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C Dani

Publications and source records attributed to C Dani.

At least 91 records · Page 5Linked to original sources
PubMed1986

Adipose cell differentiation: evidence for a two-step process in the polyamine-dependent Ob1754 clonal line.

A subclone of preadipocyte Ob17 cells has been isolated (Ob1754 clonal line). Confluent Ob1754 cells treated with an inhibitor of spermidine and spermine synthesis, methylglyoxal bis(guanylhydrazone), were totally dependent upon putrescine addition for the expression of glycerol-3-phosphate dehydrogenase which behaved as a late marker of adipose conversion. Under these conditions, the early expression of lipoprotein lipase during growth arrest remained unchanged. Studies at the mRNA level showed that the expression of unidentified pOb24 and pGH3 mRNAs, which was parallel to that of lipoprotein lipase, is independent of polyamine addition whereas the late emergence of glycerol-3-phosphate dehydrogenase mRNA was putrescine-dependent and co-ordinated with the expression of pAL422 mRNA encoding for a myelin-P2 homologue [Bernlohr, Angus, Lane, Bolanowski & Kelly (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 5468-5472]. The appearance of lipoprotein lipase preceded DNA synthesis and post-confluent mitoses which were both putrescine-dependent and which took place before the appearance of glycerol-3-phosphate dehydrogenase. Thus the adipose conversion of Ob1754 cells involves the expression of at least two separate sets of markers which are differently regulated.

Adipose Tissue↗
PubMed1986

Growth hormone regulation of the expression of differentiation-dependent genes in preadipocyte Ob1771 cells.

The adipose conversion of Ob1771 preadipocytes, during exposure to medium containing bovine serum and supplemented with growth hormone, is accompanied by the acquisition of phenotypic markers and the increased accumulation of specific mRNAs. The expression of lipoprotein lipase, and that of unidentified pOb24 and pGH3 mRNAs, are early events which are independent of growth hormone supplementation. By contrast, the late expression of mRNAs encoding for glycerol-3-phosphate dehydrogenase and p422 protein (a myelin-P2 homologue) and that of glycerol-3-phosphate dehydrogenase activity require the presence of growth hormone. The abundance of beta-actin mRNA does not change during differentiation. Runoff transcription by nuclei isolated from untreated or growth hormone-treated cells reveal little or no change in the rates of transcription of pOb24, pGH3 and beta-actin mRNAs. By contrast, the transcription rate of the p422 gene increases markedly (greater than 6-fold) in nuclei of growth hormone-treated cells. However, the p422 mRNA is more abundant than would be predicted by its nuclear transcription alone, suggesting, in Ob1771 cells exposed to growth hormone, that there is a post-transcriptional level of control. These results indicate that the permissive role of growth hormone during adipose cell differentiation is related to terminal events only and that its effects can be seen both at the protein and mRNA level. These results strongly suggest that an increased rate of specific transcription is primarily responsible for the accumulation of mRNAs during exposure to growth hormone.

Adipose Tissue↗
PubMed1986

Expression of the phosphoenolpyruvate carboxykinase gene and its insulin regulation during differentiation of preadipose cell lines.

The adipose conversion of Ob1771 and 3T3-F442A preadipose cells is accompanied by the expression of the phosphoenolpyruvate carboxykinase (PEPCK) gene. The PEPCK mRNA is absent from growing, undifferentiated Ob1771 and 3T3-F442A cells as well as from non-differentiating 3T3-C2 cells. It is present in differentiated Ob1771 and 3T3-F442A cells as well as in liver, kidney and white adipose tissue from mouse. Transcriptional run-off measurements in nuclei isolated from undifferentiated and differentiated Ob1771 and 3T3-F442A cells reveal that the PEPCK gene transcription is activated during differentiation. Studies of the time course of changes indicate that the emergence of PEPCK mRNA takes place in parallel to mRNA encoding for a 28 kDa protein (28 K mRNA) but later than that encoding for glycerol-3-phosphate dehydrogenase (GPDH mRNA). Insulin leads to an increase in the content of PEPCK and GPDH mRNAs with half-maximally effective concentrations of 0.5 and 5 nM for GPDH mRNA and PEPCK mRNA, respectively. Thus, in contrast to rat hepatoma cells, insulin exerts in adipose cells a positive regulation on the expression of the PEPCK gene.

