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Biomedical subjects

F Cimino

Publications and source records attributed to F Cimino.

At least 55 records · Page 3Linked to original sources
PubMed1990

Isolation of cDNA fragments hybridizing to rat brain-specific mRNAs.

A cDNA minilibrary in pUC18 has been generated from 3-month-old rat brains. Two hundred clones were randomly selected and sequenced. Comparison with a nucleic acid and protein data bank revealed a number of cDNA fragments not homologous to any published sequence. Northern blot analyses of some of these clones yielded 5 brain-specific cDNA fragments. The full-length cDNA for one of these clones has been isolated and completely sequenced. It corresponds to an mRNA of about 1,500 nucleotides, which is present in brain and, to a lesser extent, in heart and skeletal muscle. Its expression is developmentally regulated in the rat brain from 14-day embryos to 3-month-old adults. A very recent comparison with the EMBL nucleotide sequence data bank showed that this mRNA codes for a brain-specific snRNP-associated protein.

Aging↗
PubMed1989

Expression of genes of ferritin subunits in human hepatoma cell lines.

The expression of ferritin genes has been studied in two well differentiated hepatoma cell lines, HepG2 and Hep3B, and in an undifferentiated cell line, HepPLC/PRF/5. The steady-state level of the H and L ferritin subunit mRNAs is different in the three cell lines, being most abundant in the HepG2 and Hep3B cells. The efficiency of promotion of transcription of the H and L gene promoters is not correlated with the levels of the two transcripts; moreover the half-life of the H and L mRNAs varies among the hepatoma cells. The different level of ferritin mRNAs in differentiated and undifferentiated cells appears to be mainly due to a different stability of the transcripts.

Blotting, Northern↗
PubMed1989

Comparative effects of roxithromycin and erythromycin on cellular immune functions in vitro. 1. Uptake of 3H-macrolides by human macrophages.

The degree of penetration of roxithromycin in human macrophages was evaluated and compared with that of erythromycin. The results indicated that both macrolides at concentrations of 2, 10 and 20 micrograms/ml were concentrated by macrophages, even if roxithromycin was consistently and significantly more accumulated than erythromycin. Comparison of the degree of penetration of the two drugs into dead, resident and stimulated phagocytes indicated that the process of transfer through the macrophage wall was of an active nature, related to the metabolic state of the cells. Analysis of the binding of the two macrolides to intracellular proteins showed that more binding sites were available for erythromycin than for roxithromycin.

Analysis of Variance↗
PubMed1988

Oligonucleotide-directed mutagenesis: a sequence-based screening.

A procedure to screen for mutant clones obtained by oligonucleotide-directed mutagenesis has been developed. It is based on the preparation of phage containing supernatants from a number (100 or more) of randomly chosen mutagenized M13 plaques. Aliquots from these supernatants are mixed to obtain pools, each containing 10 phages. Heterogeneous single-stranded DNA is prepared from these pools and used as template in a "single letter" sequence according to the dideoxy chain terminator method. Thus, the pool(s) containing the mutated sequence and the mutated sequence itself is identified by sequencing the single-stranded DNAs of the 10 phages present in the selected pool.

Animals↗
PubMed1987

The transcriptional efficiency of clustered tRNA genes is affected by their position within the cluster.

The transcription of a mouse genomic segment containing four tRNA genes, coding for a tRNA(Ala), a tRNA(Ile), a tRNA(Pro) and a tRNA(Lys), has been studied in a HeLa cell extract, demonstrating that differences among their transcriptional efficiencies are evident using as templates either the natural cluster or an equimolecular mixture of the four isolated genes. Nevertheless, the structure of the cluster influences the transcriptional efficiency of the clustered genes. In fact, a cis-acting inhibitory sequence has been located at about 400 bp downstream of the tRNA(Pro) coding sequence. Moreover rearrangements of the reciprocal position of the various tRNA genes within the cluster results in significant changes in the transcriptional rates of the individual transcriptional units.

Animals↗
PubMed1986

Structure and in vitro transcription of tRNA gene clusters containing the primers of MuLV reverse transcriptase.

