Persistent phosphaturic mesenchymal tumor causing tumor-induced osteomalacia treated with image-guided ablation.

Phosphaturic mesenchymal tumors (PMTs) can present with vague symptoms of diffuse bone pain with pathologic fractures that often lead to a delayed diagnosis. We present a 60-year-old patient with a PMT that was persistently hypophosphatemic after resection, who was then successfully treated with cryoablation of the tumor. Tumor-induced osteomalacia (TIO) is a rare cause of hypophosphatemia characterized by vague symptoms of gradual muscle weakness and diffuse bone pain with pathologic fractures that often lead to a delayed diagnosis. This condition is usually caused by benign phosphaturic mesenchymal tumors (PMTs). Here, we present a case of persistent PMT after surgical resection treated with image-guided ablation. We present the patient's clinical examinations and laboratory findings (phosphorus, 1,25 (OH)2D, FGF-23, Intact PTH). Representative histologic images of a PMT are also presented. A 61-year-old male was evaluated for persistent hypophosphatemia and presumed osteomalacia. Six years earlier, he underwent surgical excision of a left ischial mass after presenting with TIO. The pathology was consistent with a PMT; however, hypophosphatemia persisted suggesting incomplete resection. He was treated with calcitriol and phosphate salts. A PET Ga68 dotatate scan of the patient revealed an avid left ischial mixed lytic and sclerotic lesions with marked amount of radiotracer uptake, suggesting persistent tumor. The patient was resistant to re-excision of the tumor due to the extended recovery period from his prior surgery and was treated instead with cryoablation of the tumor. His biochemical findings of hypophosphatemia and elevated FGF23 resolved after the ablation and have remained normal for 5 months after surgery. In patients with TIO, wide surgical excision is the treatment of choice. When this is not possible, image-guided ablation is an alternative therapeutic option.

Pain management: The rising role of interventional oncology.

Patients with early or metastatic cancer may suffer from pain of different origins. The vast majority of these patients are not adequately treated by means of systemic analgesia and radiotherapy. Percutaneous neurolysis is performed using chemical agents or thermal energy upon sympathetic nervous system plexus for pain reduction and life quality improvement. Ablation and vertebral augmentation are included in clinical guidelines for metastatic disease. As far as the peripheral skeleton is concerned bone augmentation and stabilization can be performed by means of cement injection either solely performed or in combination to cannulated screws or other metallic or peek implants. This review describes the basic concepts of interventional oncology techniques as therapies for cancer pain management. The necessity for a tailored-based approach applying different techniques for different cases and locations will be addressed.

Critique of the analysis of UpToDate.com on the treatment of painful vertebral compression fractures: time to update UpToDate.

The treatment of painful vertebral compression fractures has changed substantially since the introduction of vertebroplasty in the mid-1980s and balloon kyphoplasty in the late 1990s. Both procedures were widely accepted with the vertebral fractures treated reaching 150,000 per annum in 2009 prior to the publication of 2 randomized controlled trials comparing vertebroplasty with a sham treatment published in the New England Journal of Medicine in August 2009. Since then, there has been a flood of information on vertebral augmentation and balloon kyphoplasty. It is worth evaluating this information especially because it relates to current recommendations that are often followed blindly by medical and administrative groups unfamiliar with either the procedure or the high level of evidence surrounding vertebral augmentation. To streamline the evaluation of some current recommendations, we limited the analysis to the recommendations found on UpToDate.com. This Web site is an evidence-based, peer-reviewed source of information available for patients, doctors, health insurance companies, and population-based medical decision-making.

Specific double-stranded RNA interference in undifferentiated mouse embryonic stem cells.

