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This study determined the nutrient and some anti-nutrient components in Telfairia occidentalis seeds. The work also evaluated the effects of processing on some of the anti-nutritional factors in the seeds as well as growth and animal metabolism. Fresh seeds of T. occidentalis were divided into three groups based on heat treatment: group 1, the unprocessed (raw) seeds; group 2, the under-processed seeds (heat-treated at 70°C for 30 min); and group 3, the processed seeds (cooked at 100°C for 1 hr). Seeds from each group were de-hulled, sun-dried and pulverized. Portions from each group were subjected to proximate composition analysis; trypsin inhibitor and lectin content were also measured in the seeds. The dried seed samples were incorporated into the diets of experimental animals. Twenty albino rats were randomly divided into four groups and fed with the control or experimental diets for a period of 21 days. During this period, body weights of the animals and feed intake were recorded daily and feces and urine were collected. At the end of experimental period, blood samples were collected from the animals for heamatological analysis, then the animals were sacrificed and some key organs were excised for histopathological analysis. Results showed that the seeds contained essential nutrients and that processing significantly affected the lectin and trypsin inhibitor (anti-nutrients) in the seeds. In comparison with control animals, the parameters measured which included body weight gain, nutrient digestibility, nitrogen balance, nitrogen retention and hematological parameters were markedly different among the three groups of animals fed diets incorporated with the seeds. Histopathological analysis indicated that the spleen and small intestines were adversely affected in the experimental animals. In conclusion, T. occidentalis seeds have high nutritive value, but could have deleterious effects in animals if ingested without adequate processing. It could, however serve as a high quality and low cost plant protein source for animal feed formulations provided adequate seed processing is ensured. Key words: seeds, anti-nutrient, processing, metabolism, growth, INTRODUCTION Plant seeds form an important part of human diets and are usually regarded as good foods [1]. The significance of plant seeds especially in the diet of the population [...]

The human proton/oligopeptide cotransporters hPEPT1 and hPEPT2 have been targeted to enhance the bioavailability of drugs and prodrugs. Previously, we established the mechanisms of drug transport by hPEPT1. Here, we extend these studies to hPEPT2. Major variants hPEPT2*1 and hPEPT2*2 were expressed in Xenopus oocytes, and each was examined using radiotracer uptake and electrophysiological methods. Glycylsarcosine (Gly-Sar); the [beta]-lactam antibiotics ampicillin, amoxicillin, cephalexin, and cefadroxil; and the anti-neoplastics [delta]-aminolevulinic acid ([delta]-ALA) and bestatin induced inward currents, indicating that they are transported. Variations in transport rate were due to differences in affinity and in turnover rate: for example, cefadroxil was transported with higher apparent affinity but at a lower maximum velocity than Gly-Sar. Transport rates were highest at pH 5 and decreased significantly as the external pH was increased. Our results strongly suggest that the protein does not operate as a cotransporter in tissues where there is little or no pH gradient, such as choroid plexus, lung, or mammary gland. In the absence of substrates, rapid voltage jumps produced hPEPT2 capacitive currents at pH 7. These transients were significantly reduced at pH 5 but recovered on addition of substrates. The seven-state ordered kinetic model previously proposed for hPEPT1 accounts for the steady-state kinetics of neutral drug and dipeptide transport by hPEPT2. The model also explains the capacitive transients, the striking difference in pre-steady-state behavior between hPEPT2 and hPEPT1, and differences in turnover numbers for Gly-Sar and cefadroxil. No functional differences were found between the common variants hPEPT2*1 and hPEPT2*2. hPEPT2 substrates and drugs; kinetic model of [H.sup.+]/oligopeptide cotransport; polymorphisms

Gastrointestinal (GI) tract leucine metabolism was measured in 6- to 9-mo-old lambs subjected to trickle infection with Trichostrongylus colubriformis larvae and in separate animals that were not infected. Animals prepared with a jejunal catheter and with indwelling catheters into the aorta and the portal- (PDV) and mesenteric- (MDV) drained viscera were infused simultaneously with [1-(super 13)C] and [5,5,5-(super 2)H(sub 3)] leucine to determine GI tract sequestration of leucine from arterial and luminal amino acid pools by tracer and tracee arteriovenous concentration differences. Leucine oxidative losses and net fluxes were also determined across the GI tract. Infection had no detectable effect on whole-body leucine flux, but it increased total GI tract leucine sequestration by 24% (P < .05) and GI tract oxidative losses ofleucine by 22 to 41% (P < .01). Net PDV fluxes of leucine were decreased by 20 to 32% during the infection. The infection did not alter either the proportion of precursor leucine used by GI tract metabolism that was derived from the arterial leucine pool (.84 to .88) or the proportional sequestration of digesta-derived leucine during 'first pass' absorptive metabolism (.12 to .18). These findings help to elucidate the metabolic basis for the reduced growth rates and nitrogen retention observed when animals are subjected to subclinical nematode infection. Key Words: Digestive Tract, Amino Acids, Stable Isotopes, Sheep, Nematoda

