Mechanical strain stimulates COPII-dependent secretory trafficking via Rac1

Cells are constantly exposed to various chemical and physical stimuli. While much has been learned about the biochemical factors that regulate secretory trafficking from the endoplasmic reticulum (ER), much less is known about whether and how this trafficking is subject to regulation by mechanical signals. Here, we show that subjecting cells to mechanical strain both induces the formation of ER exit sites (ERES) and accelerates ER-to-Golgi trafficking. We found that cells with impaired ERES function were less capable of expanding their surface area when placed under mechanical stress and were more prone to develop plasma membrane defects when subjected to stretching. Thus, coupling of ERES function to mechanotransduction appears to confer resistance of cells to mechanical stress. Furthermore, we show that the coupling of mechanotransduction to ERES formation was mediated via a previously unappreciated ER-localized pool of the small GTPase Rac1. Mechanistically, we show that Rac1 interacts with the small GTPase Sar1 to drive budding of COPII carriers and stimulates ER-to-Golgi transport. This interaction therefore represents an unprecedented link between mechanical strain and export from the ER.

[Diagnostic issues of lymphogranuloma venereum: A case series of 5 patients]

INTRODUCTION

Lymphogranuloma venereum (LG) is a sexually transmitted infection (STI) caused by Chlamydia trachomatis L serovar.

METHODS

These five consecutive cases aim to highlight the risk of LG misdiagnosis, in case of initial presentation with isolated inguinal adenitis.

RESULTS

Five men (mean age: 30±7 years) were seen in an internal medicine department, for inguinal adenopathy. One patient had clinical signs of urethritis. None presented an associated rectitis. Three patients had a history of STI, and two had a discovery of related HIV disease. Urinary polymerase chain reaction (PCR) was positive for the symptomatic patient and negative for the others. Lymph node PCR was positive in all patients within a L2b serotype (searched in 4 out of 5 cases).

CONCLUSION

LG should be evoked in any patient with inguinal adenomegaly, particularly in case of STI history or risk factors. Negativity of urinary PCR should lead to further investigations, essentially a lymph node cytopuncture to evidence C. trachomatis.

Implementation of a simple innovative system for postprescription antibiotic review based on computerized tools with shared access

BACKGROUND

Controlling antibiotic use in healthcare establishments limits their consumption and the emergence of bacterial resistance.

AIM

To evaluate the efficiency of an innovative antibiotic stewardship strategy implemented over three years in a university hospital.

METHODS

An antimicrobial multi-disciplinary team (AMT) [pharmacist, microbiologist and infectious disease specialist (IDS)] conducted a postprescription review. Specific coding of targeted antibiotics (including broad-spectrum β-lactams, glycopeptides, lipopeptides, fluoroquinolones and carbapenems) in the computerized physician order entry allowed recording of all new prescriptions. The data [patient, antibiotic(s), prescription start date, etc.] were registered on an AMT spreadsheet with shared access, where the microbiologist's opinion on the drug choice, based on available microbiology results, was entered. When the microbiologist and pharmacist did not approve the antibiotic prescribed, a same-day alert was generated and sent to the IDS. That alert led the IDS to re-evaluate the treatment.

FINDINGS

From 2012 to 2014, 2106 targeted antibiotic prescriptions were reviewed. Among them, 389 (18.5%) generated an alert and 293 (13.9%) were re-evaluated by the IDS. Recommendations (mostly de-escalation or discontinuation) were necessary for 136 (46.4%) and the prescribers' acceptance rate was 97%. The estimated intervention time was <30 min/day for each AMT member. This system allowed correct use of targeted antibiotics for 91.8% of prescriptions, but had no significant impact on targeted antibiotic consumption.

CONCLUSION

This computerized, shared access, antibiotic stewardship strategy seems to be time saving, and effectively limited misuse of broad-spectrum antibiotics.

[Congestive heart failure in the aged. Diagnosis]

THREE DIAGNOSTIC PITFALLS: The difficulty in diagnosing congestive heart failure in the elderly subject is basically caused by three factors. First, clinical expression is often atypical. Secondly, severity is often underestimated as the prevalence of asymptomatic systolic dysfunction increases with age. Half of all cases of left ventricular systolic dysfunction go unrecognized if clinical signs alone are considered. Finally, the pathophysiology of diastolic dysfunction, which predominates in the over 75 population, is still poorly understood. COMPLEMENTARY EXPLORATIONS: As the clinical signs are the same whatever the mechanism of the ventricular dysfunction, echocardiography is the key exploration for diagnosis and for guiding management. Comorbidity is often a confounding factor preventing precise diagnosis and risk stratification.