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Biomedical subjects

F Malpartida

Publications and source records attributed to F Malpartida.

At least 73 records · Page 4Linked to original sources
PubMed1982

[Evaluation of the functional aerobic capacity in mitral prostheses. Preliminary report].

Based on the results of an ergometric stress testing performed in 22 patients with mitral replacement, the author concludes that this method is a highly reproductive and safe to evaluate the functional improvement of patients undergoing a mitral replacement. The results are similar for Bjork-Shiley (11 patients) and Starr-Edwards prothesis (11 patients), slurring that the only parameter that can affect functional results can be a controlled rehabilitation program.

Carbon Dioxide↗
PubMed1981

Phosphorylated intermediate of the ATPase from the plasma membrane of yeast.

A purified preparation of the plasma-membrane ATPase from Saccharomyces cerevisiae was phosphorylated when incubated with [gamma-32P]ATP. The phosphoprotein formed has the characteristics of an enzyme intermediate because of its rapidity of phosphorylation and dephosphorylation. When the phosphorylated enzyme was analyzed by polyacrylamide gel electrophoresis in sodium dodecylsulfate only one band with a molecular weight of 100000 contained radioactivity. This band represented about 80% of the protein of the preparation and its enrichment in the course of the purification correlated with the increase in the specific ATPase activity. Both the ATPase reaction and the phosphorylation of the enzyme exhibited an apparent dissociation constant for the enzyme-ATP complex of 0.2 mM, further implicating the phosphoenzyme as an intermediate of the reaction. The sensitivity of the phosphoenzyme bond to alkaline pH and hydroxylamine indicate that it is an acylphosphate. From the maximum level of intermediate (0.7 nmol/mg) and the maximum ATPase activity at 30 degrees C (21 mumol x min-1 x mg-1) a turnover number of 30000 min-1 can be calculated. The level of phosphoenzyme was not affected by either the ATPase inhibitors vanadate and dicyclohexylcarbodiimide or by ADP. These results indicate that the yeast plasma-membrane ATPase has a subunit composition and reaction mechanism similar to the cation-pumping ATPases of animal plasma membranes.

Adenosine Triphosphatases↗
PubMed1981

Reconstitution of the proton-translocating adenosine triphosphatase of yeast plasma membranes.

The plasma membrane ATPases of eukaryotic cells of the vegetable type (fungi, plants, and algae) have been postulated to operate as proton pumps which generate membrane potentials and drive the uptake of nutrients by proton co-transport (Poole, R. J. (1978) Annu. Rev. Plant Physiol. 29, 437-460). In order to verify this important physiological role, a purified preparation of the yeast plasma membrane ATPase has been reconstituted with soybean phospholipids by a freeze-thaw-sonication procedure. The reconstituted proteoliposomes catalyzed a 32Pi-ATP exchange partially sensitive to proton ionophores (uncouplers) and to the proton-potassium exchange carrier nigericin. The reaction was completely inhibited by the nonspecific ionophore gramicidin and by the combination of uncouplers with the potassium ionophore valinomycin. These results are interpreted as evidence for two types of proton transport catalyzed by the enzyme preparation: electrogenic proton transport and electroneutral proton-potassium exchange.

Adenosine Triphosphatases↗
PubMed1980

Surgical treatment for chest pain in mitral valve prolapse.

The case of a 40-year-old woman with mitral valve prolapse and severe atypical chest pain is presented. The diagnosis was confirmed by phonocardiographic, echocardiographic, and angiocardiographic studies. The electrocardiogram revealed an ischemic pattern of ST-T on the anterior and inferior wall. Coronary angiographic studies showed normal coronary arteries. The patient's long-standing, prolonged, disabling atypical chest pain could not be relieved with medical therapy, despite the administration of beta-adrenergic blocking agents, calcium antagonists, and short-acting nitrites during a 30-month period. Thus, the prolapsed mitral valve was replaced with a Hancock xenograft. After 12 months the patient is totally free of symptoms, without any treatment and with a normal ECG. This excellent surgical result could be explained on the basis of the valvular theory of chest pain in mitral valve prolapse, suggesting that pain is promoted probably by a regional imbalance between oxygen availability and consumption, because of the excessive papillary muscular stretching produced by the prolapse. To our knowledge, this is the first published report of successful surgical treatment of chest pain in mitral valve prolapse.

Adult↗