We developed a model for assessing iron bioavailability from foods which combines simulated peptic and intestinal digestion with measurement of iron uptake by Caco-2 cell monolayers. Our objective was to further validate this model by determining if meat enhances Caco-2 cell iron uptake relative to casein. Caco-2 cell monolayers were covered with Hank's balanced salt solution (HBSS) buffered with HEPES, pH 7.4. An upper chamber was created over the cells by fitting the bottom of a Costar Transwell[R] insert with a 12,000-14,000 molecular weight cut-off dialysis membrane. This membrane allowed low molecular weight iron complexes to diffuse into the media bathing the cells and prevented damage to the cells from the digestive enzymes. Prior to digestion, each sample (homogenate of beef, chicken, fish or casein) was mixed with 59FeCl3 to achieve an iron concentration of 10 [micro]mol/L. Following pepsin digestion (pH 2), pH was adjusted to 7.4, pancreatic enzymes and bile extract were added to each digest, and an aliquot was then introduced into the upper chamber of the culture dish. During this intestinal digestion period, 59Fe uptake occurred from iron that dialyzed into the lower chamber. The 59Fe uptake from beef, chicken and fish digests was 300-400% of the 59Fe uptake from a casein digest. Our results parallel human absorption studies indicating that meat enhances iron absorption. The results suggest that digestion products of the meat proteins were at least partially responsible for the enhancement of iron uptake. Overall, this study supports the usefulness of our model as a means of assessing iron bioavailability. INDEXING KEY WORDS: Caco-2; in vitro digestion; iron uptake; bioavailability

Bioavailability can be broadly defined as the absorption and utilization of a nutrient, both of which may be affected by such host factors as gender, physiologic state and coexisting pathologic conditions. This report highlights factors of particular importance for the bioavailability of nutrients for infants, children and adolescents. Considerations for nutrient bioavailability for pediatric populations include maturation of the gastrointestinal tract, growth, character of the diet, and nutritional status. Critical periods of development include early infancy (0-6 mo), late infancy/early childhood (6-24 mo) and adolescence (12-18 yr). Iron, zinc and calcium are minerals of particular interest and importance to pediatric populations and are susceptible to alterations in bioavailability. In the young infant, iron and zinc are highly bioavailable from human milk. By ~6 mo of age, other dietary sources are needed to maintain continued normal status. In breastfed infants who were born prematurely or with low birth weight, earlier supplemental iron is often recommended. For the older infant and toddler, iron and zinc are also important for normal growth and development. The bioavailability of these trace minerals in complementary foods is discussed. During adolescence, adequate calcium intake is critical to normal bone mineralization. In girls, peak calcium absorption and calcium deposition in bones occur at or near menarche, which illustrates the importance of the physiologic state on mineral bioavailability. Investigations into nutrient bioavailability must carefully consider these factors, because the failure to have well-matched comparison groups with respect to age and/or nutritional status may inadvertently mask differences in nutrient utilization. J. Nutr. 131' 1351S-1354S, 2001. KEY WORDS: * iron * zinc * calcium * bioavailability * infants * adolescents

