Load carriage physiology in normoxia and hypoxia.

PURPOSE: To determine the effects of load carriage in normoxia and normobaric hypoxia on ventilatory responses, hemodynamics, tissue oxygenation, and metabolism. METHODS: Healthy males (n = 12) completed 3 randomly ordered baseline graded exercise tests in the following conditions: (1) unloaded normoxic (U: FIO2 = 20.93%), (2) loaded (~ 30 kg) normoxic (LN), and (3) loaded hypoxic simulating ~ 3650 m (LH: FIO2 = ~ 13%). Thereafter, experimental exercise trials were completed in quasi-randomized order (i.e., U completed first) consisting of 3 × 10 min of walking (separated by 5 min seated rest) with stages matched with the U condition (in ascending order) for relative intensity, absolute oxygen consumption ([VO2]; 1.7 L min-1), and walking speed (1.45 ± 0.15 m s-1). RESULTS: Load carriage increased perceived exertion and reduced VO2max (LN: - 7%; LH: - 32%; p < 0.05). At matched VO2, stroke volume and tidal volume were reduced and maintained with LN and LH vs. U, respectively (p < 0.05). Increases in cardiac output and minute ventilation at matched VO2 (with LH) and speed (with LN and LH), were primarily accomplished via increases in heart rate and breathing frequency (p < 0.05). Cerebral oxygenated hemoglobin (O2HHb) was increased at all intensities with LN, but deoxygenated hemoglobin and total hemoglobin were increased with LH (p < 0.05). Muscle oxygen kinetics and substrate utilization were similar between LN and U, but LH increased CHO dependence and reduced muscle O2HHb at matched speed (p < 0.05). CONCLUSION: Load carriage reduces cardiorespiratory efficiency and increases physiological strain, particularly in hypoxic environments. Potential load carriage-induced alterations in cerebral blood flow may increase the risk for altitude illnesses and requires further study.

Cold Ambient Temperature Does Not Alter Subcutaneous Abdominal Adipose Tissue Lipolysis and Blood Flow in Endurance-Trained Cyclists.

This study sought to investigate the effect of cold ambient temperature on subcutaneous abdominal adipose tissue (SCAAT) lipolysis and blood flow during steady-state endurance exercise in endurance-trained cyclists. Ten males (age: 23 ± 3 years; peak oxygen consumption: 60.60 ± 4.84 ml·kg-1·min-1; body fat: 18.4% ± 3.5%) participated in baseline lactate threshold (LT) and peak oxygen consumption testing, two familiarization trials, and two experimental trials. Experimental trials consisted of cycling in COLD (3 °C; 42% relative humidity) and neutral (NEU; 19 °C; 39% relative humidity) temperatures. Exercise consisted of 25 min cycling at 70% LT and 25 min at 90% LT. In situ SCAAT lipolysis and blood flow were measured via microdialysis. Heart rate, core temperature, carbohydrate and fat oxidation, blood glucose, and blood lactate were also measured. Heart rate, core temperature, oxygen consumption, and blood lactate increased with exercise but were not different between COLD and NEU. SCAAT blood flow did not change from rest to exercise or between COLD and NEU. Interstitial glycerol increased during exercise (p < .001) with no difference between COLD and NEU. Fat oxidation increased (p < .001) at the onset of exercise and remained elevated thereafter with no difference between COLD and NEU. Carbohydrate oxidation increased with increasing exercise intensity and was greater at 70% LT in COLD compared to NEU (p = .030). No differences were observed between conditions for any other variable. Cycling exercise increased SCAAT lipolysis but not blood flow. Ambient temperature did not alter SCAAT metabolism, SCAAT blood flow, or fat oxidation in well-trained cyclists, though cold exposure increased whole-body carbohydrate oxidation at lower exercise intensities.

Dietary nitrate supplementation enhances heavy load carriage performance in military cadets.

