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At least 127 records · Page 7Linked to original sources
PubMed1975

Food iron absorption. I. Use of semisynthetic diet to study absorption of nonheme iron.

Recent studies have established the validity of employing an extrinsic radioiron tag to measure the absorption of nonheme iron from a complex meal. In the present study, extrinsic tagging was used to measure absorption of nonheme iron from a standard meal chosen as representative of a typical American meal, and from a semisynthetic meal having the same total chemical composition. The latter was designed so that the major dietary components could be systematically altered to determine their separate effects on food iron absorption. Absorption from the standard meal in 32 healthy women averaged 10.0% as compared with a mean absorption of 1.8% from semisynthetic meal. Most but not all of this fivefold difference in absorption could be explained by the enhancing effect of meat in the standard meal. The low availability of iron from the semisynthetic meal will be of particular value in studying factors which enhance food iron absorption, whereas the standard meal is suitable for studying factors which reduce availability of food iron.

Absorption↗
PubMed1981

Lymphatic absorption of shellfish sterols and their effects on cholesterol absorption.

Studies have been conducted on the absorbability of individual sterols from a mixture of oyster sterols when administered intragastrically to rats with indwelling catheters in the left thoracic duct. In addition, the effect of oyster sterols on cholesterol absorption has been assessed using [4-14C] cholesterol in the mixture, and comparison against absorption of cholesterol alone. The order of absorbability (percentage absorption) of individual sterols from the mixture of oyster sterols was: cholesterol greater than or equal to 26-carbon sterols greater than or equal to dehydrocholesterol greater than 24-methylene cholesterol greater than brassicasterol greater than plant sterols. The absorption of noncholesterol sterols was 8.2 +/- 0.8% of the fed dose, or less than half of that for an equivalent level of cholesterol alone. The presence of these sterols in mixtures containing cholesterol reduced lymphatic absorption of cholesterol by 25 to 40% compared to absorption of the same amount of cholesterol administered alone, or to an amount of cholesterol equal to the total oyster sterols, respectively. These studies suggest that shellfish sterols are poorly absorbed, and, like plant sterols, effectively reduce dietary and/or endogenous cholesterol absorption from the intestine.

Absorption↗
PubMed1980

Digestion and absorption of casein at different dietary levels in the chick: effect on fatty acid and bile acid absorption.

The site of digestion and absorption of protein was determined in chicks fed diets containing 10, 30 and 45% casein as the protein source, 3% added oil with 91Y Cl3 added as a non-absorbed reference substance. Digestion of protein to low molecular weight (MW) peptides and amino acids was rapid in all diets with major absorption occurring between duodenum and lower jejunum. Increasing the dietary casein resulted in increases in low MW peptide levels in the duodenum. This increase was disproportionate with intake when 45% casein was fed, suggesting that absorptive capacity of the duodenum was exceeded. Overall nitrogen absorption was similar in all treatments reflecting the increased participation of the ileum in nitrogen absorption when high dietary casein levels were fed. Fatty acid and bile acid absorption was depressed when 45% casein was fed, mainly due to inhibition of absorption in the ileum, presumably by binding to undigested protein.

Animals↗
PubMed1994

Dietary tannins from cowpeas and tea transiently alter apparent calcium absorption but not absorption and utilization of protein in rats.

Tannins reportedly alter absorption and utilization of protein and minerals. The present study investigated the effect of tannins extracted from 'Mississippi Silver' cowpeas and black tea when incorporated into nutritionally balanced diets. Condensed tannins were incorporated into the diet of weanling male Sprague-Dawley rats at 0.0, 0.0057, 0.0171 and 0.057 g/100 g diet for 28 d. Ingestion of tannin from cowpeas or tea did not change significantly growth rate, protein efficiency ratio, apparent protein digestibility, nitrogen excretion, relative liver weight, or nitrogen concentration of liver. During d 11-18, apparent calcium absorption was lower in rats fed the medium and high levels of cowpea tannin and in those fed all levels of tea tannin compared with the control group. By wk 4, no differences were observed in apparent calcium absorption among treatment groups. Apparent magnesium absorption was not affected by dietary treatment, nor was femur content of calcium or magnesium. We conclude that at the levels of condensed tannins fed, a short-term reduction of apparent calcium absorption occurred; however, by wk 4 calcium absorption was comparable to that of the control group. The acute change that occurred in apparent calcium absorption did not influence bone calcium content.

Absorption↗
PubMed1994

Intestinal drug absorption during induced net water absorption in man; a mechanistic study using antipyrine, atenolol and enalaprilat.

