Efficacy of urban road salt reduction strategies on public supply well quality

Long-term road salt application has increased chloride (Cl-) concentrations in public drinking water wells in many cold climate communities. A range of Best Management Practices (BMPs) have been adopted to mitigate the impact of road deicing compounds on groundwater quality. Chronic increases in chloride levels have been observed in several municipal well fields within the southern Ontario Regional Municipality of Waterloo (RMOW). In response, the RMOW and City of Kitchener implemented a plan to reduce salt application on roads by 25% within the local capture zones of one of the impacted well fields, the Greenbrook Well Field. Here the influence of salt reduction BMPs on subsurface water quality are examined by documenting changes in pore water Cl- concentrations and stored salt mass in vadose zone core samples collected at sites near the well field both before and after the implementation of the BMPs. The data indicate that ~6 years after salt reduction measures were initiated, average pore water Cl- concentration and average cumulative stored chloride mass in the vadose zone had decreased by approximately 60% and 40%, respectively. Groundwater samples collected from shallow monitoring wells installed at each field site showed similar post-BMP reductions in shallow groundwater Cl- concentration (~35%). Long-term (1973-2022) trends in raw water Cl- concentration data from the deeper public drinking water supply wells clearly demonstrate a slow, time-lagged response of the municipal supply wells to the salt reduction BMPs. The combined results suggest that controlled reductions in road salt applications within vulnerable, capture zone regions of public supply wells can reduce the impact of road salt deicing practices on municipal groundwater supplies over time.

Impact of alien fishes on the distribution pattern of indigenous freshwater fishes of Punjab, Pakistan

Pakistan is the country with mega freshwater fish diversity of native and alien species. In the presence of enormous native fishes varies species of exotic fishes have been introduced into the freshwater bodies of Pakistan which are competing with native freshwater fish fauna and making them deprive of food and habitat as well. Intentional or accidental introductions of animals, plants and pathogens away from their native niche is considered as major leading problem for biodiversity of invaded habitat. Three years study (from January 2017 to December 2019) was conducted in freshwater bodies of Province Punjab, Pakistan. Study was designed to know exotic species impacts on the distribution of native species of fishes. During current survey a total of 68 (indigenous and exotic) fish species belonging to 14 families were recorded from head Qadirabad, head Baloki, Islam headworks and Rasul barrage. Statistical analysis showed that Shannon-Wiener diversity index was the highest (1.41) at both Rasul barrage and Islam headworks but, invasive species were present in very less number in these study sites i.e. Oreochromis mozambicus, O. niloticus, Hypophthalmichthys nobilis, Carassius auratus, Ctenophryngdon idella, Cyprinus carpio and H. molitrix. The diversity index showed that comparatively low diversity was present in both area head Qadirabad (1.30) and head Baloki (1.4) due to high pressure of invasive species. Direct observation of species and statistical analysis showed that aliens' species produced negative impact on the local fish fauna diversity, evenness, and numbers. It is concluded that many factors are impacts on the diversity of native fishes, but alien (invasive) species also play a major role to reduction of native species, because aliens' species produce competition for native species. So it is urgent need to analysis the aliens and native food web and roosting sites in Pakistan, in future.

In Vitro Assay for Predicting Protein Efficiency Ratio as Measured by Rat Bioassay: Collaborative Study

Seven laboratories collaborated in testing the calculated protein efficiency ratio (C-PER and DC-PER). The collaborative study required each laboratory to analyze 6 foods and a control protein (ANRC casein) for in vitro apparent protein digestibility, amino acid composition, and PER via rat bioassay. The 6 foods or food ingredients tested were nonfat dry milk, cooked chicken muscle, protein-fortified dry breakfast cereal, textured soy protein, oat-based dry breakfast cereal, and durum wheat flour. Data obtained from the study were analyzed statistically for the intralaboratory variation for each method of analysis (i.e., amino acid analysis, PER, etc.). The ability of the C-PER to rapidly predict rat PER was also measured. The C-PER and DC-PER methods were adopted official first action.

Effects of an ozone-generating air purifier on indoor secondary particles in three residential dwellings

The use of indoor ozone generators as air purifiers has steadily increased over the past decade. Many ozone generators are marketed to consumers for their ability to eliminate odors and microbial agents and to improve health. In addition to the harmful effects of ozone, recent studies have shown that heterogeneous and homogeneous reactions between ozone and some unsaturated hydrocarbons can be an important source of indoor secondary pollutants, including free radicals, carbonyls, carboxylic acids, and fine particles. Experiments were conducted in one apartment and two detached single-family dwellings in Austin, TX, to assess the effects of an ozone generator on indoor secondary organic aerosol concentrations in actual residential settings. Ozone was generated using a commercial ozone generator marketed as an air purifier, and particle measurements were recorded before, during, and after the release of terpenes from a pine oil-based cleaning product. Particle number concentration, ozone concentration, and air exchange rate were measured during each experiment. Particle number and mass concentrations increased when both terpenes and ozone were present at elevated levels. Experimental results indicate that ozone generators in the presence of terpene sources facilitate the growth of indoor fine particles in residential indoor atmospheres. Human exposure to secondary organic particles can be reduced by minimizing the intentional release of ozone, particularly in the presence of terpene sources.

