Hexahydroxytriphenylene for the synthesis of group 13 MOFs - a new inorganic building unit in a ß-cristobalite type structure.

Two new, microporous MOFs of framework composition ((CH3)2NH2)2[M3O(HHTP)(HHTP˙)], M = Al3+, Ga3+, H6HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene, are described. Electron diffraction combined with molecular simulations show that these compounds crystallize in the ß-cristobalite structure, containing a new type of trinuclear inorganic building unit for MOFs and radical anions.

Determinants of hypocholesterolemic response to soy and animal protein-based diets.

The effect of substituting soy for animal protein in mixed diets was determined in young men with mildly elevated plasma cholesterol, 218 to 307 mg/dl. The diets were low in cholesterol, 200 mg/day, with 13 to 16% of energy as protein, 30 to 35% as fat, and a polyunsaturated to saturated fat ratio of 0.5. Of protein 65% was from either mixed animal proteins or isolated soy protein products made comparable by the addition of extracted animal fats. Fresh egg yolk was added to balance the cholesterol content of the diets. Proteins from grains and vegetables were identical in both menus and contributed about 35% of dietary protein. Twenty of 24 subjects decreased plasma cholesterol at the end of the protocol. Subjects were classified as responders or nonresponders as a function of greater or lesser than mean reduction in cholesterol for the groups. Mean decreases in plasma cholesterol, 16 and 13%, for responders in the animal and soy groups were significant, p less than 0.01 and 0.05, respectively. Responders in both groups had higher initial plasma cholesterol values than nonresponders. Although plasma high-density lipoprotein cholesterol decreased slightly, the high-density lipoprotein cholesterol to cholesterol ratio (high-density lipoprotein cholesterol/total cholesterol) remained constant for most individuals. The hypocholesterolemic effects were similar for both animal and soy protein (p less than 0.05) and fat (p less than 0.05) while on the experimental diet. All groups significantly decreased dietary cholesterol (p less than 0.001).

Absorption of dietary zinc in man: comparison of intrinsic and extrinsic labels using a triple stable isotope method.

Determination of true absorption of dietary minerals in human subjects using "extrinsic-tag" approach with stable isotopes requires establishment of its validity. The present study was conducted to test with quantitative aspects absorption of an extrinsic-tag of zinc labeled with 70Zn as compared with an "intrinsic-tag" of the mineral as 68Zn-labeled chicken meat given simultaneously to health male subjects. Three diet periods were used in which diet modulation with respect to zinc dialy intake and nature of protein source (chicken/soy protein isolate) was also examined. Absorption was measured via quantitative fecal isotope balance of 64Zn, 68Zn, 70Zn. For the three diet period 1 (protein: chicken; Zn intake: ZN intake: 10 to 11 mg/day), 2 (protein: chicken/soy protein isolate, 50/50; Zn intake: 10 to 11 mg/day), and 3 (protein: chicken; Zn intake: 7 mg/day), fractional absorption of the extrinsic tag (mean +/- 1 SEM) was 0.46 +/- 0.06, 0.46 +/- 0.06, and 0.66 +/- 0.04 respectively. The comparable values for intrinsic 68Zn were 0.57 +/- 0.06, 0.57 +/- 0.06, and 0.72 +/- 0.04. There was a highly significant correlation (r=0.91), between zinc absorption from the two labels. However, absorption of intrinsic 68Zn was significantly higher (p less than 0.02) during all periods than that for the extrinsic 70Zn. A 50% replacement of protein from chicken meat with the soy protein isolate did not later fractional absorption of zinc from either tag. The ratio of fractional absorption of the extrinsic/intrinsic tag (mean +/- 1 SEM) was 0.79 +/- 0.06, 0.79 +/- 0.04, and 0.92 +/- 0.03 for periods 1, 2, 3, respectively.

Effects of a soy-protein beverage on plasma lipoproteins in children with familial hypercholesterolemia.

