Showing papers on "Ascorbic acid published in 1988"

Bone formation in vitro by stromal cells obtained from bone marrow of young adult rats.

Abstract: Cells from fetal or neonatal skeleton can synthesize bone-like tissue in vitro In contrast, formation of bone-like tissue in vitro by cells derived from adult animals has rarely been reported and has not been achieved using cells from bone marrow We have explored development of bone-like tissue in vitro by bone marrow stromal cells Marrow stromal cells obtained from 40-43-day-old Wistar rats were grown in primary culture for 7 days and then subcultured for 20-30 days Cells were cultured in either alpha-minimal essential medium containing 15% fetal bovine serum, antibiotics, and 50 micrograms/ml ascorbic acid, or the above medium supplemented with either 10 mM Na-beta-glycerophosphate, 10(-8) M dexamethasone, or a combination of both Cultures were examined using phase-contrast microscopy, undemineralized and demineralized tissue histology, histochemistry (for alkaline phosphatase activity), immunohistochemistry (for collagen type, osteonectin, and bone Gla-protein), scanning and transmission electron microscopy, energy dispersive X-ray microanalysis, and X-ray diffraction Collagenous, mineralized nodules exhibiting morphological and ultrastructural characteristics similar to bone were formed in the cultures, but only in the presence of both beta-glycerophosphate and dexamethasone Cells associated with the nodules exhibited alkaline phosphatase activity The matrix of the nodules was composed predominantly of type-I collagen and both osteonectin and Gla-protein were present X-ray microanalysis showed the presence of Ca and P, and X-ray diffraction indicated the mineral to be hydroxyapatite The nodules were also examined for bone morphogenetic protein-like activity Paired diffusion chambers containing partly demineralized nodules and fetal muscle were implanted intraperitonealy in rats Induction of cartilage in relation to muscle was observed histologically after 40 days in the chambers This finding provided further support for the bone-like nature of the nodules The observations show that bone-like tissue can be synthesized in vitro by cells cultured from young-adult bone marrow, provided that the medium contains both beta-glycerophosphate and, particularly, dexamethasone

The use of a self-administered questionnaire to assess diet four years in the past

Abstract: The use of a mailed, self-administered, semiquantitative food frequency questionnaire to describe past dietary intake was evaluated in 1984 among a group of 150 Boston-area women who had completed four one-week diet records three to four years previously. Correlation coefficients comparing calorie-adjusted nutrient intakes computed from the questionnaire with those obtained from a compressed version of the questionnaire completed during diet record keeping ranged from 0.44 for total carbohydrate to 0.62 for vitamin C including supplements. Coefficients comparing calorie-adjusted nutrient intakes measured by questionnaire with those assessed by the diet records completed three to four years previously ranged from 0.28 for iron without supplements to 0.61 for total carbohydrate. An evaluation of the incremental contribution provided by several open-ended sections of the questionnaire to the estimation of nutrient intake suggested that in this population most of these items might be eliminated without material loss of information. These findings demonstrate that useful estimates of nutrient intake several years previously can be obtained by a relatively inexpensive, mailed, self-administered questionnaire.

Antioxidant activity of carnosine, homocarnosine, and anserine present in muscle and brain.

Abstract: Carnosine, homocarnosine, and anserine are present in high concentrations in the muscle and brain of many animals and humans. However, their exact function is not clear. The antioxidant activity of these compounds has been examined by testing their peroxyl radical-trapping ability at physiological concentrations. Carnosine, homocarnosine, anserine, and other histidine derivatives all showed antioxidant activity. All of these compounds showing peroxyl radical-trapping activity were also electrochemically active as reducing agents in cyclic voltammetric measurements. Furthermore, carnosine inhibited the oxidative hydroxylation of deoxyguanosine induced by ascorbic acid and copper ions. Other roles of carnosine, such as chelation of metal ions, quenching of singlet oxygen, and binding of hydroperoxides, are also discussed. The data suggest a role for these histidine-related compounds as endogenous antioxidants in brain and muscle.

