Malignant and benign breast tissue classification performance using a scatterer structure preclassifier

Benign and malignant breast tissue classification is examined for generalized-spectrum parameters computed from RF ultrasound data when a preclassification of subregions based on general scattering properties is performed. Results using a clinical database of 84 patients show statistically significant improvements (over 10% in receiver operation characteristic (ROC) areas) when only coherent scatterer subregions are used as compared to using all subregions within the region of interest.     

Causal modeling to estimate sensitivity and specificity of a test when prevalence changes

The suppressive effect of the halogenated inhalation anesthesia on cortical somatosensory evoked potentials (cSSEPs) has been well documented. Less studied and appreciated is the effect of nitrous oxide often with a narcotic as an alternative to a potent agent for spinal cord monitoring. This study sought to define more clearly the influence of nitrous oxide on cSSEPs elicited to posterior tibial nerve stimulation. A secondary purpose was to demonstrate the advantage of a total intravenous propofol anesthesia in facilitating uncompromised large-amplitude cSSEPs. Fifty adult patients undergoing anterior cervical discectomy served as the study sample. Brainstem and cortical posterior tibial nerve SSEPs were recorded under two independent anesthesia conditions, namely, nitrous oxide and propofol. Results demonstrated a significant amplitude reduction and latency prolongation with the nitrous oxide versus propofol protocol. cSSEP amplitude with propofol was, on the average, approximately two times larger than that with nitrous oxide. Based on these findings, the use of nitrous-oxide anesthesia is not recommended when limited to monitoring cSSEPs that are already amplitude compromised secondary to existing spinal cord disease.     

Reliability analysis of hierarchical computer-based systems subject to common-cause failures

The results from reliability modeling and analysis are key contributors to design and tuning activities for computer-based systems. Each architecture style, however, poses different challenges for which analytical approaches must be developed or modified. The challenge we address in this paper is the reliability analysis of hierarchical computer-based systems (HS) with common-cause failures (CCF). The dependencies among components introduced by CCF complicate the reliability analysis of HS, especially when components affected by a common cause exist on different hierarchical levels. We propose an efficient decomposition and aggregation (EDA) approach for incorporating CCF into the reliability evaluation of HS. Our approach is to decompose an original HS reliability analysis problem with CCF into a number of reduced reliability problems freed from the CCF concerns. The approach is represented in a dynamic fault tree by a proposed CCF gate modeled after the functional dependency gate. We present the basics of the EDA approach by working through a hypothetical analysis of a HS subject to CCF and show how it can be extended to an analysis of a hierarchical phased-mission system subject to different CCF depending on mission phases.     

Radiation therapy during pregnancy

A case of recovered memory of childhood trauma is reported with documented sexual trauma in early childhood, chronicled evidence of the absence of memory for traumatic experience over a period of time, and substantial evidence of 'spontaneous' recovery of memory. This account contains the first available prospective report of memory loss in a case in which there is both documented evidence of trauma and evidence of recovery of memory. The case emerged as part of a broadband, large-scale study of children followed closely from birth to adulthood which was not focused on memory for trauma. Prospective data gathered in a neutral research context, corroborated and supplemented by retrospective information, circumvent many limitations of previous retrospective accounts of recovered memories.     

Apolipoprotein E*3-Leiden transgenic mice as a test model for hypolipidaemic drugs

PURPOSE: We report an investigation into the distribution of proteoglycans (PGs) in normal, organ-cultured and dextran-treated human corneas. METHODS: Immunogold labeling was carried out at the electron microscope level to localize keratan sulphate (KS), chondroitin sulphate (CS), and heparan sulphate (HS) PGs. RESULTS: High levels of labeling for CS was found in the epithelium, endothelium, and keratocytes, with light labelling present in the basement membranes and the corneal stroma. Labeling for HS was present in the epithelium, endothelium, and keratocytes, with intense labeling present at the endothelium/Descemet's membrane interface and the epithelium/Bowman's layer interface. Large filaments were also observed in these regions in cuprolinic blue-stained specimens. Keratan sulphate was present at high levels in the stroma and the basement membranes with low levels present within the keratocytes, epithelium, and endothelium. The pattern of KS labeling along the collagen fibrils in the stroma sometimes showed evidence of periodicity. Organ-cultured corneas had extensive collagen-free "lakes," the interior of which immunolabeled positively for KS and showed staining with cuprolinic blue. The lakes were greatly reduced in the dextran-treated samples. CONCLUSION: This investigation determined the ultrastructural distribution of KS, CS, and HS PGs in human cornea and showed that organ culture is associated with a change in distribution of stromal PGs.     

The limit of viability--neonatal outcome of infants born at 22 to 25 weeks' gestation

BACKGROUND: With improved survival of preterm infants, questions have been raised about the limit of viability. To provide better information and counseling for parents of infants about to be delivered after 22 to 25 weeks' gestation, we evaluated the mortality and neonatal morbidity of preterm infants born at these gestational ages. METHODS: We studied retrospectively all 142 infants born at 22 to 25 weeks' gestation (as judged by best obstetrical estimate) from May 1988 through September 1991 in a single hospital. Mortality in the first six months, including stillbirths, and neonatal morbidity (i.e., the presence of intracranial pathologic conditions, chronic lung disease, and retinopathy of prematurity) were analyzed. RESULTS: Fifty-six infants (39 percent) survived for six months. Survival improved with increasing gestational age; none of 29 infants born at 22 weeks' gestation survived, as compared with 6 of 40 (15 percent) born at 23 weeks, 19 of 34 (56 percent) born at 24 weeks, and 31 of 39 (79 percent) born at 25 weeks. There were seven stillbirths at 22 weeks' gestation and four stillbirths at 23 weeks. The more immature the infant, the higher the incidence of neonatal complications as determined by the number of days of mechanical ventilation, the length of the hospital stay, and the presence of retinopathy of prematurity, periventricular or intraventricular hemorrhage, or periventricular leukomalacia. Only 2 percent of infants born at 23 weeks' gestation survived without severe abnormalities on cranial ultrasonography, as compared with 21 percent of those born at 24 weeks and 69 percent of those born at 25 weeks. CONCLUSIONS: We believe that aggressive resuscitation of infants born at 25 weeks' gestation is indicated, but not of those born at 22 weeks. Whether the occasional child who is born at 23 or 24 weeks' gestation and does well justifies the considerable mortality and morbidity of the majority is a question that should be discussed by parents, health care providers, and society.