Search PubMed⌕ Search

Biomedical subjects

J Morales

Publications and source records attributed to J Morales.

At least 145 records · Page 8Linked to original sources
PubMed1991

A major substrate of maturation promoting factor identified as elongation factor 1 beta gamma delta in Xenopus laevis.

Protein synthesis is believed to be under control of the cell cycle during meiosis and mitosis. Any relationship between substrates for cdc2 kinase and components of the protein synthetic apparatus would therefore be of prime importance. During meiosis of Xenopus laevis oocytes one of the substrates for this kinase is a p47 protein, which is complexed to two other proteins, P36 and P30. Judged from partial amino acid sequence data on P47 and P30, the P30 and P47 proteins were reported to resemble the protein synthetic elongation factors (EF) 1 beta and 1 gamma from Artemia salina (Bellé, R., Derancourt, J., Poulhe, R., Capony, J.P., Ozon, R., and Mulner-Lorillon, O. (1989) FEBS Lett. 255, 101-104). This paper shows that the complex composed of P30, P47, and P36 from Xenopus is identical to the complex of EF-1 beta, EF-1 gamma, and EF-1 delta from Artemia according to two criteria. 1) Both stimulate elongation factor 1 alpha-mediated transfer RNA binding to ribosomes and exchange of guanine nucleotides on elongation factor 1 alpha to a comparable degree. 2) Each of the three subunits of the protein complex P30.P47.P36 from Xenopus shows a structural homology with one of the corresponding subunits of EF-1 beta gamma delta from Artemia. Presumably the phosphorylation of EF-1 gamma, which associates with tubulin at least in vitro, is important in processes following the onset of meiosis which is accompanied by a rise of protein synthesis.

Amino Acid Sequence↗
PubMed1991

Structural and functional properties of thesaurin a (42Sp50), the major protein of the 42 S particles present in Xenopus laevis previtellogenic oocytes.

Thesaurin a is one of two protein components of a 42 S ribonucleoprotein particle that is very abundant in previtellogenic oocytes of Xenopus laevis. The primary function of the 42 S particle is the long-term storage of 5 S RNA and aminoacyl-tRNA. Thesaurin a is homologous to eukaryotic elongation factor 1 alpha (EF-1 alpha) and to prokaryotic elongation factor Tu (EF-Tu). Sequence comparison with EF-1 alpha and EF-Tu of different species indicates that thesaurin a is rather distantly related to all eukaryotic elongation factors. In spite of this, the secondary structure of thesaurin a, deduced from hydrophobic cluster analysis, is remarkably similar to that of EF-1 alpha and EF-Tu. The binding and catalytic properties of thesaurin a are also similar but not identical to those of EF-1 alpha. Like EF-1 alpha, purified thesaurin a binds tRNA, GDP, and GTP. Unlike EF-1 alpha, thesaurin a binds discharged tRNA more tightly than charged tRNA, and GTP more tightly than GDP. Thesaurin a also hydrolyzes GTP and catalyzes the mRNA-dependent binding of aminoacyl-tRNA to 80 S ribosomes. The functional properties of the 42 S particle are in general agreement with those of purified thesaurin a. In particular, the 42 S particle contains GTP and efficiently transfers aminoacyl-tRNA to 80 S ribosomes without addition of exogenous elongation factor.

Amino Acid Sequence↗
PubMed1991

Purification and characterization of a germ cell-specific form of elongation factor 1 alpha (EF-1 alpha) from Xenopus laevis.

Elongation factor 1 alpha (EF-1 alpha) was purified to homogeneity from full-grown oocytes of Xenopus laevis. This protein is encoded by a gene previously shown to be expressed in male and female germ cells, and repressed in somatic cells. The purified protein was identified with EF-1 alpha on criteria of molecular mass, cross-reaction with antibodies raised against Artemia salina EF-1 alpha, affinity for guanine nucleotides, and ability to promote the mRNA-dependent binding of aminoacyl tRNA to 80S ribosomes.

Adenosine Triphosphate↗
PubMed1991

Two forms of elongation factor 1 alpha (EF-1 alpha O and 42Sp50), present in oocytes, but absent in somatic cells of Xenopus laevis.

