220 research outputs found
Intrinsic symmetry groups of links with 8 and fewer crossings
We present an elementary derivation of the "intrinsic" symmetry groups for
knots and links of 8 or fewer crossings. The standard symmetry group for a link
is the mapping class group \MCG(S^3,L) or \Sym(L) of the pair .
Elements in this symmetry group can (and often do) fix the link and act
nontrivially only on its complement. We ignore such elements and focus on the
"intrinsic" symmetry group of a link, defined to be the image of
the natural homomorphism \MCG(S^3,L) \rightarrow \MCG(S^3) \cross \MCG(L).
This different symmetry group, first defined by Whitten in 1969, records
directly whether is isotopic to a link obtained from by permuting
components or reversing orientations.
For hyperbolic links both \Sym(L) and can be obtained using the
output of \texttt{SnapPea}, but this proof does not give any hints about how to
actually construct isotopies realizing . We show that standard
invariants are enough to rule out all the isotopies outside for all
links except , and where an additional construction
is needed to use the Jones polynomial to rule out "component exchange"
symmetries. On the other hand, we present explicit isotopies starting with the
positions in Cerf's table of oriented links which generate for each
link in our table. Our approach gives a constructive proof of the
groups.Comment: 72 pages, 66 figures. This version expands the original introduction
into three sections; other minor changes made for improved readabilit
Parkinsonism caused by adverse drug reactions: a case series
<p>Abstract</p> <p>Introduction</p> <p>Parkinsonism puts a high direct cost burden on both patient and caregiver. Several reports of drug-induced parkinsonism have been published, but to the best of our knowledge, there has not been any report of quinine or halothane inducing parkinsonism.</p> <p>Case presentation</p> <p>We describe two cases of parkinsonism possibly caused by adverse drug reaction to quinine in a 29-year-old black Nigerian woman and to halothane in a 36-year-old black Hausa (Nigerian) man who received it as general anaesthesia for appendicectomy in our teaching hospital.</p> <p>Conclusion</p> <p>These are two unusual cases of parkinsonism caused by adverse drug reactions to high-dose quinine and to halothane as general anaesthesia. We consider that these two cases are important in bringing this potential side-effect to the attention of both pharmacologists and primary care physicians as these are two of the most commonly used medications in our clinics. We conclude that parkinsonism should be included among the adverse drug reactions to high-dose quinine and halothane general anaesthetic.</p
Повышение эффективности проведения геолого-технических мероприятий на месторождениях Западной Сибири
Цель работы - анализ проведенных геолого-технических мероприятий, предложение нового инновационного подхода к повышению эффективности проведения ГТМ на месторождениях Западной-Сибири. В процессе исследования проводился анализ имеющихся данных, на основе которых были выделение наиболее эффективные геолого-технические мероприятия, проводимые на месторождениях Западной Сибири.The purpose of the work is to analyze the geological and technical measures carried out, to propose a new innovative approach to improving the efficiency of GTM in the fields of Western Siberia.
