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PubMed2005

Synthesis of racemic and enantiomeric 3-pyrrolidinyl derivatives of purine and pyrimidine nucleobases.

The present work relates to the synthesis of pyrrolidine nucleoside analogs. Starting from malic acid, we have elaborated a high-yield synthesis of racemic and enantiomeric N-protected 3-pyrrolidinols and their O-mesyl derivatives as key compounds for alkylations of purine and pyrimidine nucleobases. On varying base and solvent, we have found conditions providing both satisfactory N-/O-regioisomeric ratio and acceptable yield for pyrimidine compounds.

Antineoplastic Agents↗
PubMed1952

Studies on the extracellular cultivation of an intracellular parasite (avian malaria). II. The effects of malate and of coenzyme A concentrates.

The extracellular survival and development in vitro of the erythrocytic stages of Plasmodium lophurae were favored by the addition to the culture medium of l-malic acid and concentrates rich in coenzyme A. In a concentrated extract of duck erythrocytes supplemented with these two substances in addition to adenosinetriphosphate, sodium pyruvate, and certain other materials of like nature, only 5 to 10 per cent of the extracellular parasites had become abnormal after 3 days of cultivation.

Adenosine Triphosphate↗
PubMed1994

Anion-cation interactions in the pore of neuronal background chloride channels.

Background Cl channels in neurons and skeletal muscle are significantly permeable for alkali cations when tested with asymmetrical concentrations of the same salt. Both anion and cation permeation were proposed to require binding of an alkali cation with the pore (Franciolini, F., and W. Nonner. 1987. Journal of General Physiology. 90:453-478). We tested this hypothesis by bilaterally substituting large alkali cations for Na and found no significant changes of unitary conductance at 300 mM symmetrical concentrations. In addition, all organic cations examined were permeant in a salt gradient test (1,000 mM internal@300 mM external), including triethanolamine, benzyltrimethylamine, and bis-tris-propane (BTP, which is divalent at the tested pH of 6.2). Inward currents were detected following substitution of internal NaCl by the Na salts of the divalent anions of phosphoric, fumaric, and malic acid. Zero-current potentials in gradients of the Na and BTP salts of varied anions (propionate, F, Br, nitrate) that have different permeabilities under bi-ionic conditions, were approximately constant, as if the permeation of either cation were coupled to the permeation of the anion. These results rule out our earlier hypothesis of anion permeation dependent on a bound alkali cation, but they are consistent with the idea that the tested anions and cations form mixed complexes while traversing the Cl channel.

Animals↗
PubMed1988

Calcium absorption from calcium carbonate and a new form of calcium (CCM) in healthy male and female adolescents.

Calcium absorption from two Ca salts was investigated in a crossover design using stable isotopic tracers in 12 healthy adolescents (6 males, 6 females). A Ca supplement in the form of Ca carbonate or Ca citric and malic acids (CCM) was ingested with a standardized breakfast and the order of administration was randomized. The oral supplement contained 250 mg elemental Ca, 21.8 mg of which was highly enriched 44Ca tracer. Thirty minutes later subjects received 3.6 mg 42Ca tracer intravenously. The molar concentrations of 42Ca and 44Ca tracers in a urine sample obtained 24 h after tracer administration were quantified by fast-atom-bombardment mass spectrometry and used to determine fractional absorption of the Ca from the supplement. Ca in the form of CCM had an increased fractional absorption (p less than 0.03) relative to Ca carbonate in healthy adolescents (36.2 vs 26.4%). This increase was not related to body size, sex, or indices of Ca metabolism.

Administration, Oral↗
PubMed2002

Aluminium toxicity in rye (Secale cereale): root growth and dynamics of cytoplasmic Ca2+ in intact root tips.

Aluminium (Al) toxicity in rye (Secale cereale L.), an Al-resistant crop, was examined by measuring root elongation and cytoplasmic free activity of calcium ([Ca2+]cyt) in intact root apical cells. Measurement of [Ca2+]cyt, was achieved by loading a Ca2+-sensitive fluorescent probe. Fluo-3/AM ester, into root apical cells followed by detection of intracellular fluorescence using a confocal laser scanning microscope. After 20 min of exposure to 50 microM Al (pH 4-2) a slight increase in [Ca2+]cyt of root apical cells was observed, while the response of [Ca2+]cyt to 100 microM Al (pH 4.2) was faster and larger ([Ca2+]cyt increased by 46% in 10 min). Increases in [Ca2+]cyt were correlated with inhibition of root growth, generally measurable after 2 h. Addition of 400 microM malic acid (pH 4.2) largely ameliorated the effect of 100 microM Al on [Ca2+]cyt in root apical cells and protected root growth from Al toxicity. These results suggest that an increase in [Ca2+]cyt in root apical cells in rye is an early effect of Al toxicity and is followed by the secondary effect on root elongation.

