Histological and chemical damage induced by microcystin-LR and microcystin-RR on land snail Helix aspersa tissues after acute exposure.

Microcystins (MCs) are the most common cyanotoxins with more than 200 variants. Among these cyanotoxins, microcystin-LR (MC-LR) and microcystin-RR (MC-RR) are the most studied congeners due to their high toxicity and frequent occurrence in surface waters. MC-LR has been detected in more than 75% of natural cyanobacteria bloom, along with other toxic and less toxic congeners. Accumulation of several microcystins variants (MC-LR and MC-RR) has been confirmed in aquatic snails exposed naturally or in the laboratory to toxic blooms. Thus, this paper aims to compare the biochemical and histological impact of both toxic variants (microcystin-LR and microcystin-RR) and their mixed form on a bioindicator, the land snail Helix aspersa. During experiments, snails were gavaged with a single acute dose (0.5 µg/g) of purified MC-LR, MC-RR, or mixed MC-LR + MC-RR (0.25 + 0.25 µg/g). After 96 h of exposure, effects on the hepatopancreas, kidney, intestine and lungs were assessed by histological observations and analysis of oxidative stress biomarkers. The results show that a small dose of MCs variants can increase the non-enzymatic antioxidant glutathione (GSH), inhibit glutathione-s-transferase (GST) level and trigger a defense system by activating glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD). Microcystin-RR causes serious anomalies in the hepatopancreas and kidney than Microcystin-LR. The organ most affected is the kidney. The damage caused by MC-LR + MC-RR is greater than that caused by single variants.

Room-temperature ferromagnetism in Ni(ii)-chromia based core-shell nanoparticles: experiment and first principles calculations.

We have synthesized bimagnetic core-shell nanoparticles containing a first-of-its-kind Ni(ii)-chromia nanophase shell and a well-defined, epitaxial core-shell interface. Magnetic measurements reveal a substantial coercivity of the nanoparticles and a significant exchange bias effect between the antiferromagnetic chromia core and the ferromagnetic Ni(ii)-chromia shell at low temperatures. The ferromagnetism and a weak exchange bias effect are found to persist to room temperature in the core-shell nanoparticles of ∼57 nm average size. Our first principles Density Functional Theory (DFT) calculations confirm that the novel corundum-structured Ni(ii)-chromia phase has an equilibrium cluster-localized ferromagnetic spin configuration. In addition, the DFT-based calculations show that the Ni(ii)-chromia phase is a Mott-Hubbard insulator, with a narrowed energy band gap and increased covalent bonding due to strong hybridization between Ni 3d and O 2p levels in the upper portion of the valence band and within the band gap region. The antiferromagnetic, ferromagnetic and magnetoelectric properties of our core-shell nanoparticles make these well suited for patterned recording media and biomedical applications.

Charge carrier relaxation in InGaAs-GaAs quantum wire modulation-doped heterostructures.

The time dependencies of the carrier relaxation in modulation-doped InGaAs-GaAs low-dimensional structures with quantum wires have been studied as functions of temperature and light excitation levels. The photoconductivity (PC) relaxation follows a stretched exponent with decay constant, which depends on the morphology of InGaAs epitaxial layers, presence of deep traps, and energy disorder due to inhomogeneous distribution of size and composition. A hopping model, where electron tunnels between bands of localized states, gives appropriate interpretation for temperature-independent PC decay across the temperature range 150-290 K. At low temperatures (T < 150 K), multiple trapping-retrapping via 1D states of InGaAs quantum wires (QWRs), sub-bands of two-dimensional electron gas of modulation-doped n-GaAs spacers, as well as defect states in the GaAs environment are the dominant relaxation mechanism. The PC and photoluminescence transients for samples with different morphologies of the InGaAs nanostructures are compared. The relaxation rates are found to be largely dependent on energy disorder due to inhomogeneous distribution of strain, nanostructure size and composition, and piezoelectric fields in and around nanostructures, which have a strong impact on efficiency of carrier exchange between bands of the InGaAs QWRs, GaAs spacers, or wetting layers; presence of local electric fields; and deep traps.

Effects of AlGaAs cladding layers on the luminescence of GaAs/GaAs1-xBix/GaAs heterostructures.

