522 research outputs found

    Transform-domain analysis of packet delay in network nodes with QoS-aware scheduling

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    In order to differentiate the perceived QoS between traffic classes in heterogeneous packet networks, equipment discriminates incoming packets based on their class, particularly in the way queued packets are scheduled for further transmission. We review a common stochastic modelling framework in which scheduling mechanisms can be evaluated, especially with regard to the resulting per-class delay distribution. For this, a discrete-time single-server queue is considered with two classes of packet arrivals, either delay-sensitive (1) or delay-tolerant (2). The steady-state analysis relies on the use of well-chosen supplementary variables and is mainly done in the transform domain. Secondly, we propose and analyse a new type of scheduling mechanism that allows precise control over the amount of delay differentiation between the classes. The idea is to introduce N reserved places in the queue, intended for future arrivals of class 1

    Comparative analysis of inhaled particles contained in human bronchoalveolar lavage fluids, lung parenchyma and lymph nodes.

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    Translocation of inhaled particles from the alveolar spaces to lung parenchyma and lymph nodes is one of the mechanisms that determine the biopersistence of particles. This study compares the nonfibrous particulate burden in bronchoalveolar lavage (BAL) fluids, lung parenchyma, and thoracic lymph nodes and attempts to detect the degree of differentiation, if any, based on particle size or type. This comparison can only be done on BAL, lung parenchyma, and lymph node samples collected from the same subject over a short time. Patients undergoing surgical lung resection are suitable for this purpose. Particles recovered by digestion-filtration were counted, sized, and analyzed by analytical transmission electron microscopy. Total particle load ranges grossly between 10(5) to 10(7) p/ml in BAL, 10(9) to 10(10) p/g dry tissue in parenchyma and 10(10) to 10(11) p/g dry tissue in lymph nodes. Diameters are log-normally distributed and mean diameters range between 0.5 to 0.9 micron. Nonlamellar silicate particles have a significantly larger diameter in lymph nodes. Differences in particle type between the three sampling sites are small and nonsystematic

    Environmental Asbestotic Pleural Plaques in Northeast Corsica: Correlations with Airborne and Pleural Mineralogic Analysis

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    We report a prevalence study of environmental pleural plaques in subjects over 50 years old from the northeastern Corsican village of Murato, built on asbestos surface deposits. The percentage of plaques was 41%, versus 7.5% in the control village of Vezzani. Although surface deposits contain both chrysotile and tremolite, airborne pollution and asbestos lung burden of exposed inhabitants consist essentially of tremolite as assessed by transmission electron microscopy (TEM). However, TEM analysis of the parietal pleura of three animals bred in exposed areas showed a predominance of short fibers of chrysotile. The respective roles of tremolite and chrysotile in inducing pleural plaques in Corsica should thus be considered.—Environ Health Perspect 102(Suppl 5):251–252 (1994

    Cervical HIV-1 RNA shedding after cryotherapy among HIV-positive women with cervical intraepithelial neoplasia stage 2 or 3

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    Objective: To determine the effect of cryotherapy on HIV-1 cervical shedding. Design: Prospective cohort study. Methods: Five hundred HIV-positive women enrolled at an HIV treatment clinic in Nairobi, Kenya were screened for cervical cancer. Women diagnosed with cervical intraepithelial neoplasia stage 2 or 3 (CIN 2/3) by histology were offered cryotherapy treatment. The first 50 women had cervical swabs taken at baseline and at 2 and 4 weeks following treatment. Swabs were analyzed for HIV-1 RNA and compared using General Estimating Equation (GEE) with binomial or Gaussian links. Results: Of the 50 women enrolled, 40 were receiving antiretroviral therapy (ART) and 10 were not receiving ART at the time of cryotherapy and during study follow-up. Among all women, the odds of detectable cervical HIV-1 RNA did not increase at 2 weeks [odds ratio (OR) 1.18; 95% confidence interval (CI) 0.65-2.13] or 4 weeks (OR 1.29; 95% CI 0.71-2.33) following cryotherapy. Among 10 women not receiving ART, the OR of detectable shedding at 2 weeks was higher, but not statistically significant (OR 4.02; 95% CI 0.53-30.79; P = 0.2), and at 4 weeks remained unchanged (OR 1.00; 95% CI 0.27-3.74). Conclusion: There was no increase in detectable cervical HIV-1 RNA among HIV-positive women after cryotherapy. The risk of HIV-1 transmission after cryotherapy may not be significant, particularly among women already on ART at the time of cervical treatment. However, further investigation is needed among women not receiving ART

    Prevalence and determinants of human papillomavirus infection and cervical lesions in HIV-positive women in Kenya

