Prevention of retinoic acid-induced craniofacial abnormalities by folinic acid, and endothelin-1 (ET-1)/dHAND protein and mRNA expression were investigated in mouse embryos using the whole embryo culture, streptavidin–biotin peroxidase complex method, and whole-mount in situ hybridization. In the whole embryo culture, 1·0 and 0·1mm-folinic acid dose dependently prevented branchial region malformations and decreased defects by 93% and 77%, respectively. Folinic acid at concentrations of 1·0 and 0·1mm significantly increased ET-1 and dHAND protein expression levels compared to retinoic acid-exposed values in embryonic branchial areas. Folinic acid also increased ET-1 and dHAND mRNA levels in the same region. The present results suggest that folinic acid may prevent retinoic acid-induced craniofacial abnormalities via increasing ET-1 and dHAND levels in the branchial region during the organogenic period.

Dietary isoflavones, such as genistein and daidzein, are metabolised by the human gut microflora. Case–control studies have disclosed a link between the formation of the daidzein metabolite equol and prostate cancer risk. We evaluated the effects of genistein, daidzein and five metabolites on two prostate cancer cell lines by determining DNA integrity and cell growth. LNCaP cells contain the T877A androgen receptor mutation whereas Los Angeles prostate cancer (LAPC)-4 cells express the wild-type receptor, both of which may affect responses to isoflavones. DNA integrity was determined using the comet assay. Cell growth was assessed by staining DNA with 4′,6′-diamidino-2-pheylindole hydrochloride. Endogenous steroid hormones, but not isoflavones, induced DNA strand breaks. Dihydrotestosterone stimulated the growth of both cell lines. 17β-Oestradiol increased the growth of LNCaP but not LAPC-4 cells, pointing to an involvement of the T877A androgen receptor. Isoflavones did not stimulate growth in either prostate cancer cell line. However, the growth of LNCaP and LAPC-4 cells was suppressed by genistein (inhibitory concentration 50% (IC50) 39·7μmo/, 37·2μmo/) and by equol (IC50 53·8μmo/, 35·1μmo/). O-desmethylangolensin inhibited the growth of LAPC-4 cells (IC50 45·2μmo/), but not of LNCaP cells. In conclusion, isoflavones do not damage DNA or promote growth of androgen-dependent prostate cancer cells. Several isoflavones, including the reduced daidzein metabolites equol and O-desmethylangolensin, suppress cancer cell growth. Taken together, these data suggest a contribution of gut-formed isoflavone metabolites to the beneficial effects of dietary isoflavones on prostate cancer risk.

Studies have demonstrated that isolated soya protein (ISP) can slow the progression of renal injury, reduce blood pressure and improve the serum lipid profile in experimental animals and human subjects. The mechanisms and components of soya responsible have not been fully established. The present study was designed to evaluate the effects of the hydrophilic supernatant fraction (SF) and the hydrophobic precipitate fraction (PF) isolated from soya protein hydrolysate on renal function, lipid metabolism and blood pressure in five-sixths nephrectomized rats. Experimental animals were subjected to a nephrectomy and allocated to four groups (180g casei/g, 180g IS/g, 100g casei/g with 80g S/g, and 100g casei/g with 80g P/g). The SF group had the most significant decreases in blood pressure and total cholesterol, as well as a significantly retarded progression of the experimentally induced renal disease, compared with the other groups. The PF group exhibited a significantly increased faecal excretion of total steroids. The serum creatinine, level of proteinuria, total cholesterol and LDL-cholesterol concentrations, and blood pressure were significantly reduced, and HDL-cholesterol was significantly increased, in the ISP and PF groups compared with the casein group, but no significant differences were observed between the ISP and PF groups. These results suggest that both soya protein hydrolysate fractions favourably affected chronic renal failure induced by a five-sixths nephrectomy, and the hydrophilic fraction of soya protein hydrolysate had the most pronounced effect on attenuating hypertension and slowing the progression of renal disease.

