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Biomedical subjects

C Giardina

Publications and source records attributed to C Giardina.

At least 55 records · Page 3Linked to original sources
PubMed1995

Sodium salicylate and yeast heat shock gene transcription.

The anti-inflammatory drug sodium salicylate modulates the activity of specific transcription factors in humans. Here we show that salicylate and sorbate, another organic acid, stimulate DNA binding by yeast heat shock transcription factor (HSF) in vivo. Surprisingly, salicylate inhibits heat shock gene transcription even in cells induced by a prior heat shock. This inhibition of transcription occurs at a step after HSF and transcription factor IID binding but before promoter melting by RNA polymerase. Salicylate appears to generate a tight binding but activation-impotent HSF by cytoplasmic acidification, since inhibiting proton efflux from cells triggers this same DNA binding and inhibition of heat shock gene expression.

Base Sequence↗
PubMed1995

Distribution of GAGA protein on Drosophila genes in vivo.

GAGA protein binds specific CT.GA-rich DNA sequences in vitro, and many of these sequences are required for transcription in vivo. GAGA protein has been implicated in the transcription of numerous Drosophila genes, including hsp70, hsp26, actin 5C, and Ubx. Here, we examine the in vivo distribution of GAGA protein on a number of Drosophila genes that do and do not have CT-rich sequences by use of a UV cross-linking technique. Prior to heat shock, GAGA protein is associated with the promoter regions of the uninduced hsp70 and hsp26 genes. Upon heat shock induction, GAGA protein is recruited to their transcription units with its distribution coincident with that of RNA polymerase II. The recruitment of GAGA protein to the hsp70 gene after an instantaneous heat shock occurs in a 5' to 3' manner with kinetics similar to RNA polymerase. GAGA protein has been shown to disrupt nucleosome both in vivo and in vitro. We propose that GAGA protein may function in vivo both by binding constitutively to its high-affinity binding sites and by spreading through the induced gene opening the chromatin structure allowing polymerase to elongate efficiently.

Actins↗
PubMed1995

Dynamic protein-DNA architecture of a yeast heat shock promoter.

Here we present an in vivo footprinting analysis of the Saccharomyces cerevisiae HSP82 promoter. Consistent with current models, we find that yeast heat shock factor (HSF) binds to strong heat shock elements (HSEs) in non-heat-shocked cells. Upon heat shock, however, additional binding of HSF becomes apparent at weak HSEs of the promoter as well. Recovery from heat shock results in a dramatic reduction in HSF binding at both strong and weak HSEs, consistent with a model in which HSF binding is subject to a negative feedback regulation by heat shock proteins. In vivo KMnO4 footprinting reveals that the interaction of the TATA-binding protein (TBP) with this promoter is also modulated: heat shock slightly increases TBP binding to the promoter and this binding is reduced upon recovery from heat shock. KMnO4 footprinting does not reveal a high density of polymerase at the promoter prior to heat shock, but a large open complex between the transcriptional start site and the TATA box is formed rapidly upon activation, similar to that observed in other yeast genes.

Base Sequence↗
PubMed1994

Endodermal sinus (yolk sac) tumor of the urachus.

A rare case of endodermal sinus (yolk sac) tumor of urachal remnants in a two-year-old infant is described. The tumor was located in the upper part of the bladder and appeared to arise from urachal remnants. The tumor could be entirely removed. The patient is free of tumor after three years and eight months follow-up.

Chemotherapy, Adjuvant↗
PubMed1993

Polymerase processivity and termination on Drosophila heat shock genes.

5,6-Dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) limits RNA polymerase II transcription to a gene's 5'-end. Transcription of the uninduced Drosophila hsp70 gene is likewise restricted to the 5'-end, where the polymerase resides in a paused state. Furthermore, paused elongation complexes formed on the uninduced hsp70 gene and in DRB-inhibited reactions can both be restarted by Sarkosyl or high salt. These similarities prompted us to explore whether these complexes were generated by a block at the same polymerase modification step. In vivo UV cross-linking and KMnO4 hyperreactive site mapping show that while the naturally paused polymerase is restricted to the first approximately 42 base pairs of hsp70, DRB treatment of heat-induced cells allows the polymerase to transcribe past this site. Therefore, the DRB-sensitive step is probably not rate-limiting for hsp70 transcription under uninduced conditions. DRB treatment did, however, lead to the reduction of KMnO4 hyper-reactivity on hsp70 and hsp26 in a region correlating with open polymerase and/or early elongation complexes, suggesting a site for the DRB-sensitive polymerase modification step. Finally, we used the techniques of polymerase-DNA cross-linking and KMnO4 hyper-reactive site mapping to analyze the natural polymerase termination process at the 3'-end of the hsp26 gene. The data obtained are consistent with polymerases terminating at multiple sites downstream of the polyadenylation site.

