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This study involved the corneal effects of the laser beam in infrared at 1573 nm. Investigations were directed toward verifying the limit values by defining the thresholds of corneal damage in experiments carried out on the rabbit, and using biochemical techniques, to specify a damage threshold at the cellular level and a better understanding of the cellular steps of the damaging process. Corneal damage thresholds were determined for exposures to 3 ns single pulses using clinical observations and histology. The ED50 obtained with a corneal beam diameter of 400 μm was 26.6 J cm−2. The corresponding radiant exposure, calculated with the 1 mm aperture diameter recommended by standards, was 4.3 J cm−2. This value was still higher than the present 1 J cm−2 exposure limit. In vitro experiments were also carried out on primary keratocytes and HT1080 epithelial cell line. An expanded beam diameter of 3.5 mm was delivered on plates for study of cell proliferation, senescence, and cytotoxicity. The laser beam was e...

Resume L'article presente un ergometre innovant et original permettant de caracteriser les proprietes mecaniques des muscles squelettiques croisant une articulation en termes de proprietes contractiles et elastiques. La presentation des differents tests avec ses methodes de quantification se focalisera sur les proprietes elastiques. Des etudes dans differents domaines d'application montreront la validite des mesures ainsi que l'interet de telles mesures pour la recherche clinique, la reeducation fonctionnelle ou l'application dans le domaine sportif.

The possible peripheral and/or central origin in the mechanisms responsible for day-time fluctuation in maximal torque of the triceps surae muscle were investigated with a special emphasis on antagonist muscle coactivation. Eleven healthy male subjects (physical education students) took part in this investigation. The electromechanical properties of the plantar flexor muscles were recorded at two different times of day: between 06:00 h and 08:00 h in the morning and between 17:00 h and 19:00 h in the evening. To investigate peripheral mechanisms, the posterior tibial nerve was stimulated at rest, using percutaneous electrical stimuli, to evoke single twitch, double twitch, and maximal tetanic contraction (100 Hz). Maximal voluntary contraction of the plantar flexors was also assessed by means of the relative electromyographic activity of respective agonist and antagonist muscles (soleus, gastrocnemius medialis, gastrocnemius lateralis, and tibialis anterior). A double twitch was delivered during maximal voluntary plantar flexion to record muscle activation (i.e., interpolated twitch technique). The coactivation level of the tibialis anterior muscle during plantar flexion was calculated. The results indicated a significant decrease in maximal voluntary muscle torque of triceps surae in the evening as compared with the morning (-7.0 %; p < 0.05). Concerning the central command, when extrapolated by the twitch interpolation technique, the decrease in mean activation level of -6.8 % was consistent with the fluctuation in torque (-7.0 %). Soleus muscle electromyographic activity (normalized to the M-wave) showed a significant decline (21.6 %; p < 0.001). Moreover, individual changes in MVC percentage were significantly related to those of normalized electromyographic activity of the soleus muscle (r = 0.688; p < 0.01). Thus, it indicated that the subject's capacity to activate the soleus muscle was affected by the time of day. The coactivation level in the tibialis anterior muscle during plantar flexion did not change significantly in the evening. Concerning peripheral mechanisms, we observed a decrease in maximal M-wave amplitude for soleus and gastrocnemii, associated with unchanged single twitch and tetanus torque. To conclude, impairment in soleus muscle central command seemed to be the mechanism in the origin of torque failure. Such information would be of importance in the investigation of day-time fluctuations in complex motor task performances implicating the triceps surae muscle.

Laser radiation: ocular risks and safety standards. The risk for biological tissues to be damaged by a laser beam is mainly determined by their optical properties. Laser radiations emitted in ultraviolet and infrared B and C represent a hazard for the anterior segment of the eye. Depending the wavelength, laser radiation is absorbed by the cornea, the lens or both. The lower damage thresholds are reported at the retinal level, in the spectral range of 400 to 1 400 nm. The exposure limit values, recommended by laser safety standards, are evaluated with wavelength, exposure duration, pulse repetition frequency and the size of the visual angle subtending the source. The fast evolution of laser products induces a continuous revision of guidelines. Next revision of European standard EN 60825-1/A2 will include subnanosecond limit values, changes in the continuous wave exposure limits and a new classification of laser products susceptible to be in agreement with next ANSI and FDA/CDRH laser safety standards.

