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Hemodynamic and perceptual responses to blood flow-restricted exercise among patients undergoing dialysis.
Clarkson, MJ, Brumby, C, Fraser, SF, McMahon, LP, Bennett, PN, Warmington, SA
American journal of physiology. Renal physiology. 2020;(3):F843-F850
Abstract
End-stage kidney disease is associated with reduced exercise capacity, muscle atrophy, and impaired muscle function. While these may be improved with exercise, single modalities of exercise do not traditionally elicit improvements across all required physiological domains. Blood flow-restricted exercise may improve all of these physiological domains with low intensities traditionally considered insufficient for these adaptions. Investigation of this technique appeals, but is yet to be evaluated, in patients undergoing dialysis. With the use of a progressive crossover design, 10 satellite patients undergoing hemodialysis underwent three exercise conditions over 2 wk: two bouts (10 min) of unrestricted cycling during two consecutive hemodialysis sessions (condition 1), two bouts of cycling with blood flow restriction while off hemodialysis on 2 separate days (condition 2), and two bouts of cycling with blood flow restriction during two hemodialysis sessions (condition 3). Outcomes included hemodynamic responses (heart rate and blood pressure) throughout all sessions, participant-perceived exertion and discomfort on a Borg scale, and evaluation of ultrafiltration rates and dialysis adequacy (Kt/V) obtained post hoc. Hemodynamic responses were consistent regardless of condition. Significant increases in heart rate, systolic blood pressure, and mean arterial blood pressure (P < 0.05) were observed postexercise followed by a reduction in blood pressures during the 60-min recovery (12, 5, and 11 mmHg for systolic, diastolic, and mean arterial pressures, respectively). Blood pressures returned to predialysis ranges following the recovery period. Blood flow restriction did not affect ultrafiltration achieved or Kt/V. Hemodynamic safety and tolerability of blood flow restriction during aerobic exercise on hemodialysis is comparable to standard aerobic exercise.
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Children's perceptions about medicines: individual differences and taste.
Mennella, JA, Roberts, KM, Mathew, PS, Reed, DR
BMC pediatrics. 2015;:130
Abstract
BACKGROUND Bitter taste receptors are genetically diverse, so children likely vary in sensitivity to the "bad" taste of some pediatric formulations. Based on prior results that variation in a bitter taste receptor gene, TAS2R38, was related to solid (pill) formulation usage, we investigated whether this variation related to liquid formulation usage and young children's reports of past experiences with medicines and whether maternal reports of these past experiences were concordant with those of their children. METHODS We conducted retrospective interviews of 172 children 3 to 10 years old and their mothers (N = 130) separately in a clinical research setting about issues related to medication usage. Children were genotyped for the TASR38 variant A49P (alanine to proline at position 49). Children's responses were compared with their TAS2R38 genotype and with maternal reports. RESULTS Children (>4 years) reported rejecting medication primarily because of taste complaints, and those with at least one sensitive TAS2R38 allele (AP or PP genotype) were more likely to report rejecting liquid medications than were those without a taster allele (AA genotype; χ(2) = 5.72, df = 1, p = 0.02). Children's and mothers' reports of the children's past problems with medication were in concordance (p = 0.03). CONCLUSIONS Individual differences in taste responses to medications highlight the need to consider children's genetic variation and their own perceptions when developing formulations acceptable to the pediatric palate. Pediatric trials could systematically collect valid information directly from children and from their caregivers regarding palatability (rejection) issues, providing data to develop well-accepted pediatric formulations that effectively treat illnesses for all children. TRIAL REGISTRATION Clinicaltrials.gov protocol registration system (NCT01407939). Registered 19 July 2011.
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Oxygen uptake and ratings of perceived exertion at the lactate threshold and maximal fat oxidation rate in untrained adults.
Rynders, CA, Angadi, SS, Weltman, NY, Gaesser, GA, Weltman, A
European journal of applied physiology. 2011;(9):2063-8
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Abstract
The purpose of the study was to examine the relationship between VO(2) and RPE at the lactate threshold (LT) and maximal fat oxidation rate (FAT(MAX)) in untrained adults and determine the stability of the relationship across sex, age, and fitness status. A total of 148 untrained adults (mean age [year] = 30.5 ± 13.9, height [m] = 1.72 ± 0.08 m, body mass [kg] = 82.6 ± 20.5, body fat [%] = 28.7 ± 12.0) completed a continuous incremental VO(2) peak/LT protocol. Fat oxidation rates were determined using indirect calorimetry. The highest recorded fat oxidation rate was chosen as FAT(MAX). The breakpoint in the VO(2)-blood lactate relationship was chosen as LT. RPE was based on the Borg 6-20 scale. Bland-Altman plot analysis demonstrated that VO(2) FAT(MAX) systematically preceded VO(2) LT (mean bias = 1.3 ml kg(-1) min(-1)) with wide limits of agreement (+9.6 to -6.9 ml kg(-1) min(-1)). Multivariate ANOVA revealed a significant difference between VO(2) FAT(MAX) (12.7 ± 7.5 ml kg(-1) min(-1)) and VO(2) LT (14.1 ± 5.9 ml kg(-1) min(-1)) in the total sample (p = 0.04). There were no differences between the intensities when the sample was divided into sex, age, and fitness comparison groups (p values >0.05). RPE FAT(MAX) (9.4 ± 2.5) preceded RPE LT (10.4 ± 2.0) in the total sample (p = 0.008), but was not different across comparison groups (p > 0.05). The present data indicate that the highest rate of fat oxidation slightly precedes the LT in untrained adults. For exercise prescription, a Borg-RPE of 9-12 identifies both FAT(MAX) and LT.
