Genotyping of methicillin-resistant Staphylococcus aureus by assaying for the presence of variable elements associated with mecA

The region surrounding mecA in methicillin-resistant Staphylococcus aureus (MRSA) is highly variable. We describe an approach for the rapid genotyping of MRSA by assaying for the presence or absence of variable or mobile elements previously shown to be associated with the mecA region.

Genetic shifts in Helicoverpa armigera Hubner (Lepidoptera : Noctuidae) over a year in the Dawson/Callide Valleys

Microsatellites were used to analyse 68 collections of Helicoverpa armigera in the Dawson/Callide Valleys in central Queensland. The study aimed to evaluate the genetic structure in this region over a 12-month period (September 2000-August 2001). The results detected genetic shifts in H. armigera collections, with genetic changes occurring month by month. Collections in any month were genetically distant from the preceding month's collections. There was no observed difference between collections of H. armigera from the Biloela region and those found in the Theodore region of central Queensland. The data support the current area-wide management strategies for H. armigera by reinforcing the importance and contribution of local management practices. The study also indicates a need for the continuation of regional or Australia-wide approaches to management of the low levels of immigration that are occurring, and for future high pest pressure years.

Isolation and characterization of microsatellite loci in Bemisia tabaci

Bemisia tabaci (Hemiptera: Aleyrodidae) is a haplo-diploid species with a global distribution demonstrating strong geographical structure with eight recognizable genetic groups. Fifteen microsatellite loci (335 alleles, 6-44 alleles per locus) were derived from four of the eight groups and were then screened across 33 populations. These loci clearly differentiate the populations. The microsatellites amplified best in individuals from genetic groups representing the Mediterranean, Middle East, Asia (three groups) and Australasia/Oceania and amplified less well with populations from sub-Saharan Africa and the New World. This differential amplification pattern is a direct result of the relatedness to the microsatellite source material.

Isolation and characterization of nine microsatellite loci from the Hawaiian grouper Epinephelus quernus (Serranidae) for population genetic analyses

The availability of variable genetic markers for groupers (Serranidae) has generally been limited to mitochondrial DNA. For studies of population genetic structure, more loci are usually required; particularly useful are those that are nuclear in origin such as microsatellites. Here, we isolated and characterized 9 microsatellite loci from the endemic Hawaiian grouper Epinephelus quernus using a biotin-labeled oligonucleotide-streptavidin-coated magnetic bead approach. Of the 20 repeat-containing fragments isolated, 15 had sufficient flanking region in which to design primers. Among these, 9 produced consistent polymerase chain reaction product, and 6 were highly variable. These 6 loci were all composed of dinucleotide repeats, with the number of alleles ranging from 6 to 18, and heterozygosities from 33.3% to 91.7%. The high levels of variability observed should make these markers useful for population genetic studies of E. quernus, and potentially other epinephelines.

Th1 cytokines in oral lichen planus

Background: Cell-mediated immune responses in oral lichen planus (OLP) may be regulated by cytokines and their receptors. Methods: In situ cytokine expression and in vitro cytokine secretion in OLP were determined by immunohistochemistry and ELISA. Resulults: The majority of subepithelial and intraepithelial mononuclear cells in OLP were CD8(+) . In some cases, intraepithelial CD8(+) cells were adjacent to degenerating keratinocytes. CD4(+) cells were observed mainly in the deep lamina propria with occasional CD4(+) cells close to basal keratinocytes. Mononuclear cells expressed IFN-gamma in the superficial lamina propria and TNF-alpha adjacent to basal keratinocytes. Basal keratinocytes expressed TNF-alpha as a continuous band. TNF R1 was expressed by mononuclear cells and basal and suprabasal keratinocytes. There was variable expression of TGF-beta1 in the subepithelial infiltrate while all intraepithelial mononuclear cells were TGF-beta1(-) . Keratinocytes in OLP stained weakly for TGF-beta1. Unstimulated OLP lesional T cells secreted IFN-gammain vitro . TNF-alpha stimulation down-regulated IFN-gamma secretion and up-regulated TNF-alpha secretion. IL-4, IL-10 and TGF-beta1 secretion were not detected. Conclusions: These data suggest the development of a T helper 1 immune response that may promote CD8(+) cytotoxic T-cell activity in OLP.

