Acute Physiological Responses to Moderate-Intensity Continuous, High-Intensity Interval, and Variable-Intensity Intermittent Exercise.

Purpose: This study examined acute physiological responses to moderate-intensity continuous exercise (MICE), variable-intensity intermittent exercise (VIIE), and high-intensity interval exercise (HIIE) protocol, matched for total work output in healthy adults (n = 8, age = 25.1 ± 6.0 yrs). Methods: Three experimental trials were completed in a random order. MICE was continuous exercise at 40% of peak work rate (WRpeak). VIIE consisted of sixteen 10-sec bursts at 120% WRpeak, sixteen 20-sec bursts at 60% WRpeak and recovery at 20% WRpeak interspersed throughout the protocol. HIIE consisted of eight intervals of 2 minutes at 70% WRpeak and 1 minute at 20% WRpeak. Oxygen consumption during work-intervals and time within moderate and vigorous-intensity zones determined the magnitude and duration of physiological stresses. Perceptual responses were measured by affective response and post-exercise enjoyment (PACES). Repeated-measure ANOVAs analyzed differences between trials. Statistical significance was established if p ≤ 0.05. Results: Oxygen consumption during work-intervals in VIIE was greater than MICE, but less than HIIE. VIIE and HIIE had similar duration within vigorous-intensity zone (11.1 ± 3.5 min vs. 13.5 ± 1.3 min); both were greater than MICE (4.9 ± 1.1 min). The time spent in the moderate-intensity zone was different between all trials (VIIE = 11.1 ± 2.0 min; MICE = 17.4 ± 5.2 min; HIIE = 4.9 ± 0.4 min). Affective responses were similar among all trials. Post-exercise enjoyment was greater in VIIE than HIIE; both were not different from MICE. Conclusion: These results suggests the VIIE paradigm could be a viable alternative to HIIE and MICE protocols.

Thermal denaturation of wild type and mutant recombinant acetylcholinesterase from amphioxus: effects of the temperature of in vitro expression and of reversible inhibitors.

We have studied the thermal inactivation at 37 degrees C of wild type and mutant ChE2 (C310A, F312I, C466A, C310A/F312I, and C310A/C466A) from amphioxus (Branchiostoma floridae) expressed in vitro in COS-7 monkey cells under three sets of conditions: 30 degrees C for 48 h, 30 degrees C for 24 h and 37 degrees C for 24 h, and 37 degrees C for 48 h. We found biphasic denaturation curves for all enzymes and conditions, except wild type and C310A ChE2 expressed at 30 degrees C for 48 h. Generally, single mutants are more unstable than wild type, and the double mutants are even more unstable. We propose a model involving stable and unstable conformations of the enzymes to explain these results, and we discuss the implications of the model. We also found a correlation between the melting temperature of the ChEs and the rates at which they denature at 37 degrees C, with the denaturation of the unstable conformation dominating the relationship. Reversible cholinergic inhibitors protect the ChEs from thermal denaturation, and in some cases produce monophasic denaturation curves; we also propose a model to explain this stabilization.

Inactivation of an invertebrate acetylcholinesterase by sulfhydryl reagents: the roles of two cysteines in the catalytic gorge of the enzyme.

We have used site-directed mutagenesis and molecular modeling to investigate the inactivation of an invertebrate acetylcholinesterase (AChE), ChE2 from amphioxus, by the sulfhydryl reagents 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and N-ethylmaleimide (NEM), creating various mutants, including C310A and C466A, and the double mutants C310A/C466A and C310A/F312I, to assess the relative roles of the two cysteines and a proposal that the increased rate of inactivation in the F312I mutant is due to increased access to Cys310. Our results suggest that both cysteines may be involved in inactivation by sulfhydryl reagents, but that the cysteine in the vicinity of the acyl pocket is more accessible. We speculate that the inactivation of aphid AChEs by sulfhydryl reagents is due to the presence of a cysteine homologous to Cys310. We also investigated the effects of various reversible cholinergic ligands, which bind to different subsites of the active site of the enzyme, on the rate of inactivation by DTNB of wild type ChE2 and ChE2 F312I. For the most part the inhibitors protect the enzymes from inactivation by DTNB. However, a notable exception is the peripheral site ligand propidium, which accelerates inactivation in the wild type ChE2, but retards inactivation in the F312I mutant. We propose that these opposing effects are the result of an altered allosteric signal transduction mechanism in the F312I mutant compared to the wild type ChE2.

