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PubMed1999

Composition of enteral diets and meals providing optimal absorption rates of nutrients in mini pigs.

BACKGROUND: Commercial enteral diets differ widely in nutrient composition. It is unknown whether the nutrient composition of the diets influences intestinal absorption. OBJECTIVE: The objective of this study was to investigate the effects of different enteral diets providing 60% of energy as carbohydrate, protein, or fat or 33.3% of energy from each nutrient on intestinal absorption in mini pigs. DESIGN: Kinetics of nutrient absorption were determined by perfusing a 150-cm jejunal segment. The kinetics of absorption were used to determine optimal relations between the absorption and recovery of each nutrient. From these data, the optimal nutrient composition of the diets providing complete absorption of the macronutrients in the shortest intestinal length was evaluated. Absorption of nutrients was further determined after oral administration of 4 corresponding meals. RESULTS: With all enteral diets, the absorption of nutrients displayed saturation kinetics. Absorption rates of carbohydrate were significantly larger than those of fat and protein. Consequently, the amounts of nutrients remaining unabsorbed per unit length of jejunum differed among the macronutrients. After administration of various test meals, the length of the small intestine required for complete absorption of the nutrients depended on the composition of the meals. The shortest intestinal length for complete absorption was needed for a diet providing 48% of energy as carbohydrate, 23% as protein, and 29% as fat. This composition closely matched the nutritional requirements. CONCLUSION: The nutrient composition of diets can optimize intestinal absorption. This may be especially important in patients with malabsorption or short-bowel syndrome.

Animals↗
PubMed2003

Factors affecting the extent of dermal absorption of solvent vapours: a human volunteer study.

OBJECTIVES: We have previously reported that solvent vapours can be absorbed through the skin and that the extent varies markedly and depends on the chemical. For some chemicals, the extent of absorption is significant, e.g. for 1-methoxy-2-propanol dermal absorption accounts for up to 14% of the total absorbed dose after 8 h exposure at the OES. We have conducted a second study using 2-butoxyethanol to investigate the influence of temperature, humidity and clothing on the dermal absorption of vapours. As for the first study, the extent of dermal absorption was determined by biological monitoring to measure the resultant body burden of the chemical. METHODS: Four volunteers were exposed on nine occasions. For eight of these exposures they wore air-fed half-masks to supply clean air for the inhalation route. The 'baseline' conditions (one 'whole body' and one 'skin only' exposure) were 25 degrees C, 40% relative humidity with volunteers wearing shorts and T-shirt. For each subsequent exposure, a single parameter was changed: humidity (60%, 65%), temperature (20 degrees C, 30 degrees C) or clothing (minimal and overalls). Finally, a 'industrial scenario' was conducted where volunteers wore overalls over their shorts and T-shirts and environmental conditions reflected high temperature and high humidity (30 degrees C, 60%), such as might be encountered in a tank-cleaning operation or similar. RESULTS: Results show that 'baseline' dermal absorption of 2-butoxyethanol vapour was, on average, 11% of the total absorbed dose. Higher temperature (30 degrees C, mean 14%, P = 0.03) and greater humidity (65% RH, mean 13%, P = 0.1) increased dermal absorption. The wearing of whole-body overalls did not attenuate absorption (mean 10%). By combining several factors together in the 'industrial scenario', dermal absorption of vapours was significantly increased with a mean of 39% of the total absorbed dose. CONCLUSIONS: The work has shown that dermal absorption of vapours can be significant and that environmental conditions may affect the absorption. Some types of protective clothing may not be suitable to reduce absorption. The possibility of dermal absorption of vapours should be considered particularly for workers in high vapour concentration conditions where control of exposure relies on respiratory protection.

Adult↗
PubMed1980

Comparative effects of iron deficiency induced by bleeding and a low-iron diet on the intestinal absorptive interactions of iron, cobalt, manganese, zinc, lead and cadmium.

