The significance of immunological investigations during radiotherapy for breast cancer (author's transl)

The immune profile was controlled in 50 patients with breast cancer over a period of 5 years. No useful method for early detection, prognosis or exacerbation of disease could be developed from these findings for routine clinical work.     

The effect of an oxide layer on the ohmicity of contacts to amorphous silicon

Surface oxide layers on CVD films of amorphous silicon can cause the metallic contacts to the films to be non-ohmic. Dipping an amorphous silicon sample in a solution of hydrofluoric acid prior to electrode deposition removes the oxide layer and permits the formation of ohmic contacts.     

Temperature dependence of the critical electron exposure for hydrocarbon monolayers

Effects of electron-beam-induced radiation damage in monolayers of several saturated fatty acids and related molecules have been measured by observation of the fading of electron diffraction patterns produced by the crystalline monolayers. Measurements were made with the specimens at temperatures in the range from about 6 to 310 K. Near room temperature, exposures of approximately 50 and 200 electrons/nm² are required to reduce the intensities of the diffraction patterns of stearic and behenic acids, respectively, to 1/e of their initial intensities. These critical exposures increase smoothly as the temperature decreases, to 1600 and 2200 e/nm², respectively, at a specimen temperature of about 6 K. A strong correlation was observed between the critical exposures and melting temperatures of the various specimens examined. These results can be interpreted in terms of radiolysis pathways that are highly specific to hydrocarbons.     

Influence of serum, estrogen, and gonadotropins upon growth and progesterone secretion by cultures of granulosa cells from small porcine follicles

Granulosa cells from small (less than 2mm) antral porcine follicles were grown in culture to study the effects of various hormones on growth, morphology and progesterone secretion. Culture medium 199D + 4% serum was found to be most suitable since it maintained a fairly constant cell population. Estradiol (1mug/ml) and human FSH stimulated cell growth. LH and FSH stimulated progesterone secretion and induced morphological changes associated with luteinization. Estradiol (0.1 mug/ml) inhibited progesterone secretion by granulosa cells.     

Using Electronic Surveys in Organizational/Employee Communication Research: A Study at GE's Global Research Center

This study explores methodological issues that communication scholars and practitioners face when administering electronic surveys within for-profit organizations. In 2000, the researchers conducted a series of three cross-sectional studies within General Electric's (GE) Global Research Center. The Center is located in Niskayuna, NY. An equivalent version of a communication survey was administered electronically to a random stratified sample of GE employees three times that year. Each employee sample was subject to a different survey intervention: no intervention, follow-up reminder email only, and leader pre-announcement email plus a follow-up reminder. The researchers also recorded how long it took respondents to return their surveys. The highest response rate (41%) occurred in the third intervention. Across the three administrations, 465 GE employees completed the surveys; 98% of respondents returned their surveys electronically rather than printing out their responses and sending them to the researcher by postal mail. The article concludes with implications and suggestions for those who administer electronic surveys within organizations.     

Relationship between lateral subluxation and widening of medial joint space in Legg-Calvé-Perthes disease

Fifty-five patients (61 affected hips and 49 unaffected hips) with Perthes disease were reviewed to evaluate the relationship between widening of medial joint space and lateral subluxation of the femoral head in radiographs. The components of the medial joint space were evaluated by using T1, T2, proton, and Gd-enhanced T1WI magnetic resonance images (MRI). The widened medial joint space in radiographs was filled with overgrown cartilage at the initial stage (27 hips) in MRI, with both overgrown cartilage and widened true medial joint space at the fragmentation stage (23 hips) and widened true medial joint space at the healing stage (11 hips). Between affected hips and unaffected hips, the mean difference of medial joint space in radiographs between hips at the initial stage and at the fragmentation stage was 2 and 4.5 mm, respectively; the mean difference in percentage of lack of coverage of the femoral head between hips at the initial stage and at the fragmentation stage was 3 and 15%, respectively. During the healing stage, widening of the medial joint space decreased or normalized because of ossification of overgrown cartilage despite the existence of lateral subluxation because of coxa magna. We concluded that widening of the medial joint space may be used as an index of lateral subluxation at only the fragmentation stage in Perthes disease.     

Changes in RBE of 14-MeV (d + T) neutrons for V79 cells irradiated in air and in a phantom: is RBE enhanced near the surface?

PURPOSE: The relative biological effectiveness (RBE) for inactivation of V79 cells was determined as function of dose at the Heidelberg 14-MeV (d + T) neutron therapy facility after irradiation with single doses in air and at different depths in a therapy phantom. Furthermore, to assess the reproducibility of RBE determinations in different experiments we examined the relationship between the interexperimental variation in radiosensitivity towards neutrons with that towards low LET 60Co photons. METHODS: Clonogenic survival of V79 cells was determined using the colony formation assay. The cells were irradiated in suspension in small volumes (1.2 ml) free in air or at defined positions in the perspex phantom. Neutron doses were in the range, Dt = 0.5-4 Gy. 60Co photons were used as reference radiation. RESULTS: The radiosensitivity towards neutrons varied considerably less between individual experiments than that towards photons and also less than RBE. However, the mean sensitivity of different series was relatively constant. RBE increased with decreasing dose per fraction from RBE = 2.3 at 4 Gy to RBE = 3.1 at 0.5 Gy. No significant difference in RBE could be detected between irradiation at 1.6 cm and 9.4 cm depth in the phantom. However, an approximately 20% higher RBE was found for irradiation free in air compared with inside the phantom. Combining the two effects, irradiation with 0.5 Gy free in air yielded an approximately 40% higher RBE than a dose of 2 Gy inside the phantom. CONCLUSION: The measured values of RBE as function of dose per fraction within the phantom is consistent with the energy of the neutron beam. The increased RBE free in air, however, is greater than expected from microdosimetric parameters of the beam and may be due to slow recoil protons produced by interaction of multiply scattered neutrons or to an increased contribution of alpha particles from C(n, alpha) reactions near the surface. An enhanced RBE in subcutaneous layers of skin combined with an increase in RBE at low doses per fraction outside the target volume could potentially have significant consequences for normal tissue reactions in radiotherapy patients treated with fast neutrons.