Riikka Nevala

Soy based diet attenuates the development of hypertension when compared to casein based diet in spontaneously hypertensive rat

The purpose of this study was to compare the effects of soy and casein based diets on blood pressure and cardiovascular functions in male and female spontaneously hypertensive rats (SHR). The systolic blood pressure was measured at the beginning and at the end of study. After a five week supplementation period with three different diets, the rats were decapitated and arterial responses and the weight-to-body weight-ratios of the organs were studied. The development of hypertension was attenuated in both female and male rats on soy protein diet when compared to the casein diet. Soy based diet lowered serum total cholesterol level when compared to the control diet. Both casein and soy protein supplementation in diet induced a significant renal hypertrophy in both female and male SHR rats when compared to SHR rats on the control diet. Soy protein supplementation reduced significantly serum estradiol-17beta concentration when compared to the control diet. There were no differences in the serum testosterone concentrations between the diet groups. When compared to the casein based diet the soy based diet attenuated the development of hypertension and decreased serum total cholesterol level in SHRs. These effects were independent of gender. The mechanisms and clinical importance of these findings remain to be clarified.

Plant derived estrogens relax rat mesenteric artery in vitro

The aim of this study was to investigate whether plant derived estrogens have the same relaxing effects in vitro as estradiol-17beta on arterial smooth muscle. The mesenteric arterial rings of female and male Wistar rats were studied. The relaxing effects of estradiol-17beta, genistein, daidzein and beta-sitosterol were determined, with particular focus on the role of endothelium. B-sitosterol had no relaxing effect on the arteries. Estradiol-17beta, genistein and daidzein relaxed noradrenaline, potassium chloride and calcium chloride precontracted arterial rings endothelium-independently. The relaxation responses were also independent of gender. Neither the removal of endothelium, nor the inhibition prostacyclin or nitric oxide synthesis, had any effect on the relaxation responses. The exact mechanism of these findings is still unclear.

Yoghurt containing galacto-oligosaccharides, prunes and linseed reduces the severity of mild constipation in elderly subjects

Objective:Constipation is a common problem in the elderly. Dietary fibre is recommended for its treatment. The aim was to examine whether yoghurt containing galacto-oligosaccharides (GOS), prunes and linseed relieve constipation in elderly subjects.Design:A randomized, double-blinded, cross-over study.Setting:Free-living subjects.Subjects:A group of 43 elderly subjects with self-reported constipation (mean age 76 years, range 61–92 years, 32 females, 11 males).Interventions:The study consisted of a 2-week baseline period and 2, 3-week dietary interventions, with a 2-week wash-out period between the interventions. During the interventions, the subjects ingested, in random order, 260 g/day of either control yoghurt or test yoghurt containing GOS (12 g/day), prunes (12 g/day) and linseed (6 g/day). The use of laxatives was controlled and only allowed after 2 days without defecation.Results:Defecation frequency was 5.7 times/week during the baseline period. During the test yoghurt period, defecation frequency was higher (8.0 vs 7.1 times/week, P=0.011), defecation was easier (on the scale 0–3, 1.3 vs 1.5, P=0.010), and there was a tendency towards softer stools (on the scale 0–3, 2.1 vs 2.2, P=0.059) compared with the control yoghurt period. The subjects felt that the test yoghurt relieved constipation more effectively than the control yoghurt (P=0.005). The sum of gastrointestinal symptoms did not differ between the interventions. The use of laxatives remained constant throughout the study.Conclusions:Daily intake of yoghurt containing GOS, prunes and linseed reduced the severity of constipation in elderly subjects with mild constipation.Sponsorship:Valio Ltd, R&D.

Calcium-sensitive potassium channel inhibitors antagonize genistein- and daidzein-induced arterial relaxation in vitro

Estradiol-17beta relaxes rabbit coronary artery rings via large conductance Ca2+-activated K+-channels (K(Ca)). Genistein and daidzein are plant-derived estrogen-like compounds. The aim of the present study was to investigate whether potassium channels participate in the genistein- and daidzein-induced arterial relaxation like they do in the case of estradiol-17beta. Endothelium-denuded superior mesenteric arterial rings from non-pregnant Wistar female rats were used. At a concentration of 10 microM, estradiol-17beta, genistein and daidzein relaxed noradrenaline precontracted arterial rings, (58 +/- 4%, 45 +/- 5% and 31 +/- 3%, respectively; (n=6-8)). Genistein- and daidzein-induced relaxations were inhibited both by iberiotoxin (1-10 nM) and charybdotoxin (30 nM), the antagonists of large conductance Ca2+-activated K+-channels (K(Ca)). Estradiol-17beta-induced relaxation was reduced by iberiotoxin (30 nM). Estradiol-17beta- and daidzein-induced relaxations were also decreased by apamin (0.1-0.3 microM), an antagonist of small conductance Ca2+-activated K+-channels. The antagonists of voltage-dependent K+-channels (K(V)) (4-aminopyridine), ATP-sensitive K+-channels (K(ATP)) (glibenclamide), or inward rectifier K+-channels (KIR) (barium) had no effect on the relaxation responses of any of the compounds studied. Estrogen receptor antagonist tamoxifen did not inhibit the relaxations. In conclusion, in the noradrenaline precontracted rat mesenteric arteries, the relaxations caused by estradiol-17beta, genistein and daidzein were antagonized by large and small conductance K(Ca)-channel inhibitors, suggesting the role of these channels as one of the relaxation mechanisms.