Equol, a derivative of daidzein produced by enterobacteria, has greater activity as a phyto-oestrogen compared with daidzein. Difructose anhydride III (DFAIII) is a newly manufactured non-digestible disaccharide with unique fermentation properties. The present study evaluated the prebiotic effects of DFAIII on equol production and on plasma cholesterol concentrations related to the changes in equol production. We compared plasma equol concentrations at 10.00 and 18.00 hours and faecal isoflavone excretion in three groups of seven rats (male Wistar-ST strain, 6 weeks old) fed a basal diet or a DFAIII or fructooligosaccharide (15/g diet) diet containing 1g soya isoflavone/g diet for 20d. Equol concentrations in the DFAIII group were higher than in the control and fructooligosaccharides groups, especially in the later phase of the light period (18.00 hours) throughout the experiment. Daizein and genistein concentrations did not change between the diet groups. The faecal ratios of equol:daidzein were very high in all groups, but the ratios were higher in the DFAIII group than the control and fructooligosaccharide groups on day 3, and this tendency continued throughout the experiment. On day 20, the plasma total cholesterol concentration was lowest in the DFAIII group. Additionally, the cholesterol concentrations were inversely correlated to plasma equol concentration in all the rats. In conclusion, DFAIII efficiently enhanced plasma equol concentrations, which may be associated with an increase in equol production and a decrease in equol degradation by enterobacteria. Higher plasma equol concentrations may contribute to the hypocholesterolaemic effect of DFAIII feeding.

Three 8-week growth experiments were conducted to quantify the requirements of the fingerling Cirrhinus mrigala for the dietary branched-chain amino acids valine (experiment 1), isoleucine (experiment 2) and leucine (experiment 3). Six isonitrogenous (400/g) and isoenergetic (17·90k/) test diets were formulated with a gradation of 2·5/g for each test amino acid, valine (7·5–20/g), isoleucine (5·0–17·5/g) and leucine (7·5–20/g), and fed to randomly stocked fish in circular troughs. In experiment 1, the maximum weight gain (312%), best feed conversion ratio (FCR; 1·45) and best protein efficiency ratio (PER; 1·72) were obtained in fish fed 15·0g dietary valin/g. In experiment 2, the highest weight gain (317%), best FCR (1·47) and best PER (1·70) were recorded at 12·5g dietary isoleucin/g, and in experiment 3, the highest weight gain (308%), best FCR (1·46) and best PER (1·71) were noted at 15·0g dietary leucin/g. A quadratic regression analysis of weight gain, FCR and PER data showed an optimum requirement at 15·9, 15·0 and 14·8/g for valine, 13·2, 12·3 and 12·1/g for isoleucine and 15·6, 15·4 and 15·1/g for leucine in dry diets. Low body moisture and higher protein were noted in fish fed diets containing 15·5, 12·5 and 15·0g valine, isoleucine and leucine per kg, respectively. Body fat increased with increasing levels of the branched-chain amino acids. On the basis of a regression analysis of growth data, it is recommended that a diet for C. mrigala should contain valine at 15·2, isoleucine at 12·6 and leucine at 15·4/g dry diet, corresponding to 38·0, 31·5 and 38·5/g dietary protein, respectively.

Experimental butters with a high content of trans-18:1 fatty acids an/r cis-9,trans-11-18:2 (rumenic acid; RA) were fed to thirty-six New Zealand White rabbits to investigate their effects on adipose tissue (AT) and liver lipogenic activities. Animals received one of three atherogenic (0·2% cholesterol) diets containing 12% butter with either a standard fatty acid composition (rich in saturated fatty acids), rich in trans-10-18:1 (T10 diet) or in trans-11-18:1 plus RA (T11+ RA diet) for 6 or 12 weeks. The ingestion of butters rich in trans fatty acids an/r RA for 6 weeks had little or no effect on liver and AT lipogenesis. The ingestion for 12 weeks of butter rich in T11 + RA decreased perirenal AT weight, lipogenic enzyme and lipoprotein lipase activities, without affecting liver lipid concentration or lipogenic activities except for a decrease in glycerol-3-phosphate dehydrogenase activity. Similar trends, but of a lower magnitude, were observed in rabbits fed the T10 diet for 12 weeks. Ingestion of the T10 or T11 + RA diets for 6 or 12 weeks had no significant effect on plasma metabolites and hormones except for glucose which increased at 6 weeks in the T10 group. Plasma leptin concentration was positively correlated with AT weight but did not differ between the three diets. In conclusion, the supply of butters rich in either T10 or T11 + RA in an atherogenic diet for 12 weeks decreased rabbit AT lipogenesis, with a more marked effect of the T11 + RA diet, but had no effect on liver lipogenesis.