Aluminum↗
PubMed2002

Application of metabolomics to plant genotype discrimination using statistics and machine learning.

MOTIVATION: Metabolomics is a post genomic technology which seeks to provide a comprehensive profile of all the metabolites present in a biological sample. This complements the mRNA profiles provided by microarrays, and the protein profiles provided by proteomics. To test the power of metabolome analysis we selected the problem of discrimating between related genotypes of Arabidopsis. Specifically, the problem tackled was to discrimate between two background genotypes (Col0 and C24) and, more significantly, the offspring produced by the crossbreeding of these two lines, the progeny (whose genotypes would differ only in their maternally inherited mitichondia and chloroplasts). OVERVIEW: A gas chromotography--mass spectrometry (GCMS) profiling protocol was used to identify 433 metabolites in the samples. The metabolomic profiles were compared using descriptive statistics which indicated that key primary metabolites vary more than other metabolites. We then applied neural networks to discriminate between the genotypes. This showed clearly that the two background lines can be discrimated between each other and their progeny, and indicated that the two progeny lines can also be discriminated. We applied Euclidean hierarchical and Principal Component Analysis (PCA) to help understand the basis of genotype discrimination. PCA indicated that malic acid and citrate are the two most important metabolites for discriminating between the background lines, and glucose and fructose are two most important metabolites for discriminating between the crosses. These results are consistant with genotype differences in mitochondia and chloroplasts.

Algorithms↗
PubMed1989

Biochemical effects of juvenile hormone III on the tick, Argas (Persicargas) arboreus (Acari: Argasidae), during embryogenesis.

The biochemical effects of juvenile hormone III (JH III) on developing embryos from treated female Argas (Persicargas) arboreus Kaiser, Hoogstraal and Kohls were examined. Exogenous JH III resulted in a decrease in total proteins (P less than 0.001) only during the first 2 d of embryogenesis. There was no significant difference (P greater than 0.05) between RNA and DNA content in eggs from control and JH III-treated females. No significant difference (P greater than 0.05) was observed between control and JH III eggs in their lipid or phospholipid contents throughout embryogenesis. A total of 14-17 protein bands and 6-8 glycoprotein bands were separated by electrophoresis during embryogenesis of A. arboreus with some differences in mobility ratio between bands from control and JH III eggs. Differences in activity and isozyme patterns of malic acid, lactic acid, glucose 6-phosphate dehydrogenase, acid phosphatase, and alkaline phosphatase were not observed during embryogenesis of control and JH III-treated A. arboreus. Differences were observed in esterase activity.

Animals↗
PubMed1990

Biochemical changes in Hyalomma (Hyalomma) dromedarii (Acari: Ixodidae) embryos and effect of 20-hydroxyecdysone applied to the mother.

Changes in DNA, RNA, total lipids, phospholipids, and proteins and the activity of certain enzymes and pattern of their isozymes were studied in Hyalomma dromedarii Koch during embryogenesis. Total proteins fluctuated with a net increase (P less than 0.05) on day 20. Total lipids increased during the first half of embryogenesis and then declined with a net decrease to about 60% of the original level. Total phospholipids decreased to half this original level. DNA content increased greatly during cleavage, gastrulation, and organogeny and RNA increased during cleavage and blastula formation. Glucose-6-phosphate dehydrogenase (G6PDH) activity decreased (P less than 0.05), reaching 20% of its original level on day 12. Malic acid dehydrogenase (MDH) activity remained nearly unchanged throughout embryogenesis. Lactic acid dehydrogenase (LDH) activity increased greatly, with the highest level on day 14 with no further change. Acetylcholinesterase (AchE) activity increased greatly during the first 12 d, with no significant change thereafter. Acid (ACP) and alkaline (ALP) phosphatase activity increased during the first 12 d and declined returning to the original level on day 20. Seven AchE and 5 LDH isozymes were detected during different embryogenesis stages. Two MDH, 2 ACP, 1 ALP, and 2 G6PDH isozymes were detected throughout embryogenesis. Treating the mother with 20-hydroxyecdysone was associated with increases in protein and RNA contents and G6PDH and AchE activity and with decreases in ACP and ALP activity in the embryos.

Animals↗
PubMed2003

Malate synthase gene expression during fruit ripening of Cavendish banana (Musa acuminata cv. Williams).