Animals↗
PubMed1993

DNA melting on yeast RNA polymerase II promoters.

Transcription-dependent DNA melting on the yeast GAL1 and GAL10 promoters was found to be more closely correlated with the TATA box than the transcription start site. On both these genes, melting begins about 20 base pairs downstream of the TATA box. Physical and genetic analyses suggest that RNA polymerase II associates with this region. Thus, the distance between promoter melting and the TATA box in yeast may be similar to that in higher eukaryotes, even though transcription initiates in a region about 10 to 90 base pairs farther downstream in yeast.

Base Sequence↗
PubMed1992

Promoter melting and TFIID complexes on Drosophila genes in vivo.

In vivo UV cross-linking and nuclear transcriptional run-on experiments have shown that a number of Drosophila genes possess an elongationally paused RNA polymerase on their 5' ends. Here, we examine in vivo promoters that do and do not possess paused polymerases using the single-stranded DNA-probing reagent KMnO4. Melted DNA helices are found associated with the pause site of the uninduced hsp70 and hsp26 heat shock genes and the constitutively expressed beta-1 tubulin gene. The histone H1 and H2B genes, which lack a paused polymerase, have no comparable region of melted DNA. Melting at the pause site persists upon heat shock induction of the hsp70 and hsp26 genes, indicating that pausing continues after gene activation. Interestingly, activation triggers additional melting, both at the start site (in the region where open complexes would be expected to form) and downstream of the uninduced pause site. In the course of our studies, we discovered that some T residues of the TATA box were protected from KMnO4 modification in both induced and uninduced cells. This protection appears to be a consequence of TFIID binding, as a similar protection pattern could be produced in vitro with purified protein.

Animals↗
PubMed1991

Tamoxifen binding sites heterogeneity in breast cancer: a comparative study with steroid hormone receptors.

Steroid receptors and tamoxifen binding sites (TBS) were assayed in the soluble fraction of 121 primary breast cancers. Scatchard analysis of TBS in high speed supernatant (100,000 g) showed one population of binding sites; however, biphasic plots were obtained in low speed supernatants (40,000 g). Isoelectric focussing of supernatants preincubated with radioactive tamoxifen identified two classes of TBS (pI 4.1-4.6) which have different binding affinities and bind neither oestradiol nor diethylstilbestrol. Association between TBS and steroid receptors was: TBS positive/progesterone receptor positive 32.6%, TBS positive/glucocorticoid receptor positive 52.7%, TBS positive/oestrogen receptor positive 60% and TBS positive/androgen receptor positive 72.2%. We conclude that heterogeneous TBS are present in low speed fractions and can be easily separated from the oestrogen receptor by isoelectric focussing. The association between TBS and steroid receptor status could be of clinical value in the management of primary breast cancer.

Breast Neoplasms↗
PubMed1990

[Nuclear morphometry and estrogen receptors in infiltrating ductal carcinoma of the breast].

In this study ten cases of breast infiltrating ductal carcinoma have been considered. In all of them the content of ER has been evaluated by using monoclonal antibodies. Five of them were ER positive and five were ER negative. For the morphometric study ten nuclei of each case have been considered. By using the S.A.M. (Shape Analytical Morphometry) work-station an analytical study of the nuclear shape was performed. The first step was the extraction of fundamental shape which describes the basic shape of original contour without its irregularities. It was obtained by using two parametric equations. The second step was the evaluation of shape asymmetry by S.A.E. (Shape Asymmetry Evaluator). Finally the contour irregularities were evaluated by Fourier analysis. Along with analytical parameters, dimensions (area, perimeter and maximum diameter) were considered too. All obtained data were submitted to univariate statistical analysis (Student's T test) to compare the two groups (ER positive and ER negative tumors). Area, perimeter and maximum diameter were significatively greater in ER negative cases while analytical parameters were not discriminant between the two groups.

Breast Neoplasms↗
PubMed1989

Relation between primary tumor shape and biological behavior in breast cancer.

