This research investigates various applications of diffuse correlation spectroscopy (DCS) on in-vivo human muscle tissue, both at rest and during dynamic exercise. Previously suspected muscle tissue relative blood flow (rBF) baseline shift during extended measurement with DCS and DCS-Near infrared spectroscopy (NIRS) hybrid optical systems are verified, quantified, and resolved by redesign of optical probe and alteration in optical probe attachment methodology during 40 minute supine bed rest baseline measurements. We then translate previously developed occlusion techniques, whereby rBF and relative oxygen consumption rV O 2 are calibrated to initial resting absolute values by use of a venous occlusion (VO) and arterial occlusion (AO) protocol, respectively, to the lower leg (gastrocnemius) and these blood flows are cross validated at rest by strain gauge venous plethysmography (SGVP). Methods used to continuously observe 0.5Hz, 30% maximum voluntary isometric contraction (MVIC) plantar flexion exercise via dynamometer are adapted for our hybrid DCS-Imagent diffuse optical flow-oximeter in the medial gastrocnemius. We obtain healthy control muscle tissue hemodynamic profiles for key parameters BF, V O 2 , oxygen saturation (StO 2) , deoxyhemoglobin, oxyhemoglobin, and total hemoglobin concentrations ([Hb], [HbO 2 ], and THC respectively), as well as systemic mean arterial pressure (MAP) and pulse rate (PR), at rest, during VO/AO, during dynamic exercise and during 15 minute recovery periods. Next, we began investigation of muscle tissue hemodynamic disease states by performing a feasibility pilot study using limited numbers of controls and peripheral arterial disease (PAD) patients using the translated methods/techniques to determine the ability of our technology to assess differences in these populations.

Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of forearm muscle hemodynamics during handgrip exercises. The translation of these techniques from the forearm to the lower limb is the goal of this study as various diseases preferentially affect muscles in the lower extremity. This study adapted a hybrid near-infrared spectroscopy and diffuse correlation spectroscopy system with a gating algorithm to continuously quantify hemodynamic responses of medial gastrocnemius during plantar flexion exercises in 10 healthy subjects. The outcomes from optical measurement include oxy-, deoxy-, and total hemoglobin concentrations, blood oxygen saturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV̇O2). We calibrated rBF and rV̇O2 profiles with absolute baseline values of BF and V̇O2 obtained by venous and arterial occlusions, respectively. Results from this investigatio...

Purpose: The purpose of this study was to evaluate the thermal effects produced in meniscal tissue with different radiofrequency (RF) energy levels and exposure times using a bipolar device. Type of Study: An anatomic in vitro analysis of the thermal effects of an RF device. Methods: A specially designed jig was used to apply RF energy under a constant force to cadaveric menisci. Three different energy levels were applied for 4 different contact times. Results: The overall mean depth of thermal change was 547 m (range, 468 to 650 m). There were no significant differences or trends when contact time and energy were varied. Conclusions: These data suggest that increased contact times and energy outputs are not associated with increased thermal change in the meniscus. The submillimeter thermal denaturation was consistent with published reports using other thermal devices, such as laser.

Purpose: The purpose of this study was to evaluate the thermal effects produced in meniscal tissue with different radiofrequency (RF) energy levels and exposure times using a bipolar device. Type of Study: An anatomic in vitro analysis of the thermal effects of an RF device. Methods: A specially designed jig was used to apply RF energy under a constant force to cadaveric menisci. Three different energy levels were applied for 4 different contact times. Results: The overall mean depth of thermal change was 547 m (range, 468 to 650 m). There were no significant differences or trends when contact time and energy were varied. Conclusions: These data suggest that increased contact times and energy outputs are not associated with increased thermal change in the meniscus. The submillimeter thermal denaturation was consistent with published reports using other thermal devices, such as laser.

Background: Previous radiofrequency work has not rigidly controlled energy application to the articular cartilage, giving uncertain results published to date. Hypothesis: At minimal settings, radiofrequency probes cause cell death in measurable areas when applied to human articular cartilage.

