Class 2 resistant starches lower plasma and liver lipids and improve mineral retention in rats.
(65/1799)
The effects of raw potato starch (RPS) and high amylose corn starch (HAS) on cecal digestion, lipid metabolism and mineral utilization (Ca and Mg) were compared in rats adapted to semipurified diets. The diets provided either 710 g wheat starch/100 g diet (control) alone or 510 g wheat starch/100 g diet plus 200 g resistant starch/100 g (RPS or HAS). Compared with rats fed the control diet, significant cecal hypertrophy (240% after 7 d of the fiber consumption) and short-chain fatty acids accumulation (especially propionic and butyric acids) occurred after both resistant starch diets. Apparent Ca, Mg, Zn, Fe and Cu absorptions were similarly enhanced by RPS and HAS (50, 50, 27, 21 and 90%, respectively). Cholesterol absorption was reduced to 14% of intake in rats fed RPS or HAS compared with 47% absorption in control rats. RPS and HAS were also effective in lowering plasma cholesterol (-31 and -27%, respectively) and triglycerides (-28 and -22%, respectively). There was no effect of the diets on cholesterol in d > 1.040 kg/L lipoproteins (HDL), whereas RPS and HAS depressed cholesterol in d < 1.040 kg/L lipoproteins (especially in triglyceride-rich lipoproteins). Moreover, there were lower concentrations of cholesterol (-50 and -40%, respectively) and triglycerides (-53 and -47%, respectively) in the livers of RPS- and HAS-fed rats. Thus, RPS and HAS have similar effects on intestinal fermentation, mineral utilization and cholesterol metabolism in rats. (+info)
Bioavailability of nutrients: a practical approach to in vitro demonstration of the availability of nutrients in multivitamin-mineral combination products.
(66/1799)
As the dietary supplements industry is registering steady and rapid growth, consumers are demanding quality supplements. Consumer perception of the quality of oral solid dosage forms is changing. Good quality is associated with the ability to disintegrate and dissolve. Performance characteristics of oral solid dosage forms in public standards will address the in vitro dissolution requirements, which will be presented as they relate to multivitamin-mineral combination products. (+info)
Comparative pulmonary toxicity of 6 abrasive blasting agents.
(67/1799)
Inhalation of silica dust is associated with pulmonary fibrosis. Therefore, substitute abrasive materials have been suggested for use in abrasive blasting operations. To date, toxicological evaluation of most substitute abrasives has been incomplete. Therefore, the objective of this study was to compare the pulmonary toxicity of a set of substitute abrasives (garnet, staurolite, coal slag, specular hematite, and treated sand) to that of blasting sand. Rats were exposed to blasting sand or an abrasive substitute by intratracheal instillation and pulmonary responses to exposure were monitored 4 weeks postexposure. Pulmonary damage was monitored as lactate dehydrogenase (LDH) in the acellular lavage fluid. Pulmonary inflammation was evaluated from the yield of polymorphonuclear leukocytes (PMN) obtained by bronchoalveolar lavage. The activity of alveolar macrophages was determined by measuring zymosan-stimulated chemiluminescence. Blasting sand caused lung damage and showed histologic evidence for inflammation and fibrosis. Garnet, staurolite, and treated sand exhibited toxicity and inflammation that were similar to blasting sand, while coal slag caused greater pulmonary damage and inflammation than blasting sand. In contrast, specular hematite did not significantly elevate LDH or PMN levels and did not stimulate macrophage activity 4 weeks postexposure. (+info)
Effect on fecal output of various dietary nitrogen sources in pig-tailed monkeys (Macaca nemestrina) fed fiber-free, semisynthetic diets.