PURPOSE: To determine the effects of dietary nitrate (NO3-) supplementation on physiological responses, cognitive function, and performance during heavy load carriage in military cadets. METHODS: Ten healthy males (81.0 ± 6.5 kg; 180.0 ± 4.5 cm; 56.2 ± 3.7 ml·kg·min-1 VO2max) consumed 140 mL·d-1 of beetroot juice (BRJ; 12.8 mmol NO3-) or placebo (PL) for six d preceding an exercise trial, which consisted of 45 min of load carriage (55% body mass) at 4.83 km·h-1 and 1.5% grade, followed by a 1.6-km time-trial (TT) at 4% grade. Gas exchange, heart rate, and perceptual responses were assessed during constant-load exercise and the TT. Cognitive function was assessed immediately prior to, during, and post-exercise via the psychomotor vigilance test (PVT). RESULTS: Post-TT HR (188 ± 7.1 vs. 185 ± 7.4; d = 0.40; p = 0.03), mean tidal volume (2.15 ± 0.27 vs. 2.04 ± 0.23; p = 0.02; d = 0.47), and performance (770.9 ± 78.2 s vs. 809.8 ± 61.4 s; p = 0.03; d = 0.63) were increased during the TT with BRJ versus PL. There were no effects of BRJ on constant-load gas exchange or perceptual responses, and cognitive function was unchanged at all time points. CONCLUSION: BRJ supplementation improves heavy load carriage performance in military cadets possibly as a result of attenuated respiratory muscle fatigue, rather than enhanced exercise economy.

Career-Best Changes in Body Mass and Physical Fitness Test Performance Among Division 1 College Football Players Encompassing 28 Years at the Same Institution.

ABSTRACT: Baur, DA, Johnson, JB, Giron-Molina, LG, Caterisano, M, Shaner, C, Caterisano, A, and Gentry, M. Career-best changes in body mass and physical fitness test performance among Division 1 college football players encompassing 28 years at the same institution. J Strength Cond Res 37(4): 806-815, 2023-Understanding typical changes induced by collegiate American football strength and conditioning programs is essential for optimizing program design and athletic development. The purpose of the study was to evaluate body mass and physical fitness test performance changes at a Division 1 program with 28 years of coaching stability. Initial and personal record results were collected from 1,102 players who were subdivided into 3 position groups: combination players (COMBO), skill players (SKILL), and line of scrimmage players. Players followed a linear periodized training program with biannual body mass and performance testing. Tested variables included body mass, strength (bench press, back squat, and front squat), impulse (power clean, push jerk, and vertical jump [VJ]), and speed/agility (10-yard dash [10YD], 40-yard dash, and 20-yard shuttle). The fixed effect of time and position group on the dependent variables was assessed using linear mixed models. If appropriate, post hoc tests using the estimated marginal means were used to evaluate the source of any significant effects. Significance was accepted as p < 0.05. Normative values were produced by descriptive statistics (i.e., weighted means). All players and position groups increased/improved across all tested variables ( p < 0.05). Improvements were 8.2%, 11.9-18.3%, 13.5-17.5%, and 3.6-6.0% for body mass, strength, impulse, and speed/agility, respectively. Line of scrimmage improvements were absolutely larger across most tested variables and relatively larger for back squat, VJ, and 10YD vs. SKILL and with VJ vs. COMBO/SKILL ( p < 0.05). These results reveal typical expectations for 4-5 years performance improvements and that position group differences in trainability may influence game readiness and training needs.

Carbohydrate supplementation: a critical review of recent innovations.