High resolution optical frequency domain reflectometry for characterization of components and assemblies.

We describe a technique for polarization sensitive optical frequency domain reflectometry (OFDR) that achieves 22 micrometer two-point spatial resolution over 35 meters of optical length with -97 dB sensitivity in a single measurement taking only seconds. We demonstrate OFDR's versatility in both time- and frequency-domain metrology by analyzing a fiber Bragg grating (FBG) in both the spectral and impulse response domains. We also demonstrate how a polarization diversity receiver can be used in an OFDR system to track changes in the polarization state of light propagating through a birefringent component.

Gastrointestinal symptom improvement after Roux-en-Y gastric bypass: long-term analysis.

BACKGROUND: Obese patients have a multitude of gastrointestinal symptoms that differ from their nonobese counterparts. The published data remain scant on changes in gastrointestinal symptoms among this cohort before and after Roux-en-Y gastric bypass (RYGB). The aim of this study was to quantify these symptoms and understand the changes that occur after bariatric surgery. METHODS: A total of 1724 gastrointestinal symptom surveys were prospectively administered to 763 consecutive patients who underwent laparoscopic RYGB. The patients rated each symptom on a 0-100-mm Liekert scale: 0, absence of symptoms; 33, occasional occurrence; 67, frequent occurrence; 100, continuous. The surveys were administered preoperatively and yearly thereafter. The data are presented as the mean + or - standard error of the mean. RESULTS: Of the 763 patients, 137 were black, 610 were white, and 16 were Hispanic; 83% were women and 17% were men. Their age was 40.8 + or - 0.34 years. The body mass index was 48.4 + or - 0.27 kg/m(2). The American Society of Anesthesiologists class was 2 for 31%, 3 for 68%, and 4 for 1%. Of the 763 patients, 63% underwent short-limb RYGB and 37% underwent long-limb RYGB. The preoperative symptom rating was as follows: abdominal pain, 24.3 + or - 0.7; heartburn, 41.0 + or - 0.8; acid regurgitation, 30.9 + or - 0.9; gnawing epigastric sensation, 26.5 + or - 0.9; nausea/vomiting, 18.8 + or - 0.7; borborygmus, 26.2 + or - 0.8; abdominal distension, 30.3 + or - 0.9; eructation, 28.0 + or - 0.8; increased flatus, 38.9 + or - 0.8; decreased passage of stool, 14.8 + or - 0.8; increased passage of stool, 16.4 + or - 0.7; loose stools, 22.1 + or - 0.8; hard stools, 20.5 + or - 0.9; urgent need for defecation, 23.2 + or - 0.8; incomplete evacuation, 22.2 + or - 0.8; difficulty falling asleep, 42.0 + or - 1.1; insomnia, 38.4 + or - 1; feeling rested, 60.1 + or - 1; and difficulty swallowing, 13.5 + or - 0.67. At 1, 2, 3, 4, and 5 years after RYGB, 99.5% 84.2%, 68.4%, 57.9% and 47.4% of these symptoms had improved significantly (P < .05). CONCLUSION: Laparoscopic RYGB significantly improves the gastrointestinal symptoms experienced by morbidly obese patients without adversely affecting any of the measured parameters. This improvement in symptoms proved durable in the long term.

Optical vector network analyzer for single-scan measurements of loss, group delay, and polarization mode dispersion.

We present a method for measuring the complete linear response, including amplitude, phase, and polarization, of a fiber-optic component or assembly that requires only a single scan of a tunable laser source. The method employs polarization-diverse swept-wavelength interferometry to measure the matrix transfer function of a device under test. We outline the theory of operation to establish how the transfer function is obtained. We demonstrate the enhanced accuracy, precision, and dynamic range of the technique through measurements of several components.