N-aralkyl substitution of 2-aminoindans. Synthesis and their inotropic and chronotropic activity in isolated guinea pig atria.

Amino substitution of rigid forms of dopamine 4,5-dihydroxy-2-aminoindan and 5,6-dihydroxy-2-aminoindan with aralkyl functionalities were carried out to investigate the role of such structural modifications upon cardiac inotropic-chronotropic activity. Compounds synthesized demonstrated a modest inotropic selectivity, while one of them, described as 5,6-dihydroxy-N-[2-(4-hydroxyphenyl)-1-methylethyl]-2-aminoindan hydrobromide 17, showed a marked inotropic action on isolated heart tissue.

[Antigenic differentiation among 3 life-cycle stages of Toxoplasma gondii using fluorescent antibodies]. / Diferenciación antigénica entre tres estadios del ciclo de vida de Toxoplasma gondii mediante anticuerpos fluorescentes.

Antigenic differentiation between three stages of the life cycle of Toxoplasma gondii by fluorescent antibodies. Antisera were prepared in three groups of twenty mice each with three different antigens of Toxoplasma gondii: the first group was inoculated with tachyzoites of RH strain and received sulfadiazine treatment; the second with tissue cysts of T-100-cat-6751 strain and the third with oocysts of the same strain, both without treatment. In the indirect immunofluorescent antibody technique each antigen was tested with its homologous and heterologous antisera, determining qualitative and quantitative antigenic differences according to the fluorescence patterns. Some stages of Toxoplasma when reacting with their heterologous antibodies showed a central, partial posterior or total fluorescence during a certain period of development. The difference in fluorescence was sufficient to distinguish whether the origin of the infection was via cyst, oocysts and/or via tachyzoite when observation was made before day 65 post-infection.

Noninvasive transcutaneous cardiac pacing in children.

Noninvasive transcutaneous cardiac pacing is an emergency pacing modality with proven benefits for adult patients. During induction of anesthesia for heart surgery, we externally paced 22 children (aged 0.9-17.9 years and weighing 6.96 to 51 kg) using a commercially available device to pace approximately 10 beats per minute faster than the spontaneous heart rate. Three pacing electrode sizes were used (the standard adult size and two specially manufactured smaller sizes). A total of 56 pacing trials were conducted, 53 of which were successful in obtaining capture. A mean output of 63 +/- 14 mA (range, 42-98) at threshold using the large electrodes was comparable to published adult requirements. Lower current outputs were needed with the medium (53 +/- 12 mA; range, 36-92) and small electrodes (51 +/- 11 mA; range, 29-82). In any given patient, the large electrodes required more current (p less than 0.01) to obtain capture, but delivered less current density (p less than 0.01) and exhibited less impedance (p less than 0.01) than the smaller electrodes. The mean threshold energy requirement was 0.12 +/- 0.01 joules/beat regardless of pad size. Output, current density, impedance and energy requirements did not vary with age, weight or chest size. No complications of external pacing were noted. We conclude that noninvasive transcutaneous pacing can be used safely and effectively in children, and that chest size might necessitate the use of smaller electrodes in children weighing less than 15 kilograms.