Effect of Water Content on Glass Transition and Protein Aggregation of Whey Protein Powders During Short-Term Storage

The objectives of this study were to investigate the moisture-induced protein aggregation of whey protein powders and to elucidate the relationship of protein stability with respect to water content and glass transition. Three whey protein powder types were studied: whey protein isolate (WPI), whey protein hydrolysates (WPH), and beta-lactoglobulin (BLG). The water sorption isotherms were determined at 23 and 45°C, and they fit the Guggenheim–Andersson–DeBoer (GAB) model well. Glass transition was determined by differential scanning calorimeter (DSC). The heat capacity changes of WPI and BLG during glass transition were small (0.1 to 0.2 Jg⁻¹ °C⁻¹), and the glass transition temperature (T _g) could not be detected for all samples. An increase in water content in the range of 7 to 16% caused a decrease in T _g from 119 down to 75°C for WPI, and a decrease from 93 to 47°C for WPH. Protein aggregation after 2 weeks’ storage was measured by the increase in insoluble aggregates and change in soluble protein fractions. For WPI and BLG, no protein aggregation was observed over the range of 0 to 85% RH, whereas for WPH, ∼50% of proteins became insoluble after storage at 23°C and 85% RH or at 45°C and ≥73% RH, caused mainly by the formation of intermolecular disulfide bonds. This suggests that, at increased water content, a decrease in the T _g of whey protein powders results in a dramatic increase in the mobility of protein molecules, leading to protein aggregation in short-term storage.     

Post-exercise carbohydrate plus whey protein hydrolysates supplementation increases skeletal muscle glycogen level in rats

Recent studies showed that a combination of carbohydrate and protein was more effective than carbohydrate alone for replenishing muscle glycogen after exercise. However, it remains to be unclear whether the source or degree of hydrolysis of dietary protein influences post-exercise glycogen accumulation. The aim of this study was to compare the effect of dietary protein type on glycogen levels in the post-exercise phase, and to investigate the effects of post-exercise carbohydrate and protein supplementation on phosphorylated enzymes of Akt/PKB and atypical PKCs. Male Sprague-Dawley rats, trained for 3 days, swam with a 2% load of body weight for 4 h to deplete skeletal muscle glycogen. Immediately after the glycogen-depleting exercise, one group was killed, whereas the other groups were given either glucose or glucose plus protein (whey protein, whey protein hydrolysates (WPH), casein hydrolysates or branched-chain amino acid (BCAA) solutions. After 2 h, the rats were killed, and the triceps muscles quickly excised. WPH caused significant increases in skeletal muscle glycogen level (5.01 ± 0.24 mg/g), compared with whey protein (4.23 ± 0.24 mg/g), BCAA (3.92 ± 0.18 mg/g) or casein hydrolysates (2.73 ± 0.22 mg/g). Post-exercise ingestion of glucose plus WPH significantly increased both phosphorylated Akt/PKB (131%) and phosphorylated PKCζ (154%) levels compared with glucose only. There was a significant positive correlation between skeletal muscle glycogen content and phosphorylated Akt/PKB (r = 0.674, P < 0.001) and PKCζ (r = 0.481, P = 0.017). Post-exercise supplementation with carbohydrate and WPH increases skeletal muscle glycogen recovery by activating key enzymes such as Akt/PKB and atypical PKCs.     

Whey Protein Hydrolysate Increases Translocation of GLUT-4 to the Plasma Membrane Independent of Insulin in Wistar Rats

Whey protein (WP) and whey protein hydrolysate (WPH) have the recognized capacity to increase glycogen stores. The objective of this study was to verify if consuming WP and WPH could also increase the concentration of the glucose transporters GLUT-1 and GLUT-4 in the plasma membrane (PM) of the muscle cells of sedentary and exercised animals. Forty-eight Wistar rats were divided into 6 groups (n = 8 per group), were treated and fed with experimental diets for 9 days as follows: a) control casein (CAS); b) WP; c) WPH; d) CAS exercised; e) WP exercised; and f) WPH exercised. After the experimental period, the animals were sacrificed, muscle GLUT-1 and GLUT-4, p85, Akt and phosphorylated Akt were analyzed by western blotting, and the glycogen, blood amino acids, insulin levels and biochemical health indicators were analyzed using standard methods. Consumption of WPH significantly increased the concentrations of GLUT-4 in the PM and glycogen, whereas the GLUT-1 and insulin levels and the health indicators showed no alterations. The physical exercise associated with consumption of WPH had favorable effects on glucose transport into muscle. These results should encourage new studies dealing with the potential of both WP and WPH for the treatment or prevention of type II diabetes, a disease in which there is reduced translocation of GLUT-4 to the plasma membrane.     