The protection by ascorbate and glutathione against microsomal lipid peroxidation is dependent on vitamin E

Abstract: Lipid peroxidation of rat liver microsomal fractions was monitored by its low-level chemilunminescence in preparations from controls and vitamin-E-deficient animals. Measurements were made (a) of the duration of the lag phase τ0 after initiation with NADPH/iron-ADP and (b) of the slope of the chemiluminescence increase. In microsomes with normal vitamin E (α-tocopherol) level the lag phase τ0 was substantially increased by ascorbate; in contrast, even an enhanced peroxidation was observed with ascorbate in vitamin-E-deficient microsomes. Therefore, the ascorbate-mediated protection of microsomal membranes against lipid peroxidation is dependent on vitamin E in the membrane. In vitamin E deficiency the pro-oxidant effect of ascorbate was abolished when glutathione (GSH) was present. Likewise, GSH does not prolong the lag phase τ0 in vitamin E deficiency. However, GSH (but not cysteine) exerts an antioxidant effect both in controls and in vitamin E deficiency by decreasing the slope of the chemiluminescence increase during lipid peroxidation. The involvement of GSH in an enzyme-dependent mechanism is suggested.

Dietary Factors in Oral and Pharyngeal Cancer

Abstract: A population-based case-control study of oral and pharyngeal cancer conducted in four areas of the United States provided information on a number of risk factors, including diet. Interviews were obtained from 871 oral cancer patients and 979 controls among whites, frequency matched for age and sex. Consumption frequency of 61 food items was assessed in the questionnaire; attention was given to foods that are sources of vitamins A and C and carotene. The major finding was an inverse relationship between fruit intake and risk of oral and pharyngeal cancer; individuals in the highest quartile of intake had about half the risk of those in the lowest quartile. Vitamin C, carotene, or fiber in fruit did not appear to account completely for this relationship, since these nutrients in vegetables did not provide similar protection. This finding suggests the influence of other constituents in fruits, although it is possible that cooking vegetables may have a nutrient-diminishing effect. Dietary intake of other nutrients, such as the B vitamins, vitamin E, folate, and iron, showed no consistent relationship to risk of oral and pharyngeal cancer. Coffee or other hot beverage consumption did not increase risk; intake of nitrite-containing meats or cooking practices, such as smoking, pickling, or charcoal grilling, also did not increase risk. All analyses were adjusted for the effects of tobacco and alcohol, strong risk factors for oral and pharyngeal cancer. Dietary findings among the few subjects who did not use tobacco or alcohol were similar to those for all subjects.

Physiological Disturbances in Fish Living in Coastal Water Polluted with Bleached Kraft Pulp Mill Effluents

Abstract: An extensive trial to examine physiological and biochemical changes in perch (Perca fluviatilis) inhabiting coastal waters polluted by bleached kraft mill effluents (BKME) has been carried out. The investigations were performed at four different times of year. Fish from a reference site and from sampling sites 2, 4.5, 8, and 10 km from the discharge point were examined. The results of the investigation show profound effects of BKME on several fundamental biochemical and physiological functions. Typical symptoms in perch from the polluted areas were reduced gonad growth, enlarged liver, and very strong induction of certain cytochrome P-450-dependent enzyme activities in the liver. Elevated levels of ascorbic acid in liver tissue and abnormal carbohydrate metabolism reflect the effluent's ability to cause metabolic disorders. Marked effects on the white blood cell pattern indicate a suppressed immune defence. Alterations in the red blood cell status and in the ion balance suggest that the demand for oxygen ...

Inhibitors of endogenous nitrosation. Mechanisms and implications in human cancer prevention.

Abstract: Although the proof that N-nitroso compounds (NOC), a versatile class of carcinogens in animals, are also carcinogenic in man is lacking, humans are exposed through ingestion or inhalation to preformed NOC in the environment and through the endogenous nitrosation of amino precursors in the body. Activated macrophages can synthesize nitrate, nitrite and nitrosating agents that can form NOC. A number of bacterial strains isolated from human infections can produce NOC enzymatically from precursors at neutral pH. As a consequence endogenous nitrosation may occur at various sites of the body such as the oral cavity, stomach, urinary bladder, lungs, and at other sites of infection or inflammation. Since the demonstration by Mirvish et al. (1972) showing that ascorbate can reduce tumor formation in animals following feeding of nitrite plus amine, numerous substances to which humans are exposed have been identified and shown to inhibit formation of NOC in vitro, in animal models and in humans. Such inhibitors of nitrosation include vitamins C and E, phenolic compounds, and complex mixtures such as fruit and vegetable juices or other plant extracts. Nitrosation inhibitors normally destroy the nitrosating agents and thus act as competitors for the amino compound that serves as substrate for the nitrosating species. Independently, epidemiological studies have already established that fresh fruits and vegetables that are sources of vitamin C, other vitamins and polyphenols have a protective effect against cancers at various sites and in particular gastric cancer. Although the evidence that endogenously formed NOC are involved in human cancers is far from conclusive, it is suggestive and justifies preventive measures for reducing exposure to NOC. This article briefly reviews (i) the chemistry of NOC formation and inhibition, (ii) the studies in experimental animals which showed that inhibition of endogenous NOC synthesis leads to a reduction of toxic, mutagenic and carcinogenic effects, (iii) recent studies in humans where the degree of inhibition of endogenous NOC synthesis was directly quantified and lastly (iv) the contribution of nitrosation inhibitors to human cancer prevention.

