PubMed

Related Articles Untargeted Metabolomic Analysis of Rat Neuroblastoma Cells as a Model System to Study the Biochemical Effects of the Acute Administration of Methamphetamine. Metabolites. 2018 Jun 07;8(2): Authors: Maker GL, Green T, Mullaney I, Trengove RD Abstract Methamphetamine is an illicit psychostimulant drug that is linked to a number of diseases of the nervous system. The downstream biochemical effects of its primary mechanisms are not well understood, and the objective of this study was to investigate whether untargeted metabolomic analysis of an in vitro model could generate data relevant to what is already known about this drug. Rat B50 neuroblastoma cells were treated with 1 mM methamphetamine for 48 h, and both intracellular and extracellular metabolites were profiled using gas chromatography⁻mass spectrometry. Principal component analysis of the data identified 35 metabolites that contributed most to the difference in metabolite profiles. Of these metabolites, the most notable changes were in amino acids, with significant increases observed in glutamate, aspartate and methionine, and decreases in phenylalanine and serine. The data demonstrated that glutamate release and, subsequently, excitotoxicity and oxidative stress were important in the response of the neuronal cell to methamphetamine. Following this, the cells appeared to engage amino acid-based mechanisms to reduce glutamate levels. The potential of untargeted metabolomic analysis has been highlighted, as it has generated biochemically relevant data and identified pathways significantly affected by methamphetamine. This combination of technologies has clear uses as a model for the study of neuronal toxicology. PMID: 29880740 [PubMed]

Related Articles Application of Subwindow Factor Analysis and Mass Spectral information for accurate alignment of non-targeted metabolic profiling. J Chromatogr A. 2018 May 30;: Authors: Yang TB, Yan P, He M, Hong L, Pei R, Zhang ZM, Yi LZ, Yuan XY Abstract The peak shifts may lead to an incorrect statistical result for nontargeted metabolomics profiling, such as classification and discrimination in pattern recognition. In the paper, a more accurate alignment algorithm is developed based on Subwindow Factor Analysis and Mass Spectral information (SFA-MS). Compared with other methods, this new algorithm aligns the peaks more accurately without changing their shapes, especially for the overlapping peak clusters. To begin, the Continuous Wavelet Transform with Haar wavelet as the mother wavelet (Haar CWT) is used to determine the position and width of peaks. On this basis, the candidate drift points are confirmed by Fast Fourier Transform (FFT) cross correlation. Furthermore, the MS fitting degree of the common components between the reference chromatogram and the raw chromatogram is determined by the Subwindow Factor Analysis (SFA). When the MS information between reference and raw peaks is identical, the corresponding moving points are the optimum shifts. It is remarkable that all the peaks are moved through linear interpolation in the non-peak parts, so that the aligned chromatograms remain unchanged. The SFA-MS algorithm was implemented in the Matlab language and is available as an open source package. PMID: 29880218 [PubMed - as supplied by publisher]

Related Articles Novel SWATHTM technology for follicular fluid metabolomics in patients with endometriosis. Pharmazie. 2018 Jun 01;73(6):318-323 Authors: Sun Z, Song J, Zhang X, Wang A, Guo Y, Yang Y, Wang X, Xu K, Deng J Abstract AIM OF THE STUDY: Sequential window acquisition of all theoretical fragment-ion spectra (SWATHTM), a powerful high-resolution mass spectrometric data independent acquisition technique, was used to identify differences that relate certain metabolites to endometriosis (EMT) in follicular fluid collected from EMT patients and a control group. METHODS: A case-control study was conducted to analyze the EMT-related metabolites and the IVF clinical data of 33 subjects. Subjects were divided between the observation group (17 cases, infertility due to EMT) and the control group (16 cases, infertility due to male factor, such as obstructive azoospermia). RESULTS: Analysis revealed three metabolites including phytosphingosine, LysoPC(18:2(9Z,12Z)) and LysoPC(18:0), which were closely related to infertility associated withEMT. In the EMT group, LysoPC(18:2(9Z,12Z)) and LysoPC(18:0) were upregulated, while phytosphingosine was downregulated. CONCLUSIONS: This study employed, for the first time, the SWATHTM data acquisition mode for the metabolomics study of human follicular fluid in patients with EMT. The differential metabolite profiles of follicular fluid were identified and mapped. These differential metabolites are involved in cell proliferation and apoptosis, energy metabolism, inflammatory responses and angiogenesis. The differential metabolite profile may be a new tool for early noninvasive assessment of the developmental potential of oocytes in patients with EMT. PMID: 29880083 [PubMed - in process]

