Differential activation and function of Rho GTPases during Salmonella–host cell interactions

Salmonella enterica, the cause of food poisoning and typhoid fever, has evolved sophisticated mechanisms to modulate Rho family guanosine triphosphatases (GTPases) to mediate specific cellular responses such as actin remodeling, macropinocytosis, and nuclear responses. These responses are largely the result of the activity of a set of bacterial proteins (SopE, SopE2, and SopB) that, upon delivery into host cells via a type III secretion system, activate specific Rho family GTPases either directly (SopE and SopE2) or indirectly (SopB) through the stimulation of an endogenous exchange factor. We show that different Rho family GTPases play a distinct role in Salmonella-induced cellular responses. In addition, we report that SopB stimulates cellular responses by activating SH3-containing guanine nucleotide exchange factor (SGEF), an exchange factor for RhoG, which we found plays a central role in the actin cytoskeleton remodeling stimulated by Salmonella. These results reveal a remarkable level of complexity in the manipulation of Rho family GTPases by a bacterial pathogen

Diversification of a Salmonella Virulence Protein Function by Ubiquitin-Dependent Differential Localization

SummaryMany bacterial pathogens and symbionts utilize type III secretion systems to deliver bacterial effector proteins into host cells. These effector proteins have the capacity to modulate a large variety of cellular functions in a highly regulated manner. Here, we report that the phosphoinositide phosphatase SopB, a Salmonella Typhimurium type III secreted effector protein, diversifies its function by localizing to different cellular compartments in a ubiquitin-dependent manner. We show that SopB utilizes the same enzymatic activity to modulate actin-mediated bacterial internalization and Akt activation at the plasma membrane and vesicular trafficking and intracellular bacterial replication at the phagosome. Thus, by exploiting the host cellular machinery, Salmonella Typhimurium has evolved the capacity to broaden the functional repertoire of a virulence factor to maximize its ability to modulate cellular functions

Two distinct cytoplasmic regions of the β2 integrin chain regulate RhoA function during phagocytosis

αMβ2 integrins mediate phagocytosis of opsonized particles in a process controlled by RhoA, Rho kinase, myosin II, Arp2/3, and actin polymerization. αMβ2, Rho, Arp2/3, and F-actin accumulate underneath bound particles; however, the mechanism regulating Rho function during αMβ2-mediated phagocytosis is poorly understood. We report that the binding of C3bi-opsonized sheep red blood cells (RBCs) to αMβ2 increases Rho-GTP, but not Rac-GTP, levels. Deletion of the cytoplasmic domain of β2, but not of αM, abolished Rho recruitment and activation, as well as phagocytic uptake. Interestingly, a 16–amino acid (aa) region in the membrane-proximal half of the β2 cytoplasmic domain was necessary for activating Rho. Three COOH-terminal residues (aa 758–760) were essential for β2-induced accumulation of Rho at complement receptor 3 (CR3) phagosomes. Activation of Rho was necessary, but not sufficient, for its stable recruitment underneath bound particles or for uptake. However, recruitment of active Rho was sufficient for phagocytosis. Our data shed light on the mechanism of outside-in signaling, from ligated integrins to the activation of Rho GTPase signaling

Osteometric Dimension of Stapes

Background: In the present study an attempt is made to study the morphometric analysis of ear ossicles to compare and evaluate the various morphometric parameters for designing the prosthesis used by Otologist in people of Gujarat. Aim: To study normal values of stapes this helps in making of stapes prostheses for otologists. Material and Method: Present study was carried out on 60 stapes in anatomy department at 3 medical colleges namely Shri M.P. Shah Govt. Medical College, Jamnagar, Govt. Medical College, Bhavnagar and P.D.U Medical College, Rajkot. The present study was conducted after approval from the institutional ethics committee. Results: the mean total height of stapes was 3.33 ± 0.25 mm, ranging from a minimum of 2.86mm to maximum of 3.9mm. The mean length of footplate of stapes was 2.78 ± 0.15 mm, ranging from a minimum of 2.41mm to maximum of 3.11mm. The mean width of footplate of stapes was 1.34 ± 0.13 mm, ranging from a minimum of 1.05 mm to maximum of 1.73 mm. Conclusion: The results of parameters of the ear ossicles are very helpful in making ear ossicles prosthesis in ossicular chain pathology in Guajarati population. Variation in the dimension of the ear ossicles might be due to racial difference or regional population difference in India. Variation in the dimension of ear ossicles might be due to various types of instruments used for measurement; methods used for measurement of ossicles or inter observer error by other workers

Evaluation of shearing time sufficient for effective liquid metal processing

Melt shearing has been suggested to be an efficient means of structure refinement through oxide dispersion and fragmentation. One of the process parameters that needs to be optimized is the shearing time. In this paper, the effect of shearing time on alumina powder refinement was studied in a model system with water as a working fluid. The established time was taken as a first approximation for experiments with the liquid metals processing by a high shear device based on a rotor–stator technology. The water model findings were confirmed experimentally on liquid aluminum alloys, and indicate that the optimal time of mixing is equal to 4 min in fully agitated conditions for the volume of 2.7 dm3.Allocation of the equipment in the BCAST, Brunel University London is highly appreciated. The first author is grateful for Ph.D. study funding from Institute of Materials and Manufacturing, Brunel University London. The authors would like to acknowledge Prof Z. Fan who initiated this research

Acute otitis externa: Consensus definition, diagnostic criteria and core outcome set development.

OBJECTIVE: Evidence for the management of acute otitis externa (AOE) is limited, with unclear diagnostic criteria and variably reported outcome measures that may not reflect key stakeholder priorities. We aimed to develop 1) a definition, 2) diagnostic criteria and 3) a core outcome set (COS) for AOE. STUDY DESIGN: COS development according to Core Outcome Measures in Effectiveness Trials (COMET) methodology and parallel consensus selection of diagnostic criteria/definition. SETTING: Stakeholders from the United Kingdom. SUBJECTS AND METHODS: Comprehensive literature review identified candidate items for the COS, definition and diagnostic criteria. Nine individuals with past AOE generated further patient-centred candidate items. Candidate items were rated for importance by patient and professional (ENT doctors, general practitioners, microbiologists, nurses, audiologists) stakeholders in a three-round online Delphi exercise. Consensus items were grouped to form the COS, diagnostic criteria, and definition. RESULTS: Candidate COS items from patients (n = 28) and literature (n = 25) were deduplicated and amalgamated to a final candidate list (n = 46). Patients emphasised quality-of-life and the impact on daily activities/work. Via the Delphi process, stakeholders agreed on 31 candidate items. The final COS covered six outcomes: pain; disease severity; impact on quality-of-life and daily activities; patient satisfaction; treatment-related outcome; and microbiology. 14 candidate diagnostic criteria were identified, 8 reaching inclusion consensus. The final definition for AOE was 'diffuse inflammation of the ear canal skin of less than 6 weeks duration'. CONCLUSION: The development and adoption of a consensus definition, diagnostic criteria and a COS will help to standardise future research in AOE, facilitating meta-analysis. Consulting former patients throughout development highlighted deficiencies in the outcomes adopted previously, in particular concerning the impact of AOE on daily life

Manipulation of the host actin cytoskeleton by

Salmonella — all in the name of entr