Physical activity, heart rate variability-based stress and recovery, and subjective stress during a 9-month study period.

The aim of this study was to investigate the association between physical activity (PA) and objective heart rate variability (HRV)-based stress and recovery with subjective stress in a longitudinal setting. Working-age participants (n = 221; 185 women, 36 men) were overweight (body mass index, 25.3-40.1 kg/m2 ) and psychologically distressed (≥3/12 points on the General Health Questionnaire). Objective stress and recovery were based on HRV recordings over 1-3 work days. Subjective stress was assessed with the Perceived Stress Scale and PA level with a questionnaire. Data were collected at three time points: baseline, 10 weeks post intervention, and at the 36-week follow-up. We adopted a latent growth model to investigate the initial level and change in PA, objective stress and recovery, and subjective stress at the three measurement time points. The results showed that initial levels of PA (P < 0.001) and objective stress (P = 0.001) and recovery (P < 0.01) were associated with the change in subjective stress. The results persisted after adjustment for intervention group. The present results suggest that high PA and objectively assessed low stress and good recovery have positive effects on changes in subjective stress in the long-term.

The effects of native whey and α-lactalbumin on the social and individual behaviour of C57BL/6J mice.

Milk proteins are the main components of everyday feeding and demonstrate a promising potential to change the mental condition. However, the effects of milk proteins after prolonged use remain poorly understood. The aim of the present study was to compare the effects of two whey proteins (alpha-lactalbumin (alpha-lac) and native whey) with casein on social and individual behaviour in mice. During a 30 d-long dietary intervention, male C57BL/6J mice had ad libitum access to an experimental diet containing 17% (w/w) of one of three protein sources: a-lac, native whey or casein. Mice had voluntary access to a running wheel. Social behaviour (group and resident-intruder activity) was tested at baseline and at the end of the intervention. Half of each dietary group was then withdrawn from the diet and running wheel for 7 d, and social activity and individual behaviour tests (open field, elevated-plus maze, light­dark box and forced swimming) were performed, to evaluate anxiety and depression-like status. The study shows that the long-term ingestion of whey proteins may modulate behaviour when compared with casein. Diet enriched with a-lac exhibited anxiolytic and antidepressive activities while the whey diet improved sociability. The differences between the diet groups were pronounced under the running wheel and the withdrawal of the experimental diet, suggesting that the beneficial effects of the milk proteins are clearer in stressful situations. Diet-induced behavioural changes remained visible for a week after feeding, which suggests that the proteins of the milk whey fraction have prolonged efficacy on the mental state of mice.

The causal element for the lactase persistence/non-persistence polymorphism is located in a 1 Mb region of linkage disequilibrium in Europeans.

Expression of lactase in the intestine persists into adult life in some people and not others, and this is due to a cis-acting regulatory polymorphism. Previous data indicated that a mutation leading to lactase persistence had occurred on the background of a 60 kb 11-site LCT haplotype known as A (Hollox et al. 2001). Recent studies reported a 100% correlation of lactase persistence with the presence of the T allele at a CT SNP at -14 kb from LCT, in individuals of Finnish origin, suggesting that this SNP may be causal of the lactase persistence polymorphism, and also reported a very tight association with a second SNP (GA -22 kb) (Enattah et al. 2002). Here we report the existence of a one megabase stretch of linkage disequilibrium in the region of LCT and show that the -14 kb T allele and the -22 kb A allele both occur on the background of a very extended A haplotype. In a series of Finnish individuals we found a strong correlation (40/41 people) with lactose digestion and the presence of the T allele. The T allele was present in all 36 lactase persistent individuals from the UK (phenotyped by enzyme assay) studied, 31/36 of whom were of Northern European ancestry, but not in 11 non-persistent individuals who were mainly of non-UK ancestry. However, the CT heterozygotes did not show intermediate lactase enzyme activity, unlike those previously phenotyped by determining allelic transcript expression. Furthermore the one lactase persistent homozygote identified by having equally high expression of A and B haplotype transcripts, was heterozygous for CT at the -14 kb site. SNP analysis across the 1 megabase region in this person showed no evidence of recombination on either chromosome between the -14 kb SNP and LCT. The combined data shows that although the -14 kb CT SNP is an excellent candidate for the cause of the lactase persistence polymorphism, linkage disequilibrium extends far beyond the region searched so far. In addition, the CT SNP does not, on its own, explain all the variation in expression of LCT, suggesting the possibility of genetic heterogeneity.