Application of High-Intensity Ultrasounds to Control the Size of Whey Proteins Particles

In this paper, we reported a new method to prepare whey protein microparticles via high-intensity ultrasound disruption. Particles morphology was characterized by confocal microscopy, and their size and distribution were analyzed by light scattering technique. Starting whey protein isolate (WPI) exhibited changes in size and distribution according to its concentration. For WPI, 7.5% (w/w) mean size was 0.7 μm, and upon sonication at ambient temperature, the size was reduced up to 0.2 μm showing the particles a rounded morphology. Sonication at room temperature of gelled WPI led to particles with sizes between 0.1 and 10 μm which had a tendency to flocculate. When WPI was submitted to sonication under heating at protein denaturation temperature, different effects were observed according to protein concentration. The particle size was reduced for the lowest WPI concentration (7.5 wt.%), did not change at 9 wt.%, but strongly increased at 12 wt.%, in comparison with the untreated sample. WPI particles of desired size in the micron range may be obtained either by sonication of gelled WPI or by sonication under heating at denaturation temperature by controlling processing variables.     

Optimization and effect of dairy industrial waste as media components in the production of hyaluronic acid by Streptococcus thermophilus

Hyaluronic acid (HA) production using a dairy industrial waste is a more cost-efficient strategy than using an expensive synthetic medium. In this study, we investigated the production of HA using Streptococcus thermophilus under shake flask conditions using dairy industrial waste as nutritional supplements, namely whey permeate (WP) and whey protein hydrolysate (WPH). Preliminary screening using Plackett–Burman design exhibited WP, WPH, initial pH, and inoculum size as significant factors influencing HA titer. Response surface methodology design of four factors was formulated at three levels for enhanced production of HA. Shake flask HA fermentation by S. thermophilus was performed under global optimized process conditions and the optimal HA titer (342.93?mg?L^?1) corroborates with Box–Behnken design prediction. The molecular weight of HA was elucidated as 9.22–9.46?kDa. The ultralow-molecular weight HA reported in this study has a potential role in drug and gene delivery applications.     

Modulation of Glutamate and Glycine Transporters by Niflumic,Flufenamic and Mefenamic Acids

Three fenamates—niflumic, flufenamic and mefenamic acids—were tested for effects on substrate-induced currents of glutamate and glycine transporters (EAAT1, EAAT2, GLYT1b and GLYT2a) expressed in Xenopus laevis oocytes. All fenamates inhibited EAAT1 currents; 100 μM flufenamic acid produced the most inhibition, decreasing the I _max by 53 ± 4% (P < 0.001). EAAT2 currents were less sensitive, but 100 μM flufenamic acid inhibited the I _max by 34 ± 5% (P = 0.006). All fenamates inhibited GLYT1b currents; 100 μM flufenamic acid produced the most inhibition, decreasing the I _max by 61 ± 1% (P < 0.001). At 100 μM, effects on the GLYT2a I _max were mixed: 13 ± 2% inhibition by flufenamic acid (P = 0.002), 30 ± 6% enhancement by niflumic acid (P = 0.002), and no effect by mefenamic acid. Minor effects on substrate affinity suggested non-competitive mechanisms. These data could contribute to the development of selective transport modulators.     