Related Articles Ethnobotanic, Ethnopharmacologic Aspects and New Phytochemical Insights into Moroccan Argan Fruits. Int J Mol Sci. 2017 Oct 30;18(11): Authors: Khallouki F, Eddouks M, Mourad A, Breuer A, Owen RW Abstract This review summarizes available data on argan fruit botany, geographical distribution, traditional uses, environmental interest, socioeconomic role, phytochemistry, as well as health beneficial effects and examination of future prospects. In particular, ethnomedical uses of argan fruits are carried out throughout Morocco where it has been used against various diseases. Different classes of bioactive compounds have been characterized including essential oils, fatty acids, triacylglycerols, flavonoids and their newly reported acylglycosyl derivatives, monophenols, phenolic acids, cinnamic acids, saponins, triterpenes, phytosterols, ubiquinone, melatonin, new aminophenols along with vitamin E among other secondary metabolites. The latter have already shown a wide spectrum of in vitro, and ex vivo biologicalactivities including antioxidant, anti-inflammatory, anti-diabetic, antihypertensive, anti-hypercholesterolemia, analgesic, antimicrobial, molluscicidal anti-nociceptive and anticancer potential. Argan flesh (pulp) contains a broad spectrum of polyphenolic compounds which may have utility for incorporation into nutraceuticals and cosmeceuticals relevant to the food, cosmetic and health industries. Further research is recommended, especially on the health beneficial effects of the aminophenols. PMID: 29084170 [PubMed - indexed for MEDLINE]

Related Articles Isoprostanes, neuroprostanes and phytoprostanes: An overview of 25years of research in chemistry and biology. Prog Lipid Res. 2017 Oct;68:83-108 Authors: Galano JM, Lee YY, Oger C, Vigor C, Vercauteren J, Durand T, Giera M, Lee JC Abstract Since the beginning of the 1990's diverse types of metabolites originating from polyunsaturated fatty acids, formed under autooxidative conditions were discovered. Known as prostaglandin isomers (or isoprostanoids) originating from arachidonic acid, neuroprostanes from docosahexaenoic acid, and phytoprostanes from α-linolenic acid proved to be prevalent in biology. The syntheses of these compounds by organic chemists and the development of sophisticated mass spectrometry methods has boosted our understanding of the isoprostanoid biology. In recent years, it has become accepted that these molecules not only serve as markers of oxidative damage but also exhibit a wide range of bioactivities. In addition, isoprostanoids have emerged as indicators of oxidative stress in humans and their environment. This review explores in detail the isoprostanoid chemistry and biology that has been achieved in the past three decades. PMID: 28923590 [PubMed - indexed for MEDLINE]

24 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results: metabolomics These pubmed results were generated on 2018/06/08PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

24 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results: metabolomics These pubmed results were generated on 2018/06/08PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

25 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results: metabolomics These pubmed results were generated on 2018/06/07PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

25 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results: metabolomics These pubmed results were generated on 2018/06/07PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

18 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results: metabolomics These pubmed results were generated on 2018/06/06PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

18 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results: metabolomics These pubmed results were generated on 2018/06/05PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