(68/1799)
Fiber-free liquid diets containing isonitrogenous amounts of various dietary nitrogen sources were fed to five adult male pig-tailed monkeys (Macaca nemestrina) with a mean weight of approximately 10 kg. All liquid diets supplied 3.0 g N/DAY PER MONKEY AND MAINTAINED THE ANIMALS IN A POSTIVE NITROGEN BALANCE. Initial baseline fecal output data were obtained by feeding the animals a commercial solid monkey chow. The dietary nitrogen sources fed were a) egg white protein, b) an enzymatic hydrolysate of fish protein supplemented with L-amino acids to simulate the egg albumin pattern, c) a mixture of pure L-amino acids simulating the egg pattern, d) a casein hydrolysate supplemented with amino acids, and e) an amino acid mixture with Rose's pattern. Total fecal matter, dry fecal matter, percent of moisture, fecal nitrogen, lipids and ash were determined for a 10-day period for each experimental diet. A very significant difference (P smaller than 0.001) was noted between each liquid diet and the solid chow, but no significant differences were found between the various fiber-free liquid diets, pointing to the effect of fiber as a major factor affecting fecal output. Monkeys fed liquid diets excreted fecal matter with a mean of 12.9 g/day, of which 4.7 g/day was dry feces (fecal dry matter 28.5%). Fecal nitrogen was found to be 0.25 g, fecal lipids were 0.19 g, and fecal ash was 0.59 g/day per monkey, respectively. (+info)
Effects of supplement type on animal performance, forage intake, digestion, and ruminal measurements of growing beef cattle.
(69/1799)
Two experiments were conducted to determine the effects of supplement type on the rate of gain by heifers grazing bermudagrass and on the intake, apparent total-tract OM digestibility, ruminal fermentation, digesta kinetics, in situ DM digestibility, and forage protein degradation by steers fed prairie hay. In Exp. 1, 45 heifers (284+/-24 kg) grazed a bermudagrass pasture for 91 d in the late summer to determine the effects of no supplement (CON), or one of four individually fed monensin-containing (150 mg/[heifer x d]) supplements (MINCS; 0.1 kg of mineral mix with 0.2 kg [DM] of cottonseed hulls as a carrier/[heifer x d]), a pelleted protein supplement (PROT; 1 kg of DM, 242 g of degradable intake protein [DIP]/[heifer x d]), or high-fiber (HF) and high-grain (HG) (2 kg of DM, 243 and 257 g of DIP, respectively/[heifer x d]) pelleted energy supplements. In Exp. 2, four ruminally cannulated steers (311+/-22 kg) with ad libitum access to low-quality (4% DIP, 73% NDF, 40% ADF) prairie hay were individually fed monensin-containing (200 mg/[steer x d]) treatments consisting of 1) mineral mix + corn (MINCR; 0.1 kg of mineral and 0.4 kg of cracked corn [DM] as a carrier, 19 g of DIP/[steer x d]), 2) PROT (1.4 kg of DM, 335 g of DIP/[steer x d]), 3) HF, or 4) HG (2.9 kg of DM, 340 and 360 g of DIP, respectively/[steer x d]) in a 4 x 4 Latin square with 14-d adaptation and 6-d sampling periods. In Exp. 1, the HF-, HG-, and PROT-supplemented heifers had greater (P < 0.01) rates of gain than CON heifers, and the HF- and HG-supplemented heifers tended (P < 0.11) to gain more weight than those fed PROT. In Exp. 2, steers fed PROT consumed more (P < 0.05) hay OM than HF and HG, or MINCR. Total OM intake was greater (P < 0.01) by supplemented steers than MINCR-fed cattle. Hay OM digestibility was not affected (P = 0.19) by treatment, but total diet OM digestibility was greater (P < 0.01) for HF- and HG- than for MINCR- or PROT-fed steers. The rate of in situ DM digestibility was greater (P < 0.01) for HF, HG, and PROT than for MINCR. Results from these studies indicate that feeding milo- vs fiber-based energy supplements formulated to provide adequate DIP did not result in different forage intake, OM digestibility, or in situ DM digestibility, whereas both increased ADG in heifers consuming low-quality forages compared with unsupplemented or mineral- or protein-supplemented cattle. An adequate DIP:TDN balance decreased the negative associative effects often observed when large quantities of high-starch supplements are fed with low-quality hay. (+info)
Electrical stimulation influences mineral formation of osteoblast-like cells in vitro.
