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PubMed1984

Cardiovascular adrenoreceptor function during compensatory and decompensatory hemorrhagic shock.

Prior reports by Dr. Bond [1] have described the occurrence of an initial compensatory vasoconstriction followed by a decompensatory vasodilation response in animals that progress to irreversible shock induced by blood loss. Further analysis suggests that the secondary vascular decompensation is the result of sympathetic inhibition of adrenergic neurotransmission. The primary purpose of the present studies was to elucidate the roles of the alpha 1 and alpha 2 adrenoreceptors during initial compensatory and secondary decompensatory phases of hemorrhagic shock. This was accomplished by subjecting rat pairs to a modified Wiggers hemorrhagic shock protocol. One of these rats served as an untreated control (Rc) while the other (Re) received either an adrenergic antagonist or was bilaterally adrenal medullectomized 1-2 days prior to induction of shock. The adrenergic antagonists were: (1) propranolol, a nonspecific beta blocker; (2) phenoxybenzamine, a nonspecific alpha blocker; (3) tiodazosin, a specific alpha 1 blocker; and (4) yohimbine, a specific alpha 2 blocker. The results of these studies suggest that the beta receptors do not play a major role in either the compensatory or decompensatory response. Specific blockade of the alpha 2 adrenoreceptors accentuates decompensation by approximately 35%, while blockade of the alpha 1 adrenoreceptors may offer some degree of protection against the vascular decompensatory processes. These data support the conclusion that the extrasynaptic alpha 2 adrenoreceptors are better able to maintain the vascular compensatory effort than the alpha 1 adrenoreceptors.

Animals↗
PubMedDate not supplied

Interference by methyl levulinate in determination of total fat in low-fat, high-sugar products by gas chromatographic fatty acid methyl ester (GC-FAME) analysis.

Gas chromatographic fatty acid methyl ester (GC-FAME) analyses of some acid-hydrolyzed foods revealed a large peak that did not correspond to any FAME standards. The unknown peak eluted just after the C12 FAME. If the fatty acid response factor and the conversion factor for the nearest calibrated peak (C12 FAME) were used to determine the total fat, the resulting total fat determination was much higher than expected. This peak was present only in acid-hydrolyzed samples and was absent in extracts obtained with supercritical CO2 or solvents without acid hydrolysis. The compound was isolated, analyzed by mass spectrometry and nuclear magnetic resonance spectroscopy, and proved by synthesis to be methyl-4-oxopentanoate (methyl levulinate). Its source was determined to be sugar in the product formula. Levulinic acid is produced by acid hydrolysis of sugar and is transesterified by BF3 in methanol to methyl levulinate. Although methyl levulinate may appear in the GC analyses of any acid-hydrolyzed products containing sugar, if the ratio of fat to sugar is high, the impact of methyl levulinate on fat determination would be small. On the other hand, the presence of methyl levulinate in analyses of low-fat, high-sugar products is potentially problematic if not recognized, although GC analysis can account for the presence of this compound.

Chromatography, Gas↗
PubMed1970

Induction of dimorphism in the basidiomycete Lenzites saepiaria.

Sugars can serve as the germinant for basidiospores of the wood-rotting fungus Lenzites saepiaria. Hexoses sterilized by autoclaving were better germinants than hexoses that were sterilized by filtration. The degradation products in heated hexose which were responsible for the stimulation of germination were levulinic and formic acid. Another product of hexose degradation, hydroxymethyl furfural, had a marked effect on outgrowth of L. saepiaria basidiospores and on the development of mycelia. Basidiospores that germinated in the presence of hydroxymethyl furfural yielded large rounded bodies that, in some cases, developed as a chain of yeastlike cells. Addition of hydroxymethyl furfural to developing mycelia resulted in the production of chains of round yeastlike structures. Similar results were obtained by treating basidiospores or mycelia with phenethyl alcohol.

Acetates↗
PubMed2000

Effects of Ca(OH)(2) treatments ("overliming") on the composition and toxicity of bagasse hemicellulose hydrolysates.

Hemicellulose syrups from dilute sulfuric acid hydrolysates of hemicellulose contain inhibitors that prevent efficient fermentation by yeast or bacteria. It is well known that the toxicity of these hydrolysate syrups can be ameliorated by optimized "overliming" with Ca(OH)(2). We have investigated the optimization of overliming treatments for sugar cane bagasse hydrolysates (primarily pentose sugars) using recombinant Escherichia coli LY01 as the biocatalyst. A comparison of composition before and after optimal overliming revealed a substantial reduction in furfural, hydroxymethylfurfural, and three unidentified high-performance liquid chromatography (HPLC) peaks. Organic acids (acetic, formic, levulinic) were not affected. Similar changes have been reported after overliming of spruce hemicellulose hydrolysates (Larsson et al., 1999). Our studies further demonstrated that the extent of furan reduction correlated with increasing fermentability. However, furan reduction was not the sole cause for reduced toxicity. After optimal overliming, bagasse hydrolysate was rapidly and efficiently fermented (>90% yield) by LY01. During these studies, titration, and conductivity were found to be in excellent agreement as methods to estimate sulfuric acid content. Titration was also found to provide an estimate of total organic acids in hydrolysate, which agreed well with the sum of acetic, levulinic, and formic acids obtained by HPLC. Titration of acids, measurement of pH before and after treatment, and furan analyses are proposed as relatively simple methods to monitor the reproducibility of hydrolysate preparations and the effectiveness of overliming treatments.