Dans le cadre de ce projet, nous avons concu et realise un ergometre multimodalites dedie a l'analyse des proprietes mecaniques du systeme musculoarticulaire « cheville » de l'enfant preadolescent. Les deux modules ergometriques principaux, le module « table » et le module « tete motrice » sont presentes, ainsi que les differentes fonctionnalites du dispositif ergometrique: mode isometrique, mode isocinetique, mode quick-release et mode en perturbations sinusoidales. Les differents tests ainsi realisables permettent une approche complete des proprietes elastiques du systeme musculotendineux et musculoarticulaire. Les tests preliminaires realises chez 8 enfants a des fins de validation des fonctionnalites de l'ergometre ont confirme, logiquement, les plus faibles capacites de l'enfant en termes de couples isometriques maximaux. Ils amenent aussi a proposer, de facon originale, une plus faible raideur des elements elastiques musculotendineux et musculoarticulaires. Ce resultat reste a confirmer sur une plus large population. L'implantation, apres validation, de l'ergometre en site hospitalier met a la disposition du clinicien et du reeducateur un outil original pour approcher le deficit moteur et assurer le suivi de programme de reeducation fonctionnelle par la quantification de proprietes mecaniques, notamment des proprietes elastiques.

Most laser safety documents advise the laser user that caution must be used in the evaluation of exposure to repetitively pulsed radiation since they are only limited data on multiple pulse exposure criteria. The empirical multiple pulse formula is based on some data indicating that there is generally a cumulative effect in multiple-pulse exposures. This effect is a reduction in the threshold energy per pulse relative to the single pulse threshold. The best fit to experimental data predicts that the threshold energy per pulse decreases in proportion to the fourth root of the number of pulses n. This model has been reported to be in agreement for exposures ranging from picoseconds to seconds. However, the very limited data reported in the sub-nanosecond domain of time were obtained with a low pulse ratio frequency. No data exists in the litterature concerning the effect on the retina of ultrashort pulses delivered with a very high repetition rate. Also, it has been hypothesized that one cannot extrapolate from longer pulses width because the ultrashort pulse (single or multiple) induce effects which may involve fundamentally different mechanisms of damage. Thus, some laser safety guidelines do not specifically provide exposure limits for a single-pulse duration less than 1 ns because of a lack of biological data1. If exposure limits are given, the limit values for these exposure times has been derived by maintening the irradiances applicable to nanosecond pulses2. With the goal in mind to obtain adequate data base for single and multiple ultrashort pulses, an experimental study has been directed toward determining the retinal damage thresholds induced by picosecond pulses emited in the visible spectrum.Most laser safety documents advise the laser user that caution must be used in the evaluation of exposure to repetitively pulsed radiation since they are only limited data on multiple pulse exposure criteria. The empirical multiple pulse formula is based on some data indicating that there is generally a cumulative effect in multiple-pulse exposures. This effect is a reduction in the threshold energy per pulse relative to the single pulse threshold. The best fit to experimental data predicts that the threshold energy per pulse decreases in proportion to the fourth root of the number of pulses n. This model has been reported to be in agreement for exposures ranging from picoseconds to seconds. However, the very limited data reported in the sub-nanosecond domain of time were obtained with a low pulse ratio frequency. No data exists in the litterature concerning the effect on the retina of ultrashort pulses delivered with a very high repetition rate. Also, it has been hypothesized that one cannot extrapolate ...

A mechanical device for studying changes in mechanical properties of human muscle as a result of spaceflight is presented. Its main capacities are to allow during a given experiment investigation of both contractile and visco-elastic properties of a musculo-articular complex using respectively isometric contractions, isokinetic movements, quick-release tests and sinusoidal perturbations. This device is a motor driven ergometer associated to an experimental protocol designed for pre- and post-flight experiments. As microgravity preferentially affects postural muscles, the apparatus was designed to test muscle groups crossing the ankle joint. Three subjects were tested during the Euromir '94 mission. Preliminary results obtained on the european astronaut are briefly reported. During the next two years the experiments will be performed during six missions.

Review on t(10;14)(q24;q11) - t(7;10)(q34;q24), with data on clinics, and the genes involved.

Review on Soft tissue tumors: Desmoplastic small round cell tumor, with data on clinics, and the genes involved.

