Are silica defences in grasses driving vole population cycles?

Understanding the factors that drive species population dynamics is fundamental to biology. Cyclic populations of microtine rodents have been the most intensively studied to date, yet there remains great uncertainty over the mechanisms determining the dynamics of most of these populations. For one such population, we present preliminary evidence for a novel mechanism by which herbivore-induced reductions in plant quality alter herbivore life-history parameters and subsequent population growth. We tested the effect of high silica levels on the population growth and individual performance of voles (Microtus agrestis) reared on their winter food plant (Deschampsia caespitosa). In sites where the vole population density was high, silica levels in D. caespitosa leaves collected several months later were also high and vole populations subsequently declined; in sites where the vole densities were low, levels of silica were low and population density increased. High silica levels in their food reduced vole body mass by 0.5% a day. We argue that silica-based defences in grasses may play a key role in driving vole population cycles.

Low educational level: a risk factor for sexually transmitted infections among commercial sex workers in Quito, Ecuador

Few studies have assessed the effect of educational level on sexually transmitted infections (STIs) and risk-taking behaviours among commercial sex workers (CSWs). This study analysed this association among female CSWs in Quito, Ecuador. Eighty-five CSWs were given a Spanish-language questionnaire on behaviours, socioeconomics and demographics. The correlation between years of education and number of prior STIs was calculated. Three groups of varying education level were formed and risk factors were analysed by Chi-square tests and analysis of variances. Lower educational level was associated with more STIs (r= -0.36; F=4.2; P=0.04), poorer knowledge of HIV/AIDS (P=0.03), earlier first prostitution (P=0.05) and first sex (P=0.00), willingness to engage in group sex (P=0.05) and work on the street (P=0.02), and presence of non-paying sexual partners (P=0.05). CSWs with lower educational levels were disproportionately afflicted with STIs and participated in more high-risk behaviours. Low educational level may predispose CSWs to STIs and associated risk factors.

Alterations in the SMARCB1 (INI1) tumor suppressor gene in familial schwannomatosis

Schwannomatosis is a third major form of neurofibromatosis that has recently been linked to mutations in the SMARCB1 (hSnf5/INI1) tumor suppressor gene. We analyzed the coding region of SMARCB1 by direct sequencing and multiplex ligation-dependent probe amplification (MLPA) in genomic DNA from 19 schwannomatosis kindreds. Microsatellite markers in the SMARCB1 region were developed to determine loss of heterozygosity (LOH) in associated tumors. We detected four alterations in conserved splice acceptor or donor sequences of exons 3, 4 and 6. Two alterations that likely affect splicing were seen in introns 4 and 5. An additional four alterations of unclear pathogenicity were found to segregate on the affected allele in eight families including two non-conservative missense alterations in three families. No constitutional deletions or duplications were detected by MLPA. Nine of 13 tumors examined showed partial LOH of the SMARCB1 region consistent with 'second hits.' Alterations were detected in tumors both with and without somatic NF2 gene changes. These findings support the hypothesis that SMARCB1 is a tumor suppressor for schwannomas in the context of familial disease. Further work is needed to determine its role in other multiple and single tumor syndromes.

Factors affecting river health and its assessment over broad geographic ranges: the Western Australian experience

AusRivAS is an Australia-wide program that measures river condition using predictive models to compare the macroinvertebrate families occurring at a river site with those expected if the site were in natural condition. Results of assessment of 685 sites across all major rivers in Western Australia are presented. Most rivers were in relatively natural condition in the northern half of the state where the human population is low and pastoralism is the major land use. In the south, where the human population is higher and agriculture is more intensive, rivers were mostly more disturbed. AusRivAS assessment produced some erroneous results in rivers of the south-west cropping zone because of the lack of appropriate reference site groups and biased distribution of sampling sites. Collecting low numbers of animals from many forested streams, because of low stream productivity and samples that were difficult to sort, also affected assessments. Overall, however, AusRivAs assessment identified catchment processes that were inimical to river health. These processes included salinisation, high nutrient and organic loads, erosion and loss of riparian vegetation. River regulation, channel modification and fire were also associated with river degradation. As is the case with other assessment methods, one-off sampling at individual sites using AusRivAS may be misleading. Seasonal drought, in particular, may make it difficult to relate conditions at the time of sampling to longer-term river health. AusRivAS has shown river condition in Western Australia is not markedly different from other parts of Australia which, as a whole, lacks the substantial segments of severely degraded river systems reported in England.