Insulin: Its binding to specific receptors and its stimulation of DNA synthesis and 2′,3′-cyclic nucleotide phosphohydrolase activity in cerebral cells cultured from embryonic mouse brain

The presence and specificity of insulin receptors was investigated in cultured cells obtained from 15–16 days old embryonic mouse cerebra. Developmental studies suggested that the maximum insulin binding occurred at about 11 days in vitro (DIV). Scatchard analysis of binding data revealed two types of binding sites. One type of receptor was the high affinity type (K _d=7.77×10^–9 M; number of receptor sites,B _max=350 fmol/mg protein) while the other type was of low affinity type (K _d=5.75×10^–8 M;B _max=1150 fmol/mg protein). The specificity of receptors for insulin was also confirmed by showing that [¹²⁵I]insulin was displaced by non-radioactive insulin but not by glucagon or growth hormone. Insulin displayed a clear dose-dependent stimulation of thymidine incorporation. It also stimulated the activity of the enzyme 2,3-cyclic nucleotide phosphohydrolase (CNPase), which is specifically associated with myelin produced from oligodendroglia. Thus insulin has a positive influence on the proliferation and differentiation of brain cells.     

Phase Behavior of Whey Protein Aggregates/κ-Carrageenan Mixtures: Experiment and Theory

The phase separation behavior of whey protein isolate (WPI) aggregates and κ-carrageenan (κ-car) mixtures was studied using the Vrij's theory and image analysis method. The intrinsic parameter (molecular mass and radius of gyration) for κ-car and the WPI aggregates was determined using intrinsic viscosity and reduced viscosity of each biopolymer. Confocal microscopy observations revealed the appearance of protein aggregate domains when phase separation occurred, with microgel droplets of WPI included in a continuous κ-car phase. The occurrence of aggregate droplet has not been reported before for the phase-separating WPI/κ-car mixtures. So far, network emulsion-like microstructures have been observed with WPI in a network structure. By using different WPI concentrations (4% or 6%), the microstructure of the systems changes while increasing the κ-car concentration. The size of the microgels (1–2.5 μm) depends on both κ-car and WPI concentration. Confocal microscopy combined with image analysis (method of the variance) was used effectively as objective means to determine the phase boundary of the phase-separating systems. Additional information on the depletion layer thickness, Δ, was obtained using self-consistent field theory. The results show that Δ has a constant value of 80.5 nm for c_{k - car} \prec 2 g/l {{\hbox{c}}_{\kappa {\rm{ - car}}}} \prec {\hbox{2 g}}/{l} , in agreement with ∆ ≈ R _g (radius of gyration). Above this concentration, Δ decreases as a function of κ-car concentration. The experimental phase boundary was well predicted using Vrij's theory. This work showed a new approach to generate phase diagrams (e.g., under shear) of phase-separating systems.     

Acute and long-term effects of resistance exercise with or without protein ingestion on muscle hypertrophy and gene expression

The effects of timed ingestion of high-quality protein before and after resistance exercise are not well known. In this study, young men were randomized to protein (n = 11), placebo (n = 10) and control (n = 10) groups. Muscle cross-sectional area by MRI and muscle forces were analyzed before and after 21 weeks of either heavy resistance training (RT) or control period. Muscle biopsies were taken before, and 1 and 48 h after 5 × 10 repetition leg press exercise (RE) as well as 21 weeks after RT. Protein (15 g of whey both before and after exercise) or non-energetic placebo were provided to subjects in the context of both single RE bout (acute responses) as well as each RE workout twice a week throughout the 21-week-RT. Protein intake increased (P ≤ 0.05) RT-induced muscle cross-sectional area enlargement and cell-cycle kinase cdk2 mRNA expression in the vastus lateralis muscle suggesting higher proliferating cell activation response with protein supplementation. Moreover, protein intake seemed to prevent 1 h post-RE decrease in myostatin and myogenin mRNA expression but did not affect activin receptor IIb, p21, FLRG, MAFbx or MyoD expression. In conclusion, protein intake close to resistance exercise workout may alter mRNA expression in a manner advantageous for muscle hypertrophy.     

Nonobese Young Females with Polycystic Ovary Syndrome Have Nutritive Microvascular Dysfunction: A Pilot Study

