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Yttrium iron garnet has a very high Verdet constant, is transparent in the infrared and is an insulating ferrimagnet leading to its use in optical and magneto-optical applications. Its high Q-factor has been exploited to make resonators and filters in microwave devices, but it also has the lowest magnetic damping of any known material. In this article we describe the structural and magnetic properties of single crystal thin-film YIG where the temperature dependence of the magnetisation reveals a decrease in the low temperature region. In order to understand this complex material we bring a large number of structural and magnetic techniques to bear on the same samples. Through a comprehensive analysis we show that at the substrate -YIG interface, an interdiffusion zone of only 4-6 nm exists. Due to the interdiffusion of Y from the YIG and Gd from the substrate, an addition magnetic layer is formed at the interface whose properties are crucially important in samples with a thickness of YIG less than 200 nm.

The theoretical impacts of anthropogenic habitat degradation on genetic resources have been well articulated. Here we use a simulation approach to assess the magnitude of expected genetic change, and review 31 studies of 23 neotropical tree species to assess whether empirical case studies conform to theory. Major differences in the sensitivity of measures to detect the genetic health of degraded populations were obvious. Most studies employing genetic diversity (nine out of 13) found no significant consequences, yet most that assessed progeny inbreeding (six out of eight), reproductive output (seven out of 10) and fitness (all six) highlighted significant impacts. These observations are in line with theory, where inbreeding is observed immediately following impact, but genetic diversity is lost slowly over subsequent generations, which for trees may take decades. Studies also highlight the ecological, not just genetic, consequences of habitat degradation that can cause reduced seed set and progeny fitness. Unexpectedly, two studies examining pollen flow using paternity analysis highlight an extensive network of gene flow at smaller spatial scales (less than 10 km). Gene flow can thus mitigate against loss of genetic diversity and assist in long-term population viability, even in degraded landscapes. Unfortunately, the surveyed studies were too few and heterogeneous to examine concepts of population size thresholds and genetic resilience in relation to life history. Future suggested research priorities include undertaking integrated studies on a range of species in the same landscapes; better documentation of the extent and duration of impact; and most importantly, combining neutral marker, pollination dynamics, ecological consequences, and progeny fitness assessment within single studies.

Despite the typically low population densities and animal-mediated pollination of tropical forest trees, outcrossing and long-distance pollen dispersal are the norm. We reviewed the genetic literature on mating systems and pollen dispersal for neotropical trees to identify the ecological and phylogenetic correlates. The 36 studies surveyed found >90% outcrossed mating for 45 hermaphroditic or monoecious species. Self-fertilization rates varied inversely with population density and showed phylogenetic and geographic trends. The few direct measures of pollen flow (N=11 studies) suggest that pollen dispersal is widespread among low-density tropical trees, ranging from a mean of 200 m to over 19 km for species pollinated by small insects or bats. Future research needs to examine (1) the effect of inbreeding depression on observed outcrossing rates, (2) pollen dispersal in a wide range of pollination syndromes and ecological classes, (3) and the range of variation of mating system expression at different hierarchical levels, including individual, seasonal, population, ecological, landscape and range wide.

Recent studies have reported enhanced prostate cancer detection in Caucasians with serum human glandular kallikrein 2 (hK2) in combination with total- (tPSA) and free-prostate-specific antigen (fPSA). The purpose of this study is to validate these findings in an African-American patient cohort. A total of 137 African-American men were found by routine screening to have tPSA levels above 2.5 ng/ml or an abnormal digital rectal examination. Sera were drawn prior to biopsy of the prostate and Hybritech PSA, FPSA and hK2 (for research use only, not for use in diagnostic procedures) concentrations were determined on Beckman Coulter's Access immunoanalyzer. These independent variables and the ratios of percent fPSA (%fPSA), hK2/tPSA, hK2/fPSA, and hK2*tPSA/fPSA were compared between cancer and non-cancer groups. In all, 49 of 137 men had prostate cancer. hK2 and its calculated ratios outperformed tPSA on receiver operator characteristic (ROC) analysis, but %fPSA had statistically the highest area under the curve (AUC) at 0.801. When restricting the analysis to only the tPSA range of 4.0-10 ng/ml, hK2/fPSA yielded the highest AUC (0.721). The ratio of hK2/fPSA was also found to increase the positive predictive value (PPV) of the %fPSA ranges less than 10 and 10-25%. %fPSA offered the best performance and highest specificity in prostate cancer detection in African-American males over the entire range of tPSA. hK2/fPSA may offer modest improvement in the tPSA range of 4.0-10 ng/ml. Furthermore, hK2/fPSA can enhance the PPV of low %fPSA values. Therefore, the use of multiple biomarkers may ultimately increase the specificity of prostate cancer screening in African-American men.

In all, 22 African-American males undergoing radical prostatectomy for prostate adenocarcinoma had serum drawn for tPSA, cPSA, and total protein concentrations prior to, during, and after operation to determine the respective elimination rates. African-American cPSA was found to fit best a simple first-order exponential elimination kinetic, with a half-life of 44.6 h. fPSA followed a two-compartment elimination with an alpha-phase elimination of 0.50 h and a beta-phase half-life of 4.2 h. Our results suggest higher rates of elimination for both cPSA and fPSA in an African-American male population with respect to Caucasians and may account for differences in PSA values between races.

