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Showing papers on "Ascorbic acid published in 1970"



Journal ArticleDOI
TL;DR: The cell wall consists of an amorphous hemicellulose pectin matrix in which lie cellulose micro­ fibrils, and what is the explanation for the great difference between the degree of polymerization of primary wall and secondary wall cellulose?
Abstract: INTRODUCTION The cell wall is dead? The cell wall is alive and well? The cell wall consists of an amorphous hemicellulose pectin matrix in which lie cellulose micro­ fibrils? The cell wall consists of a highly ordered macromolecular multi­ l ayered network? Does the cell wall age? How are cell wall components synthesized? Where is the site of bio­ synthesis? Are Golgi, plasma membrane, endoplasmic reticulum, or micro­ tubules involved? How are the components transferred and inserted into the wall structure? Why are the growing ends of cellulose microfibrils not ob­ served? What mechanisms control the changeover from primary wall to secondary wall biosynthesis? What is the explanation for the great difference between the degree of polymerization of primary wall and secondary wall cellulose? Is the Loewus pathway for inositol metabolism of significance in changes from primary to secondary wall formation? What is the role of cell wall enzymes such as ascorbic acid oxidase, peroxidase, invertase, phospha­ tase, etc? Which of the multitude of possible cross-linkages actually exist in the wall, and which, if any of these, are labile and under cellular control? I f cell wall autolysis is involved in cell wall growth, which enzymes (autolysins?) are involved? How is the turnover of cell wall components related to growth? What is the role of the hydroxyproline-rich cell wall pro­ tein "extensin" ? What proportion of the wall polysaccharide is attached to the wall glycoprotein? Is there a protein glycan network in any way analo­ gous to bacterial peptido-glycan? Is it possible to show localization of hy­ droxyproline-rich protein by autoradiography? (Why have different workers reached different conclusions?) Is it meaningful to use such cl assical terms as apposition and intussusception in considering how cell walls grow? Are classical terms such as pectic substances and hemicellulose sufficiently pre-

307 citations


Book
01 Jan 1970

247 citations


Journal ArticleDOI
TL;DR: It is pointed out that the amount contained in a diet of raw natural plant food is less than the optimum intake, corresponding to the best health, and the conclusion that the optimum daily intake is about 2.3 g or more.
Abstract: Ascorbic acid differs from other vitamins in that an exogenous source is required by only a few animal species. It is pointed out that this fact indicates that the amount contained in a diet of raw natural plant food is less than the optimum intake, corresponding to the best health. This argument leads to the conclusion that the optimum daily intake is about 2.3 g or more, for an adult with energy requirement 2500 kcal day-1.

179 citations


Journal ArticleDOI
TL;DR: A definite need exists for low-cost artificial diets that will decrease the cost of mass producing insects, but such an inexpensive diet must also produce healthy, vigorous insects that act as nearly normal as possible.
Abstract: A definite need exists for low-cost artificial diets that will decrease the cost of mass producing insects. However, such an inexpensive diet must also produce healthy, vigorous insects that act as nearly normal as possible. Generally, the more defined, the more expensive a diet becomes. Therefore, one composed of crude organic materials that already contain most of the required nutritional components, defined by Dougherty (1959) as oligidic, should be the least expensive. Then the lowest possible cost could be achieved by purchasing, processing, mixing, and supplementing very large quantities. Blended Food Product, Child Food Supplement, Formula no. 2, commonly called CSM (for corn, soy flour, and milk solids), is such a product.

151 citations


Journal ArticleDOI
TL;DR: Since dopamineβ-hydroxylase activity in adrenal medulla was found to be inhibited in vivo after the administration of fusaric acid, the decrease in the catecholamine levels is attributed to the inhibition of norepinephrine synthesis at the dopamine β-Hydroxylases stage.

