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At least 883 records · Page 49Linked to original sources
PubMed2000

High-performance liquid chromatographic separation and measurement of various biogenic compounds possibly involved in the pathomechanism of Parkinson's disease.

The work presented here describes an optimised, reversed-phase high-performance liquid chromatographic (RP-HPLC) method for separating 46 biogenic compounds, which, as neurotoxins or as their precursors or derivatives, may be relevant in the pathomechanism of Parkinson's disease. In some cases, the physico-chemical properties of these substances are very similar, in other cases they differ greatly. In order to facilitate their detection in one chromatographic run, ion-pair chromatography was uniquely combined with a gradient elution. A diode array or a dual wavelength detector was used in combination with a fluorescence detector to verify the identity of the compounds.

Chromatography, High Pressure Liquid↗
PubMed1996

Evidence of the involvement of biogenic amines in the antinociceptive effect of a vouacapan extracted from Pterodon polygalaeflorus Benth.

In view of the extensive use of Pterodon species in Brazilian folk medicine, the present investigation was performed to examine the involvement of biogenic amines in antinociceptive by a vouacapan (6 alpha-7 beta-dihydroxy vouacapan-17 beta-oate), extracted from seeds of Pterodon polygalaeflorus Benth), using acetic acid writhing test in mice. The alpha 2-adrenergic (yohimbine) and D2-dopaminergic (domperidone) antagonists and the pretreatment with the peripheral noradrenergic depletor, guanethidine partially inhibited the antinociceptive effect of vouacapan. Dopamine and D2 dopaminergic agonist (Ly 17155) caused antinociceptive that was not antagonized by naloxone but by domperidone, whereas noradrenaline induce pain. A synergistic analgesic effect was obtained when vouacapan was associated with clonidine or dopamine. These results indicate that vouacapan acts, at least in part, through activation of the catecholaminergic system.

Analgesics, Non-Narcotic↗
PubMed1977

Biogenic amine-related enzymes and personality variations in normals.

Altered activities of biogenic amine-related enzymes have been reported in some studies of patients with affective disorders and chronic schizophrenia. To evaluate whether any relationship between personality variations, including non-diagnosed psychopathology, and these enzymes might occur in non-psychiatric patients, 95 young adult volunteers were studied. Higher MMPI and Zuckerman sensation--seeking scale scores were found in male, but not female, volunteers with lower platelet and plasma amine oxidase activities. Males generally exhibited negative correlations, while females had positive correlations between the psychological test scores and amine oxidase activities. In contrast to the amine oxidase results, no associations were observed between plasma dopamine beta-hydroxylase activities and the personality variables.

Adolescent↗
PubMed2000

Role of maternal biochemistry in fetal brain development: effect of maternal thyroidectomy on behaviour and biogenic amine metabolism in rat progeny.

Few studies have addressed the role of biochemicals of maternal origin on fetal neurodevelopment and behavioural outcome. Thyroid deficiency in the thyroidectomized pregnant rat provides an excellent model to study fetal effects of maternal chemistry, as this condition is known to be associated with deficits in motor and cognitive behaviour in human offspring. Based on evidence that thyroid hormone of maternal origin may be an important determinant in regulating these behaviours, we assessed neurobehaviours and regional brain biogenic amine levels in offspring of rats thyroidectomized (Tx) prior to conception. Cross-fostering techniques were used to isolate fetal effects of maternal thyroid deficiency from possible neonatal effects during nursing by thyroid-deficient dams. The progeny of Tx dams showed significant deficits in maze learning, were less cautious in emotionality testing, and were more active in open-field exploration. Tx females appeared to be more vulnerable to the effects on learning. Learning in Tx males was only slightly impaired. Serotonin and dopamine metabolism was also affected in a brain region-specific manner in Tx progeny. Levels of 5-HIAA were reduced in the olfactory tubercle and cortex. HVA levels were lower in olfactory tubercle, but were elevated in the hippocampus. As these neurotransmitters play a functional role in activity, mood and learning, the findings may be pertinent to the observed behavioural impairments. The results are consistent with the hypothesis that an adequate in utero thyroid hormone environment may be essential for early fetal neurodevelopment even if the fetus is euthyroid.

Journal Article↗
PubMed2001

Monitoring biogenic volatile compounds emitted by Eucalyptus citriodora using SPME.