PRACTICAL IMPLICATIONS

Past studies have shown that ozone-initiated indoor chemistry can lead to elevated concentrations of fine particulate matter, but have generally been completed in controlled laboratory environments and office buildings. We explored the effects of an explicit ozone generator marketed as an air purifier on the formation of secondary organic aerosol mass in actual residential indoor settings. Results indicate significant increases in number and mass concentrations for particles <0.7 microns in diameter, particularly when an ozone generator is used in the presence of a terpene source such as a pine oil-based cleaner. These results add evidence to the potentially harmful effects of ozone generation in residential environments.

Methicillin resistant Staphylococcus aureus: a multicentre study

OBJECTIVE

To determine the frequency of Methicillin resistance Staphylococcus aureus infection in major cities of Pakistan.

SETTING

Various laboratories of the country with one as the central Laboratory.

MATERIALS AND METHODS

Seven hundred and ninety two consecutive clinical isolates of Staphylococcus aureus were collected from 8 laboratories all over Pakistan i.e. Karachi, Peshawar, Lahore, Sukkhur, Islamabad, Quetta, and Mirpur, Azad Kashmir. Antibiotic sensitivity was done by Kirby Bauer disc diffusion method and MIC of Vancomycin was determined by 'E' test.

RESULTS

Forty two percent of the isolates were found to be Methicillin resistant staphylococcus aureus (MRSA) while no Vancomycin resistance was encountered.

CONCLUSION

Methicillin resistant Staphylococcus aureus (MRSA) are seen in the local population with frequencies varying between 2-61% highest incidence is seen in the major cities of the country. Fortunately no Vancomycin resistant Staphylococcus has been isolated from any of the major cities.

Influence of tryptophan supplementation of soy-based infant formulas on protein quality and on blood and brain tryptophan and brain serotonin in the rat model

A 2-wk feeding study with weanling rats was conducted to investigate the effects of tryptophan supplementation of soy-based infant formulas on protein quality and on the levels of blood and brain tryptophan and brain serotonin and 5-HIAA (5-hydroxyindole-3-acetic acid), a metabolite of serotonin. The powder and liquid concentrate forms of soy-based infant formulas obtained from four manufacturers were tested. The tryptophan contents of the test soy-based formulas (10.0-12.3 mg/g protein) were considerably lower compared to those of human milk (17-19 mg/g protein). The infant formulas were fed as the sole source of protein in diets containing 8% protein, 20% fat, 5% cellulose and adequate amounts of minerals and vitamins. In general, supplementation of the diets containing test formulas with graded levels of L-tryptophan (0.1 or 0.2%) had no effect on protein quality indices based on rat growth such as PER (protein efficiency ratio), NPR (net protein ratio) and relative NPR (RNPR), but resulted in significant (p < 0.05) increases in the concentrations of tryptophan in the plasma and brain, and serotonin and 5-HIAA in brain of rats. The increased concentrations of brain tryptophan and 5-hydroxyindoles (serotonin + 5-HIAA) in rats fed tryptophan-supplemented formulas compared to those fed unsupplemented formulas support the need for further research to investigate the influence of tryptophan supplementation of soy-based infant formulas on tryptophan metabolites and their potential related effects on sleep latency and neurobehavioral developments in infants.

Influence of sources of dietary oils on the life span of stroke-prone spontaneously hypertensive rats

In recent studies, the life span of stroke-prone spontaneously hypertensive (SHRSP) rats was altered by a variety of dietary fats. It was relatively shorter in rats fed canola oil as the sole source of fat. The present study was performed to find out whether the fatty acid profile and the high content of sulfur compounds in canola oil could modulate the life span of SHRSP rats. SHRSP rats (47 d old, n = 23/group) were matched by body weight and systolic blood pressure and fed semipurified diets containing 10% canola oil, high-palmitic canola oil, low-sulfur canola oil, soybean oil, high-oleic safflower oil, a fat blend that mimicked the fatty acid composition of canola oil, or a fat blend high in saturated fatty acids. A 1% sodium chloride solution was used as drinking water to induce hypertension. After consuming the diets for 37 d, five rats from each dietary group were killed for collection of blood and tissue samples for biochemical analysis. The 18 remaining animals from each group were used for determining their life span. The mean survival time of SHRSP rats fed canola oil (87.4+/-4.0 d) was not significantly different (P > 0.05) from those fed low-sulfur canola oil (89.7+/-8.5 d), suggesting that content of sulfur in canola oil has no effect on the life span of SHRSP rats. The SHRSP rats fed the noncanola oil-based diets lived longer (mean survival time difference was 6-13 d, P < 0.05) than those fed canola and low-sulfur canola oils. No marked differences in the survival times were observed among the noncanola oil-based groups. The fatty acid composition of the dietary oils and of red blood cells and liver of SHRSP rats killed after 37 d of treatment showed no relationship with the survival times. These results suggest that the fatty acid profile of vegetable oils plays no important role on the life span of SHRSP rat. However, phytosterols in the dietary oils and in liver and brain were inversely correlated with the mean survival times,indicating that the differential effects of vegetable oils might be ascribed, at least partly, to their different phytosterol contents.