Dietary iron deficiency enhances the absorption of iron, cobalt, manganese, zinc, cadmium and lead, whereas, iron deficiency due to bleeding increases the absorption of iron, cobalt and perhaps manganese. To determine whether the response to bleeding is qualitatively different from that induced by dietary iron deficiency, metal absorption was studied in mice fed either a high-iron diet (120 ppm Fe) and bled (0.5 ml) or fed a low-iron diet (< 3 ppm Fe). Iron absorption from an intragastric dose was increased by the loss of 0.5 ml of blood; smaller losses of blood had no effect. Also, iron absorption was increased more by dietary iron deficiency than by bleeding. In perfusion experiments, bleeding increased the duodenal absorption of only iron and cobalt, whereas dietary iron deficiency enhanced the absorption of all the metals except cadmium. The patterns of absorptive inhibition of the metals by each other were similar in bled mice and in mice with dietary iron deficiency except that interactions among metals with lower affinities for the iron absorption mechanism--manganese, zinc, cadmium and lead--were more obvious in mice fed the low-iron diet. We concluded that bleeding only partially activates the iron absorptive mechanism and that the lack of a bleeding effect on the absorption of manganese, zinc, cadmium and lead results from the weaker interactions of these metals, with a partly-activated absorption process.

Animals↗
PubMed1984

Morphine-neural interactions on canine intestinal absorption and blood flow.

Intestinal Na and H2O fluxes and blood flow were determined in extrinsically denervated or innervated ileum of fed dogs during intra-arterial (0.2, 2, 20 micrograms min-1) or intraluminal (4, 40, 400 micrograms ml-1) morphine sulphate infusion. 3H2O and 22Na were used to determine unidirectional fluxes and 3H2O clearances were used to determine total segmental and absorptive site blood flow. Net Na and H2O absorption decreased with time in innervated gut segments but were unchanged in denervated segments. Intra-arterial morphine prevented the decrease in net Na and H2O absorption in innervated segments due to increases in unidirectional absorptive fluxes. Intra-arterial morphine did not affect absorption in denervated segments. Intraluminal morphine increased net Na and H2O absorption from both innervated and denervated ileal segments due to increases in the unidirectional absorptive fluxes. Absorptive site blood flow was linearly related to unidirectional absorptive Na fluxes in each group although not with the same slopes. The increment in absorptive site blood flow vs. absorptive Na flux was greatest with luminal morphine, intermediate with intra-arterial morphine and in denervated segments without morphine and least in innervated segments. It was concluded that intra-arterial morphine inhibits an antiabsorptive effect of extrinsic nerves and that intraluminal morphine promotes an absorptive effect which could be direct or mediated through intrinsic nerves.

Animals↗
PubMed1969

The absorption of polyvinyl pyrrolidone by the new-born pig intestine.

1. The intestinal absorption of [(131)I]polyvinyl pyrrolidone of mean mol. wt. 160,000 (K. 60) and 40,000 (K. 30) after oral administration has been measured in unsuckled conscious pigs less than 20 hr old. Absorption was assessed by the measurement of the concentration of [(131)I]PVP in venous blood during the 6 hr after feeding and also by the distribution at the end of the experiment of [(131)I]PVP between homogenates of the alimentary tract and homogenates of the rest of the animal.2. The concentration of [(131)I]PVP in the peripheral blood after feeding was dependent upon the mol. wt. of the polymer, when comparable amounts had been absorbed from the intestine. PVP K. 60 attained higher blood concentrations than PVP K. 30 and the blood concentrations of PVP K. 60 were close to the values to be expected if all the material which had left the intestine had remained in the blood. The lower blood concentrations found when PVP K. 30 was fed were associated with the disappearance of labelled solute from the gut and were thus the consequence of the relatively rapid escape of labelled solute from the plasma after absorption had taken place.3. The ability of the intestine to absorb [(131)I]PVP K. 60 declined progressively after birth but did not terminate abruptly unless the animal was fed colostrum. In unsuckled animals the rate and extent of absorption at 3 hr was much greater than at 20 hr after birth, but some absorption was still present at least 65 hr after birth.4. The transfer of PVP K. 60 to the peripheral blood was dependent upon factors in sow colostrum, since significant absorption did not occur when PVP was fed in water or simple salt solutions.5. The factors which accelerated absorption were present in colostrum from the goat, cow and ewe as well as that from the sow; they remained in the whey, but, in contrast to the factors which accelerate absorption in the calf, were largely inactivated by boiling. Similarly, neither phosphate, lactate, pyruvate, nor lower volatile fatty acid salts, which were effective in the calf, accelerated absorption in the pig.6. The absorption of [(131)I]PVP K. 30 was found to be much less dependent upon the composition of the solvent than the absorption of [(131)I]PVP K. 60, although absorption was most rapid when PVP K. 30 was fed in colostrum.