A procedure to monitor BVOC emitted by living plants using SPME technique is presented. For this purpose, a glass sampling chamber was designed. This device was employed for the characterization of biogenic volatile compounds emitted by leaves of Eucalyptus citriodora. After extraction with SPME fibers coated with PDMS/ DVB, it was possible to identify or detect 33 compounds emitted by this plant. A semiquantitative approach was applied to monitor the behavior of the emitted BVOC during 9 days. Circadian profiles of the variation in the concentration of isoprene were plotted. Using diffusion-based SPME quantitation, a recently introduced analytical approach, with extraction times as short as 15 s, it was possible to quantify subparts-per-billion amounts of isoprene emitted by this plant.

Butadienes↗
PubMed1996

Reactions between vanadium ions and biogenic reductants of tunicates: spectroscopic probing for complexation and redox products in vitro.

Several species of marine tunicates store oxygen-sensitive VIII in blood cells. A sensitive colorimetric VIII assay was used to survey the leading candidates for the native reducing agent of vanadate in tunicates (i.e., An-type tunichromes, glutathione, NADPH, and H2S) in reactions with VV or VIV ions under anaerobic, aqueous conditions at acidic or neutral pH. Except for the case of An-1 and VV ions in pH 7 buffer, the assay results for the biogenic reducing agents clearly showed that appreciable quantities of VIII products were not generated under the conditions tested. Therefore, the assay results place new limits on hypothetical mechanisms of VIII formation in vivo. For reactions between An-1 and VV ions in pH 7 buffer, low levels of VIII products could not be ruled out because of an interfering peak in the colorimetric assays. For similar reactions between VV ions and An-1, or an An-1,2 mixture, in mildly to moderately basic media, the product mixtures precipitated as greenish black solids. Analyses of the precipitated V/An mixtures using vanadium K-edge X-ray absorption spectroscopy (XAS) showed that the major products were tris(catecholate)-type VIV complexes (65 +/- 6%) and bis(catecholate)-type VIVO complexes (20 +/- 4%). XAS analysis of the V/An-1 product mixture also provided evidence of a minor VIII component (9 +/- 5% of total V), notable for possible relevance to tunicate biochemistry. The combined results of XAS studies, spectrophotometric studies [Ryan, D. E., et al. (1996) Biochemistry 35, 8640-8650], and EPR studies [Grant, K. B., et al. (1996) J. Inorg. Biochem. (manuscript in preparation)] consistently establish that reactions between tunichromes (Mm-1 or An-1) and VV ions generate predominantly VIV-tunichrome complexes in neutral to moderately basic aqueous media.

Animals↗
PubMed2002

Biogenic phosphate minerals in manure: implications for phosphorus loss to surface waters.

Phosphorus (P) is present in waterways throughout the United States at concentrations that impair water quality. Agriculture, particularly livestock production, has been identified as a major cause of this impairment Excess manure P applied to croplands has increased P losses in runoff, leading to surface water eutrophication. We conducted a long-term (36-week) incubation with poultry and dairy manures applied to a silt loam soil to elucidate mechanisms controlling manure P loss to water. Manures were applied to supply the same total P rate to soils with different antecedent plant-available P concentrations (soil test P). There was a strong synergistic effect between dairy manure and soil test P on water extractable P, while soil test P did not affect P loss from poultry manure-amended soils. Using scanning electron microscopy and energy dispersive X-ray spectroscopy, we found that poultry manure contained sparingly soluble calcium and magnesium phosphate minerals that controlled soil solution P concentrations, while dairy manure did not These minerals resemble other biogenic phosphate minerals. Our findings refute current assumptions that all manure P behaves similarly in soils and that organic forms control manure-soil P loss to water.

Agriculture↗
PubMed2004

Carbon tetrachloride transformation on the surface of nanoscale biogenic magnetite particles.

