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Biomedical subjects

J A Torres

Publications and source records attributed to J A Torres.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effect of a cecropin-like synthetic peptide (Shiva-3) on the sporogonic development of Plasmodium berghei.

The effect of a synthetic cecropin-like peptide, Shiva-3, on in vitro ookinete development and on the early sporogonic stages of Plasmodium berghei in the midgut of Anopheles albimanus was investigated. Peptide concentrations of 75 and 100 microM were effective (P < 0.05) in reducing ookinete production and the number of infected mosquitoes in almost all experiments. These peptide concentrations in the midgut were not toxic for the survival of the mosquitoes. Complete inhibition was obtained if 100 microM Shiva-3 was applied in the first 8 hr of parasite development. The deleterious effect of the peptide on the parasite was effective after exposure for as short as 50 sec and the permanence of free peptide in the mosquito midgut was estimated to be of a minimum of 5 min. These observations indicate the possibility of using Shiva-like peptide genes to engineering malaria-resistant vectors as an alternative in malaria control strategies.

Animals↗
PubMed1995

[Amplification of contractile response by serotonin on noradrenaline in the human umbilical artery].

A progressive increase in plasma levels of serotonin (5-HT) during pregnancy has been reported. Furthermore, an increase in the concentration of noradrenaline (NA) has been described during labor. On the other hand, in different arteries it has been observed that minimal effective concentrations of 5-HT are able to produce an increase or "amplification" of the contractile response to a second agonist. From these reports, it seemed interesting to determine the existence of a synergistic interaction between 5-HT and NA in the human umbilical artery (HUA), and the probable mechanisms involved. Therefore, strips of HUA were incubated in Krebs solution at 37 degrees C and gassed with a mixture of CO2 (5%) and O2 (95%). The contractile isometric response was assessed. After a period of two hours, complete cumulative concentration-response curves to 5-HT and to NA were obtained. The maximal contractile response to NA was approximately 20% of the maximal response to 5-HT. In another series of experiments, the response to NA was enhanced by previous treatment with minimal effective doses of 5-HT (control response 0.24 +/- 0.06 g; "amplified" response 0.53 +/- 0.06 g, P < 0.01). This "amplified" response to NA was correlated with the degree of previous contraction with 5-HT, when the last was between 3 and 30% of the maximal response. However, precontractions higher than 40% abolished the responses to NA. In other experiments, the artery strips were incubated during thirty minutes with diltiazem 1 microM before agonists addition. In this condition, a decrease in the control and amplified response was observed. Therefore, we have shown the existence of an amplifying effect of 5-HT over the response to NA in the HUA, and we discuss the possible mechanisms involved and the possible clinical relevance in preeclampsia.

Humans↗
PubMed1994

Susceptibility of three laboratory strains of Anopheles albimanus (Diptera: Culicidae) to coindigenous Plasmodium vivax in southern Mexico.

Three morphologically different pupal phenotypes (green, striped, brown) were selected from a parent strain of Anopheles albimanus Wiedemann collected from the Suchiate region in the state of Chiapas, Mexico. Significant differences in susceptibility to coindigenous Plasmodium vivax Grassi & Feletti were observed when striped was compared with the parent colony as well as with brown and with green phenotypes. Differences in susceptibility were not significant between the other phenotypes and the parent colony.

Animals↗
PubMed1994

Radiographic and histological characterization of Tc/tw5 mice: an animal model of lumbosacral agenesis/myelomeningocele.

Twenty-five Tc/tw5 and 12 control mice were killed at different ages and radiographically and histologically examined. In addition, histochemical analysis was performed on muscles from four mutant and one control mouse. All Tc/tw5 mice were tailless and had a fluid-filled lumbar myelomeningocele. Radiographically, most animals had six instead of 10 lumbosacral vertebrae. Vertebral anomalies were common. The spinal cord was grossly abnormal: at the level of the plaque, it was replaced by patches of neural tissue intermingled with connective tissue and muscle. Affected skeletal muscles had small myofibers with centrally placed nuclei consistent with arrest of development at the myotubular stage secondary to denervation in early embryonic life. Abnormal nerves were smaller and had fewer axons. Tc/tw5 mice show features of neural tube and notochord dysplasia. These mutant mice may be useful as animal models of lumbosacral agenesis and myelomeningocele.

Animals↗