Corneal damage thresholds were determined for exposures to 3 ns single pulse emitted at 1.57μm, using clinical observations and histology. The DE50 obtained with comeal beam diameter of 400μm was 26.6 J.cm−2. The corresponding radiant exposure calculated with the 1mm aperture diameter recommended by ICNIRP guidelines or standards, was 4.3 J.cm−2. This value was still upper than the present 1 J.cm−2 exposure limit. In vitro experiments have been also carried out on primary keratocytes and epithelial cell line. The infrared 1.57μm laser radiation can induce morphological nucleic abnormalities. The frequency of apoptotic bodies seemed the most suitable criteria capable to reveal the cellular stress induced by laser irradiation.Corneal damage thresholds were determined for exposures to 3 ns single pulse emitted at 1.57μm, using clinical observations and histology. The DE50 obtained with comeal beam diameter of 400μm was 26.6 J.cm−2. The corresponding radiant exposure calculated with the 1mm aperture diameter recommended by ICNIRP guidelines or standards, was 4.3 J.cm−2. This value was still upper than the present 1 J.cm−2 exposure limit. In vitro experiments have been also carried out on primary keratocytes and epithelial cell line. The infrared 1.57μm laser radiation can induce morphological nucleic abnormalities. The frequency of apoptotic bodies seemed the most suitable criteria capable to reveal the cellular stress induced by laser irradiation.

Variations in force and electromyographic (EMG) activities of skeletal muscles with the time-of-day have been previously described, but not for a postural muscle, submitted to daily postural and locomotor tasks. In this article, mechanical performances, EMGs, and the ratio between these parameters, i.e., the neuromuscular efficiency (NME), were measured on the triceps surae (TS) of eight subjects, two times each day, at 6:00 and 18:00 h. NME was evaluated under different experimental conditions (electrically induced contractions, reflex contractions, maximal and submaximal voluntary isometric contractions, and during a natural movement, a drop jump) to determine whether mechanisms, peripheral or central in origin, were responsible for the eventual changes in NME with time-of-day. To calculate NME in induced conditions (NMEind), a supramaximal electrical stimulus was applied to the tibial nerve, and the maximal M wave of TS (TS Mmax) and the amplitude of the twitch tension (PtMmax) in response to this electrical stimulation were quantified. TS Mmax was significantly lower in the evening (mean gain value -10.7 +/- 5.5%, p < 0.05), whereas PtMmax was not significantly modified. NMEind (PtMmax/TS Mmax) was significantly higher in the evening (mean gain of 17.6 +/- 5.8%, p < 0.05), and this increase was necessarily peripheral in origin. Secondly, maximal tendon taps were applied to the Achilles tendon in order to quantify at the two times-of-day the reflexes in response to a mechanical stimulus. The maximal reflex, TS Tmax/Mmax (%), the peak amplitude of the twitch tension associated to this tendon jerk (PtTmax), and the corresponding NME (NMEreflex = PtTmax/TS Tmax/Mmax) were not affected by time-of-day, indicating that reflex excitability did not present daytime variations when tested under these conditions. Voluntary isometric contractions were required under maximal (MVC) and submaximal (25% MVC) conditions, and the corresponding torques and TS EMG were measured. MVC was higher in the evening (mean gain: 8.6 +/- 2.7%, p < 0.05) and TS EMGmax (normalized with regard to TS Mmax) also increased in the evening but not significantly; thus, NMEMvc was not modified. At 25% of MVC, TS EMG was significantly higher in the evening (mean gain of 23 +/- 13.9%, p

Very little is known concerning the specific cellular and molecular responses of the human cornea to excimer surgery and how these responses influence the safety, efficacy and predictability of these treatments (PRK, LASIK). Moreover, following LASIK, depth of injury may lead to more severe lesions in the corneal stroma. The cellular effects of subablative doses of 193 nm laser radiation have been examined in cultured epithelial cell lines (HT1080, RKO, H1299) and keratocytes. Excimer laser radiation cause cellular death in whole epithelial cell lines and keratocytes. Our results clearly show in several cell types that the incidence of apoptosis increases 24 hours after irradiation, as demonstrated by morphologic nuclear analyses (nuclear condensation, budding…,). Furthermore, the use of TUNEL method confirms that irradiated cells undergo apoptosis. This increase in apoptotic cell number is accompanied by a decrease in the number of proliferating cells as detected by the incorporation of BrdU. An increase of S and G2/M cell cycle phases, assessed by flow cytometric analysis of cellular DNA content, is induced after laser irradiation relative to control cells. Induction of chromosome breaks by 193 nm exposure is pointed out by micronuclei observation after DAPI DNA staining and karyotype analyses. The comprehension of these mechanisms could allow to better apprehend in the long-term side effects of processing using the laser technology.Very little is known concerning the specific cellular and molecular responses of the human cornea to excimer surgery and how these responses influence the safety, efficacy and predictability of these treatments (PRK, LASIK). Moreover, following LASIK, depth of injury may lead to more severe lesions in the corneal stroma. The cellular effects of subablative doses of 193 nm laser radiation have been examined in cultured epithelial cell lines (HT1080, RKO, H1299) and keratocytes. Excimer laser radiation cause cellular death in whole epithelial cell lines and keratocytes. Our results clearly show in several cell types that the incidence of apoptosis increases 24 hours after irradiation, as demonstrated by morphologic nuclear analyses (nuclear condensation, budding…,). Furthermore, the use of TUNEL method confirms that irradiated cells undergo apoptosis. This increase in apoptotic cell number is accompanied by a decrease in the number of proliferating cells as detected by the incorporation of BrdU. An increase...