Purpose: Currently, two different methods of applying radiofrequency (RF) energy (monopolar and bipolar) are available to the surgeon for thermal shortening of the shoulder capsule. The objective of this study was to investigate the temperature changes and the thermal conduction across the human inferior glenohumeral ligament (IGHL) during radiofrequency energy application. Methods: Thermistors were secured onto both the intra-articular and extra-articular surfaces of human IGHL. Monopolar RF energy and bipolar RF energy were delivered to the intra-articular surface at the manufacturer's recommended settings. Pre-treatment and post-treatment ligament lengths, widths, heating times, and temperatures were measured and compared. Results: For the monopolar devices, temperature spikes to 89°C were recorded for the set temperature of 67°C, averaging 77°C Ϯ 10°C. Temperatures across the ligament averaged 48°C Ϯ 3°C. For both devices, the IGHL became thicker with higher RF settings. Recorded temperatures decreased as distance increased from the point of application. Maximum temperatures occurred at least 6 to 7 seconds after cessation of energy application. Conclusions: The bipolar and monopolar devices had similar conduction times across the ligament, suggesting that this occurs by simple diffusion of heat. Bipolar and monopolar devices were equally efficacious for capsular shrinkage if the extent of the shortening is tightly defined. Clinical Relevance: The thermal probe should not rest in one position for an extended period of time during RF energy application because, as our study showed, the monitoring of temperature or the visualization of tissue change is not efficacious for determining the end point of thermal shrinkage of the shoulder capsule.

A new transducer capable ofdirect measurement of time-dependent loads in human lumbar facet joints was developed and tested. The transducer was comprised of a force-sensitive resistor (FSR) in series with a pressure-sensitive film. A wide range of experiments revealed the performance attributes and limitations of the FSR. The output signal of the FSR is actually sensitive to both force and area of contact independently. Therefore, a pressure-sensitive film was used to quantify the contact area. At least two transformation equations were calculated for each FSR corresponding to known contact areas. Each equation was a linearization of the log of the FSR output vs the log of the applied ramp loads. Coefficients of determination (CD) were calculated for small (21 mm*) and large (32 mm') contact areas, and were found to exceed 0.900 for all data. The average of nine cycles was nearly linear for some FSRs (CD of 0.999). FSR output signal and contact area were recorded in cadaveric lumbar facets under ramp load. The appropriate transformation equation was determined by a linear interpolation between benchmark equations based on the contact area measured in vitro. Facet force measurements compared well with those of other researchers. The transducer was found to be quite easy to use. Fig. 1. The FSR and ULC transducers.

We have characterized the relative efficacies of a number of protein crosslinking agents that have the potential for use in the crosslinking of proteinaceous matrices both in vitro and in vivo. The crosslinkers tested were; L-threose (LT), Genipin (GP), Methylglyoxal (MG), 1-ethyl-3-(3dimethylaminopropyl) carbodiimide hydrochloride (EDC), proanthrocyanidin (PA) and glutaraldehyde (GA). The relative effectiveness of the crosslinkers with regard to their saturating concentrations was: GA > PA > EDC > MG = GP >> LT. Most of the crosslinkers displayed a pH dependence and were more effective at more alkaline pH. At optimal pH and saturating conditions, the relative reaction rates of the crosslinkers were: PA = GA > EDC > GP > MG >> LT.

Treatment of pathological spinal discs in vivo by injection of protein crosslinking reagents to restore their mechanical properties is a new possible approach to the treatment of degenerative disc disease. In this study, the thermal stability of the collagen in disc annulus was measured by differential scanning calorimetry following treatment with six different crosslinking agents. The crosslinkers used were; L-threose (LT), genipin (GP), methylglyoxal (MG), 1-ethyl-3-(3dimethylaminopropyl) carbodiimide hydrochloride (EDC) glutaraldehyde (GA) and proanthrocyanidin (PA).