Iron-reducing conditions in subsurface environments promote dechlorination reactions via both biotic and abiotic pathways, the latter often mediated via biologically activated minerals formed by dissimilatory iron-reducing bacteria (DIRB). Here we report the major products and pathways associated with the abiotic transformation of carbon tetrachloride (CT) by nanoscale biogenic magnetite/maghemite particles produced by the DIRB Geobacter metallireducens. Product formation and free radical/carbene trapping studies indicate that CT transformation occurs via three parallel pathways. The first pathway (hydrogenolysis) results in the formation of chloroform (45-50%) via a trichloromethyl free radical (*CCl3) and possibly a trichloromethyl carbanion (**CCl3-). The second and third pathways involve a dichlorocarbene intermediate (**CCl2), which either hydrolyzes to form CO (approximately 38%) (carbene hydrolysis), or undergoes further reduction to yield methane (8-10%) (carbene reduction). The mechanism of methane formation from **CCl2 is not known, but is speculated to involve a sequence of surface coordinated carbenoid and free radical complexes. The large fraction of relatively benign products formed by the carbene-mediated pathways suggests that magnetite/maghemite particles may have a beneficial application in the remediation of CT contaminated environments.

Carbon Tetrachloride↗
PubMed2005

Mechanisms of Pb(II) sorption on a biogenic manganese oxide.

Macroscopic Pb(II) uptake experiments and Pb L3-edge extended X-ray absorption fine structure (EXAFS) spectroscopy were combined to examine the mechanisms of Pb(II) sequestration by a biogenic manganese oxide and its synthetic analogues, all of which are layer-type manganese oxides (phyllomanganates). Relatively fast Pb(II) sorption was observed, as well as extremely high sorption capacities, suggesting Pb incorporation into the structure of the oxides. EXAFS analysis revealed similar uptake mechanisms regardless of the specific nature of the phyllomanganate, electrolyte background, total Pb(II) loading, or equilibration time. One Pb-O and two Pb-Mn shells at distances of 2.30, 3.53, and 3.74 A, respectively, were found, as well as a linear relationship between Brunauer-Emmett-Teller (BET; i.e., external) specific surface area and maximum Pb(II) sorption that also encompassed data from previous work. Both observations support the existence of two bonding mechanisms in Pb(II) sorption: a triple-corner-sharing complex in the interlayers above/ below cationic sheet vacancies (N theoretical = 6), and a double-corner-sharing complex on particle edges at exposed singly coordinated -O(H) bonds (N theoretical = 2). General prevalence of external over internal sorption is predicted, but the two simultaneous sorption mechanisms can account for the widely noted high affinity of manganese oxides for Pb(ll) in natural environments.

Adsorption↗
PubMed2005

Evidence for biogenic pyromorphite formation by the nematode Caenorhabditis elegans.

The determination of chemical speciation and spatial distribution is a prerequisite for a mechanistic understanding of contaminant bioavailability and toxicity to an organism. We have employed synchrotron X-ray techniques to study Cu and Pb speciation and spatial distribution in the soil nematode Caenorhabditis elegans. Nematodes were exposed to each metal ion singly or simultaneously in solution for 24 h and were then rinsed thoroughly and preserved in formalin for transportation to the National Synchrotron Light Source. Experiments were conducted at the microprobe beamline X26A employing a focused beam of approximately 10 microm in diameter. Nematodes were mounted in agar gel on Kapton tape. Two-dimensional elemental maps for Cu- and Pb-exposed nematodes were collected in fluorescence mode. Copper was homogeneously distributed throughout the body of the nematode, but Pb exhibited a high degree of localization in the nematode, exclusively in the anterior pharynx region. Detectable localized concentrations of Pb in C. elegans occurred at aqueous exposure concentrations of 2.4 microM. Micro X-ray diffraction of these Pb hotspots gave a diffraction pattern indicating a crystalline Pb solid that was consistent with the Pb phosphate, pyromorphite. Biogenic inorganic phosphate granule formation is relatively common in soil invertebrates; however, these phosphates are typically amorphous, and we believe that this is the first report of crystalline pyromorphite formed internally in an organism.

Animals↗
PubMed2006

Determination of uranyl incorporation into biogenic manganese oxides using x-ray absorption spectroscopy and scattering.