Malate synthase (MS) is a key enzyme responsible for malic acid synthesis in the glyoxylate cycle, which functions to convert stored lipids to carbohydrates, by catalysing the glyoxylate condensation reaction with acetyl-CoA in the peroxisome. In this study, the cloning of an MS cDNA, designated MaMS-1, from the banana fruit is reported. MaMS-1 was 1801 bp in length encoding a single polypeptide of 556 amino acid residues. Sequence analysis revealed that MaMS-1 possessed the conserved catalytic domain and a putative peroxisomal targeting signal SK(I/L) at the carboxyl terminal. MaMS-1 also shared an extensive sequence homology (79-81.3%) with other plant MS homologues. Southern analysis indicated that MS might be present as multiple members in the banana genome. In Northern analysis, MaMS-1 was expressed specifically in ripening fruit tissue and transcripts were not detected in other organs such as roots, pseudostem, leaves, ovary, male flower, and in fruit at different stages of development. However, the transcript abundance in fruit was affected by stage of ripening, during which transcript was barely detectable at the early stage of ripening (FG and TY), but the level increased markedly in MG and in other fruits at advanced ripening stages. Furthermore, MaMS-1 expression in FG fruit could be stimulated by treatment with 1 microl l(-1) exogenous ethylene, but the stimulatory effect was abolished by the application of an ethylene inhibitor, norbornadiene. Results of this study clearly show that MS expression in banana fruit is temporally regulated during ripening and is ethylene-inducible.

Amino Acid Sequence↗
PubMed1994

Organic solute accumulation and dehydration tolerance in three water-stressed Populus deltoides clones.

The relationship between osmotic potential, water-soluble organic solutes and electrolyte leakage was investigated in three greenhouse-grown eastern cottonwood (Populus deltoides Bartr.) clones. The Ohio Red (from southern Ohio) and Platte (from eastern Nebraska) clones were selected because they differ in dehydration tolerance, gas exchange and osmotic potential. A third clone, Wildcat (from western Nebraska) was included because of its origin in a very dry area. Plants were either watered daily (control) or watered every 4-6 days (preconditioned). A third group of plants was watered daily until it was water-stressed at the end of the experiment (nonconditioned). Leaves for osmotic potential and water-soluble solute determinations were sampled at predawn after plants were rewatered. All clones showed osmotic adjustment ranging from 0.23 to 0.48 MPa. Organic solutes contributed up to 48% of the total osmotic adjustment. The solutes that contributed at least -0.05 MPa each to leaf osmotic potential in any clone were sucrose, malic acid, glucose, fructose, myoinositol and salicin. Fructose and glucose concentrations were unchanged or declined in preconditioned Ohio Red and Platte but increased in Wildcat. The Ohio Red clone had the highest sucrose concentration in both well-watered and preconditioned plants, and a lower injury index (more membrane stability) than Wildcat in the preconditioned plants, whereas nonconditioned Platte displayed the greatest electrolyte leakage of all clones and treatments. Cell membrane stability was correlated to osmotic potential and sucrose concentration only in Ohio Red.

Journal Article↗
PubMed2000

Antiproliferative activity in vitro of new malatoplatinum(ll) complexes.

The results of studies on antiproliferative activity in vitro of nine new platinum(II) complexes against cells of eight human and six murine neoplastic cell lines are described. New complexes with the anionic rest originating from enantiomeric forms of hydroxydicarboxylic malic acid were synthesized to obtain agents with increased water solubility and decreased toxicity. Three compounds, coded 1-3, with ethylenediamine as a neutral ligand, showed cytotoxic activity against 12 out of 14 target cell lines. Their cytotoxic activity was similar or even slightly higher than that of the reference carboplatin. The remaining six compounds, coded 4-9, with 1-alkylimidazole as a neutral ligand, revealed rather low cytotoxic activity, and only against the cells of the human bladder cancer cell line Hu1703He, ovarian cancer cell line OAW-42 and mouse leukemia P388. Most of them appeared to be negative against all other cell lines. No compounds, including reference carboplatin, showed any cytotoxicity against the cells of the T47D human breast cancer cell line or B16F-10 mouse melanoma cell line. The results obtained are in accordance with common opinion, i.e. that the presence of neutral amine ligands with NH groups is required for the cytotoxic activity of platinum complexes. Compounds with a primary amine (ethylenediamine) showed higher cytotoxic activity in vitro than complexes with a tertiary amine (1alkylimidazole).

Animals↗
PubMed2001

Systemic drug treatment for chronic musculoskeletal pain.