149 citations


01 Jan 1970
TL;DR: In this article, a review of the food processing and by-products industries for basic chemical information on the composition of citrus fruits is presented, which is an attempt to indicate the technological relevance of the various chemical constituents of the citrus fruits.
Abstract: Publisher Summary This chapter aims to review the food processing and by-products industries for basic chemical information on the composition of citrus fruits. It is an attempt to indicate the technological relevance of the various chemical constituents of citrus fruits. The chapter tabulates classification of citrus fruits. The chemical determinations most frequently reported on citrus fruits are the soluble solids content and the acidity, as well as the ascorbic acid content because of its obvious nutritional significance. The large volume of information that has accumulated on these three characteristics of citrus fruits has been reviewed separately and specific groups of constituents have been discussed detail. Ranges of values for the soluble solids content, the acidity, and the ascorbic acid content of six citrus fruits have been presented. The variability in composition among and within different kinds of citrus fruits is influenced by many factors such as genetic factors, by rootstock, by maturity, by the position of the fruit on the tree, by field factors, and by orchard practices. These factors have been discussed in detail. As an example of a specific investigation of varietal differences, the work on the ascorbic acid content of Palestine citrus fruits has been cited. The chapter provides information on the composition of citrus fruit such as carbohydrates in citrus juices, in citrus pulps and peels; acids in citrus juices, in citrus peels; vitamins, ascorbic acid and other vitamins. The chapter presents factors affecting the nitrogen content of citrus fruits. It summarizes present knowledge on considerable variety of amino acids and bases that has been identified in citrus fruits. Attempts have been made to use the nitrogen compounds of citrus juices as a basis for the estimation of the juice content of citrus beverages.

149 citations


Book ChapterDOI
TL;DR: This chapter looks at ascorbic acid as an added nutrient in a nutrient capacity or as a food processing aid is subject to government regulation in many countries.
Abstract: Publisher Summary The use of L-ascorbic acid in processing food was reviewed by Bauernfeind in 1953. By that time, several hundred papers had already been published on studies of various applications of this compound in food processing. L-Ascorbic acid, a 6-carbon compound and a water-soluble vitamin also known as vitamin C (for cevitamic acid), exists in both the reduced and the oxidized forms (dehydroascorbic acid) in nature. It is found in all living tissues. Citrus fruits, tomatoes, potatoes, and cabbage are the important natural dietary sources for man, but content varies depending on variety, environmental factors, and processing. L-Ascorbic acid (vitamin C) is added to processed fruit, vegetables, meat, fish, milk, fats, oils, flour, soft drinks, malt beverages, wine, confections, and synthetic foods. It may be added to enhance nutritional value, or to improve keeping qualities, color, stability, palatability, clarity, or baking quality. This chapter looks at ascorbic acid as an added nutrient. The use of L-ascorbic acid to inhibit or prevent undesirable oxidative changes in the processing of foodstuffs has been largely empirical. It discusses ascorbic acid as synergist in fat protection, preventive of fruit browning, preventive of vegetable discolorations, inhibitor of oxidative rancidity in fish, stabilizer of meat color, flour or bread improver, oxygen acceptor in beer processing, reducing agent in wine, oxidation inhibition in dairy products, and other miscellaneous uses. The use of ascorbic acid in a nutrient capacity or as a food processing aid is subject to government regulation in many countries. The status of ascorbic acid addition in each instance of desired use should be determined by consulting the pertinent regulation. A brief review of the regulatory requirements in some countries is given here. This chapter ends with the discussion of L-Ascorbic acid vs. erythorbic acid.

