for each type of eggplant (aqueous, ethanolic 70%, methanolic). The ethanolic extract of black eggplant showed the highest content of flavonoids. The black eggplant extract contained the largest amount of flavonoids in the three types of extracts. The antioxidant capacity of the plant extracts was measured by measuring its ability to remove free radicals of the fixed root DPPH, and the ethanolic extract of the black eggplant showed the best antioxidant capacity. Three topical pharmaceutical formulas were prepared of the ethanolic extract 70% for the rectangular black eggplant calyx, and the kinetics of the release of the main components from them in vitro was studied using a Franz cell, within four hours to determine the release model for each formulation in order to compare the formulas and select the best one. The cream of the (o / w) pattern gave the best release of the active substances because it released the highest percentage (92%) after two hours and the release pattern was of the zero order, while the rest of the formulas had the highest percentage of release after four hours with some deficiency of the active substances in them.

Polymer Grafting of Graphene Oxide Through Esterification of Terephthalic Acid and Allyl Alcohol for Metronidazole Drug Delivery: Central Composite Design Optimization Study

The present study examined the direct esterification of terephthalic acid (TPA) with allyl alcohol (AA) on the graphene oxide (GO) surface in the presence of p-toluene sulfonic acid (PTSA) catalyst. Then, the surface of GO-TPAA was modified through polymerization reaction with 2,2’-azobisisobutyronitrile (AIBN) as a reaction initiator. The developed polymer was tested successfully as a nanocarrier for the metronidazole (MNZ) drug delivery. The resulting polymer was characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-Ray (EDX), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The parameters were optimized by response surface methodology (RSM) based on the central composite design (CCD) experimental design. The maximum adsorption (93.31%) was obtained at pH = 5, contact time of 15 min, and MNZ concentration of 15 mg L− 1. Analysis of variance (ANOVA) study proposed that the obtained equation for the adsorption of the MNZ is quadratic and it is significant for the model. The drug release behavior indicated that the amount of MNZ release from nanocarrier was significantly pH dependent. The released data were fitted into different kinetic release model equations for determining the best-fit release model for the nanocarrier. The adsorption kinetic data best fitted the pseudo-second-order model with a coefficient of determination (R2) of 0.9999. The adsorption process was endothermic, following the Langmuir isotherm model (R2 = 0.9956). MNZ release was studied in vitro using stimulated gastric fluid and stimulated intestinal fluid. The proposed nanoadsorbent can be useful for the rapid and efficient adsorption of the drug.