Noninvasive dopamine determination by reversed phase HPLC in the medium of free-floating roller tube cultures of rat fetal ventral mesencephalon: a tool to assess dopaminergic tissue prior to grafting

We used a retroviral vector containing a human gamma-interferon (gamma-IFN) gene to transduce 13 renal carcinoma cell lines. The transduction efficiencies ranged from 0% to 60%, as determined by using an analogous vector containing the LacZ marker gene. In addition, gene-transferred resistance to the antibiotic neomycin was used to select for transduced cells. Nine of 13 lines were successfully transduced. Transduction was associated with the morphologic change of elongation, and there was a marked decrease in cell growth rate. Transduced cells secreted varying amounts (20-1076 pg/10(6) cells/d) of gamma-IFN as measured by enzyme-linked immunosorbent assay for at least 2 to 3 weeks after transduction (including 1 day of transduction, 6-7 days of selection, and an additional 8-12 days before the first passage of the transduced cells). Human leukocyte antigen (HLA) class II expression was markedly increased in six of seven cell lines; HLA class I expression was significantly increased in two of eight lines. Transduced cells that were subjected to cryopreservation after irradiation still produced gamma-IFN and expressed HLA class I and II antigens, although generally at lower levels than before these manipulations. This study confirms that retroviral vector transduction of the human gamma-IFN gene into renal carcinoma cells is feasible and associated with persistent production of gamma-IFN and increased expression of HLA class I and II molecules, and these effects are retained after irradiation and cryopreservation. This suggests that an autologous tumor cell vaccine trial with irradiated gamma-IFN gene-transduced renal carcinoma cell is rationale and feasible.     

The internal mammary artery 'string phenomenon'. Analysis of 10 cases

The internal mammary artery (IMA) string sign has been described as a narrowing of IMA grafts in the late course after coronary artery bypass grafting. It has been assumed that this phenomenon was due to competitive flow in grafts connected to only mildly stenosed coronary arteries. We analyzed 10 cases of IMA string sign operated on between March 1988 and June 1991. Bilateral IMA was used in six cases and unilateral IMA in four. The mean interval between operation and reangiography was 14 +/- 11 months. String sign of the whole length of the IMA was detected in nine cases, and of the distal part between two sequential anastomoses in one. In all cases, the stenosis of the vessel bypassed with the narrowed graft proved to be only mild (50% or less) at reangiography. In all six cases with bilateral IMA grafts, the contralateral IMA was widely patent. These were all connected to highly stenosed or occluded coronary arteries. With respect to this observation, there is a high index of suspicion that the string phenomenon occurs due to competitive flow in only mildly stenosed coronary arteries. We decided, for our strategy in coronary artery surgery, still to aim at complete revascularization using IMAs as much as possible, but to avoid connecting IMA grafts to only mildly or moderately stenosed coronary arteries.     

Acquired and naturally occurring resistance of thyroid follicular cells to the growth inhibitory action of transforming growth factor-beta 1 (TGF-beta 1)

While the multifunctional proteins of the transforming growth factor-beta (TGF-beta) family have a potent antiproliferative effect on thyroid follicular cell growth, increased expression of TGF-beta in proliferating thyroid cells and in thyroid tumours has recently been described, suggesting a secondary counter-regulatory role of these proteins. We have studied further this apparent paradox in vitro using FRTL-5 cells, 5 continuous cell strains from feline multinodular goitres (MNG) and 29 primary cultures prepared from human MNG. While dose dependent inhibition of FRTL-5 cell growth was confirmed, a variable fraction of these cells was naturally resistant towards TGF-beta 1, thus explaining the large interassay variability of growth inhibition (36 to 98% within 2 days, n = 19). After 40 days of continuous exposure, FRTL-5 cells became fully refractory towards TGF-beta 1 inhibition, due to the selective growth of naturally resistant subclones, as demonstrated for example by microscopic observation of three-dimensionally growing collagen-embedded cell clusters. The refractoriness could still be demonstrated even after several cell passages. In addition, 2 out of 5 feline thyroid cell strains obtained from feline MNG and 18 out of 29 primary cultures from human MNG showed a high degree of refractoriness towards TGF-beta. We conclude that constitutively TGF-beta resistant cells may occur in thyroid glands and that persistent TGF-beta refractoriness may secondarily be acquired. Resistant cells may escape regular growth control mechanisms and hence may contribute to the notorious heterogeneity of thyroid growth and to nodular transformation.     

Argumentation-Based Ontology Engineering

The Diligent argumentation framework helps capture design deliberations in ontology-engineering discussions. It makes consensus-building tasks more efficient and provides detailed guidance for nonexperts. The semantic Web envisions an infrastructure in which humans and machines seamlessly exchange information on the Web. During the discussions participants raise new issues or elaborate on existing ones. Once a discussion evolves, participants can group issues and act on them accordingly.     

Direct observation of liquid crystals using cryo‐TEM: Specimen preparation and low‐dose imaging

Liquid crystals (LCs) represent a challenging group of materials for direct transmission electron microscopy (TEM) studies due to the complications in specimen preparation and the severe radiation damage. In this paper, we summarize a series of specimen preparation methods, including thin film and cryo‐sectioning approaches, as a comprehensive toolset enabling high‐resolution direct cryo‐TEM observation of a broad range of LCs. We also present comparative analysis using cryo‐TEM and replica freeze‐fracture TEM on both thermotropic and lyotropic LCs. In addition to the revisits of previous practices, some new concepts are introduced, e.g., suspended thermotropic LC thin films, combined high‐pressure freezing and cryo‐sectioning of lyotropic LCs, and the complementary applications of direct TEM and indirect replica TEM techniques. The significance of subnanometer resolution cryo‐TEM observation is demonstrated in a few important issues in LC studies, including providing direct evidences for the existence of nanoscale smectic domains in nematic bent‐core thermotropic LCs, comprehensive understanding of the twist‐bend nematic phase, and probing the packing of columnar aggregates in lyotropic chromonic LCs. Direct TEM observation opens ways to a variety of TEM techniques, suggesting that TEM (replica, cryo, and in situ techniques), in general, may be a promising part of the solution to the lack of effective structural probe at the molecular scale in LC studies. Microsc. Res. Tech. 77:754–772, 2014. © 2014 Wiley Periodicals, Inc.     

Electron beam-induced changes in vitreous sections of biological samples

Nonpretreated high pressure frozen samples of Zea mays, cartilage and human erythrocytes were cryosectioned and observed at 110 K in a cryoelectron microscope. Changes induced by medium doses of electron irradiation (< 10 ke nm^?2) are described. After some ke nm^?2, the most conspicuous cutting artefacts are erased to a large extent and the visibility of the cell organelles is improved. The sections, compressed in the cutting direction by the sectioning process, shrink once more, in the same direction, when irradiated. This shrinkage depends on the section support and on how the section is adsorbed to it. Shrinkage is not uniform; it is most pronounced in mitochondria, condensed chromatin and nucleolus. This differential shrinkage improves the visibility of major structures on the section and, as a result, ‘nicer’ images are recorded. However, this apparent improvement is a beam-induced artefact that must be paired with a loss of high resolution information.