Related Articles Metabolome changes are induced in the arbuscular mycorrhizal fungus Gigaspora margarita by germination and by its bacterial endosymbiont. Mycorrhiza. 2018 Jun 02;: Authors: Dearth SP, Castro HF, Venice F, Tague ED, Novero M, Bonfante P, Campagna SR Abstract Metabolomic profiling is becoming an increasingly important technique in the larger field of systems biology by allowing the simultaneous measurement of thousands of small molecules participating in and resulting from cellular reactions. In this way, metabolomics presents an opportunity to observe the physiological state of a system, which may provide the ability to monitor the whole of cellular metabolism as the technology progresses. The arbuscular mycorrhizal fungus Gigaspora margarita has not previously been explored with regard to metabolite composition. To develop a better understanding of G. margarita and the influences of its endosymbiont Candidatus Glomeribacter gigasporarum, a metabolomic analysis was applied to quiescent and germinated spores with and without endobacteria. Over 100 metabolites were identified and greater than 2600 unique unidentified spectral features were observed. Multivariate analysis of the metabolomes was performed, and a differentiation between all metabolic states of spores and spores hosting the endobacteria was observed. The known metabolites were recruited to many biochemical pathways, with many being involved in maintenance of the antioxidant potential, tyrosine metabolism, and melanin production. Each of the pathways had higher metabolite abundances in the presence of the endosymbiont. These metabolomics data also agree with previously reported transcriptomics results demonstrating the capability of this technique to confirm hypotheses and showing the feasibility of multi-omic approaches for the study of arbuscular mycorrhizal fungi and their endobacterial communities. Challenges still exist in metabolomic analysis, e.g., the identification of compounds is demanding due to incomplete libraries. A metabolomics technique to probe the effects of bacterial endosymbionts on fungal physiology is presented herein, and this method is useful for hypothesis generation as well as testing as noted above. PMID: 29860608 [PubMed - as supplied by publisher]

Related Articles Glutamine supplementation enhances development of in vitro-produced porcine embryos and increases leucine consumption from the medium. Biol Reprod. 2018 May 31;: Authors: Chen PR, Redel BK, Spate LD, Ji T, Salazar SR, Prather RS Abstract Improper composition of culture medium contributes to reduced viability of in vitro-produced embryos. Glutamine (Gln) is a crucial amino acid for preimplantation embryos as it supports proliferation and is involved in many different biosynthetic pathways. Previous transcriptional profiling revealed several upregulated genes related to Gln transport and metabolism in in vitro-produced porcine blastocysts compared to in vivo-produced counterparts, indicating a potential deficiency in the culture medium. Therefore, the objective of this study was to determine the effects of Gln supplementation on in vitro-produced porcine embryo development, gene expression, and metabolism. Cleaved embryos were selected and cultured in MU2 medium supplemented with 1 mM Gln (control), 3.75 mM Gln (+Gln), 3.75 mM GlutaMAX (+Max), or 3.75 mM alanine (+Ala) until day 6. Embryos cultured with +Gln or +Max had increased development to the blastocyst stage and total number of nuclei compared to the control (P < 0.05). Moreover, expression of misregulated transcripts involved in glutamine and glutamate transport and metabolism were corrected when embryos were cultured with +Gln or +Max. Metabolomics analysis revealed increased production of glutamine and glutamate into the medium by embryos cultured with +Max and increased consumption of leucine by embryos cultured with +Gln or +Max. As an indicator of cellular health, mitochondrial membrane potential was increased when embryos were cultured with +Max which was coincident with decreased apoptosis in these blastocysts. Lastly, two embryo transfers by using embryos cultured with +Max resulted in viable piglets, confirming that this treatment is consistent with in vivo developmental competence. PMID: 29860318 [PubMed - as supplied by publisher]

Related Articles Metabolomics and antioxidant activity of the leaves of Prunus dulcis Mill. (Italian cvs. Toritto and Avola). J Pharm Biomed Anal. 2018 May 23;158:54-65 Authors: Bottone A, Montoro P, Masullo M, Pizza C, Piacente S Abstract Prunus dulcis leaves have been reported to exert some biological activity, in particular potent free radical-scavenging capacity, but so far there is limited information on their chemical composition. With the aim to achieve deep insight on the chemical constituents of the leaves of P. dulcis cultivars "Toritto" and "Avola", the most appreciated in Italy, an approach based on liquid chromatography-mass spectrometry (LC-MS) combined with isolation and structure elucidation of pure compounds by Nuclear Magnetic Resonance (NMR) analysis was carried out. Results allowed to detect in cv. Toritto leaves phenolics, terpenoids and a cyanogenic glycoside. Successively, various solvent systems were chosen to afford different extracts and an approach based on principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) from LC-MS data sets highlighted eco-friendly methods as selective in extracting phenolics and glycosides. Comparison of LC-MS profiles of the MeOH extracts of cv. Toritto and cvs. Avola (Pizzuta, Fascionello and Romana) leaves and evaluation of their phenolic contents and antioxidant activity were also carried out. PMID: 29860179 [PubMed - as supplied by publisher]

