Topical, geospatial, and temporal diffusion of the 2015 North American Menopause Society position statement on nonhormonal management of vasomotor symptoms

OBJECTIVE: We sought to depict the topical, geospatial, and temporal diffusion of the 2015 North American Menopause Society position statement on the nonhormonal management of menopause-associated vasomotor symptoms released on September 21, 2015, and its associated press release from September 23, 2015. METHODS: Three data sources were used: online news articles, National Public Radio, and Twitter. For topical diffusion, we compared keywords and their frequencies among the position statement, press release, and online news articles. We also created a network figure depicting relationships across key content categories or nodes. For geospatial diffusion within the United States, we compared locations of the 109 National Public Radio (NPR) stations covering the statement to 775 NPR stations not covering the statement. For temporal diffusion, we normalized and segmented Twitter data into periods before and after the press release (September 12, 2015 to September 22, 2015 vs September 23, 2015 to October 3, 2015) and conducted a burst analysis to identify changes in tweets from before to after. RESULTS: Topical information diffused across sources was similar with the exception of the more scientific terms "vasomotor symptoms" or "vms" versus the more colloquial term "hot flashes." Online news articles indicated media coverage of the statement was mainly concentrated in the United States. NPR station data showed similar proportions of stations airing the story across the four census regions (Northeast, Midwest, south, west; P = 0.649). Release of the statement coincided with bursts in the menopause conversation on Twitter. CONCLUSIONS: The findings of this study may be useful for directing the development and dissemination of future North American Menopause Society position statements and/or press releases

Redox-mediated quorum sensing in plants.

The rhizosphere, the narrow zone of soil around plant roots, is a complex network of interactions between plants, bacteria, and a variety of other organisms. The absolute dependence on host-derived signals, or xenognosins, to regulate critical developmental checkpoints for host commitment in the obligate parasitic plants provides a window into the rhizosphere's chemical dynamics. These sessile intruders use H2O2 in a process known as semagenesis to chemically modify the mature root surfaces of proximal host plants and generate p-benzoquinones (BQs). The resulting redox-active signaling network regulates the spatial and temporal commitments necessary for host attachment. Recent evidence from non-parasites, including Arabidopsis thaliana, establishes that reactive oxygen species (ROS) production regulates similar redox circuits related to root recognition, broadening xenognosins' role beyond the parasites. Here we compare responses to the xenognosin dimethoxybenzoquinone (DMBQ) between the parasitic plant Striga asiatica and the non-parasitic A. thaliana. Exposure to DMBQ simulates the proximity of a mature root surface, stimulating an increase in cytoplasmic Ca2+ concentration in both plants, but leads to remarkably different phenotypic responses in the parasite and non-parasite. In S. asiatica, DMBQ induces development of the host attachment organ, the haustorium, and decreases ROS production at the root tip, while in A. thaliana, ROS production increases and further growth of the root tip is arrested. Obstruction of Ca2+ channels and the addition of antioxidants both lead to a decrease in the DMBQ response in both parasitic and non-parasitic plants. These results are consistent with Ca2+ regulating the activity of NADPH oxidases, which in turn sustain the autocatalytic production of ROS via an external quinone/hydroquinone redox cycle. Mechanistically, this chemistry is similar to black and white photography with the emerging dynamic reaction-diffusion network laying the foundation for the precise temporal and spatial control underlying rhizosphere architecture

[Ca²⁺]_cyt -dynamics in A. thaliana YC3.6 seedlings in response to DMBQ.

<p>(A) Seedlings are treated with 10 μM DMBQ, LaCl₃,.t-butyl BQ, and/or TFBQ as indicated for 1 hour then visualized for calcium changes. (B) Seedlings are loaded with 10 μM DMBQ and incubated for the indicated time before being scored for calcium-dependent fluorescence changes. All experiments are conducted on seedlings of <i>A</i>. <i>thaliana</i> YC3.6 in triplicate and the results are expressed as average ± SD. Samples with different letters are statistically distinct from one another (<i>p</i><0.05) based on a Tukey’s post-hoc test.</p

Root density impacts ROS production in <i>A</i>. <i>thaliana</i>.

<p>(A) The indicated number of seedlings are placed in 3 ml of MS media containing: 10 μM DMBQ (white), 10μM DMBQ and 10 μM LaCl₃ (light grey), or 10 μM DMBQ and 10μM TFBQ (dark grey). After 2 hours the seedlings were visualized for ROS production with H₂DCF-DA. (B) Individual seedlings were stored at ‘low density’ (1 seedling in 3 ml), ‘high density’ (1 seedling in 200 μl), or ‘transfer’ media (3 ml of media previously used to store 15 seedlings) with or without catalase treatment. Media was either supplemented with just DMSO stock (white) or with the addition of 10 μM LaCl₃ (light grey) or 10μM TFBQ (dark grey). After 2 hours samples were visualized for ROS production with H₂DCF-DA. All experiments conducted on 30 seedlings of <i>A</i>. <i>thaliana</i> in triplicate with results expressed as average ± SD. Samples with different letters are statistically distinct from one another (<i>p</i><0.05) based on a Tukey’s post-hoc test.</p

ROS/phenol/BQ reaction network in plants.

