Radiofrequency treatment of tachyarrhythmias in children and adolescents

INTRODUCTION: Radiofrequency ablation has been extensively used in adults to treat supraventricular and ventricular tachycardia. In children and adolescents few data are available on its safety and efficacy. METHODS: 28 patients (mean age 12.8) with symptomatic tachyarrhythmias underwent catheter ablation; 21 children had atrioventricular accessory pathways (11 right connections, 9 lef connections and one midseptal pathway), 3 had intranodal tachycardia, 2 had ventricular tachycardia and 2 had atrial tachycardia. Only four patients had associated structural anomalies. RESULTS: Success rate was 71.4% (20 patients). The success per cents in each group were: in intranodal tachycardias 100%; we failed in the two patients with ventricular tachycardias; in accessory pathways 76.1% and 50% in atrial tachycardia. There were no recurrences of arrhythmia in a mean chase period of 24 months (12-46). Major complications were only observed in one patient who developed a Wallenberg syndrome after ablation. CONCLUSIONS: Radiofrequency catheter ablation appears to be a safe and effective method to treat arrhythmias in children and adolescents, which in most cases can supersede surgery. Alow incidence of complications is reported, although long term damage on endocardial structures remains yet to be determined.     

Functional activity of Na+,K(+)-pump in normal and pathological tissues

Na+,K(+)-ATPase, supporting the ionic homeostasis of the cell, is under control of Na+, K+, Mg2+, and ATP. The regulating effect of Mg2+ is rather unclear, whereas the Na+/K+ ratio in the cytoplasm is a potent regulatory factor, especially for osmotic balance in excitable cells. We have demonstrated two possibilities for regulation of ion pumping activity: First, via the number of Na+,K(+)-ATPase molecules under operation, and second, via changes in the turnover rate of the active molecules. In the presence of low ATP concentration, which is typical for cells with membrane damage (ischemic cardiac myocytes, tumor cells, fatigued muscles) Na+,K(+)-ATPase is transformed to a regime of the decreased efficiency. Radiation inactivation study demonstrates the weakening of the interprotein interactions in the enzyme complexes during ATP deficiency. Thus, measurements of ATPase activity of the purified enzyme under optimal conditions in vitro may be useless for the discrimination of pathological from normal tissues. In such a case, the estimation of lipid composition and microviscosity of the membranes under study could be important. This review briefly discusses several basic mechanisms of the regulation of Na+,K(+)-ATPase--an integral protein of the outer cell membranes.     

An assessment of the safety of pediatric ibuprofen. A practitioner-based randomized clinical trial

OBJECTIVE: To test the hypothesis that ibuprofen increases the risk of hospitalization for gastrointestinal bleeding, renal failure, or anaphylaxis among febrile children. DESIGN: Randomized double-blind acetaminophen-controlled trial. SETTING: Outpatient pediatric and family medicine practices. PATIENTS: A total of 84,192 children. INTERVENTION: Patients were randomly assigned to receive 12 mg/kg of acetaminophen, 5 mg/kg of ibuprofen, or 10 mg/kg of ibuprofen. MAIN OUTCOME MEASURES: Hospitalizations for acute gastrointestinal bleeding, acute renal failure, and anaphylaxis. RESULTS: A total of 277 patients (0.3%) were unavailable for follow-up. Overall, 795 participants (1%) were hospitalized, primarily for infectious diseases; hospitalization rates did not differ according to treatment group. Four children had diagnoses of acute, nonmajor gastrointestinal bleeding (two in each ibuprofen dosage group); among ibuprofen-treated children, the observed risk of gastrointestinal bleeding, 7.2 per 100,000 (95% confidence interval, 2 to 18 per 100,000), was not significantly different from the risk among acetaminophen-treated children (P = .31). There were no hospitalizations for acute renal failure or anaphylaxis; the upper 95% confidence bound for the risk of either of these outcomes was 5.4 per 100,000 ibuprofen-treated children. Among a number of other possibly serious adverse drug events, low white blood cell count was marginally associated with ibuprofen treatment. Because this association was observed in the setting of multiple comparisons and white blood cell counts may have been low before treatment, causation is unclear. CONCLUSIONS: The risk of hospitalization for gastrointestinal bleeding, renal failure, or anaphylaxis was not increased following short-term use of ibuprofen in children. These data, however, provide no information on the risks of less severe outcomes or the risks of prolonged ibuprofen use.     

Interrelationships between strains of Salmonella enteritidis belonging to phage types 4, 7, 7a, 8, 13, 13a, 23, 24 and 30

Cyclin A is a nuclear protein which is part of a kinase complex with either p34cdc2 or p33cdk2. Cyclin A is required in higher eukaryotic cells at the G1/S and the G2/M transitions. To examine the relationship between cyclin A and DNA replication, we simultaneously labeled exponentially growing HeLa cells for the distribution of cyclin A and proliferating cell nuclear antigen (PCNA). We have now demonstrated, by means of immunoelectron microscopy, that cyclin A is located at the sites of DNA replication visualized by both BrdU and PCNA labeling. Thus cyclin A may play a significant role in the phosphorylation of proteins at or near the sites of DNA replication.     

The role of genomic imprinting in implantation

OBJECTIVES: To outline the possible role of the imprinted genes in early human embryogenesis and implantation. DATA IDENTIFICATION: Literature review. STUDY SELECTION: Studies examining the issues of genomic imprinting, implantation, gestational trophoblastic diseases, placental gene expression, and trophoblast invasion. RESULTS: Certain genes have been shown to be expressed either in the embryo or in the uterine decidua before implantation. Some of these have been shown to be parentally imprinted, that is, expressed either from their paternal or maternal origin. The paternally expressed genes are linked to placental proliferation and invasiveness. CONCLUSIONS: Clinical and basic data from different disciplines indicate that genomic imprinting may be crucial to the process of implantation.     

Endometrial thickness: individual and mean growth profiles for different hormone replacement regimens

Currently, there is a paucity of data describing endometrial growth, with most studies concentrating on endometrial thickness immediately prior to implantation or embryo transfer. This study looked at the individual and combined growth profiles of 67 volunteers receiving three different hormone replacement regimens. Each treatment regimen was in excess of that considered necessary for optimal growth, and all promoted an endometrial thickness that would be considered satisfactory for embryo transfer. Three patterns of growth were identified, but overall there was a decrease in the rate of endometrial growth with duration of treatment. As expected, analysis of variance did not show a significant difference between the mean growth profiles for the three hormone replacement regimens. The correlation (r = 0.45, P < 0.0001) between rank order on day 3 and day 10 of treatment indicates that interim analysis during early treatment cannot accurately predict later thickness, but a doubling of endometrial thickness can be expected in most cases. A relationship between endometrial thickness and either the treatment dose or serum concentrations of oestradiol was not found. These findings suggest that manipulation of endometrial growth is not possible by adjustment of either the treatment dose or serum concentration. The findings indicate that treatment beyond 12 days does not promote either a clinically significant increase in endometrial thickness of an excessive thickness, suggesting that maintenance of an oocyte recipient in a pseudo-follicular phase is unlikely to be disadvantageous to implantation.