Novel molecular variants of the Na-Cl cotransporter gene are responsible for Gitelman syndrome

A hereditary defect of the distal tubule accounts for the clinical features of Gitelman syndrome (GS), an autosomal recessive disease characterized by hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria. Recently, we cloned the cDNA coding for the human Na-Cl thiazide-sensitive cotransporter (TSC; also known as ?NCCT? or ?SLC12A3?) as a possible candidate for GS, and Simon et al., independently, described mutations in patients with GS. Now, we show 12 additional mutations consistent with a loss of function of the Na-Cl cotransporter in GS. Two missense replacements, R209W and P349L, are common to both studies and could represent ancient mutations. The other mutations include three deletions, two insertions, and six missense mutations. When all mutations from both studies are considered, missense mutations seem to be more frequently localized within the intracellular domains of the molecule, rather than in transmembrane or extracellular domains. One family, previously reported as a GS form with dominant inheritance, has proved to be recessive, with the affected child being a compound heterozygote. A highly informative intragenic tetranucleotide marker, useful for molecular diagnostic studies, has been identified at the acceptor splice site of exon 9.     

Changes in doxorubicin distribution and toxicity in mice pretreated with the cyclosporin analogue SDZ PSC 833

SDZ PSC 833 (PSC 833) is a cyclosporin A analogue that is under clinical investigation in combination with doxorubicin (Dx) or other anticancer agents as a type-1 multidrug resistance (MDR-1)-reversing agent. The present study was focused on the effects of PSC 833 on the distribution and toxicity of Dx in non-tumor-bearing CDF1 male mice. Mice were given PSC 833 i.p. at 30 min before i.v. Dx treatment. Dx levels were determined by a high-performance liquid chromatography (HPLC) assay at different times during a 72-h period following Dx treatment in the serum, heart, intestine, liver, kidney, and adrenals of mice. In all tissues, Dx area under the concentration-time curve (AUC) values were much greater in mice receiving 10 mg/kg Dx in combination with 12.5 or 25 mg/kg PSC 833 than in mice receiving Dx alone. The highest increase in Dx concentrations was found in the intestine, liver, kidney, and adrenals. Lower, albeit significant, differences were found in the heart. PSC 833 did not appear to influence either urinary or fecal Dx elimination or Dx metabolism to a great extent. Doses of PSC 833 devoid of any toxicity potentiated the acute and delayed toxicity of Dx dramatically. The mechanism responsible for this enhanced toxicity has not yet been elucidated but is likely to be related to an increased tissue retention of Dx due to inhibition of the P-glycoprotein (Pgp) pump by PSC 833, as has recently been proposed for cyclosporin A.     

Characterisation of microwave phase conjugate signal generation using nonlinearly loaded wire frequency selective surface (FSS)

Both experimental and theoretical information regarding the scattering and phase conjugate mixing properties of a 2D double-periodic array of wires loaded with nonlinear/linear lumped elements have been provided. An experimental means for assessing the phase conjugate energy production capability for the array is given. These investigations enable identification of the fundamental operational characteristics and underlying mechanisms associated with the production of phase conjugate energy by this type of artificial electromagnetic media. Means for enhancing the phase conjugate energy production capability of the structure by using additional linear lumped loads is examined theoretically and limits on the production of phase conjugate energy established. Theoretical far-field prediction of the behaviour of the structure indicates that retro-directive reflector action as well as negative refraction should be possible.     

Polarisation insensitive planar dielectric slab waveguide extended hemi-elliptical lens

The authors present the performance of a patch fed planar dielectric slab waveguide extended hemi- elliptical lens antenna. The lens is constructed using polystyrene and weighs only 90 g. The maximum lens dimensions are 11 lambda times 13 lambda in the lens plane and it is 0.6 lambda thick. From 18 to 30 GHz the lens can handle both TM₀ and TE₀ signals simultaneously and at 22 GHz it can be made to generate a 1.5 dB axial ratio circularly polarised signal when fed by a linearly polarised patch antenna orientated to 38deg with respect to the horizontal. The measured gain and half-power beamwidth for TM₀ and TE₀ excitation at 28.5 GHz are 18.5 dB (aperture efficiency of 85%), 4.1deg and 18.7 dB, 4.4deg, respectively, both with a -10 dB return loss bandwidth of about 10%.     

