Accelerated EM reconstruction in total-body PET: potential for improving tumour detectability

Total-body positron emission tomography (PET) is a useful diagnostic tool for evaluating malignant disease. However, tumour detection is limited by image artefacts due to the lack of attenuation correction and noise. Attenuation correction may be possible using transmission data acquired after or simultaneously with emission data. Despite the elimination of attenuation artefacts, however, tumour detection is still hampered by noise, which is amplified during image reconstruction by filtered backprojection (FBP). We have investigated, as an alternative to FBP, an accelerated expectation maximization (EM) algorithm for its potential to improve tumour detectability in total-body PET. Signal to noise ratio (SNR), calculated for a tumour with respect to the surrounding background, is used as a figure of merit. A software tumour phantom, with conditions typical of those encountered in a total-body PET study using simultaneous acquisition, is used to optimize and compare various reconstruction approaches. Accelerated EM reconstruction followed by two-dimensional filtering is shown to yield significantly higher SNR than FBP for a range of tumour sizes, concentrations and counting statistics (deltaSNR = 6.3 +/- 3.9, p < 0.001). The methods developed are illustrated by examples derived from physical phantom and patient data.     

Immunocytochemical localization of oestrogen receptors in perichondrium of antlers in red deer (Cervus elaphus)

Remodelling of cancellous bone of antlers to compact bone can be stimulated by administration of oestrogens and previous work has demonstrated the presence of specific oestrogen binding in this tissue. In this study the presence of oestrogen receptors (ER) in antler tissue from red deer males was examined by immunocytochemistry using a monoclonal mouse anti-human ER serum. Strong positive staining was detected in the tip regions of immature antlers and was confined primarily to the cells forming a fibrous layer of the perichondrium. This finding indicates that the effects of oestrogens on remodelling of cancellous bone of the antler may be mediated indirectly by the surrounding connective tissue layers.     

Beta-carotene and lycopene, but not lutein, supplementation changes the plasma fatty acid profile of healthy male non-smokers

Polyunsaturated fatty acids (PUFAs) are highly susceptible to free radical attack. In vitro studies of carotenoids--including beta-carotene, lycopene, and lutein--have shown them to be effective quenchers of singlet oxygen, to have good radical-trapping properties, or to be effective peroxyl radical scavengers (or to have a combination of these qualities). If carotenoids act as antioxidants in vivo, then arguably, plasma PUFA should be conserved. The objective of the current study was to answer the question "Does supplementation with beta-carotene, lycopene, or lutein, at dietarily achievable levels, over a time period known to significantly increase circulating carote concentrations, lead to an observable increase in fasting plasma PUFA?" The normal diets of human volunteers were supplemented with either 15 mg/day beta-carotene (n = 25), lycopene (n = 23), or lutein (n = 21) for 26 days in three independent double-blind, placebo-controlled supplementation studies. Supplementation with beta-carotene increased plasma linoleic acid but left the polyunsaturated:saturated (P:S) fatty acid ratio unaltered. In contrast, supplementation with lycopene reduced linoleic acid, which resulted in a large decrease in the P:S ratio. Lutein supplementation had no effect. It was concluded that neither beta-carotene, lycopene, nor lutein supplementation engender antioxidant effects that lead to the widespread general conservation of plasma PUFAs. Beta-carotene and lycopene supplementation appear to interact with the metabolism of linoleic acid, the "essential" fatty acid, resulting in either an increase (beta-carotene) or decrease (lycopene) in its plasma concentration. Alterations in plasma 18:2 or P:S ratios could ultimately lead to changes in tissue cellular membrane composition and hence to alterations in membrane fluidity and cell-surface protein expression.     

NMDA and AMPA glutamate receptor subtypes in the thoracic spinal cord in lean and obese-diabetic ob/ob mice

Quantitative autoradiography was used to characterise the binding of selective radiolabelled antagonists for the N-methyl-D-aspartate (NMDA) receptor and the alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor in the dorsal, intermediate and ventral subregions of the grey matter of the upper thoracic spinal cord in male and female lean and obese-diabetic (ob/ob) mice. The density of binding sites for both receptor subtypes was greater in diabetic mice, in all three subregions of the grey matter, than the corresponding subregions in the lean mice. The affinity of the binding site for the NMDA antagonist was significantly higher in obese mice than lean mice, consistent with the presence of two subpopulations of NMDA receptors with different ligand binding affinities in obese mice. The increase in expression of the glutamate receptor subtypes, and altered ligand affinity for the NMDA receptor subtype in the obese mice may be causally involved in the peripheral neuropathies which can accompany diabetes mellitus.     

Health status of juvenile offenders. A survey of young offenders appearing before the juvenile courts

This paper reports on the health needs of a sample of juvenile offenders appearing before a Manchester Court during the month of August 1992. Of the 192 subjects interviewed (74% of those listed), 19% had significant medical problems, 42% a history of substance abuse and 7% psychiatric problems requiring further treatment. Substantial numbers (26%) engaged in a variety of dangerous behaviours. Custodial remands were common (21%), particularly in those with multiple psychosocial difficulties.     

Therapeutic Agents of Assertive Community Treatment

The goal of this study was to learn how assertive community treatment (ACT) contributes to the improvement of those with serious mental illness in order to contribute to the growing clinical literature regarding the therapeutic agents of ACT teams. Methods included reviewing the case records of three ACT clients who have improved significantly, as well as interviewing the clients themselves and their clinicians. The results indicated that there was significant agreement among the case records, the clients, and their clinicians in identifying the most useful aspects of assertive community treatment. Primary among these factors were the persistence demonstrated by ACT clinicians in engaging their clients, the trust that clients developed in their clinicians, and as a result, the process by which their clinicians became guides to the world of psychiatric and social services that further facilitated their clients' community adjustment. In closing, we consider implications from these findings both for staff development for ACT team members, and for suggestions toward the development of a model of recovery from serious mental illness.     

Avoiding malpractice in private practice and the hospital setting

An overview of very real considerations for the practicing plastic surgeon with regards to potential areas of risk and liability have been presented. As one can see, the hospital environment presents many potential sources of liability that can involve the attending or consulting plastic surgeon.     

Search for a gene x environment interaction: G x E hunt

We developed a method to identify gene x environment interactions (G x Es). To test this method in the simulated data (Problem 2, GAW11), we first identified an environmental factor (E1) that was associated with the simulated disorder. We stratified affected sibling pairs (ASPs) into two groups, those concordant for the presence of E1 and those concordant for the absence of E1. We then localized genes on chromosomes 3 and 5 using identity-by-descent (IBD) sharing rates among ASPs. Because the stratified IBD sharing rates are independent of the environmental factor if there is no G x E, we inferred the existence of a G x E near loci 3G44 and 3G45 by testing whether the proportion of ASPs sharing no alleles IBD differed among the two groups.