ObjectiveTo investigate nutritive microvascular function in young nonobese females with polycystic ovary syndrome (PCOS) and to correlate microvascular reactivity with sex steroids, inflammatory markers, and metabolic variables.MethodsFourteen nonobese females with PCOS (24.6 ± 2.7 years, body mass index [BMI] 23.7 ± 3.1 kg/ m²) and 13 age- and BMI-matched controls (22.8 ± 2.3 years, 22.5 ± 3.4kg/m2) underwent anthropometric, hormonal, and microvascular evaluations. The main outcome measures were capillary density, red blood cell velocity (RBCV) at resting and peak during postocclusive reactive hyperemia (RBCV_max), and time taken to reach RBCV_max (TRBCV_max).ResultsSubjects with PCOS had lower RBCV and higher TRBCV_max compared to controls, respectively (0.237 [0.220-0.324] vs. 0.362 [0.297-0.382] mm/s, F < .01) and (5 [5-6] vs. 4 [3-5] s, P < .05]. The free androgen index (FAI) and sex hormone-binding globulin (SHBG) level were different between groups. FAI correlated to RBCV_max (ρ = -0.49, P < .05) and to TRBCV_max (ρ = 0.41, P < .05). SHBG correlated with RBCV_max (ρ = 0.52, P < .01) while estradiol (E₂) levels correlated with RBCV (ρ = 0.80, P < .001) and RBCV_max (ρ = 0.46, P < .05).ConclusionMicrovascular dysfunction characterized by reduced RBCV_maxand prolonged TRBCV_maxwas present in young, nonobese PCOS subjects. FAI was associated with observed impairments, suggesting a possible common mechanism linking sex hormones and microvascular dysfunction. (Endocr Pract. 2014;20:1281-1289)     

Human mitochondrial haplogroup H: The highest VO2max consumer – Is it a paradox?

Mitochondrial background has been demonstrated to influence maximal oxygen uptake (VO_2max, in mL kg^?1 min^?1), but this genetic influence can be compensated for by regular exercise. A positive correlation among electron transport chain (ETC) coupling, ATP and reactive oxygen species (ROS) production has been established, and mitochondrial variants have been reported to show differences in their ETC performance. In this study, we examined in detail the VO_2max differences found among mitochondrial haplogroups. We recruited 81 healthy male Spanish Caucasian individuals and determined their mitochondrial haplogroup. Their VO_2max was determined using incremental cycling exercise (ICE). VO_2max was lower in J than in non-J haplogroup individuals (P = 0.04). The H haplogroup was responsible for this difference (VO_2max; J vs. H; P = 0.008) and this group also had significantly higher mitochondrial oxidative damage (mtOD) than the J haplogroup (P = 0.04). In agreement with these results, VO_2max and mtOD were positively correlated (P = 0.01). Given that ROS production is the major contributor to mtOD and consumes four times more oxygen per electron than the ETC, our results strongly suggest that ROS production is responsible for the higher VO_2max found in the H variant. These findings not only contribute to a better understanding of the mechanisms underneath VO_2max, but also help to explain some reported associations between mitochondrial haplogroups and mtOD with longevity, sperm motility, premature aging and susceptibility to different pathologies.     

Assessment of the potential of temporin peptides from the frog Rana temporaria (Ranidae) as anti‐diabetic agents

Temporin A (FLPLIGRVLSGIL‐NH₂), temporin F (FLPLIGKVLSGIL‐NH₂), and temporin G (FFPVIGRILNGIL‐NH₂), first identified in skin secretions of the frog Rana temporaria, produced concentration‐dependent stimulation of insulin release from BRIN‐BD11 rat clonal β‐cells at concentrations ≥1 nM, without cytotoxicity at concentrations up to 3 μM. Temporin A was the most effective. The mechanism of insulinotropic action did not involve an increase in intracellular Ca²⁺ concentrations. Temporins B, C, E, H, and K were either inactive or only weakly active. Temporins A, F, and G also produced a concentration‐dependent stimulation of insulin release from 1.1B4 human‐derived pancreatic β‐cells, with temporin G being the most potent and effective, and from isolated mouse islets. The data indicate that cationicity, hydrophobicity, and the angle subtended by the charged residues in the temporin molecule are important determinants for in vitro insulinotropic activity. Temporin A and F (1 μM), but not temporin G, protected BRIN‐BD11 cells against cytokine‐induced apoptosis (P < 0.001) and augmented (P < 0.001) proliferation of the cells to a similar extent as glucagon‐like peptide‐1. Intraperitoneal injection of temporin G (75 nmol/kg body weight) together with a glucose load (18 mmol/kg body weight) in C57BL6 mice improved glucose tolerance with a concomitant increase in insulin secretion whereas temporin A and F administration was without significant effect on plasma glucose levels. The study suggests that combination therapy involving agents developed from the temporin A and G sequences may find application in Type 2 diabetes treatment.     