PURPOSE: To critically examine the research on novel supplements and strategies designed to enhance carbohydrate delivery and/or availability. METHODS: Narrative review. RESULTS: Available data would suggest that there are varying levels of effectiveness based on the supplement/supplementation strategy in question and mechanism of action. Novel carbohydrate supplements including multiple transportable carbohydrate (MTC), modified carbohydrate (MC), and hydrogels (HGEL) have been generally effective at modifying gastric emptying and/or intestinal absorption. Moreover, these effects often correlate with altered fuel utilization patterns and/or glycogen storage. Nevertheless, performance effects differ widely based on supplement and study design. MTC consistently enhances performance, but the magnitude of the effect is yet to be fully elucidated. MC and HGEL seem unlikely to be beneficial when compared to supplementation strategies that align with current sport nutrition recommendations. Combining carbohydrate with other ergogenic substances may, in some cases, result in additive or synergistic effects on metabolism and/or performance; however, data are often lacking and results vary based on the quantity, timing, and inter-individual responses to different treatments. Altering dietary carbohydrate intake likely influences absorption, oxidation, and and/or storage of acutely ingested carbohydrate, but how this affects the ergogenicity of carbohydrate is still mostly unknown. CONCLUSIONS: In conclusion, novel carbohydrate supplements and strategies alter carbohydrate delivery through various mechanisms. However, more research is needed to determine if/when interventions are ergogenic based on different contexts, populations, and applications.

Ultra-endurance triathlon performance and markers of whole-body and gut-specific inflammation.

PURPOSE: To examine the influence of the Ultraman Florida triathlon (3 days of non-continuous racing; stage 1: 10 km swim and 144.8 km cycle; stage 2: 275.4 km cycle; stage 3: 84.4 km run) on circulating plasma concentrations of whole-body (C-reactive protein (CRP), interleukin (IL)-6 (IL-6), and IL-10 and surrogate gut-specific inflammatory markers (IL-17 and IL-23), and determine whether these variables are associated with performance. METHODS: Eighteen triathletes (N = 18; 15 men, 3 women; age: 37 ± 8 yrs) were evaluated at baseline and post-race for circulating concentrations of CRP, IL-6, IL-10, IL-17, and IL-23. Blood samples were drawn two days prior to stage 1 (1600 h) and one day after stage 3 (1200 h). RESULTS: Plasma CRP significantly increased from baseline (1985.8 ± 5962.3 ng/mL) to post-race (27,013.9 ± 12,888.8 ng/mL, p < 0.001, 13-fold increase). Both plasma IL-6 and IL-10 did not significantly change from baseline to post-race. Baseline and post-race concentrations of IL-17 and IL-23 were below detectable limits. Pearson's correlation between mean finish time and post-race IL-10 revealed a significant positive correlation (r = 0.54, p < 0.05). CONCLUSIONS: Our results suggest that cytokines such as IL-6 and IL-10 involved in the inflammatory response return to near-baseline concentrations rapidly even after ultra-endurance events of extreme duration. The absence of IL-17 and IL-23 may suggest positive gut adaptations from ultra-endurance training. A significant positive correlation between post-race IL-10 concentrations and mean finish time may indicate that a relationship between anti-inflammatory responses and performance exists.

Model-assisted process characterization and validation for a continuous two-column protein A capture process.

In this study we introduce three process characterization approaches toward validation of continuous twin-column capture chromatography (CaptureSMB), referred to as "standard," "model assisted," and "hybrid." They are all based on a traditional risk-based approach, using process description, risk analysis, design-of-experiments (DoE), and statistical analysis as essential elements. The first approach, the "standard" approach uses a traditional experimental DoE to explore the design space of the high-ranked process parameters for the continuous process. Due to the larger number of process parameters in the continuous process, the DoE is extensive and includes a larger number of experiments than an equivalent DoE of a single column batch capture process. In the investigated case, many of the operating conditions were practically infeasible, indicating that the design space boundaries had been chosen inappropriately. To reduce experimental burden and at the same time enhance process understanding, an alternative "model assisted" approach was developed in parallel, employing a chromatographic process model to substitute experimental runs by computer simulations. Using the "model assisted" approach only experimental conditions that were feasible in terms of process yield constraints (>90%) were considered for statistical analysis. The "model assisted" approach included an optimization part that identified potential boundaries of the design space automatically. In summary, the "model assisted" approach contributed to increased process understanding compared to the "standard" approach. In this study, a "hybrid" approach was also used containing the general concepts of the "standard" approach but substituting a number of its experiments by computer simulations. The presented approaches contain essential elements of the Food and Drug Administration's process validation guideline.