Actins↗
PubMed1986

Coupling of growth arrest and expression of early markers during adipose conversion of preadipocyte cell lines.

After growth arrest at the entry of the S phase of the cell cycle, Ob1771 and 3T3-F442A cells, but not 3T3-C2 cells, accumulate lipoprotein lipase and pOb24 mRNA that are early markers of adipose conversion. Removal of the single- or double-thymidine block when cultured cells are present at low density leads first to DNA synthesis and growth resumption, then to a continuous proliferation and a rapid disappearance of these markers. By contrast, growth-arrested Ob1771 cells reinoculated at high density undergo a single round of cell division, maintain high levels of early marker(s) and acquire with time both glycerol-3-phosphate dehydrogenase and lipids. Thus, depending upon the conditions in culture, growth-arrested cells can undergo either a dedifferentiation leading to a loss of early markers or a terminal differentiation leading to the acquisition of late markers.

Adipose Tissue↗
PubMed1985

Various rat adult tissues express only one major mRNA species from the glyceraldehyde-3-phosphate-dehydrogenase multigenic family.

We have isolated and sequenced a full-length cDNA clone encoding rat glyceraldehyde-3-phosphate-dehydrogenase (GAPDH, E.C.1.2.1.12). The entire mRNA is 1269 nucleotides long exclusive of poly(A) and contains respectively 71 and 196 bases of 5' and 3' non-coding regions. Primer extension as well as S1 nuclease protection experiments clearly established that a single (or at least a highly prominent) GAPDH mRNA species is expressed in all rat tissues examined. This sequence allowed the determination of the hitherto unknown primary structure of rat GAPDH which is 333 aminoacids long. Comparison between GAPDH sequences from rat, man and chicken revealed a high degree of sequence conservation at both nucleotide and protein levels.

Amino Acid Sequence↗
PubMed1985

Increased rate of degradation of c-myc mRNA in interferon-treated Daudi cells.

The recent observation made in our laboratory that cellular myc (c-myc) mRNA has a very short half-life in a variety of normal and transformed human cells emphasized the potential importance of post-transcriptional regulation of c-myc gene expression. Jonak and Knight [Jonak, G. J. & Knight, E., Jr. (1984) Proc. Natl. Acad. Sci. USA 81, 1747-1750] have reported a selective reduction of c-myc mRNA accumulation in lymphoblastoid Daudi cells treated with human beta interferon. This provided a suitable situation in which to examine a possible action of negative modulators of c-myc expression at the level of mRNA stability. Our results confirm the observation by Jonak and Knight that c-myc mRNA level is depressed in cells treated with beta interferon and extend it to alpha 2 interferon. Furthermore, we now demonstrate that interferon has no effect on c-myc transcription rate in isolated nuclei but rather reduces the half-life of its mRNA. Conversely, we show that it increases the level of HLA-A2 mRNA by stimulating its transcription.

Gene Expression Regulation↗
PubMed1984

Characterization of the transcription products of glyceraldehyde 3-phosphate-dehydrogenase gene in HeLa cells.

We have partially purified the messenger RNA coding for glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) from HeLa cells and obtained a cDNA clone containing part of its sequence. Using this clone to probe electrophoregrams of RNA transferred to nitrocellulose, we have investigated the characteristics of nuclear and cytoplasmic transcripts in these cells. In the cytoplasm, nature GAPDH mRNA was detected in Northern blots as an intense band, apparently unique, of approximately 1400 nucleotides. The half-life of this mRNA was determined both from the decay kinetics, after a chase with actinomycin D, and from the labeling kinetics during an accumulation experiment. Both kinds of experiments yielded a half-life value of about 8 h, while the accumulation experiment indicated that steady-state GAPDH mRNA amounted to about 1.6% of cytoplasmic poly(A)-rich RNA. Much longer species, likely to be restricted to the nucleus, were also detected in RNA extracted from total cells. At least three discrete species of 1600, 4000, 5800 and 6800 bases were observed above a trailing background extending up to about 8000 bases. This value is commensurate with a functional size of the GAPDH transcription unit in the order of 13000 bases, which we determined by measuring the size of the ultraviolet inactivation target. Until direct evidence can be obtained at the genomic level, the present results provide the first clue to the existence of introns, presumably at least four, in a GAPDH gene from a higher eucaryote.

