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On page 15 showing 281 ~ 300 papers out of 2,794,544 papers

Chemoresistance Evolution in Triple-Negative Breast Cancer Delineated by Single-Cell Sequencing.

  • Charissa Kim‎ et al.
  • Cell‎
  • 2018‎

Triple-negative breast cancer (TNBC) is an aggressive subtype that frequently develops resistance to chemotherapy. An unresolved question is whether resistance is caused by the selection of rare pre-existing clones or alternatively through the acquisition of new genomic aberrations. To investigate this question, we applied single-cell DNA and RNA sequencing in addition to bulk exome sequencing to profile longitudinal samples from 20 TNBC patients during neoadjuvant chemotherapy (NAC). Deep-exome sequencing identified 10 patients in which NAC led to clonal extinction and 10 patients in which clones persisted after treatment. In 8 patients, we performed a more detailed study using single-cell DNA sequencing to analyze 900 cells and single-cell RNA sequencing to analyze 6,862 cells. Our data showed that resistant genotypes were pre-existing and adaptively selected by NAC, while transcriptional profiles were acquired by reprogramming in response to chemotherapy in TNBC patients.


KREMEN1 Is a Host Entry Receptor for a Major Group of Enteroviruses.

  • Jacqueline Staring‎ et al.
  • Cell host & microbe‎
  • 2018‎

Human type A Enteroviruses (EV-As) cause diseases ranging from hand-foot-and-mouth disease to poliomyelitis-like disease. Although cellular receptors are identified for some EV-As, they remain elusive for the majority of EV-As. We identify the cell surface molecule KREMEN1 as an entry receptor for coxsackievirus A10 (CV-A10). Whereas loss of KREMEN1 renders cells resistant to CV-A10 infection, KREMEN1 overexpression enhances CV-A10 binding to the cell surface and increases susceptibility to infection, indicating that KREMEN1 is a rate-limiting factor for CV-A10 infection. Furthermore, the extracellular domain of KREMEN1 binds CV-A10 and functions as a neutralizing agent during infection. Kremen-deficient mice are resistant to CV-A10-induced lethal paralysis, emphasizing the relevance of Kremen for infection in vivo. KREMEN1 is also essential for infection by a phylogenetic and pathogenic related group of EV-As. Collectively these findings highlight the importance of KREMEN1 for these emerging pathogens and its potential as an antiviral therapeutic target.


A Visual Cortical Network for Deriving Phonological Information from Intelligible Lip Movements.

  • Anne Hauswald‎ et al.
  • Current biology : CB‎
  • 2018‎

Successful lip-reading requires a mapping from visual to phonological information [1]. Recently, visual and motor cortices have been implicated in tracking lip movements (e.g., [2]). It remains unclear, however, whether visuo-phonological mapping occurs already at the level of the visual cortex-that is, whether this structure tracks the acoustic signal in a functionally relevant manner. To elucidate this, we investigated how the cortex tracks (i.e., entrains to) absent acoustic speech signals carried by silent lip movements. Crucially, we contrasted the entrainment to unheard forward (intelligible) and backward (unintelligible) acoustic speech. We observed that the visual cortex exhibited stronger entrainment to the unheard forward acoustic speech envelope compared to the unheard backward acoustic speech envelope. Supporting the notion of a visuo-phonological mapping process, this forward-backward difference of occipital entrainment was not present for actually observed lip movements. Importantly, the respective occipital region received more top-down input, especially from left premotor, primary motor, and somatosensory regions and, to a lesser extent, also from posterior temporal cortex. Strikingly, across participants, the extent of top-down modulation of the visual cortex stemming from these regions partially correlated with the strength of entrainment to absent acoustic forward speech envelope, but not to present forward lip movements. Our findings demonstrate that a distributed cortical network, including key dorsal stream auditory regions [3-5], influences how the visual cortex shows sensitivity to the intelligibility of speech while tracking silent lip movements.


CapZyme-Seq Comprehensively Defines Promoter-Sequence Determinants for RNA 5' Capping with NAD.

