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J Amezcua

Publications and source records attributed to J Amezcua.

6 recordsLinked to original sources
PubMed1994

Low flow veno-venous ECMO: an experimental study.

Clinical use of extracorporeal membrane oxygenation (ECMO) and carbon dioxide removal (ECCO 2R) have become well established techniques for the treatment of severe respiratory failure; however they require full cardiopulmonary bypass, representing major procedures with high morbidity. We theorized the possibility of an efficient low flow veno-venous extracorporeal membrane gas exchange method. Four mongrel 12 kg dogs were submitted to veno-venous extracorporeal membrane gas exchange via a jugular dialysis catheter using a low flow (10 ml/min) roller pump and a membrane oxygenator for a period of four hours. Respiratory rate was set at 4 breaths/min with a FiO 2 of 21% and ventilatory dead space was increased. Adequate gas exchange was obtained (pO 2139, pCO 224, Sat 99.4%), without major hemodynamic changes or hematuria. Our results demonstrate the feasibility of a low flow, less aggressive system. Further research should be considered.

Animals↗
PubMed1992

Anionic currents of chick sensory neurons are affected by a phospholipase A2 purified from the venom of the taipan snake.

A neurotoxic phospholipase A2 was purified from the venom of the taipan snake Oxyuranus scutellatus scutellatus by three consecutive chromatographic steps on ion exchange resins, followed by an affinity column prepared with a phosphatidylcholine derivative attached to Sepharose. The phospholipase was shown to be of type A2 (specific activity of 85 units/mg protein), and an apparent molecular weight of 16,000. Amino acid analysis shows the presence of approx. 150 residues with the N-terminal amino acid sequence: NLAQFGFMIRCANGGSRSALDYADYGC, different from all the phospholipases described until now. This enzyme is lethal to experimental mice (LD50 = 10 micrograms/20 g mouse weight) and affects ionic currents in chick (Gallus domesticus) dorsal root ganglion cells, measured by the whole-cell clamp technique. In symmetrical external/internal ionic solutions, after suppression of Na+, K+ and Ca2+ currents, external application of phospholipase at a low concentration (30 nM) was shown to increase the baseline current in a reversible manner. The augmented response was voltage-dependent and the effect was much greater for negative currents. In the presence of a salt gradient across the membrane (out 40 mM NaCl/in 140 mM CsCl), the current reversal potential revealed a shift in the positive direction typically due to Cl- ion flux through the membrane. External application of a 50 microM concentration of picrotoxin caused a reversible reduction of the phospholipase-induced chloride current. Moreover, no appreciable current block was detected after addition of 50 microM DIDS.

Amino Acid Sequence↗
PubMed1992

Verapamil does not block the spastic response of Praziquantel on the larvae of Taenia pisiformis.

This paper describes that the previous addition of Verapamil does not block the spastic response to Praziquantel (Pz) in larvae of Taenia pisiformis kept in vitro, where opposite results were found in the literature using mammalian tissue. It is possible that Pz stimulates other Ca++ transport channels not sensitive to Verapamil action and promotes Ca++ liberation from calcareous corpuscles stimulating phospholipase C of the tegument surface generating inositol triphosphate. These hypotheses require experimental approaches to define the exact mechanism of action.

Animals↗
PubMed1968

Secondary and apparent primary antibody responses after group A streptococcal vaccination of 21 children.

A partially purified M protein, extracted from a mouse-virulent strain of type 3, group A streptococcus, was administered subcutaneously in gradually increasing amounts at weekly intervals to 21 children in a Family Program. Seven children with type 3 bactericidal antibody in prevaccination sera showed a secondary response. Of 14 children with no detectable type 3 bactericidal antibody prior to vaccination, 13 developed definite type 3 antibody during or soon after vaccination. This response appeared to be of the primary variety in at least some of the 13 children because (i) the total incidence of antibody response (20 of 21) was greater than can be accounted for by the documented incidence of clinical and subclinical type 3 infections among children of our Family Program during a period of 14 years, (ii) the response in the 13 children with no detectable antibody prior to vaccination was more delayed than in those showing a definite secondary response, and (iii) on the average, the amount of vaccine needed for a response in these 13 children was 15 to 28 times greater than that required for the secondary response. Local skin reactions were variable among the vaccinated children. Systemic reactions were infrequent and not severe. The giving of multiple injections of partially purified M protein did not seem to cause cutaneous hypersensitivity.

Adolescent↗