Caffeine and the kidney: what evidence right now?

Caffeine, or 1, 3, 7-trimethylxanthine, is one of the most frequently consumed active drugs worldwide. Its main mechanisms of action include inhibiting the phosphodiesteratic enzyme and adenosine receptors and activating the ryanodine receptors with several actions on all organs. What effect does caffeine have on the kidney? Is caffeine beneficial or dangerous? A review of the current literature reveals conflicting opinions regarding the prolithiasic effect of this substance, whereas its diuretic action is least disputed and more easily observed. Caffeine may have a toxic or preventive effect in some physiologic or pathologic conditions. Some of these incongruences may depend on several factors, such as dosage, prior chronic exposure, genetic-enzymatic axes, and concomitant drug consumption. While awaiting further insight from forthcoming studies on the issue, we may reach a preliminary conclusion that, as yet, there is no evidence contraindicating the consumption of the equivalent of 3 to 4 cups of coffee per day in healthy or nephropathic subjects. However, particular attention should be paid to the elderly, children, and patients on concomitant treatment with analgesics or diuretics, whereas in subjects with a family or clinical history of calcium lithiasis a moderate caffeine consumption should be associated with an adequate fluid intake. Further in-depth studies are required to investigate whether this beverage is beneficial to patients on hemodialysis.     

29 Year‐Old Man with New Onset Seizures

Imaging of a 29‐year‐old man with seizures showed a frontal lobe mass with curvilinear narrow calcifications, cystic components and multiple flow‐voids. An AVM was considered. A DSA confirmed the hypervascular nature of the lesion. It was resected and microscopic examination showed an anaplastic oligodendroglioma remarkable for a diffuse and hypertrophic vasculature with areas of frank vascular proliferation. The marked vascularity seen on the MRI, the gyriform calcifications and the cystic degeneration are all features which can be encountered in an AVM. This case illustrates that highly vascular malignant gliomas can simulate vascular lesions by radiology and may require an angiogram for diagnosis.     

Effect of polyphenolic compounds on the proteolytic activities of constitutive and immuno-proteasomes

The effect of several polyphenols on the 20S proteasomes, both the constitutive and the LMP proteasomes, isolated from bovine tissues, has been investigated. Polyphenolic compounds show many biological activities such as antiviral, antibacterial, antifungal, anti-inflammatory, antimutagenic, and antiallergic activities. However, the molecular mechanism underlying these effects has not been identified. It is well established that polyphenols possess inhibitory activities on several enzymes and among them the 20S proteasome. In the present work, the ChT-L, BrAAP, PGPH, and T-L activities of the isolated constitutive and immuno-proteasomes were assayed in order to get an overall information on the polyphenols binding to the complexes. The effects of the polyphenols on the proteasomal activities were analyzed, taking into account the different subunits composition of the two complexes. Furthermore the same activities were measured on whole extracts from cancer cells exposed to EGCG and gallic acid, evaluating, also, their antioxidant action under oxidative stress. EGCG and gallic acid are able to affect the 20S proteasomes functionality, depending on the complex subunit composition and, in cell extracts, they behave both as antioxidants and proteasome effectors.     

Drawing and identifying objects in relation to semantic category and handedness

We investigated whether the directionality of different objects and participants' handedness affected drawing and visual object identification performance. In Experiment 1, 190 participants were asked to draw 246 pictures of objects belonging to different semantic categories. Results showed a preferential direction (leftward, rightward, or frontal view) for most of pictures. In Experiment 2, the directionality patterns found in Experiment 1 were verified in a visual identification task. Sixty participants were requested to identify pictures presented leftward or rightward. For some categories, the speed of responses was greater for pictures having the directionality assessed in the previous experiment. The effect of handedness emerged for two categories of objects (animals and vehicles) characterised by two properties: asymmetry and motion. Findings were discussed in relation to the Motor Image Theory on the isomorphism between motor (drawing) and visual (identification) processes.