  • Irina O Vvedenskaya‎ et al.
  • Molecular cell‎
  • 2018‎

Nucleoside-containing metabolites such as NAD+ can be incorporated as 5' caps on RNA by serving as non-canonical initiating nucleotides (NCINs) for transcription initiation by RNA polymerase (RNAP). Here, we report CapZyme-seq, a high-throughput-sequencing method that employs NCIN-decapping enzymes NudC and Rai1 to detect and quantify NCIN-capped RNA. By combining CapZyme-seq with multiplexed transcriptomics, we determine efficiencies of NAD+ capping by Escherichia coli RNAP for ∼16,000 promoter sequences. The results define preferred transcription start site (TSS) positions for NAD+ capping and define a consensus promoter sequence for NAD+ capping: HRRASWW (TSS underlined). By applying CapZyme-seq to E. coli total cellular RNA, we establish that sequence determinants for NCIN capping in vivo match the NAD+-capping consensus defined in vitro, and we identify and quantify NCIN-capped small RNAs (sRNAs). Our findings define the promoter-sequence determinants for NCIN capping with NAD+ and provide a general method for analysis of NCIN capping in vitro and in vivo.


A Glial Signature and Wnt7 Signaling Regulate Glioma-Vascular Interactions and Tumor Microenvironment.

  • Amelie Griveau‎ et al.
  • Cancer cell‎
  • 2018‎

Gliomas comprise heterogeneous malignant glial and stromal cells. While blood vessel co-option is a potential mechanism to escape anti-angiogenic therapy, the relevance of glial phenotype in this process is unclear. We show that Olig2+ oligodendrocyte precursor-like glioma cells invade by single-cell vessel co-option and preserve the blood-brain barrier (BBB). Conversely, Olig2-negative glioma cells form dense perivascular collections and promote angiogenesis and BBB breakdown, leading to innate immune cell activation. Experimentally, Olig2 promotes Wnt7b expression, a finding that correlates in human glioma profiling. Targeted Wnt7a/7b deletion or pharmacologic Wnt inhibition blocks Olig2+ glioma single-cell vessel co-option and enhances responses to temozolomide. Finally, Olig2 and Wnt7 become upregulated after anti-VEGF treatment in preclinical models and patients. Thus, glial-encoded pathways regulate distinct glioma-vascular microenvironmental interactions.


Site-Specific Three-Color Labeling of α-Synuclein via Conjugation to Uniquely Reactive Cysteines during Assembly by Native Chemical Ligation.

  • Taehyung C Lee‎ et al.
  • Cell chemical biology‎
  • 2018‎

Single-molecule fluorescence is widely used to study conformational complexity in proteins, and has proven especially valuable with intrinsically disordered proteins (IDPs). Protein studies using dual-color single-molecule Förster resonance energy transfer (smFRET) are now quite common, but many could benefit from simultaneous measurement of multiple distances through multi-color labeling. Such studies, however, have suffered from limitations in site-specific incorporation of more than two dyes per polypeptide. Here we present a fully site-specific three-color labeling scheme for α-synuclein, an IDP with important putative functions and links to Parkinson disease. The convergent synthesis combines native chemical ligation with regiospecific cysteine protection of expressed protein fragments to permit highly controlled labeling via standard cysteine-maleimide chemistry, enabling more global smFRET studies. Furthermore, this modular approach is generally compatible with recombinant proteins and expandable to accommodate even more complex experiments, such as by labeling with additional colors.


NF-κB Activity Initiates Human ESC-Derived Neural Progenitor Cell Differentiation by Inducing a Metabolic Maturation Program.

  • Lorna M FitzPatrick‎ et al.
  • Stem cell reports‎
  • 2018‎

Human neural development begins at embryonic day 19 and marks the beginning of organogenesis. Neural stem cells in the neural tube undergo profound functional, morphological, and metabolic changes during neural specification, coordinated by a combination of exogenous and endogenous cues. The temporal cell signaling activities that mediate this process, during development and in the postnatal brain, are incompletely understood. We have applied gene expression studies and transcription factor-activated reporter lentiviruses during in vitro neural specification of human pluripotent stem cells. We show that nuclear factor κB orchestrates a multi-faceted metabolic program necessary for the maturation of neural progenitor cells during neurogenesis.


A rat model for pituitary stalk electric lesion-induced central diabetes insipidus: application of 3D printing and further outcome assessments.