Replacement of salt by a novel potassium- and magnesium-enriched salt alternative improves the cardiovascular effects of ramipril.

1 The influence of salt (sodium chloride; NaCl) (an additional 6% in the diet) and that of a novel sodium‐reduced, potassium‐, magnesium‐, and l‐lysine‐enriched salt alternative on the cardiovascular effects of ramipril was studied in stroke‐prone spontaneously hypertensive rats in a 6‐week study. The intake of sodium chloride was adjusted to the same level by adding the salt alternative at a 1.75 times higher amount than regular salt. 2 Salt produced a marked rise in blood pressure and induced cardiac hypertrophy and significant mortality, while the salt alternative neither increased blood pressure nor caused any mortality and produced less cardiac hypertrophy than salt. 3 Ramipril treatment at a daily dose of 3 mg kg−1normalized blood pressure and prevented the development of cardiac hypertrophy of rats on control diet. These effects of ramipril were blocked by the addition of salt but were only slightly attenuated by the addition of the salt alternative. The mortality in the salt group was prevented by ramipril. 4 Responses of mesenteric arterial rings in vitro were examined at the end of the study. Salt, but not the salt alternative, increased vascular contractile responses to noradrenaline. Ramipril treatment improved the arterial relaxation responses to acetylcholine and to sodium nitroprusside. The vascular relaxation enhancing effect of ramipril was blocked by salt but only slightly attenuated by the salt alternative. 5 Ramipril treatment did not significantly increase plasma renin activity in the presence or in the absence of salt supplementation. The salt alternative did not cause hyperkalaemia, either alone or in combination with ramipril treatment. 6 Both salt supplementations, irrespective of ramipril treatment, induced a six to eight fold increase in the urinary excretion of calcium. There was an expected 90 to 140% rise in the urinary excretion of magnesium and 200% rise in the urinary excretion of potassium in the salt alternative group. Salt also produced an approximately 50% increase in magnesuria. 7 Our findings suggest that replacement of salt by the potassium‐, magnesium‐ and l‐lysine‐enriched salt alternative improves the cardiovascular effects of ramipril. In the present study the beneficial effect was related to the increased intakes of potassium and/or magnesium and l‐lysine from the salt alternative because the amount of sodium chloride was the same.

Genistein treatment reduces arterial contractions by inhibiting tyrosine kinases in ovariectomized hypertensive rats

The aim of the present study was to evaluate the vascular effects of genistein in a short-term study. The ovariectomized spontaneously hypertensive rats (SHR) were divided into four groups (n = 8 in each), which received the following subcutaneous treatments either for 2 days or for 2 weeks: (1) solvent control (96% dimethylsulphoxide (DMSO) 1 ml/kg), (2) estradiol-17beta (25 microg/kg), (3) genistein (2.5 mg/kg; low-dose), and (4) genistein (25 mg/kg; high-dose). The renal arterial rings were studied using organ bath system. The renal artery contractions were attenuated by the 2-day low-dose genistein treatment as follows: angiotensin II (46%), noradrenaline (42%) KCl (36%), and endothelin-1 (34%). Only the angiotensin II-induced contractions were reduced by the 2-week treatment with estradiol-17beta (38%) and with the low-dose of genistein (31%). The 2-day genistein treatment reduced tyrosine phosphorylation, while the other treatments or treatment times had no effect. The 2-day low-dose genistein treatment had no estrogenic effect on the uterine morphology. The mechanism for attenuated contractility in the renal arteries after the 2-day low-dose genistein treatment is independent of the estrogenic effect of genistein, but is due to the tyrosine kinase inhibitory property of genistein.

In School-Aged Children a Combination of Galacto-Oligosaccharides and Lactobacillus GG Increases Bifidobacteria More than Lactobacillus GG on Its Own

The aim of this study was to compare a combination of Lactobacillus GG (LGG) and galacto-oligosaccharides (GOS) with LGG on its own, and their effects on the intestinal microbiota in school-aged children. The randomized, double-blinded, crossover study comprised 30 healthy children. There were two 3-week study periods with a 4-week wash-out period in between. The children ingested daily 65 ml of milk-based fruit juice containing either LGG alone (6.5 × 109 CFU) or LGG plus 2 g of GOS. Symptom diaries were filled during the study periods. Fecal samples were collected at the beginning and end of both study periods. At the end of both study periods, the amount of bifidobacteria was significantly greater after the ingestion of LGG + GOS compared with LGG alone (geometric mean 9.33 × 109 vs. 4.28 × 109 CFU/g, p < 0.001). No significant differences were seen in the amount of lactobacilli or LGG, nor did gastrointestinal symptoms, defecation frequency, consistency of stools or ease of defecation differ between the two study periods. Ingestion of LGG combined with 2 g of GOS increased the bifidobacteria more than LGG on its own and thus GOS clearly has a prebiotic effect in children. The children tolerated well a daily intake of 2 g of GOS.

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.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°C (room temperature), 2-3°C (cold) and 55-58°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.