Exercise training and regular physical activity increase oxidation of fat. Enhanced oxidation of fat is important for preventing lifestyle diseases such as hypertension and obesity. The aim of the present study in rats was to determine whether intake of dietary soya protein and exercise training have an additive effect on the activity and mRNA expression of enzymes involved in skeletal muscle fatty acid oxidation. Male Sprague–Dawley rats (n 32) were assigned randomly into four groups (eight rats per group) and then divided further into sedentary or exercise-trained groups fed either casein or soya protein diets. Rats in the exercise groups were trained for 2 weeks by swimming for 120mi/, 6/eek. Exercise training decreased hepatic triacylglycerol levels and retroperitoneal adipose tissue weight and increased skeletal muscle carnitine palmitoyltransferase 1 (CPT1) activity and mRNA expression of CPT1, β-hydroxyacyl-CoA dehydrogenase (HAD), acyl-CoA oxidase, PPARγ coactivator 1α (PGC1α) and PPARα. Soya protein significantly decreased hepatic triacylglycerol levels and epididymal adipose tissue weight and increased skeletal muscle CPT1 activity and CPT1, HAD, acyl-CoA oxidase, medium-chain acyl-CoA dehydrogenase, PGC1α and PPARα mRNA levels. Furthermore, skeletal muscle HAD activity was the highest in exercise-trained rats fed soya protein. We conclude that exercise training and soya protein intake have an important additive role on induction of PPAR pathways, leading to increased activity and mRNA expression of enzymes involved in fatty acid oxidation in skeletal muscle and reduced accumulation of body fat.

Glycaemic index (GI) values for fourteen commonly eaten carbohydrate-rich foods processed by various methods were determined using ten healthy subjects. The foods studied were round leaf yellow yam (Dioscorea cayenensis), negro and lucea yams (Dioscorea rotundata), white and sweet yams (Dioscorea alata), sweet potato (Solanum tuberosum), Irish potato (Ipomoea batatas), coco yam (Xanthosoma spp.), dasheen (Colocasia esculenta), pumpkin (Cucurbita moschata), breadfruit (Artocarpus altilis), green banana (Musa sapientum), and green and ripe plantain (Musa paradisiaca). The foods were processed by boiling, frying, baking and roasting where applicable. Pure glucose was used as the standard with a GI value of 100. The results revealed marked differences in GI among the different foods studied ranging from 35 (se 3) to 94 (se 8). The area under the glucose response curve and GI value of some of the roasted and baked foods were significantly higher than foods boiled or fried (P<0·05). The results indicate that foods processed by roasting or baking may result in higher GI. Conversely, boiling of foods may contribute to a lower GI diet.

