CT of appendicitis in children

PURPOSE: Our goal was to review the CT findings and to help define the role of CT in the evaluation of appendicitis in children. METHOD: Of 730 children with surgically proven appendicitis, 22 underwent preoperative CT evaluation. Their CT scans and operative and pathology records were retrospectively reviewed. The CT scans were evaluated for appendiceal wall thickness, diameter, and location, appendicoliths, pericecal inflammation, phlegmon, abscess, free fluid, small bowel dilatation, and bowel wall thickening. Criteria for diagnosing appendicitis were (a) appendiceal wall thickening (> 1 mm) or (b) presence of abscess, phlegmon, or pericecal inflammation associated with appendicolith(s). Prospective reports of ultrasound examinations performed within 2 days of the CT scans were available in 14 children and were correlated with the CT findings. RESULTS: An abnormally thickened appendix, with a diameter ranging from 9 to 18 mm, was seen in four children. Three appendices were retrocecal and one was near the cecal tip, anterior to the iliac vessels. Appendicoliths were present in 10 children, multiple in 1. Abscesses were seen in 13 of 22 children, multiple in 5. Phlegmon was seen in five children and pericecal inflammation in two. Bowel wall thickening was present in seven children and small bowel dilatation was noted in six. Other findings included free fluid, hydronephrosis, thickening of urinary bladder wall, air in the uterus and vagina, adenopathy, and thickening of the abdominal wall musculature. CT was diagnostic of appendicitis in 11 of 22 children (50%). In 14 children with both ultrasound and CT studies, CT was slightly better in diagnosing appendicitis and visualizing the abnormal appendix and was superior in defining the presence and extent of abscess and inflammation in 9 of 14 children. CONCLUSION: CT is a useful adjunct in diagnosing appendicitis in children, with a major role in cases of complicated appendicitis.     

Regulation in the heart field of zebrafish

In many vertebrates, removal of early embryonic heart precursors can be repaired, leaving the heart and embryo without visible deficit. One possibility is that this 'regulation' involves a cell fate switch whereby cells, perhaps in regions surrounding normal progenitors, are redirected to the heart cell fate. However, the lineage and spatial relationships between cells that are normal heart progenitors and those that can assume that role after injury are not known, nor are their molecular distinctions. We have adapted a laser-activated technique to label single or small patches of cells in the lateral plate mesoderm of the zebrafish and to track their subsequent lineage. We find that the heart precursor cells are clustered in a region adjacent to the prechordal plate, just anterior to the notochord tip. Complete unilateral ablation of all heart precursors with a laser does not disrupt heart development, if performed before the 18-somite stage. By combining extirpation of the heart precursors with cell labeling, we find that cells anterior to the normal cardiogenic compartments constitute the source of regulatory cells that compensate for the loss of the progenitors. One of the earliest embryonic markers of the premyocardial cells is the divergent homeodomain gene, Nkx2.5. Interestingly, normal cardiogenic progenitors derive from only the anterior half of the Nkx2.5-expressing region in the lateral plate mesoderm. The posterior half, adjacent to the notochord, does not include cardiac progenitors and the posterior Nkx2.5-expressing cells do not contribute to the heart, even after ablation of the normal cardiogenic region. The cells that can acquire a cardiac cell fate after injury to the normal progenitors also reside near the prechordal plate, but anterior to the Nkx2.5-expressing domain. Normally they give rise to head mesenchyme. They share with cardiac progenitors early expression of GATA 4. The location of the different elements of the cardiac field, and their response to injury, suggests that the prechordal plate supports and/or the notochord suppresses the cardiac fate.     

The effect of phototherapy on psychoautonomic disorders of a neurotic nature

Bright white light therapy was applied to 51 patients with syndrome of autonomic dysfunction of neurotic origin (1 hour of light exposure every day in the morning, during 2 weeks, 60 sm from the lamp, 3300 lux). Improvement occurred in 52% of the patients (responders--group 1, nonresponders--2). Changes occurred in nearly all symptoms: neuroendocrine, motivation, psychoautonomic, pain, psychopathologic. After the treatment in group 1 there was an increase of power of EEG spectrum, intensification of manifestations of the slow activity and decrease of the fast one from the two sides, an approach of the coefficient of asymmetry to the control levels as well as elevation of the urine excretion of metabolites of both catecholamines and serotonin. Initially higher power of EEG spectrum in group 2, became still more increased due to intensification of manifestations of theta and beta-2 rhythms from the two sides. Meanwhile coefficient of asymmetry was sharply decreased as well as general secretory activity inhibited. There were such symptoms and indices which had changed either negatively or positively under the influence of phototherapy.     

Broadband CDMA for personal communications systems

Multipath propagation in a broadband CDMA environment is described. A propagation model for broadband spread-spectrum signals is presented. Experimental results relating to the sharing of the band by fixed service microwave users and mobile personal communications network (PCN) users are discussed. Field tests indicate that PCN systems can provide high-quality communications when sharing the spectrum with fixed-service microwave systems in suburban and urban areas     

The structure and function of platelet-activating factor acetylhydrolases

Platelet-activating factor acetylhydrolases (PAF-AHs, EC 3.1.1.47) constitute a unique and biologically important family of phospholipase A2s. They are related to neither the well-characterized secretory nor cytosolic PLA2s, and unlike them do not require Ca2+ for catalytic activity. The distinguishing property of PAF-AHs is their unique substrate specificity: they act on the phospholipid platelet-activating factor (PAF), and in some cases on proinflammatory polar phospholipids, from which they remove a short acyl moiety--acetyl in the case of PAF--located at the sn-2 position. Because PAF is found both in the plasma and in the cytosol of many tissues, PAF-acetylhydrolases are equally widely distributed in an animal organism. Recent crystallographic studies shed new light on the complex structure-function relationships in PAF-AHs.     

Effect of contrast concentration on abdominal enhancement in the rabbit: spiral computed tomography evaluation

BACKGROUND: Langerhans' cell histiocytosis (LCH) is an uncommon, poorly understood granulomatous disease, characterized by the idiopathic proliferation of Langerhan's cells or their marrow precursors. In 1985, the Philadelphia Work-shop adopted the term "Langerhans' cell histiocytosis" (LCH) to differentiate it from reactive and neoplastic causes of histiocytosis. METHODS: This study includes 73 pediatric patients diagnosed with this condition in Dublin, Ireland, and Nottingham, England, during a 34-year period (1959 to 1993). These patients are reviewed with respect to clinical presentation, difficulty with making a histological diagnosis, their management, and outcome. RESULTS: A total of 49 patients (67%) had head and neck involvement. Bony involvement was the most frequent sign, most frequently located in the skull. There were 11 deaths (15%) in this series, all associated with multisystem disease, and nine of these deaths were in children younger than 2 years of age. CONCLUSIONS: The role of otolaryngologists is important in the early and accurate evaluation, staging, and diagnosis of LCH. It may mimic more common diseases, such as otitis externa, acute mastoiditis, skin rash, gingivitis, or cervical lymphadenopathy. Patients with multisystem disease may be so ill at presentation that the head and neck lesions may be overlooked. The current management of LCH has become increasingly conservative, and in the 1990s, fewer cases are given chemotherapy or radiotherapy. The prognosis is very good for single-system disease and poor for multisystem disseminated disease with early onset.