Related Articles Tracking gene expression and oxidative damage of O2-stressed Clostridioides difficile by a multi-omics approach. Anaerobe. 2018 May 31;: Authors: Neumann-Schaal M, Metzendorf NG, Troitzsch D, Nuss AM, Hofmann JD, Beckstette M, Dersch P, Otto A, Sievers S Abstract Clostridioides difficile is the major pathogen causing diarrhea following antibiotic treatment. It is considered to be a strictly anaerobic bacterium, however, previous studies have shown a certain and strain-dependent oxygen tolerance. In this study, the model strain C. difficile 630Δerm was shifted to micro-aerobiosis and was found to stay growing to the same extent as anaerobically growing cells with only few changes in the metabolite pattern. However, an extensive change in gene expression was determined by RNA-Seq. The most striking adaptation strategies involve a change in the reductive fermentation pathways of the amino acids proline, glycine and leucine. But also a far-reaching restructuring in the carbohydrate metabolism was detected with changes in the phosphotransferase system (PTS) facilitated uptake of sugars and a repression of enzymes of glycolysis and butyrate fermentation. Furthermore, a temporary induction in the synthesis of cofactor riboflavin was detected possibly due to an increased demand for flavin mononucleotid (FMN) and flavin adenine dinucleotide (FAD) in redox reactions. However, biosynthesis of the cofactors thiamin pyrophosphate and cobalamin were repressed deducing oxidation-prone enzymes and intermediates in these pathways. Micro-aerobically shocked cells were characterized by an increased demand for cysteine and a thiol redox proteomics approach revealed a dramatic increase in the oxidative state of cysteine in more than 800 peptides after 15 min of micro-aerobic shock. This provides not only a catalogue of oxidation-prone cysteine residues in the C. difficile proteome but also puts the amino acid cysteine into a key position in the oxidative stress response. Our study suggests that tolerance of C. difficile towards O2 is based on a complex and far-reaching adjustment of global gene expression which leads to only a slight change in phenotype. PMID: 29859941 [PubMed - as supplied by publisher]

Adipose Tissue-Derived Stromal Cells for Wound Healing. Adv Exp Med Biol. 2018 Jun 02;: Authors: Goodarzi P, Alavi-Moghadam S, Sarvari M, Tayanloo Beik A, Falahzadeh K, Aghayan H, Payab M, Larijani B, Gilany K, Rahim F, Adibi H, Arjmand B Abstract Skin as the outer layer covers the body. Wounds can affect this vital organ negatively and disrupt its functions. Wound healing as a biological process is initiated immediately after an injury. This process consists of three stages: inflammation, proliferation, remodeling. Generally, these three stages occur continuously and timely. However, some factors such as infection, obesity and diabetes mellitus can interfere with these stages and impede the normal healing process which results in chronic wounds. Financial burden on both patients and health care systems, negative biologic effect on the patient's general health status and reduction in quality of life are a number of issues which make chronic wounds as a considerable challenge. During recent years, along with advances in the biomedical sciences, various surgical and non-surgical therapeutic methods have been suggested. All of these suggested treatments have their own advantages and disadvantages. Recently, cell-based therapies and regenerative medicine represent promising approaches to wound healing. Accordingly, several types of mesenchymal stem cells have been used in both preclinical and clinical settings for the treatment of wounds. Adipose-derived stromal cells are a cost-effective source of mesenchymal stem cells in wound management which can be easily harvest from adipose tissues through the less invasive processes with high yield rates. In addition, their ability to secrete multiple cytokines and growth factors, and differentiation into skin cells make them an ideal cell type to use in wound treatment. This is a concise overview on the application of adipose-derived stromal cells in wound healing and their role in the treatment of chronic wounds. PMID: 29858972 [PubMed - as supplied by publisher]