Carbohydrate hydrogel beverage provides no additional cycling performance benefit versus carbohydrate alone.

PURPOSE: This study examined the effects of a novel maltodextrin-fructose hydrogel supplement (MF-H) on cycling performance and gastrointestinal distress symptoms. METHODS: Nine endurance-trained male cyclists (age = 26.1 ± 6.6, mass = 80.9 ± 10.4 kg, VO2max = 55.5 ± 3.6 mL·kg·min-1) completed three experimental trials consisting of a 98-min varied-intensity cycling protocol followed by a performance test of ten consecutive sprint intervals. In a cross-over design, subjects consumed 250 mL of a treatment beverage every 15 min of cycling. Treatments consisted of 78 g·hr-1 of either (a) MF-H, (b) isocaloric maltodextrin-fructose (ratio-matched 2:1; MF), and (c) isocaloric maltodextrin only (MD). RESULTS: There were no differences in average sprint power between treatments (MF-H, 284 ± 51 W; MF, 281 ± 46 W; and MD, 277 ± 48 W), or power output for any individual sprint. Subjective ratings of gastrointestinal distress symptoms (nausea, fullness, and abdominal cramping) increased significantly over time during the cycling trials, but few individuals exceeded moderate levels in any trial with no systematic differences in gastrointestinal discomfort symptoms observed between treatments. CONCLUSIONS: In conclusion, ingestion of a maltodextrin/fructose hydrogel beverage during high-intensity cycling does not improve gastrointestinal comfort or performance compared to MF or MD beverages.

Pre-sleep protein in casein supplement or whole-food form has no impact on resting energy expenditure or hunger in women.

The purpose of this study was to determine the effect of a whole-food protein (cottage cheese, CC) consumed before sleep on next-morning resting energy expenditure (REE), RER and appetite compared with an isoenergetic/isonitrogenous casein protein (CP) supplement and placebo (PL) in active women. In a beverage-blinded, randomised, cross-over design, ten active women (age, 23·1 (sd 1·9) years; body fat, 22·0 (sd 4·6) %) consumed pre-sleep CC (30 g of protein, 10 g of carbohydrate and 0 g of fat) or energy- and protein-matched liquid CP or PL (0 kJ). Participants arrived at 18.00 hours for an overnight stay in the laboratory. At 30-60 min before normal bed time (2 h post standard meal), participants consumed CC, CP or PL before measurement of REE. Upon waking (05.00-08.00 hours), REE was repeated and subjective appetite was recorded. Statistical analyses were conducted using repeated-measures ANOVA (SPSS). Significance was accepted at P≤0·05. There were no significant differences in acute REE (CC, 7217 (sd 1368); CP, 7188 (SD 895); PL, 7075 (sd 1108) kJ/d, P=0·95), acute RER (0·79 (sd 0·05), P=0·56), morning REE (CC, 5840 (sd 1225); CP, 5694 (sd 732); PL, 5991 (sd 903) kJ/d, P=0·79) or morning RER (0·77 (sd 0·03), P=0·52). Subjective measures of appetite were not different between groups. In active women, pre-sleep consumption of CC does not alter REE or RER more than a CP or PL beverage. These data suggest that the metabolic response from whole-food protein do not differ from the metabolic response of liquid protein.

Blood glucose kinetics and physiological changes in a type 1 diabetic finisher of the Ultraman triathlon: a case study.

