Effect of ultrasonographically guided axillary nerve block combined with suprascapular nerve block in arthroscopic rotator cuff repair: a randomized controlled trial.

PURPOSE: The aim of this study was to compare the results of ultrasonographically guided axillary nerve block (ANB) combined with suprascapular nerve block (SSNB) with those of SSNB alone on postoperative pain and satisfaction within the first 48 hours after arthroscopic rotator cuff repair. METHODS: Forty-two patients with rotator cuff tears who had undergone arthroscopic rotator cuff repair were enrolled in this study. Among them, 21 patients were randomly allocated to group 1 and received both SSNB and ANB with 10 mL ropivacaine. The other 21 patients were allocated to group 2 and received SSNB with 10 mL 0.75% ropivacaine and ANB with 10 mL saline. Visual analog scale (VAS) pain score, patient satisfaction (SAT), and lateral pain index (LPI) was checked at 1, 3, 6, 12, 18, 24, 36, and 48 hours postoperatively. RESULTS: Group 1 showed a significantly lower mean VAS score at postoperative 1, 3, 6, 12, 18, and 24 hours compared with group 2 (5.1 < 7.6, 4.4 < 6.3, 3.7 < 5.3, 3.2 < 4.5, 2.7 < 4.0, and 2.7 < 3.4, respectively). A significantly high mean SAT and low mean LPI was observed in group 1 at postoperative 1, 3, 6, 12, 18, 24, and 36 hours (4.9 > 2.4, 5.9 > 3.7, 6.3 > 5.0, 6.8 > 5.7, 7.3 > 6.2, 7.5 > 6.6, and 7.7 > 7.0, respectively), (1.1 < 3.0, 0.8 < 2.5, 0.7 < 2.0, 0.7 < 1.6, 0.6 < 1.3, 0.6 < 1.0, and 0.4 < 0.7, respectively). The frequency of rebound pain decreased in group 1 compared with group 2 (P = .032). In addition, rebound phenomenon showed a correlation with ANB on univariate logistic regression (P = .034; odds ratio, 0.246). CONCLUSIONS: Ultrasonographically guided ANB combined with SSNB in arthroscopic rotator cuff repair showed an improved mean VAS in the first 24 hours after surgery compared with SSNB alone. The mean SAT and LPI of the combined blocks were better than those of the single block within the first 36 hours. Ultrasonographically guided ANB combined with SSNB also decreased the rebound phenomenon. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

Single-molecule analysis and lifetime estimates of heterogeneous low-count-rate time-correlated fluorescence data.

We demonstrate a proof of concept for detecting heterogeneities and estimating lifetimes in time-correlated single-photon-counting (TCSPC) data when photon counts per molecule are low. In this approach photons are classified as either prompt or delayed according to their arrival times relative to an arbitrarily chosen time gate. Under conditions in which the maximum likelihood (ML) methods fail to distinguish between heterogeneous and homogeneous data sets, histograms of the number of prompt photons from many molecules are analyzed to identify heterogeneities, estimate the contributing fluorescence lifetimes, and determine the relative amplitudes of the fluorescence, scatter, and background components of the signal. The uncertainty of the lifetime estimate is calculated to be larger than but comparable to the uncertainty in ML estimates of single lifetime data made with similar total photon counts. Increased uncertainty and systematic errors in lifetime estimates are observed when the temporal profile of the lifetime decay is similar to either the background or scatter signals, primarily due to error in estimating the amplitudes of the various signal components. Unlike ML methods, which can fail to converge on a solution for a given molecule, this approach does not discard any data, thus reducing the potential for introducing a bias into the results.

Two-photon excitation of potentiometric probes enables optical recording of action potentials from mammalian nerve terminals in situ.

We report the first optical recordings of action potentials, in single trials, from one or a few (approximately 1-2 microm) mammalian nerve terminals in an intact in vitro preparation, the mouse neurohypophysis. The measurements used two-photon excitation along the "blue" edge of the two-photon absorption spectrum of di-3-ANEPPDHQ (a fluorescent voltage-sensitive naphthyl styryl-pyridinium dye), and epifluorescence detection, a configuration that is critical for noninvasive recording of electrical activity from intact brains. Single-trial recordings of action potentials exhibited signal-to-noise ratios of approximately 5:1 and fractional fluorescence changes of up to approximately 10%. This method, by virtue of its optical sectioning capability, deep tissue penetration, and efficient epifluorescence detection, offers clear advantages over linear, as well as other nonlinear optical techniques used to monitor voltage changes in localized neuronal regions, and provides an alternative to invasive electrode arrays for studying neuronal systems in vivo.

Impedance characterization of a piezoelectric immunosensor part II: Salmonella typhimurium detection using magnetic enhancement.

This study investigated the usefulness and characteristics of a 5-MHz quartz crystal resonator as a sensor of biological pathogens such as Salmonella typhimurium. An impedance analyzer measured the impedance behavior of the oscillating quartz crystal exposed to various concentrations of Salmonella (10(2)-10(8) cells per ml). The Salmonella cells were captured by antibody-coated paramagnetic microspheres, and then these complexes were moved magnetically to the sensing quartz and were captured by antibodies immobilized on the crystal surface. The response of the crystal was expressed in terms of equivalent circuit parameters. The motional inductance and the motional resistance increased as a function of the concentration of Salmonella. The viscous damping was the main contributor to the resistance and the inductance in a liquid environment. The load resistance was the most effective and sensitive circuit parameter. A magnetic force was a useful method to collect the complexes of Salmonella-microspheres on the crystal surface and enhance the response of the sensor. In this system, the detection limit, based on resistance monitoring, was about 10(3) cells per ml.

Impedance characterization of a piezoelectric immunosensor. Part I: antibody coating and buffer solution.

This study investigated the impedance characteristics of a 5 MHz quartz crystal resonator oscillating in a thickness-shear mode for utilization as a biosensor. An impedance analyzer measured the impedance of the quartz crystal, which determined all mechanical properties of the oscillating quartz and its immediate environment. In this study, the impedance behavior of the oscillating crystal was characterized in air, in potassium phosphate buffer solution, and with immobilization of antibodies using protein-A. The potassium phosphate buffer behaved like a Newtonian liquid. The series resonance frequency shifted down about 900 Hz on contact with the buffer. An immobilized-antibody layer on the quartz surface behaved like a rigid mass when immersed in the buffer solution. The impedance curve following immobilization of antibodies was shifted down in frequency by about 200 Hz compared with its value when the bare crystal was immersed in the buffer solution.