Iterative 4D reconstruction of dynamic SPECT images

[Abstract] The 22nd International Congress and Exhibition, Barcelona, Spain, June 25-28, 2008The present work presents a new approach for the 4D reconstruction algorithm for dynamic SPECT in a parallel ray geometry based on B-splines including attenuation map from CT and geometry efficiency correction. In this work we make use of 4 piecewise piecewise quadratic temporal splines and a reconstruction algorithm based on the iterative maximization of Poisson likelihood. Results on a Tecnetium (99mTc-Teboroxime) canine study are shownPublicad

Statistical 4D reconstruction of dynamic CT images: preliminary results

[Poster] 4th European Molecular Imaging Meeting, Barcelona, Spain, May 27 - 30, 2009Preliminary results are presented of a 4d reconstruction algorithm for dynamic contrast enhanced CT, in a micro-CT based on cone beam geometry. The method is based on modelling the spatial and temporal distribution of the contrast inside the field of view. The use of non-uniform time sampling with b-splines yielded smooth time-activity curves that captured the relatively fast rise and fall of contrast in the aorta, as well as the uptake and retention of contrast in the kidneysThis work is supported by Ministerio de Ciencia e innovación (TeC2008-06715-C02-01 and TeC2007-64731/TCM), Ministerio de industria (CdTeaM, Programa CeniT), and the reCaVa-reTiC network.Publicad

Application of next-generation sequencing to Enterobacter hormaechei subspecies analysis during a neonatal intensive care unit outbreak

Introduction: The Enterobacter cloacae complex (ECC) species are potential neonatal pathogens, and ECC strains are among the most commonly encountered Enterobacter spp. associated with nosocomial bloodstream infections. Outbreaks caused by ECC can lead to significant morbidity and mortality in susceptible neonates. At the molecular level, ECC exhibits genomic heterogeneity, with six closely related species and subspecies. Genetic variability poses a challenge in accurately identifying outbreaks by determining the clonality of ECC isolates. This difficulty is further compounded by the limitations of the commonly used molecular typing methods, such as pulsed field gel electrophoresis, which do not provide reliable accuracy in distinguishing between ECC strains and can lead to incorrect conclusions. Next-generation sequencing (NGS) offers superior resolution in determining strain relatedness. Therefore, we investigated the clinical pertinence of incorporating NGS into existing bundle measures to enhance patient management during an outbreak of ECC in a level-3 neonatal intensive care unit (NICU) in Germany. Methods: As the standard of care, all neonates on the NICU received weekly microbiological swabs (nasopharyngeal and rectal) and analysis of endotracheal secretion, where feasible. During the 2.5-month outbreak, colonisation with ECC was detected in n = 10 neonates. The phylogenetic relationship and potential antimicrobial resistance genes as well as mobile genetic elements were identified via bacterial whole-genome sequencing (WGS) using Illumina MiSeq followed by in silico data analysis. Results: Although all ECC isolates exhibited almost identical antimicrobial susceptibility patterns, the WGS data revealed the involvement of four different ECC clones. The isolates could be characterised as Enterobacter hormaechei subspecies steigerwaltii (n = 6, clonal), subsp. hoffmannii (n = 3, two clones) and subsp. oharae (n = 1). Despite the collection of environmental samples, no source of this diffuse outbreak could be identified. A new standardised operating procedure was implemented to enhance the management of neonates colonised with MRGN. This collaborative approach involved both parents and medical professionals and successfully prevented further transmission of ECC. Conclusions: Initially, it was believed that the NICU outbreak was caused by a single ECC clone due to the similarity in antibiotic resistance. However, our findings show that antibiotic susceptibility patterns can be misleading in investigating outbreaks of multi-drug-resistant ECC. In contrast, bacterial WGS accurately identified ECC at the clonal level, which significantly helped to delineate the nature of the observed outbreak

Structural Features Underlying Raloxifene’s Biophysical Interaction with Bone Matrix