(70/1799)
The aim of the present study was to assess the structure of newly formed mineral crystals after electrical stimulation of osteoblast-like cells in vitro. Pulsed electrical stimulation was coupled capacitively or semi-capacitively to primary osteoblast-like cells derived from bovine metacarpals. Computer calculations revealed that the chosen input signal (saw-tooth, 100 V, 63 ms width, 16 Hz repetition rate) generated a short pulsed voltage drop of 100 microV (capacitive coupled mode) and of 350 microV (semi-capacitive coupled mode) across the cell-matrix layer. Stimulated cultures showed an enhanced mineral formation compared to the non stimulated controls. In cultures exposed to capacitively coupled electric fields and in control cultures nodules and mineralized globules were found. Nodules with a diameter of less than 200 nm covered the cell surface, whereas mineral globules with a diameter of up to 700 nm formed characteristic mineral deposits in the vicinity of the cells similar to biomineral formations occurring in mineralizing tissues. In contrast, large rod-shaped crystals were found in cultures stimulated by semi-capacitive coupled electric fields, indicating a non-physiological precipitation process. In conclusion, osteoblasts in culture are sensitive to electrical stimulation resulting in an enhancement of the biomineralization process. (+info)
Renal regulation of acid-base equilibrium during chronic administration of mineral acid.
(71/1799)
Previous studies in metabolic alkalosis have demonstrated that two factors are the prime determinants of acid excretion and bicarbonate reabsorption; first, the diversion to distal exchange sites of sodium previously reabsorbed in the proximal tubule and loop of Henle; and, second, a stimulus to sodium-cation exchange greater than that produced by a low-salt diet alone. In the present study we have examined the hypothesis that these two factors are also the prime determinants of acid excretion during the administration of mineral acid loads. To test this hypothesis, we have administered to dogs ingesting a low NaCl diet a daily dose of 7 meq/kg of H+ with anions (chloride, sulfate, or nitrate) whose differing degrees of reabsorbability influence the speed and completeness with which each is delivered to the distal nephron with its accompanying Na+. After 2-3 wk of acid administration, and after an initial urinary loss of Na+ and K+, the steady-state value for plasma [HCO3-] was 8.6 meq/liter below control in the HCl group, 3.7 meq/liter below control in the H2SO4 group, and unchanged from control in the HNO3 group; all of these values were significantly different from each other. We would propose the following explanation for our findings: when HCl is administered chronically, marked acidosis occurs because distal delivery of Cl- is restricted by the ease with which the Cl- can be reabsorbed in the proximal portions of the nephron. Only when Cl- retention produces sufficient hyperchloremia to insure delivery of Na+ (previously reabsorbed in proximal tubule and loop of Henle) to the distal nephron in quantities equal to ingested Cl is this primary constraint removed. In the case of sulfuric and nitric acids, there is no constraint on distal delivery, the nonreabsorbability of the administered anion causing prompt, total delivery of Na+ to exchange sites in quantities equal to administered hydrogen. Thus, with H2SO4 and HNO3 the sole constraint on removal of the acid load is the inability of the distal exchange mechanism to conserve the Na+ increment fully by means of H+ exchange. Escape of Na+ and K+ into the urine and the resulting stimulus to Na(+)-H+ exchange remove this constraint and are responsible for establishment of a new steady-state of acid-base equilibrium at plasma [HCO3-] levels significantly higher than those seen with HCl. The feeding of HCl in the presence of a normal salt intake led to a degree of metabolic acidosis not significantly different from that seen in dogs ingesting a low-salt diet. We suggest that the presence of dietary sodium at distal exchange sites did not enhance acid excretion because it is only after a loss of body sodium stores that sodium avidity is increased sufficiently to allow full removal of the acid load. The present findings indicate that the fundamental factors controlling acid excretion and bicarbonate reabsorption in metabolic acidosis are closely similar to those operative in metabolic alkalosis. (+info)
Bacterial recognition of mineral surfaces: nanoscale interactions between Shewanella and alpha-FeOOH.
(72/1799)
Force microscopy has been used to quantitatively measure the infinitesimal forces that characterize interactions between Shewanella oneidensis (a dissimilatory metal-reducing bacterium) and goethite (alpha-FeOOH), both commonly found in Earth near-surface environments. Force measurements with subnanonewton resolution were made in real time with living cells under aerobic and anaerobic solutions as a function of the distance, in nanometers, between a cell and the mineral surface. Energy values [in attojoules (10(-18) joules)] derived from these measurements show that the affinity between S. oneidensis and goethite rapidly increases by two to five times under anaerobic conditions in which electron transfer from bacterium to mineral is expected. Specific signatures in the force curves suggest that a 150-kilodalton putative iron reductase is mobilized within the outer membrane of S. oneidensis and specifically interacts with the goethite surface to facilitate the electron transfer process. (+info)