A diagnosis of giant cell-rich tumour of bone is supported by p63 immunohistochemistry,when more than 50 % of cells is stained

Some primary malignant or benign tumours of bone contain numerous multinucleated cells. These “giant cell-rich tumours of bone” have overlapping features and clinical and radiological data are needed to reach an accurate pathological diagnosis. We studied the potential contribution of p63 immunohistochemistry to the reliability of the histological diagnosis. We performed a multicentric retrospective study of 291 giant cell-rich tumours of bone which included 119 giant cell tumours of bone (GCTB), 76 aneurysmal bone cysts (ABC), 49 chondroblastomas (CB), 15 nonossifying fibromas (NOF), 10 giant cell reparative granulomas (RG) of jaws, 1 giant cell lesion of small bones, 2 hyperparathyroidism-related brown tumours (BT), 17 bone sarcomas with numerous osteoclasts and 2 malignant giant cell tumours of bone. p63 is expressed in ABC, CB, NOF, RG, BT and GCTB, but its expression in more than 50 % of mononuclear cells is strongly suggestive of a diagnosis of GCTB. In contrast, malignant GCTB were mostly negative. Our results show that p63 is expressed in a broad range of benign giant cell-rich tumours of bone, consistent with data in the recent literature, while infrequent in malignant tumours. With a cut-off 50 %, the presence of p63 positive cells is useful in supporting a diagnosis of giant cell-rich tumour of bone. However, a final diagnosis cannot be made without due consideration of all clinical/radiological and pathological data.     

Clinical spectrum and outcomes in families with coronal synostosis and TCF12 mutations

TCF12 mutations have been reported very recently in coronal synostosis. We report several cases of familial coronal synostosis among four families harbouring novel TCF12 mutations. We observed a broad interfamilial phenotypic spectrum with features overlapping with the Saethre–Chotzen syndrome. TCF12 molecular testing should be considered in patients with unilateral- or bilateral-coronal synostosis associated or not with syndactyly, after having excluded mutations in the TWIST1 gene and the p.Pro250Arg mutation in FGFR3.     

Archaebiotics

Trimethylamine (TMA) is produced by gut bacteria from dietary ingredients. In individuals with a hereditary defect in flavin-containing monooxygenase 3, bacterial TMA production is believed to contribute to the symptoms of trimethylaminuria (TMAU; fish-odor syndrome). Intestinal microbiota TMA metabolism may also modulate atherosclerosis risk by affecting trimethylamine oxide (TMAO) production levels. We propose that reducing TMA formation in the gut by converting it to an inert molecule could be used to prevent or limit these human diseases, while avoiding the major drawbacks of other clinical interventions. Reducing TMA levels by microbiological interventions could also be helpful in some vaginoses. Particular members of a recently discovered group of methanogens, that are variably present in the human gut, are unusual in being apparently restricted to utilizing only methyl compounds including TMA as substrates. We confirmed experimentally that one of these strains tested, Methanomassiliicoccus luminyensis B10, is able to deplete TMA, by reducing it with H₂ for methanogenesis. We therefore suggest that members of this archaeal lineage could be used as treatments for metabolic disorders.     

Is melatonin ready to be used in preterm infants as a neuroprotectant?

The prevention of neurological disabilities following preterm birth remains a major public health challenge and efforts are still needed to test the neuroprotective properties of candidate molecules. Melatonin serves as a neuroprotectant in adult models of cerebral ischemia through its potent antioxidant and anti‐inflammatory effects. An increasing number of preclinical studies have consistently demonstrated that melatonin protects the damaged developing brain by preventing abnormal myelination and an inflammatory glial reaction, a major cause of white matter injury. The main questions asked in this review are whether preclinical data on the neuroprotective properties of melatonin are sufficient to translate this concept into the clinical setting, and whether melatonin can reduce white matter damage in preterm infants. This review provides support for our view that melatonin is now ready to be tested in human preterm neonates, and discusses ongoing and planned clinical trials.     

Decreased osteoclastogenesis in serotonin-deficient mice

Peripheral serotonin, synthesized by tryptophan hydroxylase-1 (TPH(1)), has been shown to play a key role in several physiological functions. Recently, controversy has emerged about whether peripheral serotonin has any effect on bone density and remodeling.We therefore decided to investigate in detail bone remodeling in growing and mature TPH(1) knockout mice (TPH(1)(-/-)). Bone resorption in TPH(1)(-/-) mice, as assessed by biochemical markers and bone histomorphometry, was markedly decreased at both ages. Using bone marrow transplantation, we present evidence that the decrease in bone resorption in TPH(1)(-/-) mice is cell-autonomous. Cultures from TPH(1)(-/-) in the presence of macrophage colony-stimulating factor and receptor activator for NF-KB ligand (RANKL) displayed fewer osteoclasts, and the decreased differentiation could be rescued by adding serotonin. Our data also provide evidence that in the presence of RANKL, osteoclast precursors express TPH(1) and synthesize serotonin. Furthermore, pharmacological inhibition of serotonin receptor 1B with SB224289, and of receptor 2A with ketanserin, also reduced the number of osteoclasts. Our findings reveal that serotonin has an important local action in bone, as it can amplify the effect of RANKL on osteoclastogenesis.     

Highly neurotoxic monomeric α-helical prion protein

Prion diseases are infectious and belong to the group of protein misfolding neurodegenerative diseases. In these diseases, neuronal dysfunction and death are caused by the neuronal toxicity of a particular misfolded form of their cognate protein. The ability to specifically target the toxic protein conformer or the neuronal death pathway would provide powerful therapeutic approaches to these diseases. The neurotoxic forms of the prion protein (PrP) have yet to be defined but there is evidence suggesting that at least some of them differ from infectious PrP (PrP(Sc)). Herein, without making an assumption about size or conformation, we searched for toxic forms of recombinant PrP after dilution refolding, size fractionation, and systematic biological testing of all fractions. We found that the PrP species most neurotoxic in vitro and in vivo (toxic PrP, TPrP) is a monomeric, highly α-helical form of PrP. TPrP caused autophagy, apoptosis, and a molecular signature remarkably similar to that observed in the brains of prion-infected animals. Interestingly, highly α-helical intermediates have been described for other amyloidogenic proteins but their biological significance remains to be established. We provide unique experimental evidence that a monomeric α-helical form of an amyloidogenic protein represents a cytotoxic species. Although toxic PrP has yet to be purified from prion-infected brains, TPrP might be the equivalent of one highly neurotoxic PrP species generated during prion replication. Because TPrP is a misfolded, highly neurotoxic form of PrP reproducing several features of prion-induced neuronal death, it constitutes a useful model to study PrP-induced neurodegenerative mechanisms.