The effects of soy protein (35% of protein energy) given as a beverage and those of cow-milk proteins were investigated on plasma lipoprotein concentrations in children with familial hypercholesterolemia (FH). Subjects were randomly assigned to either the soy-protein or cow-milk-protein experimental period, with subsequent crossover after a washout period, each period lasting 4 wk. Diets were planned to provide 20% energy as protein, 28% as fat (polyunsaturated:monounsaturated:saturated fatty acids, 1:3:3) and less than 200 mg cholesterol/d. No changes were observed in either plasma cholesterol, low-density-lipoprotein cholesterol, or apolipoprotein concentrations. However, the soy beverage significantly reduced the concentrations of triglyceride and very-low-density-lipoprotein cholesterol (P less than 0.05) and significantly increased the concentrations of high-density-lipoprotein cholesterol (HDL-C) and HDL3-C (P less than 0.04 and P less than 0.03, respectively). These results indicate that the administration of soy protein may induce clinically beneficial effects in children with FH.

Effects of soy polysaccharide on gastrointestinal functions, nutrient balance, steroid excretions, glucose tolerance, serum lipids, and other parameters in humans.

A diet-controlled study with a cross-over design was conducted to determine the effect of soy polysaccharide on gastrointestinal functions, nutrient balance, steroid excretion, blood lipid levels, postprandial serum glucose response, and other blood parameters in healthy male human subjects. A total of 14 college students was selected to participate in the study on a voluntary basis and each served as his own control. The study had two 17-day feeding periods. During the first feeding period, half of the subjects served as controls, the other as experimentals. During the second feeding period, treatments were crossed. When serving as controls, subjects consumed a low-fiber basal diet; when serving as experimentals, the same diet was supplemented with 25 g/day of soy polysaccharide. Blood samples taken at the beginning (days -1 and 1) and at the end (days 17 and 18) of each period revealed no changes in serum lipid levels or other blood parameters by soy polysaccharide supplementation. Nutrient balance and fecal transit studies revealed a significant increase in fecal wet weight and fecal water content, but no changes in total dry weight, fecal neutral steroid, bile salt, protein, and mineral contents. Glucose tolerance tests conducted during each period revealed that addition of soy polysaccharide to the glucose solution significantly reduced the reactive hypoglycemia at 180 min. Results of the present study suggest that in healthy male subjects, supplementation of soy polysaccharide can result in an increase in wet fecal content and possibly some improvement in glucose tolerance response.

A long-term metabolic balance study in young men to assess the nutritional quality of an isolated soy protein and beef proteins.

To evaluate the capacity of an isolated soy protein to maintain long-term protein nutritional status in healthy young adult men, an 84-day metabolic balance experiment was conducted in eight subjects. The sole source of protein intake was provided by the isolated soy protein, given at a level of 0.8 g (N X 6.25) per kg per day. In a second and similar study, four young men received 0.8 g protein and three subjects 0.68 g protein per kg per day from beef proteins for 60 to 81 days. Body weight, nitrogen balance, blood chemistries, and body composition (whole body 40K) were monitored throughout each study. Body nitrogen balances were maintained within the range of N equilibrium in both diet groups. Body cell mass, as judged from 40K measurements, did not reveal any deterioration in protein nutritional status. These observations confirm the prediction, derived from previous short-term. N balance studies, that the nutritional quality of isolated soy protein is high and that this plant protein can serve as the sole source of essential amino acids and nitrogen for protein maintenance in adults.

Effect of soy fiber and soy protein on cholesterol metabolism and atherosclerosis in rabbits.

