Search Results - (Author, Cooperation:D. D. Miller)

2011-06-04

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

*Agriculture/economics/standards ; Conservation of Natural Resources ; *Developing Countries/economics ; Food Handling ; *Food Industry/economics/standards ; Food Safety ; *Food Supply/economics/standards ; Marketing ; Policy Making ; Private Sector

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

The effects of breakfast cereal composition, breakfast cereal processing, and breakfast meal composition on relative iron availability from breakfast meals were estimated using an in vitro method. Addition of wheat bran and germ to cereals and meals reduced iron availability. Presweetening caused a slight increase in iron availability. Comparisons among meals containing cereals that were similar except for type of processing showed that processing may affect iron availability. Addition of orange juice to breakfast meals caused a dramatic enhancement of iron availability. Ascorbic acid fortified apple and grape juice increased iron availability but the effect was small compared with the orange juice effect. Studies with purified organic acids showed that ascrobic and citric acids present in the juices caused the observed enhancement of iron availability. Citric acid was a more potent enhancer than ascorbic acid.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

An in vitro method was used to estimate relative availabilities of eight iron fortification sources under a variety of conditions. The eight iron sources examined were: ferrous sulfate, ferric orthophosphate, ferric sodium pyrophosphate, ferrous fumarate, reduced iron (hydrogen), reduced iron (carbonyl) and two sources of reduced iron (electrolytic). When incorporated into breads or complex meals, seven of the sources tested showed only slight differences in relative availability compared to the ferrous sulfate control. Ferric orthophosphate showed consistently lower relative availability. The baking process did not substantially alter the relative availabilities of nonheme iron in breads and meals containing the different iron fortification sources. Variation in meal composition had a greater influence on the availability of the nonheme iron in the meal than the form of fortification iron incorporated into the meal.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Zinc concentration was measured in four muscles from beef, pork, and lamb: longissimus dorsi (LD), biceps femoris (BF), gluteus medius (GM), and triceps brachi (TB). Within a species, BF, GM, and LD had similar zinc concentrations but TB was significantly (P〈0.01) higher in zinc. The means for the four muscles ranged from 39.8–53.5, 13.9–28.0, and 28.2–36.9 μg Zn/g wet weight for beef, pork, and lamb, respectively. The zinc concentration of muscle may relate to protein synthesis and the predominant type of energy metabolism occurring in the muscle. The mean zinc concentration of the four muscles between species was significantly (P〈 0.01) different.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

A method for determining the nonheme iron content of meats was evaluated and used to determine the nonheme and heme iron content of selected muscles from beef, pork, and lamb. The method allows a quantitative determination of nonheme iron in meat and is influenced to only a minor degree by the presence of heme iron. Heating meat in a boiling water bath increased the nonheme iron content of the meat. Possibly, heating accelerates oxidative cleavage of the prophyrin ring thereby allowing release of the iron from the heme complex. Total iron content differed between muscles in pork and beef but not in lamb. Heme iron, expressed as percent of the total iron, in raw pork, lamb, and beef average 49, 57, and 62%, respectively.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

: :Iron availability from FeSO4 in samples containing sodium caseinate (SC), casein phosphopeptides (CPP) or whey protein concentrate (WPC), and from ferric citrate (Fe-CA) in samples containing SC or CPP was measured using an in vitro digestion/Caco-2 cell culture model. In FeSO4 spiked samples, relative availability was CPP 〉 SC, CPP = WPC, and CPP = FeSO4 alone. In samples containing Fe-CA, a soluble iron chelate, relative availability was CPP = SC and CPP 〈 Fe-CA alone. These results suggest that CPP enhances iron availability from foods with low availability but does not improve and may inhibit availability from soluble iron species.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Treatment of ground beef samples with heat (conventional and microwave), ascorbic acid, or H2O2 increased nonheme iron concentrations. The increases ranged from less than 10% to more than 100% depending on the type, length, and severity of the treatment. Cooking of fresh beef round using common household methods (braising, roasting, microwave cooking) resulted in nonheme iron increases that were generally less than 10%. Treatment of hemin and meat extract solutions with heat and H2O2 resulted in destruction of the iron-porphyrin complex. Oxidative cleavage of the porphyrin ring followed by release of the iron is probably the mechanism for the observed increases in nonheme iron.

Electronic Resource

1572-8927

Zeta potential ; video enhanced microscopy ; didodecyldimethylammonium bromide and acetate ; ditetradecyldimethylammonium bromide and acetate

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Abstract The zeta potential of 2 mM solutions of didodecyldimethylammonium and ditetradecyldimethylammonium surfactants containing a mixture of acetate and bromide are reported. The measuremtns were made using new electrophoretic cells which can be used with a video enhanced microscope. This permits the simultaneous visualization and zeta potential characterization of vesicles and microtobule surfactant solutions. With increasing acetate molar fraction, the zeta potential increases. These results are interpreted in terms of the charge density at the shear plane of the aggregate interface.