Improved Viability of Microencapsulated Probiotics in a Freeze-Dried Banana Powder During Storage and Under Simulated Gastrointestinal Tract

Freeze-dried banana powder represents an ideal source of nutrients and has not yet been used for probiotic incorporation. In this study, microencapsulation by freeze drying of probiotics Lactobacillus acidophilus and Lactobacillus casei was made using whey protein isolate (WPI), fructooligosaccharides (FOS), and their combination (WPI + FOS) at ratio (1:1). Higher encapsulation yield was found for (WPI + FOS) microspheres (98%). Further, microcapsules of (WPI + FOS) were used to produce a freeze-dried banana powder which was analyzed for bacterial viability under simulated gastrointestinal fluid (SGIF), stability during storage at 4 °C and 25 °C, and chemical and sensory properties. Results revealed that (WPI + FOS) microcapsules significantly increased bacteria stability in the product over 30 days of storage at 4 °C averaging (≥ 8.57 log CFU/g) for L. acidophilus and (≥ 7.61 log CFU/g) for L. Casei as compared to free cells. Bacteria encapsulated in microspheres (WPI + FOS) were not significantly affected by the SGIF, remaining stable up to 7.05 ± 0.1 log CFU/g for L.acidophilus and 5.48 ± 0.1 log CFU/g for L.casei after 90 min of incubation at pH 2 compared to free cells which showed minimal survival. Overall, encapsulated probiotics enriched freeze-dried banana powders received good sensory scores; they can therefore serve as safe probiotics food carriers.

     

Glutathione and Vitamin B12 Cooperate in Stabilization of a B12 Trafficking Chaperone Protein

The protein bCblC (bCblCpro) is a bovine homolog of a human B₁₂ trafficking chaperone that is responsible for the processing of vitamin B₁₂ and its escorted delivery in intracellular B₁₂ metabolism. In this study, we found that bCblCpro is highly thermolabile with a T _m = 42.0 ± 0.2 °C as shown for the human homolog, suggesting thermal regulation of these proteins. Binding of the reduced form of glutathione (GSH) that is a predominant cellular thiol increased the T _m of bCblCpro from 42 °C to ~45 °C (ΔT _{m max} = 3.1 ± 0.2 °C and AC₅₀ = 2.1 ± 0.5 mM). Binding of vitamin B₁₂ and its derivatives also stabilized bCblCpro increasing the T _m to a different extent and vitamin B₁₂ (cyanocobalamin, CNCbl) was the least efficient (ΔT _{m max} = 4.3 ± 0.3 °C and AC₅₀ = 291 ± 36 μM). However, the stabilizing effect of CNCbl was significantly greater for GSH-bound bCblCpro (ΔT _{m max} = 12.8 ± 0.6 °C and AC₅₀ = 9.3 ± 1.6 μM) than for GSH-free bCblCpro. In addition, the stabilizing effect of GSH was also greater for CNCbl-bound bCblCpro (ΔT _{m max} = 9.3 ± 0.3 °C and AC₅₀ = 57.0 ± 6.8 μM). Limited proteolysis revealed that thermal stabilization of bCblCpro is derived from conformational changes of the protein induced by binding of the ligands. The results in this study indicate that GSH cooperates with vitamin B₁₂ in thermal stabilization of bCblCpro and is a positive regulator of the protein.     

Type 1 Diabetes Mellitus and Lipohypertrophy - Impact of the Intervention on Glycemic Control via Patient’s Examination and Retraining on Change of Infusion Set

