Rheology, granule growth and granule strength: Application to the wet granulation of lactose–MCC mixtures

This study aims at better understanding the wet granulation process of a binary mixture composed of microcrystalline cellulose (water insoluble) and lactose (water soluble). It investigates the effect of formulation (proportion of the different components in the mixture) on the granule growth kinetics, the evolution of granule morphology during granulation, the wet mass consistency and dry granule trength of the end product. Additionally the influence of mixer design has been studied by up scaling the process from the 1.9 L Mi-pro high shear mixer used as the reference scale to a 6 L Diosna P1-6 high shear mixer. The scale-up rules investigated were constant impeller tip speed and constant Froude number. Our results allowed us to draw the following conclusions: – The increase in MCC content is found to increase the optimum binder requirement for granulation, wet mass consistency and dry granule strength. – Granule growth takes place in three distinct stages: wetting, nucleation and growth. These stages can be identified with the help of the recorded torque values during the granulation process or by the evolution of granule size and granule morphology. – The characterization of the starting materials by moisture sorption isotherms brings more insight to the role of each component during the granulation process. – The increase of the granulation scale has little influence on the observed growth mechanism. However bi-modality of the granule size distribution is increased, wet mass consistency and dry granule strength are decreased with increasing scale of operation

Granule Cell Dispersion in Human Temporal Lobe Epilepsy: Proteomics investigation of neurodevelopmental migratory pathways

Granule cell dispersion (GCD) is a common pathological feature observed in the hippocampus of patients with Mesial Temporal Lobe Epilepsy (MTLE). Pathomechanisms underlying GCD remain to be elucidated, but one hypothesis proposes aberrant reactivation of neurodevelopmental migratory pathways, possibly triggered by febrile seizures. This study aims to compare the proteomes of basal and dispersed granule cells in the hippocampus of eight MTLE patients with GCD to identify proteins that may mediate GCD in MTLE. Quantitative proteomics identified 1882 proteins, of which 29% were found in basal granule cells only, 17% in dispersed only and 54% in both samples. Bioinformatics analyses revealed upregulated proteins in dispersed samples were involved in developmental cellular migratory processes, including cytoskeletal remodelling, axon guidance and signalling by Ras homologous (Rho) family of GTPases (P<0.01). The expression of two Rho GTPases, RhoA and Rac1, was subsequently explored in immunohistochemical and in situ hybridisation studies involving eighteen MTLE cases with or without GCD, and three normal post mortem cases. In cases with GCD, most dispersed granule cells in the outer-granular and molecular layers have an elongated soma and bipolar processes, with intense RhoA immunolabelling at opposite poles of the cell soma, while most granule cells in the basal granule cell layer were devoid of RhoA. A higher density and percentage of cells expressing RhoA was observed in cases with GCD than without GCD (P<0.004). In GCD cases, the density and percentage of cells expressing RhoA was significantly higher in the inner molecular layer than granule cell layer (P<0.026), supporting proteomic findings. In situ hybridisation studies using probes against RHOA and RAC1 mRNAs revealed fine peri- and nuclear puncta in granule cells of all cases. The density of cells expressing RHOA mRNAs were significantly higher in the inner molecular layer of cases with GCD than without GCD(P=0.05). In summary, our study has found limited evidence for ongoing adult neurogenesis in the hippocampus of patients with MTLE, but evidence of differential dysmaturation between dispersed and basal granule cells has been demonstrated, and elevated expression of Rho GTPases in dispersed granule cells may contribute to the pathomechanisms underpinning GCD in MTLE

Wet granulation in laboratory scale high shear mixers: Effect of binder properties

The effect of binder properties on torque curves, granule growth kinetics, wet mass consistency and dry granule strength has been investigated in this study. Granulation runs have been performed on a fine cohesive microcrystalline cellulose powder (Avicel 105, d50 = 20 μm) in two types of laboratory high shear mixers: a Mi-Pro high shear mixer using a 1.9 L bowl and a 6 L Diosna high shear mixer. Binders used included ultra-pure water and solutions of varying concentrations of PVP and HPMC allowing us to cover different values for parameters like viscosity and work of adhesion. Torque curves recorded during granulation are found to allow good control of the process. Optimum liquid requirement for granulation has been found to vary with binder type and decrease with increasing viscosity while granule growth kinetics has been found to be to be related to the work of adhesion for low viscosity binders. Granule strength has been evaluated for wet granules by the means of wet mass consistency measurements on a mixer torque rheometer and for dried granules by means of uniaxial compression tests on a Texture Analyser mechanical testing machine. For low viscosity binders both wet mass consistency and dry granule strength have been found to depend on the work of adhesion. For high viscosity bindershigherwet mass consistencies but lower dry granule strengths have been observed. Granulating on the larger 6 L scale has shown that constant impeller tip speed offers good agreement in terms of mean granule size however granule size distribution seems to be scale dependan

Population-scale organization of cerebellar granule neuron signaling during a visuomotor behavior.