Short-term autocorrelation in Australian equities

This paper examines the statistical and economic significance of short-term autocorrelation in Australian equities. We document large negative first-order autocorrelation in individual stock returns. Preliminary results suggest this autocorrelation is economically significant, as two simple trading strategies based on the autocorrelation structure appear to yield large risk-adjusted returns. Further analysis, however, shows that these results are driven by the inclusion of small-capitalisation and low-priced stocks which are vulnerable to a number of market-microstructure-related problems. After revising the dataset to mitigate these problems, little evidence of economic significance remains.

Fas ligand and tumour counter-attack in colorectal cancer stratified according to microsatellite instability status

Expression of membrane-bound Fas ligand (FasL) by colorectal cancer cells may allow the development of an immune-privileged site by eliminating incoming tumour-infiltrating lymphocytes (TILs) in a Fas-mediated counter-attack. Sporadic colorectal cancer can be subdivided into three groups based on the level of DNA microsatellite instability (NISI). High-level NISI (NISI-High) is characterized by the presence of TILs and a favourable prognosis, while microsatellite-stable (MSS) cancers are TIL-deficient and low-level MSI (MSI-Low) is associated with an intermediate TIL density. The purpose of this study was to establish the relationship between MSI status and FasL expression in primary colorectal adenocarcinoma. Using immunohistochemistry and a selected series of 101 cancers previously classified as 31 MSI-High, 30 NISI-Low, and 40 MISS, the present study sought to confirm the hypothesis that increased TIL density in MSI-High cancers is associated with low or absent membrane-bound FasL expression, while increased FasL in MSS cancers allows the killing of host TILs. TUNEL/CD3 double staining was also used to determine whether MSS cancers contain higher numbers of apoptotic TILs in vivo than MSI-High or MSI-Low cancers. Contrary to the initial hypothesis, it was found that MSI-High cancers were associated with higher FasL expression (p = 0.04) and a stronger intensity of FasL staining (p = 0.007). In addition, mucinous carcinomas were independently characterized by increased FasL expression (p = 0.03) and staining intensity (p = 0.0005). Higher FasL expression and staining intensity did not correlate with reduced TIL density or increased numbers of apoptotic TILs. However, consistent with the hypothesis that curtailment of the host anti-tumour immune response contributes to the poor prognosis in MSS cancers, it was found that apoptotic TILs were most abundant in MSS carcinomas and metastatic Dukes' stage C or D tumours (p = 0.004; p = 0.046 respectively). This study therefore suggests that MSS colorectal cancers are killing incoming TILs in an effective tumour counter-attack, but apparently not via membrane-bound FasL. Copyright (C) 2003 John Wiley Sons, Ltd.

Distribution of Chlamydia pneumoniae DNA in atherosclerotic carotid arteries: significance for sampling procedures

Despite extensive efforts to confirm a direct association between Chlamydia pneumoniae and atherosclerosis, different laboratories continue to report a large variability in detection rates. In this study, we analyzed multiple sections from atherosclerotic carotid arteries from 10 endartectomy patients to determine the location of C. pneumoniae DNA and the number of sections of the plaque required for analysis to obtain a 95% confidence of detecting the bacterium. A sensitive nested PCR assay detected C. pneumoniae DNA in all patients at one or more locations within the plaque. On average, 42% (ranging from 5 to 91%) of the sections from any single patient had C. pneumoniae DNA present. A patchy distribution of C. pneumoniae in the atherosclerotic lesions was observed, with no area of the carotid having significantly more C. pneumoniae DNA present. If a single random 30-mum-thick section was tested, there was only a 35.6 to 41.6% (95% confidence interval) chance of detecting C. pneumoniae DNA in a patient with carotid artery disease. A minimum of 15 sections would therefore be required to obtain a 95% chance of detecting all true positives. The low concentration and patchy distribution of C. pneumoniae DNA in atherosclerotic plaque appear to be among the reasons for inconsistency between laboratories in the results reported.