  • Zhanpeng Feng‎ et al.
  • Experimental animals‎
  • 2018‎

A stable and reproducible rat injury model is not currently available to study central diabetes insipidus (CDI) and the neurohypophyseal system. In addition, a system is needed to assess the severity of CDI and measure the accompanying neurobiological alterations. In the present study, a 3D-printed lesion knife with a curved head was designed to fit into the stereotaxic instrument. The neuro-anatomical features of the brain injury were determined by in vivo magnetic resonance imaging (MRI) and arginine vasopressin (AVP) immunostaining on brain sections. Rats that underwent pituitary stalk electrical lesion (PEL) exhibited a tri-phasic pattern of CDI. MRI revealed that the hyperintenseT1-weighted signal of the pituitary stalk was interrupted, and the brain sections showed an enlarged end proximal to the injury site after PEL. In addition, the number of AVP-positive cells in supraoptic nucleus (SON) and paraventricular nucleus (PVN) decreased after PEL, which confirmed the success of the CDI model. Unlike hand-made tools, the 3D-printed lesion knives were stable and reproducible. Next, we used an ordinal clustering method for staging and the k-means' clustering method to construct a CDI index to evaluate the severity and recovery of CDI that could be used in other multiple animals, even in clinical research. In conclusion, we established a standard PEL model with a 3D-printed knife tool and proposed a CDI index that will greatly facilitate further research on CDI.


Phylloporia lonicerae (Hymenochaetales, Basidiomycota), a new species on Lonicera japonica from Japan and an identification key to worldwide species of Phylloporia.

  • Wen-Min Qin‎ et al.
  • MycoKeys‎
  • 2018‎

Phylloporia, in the Hymenochaetaceae, is a polypore genus with a worldwide distribution. The new taxon Phylloporia lonicerae is introduced, which is the first Phylloporia species to originate from Japan. This species grows exclusively on living Lonicera japonica and is distinguished by annual, sessile basidiocarps that occur in clusters, pileal surface of narrow, concentrically sulcate zones, 6-8 pores per mm, duplex context separated by a black zone, dimitic hyphal system and broadly ellipsoid basidiospores, 3.2-4 × 2.3-3.1 µm. Phylogenetically, P. lonicerae is nested within the Phylloporia clade as a distinct terminal lineage with full statistical supports and sister to the clade of P. minutispora, P. cf. pulla and P. terrestris with weak supports. Besides Phylloporia bibulosa, P. chrysites and P. spathulata, P. lonicerae is the fourth species of Phylloporia recorded from Japan. An identification key to all accepted 48 species of Phylloporia is provided.


A multi-gene phylogeny of Chlorophyllum (Agaricaceae, Basidiomycota): new species, new combination and infrageneric classification.

  • Zai-Wei Ge‎ et al.
  • MycoKeys‎
  • 2018‎

Taxonomic and phylogenetic studies of Chlorophyllum were carried out on the basis of morphological differences and molecular phylogenetic analyses. Based on the phylogeny inferred from the internal transcribed spacer (ITS), the partial large subunit nuclear ribosomal DNA (nrLSU), the second largest subunit of RNA polymerase II (rpb2) and translation elongation factor 1-α (tef1) sequences, six well-supported clades and 17 phylogenetic species are recognised. Within this phylogenetic framework and considering the diagnostic morphological characters, two new species, C. africanum and C. palaeotropicum, are described. In addition, a new infrageneric classification of Chlorophyllum is proposed, in which the genus is divided into six sections. One new combination is also made. This study provides a robust basis for a more detailed investigation of diversity and biogeography of Chlorophyllum.


New nematicidal and antimicrobial secondary metabolites from a new species in the new genus, Pseudobambusicola thailandica.

