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At least 901 records · Page 50Linked to original sources
PubMed2003

On-site monitoring of biogenic emissions from Eucalyptus dunnii leaves using membrane extraction with sorbent interface combined with a portable gas chromatograph system.

Membrane extraction with sorbent interface, combined with a portable gas chromatograph system (MESI-Portable GC) for continuous on-line monitoring of biogenic volatile organic compounds (BVOCs) emissions (from leaves of Eucalytus dunnii in a greenhouse), is presented herein. A sampling chamber was designed to facilitate the extraction and identification of the BVOCs emitted by the Eucalytus dunnii leaves. Preliminary experiments, including; enrichment times, microtrap temperatures, stripping gas flow rates, and desorption temperatures were investigated to optimize experimental parameters. The main components of BVOCs released by the Eucalytus dunnii leaves were identified by comparing the retention times of peaks with those of authentic standard solutions. They were then confirmed with solid phase microextraction coupled with gas chromatography and mass spectrometry (SPME-GC-MS). BVOC emission profiles of [small alpha]-pinene, eucalyptol, and [gamma]-terpinene emitted by intact and damaged Eucalytus dunnii leaves were obtained. The findings suggest that the MESI-Portable GC system is a simple and useful tool for field monitoring changes in plant emissions as a function of time.

Chromatography, Gas↗
PubMed2005

Secondary organic aerosols from anthropogenic and biogenic precursors.

Secondary organic aerosol (SOA) formation from the photooxidation of an anthropogenic (1,3,5-trimethylbenzene) and a biogenic (alpha-pinene) precursor was investigated at the new PSI smog chamber. The chemistry of the gas phase was followed by proton transfer reaction mass spectrometry, while the aerosol chemistry was investigated with aerosol mass spectrometry, ion chromatography, laser desorption ionization mass spectrometry, and infrared spectroscopy, along with volatility and hygroscopicity studies. Evidence for oligomer formation for SOA from both precursors was given by an increasing abundance of compounds with a high molecular weight (up to 1000 Da) and by an increasing thermal stability with increasing aging time. The results were compared to data obtained from ambient aerosol samples, revealing a number of similar features.

Aerosols↗
PubMed1987

Plasma biogenic amine levels in agoraphobia with panic attacks.

Eight patients with agoraphobia and panic attacks as defined by DSMIII and 11 controls were included in this study which measured the circulating biogenic amine levels. The method of assay used a high performance liquid chromatograph with electrochemical detection. Measurement of dopamine, noradrenaline and adrenaline showed no differences between the groups. Levels of serotonin (5-HT) were significantly lower in the agoraphobic group. The authors discuss the implication of this finding.

Adult↗
PubMed1979

A simple procedure for the assay of brain biogenic amines by selected-ion monitoring: its application to the elucidation of the mechanism of prolactin release induced by 3-iodo-L-tyrosine.

A simple method for the assay of brain biogenic amines by selected-ion monitoring was applied to examination of the effects of 3-iodo-L-tyrosine on the hypothalamic-median eminence concentrations of dopamine, noradrenaline and serotonin in the rat. Thirty minutes after its administration iodotyrosine (50 mg/kg) caused a highly significant (P less than 0.0005) rise in serum prolactin and a highly significant (P less than 0.0025) fall in the concentration of dopamine in the hypothalamus and median eminence where the levels reached 50% of control levels. Less marked but significant falls were also observed in the hypothalamic (P less than 0.05) and median eminence (P less than 0.0025) concentrations of noradrenaline after iodotyrosine administration. Serotonin concentration was significantly reduced (P less than 0.025) in the median eminence but not in the hypothalamus after iodotyrosine administration. These findings suggest that iodotyrosine exerts its prolactin stimulating effect by blockage of dopamine synthesis rather than by receptor blockade.

Animals↗
PubMed2002

Origin of supposedly biogenic magnetite in the Martian meteorite Allan Hills 84001.

