Thalamocortical bistable switch as a theoretical model of fibromyalgia pathogenesis inferred from a literature survey

Fibromyalgia (FM) is an unsolved central pain processing disturbance. We aim to provide a unifying model for FM pathogenesis based on a loop network involving thalamocortical regions, i.e., the ventroposterior lateral thalamus (VPL), the somatosensory cortex (SC), and the thalamic reticular nucleus (TRN). The dynamics of the loop have been described by three differential equations having neuron mean firing rates as variables and containing Hill functions to model mutual interactions among the loop elements. A computational analysis conducted with MATLAB has shown a transition from monostability to bistability of the loop behavior for a weakening of GABAergic transmission between TRN and VPL. This involves the appearance of a high-firing-rate steady state, which becomes dominant and is assumed to represent pathogenic pain processing giving rise to chronic pain. Our model is consistent with a bulk of literature evidence, such as neuroimaging and pharmacological data collected on FM patients, and with correlations between FM and immunoendocrine conditions, such as stress, perimenopause, chronic inflammation, obesity, and chronic dizziness. The model suggests that critical targets for FM treatment are to be found among immunoendocrine pathways leading to GABA/glutamate imbalance having an impact on the thalamocortical system

Simulations of black hole fueling in isolated and merging galaxies with an explicit, multiphase ISM

We study gas inflows onto supermassive black holes using hydrodynamics simulations of isolated galaxies and idealized galaxy mergers with an explicit, multiphase interstellar medium (ISM). Our simulations use the recently developed ISM and stellar evolution model called Stars and MUltiphase Gas in GaLaxiEs (SMUGGLE). We implement a novel super-Lagrangian refinement scheme that increases the gas mass resolution in the immediate neighborhood of the black holes (BHs) to accurately resolve gas accretion. We do not include black hole feedback in our simulations. We find that the complex and turbulent nature of the SMUGGLE ISM leads to highly variable BH accretion. BH growth in SMUGGLE converges at gas mass resolutions $\lesssim3\times10^3{\rm M_\odot}$. We show that the low resolution simulations combined with the super-Lagrangian refinement scheme are able to produce central gas dynamics and BH accretion rates very similar to that of the uniform high resolution simulations. We further explore BH fueling by simulating galaxy mergers. The interaction between the galaxies causes an inflow of gas towards the galactic centres and results in elevated and bursty star formation. The peak gas densities near the BHs increase by orders of magnitude resulting in enhanced accretion. Our results support the idea that galaxy mergers can trigger AGN activity, although the instantaneous accretion rate depends strongly on the local ISM. We also show that the level of merger-induced enhancement of BH fueling predicted by the SMUGGLE model is much smaller compared to the predictions by simulations using an effective equation of state model of the ISM.Comment: 16 pages, 10 figure

Ruolo dei mastociti nella fisiopatologia delle lesioni gastriche indotte da Helicobacter pylori. [Role of mast cells in the physiopathology of gastric lesions caused by Helicobacter pylori].

Routine observation of stained histological preparations for the detection of Helicobacter pylori (HP) has shown a variable presence of mast cells in the mucosa of patients suffering from gastritis. Our aim was to verify whether any correlations exist between HP positivity, type of gastritis and presence of mast cells. We examined 300 bioptic fragments of gastric mucosa obtained by diagnostic oesophagogastroduodenoscopy. The study population consisted of 88 patients with chronic superficial gastritis and 12 with chronic atrophic gastritis (59 males and 41 females). HP detection was performed on Giemsa-stained preparations. Mast cell detection was performed on Giemsa- and PAS-stained preparations. Seventy percent of chronic superficial gastritis cases were found to be HP-positive and mast cells were present in 90% of these and absent in 10%. In the chronic atrophic gastritis cases 50% were HP-positive and mast cells were present in 50% and absent in the rest. HP is regarded as the causal agent of type B gastritis. On the basis of our data a significant correlation was found (86%) between HP-positivity and presence of mast cells in the inflammatory gastric mucosa. Z9