The aim of the present study was to investigate in human subjects whether or not the ingestion of two liquid meals that differed only in their fatty acid composition (due to the addition of olive oil (group O) or sunflowerseed oil (group S) as the source of dietary fat) would lead to differences in the pancreatic enzyme activities secreted into the duodenum. The experiments were performed in eighteen cholecystectomized subjects who, during the 30d period immediately before surgery, modified their habitual diets in such a way that their fat composition would reflect, as far as possible, that of the experimental meals. Lipase (EC 3.1.1.3), colipase, amylase (EC 3.2.1.1), chymotrypsin (EC 3.4.21.1) and trypsin (EC 3.4.21.4) activities were measured in duodenal contents aspirated before and after the ingestion of the test meals. The plasma levels of secretin and cholecystokinin (CCK) were also examined. Duodenal enzyme activities were similar in resting conditions. No significant differences were revealed in postprandial enzyme activities, except for lipase activity, which was higher in group O, probably in relation to the greater plasma CCK concentrations observed in this group. In the absence of enzyme output data, we should not exclude the possibility that the type of dietary fat will affect human pancreatic enzyme secretion to a greater extent than is evident from the present study, for instance through a flow-mediated effect, as we previously observed in dogs.

To examine the effects of dietary docosahexaenoic acid (DHA) on the potential changes in endogenous lipid peroxidation in the liver and kidney, diets containing a fixed amount of vitamin E (VE; RRR-α-tocopherol equivalent; 134 mg/kg diet) and a graded amount of DHA at the levels of 0, 1.0, 3.4 and 8.7% of total dietary energy were fed to rats for 14 d (Expt 1). In Expt 2, diets containing a fixed amount of DHA (8.7% of total dietary energy) and a graded amount of VE at the levels of 54, 134 and 402 mg/kg were fed to rats for 15 d. In Expt 1 it was found that endogenous lipid peroxide contents of the liver and kidney, as measured by thiobarbituric acid value and chemiluminescence intensity, were higher, and their α-tocopherol contents lower than those of the controls, with a gradual increase and decrease in values respectively as the dietary DHA level increased (Expt 1). However, the contents of water-soluble antioxidants, i.e. ascorbic acid and non-protein-SH (glutathione), increased with increases in the dietary DHA level, while the Se-dependent glutathione peroxidase (EC 1.11.1.9) activities did not change or tended to be lower. When the graded level of VE was given to rats in Expt 2, lipid peroxide contents in the liver and kidney did not change significantly in response to the increasing levels of dietary VE, although their α-tocopherol contents were higher than control values, increasing with increases in the dietary VE levels. The lipid peroxide scavengers other than a-tocopherol changed similarly to those in Expt 1. The results obtained in Expts 1 and 2 indicate that DHA enhances the susceptibility of the liver and kidney to lipid peroxidation concomitant with higher levels of DHA in these tissues, as shown by the fatty acid composition. In addition, VE is unable to protect membranes of the liver and kidney rich in DHA from lipid peroxidation, even after ingestion of the highest level of VE. However, the liver lipid peroxide content of the group given the highest level of DHA was not as high as expected, based on the peroxidizability index which was calculated from the fatty acid composition of the liver lipid.

Cholesterol oxidation products (COP) have been reported to influence vital cellular processes such as cell growth, cell proliferation, membrane function and de novo sterol biosynthesis. The objectives of the present study were: (1) to develop an in vitro model using newborn rat kidney (NRK) cells to investigate the actions of COP; (2) to investigate the effect of COP on cell viability, endogenous antioxidant enzymes activities, i.e. superoxide dismutase (EC 1.15.1.1; SOD) and catalase (EC 1.11.1.6; CAT), and the extent of lipid peroxidation in this model; (3) to determine whether the addition of 100–1000 nm-α-tocopherol, β-carotene or butylated hydroxytoluene (BHT) could protect against COP-induced cytotoxicity. NRK cells were cultured in the presence of various concentrations (5–50 μM) of cholesterol or cholestan-3β,5α,6β-triol (cholestantriol) for a period of 24 h. Cholesterol over the range 5–50 μM did not induce cytotoxicity as indicated by the neutral-red-uptake assay or the lactate dehydrogenase (EC 1.1.1.27)-release assay. However, cell viability was compromised by the addition of > 10 μM-cholestantriol (P < 0.05). The addition of β-carotene (100–1000 nM) did not increase cell viability significantly in cholestantriol-supplemented cells. However, the addition of α-tocopherol (1000 nM) and BHT (1000 nM) significantly increased percentage cell viability above that of the cholestantriol-supplemented cells but not back to control levels. SOD and CAT activities in NRK cells significantly decreased (P < 0.05) following incubation with cholestantriol. The addition of > 750 nM-α-tocopherol, β-carotene or BHT returned SOD and CAT activities to that of the control. Lipid peroxidation was significantly induced (P < 0.05) in the presence of cholestantriol. Supplementation of the cells with α-tocopherol (250, 500 or 1000 nM) or BHT (750 or 1000 nM) resulted in a reduction in the extent of lipid peroxidation (P < 0.05). The addition of β-carotene over the concentration range of 250–1000 nM did not reduce lipid peroxidation significantly compared with cells exposed to cholestantriol alone. These findings suggest that addition of exogenous antioxidants may be beneficial in the prevention of COP-induced toxicity in vitro.