Investigation of the mechanisms governing doxorubicin and irinotecan release from drug-eluting beads: mathematical modeling and experimental verification

Drug-eluting beads (DEBs) are embolising devices in clinical use for the treatment of liver cancer by transarterial chemoembolisation. In this study, release kinetics of doxorubicin (DOX) and irinotecan (IRI) were investigated by experimental evaluations and mathematical modeling, based on Langmuir isotherm and two phenomenological models (Boyd/Bhaskar) developed to determine the actual mechanisms controlling drug release rate. The model was validated through release studies, in particular by assessing how drug loading, ionic strength of the release medium and device swelling during release influence drug release kinetics. Results demonstrated that IRI is released much faster than DOX, and that DEB volume strongly depends upon drug loading and fractional release. This effect was properly taken into account in developing the mathematical model. Experimental results were well fit by numerical simulations, and two different rate-controlling mechanisms were found to govern DOX and IRI delivery.     

Analytical expression of long-exposure adaptive-optics-corrected coronagraphic image. First application to exoplanet detection

In this paper we derive an analytical model of a long-exposure star image for an adaptive-optics(AO)-corrected coronagraphic imaging system. This expression accounts for static aberrations upstream and downstream of the coronagraphic mask as well as turbulence residuals. It is based on the perfect coronagraph model. The analytical model is validated by means of simulations using the design and parameters of the SPHERE instrument. The analytical model is also compared to a simulated four-quadrant phase-mask coronagraph. Then, its sensitivity to a miscalibration of structure function and upstream static aberrations is studied, and the impact on exoplanet detectability is quantified. Last, a first inversion method is presented for a simulation case using a single monochromatic image with no reference. The obtained result shows a planet detectability increase by two orders of magnitude with respect to the raw image. This analytical model presents numerous potential applications in coronographic imaging, such as exoplanet direct detection, and circumstellar disk observation.     

Role of p53 gene in colorectal neoplasms

A prospective study on the role of the p53 gene in sporadic colorectal neoplasms is presented and the level of mutant p53 protein was measured in the tissue removed during colonoscopy from: patients previously operated for colorectal malignant neoplasms, patients with active neoplasms, first degree relatives and during regular checks. 72% of patients with an active tumour showed a positive p53 and 38% in follow-up checks. Longer follow-up periods and a major number of patients are necessary to assess the prognostic importance of the p53 protein.     

Alteration of central excitation circuits in chronic headache and analgesic misuse

Central excitatory circuits could be involved in the pathophysiology of pain; particularly, the genesis of chronic pain. The "second pain" is the sensation that follows the initial pain after an appropriate nociceptive stimulus. The second pain is amplified by repeating the stimulus after brief intervals (temporal summation). This phenomenon is the psychophysical correlate of the excitatory pain circuits. The temporal summation of the second pain was evaluated in four groups of subjects; one group affected by migraine without aura, one by episodic tension headache, one by chronic daily headache, and a group of healthy subjects. A percutaneous electrical shock was used as the nociceptive stimulus. The intensity of the second pain was significantly greater in the group of patients with chronic headache in comparison with the other groups. The patients with chronic headache were subdivided into three groups on the basis of their clinical history: a group with transformed migraine; a group with chronic headache ab initio, a form related to the first one; (both groups suffered from chronic daily headache with a frequent superimposition of episodes of migraine attacks) and the third group consisted of patients with chronic tension headache. The temporal summation of the second pain was altered in the first two groups. The patients with chronic migraine abused ergotamine given as a symptomatic drug. Those who were able to discontinue this drug were retested and reported a decrease of the second pain in comparison to the previous measurements. The results of the present study indicate that central excitatory circuits could be involved in the mechanism leading to the development of chronic daily headache.