Amino Acid Sequence↗
PubMed1984

Post-transcriptional regulation of glyceraldehyde-3-phosphate-dehydrogenase gene expression in rat tissues.

We have isolated and identified cDNA clones containing part of the coding sequence for rat glyceraldehyde-3-phosphate-dehydrogenase (GAPDH, E.C. 1.2.1.12). By using one of these clones as a probe, we have shown that: i) the abundance of GAPDH mRNA is different in various tissues of the adult rat and in good correlation with the abundance of the enzyme; ii) the transcription rates are quite similar in all tissues tested. We therefore conclude that the tissue-specific differential GAPDH gene expression is regulated by adjusting the abundance of its mRNA at the post-transcriptional level.

Animals↗
PubMed1984

Complete nucleotide sequence of the messenger RNA coding for chicken muscle glyceraldehyde-3-phosphate dehydrogenase.

The complete nucleotide sequence for chicken glyceraldehyde-3-phosphate dehydrogenase mRNA has been determined, thereby extending the longest such sequence previously reported (Dugaiczyk et al. Biochemistry, 1983, 22, 1605-1613) by 27 nucleotides. The complete mRNA with the exclusion of poly(A) is 1284 nucleotides long and contains 56 nucleotides of 5' non coding sequence and 229 nucleotides of 3' non coding region. Knowledge of the complete sequence allows us to propose secondary structures models which may be of biological significance.

Animals↗
PubMed1984

Extreme instability of myc mRNA in normal and transformed human cells.

To address the possibility that the expression of the myc gene might be regulated at a post-transcriptional level, we have investigated the half-life of myc mRNA in various cells. Our survey included normal human embryonic fibroblasts as well as transformed human cells of various origins: cervix carcinoma (HeLa), breast carcinoma (MCF7), Burkitt lymphoma (Daudi), and promyelocytic leukemia (HL60). All these cells revealed an extreme instability of myc mRNA (half-life, approximately equal to 10 min), suggesting that the control of myc mRNA degradation might be a general means (although not necessarily exclusive) of regulating both the level and the timing of myc gene expression. Inhibition of protein synthesis resulted in a dramatic stabilization of myc mRNA in HeLa, MCF7, and HL60 cells, suggesting that the controlling element might itself be, at least in these cells, a protein of rapid turnover. This finding opens the way to studying the mechanism of myc mRNA inactivation in these different cell types. However, protein synthesis inhibition had no effect on myc mRNA instability in other transformed (Daudi) cell lines as well as normal embryonic human fibroblasts. These different types of behavior suggest that the post-transcriptional control of myc gene expression might involve multiple factors that would be differently affected in various cell types.

Cell Transformation, Neoplastic↗
PubMedDate not supplied

Unusual abundance of vertebrate 3-phosphate dehydrogenase pseudogenes.

Only one gene coding for glyceraldehyde 3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12), a key enzyme in the control of glycolysis, is known to be functional in man, mouse, rat and chicken. The gene has been localized to chromosome 12 in human and chromosome 6 in mouse. Only a single mRNA species has been found in chicken and rat. However, analysis of genomic DNA blots of various species with a cloned GAPDH cDNA probe has revealed large differences in the level of reiteration, ranging from one to over 200 copies. On this basis, we have grouped these organisms into three classes according to the number of GAPDH-related sequences they contain; one class with a unique representation (chicken), another class of relatively low reiteration (10-30 copies in man, hare, guinea-pig and hamster) and a third class of high reiteration (greater than 200 copies in mouse and rat). The third class represents the first reported occurrence of such an extreme number of pseudogenes related to an enzyme-coding gene and suggests that a dramatic amplification event took place between 15 and 25 million years ago.

Animals↗
PubMedDate not supplied

c-myc gene is transcribed at high rate in G0-arrested fibroblasts and is post-transcriptionally regulated in response to growth factors.

