HER-2/neu oncogene expression and DNA ploidy in normal human kidney and renal cell carcinoma.

Using flow cytometry (FCM), we have investigated both the DNA content (stained with propidium iodide) and HER-2/neu oncogene expression (revealed by means of an anti-HER-2/neu monoclonal antibody) in neoplastic and non-neoplastic kidney samples from 20 patients with renal cell carcinoma. All the non-neoplastic samples and 15/20 (75%) renal cell cancers showed diploid modal DNA content while the remaining 5 neoplastic sample (25%) showed both diploid and hyperdiploid cell populations. In normal kidney the level of HER-2/neu oncoprotein was low (median fluorescence values in arbitrary units = 7.5 AU, range: 4-10 AU). In diploid renal cancers the level of HER-2/neu was slightly increased (median fluorescence values = 20 AU, range: 9.5-30 AU) (p < .005). The relationship of HER-2/neu expression to the cell cycle in these tumor samples is not clear since most of the cells express the antigen in all phases of the cell cycle. On the other hand, there is an association between HER-2/neu expression and abnormal DNA content suggesting that aneuploid pattern may be biologically related to overexpression of the HER-2/neu gene.     

Effects of lead on the nuclear repetitive DNA of the mossFunaria hygrometrica (Bryophyta)

Summary Funaria hygrometrica gametophytes were grown in in vitro controlled systems in the presence and absence of lead. Their nuclear genomes were then analyzed directly in situ with A+T and G+C specific fluorochromes, image analysis and statistical data elaboration by specific software, in order to characterize the different fractions of repetitive DNA. The results reveal qualitative and quantitative differences between the nuclear genomes of lead-stressed and unstressed individuals. These differences seem to consist of a significant increase in G+C rich repetitive DNA sequences in nuclei of the stressed individuals. These sequences form well defined agglomerates, generally situated adjacent to the nucleolar region, which increase in both size and number in the presence of lead. Some hypotheses are discussed.Abbreviations DAPI 4,6-diamidino-2-phenylindole - BBM bold basal medium     

DC-ELF characterization of random mixtures of piecewise nonlinear media

Biological tissues are ensembles of linear and nonlinear, symmetric and asymmetric constituents. As far as their electromagnetic characterization is concerned, they can be modeled as microscopic mixtures of the corresponding material media. Any medium volume can be properly discretized in a finite number of cells which can be modeled as an equivalent three dimensional network of lumped components, in order to characterize its electromagnetic behavior at wavelengths much longer than the relevant average linear size of the constitutive cells. Therefore, any mixture and the corresponding tissue can be characterized in terms of its effective conductance at extremely low frequency, with respect to a reference set of electrodes (ports of the equivalent network). When the above procedure is implemented for evaluating any of the aforesaid conductances, a resulting nonlinear characteristic should be expected. In reality, it may happen that the effect of the constitutive nonlinearities and the related asymmetries are smeared out by the randomness of the interconnections of the lumped components, leading at a macroscopic level to an isotropic constant equivalent conductance, i.e., to an isotropic constant equivalent conductivity of the mixture. The closed form analysis of a random network of nonlinear (piecewise linear) resistors offers a simple but clear cut example of such a property. This result, if extrapolated to biological media, suggests a new hint for explaining why there is no inconsistency between the typical electric characterization of biological tissues as almost linear macroscopic media, by means of their effective conductivity and permittivity, and the nonlinearities of the biochemical processes occurring in the tissue cells. In fact, the nonlinearities may not be observable by means of macroscopic electrical measurements because of the randomized spatial orientation and location of the processes.     

Nackt (nkt), a new hair loss mutation of the mouse with associated CD4 deficiency

 A spontaneous recessive mutation named nackt (symbol: nkt) affecting hair growth and T-cell development was discovered in a moderately inbred stock of mice. Skin lesions were characterized by sparse rough coat, bare patches around the eyes and neck, and a scratching behavior throughout life. Fluorescence-activated cell sorter analysis indicated a deficiency in the CD4⁺ 8^– T-cell subset in the thymus and a marked decrease in CD4⁺ T cells in peripheral lymphoid organs. Linkage analysis using a set of molecular markers and an F₂ intersubspecific cross indicated that the mutation maps to the central region of mouse chromosome 13, in a region homologous to human chromosome 5q22-q35. Received: 15 July 1998 / Revised: 27 October 1998