133 citations


Journal ArticleDOI
TL;DR: Although Ham's F12 medium is advantageous in establishing a primary culture of chondrocytes, sulfate incorporation was greater when Dulbecco-Eagle medium, with or without supplemental L-proline, was used for subcultures and ascorbic acid added to an already confluent monolayer had no consistent effect.
Abstract: Articular chondrocytes in primary monolayers or subcultures synthesize sulfated macromolecules, presumably mucopolysaccharides. Intracellular 35SO4 incorporation by postnatal rabbit chondrocytes reached a steady level by 24 hr of incubation; the nondialyzable extracellular (centrifuged medium + trypsin digest) counts increased over 72 hr, when they were up to 100 times the intracellular value. Cell for cell, radiosulfate counts in each fraction were higher in chondrocytes than fibroblasts. Data from a 3-year-old rabbit were comparable to those from recently weaned animals. Secretion of sulfated mucopolysaccharide was also found in cultures of adult human and bovine articular chondrocytes. Although Ham's F12 medium is advantageous in establishing a primary culture of chondrocytes, sulfate incorporation was greater when Dulbecco-Eagle medium, with or without supplemental L-proline, was used for subcultures. Ascorbic acid (5 mg/100 ml) added to an already confluent monolayer had no consistent effect.

108 citations


Book ChapterDOI
TL;DR: This chapter describes the assay, purification, and properties of pyrocatechase, which is based on the measurement spectrophotometrically of the rate of formation of cis,cis-muconic acid.
Abstract: Publisher Summary This chapter describes the assay, purification, and properties of pyrocatechase. The assay is based on the measurement spectrophotometrically of the rate of formation of cis,cis-muconic acid. The rate of oxygen uptake can be measured by means of a polarographic technique. One unit of enzyme activity is defined as that amount that catalyzes the formation of 1 micromole of cis,cis-muconic acid per minute at 24°. Protein is determined spectrophotometrically from the absorbance at 280 and 260 mμ. The crude enzyme is stable for long periods of time at 4°. The purified enzyme is less stable; it loses about 15% of its activity during storage for four days at 4 °. The enzyme is most stable at a pH range of 8.0–9.5. Upon freezing, the purified enzyme at -20o for several months, the red enzyme solution changes to a more bluish color with a concomitant complete loss of activity. Sodium dithionite, ascorbic acid, sodium borohydride, mercaptoethanol, cysteine, reduced glutathione, or ferrous ion increase the rate of inactivation.

107 citations


Journal ArticleDOI
TL;DR: This brief account records the first ingestion of potassium dichromate by a child treated by peritoneal dialysis, and the presence of chromate in the stomach was confirmed.
Abstract: Although the industrial hazards of both acute and chronic chromate poisoning are well recognized, 1-2 the ingestion of hexavalent chromium compounds is uncommon and usually fatal. The recording of such oral poisonings in children, particularly potassium dichromate, is extremely rare. 3-7 This brief account records the first ingestion of potassium dichromate by a child treated by peritoneal dialysis. Report of a Case A 14-year-old boy was transferred to UCLA Hospital three days after the ingestion of approximately 1.5 gm of potassium dichromate obtained from his chemistry set and taken in an attempt to "get high." Ingestion was followed immediately by nausea and vomiting. Gastric lavage was performed at a local emergency room, and the presence of chromate in the stomach was confirmed. The patient was admitted to the hospital and given parenteral fluids in an attempt to induce diuresis. Twenty-four hours after admission he became anuric, and his blood urea

Journal ArticleDOI
01 May 1970-Blood
TL;DR: Black beans, a staple food consumed in large amounts in Central and South America, were used as a model for the studies of the effect of fish or amino acids present in fish on iron absorption from vegetable food, and showed an asymmetric distribution.

Journal ArticleDOI
TL;DR: Procedures are described for estimating pyrrole and N-oxide metabolites formed in animal tissues from pyrrolizidine alkaloids in vivo or in vitro.