Iron nutrition and absorption: dietary factors which impact iron bioavailability.

Abstract: Iron deficiency is widely observed worldwide, yet, paradoxically, iron is the most plentiful heavy metal in the earth's crust. Although absorption of iron from the gastrointestinal tract is strictly controlled, excretion is limited to iron lost from exfoliation of skin and gastrointestinal cells, customary and abnormal blood loss, and menses. Individuals highly vulnerable to iron deficiency have high iron needs, as during growth or pregnancy; high iron loss, as during marked hemorrhage or excessive and/or frequent menstrual losses; or diets with low iron content or bioavailability. Food iron is classified as heme or nonheme. Approximately half of the iron in meat, fish, and poultry is heme iron. Depending on an individual's iron stores, 15% to 35% of heme iron is absorbed. Food contains more nonheme iron and, thus, it makes the larger contribution to the body's iron pool despite its lower absorption rate of 2% to 20%. Absorption of nonheme iron is markedly influenced by the levels of iron stores and by concomitantly consumed dietary components. Enhancing factors, such as ascorbic acid and meat/fish/poultry, may increase nonheme iron bioavailability fourfold.

Diet and prostatic cancer: a case-control study in Hawaii

Abstract: A total of 452 cases of prostatic cancer identified through the population-based Hawaii Tumor Registry during the period 1977-1983 and 899 age-matched population controls were interviewed on the island of Oahu from 1981 to 1983. All interviews of the subjects, who comprised five different ethnic groups, were conducted in the home by use of a quantitative dietary history method. Usual weekly intake of fat, zinc, and vitamins A and C, including supplements, was determined for each subject. Among men 70 years or older, but not among younger men, and mean weekly consumption of saturated fat, carotenes, and zinc, adjusted for age and ethnicity, was greater for cases than for controls. In a multiple logistic regression analysis, the odds ratio for the highest quartile of fat intake among the older men was 1.7 (95% confidence interval (CI) 1.0-2.8). The corresponding odds ratios were 1.6 (95% CI 1.0-2.5) for carotenes, 1.4 (95% CI 0.9-2.3) for total vitamin C, and 1.7 (95% CI 1.1-2.7) for total zinc. There were significant linear trends in the odds ratios for saturated fat and zinc, but no synergistic interactions among the nutrients. The findings suggest that several different components of the diet may contribute independently to the risk of prostatic cancer in elderly men.

Terminal differentiation and calcification in rabbit chondrocyte cultures grown in centrifuge tubes: regulation by transforming growth factor beta and serum factors.

Abstract: Rabbit chondrocyte cultures on plastic dishes are capable of depositing a cartilaginous matrix, although the matrix does not calcify unless high levels of phosphate are added to the medium. In the present study, we cultivated a pelleted mass of rabbit growth-plate chondrocytes in the presence of Eagle's minimum essential medium supplemented with 10% fetal bovine serum and 50 micrograms of ascorbic acid per ml in a plastic centrifuge tube. These cells proliferated for several generations and then reorganized into a cartilage-like tissue that calcified without additional phosphate. The deposition of minerals was observed only after synthesis of a short-chain collagen and alkaline phosphatase. Serum factors were required for the increases in alkaline phosphatase and calcium contents. 5-Bromo-2'-deoxyuridine abolished the increases in uronic acid, alkaline phosphatase, and calcium contents. Transforming growth factor beta, at very low concentrations, suppressed the expression of the mineralization-related phenotype by chondrocytes. These results suggest that cartilage-matrix calcification can be controlled by growth factor(s) and that chondrocytes induce the mineralization of extracellular matrix when terminal differentiation is permitted in the absence of an artificial substrate.

Studies on scavengers of active oxygen species. 1. Synthesis and biological activity of 2-O-alkylascorbic acids

Abstract: A novel series of 2-O-alkylascorbic acids (5a-u) was synthesized, and their scavenging activities against active oxygen species as well as their suppressive effects on the arrhythmias in rat heart ischemia-reperfusion models were evaluated. Some 2-O-alkylascorbic acids (5e-1) exhibited potent inhibiting activities against lipid peroxidation in rat brain homogenates and in alleviating effects in the ischemia-reperfusion models. Studies on the structure-activity relationship demonstrated that a free 3-enolic hydroxyl group and the longer alkyl chains substituted on the 2-hydroxyl group of ascorbic acid were beneficial for the biological and pharmacological activities. 2-O-Octadecylascorbic acid (5k, CV-3611), one of the most potent and promising compounds, markedly inhibited lipid peroxidation (IC50 = 4.3 X 10(-6) M) and alleviated myocardial lesions induced by ischemia-reperfusion at an oral dose of 1 mg/kg in rats.

