Altered morphine-induced analgesia in neurotensin type 1 receptor null mice.

Both neurotensin (NT) and opioid agonists have been shown to induce antinociception in rodents after central administration. Besides, previous studies have revealed the existence of functional interactions between NT and opioid systems in the regulation of pain processing. We recently demonstrated that NTS1 receptors play a key role in the mediation of the analgesic effects of NT in long-lasting pain. In the present study, we therefore investigated whether NTS1 gene deletion affected the antinociceptive action of mu opioid drugs. To this end, pain behavioral responses to formalin were determined following systemic administration of morphine in both male and female NTS1 knockout mice. Acute injection of morphine (2 or 5 mg/kg) produced strong antinociceptive effects in both male and female wild-type littermates, with no significant sex differences. On the other hand, morphine analgesia was considerably reduced in NTS1-deficient mice of both sexes compared to their respective controls, indicating that the NTS1 receptor actively participates in mu opioid alleviating pain. By examining specifically the flinching, licking and biting nociceptive behaviors, we also showed that the functional crosstalk between NTS1 and mu opioid receptors influences the supraspinally-mediated behaviors. Interestingly, sexual dimorphic action of morphine-induced pain inhibition was found in NTS1 null mice in the formalin test, suggesting that the endogenous NT system interacts differently with the opioid network in male and female mice. Altogether, these results demonstrated that NTS1 receptor activation operates downstream to the opioidergic transmission and that NTS1-selective agonists combined with morphine may act synergistically to reduce persistent pain.

Involvement of NTS2 receptors in stress-induced analgesia.

Stress activates multiple neural systems that suppress pain sensation. This adaptive phenomenon referred as stress-induced analgesia (SIA) is mediated by the activation of endogenous pain inhibitory systems. Both opioid and non-opioid forms of SIA have been elicited in rodents according to stressor parameters and duration. There is accumulating evidence that the endogenous neurotensin (NT) system plays an important role in SIA. Especially, NT-deficient mice were shown to exhibit reduced SIA following water avoidance or restraint stress. Since central NT produces naloxone-insensitive analgesic effects by acting on spinal and supraspinal NTS2 receptors, we hypothesized that NT might mediate non-opioid SIA through NTS2 activation. Here, we evaluated the influence of an opioid-independent severe stress produced by a cold-water swim for 3 min at 15 degrees C on rodent offspring's pain perception. Our results demonstrated that mice lacking NTS2 exhibit significantly reduced SIA following cold-water swim stress. Indeed, NTS2 knockout mice submitted to both acute (plantar test) and tonic (formalin test) pain stimuli show a greater sensitivity to pain in comparison to wild-type littermates. Accordingly, pretreatment with the NT receptor antagonist SR142948A results in a hyperalgesic response to stress induced by cold-water swim. Endogenous NT regulates hypothalamic-pituitary-adrenal axis activity in stress condition by increasing corticosterone plasma levels. Accordingly, the plasma levels of corticosterone measured by radioimmunoassay are significantly reduced in non-stressed and stressed NTS2-deficient mice in comparison with wild-type mice. To further investigate the site of action of NT in mediating SIA, we microinjected NTS2 agonists in lumbar spinal cord and quantified post-stress sensitivity to pain in rats using the plantar test. Exogenously administered NTS2 analogs, JMV-431, beta-lactotensin and NT69L markedly enhance the magnitude and duration of stress antinociception in both 25- and 60-day-old rats. In sum, by using genetic and pharmacological approaches, we demonstrated here that NTS2 receptors mediate non-opioid SIA. Our results also revealed that the release of endogenous NT in response to stress requires the presence of NTS2 to stimulate corticotropin-releasing factor (CRF)-induced elevation of plasma corticosterone, and that NTS2 receptors localized at the lumbar spinal cord participate to the disinhibition of descending pain control pathways. Therefore, these data highlight the significance of NTS2 as a novel target for the treatment of pain and stress-related disorders.

Reference phase-shifter for measuring high power microwave impedance by using a phase modulation method.

A basic mechanical phase-shifter is described and proposed for use as a reference circuit for impedance measurements with a phase modulation method. It consists of a section of a curved rectangular waveguide, the length of which is mechanically varied with a stepper motor. The phase-shifter functions without gears. It can be used successfully in industrial set-ups with a pulsed or CW generator which are of low stability in frequency and in amplitude.

A flexible RF applicator for heating viscous lossy products such as foods.

A helical RF industrial applicator was evaluated for heating minced meat flowing in a hollow tube. Heating was homogeneous inside the product, although the product was highly lossy due to its high electric conductivity. The homogeneity was much better than could be obtained with microwave heating. A high power density, up to 5 kW/liter, can be deposited inside the product with 95% efficiency.

Derivation of an explicit formula for determining the effective permittivity of a three-component composite.

The author extends the Bergman-Milton formula of the effective permittivity of a two-component heterogeneous dielectric mixture to the case of a three-component mixture. He validates the introduction of a unique two-variable density function which describes the microgeometry. He also supplements the theoretical approach by discussing the significance and the forms of the percolation terms. The geometrical density functions, which correspond to the well-known Lichtnecker, C.R.I.M. and Looyenga formulae are explicitly given as cases for illustrating the general approach.

Look at European RF industrial applications.

The authors review the European RF industrial applications. European RF technology produced the 50omega-technology, which has been the basis for many successful applications in classical industrial domains such as food tempering and defrosting, rubber curing but also in new domains such as RF for curing of many car products. These new applications make clear the fundamental advantage of fast processing with RF technology.

Improving electric field distribution in a microwave heating device.

The authors describe a microwave reheater for food products in which two magnetrons and a magic tee are used for decoupling the waves emitted and for obtaining good impedance matching. Symmetric and asymmetric parts of the electric field pattern can be separately adjusted and optimized for best results.

Broadband and low insertion loss Stark cell for microwave spectroscopy.

A groove guide cell for Stark modulation spectroscopy has been constructed and tested. This structure with quasi-unique mode propagation between two isolated plates is well adapted to application of a modulation voltage. The insertion losses are low (0.6 dB for a 3-m-long cell, and R band) and the cell is free of internal reflection. A metallic casing enclosing the plates acts as a shield against electrical interference, prevents low-voltage breakdown, and reduces wall adsorption of the gas. The performance of the cell is not affected by temperature variation (-80 degrees to 25 degrees C). A high sensitivity has been obtained by converting the cell into a 3-m-long, high-Q cavity. This type of cell appears to particularly recommend itself for use in intensity measurements, broadband spectroscopy, analytical studies, and high frequency range work.