Journal ArticleDOI
TL;DR: In this paper, 40 lots of strawberries, consisting of 13 different selections and 5 varieties, were packed as frozen, sliced, sugared (4:1) fruit and after 9 months of storage, panel evaluation of the color quality and Gardner L, a, b determinations were taken.
Abstract: SUMMARY— 40 lots of strawberries, consisting of 13 different selections and 5 varieties, were packed as frozen, sliced, sugared (4:1) fruit. Total anthocyanin content, the relative amounts of pelargonidin-3-glucoside and cyanidin-3-glucoside, ascorbic acid, pH, total acidity, soluble solids and Gardner L, a, b. determinations were made. After 9 months of storage, panel evaluation of the color quality and Gardner L, a and b determinations were taken. Results of correlation analyses indicated that pH was the only objective measurement having a high correlation with color quality. Neither ascorbic acid, total acidity nor soluble solids had significant correlations with color quality. From regression equation values, it was calculated that berries should have a pH of 3.51 or lower to have acceptable color after freezing. Anthocyanin content should be in the approximate range 450–700 μg/g to have acceptable color quality.

Journal ArticleDOI
TL;DR: In this article, various flavonoids inhibit the production of adenosine triphosphate in mitochondria of cucumber hypocotyls, and the structural details regulating the activity against ATP production are different from those determining the activity of flavonoid in the oxidation of indol-3-yl acetic acid and of ascorbic acid.

Journal ArticleDOI
TL;DR: Protocatechuate 4,5-dioxygenase was purified from a pseudomonad to an almost homogeneous state and the inactivation was found to be due simply to the removal of the iron from the enzyme protein, since the inactivated enzyme was fully reactivated by the addition of Fe 2+ alone.

Journal ArticleDOI
TL;DR: The culture of sorghum callus, the initiation of shoot primordia, and development of plants from callus tissue of this species are described.
Abstract: Successful culturing of callus has recently been reported for the following monocotyledonous species: corn (Reference 2, and Linsmaier Bednar, E. M., personal communication), oats (1, 6), rice root (8), asparagus (7), wheat (5), and sorghum (4). For the culture of sorghum callus from roots and tillering nodes, Strogonov et al., (4) used Murashige and Skoog's basal medium plus calcium pantothenate, 5 mg/liter; 2,4-dichlorophenoxyacetic acid, 1 mg/liter; kinetin, 1 mg/liter; casein hydrolysate, 0.5 g/liter; and ascorbic acid, 1 mg/liter. The same basal inorganic medium was also used for the culture of oats (1), asparagus (7), and by Linsmaier Bednar for corn. Corn callus was also cultured on White's medium (2), oats and rice root on Heller's medium (6, 8), and wheat on Hildebrandt's D medium (5). Generally, 2,4-D was used as the auxin, but a-naphthaleneacetic acid as well as 2,4-D was used for corn (2). In other respects the same nutrients and growth conditions were used as those required for the culture of dicotyledonous callus. The ability of monocotyledonous callus tissue to form organs has been demonstrated by the production of embryoids and plantlets from asparagus cells (7), many shoots but few roots from oats (1), roots from wheat callus (5), and roots (2) and both roots and shoots from corn callus (Linsmaier Bednar, E. M., personal communication). This report describes the culture of sorghum callus, the initiation of shoot primordia, and development of plants from callus tissue of this species.


Journal ArticleDOI
TL;DR: The enzyme activity was increased at 5 weeks in silicotic rats and reached a maximum, 259 per cent of the control value, at 16 weeks after the induction of silicosis, before fibrosis could be demonstrated by means of histological staining or chemical hydroxyproline analyses.

Journal ArticleDOI
TL;DR: The concentrations of sodium, potassium, calcium, magnesium, glucose, lactic acid, free α-amino nitrogen and ascorbic acid were determined in the aqueous and vitreous humor of rabbit eyes directly after enucleation and after up to 4 hr of incubation of the globes at either 3° or 37°C.


Journal ArticleDOI
TL;DR: In this paper, Δ 9 -Tetrahydrocannabinol (Δ 9 -THC) was found to be a potent stimulator of ACTH secretion, as evidenced by depletion of adrena ascorbic acid in rats.

