Using Doppler shift induced by Galvanometric mirror scanning to reach shot noise limit with laser optical feedback imaging setup.

This paper proposes what we believe is a new method to remove the contribution of parasitic reflections in the images of the laser optical feedback imaging (LOFI) technique. This simple method allows us to extend the LOFI technique to long-distance applications, as imaging through a fog or a smoke. The LOFI technique is an ultrasensitive imaging technique that is interesting for imaging objects through a scattering medium. However, the LOFI sensitivity can be dramatically limited by parasitic optical feedback occurring in the experimental setup. In previous papers [Appl. Opt.48, 64 (2009)10.1364/AO.48.000064APOPAI1559-128X, Opt. Lett.37, 2514 (2012)10.1364/OL.37.002514OPLEDP0146-9592], we already have proposed methods to filter a parasitic optical feedback, but they are not well suited to metric working distances. This new method uses a Doppler frequency shift induced by the moving mirror used to scan the object to be imaged. Using this Doppler frequency shift, we can distinguish the photons reflected by the target and the parasitic photons reflected by the optical components in the experimental setup. In this paper, we demonstrated theoretically and experimentally the possibility to filter the parasitic reflection in LOFI images using the Doppler frequency shift. This method significantly improves the signal-to-noise ratio by a factor 15 and we can obtain a shot noise limited image through a scattering medium of an object at 3 m from the detector.

Generation of ultrahigh and tunable repetition rates in CW injection-seeded frequency-shifted feedback lasers.

We show both theoretically and experimentally that frequency-shifted feedback (FSF) lasers seeded with a single frequency laser can generate Fourier transform-limited pulses with a repetition rate tunable and limited by the spectral bandwidth of the laser. We demonstrate experimentally in a FSF laser with a 150 GHz spectral bandwidth, the generation of 6 ps-duration pulses at repetition rates tunable over more than two orders of magnitude between 0.24 and 37 GHz, by steps of 80 MHz. A simple linear analytical model i.e. ignoring both dynamic and non-linear effects, is sufficient to account for the experimental results. This possibility opens new perspectives for various applications where lasers with ultra-high repetition rates are required, from THz generation to ultrafast data processing systems.

Deep and optically resolved imaging through scattering media by space-reversed propagation.

We propose a novel technique of microscopy to overcome the effects of both scattering and limitation of the accessible depth due to the objective working distance. By combining laser optical feedback imaging with acoustic photon tagging and synthetic aperture refocusing we demonstrate an ultimate shot noise sensitivity at low power (required to preserve the tissues) and a high resolution beyond the microscope working distance. More precisely, with a laser power of 10 mW, we obtain images with a micrometric resolution over approximately eight transport mean free paths, corresponding to 1.3 times the microscope working distance. Various applications such as biomedical diagnosis and research and development of new drugs and therapies can benefit from our imaging setup.

Acousto-optic laser optical feedback imaging.

We present a photon noise and diffraction-limited imaging method combining an imaging laser and ultrasonic waves. The laser optical feedback imaging (LOFI) technique is an ultrasensitive imaging method for imaging objects through or embedded within a scattering medium. However, LOFI performances are dramatically limited by parasitic optical feedback occurring in the experimental setup. In this Letter, we have tagged the ballistic photons by an acousto-optic effect in order to filter the parasitic feedback effect and to reach the theoretical and ultimate sensitivity of the LOFI technique. We present the principle and the experimental setup of the acousto-optic laser optical feedback imaging technique, and we demonstrate the suppression of the parasitic feedback.

[Post-traumatic focal fixed dystonia of the shoulder: a distinctive syndrome with speculative mechanisms?]. / Dystonie focale fixée de l'épaule à distance d'un traumatisme scapulaire minime : une entité pour quels mécanismes ?

INTRODUCTION: Whether post-traumatic focal fixed dystonia has a physiological or psychologically-mediated mechanism is discussed. CASE REPORT: We report the case of an active 22-year-old soldier with shoulder-fixed dystonia, eight months after a fall with minor right-acromioclavicular sprain. CONCLUSION: Psychiatric examination and search of complex regional pain syndrome, radicular or accessory nerve damage, and genetic predisposition to dystonia are necessary for selecting a difficult treatment in these patients.

Cell imaging by coherent backscattering microscopy using frequency-shifted optical feedback in a microchip laser.

In this work, we present a new development of the laser optical feedback imaging technique for imaging biological structures with a high resolution. The first results obtained on human red blood cells and mice cerebral and muscular tissues slices are shown. The performances of the system and its future developments are also discussed.

Enzymatic functionalization of a nanobody using protein insertion technology.