Age Factors↗
PubMed1976

Absorption of xylose, glucose, glycine, and folic (pteroylglutamic) acid in Zambian Africans with anaemia.

Rates of glucose, glycine, and folic (pteroylglutamic) acid absorption were determined for a 30 cm jejunal segment in vivo, with a double-lumen tube perfusion system, in 10 Zambian African women with a mean haemoglobin concentration of 5-1 (3-5-9-2) g/dl. In four the anaemia was megaloblastic (due to folate deficiency) and in six hypochromic. Perfusion solutions contained (1) glucose 200 mmol/1, (2) glycine 100 mmol/1, and (3) folic acid 250 mug/1. D-xylose absorption after a 25 g oral load was determined in them, and also in 18 additional patients (11 had megaloblastic and seven either hypochromic or haemolytic anaemia). Xylose absorption tests were significantly impaired in the patients with megaloblastic compared with hypochromic or haemolytic anaemia (P less than 0-001); those with untreated megaloblastic anaemia had a greater abnormality than those who had started treatment. Mean glucose, glycine, and folic acid absorption rates were similar to those in controls, and the rates in patients with megaloblastic and hypochromic anaemia were not significantly different. Correlation between glucose absorption rate and xylose excretion was, however, significantly (P less than 0-02). If more patients had been studied it seems likely therefore that a significant impairment of glucose absorption rate in the presence of megaloblastic anaemia would also have been demonstrated. In this investigation anaemia per se did not affect glucose, glycine, or folic acid absorption rates or xylose absorption, but xylose absorption was reduced in patients with megaloblastic anaemia. That abnormality was probably related to folate deficiency, and the underlying mechanism seems to be different from that causing impairment of monosaccharide absorption in patients with systemic bacterial infections. Mean glycine and folic acid absorption rates were not altered by megaloblastic anaemia, indicating that folate deficiency does not cause a general depression of absorption.

Adolescent↗
PubMed1998

Regulation of jejunal sodium and water absorption by angiotensin subtype receptors.

The purpose of this study was to determine the precise role of angiotensin subtype-1 (AT1) and -2 (AT2) receptors and the mechanisms by which they act to alter fluid transport in the rat jejunum. In rats on normal sodium intake, ANG II at low dose stimulated net jejunal fluid absorption, whereas at a high dose the peptide inhibited absorption. Low-dose ANG II-stimulated fluid absorption was blocked completely by the specific AT2 receptor antagonist PD-123319 (PD) but was unchanged by the AT1 receptor antagonist losartan (Los). The AT2 receptor agonist CGP-42112A, caused an inversely dose-dependent increase in fluid absorption, which also was totally prevented by PD but was unaltered by Los. Conversely, high-dose ANG II inhibition of absorption was blocked by Los but not by PD. In animals receiving normal sodium intake, neither Los nor PD alone altered fluid absorption. In sodium-restricted animals, however, Los alone increased absorption and PD alone inhibited absorption. In rats on normal sodium intake, low-dose ANG II increased jejunal interstitial and luminal (loop) fluid concentrations of cGMP. These increases in cGMP were blocked with PD but not with Los. 8-Bromoguanosine-3',5'-cyclic monophosphate administered via the mesenteric artery or the submucosal interstitial space markedly increased absorption, but it inhibited absorption when administered into the loop. High-dose ANG II decreased jejunal interstitial and loop fluid cAMP and increased PGE2. The increase in PGE2 was blocked by Los but not by PD. The data demonstrate that ANG II mediates jejunal sodium and water absorption by an action at the AT2 receptor involving cGMP formation. The data also show that ANG II inhibits absorption via the AT1 receptor by a mechanism that is both negatively coupled to cAMP and increases jejunal PGE2 production.