Biogenic manganese oxides are common and an important source of reactive mineral surfaces in the environment that may be potentially enhanced in bioremediation cases to improve natural attenuation. Experiments were performed in which the uranyl ion, UO2(2+) (U(VI)), at various concentrations was present during manganese oxide biogenesis. At all concentrations, there was strong uptake of U onto the oxides. Synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray diffraction (XRD) studies were carried out to determine the molecular-scale mechanism by which uranyl is incorporated into the oxide and how this incorporation affects the resulting manganese oxide structure and mineralogy. The EXAFS experiments show that at low concentrations (<0.3 mol % U, <1 microM U(VI) in solution), U(VI) is present as a strong bidentate surface complex. At high concentrations (>2 mol % U, >4 microM U(VI) in solution), the presence of U(VI) affects the stability and structure of the Mn oxide to form poorly ordered Mn oxide tunnel structures, similar to todorokite. EXAFS modeling shows that uranyl is present in these oxides predominantly in the tunnels of the Mn oxide structure in a tridentate complex. Observations by XRD corroborate these results. Structural incorporation may lead to more stable U(VI) sequestration that may be suitable for remediation uses. These observations, combined with the very high uptake capacity of the Mn oxides, imply that Mn-oxidizing bacteria may significantly influence dissolved U(VI) concentrations in impacted waters via sorption and incorporation into Mn oxide biominerals.

Bacteria↗
PubMed2002

Sampling and monitoring of biogenic emissions by eucalyptus leaves using membrane extraction with sorbent interface (MESI).

Membrane extraction with sorbent interface (MESI) has been applied to monitor plant fragrance volatiles emitted into indoor air. The main components of the MESI system are a membrane module and a trap, which can be connected directly to a GC or GC-MS for simultaneous multicomponent extraction and monitoring. A polydimethylsiloxane (PDMS) membrane and two different traps, PDMS and Tenax, as well as a DC current supply for trap desorption have been applied in this research. After the membrane module is placed in contact with the plant, the MESI/GC-MS provides semicontinuous characterization of volatile compounds emitted. The MESI device has been applied to monitor the biogenic volatile organic compounds released during the first 8 h after a branch was cut from a Eucalyptus dunnii tree. The study demonstrates that the MESI system is a simple and useful tool for monitoring changes in emission processes as a function of time.

Chemistry Techniques, Analytical↗
PubMed1998

Biogenic catalysis of soil formation on Mars?

The high iron abundance and the weak ferric iron spectral features of martian surface material are consistent with nanophase (nm-sized) iron oxide minerals as a major source of iron in the bright region soil on Mars. Nanophase iron oxide minerals, such as ferrihydrite and schwertmannite, and nanophase forms of hematite and goethite are formed by both biotic and abiotic processes on Earth. The presence of these minerals on Mars does not indicate biological activity on Mars, but it does raise the possibility. This work includes speculation regarding the possibility of biogenic soils on Mars based on previous observations and analyses. A remote sensing goal of upcoming missions should be to determine if nanophase iron oxide minerals, clay silicates and carbonates are present in the martian surface material. These minerals are important indicators for exobiology and their presence on Mars would invoke a need for further investigation and sample return from these sites.

Catalysis↗
PubMed2000

Melanophore lineage and clonal organization of the epidermis in Xenopus embryos as revealed by expression of a biogenic marker, GFP.

Melanophore lineage during embryogenesis of Xenopus laevis was traced using the overexpression of a biogenic marker, green fluorescent protein (GFP). Two different approaches were applied after injection of GFP mRNA (hence a marker construct) into each blastomere at the 16-cell stage. In in vivo experiments, the embryos injected with a marker construct were grown until stage 45, in which melanophores were distributed over the whole body and were good enough for checking GFP expression at their migratory destination. In in vitro experiments, neural tubes of the embryos injected with a marker construct were isolated and cultured at stage 21 to examine by virtue of GFP expression how neural crest cells differentiate into melanophores. The results obtained from both in vivo and in vitro experiments indicated the following: 1) selected animal blastomeres vastly contribute to the development of melanophores, whereas other animal blastomeres do so slightly at a limited pace; and 2) vegetal blastomeres never contribute to melanophores in normal development, whereas certain vegetal blastomeres have a potential to give rise to melanophores in vitro. The analyses using GFP also disclosed that the dorsal and ventral epidermis derive from the restricted animal blastomeres in the normal development. Since the dorso-ventrality of the epidermis has been inseparably coupled with integumental pigmentation, the clonal organization of the epidermis observed in the present study is discussed in the light of pigment pattern formation attributed by melanophores.

Animals↗
PubMed2002

Marine aerosol formation from biogenic iodine emissions.

