Adipogenic progenitors from obese human skeletal muscle give rise to functional white adipocytes that contribute to insulin resistance

BACKGROUND/OBJECTIVES

Recent reports indicate that inter/intramuscular adipose tissue (IMAT), composed by adipocytes underneath the deep fascia of the muscles, is positively correlated with aging, obesity and insulin resistance in humans. However, no molecular/cellular evidence is available to support these interactions. The current study aimed to better characterize human skeletal muscle-derived adipogenic progenitors obtained from obese volunteers and investigate the impact of derived adipocytes on insulin action in primary skeletal muscle cells.

METHODS

Primary cultured stroma-vascular fraction (SVF) obtained from vastus lateralis muscle biopsies of middle-aged obese subjects was immunoseparated (magnetic beads or flow cytometry). The characteristics and/or metabolic phenotype of CD56(+), CD56(-) and CD56(-)CD15(+) cellular fractions were investigated by complementary approaches (flow cytometry, cytology, quantitative PCR and metabolic assays). The effects of conditioned media from CD56(-)CD15(+) cells differentiated into adipocytes on insulin action and signaling in human primary myotubes was also examined.

RESULTS

Our data indicate that CD56(+) and CD56(-) cellular fractions isolated from cultured SVF of human muscle contain two distinct committed progenitors: CD56(+) cells (that is, satellite cells) as myogenic progenitors and CD15(+) cells as adipogenic progenitors, respectively. CD56(-)CD15(+)-derived adipocytes display the phenotype and metabolic properties of white adipocytes. Secretions of CD56(-)CD15(+) cells differentiated into functional white adipocytes reduced insulin-mediated non-oxidative glucose disposal (P=0.0002) and insulin signaling.

CONCLUSIONS

Using in-vitro models, we show for the first time that secretions of skeletal muscle adipocytes are able to impair insulin action and signaling of muscle fibers. This paracrine effect could explain, at least in part, the negative association between high levels of IMAT and insulin sensitivity in obesity and aging.

[Efficacy of intravitreal dexamethasone implants in macular edema excluding venous occlusions: results for a cohort of 80 patients]

INTRODUCTION

The intravitreal dexamethasone implant has shown efficacy in the treatment of macular edema (ME) arising after retinal venous occlusions (central or branch), and in the treatment of non-infectious uveitis. The purpose of this study was to evaluate the efficacy of this implant in the treatment of other diffuse macular edemas with an inflammatory mechanism.

MATERIALS AND METHODS

We carried out a retrospective cohort study over 2 years: from January 2012 to December 2013, including all patients who received at least one injection of intravitreal dexamethasone implant, excluding venous occlusions and non-infectious uveitis. The primary study parameter was the progression of visual acuity. The study protocol had the approval of the institutional review board of the respective clinical ethics committees, and was conducted in accordance to the tenets of the Declaration of Helsinki.

RESULTS

Eighty patients were included. Eighty-eight percent of patients were pseudophakic. The indications for treatment were: diabetic ME when anti-VEGF were ineffective (53%), ME after retinal detachment (RD) (22%), ME of Irvine-Gass syndrome (16%), ME after endophthalmitis (4%), macular telangiectasia (4%), ME secondary to retinitis pigmentosa (1%). The mean ETDRS visual acuity was 53.7 letters prior to injection, improving to 62.3 letters after injection (P<0.001). The average gain in visual acuity was 6.7 letters [4.53;8.84] (P<0.001) in patients treated for diabetic ME, 9.6 letters [6.1;13.1] (P<0.001) in patients with ME after RD, and 15.2 letters [10.25;20.28] (P<0.001) for Irvine-Gass syndrome. The mean duration of efficiency was 4.6 months, with a median of 3.8 months.

CONCLUSION

The intravitreal dexamethasone implant appears to be an effective second-line treatment even in patients with diabetic ME after failure or in the case of contraindication of anti-VEGF. It is also effective and well tolerated in patients with ME after RD, as well as in patients with Irvine-Gass syndrome.

