Neonatal imaging.

This article reviews diagnostic imaging of newborns, beginning with a discussion of helpful approaches and safety concerns and an overview of imaging techniques used. The author then presents a variety of common neonatal disorders and their radiologic appearance.

Radiography of bone tumors and lesions.

This Directed Reading reviews the biology and classification of bone tumors, forms of primary bone tumors and techniques for imaging these lesions.

Nuclear medicine infection imaging.

This Directed Reading introduces the reader to basic immunological processes related to infection scintigraphy and describes the radiopharmaceuticals used in this type of imaging. Following a discussion of radiation safety and infection control, the article explains various applications of nuclear medicine for detecting and assessing infection.

Coronary artery disease and electron-beam CT.

Because its precision allows early detection of atherosclerotic processes in patients exhibiting no or few symptoms, electron-beam computed tomography (EBCT) will play an increasingly important role in the assessment of coronary artery disease (CAD). This article provides an introduction to CAD, traditional imaging approaches for its assessment, and the rationale and methods used in CAD-related EBCT imaging. The article also discusses the promise and limitations of using EBCT to detect, assess and monitor CAD, particularly in asymptomatic patients.

Bone fracture fixation.

This article reviews the anatomy, physiology and biomechanics of bone and describes various types of fractures. It discusses the comparative advantages of different imaging techniques for fracture diagnosis and the radiographic characteristics of some common fractures. The article concludes with a description of fixation techniques and the role of imaging after treatment.

Radiologic assessment of schizophrenia.

Schizophrenia is a debilitating psychotic disorder. Neuroimaging, particularly magnetic resonance and computed tomography, plays a central role in describing schizophrenia and in characterizing its progression from mild childhood symptoms to adult psychosis. This article introduces readers to schizophrenia, its precursors, risk factors, progressive symptomatology and imaging techniques used to assess the disease.

Developmental stability and human violence.

Developmental stability (the precision with which genotypes are translated into phenotypes under physically stressful developmental conditions), is a major source of phenotypic and behavioural variation, yet researchers have largely ignored its potential role in the ontogeny of individual propensities toward human aggression and violence. In this study, we measured fluctuating asymmetry of the body and administered aggression and fighting history questionnaires to 229 college students (139 female and 90 male undergraduates). Among males, but not females, fluctuating asymmetry correlated negatively and significantly with the participants' number of fights and propensity to escalate agonistic encounters to physical violence. Principal components analyses and scree tests suggested that two psychometric factors underlie observed correlations between self-report measures of aggressive tendencies. The first factor, 'aggressive negative affect', reflected verbal aggression and hostility toward others, while the second factor, 'self-assessed fighting ability', reflected physical violence and a tendency to win fights. The two factors correlated minimally. For both males and females, the second factor correlated with number of fights while the first factor did not. Fluctuating asymmetry did not significantly correlate with either factor for either sex, but for both sexes, psychometric intelligence (IQ) correlated positively with the first factor.

Enteroendocrine peptides in a canine model of orthotopic jejunoileal autotransplantation.

The enteroendocrine cells of the small bowel provide a rich source of regulatory peptides involved in the modulation of gastrointestinal function. Recent work from our laboratory showed that in situ neural isolation (autotransplantation) of the jejunoileum produced marked changes in tissue expression of several neuropeptides. In the present study, we examined the influence of extrinsic innervation on the tissue expression of endocrine peptides localized to various regions of the gastrointestinal tract. Concentrations of immunoreactive gastric inhibitory polypeptide (GIP), neurotensin (NT) and peptide tyrosine tyrosine (PYY) in fasting plasma and regional tissue biopsies were determined before and at varying time points (2, 6, 12 weeks) after a model of canine orthotopic jejunoileal autotransplantation. GIP was not altered in plasma or tissue at any time point. Plasma concentrations of NT and PYY increased after autotransplantation. Following a decrease in tissue concentrations two weeks after autotransplantation, NT increased progressively from 2 to 6 to 12 weeks, reaching a maximal increase of 895% over baseline in proximal ileum. Tissue concentrations of PYY followed much the same pattern as NT, but these trends never achieved statistical significance. Chromatographic characterization of tissue biopsy extracts revealed molecular heterogeneity of NT-like immunoreactivity, while GIP and PYY immunoreactivity coeluted as single species with authentic standards. Taken together with our earlier observations, it appears that disruption of extrinsic and intrinsic neural continuity to the jejunoileum (autotransplantation) does not affect gut endocrine peptides such as GIP and PYY to the same extent as enteric neuropeptides. NT has been localized to neural as well as endocrine cells and is involved in the temporal adaptive response to autotransplantation.

Responses of gastrointestinal peptides and motor activity to milk and water feedings in preterm and term infants.

Because duodenal motor activity differs between preterm and term infants during fasting, this study evaluated the responses of motor activity and peptide release in response to feeding. In the first study, fasting concentrations of gastrin, gastric inhibitory peptide, neurotensin, and peptide YY (PYY) were determined in 53 preterm and 20 term infants. Plasma concentrations of gastrin and neurotensin were significantly lower in preterm infants than in healthy adults reported previously by our lab (p less than 0.01). Plasma concentration of gastric inhibitory peptide and PYY were higher than in healthy adults (p less than 0.01). Gastrin concentrations in preterm and term infants varied directly with gestational age (p less than 0.005); PYY varied inversely with gestational age (p less than 0.005). In a secondary study, intestinal manometry was recorded and serial peptide concentrations were determined in 43 preterm babies who were given their first enteral feeding intraduodenally with formula or sterile water. Although none of the four peptide plasma concentrations changed in response to feeding with water, plasma concentrations of gastric inhibitory peptide, neurotensin, and PYY significantly increased with formula feedings (p less than 0.05 or less). In addition, plasma gastrin increased significantly in seven infants fed milk compared with eight fed water by orogastric tube (p less than 0.01). In contrast to the peptide response to feeding, motor activity changed in response to feeding with either water or milk; motility indices increased and periods of motor quiescence decreased significantly during feeding as compared with fasting (p less than 0.02). Responses of both motor activity and peptides to feeding were time related.(ABSTRACT TRUNCATED AT 250 WORDS)