Liquid concentrates are lower in bioavailable tryptophan than powdered infant formulas, and tryptophan supplementation of formulas increases brain tryptophan and serotonin in rats

The bioavailability of tryptophan in powdered and/or liquid concentrate forms of milk-based infant formulas was determined by studying rat growth response by using a slope ratio method (food conversion efficiency: weight gain/food consumed vs. tryptophan consumed). A gelatin basal diet formulated to be adequate in all nutrients, except tryptophan (0.03%), for rat growth was supplemented with graded levels of crystalline L-tryptophan (0.02, 0. 04, 0.06, 0.08, 0.10, 0.12 and 0.14%, standard diets) or infant formulas providing 0.04 and 0.08% supplemental tryptophan (test diets). These diets were fed to weanling rats for 2 wk. Tryptophan bioavailabilities of various formulas varied from 83 to 95%, with some of the liquid concentrates having the lowest values. The levels of bioavailable tryptophan in the liquid concentrate forms (9.7-12.6 mg/g protein) and the powdered forms (11.1-13.1 mg/g protein) were considerably lower than those of human milk (17-19 mg/g protein). Supplementation of the liquid concentrates with graded levels of L-tryptophan (0.1, 0.5 and 1.0%) had no effect on protein quality indices, based on rat growth, but resulted in a dose-related increase in the concentrations of tryptophan in the plasma and brain and of serotonin and 5-hydroxyindole-3-acetic acid in the brains of rats. This study supports further research to investigate the influence of tryptophan supplementation of infant formulas, to more closely simulate tryptophan composition of human milk, on tryptophan metabolites and their potential related effects on sleep latency and neurobehavioral developments in infants.

Influence of feeding alkaline/heat processed proteins on growth and protein and mineral status of rats

Effects of feeding alkaline (0.1 N NaOH) and heat treated (75 degrees C for 3 h) proteins (lactalbumin and soybean protein isolate, SPI) on growth, and protein and mineral status of rats have been determined. The untreated and alkaline/heat treated lactalbumin contained 0.10 and 4.42 g lysinoalanine (LAL)/100 g protein, respectively. Similarly, the untreated and treated SPI contained 0.03 and 1.94 g LAL/100 g protein, respectively. The formation of LAL in the treated proteins was accompanied with a loss of cystine (73-77%), threonine (35-45%), serine (18-30%) and lysine (19-20%). The alkaline/heat treatments caused significant (P < 0.05) reductions in protein digestibility of lactalbumin (99 vs. 73%) and SPI (96 vs. 68%). The processing treatments also caused a drastic negative effect on protein quality, as measured by rat growth methods such as relative protein efficiency ratio (RPER) and relative net protein ratio (RNPR). The RPER and RNPR values of untreated lactalbumin and SPI were 89-91 and 56-64%, respectively. But the RPER and RNPR values of the treated lactalbumin and SPI were 0%. The mineral status of rats was also compromised by feeding alkaline/heat treated proteins. Liver iron levels in male rats (165-180 micrograms/g dry weight) and female rats (306-321 micrograms/g dry weight) fed the treated proteins were about half the levels in male rats (229-257 micrograms/g dry weight) and female rats (578-697 micrograms/g dry weight) fed the untreated proteins. The kidney iron contents of rats fed the treated proteins were also lower than that of rats fed the untreated proteins. Liver copper levels of male and female rats fed the treated proteins were up to three fold higher than those found in rats fed the untreated proteins. The data suggested that LAL, an unnatural amino acid derivative formed during processing of foods, may produce adverse effects on growth, protein digestibility, protein quality and mineral bioavailability and utilization. The antinutritional effects of LAL may be more pronounced in sole-source foods such as infant formulas and formulated liquid diets which have been reported to contain significant amounts (up to 2400 ppm of LAL in the protein) of LAL.

Threonine kinetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein

BACKGROUND

Plasma threonine concentrations are elevated in infants fed formula containing a whey-to-casein protein ratio of 60:40 compared with concentrations in infants fed formula containing a ratio of 20:80 or human milk (60:40).

OBJECTIVE

We studied whether degradation of excess threonine was lower in formula-fed infants than in infants fed their mothers' milk.

DESIGN

Threonine kinetics were examined in 17 preterm infants (gestational age: 31+/-2 wk: birth weight: 1720+/-330 g) by using an 18-h oral infusion of [1-13C]threonine at a postnatal age of 21+/-11 d and weight of 1971+/-270 g. Five infants received breast milk. Formula-fed infants (n = 12) were randomly assigned to receive 1 of 3 formulas (5.3 g protein/MJ) that differed only in the whey-to-casein ratio (20:80, 40:60, and 60:40).

RESULTS

Threonine intake increased significantly in formula-fed infants with increasing whey content of the formula (48.5, 56.4, and 63.2 micromol.kg(-1).h(-1), respectively; pooled SD: 2.2; P = 0.0001), as did plasma threonine concentrations (228, 344, and 419 micromol/L, respectively; pooled SD: 75; P = 0.03). Despite a generous threonine intake by infants fed breast milk (58.0+/-16.0 micromol.kg(-1).h(-1), plasma threonine concentrations remained low (208+/-41 micromol/L). Fecal threonine excretion and net threonine tissue gain, estimated by nitrogen balance, did not differ significantly among groups. Threonine oxidation did not differ significantly among formula-fed infants but was significantly lower in formula-fed infants fed than in infants fed breast milk (17.1% compared with 24.3% of threonine intake, respectively).

