Pain Relief and Safety Outcomes with Cervical 10 kHz Spinal Cord Stimulation: Systematic Literature Review and Meta-analysis.

BACKGROUND: Chronic pain in head, neck, shoulders and upper limbs is debilitating, and patients usually rely on pain medications or surgery to manage their symptoms. However, given the current opioid epidemic, non-pharmacological interventions that reduce pain, such as spinal cord stimulation (SCS), are needed. The purpose of this study was to review the evidence on paresthesia-free 10 kHz SCS therapy for neck and upper extremity pain. METHODS: Systematic literature search was performed for studies reporting outcomes for cervical 10 kHz SCS using date limits from May 2008 to November 2020. The study results were analyzed and described qualitatively. Additionally, when feasible, meta-analyses of the outcome data, with 95% confidence intervals (CIs), were conducted using both the fixed-effects (FE) and random-effects (RE) models. RESULTS: A total of 15 studies were eligible for inclusion. The proportion of patients who achieved ≥ 50% pain reduction was 83% (95% CI 77-89%) in both the FE and RE models. The proportion of patients who reduced/eliminated their opioid consumption was 39% (95% CI 31-46%) in the FE model and 39% (95% CI 31-48%) in the RE model. Pain or discomfort with the implant, lead migration, and infections were potential risks following cervical SCS. Explant rate was 0.1 (95% CI 0.0-0.2) events per 100 person-months, and no patients in the included studies experienced a neurological complication or paresthesia. CONCLUSION: Findings suggest 10 kHz SCS is a promising, safe, minimally invasive alternative for managing chronic upper limb and neck pain.

A convenient route to tetraalkylammonium perfluoroalkoxides from hydrofluoroethers.

Hydrofluoroethers are shown to alkylate tertiary amines readily under solvent-free conditions, affording valuable tetraalkylammonium perfluoroalkoxides bearing α-fluorines. The reaction of R(F)CF2-OCH3 (R(F)=CF2CF3, CF2CF2CF3, and CF(CF3)2) with NR(1)R(2)R(3) produces twenty new α-perfluoroalkoxides, [(CH3)NR(1)R(2)R(3)][R(F)CF2O] under mild conditions. These α-perfluoroalkoxides are easy to handle, thermally stable, and can be used for the perfluoroalkoxylation of benzyl bromides.

DLL4-Notch signaling mediates tumor resistance to anti-VEGF therapy in vivo.

Resistance to VEGF inhibitors is emerging as a major clinical problem. Notch signaling has been implicated in tumor angiogenesis. Therefore, to investigate mechanisms of resistance to angiogenesis inhibitors, we transduced human glioblastoma cells with retroviruses encoding Notch delta-like ligand 4 (DLL4), grew them as tumor xenografts and then treated the murine hosts with the VEGF-A inhibitor bevacizumab. We found that DLL4-mediated tumor resistance to bevacizumab in vivo. The large vessels induced by DLL4-Notch signaling increased tumor blood supply and were insensitive to bevacizumab. However, blockade of Notch signaling by dibenzazepine, a γ-secretase inhibitor, disrupted the large vessels and abolished the tumor resistance. Multiple molecular mechanisms of resistance were shown, including decreased levels of hypoxia-induced VEGF and increased levels of the VEGF receptor VEGFR1 in the tumor stroma, decreased levels of VEGFR2 in large blood vessels, and reduced levels of VEGFR3 overall. DLL4-expressing tumors were also resistant to a VEGFR targeting multikinase inhibitor. We also observed activation of other pathways of tumor resistance driven by DLL4-Notch signaling, including the FGF2-FGFR and EphB4-EprinB2 pathways, the inhibition of which reversed tumor resistance partially. Taken together, our findings show the importance of classifying mechanisms involved in angiogenesis in tumors, and how combination therapy to block DLL4-Notch signaling may enhance the efficacy of VEGF inhibitors, particularly in DLL4-upregulated tumors, and thus provide a rational base for the development of novel strategies to overcome antiangiogenic resistance in the clinic.

Cell-penetrating metal complex optical probes: targeted and responsive systems based on lanthanide luminescence.

To understand better the structure and function of biological systems, cell biologists and biochemists would like to have methods that minimally perturb living systems. The development of emissive optical probes is essential for improving our observation of intracellular signaling and recognition processes. Following excitation of the probe, photons emitted from the probe may be observed by spectroscopy or microscopy and encode information about their environments in their energy, lifetime, and polarization. Such optical probes may be based on organic fluorophores, quantum dots, recombinant proteins, or emissive metal complexes. In this Account, we trace the emergence of lanthanide coordination complexes as emissive optical probes. These probes benefit from sharp emission bands and long lifetimes. We can design these complexes to report on the concentration of key biochemical variables by modulation of spectral form, lifetime, or circular polarization. These properties allow us to apply ratiometric methods of analysis in spectroscopy or microscopy to report on local pH, pM (M = Ca, Zn), or the concentration of certain anionic metabolites, such as citrate, lactate, bicarbonate, or urate. For optical microscopy studies in living cells, these probes must be cell-permeable and, ideally, should localize in a given cell organelle. We undertook systematic studies of more than 60 emissive complexes, examining the time dependence of cellular uptake and compartmentalization, cellular toxicity, protein affinity, and quenching sensitivity. These results and their relationship to probe structure have allowed us to identify certain structure-activity relationships. The nature and linkage mode of the integral sensitizing group-introduced to harvest incident light efficiently-is of primary importance in determining protein affinity and cellular uptake and trafficking. In many cases, uptake may occur via macropinocytosis. We have defined three main classes of behavior: complexes exhibit predominant localization profiles in protein-rich regions (nucleoli/ribosomes), in cellular mitochondria, or in endosomes/lysosomes. Therefore, these systems offer considerable promise as intracellular optical probes, amenable to single- or two-photon excitation, that may report on the local ionic composition of living cells subjected to differing environmental stresses.