Epidemiological data suggest that those who consume a diet rich in quercetin-containing foods may have a reduced risk of CVD. Furthermore, in vitro and ex vivo studies have observed the inhibition of collagen-induced platelet activation by quercetin. The aim of the present study was to investigate the possible inhibitory effects of quercetin ingestion from a dietary source on collagen-stimulated platelet aggregation and signalling. A double-blind randomised cross-over pilot study was undertaken. Subjects ingested a soup containing either a high or a low amount of quercetin. Plasma quercetin concentrations and platelet aggregation and signalling were assessed after soup ingestion. The high-quercetin soup contained 69mg total quercetin compared with the low-quercetin soup containing 5mg total quercetin. Plasma quercetin concentrations were significantly higher after high-quercetin soup ingestion than after low-quercetin soup ingestion and peaked at 2·59 (sem 0·42) μmo/. Collagen-stimulated (0·5μ/l) platelet aggregation was inhibited after ingestion of the high-quercetin soup in a time-dependent manner. Collagen-stimulated tyrosine phosphorylation of a key component of the collagen-signalling pathway via glycoprotein VI, Syk, was significantly inhibited by ingestion of the high-quercetin soup. The inhibition of Syk tyrosine phosphorylation was correlated with the area under the curve for the high-quercetin plasma profile. In conclusion, the ingestion of quercetin from a dietary source of onion soup could inhibit some aspects of collagen-stimulated platelet aggregation and signalling ex vivo. This further substantiates the epidemiological data suggesting that those who preferentially consume high amounts of quercetin-containing foods have a reduced risk of thrombosis and potential CVD risk.

The aim of the study was to determine the effect of consuming meals with different fatty acid compositions on the postprandial changes over 6h in plasma triacylglycerol, NEFA, total cholesterol, glucose and insulin concentrations in middle-aged men and women. Men (n 11; 58 (5) years) and women (n 11; 56 (4) years) consumed four test meals with a similar macronutrient energy content in random order: a reference meal based on the habitual pattern of fatty acid intake in the UK, a meal with an increased (155%) linoleic acid (LA) to α-linolenic acid (αLNA) ratio (high LA:αLNA), a meal with increased (23%) MUFA content (high MUFA) and a meal with increased (583%) EPA and DHA content (high EPA+DHA). The high-LA:αLNA and high-EPA+DHA meals selectively increased the ratio of LA to αLNA (men 341%; women 310%) and the EPA+DHA (men 414%; women 438%) concentration in plasma triacylglycerol. The high-MUFA meal did not alter the change in MUFA content of the plasma. Plasma triacylglycerol, NEFA, glucose and insulin, but not total cholesterol, concentrations changed significantly after each meal. There was no significant effect of meal fatty acid composition or gender on maximum change in concentration, time to maximum concentration or area under the curve of any of the metabolites measured in the blood. These results suggest that differences in meal fatty acid composition exert little or no effect on postprandial changes in plasma lipids, glucose and insulin concentrations.

Dietary patterns have been identified in adults, but less is known about children and adolescents. For the first time, we have investigated lifestyle patterns combining diet and physical activity in 12-year-old French preadolescents and examined their association with sociodemographic factors. Physical activity, sedentary activities and dietary habits were assessed by questionnaires given to 2724 students in 2001. Family income tax and parents' educational level, as indicators of socio-economic status, and the size of the residence commune were obtained from parents. After adjusting for socio-economic status, physical activity was positively associated with a consumption of frui/egetable/ruit juice on more than four occasions in the previous 24h (P<0·001). Sedentary activities were positively associated with the consumption of French fries or potato chips (P<0·001), with sweetened drink as the most usual drink (P<0·001) and with nibbling while watching television (P<0·001), and inversely associated with a high consumption of frui/egetable/ruit juice (P=0·04). Multiple correspondence analysis identified two independent axes and specific combinations of behaviour: one axis characterised by sedentary activity, sweetened drink as the most usual drink, the consumption of French fries or potato chips and nibbling while watching television; a second one associating physical activity and the consumption of frui/egetable/ruit juice. Both socio-economic proxies were associated with the former axis (P<0·001). The size of the residence commune was associated with the latter (P<0·1). Combinations of diet and physical activity habits were identified in adolescents, indicating that prevention programmes targeting both behaviours may have an enhanced outcome.