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Processing of food stimuli is selectively enhanced during insulin-induced hypoglycemia in healthy men.
Schultes, B, Peters, A, Kern, W, Gais, S, Oltmanns, KM, Fehm, HL, Born, J
Psychoneuroendocrinology. 2005;(5):496-504
Abstract
Recently it has been reported that during insulin-induced hypoglycemia selective attention is directed to food stimuli suggesting an adaptive cognitive strategy to escape from this potentially dangerous metabolic state. Here, we tested this hypothesis using a short-term memory task. We also aimed to define a hypoglycemic threshold level at which such an adaptive cognitive strategy first occurs. Fifteen healthy men underwent stepwise hypoglycemic (plasma glucose: 4.1-3.6-3.1-2.6 mmol/l) and euglycemic clamp experiments. Clamps were performed in a single blind fashion within a cross-over design with the order balanced across subjects. During the clamps cognitive function tests (short-term recall of food-related and non-food-related words; Stroop task) were applied at baseline and each hypoglycemic plateau, and at the corresponding time intervals of the euglycemic clamp. Performance on all cognitive function tests applied deteriorated during the hypoglycemic as compared to the euglcemic clamp (all P<0.02). Separate analyses at each hypoglycemic plateau revealed that food and non-food related short-term memory was similar during baseline and mild hypoglycemia. However, at the hypoglycemic target level of 2.6 mmol/l recall of food related words was higher than non-food related words when compared to the euglycemic control clamp condition (p=0.024). Performance on the word-color conflict Stroop task became significantly impaired first at the lowest hypoglycemic plateau (2.6 mmol/l), while performance on the Stroop subtests 'color naming' and 'word reading' were already impaired at higher plasma glucose levels (3.6 and 3.1 mmol/l; respectively). Collectively, data of the Stroop task indicate that the control of attention via executive mechanisms is less sensitive to insulin-induced hypoglycemia than pre-attentive automated stimulus processing (reading, naming). If executive control of attention becomes affected by hypoglycemia, cognitive resources appear to be preferentially allocated to the processing of food stimuli.
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Odor-induced changes in taste perception.
Djordjevic, J, Zatorre, RJ, Jones-Gotman, M
Experimental brain research. 2004;(3):405-8
Abstract
We investigated odor-induced changes in taste perception (OICTP), by examining the influence of strawberry and soy sauce odors on perceived sweetness (Experiment 1) and saltiness (Experiment 2). We explored whether taste-smell interactions occur at the central level, by delivering odorants (strawberry, soy sauce, odorless water) and tastants (sucrose, sodium chloride) separately, and whether effects of imagined odors are comparable to those of physically presented odors. We found specific taste-smell interactions: sweetness enhancement induced by strawberry odor and saltiness enhancement induced by soy sauce odor. These interactions were elicited with separate delivery of olfactory and gustatory stimuli. Secondly, we found a similar but rather limited effect with the imagined odors: imagined strawberry enhanced perceived sweetness of water solutions, and imagined soy sauce enhanced perceived saltiness of weak sodium chloride solutions. We concluded that OICTP is a centrally mediated phenomenon, and that imagined odors can to some extent induce changes in perceived taste intensity comparable to those elicited by perceived odors.
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Role of cognitive factors in symptom induction following high and low fat meals in patients with functional dyspepsia.