  • Zeljka Rupcic‎ et al.
  • MycoKeys‎
  • 2018‎

During the course of a study on the functional biodiversity of the mycobiota inhabiting rainforests in Thailand, a fungal strain was isolated from a plant sample and shown to represent an undescribed species, as inferred from a combination of morphological and molecular phylogenetic methods. Molecular phylogenetic analyses, based on four DNA loci, revealed a phylogenetic tree with the newly generated sequences clustering in a separate branch, together with members of the Sulcatisporaceae (Pleosporales, Ascomycota). The Thai specimen morphologically resembled Neobambusicola strelitziae in having pycnidial conidiomata with phialidic conidiogenous cells that produce both fusoid-ellipsoid macroconidia and subcylindrical microconidia. However, the new fungus, for which the name Pseudobambusicola thailandica is proposed, differs from N. strelitziae in having conidiomata with well-defined necks, the presence of globose to subglobose thick-walled cells adjacent to conidiomata and the production of chlamydospores in culture. When cultures of P. thailandica, growing on water agar, were confronted with Caenorhabditis elegans nematodes, worms approaching the fungal mycelia were killed. This observation gave rise to a study of its secondary metabolites and six novel and two known compounds were isolated from submerged cultures of P. thailandica. The structures of metabolites 1-6, for which the trivial names thailanones A-F are proposed, were elucidated using a combination of spectral methods, including extensive 1 and 2D NMR analysis and high resolution mass spectrometry. Compounds 4 and 8 showed strong nematicidal and weak antifungal activity, whereas all other tested compounds showed moderate to weak nematicidal activity but no significant effects in the serial dilution assay against various fungi and bacteria. Compounds 1 and 8 also inhibited growth of the pathogenic basidiomycete Phellinus tremulae in a plate diffusion assay.


An updated checklist of the lichens of St. Eustatius, Netherlands Antilles.

  • André Aptroot‎ et al.
  • MycoKeys‎
  • 2018‎

In the course of a multi-taxon biodiversity inventory for the island of St. Eustatius, lichens were collected from 11 plots representing different vegetation types. From these collections, 126 lichen species are reported, 54 of which are new reports for St. Eustatius. Most species could be identified to species level based on morphological and chemical characters. In a few cases, mtSSU DNA sequences were generated for a preliminary molecular identification and future phylogenetic studies. In total, 263 identified lichen species are currently known from St. Eustatius, as well as some additional genera with yet unidentified species and lichenicolous fungi.


Evaluation of Lymphocyte Response to the Induced Oxidative Stress in a Cohort of Ageing Subjects, including Semisupercentenarians and Their Offspring.

  • Federico Sizzano‎ et al.
  • Mediators of inflammation‎
  • 2018‎

The production of reactive oxygen species (ROS) may promote immunosenescence if not counterbalanced by the antioxidant systems. Cell membranes, proteins, and nucleic acids become the target of ROS and progressively lose their structure and functions. This process could lead to an impairment of the immune response. However, little is known about the capability of the immune cells of elderly individuals to dynamically counteract the oxidative stress. Here, the response of the main lymphocyte subsets to the induced oxidative stress in semisupercentenarians (CENT), their offspring (OFF), elderly controls (CTRL), and young individuals (YO) was analyzed using flow cytometry. The results showed that the ratio of the ROS levels between the induced and noninduced (I/NI) oxidative stress conditions was higher in CTRL and OFF than in CENT and YO, in almost all T, B, and NK subsets. Moreover, the ratio of reduced glutathione levels between I/NI conditions was higher in OFF and CENT compared to the other groups in almost all the subsets. Finally, we observed significant correlations between the response to the induced oxidative stress and the degree of methylation in specific genes on the oxidative stress pathway. Globally, these data suggest that the capability to buffer dynamic changes in the oxidative environment could be a hallmark of longevity in humans.


Early Detection of Aβ Deposition in the 5xFAD Mouse by Amyloid PET.