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1979

Effects of intraluminal D-glucose and probenecid on urate absorption in the rat proximal tubule.

The in vivo microperfusion technique was employed to examine urate absorption in the proximal convoluted tubule of the rat kidney using [2-14C]urate as the marker for fractional urate absorption. With NaCl as the perfusion solution, water absorption averaged 2.53 +/- 0.16 nl.min-1.mm tubule-1, and the fractional absorption of [2-14C]urate averages 11.6 +/- 1.0%/mm tubule. The addition of D-glucose (50 mg/100 ml) enhanced water absorption to 3.62 +/- 0.19 nl.min-1.mm tubule-1, but inhibited fractional urate absorption to 6.6 +/- 1.2%/mm tubule. Phloridzin (4.4 mg/100 ml), 2-deoxy-D-glucose (45.6 mg/100 ml), and 3-O-methyl-D-glucose (53.9 mg/100 ml) also inhibited the absorption of [2-14C]urate to the same degree as did D-glucose despite differing effects on water absorption. The addition of probenecid (2.8 mg/100 ml) to the NaCl perfusion solution had no effect on water absorption but inhibited [2-14C]urate absorption to 6.4 +/- 0.6%/mm tubule. The addition of both probenecid and phloridzin further reduced [2-14C-A1urate absorption to 3.8 +/- 0.7%/mm tubule. Probenecid alone had no effect on glucose transport. These studies suggest that the presence of either certain hexose sugars, phloridzin, or probenecid in the lumen of the proximal convoluted tubule inhibits the tubular absorption of urate.

Absorption↗
PubMed1986

Chloride transport by rat renal proximal tubule: effects of bicarbonate absorption.

In the early part of the proximal tubule chloride concentration is increased above that in plasma, a change attributed to preferential absorption of bicarbonate with sodium and water. To determine the mechanism(s) of the preferential absorption of HCO3 over chloride, in vivo paired perfusions were done in surface proximal tubules of the rat kidney. Each tubule was perfused with a control bicarbonate solution, similar in ionic composition to the solution normally present in the early part of the proximal tubule, and one of the experimental solutions that were modified by either replacing all of bicarbonate with sulfate, N-2-hydroxyethylpiperazine-N'-ethanesulfonate (HEPES), or all bicarbonate with sulfate and sodium with lithium, or addition of acetazolamide (ATZ), or cyanide (CN). Sufficient mannitol was added to reduce net fluid flux to zero. When sulfate replaced bicarbonate in luminal fluid, net chloride absorption was enhanced, a change associated with low lumen HCO3 and low pH. ATZ inhibited HCO3 absorption, whereas net Cl absorption increased, an effect associated with high HCO3 and low pH. With HEPES-plus-ATZ solutions, chloride absorption also increased but, in contrast to SO4 or ATZ solutions, pH increased. With sulfate and lithium replacement chloride absorption also increased despite net sodium secretion. CN, a metabolic inhibitor, inhibited HCO3 and sodium absorption but stimulated net chloride absorption. The data indicate that HCO3 absorption inhibits chloride absorption, a process independent of luminal HCO3 per se, luminal pH, sodium absorption, and transepithelial volume flux and voltage.

Absorption↗
PubMed1974

Use of inert gases and carbon monoxide to study the possible influence of countercurrent exchange on passive absorption from the small bowel.

