Impact of soil pedogenesis on the diversity and composition of fungal communities across the California soil chronosequence of Mendocino.

Understanding how soil pedogenesis affects microbial communities and their in situ activities according to ecosystem functioning is a central issue in soil microbial ecology, as soils represent essential nutrient reservoirs and habitats for the biosphere. To address this question, soil chronosequences developed from a single, shared mineralogical parent material and having the same climate conditions are particularly useful, as they isolate the factor of time from other factors controlling the character of soils. In our study, we considered a natural succession of uplifted marine terraces in Mendocino, CA, ranging from highly fertile in the younger terrace (about 100,000 years old) to infertile in the older terraces (about 300,000 years old). Using ITS amplicon pyrosequencing, we analysed and compared the diversity and composition of the soil fungal communities across the first terraces (T1 to T3), with a specific focus in the forested terraces (T2 and T3) on soil samples collected below trees of the same species (Pinus muricata) and of the same age. While diversity and richness indices were highest in the grassland (youngest) terrace (T1), they were higher in the older forested terrace (T3) compared to the younger forested terrace (T2). Interestingly, the most abundant ectomycorrhizal (ECM) taxa that we found within these fungal communities showed high homology with ITS Sanger sequences obtained previously directly from ECM root tips from trees in the same study site, revealing a relative conservation of ECM diversity over time. Altogether, our results provide new information about the diversity and composition of the fungal communities as well as on the dominant ECM species in the soil chronosequence of Mendocino in relation to soil age and ecosystem development.

Comparative analysis of nutrition data from national, household, and individual levels: results from a WHO-CINDI collaborative project in Canada, Finland, Poland, and Spain.

STUDY OBJECTIVE: This project determined to what extent data on diet and nutrition, which were collected in a non-uniform manner, could be harmonised and pooled for international and national comparison. DESIGN: Direct comparisons of dietary data between studies were made using food balance sheets (FBS), household budget surveys (HBS), and individual dietary data (IDS); comparisons were also made within countries. Differences in study design and methodological approaches were taken into consideration. Data from research projects from the following four World Health Organisation (WHO) Countrywide Integrated Noncommunicable Disease Intervention (CINDI) countries were included-Canada, Finland, Poland, and Spain. MAIN RESULTS: FBS overestimated food consumption and nutrient intake compared to IDS. Results between HBS and IDS were quite similar, except for fish, meat, pulses and vegetables, which were underestimated by HBS, and sugar and honey and cereals, which were overestimated. Percentages of energy from fat, carbohydrates and proteins were higher when estimated from FBS, HBS, and IDS respectively. CONCLUSIONS: Results suggest that estimations from these three sources of dietary data are difficult to compare because they are measuring different levels of dietary information. The understanding of their relations may be important in formulating and evaluating a nutrition policy.

Food consumption patterns of Inuit women.

To evaluate nutrient intake and food consumption patterns of Inuit women of child-bearing age, a 24-hour diet recall and general health and food frequency questionnaire was administered to 688 Inuit women aged 15-44 in six isolated communities. Data were analyzed using the 1991 Canadian Nutrient File. Mean intakes of essential nutrients were expressed as percentages of Health Canada's 1990 Recommended Nutrient Intakes (RNI). Chi-square tests were used to determine relationships between categorical variables. Folacin intake ranged from 49% to 95% of the RNI in most communities (median = 76%) and was only 37% of the RNI for pregnant and 54% for lactating women. Mean calcium intake for pregnant and lactating women averaged 55% and 47% of the RNI, respectively. Average vitamin A intakes ranged from 26% to 87% of the RNI (median = 65%), with intake for pregnant Inuit women and lactating women 79% and 54% of the RNI, respectively. Country food was the major source of protein and iron, and store foods the major source of calories, calcium, folacin, and vitamin A. Low intakes of folacin, calcium, and vitamin A, especially among pregnant and lactating women, place Inuit women of childbearing age at risk. Women on social assistance are nutritionally vulnerable.

Inorganic components of drinking water and microalbuminuria.

Relatively little is known of the chronic effects attributable to the ingestion of inorganic components such as uranium and silicon. Although ingestion of large amounts of U can cause acute renal damage through a chemical effect, studies on humans have typically considered inhalation the route of exposure. We investigated the association between drinking water concentration levels of U and Si, and microalbuminuria, a sensitive biological indicator of renal dysfunction. Linear regression analysis revealed a statistically significant association between U cumulative exposure index and albumin per mmol creatinine (P = 0.03). No such significant relationship appeared for Si, although a positive trend was witnessed. Since normal but increasing levels of microalbuminuria were observed at U concentration levels below the Canadian Maximum Allowable Concentration (MAC), it is suggested that further study be undertaken.

High beta-glucan oat bran and oat gum reduce postprandial blood glucose and insulin in subjects with and without type 2 diabetes.