1. The effect of induced water absorption on the intestinal permeability of antipyrine, atenolol and enalaprilat in the proximal jejunum was studied in eight healthy subjects with a regional intestinal perfusion technique. 2. The mean (+/- s.d.) net water flux changed from a secretory status of 1.2 +/- 1.2 ml h-1 cm-1 to an absorptive status of -3.7 +/- 3.5 ml h-1 cm-1 (P < 0.0025) on the introduction of a hypo-osmolar glucose-containing electrolyte solution. 3. The mean permeability values for the three drugs in the eight subjects were unchanged despite the increase in net water absorption (5.7 +/- 3.0 to 7.0 +/- 3.6 x 10(-4) cm s-1 for antipyrine, 0.1 +/- 0.2 to 0.2 +/- 0.2 x 10(-4) cm s-1 for atenolol and 0.3 +/- 0.3 to 0.1 +/- 0.2 x 10(-4) cm s-1 for enalaprilat). One subject showed a large change in the permeability for antipyrine and atenolol in parallel with a large increase in water absorption, but enalaprilat was unaffected. 4. The luminal recovery of PEG 4000 was similar before (100 +/- 4%) and during (101 +/- 7%) induction of water absorption, which indicates that the barrier function of the intestine appears to be maintained during glucose-stimulated fluid absorption in man. 5. We conclude that induced net water absorption in man does not influence the paracellular permeability of hydrophilic drugs or drugs with high molecular weight to any significant extent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Mechanisms of absorption of inorganic mercury from rat small intestine. I. Solvent drag effect on absorption of inorganic mercury.

A correlation of mercury absorption with water absorption was investigated by using the perfusion of rat small intestine with buffers containing 10(-4) M HgCl2. With a decrease in the osmolarity of the buffers or with increases in the sodium ion and urea concentrations in the buffers, absorption of water and mercury and accumulation of mercury in the intestinal tissue increased, and the increases in mercury absorption and accumulation were found to correlate with the increase in water absorption. Both the decrease in osmolarity and the increase in sodium ion concentration increased mercury accumulation in the epithelial cell after the perfusion. But these changes did not alter the mercury distribution in subcellular fractions. The results suggest that the increase in water absorption due to the hyptonicity or the increase in concentration of sodium ion or urea increases the mercury absorption and accumulation in the epithelial cell without change in the distributional pattern of mercury in the cell.

Adenosine Triphosphate↗
PubMed1994

Absorption enhancement of intrapulmonary administered insulin by various absorption enhancers and protease inhibitors in rats.

The effects of absorption enhancers and protease inhibitors on the pulmonary absorption of insulin were examined by means of an in-situ pulmonary absorption experiment. Absorption enhancers used in this study were sodium glycocholate, linoleic acid-surfactant mixed micelles and N-lauryl-beta-D-maltopyranoside whereas aprotinin, bacitracin and soybean trypsin inhibitor were used as protease inhibitors. The absorption of insulin from the lung was evaluated by its hypoglycaemic effect. In the absence of these additives, a slight hypoglycaemic effect was obtained following intrapulmonary administration of insulin. However, we found significant and continuous hypoglycaemic effects after the insulin administration with these additives. N-Lauryl-beta-D-maltopyranoside and bacitracin appeared to be more effective for enhancing the pulmonary absorption of insulin than the other adjuvants. These findings suggest that the use of these two adjuvants would be a useful approach for improving the pulmonary absorption of insulin.

Absorption↗
PubMed1972

The role of the pancreas in vitamin B 12 absorption: studies of vitamin B 12 absorption in partially pancreatectomized rats.

The effect of partial pancreatectomy (80-90%) on vitamin B(12) absorption was studied in the rat. The absorption of 5 ng of (57)Co-labeled vitamin B(12) was significantly reduced from 70 +/-2.5% (mean +/-SE) in control and sham-operated rats to 32 +/-2.6% in partially pancreatectomized rats. Hog pancreatic extract (0.17 g/kg) improved vitamin B(12) absorption from 30.0 to 61.0% in partially pancreatectomized rats but did not alter vitamin B(12) absorption in control rats. Chloramphenicol did not enhance vitamin B(12) absorption in partially pancreatectomized rats with pancreatic extract-improved vitamin B(12) malabsorption. The partially pancreatectomized rats with pancreatic extract-improved vitamin B(12) malabsorption were sacrificed and the stomach and small bowel studied in vitro to further define the pathogenesis of the vitamin B(12) malabsorption. Rat gastric intrinsic factor stimulated vitamin B(12) uptake by intestinal sacs prepared from partially pancreatectomized rats 3.1-fold. Gastric intrinsic factor prepared from partially pancreatectomized rats was as effective in promoting vitamin B(12) uptake by rat intestinal sacs as intrinsic factor prepared from control rats. These data indicate that partially pancreatectomized rats develop an abnormality in the absorption of labeled vitamin B(12) which can be corrected by pancreatic extract. The vitamin B(12) malabsorption is due to neither an alteration in gastric intrinsic factor activity nor an impairment of the intrinsic factor-vitamin B(12) receptor in the intestine. It is suggested that in the partially pancreatectomized rats the intrinsic factor-vitamin B(12) complex exists in a form which is not available for absorption.