[Diagnostic value of suspicion criteria for early-onset neonatal bacterial infection: report ten years after the Anaes recommendations]

BACKGROUND

Because clinical symptoms and biological markers are neither sensitive nor specific, newborns are frequently suspected of having an infection. In France, 30-50% of newborns are suspected of having early-onset sepsis (EOS) and many of them undergo laboratory tests and empirical antibiotic treatments while awaiting results. The aim of this study was to evaluate the diagnostic value of various suspicion criteria for EOS as recommended by the Anaes since 2002, and the value of umbilical cord blood procalcitonin (PCT), currently assayed in our maternity ward.

MATERIAL AND METHODS

This 4-year retrospective study in the CHU of Nantes included hospitalized newborns with suspected early neonatal infection. Infection status was established according to the Anaes definitions and clinical evolution.

RESULTS

The study included 2151 newborns. Among anamnestic criteria, only prematurity significantly increased the risk of EOS (relative risk of 3.1; 95% CI 1.4-7.0). The relative risk of infection for a symptomatic newborn was 12.2 (95% CI 4.9-30.2; P<0.0001). Laboratory test results were the most predictive criteria. The relative risk to be infected was 291.6 (95% CI 70.7-1,214.0; P<0.0001) with a blood cord PCT value>0.6 ng/L. The positive post-test probability was 28% (95% CI: 23-33) and the negative post-test probability was close to 0 (95% CI: 0-0).

CONCLUSION

Clinical criteria of postnatal life adaptation are more predictive of early-onset neonatal infection than anamnestic criteria are. The blood cord PCT value could be a helpful marker in the identification of infected newborns. PCT measured in umbilical cord blood could be included in a general algorithm in order to identify as soon as possible newborns with a high risk of EOS.

[Prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma genitalium infections in the emergency department]

STUDY OBJECTIVE

To estimate the prevalence of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Mycoplasma genitalium (MG) in patients under 31 years of age admitted to the emergency department of the University Hospital of Montpellier, for which a urinalysis was performed.

PATIENTS AND METHODS

CT, NG and MG specific real-time PCRs were performed in the urine samples from 301 patients between July 2010 and January 2011.

RESULTS

CT DNA was detected in 11% of patients, NG DNA in 3.7% of patients and MG DNA in one patient. Seventy-five percent of male patients and only 13% of women were diagnosed with sexually transmitted infection (STI). No patient with leucocyturia below 10(4)/mL had a positive PCR result for one of the three bacteria. Of the patients with leucocyturia greater or equal to 10(4)/mL, CT was detected in 23.4% of men and 11% of women, NG in 19.2% of men and 1% of women, and MG in 2.1% of men.

CONCLUSION

The prevalence of NG and CT detection in our population was high while that of MG was low. The diagnosis was facilitated by the use of PCR on the urine sample although this sample is not recommended for the molecular detection of bacterial agents of STIs and may explain the low detection of MG. The study allowed diagnosing STIs in 14.3% of our patient population.

[Multifocal placoid epitheliopathy and anti-hepatitis B vaccination]

The appearance of ocular pathological outcomes following an hepatitis B vaccination is uncommon. Among them, acute multiple posterior placoid pigment epitheliopathy has been noticed after injections of Engerix B recombinant vaccine. We describe the case of an 11-year-old child who presented this affection following a Genhevac B recombinant vaccine injection.

Enhancement of neurite outgrowth from central nervous system neurons in primary culture by thrombin inhibitors

Previous studies have shown that serine protease inhibitors promote neurite outgrowth from neuroblastoma cells, sympathetic neurons and sensory ganglia in culture. In the present study, a neurite promoting activity of thrombin inhibitors such as hirudin, D-Phe,Pro,Arg-CH2Cl, and paraamidinophenylalanine derivatives, was found in rat embryo (E17) septal neurons in primary culture. In contrast, no effect was shown on choline acetyltransferase activity of septal fragments in culture. These results suggest that thrombin inhibitors might interact with a thrombin-like protease involved in the control of neurite outgrowth.