Biomedical subjects

R Bastos

Publications and source records attributed to R Bastos.

27 records · Page 2Linked to original sources

PubMed1994

Interactions and three-dimensional localization of a group of nuclear pore complex proteins.

We have used antibodies directed against a number of nuclear pore complex (NPC) proteins to determine their mutual interactions and location within the three-dimensional structure of the NPC. A monoclonal antibody, termed QE5, recognized three NPC polypeptides, p250, NUP153, and p62 on Western blots, and labeled the nuclear envelope of several cultured cell lines by immunofluorescence microscopy. These three polypeptides contained O-linked N-acetylglucosamine residues and were released from the NPC by detergent/high-salt treatment as discrete high molecular weight complexes. p250 was found in association with a novel 75 kD protein, NUP153 was released as a homo-oligomer of about 1 megadalton, and p62 was associated with polypeptides of 58 and 54 kD (previously reported by Finlay, D. R., E. Meier, P. Bradley, J. Horecka, and D. J. Forbes. 1991. J. Cell Biol. 114:169-183). p75, p58, and p54 were not galactosylated in vitro. Xenopus oocyte NEs were labeled with gold-conjugated QE5 and prepared for electron microscopy by quick freezing/freeze drying/rotary metal shadowing. This EM preparation method enabled us to more precisely localize the epitopes of this antibody to the cytoplasmic filaments and the nuclear basket of the NPC. Since QE5 recognizes three O-linked NPC glycoproteins, its labeling was compared with that of the lectin wheat germ agglutinin which recognizes O-linked N-acetylglucosamine moieties. The two probes were found to yield similar, although not identical, distributions of label. To identify the individual proteins with particular NPC components, we have used an anti-peptide antibody against NUP153 and a monospecific anti-p250 polyclonal antibody. Labeling with these two antibodies has documented that NUP153 is a constituent of the nuclear basket with at least one of its epitopes residing in its terminal ring, whereas p250 is a constituent of the cytoplasmic filaments.

Amino Acid Sequence↗

PubMed1993

High prevalence of sexually transmitted diseases in a rural area in Mozambique.

OBJECTIVE: To assess the extent of the sexually transmitted diseases (STDs) problem in a rural area of Mozambique. METHODS: A cross sectional study among pregnant women and patients presenting with genital complaints. Laboratory confirmation was done for gonorrhoea, chlamydial infection, active syphilis, trichomoniasis and HIV infection. SETTING: A primary health care setting in Vilanculos, Inhambane province, Mozambique. RESULTS: Evidence of one or more of the above STDs was found in 51% of 201 pregnant women, 56% of 85 women and 62% of 77 men with genital complaints. Neisseria gonorrhoea or Chlamydia trachomatis were found in 16% of pregnant women, 23% of female patients and 28% of male patients; genital ulcer disease was present in 6%, 28% and 36%, of respectively pregnant women, female and male patients. The prevalence of active syphilis was about the same in the three groups of study subjects, that is 15%. HIV infection was found in 4% of the male patients; no HIV infection could be detected in the female groups. CONCLUSION: STDs were a major health problem in this rural area in Mozambique. Though HIV infection was still low, the high prevalence of STDs indicates that the potential is there for an explosive spread of the HIV/AIDS epidemic.

Adolescent↗

PubMed1992

Increase of cytokeratin D during liver regeneration: association with the nuclear matrix.

An increase of a 45 kD protein (p45) in the nuclear matrix has been observed when rat liver cells were proliferatively activated in vivo by a partial hepatectomy. The maximal levels of the association of p45 with the nuclear matrix have been detected 24 hr after hepatectomy just at the time when DNA replication is also maximal. By amino acid sequence analysis, immunoblotting and immunocytochemical methods, it has been demonstrated that p45 is identical to rat cytokeratin D. Immunogold staining of nuclear matrix-intermediate filament preparations from cultured hepatocytes indicated that p45 is associated with cytoskeletal filaments that are strongly interconnected to the lamina, whereas no intranuclear localization of the protein has been detected. With an overlay assay a specific binding of labeled p45 to two nonidentified high-molecular weight proteins and also to lamin B has been observed. Northern blot analysis revealed a biphasic pattern of expression of the messenger RNA for cytokeratin D during liver regeneration. A sharp increase in the messenger RNA levels occurred in the prereplicative phase of liver regeneration a few hours before the accumulation of the protein in the nuclear matrix fraction, and a second peak occurred 48 hr after partial hepatectomy.

Amino Acid Sequence↗

PubMed1992

[Meniscal injury in the plastic reconstruction of the anterior cruciate ligament. Meniscal suture or abstention].

The purpose of this study was to observe the change of the meniscal lesions, which are conservable by suture or simply by leaving-in-place within the frame of operated anterior instability. Forty-six knees which had been operated by the free transplant of bone-patellar tendon-bone, presented the associated lesions of conservable meniscus. These lesions were treated by suture of the meniscus in 15 cases and left in place in 31 cases. The programme of rehabilitation was the same in the two groups. All the patients have been followed-up for 26 months in average (12-40 months). In the group of meniscal suture, only one secondary meniscectomy was carried out. 8 patients presented moderate pain on the corresponding femorotibial joint line and 5/13 of the sportive patients recovered to the same level of activity. In the group of leaving-in-place, no meniscectomy has been carried out. Only 4 patients complained of pain and 23/27 recovered to the same activity level. The arthrographic and arthroscopic observations have been carried out in 23 cases. They confirmed the cicatrization of the sutured meniscus but also showed the possibility of total or partial cicatrization of the lesions left in place (12 on 13). The authors conclude that the peripheral meniscal lesions associated with the operation of the chronic anterior instability do not always require suture. The abstention on the meniscal lesion is possible if it is limited on the posterior segment: Then the functional results seem better.