The current laser safety standards do not define the exposure limit values for pulsewidth less than one nanosecond. It has been hypothesized that one cannot extrapolate from longer pulse widths because the ultrashort pulse contains high peak power and may induce non linear effects. These effects may involve fundamentally different mechanisms of damage particularly for repetitively ultrashort pulses1. Most laser safety documents advise the laser user that caution must be used in the evaluation of exposure to repetitively pulsed radiation since they are only limited data on multiple pulse exposure criteria. The empirical multiple pulse formula is based on some data indicating that there is generally a cumulative effect in multiple-pulse exposures. No data exists in the litterature concerning the histological effects on the retina of ultrashort pulses delivered with a high repetition rate.The current laser safety standards do not define the exposure limit values for pulsewidth less than one nanosecond. It has been hypothesized that one cannot extrapolate from longer pulse widths because the ultrashort pulse contains high peak power and may induce non linear effects. These effects may involve fundamentally different mechanisms of damage particularly for repetitively ultrashort pulses1. Most laser safety documents advise the laser user that caution must be used in the evaluation of exposure to repetitively pulsed radiation since they are only limited data on multiple pulse exposure criteria. The empirical multiple pulse formula is based on some data indicating that there is generally a cumulative effect in multiple-pulse exposures. No data exists in the litterature concerning the histological effects on the retina of ultrashort pulses delivered with a high repetition rate.

A complex translocation involving chromosome 6, 8 and 9 [t(6;9;8)(p23;q34;q22)] associated with other structural and numerical abnormalities was observed on bone marrow karyotype of a woman suffering with acute myeloblastic leukemia (AML2). Fluorescence in situ hybridization agreed with the conventional cytogenetic interpretation by showing that a part of chromosome 6 short arm was inserted on the rearranged chromosome 9 resulting in the t (6;9) usually encountered in AML.

Objectifs L’existence d’une hyperdiploidie est retrouvee dans 25 %-30 % des LAL de la lignee B de l’enfant, et peut etre associee a des rearrangements geniques de la voie Ras. L’objectif de cette etude retrospective est de decrire ces anomalies et leur role pronostic eventuel dans ce groupe phenotypique. Patients et Methodes 113 pts pris en charge pour une LAL avec hyperploidie a l’hopital Trousseau entre 2000 et 2008 ont ete repertories. Une analyse de mutation concernant les genes FLT3, NRAS et PTPN11 a ete realisee associee a l’etude de l’expression du gene FLT3 par RQ-PCR. Resultats Des mutations des genes FLT3, NRAS et PTPN11 ont ete retrouvees chez 24,3 % (n = 25) des patients. Il n’a pas ete mis en evidence d’association entre ces mutations et âge, sexe, hyperleucocytose, corticosensibilite, MRD et EFS. Nous avons retrouve une surexpression de FLT3 dans ce groupe comparees aux autres groupes cytogenetiques ( p p = 0,04). Conclusion Notre etude confirme la relative frequence des mutations de FLT3, NRAS et PTPN11 dans les LAL hyperdiploides et le role de la voie RAS dans les evenements genomiques successifs associes a la leucemogenese des LAL de l’enfant.