The disease risk indicator plasma total homocysteine (tHcy) is influenced by genetic and environmental factors, including folate and vitamin B12 status. Little is known about the determinants of tHcy in rural West Africa. We explored the hypothesis that tHcy in rural Gambian adults might vary between the sexes and physiological groups, an/r with folate and vitamin B12 status. Comparisons were made with a British national survey. Non-pregnant Gambian women (n 158) had tHcy concentrations (geometric mean 9·0μmo/) similar to those of non-pregnant UK women (n 449; 9·4μmo/), whereas pregnant Gambian women (n 12) had significantly lower values (6·2μmo/). Gambian men (n 22) had significantly higher values (14·7μmo/) than British men (n 354; 10·8μmo/). Gambian lactating women and British men and women exhibited significant inverse relationships between loge(tHcy) and folate status; however, only the British subjects exhibited significant inverse relationships between loge(tHcy) and vitamin B12 status. In the British sample, and in Gambian lactating women, folate and vitamin B12 status variations together accounted for 20–25% of the variation in loge(tHcy). Within the UK, black-skinned adults had folate and tHcy levels similar to those of their white-skinned counterparts, but significantly higher vitamin B12 values. We conclude that, whereas folate and vitamin B12 status are similar between British and rural Gambian populations, tHcy is higher in Gambian men and lower in pregnant Gambian women, and that serum vitamin B12 values appear to be higher in black-skinned than white-skinned British subjects. Possible reasons are discussed.

High plasma concentrations of ascorbic acid, a marker of fruit and vegetable intake, are associated with low risk of coronary artery disease. Whether this relationship is explained by a reduction in systemic inflammation is unclear. We investigated the relationship between ascorbic acid plasma concentration and coronary artery disease risk, and in addition whether this relationship depended on classical risk factors and C-reactive protein (CRP) concentration. We used a prospective nested case–control design. The study consisted of 979 cases and 1794 controls (1767 men and 1006 women). Increasing ascorbic acid quartiles were associated with lower age, BMI, systolic and diastolic blood pressure, and CRP concentration, but with higher HDL-cholesterol concentration. No associations existed between ascorbic acid concentration and total cholesterol concentration or LDL-cholesterol concentration. When data from men and women were pooled, the risk estimates decreased with increasing ascorbic acid quartiles such that people in the highest ascorbic acid quartile had an odds ratio for future coronary artery disease of 0·67 (95% CI 0·52, 0·87) compared with those in the lowest quartile (P for linearity=0·001). This relationship was independent of sex, age, diabetes, smoking, BMI, LDL-cholesterol, HDL-cholesterol, systolic blood pressure and CRP level. These data suggest that the risk reduction associated with higher ascorbic acid plasma concentrations, a marker of fruit and vegetable intake, is independent of classical risk factors and also independent of CRP concentration.

Relationships between Se and Hg in erythrocytes, and between these indices and intakes of fish and other foods, were studied as an adjunct to the British National Diet and Nutrition Survey (NDNS) of young people aged 4–18 years. Hg was measured in 965 packed erythrocyte samples by inductively coupled plasma mass spectrometry. Fe measurements permitted the calculation of whole-blood Hg. Erythrocyte and plasma Se, and 7d weighed dietary intake estimates, were available. Erythrocyte Hg was positively skewed, normalised by log-transformation. It was 20% higher in girls than boys (3·17 v. 2·65nmo/, P=0·004), and increased with age in boys but not girls. It was directly and strongly correlated with erythrocyte or plasma Se. Hg and Se concentrations were directly correlated with fish intake. Certain other food groups were also directly correlated with Se and Hg concentrations, but less strongly than for fish. The strength and consistency of the relationship between erythrocyte Hg and Se suggests an important chemical link. Previous studies suggest that Se protects against the toxicity of Hg, and that fish is an important source of both. No toxic levels of Hg were found, which is reassuring because of the known health benefits of fish consumption, especially oily fish. Hg intakes need to be monitored, especially in women of child-bearing age, to ensure that Food Standards Agency guidelines are met.