The effect of dietary fiber isolated from dehulled, defatted soybean seeds on cholesterol (CHOL) metabolism and atherosclerosis in rabbits was studied alone and in combination with isolated soy protein (ISP). Soy fiber (SF) contains both cellulosic and non-cellulosic dietary fiber. Based on the official AOAC method, soy fibers contains 75% total dietary fiber. Rabbits at 6 months of age were randomly assigned to 1 of 4 dietary treatments. All rabbits received either a casein or ISP-based diet with cellulose or SF as the only dietary fiber source for 36 weeks. Fasting blood samples and feces were collected and analyzed for lipids from individual rabbits. The entire aorta was removed and fixed, and sudanophilic stained lesions were examined visually. Rabbits consuming the SF and/or ISP diets had lower plasma CHOL levels and lower incidence of atherosclerotic lesions relative to the rabbits fed the casein-based cellulose diets. Rabbits consuming the SF and/or ISP diets also had a lower CHOL content in their liver and heart. Rabbits fed ISP-based diets had consistently increased fecal bile acid excretion, whereas rabbits fed diets containing SF had increased fecal and cholesterol concentration. These results suggest a complementary role for SF and ISP in preventing atherosclerosis in rabbits.

Enantioselectivity of asocainol studied at different conditions: a novel approach to check the feasibility of molecular models of antiarrhythmic drug action.

In terms of the "guarded receptor" hypothesis, changes in potency of Na+ channel blocking drugs reflect alterations in drug access to and/or egress from a compartment facing a binding site with constant affinity. Potency is therefore assumed to be determined by changes in drug diffusion, its mobility in the electric field, protonation etc. Hence, the potencies of enantiomers, i.e. compounds with identical physicochemical properties, should be influenced in a parallel manner by the condition. To test this prediction, actions of the enantiomers of the stereoselective antiarrhythmic drug asocainol were compared at various membrane potentials and stimulus frequencies. Several experimental models indicative of Na+ channel block were used: the elevation of the rectangular pulse stimulation threshold (RPT) and the suppression of alternating-current induced arrhythmia (ACT) were studied in guinea-pig atria. The reduction of the upstroke velocity of action potentials was measured in guinea-pig papillary muscles. The inhibition of whole-cell Na+ currents was investigated in isolated guinea-pig ventricular myocytes. In all these assays, (+)-asocainol was more potent than the (-)-enantiomer. Lowering the membrane potential and/or increasing the stimulus frequency enhanced the effects of both enantiomers. However, over a certain range of conditions, the potency of (+)-asocainol was more markedly affected than that of (-)-asocainol, indicating that the eudismic ratio between potencies of the two drugs is not constant. Accordingly, these findings are inconsistent with the guarded receptor hypothesis.

Effects of soybean polysaccharide on plasma lipids.

Free-living volunteers with mild to moderate hypercholesteremia added 25 gm soybean polysaccharide or starch placebo in crouton or cookie form to their normal, daily diets. A total of 31 persons completed the blind, crossover design, 8-week, experimental protocol. Subjects ingesting soybean polysaccharide prior to placebo showed an 11% decrease (from 252 to 224 mg/dl) in total plasma cholesterol; those who followed placebo with fiber showed a 5% decrease (from 241 to 230 mg/dl). Starch placebo was associated with a 2% decrease in total cholesterol when consumed first and a 4% increase when consumed following the fiber consumption period. High-density-lipoprotein (HDL) cholesterol decreased 8% and 6% from initial values during the first period for the fiber and starch groups, respectively. HDL cholesterol increased 2% but decreased 1% during the second period for starch and fiber, respectively. No significant changes in triglyceride levels occurred. The data indicate that soybean polysaccharide fiber promotes a significant decrease in plasma cholesterol in persons with mild to moderate hypercholesteremia. The addition of fiber may represent an important adjunct to traditional fat- and cholesterol-controlled diets for such persons.

Biological availability to the rat of intrinsic and extrinsic iron with soybean protein isolates.

Evaluations were conducted to assess the biological availability of iron in three food grade isolated soybean proteins and to evanuate the influence of these proteins on iron added to the diet from a source of known high biological availability. Ferrous sulfate was used as the standard iron source in all experiments. The biological availability was measured by a 14-day hemoglobin repletion after a 4 week depletion period using multiple dose response and comparing the test samples and standard iron source by the slope ratio assay procedure. The relative iron bioavailability for three isolated soybean proteins was A = 60%; B = 64% and C = 59% with a mean value of 61%. Autoclaving isolated soybean protein B at 108.4 degrees improved iron bioavailability over the unheated samples while isolated soybean protein A was unaffected by this treatment. Iron added to the diets containing isolated soybean protein had bioavailabilities similar to that of iron present in the soybean which supports the common dietary iron pool hypothesis. The high iron content (0.18 mg/g protein) coupled with the bioavailability data make the isolated soybean proteins a good dietary iron source.