Effects of storage and handling conditions on concentrations of individual carotenoids, retinol, and tocopherol in plasma.

Abstract: We investigated the effects of storage and handling on measured values for carotenoids, retinol, and tocopherol in plasma. We found no significant differences in the concentrations of these analytes measured in plasma samples that were frozen immediately after separation as compared with replicate samples maintained at room temperature in the dark for 24 h. Analytes were stable in solvents for at least 18 h at 23 degrees C after extraction. Purging samples with nitrogen gas before freezing had no detectable beneficial effects. All analytes were stable in plasma stored at -70 degrees C for at least 28 months or at -20 degrees C for five months. By 15 months the concentrations of carotenoids were significantly less (P less than 0.05) in plasma stored at -20 degrees C than in plasma stored at -70 degrees C, while retinol and tocopherol concentrations were not significantly different. Concomitant with the decrease in carotenoids was the appearance of unidentified peaks in the ultraviolet. Adding ascorbic acid or butylated hydroxytoluene antioxidants to the precipitating solvent did not alter the losses of carotenoids or alter the appearance of unidentified peaks. Under appropriate conditions, plasma carotenoids, retinol, and tocopherol are stable for more than two years.

Nutritive Value of Foods

Abstract: Gebhardt, Sjusan E., and Robin G. Thomas. 2002. Nutritive Value of Foods. U.S. Department of Agriculture, Agricultural Research Service, Home and Garden Bulletin 72 This pubUcation gives in tabular form the nutritive values for household measures of commonly used foods. It was first published in 1960; the last revision was pubhshed in 1991. In this revision, values for total dietary fiber have been added and phosphorus values have been removed. Values are reported for water; calories; protein; total fat; saturated, monounsaturated, and polyunsaturated fatty acids; cholesterol; carbohydrate; total dietary fiber; calcium; iron; potassium; sodium; vitamin A in lU and RE units; thiamin; riboflavin; niacin; and ascorbic acid (vitamin C). Data are from the U.S. Department of Agriculture Nutrient Database for Standard Reference, Release 13. Mention of trade names, commercial products, or companies in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture over others not mentioned.

Effect of sunlight on redox cycles of manganese in the southwestern Sargasso Sea

Abstract: The cycling of manganese between soluble Mn(II) and particulate manganese oxides was investigated in the upper 750 m at a station in the southwestern Sargasso Sea. Dissolved manganese was present at a maximum concentration (4.3 ± 0.6 nM) in the surface mixed layer (0–40 m) and decreased to 0.67 ± 0.19 nM at depths of 400–750 m. Particulate manganese, on the other hand, occurred at a minimum concentration (0.034 ± 0.012 nM) in the mixed layer and increased to a maximum of 0.41–0.48 nM at depths of 120–250 m. All of the increase in particulate manganese with depth occurred within the fraction that could be reductively dissolved by 0.3 mM ascorbic acid at ambient seawater pH, indicating that the rise resulted from an increase in the concentration of manganese oxides. Oxides were undetectable in the mixed layer, but a mean of 94% of the particulate manganese appeared to be associated with oxides at depths of 80–250 m. Radiotracer (54MnCl2) measurements of particulate formation rates and concomitant steady-state calculations of particulate turnover rates indicate that the low near-surface concentrations of particulate manganese resulted from both low formation rates and high turnover rates of particulate manganese. The formation of particulate manganese was sharply inhibited by sunlight, consistent with photoinhibition of manganese oxidizing microorganisms. Likewise, sunlight caused a 12-fold increase in the dissolution rate of 54Mn-labeled particulate manganese, which we attribute to photoreduction of manganese oxides. Both photo-effects appear to be important in sharply reducing the concentration of particulate manganese in near-surface seawater, and thereby minimizing the removal of manganese via particulate sinking. The resulting reduction in removal rates should be a major factor contributing to the surface maximum in manganese concentrations, which is a prominent feature of manganese profiles in much of the worlds ocean.

