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The concentration of serum dehydroepiandrosterone sulfate (DHEA-S) and DHEA decreases markedly during aging, and low circulating levels of DHEA have been associated with a higher incidence of breast cancer in women. Using 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat as model, we have studied the effect of increasing serum levels of DHEA released from Silastic implants on the incidence of these tumors in the rat. Treatment with increasing doses of DHEA leading to serum DHEA levels comparable to those observed in normal adult women (7.1 +/- 0.6 nM and 17.5 +/- 1.1 nM) caused a progressive inhibition of tumor development from 68% bearing tumors in control animals to 22% and 11%, respectively. The average tumor area per rat decreased from 2.81 cm2 in intact control animals to 0.96 and 0.09 cm2 in the groups treated with the same doses of DHEA, respectively. The present data indicate that circulating levels of DHEA similar to those found in normal adult premenopausal women exert a potent inhibitory effect on the development of DMBA-induced mammary tumors in the rat, thus suggesting the possibility of a new and more physiological approach for the prevention of breast cancer in women.

A sub-6-GHz four-element multi-input multi-output (MIMO) slot antenna system was proposed in this study for fifth-generation (5G) tablet computers, where each antenna element was constructed using a slot structure. To effectively use the available space in a tablet and maximize the screen, we have deployed the MIMO antenna system on the left side-edge frame of the tablet. The MIMO antenna system measuring 37.2 × 7 mm 2 consists of two identical 13.6 × 7 mm 2 dual-slot-antenna units that are separated by 10 mm. The two closely spaced slot antennas in the same dual-slot-antenna unit are arranged asymmetrically mirrored of each other with respect to the system ground plane. Although the dual-slotantenna unit is very compact, the isolation between the two slot antennas in the same unit can be enhanced by using an ungrounded full-wavelength strip resonator. With the two ungrounded resonators in the MIMO slot antenna system, the simulated intra-unit isolations at the mid-band frequency can be enhanced by about 3.5 dB to meet the design requirement. As a byproduct, the two ungrounded resonators in the MIMO antenna system can also enhance the simulated mid-band antenna efficiency by about 4.5% and lower the worst simulated ECC by 0.195, from 0.518 to 0.323. This MIMO antenna system can support the frequency band of 3400-3600 MHz for 5G. In the operating band, the measured isolation is larger than 11 dB, and the measured antenna efficiency is larger than 40%. The envelope correlation coefficients (ECCs) calculated from the measured complex E-field radiation patterns are all smaller than 0.23, making the proposed design suitable for 5G mobile communications that require fast transmission. INDEX TERMS Tablet antennas, multi-input multi-output (MIMO) antennas, slot antennas, miniaturized antennas, 5G MIMO antenna system, envelope correlation coefficient (ECC).

Hemangiomas are uncommon benign tumors of the mediastinum. The definite diagnosis is sometimes difficult to make because of usually nonspecific features on single-phase contrast-enhanced computed tomography (CT) images. We described a 60-year-old woman suffering from a neck mass with progressive enlargement. On the dynamic CT study, the tumor showed peripheral nodular enhancement on early phase images and progressive centripetal fill-in on delayed phase images. Hemangioma was preoperatively diagnosed on the basis of this characteristic CT appearance. J Thorac Dis 2017;9(5):E412-E415 jtd.amegroups.com circumscribed mass in right superior mediastinum. The interface between the mass lesion and the thyroid gland was clear. A bronchogenic cyst was initially suspected according to its location and low attenuation on the pre-contrast images. However, due to a few peripheral enhancing foci seen on the post-contrast images, the possibility of a bronchogenic cyst was unlikely. In order to evaluate the nature and enhancing pattern of the mass, we performed a dynamic CT study with intravenous administration of 100 mL contrast medium at the rate of 3.5 mL/s by the powerful injector. Spiral scanning of the mediastinal mass was done repeatedly at 30 seconds, 1 minute and 3 minutes after injection. The mass revealed initially peripheral nodular enhancement with gradually central fill-in on the delayed phase images (Figure 2). The mediastinal hemangioma was first considered based on its enhancing pattern. Biopsy was not warranted due to high risk of major bleeding. The median sternotomy was performed for tumor resection. Grossly, the tumor revealed a well-circumscribed and hypervascular appearance (Figure 3). Pathological findings showed proliferation of small to medium-sized vessels with variable anastomosing channels ( Figure 4). The cavernous hemangioma was confirmed. DiscussionHypervascular mediastinal masses may show strong enhancement after contrast media administration. They are divided into anterior, middle and posterior according to their location. Each compartment of mediastinal mass contains different differential diagnoses (4). Several entities such as Castleman disease, paraganglioma, vascular malformation, ectopic parathyroid adenoma and hypervascular metastasis should be taken into account as hypervascular anterior mediastinal masses are mentioned.Mediastinal hemangiomas are very rare and consist of only 0.5% of mediastinal masses (5,6). According to International Society for the Study of Vascular Anomalies (ISSVA) classification, hemangiomas are classified into benign vascular tumors. They occur more frequently at the anterior mediastinum followed by posterior compartment. They also have a higher incidence before the age of 35 (5,7). At the histological examination, these tumors consist of interconnecting vascular spaces interposed with various stromal elements such as fat, myxoid and fibrous tissues. Organized thrombi in hemangiomas are frequent and may calcify as phleboliths that are a potentially dia...