PURPOSE: To investigate the blood glucose kinetics and physiological effects experienced by a type 1 diabetic (T1D) finisher of a 3-day, multi-stage ultra endurance triathlon consisting of a 10 km swim and 144.8 km bike (stage 1), a 275.4 km bike (stage 2), and an 84.4 km run (stage 3). METHODS: The athlete self-monitored blood glucose (SMBG) levels via fingerstick blood draw and hand-held glucometer. Researchers evaluated blood glucose kinetics via a continuous glucose monitoring device. The athlete maintained normal dietary and insulin patterns before, during and after competition daily. Weight and body composition were measured via bioelectrical impedance and select biomarkers were measured in blood. RESULTS: The athlete spent 73.0, 3.4, and 15.1% of during race time in a hyperglycemic state (≥130 mg dL-1) during stages 1, 2, and 3, respectively, and 0.0, 78.6, and 33.6% in a hypoglycemic state (≤80 mg dL-1). Nocturnal glycemic levels showed the athlete spent 86.1, 83.0, and 84.8% of sleep in a hyperglycemic state during nights 1, 2, and 3, respectively, and 9.0, 0.0, and 0.0% in a hypoglycemic state. From pre- to post-race, body weight (73.2 to 76.9 kg) and total body water increased (49.2-51.6 kg). In addition, there were dramatic increases in creatine kinase (271.7-9252.8 µ L-1), cortisol (137.1-270.2 pg mL-1), CRP (188.3-8046.9 ng mL-1), and aldosterone (449.1-1679.6 pg mL-1). CONCLUSIONS: It is possible for a T1D athlete to complete a multi-stage ultraendurance triathlon and maintain glycemic control using SMBG methods. In addition, a T1D athlete participating in an ultraendurance triathlon results in substantial changes in body composition, hormones, and muscle damage.

Fluid retention, muscle damage, and altered body composition at the Ultraman triathlon.

PURPOSE: The primary purpose of this investigation was to determine the effects of participation in a 3-day multistage ultraendurance triathlon (stage 1 = 10 km swim, 144.8 km bike; stage 2 = 275.4 km bike; stage 3 = 84.4 km run) on body mass and composition, hydration status, hormones, muscle damage, and blood glucose. METHODS: Eighteen triathletes (mean ± SD; age 41 ± 7.5 years; height 175 ± 9 cm; weight 73.5 ± 9.8 kg; male n = 14, female n = 4) were assessed before and after each stage of the race. Body mass and composition were measured via bioelectrical impedance, hydration status via urine specific gravity, hormones and muscle damage via venous blood draw, and blood glucose via fingerstick. RESULTS: Following the race, significant changes included reductions in body mass (qualified effect size: trivial), fat mass (moderate), and percent body fat (small); increases in percent total body water (moderate) and urine specific gravity (large); and unchanged absolute total body water and fat-free mass. There were also extremely large increases in creatine kinase, C-reactive protein, aldosterone and cortisol combined with reductions in testosterone (small) and the testosterone:cortisol ratio (moderate). There were associations between post-race aldosterone and total body water (r = -0.504) and changes in cortisol and fat-free mass (r = -0.536). Finally, blood glucose increased in a stepwise manner prior to each stage. CONCLUSIONS: Participation in Ultraman Florida leads to fluid retention and dramatic alterations in body composition, muscle health, hormones, and metabolism.

Cycling time trial performance may be impaired by whey protein and L-alanine intake during prolonged exercise.

Previous studies reported that adding protein (PRO) to carbohydrate (CHO) solutions enhances endurance performance. The ergogenic effect may be a function of additional protein/amino acid calories, but this has not been examined. In addition, although supplemental L-alanine (ALA) is readily oxidized during exercise, the subsequent impact on metabolism and prolonged endurance performance is unknown. The purpose of this investigation was to independently gauge the impact of whey PRO hydrolysate and ALA supplementation on performance and various physiological parameters. Eight cyclists (age: 22.3 ± 5.6 yr, weight: 70.0 ± 8.0 kg, VO2max: 59.4 ± 4.9 ml · kg(-1) · min(-1)) performed 120 min of constant-load cycling (55% of peak power) followed by a 30-km time trial (TT) under placebo (PLA), PRO, and ALA conditions. Magnitude-based qualitative inferences were applied to evaluate treatment differences and data are presented as percent difference between treatments ± 90% confidence limit. Both ALA (2.1 ± 2.7%) and PRO intake (-2.1 ± 2.2%) possibly harmed performance compared with PLA. Of interest, heart rate was possibly lower with ALA than PLA at 20- (-2.7 ± 3.4%) and 120-min (-1.7 ± 2.9%) of constant-load cycling and the serum interleukin-6 (IL-6) response to 120 min of cycling was likely attenuated with PRO compared with PLA (PLA, 6.6 ± 3.7 fold vs. PRO, 2.9 ± 1.8 fold). In addition, blood glucose levels were lower with PRO than PLA at 20- (-8.8 ± 2.3%; very likely) and 120-min (-4.9 ± 4.6%; likely) of constant-load cycling. Although ALA intake appears to lower HR and PRO ingestion dampens the IL-6 response to exercise, the ingestion of PRO (without CHO) or ALA does not enhance, and may actually impair, performance following prolonged cycling.