The purpose of the present study was to quantitate the influence of countercurrent exchange on passive absorption of highly diffusible substances from the small intestine of the rabbit. The absorption of carbon monoxide, which is tightly bound to hemoglobin and therefore cannot exchange, was compared to the absorption of four unbound gases (H(2), He, CH(4), and (133)Xe), which should exchange freely. The degree to which the observed absorption of the unbound gases falls below that predicted from CO absorption should provide a quantitative measure of countercurrent exchange.CO uptake at high luminal Pco is flow-limited and, assuming that villus and central hemoglobin concentrations are equal, the flow that equilibrates with CO (F(co)) was calculated to equal 7.24 ml/min/100 g. The observed absorption rate of the unbound gases was from two to four times greater than would have been predicted had their entire uptake been accounted for by equilibration with F(co). This is the opposite of what would occur if countercurrent exchange retarded absorption of the unbound gases. The unbound gases have both flow- and diffusion-limited components, and F(co) should account for only the fraction of absorption that is flow limited. A simple model of perfusion and diffusion made it possible to calculate the fraction of the total uptake of unbound gases that was flow limited. This fraction of the total observed absorption rate was still about 1.8 times greater than predicted by CO absorption. A possible explanation for this discrepancy is that plasma skimming reduces the hemoglobin of villus blood to about 60% of that of central blood. Thus, F(co) is actually about 1.7 times greater than initially calculated, and with this correction, there is close agreement between the predicted and observed rates of absorption of each of the unbound gases. We conclude that countercurrent exchange does not influence passive absorption under the conditions of this study.

Animals↗
PubMedDate not supplied

3-0 methylglucose uptake as a marker of nutrient absorption and bowel length in pediatric patients.

BACKGROUND: Inert carbohydrate probes are commonly used to assess intestinal permeability; we have previously shown that the actively transported moiety 3-0 methylglucose (3-0 MG) is a useful marker of intestinal surface area and nutrient absorption in animal models of short bowel syndrome (SBS). This study examines the correlation of 3-0 MG absorption with nutrient absorption, bowel length, and the tolerance of enteral feeds in pediatric patients. METHODS: Fifteen children (1 month to 15 years in age) were studied after intestinal surgery. All had a stoma, 2 were > 1 year of age, the remainder had surgical intervention as a neonate or within the first month of life. Eight had SBS (50% expected bowel length for age). Bowel length was measured intraoperatively. Nutrient absorption was quantified with a 48-hour bowel study, measuring fat, protein, and carbohydrate output directly. 3-0 MG absorption and intestinal permeability were quantified using a solution containing 30 mg/mL 3-0 MG, 20 mg/mL mannitol and 30 mg/mL lactulose (osmolarity 352, given at 1 mL/kg via feeding tube). Subsequent urine production was collected for 8 hours, and probe recovery measured using HPLC. RESULTS: 3-0 MG absorption was significantly correlated with nutrient absorption. The correlation with protein absorption was r2 = .59, fat r2 = .62 and carbohydrate r2 = .56. The correlation between 3-0 MG absorption and bowel length was r2 = .58. 3-0 MG absorption was significantly lower in SBS patients vs patients with normal bowel length (15.8 +/- 6.7 vs 30.5 +/- 10.2%). 3-0 MG absorption also correlated with the ability to tolerate enteral feeds (r2 = .38; p < .03 for all comparisons). CONCLUSIONS: 3-0 MG may be a useful marker of nutrient absorption and bowel length in pediatric patients with short bowel syndrome. The simplicity and reproducibility of the method make it an attractive option for following patient outcomes. Further studies are suggested to determine the utility of these markers in directing the clinical management of patients.

3-O-Methylglucose↗
PubMed1996

Thiamine absorption in alcoholic delirium patients.