Crystals of magnetite (Fe(3)O(4)) and periclase (MgO) in Fe-Mg-Ca carbonate in the Martian meteorite Allan Hills 84001 were studied by using transmission electron microscopy to understand their origin and evaluate claims that the magnetites were made by Martian microorganisms. In magnesian carbonate, periclase occurs as aggregates of crystals (grain size approximately equal to 3 nm) that are preferentially oriented with respect to the carbonate lattice. Larger periclase crystals approximately equal to 50 nm in size are commonly associated with voids of similar size. Periclase clearly formed by precipitation from carbonate as a result of partial decomposition and loss of CO(2). Magnetite occurs in more ferroan carbonate, and, like periclase, it is associated with voids and microfractures and the two oxides may be intermixed. Magnetite nanocrystals that are commonly euhedral and entirely embedded in carbonate are topotactically oriented with respect to the carbonate lattice, showing that they formed as solid-state precipitates. Magnetites in Fe-rich carbonate rims are not well oriented. These magnetites are generally more irregular in shape and diverse in size than the euhedral variety. All occurrences of magnetite and periclase are entirely consistent with in situ growth by solid-state diffusion as a result of carbonate decomposition during impact heating. Biogenic sources should not be invoked for any magnetites.

Journal Article↗
PubMed1975

Interaction of glyoxal and methylglyoxal with biogenic amines.

Glyoxal and methylglyoxal interact with biogenic amines and form biologically active free radicals. Electron spin resonance absorption of the radical at room temperature is characterized by a signal at g equals 2.004 with peak-to-peak width of 29 G. An optical absorption at 400 nm with molar absorptivity of 23,000 accompanies the formation of the radical. The dry powdered preparation of the same reaction, which is considered to be the seconardy product, gives an electron spin resonance signal much narrower and 1/200 in intensity compared with the one in solution. Similarly the 400 nm absorption intensity is 1/8 that of the primary product. Possible biological significance of the primary and the secondary product, in relation to muscular dystrophy and photophosphorylation, is discussed.

Aldehydes↗
PubMed1976

Biogenic amines in the Caenorhabditis briggsae.

Dopamine, epinephrine, norepinephrine and serotonin were demonstrated from homogenates of Caenrohabditis briggsae by two-dimensional thin layer chromotography and the identification confirmed by gas liquid chromtography. In Vitro studies with 14C precursors of these biogenic amines demonstrate the ability of C. briggsae to synthesize each compound. The results provide required preliminary data for studying the neurophysiology of aging utilizing the nematode as a model.

Aging↗
PubMed1987

In vitro LH release from the hypothalamus-pars tuberalis; effects of gonadotropin-releasing hormone (GnRH), beta-endorphin and biogenic amines.

Immunoreactive and bioactive luteinizing hormone (LH) has been shown to be widely distributed in the rodent central nervous system (CNS), particularly in the hypothalamus. Subcellular localization of this LH in fractions rich in synaptosomes and in vitro release by potassium-induced depolarization suggests that this peptide may act in trans-synaptic neuromodulatory roles. Furthermore, a variety of experiments have proved that this brain-based LH is not of pituitary origin. In the in vitro studies reported here characterization of brain-based LH release, in response to gonadotropin-releasing hormone (GnRH), beta-endorphin, and biogenic amines, was examined. Adult male rats were sacrificed by decapitation, hypothalami removed, quartered, and incubated in Krebs Ringer's Bicarbonate (KRB). High potassium concentration and GnRH induced release of LH from these hypothalamic explants in short-term culture and serotonin significantly inhibited release of LH from these explants. In contrast, however, beta-endorphin, norepinephrine, dopamine, and acetylcholine, agents known to modulate pituitary LH release, had no effect on the release of LH from hypothalamic tissues in vitro. Furthermore, beta-endorphin did not alter potassium-induced release of LH from the hypothalamus. Whereas there are some similarities between LH release from the pituitary and from the CNS, the differences reported here suggest that hypothalamic LH does not simply serve as a supplemental source for LH in the general circulation but more likely subserves an entirely different role(s) than its pituitary counterpart, presumably acting in a neuromodulatory fashion within the brain.

Animals↗
PubMed2000

Integrating remote sensing and local vegetation information for a high-resolution biogenic emissions inventory--application to an urbanized, semiarid region.

