Multiple myeloma and chemical maxillary osteonecrosis. Can both occur simultaneously?

INTRODUCTION: The aim of the present study was to investigate the number of patients with Multiple Myeloma (MM) treated with intravenous Zoledronic Acid who presented an involvement of the jaws by Myeloma that mimicked an osteonecrosis. MATERIAL AND METHODS: A retrospective study was performed in a University Hospital reference for a population of 1.084.000 inhabitants. A 'case' Medication-Related Osteonecrosis of the jaw (MRONJ) was considered when the patient met diagnostic criteria established by the American Association of Oral and Maxillofacial Surgeons (AAOMS, 2014). We recorded data on the underlying disease, medications used, mode of Bisphosphonate administration (oral or intravenous), and timing of medication use. RESULTS: The sample size was 84 cases. 22 patients had MRONJ associated to MM treatment. Histopathological examination of pathological bone was characterized by the presence of necrotic osteitis in 82 patients. Only 2 patients with MRONJ suspicion were finally diagnosed as MM. These cases represented 9.09% of all patients with multiple myeloma initially labeled MRONJ in our hospital. CONCLUSION: The present study has shown that MM can be identified in jaw specimens of patients exposed to Bisphosphonates and clinically diagnosed as osteonecrosis. Biopsy examination should be considered in at least selected cases, for example, before surgical treatment in patients with MM and clinical stage 3 osteonecrosis (due to the detection of malignancy would alter the surgical strategy).

Differential utilization of Trk autophosphorylation sites.

Tyrosine autophosphorylation controls the catalytic and signaling activities of the neurotrophin receptors, the Trks. To analyze the regulation of distinct tyrosine sites, we generated a panel of antibodies that report the phosphorylation state of individual tyrosines within the Trk cytoplasmic domain. Using pheochromocytoma-derived cell lines, we show that individual tyrosines within the nerve growth factor receptor TrkA are phosphorylated in a non-coordinate fashion following receptor activation. The non-coordinate response of these tyrosines reflects their separate functions in regulating the catalytic and signaling activities of Trk receptors. The differential utilization of distinct sites on Trk receptor tyrosine kinases suggests that the receptor can specify both the timing and the nature of neurotrophin-stimulated signal transduction pathways. Moreover, we show that these Trk autophosphorylation sites, which have hitherto been mapped and characterized only in non-neuronal cell lines, are activated in normal neurons in response to ligand stimulation.

Purification and characterization of two distinct lipases from Candida cylindracea.

We have purified and characterized two isoenzymes from a commercial lipase preparation of Candida cylindracea. The purification procedure includes ethanol precipitation and DEAE-Sephacel and Sephacryl HR 100 chromatographies. Lipase A and lipase B were purified 11-fold with a 5% and 21% recovery in activity, respectively. The enzymes have similar amino acid content, N-terminal sequence and molecular weight, but differ on neutral sugar content, hydrophobicity, presence of isoforms and stability to pH and temperature. They also show some differences in the substrate specificity.