CONCLUSION

Formula-fed infants have a lower capacity to oxidize threonine than do infants fed breast milk.

Free amino acids in milks of human subjects, other primates and non-primates

Preterm and term transitional milks of human subjects and mature milks of human subjects, non-human primates and non-primates were analysed for free amino acids (AA) using precolumn phenylisothiocyanate derivatization and liquid chromatography. Differences in free AA between three types of human milk were small. Milks of pinnipeds (seals and sea lions) contained the highest levels of total free AA (8634-20,862 mumol/l), while the milks of cows and sheep had the lowest levels of total free AA (1061-1357 mumol/l). The milks of human subjects, chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), elephants (Elephas maximus), horses and pigs had intermediate levels of total free AA (3069-7381 mumol/l). Glutamic acid was the most abundant free AA in milks of human subjects (1339-2157 mumol/l), non-human primates (423-2528 mumol/l), elephants (1332 mumol/l), horses (1119 mumol/l), and cows (349 mumol/l). Taurine was the most abundant free AA in milks of pinnipeds (5776-13,643 mumol/l), pigs (1238 mumol/l), goats (1150 mumol/l) and sheep (341 mumol/l). Taurine was the second most abundant free AA in milks of human subjects and non-human primates, while histidine was the second most abundant free AA in milks of pinnipeds. Milks of each species had a distinctive free AA pattern which may reflect the relative importance of the free AA during early postnatal development.

Influence of dietary protein and fat on serum lipids and metabolism of essential fatty acids in rats

A 120 d feeding study with adult rats was conducted to evaluate the influence of two protein sources (casein and gelatin), two protein levels (50 and 300 g/kg diet) and two fat levels (50 and 150 g/kg diet) on serum lipids (total cholesterol, HDL-cholesterol and triacylglycerols) and liver polyunsaturated fatty acid levels. In general, the concentrations of serum triacylglycerols and total cholesterol and liver phospholipid levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) were higher in rats fed on casein diets compared with those fed on the gelatin diets. These effects were more pronounced in rats fed on the high-casein (300 g/kg)-high-fat (150 g/kg) diet. Gelatin was hypocholesterolaemic and also suppressed the liver phospholipid levels of AA and DHA (reported for the first time). The difference in the amino acid composition between casein and gelatin may be responsible for the observed effects. Casein contains higher levels of glutamic acid, methionine, phenylalanine and tyrosine, while gelatin contains higher levels of arginine, glycine and hydroxyproline. It is suggested that a protein source which increases serum cholesterol may also increase the concentrations of AA and DHA in rat tissues.

The protein digestibility-corrected amino acid score method overestimates quality of proteins containing antinutritional factors and of poorly digestible proteins supplemented with limiting amino acids in rats

The validity of the protein digestibility-corrected amino acid score (PDCAAS) method in predicting the quality of fourteen protein products was compared with the commonly used protein quality methods, protein efficiency ratio (RER) and net protein ratio (NPR). A rat growth and balance study was conducted to determine protein digestibility and quality of the animal and vegetable protein products by the PER and NPR methods. Amino acid compositions of the products were also determined, and PDCAAS were calculated using a rat and a human pattern of amino acid requirements. Compared to the biological methods, the scoring method overestimated protein quality of mustard flour [PDCAAS of 84-92% vs. relative PER (RPER) or relative NPR (RNPR) of 0], raw black beans (PDCAAS of 45-72% vs. RPER or RNPR of 0), alkaline-treated lactalbumin and soybean protein isolate (PDCAAS of 44-67% vs. RPER or RNPR of 0) and heated skim milk (PDCAAS of 29-31% vs. RPER and RNPR of 0-5%). The scoring method also overestimated the protein quality of zein (true protein digestibility of 63%) supplemented with Lys, Met, Thr and Trp (PDCAAS of 63-71% vs. RPER and RNPR of 3-44%). These data demonstrate that the PDCAAS method is inappropriate for predicting protein quality of those protein sources which may contain naturally occurring growth-depressing factors or antinutritional factors formed during alkaline and/or heat processing.

Use of amino acid profiles of preterm and term human milks in evaluating scoring patterns for routine protein quality assessment of infant formulas

Reports on the amino acid composition of human milk vary considerably with respect to concentrations of sulfur amino acids. Often, analyses forego tryptophan determination. A complete analysis of protein and amino acid concentrations was performed on human milk samples (5-10 days postpartum) collected from mothers of preterm (gestations of 25-32 weeks) and term (gestations of > 36 weeks) infants. Careful attention was given to quantitate amino acids such as cysteine and tryptophan, which are vulnerable to acidic hydrolysis conditions. Differences in concentrations of total amino acids (expressed on protein basis) between preterm and term milks were small, despite the higher true protein content of preterm milk versus term milk (19.20 versus 12.60 g/L). The methionine + cyst(e)ine contents of term and preterm milks (3.72-3.84 g/100 g protein) were comparable with those reported in 1991 by the Food and Agricultural Organization/World Health Organization (FAO/WHO) for mature human milk (4.20 g/100 g protein) but higher than those reported in 1991 by the European Commission (2.9 g/100 g protein). The amino acid pattern of human milk obtained in this study confirms that the 1991 FAO/WHO amino acid scoring pattern for predicting protein quality of infant formulas is representative of the amino acid quality of both preterm and term human milks.

