Background parenchymal enhancement in preoperative breast MRI.

We aimed to assess the influence of background parenchymal enhancement (BPE) on surgical planning performed using preoperative MRI for breast cancer evaluation. Between January 2009 and December 2010, 91 newly diagnosed breast cancer patients (mean age, 55.5 years; range, 30-88 years) who underwent preoperative bilateral breast MRI followed by planned breast conservation therapy were retrospectively enrolled. MRI was performed to assess the tumor extent in addition to mammography and breast ultrasonography. BPE in the contralateral normal breast MRI at the early dynamic phase was visually classified as follows: minimal (n=49), mild (n=27), moderate (n=7), and marked (n=8). The correlations between the BPE grade and age, menopausal status, index tumor size, changes in surgical management based on MRI results, positive predictive value (PPV) of MRI, and surgical margins were assessed. Patients in the strong BPE groups were significantly younger (p=0.002) and generally premenopausal (p<0.001). Surgical treatment was not changed in 67 cases (73.6%), while extended excision and mastectomy were performed in 12 cases (13.2%), each based on additional lesions on MRI. Six of 79 (7.6%) patients who underwent breast conservation therapy had tumor-positive resection margins. In cases where surgical management was changed, the PPV for MRI-detected foci was high in the minimal (91.7%) and mild groups (66.7%), and 0% in the moderate and marked groups (p=0.002). Strong BPE causes false-positive MRI findings and may lead to overly extensive surgery, whereas MRI may be beneficial in select patients with weak BPE.

Prediction of background parenchymal enhancement on breast MRI using mammography, ultrasonography, and diffusion-weighted imaging.

This retrospective study assessed the effects of menopausal status and menstrual cycle on background parenchymal enhancement (BPE) of breast magnetic resonance imaging (MRI), and investigated whether the degree of BPE can be predicted by findings of mammography, ultrasonography (US), and diffusion-weighted MR imaging (DWI). There were 160 study patients (80 premenopausal, 80 postmenopausal). Degree of BPE was classified into minimal, mild, moderate, or marked. Mammographic density was classified into fatty, scattered, heterogeneously dense, and extremely dense. BP echotexture on US and BP intensity on DWI were visually classified as homogeneous or heterogeneous. Apparent diffusion coefficient (ADC) values of normal breast tissue were measured. Associations of the degree of BPE with menopausal status, menstrual cycle, or imaging features were evaluated by univariate and multivariate analyses. No significant correlation was found between mammographic density and BPE (p=0.085), whereas menopausal status (p=0.000), BP echotexture (p=0.000), and BP intensity on DWI (p= 0.000), and ADC values (p=0.000) showed significant correlations with BPE. Multivariate analysis showed that postmenopausal status was an independent predictor of minimal BPE (p=0.002, OR=3.743). In premenopausal women, there was no significant correlation between menstrual cycle and BPE, whereas BP echotexture was an independent predictor of whether BPE was less than mild or greater than moderate (p=0.001, OR=26.575). BPE on breast MRI is associated with menopausal status and the findings of US and DWI. Because premenopausal women with heterogeneous BP echotexture may be predicted to show moderate or marked BPE, scheduling of breast MRI should preferentially be adjusted to the menstrual cycle.

Involvement of two-component signal transduction system, ComDE, in the regulation of growth and genetic transformation, in the ruminal bacterium Streptococcus bovis.

In ruminants, Streptococcus bovis is considered to be associated with acute rumen acidosis. To elucidate the regulatory mechanisms of S. bovis growth, we investigated the function of the two components of the peptide pheromone-signaling system, ComD and ComE, which are encoded by comD and comE, respectively, via the competence-stimulating peptide ComC, which is encoded by comC. Deletion of entire comC and two-thirds of comD resulted in decreased growth rate, which may be related to the change in the expression of several proteins, as shown by two-dimensional gel electrophoresis. The transcript level of comED was decreased by the disruption of comCD, suggesting that the transcription of comED might be stimulated by ComC. The transformation frequency was decreased by the disruption of comCD. Addition of recombinant ComC to S. bovis cultures increased the growth rate and transformation frequency. In the cultures of mixed ruminal microbes, addition of mature ComC peptide increased the number of S. bovis per total bacterial counts as estimated by the cDNA amounts of 16SrRNA. Thus, the peptide pheromone-signaling system via ComC, D, and E might be involved in the control of S. bovis growth in addition to competence development. This is the first report suggesting that an autoinducing peptide functions in the ruminal ecosystem.

Molecular loops in the galactic center: evidence for magnetic flotation.

The central few hundred parsecs of the Milky Way host a massive black hole and exhibit very violent gas motion and high temperatures in molecular gas. The origin of these properties has been a mystery for the past four decades. Wide-field imaging of the (12)CO (rotational quantum number J = 1 to 0) 2.6-millimeter spectrum has revealed huge loops of dense molecular gas with strong velocity dispersions in the galactic center. We present a magnetic flotation model to explain that the formation of the loops is due to magnetic buoyancy caused by the Parker instability. The model has the potential to offer a coherent explanation for the origin of the violent motion and extensive heating of the molecular gas in the galactic center.