Raloxifene, a selective estrogen receptor modulator (SERM), reduces fracture risk at least in part by improving the mechanical properties of bone in a cell- and estrogen receptor-independent manner. In this study, we determined that raloxifene directly interacts with the bone tissue. Through the use of multiple and complementary biophysical techniques including nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR), we show that raloxifene interacts specifically with the organic component or the organic/mineral composite, and not with hydroxyapatite. Structure–activity studies reveal that the basic side chain of raloxifene is an instrumental determinant in the interaction with bone. Thus, truncation of portions of the side chain reduces bone binding and also diminishes the increase in mechanical properties. Our results support a model wherein the piperidine interacts with bone matrix through electrostatic interactions with the piperidine nitrogen and through hydrophobic interactions (van der Waals) with the aliphatic groups in the side chain and the benzothiophene core. Furthermore, in silico prediction of the potential binding sites on the surface of collagen revealed the presence of a groove with sufficient space to accommodate raloxifene analogs. The hydroxyl groups on the benzothiophene nucleus, which are necessary for binding of SERMs to the estrogen receptor, are not required for binding to the bone surface, but mediate a more robust binding of the compound to the bone powder. In conclusion, we report herein a novel property of raloxifene analogs that allows them to interact with the bone tissue through potential contacts with the organic matrix and in particular collagen

Isolated bladder exstrophy associated with a de novo 0.9 Mb microduplication on chromosome 19p13.12.

The exstrophy-epispadias complex (BEEC) is a urogenital birth defect of varying severity. The causes of the BEEC are likely to be heterogeneous, with individual environmental or genetic risk factors still being largely unknown. In this study, we aimed to identify de novo causative copy number variations (CNVs) that contribute to the BEEC. METHODS Array-based molecular karyotyping was performed to screen 110 individuals with BEEC. Promising CNVs were tested for de novo occurrence by investigating parental DNAs. Genes located in regions of rearrangements were prioritized through expression analysis in mice to be sequenced in the complete cohort, to identify high-penetrance mutations involving small sequence changes. RESULTS A de novo 0.9 Mb microduplication involving chromosomal region 19p13.12 was identified in a single patient. This region harbors 20 validated RefSeq genes, and in situ hybridization data showed specific expression of the Wiz gene in regions surrounding the cloaca and the rectum between GD 9.5 and 13.5. Sanger sequencing of the complete cohort did not reveal any pathogenic alterations affecting the coding region of WIZ. CONCLUSIONS The present study suggests chromosomal region 19p13.12 as possibly involved in the development of CBE, but further studies are needed to prove a causal relation. The spatiotemporal expression patterns determined for the genes encompassed suggest a role for Wiz in the development of the phenotype. Our mutation screening, however, could not confirm that WIZ mutations are a frequent cause of CBE, although rare mutations might be detectable in larger patient samples

Measurements of NaI:Tl Electron Response using SLYNCI: Comparison of Different Samples

This paper measures the sample to sample variation in the light yield non-proportionality of NaI:Tl, and so explores whether this is an invariant characteristic of the material or whether it is dependent on the chemical and physical properties of tested sample. In this work we report on the electron response of nine crystals of NaI(Tl), differing in shape, volume, age, manufacturer and quality. The non-proportionality has been measured at the SLYNCI facility in the energy range between 3.5 to 460 keV. The Scintillation Light Yield Non-proportionality Characterization Instrument (SLYNCI) is a next generation Compton Coincidence device, explicitly designed to study the 'non-proportionality' of the electron response in scintillators and the contribution of this effect to the intrinsic energy resolution. We also discuss the gamma response, x-ray excited emission spectra and decay times for the nine crystals, in order to provide a complete characterization of their physical properties and determine whether the mechanism of scintillation varies between samples

Bodyweight Perceptions among Texas Women: The Effects of Religion, Race/Ethnicity, and Citizenship Status