In the course of the study, the available data were analyzed, on the basis of which the most effective geological and technical measures carried out in the fields of Western Siberia were identified
Homicide and geographic access to gun dealers in the United States
<p>Abstract</p> <p>Background</p> <p>Firearms are the most commonly used weapon to commit homicide in the U.S. Virtually all firearms enter the public marketplace through a federal firearms licensee (FFL): a store or individual licensed by the federal government to sell firearms. Whether FFLs contribute to gun-related homicide in areas where they are located, in which case FFLs may be a homicide risk factor that can be modified, is not known.</p> <p>Methods</p> <p>Annual county-level data (1993–1999) on gun homicide rates and rates of FFLs per capita were analyzed using negative binomial regression controlling for socio-demographic characteristics. Models were run to evaluate whether the relation between rates of FFLs and rates of gun homicide varied over the study period and across counties according to their level of urbanism (defined by four groupings, as below). Also, rates of FFLs were compared against FS/S – which is the proportion of suicides committed by firearm and is thought to be a good proxy for firearm availability in a region – to help evaluate how well the FFL variable is serving as a way to proxy firearm availability in each of the county types of interest.</p> <p>Results</p> <p>In major cities, gun homicide rates were higher where FFLs were more prevalent (rate ratio [RR] = 1.70, 95% CI 1.03–2.81). This association increased (p < 0.01) from 1993 (RR = 1.69) to 1999 (RR = 12.72), due likely to federal reforms that eliminated low-volume dealers, making FFL prevalence a more accurate exposure measure over time. No association was found in small towns. In other cities and in suburbs, gun homicide rates were significantly lower where FFLs were more prevalent, with associations that did not change over the years of the study period. FFL prevalence was correlated strongly (positively) with FS/S in major cities only, suggesting that the findings for how FFL prevalence relates to gun homicide may be valid for the findings pertaining to major cities but not to counties of other types.</p> <p>Conclusion</p> <p>Modification of FFLs through federal, state, and local regulation may be a feasible intervention to reduce gun homicide in major cities.</p
Comparative effectiveness of lifestyle interventions on cardiovascular risk factors among a Dutch overweight working population: A randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>Overweight (Body Mass Index [BMI] ≥ 25 kg/m<sup>2</sup>) and obesity (BMI≥ 30 kg/m<sup>2</sup>) are associated with increased cardiovascular risk, posing a considerable burden to public health. The main aim of this study was to investigate lifestyle intervention effects on cardiovascular risk factors in healthy overweight employees.</p> <p>Methods</p> <p>Participants were 276 healthy overweight employees (69.2% male; mean age 44.0 years [SD 9.2]; mean BMI 29.7 kg/m<sup>2 </sup>[SD 3.1]). They were randomized to one of two intervention groups receiving a six month lifestyle intervention with behavior counseling by phone (phone group) or e-mail (Internet group), or to a control group receiving usual care. Body weight, height, waist circumference, sum of skinfolds, blood pressure, total cholesterol level and predicted aerobic fitness were measured at baseline, at 6 and at 24 months. Regression analyses included the 141 participants with complete data.</p> <p>Results</p> <p>At 6 months a significant favorable effect on total cholesterol level (-0.2 mmol/l, 95%CI -0.5 to -0.0) was observed in the phone group and a trend for improved aerobic fitness (1.9 ml/kg/min, 95%CI -0.2 to 3.9) in the Internet group. At two years, favorable trends for body weight (-2.1 kg, 95%CI -4.4 to 0.2) and aerobic fitness (2.3 ml/kg/min, 95%CI -0.2 to 4.8) were observed in the Internet group.</p> <p>Conclusions</p> <p>The intervention effects were independent of the used communication mode. However short-term results were in favor of the phone group and long-term results in favor of the internet group. Thus, we found limited evidence for our lifestyle intervention to be effective in reducing cardiovascular risk in a group of apparently healthy overweight workers.</p> <p>Trial registration</p> <p><a href="http://www.controlled-trials.com/ISRCTN04265725">ISRCTN04265725</a></p
Exploring the relationships between housing, neighbourhoods and mental wellbeing for residents of deprived areas