Journal ArticleDOI
TL;DR: Data presented in this paper can be interpreted as evidence that both heme and non-heme iron are functioning as catalysts of lipid oxidation in meat, since the most direct evidence comes from cooked meat.
Abstract: SUMMARY Data presented in this paper can be interpreted as evidence that both heme and non-heme iron are functioning as catalysts of lipid oxidation in meat. The most direct evidence comes from cooked meat, since there the picture is not complicated by interfering enzymes. After removal of MetMb by treating with H2O2, a significant lipid oxidation was demonstrated, especially at lower pH where non heme iron is most active. The catalytic activity of hemoprotein is limited in raw meat. Oxygen can be removed from the tissues and MetMb reduced back to Mb by the reducing enzymes. This is especially true at higher PH. Possible limitations of the heme-catalyzed reactions in meat by high (inhibition) levels of myoglobin, or because of separation of reactants in cellular structures, are discussed. The effects of additives were in line with the interpretation that lipid oxidation is catalyzed by both non-heme and hemoprotein. In raw meat, lipid oxidation could be slightly accelerated by adding TDPA or cysteine but inhibited by adding ascorbic acid or EDTA. It is considered that EDTA inhibited the non-heme iron catalysis at the natural acidic pH, whereas ascorbic acid prevented Mb oxidation and thus indirectly retarded the rancidity developed.


Journal ArticleDOI
TL;DR: The results suggested that the effect of ascorbic acid deficiency on Elastin biosynthesis could be regarded as simply an elimination of hydroxylation of elastin proline with the formation and retention of a polymer increasingly deficient in hydroxyproline.
Abstract: 1. After the administration of l-[G-3H]proline to guinea pigs deprived of ascorbic acid for increasing periods of time, the specific radioactivities of proline and hydroxyproline in skin collagen and aortic elastin were determined at various time-intervals after administration of the labelled compound with a view to studying the formation and degradation of collagen and elastin both deficient in hydroxyproline. 2. As judged from the incorporation of radioactivity into elastin proline, elastin synthesis was not decreased in the ascorbic acid-deficient animals. There was however, a rapid decline in the specific radioactivity of elastin hydroxyproline. The proline/hydroxyproline specific-radioactivity ratio was approx. 1.5:1 after 6 days and 20:1 after 12 days of ascorbic acid deprivation, in contrast with the ratio of 1:1 in controls. The results suggested that the effect of ascorbic acid deficiency on elastin biosynthesis could be regarded as simply an elimination of hydroxylation of elastin proline with the formation and retention of a polymer increasingly deficient in hydroxyproline. 3. Collagen proline and hydroxyproline specific radioactivities were derived from material that was soluble in hot trichloroacetic acid, non-diffusible and collagenase-degradable. In contrast with elastin, there was a rapid decline in the specific radioactivity of proline as well as hydroxyproline in collagen from the ascorbic acid-deficient animals. However, the proline/hydroxyproline specific-radioactivity ratio in all samples from scorbutic animals was consistently slightly above 1:1. The results suggest the appearance in place of collagen, but in rapidly diminishing amounts, of a partially hydroxylated collagen in which the degree of hydroxylation may be decreased only by approx. 10%. 4. Incorporation of radioactivity into the diffusible hydroxyproline in skin remained relatively high despite the rapid decline in the incorporation of radioactivity into collagen. This observation is interpreted as indicative of an increasing degree of degradation of partially hydroxylated collagen to diffusible peptides. An alternative explanation might be that partially hydroxylated peptides are released to an increasing extent from ribosomes before they attain a length at least sufficient to render them non-diffusible. In either case it implies the accumulation in scurvy of low-molecular-weight peptides enriched in proline and deficient in hydroxyproline and could explain the failure to accumulate a high-molecular-weight collagen deficient in hydroxyproline. 5. It is thought, however, that, in addition, an inhibition of ribosomal amino acid incorporation leading to decreased synthesis of partially hydroxylated collagen may also occur, perhaps secondarily to impaired hydroxylation.