Wide variations in the testing of lactose tolerance: results of a questionnaire study in Finnish health care centres.

About 70% of the world's adult population is unable to digest lactose, the sugar found naturally only in milk. This disability leads to gastrointestinal symptoms called lactose intolerance. In Finland, many patients visit health care centres because they are suffering from gastrointestinal symptoms. A few of them are diagnosed as being lactose intolerant. However, a far larger number diagnose themselves as suffering from lactose intolerance. Therefore the diagnostic tests used should be carefully validated and standardized in clinical laboratories throughout the country. The aim of this questionnaire study was to clarify the situation centres with adult patients in Finnish health care and to try to standardize procedures for administering lactose tolerance tests.

Temperature of a test solution influences abdominal symptoms in lactose tolerance tests.

In lactose maldigesters, retarding gastric emptying (food/pharmaceuticals) improves tolerance to lactose. The role of temperature of test solution on the indicators of lactose intolerance was studied. After an overnight fast, 10 lactose maldigesters ingested, in three sessions, 50 g lactose in a randomized cross-over trial. The solutions were at temperatures of 20-21 degrees C (room temperature), 2-3 degrees C (cold) and 55-58 degrees C (hot). Gastrointestinal symptoms and indicators measuring lactose absorption were recorded. Abdominal pain was noticeably increased by the modification of temperature. The cold solution reduced flatulence and abdominal bloating, whereas the hot solution increased bloating and borborygmi. Breath hydrogen excretion tended to be augmented and retarded after cold solution. The temperature of the solution used in a lactose tolerance test affects the gastrointestinal symptoms, but has only minor effects on the other indicators of lactose maldigestion. The constant tendencies observed suggest that a room temperature solution is to be recommended for testing lactose digestion.

Ibuprofen augments gastrointestinal symptoms in lactose maldigesters during a lactose tolerance test.

BACKGROUND: Clinical symptoms during lactose tolerance test mimic those seen after therapeutic administration of prostaglandins, and resemble inflammatory processes. AIM: To investigate the possibility that lactose-induced gastrointestinal symptoms are associated with prostaglandins and/or nitric oxide. METHODS: After an overnight fast, nine maldigesters ingested lactose or sucrose with or without an inhibitor of prostaglandin synthesis (ibuprofen), in a randomised double-blind crossover trial. Gastrointestinal symptoms, concentrations of PGE2-M in blood and urine, and urinary 6-keto PGF1alpha (as indicators of prostaglandin synthesis), and urinary nitrate and nitrite as well as cyclic GMP excretions (as indicators of nitric oxide formation), were measured. RESULTS: Ibuprofen increased the first 3-h symptom scores (flatulence + borborygmi + abdominal bloating + pain) caused by lactose (P=0.008) but not sucrose. The concentrations of PGE2-M in the plasma and in the urine were unaffected. Lactose increased the urinary excretion of 6-keto PGF1alpha by about 30% (P=0.17), which was inhibited by ibuprofen (P=0.02). The production of nitric oxide was unaffected by lactose or ibuprofen. CONCLUSION: The inhibition of prostaglandin synthesis intensified gastrointestinal symptoms in lactose maldigesters, suggesting a negligible role for prostanoids in lactose-induced symptoms.

Influence of the pharmacological modification of gastric emptying on lactose digestion and gastrointestinal symptoms.