The Australian Vascular Quality of Life Index (AUSVIQUOL): An Improved Clinical Quality of Life Tool for Peripheral Vascular Disease

OBJECTIVES

To validate the Australian Vascular Quality of Life Index (AUSVIQUOL) as a quality of life (QOL) tool appropriate for peripheral vascular disease patients in the clinical setting.

DESIGN

Cross-sectional study.

MATERIALS

The study group consisted of 71 patients with vascular claudication of varying severity attending a tertiary hospital outpatient department.

METHODS

The results of the AUSVIQUOL and Medical Outcomes Short Form Health Survey (SF-36) were compared through factor and regression analyses. A group of 12 patients was then reassessed to compare the reliability and internal consistency of the two indices.

RESULTS

The AUSVIQUOL took less time to complete than the SF-36 (3.27 v 10.79 min; p<0.0001) and fewer patients found the questions confusing (2% v 26%). The AUSVIQUOL was easier to administer and had a higher level of patient acceptance than the SF-36. The regression analysis showed that for each of the domains in the AUSVIQUOL there was a significant correlation with measures in the SF-36 (adjusted R-squared 0.420, 0.480 and 0.331). The AUSVIQUOL demonstrated a good level of internal consistency when compared to the SF-36 (Cronbach's alpha 0.8702 vs 0.6307).

CONCLUSION

In comparison with the SF-36, the AUSVIQUOL is an improved tool for the QOL assessment of patients with peripheral vascular disease in the clinical setting.

Salmonella typhimurium stimulation combined with tumour-derived heat shock proteins induces potent dendritic cell anti-tumour responses in a murine model

Appropriate activation of the immune system and effective targeting of tumour cells are the primary hurdles to be overcome for cancer immunotherapy to be successful and applicable to a wide range of tumour types. Our studies have examined the ability of bacterial-stimulated dendritic cells (DCs), loaded with tumour-associated antigens, to inhibit tumour growth in a murine model. Immature murine bone marrow-derived DCs were stimulated in vitro with the cytoplasmic fraction (CM) of Salmonella typhimurium in combination with heat shock proteins (hsps) from 4T1 tumours, isolated using heparin affinity chromatography. Activated DCs were administered subcutaneously. Tumours were generated by orthotopic inoculation of 4T1 cells in Balb/c mice. Primary tumour growth was measured using Vernier calipers, while lung metastases were measured using the clonogenic assay. S. typhimurium CM induced potent tumour necrosis factor (TNF)-alpha responses from DCs accompanied by significant up-regulation of CD80 and CD86 expression. When injected into mice, bacterial-stimulated DCs loaded with 4T1 hsps inhibited the formation of new 4T1 tumours and reduced the growth rate of established tumours. In addition, the number of lung metastatic nodules was reduced significantly in the DC-treated mice (1.6 +/- 0.6 versus 245.9 +/- 55.6, P = 0.0015). DCs stimulated with CM alone, exposed to tumour hsps alone or exposed to tumour hsps from an unrelated tumour cell line did not induce a protective immune response. Dendritic cells primed with a proinflammatory bacterial stimulus and tumour-associated antigens induce a protective anti-tumour immune response in this murine model.

Sentinel lymph node biopsy in elderly irish patients with malignant melanoma

In patients with malignant melanoma, Breslow depth increases with age. However, studies suggest that the frequency of sentinel lymph node metastases in malignant melanoma decreases with age. We investigated whether this applied to the cohort of patients undergoing sentinel lymph node biopsy (SLNB) in our institution. In a prospectively accrued database we identified 149 patients undergoing SLNB from 1997 to 2005. Tumour thickness as measured by Breslow depth was assessed in stratified age groups. We assessed the relationship between SLNB positivity and age using the Chi-square for trend. We directly examined the relationship between SLNB positivity in patients aged less than 65 and aged 65 years of age and over. Disease-free and overall survival in patients aged less than 65 and aged 65 years of age and over were also assessed. Comparing the age groups, there was no significant difference identified in Breslow depth (<65 years, median Breslow > or = 1.2 mm (range 0.2-9.7); > or =65 years, median Breslow > or = 1.4 mm (range 0.12-8.5); p > or = 0.06, Mann-Whitney U). Chi-square for trend identified no significant relationship between SLNB positivity and age. We found n=120 patients <65 had SLNB, of which 26 (21.7%) were positive. In patients =65, n=29 had SLNB of which 3 (10.3%) were positive. These differences were not statistically significant (Fisher's exact test, p > or = 0.2). There was no difference in disease-free or overall survival between patients aged <65 or > or =65 who had SLNB (median follow-up 37.5 months (range 5-70); disease-free survival, p > 0.08; overall survival, p > or = 0.3, Logrank test). We did not find that elderly patients with malignant melanoma had a demonstrable difference in tumour thickness when compared to younger patients. In those patients who underwent SLNB there was no significant difference in node positivity between the age groups. Disease-free and overall survival were not significantly different between the age groups. Further study and longer follow-up will help establish the relationship between age and SLNB positivity.