We have purified and partially sequenced the EF-1 alpha protein from Xenopus laevis oocytes (EF-1 alpha O). We show that the two cDNA clones isolated by Coppared et al. (Coppard, N. J., K. Poulsen, H. O. Madsen, J. Frydenberg, and B. F. C. Clark. 1991. J. Cell Biol. 112:237-243) do not encode 42Sp50, as claimed by these authors, but two very similar forms of EF-1 alpha O (EF-1 alpha O and EF-1 alpha O1). 42Sp50 is the major protein component of a 42S nucleoprotein particle that is very abundant in previtellogenic oocytes of X. laevis, 42Sp50 differs from EF-1 alpha O not only by its amino acid sequence, but also by several properties already reported. In particular, 42Sp50 has a low EF-1 alpha activity. It is distributed uniformly in the cytoplasm of previtellogenic oocytes, in contrast to EF-1 alpha O which is concentrated in a small region of the cytoplasm, known as the mitochondrial mass or Balbiani body.

Amino Acid Sequence↗
PubMed1991

A cell culture model of the blood-brain barrier.

Endothelial cells that make up brain capillaries and constitute the blood-brain barrier become different from peripheral endothelial cells in response to inductive factors found in the nervous system. We have established a cell culture model of the blood-brain barrier by treating brain endothelial cells with a combination of astrocyte-conditioned medium and agents that elevate intracellular cAMP. These cells form high resistance tight junctions and exhibit low rates of paracellular leakage and fluid-phase endocytosis. They also undergo a dramatic structural reorganization as they form tight junctions. Results from these studies suggest modes of manipulating the permeability of the blood-brain barrier, potentially providing the basis for increasing the penetration of drugs into the central nervous system.

Animals↗
PubMed1991

Hemorrhagic shock and bacterial translocation in a swine model.

Bacterial translocation is proposed as an explanation for sepsis associated with hemorrhagic shock. This study attempted to document these events in a large animal model. Male swine were randomly assigned to control (n = 10) or experimental (n = 10) groups. Animals were anaesthetized, and the bladder, portal vein, and a mesenteric lymphatic vessel cannulated. Experimental animals were bled 40% of blood volume. Over the next six hours maintenance fluids were given, and cultures of portal blood and mesenteric lymph taken. Before the swine were killed, cultures were taken from portal and systemic blood, mesenteric lymph, and lymph nodes, and a portion of terminal ileum was resected for histologic study. Experimental animals experienced significant shock as demonstrated by changes in hemodynamic and biochemical variables. Cultures and histologic examination of the terminal ileum showed no significant difference between control and experimental animals. In an unresuscitated swine model, significant bacterial translocation was not demonstrated within six hours of hemorrhagic shock.

Animals↗
PubMed1991

Correlations between self-handicapping and self-defeating personality.

In this study scores on Strube's self-handicapping scale were correlated with scores on Schill's self-defeating personality scale. Berglas believes there are subtypes of self-defeating personality and that his concept of self-handicapping should be correlated with the three criteria which represent a self-protective component of self-defeating personality. Some support for Berglas' proposition was found, particularly for men. However, correlations with other components of self-defeating personality suggest the criteria thought to be self-protective may need to be reconsidered.

Adult↗
PubMed1991

Self-defeating personality and perceptions of family environment.

People scoring higher on a scale of self-defeating personality perceived their family environments as lacking cohesiveness. Men also perceived their family environments as discouraging open expression of feelings, being unconcerned about school and work achievement, and providing no ethical or religious values. Results were seen as lending validity to clinical theories of masochism which relate lack of family support and lack of reinforcement for assertive, efficacious behavior to the development of self-defeating behavior patterns.

Achievement↗
PubMed1991

[Transesophageal echocardiography in the selection of patients prior to percutaneous mitral valvuloplasty. Study of 71 consecutive patients].

We studied 71 consecutive patients with mitral stenosis candidates for mitral valvuloplasty by means of transthoracic (TTE) and transesophageal echocardiography (TEE). We compared the information obtained by the two methods with respect to: mitral valve morphology (echocardiographic score), severity of mitral regurgitation, prevalence of atrial thrombus and incidence of spontaneous contrast in the left atrium. The assessment of valvular thickening, mobility and calcification was similar by the two methods. The assessment of the subvalvular disease was significantly lower by TEE than the assessed by TTE (1.66 +/- 0.6 vs 2.12 +/- 0.5; p less than 0.001). The total "score" obtained by TEE was significantly lower than the "score" obtained by TTE (7.32 +/- 1.9 vs 7.88 +/- 1.8; p +/- 0.001), but when we classified the patients in groups according to the "score", there were no significant differences between the groups obtained by the two methods. We detected mitral regurgitation in 27 patients (38%) by TTE and in 36 (50%) by TEE. The difference in the quantification of the mitral regurgitation was no more than one grade in any case. Atrial thrombus were detected in 16 patients (22%) by TEE and in 2 patients by TTE. Spontaneous contrast was seen in 53 patients (75%) by TEE and in only 1 by TTE. We conclude that TEE is essential in detecting atrial thrombus, but does not provide any new information about mitral valve morphology and mitral regurgitation in the selection of patients for percutaneous mitral valvuloplasty.