Animals↗
PubMed2002

Aminated gelatin as a nasal absorption enhancer for peptide drugs: evaluation of absorption enhancing effect and nasal mucosa perturbation in rats.

This study was carried out to evaluate the potential of aminated gelatin as a nasal absorption enhancer for peptide drugs. The absorption-enhancing effect was investigated in rats using insulin and fluorescein isothiocyanate-dextran with a molecular weight of 4.4 kDa (FD-4) as model drugs. The absorption of insulin was estimated by measuring the changes in plasma glucose levels following intranasal administration, and that of FD-4 was determined by measuring its plasma concentration after dosing. The hypoglycaemic effect after intranasal administration of insulin with aminated gelatin significantly increased compared with that after intranasal administration of insulin in phosphate buffered saline, indicating that aminated gelatin effectively enhanced the nasal absorption of insulin. In contrast, neither kind of native gelatin (isoelectric point = 5.0 and 9.0) showed any absorption-enhancing effect. The pH of the formulations and the concentration of aminated gelatin were found to affect the hypoglycaemic effect. In addition, aminated gelatin at a concentration of 0.2% significantly enhanced the absorption and the efflux of FD-4 through the rat nasal mucosa. The possible perturbation of aminated gelatin to nasal mucosa was evaluated by measuring the leaching of lactate dehydrogenase (LDH) using an in-situ perfusion rat model. Aminated gelatin presented a concentration-dependent (0.1-0.4%) but relatively small effect on the LDH leaching from the rat nasal epithelial membrane. These results suggest that positively charged aminated gelatin could be a new absorption enhancer for nasal delivery of peptide drugs.

Absorption↗
PubMed1993

Effects of various absorption promoters on pulmonary absorption of drugs with different molecular weights.

The effects of various absorption promoters on the pulmonary absorption of drugs with different molecular weights were examined in rats. Phenol red and fluorescein isothiocyanate-labeled dextrans (FDs) with various molecular weights were used as model drugs and the absorption promoters used in this study were sodium glycocholate, sodium salicylate, ethylenediaminetetraacetic acid disodium salt (Na2-EDTA) and sodium caprate, all at a concentration of 1%. Of these absorption promoters, sodium glycocholate and sodium caprate appeared to be more effective for enhancing the pulmonary absorption of these drugs than sodium salicylate and Na2-EDTA. Furthermore, it was indicated that there is the optimal molecular weight to which each absorption promoter gives the largest enhancing effect on the pulmonary absorption of drugs.

Absorption↗
PubMed1975

Dietary iron absorption in pregnancy - a longitudinal study with repeated measurements of non-haeme iron absorption from whole diet.

In 22 healthy women the non-haeme iron absorption (bone-marrow smears and haematological parameters) was studied at the 12th, the 24th and the 36th week of gestation and two months after delivery. In eight non-pregnant women and in seven pregnant women (at the 36th week of gestation) the absorption of food iron was measured from different types of meals. The iron absorption was measured from radioiron-labelled test meals using a whole-body counter with a very high sensitivity. During pregnancy the non-haeme iron absorption increased continuously from less than 1 % in early pregnancy to almost 15 % in late pregnancy. Calculations indicated that the amount of iron absorbed from the diet covered only about half of the demands. The increasing absorption of food iron during pregnancy seems to be related to the still more increasing demands. However, the very low absorption values in early pregnancy was quite unexpected. The amount of iron absorbed was actually below the basal demands, which means that even in early pregnancy, for reasons unknown, there is a negative iron balance. Further studies are necessary to elucidate the significance of this finding. Two months after delivery the absorption of iron from the diet was increased compared to in non-pregnant women and exceeded the demands at that phase thus indicating that a positive iron balance was achieved.