The present study examined the association between dietary factors and metabolic syndrome in a 7-year follow-up of Japanese–Brazilians. In 1993, a survey estimated the prevalence of diabetes in a Japanese–Brazilian population aged 40–79 years. From 647 subjects studied at baseline, 394 (60·9%) participated in a second survey (2000); after exclusion of subjects with self-reported diseases, 23·4% (n 151) were included in the present analysis. Metabolic syndrome diagnosis was based on the National Cholesterol Education Program criteria modified for Asians. Food intake was assessed by a validated food-frequency questionnaire. At baseline, mean ages were 56·1 (sd 9·7) and 54·7 (sd 10·6) years for men and women, respectively. Similar cumulative incidence rates of the metabolic syndrome were found in both sexes (36·9 (95% CI 26·6, 48·1)% for men and 38·8 (95% CI 27·1, 51·4) % for women). In 1993, mean values of blood pressure, waist circumference for men and 2h plasma glucose for both sexes were higher among subjects who developed metabolic syndrome when compared with those who did not. Comparisons of nutrient intakes between subsets of subjects who developed or did not develop metabolic syndrome showed an association of protein intake with the syndrome only in men (96·4 (sd 56·8) v. 74·3 (sd 26·0) /; P<0·05). Odds ratios of the metabolic syndrome across tertiles of food groups intake showed that among men the highest tertile of red meat consumption was associated with a 4·7-fold increase in risk of developing the syndrome, after adjustments for confounders. However, the statistical significance of this model disappeared when saturated fatty acids were added. The data raised the possibility of a role of red meat consumption for the occurrence of metabolic syndrome in Japanese–Brazilian men. The present findings may have implications for the prevention of metabolic syndrome in this high-risk population.

A purified pancreatic α-amylase inhibitor (α-AI) from white beans (Phaseolus vulgaris) was administered orally (100m/g body weight dissolved in 9g NaC/) for 22d to non-diabetic (ND) and type 2 diabetic (neonatal diabetes models n0-STZ and n5-STZ) male Wistar rats. Mean glycaemia (mmo/) declined from day 4 of the α-AI administration in ND rats (5·48 (sem 0·08) v. 4·39 (sem 0·13); P<0·05), n0-STZ diabetic rats (7·94 (sem 0·42) v. 5·56 (sem 0·32); P<0·01) and n5-STZ diabetic rats (17·34 (sem 2·58) v. 11·93 (sem 1·96)), until the end of treatment: ND (5·22 (sem 0·21) v. 3·97 (sem 0·06); P<0·01); n0-STZ (8·10 (sem 0·19) v. 5·21 (sem 0·30); P<0·01); and n5-STZ (16·36 (sem 2·14) v. 7·69 (sem 1·34); P<0·01). There was a decrease in water intake (m/) in the α-AI-treated diabetic rats: n0-STZ (30 (sem 0·10) v. 22 (sem 1·50); P<0·01) and n5-STZ (76 (sem 5·04) v. 57 (sem 4·85); P<0·01). Food intake (/) decreased in all three groups: ND (23 (sem 0·31) v. 20 (sem 0·03); P<0·05); n0-STZ (22 (sem 0·55) v. 16 (sem 0·98); P<0·01); and n5-STZ (31 (sem 0·58) v. 23 (sem 1·20); P<0·01). The enterocyte sucrase and maltase activities (/ proteins) were high (P<0·01) in the untreated diabetic rats, n0-STZ (45 (sem 4) and 152 (sem 10), respectively) and n5-STZ (67 (sem 12) and 151 (sem 10), respectively) with respect to the ND rats (24 (sem 2) and 74 (sem 10), respectively). After α-AI treatment, enzyme activities declined in both diabetic rats, n0-STZ (21 (sem 2) and 85 (sem 11); P<0·01) and n5-STZ (28 (sem 7) and 75 (sem 19); P<0·05), to values close to those in the ND rats. In conclusion, α-AI significantly reduced glycaemia in both the ND and diabetic animals and reduced the intake of food and water, and normalized the elevated disaccharidase levels of the diabetic rats.