  • Se Jong Oh‎ et al.
  • Contrast media & molecular imaging‎
  • 2018‎

Purpose.18F-FC119S is a positron emission tomography (PET) tracer for imaging β-amyloid (Aβ) plaques in Alzheimer's disease (AD). The aim of this study is to evaluate the efficacy of 18F-FC119S in quantitating Aβ deposition in a mouse model of early amyloid deposition (5xFAD) by PET. Method. Dynamic 18F-FC119S PET images were obtained in 5xFAD (n = 5) and wild-type (WT) mice (n = 7). The brain PET images were spatially normalized to the M. Mirrione T2-weighted mouse brain MR template, and the volumes of interest were then automatically drawn on the cortex, hippocampus, thalamus, and cerebellum. The specific binding of 18F-FC119S to Aβ was quantified as the distribution volume ratio using Logan graphical analysis with the cerebellum as a reference tissue. The Aβ levels in the brain were also confirmed by immunohistochemical analysis. Result. For the 5xFAD group, radioactivity levels in the cortex, the hippocampus, and the thalamus were higher than those for the WT group. In these regions, specific binding was approximately 1.2-fold higher in 5xFAD mice than in WT. Immunohistochemistry supported these findings; the 5xFAD showed severe Aβ deposition in the cortex and hippocampus in contrast to the WT group. Conclusion. These results demonstrated that 18F-FC119S PET can successfully distinguish Aβ depositions in 5xFAD mice from WT.


High-mass-resolution MALDI mass spectrometry imaging reveals detailed spatial distribution of metabolites and lipids in roots of barley seedlings in response to salinity stress.

  • Lenin D Sarabia‎ et al.
  • Metabolomics : Official journal of the Metabolomic Society‎
  • 2018‎

Mass spectrometry imaging (MSI) is a technology that enables the visualization of the spatial distribution of hundreds to thousands of metabolites in the same tissue section simultaneously. Roots are below-ground plant organs that anchor plants to the soil, take up water and nutrients, and sense and respond to external stresses. Physiological responses to salinity are multifaceted and have predominantly been studied using whole plant tissues that cannot resolve plant salinity responses spatially.


Early Retinal Defects in Fmr1-/y Mice: Toward a Critical Role of Visual Dys-Sensitivity in the Fragile X Syndrome Phenotype?

  • Olivier Perche‎ et al.
  • Frontiers in cellular neuroscience‎
  • 2018‎

Fragile X Syndrome (FXS) is caused by a deficiency in Fragile X Mental Retardation Protein (FMRP) leading to global sensorial abnormalities, among which visual defects represent a critical part. These visual defects are associated with cerebral neuron immaturity especially in the primary visual cortex. However, we recently demonstrated that retinas of adult Fmr1-/y mice, the FXS murine model, present molecular, cellular and functional alterations. However, no data are currently available on the evolution pattern of such defects. As retinal stimulation through Eye Opening (EO) is a crucial signal for the cerebral visual system maturation, we questioned the precocity of molecular and functional retinal phenotype. To answer this question, we studied the retinal molecular phenotype of Fmr1-/y mice before EO until adult age and the consequences of the retinal loss of Fmrp on retinal function in young and adult mice. We showed that retinal molecular defects are present before EO and remain stable at adult age, leading to electrophysiological impairments without any underlying structural changes. We underlined that loss of Fmrp leads to a wide range of defects in the retina, settled even before EO. Our work demonstrates a critical role of the sensorial dysfunction in the Fmr1-/y mice overall phenotype, and provides evidence that altered peripheral perception is a component of the sensory processing defect in FXS conditions.


High Dietary Iron Supplement Induces the Nigrostriatal Dopaminergic Neurons Lesion in Transgenic Mice Expressing Mutant A53T Human Alpha-Synuclein.

  • Fengju Jia‎ et al.
  • Frontiers in aging neuroscience‎
  • 2018‎

Both alpha-synuclein aggregation and iron deposits are neuropathological hallmarks of Parkinson's disease (PD). We are particularly interested in whether iron could synergize with alpha-synuclein pathology in vivo, especially in the nigrostriatal system. In the present study, we reported transgenic mice with overexpressing human A53T alpha-synuclein, as well as WT mice with high dietary iron displayed hyperactive motor coordination and impaired colonic motility, compared with those with basal dietary iron. Only A53T mice, but not WT mice with high dietary iron exhibited nigral dopaminergic neuronal loss, lower levels of tyrosine hydroxylase (TH) in the substantia nigra (SN) and decreased dopamine contents in the striatum. Although there was no obvious elevation of iron contents in the SN in WT mice with high dietary iron, we observed iron contents in the SN were especially higher than the other brain regions in 12-month aged mice with either high or basal dietary iron. These results suggested high dietary iron supplement could induce nigral dopaminergic neurons lesion in A53T mice, which might be due to the vulnerability of SN to accumulate iron.


Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa.