This paper presents a methodology for the development of a high-resolution (30-m), standardized biogenic volatile organic compound (BVOC) emissions inventory and a subsequent application of the methodology to Tucson, AZ. The region's heterogeneous vegetation cover cannot be modeled accurately with low-resolution (e.g., 1-km) land cover and vegetation information. Instead, local vegetation data are used in conjunction with multispectral satellite data to generate a detailed vegetation-based land-cover database of the region. A high-resolution emissions inventory is assembled by associating the vegetation data with appropriate emissions factors. The inventory reveals a substantial variation in BVOC emissions across the region, resulting from the region's diversity of both native and exotic vegetation. The importance of BVOC emissions from forest lands, desert lands, and the urban forest changes according to regional, metropolitan, and urban scales. Within the entire Tucson region, the average isoprene, monoterpene, and OVOC fluxes observed were 454, 248, and 91 micrograms/m2/hr, respectively, with forest and desert lands emitting nearly all of the BVOCs. Within the metropolitan area, which does not include the forest lands, the average fluxes were 323, 181, and 70 micrograms/m2/hr, respectively. Within the urban area, the average fluxes were 801, 100, and 100 micrograms/m2/hr, respectively, with exotic trees such as eucalyptus, pine, and palm emitting most of the urban BVOCs. The methods presented in this paper can be modified to create detailed, standardized BVOC emissions inventories for other regions, especially those with spatially complex vegetation patterns.

Air Pollution↗
PubMed2004

Design scenario for the radioisotopic estimation of the biogenic component of airborne particles.

An experimental design is described to estimate the fraction of secondary fine particle from the biogenic component of volatile organic compounds (VOCs) in the atmosphere using radiocarbon isotopic abundance ratios. The method distinguishes between "modern" carbon (C), and "old" C of primary and secondary origins based on three components, condensed-phase organic carbon (OC), semi-volatile particulate compounds (SVOCs), and VOCs. The method depends on interpretation of diurnal and seasonal variation in OC, SVOC, and VOC concentrations. Sampling employs a filter-denuder unit, which collects the three C components for isotopic analysis. The samples are collected repetitively for a daily sequence of the same hourly intervals covering diurnal periods with similar meteorological conditions. Collected C is thermally treated to separate OC from black carbon on filters and VOCs or SVOCs from adsorbents, with all four fractions individually oxidized to carbon dioxide to determine the radiocarbon content by accelerator mass spectrometry. Using C isotope abundance, the data are interpreted for fractions of primary modern C and secondary modern C as estimated from averaging diurnal and seasonal variations in the concentration data. As support for interpretation, samples of OC, SVOCs, and VOCs would be analyzed for speciation to identify source indicator species present.

Air Pollutants↗
PubMed2004

A foldable CFTR{Delta}F508 biogenic intermediate accumulates upon inhibition of the Hsc70-CHIP E3 ubiquitin ligase.

CFTRDeltaF508 exhibits a correctable protein-folding defect that leads to its misfolding and premature degradation, which is the cause of cystic fibrosis (CF). Herein we report on the characterization of the CFTRDeltaF508 biogenic intermediate that is selected for proteasomal degradation and identification of cellular components that polyubiquitinate CFTRDeltaF508. Nonubiquitinated CFTRDeltaF508 accumulates in a kinetically trapped, but folding competent conformation, that is maintained in a soluble state by cytosolic Hsc70. Ubiquitination of Hsc70-bound CFTRDeltaF508 requires CHIP, a U box containing cytosolic cochaperone. CHIP is demonstrated to function as a scaffold that nucleates the formation of a multisubunit E3 ubiquitin ligase whose reconstituted activity toward CFTR is dependent upon Hdj2, Hsc70, and the E2 UbcH5a. Inactivation of the Hsc70-CHIP E3 leads CFTRDeltaF508 to accumulate in a nonaggregated state, which upon lowering of cell growth temperatures, can fold and reach the cell surface. Inhibition of CFTRDeltaF508 ubiquitination can increase its cell surface expression and may provide an approach to treat CF.

Animals↗
PubMed2003

Lossless compression of stromatolite images: a biogenicity index?

It has been underappreciated that inorganic processes can produce stromatolites (laminated macroscopic constructions commonly attreibuted to microbiological activity), thus calling into question the long-standing use of stromatolites as de facto evidence for ancient life. Using lossless compression on unmagnified reflectance red-green-blue (RGB) images of matched stromatolite-sediment matrix pairs as a complexity metric, the compressibility index (delta(c), the log ratio of the ratio of the compressibility of the matrix versus the target) of a putative abiotic test stromatolite is significantly less than the delta(c) of a putative biotic test stromatolite. There is a clear separation in delta(c) between the different stromatolites discernible at the outcrop scale. In terms of absolute compressibility, the sediment matrix between the stromatolite columns was low in both cases, the putative abiotic stromatolite was similar to the intracolumnar sediment, and the putative biotic stromatolite was much greater (again discernible at the outcrop scale). We propose tht this metric would be useful for evaluating the biogenicity of images obtained by the camera systems available on every Mars surface probe launched to date including Viking, Pathfinder, Beagle, and the two Mars Exploration Rovers.