The disynaptic Ia-alpha inhibition between the tibialis anterior and the soleus muscles is now well known. This neuronal organization has been established thanks to the analysis of the Hoffmann reflex (H reflex) changes following an electrical stimulation of the antagonist muscle nerve. In some cases, anatomical constraints impede the use of this classical technique for assessing a reciprocal Ia inhibition between muscles. Furthermore, an electrical stimulus solicits the primary spindle afferents in conditions which are very different from their natural stimulus: the muscle stretch. Thus we have undertaken to analyse the changes of a soleus H reflex following a rapid stretch of the ankle dorsiflexors and therefore of their prime-mover: the tibialis anterior. The mechanical perturbations were imposed with a strong initial acceleration and a limited angular displacement thanks to an original device including electromagnet and spring. This technique, derivated from the quick release technique, was applied on relaxed muscles to avoid a co-contraction phenomenon. 45 to 50 ms after the initiation of the mechanical perturbation an early reflex response was observed on the stretched tibialis anterior. The area of this first reflex response was related to the initial acceleration of the passive dorsiflexion. Several arguments are presented in favour of the myotatic origin of this reflex component. The passive dorsiflexion used as a conditioning stimulus led to a strong and longlasting inhibition of the test soleus H reflex. The early inhibition of the soleus H reflex was observed only about 18 ms after the conditioning stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

With reference to the concept that contraction of a muscle can be inhibited by contraction of its antagonists, the excitability of a bifunctional muscle, the soleus (plantarflexor and adductor) was studied during voluntary isometric contractions of the abductors in man. For this purpose, the soleus monosynaptic stretch reflex (MSR) was solicited by means of quick-release dorsiflexion movements which also induce inactivation of the tibialis anterior (unloading reflex). When different initial torques of dorsiflexion were developed (reference conditions) the amplitude of the soleus MSR was found to be related linearly to the maximal value of angular acceleration. When an abduction torque was superimposed (combined efforts), the soleus response was always depressed, but no significant reinforcement of this inhibition was observed when the abduction torque increased. From present results, and from classical data concerning reciprocal inhibition between soleus and tibialis anterior, it is concluded that the MSR of a bifunctional muscle is depressed when the antagonists of either one of its functions are voluntarily activated.

Congenital deficit of the inhibitor of C1 esterase (C1 INH) usually presents by oedema of the lower limbs, abdomen and glottis (sometimes lethal), which explains its clinical denomination of angioneurotic oedema. The association of this condition with disseminated lupus erythematosis has been reported in 4 cases and with discoid lupus in 4 cases. Antinuclear factors were found in all these cases but there were only two documented cases of nephropathy (one diffuse proliferative glomerulonephritis and one local glomerulonephritis). The association of a deficit of C1 INH and membrano-proliferative glomerulonephritis has only been reported in 2 cases (one lobular glomerulonephritis and one glomerulonephritis with dense basal membrane deposits). Our case had C1 INH deficiency and proliferative lupic glomerulonephritis in the absence of other clinical and immunological signs of DLE. Nephropathy was not looked for in 9 cases of association of C1 INH deficiency and C3-shearing autoantibody (C3 NEF). A common genetic mechanism for these associations seems very improbable. The aptitude of patients with C1 INH deficiency to synthesise autoantibodies under the influence of infections factors, for example, could explain the higher incidence of lupus and glomerulopathies in these patients.

The activation of antagonistic muscles is studied during isometric combined contractions of bifunctional muscles. It is established that the co-contraction mechanism observed in such situations limits unwanted movements. Furthermore, when a co-contraction appears between two biantagonistic muscles, the phenomenon underlies a conflicting situation and, consequently, the muscular patterns encountered are in most cases the reverse of those classically described. In these circumstances the inhibition usually present between antagonistic muscles could be masked, due to convergence on the motoneurones of both inhibitory and excitatory discharges coming from homonymous and antagonistic muscles of a given bifunctional muscle.

The electrical activity of the biceps brachii and pronator teres muscles is studied through the prono-supination of the forearm in some anisometrical conditions (dynamic work) when the inertia of the mobile system and the elbow position are being varied. The subjects are required to perform pronation, supination and flexion movements, either isolated or combined. From the findings obtained when the integrated electrical activity (Q) is related to the mechanical work (W), one can conclude that a. the Q-W linear relationship seems to characterize the chief function of a muscle, b. the slope of the Q-W relationship depends on the elbow position, c. the pronator muscles do not inhibit in a selective manner the biceps supinating function. So a bifunctional muscle seems to act as a whole.

The electrical activity of the biceps brachii and pronator teres muscles is studied through the prono-supination of the forearm in some isometrical conditions (static work) with different loads and joint positions. If the pronator teres is always being active in pronation, this activity is a function of the load and of the wrist and elbow positions. The same phenomena can be observed for the biceps brachii but when in supination. From the curvilinear relationships between the integrated electrical activity and the load--observed on both muscles--some torque-angle relationships can be established for the biceps brachii which show that a bifunctional muscle seems to be characterized by a very and unique force-length relationship.