The pharmacokinetic behavior of naturally occurring isoflavones has been determined for the first time in healthy adults. We compared plasma kinetics of pure daidzein, genistein and their [Beta]-glycosides administered as a single-bolus dose to 19 healthy women. This study demonstrates differences in the pharmacokinetics of isoflavone glycosides compared with their respective [Beta]-glycosides. Although all isoflavones are efficiently absorbed from the intestinal tract, there are striking differences in the fate of aglycones and [Beta]-glycosides. Mean time to attain peak plasma concentrations ([t.sub.max]) for the aglycones genistein and daidzein was 5.2 and 6.6 h, respectively, whereas for the corresponding [Beta]-glycosides, the [t.sub.max] was delayed to 9.3 and 9.0 h, respectively, consistent with the residence time needed for hydrolytic cleavage of the glycoside moiety for bioavailability. The apparent volume of distribution of isoflavones confirms extensive tissue distribution after absorption. Plasma genistein concentrations are consistently higher than daidzein when equal amounts of the two isoflavones are administered, and this is accounted for by the more extensive distribution of daidzein (236 L) compared with genistein (161 L). The systemic bioavailability of genistein [mean AUC = 4.54 [micro]g/(mL [multiplied by] h)] is much greater than that of daidzein [mean AUC = 2.94 [micro]g/(mL [multiplied by] h)], and bioavailability of these isoflavones is greater when ingested as [Beta]-glycosides rather than aglycones as measured from the area under the curve of the plasma appearance and disappearance concentrations. The pharmacokinetics of methoxylated isoflavones show distinct differences depending on the position of the methoxyl group in the molecule. Glycitin, found in two phytoestrogen supplements, underwent hydrolysis of the [Beta]-glycoside moiety and little further biotransformation, leading to high plasma glycitein concentrations. Biochanin A and formononetin, two isoflavones found in one phytoestrogen supplement, were rapidly and efficiently demethylated, resulting in high plasma genistein and daidzein concentrations typically observed after the ingestion of soy-containing foods. These differences in pharmacokinetics and metabolism have implications for clinical studies because it cannot be assumed that all isoflavones are comparable in their pharmacokinetics and bioavailability. An analysis of 33 phytoestrogen supplements and extracts revealed considerable differences in the isoflavone content from that claimed by the manufacturers. Plasma concentrations of isoflavones show marked qualitative and quantitative differences depending on the type of supplement ingested. These studies indicate a need for improvement in quality assurance and standardization of such products. J. Nutr. 131: 1362S-1375S, 2001. KEY WORDS: * phytoestrogens * isoflavones * pharmacokinetics * soy foods, supplements * humans, blood

Until a few years ago, little was known about bioavailability of micronutrients in elderly humans. It was assumed by many basic investigators and geriatricians that malabsorption of both macronutrients and micronutrients was a common problem among elderly persons. We now know that this is not the case; elderly persons who malabsorb macronutrients do so because of disease, not because of age. This report will be divided into three sections. The first section focuses on the general principles of absorptive processes in elderly persons. The second section focuses on the bioavailability of specific micronutrients in elderly persons, with specific examples of 'problem' nutrients. The third section lays out a proposed research agenda for studying the bioavailability of nutrients and other active components of dietary supplements in elderly persons. J. Nutr. 131: 1359S-1361S, 2001.

Nutrient needs increase during pregnancy and lactation to support fetal growth and milk synthesis, respectively. Physiological adjustments that are made to meet those needs alter the fraction of ingested nutrient retained, or the bioavailability. Using stable isotopes as tracers, we measured calcium, zinc and selenium homeostasis in women during reproduction. The physiological response, and therefore the bioavailability, of these three minerals differed during reproduction. Calcium absorption increased ~2-fold during pregnancy but dropped to values for nonpregnant women during lactation. The calcium needs for lactation were met by renal conservation and bone resorption. In women chronically consuming a low calcium diet, fractional calcium absorption increased to [is greater than] 80% during reproduction. Zinc absorption tended to increase during pregnancy and lactation; renal conservation was not evident at any time during the reproductive cycle. Selenium absorption was high, ~80% of intake, in both pregnant and nonpregnant women. Pregnant women conserved selenium by decreasing urinary selenium excretion. Studies defining the impact of maternal status and the dietary mineral source and amount on mineral bioavailability are needed to determine the potential benefits of mineral supplementation during reproduction. J. Nutr. 131: 1355S-1358S, 2001. KEY WORDS: * calcium * zinc * selenium * pregnancy * lactation * bioavailability

A method for in vitro determination of available calcium, iron and zinc content from infant food after digestion was evaluated. This method introduced an intraluminal digestive phase, adapted to the gastrointestinal conditions of infants younger than 6 months of age, prior to continuous flow dialysis of the resultant gastric digest. Precautions handling the method were discussed and enzymatic parameters were defined. Ruggedness of the method was determined from the availability of calcium, iron and zinc at different gastrointestinal conditions. Availability of all three elements was higher at gastric pH of 2 (20.0 [+ or -] 1.1% for calcium, 4.06 [+ or -] 0.66% for iron and 17.5 [+ or -] 1.3% for zinc), than from the normal procedure (pH 4) (15.6 [+ or -] 1.2% for calcium, 1.18 [+ or -] 0.26% for iron and 8.2 [+ or -] 0.9% for zinc). At pH 5, however, calcium availability appeared to be lower (11.7 [+ or -] 1.0%) (P [is less than] 0.05). The intestinal pH also had a major influence on the availability. At low intestinal pH (5.5), availability was 40.5 [+ or -] 2.3% for calcium, 3.01 [+ or -] 0.58% for iron and 26.8 [+ or -] 1.8% for zinc, which was higher compared with the normal procedure (P [is less than] 0.05). Moreover, other factors, such as digestion time, mixing and filtration pressure, also affected the availability. Recovery tests yielded mean values of 94 [+ or -] 3% for calcium, 109 [+ or -] 9% for iron and 106 [+ or -] 4% for zinc. Mean intra- and inter-batch precision of the availability procedure was 4.1 CV% and 6.6 CV% for calcium, 14.5 CV% and 19.2 CV% for iron, and 4.0 CV% and 13.6 CV% for zinc. The method provides adequate accuracy, acceptable precision and good recovery. It offers the advantage of being simple, rapid and inexpensive, since it takes only I day to run the whole availability procedure (including four replicates per sample), and the low costs of the dialysis equipment. It can therefore be considered as suitable for predicting the availability of essential elements from foods used during the first months of infancy.