Antibody-based products constitute one of the most attractive biological molecules for diagnostic, medical imagery and therapeutic purposes with very few side effects. Their development has become a major priority of biotech and pharmaceutical industries. Recently, a growing number of modified antibody-based products have emerged including fragments, multi-specific and conjugate antibodies. In this study, using protein engineering, we have functionalized the anti-hen egg-white lysozyme (HEWL) camelid VHH antibody fragment (cAb-Lys3), by insertion into a solvent-exposed loop of the Bacillus licheniformis ß-lactamase BlaP. We showed that the generated hybrid protein conserved its enzymatic activity while the displayed nanobody retains its ability to inhibit HEWL with a nanomolar affinity range. Then, we successfully implemented the functionalized cAb-Lys3 in enzyme-linked immunosorbent assay, potentiometric biosensor and drug screening assays. The hybrid protein was also expressed on the surface of phage particles and, in this context, was able to interact specifically with HEWL while the ß-lactamase activity was used to monitor phage interactions. Finally, using thrombin-cleavage sites surrounding the permissive insertion site in the ß-lactamase, we reported an expression system in which the nanobody can be easily separated from its carrier protein. Altogether, our study shows that insertion into the BlaP ß-lactamase constitutes a suitable technology to functionalize nanobodies and allows the creation of versatile tools that can be used in innovative biotechnological assays.

[Hashimoto's thyroiditis associated with recurrent transverse myelopathy]. / Myélite transverse à rechutes associée à une thyroïdite d'Hashimoto.

A 55-year-old woman presented first episode of paraplegia at D6 level with a marked improvement of neurological signs, but relapse occurred five months later. Hashimoto's thyroiditis with euthyroidism was found. Long-term 9 months treatment with oral corticosteroids was applied. Also she was able to walk with help. Two years after the second palsy she developed a new paraplegia at D6 level with a severe residual deficit five months later in spite of oral corticosteroids. Thyroid antibodies remained positive. Devic's disease without optica neuritis associated with thyroiditis or spinal cord localisation of Hashimoto's encephalopathy was discussed.

[Split-cord malformation (diastematolmyelia) presenting in two adults: case report and a review of the literature]. / Diastématomyélie révélée chez l'adulte: étude de deux cas et revue de la littérature.

INTRODUCTION: Split cord malformation (SCM) is an uncommon developmental anomaly characterized a cleft spinal cord. In type I, each of the hemicords is contained within an individual dural tube whereas in type II there is a common dural tube housing both hemicords. Commonly diagnosed in childhood, adult presentation is exceptional. METHODS: We report the case of two women whose type II SCM was discovered at the age of 40 and 54 years. RESULTS: The first patient complained of chronic lombar and radicular chronic pain with dysuria. Physical examination revealed a radicular syndrome with abolition of the left Achille reflex and a lombar hair tuft. MRI showed a disc herniation at the L5-S1 level, with a partial SCM at the level of the L2 vertebra, spina bifida and tethered cord. The second patient complained of lombar pain with perineal irradiation for 6 years. Physical examination showed a lombar cutaneous angioma. MRI revealed a thoraco-lombar SCM at the T12 to L1 level, with spina bifida. No spur could not be identified in either patient. No further surgical treatment was given. CONCLUSION: Based on these two observations, we propose a review of literature reporting 90 cases of adult SCM.

Coherent microscopy by laser optical feedback imaging (LOFI) technique.

The application of the non-conventional imaging technique LOFI (laser optical feedback imaging) to coherent microscopy is presented. This simple and efficient technique using frequency-shifted optical feedback needs the sample to be scanned in order to obtain an image. The effects on magnitude and phase signals such as vignetting and field curvature occasioned by the scanning with galvanometric mirrors are discussed. A simple monitoring method based on phase images is proposed to find the optimal position of the scanner. Finally, some experimental results illustrating this technique are presented.

Common peroneal nerve palsy following TNF-based isolated limb perfusion for irresectable extremity desmoid tumor.

Hyperthermic isolated limb perfusion (ILP) (2 mg, TNF-alpha and 100mg, melphalan) was performed for an irresectable right thigh desmoid tumor with calf extension in a 49-year-old man. The patient had a history of four resections since the age of 19 years. Local ILP toxicity appeared with extensive edema and common peroneal neurologic impairment including paresis that remained severe 10 months later. One of the most troublesome side effects of perfusion is peripheral nerve damage, which has been reported at a rate of between 1 and 48% of perfused patients. ILP is an effective treatment in recurrence situations or where resection threatens loss of function; it, however, requires administration in specialized centers, progress in standardization and close monitoring to avoid locoregional toxicity, the mechanisms of which merit further investigation. Emergency compartmental pressure measurement may indicate fasciotomy, can be of great interest.