Differential expression analysis for pathways.

Life science technologies generate a deluge of data that hold the keys to unlocking the secrets of important biological functions and disease mechanisms. We present DEAP, Differential Expression Analysis for Pathways, which capitalizes on information about biological pathways to identify important regulatory patterns from differential expression data. DEAP makes significant improvements over existing approaches by including information about pathway structure and discovering the most differentially expressed portion of the pathway. On simulated data, DEAP significantly outperformed traditional methods: with high differential expression, DEAP increased power by two orders of magnitude; with very low differential expression, DEAP doubled the power. DEAP performance was illustrated on two different gene and protein expression studies. DEAP discovered fourteen important pathways related to chronic obstructive pulmonary disease and interferon treatment that existing approaches omitted. On the interferon study, DEAP guided focus towards a four protein path within the 26 protein Notch signalling pathway.

Targeting the spinal nerve via a double-needle, transforaminal approach in failed back surgery syndrome: demonstration of a technique.

Spinal surgery, particularly spinal fusion surgery, alters the anatomy of the spine and hence, may increase the difficulty of performing an interventional spine procedure. Transforaminal epidural procedures have gained popularity as an alternative to interlaminar epidural steroids in the management of radicular pain syndromes. Patients with failed back surgery syndrome are often excluded or represent a minor subset in many clinical studies evaluating the efficacy of transforaminal procedures. When included, however, patients with FBSS have typically undergone laminectomies or microdiscectomies: these procedures are less likely to violate the foraminal space in the spine compared to fusion surgery. We describe the specific details of a transforaminal approach to the epidural space/spinal nerve in a patient with a posterolateral and posterior interbody fusion.

2006 Young Investigator Award Winner: lumbosacral nerve root displacement and strain: part 1. A novel measurement technique during straight leg raise in unembalmed cadavers.

STUDY DESIGN: A descriptive cadaveric study incorporating a novel nerve root marking technique. OBJECTIVES: To describe the displacement and strain of the lumbosacral nerve roots in the lateral recess during straight leg raise (SLR) without disrupting the foraminal ligaments. SUMMARY OF BACKGROUND DATA: Previous studies document 2 to 8 mm of lumbosacral nerve root displacement during SLR. Prior dissection methods incorporated laminectomy and facetectomy. METHODS: Lower limbs and associated nerve roots of 5 unembalmed cadavers (n = 10) were studied. Metal markers were inserted intraneurally within the lateral recess of L4, L5, and S1 with a modified spinal needle. Fluoroscopic images were digitized to evaluate displacement and strain during SLR. RESULTS: The lumbosacral nerve roots in the lateral recess moved less and experienced less strain during SLR than described in previously published reports. Statistically significant distal displacement occurred at hip positions greater than 60 degrees of flexion at all nerve root levels (P < 0.01). CONCLUSIONS: The lumbosacral nerve roots (L4, L5, S1) moved less and underwent less strain during SLR testing than previously reported and may require hip motion greater than 60 degrees to produce substantive displacement in the lateral recess. Additional research is needed to examine the effects of prepositioning during SLR.

2006 Young Investigator Award Winner: lumbosacral nerve root displacement and strain: part 2. A comparison of 2 straight leg raise conditions in unembalmed cadavers.

STUDY DESIGN: An inferential cadaveric study. OBJECTIVES: To compare the displacement and strain of the lumbosacral nerve roots during different conditions of straight leg raise (SLR) with intact foraminal ligaments. SUMMARY OF BACKGROUND DATA: Clinicians use sensitizing movements such as dorsiflexion during neurodynamic testing, assuming that these prepositions influence the displacement or strain to the lumbosacral nerve roots. Little is known about the effect of these prepositions on neurodynamic behavior. METHODS: Lower limbs and associated nerve roots of 5 unembalmed cadavers (n = 10) were used to evaluate the displacement and strain of the L4, L5, and S1 roots during 2 different SLR conditions. Fluoroscopic images of intraneural metal markers were digitized to evaluate displacement and strain during SLR with no preposition (SLR NPP) of the ankle and SLR with dorsiflexion preposition (SLR DF) of the ankle, respectively. RESULTS: SLR NPP produced larger distal displacement at L5 and S1, (P < 0.001) when compared with SLR DF. Displacement comparisons at L4 were nonsignificant (P = 0.051). While nonsignificant, medium to large effect sizes (0.60-0.96) suggest that SLR DF may produce more strain than the SLR NPP condition. CONCLUSIONS: Prepositions of the SLR test alter the displacement and possibly the strain of the lumbosacral nerve roots in the lateral recess.