Adolescent↗

PubMed1990

Decrease of calmodulin and actin in the plasma membrane of rat liver cells during proliferative activation.

After proliferative activation of rat liver cells in vivo by a partial hepatectomy a decrease of the calmodulin content in the three plasma membrane domains (blood sinusoidal, canalicular and lateral) was observed. At 24 hours after partial hepatectomy calmodulin was found to be 3 fold lower in the sinusoidal and lateral fractions whereas a 2 fold decrease was detected in the canalicular domain. Decreases on the actin levels have been also detected at 24 hours after a partial hepatectomy. Since at this time after surgery increases on nuclear actin and calmodulin have been reported, these results suggest the possibility that the actin and calmodulin dissociated from the plasma membrane after a partial hepatectomy could subsequently be translocated into the nuclei.

Actins↗

PubMed1990

Calmodulin-binding proteins in the nuclei of quiescent and proliferatively activated rat liver cells.

alpha-Spectrin, myosin light chain kinase (MLCK), and caldesmon have been detected in the nuclei of rat liver cells by 125I-calmodulin overlay, immunoblotting, and immunocytochemical methods. alpha-Spectrin is localized in the nuclear matrix, nuclear envelope, and nuclear pores. It has also been detected inside the nuclei in the form of small aggregates. MLCK is present in the nuclear matrix, envelope, nucleoli, and in a nuclease extract (S1 subfraction) but not in the nuclear pores. Caldesmon shows a diffuse distribution pattern inside the nuclei but it is not present in the nucleoli. Since all these proteins are components of the actin-myosin motility systems the presence of actin in the different nuclear subfractions has also been investigated: actin is present in the nuclear matrix, nuclear envelope, nucleoli, and nuclear pores. Proliferative activation of rat liver cells in vivo by partial hepatectomy induces the increase of alpha-spectrin, MLCK, and actin in different nuclear subfractions. This, together with the increase of nuclear calmodulin at the same time after hepatectomy (Pujol, M. J., Soriano, M., Aligúe, R., Carafoli, E., and Bachs, O. (1989) J. Biol. Chem. 264, 18863-18865), indicates that nuclear calmodulin could activate a nuclear contractile system during proliferative activation. A 62-kDa protein (p62) which binds to calmodulin columns and shows immunological similarities to caldesmon is specifically located in the region surrounding the nuclear envelope and is associated with the heterochromatin.

Animals↗

PubMed1990

Increase in a 55-kDa keratin-like protein in the nuclear matrix of rat liver cells during proliferative activation.

We have identified a protein (p55) with a molecular weight of 55 kDa and a pI of 6.2, which was strongly increased in the nuclear matrix of rat liver cells during proliferative activation. This protein is highly insoluble since it could not be solubilized either by detergents or by alkaline extraction. We have obtained three partial amino acid sequences which revealed that p55 has a high homology with cytokeratins. Polyclonal antibodies raised against p55 were used to carry out Western blot and immunocytochemical studies which indicated that p55 was localized only in the nuclei, specifically in the nuclear matrix. Autoradiographic experiments revealed that not all the cells presenting an increase in p55 incorporated [3H]thymidine, indicating that this protein is not related to DNA replication. Immunocytochemical studies also revealed that during mitosis p55 is localized surrounding the chromosomes and associated with the mitotic apparatus, suggesting that p55 is involved in the separation of chromosomes during cell division.

Amino Acid Sequence↗

PubMed1987

Molecular structure of the gene and the 5'-flanking region of the human lymphocyte immunoglobulin E receptor.

Overlapping clones which contain the complete gene encoding the human lymphocyte IgE receptor (MW:45kd; identical with CD23), were isolated from human genomic lambda-libraries. The gene spans approximately 13kb and comprises 11 exons. The 5'-end of the mRNA was mapped by primer extension and S1-mapping, revealing two initiation sites for transcription. Two corresponding TATA boxes were identified by sequencing the 5'-flanking region. A 188bp long inverted repeat was found which flanks the promoter region and could possibly be involved in gene regulation. Exons 9 to 11 code for the IgE-binding domain of the receptor which shows homology to several lectins, particularly to the asialoglycoprotein receptor. A comparison of the exon/intron arrangement of these genes implies that their lectin domains have evolved from a common ancestral cassette.

Base Sequence↗

PubMed1976

Biosynthesis and stability of globin mRNA in cultured erythroleukemic Friend cells.

Biosynthesis and stability of the mRNA population in DMSO-induced Friend erythroleukemic cells were studied after labeling the RNA with 3H-uridine and then chasing it with nonlabeled uridine. Globin RNA metabolism was studied by hybridization to excess complementary DNA convalently coupled to oligo(dT)-cellulose. After a labeling period of 120 min, 2-4% of the poly(A)-containing labeled RNA was in globin RNA; it decayed with a half-life of 16-17 hr. The rest of the poly(A)-containing RNA was composed to two kinetic populations: 85-90% decayed with a half-life of about 3 hr, while 10% decayed with a half-life of about 37 hr. The portion of globin RNA in labeled poly(A)-containing RNA behaved in an unexpected fashion during the chase period. During the initial chase period, the percentage of globin RNA increased rapidly, reaching a maximum of about 15% at 20 hr, but it subsequently declined gradually. Based on these findings, a model was built that describes the changes in the proportion of globin mRNA in poly(A)-containing RNA during continuous synthesis and after chase of the labeled RNA. It appears that if the parameters described remain constant during the maturation of erythroblasts, then this model would not account for the almost exclusive presence of globin RNA in the reticulocyte. By far the most effective way to achieve this high level of globin RNA is the destabilization of the mRNA population which is more stable than globin RNA, and not the stabilization of globin RNA itself.

Cell Line↗