The formation of marine aerosols and cloud condensation nuclei--from which marine clouds originate--depends ultimately on the availability of new, nanometre-scale particles in the marine boundary layer. Because marine aerosols and clouds scatter incoming radiation and contribute a cooling effect to the Earth's radiation budget, new particle production is important in climate regulation. It has been suggested that sulphuric acid derived from the oxidation of dimethyl sulphide is responsible for the production of marine aerosols and cloud condensation nuclei. It was accordingly proposed that algae producing dimethyl sulphide play a role in climate regulation, but this has been difficult to prove and, consequently, the processes controlling marine particle formation remains largely undetermined. Here, using smog chamber experiments under coastal atmospheric conditions, we demonstrate that new particles can form from condensable iodine-containing vapours, which are the photolysis products of biogenic iodocarbons emitted from marine algae. Moreover, we illustrate, using aerosol formation models, that concentrations of condensable iodine-containing vapours over the open ocean are sufficient to influence marine particle formation. We suggest therefore that marine iodocarbon emissions have a potentially significant effect on global radiative forcing.

Aerosols↗
PubMed1994

Spectroscopic evaluation of interactions among trace elements and biogenic carbonates in the marine environment.

The interactions between trace elements and biogenic carbonates (marine mussel shells) in aqueous media were evaluated. The behaviour of Mn, Cu, Co, and Cd was investigated using spectrometric techniques (electrothermal atomic absorption, inductively coupled plasma atomic emission and electron paramagnetic resonance). The results obtained show that the metals considered do not form a distinct precipitated phase on the shell surfaces, but that they interact with the CaCO3. This study aimed to provide more information on the mechanisms involved in the storage of trace elements by the shells of marine bivalves. This would allow the use of mussel shells as an alternative to soft tissues for trace metal analyses in biological monitoring programmes.

Animals↗
PubMed2003

Determination of the amino acid tryptophan and the biogenic amine tryptamine in foods by the heavy atom induced-room temperature phosphorescence methodology.

Very simple and selective methods are presented to determine the amino acid tryptophan (Trp) and the biogenic amine tryptamine (Tryp), both compounds with an indole-type molecular structure by the methodology named Heavy Atom Induced-Room Temperature Phosphorescence (HAI-RTP) which constitutes the first time that HAI-RTP has been used to detect compounds with non-naphthalenic structures in their molecules. Different variables affecting the phosphorescence signal (heavy atom perturber and sodium sulfite concentration) were carefully studied. The analytical curves give a linear dynamic range of 15-100 ng ml(-1) and a detection limit of 4 ng ml(-1) for Trp and 94-400 ng ml(-1) and 28 ng ml(-1) for Tryp. The methods have been successfully applied to the analysis of complex food matrices such as the presence of tryptophan in yoghurt and tryptamine in bottled beer. A single alkaline hydrolysis to release Trp from yoghurt proteins and two methods for extracting Tryp from beer samples are proposed and optimised. A total Trp content of 374 mg of Trp per kg of yoghurt was quantified by the standard addition method of calibration and a recovery of 90% was obtained for 250 ng ml(-1) of Tryp in spiked non-alcoholic beer samples.

Beer↗
PubMed2003

Airborne observations of vegetation and implications for biogenic emission characterization.

Measuring hydrocarbons from aircraft represents one way to infer biogenic emissions at the surface. The focus of this paper is to show that complementary remote sensing information can be provided by optical measurements of a vegetation index, which is readily measured with high temporal coverage using reflectance data. We examine the similarities between the vegetation index and in situ measurements of the chemicals isoprene, methacrolein, and alpha-pinene to estimate whether the temporal behavior of the in situ measurements of these chemicals could be better understood by the addition of the vegetation index. Data were compared for flights conducted around Houston in August and September 2000. The three independent sets of chemical measurements examined correspond reasonably well with the vegetation index curves for the majority of flight days. While low values of the vegetation index always correspond to low values of the in situ chemical measurements, high values of the index correspond to both high and low values of the chemical measurements. In this sense it represents an upper limit when compared with in situ data (assuming the calibration constant is adequately chosen). This result suggests that while the vegetation index cannot represent a purely predictive quantity for the in situ measurements, it represents a complementary measurement that can be useful in understanding comparisons of various in situ observations, particularly when these observations occur with relatively low temporal frequency. In situ isoprene measurements and the vegetation index were also compared to an isoprene emission inventory to provide additional insight on broad issues relating to the use of vegetation indices in emission database development.

Aircraft↗