Functional characterization of a conserved pair of NKR‐P1 receptors expressed by NK cells and T lymphocytes in liver and gut

Natural killer cell receptor protein 1 (NKR‐P1) molecules are C‐type lectin‐like receptors modulating cellular responses toward target cells expressing C‐type lectin‐like related (Clr) molecules. Although the function of the prototypic rat NKR‐P1A receptor and its inhibitory counterpart NKR‐P1B are known, little is known about NKR‐P1F and NKR‐P1G apart from their promiscuity for Clr ligands. Here we generated mAbs against both receptors for phenotypic and functional analyses in rat tissues. NKR‐P1F induced redirected lysis and robust Ca²⁺ signaling in NK cells, which were prevented by simultaneous engagement of NKR‐P1G. NKR‐P1G also inhibited NK‐cell lysis of Clr transfectants. NKR‐P1F was expressed by most NK cells and NKR‐P1A⁺ T cells in all tissues analyzed, and by many NKR‐P1A^? intestinal T cells, while NKR‐P1G was expressed by subsets of these cells with highest prevalence in gut and liver. In the intraepithelial compartment, the proportion of NKR‐P1A⁺ and NKR‐P1F⁺ cells was high at birth and thereafter declined, while NKR‐P1B⁺ and NKR‐P1G⁺ cells increased with age. Expression levels were also modulated by cytokines, with an increase of NKR‐P1B and NKR‐P1G induced by inflammatory cytokines, and a reduction of NKR‐P1A by TGF‐β. The physiological impact of NKR‐P1 receptors might thus be dependent on age, tissue, and inflammatory status.     

A CLAG3 Mutation in an Amphipathic Transmembrane Domain Alters Malaria Parasite Nutrient Channels and Confers Leupeptin Resistance

Erythrocytes infected with malaria parasites have increased permeability to ions and nutrients, as mediated by the plasmodial surface anion channel (PSAC) and recently linked to parasite clag3 genes. Although the encoded protein is integral to the host membrane, its precise contribution to solute transport remains unclear because it lacks conventional transmembrane domains and does not have homology to ion channel proteins in other organisms. Here, we identified a probable CLAG3 transmembrane domain adjacent to a variant extracellular motif. Helical-wheel analysis revealed strict segregation of polar and hydrophobic residues to opposite faces of a predicted α-helical transmembrane domain, suggesting that the domain lines a water-filled pore. A single CLAG3 mutation (A1210T) in a leupeptin-resistant PSAC mutant falls within this transmembrane domain and may affect pore structure. Allelic-exchange transfection and site-directed mutagenesis revealed that this mutation alters solute selectivity in the channel. The A1210T mutation also reduces the blocking affinity of PSAC inhibitors that bind on opposite channel faces, consistent with global changes in channel structure. Transfected parasites carrying this mutation survived a leupeptin challenge significantly better than a transfection control did. Thus, the A1210T mutation contributes directly to both altered PSAC activity and leupeptin resistance. These findings reveal the molecular basis of a novel antimalarial drug resistance mechanism, provide a framework for determining the channel''s composition and structure, and should guide the development of therapies targeting the PSAC.     

The outcome of surgical fixation of mid shaft clavicle fractures; looking at patient satisfaction and comparing surgical approaches

Introduction:

Clavicle fractures represent 2.5% of fractures in adults and almost 44% of shoulder injuries. The treatment is usually non-surgical with good results; however, significantly displaced fractures can be associated with high non-union rate and therefore many would advocate surgical fixation. This is traditionally carried out by direct approach over the clavicle but an infraclavicular approach has also been used for clavicular fixation. The aim of this study was to identify the main indications for surgical intervention at our unit and patient satisfaction following surgery. We also wanted to compare the direct and the infraclavicular surgical approaches in relation to the outcome of surgical intervention.

Materials and Methods:

Retrospective study looking at all the clavicle fractures managed surgically over 5 years at our department. Information relating to surgical indication, surgical approach, complications, outcome, patient satisfaction, and oxford shoulder score were collected.

Results:

A total of 35 patients were identified, the majority were males (n = 25) and most (n = 29) were working at the time of injury. The commonest indication for surgery was displacement with shortening (n = 16). The infraclavicular approach was used in the majority of patients (n = 21), the rest (n = 14) had direct incision. Evidence of radiological and union was achieved in all patients after an average of 13 (8-24) weeks. There were no major complications but minor complications were reported in 28% and 19% of cases with direct and infraclavicular approaches, respectively. Plates were removed from six symptomatic patients; infraclavicular (n = 2) and direct approach (n = 4). Four asymptomatic plates were removed on patients’ requests. All patients returned to work (after an average 2.6 months), had good oxford shoulder score between 12-20, regardless of the surgical approach used. All patients except one would recommend it to a friend.

Conclusion:

Our study showed excellent surgical outcome for displaced clavicle fractures supported by the high union rate, good oxford shoulder score, high return to work rate, and good patient''s satisfaction. The number of minor complications and symptomatic metal work removal was less in the infraclavicular approach.     

The role of Grey Scale Inversion Imaging (GSII) as a diagnostic tool of neck of femur fractures: is it more effective?

Emergency Radiology - Grey Scale Inversion Imaging (GSII), a radiology reading software, has been utilized to improve anatomical and pathological delineation and consequently increase the...