There is increasing evidence that at least some of the cellular homologues to retroviral oncogenes (c-onc or proto-oncogenes) are directly linked to the control of cell growth (for a review see ref. 1). Among these, c-myc, the cellular homologue to the avian myelocytomatosis virus (MC29) oncogene, has been shown to express high levels of mRNA during early G0/G1 phase after mitogenic stimulation of T lymphocytes by concanavalin A or of fibroblasts by platelet-derived growth factor (PDGF) or serum. An attractive model proposed for this regulation is that the c-myc gene is strongly repressed in cells arrested in the G0 phase of the cell cycle by a growth factor-sensitive repressor. We have investigated an alternative model of post-transcriptional regulation. This latter model leads to two testable predictions. First, that c-myc mRNA should be unusually unstable, which we have confirmed. And second, that there would be a high level of constitutive expression, a situation opposite to that implied by the repressor model. Here we report that c-myc gene is indeed transcribed at a high rate in G0-arrested chinese hamster lung fibroblasts, although the level of mature c-myc mRNA is barely detectable. The early and dramatic increase in c-myc mRNA levels when these resting cells are stimulated by growth factors is not accompanied by any appreciable change in the transcription rate of c-myc gene. Taken together these findings support a model of post-transcriptional regulation of c-myc expression at the level of mRNA degradation.

Animals↗
PubMedDate not supplied

Increasing dose of continuous infusion ifosfamide and fixed dose of bolus epirubicin in soft tissue sarcomas. A study of the Italian group on rare tumors.

PURPOSE: To evaluate the maximum tolerated doses (MTD) of ifosfamide when given as a continuous infusion and in combination with fixed doses of bolus 4'-epidoxorubicin in advanced previously untreated adult soft tissue sarcoma patients. METHODS: Treatment consisted of epidoxorubicin, 60 mg/m2 days one and two, and ifosfamide, 1.5 g/m2 every 12 hrs as a 72-hr infusion, at the first level. Further levels of ifosfamide were defined as increments of 12 hrs of the same infusion program. G-CSF 300 microg/die was administered from days +7 to +14. Dose-limiting toxicity (DLT) was defined as: G4 leukopenia or thrombocytopenia of > or =5 days; any G3 neuro or nephrotoxicity; G4 toxicity of any kind. Patients had to complete at least 2 consecutive cycles, and MTD was defined as the level in which 20% of patients developed a DLT; 10-15 patients were entered in each level. RESULTS: First level: overall, 13 patients entered, 3 were not assessable for MTD, and only one developed a DLT. Second level: 18 patients entered, 3 were not assessable for MTD. Hematologic DLT was observed in 3/15 assessable patients. Therefore, the MTD was found at the ifosfamide level of 10.5 g/m2 given in 84 hrs. Eight patients of 29 assessable for response achieved an objective response: 1 complete and 7 partial. The overall response rate was 28% (95% CI: 13-47%). CONCLUSIONS: If we accept 4-day G4 leukopenia as a reliable cutoff for safety, ifosfamide intensification cannot be substantially exploited over already available schedules with the combination of ifosfamide and anthracyclines.

Adult↗
PubMedDate not supplied

[The micro-ESR with the capillary tube inclined to 45 degrees in the "sepsis screen" of neonatal infection due to beta-hemolytic B-group Streptococcus].

The authors describe the advantages of a new method to determinate the erythrocyte sedimentation rate (micro-ESR) during neonatal GBS infections. They utilize a capillary tube placed at a 45 degrees angle and have the results of this test only after 15 minutes. The micro-ESR is proposed as a simple and quick method of sepsis screen in term and preterm newborns.

Blood Sedimentation↗
PubMedDate not supplied

[Computerization of a clinical chart of perinatal data].

A computerized protocol, PADOVA-BPD, has been set-up to study prematures affected by RDS, PDA and/or BPD. This protocol consists of a Data Bank, BPDdata, where the information of traditional clinical chart has been stored and of the BPDPadova program, written for this purpose in FORTRAN 77, that allows a wide band of clinical and statistical analysis.

Adult↗
PubMedDate not supplied

[Prevalence of group B beta-hemolytic Streptococcus colonization in a sample of 23,312 pregnant women and newborn infants].

We report the prevalence of colonization of Group B Streptococci in a given population referred to a limited area in the north-west of Italy. 23.312 pregnant women were tested. Group B Streptococci have been isolated from genital cultures in 0.18-13.2% (mean 8.18). The prevalence of Group B streptococcal colonization from ear, throat and ocular cultures of newborn infants from colonized mothers was 11.55%. Incidence of infection in neonates has varied from 0 to 2.33% (1.5 per 1000 live births).

Ear↗