Three genes coding for mouse tRNAPro have been isolated from a genomic library and characterized both structurally and functionally. Two of these (tPro52 and tPro53) code for the tRNA primer of reverse transcriptase of MuLV. The third one (tPro51) shows several differences (mutations and deletions) that probably prevent the folding of the matured transcript into the cloverleaf structure, and is therefore a pseudogene. This pseudogene gives rise to a RNA transcription product in vitro. tPro52 is clustered with a tRNALys gene and with a tRNAAla gene, which is strongly homologous to the rat identifier repeated sequence. tPro53 is clustered with a tRNAAsp and a tRNAGly gene. Other tRNA-hybridizing sequences are present in the lambda clones that contain tPro51 and tPro53.

Anticodon↗
PubMed1985

Pseudouridine excretion and transfer RNA primers for reverse transcriptase in tumors of retroviral origin.

To evaluate the relationship between pseudouridine increase in biological fluids and retroviral cell transformation, we have studied the effect of retrovirus infection and/or transformation on the rate of pseudouridine excretion by chick embryo fibroblasts. The results show that: pseudouridine excretion by chick embryo fibroblasts transformed by Rous sarcoma virus is several times higher than that of normal cells; this increased excretion precedes by many hours the appearance of the morphological signs of transformation and it is always present when neosynthesized infectious viral particles are released into the culture medium; and pseudouridine excretion was also increased in cells infected by a mutant of Rous sarcoma virus (RAV-1) which, lacking the src gene, does not transform the cells but replicates normally. To investigate if pseudouridine overproduction is related to an altered turnover rate of specific transfer RNA (tRNA) species which functions as primer of retrovirus reverse transcriptase, the concentration of non-acylated proline-accepting tRNA and non-acylated tryptophan-accepting tRNA, primers of reverse transcriptase of murine leukemia virus and of Rous sarcoma virus, respectively, has been measured, the former in normal and transformed AKR thymus and the latter in normal fibroblasts and in fibroblasts infected by Rous sarcoma virus or by its nontransforming mutant. The results show that in both systems a significant increase of the primer tRNA species occurs in the infected or transformed cells.

Animals↗
PubMed1984

Determination of pseudouridine in tRNA and in acid-soluble tissue extracts by high-performance liquid chromatography.

A high-performance liquid chromatographic method to measure pseudouridine and other nucleosides in hydrolyzed unfractionated tRNA and in acid soluble tissue extracts is described. The method is based on the following steps: tRNA extraction and hydrolysis by a mixture of ribonuclease A, snake venom phosphodiesterase and bacterial alkaline phosphatase; nucleoside purification (in the case of acid soluble tissue extract) by affinity chromatography on a phenyl-boronate gel column; nucleoside separation and quantitation by high-performance liquid chromatography on an octadecylsilane column by a reversed polarity gradient elution. The procedure allows a very accurate quantitation of pseudouridine and some other nucleosides, and its sensitivity is such that only 20 micrograms of tRNA are required. The method has been utilized to compare the pseudouridine content of hydrolyzed tRNA extracted from normal and lymphomatous murine thymus, as well as the pseudouridine content in acid soluble extracts from the same tissues.

Animals↗
PubMed1984

Serum pseudouridine as a biochemical marker in the development of AKR mouse lymphoma.

Pseudouridine is a modified nucleoside derived from the degradation of some species of RNA, primarily transfer RNA, the level of which is elevated in biological fluids of tumor-bearing subjects. In order to study the relationship between pseudouridine levels and the development and progression of neoplasia, we have measured pseudouridine levels in the serum of inbred mice with high (AKR) and low (BALB/c) incidence of spontaneous lymphoma and in mice carrying transplantable lymphoid tumors. Our results show that the serum level of pseudouridine: (a) in healthy mice, is higher in females than in males; (b) increases significantly in female AKR mice in the period preceding the development of lymphoma (preneoplastic period occurring at about 6 months of age); and (c) is highest in AKR mice with lymphoma, the most elevated levels being found in mice with widely disseminated disease. The latter observation was confirmed by experiments with a transplantable AKR lymphoma (T2), where a positive correlation between tumor burden and serum pseudouridine levels was found. On the contrary, in BALB/c mice carrying a transplantable myeloma tumor (MOPC-460), no increase was seen despite the presence of a considerable tumor burden. The increase of pseudouridine in the preneoplastic period, in the absence of overt disease is viewed as an early sign of the development of the disease.

Animals↗