<p><b>Simple model for ‘quorum’ or collision sensing in Arabidopsis.</b> (A) A growing lateral root from a young seedling encounters an established plant (red box). (B) Within a certain distance, ROS produced by the tip of the growing seedling contributes to oxidation of cell wall associated phenols to yield BQs (red arrow). DMBQ is shown here as an example. These BQs accumulate, contribute to the autocatalytic production of new ROS intermediates, amplify the signal (green arrow). (C) Evidence of an established root system arrests root elongation in a quorum-like process, regulating global root system architecture.</p

LaCl₃ inhibits DMBQ perception.

<p>(A) Seedlings were treated with 10 μM DMBQ and the indicated concentration of LaCl₃, then scored for haustorium formation after 24 h. ‘Rinsed’ seedlings were subsequently washed with 100 μM CaCl₂, re-exposed to 10 μM DMBQ and scored for haustorium development after 24 h. (B) Seedlings treated with the indicated concentration of DMBQ for 2 hours were then incubated with H₂DCF-DA and visualized for ROS production. LaCl₃ seedlings were treated with 10 μM DMBQ and LaCl₃ simultaneously, incubated for 2 hours then imaged for ROS production. (C) Bright field (light background) and H₂DCF fluorescence images (dark background) of <i>S</i>. <i>asiatica</i> seedlings 2 hours after treatments with (+) or without (-) 10 μM DMBQ and/or LaCl₃. Bar = 100 microns. All experiments conducted on day-old seedlings of <i>Striga asiatica</i> in triplicate with results expressed as average ± SD.</p

[Ca²⁺]_cyt -dynamics in A. thaliana YC3.6 seedlings in response to DMBQ.

<p>(A) Seedlings are treated with 10 μM DMBQ, LaCl₃,.t-butyl BQ, and/or TFBQ as indicated for 1 hour then visualized for calcium changes. (B) Seedlings are loaded with 10 μM DMBQ and incubated for the indicated time before being scored for calcium-dependent fluorescence changes. All experiments are conducted on seedlings of <i>A</i>. <i>thaliana</i> YC3.6 in triplicate and the results are expressed as average ± SD. Samples with different letters are statistically distinct from one another (<i>p</i><0.05) based on a Tukey’s post-hoc test.</p

Proposed role of Ca²⁺ balance in BQ regulated root recognition in parasitic and non-parasitic plants.

<p>DMBQ reduction by plant’s NADPH- oxidase is needed to maintain the production of hydrogen peroxide via redox cycling. Ca²⁺ assisted NADPH down-regulation of NADPH oxidase in <i>Sriga</i> leads to decrease the rate of hydrogen production while up-regulation of the enzyme in <i>A</i>. <i>thaliana</i> leads to rise in ROS concentration along the root surface that ultimately is perceived as a signal to shut down the root growth.</p

LaCl₃ inhibits DMBQ perception in <i>Striga asiatica</i>.

<p>(A) Seedlings were treated with 10 μM DMBQ and/or 10 μM LaCl₃ or with <i>t</i>-butyl-BQ for 1 hour then loaded with Fluo-4 AM and imaged for calcium-dependent fluorescence. (B) Seedlings were incubated with 10 μM DMBQ for the indicated time period then loaded with Fluo-4 AM and imaged for calcium dependent fluorescence. All experiments conducted on day-old seedlings of <i>S</i>. <i>asiatica</i> in triplicate with results expressed as average ± SD. Samples with different letters are statistically distinct from one another (<i>p</i><0.05) based on a Tukey’s post-hoc test.</p

DMBQ induction of ROS depends on Ca²⁺ in <i>A</i>. <i>thaliana</i> seedlings.

<p>(A) Seedlings were treated with 10 μM DMBQ, LaCl₃, and TFBQ as indicated for 1 hour then visualized for ROS production with H₂DCF-DA. (B) Seedlings were treated with 10 μM DMBQ for the indicated period of time then visualized for ROS production with H₂DCF-DA. Relative ROS production is normalized to DMBQ-free seedlings treated with H₂DCF-DA, and all experiments are conducted in triplicate and expressed as average ± SD. Samples with different letters are statistically distinct from one another (<i>p</i><0.05) based on a Tukey’s post-hoc test.</p