BACKGROUND: In lactose maldigesters the ingestion of food which retards gastric emptying improves tolerance to lactose. AIM: To study the effects of the pharmacological modification of gastric emptying on the speed of development of lactose-induced symptoms. METHODS: After an overnight fast, 18 lactose maldigesters were given, in a randomized double-blind study design at 1-week intervals, either propantheline (as bromide 15 mg), metoclopramide (as hydrochloride 10 mg) or placebo, in identical capsules, 60 min before ingesting 50 g lactose coloured with 1 g carmine dye (to measure gastrointestinal transit time). Gastrointestinal symptoms, urinary galactose excretion, and breath hydrogen and blood glucose concentrations were recorded. RESULTS: The propantheline-induced prolongation of gastric emptying improved tolerance to lactose, as measured by reduced area under the gastrointestinal symptom score curve 0-12 h, compared to placebo (by 26%) (P < 0.05) or metoclopramide (by 30%) (P < 0.05). The total hydrogen excretion AUC (180 min follow-up) increased by 15% after metoclopramide as compared with placebo (P = 0.18). Propantheline decreased this variable by 15% from placebo (P = 0.17). No significant differences in blood glucose, urinary galactose or gastrointestinal transit time were found. CONCLUSIONS: In an oral lactose tolerance test, delaying gastric emptying with propantheline improved tolerance in lactose maldigesters, as measured by diminished gastrointestinal symptoms and reduced breath hydrogen concentration.

Comparison of a portable breath hydrogen analyser (Micro H2) with a Quintron MicroLyzer in measuring lactose maldigestion, and the evaluation of a Micro H2 for diagnosing hypolactasia.

The measurement of hydrogen in exhaled air and changes in the concentration of blood glucose and urine galactose excretion are indirect methods of diagnosing hypolactasia. The aim of this study was to compare a portable breath hydrogen analyser (Micro H2) with a widely used model (Quintron MicroLyzer) and to compare them with the blood glucose, urine galactose, and gastrointestinal symptoms in the lactose tolerance test. After an overnight fast, 44 volunteers (18-66 y) ingested 50 g lactose in a single oral dose. Changes in exhaled breath hydrogen concentrations were measured with the two analysers, and changes in blood glucose and urinary galactose were assayed for 4 h and used as a reference. Eighteen subjects were diagnosed as maldigesters according to our gold standard of at least two positive tests out of the three: breath hydrogen by Quintron, blood glucose concentration, and urine galactose excretion. The highest increase in the breath hydrogen concentration over the baseline was highly variable: 44-366 ppm (Micro H2) or 27-187 ppm (Quintron MicroLyzer). The sensitivity, specificity, and positive and negative predictive values of the Micro H2 compared to the gold standard were 83%, 96%, 94% and 89%, respectively. Overall agreement was 91% (95% CI 78-97%). Compared to the Quintron, the diagnoses were identical in 100% of the cases (92-100%). Thus, for diagnosing hypolactasia, the Micro H2 appeared as reliable for measuring breath hydrogen concentrations as Quintron MicroLyzer commonly used in oral lactose tolerance tests.

Age and continuous lactose challenge modify lactase protein expression and enzyme activity in gut epithelium in the rat.

The activity of lactase enzyme declines after weaning. This study was to investigate changes in the lactase expression in the whole gastrointestinal tract during the development and the possibility that this and activity can be induced by lactose. Expression of lactase protein in the gut of 1-12-weeks old rats was studied by immunocytochemistry. Possible induction was evaluated by immunohistochemical and biochemical techniques in 8-week-old rats after lactose challenge for seven days. Lactase immunoreactivity was detected only in the small intestine and it decreased 20% during the week after weaning. A steady level of 40% lower than in the sucklings was found in the adult rats. In the lactose-challenged rats the optical density of immunoreactivity increased by about 30% in those that consumed the highest concentration of lactose. In the proximal jejunum, elevation of the enzymatic activity was three-fold. In the rat lactase protein expression decreased rapidly after weaning and expression and activity were induced by lactose-rich diet, most notably in the proximal jejunum.