Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Environmental matrix”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2005

Toxicogenomic profile of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the murine fetal heart: modulation of cell cycle and extracellular matrix genes.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and similar environmental contaminants have been demonstrated to be potent cardiovascular teratogens in developing piscine and avian species. In the present study, we investigated the effects of TCDD on gene expression during murine cardiovascular development. C57Bl6N pregnant mice were dosed with 1.5, 3.0, or 6.0 microg TCDD/kg on gestational day (GD) 14.5, and microarray analysis was used to characterize the global changes in fetal cardiac gene expression on GD 17.5. TCDD significantly altered expression of a number of genes involved in xenobiotic metabolism, cardiac homeostasis, extracellular matrix production/remodeling, and cell cycle regulation. Interestingly, while the AhR-responsive genes Cyp1A1, Cyp1B1, Ugt1a6, and Ahrr, were all induced by TCDD in the fetal murine heart, other AhR-responsive genes, Cyp1a2, Nqo1, and Gsta1, were not. Quantitative real-time polymerase chain reactions confirmed the changes in expression of several G1/S-type cyclins and extracellular matrix-related genes. These results demonstrate the global changes in cardiac gene expression that result from TCDD exposure of the fetal murine heart and implicate genes involved in cell cycle and extracellular matrix regulation in TCDD-induced cardiac teratogenicity and functional deficits.

Animals↗
PubMed1993

Disruption and fractionation of biological materials by matrix solid-phase dispersion.

The isolation of drug residues, environmental contaminants or naturally occurring component molecules from biological materials is often a complex undertaking. We report here the development and application of a simple approach to the disruption of biological samples that also allows for the rapid fractionation and isolation of the sample's natural components or incurred residues. This process, called matrix solid-phase dispersion (MSPD), combines the use of mechanical forces generated from the grinding of samples with irregular shaped particles (silica or polymer based solid supports) with the lipid solubilizing capacity of a support-bound polymer (octadecylsilyl or others) to produce a sample column material from which dispersed sample matrix components can be selectively isolated. The factors governing this process and examples of its various applications are presented.

Animals↗
PubMed1996

Development of chicken embryos exposed to an intermittent horizontal sinusoidal 50 Hz magnetic field.

The effects of intermittent exposure (2 h on/22 h off) to a 200 microT horizontal, sinusoidally oscillating (50 Hz) magnetic field were studied in 210 fertilized chicken eggs. Two hundred ten control eggs (sham-exposed) were incubated in the same chamber as the experimental eggs. Chick embryos were examined for developmental anomalies and maturity stage after 48 h of incubation. Immunohistochemical analysis of extracellular membrane components (laminin, fibronectin, and type IV collagen) were conducted on day 7 and histological examinations for malformations of brain, liver, and heart, on days 7, 12, and 18 of incubation. Furthermore, egg fertility and egg weights were evaluated on days 2, 7, 12, and 18. The investigation also measured the body weight of chickens for 90 days from hatching and included histological analysis of body organs. Each variable was investigated blind. Statistical comparison between exposed and sham-exposed values did not show significant differences in any of the variables investigated. Thus, it appears that the exposure of embryos to an intermittent 200 microT magnetic field at 50 Hz does not cause developmental anomalies, changes in maturity stage, alterations in distribution of extracellular membrane components, or malformations in the brain, liver, or heart. Moreover, there were no differences in body weight, morphology, or histology of central nervous system, liver, heart, or testis in 90-day-old chickens hatched from exposed in comparison to sham-exposed eggs.

Animals↗
PubMed1998

Influence of hydration status and fluid replacement on heat tolerance while wearing NBC protective clothing.

