Appendiceal CT in pediatric patients: relationship of visualization to amount of peritoneal fat

OBJECTIVE: This study was performed to determine the rate of visualization of the normal pediatric appendix on CT and to evaluate the relationship of the appendix to parameters such as amount of intraperitoneal fat, use of contrast material, patient age, and slice thickness. MATERIALS AND METHODS: Three board-certified radiologists retrospectively reviewed 248 successive pediatric abdominal and pelvic CT examinations performed from 1995 to 1999. Each radiologist independently assessed the degree of intraperitoneal fat (minimal, moderate, or marked compared with a standard slice), appendiceal visualization (definite, unsure, not seen), cecal and terminal ileal opacification, and the outer diameter of visualized appendixes. The age and sex of the patient, collimation thickness (3-10 mm), and use of enteric or IV contrast material was also recorded. RESULTS: A normal appendix was identified in 120 (48.4%) of 248 examinations. The only individual variable with statistically significant correlation was the degree of intraperitoneal fat. This was determined using the Pearson chi-square test, the likelihood ratio, and logistic regression. The appendix was seen in 68.8% (n = 93) of patients with moderate or marked intraperitoneal fat versus 36.1% (n = 155) with minimal fat (p<0.001). A trend toward decreased visualization in children younger than 10 years old with minimal peritoneal fat was identified and confirmed with a 95% confidence limit. The outer diameter of the visualized appendix varied from 3 to 10 mm, with a mean value of 6 mm. CONCLUSION: Increased peritoneal fat significantly increases the rate of identification of the normal appendix in pediatric patients. Although less fat is generally seen in younger patients, there is significant overlap of appendix visualization among age groups.     

Transnasal removal of a biliary endoprosthesis with percutaneous transhepatic biliary catheter replacement

The authors describe a novel fluoroscopically guided transnasal technique for removal of an endoscopically placed endobiliary prosthesis (EBP). A case in which the approach was applied is used to demonstrate its indications, clinical utility and possible benefits. The procedure entails simultaneous percutaneous replacement of the EBP with an internal/external biliary catheter over a through-and-through transhepatic/transnasal access wire. A comparison of the technique's limitations with those of traditional approaches for endoscopic or percutaneous EBP removal and replacement is presented.     

Effects of the mGluR2/3 agonist LY354740 on computerized tasks of attention and working memory in marmoset monkeys

Rationale LY354740 is a recently developed metabotropic glutamatergic receptor 2 and 3 (mGluR2/3) agonist. A high density of mGluR2 has been reported in terminal fields of the perforant path in rodents and humans, suggesting its involvement in cognitive functions mediated by the temporal lobe, including memory. A small number of in vivo studies in rodents have assessed the effects of LY354740 on memory tasks, reporting the induction of impaired memory for spatial orientation in a water maze task and for delayed match and non-match to position in an operant version of these tasks.Objective In the present primate study, we used radioautography to describe the distribution and intensity of ³H-LY354740 binding in the hippocampal formation of the common marmoset monkey (Callithrix jacchus) relative to the rat. In the major, in vivo part of the study, the effects of systemic LY354740 on computerized tasks of attention and memory were investigated.Methods Adult common marmosets were trained to perform a five-choice serial reaction time (5-CSRT) task and a concurrent delayed match-to-position (CDMP) task from the Cambridge Neuropsychological Automated test Battery (CANTAB). Filter tests of LY354740 effects on motor dexterity and motivation for reward revealed high inter-individual variation in sensitivity; therefore, on the 5-CSRT, subjects were tested at a dose range of 3–10 mg/kg, and on the CDMP, subjects were tested at 1–3 or 3–10 mg/kg.Results Radioautography revealed a relatively low level of ³H-LY354740 binding in the marmoset hippocampal formation compared to the rat. Despite low binding, LY354740 reduced sustained-attention accuracy in the 5-CSRT, and reduced accuracy in two stages of the CDMP.Conclusions The current study provides novel evidence for the importance of mGluR2/3 in the regulation of primate cognitive functioning.