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    Background: We assessed the association of human papillomavirus (HPV) infection and cervical intraepithelial neoplasia (CIN) with various characteristics, CD4 count and use of combination antiretroviral therapy (cART) among HIV-positive women. Methods: Cross-sectional study of 498 HIV-positive women who underwent HPV PCR-based testing, cytology, and systematic cervical biopsy. Results: In all, 68.7% of women were HPV-positive, 52.6% had high-risk (hr) HPV, and 40.2% multiple type infections. High-risk human papillomavirus-positivity did not vary significantly by age but it was negatively associated with education level. The most frequent types in 113 CIN2/3 were HPV16 (26.5%), HPV35 (19.5%), and HPV58 (12.4%). CD4 count was negatively associated with prevalence of hrHPV (Po0.001) and CIN2/3 among non-users of cART (P¼0.013). Combination antiretroviral therapies users (X2 year) had lower hrHPV prevalence (prevalence ratio (PR) vs non-users¼0.77, 95% confidence interval (CI): 0.61–0.96) and multiple infections (PR¼0.68, 95% CI: 0.53–0.88), but not fewer CIN2/3. The positive predictive value of hrHPV-positivity for CIN2/3 increased from 28.9% at age o35 years to 53.3% in X45 years. Conclusion: The burden of hrHPV and CIN2/3 was high and it was related to immunosuppression level. Combination antiretroviral therapies (X2 year) use had a favourable effect on hrHPV prevalence but cART in our population may have been started too late to prevent CIN2/3

    Implication of human papillomavirus-66 in vulvar carcinoma: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Vulvar cancer in older women is seldom associated with human papillomavirus infection.</p> <p>Case presentation</p> <p>We present the case of an 80-year-old Greek Caucasian woman with an undetermined obstetric and gynecologic history. The patient underwent radical vulvectomy and bilateral inguinal lymphadenectomy for a vulvar carcinoma. A human papillomavirus infection was suggested on the basis of histological and cytological examinations followed by human papillomavirus DNA typing, which revealed the presence of human papillomavirus-66.</p> <p>Conclusion</p> <p>Even though human papillomavirus-16 and human papillomavirus-18 are most frequently implicated in the pathogenesis of vulvar carcinoma, human papillomavirus-66 can also be regarded as a causative factor. Suspicious lesions should be biopsied, and in the presence of carcinoma, vulvectomy with bilateral lymphadenectomy, if necessary, must be performed. Furthermore, polymerase chain reaction assay analysis with clinical arrays in cytological samples is an accurate test for the detection of a wide range of human papillomavirus genotypes and can be used to verify the infection and specify the human papillomavirus type implicated.</p

    Increased Cervical Human Immunodeficiency Virus (HIV) RNA Shedding Among HIV-Infected Women Randomized to Loop Electrosurgical Excision Procedure Compared to Cryotherapy for Cervical Intraepithelial Neoplasia 2/3

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    Background Treatment of human immunodeficiency virus (HIV)–infected women to prevent cervical cancer may stimulate HIV RNA cervical shedding and risk HIV transmission. Methods From 2011 to 2014, 400 HIV-infected women diagnosed with cervical intraepithelial neoplasia 2/3 in Kenya were randomized to loop electrosurgical excision procedure (LEEP) or cryotherapy. Cervical samples were collected at baseline and 3 weekly intervals. Samples were tested for HIV RNA using the Gen-Probe Aptima HIV assay with a minimum detection level of 60 copies/swab and analyzed using generalized estimating equations. Results Women who received LEEP had significantly higher cervical HIV RNA levels than those who received cryotherapy at weeks 2 (adjusted incident rate ratio [aIRR], 1.07; P = .038) and 3 (aIRR, 1.08; P = .046). Within LEEP, significantly higher cervical shedding was found at weeks 2 (2.03 log10 copies/swab; P < .001) and 3 (2.04 log10 copies/swab; P < .001) compared to baseline (1.80 log10 copies/swab). Cervical HIV RNA was significantly higher following LEEP for up to 3 weeks among women on antiretroviral treatment (ART) (0.18 log10 copies/swab increase; P = .003) and in ART-naive women (1.13 log10 copies/swab increase; P < .001) compared to baseline. Within cryotherapy, cervical shedding increased in ART-naive women (0.72 log10 copies/swab increase; P = 0.004) but did not increase in women on ART. Conclusions Women randomized to LEEP had a larger increase in post-procedural cervical HIV shedding than cryotherapy. Benefits of cervical cancer prevention outweigh the risk of HIV sexual transmission; our findings underscore the importance of risk-reduction counseling

    Potential Impact of Antiretroviral Therapy and Screening on Cervical Cancer Mortality in HIV-Positive Women in Sub-Saharan Africa: A Simulation

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    Despite having high cervical cancer incidence and mortality rates, screening for cervical precancerous lesions remains infrequent in sub-Saharan Africa. The need to screen HIV-positive women because of the higher prevalence and faster progression of cervical precancerous lesions may be heightened by the increased access to highly-active antiretroviral therapy (HAART). Policymakers need quantitative data on the effect of HAART and screening to better allocate limited resources. Our aim was to quantify the potential effect of these interventions on cervical cancer mortality.We constructed a Markov state-transition model of a cohort of HIV-positive women in Cameroon. Published data on the prevalence, progression and regression of lesions as well as mortality rates from HIV, cervical cancer and other causes were incorporated into the model. We examined the potential impact, on cumulative cervical cancer mortality, of four possible scenarios: no HAART and no screening (NHNS), HAART and no screening (HNS), HAART and screening once on HAART initiation (HSHI), and HAART and screening once at age 35 (HS35). Our model projected that, compared to NHNS, lifetime cumulative cervical cancer mortality approximately doubled with HNS. It will require 262 women being screened at HAART initiation to prevent one cervical cancer death amongst women on HAART. The magnitudes of these effects were most sensitive to the rate of progression of precancerous lesions.Screening, even when done once, has the potential of reducing cervical cancer mortality among HIV-positive women in Africa. The most feasible and cost-effective screening strategy needs to be determined in each setting
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