Electronic Resource

1432-2137

Springer Online Journal Archives 1860-2000

Mathematics

Electronic Resource

1432-1912

Fluoro-catecholimidazolines ; Iodo-imidazolines ; Naphazolines ; Imidazoles ; SAR-quantification ; Adrenoceptors ; Rat aorta ; Human platelets

Springer Online Journal Archives 1860-2000

Medicine

Summary Potencies of new aromatic substituted fluoro or iodo analogues of catecholimidazolines on functional responses in rat aorta (α1) and platelets (α2) were quantified. (1) When compared either on the basis of EC50 or the dissociation constant (KA), 5-fluorocatecholimidazoline was as potent as the reference α1-adrenoceptor agonist, phenylephrine in the vascular tissue. The maximum contraction of aorta produced by the fluoro analogue was, however, 17% higher than that of phenylephrine. The time required for 1/2 relaxation of the tissue after 5-fluoro hydroxy imidazoline was at least twice as long as that of the phenylephrine. The catechol moiety as well as fluorine substitution at the critical 5-position of the aromatic ring is essential for higher α1 adrenoceptor-mediated potency. (2) As compared to the fluoro analogues, the adrenoceptor-mediated potencies of iodo-analogues were relatively weak on vascular tissue. Naphazoline and its analogues were partial agonists on vascular tissue with dissociation constants which ranged from 110 to 2600 nmol/l. (3) Imidazole analogues were generally less potent agonist than the imidazolines by one order of magnitude. (4) The vascular effects of all agonists were competitively blocked by prazosin with KB values which ranged from 0.04 to 0.48 nmol/l. Since the variation in KB values were within normal limits, the action of new imidazolines on rat aorta appears to be mediated mainly by the activation of the α1-adrenoceptor. Prazosin 10 nmol/l abolished the vascular response of some partial agonists. This indicates a slightly different mode of interaction of agonists with the transduction process. (5) Carbon 4-substituted imidazolines produced little or no α1 adrenoceptor-mediated intrinsic activity, but competitive receptor blocking potency was comparable to that of phentolamine. (6) Medetomidine was a partial agonist on the rat aorta with a KA of 260 nmol/l. When investigated as a blocker, the KB of medetomidine against phenylephrine was approximately 5600 nmol/l. The variation in the latter value was high. (7) In acetylsalicylic acid-treated human platelets, the α2-adrenoceptor-mediated aggregatory effect of all fluoro analogues was weak. lodo or naphazoline analogues did not initiate platelet aggregation but blocked the aggregation induced by epinephrine. The affinity of naphazoline for the α2-adrenoceptor was 1100 nmol/l. The IC50 of medetomidine for platelet anti-aggregatory effect was 3300 nmol/l, which compares favorably with other imidazoline type of blockes of platelet aggregation. (8) Sympathomimetic vasoconstrictor actions and platelet aggregation effects of these compounds can be dissociated. Some vasoconstrictors were antiaggregatory. The structure-activity relationships of the two receptor systems, namely rat aorta (α1) and platelets (α2), are discussed.

Electronic Resource

1432-1912

α-Adrenoceptors ; Stereoisomeric-imidazolines ; Affinity constants ; Molecular receptor-mapping

Springer Online Journal Archives 1860-2000

Medicine

Summary Adrenoceptor-mediated effects of the enantiomers of hydroxytolazoline and tolazoline (i. e., desoxy derivative) have been investigated in vitro. The enantiomers and tolazoline were partial agonists of postjunctional α1-adrenoceptors in rat aorta. The rank order of potencies of the compounds in this system was as follows: tolazoline 〉 R(−)-hydroxytolazoline 〉 S(+)-hydroxytolazoline. The efficacy of R(−)-hydroxytolazoline was higher than that of tolazoline, though its affinity for the receptor was less. The K B values for prazosin against these agonists were nearly equal, which indicated that these imidazolines activate the same type of receptor in rat aorta. The S(+)-isomer, however, produced both a prazosin sensitive and resistant component of the response. The interactions of the derivatives with presynaptic α2-adrenoceptors were studied in field-stimulated myenteric plexus-longitudinal muscle of guinea-pig ileum. These substances were blockers at presynaptic α2-adrenoceptors. Based on K B values, the order of affinity in this system was as follows: tolazoline 〉 S(+)isomer ≥ R(−)-isomer. β-Adrenoceptor mediated activity was quantitated in guinea-pig and rat atria. R(−)-hydroxytolazoline lacked chronotropic effects either in guinea pig or rat atria. At 3 × 10−4 M the isomer did not antagonize the effect of isoproterenol in the atria. On the other hand, S(+)-hydroxytolazoline produced a variable chronotropic effect in guinea-pig atria, but failled to show any significant activity in rat atria. Thus, the β-adrenoceptor mediated action appears to be insignificant. Steric aspects of α-adrenoceptor mediated events are discussed.

Electronic Resource

1615-6102

Actin ; Immunogold ; Microfilaments ; Microinjection ; Pollen tube

Springer Online Journal Archives 1860-2000

Biology

Summary Controversy over whether the apical region of a growing pollen tube contains a dense array of actin microfilaments (MFs) was the impetus for the present study. Microinjection of small amounts of fluorescently labeled phalloidin allowed the observation of MF bundles inLilium longiflorum pollen tubes that were growing and functioning normally. The results show that while the pollen tube contains numerous MF bundles arranged axially, the apical region is essentially devoid of them. The MF bundles could be seen shifting and changing in distribution as the cells grew, but they always remained out of the apical regions. Perturbation of normal growth and function by caffeine causes a change in the MF distribution, which returns to normal upon removal of caffeine from the growth medium. The lack of MFs in the apex is confirmed by careful immunogold electron microscopic analysis of thin sections of rapidly frozen and freeze-substituted pollen tubes, in which very fine MF bundles could be seen somewhat closer to the tip than is discernible with fluorescence microscopy. Still, these are very few in number and are basically absent from the very tip. Thus a reassessment of current assumptions about the distribution of actin in the pollen tube apical region is required.

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