Enantioselective regulation of a metal complex in reversible binding to serum albumin: dynamic helicity inversion signalled by circularly polarised luminescence.

The helicity of the (SSS)-Delta enantiomer of a terbium and europium(III) complex is inverted on reversible binding to 'drug site II' of serum albumin, signalled by a switch in its circularly polarised emission; no such behaviour occurs with the (RRR)-Lambda complexes, thereby defining a unique chiroptical probe of albumin binding.

A mechanistic study of the dynamic quenching of the excited state of europium(III) and terbium(III) macrocyclic complexes by charge- or electron transfer.

Dynamic quenching of the metal-based excited state of Eu(III) and Tb(III) complexes of sixteen different macrocyclic ligands has been studied. Quenching by urate, ascorbate and selected catechols is most effective for Tb(III) systems, and involves intermediate formation of an excited state complex (exciplex) between the electron-poor heterocyclic sensitising moiety incorporated into the ligand (tetraazatriphenylene, azaxanthone or a pyrazoyl-azaxanthone) and the electron-rich reductant. The process is sensitive to steric inhibition created by the local ligand environment; quenching is reduced as temperature increases as exciplex formation is entropically disfavoured. In contrast, iodide quenches each complex studied according to a classical collisional encounter model; increasing temperature enhances the rate of quenching, and the process is more sensitive to local electrostatic fields generated by ligand substitution, conforming to a traditional Stern-Volmer kinetic model. Quenching may be inhibited by protein association, allowing the identification of candidates for use as optical imaging probes in cellulo.

Identification of emissive lanthanide complexes suitable for cellular imaging that resist quenching by endogenous anti-oxidants.

Excited state quenching by urate and ascorbate of selected europium and terbium(III) macrocyclic complexes has been assessed and related to the ease of complex visualisation by optical microscopy inside various living cells, e.g. CHO, COS and NIH 3T3. It is the relative insensitivity of certain sterically encumbered complexes to dynamic quenching by urate that favours their usage for in cellulo applications. Non-covalent binding of the complex by protein also shields the excited lanthanide(III) ion from collisional quenching; this effect is most marked for a cationic triamide complex, [Ln.1](3+), consistent with its ease of visualisation by luminescence microscopy.

Effective and efficient sensitisation of terbium luminescence at 355 nm with cell permeable pyrazoyl-1-azaxanthone macrocyclic complexes.

Emissive terbium complexes, suitable for protein conjugation, incorporating a pyrazoyl-1-aza-xanthone chromophore have been prepared; they exhibit cellular uptake and possess a much lower sensitivity to excited state quenching.

Gamma knife surgery for trigeminal neuralgia: improved initial response with two isocenters and increasing dose.

OBJECT: The authors sought to evaluate the initial response of trigeminal neuralgia (TN) to gamma knife surgery (GKS) based on the number of shots delivered and radiation dose. METHODS: Between September 1998 and September 2003, some 63 patients with TN refractory to medical or surgical management underwent GKS at Upstate Medical University. Ten patients had multiple sclerosis and 25 patients had undergone prior invasive treatment. Gamma knife surgery was delivered to the trigeminal nerve root entry zone in one shot in 27 patients or two shots in 36 patients. The radiation dose was escalated to less than or equal to 80 Gy in 20 patients, 85 Gy in 21 patients, and greater than or equal to 90 Gy in 22 patients. Pain before and after GKS was assessed using the Barrow Neurological Institute Pain Scale and the improvement score was analyzed as a function of dose grouping and number of shots. Sixty patients were available for evaluation, with an initial overall and complete response rate of 90% and 27%, respectively. There was a greater improvement score for patients who were treated with two shots compared with one shot, mean 2.83 compared with 1.72 (p < 0.001). There was an increased improvement in score at each dose escalation level: less than or equal to 80 Gy (p = 0.017), 85 Gy (p < 0.001), and greater than or equal to 90 Gy (p < 0.001). Linear regression analysis also indicated that there was a greater response with an increased dose (p = 0.021). Patients treated with two shots were more likely to receive a higher dose (p < 0.001). There were no severe complications. Five patients developed mild facial numbness. CONCLUSIONS: Gamma knife surgery is an effective therapy for TN. Initial response rates appear to correlate with the number of shots and dose.

Successful treatment of spindle cell sarcoma of the sella turcica. Case report.

A primary spindle cell sarcoma of the sella turcica in a patient without a history of radiation treatment is a very rare occurrence. Only one other case has been reported to date, with local recurrence 7 months after the patient underwent subtotal resection and stereotactic radiosurgery of the tumor. The authors present a case of spindle cell sarcoma of the sella turcica successfully treated by surgery, external-beam radiotherapy, and gamma knife radiosurgery. After 24 months of follow up, the patient continues to show no evidence of disease.