A Randomized Trial of Vitamins C and E in the Prevention of Recurrence of Colorectal Polyps

Abstract: Because supplements of vitamins C and E had been associated with reduction of fecal mutagen levels, a double-blind randomized trial was designed to examine the effects of these vitamins on the rate of recurrence of colorectal polyps, presumed precursors for colorectal cancer. Two hundred patients believed to be free of polyps after removal of at least one colorectal polyp were randomized to receive a supplement of 400 mg each of ascorbic acid and alpha-tocopherol, or a placebo. Fifteen patients had to be excluded because a review of pathology indicated that their polyps were not adenomatous. A second colonoscopic examination was planned after 2 yr of supplementation. One hundred thirty-seven people (75% of eligible subjects) completed the study; polyps were observed in the second colonoscopy in 41.4% of 70 subjects on vitamin supplements and in 50.7% of 67 subjects on placebos. After adjustment for differences between groups in demographic and dietary factors before study entry, the relative risk of polyp occurrence was 0.86, with 95% confidence limits from 0.51 to 1.45, in an analysis of 129 subjects with complete information on demographic and dietary factors who had completed the trial. Of the 48 patients who had not completed the study, 7 had died, 33 had not returned to their physician for an examination, and 8 had had a follow-up colonoscopy or sigmoidoscopy. Inclusion of the three polyps found in these eight examinations led to an estimate of relative risk of 0.86 (95% confidence limits, 0.51 to 1.43). The findings of this investigation suggest that any reduction in the rate of polyp recurrence associated with vitamin supplementation is small, and a larger study would be required to ensure that an effect of this size was not a chance finding.

Vitamin E analogue Trolox C. E.s.r. and pulse-radiolysis studies of free-radical reactions.

Abstract: The reactions between Trolox C, a water-soluble vitamin E analogue, and several oxidizing free radicals including the hydroxyl radical and various peroxy radicals were examined by using the pulse-radiolysis technique. The results demonstrate that Trolox C may undergo rapid one-electron-transfer reactions as well as hydrogen-transfer processes; the resulting phenoxyl radical is shown to be relatively stable, in common with the phenoxyl radical derived from vitamin E. The reactions between the Trolox C phenoxyl radical and a variety of biologically relevant reducing compounds were examined by using both pulse radiolysis and e.s.r. The results demonstrate that the Trolox C phenoxyl radical is readily repaired by ascorbate (k = 8.3 x 10(6) dm3.mol-1.s-1) and certain thiols (k less than 10(5) dm3.mol-1.s-1) but not by urate, NADH or propyl gallate. Evidence from e.s.r. studies indicates that thiol-containing compounds may also enter into similar repair reactions with the alpha-tocopherol phenoxyl radical. Kinetic evidence is presented that suggests that Trolox C may 'repair' proteins that have been oxidized by free radicals.

Vitamin supplement use, by demographic characteristics

Abstract: Detailed data on vitamin supplement use are presented for nine specific vitamins and minerals by a wide range of demographic and behavioral characteristics. Previously recorded but uncoded data from the first National Health and Nutrition Examination Survey (1971-1974) have been coded and analyzed, providing the only detailed vitamin use data in a representative sample large enough to examine joint distributions and multivariate analyses of numerous characteristics. Significantly fewer black persons than white persons consume vitamins regularly, and the difference is especially pronounced for specific vitamins: fourfold for vitamin E, sixfold for vitamin A, and 10-fold for vitamin C. Significant differences were also seen for age, sex, geographic region, education, poverty, type of alcoholic beverage consumed, and Quetelet index. Data are presented indicating that supplement use has not increased notably between the time of the survey and 1983, and thus the supplement use data are considered to be reasonably representative of current patterns of supplementation practice in the United States.

Skin-beautifying cosmetic

Abstract: PURPOSE:To obtain a skin beautifying cosmetic exhibiting excellent synergistic effect on the elimination or prevention of melanism or pigmentation of skin with ultraviolet ray, by compounding a specific unsaturated fatty acid (derivative) and ascorbic acid, extract of placenta, kojic acid, etc. CONSTITUTION:The cosmetic contains (A) a compound selected from a 18-22C fatty acid containing >=2 unsaturated bonds in a molecular structure (e.g. linoleic acid or eicosapentaenoic acid), its salt and its ester with monohydric or dihydric alcohol and (B) a compound selected from ascorbic acid (derivative), placenta extract, kojic acid (derivative), glucosamine (derivative), azelaic acid (derivative), retinol (derivative), pyridoxine (derivative), pantothenic acid (derivative), tranexamic acid (derivative), arbutin, photo-sensitizer, sulfur, tocopherol (derivative), etc. The amounts of the components A and B in the whole cosmetic are 0.1-10wt.% and 0.1-10wt.%, respectively.