The purpose of the present study was to investigate the influence of hypohydration and fluid replacement on tolerance to an uncompensable heat stress. Eight healthy young males completed a matrix of six trials in an environmental chamber, set at 40 degrees C and 30% relative humidity, while wearing nuclear, biological, and chemical protective clothing. Subjects performed either light (3.5 km x h(-1), 0% grade, no wind) or heavy (4.8 km x h(-1), 4% grade, no wind) treadmill exercise combined with three hydration states [euhydration with fluid replacement (EU/F), euhydration without fluid replacement (EU/NF), and hypohydration with fluid replacement (H/F)]. Hypohydration of 2.2% body mass was achieved by exercise and fluid restriction on the day preceding the trials. No differences in the endpoint mean skin temperature (Tsk), sweat rate, or rectal temperature (Tre) were observed among the hydration conditions for either work rate. During light exercise, the change in Tre (deltaTre) was significantly higher with H/F than EU/F after 40 min, and heart rate was greater after 25 min. The heart rate was greater during EU/NF than during EU/F after 60 min. Tolerance times were significantly greater for EU/F than for either EU/NF or H/F. With heavy exercise, no differences in deltaTre were observed across hydration conditions. Compared to EU/F, heart rates were higher after 10 and 30 min for H/F and EU/NF, respectively. Tolerance times were significantly less during H/F than with either of the EU conditions. Stroke volume was significantly decreased in H/F trials compared to EU/F trials for both light and heavy work rates, but no differences in cardiac output were observed. It was concluded that even minor levels of hypohydration significantly impaired exercise tolerance in a severely uncompensable heat stress environment at both light and heavy exercise intensities.

Adult↗
PubMed1990

Development of poly(ortho esters): a historical overview.

At the present time, three poly(ortho ester) systems have been described. The first one was developed at the Alza Corporation and is prepared by the transesterification reaction between a diol and diethoxytetrahydrofuran. It is currently marketed under the trade name of Alzamer. A second poly(ortho ester) system, developed at SRI International, is prepared by the addition of polyols to the diketene acetal 3,9 bis (ethylidene 2,4,8,10 tetraoxaspiro [5,5] undecane). A third poly (ortho ester) system, also developed at SRI International, is prepared by a transesterification reaction between a triol and an ortho ester, followed by self-condensation of the reaction product. Major utility of poly(ortho esters) as bioerodible drug delivery devices resides in their acid sensitivity which allows preparation of devices with lifetimes ranging from hours to many months by using acidic or basic excipients physically incorporated into the matrix.

Biodegradation, Environmental↗
PubMed1991

Connective tissue polypeptides in serum as parameters to monitor antifibrotic treatment in hepatic fibrogenesis.

With the potential to specifically inhibit hepatic collagen synthesis a demand for serum tests to monitor the effectiveness of such treatment is expected. Serum assays for connective tissue polypeptides offer the potential to assess the dynamics of accumulation, i.e., fibrogenesis, and removal, i.e., fibrolysis, of the hepatic connective tissue on a regular and frequent basis. Several assays for circulating connective tissue polypeptides may be of use in fibrogenic liver diseases. Whereas an increase of the aminoterminal propeptide of type III procollagen (PIIINP) appears to be related to fibrogenesis, the propeptides of type IV procollagen (PIVNP, PIVCP) and laminin mirror enhanced basement membrane turnover in active fibrosis. Collagen type VI (CVI) and undulin (Un) rather reflect fibrolysis and remodelling of the interstitial connective tissue. Although the circulating antigens measured by these assays are heterogeneous, which often complicates the interpretation of elevated serum levels, it is likely that firm conclusions can be drawn as to the ongoing fibrogenesis, fibrolysis or both, once individual patients are followed with a combined measurement of two or three of these connective tissue parameters. Since 'easy to perform' assays are currently developed, such as therapy control seems practicable.

Biomarkers↗
PubMed2006

Sun exposure related methylation in malignant and non-malignant skin lesions.

