A Study of Through-Space and Through-Bond JPP Coupling in a Rigid Nonsymmetrical Bis(phosphine) and Its Metal Complexes.

A series of representative late d-block metal complexes bearing a rigid bis(phosphine) ligand, iPr2P-Ace-PPh2 (L, Ace = acenaphthene-5,6-diyl), was prepared and fully characterized by various techniques, including multinuclear NMR and single-crystal X-ray diffraction. The heteroleptic nature of the peri-substituted ligand L allows for the direct observation of the JPP couplings in the 31P{1H} NMR spectra. Magnitudes of JPP are correlated with the identity and geometry of the metal and the distortions of the ligand L. The forced overlap of the phosphine lone pairs due to the constraints imposed by the rigid acenaphthene skeleton in L results in a large 4 JPP of 180 Hz. Sequestration of the lone pairs, either via oxidation of the phosphine or via metal chelation, results in distinct changes in the magnitude of JPP. For tetrahedral d10 complexes ([LMCl2], M = Zn, Cd, Hg), the JPP is comparable to or larger than (193-309 Hz) that in free ligand L, although the P···P separation in these complexes is increased by ca. 0.4 Å (compare to free ligand L). The magnitude of JPP diminishes to 26-117 Hz in square planar d8 complexes ([LMX2], M = Ni, Pd, Pt; X = Cl, Br) and the octahedral Mo0 complex ([LMo(CO)4], 33 Hz). Coupling deformation density calculations indicate the through-space interaction dominates in free L, while in metal complexes the main coupling pathway is via the metal atom.

Distribution and trends of mercury in deciduous tree cores.

The distribution of total mercury (THg) within common deciduous trees and the applicability of tree cores as biomonitors of historical environmental THg trends were assessed for both contaminated and reference sites around Kingston, Ontario. Samples were collected from Acer spp., Quercus spp. Populus spp. and Salix spp. Bark and wood THg concentrations were found to be highly correlated whereas soil and wood THg concentrations were not. There were no temporal relationships for THg in dated tree rings corresponding with any other known environmental Hg trends. The shoreline species, Populus and Salix spp., had the greatest bark and wood Hg concentrations reaching 18 ng/g, significantly higher than for inland trees Quercus and Acer spp. with maximum values of 7 and 1.2 ng/g for bark and wood respectively. While tree cores cannot be reliably used as temporal THg biomonitors, there is promise for tree species such as Populus spp and Salix spp as spatial indicators of local long-term Hg contamination.

Fine-scale mercury trends in temperate deciduous tree leaves from Ontario, Canada.

This study focused on the value of deciduous leaves as biomonitors of total mercury (THg). Leaf samples were collected from a range of deciduous species from five sampling sites in the province of Ontario, Canada. These included a site in the northwest (the Experimental Lakes Area, ELA), two sites in central Ontario (the town of Dorset and the Centre for Atmospheric Research Experiments, CARE), and two sites in the southeast (Sandbanks Provincial Park, SBPP and the City of Kingston). The sampled species exhibited distinctive species-specific differences with red oaks consistently having lower leaf THg concentrations than all maple species, while black and white ash leaves had the highest concentrations. Spatially, leaves collected across the distance between ELA and SBPP (approximately 1500 km apart) had overlapping THg concentrations between 20 and 40 ng/g. Unexpectedly, leaves from urban parks of Kingston had considerably lower THg concentrations (<25 ng/g) than the other sites, which suggested leaves may not reflect subtle gradients of atmospheric THg found under field conditions. Leaf THg increased with the growing season, with highest THg leaf concentrations found in early autumn just before senescence. Microspatial differences within a single tree, such as position on a branch are important, since higher mercury concentrations were associated with leaves positioned deeper into the canopy relative to outer leaves more exposed to wind turbulence and sunlight. Within any single leaf, THg concentrations were highest in the leaf tissue, and consistently distributed, while the vein and petiole tissue had lower THg concentrations. There was no relationship between THg concentrations and leaf area. Using deciduous tree leaves as regional temporal monitors of bioavailable mercury may be feasible, but careful selection of leaf sampling sites on the tree itself and the timing is of utmost importance for ensuring consistent and high quality biomonitoring data.

Factors associated with one step surgery in case of non-palpable breast cancer.

PURPOSE: To examine factors associated with one step surgery in case of non-palpable breast cancer. MATERIALS AND METHODS: Clinical data of 152 consecutively diagnosed patients with breast cancer were analyzed retrospectively. Preoperative diagnostic findings were divided in subgroups: mammographically visible mass/microcalcifications/sonographically visible mass/sonographically visible architectural distortion. Correlation between tumor-size, radiologic tumor morphology, quality of localization and number of operation was evulated. For localization exact wire position was defined less than 3mm apart from the lesion. RESULTS: One hundred and thirty-six patients attempted breast conservation and underwent preoperative tumor localization. Fourteen of 16 patients had mastectomy without preoperative localization. Average tumor size was 12mm for one-operation, and 17mm for re-operation. Significant correlation (p<0.001) was found between one operation and masses visible in mammograms (55/62 (89%) patients) or sonography (53/64 (83%) patients). Significant correlation was found (p<0.001) between more re-operation and microcalcifications in mammograms (33/89 (37% patients). In 123/138 (89%) cases wire position was central, in 15/138 (11%) cases distance was maximally 10mm. No significant correlation was found between number of operation and wire position. Re-operation was required in 38 cases. CONCLUSION: Mammographically or sonographically visible mass, small size of tumors, preoperative percutaneous biopsy and exact preoperative localization are important for a single step procedure for definite surgical treatment, that we found in 74% of the patients.

Stress proteins as targets for anti-inflammatory therapies.

Microbial heat shock proteins (HSPs) are ubiquitous and highly immunogenic. In healthy humans, B- and T-cells with specificity for self-HSP can be easily detected. In patients with chronic inflammatory diseases, raised levels of antibodies and T-cells with reactivity to self-HSP have been observed. Based on this and other evidence, this raised immune reactivity might be the result of stress-induced upregulation of self-HSP during inflammation and is possibly caused by tissue destruction. More importantly, immunization with conserved sequences of microbial-HSP increases resistance to the induction of autoimmune disease. Together, it appears that immune reactivity directed towards self-HSP can be part of a regulatory immune effector mechanism that contributes to maintenance of self-tolerance and has anti-inflammatory activity. Boosting of such anti-inflammatory effector mechanisms by artificial immunization offers attractive immunotherapeutic possibilities.

Perceived control of nutrition behavior: a study of the locus of control theory among healthy subjects.

This study was conducted to gain insight into individuals' perceptions of their willingness and ability to change their nutrition behavior. As eating habits are primarily socially learned, the locus of control theory, a social learning theory, was applied to the understanding of nutrition behavior. Responses from 105 young male and female subjects to a questionnaire devised to examine individuals' beliefs about the internal and external factors which control, or determine, dietary habits and health were analyzed. Individual values and assessment of personal health and diet were measured, and demographic data were collected. Two major findings were obtained. First, the locus of control theory was too narrow a construct to explain the subjects' responses and beliefs. The data suggested six categories which differentiated between individuals' expectations about factors controlling outcomes of behavior and those controlling actual personal behaviors. Second, there were significant differences in responses to locus of control statements on the basis of certain demographic variables, especially religious affiliation. Religious/traditional Jewish subjects tended to be more internally oriented than nonreligious/nontraditional Jewish subjects, independent of other demographic variables. Subjects with greater willingness and perceived ability to change their nutrition behavior appeared to take responsibility for choosing what is "right" or "better" and had firmly established personal guidelines for what is, or is not, acceptable.