  • Xiaofei Liu‎ et al.
  • Frontiers in pharmacology‎
  • 2018‎

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B1, B2, G1, G2 were extracted from samples by using methanol/water (70:30, v/v) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity (R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15-0.65 and 0.53-2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2-3.6%), and accuracy (recovery rates of 86.0-102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B1 (AFB1) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.


Caffeine Promotes Conversion of Palmitic Acid to Palmitoleic Acid by Inducing Expression of fat-5 in Caenorhabditis elegans and scd1 in Mice.

  • Xiaocui Du‎ et al.
  • Frontiers in pharmacology‎
  • 2018‎

The synthesis and metabolism of fatty acids in an organism is related to many biological processes and is involved in several diseases. The effects of caffeine on fatty acid synthesis and fat storage in Caenorhabditis elegans and mice were studied. After 6 h of food deprivation, adult C. elegans were treated with 0.1 mg/mL caffeine for 24 h. Quantitative reverse-transcription polymerase chain reaction showed that, among all the genes involved in fat accumulation, the mRNA expression of fat-5 in caffeine-treated C. elegans was significantly higher than that of controls, whereas fat-6 and fat-7 displayed no significant difference. Gas chromatography-mass spectrometry was used to verify the fatty acid composition of C. elegans. Results showed that the ratio of palmitoleic acid (16:1) to that of palmitic acid (16:0) was higher in the caffeine-treated group. Several mutant strains, including those involved in the insulin-like growth factor-1, dopamine, and serotonin pathways, and nuclear hormone receptors (nhrs), were used to assess their necessity to the effects of caffeine. We found that mdt-15 was essential for the effects of caffeine, which was independent of nhr-49 and nhr-80. Caffeine may increase fat-5 expression by acting on mdt-15. In high fat diet (HFD), but not in normal diet (ND) mice, caffeine induced expression of scd1 in both subcutaneous and epididymal white adipose tissue, which was consistent with the palmitoleic/palmitic ratio results by gas chromatograph analysis. In mature adipocytes, caffeine treatment induced both mRNA and protein expression of scd1 and pgc-1α. Overall, our results provided a possible mechanism on how caffeine modulates metabolism homeostasis in vivo.


Evidence Supports Tradition: The in Vitro Effects of Roman Chamomile on Smooth Muscles.

  • Zsolt Sándor‎ et al.
  • Frontiers in pharmacology‎
  • 2018‎

The dried flowers of Chamaemelum nobile (L.) All. have been used in traditional medicine for different conditions related to the spasm of the gastrointestinal system. However, there have been no experimental studies to support the smooth muscle relaxant effect of this plant. The aim of our research was to assess the effects of the hydroethanolic extract of Roman chamomile, its fractions, four of its flavonoids (apigenin, luteolin, hispidulin, and eupafolin), and its essential oil on smooth muscles. The phytochemical compositions of the extract and its fractions were characterized and quantified by HPLC-DAD, the essential oil was characterized by GC and GC-MS. Neuronally mediated and smooth muscle effects were tested in isolated organ bath experiments on guinea pig, rat, and human smooth muscle preparations. The crude herbal extract induced an immediate, moderate, and transient contraction of guinea pig ileum via the activation of cholinergic neurons of the gut wall. Purinoceptor and serotonin receptor antagonists did not influence this effect. The more sustained relaxant effect of the extract, measured after pre-contraction of the preparations, was remarkable and was not affected by an adrenergic beta receptor antagonist. The smooth muscle-relaxant activity was found to be associated with the flavonoid content of the fractions. The essential oil showed only the relaxant effect, but no contracting activity. The smooth muscle-relaxant effect was also detected on rat gastrointestinal tissues, as well as on strip preparations of human small intestine. These results suggest that Roman chamomile extract has a direct and prolonged smooth muscle-relaxant effect on guinea pig ileum which is related to its flavonoid content. In some preparations, a transient stimulation of enteric cholinergic motoneurons was also detected. The essential oil also had a remarkable smooth muscle relaxant effect in this setting. Similar relaxant effects were also detected on other visceral preparations, including human jejunum. This is the first report on the activity of Roman chamomile on smooth muscles that may reassure the rationale of the traditional use of this plant in spasmodic gastrointestinal disorders.


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