<p><b>Background:</b> Housing-led regeneration has been shown to have limited effects on mental health. Considering housing and neighbourhoods as a psychosocial environment, regeneration may have greater impact on positive mental wellbeing than mental ill-health. This study examined the relationship between the positive mental wellbeing of residents living in deprived areas and their perceptions of their housing and neighbourhoods.</p>
<p><b>Methods:</b> A cross-sectional study of 3,911 residents in 15 deprived areas in Glasgow, Scotland. Positive mental wellbeing was measured using the Warwick-Edinburgh Mental Wellbeing Scale.</p>
<p><b>Results:</b> Using multivariate mulit-nomial logistic regressions and controlling for socio-demographic characteristics and physical health status, we found that several aspects of people's residential psychosocial environments were strongly associated with higher mental wellbeing. Mental wellbeing was higher when respondents considered the following: their neighbourhood had very good aesthetic qualities (RRR 3.3, 95% CI 1.9, 5.8); their home and neighbourhood represented personal progress (RRR 3.2 95% CI 2.2, 4.8; RRR 2.6, 95% CI 1.8, 3.7, respectively); their home had a very good external appearance (RRR 2.6, 95% CI 1.3, 5.1) and a very good front door (both an aesthetic and a security/control item) (RRR 2.1, 95% CI 1.2, 3.8); and when satisfaction with their landlord was very high (RRR 2.3, 95% CI 2.2,4.8). Perception of poor neighbourhood aesthetic quality was associated with lower wellbeing (RRR 0.4, 95% CI 0.3, 0.5).</p>
<p><b>Conclusions:</b> This study has shown that for people living in deprived areas, the quality and aesthetics of housing and neighbourhoods are associated with mental wellbeing, but so too are feelings of respect, status and progress that may be derived from how places are created, serviced and talked about by those who live there. The implication for regeneration activities undertaken to improve housing and neighbourhoods is that it is not just the delivery of improved housing that is important for mental wellbeing, but also the quality and manner of delivery.</p>
Phenotypic and Functional Characterization of Human Memory T Cell Responses to Burkholderia pseudomallei
The Gram-negative bacterium, Burkholderia pseudomallei, is a public health problem in southeast Asia and northern Australia and a Centers for Disease Control and Prevention listed Category B potential bioterrorism agent. It is the causative agent of melioidosis, and clinical manifestations vary from acute sepsis to chronic localized and latent infection, which can reactivate decades later. B. pseudomallei is the major cause of community-acquired pneumonia and septicemia in northeast Thailand. In spite of the medical importance of B. pseudomallei, little is known about the mechanisms of pathogenicity and the immunological pathways of host defense. There is no available vaccine, and the mortality rate in acute cases can exceed 40% with 10–15% of survivors relapsing or being reinfected despite prolonged and complete treatments. In this article, we describe cell-mediated immune responses to B. pseudomallei in humans living in northeast Thailand and demonstrate clear evidence of T cell priming in healthy seropositive individuals and patients who recovered from melioidosis. This is the most detailed study yet performed on the cell types that produce interferon-gamma to B. pseudomallei in humans and the antigens that they recognize and the first to study large sample numbers in the primary endemic focus of melioidosis in the world
Topical Polyethylene Glycol as a Novel Chemopreventive Agent for Oral Cancer via Targeting of Epidermal Growth Factor Response
Head and neck squamous cell carcinoma (HNSCC) is a major cause of morbidity and mortality underscoring the need for safe and effective chemopreventive strategies. Targeting epidermal growth factor receptor (EGFR) is attractive in that it is an early critical event in HNSCC pathogenesis. However, current agents lack efficacy or have unacceptable toxicity. Several groups have demonstrated that the over-the-counter medication, polyethylene glycol (PEG) has remarkable chemopreventive efficacy against colon carcinogenesis. Importantly, we reported that this effect is mediated through EGFR internalization/degradation. In the current study, we investigated the chemopreventive efficacy of this agent against HNSCC, using both the well validated animal model 4-NQO (4-nitroquinoline 1-oxide) rat model and cell culture with the human HNSCC cell line SCC-25. We demonstrated that daily