Biotechnology↗
PubMed1999

Effect of organic acids on the growth and fermentation of ethanologenic Escherichia coli LY01.

Hemicellulose residues can be hydrolyzed into a sugar syrup using dilute mineral acids. Although this syrup represents a potential feedstock for biofuel production, toxic compounds generated during hydrolysis limit microbial metabolism. Escherichia coli LY01, an ethanologenic biocatalyst engineered to ferment the mixed sugars in hemicellulose syrups, has been tested for resistance to selected organic acids that are present in hemicellulose hydrolysates. Compounds tested include aromatic acids derived from lignin (ferulic, gallic, 4-hydroxybenzoic, syringic, and vanillic acids), acetic acid from the hydrolysis of acetylxylan, and others derived from sugar destruction (furoic, formic, levulinic, and caproic acids). Toxicity was related to hydrophobicity. Combinations of acids were roughly additive as inhibitors of cell growth. When tested at concentrations that inhibited growth by 80%, none appeared to strongly inhibit glycolysis and energy generation, or to disrupt membrane integrity. Toxicity was not markedly affected by inoculum size or incubation temperature. The toxicity of all acids except gallic acid was reduced by an increase in initial pH (from pH 6.0 to pH 7.0 to pH 8.0). Together, these results are consistent with the hypothesis that both aliphatic and mononuclear organic acids inhibit growth and ethanol production in LY01 by collapsing ion gradients and increasing internal anion concentrations.

Acids↗
PubMed1988

Synthesis of a spin-labeled phospholipid for studying membrane dynamics in intact mammalian cells.

We report here the synthesis of a spin-labeled phospholipid, 1-palmitoyl-2-(4-doxylpentanoyl)glycerophosphocholine. The synthetic route for this probe involves two major steps: 1) the synthesis of 4-doxylpentanoic acid from ethyl levulinate and 2-amino-2-methyl propanol, and 2) the synthesis of the lipid from 4-doxylpentanoic acid and lysolecithin. The efficiency and yield of both steps have been greatly improved. This represents the first instance that the synthesis of this important spin-labeled phospholipid is described in detail. Because it mimics the native lipid molecule and can be readily incorporated into biological membranes, this probe should be extremely useful for studying lipid dynamics in the plasma membrane of intact mammalian cells using electron spin resonance (ESR) spectroscopy.

Animals↗
PubMed1975

Biosynthesis of delta-aminolevulinic acid from the intact carbon skeleton of glutamic acid in greening barley.

The customary route in animals and bacteria for delta-aminolevulinic acid biosynthesis is from glycine and succinyl CoA, catalyzed by the enzyme delta-aminolevulinic acid synthetase [succinyl-CoA:glycine C-succinyltransferase (decarboxylating), EC 2.3.1.37]. Attempts to demonstrate this route in plants have been unsuccessful. Evidence is given for a new enzymic route of synthesis of delta-aminolevulinic acid in plants. This route involves the incorporation of the intact five-carbon skeleton of glutamic acid into delta-aminolevulinic acid. Demonstration of the new pathway in plants has been made by feeding specifically labeled [14C]glutamic acid to etiolated barley shoots greening in the light. In the presence of levulinate, a competitive inhibitor of delta-aminolevulinic acid dehydrastase [porphobilinogen synthase; delta-aminolevulinate hydro-lyase (adding delta-aminolevulinate and cyclizing); EC 4.2.1.24], delta-aminolevulinate accumulates. The delta-aminolevulinate formed was chemically degraded by periodate to formaldehyde and succinic acid. The C5 (formaldehyde) fragment was separated, as the 5,5-dimethyl-1,3-cyclohexanedione (dimedone) derivative, from the C1-C4 (succinic acid) fragment. The C5 atom contained radioactivity predominantly derived from C1 of glutamic acid. Conversely, the labeled C3 and C4 atoms of glutamic acid were found primarily in the succinic acid (C1-C4) fragment of delta-aminolevulinate. This labeling pattern for delta-aminolevulinic acid is consistent with a biosynthetic route utilizing the intact five-carbon skeleton of alpha-ketoglutarate, glutamate, or glutamine, and is inconsistent with the delta-aminolevulinic acid synthetase pathway utilizing glycine and succinyl CoA as precursors.

Aminolevulinic Acid↗
PubMed1984

Mechanisms and pathways of aniline elimination from aquatic environments.

The fate of aniline, a representative of arylamine pollutants derived from the manufacture of dyes, coal liquefaction, and pesticide degradation, was comprehensively evaluated by use of unpolluted and polluted pond water as model environments. Evaporation plus autoxidation proved to be minor elimination mechanisms, removing ca. 1% of the added aniline per day. Instantaneous binding to humic components of a 0.1% sewage sludge inoculum removed 4%. Biodegradation of aniline in pond water was accelerated by the sewage sludge inoculum. A substantial portion of the degraded aniline carbon was mineralized to CO2 within a 1-week period, and microbial biomass was formed as a result of aniline utilization. Biodegradation was clearly the most significant removal mechanism of polluting aniline from pond water. A gas chromatographic-mass spectrometric analysis of biodegradation intermediates revealed that the major pathway of aniline biodegradation in pond water involved oxidative deamination to catechol, which was further metabolized through cis,cis-muconic, beta-ketoadipic, levulinic, and succinic acid intermediates to CO2. Minor biodegradation pathways involved reversible acylation to acetanilide and formanilide, whereas N-oxidation resulted in small amounts of oligomeric condensation products.

Aniline Compounds↗