Adult↗
PubMed1982

Oral magnesium load test for the assessment of intestinal magnesium absorption. Application in control subjects, absorptive hypercalciuria, primary hyperparathyroidism, and hypoparathyroidism.

The intestinal absorption of magnesium (Mg) was estimated from the increment in urinary Mg following oral administration of 25 mmol of Mg. Fasting urinary Mg did not differ between the control group and patient groups (absorptive hypercalciuria, primary hyperparathyroidism, and hypoparathyroidism). As compared to the value in the control group, the increment in urinary Mg above the fasting value was not significantly different in absorptive hypercalciuria. However, it was significantly increased in primary hyperparathyroidism and significantly reduced in hypoparathyroidism. In control subjects, the increment in urinary Mg was much higher during a low than during a high calcium diet. The results suggest that 1,25-(OH)2-vitamin D stimulates Mg absorption, since Mg absorption was elevated in situations associated with stimulated 1,25-(OH)2-vitamin D synthesis (primary hyperparathyroidism and low calcium diet) and reduced in a condition characterized by low 1,25-(OH)2-vitamin D production (hypoparathyroidism). Moreover, the data indicate that 1,25-(OH)2-vitamin D may not be pathogenetically important in absorptive hypercalciuria, since Mg absorption was normal.

Adult↗
PubMed1996

Local absorption kinetics into the portal system using the portal-venous concentration difference after an oral dose of diclofenac in the awakening rat. Accelerative effect of bile on intestinal absorption of diclofenac.

The local absorption kinetics from the intestinal tract into the portal system was evaluated using the portal-venous concentration difference (P-V difference) after oral administration of diclofenac in conscious rats. The local absorption ratio (Fa), mean local absorption time (ta), and relative variance (sigma 2/ta2) from the intestinal tract into the portal system were estimated by simultaneously measuring the portal and venous concentrations, using diclofenac as a model drug. The effect of bile on diclofenac intestinal absorption was also investigated. The awakening rats simultaneously cannulated into the jugular and portal veins were divided into group A with intact enterohepatic circulation (EHC) and into another group with bile-duct cannulation to block EHC. The rats in the latter group were further divided into group B without the bile supply to the intestinal tract and into group C with the bile supply from the other rat. After oral administration of diclofenac to rats in groups A, B, and C, the portal and venous concentrations of diclofenac in each rat were simultaneously monitored by HPLC method at proper time intervals. The absorption time profile of diclofenac into the portal system was directly predicted from P-V difference. Plasma concentrations of diclofenac in the portal vein were constantly higher than those in the jugular vein after the oral administration. It was demonstrated that P-V difference was caused by absorption from the intestinal tract into the portal system. Fa in groups A, B, and C were estimated to be 91.5% for 8 hr, 33.8% for 3 hr, and 57.8% for 3 hr, respectively. ta in groups A, B, and C were estimated to be 2.26 hr, 0.65 hr, and 0.96 hr, respectively. sigma 2/ta2 in groups A, B, and C were 1.31, 0.48, and 0.55, respectively. Fa and ta of diclofenac extensively increased in the presence of the bile in the intestinal tract, whereas sigma 2/ta2 was unaffected by the bile. The mean absorption time (MAT) almost agreed with ta, which demonstrates that the mean transit time through the liver (tH) is negligible in MAT(= ta+tH).

Administration, Oral↗
PubMedDate not supplied

Evaluation of the pseudo-absorption method to quantify human stratum corneum removed by tape stripping using protein absorption.

Tape stripping is a well-known method to study the barrier function of the stratum corneum (SC) and penetration processes of topically applied substances into the horny layer. The quantification of the removed corneocytes for each tape strip is the prerequisite for these studies. The pseudo-absorption of the corneocytes was proposed as a measure for the quantification of the removed corneocyte aggregates. In this study, the pseudo-absorption of the corneocytes in the visible range (430 nm) is compared with the protein absorption in the UV range (278 nm) and an absorption at 652 nm obtained after staining of the SC proteins with Trypan blue. Both the protein absorption and the absorption measured after staining correlate well with the pseudo-absorption measured at 430 nm (R(2) = 0.92 +/- 0.04 and R(2) = 0.95 +/- 0.04, respectively).

Adult↗
PubMed2006

[Shock absorption of mouthguard materials--influence of temperature conditions and shore hardness on shock absorption].

