SHP-1 tyrosine phosphatase binding to c-Src kinase phosphor-dependent conformations: A comparative structural framework.

SHP-1 is a cytosolic tyrosine phosphatase that is primarily expressed in hematopoietic cells. It acts as a negative regulator of numerous signaling pathways and controls multiple cellular functions involved in cancer pathogenesis. This study describes the binding preferences of SHP-1 (pY536) to c-Srcopen (pY416) and c-Srcclose (pY527) through in silico approaches. Molecular dynamics simulation analysis revealed more conformational changes in c-Srcclose upon binding to SHP-1, as compared to its active/open conformation that is stabilized by the cooperative binding of the C-SH2 domain and C-terminal tail of SHP-1 to c-Src SH2 and KD. In contrast, c-Srcclose and SHP-1 interaction is mediated by PTP domain-specific WPD-loop (WPDXGXP) and Q-loop (QTXXQYXF) binding to c-Srcclose C-terminal tail residues. The dynamic correlation analysis demonstrated a positive correlation for SHP-1 PTP with KD, SH3, and the C-terminal tail of c-Srcclose. In the case of the c-Srcopen-SHP-1 complex, SH3 and SH2 domains of c-Srcopen were correlated to C-SH2 and the C-terminal tail of SHP-1. Our findings reveal that SHP1-dependent c-Src activation through dephosphorylation relies on the conformational shift in the inhibitory C-terminal tail that may ease the recruitment of the N-SH2 domain to phosphotyrosine residue, resulting in the relieving of the PTP domain. Collectively, this study delineates the intermolecular interaction paradigm and underlying conformational readjustments in SHP-1 due to binding with the c-Src active and inactive state. This study will largely help in devising novel therapeutic strategies for targeting cancer development.

Structural basis of constitutive c-Src kinase activity due to R175L and W118A mutations.

Cellular Src (c-Src) belongs to a non-receptor membrane-associated tyrosine kinase family that plays essential roles in cellular processes. Growing evidence suggests that R175L and W118A mutations in SH2/SH3 domains of c-Src functionally inactivate these domains leading to constitutive activation of kinase domain (KD). Here we modeled c-SrcR175L, c-SrcW118A and c-SrcW118A+R175L structures by inducing phosphorylation at Y416 or Y527, respectively to characterize the comparative dynamics in the active versus inactive states through molecular dynamics simulation assay. We observed more conformational readjustments in c-Srcopen than its close variants. In particular, C-terminal tail residues of c-SrcW118A-open and c-SrcW118A+R175L-open demonstrate significantly higher transitions. The cross-correlation analysis revealed an anticorrelation behavior in the motion of KD with respect to SH2, SH3 and the linker region of SrcW118A+R175L-open, while in c-SrcWT-open, SH2 and SH3 domains were anticorrelated, while KD and C-terminal tail motions were correlated. Due to these conformational differences, c-Src open forms exhibited lower interaction between pY527 and SH2 domain. Through detailed structural analysis, we observed a uniform myristate binding cavity in c-SrcWT-open, while the myristoyl pockets of mutant forms were deformed. We propose that constitutive activation of mutant Src forms may presumably be achieved by the prolonged membrane binding due to unusual conformations of C-terminal and myristoyl switch residues that may result in a higher dephosphorylation rate at pY527 in the myristoylated c-Src. Thus, our study establishes novel clues to decipher the constitutive activation status of c-Src in response to known mutations that may help in devising novel therapeutic strategies for cancer metastasis treatment.Communicated by Ramaswamy H. Sarma.

Improving junior doctor medicine prescribing and patient safety: An intervention using personalised, structured, video-enhanced feedback and deliberate practice.

AIMS: This research investigated the effectiveness of an intervention for improving the prescribing and patient safety behaviour among Foundation Year doctors. The intervention consisted of simulated clinical encounters with subsequent personalised, structured, video-enhanced feedback and deliberate practice, undertaken at the start of four-month sub-specialty rotations. METHODS: Three prospective, non-randomised control intervention studies were conducted, within two secondary care NHS Trusts in England. The primary outcome measure, error rate per prescriber, was calculated using daily prescribing data. Prescribers were grouped to enable a comparison between experimental and control conditions using regression analysis. A break-even analysis evaluated cost-effectiveness. RESULTS: There was no significant difference in error rates of novice prescribers who received the intervention when compared with those of experienced prescribers. Novice prescribers not participating in the intervention had significantly higher error rates (P = .026, 95% confidence interval [CI] Wald 0.093 to 1.436; P = .026, 95% CI 0.031 to 0.397) and patients seen by them experienced significantly higher prescribing error rates (P = .007, 95% CI 0.025 to 0.157). Conversely, patients seen by the novice prescribers who received the intervention experienced a significantly lower rate of significant errors compared to patients seen by the experienced prescribers (P = .04, 95% CI -0.068 to -0.001). The break-even analysis demonstrates cost-effectiveness for the intervention. CONCLUSION: Simulated clinical encounters using personalised, structured, video-enhanced feedback and deliberate practice improves the prescribing and patient safety behaviour of Foundation Year doctors. The intervention is cost-effective with potential to reduce avoidable harm.

Meta-analysis of medial-to-lateral versus lateral-to-medial colorectal mobilisation during laparoscopic colorectal surgery.