Despite previous work exploring linkages between religious participation and health, little research has looked at the role of religion in affecting bodyweight perceptions. Using the theoretical model developed by Levin et al. (Sociol Q 36(1):157–173, 1995) on the multidimensionality of religious participation, we develop several hypotheses and test them by using data from the 2004 Survey of Texas Adults. We estimate multinomial logistic regression models to determine the relative risk of women perceiving themselves as overweight. Results indicate that religious attendance lowers risk of women perceiving themselves as very overweight. Citizenship status was an important factor for Latinas, with noncitizens being less likely to see themselves as overweight. We also test interaction effects between religion and race. Religious attendance and prayer have a moderating effect among Latina non-citizens so that among these women, attendance and prayer intensify perceptions of feeling less overweight when compared to their white counterparts. Among African American women, the effect of increased church attendance leads to perceptions of being overweight. Prayer is also a correlate of overweight perceptions but only among African American women. We close with a discussion that highlights key implications from our findings, note study limitations, and several promising avenues for future research

The Exstrophy-epispadias complex

Exstrophy-epispadias complex (EEC) represents a spectrum of genitourinary malformations ranging in severity from epispadias (E) to classical bladder exstrophy (CEB) and exstrophy of the cloaca (EC). Depending on severity, EEC may involve the urinary system, musculoskeletal system, pelvis, pelvic floor, abdominal wall, genitalia, and sometimes the spine and anus. Prevalence at birth for the whole spectrum is reported at 1/10,000, ranging from 1/30,000 for CEB to 1/200,000 for EC, with an overall greater proportion of affected males. EEC is characterized by a visible defect of the lower abdominal wall, either with an evaginated bladder plate (CEB), or with an open urethral plate in males or a cleft in females (E). In CE, two exstrophied hemibladders, as well as omphalocele, an imperforate anus and spinal defects, can be seen after birth. EEC results from mechanical disruption or enlargement of the cloacal membrane; the timing of the rupture determines the severity of the malformation. The underlying cause remains unknown: both genetic and environmental factors are likely to play a role in the etiology of EEC. Diagnosis at birth is made on the basis of the clinical presentation but EEC may be detected prenatally by ultrasound from repeated non-visualization of a normally filled fetal bladder. Counseling should be provided to parents but, due to a favorable outcome, termination of the pregnancy is no longer recommended. Management is primarily surgical, with the main aims of obtaining secure abdominal wall closure, achieving urinary continence with preservation of renal function, and, finally, adequate cosmetic and functional genital reconstruction. Several methods for bladder reconstruction with creation of an outlet resistance during the newborn period are favored worldwide. Removal of the bladder template with complete urinary diversion to a rectal reservoir can be an alternative. After reconstructive surgery of the bladder, continence rates of about 80% are expected during childhood. Additional surgery might be needed to optimize bladder storage and emptying function. In cases of final reconstruction failure, urinary diversion should be undertaken. In puberty, genital and reproductive function are important issues. Psychosocial and psychosexual outcome depend on long-term multidisciplinary care to facilitate an adequate quality of life

Enhancing precision in human neuroscience

Human neuroscience has always been pushing the boundary of what is measurable. During the last decade, concerns about statistical power and replicability - in science in general, but also specifically in human neuroscience - have fueled an extensive debate. One important insight from this discourse is the need for larger samples, which naturally increases statistical power. An alternative is to increase the precision of measurements, which is the focus of this review. This option is often overlooked, even though statistical power benefits from increasing precision as much as from increasing sample size. Nonetheless, precision has always been at the heart of good scientific practice in human neuroscience, with researchers relying on lab traditions or rules of thumb to ensure sufficient precision for their studies. In this review, we encourage a more systematic approach to precision. We start by introducing measurement precision and its importance for well-powered studies in human neuroscience. Then, determinants for precision in a range of neuroscientific methods (MRI, M/EEG, EDA, Eye-Tracking, and Endocrinology) are elaborated. We end by discussing how a more systematic evaluation of precision and the application of respective insights can lead to an increase in reproducibility in human neuroscience