Algorithms↗
PubMed2005

Raman imagery: a new approach to assess the geochemical maturity and biogenicity of permineralized precambrian fossils.

Laser-Raman imagery is a non-intrusive, non-destructive analytical technique, recently introduced to Precambrian paleobiology, that can be used to demonstrate a one-to-one spatial correlation between the optically discernible morphology and kerogenous composition of permineralized fossil microorganisms. Made possible by the submicron-scale resolution of the technique and its high sensitivity to the Raman signal of carbonaceous matter, such analyses can be used to determine the chemical-structural characteristics of organic-walled microfossils and associated sapropelic carbonaceous matter in acid-resistant residues and petrographic thin sections. Here we use this technique to analyze kerogenous microscopic fossils and associated carbonaceous sapropel permineralized in 22 unmetamorphosed or little-metamorphosed fine-grained chert units ranging from approximately 400 to approximately 2,100 Ma old. The lineshapes of the Raman spectra acquired vary systematically with five indices of organic geochemical maturation: (1) the mineral-based metamorphic grade of the fossil-bearing units; (2) the fidelity of preservation of the fossils studied; (3) the color of the organic matter analyzed; and both the (4) H/C and (5) N/C ratios measured in particulate kerogens isolated from bulk samples of the fossil-bearing cherts. Deconvolution of relevant spectra shows that those of relatively well-preserved permineralized kerogens analyzed in situ exhibit a distinctive set of Raman bands that are identifiable also in hydrated organic-walled microfossils and particulate carbonaceous matter freed from the cherts by acid maceration. These distinctive Raman bands, however, become indeterminate upon dehydration of such specimens. To compare quantitatively the variations observed among the spectra measured, we introduce the Raman Index of Preservation, an approximate measure of the geochemical maturity of the kerogens studied that is consistent both with the five indices of organic geochemical alteration and with spectra acquired from fossils experimentally heated under controlled laboratory conditions. The results reported provide new insight into the chemical-structural characteristics of ancient carbonaceous matter, the physicochemical changes that accompany organic geochemical maturation, and a new criterion to be added to the suite of evidence by which to evaluate the origin of minute fossil-like objects of possible but uncertain biogenicity.

Animals↗
PubMed1976

Nonfunctioning argyrophilic tumor (APUDoma) of the hepatic duct: simplified methods of detecting biogenic amines in tissue.

This report documents a foregut endocrine neoplasm in an unusual location, the main hepatic bile duct, and describes simplified methods of detecting similar endocrine tumors. Formaldehyde fume-induced fluorescence (FIF) is a quick, specific method to demonstrate biogenic amines. FIF combined with histochemical procedures showing abundant alpha-glycerol phosphate dehydrogenase and esterases indicates the neural crest origin of these and related neoplasms. Amine precursor uptake and decarboxylation (APUD) is a significant marker of these cells and gives them their name.

Adult↗
PubMed1992

Induction of epidermal ornithine decarboxylase activity in mouse skin exposed to biogenic silica fibers.

The present study demonstrates that biogenic silica fibers (BSF), previously shown to promote skin tumors in mice and more recently to promote the induction of mesotheliomas when injected into the pleural cavity of rats, rapidly induces epidermal ornithine decarboxylase (ODC) activity in SENCAR mice following topical application. The time course for induction of epidermal ODC by BSF was very similar to that observed following topical treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). Maximal ODC activity was observed 4-6 h following treatment with BSF. Cycloheximide (70 mg/kg i.p.) partially inhibited (61%) the induction of ODC by BSF at 5 h. In addition, retinoic acid (RA, 5 micrograms per mouse given 30 min before BSF) effectively inhibited BSF-induced ODC by 68%, while indomethacin (100 micrograms per mouse 2 h before BSF) had little or no effect. Copper(II) bis(diisopropylsalicylate) (2 mumol 30 min before BSF), an effective inhibitor of TPA-induced ODC activity and tumor promotion, also had little or no effect on BSF-induced ODC. The work described in this paper suggests that BSF induces epidermal ODC by a very specific mechanism that exhibits both similarities and differences with that of the phorbol ester, TPA. Nevertheless, this response strongly supports the conclusion that BSF is an effective tumor promoter in mouse skin and that ODC induction is an integral part of the mechanism of action of this environmental promoter.