The aim of the current study was to characterize the effects of isolated and native sources of beta-glucan, oat gum, and oat bran, respectively, when incorporated into a complete meal. Fasting control subjects and subjects with Type 2 diabetes were fed porridge meals containing either wheat farina, wheat farina plus oat gum or oat bran. Blood samples were collected for 3 h after the test meals and plasma glucose and insulin were measured. Oat bran and wheat farina plus oat gum meals reduced the postprandial plasma glucose excursions and insulin levels when compared with the control wheat farina meal in both control and Type 2 diabetic subjects. This study shows that both the native cell wall fibre of oat bran and isolated oat gum, when incorporated into a meal, act similarly by lowering postprandial plasma glucose and insulin levels. A diet rich in beta-glucan may therefore be of benefit in the regulation of postprandial plasma glucose levels in subjects with Type 2 diabetes.

Changes in serum and urinary uric acid levels in normal human subjects fed purine-rich foods containing different amounts of adenine and hypoxanthine.

The effect of ingesting some purine-rich foods (beef liver, haddock fillets and soybeans) on uric acid metabolism was investigated in 18 male subjects with no history of gout or kidney disorder. In a crossover design, three isoenergetic and isonitrogenous meals were fed to volunteers during a 3-week period. Only the content of uricogenic bases (adenine and hypoxanthine) varied among the test meals. Ingestion of all experimental meals caused an increase in serum uric acid levels at 120 minutes and this increase was more marked (about twofold) with haddock and soybean ingestion. In all groups, the postprandial serum uric acid levels at 240 minutes were lower than those obtained at 120 minutes, but still remained elevated in comparison to the fasting level. The test foods had little or no effect on serum and urinary creatinine values. As expected, 24-hour urinary uric acid excretion was similar for the three test meals due to the isonitrogenous load of proteins and purines. Assessment of each purine base content rather than the total purine content of foods should be considered in future recommendations for hyperuricemic individuals.

Milk- and soy-protein ingestion: acute effect on serum uric acid concentration.

Acute effect of the ingestion of 80 g each of casein, lactalbumin, and soybean isolate on serum and urinary uric acid concentrations was investigated in 10 healthy subjects. Serum and urinary uric acid concentrations were measured before and after the ingestion of proteins. Serum uric acid decreased significantly 3 h after ingestion of lactalbumin and casein but increased after soybean consumption. Urate clearance was significantly increased after ingestion of each of the three proteins. Multivariate analysis of urate clearance during lactalbumin and casein loads showed that independent correlation was obtained for serum alanine and urea concentration. These results demonstrate that, in addition to their known uricosuric effect, milk proteins acutely decrease serum uric acid concentration. Analysis of the effects of lactalbumin and casein on urinary uric acid elimination suggests that the uricosuric effect of proteins is a multifactorial phenomenon.

Assessment of the uricogenic potential of processed foods based on the nature and quantity of dietary purines.

Foods rich in nucleic acids, which elevate serum uric acid levels, are restricted in the diets of hyperuricemic individuals. This restriction has been based on the amount of total dietary nucleic acids or all purines, assuming no differences in uricogenic effects of individual purines (adenine, guanine, hypoxanthine, and xanthine). However, inspite of their biochemical similarity, purines are metabolized differently and produce different uricogenic effects in animals and humans. Among the four purine bases, adenine and hypoxanthine have been reported to be more uricogenic than guanine and xanthine. Moreover, free adenine has been shown to be more uricogenic than its nucleoside or nucleotide when fed to animals. Changes in the contents of purines and release of free bases have been reported to occur during various cooking procedures such as stewing, roasting, boiling, and broiling of meat, poultry, and fish products. The differences in metabolic effects of individual purines, and modification in the amount and form of purines caused by processing would suggest that the uricogenic potential of processed foods should be based on the nature and quantity of dietary purines. Recent data on purine contents of processed foods, and information on metabolic effects of dietary purines are reviewed to assess the uricogenic potential of processed foods.

Uricogenic potential of selected cooked foods in rats.

Samples of beefsteak, beef liver, haddock, and mushrooms were cooked by two methods: boiling and broiling. Growth and purine metabolism in rats fed diets containing 20% protein (N x 6.25) were studied for a period of 26 days. The cooked meats and fish were used as the sole source of dietary protein, while cooked mushrooms provided 5% protein in mushroom-casein diets. Body weight, and food and water intakes were recorded weekly while total urine was collected during the last 6 days of the feeding period. Levels of purine metabolites (uric acid and allantoin) in blood and urine were determined by enzymatic methods and reverse-phase HPLC techniques. Dietary treatments had no significant effects on weight gain and food consumption. Compared with animals fed the casein control diet, rats fed the broiled liver, broiled haddock, and boiled mushroom diets had significantly (p less than 0.05) higher concentrations of serum allantoin, suggesting that uricogenicity of these foods was influenced by the method of cooking. The renal excretion of purine metabolites was significantly correlated with purine intake, the renal excretion of allantoin and uric acid being the highest in rats fed the liver diets.