Quantifying the magnetic advantage in magnetotaxis

Magnetotactic bacteria are characterized by the production of magnetosomes, nanoscale particles of lipid bilayer encapsulated magnetite, that act to orient the bacteria in magnetic fields. These magnetosomes allow magneto-aerotaxis, which is the motion of the bacteria along a magnetic field and toward preferred concentrations of oxygen. Magneto-aerotaxis has been shown to direct the motion of these bacteria downward toward sediments and microaerobic environments favorable for growth. Herein, we compare the magneto-aerotaxis of wild-type, magnetic Magnetospirillum magneticum AMB-1 with a nonmagnetic mutant we have engineered. Using an applied magnetic field and an advancing oxygen gradient, we have quantified the magnetic advantage in magneto-aerotaxis as a more rapid migration to preferred oxygen levels. Magnetic, wild-type cells swimming in an applied magnetic field more quickly migrate away from the advancing oxygen than either wild-type cells in a zero field or the nonmagnetic cells in any field. We find that the responses of the magnetic and mutant strains are well described by a relatively simple analytical model, an analysis of which indicates that the key benefit of magnetotaxis is an enhancement of a bacterium's ability to detect oxygen, not an increase in its average speed moving away from high oxygen concentrations.

Effects of polycyclic aromatic hydrocarbons on germination and subsequent growth of grasses and legumes in freshly contaminated soil and soil with aged PAHs residues

The relevance of germination trials for screening plants that may have potential for use in the phytoremediation of PAH contaminated land was evaluated. The germination and subsequent growth of 7 grass and legume species were evaluated in soil spiked with a pure PAH mixture or coal tar and soil from a former coking plant heavily contaminated with aged PAHs. None of these treatments adversely affected germination of the plants. However, apart from Lolium perenne all species exhibited reduced growth in the coking plant soil after 12 weeks growth when compared to the untreated soil. In the coal tar spiked soil 4 out of the 7 species showed reduced growth, as did 3 out of the 7 in the soil spiked with a mixture of 7 PAHs. Therefore, germination studies alone would not predict the success of subsequent growth of the species tested in the ranges of soil PAH levels studied.

A heretofore undisclosed crux of eosinophilia-myalgia syndrome: compromised histamine degradation

In contrast to early epidemiological evidence offering links between eosinophilia-myalgia syndrome (EMS) and microimpurities of L-tryptophan-containing dietary supplements (LTCDS), this account shows why reliance on a finite impurity from one manufacturer is both unnecessary and insufficient to explain the etiology of EMS. Excessive histamine activity has induced blood eosinophilia and myalgia (Greek: mys, muscle + algos, pain). Termination of the multiple actions of histamine is dependent on particular amine oxidases and histamine-N-methyltransferase. Histamine metabolism is rapid when these degradative reactions are operative. The latent effects of incurred histamine can be potentiated and aggravating when these mechanisms are impaired. Overloads of tryptophan supplements cause - among other relevant side-effects - an increased formation of formate and indolyl metabolites, several of which inhibit the degradation of histamine. Moreover, (non-EMS) subjects with hypothalamic-pituitary- adrenal (HPA) axis dysregulation have also manifested greatly increased sensitivities to incurred tryptophan and histamine. A final common pathway for syndromes characterized by eosinophilia with myalgia is now evident.

Surgical delay in the management of dog bite injuries in children, does it increase the risk of infection?

Dog bites are contaminated wounds and convention dictates that any surgical treatment should be performed at the earliest opportunity. This practice, however, may be in direct conflict with NCEPOD guidelines to reduce night time operating. We audited our treatment of dog bite injuries in children over a 5-year period (1998-2002) to determine whether delaying surgery to conform to operating guidelines increased the incidence of infection. A retrospective case note study identified 118 patients admitted to Sheffield Children's Hospital with dog bite injuries. Details of their injury, treatment and outcome were recorded. There were 70 males and 48 females and an average age of 6.6 years (range 1-15 years). The most common type of injury was a single laceration (32%) and the most frequent site of injury was the face (59%). The majority of wounds (68%) were cleaned and dressed before theatre and 89% were closed directly after minimal debridement. All patients received prophylactic antibiotics. Of the 114 patients that required surgery, 57 (50%) were operated on within 12 h of their injury and 57 (50%) after 12 h. There were three cases of infection in the early group (<12 h) and none in the delayed group (>12 h). We suggest that delaying the surgical treatment of dog bites in children to avoid operating at night does not increase the infection rate.