ObjectiveLipohypertrophy (LH) is a common complication of insulin therapy in type 1 diabetes mellitus (T1DM). We examined whether an intervention consisting of LH assessment and retraining on insulin infusion set use improves glycemic control on subcutaneous insulin infusion (CSII) in patients with T1DM.MethodsThe intervention was conducted in 79 consecutive patients with T1DM. Data on glucose levels, glycated hemoglobin (HbA1c), and insulin doses were collected at baseline and after a median of 22 weeks (20-31.75 weeks).ResultsA total of 46 patients with T1DM (23 [50%] women) participating in the follow-up were characterized by a median age of 29 years (25-33.8 years), body mass index of 24.6 ± 3.3 kg/m², T1DM duration of 16.5 years (8.3-20 years), and subcutaneous insulin infusion duration of 7 years (4-10.8 years). Patients’ median HbA1c fell from 7.4% (6.7%-8.2%) to 7.05% (6.4%-7.6%) (P < .001), daily insulin dose/kg decreased (0.7 ± 0.20 vs 0.68 ± 0.15 IU/kg; P = .017) together with the total daily insulin dose (50.3 [40.5-62.7] vs 47.6 [39.8-62.1] IU; P = .019]. Furthermore, the percentage of basal insulin dose increased (43.0% [36-50] vs 44.0% [39.0-50.0]; P = .010], whereas the percentage of bolus dose decreased (57% [50-64] vs 56% [50-61], P = .010).ConclusionsThe structured LH-related intervention in patients with T1DM on insulin pumps resulted in better glycemic control and a decrease in total daily insulin dose.     

Delayed treatment with GnRH agonist, hCG and progesterone and reduced embryonic mortality in buffaloes

The present study examined the effect of delayed treatment with tropic hormones and progesterone (P₄) on embryonic mortality in buffaloes. Buffaloes with a conceptus on Day 25 after AI were assigned to the following treatments: Control (n = 41), i.m. physiological saline; GnRH agonist (n = 36), i.m. 12 μg buserelin acetate; hCG (n = 33), i.m. 1500 IU hCG; P₄ (n = 38), i.m. 341 mg P₄ every 4 days on three occasions. Control buffaloes had an embryonic mortality of 41.4% (17/41) between Days 25 and 45, and this was reduced (P < 0.01) by treatment with GnRH agonist (11.1%, 4/36), hCG (9.0%, 3/33) and P₄ (13.1%, 5/38). On Day 45, buffaloes treated with hCG and which ovulated had greater (P < 0.05) concentrations of P₄ in whey (453 ± 41 pg/ml) than buffaloes in the same treatment that did not ovulate (297 ± 32 pg/ml). A similar but non-significant trend was observed for buffaloes treated with GnRH agonist. It was concluded from the findings that the treatment of buffaloes on Day 25 after AI with tropic hormones or P₄ is beneficial to processes associated with embryonic implantation.     

Whey Protein Hydrolysate Enhances HSP90 but Does Not Alter HSP60 and HSP25 in Skeletal Muscle of Rats

Whey protein hydrolysate (WPH) intake has shown to increase HSP70 expression. The aim of the present study was to investigate whether WPH intake would also influences HSP90, HSP60 and HSP25 expression, as well as associated parameters. Forty-eight male Wistar rats were divided into sedentary (unstressed) and exercised (stressed) groups, and were fed with three different sources of protein: whey protein (WP), whey protein hydrolysate (WPH) and casein (CAS) as a control, based on the AIN93G diet for 3 weeks. WPH intake increased HSP90 expression in both sedentary and exercised animals compared to WP or CAS, however no alteration was found from exercise or diet to HSP60 or HSP25. Co-chaperone Aha1 and p-HSF1 were also increased in the exercised animals fed with WPH in comparison with WP or CAS, consistent with enhanced HSP90 expression. VEGF and p-AKT were increased in the WPH exercised group. No alteration was found in BCKDH, PI3-Kinase (p85), GFAT, OGT or PGC for diet or exercise. The antioxidant system GPx, catalase and SOD showed different responses to diet and exercise. The data indicate that WPH intake enhanced factors related to cell survival, such as HSP90 and VEGF, but does not alter HSP60 or HSP25 in rat skeletal muscle.     