Kritsch, K. R., D. J. Huss, and D. M. Ney. Greater potency of IGF-I than IGF-I/BP-3 complex in catabolic parenterally fed rats.--Am. J. Physiol. Endocrinol. Metab. 278: E252--E262, 2000.--We compared the anabolic effects of recombinant human insulin-like growth factor I (rhIGF-I, 2.5 mg/kg) and equimolar amounts of rhIGF-I prebound to rhIGF binding protein-3 (rhIGF-I/BP-3) coinfused continuously with total parenteral nutrition (TPN) solution in dexamethasone (Dex, 70 [micro]g/day ip)-treated male rats for 6 days. The four TPN groups included control, Dex, Dex + IGF-I, and Dex+IGF-I/ BP-3. Pharmacokinetic analysis indicated reduced clearance of IGF-I when infused as IGF-I/BP-3 compared with free IGF-I (0.91 [+ or -] 0.09 vs. 2.01 [+ or -] 0.19 ml serum/min, P [is less than] 0.001) and this was associated with significantly greater serum IGF-I concentrations in the Dex+IGF-I/BP-3 group. Despite greater total serum IGF-I levels, infusion of free IGF-I produced greater anabolic responses than IGF-I/BP-3 based on body weight, nitrogen balance, and jejunal cellularity. Treatment with free IGF-I, but not IGF-I/BP-3, significantly reduced serum insulin and glucose levels that were elevated due to Dex. There were no significant differences in liver IGF-I mRNA levels between groups. Serum IGFBP-3 levels were elevated with infusion of IGF-I/BP-3 compared with IGF-I. These results indicate greater anabolic potency of IGF-I compared with IGF-I/BP-3 when administered by continuous parenteral infusion with TPN solution in catabolic rats. total parenteral nutrition; dexamethasone; bioavailability; pharmacokinetics

Noah Lionel, Michel Krempf, Gerard Lecannu, Pascale Maugere, and Martine Champ. Bioavailability of starch and postprandial changes in splanchnic glucose metabolism in pigs. Am. J. Physiol. Endocrinol. Metab. 278: E181--E188, 2000.--Changes in splanchnic metabolism in pigs were assessed after meals containing slowly or rapidly digested starch. The pigs were fed a mixed meal containing a 'slow' native (n = 5) or a 'rapid' pregelatinized (n = 5) cornstarch naturally enriched with [.sup.13]C]glucose. Absorption of [sup.13]C]glucose was monitored by the arteriovenous difference technique, and infusion of D-[6,[6-.sup.2][H.sub.2]]glucose in the jugular vein was used to calculate the systemic appearance of [sup.13]C]glucose. Arteriovenous balance data obtained during a 12-h study period showed that the fraction of ingested glucose equivalent appearing as glucose in the portal vein was 49.7 [+ or -] 7.2% for the slow starch and 48.2 [+ or -] 7.5% for the rapid starch (P = 0.86). These values, corrected for the gut extraction of circulating [.sup.13]C]glucose, became 66.4 [+ or -] 5.6 and 65.3 [+ or -] 5.6%, respectively (P = 0.35). Isotope dilution data indicated that systemic appearance of exogenous [[.sup.13]C]glucose represented 62.9 [+ or -] 7.6 and 67.4 [+ or -] 3.0% of the oral load for slow and rapid starch, respectively (P = 0.68). Arterial glucose utilization by the gut increased from 7.3 [+ or -] 0.9 [micro]mol [multiplied by] [kg.sup.-1] [multiplied by] [min.sup.-1] before the meal to 8.5 [+ or -] 1.6 [micro]mol [multiplied by] [kg.sup.-1] [multiplied by] [min.sup.-1] during absorption, independently of the nature of the starch. Thus splanchnic glucose metabolism was unaffected by the nature of starch ingested. starch; glucose metabolism; stable isotope