OBJECTIVE: The role of a deficiency of vitamin B1 in the development of alcoholic complaints is confined to the case of the Wernicke-Korsakov syndrome. Findings concerning a deficiency of thiamine in alcoholics in comparison with normal persons are contradictory and there are no differentiated tests in the case of delirium tremens. In this study the vitamin B1 absorption in patients with delirium tremens was of interest in connection with the presence or absence of hallucinations and autonomic symptoms. METHOD: Male patients (N = 70) with delirium tremens were compared with a group of 13 controls. The controls and patients were hospitalized in order to ensure abstinence from alcohol. The examination of the delirium patients was carried out with their consent after termination of the delirium tremens and again on discontinuance of drug therapy. In the case of 33 delirium patients the absorption of thiamine was tested again 4 weeks after the first examination. RESULTS: The absorption of vitamin B1 was in general only minimally lower in the case of the delirium patients in comparison with the nonalcoholics. The results showed, however, a considerably greater range of scattering of vitamin B1 absorption in the delirium patients. The absorption conditions showed marked improvement in the 4 weeks after delirium. The extent of absorption of vitamin B1 showed no influence on the duration of delirium. The patients with visual hallucinations, however, showed lower thiamine absorption than patients without such symptoms, whereas no dependence of autonomic symptoms on vitamin B1 absorption was seen. CONCLUSIONS: The disturbed absorption conditions in the delirium patients were obvious at the time of the examination as demonstrated by the wide range of absorption values. Improvement or near normal conditions were registered 4 weeks after the delirium. The absorption conditions had possibly already improved during the few days of alcohol abstinence in the course of the delirium treatment. The reduced vitamin B1 absorption of patients suffering from visual hallucination corresponds to observations of alcoholic hallucinosis.

Adult↗
PubMed2000

Low fractional calcium absorption increases the risk for hip fracture in women with low calcium intake. Study of Osteoporotic Fractures Research Group.

BACKGROUND: Decreased ability to absorb calcium with age limits adaptation to low calcium intake and is thought to lead to secondary hyperparathyroidism and increased risk for hip and other fractures. However, the associations between fractional calcium absorption, dietary calcium intake, and risk for fracture have never been studied. OBJECTIVE: To determine whether low fractional calcium absorption in women with low calcium intake increases the risk for subsequent hip and other nonspine fractures. DESIGN: Prospective cohort study. SETTING: Four clinical centers in Baltimore County, Maryland; Portland, Oregon; Minneapolis, Minnesota; and the Monongahela Valley, Pennsylvania. PARTICIPANTS: 5452 nonblack women 69 years of age or older participating in the fourth examination of the Study of Osteoporotic Fractures. MEASUREMENTS: Fractional calcium absorption was measured by using a 3-hour single isotope (45Ca) technique. Incident fractures were identified prospectively and were confirmed by radiographic report. RESULTS: During an average of 4.8 years, 729 women (13%) experienced at least one nonspine fracture; 153 of these women had hip fractures. After adjustment for age, women with lower fractional calcium absorption were at increased risk for hip fracture (relative risk per 1-SD [7.7%] decrease in fractional calcium absorption, 1.24 [95% CI, 1.05 to 1.48]). Women with low fractional calcium absorption and low calcium intake were at greatest risk for subsequent hip fracture; among women whose dietary calcium intake was less than 400 mg/d, those who had fractional calcium absorption at or below the median value of 32.3% had a 2.5-fold (CI, 1.29-fold to 4.69-fold) increase in risk for hip fracture compared with those who had greater absorption efficiency. Fractional calcium absorption was not related to risk for other nonspine fractures (relative risk per 1-SD [7.7%] decrease in fractional calcium absorption, 1.05 [CI, 0.96 to 1.14]). CONCLUSIONS: In elderly women, low fractional calcium absorption in the setting of low calcium intake increases the risk for hip fracture. Our findings support the hypothesis of type II osteoporosis, which postulates that decreased calcium absorption is an important risk factor for hip fracture in older persons.

Aged↗
PubMed1975

Effect of sodium, mannitol, and magnesium on glucose, galactose, 3-O-methylglucose, and fructose absorption in the human ileum.

