Treatment of chronic low back pain - new approaches on the horizon

Back pain is the second leading cause of disability among American adults and is currently treated either with conservative therapy or interventional pain procedures. However, the question that remains is whether we, as physicians, have adequate therapeutic options to offer to the patients who suffer from chronic low back pain but fail both conservative therapy and interventional pain procedures before they consider surgical options such as discectomy, disc arthroplasty, or spinal fusion. The purpose of this article is to review the potential novel therapies that are on the horizon for the treatment of chronic low back pain. We discuss medications that are currently in use through different phases of clinical trials (I–III) for the treatment of low back pain. In this review, we discuss revisiting the concept of chemonucleolysis using chymopapain, as the first drug in an intradiscal injection to reduce herniated disc size, and newer intradiscal therapies, including collagenase, chondroitinase, matrix metalloproteinases, and ethanol gel. We also review an intravenous glial cell-derived neurotrophic growth factor called artemin, which may repair sensory nerves compressed by herniated discs. Another new drug in development for low back pain without radiculopathy is a subcutaneous monoclonal antibody acting as nerve growth factor called tanezumab. Finally, we discuss how platelet-rich plasma and stem cells are being studied for the treatment of low back pain. We believe that with these new therapeutic options, we can bridge the current gap between conservative/interventional procedures and surgeries in patients with chronic back pain.

Vesicourethral anastomosis biopsy after radical prostatectomy: predictive value of prostate-specific antigen and pathologic stage

OBJECTIVES

To assess the role of clinical parameters and pathologic stage in predicting a positive vesicourethral anastomosis (VUA) biopsy in patients with a rising prostate-specific antigen (PSA) level after radical prostatectomy.

METHODS

Forty-five patients were referred for a rising PSA level after radical prostatectomy. Transrectal ultrasound evaluation included visualization of the VUA and VUA quadrant biopsies. The rate of positive biopsies (per core and per patient) was correlated with race, PSA level, and the radical prostatectomy pathologic stage.

RESULTS

Overall, 53% of patients had a positive biopsy. In multivariate analysis, the dominant independent and synergistic clinical parameters determining positive biopsy rates were a PSA greater than 1 ng/mL at the time of biopsy and the pathologic stage (P = 0.04 and P = 0.02, respectively). Using a PSA cutoff point of 1.0 ng/mL, those patients with organ-confined disease and a PSA of 1.0 ng/mL or less showed no positive cancer cores (low-risk group). Conversely, 89% of patients with extraprostatic extension and a PSA greater than 1.0 ng/mL had a positive biopsy (P <0.01) (high-risk group). Patients with organ-confined disease and a PSA greater than 1.0 ng/mL or extraprostatic extension and a PSA 1.0 ng/mL or less (intermediate-risk group) had a significantly higher chance of having residual cancer than the low-risk group (P <0.025).

CONCLUSIONS

The PSA level at the time of biopsy and the pathologic stage of the radical prostatectomy specimen were the strongest determinants of a positive biopsy. A combination of PSA and pathologic stage is useful for decisions regarding VUA biopsy. Patients with organ-confined disease and a PSA of 1.0 ng/mL or less do not appear to benefit from a VUA biopsy, and patients with extraprostatic extension and a PSA greater than 1.0 ng/mL have such a high probability (89%) of local recurrence at the VUA that biopsy may be unnecessary. It appears that VUA biopsy can be restricted to those patients with an intermediate risk (organ-confined disease with PSA greater than 1 ng/mL or extraprostatic extension with a PSA less than 1 ng/mL).

Alteration in cellular morphology, density and distribution in rat vocal fold mucosa following injury

The vocal fold mucosa plays an important role in voice production. Its cellular composition and density frequently change under various pathological conditions, often contributing to altered extracellular matrix production, tissue viscoelasticity, and voice quality. In this study, cellular changes in the rat mucosa following a unilateral stripping injury were investigated and analyzed semi-quantitatively. Distinctive and sequential changes in cellular morphology, composition, and density were observed in the mucosa post-injury. Cellular recruitment was a major event during the early stage of injury and reached its peak level by day 5 post-injury. Several types of cells, including neutrophil-like cells, epithelial cells, and fibroblast-like cells, were sequentially recruited. The sequential emergence of reactive cell populations following injury and subsequent reconstruction of the mucosa suggests their involvement in vocal fold tissue repair and scar formation processes.

E-cadherin and transglutaminase-1 epithelial barrier restoration precedes type IV collagen basement membrane reconstruction following vocal fold mucosal injury

The vocal fold epithelium is critical to upper airway immunologic defense and water/ion transport; therefore, any form of physical trauma or insult increases the vulnerability of this structure to functional impairment and pathogen invasion/infection. In this study, we examined the reestablishment of epithelial and basement membrane barrier structures in a well-established rat model of vocal fold mucosal injury. We observed active cell recruitment culminating in peak hyperplasia at 3 days postinjury, the establishment of robust E-cadherin+ and transglutaminase-1+ biochemical barrier signals along the epithelial surface by 3 days postinjury, and the persistent absence of a type IV collagen+ basement membrane at 7 days postinjury. The distinct spatial and temporal immunoactivity of these molecules is consistent with a programmed repair process driving the restoration of vocal fold mucosal integrity and permeability. These data may inform future efforts to optimize functional mucosal recovery postinjury and avoid undesirable events such as barrier compromise or epithelial metaplasia.

Microbunching instability in relativistic electron bunches: direct observations of the microstructures using ultrafast YBCO detectors

Relativistic electron bunches circulating in accelerators are subjected to a dynamical instability leading to microstructures at millimeter to centimeter scale. Although this is a well-known fact, direct experimental observations of the structures, or the field that they emit, remained up to now an open problem. Here, we report the direct, shot-by-shot, time-resolved recording of the shapes (including envelope and carrier) of the pulses of coherent synchrotron radiation that are emitted, and that are a "signature" of the electron bunch microstructure. The experiments are performed on the UVSOR-III storage ring, using electrical field sensitive YBa2Cu3O(7-x) thin-film ultrafast detectors. The observed patterns are subjected to permanent drifts, that can be explained from a reasoning in phase space, using macroparticle simulations.