Ca and P are both essential nutrients for bone and are known to affect one of the most important regulators of bone metabolism, parathyroid hormone (PTH). Too ample a P intake, typical of Western diets, could be deleterious to bone through the increased PTH secretion. Few controlled dose–response studies are available on the effects of high P intake in man. We studied the short-term effects of four P doses on Ca and bone metabolism in fourteen healthy women, 20–28 years of age, who were randomized to four controlled study days; thus each study subject served as her own control. P supplement doses of 0 (placebo), 250, 750 or 1500mg were taken, divided into three doses during the study day. The meals served were exactly the same during each study day and provided 495mg P and 250mg Ca. The P doses affected the serum PTH (S-PTH) in a dose-dependent manner (P=0·0005). There was a decrease in serum ionized Ca concentration only in the highest P dose (P=0·004). The marker of bone formation, bone-specific alkaline phosphatase, decreased (P=0·05) and the bone resorption marker, N-terminal telopeptide of collagen type I, increased in response to the P doses (P=0·05). This controlled dose–response study showed that P has a dose-dependent effect on S-PTH and increases PTH secretion significantly when Ca intake is low. Acutely high P intake adversely affects bone metabolism by decreasing bone formation and increasing bone resorption, as indicated by the bone metabolism markers.

The effects of two bovine β-casein peptides on the urokinase plasminogen activator (u-PA) system and superoxide anion (SA) production by porcine macrophages and neutrophils activated by phorbol myristate acetate (PMA) were investigated. Macrophages and neutrophils were obtained from fourteen weaned piglets and were cultured in vitro for 24h with or without one of two chemically synthesised peptides: tripeptide leucine–leucine–tyrosine (residues 191–193 of β-casein) (LLY) and hexapeptide proline–glycine–proline–isoleucine–proline–asparagine (residues 63–68 of β-casein). Following incubation, cells were stimulated with 80μM-PMA. Total cell-associated u-PA, membrane-bound u-PA, free u-PA binding sites along with SA production were determined after stimulation with PMA. Both peptides suppressed the u-PA system and SA production of PMA-stimulated macrophages isolated from piglets during weeks 1–2 after weaning. Only the tripeptide LLY suppressed the u-PA system and SA production of PMA-stimulated neutrophils during the same time period. None of the peptides tested had any effect (P>0·05) on the u-PA system and SA production of PMA-stimulated macrophages and neutrophils isolated from the same piglets during weeks 5–6 after weaning. Thus, peptides are effective only in the early post-weaning period. Using cyclic AMP analogues that are highly specific activators of protein kinase A (PKA) or exchange protein directly activated by cyclic AMP-1 (Epac-1), we found that activation of PKA, but not Epac-1, was responsible for the downregulation of the u-PA system, whereas activation of PKA an/r Epac-1 was responsible for the downregulation of SA system in both macrophages and neutrophils.

The in vitro digestion of caprine whey proteins was investigated by a two-step degradation assay, using human gastric juice (HGJ) at pH 2·5 and human duodenal juice (HDJ) at pH 7·5. Different protein and peptide profiles were observed after the first (HGJ) and second (HDJ) enzymatic degradation. The minor whey proteins serum albumin, lactoferrin and Ig were rapidly degraded by HGJ, while α-lactalbumin (α-LA) and β-lactoglobulin (β-LG) were more resistant and survived both 30 and 45min of the enzymatic treatment. Further digestion with HDJ still showed intact β-LG, and the main part of α-LA also remained unchanged. The protein degradation by HGJ and HDJ was also compared with treatment by commercial enzymes, by using pepsin at pH 2·5, and a mixture of trypsin and chymotrypsin at pH 7·5. The two methods resulted in different caprine protein and peptide profiles. The digests after treatment with HGJ and HDJ were screened for antibacterial effects on some selected microorganisms, Escherichia coli, Bacillus cereus, Lactobacillus rhamnosus GG and Streptococcus mutans. Active growing cells of E. coli were inhibited by the digestion products from caprine whey obtained after treatment with HGJ and HDJ. Cells of B. cereus were inhibited only by whey proteins obtained after reaction with HGJ, while the products after further degradation with HDJ demonstrated no significant effect. Screenings performed on cells of Lb. rhamnosus GG and S. mutans all showed no signs of inhibition.