Specific mRNA degradation mediated by double-stranded RNA (dsRNA) interference (RNAi) is a powerful way of suppressing gene expression in plants, nematodes, and fungal, insect, and protozoan systems. However, only a few cases of RNAi have been reported in mammalian systems. Here, we investigated the feasibility of the RNAi strategy in several mammalian cells by using the enhanced green fluorescent protein gene as a target, either by in situ production of dsRNA from transient transfection of a plasmid harboring a 547-bp inverted repeat or by direct transfection of dsRNA made by in vitro transcription. Several mammalian cells including differentiated embryonic stem (ES) cells did not exhibit specific RNAi in transient transfection. This long dsRNA, however, was capable of inducing a sequence-specific RNAi for the episomal and chromosomal target gene in undifferentiated ES cells. dsRNA at 8.3 nM decreased the cognate gene expression up to 70%. However, RNAi activity was not permanent because it was more pronounced in early time points and diminished 5 days after transfection. Thus, undifferentiated ES cells may lack the interferon response, similar to mouse embryos and oocytes. Regardless of their apparent RNAi activity, however, cytoplasmic extracts from mammalian cells produced a small RNA of 21 to 22 nucleotides from the long dsRNA. Our results suggest that mammalian cells may possess RNAi activity but nonspecific activation of the interferon response by longer dsRNA may mask the specific RNAi. The findings offer an opportunity to use dsRNA for inhibition of gene expression in ES cells to study differentiation.

The basis for k(cat) impairment in prophospholipase A(2) from the anion-assisted dimer structure.

Kinetic results in this paper show that, contrary to earlier reports, pig pancreatic prophospholipase A(2) (proPLA2) does not hydrolyze monodisperse short chain phosphatidylcholine below the critical micelle concentration. ProPLA2 is active on an anionic interface, but at a rate that is decreased by more than 100-fold compared to that of PLA2, the active form. Solution studies show that both proPLA2 and PLA2 bind to an anionic interface and also bind a tetrahedral intermediate mimic at the active site. The 1.5 A resolution crystal structure of the anion-assisted dimer of proPLA2 reported in this paper is compared with the corresponding structure for PLA2 [Pan, Y. H., et al. (2001) Biochemistry 40, 609-617]. As a mimic for the forms bound to the anionic interface, these structures provide insights into the possible structural basis for the impaired chemical step of the zymogen. The proPLA2 dimer contained within one crystallographic asymmetric unit has one molecule of the inhibitor 1-hexadecyl-3-(trifluoroethyl)-sn-glycero-2-phosphomethanol and is bridged by four coplanar sulfate anions. Relative to the structure of PLA2, the subunit contact surface in proPLA2 displays a tilted orientation, an altered mode of inhibitor binding, displacement of a mechanistically significant loop that includes Tyr69, and a critical active site water seen in PLA2 that is not seen in proPLA2. These differences are interpreted to suggest possible origins of the functional differences between the pro and active enzyme at an anionic interface. A structural origin of this difference is discussed in terms of the calcium-coordinated activated water mechanism of the esterolysis reaction. Together, a comparison of the structures of the anion-assisted dimers of PLA2 and proPLA2 not only offers an explanation of why the zymogen form is k(cat)-impaired and binds poorly even to the anionic interface but also supports a mechanism for the activated enzyme that includes a critical second-sphere assisting water bridging His48 and the calcium-coordinated catalytic water.

MR imaging of the adult elbow.

Magnetic resonance (MR) imaging can provide important diagnostic information in the evaluation of the adult elbow. Optimal imaging technique should include the use of proper positioning, surface coils, and appropriate sequences and imaging planes as indicated by the suspected abnormalities. A familiarity with the anatomy of the normal elbow is crucial to identifying pathologic entities correctly and avoiding diagnostic pitfalls. Disruption of the collateral ligaments can best be demonstrated with thin-section coronal gradient-echo MR images. Injuries to the flexor and extensor muscle groups, biceps muscles, and triceps muscles require T2-weighted or short-inversion-time inversion recovery (STIR) MR images in the long and short axes of the affected muscle. The evaluation of osteochondral lesions and intraarticular bodies is optimized with T1-weighted and STIR MR images. Synovial processes usually necessitate the intravenous administration of gadopentetate dimeglumine to distinguish joint fluid from pannus. The contents of the cubital tunnel are best visualized on axial T1-weighted and STIR MR images. Masses arising in or near the elbow should be imaged with multiple sequences in at least two planes, and involvement of adjacent vital structures should be carefully evaluated.