Adult↗
PubMed1990

[Transesophageal Doppler color echocardiography in the evaluation of patients after percutaneous mitral valvuloplasty].

To determine the value of transesophageal ultrasound in the assessment of patients after percutaneous mitral valvuloplasty, 42 patients were studied by transthoracic (TTE) and transesophageal (TEE) two-dimensional and color Doppler echocardiography. All of them were studied as out-patients and without complications. We describe the technique, planes of examination and the advantages that this new acoustic window offers in patients after balloon valvuloplasty regarding to: detection of thrombus in the left atrium (LA), visualization of spontaneous echo contrast in the LA, evaluation of mitral regurgitation (MR), detection of small atrial septal defects (ASD) and evaluation of the stage of the commissures of the mitral valve. We detected thrombus by TEE, in 5/42 vs 1/42 by TTE approach. Spontaneous echo contrast was found in 35/42 by TEE and none by TTE. Small ASDs were visualized in 10/42 patients vs 2/42 by TTE. No differences were found in the evaluation of MR and mitral valve commissures either by TEE or TTE. We conclude that transesophageal echocardiography is a well-tolerated technique in outpatients which complements and improves the information obtained by the transthoracic approach in patients after balloon mitral valvuloplasty.

Adult↗
PubMed1990

[Treatment of chronic renal failure: effects of a supplemented diet with essential amino acids].

We evaluated the results of essential amino acids supplementation added to a protein restricted diet (0.6 g/kg/day) in patients with advanced renal failure (creatinine clearance under 20 ml/min). A diet containing food with high biologic value was used as control. Diets were tested during 7 months. Anthropometric and nutritional (serum albumin and transferrin) values were normal in both groups both at the beginning and at the end of the treatment period. A slight increase in weight in the natural diet group and in serum phosphorus level in the amino acid supplemented group was observed. Two patients in each group required chronic dialysis, renal function remaining stable in the rest. We conclude that both forms of diet supplementation were effective in preserving nutritional status possibly in delaying deterioration of renal function in patients with advanced renal failure.

Amino Acids, Essential↗
PubMed1990

Protein phosphorylation during meiotic maturation of Xenopus oocytes: cdc2 protein kinase targets.

M-Phase specific protein kinase or cdc2 protein kinase is a component of MPF (M-Phase promoting factor). During meiotic maturation of Xenopus oocytes, cdc2 protein kinase is activated in correlation with MPF activity. A protein phosphorylation cascade takes place involving several protein kinases, among which casein kinase II, and different changes associated with meiosis occur such as germinal vesicle breakdown, chromosome condensation, cytoskeletal reorganization and increase in protein synthesis. Our results provide a biochemical link between cdc2 protein kinase and protein synthesis since they show that the kinase phosphorylates in vitro a p47 protein identified as elongation factor EF1 (gamma subunit) and that the in vitro site of p47 corresponds to the site phosphorylated in vivo. Immunofluorescence showed that the elongation factor (EF1-beta gamma) is localized in the oocyte cortex. Furthermore, they show that cdc2 kinase phosphorylates and activates casein kinase II in vitro, strongly supporting the view that casein kinase II is involved in the phosphorylation cascade originated by cdc2 kinase.

Animals↗
PubMed1989

[School feeding program in Guatemala: technology transfer to artisan bakers, producers of the nutritionally improved cookie].

The Ministry of Education of Guatemala requested from the Institute of Nutrition of Central America and Panama (INCAP), the development of a solid food for delivery to school children who attend the official schools throughout the country. INCAP developed and transferred the processing technology to produce a nutritionally improved cookie to artisan bakers from the different regions of the country. The present paper describes the technological process, focusing on the training, supervision and quality control actions executed with approximately 100 micro baking enterprises, in 1988 and 1989. These actions have had a positive impact on the bakeries, a fact evidenced by the significant improvement of the conditions and processes of the nutritionally improved cookie production. The performance of the above-mentioned activities has allowed us to detect necessities, for the solution of which research and development of technologies are most important for their immediate transference to artisan bakers. Nevertheless, it is necessary to monitor and control the transferred technology, and efforts must continue to increase the effectiveness of the whole system which involves technology transference model, created for this project.

Child↗