Sleep Duration Correlates With Performance in Ultra-Endurance Triathlon.

The relationship between sleep duration, sleep quality, and race completion time during each stage of a 3-day ultra-endurance triathlon (stage 1: 10-km swim, 146-km cycle; stage 2: 276-km cycle; and stage 3: 84.4-km run) was investigated. Seventeen triathletes partook in sleep analysis throughout the ultra-endurance multiday triathlon using an actigraphy wristband. The participants wore the band to record objective sleep outcomes for approximately 4 days (1-2 d prerace, 3 race days, and 1 d postrace), except while racing. The total sleep time (TST; prerace: 414.1 [95.3] min, prestage 1: 392.2 [138.3] min, prestage 2: 355.6 [62.5] min, and prestage 3: 299.7 [107.0] min) significantly decreased over time (P < .05). Significant Pearson moment-product correlations were found between TST and subsequent race-day performance for race stage 1 (r = -.577; P = .019) and stage 3 (r = -.546; P = .035), with further analysis revealing that TST explained 33% and 30% of the variation in performance for stages 1 and 3, respectively. During a 3-day ultra-endurance triathlon, the TST was reduced and had a significant negative correlation to exercise performance, indicating that sleep loss was associated with slower performances. Sleep onset latency, wake episodes, and sleep efficiency did not significantly change over the course of this investigation, which may stem from the close proximity of exercise to sleep.

A Bio-Physio-Psychological Investigation of Athletes' Burnout.

Purpose: Changes in biophysiological markers related to perceived burnout and self-comfort were tested in this study. Method: Forty-two student-athletes from middle and high school grades were evaluated for burnout, salivary cortisol levels, measures of arousal-related physiological markers (i.e., blood volume pulse; BVP), galvanic skin response (GSR), and respiratory rate, and self-comfort variables during the last two weeks of the season. Using self-comfort theory as its conceptual framework, we examined burnout through a conceptual model in which feeling of discomfort with the self was related to biophysiological markers affecting perceived burnout. The proposed model was tested by using a partial least squares structural equation modeling (PLS-SEM). Results: The main findings indicate that increased self-discomfort is significantly (p < .001) associated with increased salivary cortisol (ß = - 0.189) along with a significant (p = .050) decrease in GSR (ß = - 0.259). Increased salivary cortisol is significantly (p < .001) associated with increased burnout (ß = 0.242). Conclusion: The findings partially support the model and encourage further effort to capture the burnout syndrome through the integration of biological and psychological markers.

Shear Wave Elastography of the Plantar Fascia: Comparison between Patients with Plantar Fasciitis and Healthy Control Subjects.