Feinle-Bisset, C, Meier, B, Fried, M, Beglinger, C
Gut. 2003;(10):1414-8
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BACKGROUND and aims: Dietary fat plays a role in the pathophysiology of symptoms in functional dyspepsia (FD). In healthy subjects, cognitive factors enhance postprandial fullness; in FD patients, attention increases gut perception. We hypothesised that the information given to patients about the fat content of a meal would affect dyspeptic symptoms. METHODS Fifteen FD patients were each studied on four occasions in a randomised double blind fashion. Over two days they ingested a high fat yoghurt (HF) and over the other two days a low fat yoghurt (LF). For each yoghurt, the patients received the correct information about its fat content on one day (HF-C, LF-C) and the opposite (wrong) information on the other day (HF-W, LF-W). Dyspeptic symptoms, plasma cholecystokinin (CCK) concentrations, and gastric volumes were evaluated. RESULTS Both the fat content and information about the fat content affected fullness and bloating scores-both were higher after HF-C compared with LF-C, and LF-W compared with LF-C, with no differences between HF-C and HF-W. Nausea scores were higher after HF compared with LF, with no effect of the information about fat content. No differences between discomfort and pain scores were found between study conditions. Plasma CCK and gastric volumes were greater following HF compared with LF, with no effect of the information given to the patients. All differences are p<0.05. CONCLUSIONS Cognitive factors contribute to symptom induction in FD. Low fat foods may also elicit symptoms if patients perceive foods as high in fat, while CCK and gastric volumes do not appear to be affected by cognitive factors.
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Effect of dietary supplements and physical exercise on sensory perception, appetite, dietary intake and body weight in frail elderly subjects.
de Jong, N, Chin A Paw, MJ, de Graaf, C, van Staveren, WA
The British journal of nutrition. 2000;(6):605-13
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Abstract
This present study investigated the effect of a 17-week intervention programme with nutrient-dense foods (enriched with vitamins and minerals at 25-100% of the Dutch recommended dietary allowance) and/or physical exercise in 159 frail elderly subjects (forty-six men, 113 women, mean age 78.7 (SD 5.6) years). Subjects were randomized into four groups: (1) control, (2) nutrition intervention, (3) exercise or (4) both nutrition intervention and exercise. Main outcome variables were sensory perception (smell test and questionnaire), appetite (questionnaire), energy intake (3 d food record) and body weight (on a weighing scale and with dual energy X-ray absorptiometry measurements). At baseline, moderate but significant correlations were found between appetite and energy intake (r 0.30, P < 0.0001), between smell test and smell perception assessed by questionnaire (r 0.40, P < 0.0001) and between lean body weight and energy intake (r 0.50, P < 0.0001). Results after 17-weeks intervention revealed neither change in smell test scores (P = 0.19) nor in appetite (P = 0.17). A slight positive effect of exercise compared with non-exercising groups on energy intake (difference 0.5 MJ, P = 0.05) was shown next to a preserving effect of exercise on lean body mass (+0.08 kg) compared with a decrease (-0.4 kg) in non-exercisers (P < 0.02). The correlation between the change in lean body mass and change in energy intake was 0.18 (P = 0.05). In conclusion, an interesting preserving effect on lean body mass in frail elderly subjects due to 17 weeks of exercise was shown. Since a decline in lean body mass was observed in the non-exercisers, effects may be attributable to change in activity pattern. Changes in lean mass were also slightly, but significantly, correlated with changes in energy intake. In turn, energy intake was not related to a change in reported appetite or sensory perception. Nutrient-dense foods were not able to improve any of the outcome variables in this study.
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Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes.
Watson, JM, Jenkins, EJ, Hamilton, P, Lunt, MJ, Kerr, D
Diabetes care. 2000;(4):455-9
Abstract
OBJECTIVE To examine the influence of caffeine on the frequency and perception of hypoglycemia in "free-living" patients with type 1 diabetes. RESEARCH DESIGN AND METHODS A total of 34 patients with type 1 diabetes were recruited for a prospective randomized placebo-controlled double-blind study. After a lead-in phase and while adhering to a low-caffeine diet, subjects were randomized to capsules containing either 200 mg caffeine or matched placebo with crossover at 3 months. Hypoglycemic episodes were monitored throughout with capillary blood glucose readings and a symptom questionnaire. During the study, measurements of blood pressure, middle cerebral artery blood velocity (a surrogate measure of cerebral blood flow), cognitive function (via a four-choice reaction time test), HbAlc levels, and lipid profiles were taken at the beginning and end of each phase. RESULTS Throughout the study, no changes were evident regarding glycemic control or lipid profile. The number of symptomatic episodes was greater with caffeine (1.3 vs. 0.9 episodes/week; P < 0.03) and was associated with more intense warning symptoms (29 vs. 26 total symptom score; P < 0.05). For women, caffeine ingestion caused a modest pressor response (115 vs. 110 mmHg; P < 0.01). Four-choice reaction time improved slightly with caffeine supplementation (P < 0.05). CONCLUSIONS Ingestion of modest amounts of caffeine enhances the intensity of hypoglycemia warning symptoms in patients with type 1 diabetes without altering the prevailing standard of glycemic control or increasing the incidence of severe hypoglycemic episodes.