Journal ArticleDOI
TL;DR: PGE1 did not affect adrenal ascorbic acid in cortisol-pretreated intact rats or in 24-hr hypophysectomized rats, indicating that it has no ACTH-like effect on the adrenal cortex but acts by stimulating ACTH release.
Abstract: Prostaglandin E1 (PGE1) depleted adrenal ascorbic acid and cholesterol and increased plasma and adrenal corticosterone in rats. The log dose relationship between PGE1 iv and adrenal ascorbic acid concentration was linear between 0.5 and 2.0 μg. PGE1 was relatively specific since PGA1 and PGF2a did not deplete adrenal ascorbic acid at doses 10 times that of PGE1 and the respective vasopressor and vasodilator activities of the 3 prostaglandins did not correlate with capacity to stimulate the adrenal cortex. PGE1 did not affect adrenal ascorbic acid in cortisol-pretreated intact rats or in 24-hr hypophysectomized rats, indicating that it has no ACTH-like effect on the adrenal cortex but acts by stimulating ACTH release. Morphine strongly inhibited the adrenal ascorbic acid response to PGE1 in intact rats anesthetized with pentobarbital, indicating that the action of PGE1 on ACTH release is not direct on the anterior pituitary gland but is at some level in the central nervous system, possibly the hypothalamus...

Journal ArticleDOI
04 Sep 1970-Science
TL;DR: Dietary ascorbic acid supplements almost completely prevented the anemia and improved the growth rate but did not markedly alter concentrations of iron or cadmium in the liver.
Abstract: Feeding the environmental toxicant cadmium to young Japanese quail for 4 weeks produced growth retardation, severe anemia, low concentrations of iron in the liver, and high concentrations of cadmium in the liver. Dietary ascorbic acid supplements almost completely prevented the anemia and improved the growth rate but did not markedly alter concentrations of iron or cadmium in the liver.

Journal ArticleDOI
TL;DR: Experiments with specifically labeled l-gulono-1,4-lactone and l-galactono-2-(14)C) prove that conversion is direct, and this method can be extended to the preparation of l-ascorbic acid-2-C on the basis of results obtained in the present study.
Abstract: Detached bean ( Phaseolus vulgaris ) and strawberry ( Fragaria ) fruits fed l-gulono-1,4-lactone or l-galactono-1,4-lactone convert this compound, in part, to l-ascorbic acid. When l-galactono-1,4-lactone is given as a 0.25% solution to detached bean shoots, the ascorbic acid content is tripled in less than 10 hours. l-Gulono-1,4-lactone is only 5 to 10% as effective as its epimer. Experiments with specifically labeled l-gulono-1,4-lactone and l-galactono-1,4-lactone prove that conversion is direct. Ascorbic acid is labeled at the same carbon as its precursor. A method is described for preparation of l-galactono-1,4-lactone-2- 14 C from myo -inositol-2- 14 C. This method can be extended to the preparation of l-ascorbic acid-2- 14 C on the basis of results obtained in the present study.

Journal ArticleDOI
01 Aug 1970-BMJ
TL;DR: It is concluded that the offer of a routine examination to high risk groups is of benefit to old people and a form of medical practice which should be widely adopted.
Abstract: Medical examination was offered to a group of “high risk” old people who were not necessarily patients or known to their family doctors, but with the agreement of these family doctors. Two clinics set up for this purpose have been running for several years, and the results of examination and follow-up of 300 consecutive patients are reported. Major conditions were found in two-thirds of patients producing functional impairment in most of these. Recommendations as to therapy and management were carried out in 161 of 194 patients but not in the remainder. Clear evidence of improvement was found in half of the patients who carried out recommendations, and this improvement was attributable to earlier diagnosis than would have been achieved without these clinics in 42% of cases. Including all patients examined, the proportion helped by early diagnosis at 18 to 30 months9 follow-up was 23%. It is concluded that the offer of a routine examination to high risk groups is of benefit to old people and a form of medical practice which should be widely adopted.

Journal ArticleDOI
TL;DR: The results appear to contradict the generally accepted concept that alata-production is enhanced by poor nutrition, as poor larval growth was associated with the production of apterous rather than alate progeny by their mothers on artificial diets.