We investigated the aberrant promoter methylation status of 12 genes in skin lesions, both malignant (basal cell carcinomas (BCCs), n=68 and squamous cell carcinomas (SCCs), n=35) and non-malignant (tags, n=58) skin lesions and compared the results of lesions from sun exposed (SE) and sun protected (SP) regions. Methylation was studied using a methylation specific PCR (MSP) and methylation of CDH1 was also measured using a semi-quantitative fluorescence based real-time MSP method. The methylation index (MI) was calculated as the methylated fraction of the genes examined. In this report, we found high frequencies of methylation of several known or suspected tumor suppressor genes in tags and skin cancers. Among the 12 genes, for the cadherin genes CDH1 and CDH3 and for two of the laminin 5 encoding genes LAMA3 and LAMC2 methylation frequencies greater than 30% were noted in one or more specimen types. We investigated whether methylation was tumor related. Surprisingly, the differences in the methylation profile of genes among the three specimen types were modest, and the MI, indicators of overall methylation frequencies, was nearly identical. However, significant differences were noted in the frequencies of methylation among the three specimen types for the genes RASSF1A (P=0.002), CDH1 (P=0.007) and one or more of three CAD genes (P=0.02). Methylation was highly significantly related to sun exposure, and sun protected specimens had little or no methylation. As methylation of CDH1 was completely SE specific we analyzed all the skin samples using a semi-quantitative real-time PCR assay for the CDH1 gene. The concordance between standard MSP and real-time MSP for all the samples (n=161) was 75% (P<0.0001). While weak signals were detected in the SP samples by real time PCR, the differences between SE and SP specimens were 148 fold for tags and 390 fold for BCCs. These differences were highly significant (P<0.0001). These findings suggest that methylation commences in UV exposed skin at a relatively early age and occurs in skin prior to the onset of recognizable preneoplastic changes.

Aged↗
PubMed2005

Plant-based material, protein and biodegradable plastic.

Fibrous proteins from spiders, proteins with synthetic multiple repeats and mammalian structural proteins such as collagen have been produced in transgenic plants. Recent advances in the production of biodegradable plastic in plants also show the potential of molecular farming for research into and production of materials. Selection of a growing variety of such products, optimization of expression, and the development of effective purification strategies will further promote this growing field of biotechnology.

Animals↗
PubMed2000

Determination of trace cadmium in environmental water samples using ion-interaction reversed-phase liquid chromatography with fluorescence detection.

An ion-interaction reversed-phase liquid chromatographic method has been developed for the determination of cadmium at low microg/l concentrations in environmental water samples. Cadmium and other matrix metals were separated through on-column complexation with 8-hydroxyquinoline sulphonate, using an octadecylsilica column and a mobile phase containing 15% acetonitrile, 10-13 mM tetrabutylammonium hydroxide, 5 mM 8-hydroxyquinoline 5-sulphonic acid and 10 mM acetic acid-acetate buffer (pH 4.8-5.4). Under the above conditions Cd(II) could be easily resolved from excess concentrations of matrix metals and could be detected at concentrations as low as 2 microg/l using fluorescence detection at 500 nm (based upon a 100-microl injection). The method showed a slightly curved detector response over the range of interest [up to 1 mg/l Cd(II)] and was successfully applied to the determination of trace Cd(II) in water samples containing large excesses of Mg(II) and Zn(II) and other matrix metals.

Cadmium↗
PubMed2001

Aluminum exposure: a study of an effect on cellular growth rate.

Aluminum effects on cultured human brain cells were examined. Human brain cells (neuroblastoma IMR-32) were cultured to examine possible effects of soluble aluminum at a cellular level. The cellular growth rate was measured by counting the number of cells with a hemocytometer under an optical microscope over a period of time. No significant change in cell growth was found during a three-week exposure period to aluminum at concentrations from 0.1 to 10 mg/l. However, after 3 weeks Al started to reduce the growth rate relative to the control, and the decrease became more pronounced as the exposure period to aluminum increased. The effect was greatest at the higher Al-concentration.

Aluminum↗
PubMed2000

Phosphorylation of microtubule-associated protein 2 (MAP2) and its relevance for the regulation of the neuronal cytoskeleton function.