topical application of 10% PEG-8000 in the oral cavity (tongue and cavity wall) post 4NQO initiation resulted in a significant reduction in tumor burden (both, tumor size and tumors/tumor bearing rat) without any evidence of toxicity. Immunohistochemical studies depicted decreased proliferation (number of Ki67-positive cells) and reduced expression of EGFR and its downstream effectors cyclin D1 in the tongue mucosa of 4NQO-rats treated with PEG. We showed that EGFR was also markedly downregulated in SCC-25 cells by PEG-8000 with a concomitant induction of G1-S phase cell-cycle arrest, which was potentially mediated through upregulated p21cip1/waf1. In conclusion, we demonstrate, for the first time, that PEG has promising efficacy and safety as a chemopreventive efficacy against oral carcinogenesis
In vivo expression of innate immunity markers in patients with mycobacterium tuberculosis infection
<p>Abstract</p> <p>Background</p> <p>Toll-like receptors (TLRs), Coronin-1 and Sp110 are essential factors for the containment of <it>Mycobacterium tuberculosis </it>infection. The purpose of this study was to investigate the <it>in vivo </it>expression of these molecules at different stages of the infection and uncover possible relationships between these markers and the state of the disease.</p> <p>Methods</p> <p>Twenty-two patients with active tuberculosis, 15 close contacts of subjects with latent disease, 17 close contacts of subjects negative for mycobacterium antigens and 10 healthy, unrelated to patients, subjects were studied. Quantitative mRNA expression of Coronin-1, Sp110, TLRs-1,-2,-4 and -6 was analysed in total blood cells <it>vs </it>an endogenous house-keeping gene.</p> <p>Results</p> <p>The mRNA expression of Coronin-1, Sp110 and TLR-2 was significantly higher in patients with active tuberculosis and subjects with latent disease compared to the uninfected ones. Positive linear correlation for the expression of those factors was only found in the infected populations.</p> <p>Conclusions</p> <p>Our results suggest that the up-regulation of Coronin-1 and Sp110, through a pathway that also includes TLR-2 up-regulation may be involved in the process of tuberculous infection in humans. However, further studies are needed, in order to elucidate whether the selective upregulation of these factors in the infected patients could serve as a specific molecular marker of tuberculosis.</p
Mutation analysis of SDHB and SDHC: novel germline mutations in sporadic head and neck paraganglioma and familial paraganglioma and/or pheochromocytoma
BACKGROUND: Germline mutations of the SDHD, SDHB and SDHC genes, encoding three of the four subunits of succinate dehydrogenase, are a major cause of hereditary paraganglioma and pheochromocytoma, and demonstrate that these genes are classic tumor suppressors. Succinate dehydrogenase is a heterotetrameric protein complex and a component of both the Krebs cycle and the mitochondrial respiratory chain (succinate:ubiquinone oxidoreductase or complex II). METHODS: Using conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing to analyse genomic DNA from peripheral blood lymphocytes, here we describe the mutation analysis of the SDHB and SDHC genes in 37 patients with sporadic (i.e. no known family history) head and neck paraganglioma and five pheochromocytoma and/or paraganglioma families. RESULTS: Two sporadic patients were found to have a SDHB splice site mutation in intron 4, c.423+1G>A, which produces a mis-spliced transcript with a 54 nucleotide deletion, resulting in an 18 amino acid in-frame deletion. A third patient was found to carry the c.214C>T (p.Arg72Cys) missense mutation in exon 4 of SDHC, which is situated in a highly conserved protein motif that constitutes the quinone-binding site of the succinate: ubiquinone oxidoreductase (SQR) complex in E. coli. Together with our previous results, we found 27 germline mutations of SDH genes in 95 cases (28%) of sporadic head and neck paraganglioma. In addition all index patients of five families showing hereditary pheochromocytoma-paraganglioma were found to carry germline mutations of SDHB: four of which were novel, c.343C>T (p.Arg115X), c.141G>A (p.Trp47X), c.281G>A (p.Arg94Lys), and c.653G>C (p.Trp218Ser), and one reported previously, c.136C>T, p.Arg46X. CONCLUSION: In conclusion, these data indicate that germline mutations of SDHB and SDHC play a minor role in sporadic head and neck paraganglioma and further underline the importance of germline SDHB mutations in cases of familial pheochromocytoma-paraganglioma
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