Effects of amylose and wheat bran on the levels of blood serum urea nitrogen (BUN), other blood parameters, growth and fecal characteristics in rats

A basal diet (containing 20% soybean protein isolate) was supplemented with limiting amino acids (AA, methionine, threonine and tryptophan); wheat bran (WB, 24.3%); amylose (AM, 10%) or a combination of AA and WB or AM to investigate their effects on the levels of blood serum urea nitrogen (BUN), other blood parameters, growth and fecal characteristics in young rats. After 3 weeks feeding, supplementation of the basal diet with AA or WB resulted in improved growth (gain/food ratio) while the addition of AM had no effect on rat growth. Addition of WB to the basal diet had no effect on BUN while the addition of AA and AM caused about 20 and 12% reduction in BUN values, respectively. Rats fed the AA-AM diet had the lowest BUN values (42% lower than those fed the basal diet). Fresh volume, fresh weight, moisture and dry weight of feces in rats fed the WB diets were about four to five fold higher than in those fed the AM diets. The results suggested that BUN may not be a good predictor of growth and protein quality in diets containing AM or a source of dietary fiber (WB).

A comparison of methods for determining total body protein

The aim of the study was to find the optimal method (with respect to convenience and accuracy) for determining total protein in whole-body homogenates of rats. Three different protein extraction methods and five different protein concentration methods were assessed. The results were compared against a reference value measured by complete amino acid analysis after acid hydrolysis. The data demonstrated that extraction with 5% (w/v) sodium dodecylsulfate (SDS) in 0.5 N NaOH was far superior to that with water alone or to 6 N guanidine-HCl. A comparison of the Biuret, Bradford, and bicinchoninic acid methods on the SDS-NaOH-extracted samples showed that the Biuret method was optimal, giving a value that was 90% of the reference value with a small variation (2.4% of the mean). The Kjeldahl method gave the correct protein concentration only when a nitrogen factor of 5.51 +/- 0.03 (N = 5) was applied. The results suggest that extraction with SDS-NaOH followed by the Biuret procedure is a good method for measuring protein concentrations in whole body rat homogenates.

The effect of various bacteria and sera on functional activity of mouse macrophages

The study has been performed to compare the ability of mouse peritoneal macrophages to ingest various types (catalase positive and negative) of bacteria and compared the influence of various sera on intracellular killing of Escherichia coli C (E. coli C). Among the tested microbes only E. coli C was ingested very luxuriantly and other organisms were taken up luxuriantly and moderately by mouse peritoneal resident macrophages (RMQs). Broad difference of ingestion was found even within the same genus (i.e., E. coli B and E. coli C). Intracellular killing of E. coli C by RMQs also varied depending on the type of serum. The maximum intracellular killing was found in the presence of normal mouse serum, although the difference was not much. The study has revealed that bacterial ingestion and intracellular killing ability of RMQs varies depending on bacterial strains and sera respectively.

The protein quality of some enteral products is inferior to that of casein as assessed by rat growth methods and digestibility-corrected amino acid scores

Protein digestibility and quality of six enteral nutrition products sold in Canada were studied by rat balance and growth methods. Casein+L-methionine, 0.2 g/100 g diet (control) and six enteral products (freeze-dried) were fed as the sole source of protein in diets containing 8.61-9.12 g/100 g protein (N x 6.25) to weanling and 18-mo-old rats for a period of 2 and 1 wk, respectively. A protein-free diet was also included in the feeding studies to permit calculations of true protein digestibility and net protein ratio values. Values for true digestibility of protein as determined in old rats for the control diet and the test products were 95 and 89-93%, respectively. Compared with old rats, protein digestibility values were 5-7 percentage units higher in young rats. The 2-wk relative protein efficiency ratio values (42-56%) or the relative net protein ratio values (61-74%) of the enteral products were considerably lower compared to those of the control (100). Supplementation of an enteral product with cysteine, cysteine + tryptophan, cysteine + threonine or cysteine + tryptophan + threonine caused significant improvement in protein quality; suggesting that the product was limiting in these three amino acids. The protein digestibility-corrected amino acid scores for the enteral products were 43-46, 69-75 and 86-93% by using whole egg, casein and the FAO-WHO (1991) pattern as reference proteins, respectively. The results indicate that these enteral products are inferior to casein in protein quality.