Comparative transcription profiling of two fermentation cultures of Xanthomonas campestris pv. campestris B100 sampled in the growth and in the stationary phase. Appl Microbiol Biotechnol. 2018 Jun 01;: Authors: Alkhateeb RS, Vorhölter FJ, Steffens T, Rückert C, Ortseifen V, Hublik G, Niehaus K, Pühler A Abstract The ɣ-proteobacterium Xanthomonas campestris pv. campestris (Xcc) is the producer of the biopolymer xanthan, a polysaccharide which is used as a thickener in numerous industrial applications. In this study, we present a global transcriptome profiling of two Xcc strain B100 cultures obtained from fermentation during the growth phase and the subsequent stationary phase associated with xanthan biosynthesis. During the xanthan production phase, highly abundant transcripts belonged to genes encoding for small RNAs, glycogen biosynthesis, and xanthan export. A total of 1850 (40%) genes were differentially transcribed during the stationary phase where 924 were transcriptionally up-regulated and 926 genes were down-regulated. An overview of differentially transcribed genes includes a significant down-regulation of genes involved in transcription, translation, and amino acid biosynthesis pathways. A group of up-regulated genes was involved in cellular response against oxidative stress, such as those coding for superoxide dismutase and catalase. Genes encoding enzymes involved in nucleotide sugar precursor synthesis of xanthan biosynthesis, such as xanA, galU, and ugd, exhibited a transcription pattern that did not change during the growth and stationary phase. Regarding the transcription pattern of the gum gene cluster that govern xanthan biosynthesis, a significant up-regulation of the genes gumB, gumC, and gumD was observed, while the transcript pools of the genes gumG, gumH, gumI, and gumJ were reduced and those of genes gumE, gumF, gumK, gumL, and gumM remained un-changed during the stationary phase compared to the growth phase. The obtained data represents the first analysis of gene expression patterns under xanthan production conditions and provides the bases for future studies aiming at enhancing xanthan yield. PMID: 29858955 [PubMed - as supplied by publisher]

Longitudinal Changes in Cholesterol Efflux Capacities in Patients With Coronary Artery Disease Undergoing Lifestyle Modification Therapy. J Am Heart Assoc. 2018 Jun 01;7(11): Authors: Boyer M, Lévesque V, Poirier P, Marette A, Mitchell PL, Mora S, Mathieu P, Després JP, Larose É, Arsenault BJ Abstract BACKGROUND: Our objective was to identify the determinants of high-density lipoprotein cholesterol efflux capacity (HDL-CEC) changes in patients with coronary artery disease who participated in a lifestyle modification program aimed at increasing physical activity levels and improving diet quality. METHODS AND RESULTS: A total of 86 men with coronary artery disease aged between 35 and 80 years participated in a 1-year lifestyle modification program that aimed to achieve a minimum of 150 minutes of aerobic physical activity weekly and improve diet quality. HDL-CECs were measured before and after the 1-year intervention using 3H-cholesterol-labeled J774 and HepG2 cells. Visceral, subcutaneous, and cardiac adipose tissue levels were assessed before and after the intervention using magnetic resonance imaging. Lipoprotein particle size and concentrations were measured by proton nuclear magnetic resonance spectroscopy and a complete lipoprotein-lipid profile was obtained. At baseline, the best correlate of HDL-CECs were apolipoprotein AI (R2=0.35, P<0.0001) and high-density lipoprotein cholesterol (R2=0.21, P<0.0001) for J774-HDL-CECs and HepG2-HDL-CECs, respectively. Baseline and longitudinal changes in HDL-CECs were associated with several lipoprotein size and concentration indices, although high-density lipoprotein cholesterol was the best predictor of longitudinal changes in J774-HDL-CECs (R2=0.18, P=0.002) and apolipoprotein AI was found to be the best predictor of longitudinal changes in HepG2 cholesterol efflux capacities (R2=0.21, P=0.002). CONCLUSIONS: Results of this study suggest that increases in high-density lipoprotein cholesterol and apolipoprotein AI levels typically observed in patients with coronary artery disease undergoing healthy lifestyle modification therapy may be indicative of higher plasma concentrations of functional high-density lipoprotein particles. PMID: 29858367 [PubMed - in process]

