Transgluteal Approach for Drainage of Obturator Internus Abscess in Pediatric Patients.

BACKGROUND: Of the locations of peripelvic pyomyositis, infection of the obturator musculature poses a difficult challenge for operative drainage. The anatomic location of the obturator muscles, especially the obturator internus, complicates operative debridement as the surgical approach must safely bypass a large number of neurovascular structures. Realizing the challenges and risks of approaches to the obturator musculature, the purpose of our study was to review a novel, yet simple, posterior approach to the obturator internus. METHODS: We reviewed a case series of children (age 0 to 18 y), who presented to our institution with obturator internus pyomyositis. The patients' demographics, vital signs, laboratory data, and radiographic findings from the initial evaluation were reviewed. Blood and intraoperative culture results were collected. Duration of symptoms and length of hospital stay were also reviewed. Cases of suspected obturator internus abscess were confirmed by magnetic resonance imaging of the pelvis. All patients in this study who met the operative indications were debrided using the posterior transgluteal approach. RESULTS: Five patients were identified who met criteria for isolated obturator internus pyomyositis. Four out of the 5 patients met operative indications and underwent drainage through a transgluteal approach. One patient responded well to antibiotic treatment; therefore, no surgery was indicated. Purulence was expressed in all 4 operative cases. Hospital length of stay ranged from 6 to 14 days. All patients were treated with an IV antibiotic course for 3 to 6 weeks. All patients returned to normal function and activity levels. There were no surgical complications. CONCLUSIONS: This case series has reviewed a new technique for the drainage of an isolated obturator internus abscess. The transgluteal posterior approach is a simple approach that is performed through a single incision with minimal soft-tissue dissection. It avoids the risks and challenges posed by other approaches. Most importantly, our case series, although small, in our experience, has shown that it is a safe and effective approach for drainage of obturator internus abscess. LEVEL OF EVIDENCE: Level IV.

High-output LED-based light engine for profile lighting fixtures with high color uniformity using freeform reflectors.

In the stage lighting and entertainment market, light engines (LEs) for lighting fixtures are often based on high-intensity discharge (HID) bulbs. Switching to LED-based light engines gives possibilities for fast switching, additive color mixing, a longer lifetime, and potentially, more energy-efficient systems. The lumen output of a single LED is still not sufficient to replace an HID source in high-output profile fixtures, but combining multiple LEDs can create an LE with a similar output, but with added complexity. This paper presents the results of modeling and testing such a light engine. Custom ray-tracing software was used to design a high-output red, green and blue LED-based light engine with twelve CBT-90 LEDs using a dual-reflector principle. The simulated optical system efficiency was 0.626 with a perfect (R=1) reflector coating for light delivered on a target surface through the entire optical system. A profile lighting fixture prototype was created, and provided an output of 6744 lumen and an efficiency of 0.412. The lower efficiency was mainly due to a non-optimal reflector coating, and the optimized design is expected to reach a significantly higher efficiency.

Compact lens with circular spot profile for square die LEDs in multi-LED projectors.

In the stage illumination industry, LED technology is promising both in terms of energy use and novel features, but it also has inherent issues. This paper presents a solution to the poor color homogeneity arising when multiple rectangular images formed from LED dies are combined into a circular spot profile. Using ray tracing, a nonrotationally symmetric collimating lens was optimized to round off such die images. The result is a high-output lens with an almost perfectly circular spot. In a simulated red green blue color mixing projector with seven LEDs, the lens reduced measurable color inhomogeneity by ≈24.1%, with a 5.3% luminous gain, compared to the best rotationally symmetric benchmark lens.

Use of heterotrophic CO2 assimilation as a measure of metabolic activity in planktonic and sessile bacteria.

We have examined whether assimilation of CO2 can be used as a measure of metabolic activity in planktonic and sessile heterotrophic bacteria. CO2 assimilation by environmental samples and pure cultures of heterotrophic bacteria was studied using 14CO2 and 13CO2 as tracers. Heterotrophic growth on complex organic substrates resulted in assimilation of CO2 into cell biomass by activated sludge, drinking water biofilm, and pure cultures of Escherichia coli ATCC 25922, Es. coli ATCC 13706, Rhodococcus ruber, Burkholderia sp., Bacillus circulans, Pseudomonas putida, Pseudomonas stutzeri, and Pseudomonas aeruginosa. Analysis of 13C-labelled phospholipid fatty acids (PLFAs) confirmed that heterotrophic bacteria may assimilate 13CO2 into cell macromolecules such as membrane lipids. All major PLFAs extracted from activated sludge and drinking water biofilm samples were enriched in 13C after incubation with CO2. Between 1.4% and 6.5% of the biomass produced by cultures of P. putida and a drinking water biofilm during growth in complex media was apparently derived from assimilation of CO2. Resting cells assimilated less CO2 compared to actively growing cells, and CO2 assimilation activity correlated with the amount of biomass produced during heterotrophic growth. The 14CO2 assimilation assay was evaluated as a tool to examine inhibitory effects of biocides on planktonic and sessile heterotrophs (biofilms). On the basis of 14CO2 assimilation activity, the minimum inhibitory concentration (MIC) of benzalkonium chloride was estimated to 21.1 and 127.2 mg l(-1) for planktonic and biofilm samples, respectively. The results indicate that assimilation of isotopically labelled CO2 can be used as a relatively simple measure of metabolic activity in heterotrophic bacteria. CO2 assimilation assays may be used to study the effects of antimicrobial agents on growth and survival of planktonic and sessile heterotrophic organisms.

Cooling vest worn during active warm-up improves 5-km run performance in the heat.

We investigated whether a cooling vest worn during an active warm-up enhances 5-km run time in the heat. Seventeen competitive runners (9 men, maximal oxygen uptake = 66.7 +/- 5.9 ml x kg(-1) x min(-1); 8 women, maximal oxygen uptake = 58.0 +/- 3.2 ml x kg(-1) x min(-1)) completed two simulated 5-km runs on a treadmill after a 38-min active warm-up during which they wore either a T-shirt (C) or a vest filled with ice (V) in a hot, humid environment (32 degrees C, 50% relative humidity). Wearing the cooling vest during warm-up significantly (P < 0.05) blunted increases in body temperature, heart rate (HR), and perception of thermal discomfort during warm-up compared with control. At the start of the 5-km run, esophageal, rectal, mean skin, and mean body temperatures averaged 0.3, 0.2, 1.8, and 0.4 degrees C lower; HR averaged 11 beats/min lower; and perception of thermal discomfort (5-point scale) averaged 0.6 point lower in V than C. Most of these differences were eliminated during the first 3.2 km of the run, and these variables were not different at the end. The 5-km run time was significantly lower (P < 0.05) by 13 s in V than C, with a faster pace most evident during the last two-thirds of the run. We conclude that a cooling vest worn during active warm-up by track athletes enhances 5-km run performance in the heat. Reduced thermal and cardiovascular strain and perception of thermal discomfort in the early portion of the run appear to permit a faster pace later in the run.