The structural and optical properties of GaAs1-xBix quantum wells (QWs) symmetrically clad by GaAs barriers with and without additional confining AlGaAs layers are studied. It is shown that a GaAs/GaAs1-xBix/GaAs QW with x ~ 4% and well width of ~ 4 nm grown by molecular beam epitaxy demonstrates efficient photoluminescence (PL) that becomes significantly more thermally stable when a cladding AlGaAs layer is added to the QW structure. The PL behavior for temperatures between 10 and 300 K and for excitation intensities varying by seven orders of magnitude can be well described in terms of the dynamics of excitons including carrier capture in the QW layer, thermal emission and diffusion into the cladding barriers. Understanding the role of these processes in the luminescence of dilute GaAs1-xBix QW structures facilitates the creation of highly efficient devices with reduced thermal sensitivity and low threshold current.

[A rare side effect of mesotherapy: Nicolau syndrome]. / Un effet indésirable rare de la mésothérapie : la dermite de Nicolau.

BACKGROUND: Nicolau's livedoid dermatitis is associated with drug-induced embolism in the cutaneous arterial bed, generally as a result of accidental intra-arterial injection. Herein, we report a case that is somewhat surprising because of its late onset following mesotherapy injections. CASE REPORT: A 53-year-old man, with a history solely of tendinopathy for which he underwent mesotherapy sessions, consulted for livedoid lesions of the front of the knee with central necrosis. History-taking revealed a final course of mesotherapy three weeks earlier for patellar tendinitis below the left kneecap; intradermal injection of procaine and piroxicam had been unusually and intensely painful. The remainder of the clinical examination revealed additional livedoid lesions on the outside of the left ankle as well as purpuric lesions on the pads of the toes on the left foot. Laboratory tests revealed nothing of note. Skin biopsies of the livedoid circumference of the lesion showed arteriolar emboli of an amorphous material within the dermis obliterating the arteriolar lumen. The clinical appearance of skin lesions after mesotherapy led us to a diagnosis of Nicolau livedoid dermatitis. DISCUSSION: Nicolau dermatitis is a rare skin complication described as occurring mainly as a result of intramuscular injections. The reported case is special because it comprises Nicolau dermatitis arising out of a session of mesotherapy employing an intradermal injection. However, there are only very few cases in which subcutaneous injections have induced Nicolau dermatitis. The pathophysiology is not well known, but several mechanisms are involved: arterial ischaemia by vasospasm or thrombosis. In this case, the semiotic appearance of the lesions and histological analysis militate in favour of accidental injection of a skin product into an arteriole, resulting in obliteration of the latter. Mesotherapy can induce Nicolau dermatitis.

Aharonov-Bohm interference in neutral excitons: effects of built-in electric fields.

We report a comprehensive discussion of quantum interference effects due to the finite structure of neutral excitons in quantum rings and their first experimental corroboration observed in the optical recombinations. The signatures of built-in electric fields and temperature on quantum interference are demonstrated by theoretical models that describe the modulation of the interference pattern and confirmed by complementary experimental procedures.

Common bile duct stenosis with hypereosinophilia and pancreatitis in childhood: report of 2 cases.

Common bile duct stenosis associated with pancreatitis and hypereosinophilia is described in two children. Ultrasonography and CT showed slight increase in the size of the pancreas and bile duct dilatation. Percutaneous cholangiography (PTC) demonstrated extrinsic stenosis of the bile duct at the level of the pancreas. Spontaneous resolution of the clinical and radiological findings was observed. Knowledge of this rare pathological association with favourable evolution can avoid an unnecessary surgical procedure.

[Pneumocystis carinii pneumopathy in patients with AIDS. The first 3 cases reported in Algeria and review of the literature]. / Pneumopathie à pneumocystis carinii chez les malades atteints de sida. Les 03 premiers cas algériens et revue de la littérature.

Pneumocystis carinii pneumonia (PCP) is a severe and dangerous infection which afflicts patients with immune deficiency, particularly those with AIDS. This pathology isn't well known in Algeria. The aim of the present study is a contribution to make this disease more known in the algerian AIDS patients. It has focused on the research and the identification of P. carinii in the expectorations and in the bronchalveolar lavage (BAL) fluids of 14 patients with respiratory troubles: 13 were AIDS cases and one with an iatrogenic immune deficiency. 3 of these patients were women and the rest were men. Their average age was 35.

[First Algerian case of human otomyiasis from Chrysomya bezziana]. / Premier cas algérien d'otomyiase humaine à Chrysomya bezziana.

In Algeria, Human myiasis, essentially ophtalmomyiasis, are known for a long time. Most of cases are due to Oestrus ovis. In this papers the authors report, in a shepherd, the first case of otomyiasis due to Chrysomya bezziana larvae, a species still unknown in North Africa. This observation which indicates the presence of the species in a Northern part of Algeria is also the first report of the insect outside of its endemic traditional area.