Effect of water of hydration on the measurement of the protein efficiency ratio of casein and soybean protein with rats.

The hydration of soybean protein or casein prior to mixing of the diet improves the apparent protein efficiency ratio (PER). The PER of soybean protein was improved more than that of casein, so that an increase in adjusted PER of soybean protein was observed also. The improvement did not appear to be associated with digestibility. It is theorized that some diets with dry protein isolates may be less acceptable to the rat due to the dusty nature of the isolate. Consequently, diets with such isolates may have a lower PER. The effect can be overcome by hydrating the protein isolates prior to mixing the diet.

Effect of isolated soybean protein on magnesium bioavailability.

The effects of isolated soybean protein and animal protein on magnesium bioavailability were evaluated in this study. Total serum magnesium and femur bone ash magnesium values were used to evaluate the relative bioavailability of magnesium in diets in which ANRC casein, isolated soybean proteins, autoclaved isolated soybean proteins or lyophilized beef served as protein sources. Low magnesium basal diets were supplemented with graded levels of magnesium from magnesium carbonate and fed to weanling Sprague-Dawley rats for 28 days. Serum and femur bone ash magnesium were analyzed by atomic absorption spectrophotometry. Statistical analysis of serum and bone ash magnesium using a slope-ratio bioassay indicated that the protein sources did not have a significant effect on the bioavailability of magnesium.

Bioavailability of copper in isolated soybean protein using the rat as an experimental model.

The bioavailability of copper from isolated soybean protein was evaluated with growing rats. Copper depletion and repletion feeding techniques were used to evaluate the biologically available copper. Serum and liver copper contents were used as physiological indication to determine the bioavailability of copper in the diet. Sprague-Dawley male weanling rats were fed a diet low in copper for 21-42 days and then transferred to the test diets containing different levels of copper from copper carbonate or isolated soybean proteins for 7-14 days. Statistical analyses of serum and liver copper by using the slope-ratio bioassay were performed to determine the relative potency of the test products to the copper carbonate standard. The results from four feeding experiments indicate that 1) hypocupremia was produced by feeding a low copper basal diet to weanling rats after 28 days, 2) the time required to replete serum and liver copper was 7 days and 3) copper was available equally from isolated soybean protein and copper carbonate.

Feasibility of intrinsic labeling of poultry meat with stable isotope of selenium (74Se) for use in human metabolic studies.

Sixteen day-old cockerel broiler-type chickens were placed on a simplified, corn-soybean meal broiler starter ration. Each chick was gavaged on 12 separate days over a growth period of 42 days with solutions of Na2SeO3 (control group) or Na74SeO3 (test group). The animals were killed on the 43rd day and the concentrations of the stable isotopes 74Se and 76Se were determined in meat, skin and liver samples using the method of radiochemical neutron activation analysis. We found that significant enrichment of 74Se occurred in the tissues of test animals as compared with the controls and that the degree of enrichment achieved was sufficient to allow use of these chickens in human feeding experiments designed to investigate bioavailability of dietary selenium employing the method of stable isotopes and fecal monitoring.

Comparative measurement of zinc absorption in rats with stable isotope 70Zn and radioisotope 65Zn.

The use of stable isotopes in a study on zinc bioavailability was evaluated in rats by comparing the zinc absorption of a stable isotope 70Zn and a radioisotope 65Zn simultaneously. The rats of low zinc status were obtained by feeding 1.2% phytic acid from sodium phytate and 12 ppm zinc from zinc sulfate in a semipurified diet for 14 days. The rats were then randomly assigned into five groups of ten rats. The rats were intubated with a test diet mixture with a phytate:zinc molar ratio of 0, 6.25, 12.5, 25 or 50 along with one microCi of 65Zn and 0.02 mg of 70Zn in 2.5 ml of intubating solution. Four hours after the intubation, rats were allowed to consume the diets having the same phytate:zinc ratio as used for intubation ad libitum. Feces were collected every 24 hours for a total of 168 hours. The 65Zn and 70Zn content of diets and fecal samples were determined and the percent of zinc absorption was calculated. The results of this study indicated that the zinc absorption determined by these two isotopes were highly correlated with a correlation coefficient ratio of 0.914.