Medicago sativa (lucerne) is used as a traditional plant treatment of diabetes. In the present study, administration of lucerne in the diet (62·5 g/kg) and drinking water (2·5 g/l) reduced the hyperglycaemia of streptozotocin-diabetic mice. An aqueous extract of lucerne (1 mg/ml) stimulated 2-deoxy-glucose transport (1·8-fold), glucose oxidation (1·7-fold) and incorporation of glucose into glycogen (l·6-fold) in mouse abdominal muscle. In acute 20 min tests, 0·25–1 mg/ml aqueous extract of lucerne evoked a stepwise 2·5–6·3-fold stimulation of insulin secretion from the BRIN-BD11 pancreatic B-cell line. This effect was abolished by 0·5 mM-diazoxide, and prior exposure to extract did not affect subsequent stimulation of insulin secretion by 10 mM-L-alanine, thereby negating a detrimental effect on cell viability. The effect of extract was potentiated by 16·7 mM-glucose and by 1 mM-3-isobutyl-1-methylxanthine. L-Alanine (10 mM) and a depolarizing concentration of KCI (25 mM) did not augment the insulin-releasing activity of lucerne. Activity of the extract was found to be heat stable and largely acetone insoluble, and was enhanced by exposure to acid and alkali (0·1 M-HCI and NaOH) but decreased 25% with dialysis to remove components with molecular mass <2000 Da. Sequential extraction with solvents revealed insulin-releasing activity in both methanol and water fractions indicating a cumulative effect of more than one extract constituent. The results demonstrate the presence of antihyperglycaemic, insulin-releasing and insulin-like activity in the traditional antidiabetic plant, Medicago sativu.

Thirty-one men (47 (SD 14) years) and thirty-four women (35 (SD 13) years) took part in a 4-week randomized cross-over trial to compare the effect of six mugs of black tea daily v. placebo (water, caffeine, milk and sugar) on blood lipids, bowel habit and blood pressure, measured during a run-in period and at the end of weeks 2, 3 and 4 of the test periods. Compliance was established by adding a known amount of p–aminobenzoic acid (PABA) to selected tea bags, and then measuring its excretion in urine. Mean serum cholesterol values during run-in, placebo and on tea drinking were 5·67 (SD 1·05), 5·76 (SD 1·11) and 5·69 (SD 1·09)mmol/l (P=0·16). There were also no significant changes in diet, LDL-cholesterol, HDL-cholesterol, triacylglycerols, and blood pressure in the tea intervention period compared with placebo. Compared with placebo, stool consistency was softened with tea (P=0·04), and no other differences were found in bowel habit. Results were unchanged when fifteen ‘non-compliers’, whose PABA excretion indicated that fewer than six tea bags had been used, were excluded from the analysis, and when differences between run-in and tea periods were considered separately for those who were given tea first or second.

Since experimental Se deficiency results in a significant increase in plasma cholesterol concentration the present investigation was undertaken to assess further the influence of this deficiency on the expression of proteins involved in hepatic lipid metabolism. Se deficiency was induced by feeding weanling male Wistar rats on a deficient diet for 6 weeks. Hypercholesterolaemia associated with Se deficiency was related to increased 3-hydroxy-3-methylglutaryl-coA (HMG-CoA) reductase (EC 1.1.1.34) activity in liver microsomes as compared with control animals. Hepatic lipoprotein receptor levels (LDL-receptor and HDL-binding proteins, HB1 and HB2) were not significantly affected by Se deficiency, as assessed by immunoblotting. Plasma triacylglycerol concentrations tended to decrease in Se-deficient rats in concert with their reduced post-Triton secretion. There was no significant effect of Se deficiency on the hepatic synthesis of apolipoproteins. These results point to the need for further investigations into the mechanism related to the increased activity of HMG-CoA reductase and the enhanced cholesterogenesis in the liver of Se-deficient rats likely to result from this.