Digestibility of protein and amino acids in selected foods as determined by a rat balance method.

Values (%) for true digestibility of crude protein and individual amino acids in 20 selected foods were determined by the rat balance (fecal) method. The products were fed as the sole source of protein in diets containing 8% crude protein (N x 6.25). Lowest true protein digestibility values (79-84) were obtained for pinto beans, kidney beans and lentils; intermediate values (89-92) were obtained for chick peas, beef stew, skim milk (over heated), rolled oats, whole wheat cereal, and pea protein concentrate; and highest values (94-100) were obtained for sausage, macaroni-cheese, rice-wheat gluten cereal, skim milk, tuna, soy isolate, peanut butter, chicken frankfurters, beef salami, casein and casein + methionine. In animal foods, peanut butter and soy isolate, the differences between true digestibility of crude protein and most individual amino acids were less than 5%. However, the values for true digestibility of methionine and cystine were up to 44% lower than those of crude protein in pinto beans, kidney beans, lentils, chick peas and pea concentrate. In these legumes, digestibility of crude protein was not a good predictor of digestibility of the limiting amino acids.

Relationship between amino acid scores and protein quality indices based on rat growth.

Protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR) and relative NPR (RNPR) values, and amino acid scores were calculated for 20 food products (casein, casein + Met, beef salami, skim milk, tuna, chicken frankfuters, sausage, heated skim milk, peanut butter, rolled oats, soy isolate, chick peas, pea concentrate, kidney beans, wheat cereal, pinto bean, lentils, rice-wheat gluten cereal, macaroni-cheese, and beef stew). In most cases, PER, RPER, NPR or RNPR ranked the products in the same order and positive correlations among the protein quality methods were highly significant (r = 0.98-0.99). Amino acid scores (based on the first limiting amino acid, Lys-Met-Cys, Lys-Met-Cys-Trp or lys-Met-Cys-Trp-Thr) were positively correlated to the PER, RPER, NPR or RNPR data (r = 0.61-0.75). Inclusion of the correction for true digestibility of protein improved the correlations between amino acid scores and the indices based on rat growth. The correlations were especially high between Lys-Met-Cys scores (corrected for true digestibility of protein) and PER, RPER, NPR or RNPR (r = 0.86-0.91). Inclusion of the correction for true digestibility of individual amino acids did not result in further improvements of the correlations in most cases. It is concluded that adjusting amino acid scores for true digestibility of protein would be sufficient and further correction for digestibility of amino acids would be unnecessary in mixed diets.

Differences in uricogenic effects of dietary purine bases, nucleosides and nucleotides in rats.

The uricogenic effects of dietary free purines (adenine, guanine, hypoxanthine and xanthine), their nucleosides (adenosine, monophosphate, guanosine monophosphate and inosine monophosphate) were studied in rats. Casein-based diets (20% protein) supplemented with 30 mmol/kg diet of each of the free purine base, nucleoside or nucleotide were fed to male Sprague-Dawley rats (100 +/- 5 g) for 14 d. Addition of adenine resulted in less weight gain than in controls, greater kidney weight, greater urine volume and higher levels of blood urea nitrogen, serum uric acid, creatinine and allantoin but lower urinary levels of allantoin, uric acid and creatinine. The adenine diet also caused nephropathy characterized by nephromegaly and deposition of crystals. A microscopic examination of the kidneys revealed deposition of crystals mainly in the lumen of convoluted tubules of the cortex. Feeding of diets containing other purine bases, nucleosides and nucleotides had no adverse effects on kidney weight or structure, urine volume, serum uric acid or creatinine. Urinary allantoin excretion, however, was greater in rats fed hypoxanthine, xanthine, nucleoside and nucleotide diets than in control rats. Adenine produced adverse effects only when fed in the free form and not when fed as the nucleoside or nucleotide, suggesting a metabolic significance for free adenine in predicting hyperuricemic effects of foods.

Indoor-outdoor levels of nitrogen and sulphur species and their relation to air flow in Antigonish, Nova Scotia.

A study was conducted in Antigonish, Nova Scotia, to determine the extent to which acid rain related pollutants are present in indoor ambient air. The pollutant study included: fine (0 to 2.5 micron) and coarse (2.5 to 10 micron) particulates, sulphates, nitrates, acidity (H2SO4 and HNO3), SO2 and NO2. During the 3 1/2 month study, maximum levels of 173n equivalent/m3 fine sulphate and 55 n equivalent/m3 H2SO4 were recorded for outdoor air within the town site compared to corresponding values of 110 n equivalent/m3 and 13 n equivalent/m3 for indoor air. Based on back trajectory analysis, wind direction, and sulphuric acid content, it was postulated that local or medium range pollution sources are predominant in the winter while long range transport originating from the United States produces the major episodes when SW winds are persistent.