Although it is generally agreed that active sugar absorption in vitro is absolutely dependent on the presence of sodium ions on the luminal side of the mucosa, previous in vivo studies in the ileum of rat, dog and man have shown that active glucose absorption is almost as rapid from a sodium-free mannitol solution as from a sodium chloride solution. These experiments were performed in hopes of reconciling this discreptancy. Absorption of three actively transported sugars (glucose, galactose, and 3-O-methylglucose) having different apparent Km's, and of fructose (absorbed by a separate carrier-mediated process) were measured in the human ileum in vivo. The following observations were made: (1) Mannitol substitution for sodium results in only a slight reduction (23%) in the active absorption of glucose. (2) Magnesium substitution for sodium results in a greater depression (45%) of glucose absorption. (3) The apparent Km for glucose absorption is increased when sodium is replaced by magnesium, but the Vmax is not altered. (4) Magnesium does not depress glucose absorption or the apparent Km for glucose transport when sodium is present in the perfusing solution. (5) Neither sodium removal nor magnesium has any effect on fructose absorption. (6) Absorption of galactose and 3-O-methylglucose (low affinity sugars for the glucose carrier) is reduced by about 40 to 50% when mannitol replaces sodium, but magnesium substitution for mannitol in a sodium-free medium does not further depress absorption of these sugars. The following conclusions are suggested by these results: First, part of the discrepancy between previous in vitro and in vivo experiments was due to the type of test sugar (glucose versus glucose analogue) and the solute used to replace sodium in the luminal solution. Second, magnesium is more effective than mannitol in reducing sodium concentration at the glucose transport site on the brush border. Third, luminal sodium ions have an important effect on active sugar absorption in the human small intestine in vivo, as they do in vitro. And, fourth, there is a component of active sugar absorption (about one-half) which appears to be independent of luminal sodium ions in vivo.

Adult↗
PubMed1992

Magnesium and calcium absorption in Fischer-344 rats influenced by changes in dietary fibre (wheat bran), fat and calcium.

Magnesium and calcium absorption were affected by changes in dietary wheat bran fibre and calcium, but not fat, in Fischer-344 rats when studied in a full factorial study which was a portion of a larger study of diet and colon carcinogenesis. For four weeks, nine-week-old rats were fed experimental purified diets to which had been added: wheat bran 0, 2.5 10, or 20%; fat 1, 5 or 10%; and calcium 0.18, 0.52, or 1.04% of diet weight. From day 26 to 29 all faeces were collected in metabolic cages, and food consumption noted. Dietary magnesium intake and net magnesium absorption increased in direct relation to the quantity of wheat bran in the diet. Calcium supplementation inhibited magnesium absorption on fibre-free diet, but had little effect on magnesium absorption when fibre was present. Fat had no measurable effect on magnesium absorption. A low dietary fibre content enhanced Ca absorption compared to that on a fibre-free diet. However, further increases in fibre content slightly inhibited calcium absorption. We conclude that the magnesium content of dietary wheat bran fibre is available for absorption to rats. Calcium supplementation inhibits magnesium absorption in a fibre-free diet, but presence of dietary fibre protects magnesium absorption from the calcium inhibition observed on a fibre-free diet. Absorption of calcium is increased by including some fibre in the diet. However, calcium absorption may be diminished slightly by increasing wheat bran content of the diet to a high level, probably through calcium binding and excretion with undigested fibre.

Animals↗
PubMed2005

[Absorptional function of the small bowel in patients with chronic obstructive bronchitis].

The purpose of the study was to evaluate intestinal absorption of fats, proteins and carbohydrates in patients with chronic obstructive bronchitis (COB) depending on the functional condition of the lungs, and clinical manifestation of its disorder. Fat, protein and carbohydrate absorption was studied in 68 COB patients. Lung ventilation was evaluated by means of spirography, pulmonary gas exchange--via measurement of paO2 of arterialized capillary blood by Astrup method. Fat absorption was evaluated using Kamer method and radioindication with 131I-trioleate-glycerine and 131I-oleic acid; protein absorption was determined using 131I-albumin; carbohydrate absorption was determined by d-xylose test. The study demonstrated that deterioration of respiratory and ventilatory pulmonary functions in patients with COB impaired fat, protein and carbohydrate absorption: paO2 > or = 70 mmHg and ventilatory insufficiency (VI) I were associated with an significant reduction of fat absorption by 49% on the average, protein--by 23%, carbohydrates--by 15%; paO2 = 70-40 mmHg and VI II-III--with reduction of these parameters by 104%, 69%, and 41%, respectively. The results show a direct correlation between body weight (BW) deficit and the reduction of fat, protein, and carbohydrate absorption (r = 0.549, 0.707, and 0.482, respectively) in COB patients. The most prominent was the correlation between BW deficit and the reduction of protein absorption. Thus the study of intestinal absorption of fats, proteins and carbohydrates in patients with COB demonstrates not only reduction of absorption, correlating with the degree of the impairment of ventilatory and respiratory pulmonary functions, but also direct correlations between BW deficit and reduction of fat, protein and carbohydrate absorption.