Ion distribution in relation to leaf age in Leptochloa fusca (L.) Kunth* (Kallar grass) II. Anions*†

Using Leptochloa fusca (L.) Kunth (Kallar grass) plants, the distribution of Cl^- , NO₃ ^- , H₃ PO₄ ^- , SO₄ ^2- and malate between leaves of various ages has been studied. Plants grown in a reclaimed, salt-affected field, in solution culture and in soil at 10, 100 and 125 mM NaCl have been analyzed. Apparently due to excretion by salt secreting glands on L. fusca leaves and to phloem export, Cl^- concentrations did not increase strongly with leaf age. On a leaf f. wt basis, chloride secretion was constant over the series of increasingly aged mature leaves. If it was related to the chloride increments in the leaves, chloride secretion increased strongly from younger to mature leaves and reached between ISO and 200% of the concurrent Cl^- deposition in the lamina. Changes in the tissue concentrations of nitrate and phosphate with leafage showed a maximum in recently matured leaves. Decreases in older leaves were attributed to nitrate reduction and export of reduced nitrogen and to retranslocation of phosphate. In leaves of field-grown L. fusca nitrate was non-detectable. Sulphate and malate concentrations in laminae continued to increase from the youngest to the oldest leaves. The increasing negative charge resulting from these increases in divalent anions can be accounted for by the loss of charge occurring in connection with reduction of nitrate and export of phosphate. Higher external salinity led, apart from increases in tissue Cl^- , to noticeable decreases in tissue nitrate and phosphate but not in sulphate and malate concentrations, the latter being even increased at higher external NaCl. The observed changes in anion concentrations are compared with and discussed in relation to changes found in Ricinus communis and in Atriplex hortensis.

Evaluation of liquid chromatographic analysis of nutritionally important amino acids in food and physiological samples

Significant advances have been made in standardizing methods for amino acid analysis of foods. The methods included standardized hydrolysis of the food proteins followed by separation and quantitation of the released amino acids by ion-exchange chromatography (IEC). IEC is still the main method in use. Its use is, however, being replaced by the faster higher-performance liquid chromatographic (HPLC) methods of derivatized amino acids. The HPLC separation of precolumn phenylisothiocyanate (PITC) derivatives has been adapted for rapid analysis of all amino acids in protein hydrolysates (12 min) and nutritionally important amino acids in deproteinized physiological samples (20 min). The inter-laboratory variability of the PITC derivatization method has not been determined although the intra-laboratory variation of the HPLC method was found to be similar to that of IEC. When similar hydrolytic conditions were used in preparing protein hydrolysates, amino acid results obtained with the PITC derivatization method were generally in close agreement with those obtained by IEC. There is, however, room for improvement in the HPLC analysis of amino acids in physiological samples.

Effect of amino acid supplementation on protein quality of soy-based infant formulas fed to rats

The powder forms of soy-based infant formulas obtained from four manufacturers were fed to weanling rats for two weeks, as the sole source of protein in diets containing 8% protein, 20% fat, and adequate amounts of minerals and vitamins. The relative protein efficiency ratio (RPER) and the relative net protein ratio (RNPR) values (casein + methionine = 100) of diets containing unsupplemented formulas were 71-81 and 78-85, respectively. Supplementation of the formula diets with lysine (0.2%), methionine (0.2%), threonine (0.1%) or tryptophan (0.05%) increased the level of the supplemental amino acid in rat serum but generally failed to improve the RPER or RNPR values. Addition of all four essential amino acids to the formula diets, however, caused a marked improvement in their protein quality (RPER or RNPR values = 100). The data suggested that proteins in soy-based formulas could be marginally co-limited in several indispensable amino acids.

Ion distribution in relation to leaf age in Leptochloa fusca* (L.) Kunth (Kallar grass): I. K, Na, Ca and Mg

Using Leptochloa fusca (Kallar grass) plants, the distribution of K, Na, Mg and Ca between leaves of various ages has been studied. Plants grown in a salt-affected, reclaimed field, in a solution culture and in soil in pots at 10, 100 and 125 mM NaCl have been analyzed. Despite the presence of salt-secreting glands on Leptochloa fusca leaves, Na concentrations increased strongly with leaf age, while K concentrations were highest in young leaves and decreased with increasing leaf age. This was due to K retranslocation, which was clearly intensified at higher external NaCl concentration. The data point to the importance of K recycling in this halophyte and also to the use of Na by this salt-secreting species for turgor maintenance in mature and old leaves. Both Mg and particularly Ca concentrations increased with leaf age, indicating that xylem import surpassed phloem export even for the phloem-mobile ion, Mg. In young leaves, Mg concentrations exceeded those of Ca.

A double-blind placebo-controlled glucose challenge in bulimia nervosa: psychological effects

Nineteen bulimic women and 22 age-matched controls were randomly assigned to receive 25 g of glucose or a placebo injection under double-blind conditions. Blood samples of glucose, insulin, and glucagon, and psychometric assessments of mood and food cravings were obtained 10 min before, and 0, 5, 10, 20, 30, 45, and 60 min after injection. Blood levels of the large neutral amino acids (LNAAs) tryptophan, tyrosine, leucine, valine, phenylalanine, and leucine were determined at 10 min before and 60 min after the injection. Bulimic subjects were found to report more symptoms of distressed mood throughout the entire monitoring period than controls. Five minutes following glucose ingestion the self-reports of depression, fatigue, anxiety, and bewilderment rose to a level among the bulimic subjects that was above that at baseline, and was higher than that of bulimia nervosa (BN) subjects receiving placebo. No comparable change in mood was observed among controls. Blood glucose levels were correlated with mood in the bulimic group, but not in controls. In addition, the glucose injection induced a heightened urge to binge in the bulimic group (compared to placebo at 10 and 60 min), whereas reducing food cravings (for sweets) in the controls (at 5 min). When collapsed across time and injection condition, the blood glucose level of bulimics was lower than that of controls. There were no differences in insulin response between the groups. The bulimic group was found to have lower baseline levels of blood tryptophan, whereas no differences in the tryptophan/LNAA ratio were observed either at baseline or following glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of dietary soybean trypsin inhibitors and DL-ethionine on sulfur amino acid adequacy of diets for young rats