Granule cells at the input layer of the cerebellum comprise over half the neurons in the human brain and are thought to be critical for learning. However, little is known about granule neuron signaling at the population scale during behavior. We used calcium imaging in awake zebrafish during optokinetic behavior to record transgenically identified granule neurons throughout a cerebellar population. A significant fraction of the population was responsive at any given time. In contrast to core precerebellar populations, granule neuron responses were relatively heterogeneous, with variation in the degree of rectification and the balance of positive versus negative changes in activity. Functional correlations were strongest for nearby cells, with weak spatial gradients in the degree of rectification and the average sign of response. These data open a new window upon cerebellar function and suggest granule layer signals represent elementary building blocks under-represented in core sensorimotor pathways, thereby enabling the construction of novel patterns of activity for learning

Interaction between Granulation and Small-Scale Magnetic Flux Observed by Hinode

We study the relationship between granular development and magnetic field evolution in the quiet Sun. 6 typical cases are displayed to exhibit interaction between granules and magnetic elements, and we have obtained the following results. (1) A granule develops centrosymmetrically when no magnetic flux emerges within the granular cell. (2) A granule develops and splits noncentrosymmetrically while flux emerges at an outer part of the granular cell. (3) Magnetic flux emergence as a cluster of mixed polarities is detected at the position of a granule as soon as the granule breaks up. (4) A dipole emerges accompanying with the development of a granule, and the two elements of the dipole root in the adjacent intergranular lanes and face each other across the granule. Advected by the horizontal granular motion, the positive element of the dipole then cancels with pre-existing negative flux. (5) Flux cancellation also takes place between a positive element, which is advected by granular flow, and its surrounding negative flux. (6) While magnetic flux cancellation takes place at a granular cell, the granule shrinks and then disappears. (7) Horizontal magnetic fields enhance at the places where dipoles emerge and where opposite polarities cancel with each other, but only the horizontal fields between the dipolar elements point orderly from the positive element to the negative one. Our results reveal that granules and small-scale magnetic flux influence each other. Granular flow advects magnetic flux, and magnetic flux evolution suppresses granular development. There exist extremely large Doppler blue-shifts at the site of one cancelling magnetic element. This phenomenon may be caused by the upward flow produced by magnetic reconnection below the photosphere.Comment: 8 figures, 13 pages. RAA, in pres

Drug-induced stress granule formation protects sensory hair cells in mouse cochlear explants during ototoxicity

Stress granules regulate RNA translation during cellular stress, a mechanism that is generally presumed to be protective, since stress granule dysregulation caused by mutation or ageing is associated with neurodegenerative disease. Here, we investigate whether pharmacological manipulation of the stress granule pathway in the auditory organ, the cochlea, affects the survival of sensory hair cells during aminoglycoside ototoxicity, a common cause of acquired hearing loss. We show that hydroxamate (-)-9, a silvestrol analogue that inhibits eIF4A, induces stress granule formation in both an auditory cell line and ex-vivo cochlear cultures and that it prevents ototoxin-induced hair-cell death. In contrast, preventing stress granule formation using the small molecule inhibitor ISRIB increases hair-cell death. Furthermore, we provide the first evidence of stress granule formation in mammalian hair cells in-vivo triggered by aminoglycoside treatment. Our results demonstrate that pharmacological induction of stress granules enhances cell survival in native-tissue, in a clinically-relevant context. This establishes stress granules as a viable therapeutic target not only for hearing loss but also other neurodegenerative diseases.EI:595 - Action on Hearing Loss; 091092/Z/09/Z - Wellcome Trust (Wellcome); MR/N004329/1 - RCUK | Medical Research Council (MRC)Published versio

Autonomous Systems as Legal Agents: Directly by the Recognition of Personhood or Indirectly by the Alchemy of Algorithmic Entities

The clinical manifestations of platelet dense (δ) granule defects are easy bruising, as well as epistaxis and bleeding after delivery, tooth extractions and surgical procedures. The observed symptoms may be explained either by a decreased number of granules or by a defect in the uptake/release of granule contents. We have developed a method to study platelet dense granule storage and release. The uptake of the fluorescent marker, mepacrine, into the platelet dense granule was measured using flow cytometry. The platelet population was identified by the size and binding of a phycoerythrin-conjugated antibody against GPIb. Cells within the discrimination frame were analysed for green (mepacrine) fluorescence. Both resting platelets and platelets previously stimulated with collagen and the thrombin receptor agonist peptide SFLLRN was analysed for mepacrine uptake. By subtracting the value for mepacrine uptake after stimulation from the value for uptake without stimulation for each individual, the platelet dense granule release capacity could be estimated. Whole blood samples from 22 healthy individuals were analysed. Mepacrine incubation without previous stimulation gave mean fluorescence intensity (MFI) values of 83±6 (mean ± 1 SD, range 69–91). The difference in MFI between resting and stimulated platelets was 28±7 (range 17–40). Six members of a family, of whom one had a known δ-storage pool disease, were analysed. The two members (mother and son) who had prolonged bleeding times also had MFI values disparate from the normal population in this analysis. The values of one daughter with mild bleeding problems but a normal bleeding time were in the lower part of the reference interval