Animals↗
PubMed2002

Chiral analysis of biogenic D,L-amino acids derivatized by N-fluorenylmethoxycarbonyl-L-alanyl N-carboxyanhydride using high-performance liquid chromatography.

Nineteen biogenic D,L-amino acids are derivatized with highly reactive N-fluorenylmethoxycarbonyl-L-alanyl N-carboxyanhydride. Using a 0.5M borate buffer at pH 7.5 and acetone, the derivatization of amino acids is completed in 5 min at room temperature. Some of the resulting diastereomeric N-protected dipeptides are successfully separated on an octylsilica stationary phase using 100mM acetate buffer (pH 4.4) and acetonitrile as the eluent.

Amino Acids↗
PubMed1993

Relation between blood lead and urinary biogenic amines in community-exposed men.

The cross-sectional relation between levels of urinary biogenic amines (dopamine, epinephrine, norepinephrine, and serotonin) and levels of blood lead was examined in a study of 645 male participants from a longitudinal study of aging. This stable population of men had initially been recruited from communities in and around Boston, Massachusetts, and had not been selected with regard to lead exposure. Blood lead samples and 24-hour and 2-hour urine specimens were collected during regularly scheduled clinic visits. In multivariate linear regression step-forward models, 24-hour epinephrine excretion was significantly and positively associated with blood lead (beta = 0.101 microgram(microgram/dl)-1 blood lead, SE (standard error) (beta) = 0.045, p = 0.026). Twenty-four-hour norepinephrine excretion was positively associated with blood lead (beta = 0.023 microgram(microgram/dl)-1 blood lead, SE(beta) = 0.029, p = 0.425), and both 24-hour dopamine (beta = -4.35 microgram(microgram/dl)-1 blood lead, SE(beta) = 6.90, p = 0.529) and 2-hour serotonin (beta = -0.348 microgram(microgram/dl)-1 blood lead, SE(beta) = 0.277, p = 0.210) excretion were negatively associated with blood lead; however, these relations did not achieve statistical significance. An increase of 10 micrograms/dl in blood lead was associated with an increase in epinephrine excretion of 11 micrograms/24 hours. These results support the hypothesis that epinephrine metabolism is influenced by low levels of lead exposure.

Adult↗
PubMed2005

Toll-like receptor 4 mediates mitochondrial DNA damage and biogenic responses after heat-inactivated E. coli.

An important site of cellular damage in bacterial sepsis is mitochondrial DNA (mtDNA), which we proposed is caused by reactive oxygen and nitrogen species generated by activation of signaling through specific toll-like receptors (TLR). In wild-type (Wt) mice injected with heat-inactivated E. coli, hepatic TLR4 and TLR2 proteins were up-regulated with TLR-dependent increases in transcript levels for tumor necrosis factor (TNF-alpha), interleukin 6, nitric oxide synthase-II (iNOS), and NADPH oxidase 2 (Nox2). The accompanying stress significantly depleted hepatic mtDNA despite eight- and fourfold increases in manganese superoxide dismutase (MnSOD) and mitochondrial transcription factor A (Tfam) expression, respectively. The identical E. coli dose generated significantly less TNF-alpha, NO, and Nox2 in TLR4-/- and TLR2/4-/- but not in TLR2-/- mice. TLR4-/- and TLR2/4-/- compared with Wt mice were protected from mtDNA oxidation but showed no Tfam up-regulation and little copy number restoration. A critical role in the mtDNA damage was determined for TLR4-mediated iNOS transcription through the MyD88 pathway. In Wt mice, mtDNA depletion was avoided by selective iNOS blockade, and residual mtDNA loss was linked to NF-kappaB-dependent TNF-alpha expression. These data disclose the dual role of TLR4 in mtDNA damage and compensatory mitochondrial biogenic responses after innate immune activation.

Adaptor Proteins, Signal Transducing↗