The aim of this study was to investigate the biological significance of tumor shape in breast cancer by considering the shape not as a casual event but as an expression of the behavior and natural history of the tumor. The shape was studied by an analytical morphometry procedure and was related to axillary metastases, which up to now are the most meaningful prognostic factors in this disease. Fifty cases of infiltrating breast carcinoma (25 N+ and 25 N-) were investigated. The shape, studied on subgross sections of the tumor, was considered as the result of two components: the subtle contour irregularities and the main distortions of the figure. The procedures used allowed us to distinguish and to parametrize these two components in order to submit them to univariate analysis (Student's t test), a principal components analysis and, finally, a multivariate discriminant analysis (Hotelling test). The utilized analytical procedures by work-station S.A.M. (S.A.M. work station is a product of "Metamorphosis") consisted of three steps: 1) Extraction of tumor function curve obtained by Kth order polynominals which gives a smoothing effect to the original curve; 2) Evaluation of contour irregularities by Fourier harmonic analysis; 3) Evaluation of shape asymmetry by SAE (shape asymmetry evaluator). We considered also the roundness factors of the original and function curves and finally the maximum tumor diameter. Three parameters relating to contour irregularities (sum and mean value of Fourier harmonic amplitude and percentage of superimposed points) and parameters relating to main distortions of the figure (mean value of SAE) were highly significant (p less than 0.001). The roundness factor of the original curve was more significant (p less than 0.001) than that of the function curve (p less than 0.01) whereas maximum tumor diameter was not significant when tested by Student's t test. Multivariate discriminant analysis allowed 20% of error to be reached by using 3 parameters relating to the shape analysis and the two roundness factors. By using 8 parameters, including maximum tumor diameter, the percentage error was 16%. The results obtained, while they stress the usefulness of the employed procedure, reveal that shape of the tumor, together with its dimensions, is an important expression of the biological behavior relating to metastatic spread.

Analysis of Variance↗
PubMed1989

Differential diagnosis between thyroid follicular adenoma and carcinoma. Analytic morphometric approach.

In this study some nuclear dimensional and analytical parameters were evaluated in order to distinguish follicular atypical adenoma from follicular carcinoma of the thyroid. Eighty nuclei from carcinomas, 80 from adenomas and 80 from normal thyroid were studied. Analytical parameters obtained by the nuclear shape study (by S.A.M. system) as well as dimensional parameters were submitted to univariate statistical analysis. On the ground of our results atypical adenoma could be considered as an intermediate aspect of a progressive change from benign to malignant even if they are closer to normal thyroid than to carcinoma.

Adenocarcinoma↗
PubMed1985

Morphometric analytical evaluators of lymphoid populations in nonneoplastic lymph nodes.

A morphometric analysis using an Apple II microcomputer and shape analytical morphometry (SAM) software was performed of the nuclear shape in the lymphoid population of normal (nonneoplastic) lymph nodes to provide baseline parameters useful for distinguishing between different subtypes of lymphomas. Fourier harmonic analysis and two indices, a contour asymmetric evaluator (CAE) and a shape asymmetric evaluator (SAE), are proposed as non-dimensional shape parameters. Results obtained with the CAE and SAE indices indicate that they represent sensitive shape descriptors able to reveal even subtle irregularities of nuclear outline. With these parameters, centrocyte nuclei were easily differentiated from those of all other lymphoid cells while an interesting close relationship was found between lymphocytes and centroblasts. Lymphocyte nuclear shape was shown to be less regular than generally reported, suggesting the existence of subtle differences between stimulated and unstimulated nuclei. Immunoblast nuclei were shown to have the most regular shapes.

Cell Nucleus↗
PubMed1984

[Definition of the analytical relation between the surface and internal perimeter of seminiferous tubules from subjects with normal spermatogenesis].

Luminal tubular measurements are executed in testis with normal spermatogenesis to individuate, by computerized morphometric method, the ratio between these two values. Statistical evaluations and calculation of the regression curves demonstrate that this ratio is well described by means of an exponential equation which coefficients are determined. This parameter results very useful in the diagnosis of Sertoli cell only syndrome and maturation arrest both characterized by tubular lumen modification.

Biometry↗
PubMed1984

[Description of the shape of carcinomatous nodules of the breast by means of high degree polynomial equations and Fourier harmonic analysis].

Breast cancer nodule shape has been investigated by two analytical procedures: upper degree polynomials and harmonic Fourier analysis. An automized method (TV camera interfaced with a computer) has been employed to find the coefficients of kth order equation giving the best fit. Then the difference between real node contour and function curve has been calculated and submitted to harmonic analysis. This gives the sine/cosine coefficients of the two series and the amplitude of the harmonics. The results point out that no difference exists between metastatic and non metastatic tumors and suggest that parametrized descriptors calculated may represent a peculiar behaviour in the growth of the tumor.

Breast Neoplasms↗