Using a D meson cloud model we calculate the squared charm radius of the nucleon. The ratio between this squared radius and the ordinary baryon squared radius is identified with the probability of ''seeing'' the intrinsic charm component of the nucleon. Our estimate is compatible with those used to successfully describe the charm production phenomenology. However, because of the lack of relevant experimental information, a large uncertainty in our result is unavoidable.

Ovarian carcinoma (OvC) remains a major therapeutic challenge due to its propensity to develop resistance after an initial response to chemotherapy. Interactions of tumour cells with the surrounding microenvironment play a role in tumour survival, invasion capacity and drug resistance. Cancer models that retain tissue architecture and tumour microenvironment components are therefore essential to understand drug response and resistance mechanisms. Herein, our goal was to develop a long-term OvC patient-derived explant (OvC-PDE) culture strategy in which architecture and cell type heterogeneity of the original tumour would be retained. Samples from 25 patients with distinct OvC types and one with a benign tumour, were cultured for 30 days in agitation-based culture systems with 100% success rate. OvC-PDE cultures retained the original tumour architecture and main cellular components: epithelial cells, fibroblasts and immune cells. Epithelial cells kept their original levels of proliferation and apoptosis. Moreover, the major extracellular components, such as collagen-I and -IV, were retained in explants. OvC-PDE cultures were exposed to standard-of-care chemotherapeutics agents for 2 weeks, attesting the ability of the platform for drug assays employing cyclic drug exposure regimens. We established an OvC-PDE dynamic culture in which tumour architecture and cell type heterogeneity were preserved for the different OvC types, replicating features of the original tumour and compatible with long-term drug exposure for drug efficacy and resistance studies.

Diterpenes have been identified as active compounds in several medicinal plants showing remarkable biological activities, and some isolated diterpenes are produced at commercial scale to be used as medicines, food additives, in the synthesis of fragrances, or in agriculture. There is great interest in developing methods to obtain derivatives of these compounds, and biotransformation processes are interesting tools for the structural modification of natural products with complex chemical structures. Biotransformation processes also have a crucial role in drug development and/or optimization. The understanding of the metabolic pathways for both phase I and II biotransformation of new drug candidates is mandatory for toxicity and efficacy evaluation and part of preclinical studies. This review presents an overview of biotransformation processes of diterpenes carried out by microorganisms, plant cell cultures, animal and human liver microsomes, and rats, chickens, and swine in vivo and highlights the main enzymatic reactions involved in these processes and the role of diterpenes that may be effectively exploited by other fields.

Clostridia comprise bacteria of environmental, biotechnological and medical interest and many commensals of the gut microbiota. Because of their strictly anaerobic lifestyle, oxygen is a major stress for Clostridia. However, recent data showed that these bacteria can cope with O 2 better than expected for obligate anaerobes through their ability to scavenge, detoxify and consume O 2 . Upon O 2 exposure, Clostridia redirect their central metabolism onto pathways less O 2 -sensitive and induce the expression of genes encoding enzymes involved in O 2 -reduction and in the repair of oxidized damaged molecules. While Faecalibacterium prausnitzii efficiently consumes O 2 through a specific extracellular electron shuttling system requiring riboflavin, enzymes such as rubrerythrins and flavodiiron proteins with NAD(P) H-dependent O 2 -and/or H 2 O 2 -reductase activities are usually encoded in other Clostridia. These two classes of enzymes play indeed a pivotal role in O 2 tolerance in Clostridioides difficile and Clostridium acetobutylicum. Two main signalling pathways triggering O 2 -induced responses have been described so far in Clostridia. PerR acts as a key regulator of the O 2 -and/or reactive oxygen species-defence machinery while in C. difficile, σ B , the sigma factor of the general stress response also plays a crucial role in O 2 tolerance by controlling the expression of genes involved in O 2 scavenging and repair systems.

We present the case of a 72-year-old woman observed for dermatitis on the legs followed by apperance of erythema on the eyelids. She had a past history of peripheral venous insufficiency and had been using self home-made Aloe vera juice over the legs for relief from pain. Patch tests showed positive reactions to the leaf of Aloe, the macerated Aloe jelly, and nickel sulfate. Although most manufacturers process Aloe products avoiding its irritant extracts, and probably as a consequence reports of allergic reactions are rare, one must remember that the growing popularity on the use of Aloe products may stimulate its use 'as is' by the patients. Furthermore, it is important to specifically ask patients about the use of these products, because they consider it as innocuous and thus would not spontaneously provide such information. Case reportA 72-year-old woman was observed for a 3-month history of pruriginous erythema of the legs, followed by intense itching, erythema, and desquamation of the eyelids (Figs 1 and 2). Shortly before, she had started applying self home-made Aloe vera leaf juice over the legs for the treatment of chronic peripheral venous insufficiency. There was no history of atopy or other relevant medical condition.

We present the case of a 30-year-old atopic lady with a known history of intolerance to several materials, including dark stockings, who developed a severe dermatitis on the eyelids and peri-orbital regions, as well as a conjunctivitis after having her eyelashes tinted by a beautician with a permanent black eyelash and eyebrow dye (Combinal, Dr Temt Laboratories, Austria). Patch tests revealed positive reactions to para-phenylenediamine (PPD), both diluted 0.01% and 1% in pet., to the eyelash dye (tested semiopen as is) and to some of the azo-dyes tested. The permanent eyelash dye did contain PPD, the use of which is illegal but seems to be a common practice. The patient had most probably been sensitized through nylon stockings containing azo-dyes, with PPD itself cross-reacting to them. With the growth in popularity of tattooing and permanent make-up, doctors should be aware of the new uses of this old allergen. Moreover, although many manufacturers have made great efforts to improve cosmetics concerning their safety, some of them remain uninformed about cosmetic legislation or do not respect it at all. Because many of these products are acquired via internet, lack of legislation about this shopping modality is also a serious problem.

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