Automatic external defibrillation in a 6 year old.

A case is reported in which an automatic external defibrillator (AED) was used during the successful resuscitation of a 6 year old child in out-of-hospital cardiac arrest, despite the fact that these devices are not recommended in children under 8 years. The interpretation of resuscitation protocols is discussed and new developments in this area reported.     

Magnetic resonance imaging: absence of in vitro cytogenetic damage

Human lymphocytes and Chinese hamster ovary (CHO) cells in culture were exposed for 12 1/2 hours to a magnetic resonance imaging apparatus with a 2.35-Tesla magnet and 100-MHz radio frequency emission. The cells were examined for cytogenetic damage manifested either as chromosome aberrations or sister chromatid exchanges (SCEs), which constitute very sensitive measures of genetic and cellular damage. In either unstimulated or stimulated human lymphocytes, as well as in exponentially growing CHO cells, no increase in either chromosome aberrations or SCEs was found as a result of exposure to these MR conditions. The data indicate that long-term exposure to MR imaging conditions far exceeding those to be found in the clinical situation does not cause cytogenetic damage.     

The quantitative analysis and stability of histochemical markers of altered hepatic foci in rat liver following initiation by diethylnitrosamine administration and promotion with phenobarbital

The stability and response of histochemical phenotypes of altered hepatic foci (AHF) were studied both in the presence and following the withdrawal of 0.05% phenobarbital (PB) treatment in rats previously given a single dose of diethylnitrosamine (DEN) 20-24 h following partial hepatectomy (PH). AHF were scored by their expression of three biochemical markers: gamma-glutamyl transpeptidase (GGT), adenosine triphosphatase and glucose-6-phosphatase (G6P). AHF demonstrated significant heterogeneity with respect to the marker alterations. The use of three markers in the present study confirmed the findings of our earlier study, which showed the maximal response of GGT+ AHF to PB administration following PH/DEN initiation and the stability of GGT+/AHF induced by the PH/DEN/PB regimen after the withdrawal of PB. In the regimen employed, the GGT marker alone scored the great majority of the AHF detected by all three markers. The frequency distribution of histochemical phenotypes remained relatively constant in AHF during continuous PB administration and in AHF promoted by PB followed by a 6-month period of feeding a diet containing no PB. These findings suggest that individual AHF remain phenotypically stable throughout the PB promotion phase, i.e., do not progress from one phenotype to another. In every marker class, the mean volume of AHF increased during continuous PB administration. These data illustrate the enhancing effect of PB on the growth of the AHF. The size of AHF continued to increase following the withdrawal of PB in the 3-month PB treatment group, but not in the animals treated for 4 months. A mechanism that may account for the differences in these two treatment groups is discussed.     

咪苯嗪酮对TXA2和HHT生成的选择性抑制作用

咪苯嗪酮(CI-914)能抑制大鼠血小板环氧酶和TXA₂合成酶产物HHT的生成,而对脂氧酶产物12-HETE的生成仅高浓度药物才有弱的抑制作用,提示CI-914主要影响花生四烯酸(AA)环氧酶途径,而对脂氧酶途径影响较少。在大鼠血小板和中性白细胞CI-914能抑制TXA₂的生成,同时CI-914还可使白细胞6-keto-PGF_1a和血小板PGE₂的产生量显著增加,提示CI-914在这两种细胞引起了AA的转向合成。上述结果基本证实,CI-914在大鼠中性白细胞和血小板对TXA₂合成酶具有选择性抑制作用。