Protective effects of Scutellaria baicalensis Georgi extract on D-galactose induced aging rats. Metab Brain Dis. 2018 May 31;: Authors: Zhao F, Chang Y, Gao L, Qin X, Du G, Zhang X, Zhou Y Abstract Scutellaria baicalensis Georgi (SBG), a traditional Chinese herb, has attracted considerable attention for its wide range of pharmacological activities. This study aimed to investigate the intervention effects of SBG ethanol extract on aging rats induced by D-galactose (D-gal) and to explore potential mechanisms by serum and liver metabolic profiles. The aging rats were induced by the D-gal (100 mg/kg) for 10 weeks continuously with subcutaneous injection, while the control rats received physiological saline. Two other groups of rats were administered with 100 mg/kg/day and 200 mg/kg/day of SBG by oral route following D-gal injections. The abilities of spatial and learning memory were evaluated by open-field test and Morris water maze test. Then, some biochemical indexes related to cognitive ability and aging were measured. Histopathological feature in hippocampal region was observed by Hematoxylin and eosin (HE) staining. The changes of metabolic profiles were evaluated using proton nuclear magnetic resonance (1H NMR) spectroscopy coupled with multivariate data analysis. Results showed that SBG could significantly improve the learning and memory functions, reducing oxidative damage and histological abnormalities of hippocampus neurons. In addition, significant differences in the metabolic profiles were observed both in serum and liver between the model group and the control group. After the treatment using SBG, the levels of these metabolites are significantly changed back to their similar levels in the control group. These metabolic changes are related to the disturbance in amino acid metabolism, glycometabolism and choline metabolism. Hence, SBG may have the potential to improve neurodegeneration and provide brain protection. Graphical abstract A 1H NMR-based metabonomic study was conducted to provide a global view of metabolites related to D-gal induced aging rats and assess the holistic efficacy of Scutellaria baicalensis Georgi. PMID: 29855978 [PubMed - as supplied by publisher]

Tissue Engineered Skin Substitutes. Adv Exp Med Biol. 2018 Jun 01;: Authors: Goodarzi P, Falahzadeh K, Nematizadeh M, Farazandeh P, Payab M, Larijani B, Tayanloo Beik A, Arjmand B Abstract The fundamental skin role is to supply a supportive barrier to protect body against harmful agents and injuries. Three layers of skin including epidermis, dermis and hypodermis form a sophisticated tissue composed of extracellular matrix (ECM) mainly made of collagens and glycosaminoglycans (GAGs) as a scaffold, different cell types such as keratinocytes, fibroblasts and functional cells embedded in the ECM. When the skin is injured, depends on its severity, the majority of mentioned components are recruited to wound regeneration. Additionally, different growth factors like fibroblast growth factor (FGF), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) are needed to orchestrated wound healing process. In case of large surface area wounds, natural wound repair seems inefficient. Inspired by nature, scientists in tissue engineering field attempt to engineered constructs mimicking natural healing process to promote skin restoration in untreatable injuries. There are three main types of commercially available engineered skin substitutes including epidermal, dermal, and dermoepidermal. Each of them could be composed of scaffold, desired cell types or growth factors. These substitutes could have autologous, allogeneic, or xenogeneic origin. Moreover, they may be cellular or acellular. They are used to accelerate wound healing and recover normal skin functions with pain relief. Although there are a wide variety of commercially available skin substitutes, almost none of them considered as an ideal equivalents required for proper wound healing. PMID: 29855826 [PubMed - as supplied by publisher]