OBJECTIVE: The purpose of this review was to determine how effective different classes of analgesic agents are in the management of chronic pain. METHODOLOGY: The literature search identified five systematic reviews and 18 randomized controlled trials to provide evidence about systemic drug treatment for chronic pain. RESULTS: Studies in the systematic reviews were mainly of low back pain, and studies in the randomized controlled trials were mainly of fibromyalgia. Other studies investigated of rheumatic pain, musculoskeletal pain, chronic low back pain, and temporomandibular pain. Classes of analgesic agents reviewed were antidepressants, nonsteroidal anti-inflammatory drugs, muscle relaxants, opioid analgesics, and a number of miscellaneous agents. CONCLUSIONS: For chronic pain, opioid analgesics provide benefit for up to 9 weeks (level 2). For chronic low back pain, the evidence shows that various types of nonsteroidal antiinflammatory drugs are equally effective or ineffective, and that antidepressants provide no benefit in the short to intermediate term (level 2). Muscle relaxants showed limited effectiveness (level 3) for chronic neck pain and for chronic low back pain for up to 4 weeks. For fibromyalgia, there is limited evidence (level 3) of the effectiveness of amitryptiline, ondansetron, zoldipem, or growth hormone, and evidence of no effectiveness for nonsteroidal anti-inflammatory drugs, malic acid with magnesium, calcitonin injections, or s-adenyl-L-methionine. For temporomandibular pain, oral sumatriptan is not effective (level 2). The remaining evidence was inadequate (level 4a) or contradictory (level 4b).

Analgesics, Opioid↗
PubMed2005

The grapevine fleshless berry mutation. A unique genotype to investigate differences between fleshy and nonfleshy fruit.

In flowering plants, fruit morphogenesis is a distinct process following fertilization resulting in the formation of a specialized organ associated with seeds. Despite large variations in types and shapes among species, fleshy fruits share common characteristics to promote seed dispersal by animals such as organ growth and metabolite accumulation to attract animal feeding. The molecular biology of fruit ripening has received considerable attention, but little is known about the determinism of early fruit morphogenesis and why some fruits are fleshy while others lack flesh. We have identified in grapevine (Vitis vinifera) a mutation we have named fleshless berry (flb) that reduces by 20 times the weight of the pericarp at ripening without any effect on fertility or seed size and number. The flb mutation strongly impaired division and differentiation of the most vacuolated cells in the inner mesocarp. The timing of ripening was not altered by the mutation although the accumulation of malic acid in the green stage was noticeably reduced while sucrose content (instead of hexoses) increased during ripening. The mutation segregates as a single dominant locus. These results indicate that the Flb- mutant is suitable material to advance our understanding of the genetic and developmental processes involved in the differentiation of an ovary into a fruit.

Cell Differentiation↗
PubMed1976

Enhancement of CO(2) Uptake in Avena Coleoptiles by Fusicoccin.

When Avena coleoptile segments are immersed in a solution containing H(14)CO(3) (-), the appearance of label in the tissue is stimulated approximately 3-fold by fusicoccin application. This effect is rapid (1-2 minutes lag time), dependent upon respiratory energy, inhibited by carbonyl cyanide m-chlorophenylhydrazone, but not appreciably altered by cycloheximide treatment. A large percentage of the cellular radioactivity is found in the form of malate. Preliminary experiments indicate that CO(2), as opposed to HCO(3) (-), is the favored species of "CO(2)" taken up by the segments. These results are consistent with the notion that CO(2), presumably by virtue of its fixation and conversion to malic acid, participates in the early events associated with fusicoccin-enhanced acidification of the cell wall region leading to the stimulation of cell extension growth.

Journal Article↗
PubMed1981

Carbon metabolism in two species of pereskia (cactaceae).

The Pereskia are morphologically primitive, leafed members of the Cactaceae. Gas exchange characteristics using a dual isotope porometer to monitor (14)CO(2) and tritiated water uptake, diurnal malic acid fluctuations, phosphoenolpyruvate carboxylase, and malate dehydrogenase activities were examined in two species of the genus Pereskia, Pereskia grandifolia and Pereskia aculeata. Investigations were done on well watered (control) and water-stressed plants. Nonstressed plants showed a CO(2) uptake pattern indicating C(3) carbon metabolism. However, diurnal fluctuations in titratable acidity were observed similar to Crassulacean acid metabolism. Plants exposed to 10 days of water stress exhibited stomatal opening only during an early morning period. Titratable acidity, phosphoenolpyruvate carboxylase activity, and malate dehydrogenase activity fluctuations were magnified in the stressed plants, but showed the same diurnal pattern as controls. Water stress causes these cacti to shift to an internal CO(2) recycling ("idling") that has all attributes of Crassulacean acid metabolism except nocturnal stomata opening and CO(2) uptake. The consequences of this shift, which has been observed in other succulents, are unknown, and some possibilities are suggested.