Habitual physical activity and peak anaerobic power in elderly women

The aim of this study was to investigate the relationship between maximal anaerobic power (P _max) and corresponding optimal velocity (V _opt) and habitual physical activity (PA) on the one hand and with maximal oxygen consumption (V˙O_2max) on the other hand, in elderly women. Twenty-nine community dwelling, healthy women aged 66–82 years participated in the study. PA was evaluated using the Questionnaire d'Activite Physique Saint-Etienne (QAPSE) and expressed using two QAPSE activity indices: mean habitual daily energy expenditure (MHDEE) and daily energy expenditure corresponding to leisure time sports activities (sports activity). The subjects' P _max and V _opt were measured while they cycled on a friction-loaded non-isokinetic cycle ergometer. P _max was expressed relative to body mass [P _max/kg(W · kg⁻¹)], and relative to the mass of two quadriceps muscles [P _{max /Quadr}(W·kg_Quadr ⁻¹)]. A negative relationship between P _max/kg (Spearman's r = −0.56; P < 0.01), P _max/Quadr (r = −0.53; P < 0.01) and V _opt (r = −0.45; P < 0.05) and age was found. P _max/kg was positively associated with MHDEE (r = 0.51; P < 0.01) and sports activity (r = 0.58; P < 0.01), as were P _max/Quadr and V _opt (r = 0.55; P < 0.01 and r = 0.54; P < 0.01, respectively). P _max/kg, P _max/Quadr and V _opt correlated positively with V˙O_2max. The positive relationship between ergometer measurements and PA indices was similar to that between V˙O_2max and PA. P _max/kg was, moreover, closely related to V _opt (r = 0.77; P < 0.001). When a multiple stepwise regression analysis was used to select the variables influencing ergometer measurements, MHDEE contributed significantly to P _max/kg variance, whereas sports activity contributed to P _max/Quadr and V _opt variances. In conclusion, the data from this cross-sectional study suggest that in healthy elderly women habitual PA, and especially leisure time PA, alleviates the decline of the P _max of the quadriceps muscles. Accepted: 30 January 1997     

Whey protein hydrolysates enhance water absorption in the perfused small intestine of anesthetized rats

We evaluated the effect of whey protein hydrolysates (WPH) on the water absorption rate in the small intestine using a rat small intestine perfusion model. The rate was significantly higher with 5 g/L WPH than with 5 g/L soy protein hydrolysates or physiological saline (p?p?p?r?=?0.82, p?相似文献   

Exercise-induced oxyhemoglobin desaturation and pulmonary diffusing capacity during high-intensity exercise

The purpose of this investigation was to examine if exercise-induced arterial oxyhemoglobin desaturation selectively observed in highly trained endurance athletes could be related to differences in the pulmonary diffusing capacity (D _L) measured during exercise. The D _L of 24 male endurance athletes was measured using a 3-s breath-hold carbon monoxide procedure (to give D _LCO) at rest as well as during cycling at 60% and 90% of these previously determined O_2max. Oxyhemoglobin saturation (S _aO₂%) was monitored throughout both exercise protocols using an Ohmeda Biox II oximeter. Exercise-induced oxyhemoglobin desaturation (DS) (S _aO₂% < 91% at O_2max) was observed in 13 subjects [88.2 (0.6)%] but not in the other 11 nondesaturation subjects [NDS: 92.9 (0.4)%] (P ≤ 0.05), although O_2max was not significantly different between the groups [DS: 4.34 (0.65) l / min vs NDS: 4.1 (0.49) l / min]. At rest, no differences in either D _LCO [m1 CO · mmHg⁻¹ · min⁻¹: 41.7 (1.7) (DS) vs 41.1 (1.8) (NDS)], D _LCO / _A [8.2 (0.4) (DS) vs 7.3 (0.9) (NDS)], MVV [l / min: 196.0 (10.4) (DS) vs 182.0 (9.9) (NDS)] or FEV₁/FVC [86.3 (2.2) (DS) vs 82.9 (4.7) (NDS)] were found between groups (P ≥ 0.05). However, _E /O₂ at O_2max was lower in the DS group [33.0 (1.1)] compared to the NDS group [36.8 (1.5)] (P ≤ 0.05). Exercise D _LCO (m1 CO · mmHg⁻¹ · min⁻¹) was not different between groups at either 60% O_2max [DS: 55.1 (1.4) vs NDS: 57.2 (2.1)] or at 90% O_2max [DS: 61.0 (1.8) vs NDS: 61.4 (2.9)]. A significant relationship (r = 0.698) was calculated to occur between S _aO₂% and _E /O₂ during maximal exercise. The present findings indicate that the exercise-induced oxyhemoglobin desaturation seen during submaximal and near-maximal exercise is not related to differences in D _L, although during maximal exercise S _aO₂ may be limited by a relatively lower exercise ventilation. Accepted: 25 September 1996