Sacroiliac Pain: Structural Causes of Pain Referring to the SI Joint Region.

BACKGROUND: The currently reported incidence of primary sacroiliac joint (SIj) pathology ranges from 15% to 30%. The differential diagnosis of SIj region pain includes pain generated from the lumbar spine, the SIj, and the hip joint. The origins of SIj dysfunctions are controversial and pain generation from this joint has been questioned. PURPOSE: Retrospectively analyze the relative incidence of lumbar spine, SIj, and hip joint etiologies in patients complaining of ≥50% SIj region pain. STUDY DESIGN: This is a retrospective cohort case series. METHODS: Inclusion criteria: chief complaint SIj pain (≥50% of overall complaint). In total, 124 patients charts were reviewed from a single spine surgeon's clinic. All patients were evaluated by the same 2 practitioners and all cases were reviewed for clinical examination findings, diagnostic tests performed, final diagnosis, treatment, and clinical follow-up. RESULTS: After complete diagnostic workup, 112 (90%) had lumbar spine pain, 5 (4%) had hip pain, 4 (3%) had primary SIj pain, and 3 (3%) had an undetermined source of pain upon initial diagnosis. SIj pain generation was confirmed via fluoroscopy-guided diagnostic injections. Following designated treatment, 11 (9%) patients returned to clinic at an average of 2.4 years complaining of continued/recurrent SIj region pain. Further investigation revealed 6 patients had confirmed pain generation from the lumbar spine, 3 patients had confirmed pain generation from the SIj, and 2 patients had undetermined sources of pain. CONCLUSIONS: The SIj is a rare pain generator (3%-6%) in patients complaining of ≥50% SIj region pain and is a common site of referral pain from the lumbar spine (88%-90%). Clinicians ought to quantify areas of pain (via percent of overall complaint) when interviewing their patients complaining of low back pain to distinguish potential pain generators. Recommended breakdown of areas of interest include axial low back, SIj region, buttock/leg, groin/anterior thigh.

Navigation accuracy comparing non-covered frame and use of plastic sterile drapes to cover the reference frame in 3D acquisition.

BACKGROUND: Advancements in surgical navigation technology coupled with 3-dimensional (3D) radiographic data have significantly enhanced the accuracy and efficiency of spinal fusion implant placement. Increased usage of such technology has led to rising concerns regarding maintenance of the sterile field, as makeshift drape systems are fraught with breaches thus presenting increased risk of surgical site infections (SSIs). A clinical need exists for a sterile draping solution with these techniques. Our objective was to quantify expected accuracy error associated with 2MM and 4MM thickness Sterile-Z Patient Drape® using Medtronic O-Arm® Surgical Imaging with StealthStation® S7® Navigation System. Camera distance to reference frame was investigated for contribution to accuracy error. METHODS: A testing jig was placed on the radiolucent table and the Medtronic passive reference frame was attached to jig. The StealthStation® S7® navigation camera was placed at various distances from testing jig and the geometry error of reference frame was captured for three different drape configurations: no drape, 2MM drape and 4MM drape. The O-Arm® gantry location and StealthStation® S7® camera position was maintained and seven 3D acquisitions for each of drape configurations were measured. Data was analyzed by a two-factor analysis of variance (ANOVA) and Bonferroni comparisons were used to assess the independent effects of camera angle and drape on accuracy error. RESULTS: Median (and maximum) measurement accuracy error was higher for the 2MM than for the 4MM drape for each camera distance. The most extreme error observed (4.6 mm) occurred when using the 2MM and the 'far' camera distance. The 4MM drape was found to induce an accuracy error of 0.11 mm (95% confidence interval, 0.06-0.15; P<0.001) relative to the no drape testing, regardless of camera distance. Medium camera distance produced lower accuracy error than either the close (additional 0.08 mm error; 95% CI, 0-0.15; P=0.035) or far (additional 0.21mm error; 95% CI, 0.13-0.28; P<0.001) camera distances, regardless of whether a drape was used. CONCLUSIONS: In comparison to the 'no drape' condition, the accuracy error of 0.11 mm when using a 4MM film drape is minimal and clinically insignificant.

Modeling and high-throughput experimental data uncover the mechanisms underlying Fshb gene sensitivity to gonadotropin-releasing hormone pulse frequency.

Neuroendocrine control of reproduction by brain-secreted pulses of gonadotropin-releasing hormone (GnRH) represents a longstanding puzzle about extracellular signal decoding mechanisms. GnRH regulates the pituitary gonadotropin's follicle-stimulating hormone (FSH) and luteinizing hormone (LH), both of which are heterodimers specified by unique ß subunits (FSHß/LHß). Contrary to Lhb, Fshb gene induction has a preference for low-frequency GnRH pulses. To clarify the underlying regulatory mechanisms, we developed three biologically anchored mathematical models: 1) parallel activation of Fshb inhibitory factors (e.g. inhibin α and VGF nerve growth factor-inducible), 2) activation of a signaling component with a refractory period (e.g. G protein), and 3) inactivation of a factor needed for Fshb induction (e.g. growth differentiation factor 9). Simulations with all three models recapitulated the Fshb expression levels obtained in pituitary gonadotrope cells perifused with varying GnRH pulse frequencies. Notably, simulations altering average concentration, pulse duration, and pulse frequency revealed that the apparent frequency-dependent pattern of Fshb expression in model 1 actually resulted from variations in average GnRH concentration. In contrast, models 2 and 3 showed "true" pulse frequency sensing. To resolve which components of this GnRH signal induce Fshb, we developed a high-throughput parallel experimental system. We analyzed over 4,000 samples in experiments with varying near-physiological GnRH concentrations and pulse patterns. Whereas Egr1 and Fos genes responded only to variations in average GnRH concentration, Fshb levels were sensitive to both average concentration and true pulse frequency. These results provide a foundation for understanding the role of multiple regulatory factors in modulating Fshb gene activity.

A plasmodesmal glycosyltransferase-like protein.

Plasmodesmata (Pd) are plant intercellular connections that represent cytoplasmic conduits for a wide spectrum of cellular transport cargoes, from ions to house-keeping proteins to transcription factors and RNA silencing signals; furthermore, Pd are also utilized by most plant viruses for their spread between host cells. Despite this central role of Pd in the plant life cycle, their structural and functional composition remains poorly characterized. In this study, we used a known Pd-associated calreticulin protein AtCRT1 as bait to isolate other Pd associated proteins in Arabidopsis thaliana. These experiments identified a beta-1,6-N-acetylglucosaminyl transferase-like enzyme (AtGnTL). Subcellular localization studies using confocal microscopy observed AtGnTL at Pd within living plant cells and demonstrated colocalization with a Pd callose-binding protein (AtPDCB1). That AtGnTL is resident in Pd was consistent with its localization within the plant cell wall following plasmolysis. Initial characterization of an Arabidopsis T-DNA insertional mutant in the AtGnTL gene revealed defects in seed germination and delayed plant growth.