Weanling male Wistar rats were fed 20% protein diets based on casein or either of two combinations of soy protein isolate and ground raw soy providing three levels of soybean trypsin inhibitors (SBTI; 0, 448 and 808 mg of trypsin inhibited per 100 g of diet respectively). DL-ethionine was included at three levels (0, 0.05% and 0.10%) with each level of SBTI. After 4, 8 and 12 weeks of ad libitum feeding, diets containing SBTI without DL-ethionine were associated with decreases in weight gain, feed efficiency, serum cholesterol and serum urea nitrogen. Higher levels of triglycerides, glutamate pyruvate transaminase (SGPT) and altered serum free amino acid levels were also found. Increased dietary levels of DL-ethionine also resulted in deficits in growth and feed efficiency, decreased serum cholesterol, increased SGPT and similar alterations in serum free amino acids. Combination of dietary SBTI with DL-ethionine resulted in even greater growth deficits and serum cholesterol decreases as well as increases in SGPT and serum triglycerides and changes in serum free amino acid levels. Methionine deficiency in the young rats fed SBTI and DL-ethionine was indicated by the changes in serum amino acids and growth deficits. Moderation of some effects over the 12 week test period suggested decreased methionine requirements in the older rats.

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.

A comparison of fasting serum amino acid profiles of young and elderly subjects

The fasting serum amino acid profile in 37 healthy young women and men (30-35 years) was compared with the fasting profile in 30 institutionalized elderly women and men (80-89 years), an ambulatory, self-fed senior-residence group. Levels of serum lysine, leucine, methionine, valine, and total essential amino acids were significantly lower in the older group than in the younger group; however, citrulline and hydroxyproline were significantly higher in the older group compared to the younger group. Histidine, threonine, tryptophan, and the ratio of tryptophan to large neutral amino acids (isoleucine, leucine, phenylalanine, tyrosine, and valine) were also generally lower in the older group than in the younger group, while the difference due to age was more pronounced in the females compared to males. The essential/nonessential amino acid ratio was lower in females compared to males.

Amino acid ratings of different forms of infant formulas based on varying degrees of processing

Amino acid profiles, protein digestibility and/or amino acid bioavailability for the various forms (powder, liquid concentrate, ready-to-use, etc.) of infant formulas (involving varying degrees of heat processing during preparation) have been determined. Amino acid scores (based on the single most limiting amino acid) were calculated by comparing the essential amino acid data with that of human milk. Amino acid scores were multiplied by total protein (g/100 kcal) to obtain amino acid ratings, which take into account both quality and quantity of protein. Amino acid scores for milk- and soy-based formulas ranged from 49 to 90 and 59 to 81%, respectively, due to deficiencies in methionine plus cystine and/or tryptophan. The deficiency in the limiting amino acids was more marked in liquid concentrate than powder prepared by the same manufacturer. Because of significantly higher total protein contents (g/100 kcal) of soy- (2.65-3.68) and milk-based (2.20-2.95) formulas compared to human milk (1.5), the relative amino acid ratings (human milk = 100) of all formulas except two milk-based liquid concentrates and one ready-to-feed (with values of 77-87%) were greater than 100%. When corrected for protein digestibility, the relative amino acid ratings for all four liquid concentrates were less than 100%. Lower levels of digestible protein and bioavailable amino acids in liquid concentrate compared with powder (prepared by the same manufacturer) would suggest that inferior protein quality of liquid concentrates may be due to more severe heat treatment involved in their preparation.

In vivo rat assay for true protein digestibility: collaborative study

Eight laboratories participated in a collaborative study to estimate precision of a standardized rat assay for determining true protein digestibility in selected animal, fish, and cereal products. Each of 7 test protein sources (casein, tuna fish, macaroni/cheese, pea protein concentrate, rolled oats, pinto beans, and nonfat dried milk) was fed as the sole source of protein at a 10% protein level in mixed diets. Each diet was fed to 2 replicate groups of 4 rats each for a 4-day acclimation period and a 5-day balance period. Mean digestibilities ranged from 98.6% for casein to 72.6% for pinto beans. Repeatability standard deviations ranged from 0.5 to 2.0%; the mean relative standard deviation for repeatability was 0.9% (range 0.5-2.8%). Reproducibility standard deviations ranged from 1.2 to 3.2%, and the mean relative standard deviation for reproducibility was 2.4% (range 1.3-4.4%). The method has been approved interim official first action for determining true protein digestibility in foods and ingredients.