Neurons, the basic information processing units of the nervous system, are characterized by a complex polar morphology which is essential for their function. To attain their precise morphology, neurons extend cytoplasmatic processes (axons and dendrites) and establish synaptic connections in a highly regulated way. Additionally, neurons are also subjected to small plastic changes at the adult stage which serve to regulate synaptic transmission. Every step of neuronal development is genetically controlled by endogenous determinants, as well as by environmental signals including intercellular contacts, extracellular matrix and diffusible signals. Cytoskeletal components are among the main protein targets modified in response to most of those extracellular signals which ultimately determine neuronal morphology. One of the major mechanisms controlling the neuronal cytoskeleton is the modification of the phosphorylation state of cytoskeletal proteins via changes in the relative activities of protein kinases and phosphatases within neurons. In particular, the microtubule-associated protein 2 (MAP2) family of proteins is an abundant group of cytoskeletal components which are predominantly expressed in neurons and serve as substrates for most of protein kinases and phosphatases present in neurons. MAP2 phosphorylation seems to control its association with the cytoskeleton and it is developmentally regulated. Moreover, MAP2 may perform many functions including the nucleation and stabilization of microtubules (and maybe microfilaments), the regulation of organelle transport within axons and dendrites, as well as the anchorage of regulatory proteins such as protein kinases which may be important for signal transduction. These putative functions of MAP2 have also been proposed to play important roles in the outgrowth of neuronal processes, synaptic plasticity and neuronal cell death. Thus, MAP2 constitutes an interesting case to understand the regulation of neuronal function by the alteration of the phosphorylation state of cytoskeletal proteins in response to different extracellular signals. Here we will review the current knowledge about the regulation of MAP2 function through phosphorylation/dephosphorylation and its relevance in the broader context of neuronal functions.

Animals↗
PubMed2002

Use of L-lysine fluorescence derivatives as tracers to enhance the performance of polarization fluoroimmunoassays. A study using two herbicides as model antigens.

Fluorescence polarization immunoassay (FPIA) is a convenient homogeneous assay, the use of which is restricted in environmental analysis by low sensitivity and matrix effects. We selected the herbicides 2,4D and 2,4,5T to synthesize new L-lysine-based fluorescent tracers using solid-phase chemistry. In addition, three different immunogens of 2,4,5T were prepared for immunization and antibody production. The new tracers and antibodies were adapted to FPIA. Tracers with the hapten attached to the alpha-aminogroup of L-lysine and fluorescein to the e-amino group exhibited at least a 5-fold increased sensitivity when compared to the previously reported ethylenediamine-based tracer (2,4D-EDA-F). The isomeric structure (hapten attached to the e-amino and fluorescein to the alpha-amino group) appeared 7.6 times less sensitive, and all other alternative structures exhibited even lower sensitivities. This observation was confirmed against the monoclonal anti-2,4D antibody E2/G2 and polyclonal anti-2,4,5T antibodies. The affinity constant of 2,4D-EDA-F with E2/G2 was 8.1 times higher when compared with the new tracer, suggesting the more specific nature of the L-lysine-based tracer, the use of which leads to a more sensitive assay. This type of tracer could improve performance and lower substantially the detection limits of FPIAs.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed2006

Mechanism of fiber carcinogenesis: from reactive radical species to silencing of the beta igH3 gene.

Although the U.S. Environmental Protection Agency has restricted the industrial use of regulated forms of asbestos in the United States since the early 1970s, environmental exposure to asbestos remains a health concern in the United States and is a significant health issue among developing countries. Exposure to asbestos is associated with chronic pulmonary diseases and cancer of the lung, pleura, and peritoneum. The mechanism of fiber carcinogenesis is far from clear and is likely to be complex, depending on fiber dimensions, surface properties, and physical durability. The induction of reactive oxygen and nitrogen species upon phagocytosis of fibers plays an important role in fiber genotoxicity. The beta igH3, a secreted protein induced by the transforming growth factor-beta and essential for cell adhesion, is downregulated in asbestos-induced tumorigenic human bronchial epithelial cells. Ectopic expression of the beta igH3 gene abrogates the tumorigenic phenotype and suggests that the gene plays a causal role in fiber carcinogenesis. A better understanding of the carcinogenic mechanism of asbestos and other mineral fibers will provide useful information on interventional and preventive measures for asbestos-mediated diseases such as human pleural and peritoneal mesotheliomas.