Intrinsic labelling of chicken meat with stable isotopes of zinc, for intended use in human feeding studies: feasibility and design considerations.

1. The feasibility of intrinsically labelling poultry meat with the stable isotopes 68Zn and 70Zn was investigated. 2. Chickens (1-d-old) were gavaged with solutions of 68Zn and 70Zn several times over a 42 d period. 3. Isotopic analysis of edible tissues has shown that they were significantly enriched with respect to the gavaged isotope and that the extent of isotopic enrichment achieved was sufficient to permit their use in human feeding experiments designed to investigate availability of native Zn from such food models. 4. The absolute efficiency of retention of the stable isotopes from gavage solutions in the edible tissues has been calculated to be 2-3% of the administered dose; methods have been suggested to enhance this value, based on considerations of utilization of dietary Zn.

Effect of phytate:zinc molar ratio and isolated soybean protein on zinc bioavailability.

The effect of phytate to zinc (Zn) molar ratio on zinc bioavailability was evaluated in rats. The bioavailability was determined by giving an oral dose of 65Zn and measuring the liver uptake and disappearance from the gastrointestinal tract after 4 hours and fecal and urinary 65Zn excretion from 24 to 168 hours. Rats were fed a diet containing 12 ppm zinc from zinc sulfate with and without phytic acid from sodium phytate for 14 days. At the end of 14 days feeding, the rats were intubated with a homogenized diet containing 12 ppm zinc, one microCi 65Zn and graded levels of phytic acid so that the phytate:Zn molar ratio varied from 0 to 100. Zinc bioavailability was significantly reduced only in the rats fed diets containing phytate and intubated diet containing phytate:zinc molar ratio of 12.5 and above. The results from this study also indicated that measuring 65Zn disappearance and uptake was a valid bioassay for determining zinc bioavailability. The effect of isolated soybean protein on extrinsic zinc bioavailability was also evaluated in rats fed zinc adequate and zinc deficient diets. The results showed that zinc bioavailability was significantly reduced by replacing egg white protein with isolated soybean protein only when the rats were fed zinc deficient diet prior to single oral dose of 65Zn mixed with test proteins. The effect of isolated soybean protein on intrinsic zinc bioavailability for the growing rats was also evaluated. The results demonstrated that the zinc bioavailability in isolated soybean protein can be improved by fortifying with zinc so that the phytate:Zn molar ratio is less than 10.

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.

Simultaneous determination of absorption of selenium from poultry meat and selenite in young men: application of a triple stable-isotope method.

A triple stable-isotope method was used to estimate simultaneously selenium absorption from poultry meat intrinsically labelled with 74Se and from an extrinsic tracer of 76SeO3(2-) in four young adult men. The subjects received an experimental diet based on chicken meat as the source of protein. Two diet periods, lasting from 5 to 10 d, depending on the frequency of stool output for each subject, were conducted to allow duplicate determinations within each subject of Se absorption from both sources. Absorption of Se was determined by the faecal isotope balance procedure through monitoring the stable isotopes 74Se, 76Se and 80Se by means of radiochemical neutron activation analysis. For the separate periods, mean (with SEM) absorption of 74Se from the intrinsically-labelled poultry meat was 70.9 (1.5)% and 72.0 (2.5)%. The absorption of Se from 76SeO3(2-) was 34.7 (5.5)% and 37.6 (3.2)% during the same periods. From these results it is concluded that, under the present experimental conditions, the intrinsic and extrinsic Se isotopes did not form a common pool before absorption. Possible reasons for this are discussed.