Bicyclic and tricyclic thiophenes as protein tyrosine phosphatase 1B inhibitors

A novel pyridothiophene inhibitor of PTP1B was discovered by rational screening of phosphotyrosine mimics at high micromolar concentrations. The potency of this lead compound has been improved significantly by medicinal chemistry guided by X-ray crystallography and molecular modeling. Excellent consistency has been observed between structure-activity relationships and structural information from PTP1B-inhibitor complexes.

DNA methylation in lysogens of pathogenic Burkholderia spp. requires prophage induction and is restricted to excised phage DNA

Burkholderia mallei-specific phage PhiE125 encodes DNA methyltransferases in both the lysogenic and replication modules within its genome. Characterization of DNA methylation in recombinant systems, specifically in PhiE125 lysogenic strains of B. mallei and Burkholderia thailandensis, revealed that, upon induction, cytosine methylation was targeted specifically to the phage episome but not the phage provirus or the host chromosome.

Evolution of duplicated growth hormone genes in autotetraploid salmonid fishes

A defining character of the piscine family Salmonidae is autotetraploidy resulting from a genome-doubling event some 25-100 million years ago. Initially, duplicated genes may have undergone concerted evolution and tetrasomic inheritance. Homeologous chromosomes eventually diverged and the resulting reduction in recombination and gene conversion between paralogous genes allowed the re-establishment of disomic inheritance. Among extant salmonine fishes (e.g. salmon, trout, char) the growth hormone (GH) gene is generally represented by two functional paralogs, GH1 and GH2. Sequence analyses of salmonid GH genes from species of subfamilies Coregoninae (whitefish, ciscos) and Salmoninae were used to examine the evolutionary history of the duplicated GH genes. Two divergent GH gene paralogs were also identified in Coregoninae, but they were not assignable to the GH1 and GH2 categories. The average sequence divergence between the coregonine GH genes was more than twofold lower than the corresponding divergence between the salmonine GH1 and GH2. Phylogenetic analysis of the coregonine GH paralogs did not resolve their relationship to the salmonine paralogs. These findings suggest that disomic inheritance of two GH genes was established by different mechanisms in these two subfamilies.

Gonadotropin-releasing hormone-stimulated gonadotropin levels in women with premenstrual dysphoria

Despite consistent evidence that premenstrual dysphoria (PMD) is not characterized by abnormalities in basal ovarian hormone secretion, the possibility remains that PMD is associated with an abnormality in the regulation of the hypothalamic-pituitary-ovarian (HPO) axis. We studied HPO axis regulation in 11 women with prospectively confirmed PMD and 20 asymptomatic controls, during both the follicular and luteal phases of the menstrual cycle. Plasma levels of the gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), were obtained before and after stimulation with gonadotropin-releasing hormone (GnRH) (100 microg intravenously). Potential diagnostic- and menstrual cycle phase-related diferences in basal and plasma hormone levels were analyzed by repeated-measures analysis of variance. No significant differences were observed between women with PMD and controls in either basal or stimulated levels of FSH and LH. Stimulated FSH was significantly increased and stimulated LH was significantly decreased during the follicular compared with the luteal phase in both women with PMD and controls. These data are consistent with prior findings of normal basal reproductive hormone levels in women with PMD. Our data suggest the absence in women with PMD of an abnormality of dynamic ovarian function as measured by GnRH stimulation.

The SIS extracellular matrix scaffold-preliminary results of use in congenital diaphragmatic hernia (CDH) repair

There is no ideal bio-tensile material for tissue replacement in paediatric surgical conditions. A variety of materials have been described to replace or reinforce tissue deficits in congenital diaphragmatic hernia (CDH). The problems with these materials range from extensive surgery to body wall deformity and hernia recurrence. The ideal graft would be safe, strong, have the potential to grow and not require replacement, not affect chest wall development or produce deformity, and have minimal risk of recurrence. Surgisis is a biomaterial composed of porcine intestinal submucosa that provides inherent tensile strength as a collagen lattice and is ultimately replaced by native collagen tissue. Our objective was to prospectively assess the utility of Surgisis as a replacement graft in a cohort of 10 children undergoing primary or recurrent CDH repair. The graft was well tolerated, and there was no recurrence of herniation. We conclude that Surgisis collagen mesh may be a useful alternative for tissue replacement or reinforcement in difficult cases of CDH and diaphragmatic agenesis. The biological framework of Surgisis may also prove useful in other situations of complex tissue loss in children.