Asbestos↗
PubMed2004

Morphogenetic pathway of spore wall assembly in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae spore is protected from environmental damage by a multilaminar extracellular matrix, the spore wall, which is assembled de novo during spore formation. A set of mutants defective in spore wall assembly were identified in a screen for mutations causing sensitivity of spores to ether vapor. The spore wall defects in 10 of these mutants have been characterized in a variety of cytological and biochemical assays. Many of the individual mutants are defective in the assembly of specific layers within the spore wall, leading to arrests at discrete stages of assembly. The localization of several of these gene products has been determined and distinguishes between proteins that likely are involved directly in spore wall assembly and probable regulatory proteins. The results demonstrate that spore wall construction involves a series of dependent steps and provide the outline of a morphogenetic pathway for assembly of a complex extracellular structure.

Cell Membrane↗
PubMed1999

Noise-induced extra-aural pathology: a review and commentary.

The focus of this review paper will be the effects of acoustic phenomenon (noise), characterized by large pressure amplitude (> or =90 dB) and low frequency (< or =500 Hz) (LPALF) on humans and animal models. Current concepts imply the assumption that such LPALF noise impinges only on, or through, the somatic medium of the auditory system. As a consequence of this assumption, the effect of noise on humans is only regulated for purposes of hearing conservation. Guidelines and regulations governing occupational noise assessments are biased toward the subjective human perception of sound. The author will not make the assumption that airborne acoustic phenomena impacts only on the auditory system, and will present a literature review providing evidence for such position. The purpose of this review paper is to defend the existence of extra-aural, noise-induced pathology, particularly the vibroacoustic disease; and to advance the recognition that the respiratory tract could very well be a target organ of this environmental stressor.

Animals↗
PubMedDate not supplied

Addiction and paranoid process: psychoanalytic perspectives.

Multiple aspects of the problem of drug abuse and addiction are formulated in terms of the dynamics of the paranoid process, specifically emphasizing the complex interactions of introjection, projection, and the paranoid construction. The effect of projection is to modify the experience of the drug substance so qualities and capacities, often powerful and magical, are attributed to it, allowing it to serve as an external agency contributing to the maintenance of internal introjective configurations and correspondingly to the preservation of an inner sense of self-cohesion. The projective dynamics deal primarily with the vicissitudes of aggression and narcissism, and are given a sense of organization and meaningful integration by the cognitive elaboration of the paranoid construction. They also serve to locate the drug-taking behavior in a larger matrix of familial, social, and other environmental influences, which tend to give support to the projective system. The interaction of these projective psychological dynamics with the pharmacological action of drug substances completes the drug equation and helps to shed further light on the selection of specific drug substances as having addictive potential.

Adult↗
PubMed2001

Matrix-assisted laser desorption/ionization Fourier transform mass spectrometric analysis of oxygenated triglycerides and phosphatidylcholines in egg tempera paint dosimeters used for environmental monitoring of museum display conditions.

Oxidative changes in triacylglycerols and diacylphosphatidylcholines in egg tempera paint strips are used for chemical dosimetry of the quality of the museum environment. High-resolution matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) was used as a rapid method for the determination of the exact elemental composition of the alteration products from diacylphosphatidylcholines and triacylglycerols. Light exposure of the egg tempera paints yields oxygenated diacylphosphatidylcholines and triacylglycerols. In the latter multiple incorporation of oxygen was observed as a recurring mass difference of 15.995, the exact atomic mass of oxygen. Owing to the high resolution of the FTMS data (routinely 20 000 at m/z 1000 in broadband mode), oxidation products with different elemental compositions but identical nominal mass could be distinguished. Products of oxidative cleavage of triacylglycerols were observed in samples exposed for longer times. The relative intensities of the peaks of singly and multiply oxygenated triacylglycerols were used to derive the degree of oxygenation of the egg lipids in the tempera paint dosimeters. The degree of oxygenation was found to be directly related to the light exposure time. Exposure to elevated temperature (60 degrees C) for a period of 21 days did not lead to oxygenation of the triacylglycerols and diacylphosphatidylcholines. Exposure to NO(x) and SO(2) in the dark greatly increased the degree of oxygenation. Addition of lead- or copper-containing pigments to the egg binding medium (and subsequent storage for 6 months in the dark) led to accelerated conversion of egg lipids to oxidised products.

Journal Article↗