Serum oestradiol in women with and without breast disease

It has been suggested that the percentage of non-protein-bound or free oestradiol (E2) is abnormally high in patients with breast cancer. In this study, the serum oestradiol profiles of a large group of women were analysed to determine whether a significant correlation could be found between serum oestradiol and various breast diseases. In addition oestradiol levels were measured in relation to sex hormone binding globulin (SHBG), albumin levels, oestrogen receptor status and family history of breast cancer. Serum samples were taken from a total of 300 women who had either no breast disease, benign breast disease or breast cancer. The percentage of free oestradiol was found to be highest in women with breast cancer, lowest in the control group and intermediate for the women with benign breast disease. These differences were most marked in post-menopausal women. The absolute values for total and free oestradiol were not statistically different in the three groups studied. There did not appear to be a correlation between oestrogen receptor (ER) concentration in breast cancer tissue and free E2 percentage levels. Women who had a family history of breast cancer did not appear to have higher percentage levels of free E2 than those with no such history. The presence of elevated proportions of free oestradiol in the serum of women with breast cancer may be significant in regard to understanding the aetiology of breast neoplasia. There also may be important implications for the use of this measurement in the earlier diagnosis and detection of breast cancer

Phosphatidylcholesterol bilayers. A model for phospholipid-cholesterol interaction

Aqueous dispersions of monovalent and divalent cation salts of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl) cholesterol form multilamellar vesicles as shown by freeze-fracture electron microscopy, by electron micrographs of the negatively stained liposomes, and by swelling curves of liposomes in hypoosmotic medium. Differential scanning calorimetry reveals that aqueous dispersions of divalent metal salts of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)-cholesterol undergo a characteristic thermotropic phase transition with a relatively large cooperative unit (n > 250 for the calcium salt). In contrast, monovalent cation salts of O-(1,2-dipalmitoyl-sn-glycerol-3-phosphoryl)cholesterol do not show a thermotropic phase transition under comparable conditions. The molecular area of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol in a monolayer is the same in the presence and absence of Ca2+, and is virtually equal to the area of an equimolar mixture of dipalmitoyl phosphatidic acid and cholesterol. To account for the novel state induced by Ca2+ on aqueous dispersions of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol (i.e., bilayer organization and highly cooperative phase transition), a linear array model is proposed in which Ca2+ bridges adjacent arrays of O-(1,2-dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol molecules, thus freezing the acyl chains in their normal state. One of the main corollaries of the model is that the cooperative unit for a thermotropic phase transition is essentially one-dimensional, rather than a two-dimensional matrix. O-(1,2-Dipalmitoyl-sn-glycero-3-phosphoryl)cholesterol is proposed as an orientationally and conformationally restricted analog of glycerophospholipid plus cholesterol in bilayers

Earthquake source parameters at the sumatran fault zone: Identification of the activated fault plane

Fifteen earthquakes (Mw 4.1-6.4) occurring at ten major segments of the Sumatran Fault Zone (SFZ) were analyzed to identify their respective fault planes. The events were relocated in order to assess hypocenter uncertainty. Earthquake source parameters were determined from three-component local waveforms recorded by IRIS-DMC and GEOFON broadband IA networks. Epicentral distances of all stations were less than 10°. Moment tensor solutions of the events were calculated, along with simultaneous determination of centroid position. Joint analysis of hypocenter position, centroid position, and nodal planes produced clear outlines of the Sumatran fault planes. The preferable seismotectonic interpretation is that the events activated the SFZ at a depth of approximately 14-210 km, corresponding to the interplate Sumatran fault boundary. The identification of this seismic fault zone is significant to the investigation of seismic hazards in the region