Purpose: The principal objective was to test the hypothesis that HIV-positive patients have significantly reduced amplitudes of accommodation compared with controls. The secondary objective was to investigate accommodative impairment in relation to factors such as age of susceptibility, CD4 count, viral load and current antiretroviral therapies., Method: The study was a single-center open prospective study involving a subject population of 43 HIV-positive men aged from 26 to 39 years with no previous history of eye problems and 21 age-matched healthy male controls. The main outcome measure was the amplitude of accommodation, as measured monocularly with a standard push-up technique., Results: Amplitudes of accommodation were significantly smaller in the HIV-positive group compared with controls for age groups 25-29 (p = 0.016) and 30-34 years (p = 0.030) but not in the older group. In total, 30% (8/27) of patients aged between 25 and 34 years had reduced amplitudes of accommodation below age-expected norms. Accommodative failure was not related to current or lowest CD4 count, viral load or specific antiretroviral therapies., Conclusion: This study has identified accommodative failure in a significant proportion of HIV-positive patients aged between 26 and 35 years. This problem may be under-recognised, and further studies are warranted to investigate possible causes.

We have performed a pilot study of MDR-1 gene transfer in patients receiving CD34-selected peripheral blood stem cell (PBSC) transplant for lymphoma. To ensure minimum engraftment thresholds and facilitate CD34 purification, mobilisation of > 2 x 10(6) CD34 cells/kg was a condition for recruitment. Of 11 patients counselled for study entry, only five achieved this target in a single apheresis. In three consenting patients, purified CD34 cells were exposed to A12M1 MDR-1 retroviral supernatant for 6 h, cryopreserved then thawed and readministered following ablative chemotherapy. No delay in engraftment was observed, although one patient received additional back-up cells. Gene transfer was demonstrated by polymerase chain reaction (PCR) for vector-derived MDR-1 cDNA sequence in all cases. Analysis of peripheral blood and bone marrow cells after transplant has, however, shown no evidence of in vivo gene transfer with a follow-up of 12, 15 and 18 months. The effect of MDR-1 substrate drugs has not yet been tested as all patients remain in clinical and radiological remission of their lymphoma. These results confirm the difficulty of achieving in vivo gene transfer in human haemopoietic cells and indicate major logistical constraints in PBSC mobilisation in patients with relapsed and resistant disease in whom initial studies are appropriate.

L-myc is a nuclear oncogene which is sometimes activated late in tumourigenesis. Digestion of DNA with EcoRI reveals a simple restriction fragment length polymorphism (RFLP) located in the second intron of L-myc, with allele sizes 10 kb (L-allele) and 6.6 kb (S-allele). Some studies have suggested that the presence of the S-allele in the constitutional DNA of a patient with cancer is associated with a higher risk of metastasis in lung, breast and renal cell carcinomas. The aims of this study were to determine if the S-allele was significantly associated with metastasis and also with inactivation of tumour suppressor genes in colorectal cancer. One hundred and twenty-four Caucasian colorectal cancer patients were studied for L-myc genotype, and a subgroup of these (108) had their tumours examined for allele loss at multiple loci on nine chromosomal arms (1p, 1q, 5q, 8p, 14q, 17p, 17q, 18q, 22q) and for mutations in the 12th codon of K-ras. The percentage of individuals with the SS genotype was 19% (4/21) Dukes Stage A, 19% (10/54) Dukes B, 25% (8/32) Dukes C and 40% (8/20) Dukes D. The trend observed here is significant (P < 0.05, Wilcoxon Rank Sum Test). Also, the SS genotype was significantly more common in individuals whose tumours showed allelic loss on 18q (P < 0.01, Fishers Exact Test). This work suggests that the S-allele of L-myc, or a gene in linkage disequilibrium with it, may modify the development of colorectal cancer.

The current model for colorectal tumorigenesis defines four specific mutations (activation of a ras proto-oncogene and inactivation of the APC, p53 and DCC tumor-suppressor genes) that accumulate in a colonic epithelial cell as it progresses towards a carcinoma. However, further mutations must be needed for progression to malignancy because advanced adenomas have been observed with all four of these mutations. Loss of heterozygosity (LOH) for 11 loci spanning the distal portion of the long arm of chromosome 14 was studied in 89 sporadic colorectal adenocarcinomas and 25 adenomas. The overall rate of LOH in carcinomas was 53% (46/86 informative carcinomas). The smallest region of overlap (SRO) of deletions includes the markers D14S19 to D14S20. No LOH was seen in the 18 informative adenomas examined. There was a significant trend towards higher levels of LOH within the SRO in advanced Dukes' stages (P = 0.016). Since frequent loss of heterozygosity in a specific region of a chromosome may reflect the inactivation of a tumor-suppressor gene located there, these data suggest that a gene involved in the progression of colonic neoplasia may reside on the distal portion of the long arm of chromosome 14, and that its inactivation may be a critical event in this process.