Minimally invasive surgical techniques have become routinely applied to the evaluation and treatment of patients with isolated diaphragmatic injuries due to penetrating trauma. The objective of the study was to compare the healing of diaphragm injuries as determined by macroscopic inspection, histologic appearance, and tensile strength following repair by open suturing, laparoscopic suturing, and laparoscopic stapling techniques in an animal model.

in vitro cytotoxicity studies in the presence of drug-loaded NSPs. MTT assay as well as fluorescent and confocal microscopy were performed to characterize the effect of the delivery system on bacterial cell growth. RESULTS: We successfully demonstrated the ability (1) to load various amounts of cefazolin and clindamycin into NSP; (2) to create polymer coatings affording a tunable and sustained release of chemotherapeutic drugs; (3) to demonstrate significant cytotoxicity of loaded particles to staph aureus in vitro compared to controls. CONCLUSIONS: We developed a delivery system based on biodegradable, biocompatable NSP loaded with cefazolin/clindamycin. The release of drugs is controlled through appropriate tailoring of surface chemistries. Administered to staph aureus in vitro, this delivery system induced significant bacterial kill and, when coupled with direct or targeted delivery to bone, shows therapeutic potential for the treatment and/or prevention of spinal infections.

Andriacchi performed a computer-simulated mathematical analysis showing that the rib cage enhances stability of the normal thoracic spine in flexion, rotation, lateral bending, and especially extension. He showed an increase of 27 per cent in flexion and of 132 percent in extension with the addition of the rib cage. Panjabi and White established criteria assessing stability in the thoracic spine by performing studies supporting the stabilizing role of the costovertebral joints. However, these experiments underestimated the role of the rib cage because the ribs were removed 3 cm lateral to the costovertebral joints. Recently, Oda et al. showed significant increases in the neutral zone in lateral bending and axial rotation after resection of the costovertebral joints and destruction of the rib cage. The limitation to this study was the use of canine specimens rather than human. There is no published study of biomechanical testing of human cadaveric specimens with the rib cage intact. PURPOSE: To determine the amount of stability the rib cage imparts to the thoracic spine and to show the amount of stability lost by a sternal fracture. STUDY DESIGN/SETTING: Specimens were tested using a biaxial material testing machine (MTS) synchronized with an opto-electronic three-dimensional motion measuring device (Opto-trak 3020). PATIENT SAMPLE: Ten fresh-frozen human cadaveric thoracic spines with the rib cage and sternum intact. OUTCOME MEASURES: Multidirectional flexibility of the whole thoracic spine was measured using the Optotrak 3020, an opto-electronic threedimensional motion measuring device. This machine uses three cameras to detect movement of multiplexed arrays of light emiting diodes (LEDs). An array attached to the MTS machine established the fixed coordinate axes. One array was attached to T1 by way of a rigid pin placed in the pedicle. With T12 rigidly fixed to the base of the MTS system, motion of the T1 array represented motion of the entire thoracic spine specimen.

Intervertebral disc and facet joints are the two primary load-bearing structures of the lumbar spine, and altered loading to these structures may be associated with frontal plane spinal deviations. To determine the load on the lumbar facet joint and intervertebral disc under simulated frontal plane pelvic obliquity combined loading, an in vitro biomechanical study was conducted. An in vitro biomechanical study using a repeated-measures design was used to compare L4-L5 facet joint and intervertebral disc loading across pure moment and combined loading conditions. Eight fresh-frozen lumbosacral specimens were tested under five loading conditions: flexion/extension, lateral bending, axial rotation using pure moment bending (±10 Nm), and two additional tests investigating frontal plane pelvic obliquity and axial rotation (sacrum tilted left 5° and at 10° followed by a ±10-Nm rotation moment). Three-dimensional kinematics, facet load, and intradiscal pressures were recorded from the L4-L...

Degradation of genipin (GP), a low toxicity natural protein crosslinking agent, in aqueous solution was monitored by HPLC at various pH levels. Degradation of GP was consistent with a mechanism consisting of a first order reaction with a reversible first step. Formation of the intermediate was slowest at more neutral pHs while formation of the irreversible product was correlated to increasing alkalinity. Degradation at all pHs was enhanced by the presence of phosphate ions. Degradation of GP most likely proceeds via the reversible opening of the dihydropyran ring by water followed by irreversible polymerization of the intermediate. Degraded solutions containing no detectable GP or intermediate, however, are still capable of crosslinking proteins.