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Biomedical subjects

R Oliva

Publications and source records attributed to R Oliva.

95 records · Page 6Linked to original sources
PubMed1982

Cellular content and biosynthesis of polyamines during rooster spermatogenesis.

The natural polyamines spermine and spermidine, and the diamine putrescine, were extracted from rooster testis cells separated by sedimentation at unit gravity, and from vas-deferens spermatozoa. The ratios spermine/DNA and spermidine/DNA were kept relatively constant throughout spermatogenesis, whereas the ratio putrescine/DNA rose in elongated spermatids. The cellular content of spermine, spermidine and putrescine decreased markedly in mature spermatozoa. Two rate-limiting enzymes in the biosynthetic pathway of polyamines, ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase, showed their highest activities at the end of spermiogenesis and were not detectable in vas-deferens spermatozoa. A marked reduction in cell volume during spermiogenesis without a parallel decrease in the cellular content of polyamines suggests the possibility that the marked changes in chromatin composition and structure occurring in rooster late spermatids could take place in an ambience of high polyamine concentration.

Adenosylmethionine Decarboxylase↗
PubMedDate not supplied

Conformation and calcium-binding properties of a bicyclic nonapeptide.

The conformation and calcium binding properties of the bicyclic nonapeptide BCP2, cyclo-(Glu(1)-Ala(2)-Pro(3)-Gly(4)-Lys(5)-Ala(6)-Pro(7)-Gly(8))-cyclo-(1gamma --> 5epsilon) Gly(9), have been investigated by means of NMR spectroscopy. Interproton distances, evaluated by nuclear Overhauser effect (NOE) contacts, and straight phi angles, from (3)J(NH-alphaCH), have been used to obtain a feasible model for the BCP2-Ca(2+) (BCP: bicyclic peptide) complex by means of restrained molecular dynamics (RMD). The NMR analysis of the free peptide, carried out in CD(3)CN, shows the presence in solution of at least four conformers in intermediate exchange rate. The addition of calcium ions caused the appearance of a new set of resonances, differing from those observed for the free BCP2. A comparison with published data about the conformational behavior of the closely analogous peptide BCP3, differing from BCP2 for two Leu residues instead of two Ala residues in positions 2 and 6, shows that this simple substitution dramatically increases the peptide flexibility. On the contrary, upon calcium ion addition, both BCP2 and BCP3 reach a strictly close conformation, as strongly testified by the almost identical (1)H-NMR spectra exhibited by both peptides. The RMD molecular model of the BCP2-Ca(2+) complex, here reported, is a quite symmetric structure, presenting a three-dimensional cavity ideal for the binding of spherical cations. Four carbonyls from the main ring (Ala(2), Gly(4), Ala(6) and Gly(8)) point toward it, offering, together with the two carbonyls of the peptide bridge (Gly(9) and gammaGlu(1)), putative coordinations to the cation.

Amino Acid Sequence↗
PubMedDate not supplied

Complete characterization of the 3' region of the human and mouse hereditary hemochromatosis HFE gene and detection of novel splicing forms.

The human HFE gene was identified in 1996 as the gene whose mutations are responsible for hereditary hemochromatosis in most patients. Expression analysis by Northern blot indicated that the gene was approximately 4.1 kb in length. However, the cDNA reported was only 2716 bp. These results implied that at least 1.4 kb of the mRNA remained to be identified. In the present study, we detected several 3' EST clones while screening the genomic region of the gene in search of potential additional HFE mRNA sequences. Subsequent sequencing of these EST clones and RT-PCR experiments revealed that exon 7 of the HFE gene has, in fact, a length of 1944 bp and it presents two polyadenylation signals. The new human HFE exon 7 region has been screened in non-C282Y HH patients in search for new putative mutations. Mouse 3' RACE experiments also further extend the previously reported mouse HFE exon 6 sequence. Additionally, we report two novel end forms of the human HFE gene detected by 3' RACE experiments and several novel splicing forms identified in the HepG2 cell line.

3' Untranslated Regions↗
PubMedDate not supplied

Molecular staging of bladder cancer with RT-PCR assay for CK20 in peripheral blood, bone marrow and lymph nodes: comparison with standard histological staging.

BACKGROUND: The aim of this study was to analyze whether the CK20 reverse transcriptase polymerase chain reaction (RT-PCR) is suitable for detecting circulating tumor cells and residual tumor cells in lymph nodes, in patients with muscle invasive transitional cell carcinoma (TCC) of the bladder, and to compare these results with standard histological staging. PATIENTS AND METHODS: The nested RT-PCR assay was used to analyze the CK20 transcript in the peripheral blood, bone marrow, lymph nodes, the tumor and normal biopsies of bladder from 57 patients with invasive TCC of the bladder, who underwent radical cystectomy, and from 9 patients with noninvasive TCC. RESULTS: Lymph node pathological status was positive in 24 out of the 57 patients studied and all of them except I showed expression of CK20, with a correlation between histological technique and RT-PCR of 95.8%. A statistically significant correlation of lymph node CK20 RT-PCR with the standard risk factor of pathological stage (p = 0.04) was observed Blood and bone marrow CK20 RT-PCR showed no correlation with pathological stage. CONCLUSION: Lymph node CK 20 RT-PCR correlates with pathological stage in bladder cancer. The CK20 RT-PCR assay appears to be a highly sensitive and specific method for detecting circulating tumor cells and residual disease in lymph nodes in patients with invasive bladder cancer. Further evaluation of the significance of CK20 as a molecular marker for staging and follow-up in these patients is necessary.

Adult↗