PURPOSE: To consider changes in the physical properties of mouthguard materials with the change of temperature, shock-absorbing examination and Shore hardness measurement of existing MG materials and other elastic materials were carried out. METHODS: Both examinations were done under two temperature conditions: at room temperature (25 degrees C) and simulated intraoral temperature (37 degrees C). In addition, a comparative study of the relation between Shore hardness and shock absorption of the materials was made. A self-made drop impact machine was used for the shock-absorbing examination. The thickness of a sample was assumed to be 3 mm. The loading was applied by dropping 3 kinds of steel ball, phi 10 mm (4.0 g), phi 15 mm (13.7 g), and phi 20 mm (32.6 g) from a height of 60 cm. The shock absorption of all materials was compared by the maximum impact force. Shore hardness was measured based on the JIS standard. RESULTS: The shock absorption of each material showed a different tendency depending on the loading condition. Furthermore, the shock absorption of the same material showed different results depending on the temperature condition. Shore hardness measurements tended to show low values with the condition of 37 degrees C for all materials. CONCLUSION: From the relation between shock absorption and Shore hardness, it was confirmed that there is a correlation between hardness and the maximum impact force in the materials that showed shock absorption by elastic deformation. Some materials showed high shock absorption compared with existing MG materials.

Hardness↗
PubMed1976

On the absorption probabilities and absorption times of finite homogeneous birth-death processes.

This paper provides some formulas for the absorption probabilities, the mean absorption times and the variances of first absorption times in finite homogeneous absorbing birth-death processes. The results are then applied to a genetic model of Moran [1958] for computing the absorption probability densities, the mean absorption times and the variances of first absorption times. Specifically, it is shown that the probability distribution of the first absorption time is the matrix analog of exponential distribution or a mixture of exponential distributions if the transition matrix is diagonable.

Alleles↗
PubMed2005

[The study of CO2 cavity enhanced absorption and highly sensitive absorption spectroscopy].

Cavity enhanced absorption spectroscopy (CEAS) is a new spectral technology that is based on the cavity ring down absorption spectroscopy. In the present paper, a DFB encapsulation narrow line width tunable diode laser (TDL) was used as the light source. At the center output, the TDL radiation wavelength was 1.573 microm, and an optical cavity, which consisted of two high reflectivity mirrors (near 1.573 microm, the mirror reflectivity was about 0.994%), was used as a sample cell. A wavemeter was used to record the accurate frequency of the laser radiation. In the experiment, the method of scanning the optical cavity to change the cavity mode was used, when the laser frequency was coincident with one of the cavity mode; the laser radiation was coupled into the optical cavity and the detector could receive the light signals that escaped the optical cavity. As a result, the absorption spectrum of carbon dioxide weak absorption at low pressure was obtained with an absorption intensity of 1.816 x 10(-23) cm(-1) x (molecule x cm(-2)(-1) in a sample cell with a length of only 33.5 cm. An absorption sensitivity of about 3.62 x 10(-7) cm(-1) has been achieved. The experiment result indicated that the cavity enhanced absorption spectroscopy has the advantage of high sensivity, simple experimental setup, and easy operation.

English Abstract↗
PubMed1986

Gastric absorption of D-xylose in the rat: its influence on the D-xylose absorption test.

Relatively high incidences of false-positive results of D-xylose absorption tests have been reported. Delayed gastric emptying is invariably listed as one important cause for such tests. However, this conclusion assumes that gastric absorption from the relatively concentrated D-xylose solutions used clinically is negligible. In our study, D-xylose was injected (0.5 gm/kg) into either the stomach or duodenum of rats that had undergone pyloric ligation. Blood xylose levels 30 minutes later were almost as high after intragastric administration (0.61 +/- 0.22 mmol/L) as they were after intraduodenal injection (0.65 +/- 0.16 mmol/L). A chymotrypsin-labile peptide (N-benzoyl-L-tyrosyl-p-aminobenzoate), given at the same time, was poorly absorbed from the stomach, as shown by the low plasma p-aminobenzoic acid levels (14 +/- 2 mumol/L vs. 158 +/- 22 mumol/L after intraduodenal injection). Intragastric absorption of xylose, therefore, did not appear to result from the surgical trauma of pyloric ligation. In rats given doses orally of the D-xylose, the peptide, and a nonabsorbable marker (phenol red), epinephrine and atropine both showed gastric emptying without any surgical trauma, decreased digestion and absorption of the peptide as expected, but did not significantly decrease xylose absorption. These results indicate that, at least in rats, D-xylose is absorbed from relatively concentrated solutions within the stomach. Consequently, circumstances that delay gastric emptying should not markedly decrease xylose absorption. Bacterial overgrowth and altered blood flow seem more likely causes for false-positive D-xylose absorption test results.

4-Aminobenzoic Acid↗