Selenium: Cholesterol: Triacylglycerol: HMG-CoA reductase

To study the fate of l-cysteine and amino acid homeostasis in liver after the inhibition of the trans-sulfuration pathway, rats were treated with propargylglycine (PPG). At 4 h after the administration of PPG, liver cystathionase (EC 4.4.1.1) activity was undetectable, l-cystathionine levels were significantly higher, l-cysteine was unchanged and GSH concentration was significantly lower than values found in livers from control rats injected intraperitoneally with 0.15 M-NaCl. The hepatic levels of amino acids that are intermediates of the urea cycle, l-ornithine, l-citrulline and l-arginine and blood urea were significantly greater. Urea excretion was also higher in PPG-treated rats when compared with control rats. These data suggest a stimulation of ureagenesis in PPG-treated rats. The inhibition of γ-cystathionase was reflected in the blood levels of amino acids, because the L-methionine: l-cyst(e)ine ratio was significantly higher in PPG-treated rats than in control rats; blood concentration of cystathionine was also greater. Histological examination of liver and kidney showed no changes in PPG-treated rats when compared with controls. The administration of N-acetylcysteine (NAC) to PPG-treated rats reversed the changes in blood urea and in liver GSH. These data suggest that when liver l-cysteine production was impaired by the blockage of the trans-sulfuration pathway, the concentration of this amino acid was maintained mainly by an increase in protein degradation and by a depletion in GSH concentration that may spare l-cysteine.

Weanling Wistar rats were fed on diets prepared from grain from areas deficient in I and Se where Keshan disease is endemic. Rats were divided into four groups, each of twelve rats, and received a diet supplemented with: I, Se, I + Se or nothing. At 8 weeks after weaning, myocardial α-glycerophosphate dehydrogenase (EC 1.1.1.8; α-GPD) activity and indices of Se and thyroid hormone status were determined. The group supplemented with iodine had increased plasma thyroxine levels. There was no difference in plasma triiodothyronine concentration between the groups but triiodothyronine levels in heart were reduced in the Se-supplemented group. Se supplementation increased myocardial glutathione peroxidase activity (EC 1.11.1.9) and the type I 5'-deiodinase (EC 3.8.1.4) activity in rat liver, but no type I 5'-deiodinase activity was detected in heart. α-GDP activity in heart was increased in the group supplemented with Se, I or both. There was a significant relationship (P < 0.05) between myocardial α-GDP activity and plasma thyroxine levels but not between α-GDP and myocardial glutathione peroxidase activity. The results indicate that iodine may be more important than Se in energy metabolism in the myocardium, which may give a new insight for the study of the aetiology of Keshan disease in areas where foodstuffs are deficient in both Se and I.

Several clinical reports have shown changes in plasma Se concentration with corticosteroid treatments, but the results have been inconsistent. Few experimental studies have been done on this subject. In the present study the effect of dexamethasone (DEX) treatment on Se concentrations and activities of Se-dependent glutathione peroxidase (EC 1.11.1.9; SeGPx) were examined in adult male ICR mice. In the first experiment, DEX was given via drinking water containing 5 or 50 mg DEX/I. At 1 or 3 weeks of DEX treatment, mice were dissected and the Se concentrations as well as SeGPx activities in various tissues, including plasma, were determined. At 1 week the DEX-treated groups had significantly lower hepatic Se concentrations and significantly higher plasma and cerebral concentrations than the control group. The DEX-treated groups showed lower SeGPx activities in the hepatic cytosol and higher SeGPx activities in the plasma than the saline (9 g NaCl/l)-treated group, in parallel with the changes in Se concentrations. At 3 weeks, neither hepatic nor plasma Se concentrations showed a significant change. In the second experiment, mice were injected subcutaneously with DEX and, thereafter, mice were food-deprived. The DEX-injected groups had higher plasma Se concentrations. A similar finding was obtained also when the DEX- or saline-injected mice were not food-deprived. Thus, the difference between the DEX-treated and control groups was possibly caused by redistribution of tissue Se. These results suggested that the effects of DEX on Se concentrations were tissue dependent and that the higher plasma Se observed in DEX-treated groups might be explained by the release of tissue Se into plasma as plasma SeGPx.

An experiment was conducted to study the efficacy of two tomato pastes and aronia nectar (fruit juice + pulp from the black chokeberry, Aronia melanocarpa Elliot) as inhibitors of nitrosamine production in cancer prophylaxis programmes. White male rats of the Wistar strain were employed in an acute trial. Aminopyrin + sodium nitrite (APSN) were used as precursors for generation of endogenous nitrosamine. The animals were allocated to different dietary groups and fed by intubation with APSN or APSN + food products. Introduction of tomato paste (TP), high-β-carotene tomato paste (HCTP) and aronia nectar (AN) as inhibitors of n−nitrosamine formation exerted a positive effect on blood and liver variables which was demonstrated by decreased concentrations of glutamic-oxaloacetic transaminase (EC 2.6.1.1), glutamic-pyruvic transaminase (EC 2.6.1.2) and uric acid in serum and lipid content in hepatocytes. Animals treated with APSN developed dystrophic changes in liver such as centrolobular necrosis, intense exangia, and enlarged cells with two, often large, pyknotic nuclei, while the structure of livers of rats fed with TP, HCTP or AN was well protected and almost normal. TP had a particularly beneficial effect on serum total protein and albumin concentrations as had AN on the urea value. The inhibitory effect of th food products used is explained by their chemical nature including pH, ascorbic index (ascorbate:nitrate), lycopene and β-carotene contents.