Journal Article↗
PubMed1986

Stem infusions enhanced methionine content of soybean storage protein.

The quality of soybean (Glycine max [L.] Merrill) seed storage protein is limited by its low methionine (Met) content. Met supplementation of an in vitro soybean cotyledon culture has been shown to increase Met content by 21.9% due to an inhibition of the synthesis of the Met-devoid beta subunit of 7S storage protein (JF Thompson et al. 1981, Phytochemistry 20: 941-945). The objective of this research was to determine if Met supplementation of intact plants would result in a similar improvement in soybean protein quality. A solution including 10 millimolar d,l malic acid plus 10 millimolar K(2)HPO(4) with or without 20 millimolar d,l Met or 20 millimolar Na(2)SO(4) was infused throughout seed development into lower stem internodes of soybeans (cv ;Williams 79' or ;Williams 82') grown under both greenhouse and field conditions. Pediatric intravenous kits were used to infuse an average of 51.2 milliliters per plant. Met content of whole soybean seeds from intact plants receiving Met infusions increased by as much as 22.7%. Even greater (up to 31.0%) increases in cysteine (Cys) content were noted, indicating that soybean plants are able to metabolize Met to Cys, or that supplemental Met allows Cys accumulation by some other mechanism. Electrophoretic patterns showed a dramatic decrease in the synthesis of the beta subunit of 7S storage protein when Met was supplemented, and this effect was not confined to seeds at the lower nodes. In addition, seeds from upper compared to lower plant nodes (regardless of infusion treatment) had greater protein content (45.0 versus 41.6 w/w%), and different protein composition, as indicated by significantly different amino acid profiles. Methionine supplementation of intact soybean plants improved protein quality through an alteration in storage protein composition.

Journal Article↗
PubMed2005

Interactions between Saccharomyces cerevisiae and malolactic bacteria: preliminary characterization of a yeast proteinaceous compound(s) active against Oenococcus oeni.

AIMS: To investigate the occurrence and extent of Saccharomyces cerevisiae and Oenococcus oeni interactions. METHODS AND RESULTS: Interactions between S. cerevisiae and O. oeni were investigated by double-layer and well-plate assays showing the occurrence of specific interactions for each yeast-malolactic bacteria (MLB) coupling. Heat and protease treatments of synthetic grape juice fermented by the S. cerevisiae strain F63 indicated that the inhibitory activity exerted by this yeast on O. oeni is due to a proteinaceous factor(s) which exerts either bacteriostatic or bactericidal effect depending on concentration and affects malolactic fermentation in natural grape juice and wine. CONCLUSIONS: A proteinaceous factor(s) produced by a S. cerevisiae wine strain able to inhibit O. oeni growth and malic acid fermentation was characterized. SIGNIFICANCE AND IMPACT OF THE STUDY: The individuation, characterization and exploitation of yeast proteinaceous factor(s) exerting inhibitory activity on MLB may offer new opportunities for the management of malolactic fermentation.

Anti-Bacterial Agents↗
PubMed2006

Optimization of activation conditions of Rhodobacter sphaeroides in hydrogen generation process.

AIMS: To examine the effects of the culture age, illuminance intensity and changes in these parameters during activation on hydrogen generation process carried out by purple nonsulfur Rhodobacter sphaeroides bacteria. METHODS AND RESULTS: The following parameters were determined in all experiments: the amount of hydrogen evolved (measured using gas chromatography), biomass increase as dry mass, pH values and consumption of organic substance as chemical oxygen demand (COD). The medium used in the process of activation and hydrogen generation contained malic acid (15 mmol) and sodium glutamate (2 mmol). The optimum age of bacteria was 12-24 h and the best intensity of illuminance was found to be 5 cd sr m-2 on activation and 9 cd sr m-2 on hydrogen generation. These conditions provided hydrogen evolution of 1.39 l l-1 of the medium with the highest specific hydrogen production of 0.146 l H2 l-1 medium h-1 g-1 inoculum. An increase in the illuminance intensity resulted in a slight inhibition of the process. CONCLUSIONS: The activation stage of bacteria has a significant effect on the parameters of hydrogen photogeneration. The optimization of the activation stages allowed a shortening of the time of hydrogen generation and of the period after which hydrogen evolution starts. SIGNIFICANCE AND IMPACT OF THE STUDY: An innovative method of bacteria activation before the initiation of the hydrogen generation process has been used to optimize this process. The shortening of the process duration as well as the twice higher hydrogen yield can help in the designing of other systems (including also those operating under solar irradiation) in which R. sphaeroides bacteria are to be applied.

Biomass↗