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Biomedical subjects

A Valenzuela

Publications and source records attributed to A Valenzuela.

At least 145 records · Page 8Linked to original sources
PubMed1976

O2 transport in the alpaca (Lama pacos) at sea level and at 3,300 m.

Five male alpacas native to high altitude, of approximately 40 kg, were studied first at 3,300 m and again after a 3-month sojourn at sea level. Measurements were made with the animals standing, unsedated and breathing air. Cardiac output was measured by the dye dilution technique. Blood gas tensions and contents were measured in arterial and mixed venous blood. Blood samples were also equilibrated with different oxygen tensions to construct O2-Hb dissociation curves. The P50 was 17.8 and 19.7 torr at 3,300 m and at sea level, respectively. The higher P50 values at sea level were associated with higher values of base excess. PaO2 was lower at 3,300 m but SaO2 was always above 90%. No significant changes in [Hb], Hct, Q, CaO2 and CvO2 with changes in elevation were observed. PaCO2 tended to be lower at altitude indicating a mild hyperventilation. The values of PvO2 were lower than those reported for other mammals but similar to those of the llama. A higher PvO2 was measured in the alpacas at sea level. The alpaca under conditions of chronic hypoxia presents only minor cardiorespiratory adjustments suggesting the possibility of tissue characteristics well suited for life at high altitude.

Adaptation, Physiological↗
PubMed1976

Hormone action on the cell nucleus: effect of erythropoietin and testosterone on bone marrow.

Experiments intended to correlate the biochemical action of erythropoietin and testosterone on marrow cells are presented. Both hormones seem to act at different cytological and biochemical levels. Erythropoietin triggers the erythropoietic phenomenon acting on the Erythropoietin-Sensitive Cells. Inducing the synthesis of a large size RNA, (85S) which after a ribonuclease-dependent processing mechanism generates the informational RNA (9S) required for hemoglobin synthesis. Testosterone acts directly on bone marrow (probably at the level of polychromatophylic erythroblasts) enhancing the synthesis of ribosomal RNA or its precursors and stimulates a nuclear ribonuclease which might represent a control mechanism on the processing of high molecular weight RNAs. It is postulated that erythropoietin and testosterone act synergistically to create the biochemical machinery for hemoglobin synthesis.

Animals↗
PubMedDate not supplied

Effect of ethanol and iron on the hepatic and biliary levels of glutathione and lipid peroxidative indexes.

Data presented here indicate that iron exposure exacerbates the changes in the glutathione status of the liver cell and the lipid peroxidative response of the tissue induced by acute ethanol intoxication. In these conditions, additivity in lipid peroxidation was found to occur either when the process was estimated by hepatic malondialdehyde formation, as well as by measurements of the biliary malondialdehyde release in the anesthetized rat and by the antioxidant-sensitive respiration in the perfused rat liver, procedures which are non-invasive for the tissue.

Animals↗
PubMedDate not supplied

Hemopoietic stem cell transplantation in refractory rheumatoid arthritis is not a contraindication for reconstructive surgery.

Hemopoietic stem cell transplantation (HCST) is an experimental therapy that may produce prolonged remissions in patients with rheumatoid arthritis (RA) resistant to other treatments. Prosthetic articular replacement is often required in severe long-lasting disease. There is a well-founded concern regarding the feasibility and safety of reconstructive surgery after HSCT and as yet no published data on the subject. We report a patient with RA of 9 years' duration resistant to conventional treatments plus femoral head necrosis, who underwent prosthetic hip replacement with no post-surgical complications one year after HSCT, with a sustained response.

Adult↗