Adult↗
PubMed2006

[Effect of absorption enhancers on nasal ginsenoside Rg1 delivery and its nasal ciliotoxicity].

AIM: The enhancing activity and safety of several absorption enhancers were evaluated as potential nasal absorption enhancers to increase intranasal absorption of ginsenoside Rg1. METHODS: Nasal circulatory perfusion test in vivo had been employed to investigate the effect of absorption enhancers for nasal mucosa absorption of ginsenoside Rgl in rats. The safety of the absorption enhancers were evaluated by testing cilia movement of the in situ toad palate model, the hemolysis of erythrocyte membrane of the rabbit, leaching of protein and LDH from the mice nasal mucosa and the effect on cilia structural and specific cellular changes of nasal mucosa. RESULTS: Absorption enhancers were necessary to facilitate ginsenoside Rg1 absorption by nasal mucosa. Among the absorption enhancers 1% sodium deoxycholate had great effect to facilite ginsenoside Rgl absorption by nasal mucosa; 1% dipotassium glycyrrhizinate and 1% azone had moderate effect to facilitate ginsenoside Rg1 absorption by nasal mucosa; 1% Tween-80, 2% beta-cyclodextrin, 0.5% borneol (dissolved in paraffin liquid), 0.5% chitosan, 5% hydroxypropyl-beta-cyclodextrin and 0.1% EDTA had low effect to facilitate ginsenoside Rgl absorption by nasal mucosa. 1% sodium deoxycholate, 1% azone and 1% dipotassium glycyrrhizinate had serious nasal toxicity; 1% Tween-80, 2% beta-cyclodextrin, 5% hydroxypropyl-beta-cyclodextrin had moderate nasal toxicity; 0.5% borneol (dissolved in paraffin liquid), 0.5% chitosan and 0.1% EDTA have little nasal toxicity. CONCLUSION: 0.5% borneol and 0.5% chitosan were the promising candidates having a good balance between enhancing activity and safety for nasal ginsenoside Rg1 delivery.

Absorption↗
PubMed1990

In vivo intestinal absorption of calcium in humans.

We reviewed data on calcium absorption in humans, mainly focusing on concentrations of soluble calcium in the gut, kinetics of absorption, correlation of net absorption with serum 1,25-(OH)2-vitamin D, and adaptation to different intakes. We conclude: (a) most of the unabsorbed food calcium is insoluble when it reaches the terminal ileum; (b) calcium absorption in jejunum is both active and passive with active component being dependent on vitamin D; ileal absorption is also highly dependent on vitamin D, but it is uncertain whether this action is on the active or passive component; (c) the relative role of vitamin D-dependent and vitamin D-independent mechanisms to dietary calcium absorption depends upon serum 1,25-(OH)2-D level and calcium intake; (d) over short periods, the gut reduces calcium absorption much more in response to a high-calcium diet than it increases absorption in response to a low-calcium diet. We also evaluated the measurement of 'true' calcium absorption by isotopic methods. By ignoring isotopic equilibration, these methods overestimate both the amount of calcium secreted into and absorbed from the gut. Since altered gut physiology and pathology can variably affect isotopic equilibration, 'true' absorption may not reflect absorption of dietary calcium in an individual patient. Moreover, only net absorption has metabolic and nutritional significance.

Adaptation, Physiological↗