BACKGROUND: The purpose of this study was to evaluate plantar fasciae of healthy subjects and patients with plantar fasciitis by shear wave velocity (SWV) and stiffness with correlation to B-Mode and color Doppler ultrasonography (CDUS) and to establish cut-off values. METHODS: This observational study was conducted with the approval of the Institutional Review Boards (IRBs) of our institution. 108 unilateral plantar fasciae were evaluated by including 87 consecutive patients (mean age 51.7; range: 29-82) (66 women and 21 men) with plantar fasciitis and 21 asymptomatic age matched healthy volunteers (mean age 47.3; range: 32-58) (15 women and 6 men). All patients were prospectively imaged between July 2018 and March 2019. B-mode US was used to measure thickness and CDUS to grade vascularity. SWE measurements were repeated 3 times and mean was used for statistical analysis. RESULTS: Mean SWV value in healthy subjects was 6.94 m/s and in patients 4.98 m/s with a mean stiffness value of 152.88 kPa and 93.54 kPa respectively (p < 0.001). For SWV a cut-off value of 6.16 m/s had a specificity of 80.95% and sensitivity of 79.31%. For stiffness a cut-off value of 125.57 kPa had a specificity of 80.95% and sensitivity of 80.46%. No correlation to CDUS was found. The mean thickness of healthy fascias was 3.3 mm (range 2.4-3.9) compared to 6.1 mm (range 2.0-22.0) in plantar fasciitis (p < 0.001) with no correlation to SWV or to stiffness (r² = 0.02, p = 0.06). CONCLUSION: SWE allows quantitative assessment of plantar fascia stiffness, which decreases in patients with plantar fasciitis. No correlation to the thickness of the plantar fascia was found, therefore it represents an independent factor for the diagnosis of plantar fasciitis and could be helpful in addition to thickness measurement in unclear cases.

Preparation of perfusive chromatographic materials via shear-induced reactive gelation.

A simple method for producing highly porous materials suitable for chromatographic applications is discussed. Starting from a dispersion of polymer core-shell nanoparticles (latex), micrometer sized clusters (100 µm) are produced via shear-induced Reactive Gelation. Thanks to their fractal structure, these aggregates exhibit highly porous structures, with pore size distribution ranging from 0.1 to several micrometers. The effect of different properties of the primary nanoparticles on the qualities of the final products is also investigated. Particle architecture, namely the ratio between the hard, highly crosslinked core, and the soft, poorly crosslinked shell, turned out to be the most important parameter to be tuned in order to obtain highly porous and mechanically resistant clusters. The final materials can be easily slurry-packed into conventional chromatographic columns. In comparison to other commercial stationary phases, these materials show not only much lower pressure drops at very high flow rates (i.e. <0.2 bar/cm at 6 mL/min), but also HETP profiles independent of fluid velocity when measured with tracers of sizes comparable to typical bio-macromolecules. Moreover, these materials, while offering the key advantage of being in a slurry form and thus easily packable and scalable, have a behavior that closely resembles that of monoliths, in which convective flow contribution dominates.

Adipose Lipolysis Unchanged by Preexercise Carbohydrate Regardless of Glycemic Index.

PURPOSE: This study aimed to determine the effect of preexercise carbohydrate of different glycemic indices on subcutaneous abdominal adipose tissue (SCAAT) metabolism and running performance. METHODS: Ten trained male runners completed three experimental trials consisting of 30 min at 60% maximal oxygen consumption, 30 min at 75% maximal oxygen consumption, and a 5-km time trial. Thirty minutes before exercise, participants consumed one of three beverages: 1) 75 g low glycemic index modified starch supplement (UCAN), 2) 75 g high glycemic index glucose-based supplement (G), or 3) a flavor-matched noncaloric placebo (PL). SCAAT lipolysis was assessed via microdialysis. RESULTS: Before exercise, blood glucose and insulin were elevated with G versus PL (+53.0 ± 21.3 mg·dL (mean ± SD), P < 0.0001; +33.9 ± 11.0 µU·mL, P < 0.0001) and G versus UCAN (+36.6 ± 24.9 mg·dL, P < 0.0001; +25.2 ± 11.0 µU·mL, P < 0.0001), respectively. Fat oxidation was attenuated, and carbohydrate oxidation increased before exercise with G versus PL (-0.06 ± 0.06 g·min, P = 0.005; +0.18 ± 0.07 g·min, P < 0.0001) and G versus UCAN (-0.06 ± 0.05 g·min, P = 0.004; +0.18 ± 0.14 g·min, P < 0.0001). However, there were no differences in SCAAT lipolysis at rest or during running at either exercise intensity. Also, there was no effect of treatment on running performance. CONCLUSIONS: Preexercise carbohydrate lowers fat oxidation and increases carbohydrate oxidation, and these effects are attenuated with low glycemic index carbohydrate. However, these changes are not the result of alterations in SCAAT lipolysis, nor do they affect running performance.