Wistar rats fed on either a high-protein or a protein-free diet were examined to determine their pancreatic hydrolase mRNA stabilities in comparison with those of control animals receiving a standard diet. Actinomycin D was used to inhibit transcription and, after isolating the pancreatic RNA, the specific messengers were quantified by performing dot-blot hybridization with cDNA probes. In the rats fed on a high-protein diet, only the half-lives of anionic trypsinogen I and elastase I (EC 3.4.21.36) were affected. Interestingly, when rats were fed on the protein-free diet, most of the hydrolase mRNA half-lives showed changes, except that corresponding to lipase. In these rats, the half-life values of the mRNA coding for anionic trypsinogen I, chymotrypsinogen and procarboxypeptidase B increased, in sharp contrast with those of the amylase and elastase I mRNA, which decreased. These results strongly suggest that the mechanism whereby the biosynthesis of pancreatic hydrolases is regulated, depending on the presence or absence of proteins in the diet, is not unique and provide evidence that the stability of mRNA encoding most, if not all, the hydrolases in pancreatic cells is modulated by the dietary protein content.

The clinical significance of low serum vitamin B12 levels in elderly people is controversial. We aimed to document the prevalence of a low serum vitamin B12 (<175pmol/l) in patients referred to a geriatric medical unit, and to determine whether haemopoiesis is commonly affected in elderly patients with low serum vitamin B12. We studied prospectively 472 consecutive referrals to a geriatric medical unit; fifty-six (13%) had a low serum vitamin B12 level, of whom nineteen (34%) of the fifty-six also had evidence of Fe deficiency (serum ferritin<45ng/ml). Low vitamin B12 was associated with a raised mean erythrocyte volume (MCV; mean 96·0 (SD 6·7) fl), compared with a control group (91·7 (SD 6·0) fl; P=0·001). However, only thirteen (23%) of the fifty-six patients with a low vitamin Blz had an MCV≥100 fl. Mean haemoglobin (Hb) levels were not significantly reduced in those with a low vitamin B12. In a subsequent study the haematological response to intramuscular hydroxocobalamin was examined in thirty-four patients with a low serum vitamin B12. Treatment resulted in a significant fall in MCV and rise in Hb; these effects could be detected both in those patients with an initially normal full blood count (change in MCV -1·2 (SD 1·2); Hb + 0·5 (SD 0·6); P<0·01) and in those with macrocytosis and/or anaemia (-9·1 (SD 11·8); + 0·8 (SD 1·2); P<0·05). A low serum vitamin B12 is common in geriatric medical patients. This is usually associated with an upset in erythropoiesis, although the abnormalities are often subtle and may not be apparent on inspection of the full blood count. Elderly patients with serum vitamin B12<175pmol/l should be assumed to have vitamin deficiency even if their full blood count is normal.

Rodents fed on a Mg-deficient (Mg-D) diet develop cardiomyopathic lesions, as well as other types of cardiovascular dysfunction. In the rat, inflammatory cell infiltration of the myocardium begins to occur by week 1, and the lesions develop extensively in the third and fourth weeks on the Mg-D diet. Although the aetiologic mechanisms of Mg-D cardiomyopathy are unknown, we have previously reported that once plasma Mg is markedly reduced, one of the earliest molecular markers of the pathophysiological process is elevation of plasma substance P, calcitonin gene-related peptide and prostaglandin E2, followed by histamine and the inflammatory cytokines (interleukin-1, interleukin-6, and tumor necrosis factor-α). In order to evaluate the potential role of specific circulating inflammatory cell subpopulations in the mechanisms underlying pathophysiological changes observed in Mg-deficiency-induced cardiomyopathy, we analysed these cells by flow cytochemistry. Leucocyte subpopulation pools increased progressively in the Mg-D rats. Elevated circulating levels of neutrophils and lymphocytes appeared to contribute to both the acute (week 1–2) and chronic phases (week 3–4) of the inflammatory responses; monocytes, eosinophils, basophils and large unstained cells which are lymphoid in stained smears, on the other hand, increased significantly in the third and fourth weeks and thus contributed to the chronic inflammatory phase. Changes in the circulating leucocyte subpopulations paralleled the chronological progression of the cardiomyopathic lesions, particularly in weeks 3 and 4. Since a pronounced neutrophilia preceded leucocyte infiltration and deposition within the myocardial tissue, modifications of the microvascular barrier may be a prerequisite for cardiomyopathy in this model of neurogenic inflammation.