In vitro assay for protein digestibility: interlaboratory study

True protein digestibilities of 17 protein sources were estimated by 6 laboratories using an in vitro, 3-enzyme digestion system in a pH stat. Samples from animal, vegetable, and mixed food sources were freeze-dried (if not already dried), ground, mixed, and shipped to each collaborator along with a sodium caseinate standard and trypsin, chymotrypsin, and peptidase. The uptake of titrant during enzymatic digestion was used to calculate estimates of digestibility. Digestibilities ranged from 100% for casein to 89.9% for whole wheat cereal. Mean relative standard deviations for repeatability were 1.4% for rolled oats and less than 1% for the remaining 16 samples. Mean relative standard deviations for reproducibility ranged from 5.0 to 0.8%; values were less than 2.5% for 13 of the 17 samples.

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.

Rapid analysis of nutritionally important free amino acids in serum and organs (liver, brain, and heart) by liquid chromatography of precolumn phenylisothiocyanate derivatives

An amino acid analysis method for protein hydrolysates, using precolumn phenylisothiocyanate (PITC) derivatization and liquid chromatography, was modified for its application in rapid analysis of commonly occurring free amino acids in serum and other physiological samples. The modifications included changes in column temperature (47.5 degrees C compared to 25-35 degrees C used in analyzing protein hydrolysates), method of preparing standard and test samples, and gradient conditions. By using a Waters Pico-Tag amino acid analysis 15 cm long column (which is also used for analyzing protein hydrolysates), separation of 27 PTC-amino acids in human serum and rat liver, brain, or heart was completed in 20 min by the modified method. The total time for analysis and equilibration was 30 min. The modified method was much faster than the traditional ion-exchange methods (2-3 h) or the existing liquid chromatographic methods using PITC derivatization (66-80 min) for determining nutritionally important free amino acids in physiological fluids and tissues. Variability of the method (expressed as coefficients of variation) for the determination (including deproteinization, derivatization, and liquid chromatography) of all amino acids was less than 5%, which compared favorably with the reproducibility of ion-exchange methods.

Evaluation of protein digestibility-corrected amino acid score method for assessing protein quality of foods

The current concepts of protein quality evaluation were reviewed. A detailed examination of existing animal assays and more promising amino acid scoring methods has been carried out by an Ad Hoc Working Group on Protein Quality Measurement for the Codex Committee on Vegetable Proteins during the last 5 years. Several factors such as inadequacies of protein efficiency ratio (PER, the poorest test) and other animal assays, advancements made in standardizing methods for amino acid analysis and protein digestibility, availability of data on digestibility of protein and individual amino acids in a variety of foods, and reliability of human amino acid requirements and scoring patterns were evaluated. On the basis of this evaluation, amino acid score, corrected for true digestibility of protein, was recommended to be the most suitable routine method for predicting protein quality of foods for humans. Amino acid scores corrected for true digestibility of protein (as determined by rat balance method) were termed "protein digestibility-corrected amino acid scores." A detailed method for the determination of the protein digestibility-corrected amino acid score was proposed, and information about the range of scores to be expected in foods or food products was provided in the present investigation. The protein digestibility-corrected amino acid score method is a simple and scientifically sound approach for routine evaluation of protein quality of foods. Accuracy of the method would, however, be confirmed after validation with growth or metabolic balance studies in humans.

Potentiality of protamine sulfate as mutagen

The mutagenicity of protamine sulfate has been clarified based on chromosomal aberration of cultured chinese hamster lung cells (cell line) in direct and metabolic activation methods and microbial mutagenesis (Ames test). In chromosomal aberration test, protamine sulfate caused cytotoxicity in the high doses (2500 and 5000 micrograms/ml) in the presence of rat liver homogenates (S-9). But very negligible or no cytotoxicity occurred in direct method at high dose (5000 micrograms/ml). Structural aberration of chromosome was not occurred in either of the methods. In microbial mutagenesis study, protamine sulfate did not show any cytotoxicity to microbes up to the dose of 5000 micrograms per plate. Furthermore, it did not have any effect in microbes like mutagens or like some toxic agent. The study reveals that protamine sulfate is not mutagen.

Amino acid rating method for evaluating protein adequacy of infant formulas

Amino acid profiles and/or protein digestibility (by the rat balance method) were determined for various forms (powder, ready-to-use, liquid concentrate, etc.) of cow's milk- and soy-based infant formulas obtained from 4 manufacturers. The essential amino acid data of the formulas were compared with that of human milk for the calculation of amino acid scores (based on the single most limiting amino acid). The product of amino acid score and total protein (g/100 kcal) was then termed "amino acid rating." Amino acid scores for the milk- and soy-based formulas ranged from 59 to 90 and from 59 to 81%, respectively, due to deficiencies in sulfur amino acids and/or tryptophan. Because of significantly higher total protein contents (g/100 kcal) of soy- (2.65-3.68) and milk-based (2.20-2.95) infant formulas compared to human milk (1.5), the relative amino acid ratings (human milk = 100) for all infant formulas except 2 liquid concentrates (having values of 87%) were above 100%. Values for true digestibility of protein in milk- and soy-based formulas ranged from 87 to 97 and from 92 to 95%, respectively. When corrected for protein digestibility, the relative amino acid ratings for all the milk-based liquid concentrates were below 100% (77-98%).