Model assisted comparison of Protein A resins and multi-column chromatography for capture processes.

Effect of particle size (85µm vs. 50µm) on the performance of continuous capture chromatography using Protein A affinity was evaluated in combination with varied feed titers, loading flow rates and target breakthrough using a Design of Experiments (DoE) approach. In comparison to previous studies, higher cell culture titers on the order of 5-15 g/L, relevant to current high productivity industrial cell lines, were evaluated. Further, three modes of capture continuous chromatography were included in the DoE: single column batch, 2-column CaptureSMB and 4-column periodic counter-current chromatography (PCC). The breakthrough percentage at the outlet of the first column being loaded showed the most significant impact on process performance, confirming the advantage of multi-column over batch chromatography processes. Out of the two resins, the one with smaller particle size displayed significantly better performance. To verify and generalize these results, a shrinking core model for protein A chromatography has been developed and validated. The model was used to optimize the processes with respect to capacity utilization (load per cycle) and productivity (load per time). The smaller particle size resin (50µm) produced steeper breakthrough curves and allowed for better capacity utilization at any given productivity value. The improvement in loading was around 15% on average in comparison to the 85µm bead size in spite of the ligand density being same. The 50µm resin also allowed for higher maximum productivity values compared to the 85µm resin (improvements of 25-50%, depending on the process), despite lower maximum flow rate due to increased pressure drop. In addition, it is worth noting that recovery and regeneration rather than the maximum flow rate (pressure drop) became the limiting factor for process optimization in almost all considered scenarios.

Optimal model-based design of the twin-column CaptureSMB process improves capacity utilization and productivity in protein A affinity capture.

Multi-column chromatographic processes have recently been developed for protein A affinity chromatography to efficiently capture monoclonal antibodies from cell culture supernatant. In this work, the novel twin-column CaptureSMB process was compared to a batch capture process with dual loading flow rate to identify performance gains. As a case study, the isolation of a monoclonal antibody with the Amsphere JWT-203 protein A resin was investigated. Using model based optimization, both processes were optimized and compared over a wide range of operating conditions. A trade-off between productivity and capacity utilization was found, and the resulting pareto-curves showed that CaptureSMB dominates batch, except at very low productivity values. With a feed titer of 1.2 mg mL(-1) , CaptureSMB could reach a productivity of up to 19.5 mg mL(-1) h(-1) experimentally, while maintaining relatively high capacity utilization of 63.8%. On the other hand, at maximum capacity utilization of 95.5%, a productivity of 10.2 mg mL(-1) h(-1) could be reached. This corresponds to a performance improvement with respect batch operation of about 25% in capacity utilization and 40% in productivity, for given yield and purity. CaptureSMB therefore offers a greatly increased performance over batch capture.

Comparison of batch and continuous multi-column protein A capture processes by optimal design.

Multi-column capture processes show several advantages compared to batch capture. It is however not evident how many columns one should use exactly. To investigate this issue, twin-column CaptureSMB, 3- and 4-column periodic counter-current chromatography (PCC) and single column batch capture are numerically optimized and compared in terms of process performance for capturing a monoclonal antibody using protein A chromatography. Optimization is carried out with respect to productivity and capacity utilization (amount of product loaded per cycle compared to the maximum amount possible), while keeping yield and purity constant. For a wide range of process parameters, all three multi-column processes show similar maximum capacity utilization and performed significantly better than batch. When maximizing productivity, the CaptureSMB process shows optimal performance, except at high feed titers, where batch chromatography can reach higher productivity values than the multi-column processes due to the complete decoupling of the loading and elution steps, albeit at a large cost in terms of capacity utilization. In terms of trade-off, i.e. how much the capacity utilization decreases with increasing productivity, CaptureSMB is optimal for low and high feed titers, whereas the 3-column process is optimal in an intermediate region. Using these findings, the most suitable process can be chosen for different production scenarios.