OBJECTIVES: To evaluate comparative outcomes of medial-to-lateral and lateral-to-medial colorectal mobilisation in patients undergoing laparoscopic colorectal surgery. METHODS: We conducted a systematic search of electronic databases and bibliographic reference lists. Perioperative mortality and morbidity, procedure time, length of hospital stay, rate of conversion to open procedure, and number of harvested lymph nodes were the outcome parameters. Combined overall effect sizes were calculated using fixed-effects or random-effects models. RESULTS: We identified eight comparative studies reporting a total of 1477 patients evaluating outcomes of medial-to-lateral (n = 626) and lateral-to-medial (n = 851) approaches in laparoscopic colorectal resection. The medial-to-lateral approach was associated with significantly lower rate of conversion to open (odds ratio (OR) 0.43, P = 0.001), shorter procedure time (mean difference (MD) - 32.25, P = 0.003) and length of hospital stay (MD - 1.54, P = 0.02) compared to the lateral-to-medial approach. However, there was no significant difference in mortality (risk difference (RD) 0.00, P = 0.96), overall complications (OR 0.78, P = 0.11), wound infection (OR 0.84, P = 0.60), anastomotic leak (OR 0.70, P = 0.26), bleeding (OR 0.60, P = 0.50), and number of harvested lymph nodes (MD - 1.54, P = 0.02) between two groups. Sub-group analysis demonstrated that the lateral-to-medial approach may harvest more lymph nodes in left-sided colectomy (MD - 1.29, P = 0.0009). The sensitivity analysis showed that overall complications were lower in the medial-to-lateral group (OR 0.72, P = 0.49). CONCLUSIONS: Our meta-analysis (level 2 evidence) showed that medial-to-lateral approach during laparoscopic colorectal resection may reduce procedure time, length of hospital stay and conversion to open procedure rate. Moreover, it may probably reduce overall perioperative morbidity. However, both approaches carry similar risk of mortality, and have comparable ability to harvest lymph nodes. Future high-quality randomised trials are required.

Routine monitoring for heparin-induced thrombocytopenia following lower limb arthroplasty: Is it necessary? A prospective study in a UK district general hospital.

INTRODUCTION: Heparin-induced thrombocytopenia (HIT) is a potentially life-threatening condition associated with heparin administration. Many orthopaedic units routinely prescribe low-molecular-weight heparins as thromboprophylaxis after hip and knee arthroplasty. HYPOTHESIS: We postulated that routine platelet monitoring following heparin administration is of no clinical benefit. We therefore asked: firstly, what was the rate of thrombocytopenia in a large population of patients undergoing lower limb arthroplasty? Secondly, did this rate justify routine platelet monitoring? MATERIALS AND METHODS: Unless contraindicated, all patients (n=1999, 53.05% female, mean age 69.23 years) at a UK district general hospital undergoing hip and knee arthroplasty were given daily prophylactic enoxaparin. Platelet counts were obtained between the 8th and 10th postoperative days and compared to preoperative baseline. A > 50% fall in platelet count was classified as "possible HIT". The minimal acceptable risk of thrombocytopenia was defined using The American College of Chest Physicians (ACCP) 2012 guidelines, which recommend monitoring platelet counts in patients receiving heparin where the expected risk of HIT is>1% and by descriptive cost-benefit analysis based on the cost of routine platelet monitoring in the clinical setting. RESULTS: Complete results were available for 1361 (68.1%) patients, comprising: 653 primary hips, 22 revision hips, 1 hip resurfacing, 665 primary knees, 19 revision knees and 1 unicompartmental knee replacement. Mean platelet level was 281.9×109/L preoperatively and 527.83×109/L postoperatively. Forty-four patients (3.2%) experienced a postoperative fall in platelet levels. However, no patient experienced a drop in platelets to less than 50% of the preoperative value. DISCUSSION: The incidence of HIT in the elective arthroplasty population is low. Therefore, routine postoperative monitoring of platelets is not necessary in this population of patients. LEVEL OF EVIDENCE: II, prospective study.

Improving the accuracy of HES comorbidity codes by better documentation in surgical admission proforma.

BACKGROUND: Poor documentation in medical notes can affect the quality of the source document for coding which can lead to inaccurate coding. This study aimed to determine the accuracy of Hospital Episode Statistics (HES) data for comorbidities and to establish whether better documentation in admission clerking proforma can improve the accuracy of codes for comorbidities in general surgical patients. METHODS: A clinical audit was conducted to assess the accuracy, sensitivity, specificity, positive predictive value and negative predictive value of HES codes for comorbidities in general surgical patients before and after implementing better documentation in admission clerking proforma. The following comorbidities were included: hypertension, ischaemic heart disease, diabetes, asthma, chronic obstructive pulmonary disease, cerebrovascular disease, chronic kidney disease and hypercholesterolaemia. Medical notes were used as reference standard and a target standard of 98% was determined for the above measures. RESULTS: Overall, on the initial audit, HES codes had substandard accuracy (90.5%, kappa = 0.599), sensitivity (47.71%, 95% confidence interval 38.05-57.49%) and negative predictive value (89.60%, 95% confidence interval 86.73-92.03%). HES codes for comorbidities were 100% specific with positive predictive value of 100%. Implementing better documentation in the admission clerking proforma improved the accuracy (99.67%, kappa = 0.985), sensitivity (97.4%, 95% confidence interval 90.93-99.68%) and negative predictive value (99.62%, 95% confidence interval 98.63-99.95%) significantly from the baseline (P<0.0001). CONCLUSIONS: Although HES codes can confidently predict the actual presence of the comorbidities, they have substandard accuracy and ability to rule out the presence of the comorbidities. Better documentation in clerking proforma can improve the accuracy and 'ruling out' ability of the HES codes. This can be achieved by improving knowledge and accountability of clinicians about documenting comorbidities.