Unexpected silicon localization in calcium carbonate exoskeleton of cultured and fossil coccolithophores.

Coccolithophores, marine calcifying phytoplankton, are important primary producers impacting the global carbon cycle at different timescales. Their biomineral structures, the calcite containing coccoliths, are among the most elaborate hard parts of any organism. Understanding the morphogenesis of coccoliths is not only relevant in the context of coccolithophore eco-physiology but will also inform biomineralization and crystal design research more generally. The recent discovery of a silicon (Si) requirement for crystal shaping in some coccolithophores has opened up a new avenue of biomineralization research. In order to develop a mechanistic understanding of the role of Si, the presence and localization of this chemical element in coccoliths needs to be known. Here, we document for the first time the uneven Si distribution in Helicosphaera carteri coccoliths through three synchrotron-based techniques employing X-ray Fluorescence and Infrared Spectromicroscopy. The enrichment of Si in specific areas of the coccoliths point to a targeted role of this element in the coccolith formation. Our findings mark a key step in biomineralization research because it opens the door for a detailed mechanistic understanding of the role Si plays in shaping coccolith crystals.

[Study of codeine-paracetamol combination treatment compared with tramadol-paracetamol in the control of moderate-to-severe low back pain]. / Associazione codeina-paracetamolo e tramadolo-paracetamolo nel controllo del dolore lombare moderato-severo.

AIM: The objective of this study was to compare the analgesic efficacy and tolerability of tramadol hydrochloride compared with codeine phosphate in combination with paracetamol in patients with moderate-to-severe low back pain caused by osteoarthritis. In fact, while paracetamol is the analgesic of choice for this disease, in cases where this treatment may be ineffective, the therapeutic choice involves the addition of weak opioids. Due to the chronic nature of the disease, these drugs represent a safer alternative compared to anti-inflammatory drugs (NSAIDs) and selective inhibitors of cyclooxygenase 2 (COX-2). METHODS: In the present study two combination treatments were considered: codeine-paracetamol (respectively 30 mg and 500 mg) and tramadol-paracetamol (respectively 37.5 mg and 325 mg). The study duration was 4 weeks and involved 38 patients (mean age 64.7 years). The effectiveness of the two treatments was assessed in terms of analgesic efficacy, tolerability and safety. RESULTS: The results recorded after a week of treatment and at the end of the study showed a difference in favour of codeine-paracetamol association which showed slightly higher values ​​in pain improvement and, above all, was better tolerated in terms of adverse events and drop out. CONCLUSION: The study, although conducted on a limited number of patients and for a relatively short time, demonstrates the greater efficacy and tolerability of the association codeine-paracetamol compared to tramadol-paracetamol.

Comparison of the effects of colchicine and beta-lumicolchicine on cultured adrenal chromaffin cells: lack of evidence for an action of colchicine on receptor-associated microtubules.

The involvement of microtubules in adrenomedullary secretion is presently unclear. Evidence exists for a possible role of microtubules in cholinergic nicotinic receptor-related events. We now describe the actions of the microtubule disrupter, colchicine, on primary cultures of bovine adrenal chromaffin cells and compare these with corresponding actions of beta-lumicolchicine. beta-Lumicolchicine is a structural isomer of colchicine which neither binds microtubular protein (tubulin) nor interferes with microtubule assembly. Both colchicine and beta-lumicolchicine were found to inhibit acetylcholine-induced secretion with similar potencies (half maximal inhibitory concentration 0.2-0.5 mM). The inhibitory actions of both drugs are time-dependent and reversible. However, unlike colchicine which has no inhibitory effects on secretion evoked by depolarization with excess K+, beta-lumicolchicine also inhibits K+-induced secretion. Because colchicine and beta-lumicolchicine have similar effects, the selective inhibitory actions of colchicine on nicotinic receptor-mediated secretion cannot in itself be used as evidence in support of a role of microtubules in receptor-mediated events. However, our data do not preclude such a role. Differences in the effect of colchicine and beta-lumicolchicine on K+-evoked secretion suggests different modes of action of these structural isomers on chromaffin cell function.