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91.
92.
Overdiagnosis and overtreatment of breast cancer: Estimates of overdiagnosis from two trials of mammographic screening for breast cancer 总被引:1,自引:0,他引:1 下载免费PDF全文
Duffy SW Agbaje O Tabar L Vitak B Bjurstam N Björneld L Myles JP Warwick J 《Breast cancer research : BCR》2005,7(6):258-265
Randomised controlled trials have shown that the policy of mammographic screening confers a substantial and significant reduction in breast cancer mortality. This has often been accompanied, however, by an increase in breast cancer incidence, particularly during the early years of a screening programme, which has led to concerns about overdiagnosis, that is to say, the diagnosis of disease that, if left undetected and therefore untreated, would not become symptomatic. We used incidence data from two randomised controlled trials of mammographic screening, the Swedish Two-county Trial and the Gothenburg Trial, to establish the timing and magnitude of any excess incidence of invasive disease and ductal carcinoma in situ (DCIS) in the study groups, to ascertain whether the excess incidence of DCIS reported early in a screening trial is balanced by a later deficit in invasive disease and provide explicit estimates of the rate of 'real' and non-progressive 'overdiagnosed' tumours from the study groups of the trials. We used a multistate model for overdiagnosis and used Markov Chain Monte Carlo methods to estimate the parameters. After taking into account the effect of lead time, we estimated that less than 5% of cases diagnosed at prevalence screen and less than 1% of cases diagnosed at incidence screens are being overdiagnosed. Overall, we estimate overdiagnosis to be around 1% of all cases diagnosed in screened populations. These estimates are, however, subject to considerable uncertainty. Our results suggest that overdiagnosis in mammography screening is a minor phenomenon, but further studies with very large numbers are required for more precise estimation. 相似文献
93.
Pierre Feugier Deog-Yeon JO Jae Hung Shieh Karen L. MacKenzie JF Lesesve V Latger-Cannard D Bensoussan Ronald G Crystal Shahin Rafii JF Stoltz Malcolm A.S. Moore 《生物医学工程学杂志》2005,(Z1)
1 IntroductionCulture systems capable of expanding and/or maintaining hematopoietic stem cells will not only facilitate our understanding of stem cell biology, but also broaden clinical applications. Among various in vitro hematopoietic culture systems, co-cultures of marrow or CD34~ cells with an adherent stromal layer that can produce cytokines and extracellular matrix components most effectively supports long-term hematopoiesis (LTC), mimicking the bone marrow micro-environment.The OP-9 stromal cells ar... 相似文献
94.
GEORGE M. SPYRIDES DDS MS PHD JORGE PERDIGÅO DMD MS PHD CLÓVIS PAGANI DDS MS PHD MARIA AMÉLIA M. ARAÚJO DDS MS PHD SILVANA M.M. SPYRIDES DDS 《Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.]》2000,12(5):264-270
Background: Several studies have shown a reduction in enamel bond strengths when the bonding procedure is carried out immediately after vital bleaching with peroxides. This reduction in bond strengths has become a concern in cosmetic dentistry with the introduction of new “in‐office” and “waiting‐room” bleaching techniques. The aim of this in vitro study was to evaluate the effect of three bleaching regimens: 35% hydrogen peroxide (HP), 35% carbamide peroxide (CP), and 10% CP, on dentin bond strengths. Materials and Methods: One hundred and twenty fresh bovine incisors were used in this study. The labial surface of each tooth was ground flat to expose dentin and was subsequently polished with 600‐grit wet silicon carbide paper. The remaining dentin thickness was monitored and kept at an average of 2 mm. The teeth were randomly assigned to four bleaching regimens (n = 30): (A) control, no bleaching treatment; (B) 35% HP for 30 minutes; (C) 35% CP for 30 minutes; and (D) 10% CP for 6 hours. For each group, half of the specimens (n = 15) were bonded with Single Bond/Z100 immediately after the bleaching treatment, whereas the other half was bonded after the specimens were stored for 1 week in artificial saliva at 37°C. The specimens were fractured in shear using an Instron machine. Results: For the groups bonded immediately after bleaching, one‐way analysis of variance (ANOVA) followed by the Duncan's post hoc test revealed a statistically significant reduction in bond strengths in a range from 71% to 76%. For the groups bonded at 1 week, one‐way ANOVA showed that group B (35% HP for 30 min) resulted in the highest bond strengths, whereas 10% CP resulted in the lowest bond strengths. Student's t‐test showed that delayed bonding resulted in a significant increase in bond strengths for groups B (35% HP) and C (35% CP); whereas the group bleached with 10% CP (group D) remained in the same range obtained for immediate bonding. Storage in artificial saliva also affected the control group, reducing its bond strengths to 53% of the original. 相似文献
95.
Agbaje IM McVicar CM Schock BC McClure N Atkinson AB Rogers D Lewis SE 《Reproductive biomedicine online》2008,16(3):401-409
The effects of diabetes mellitus on male reproductive health have not been clearly defined. A previous publication from this group reported significantly higher levels of nuclear DNA fragmentation and mitochondrial DNA deletions in spermatozoa from men with type 1 diabetes. This study compared semen profiles, sperm DNA fragmentation and levels of oxidative DNA modification in spermatozoa of diabetic and non-diabetic men. Semen samples from 12 non-diabetic, fertile men and 11 type 1 diabetics were obtained and subjected to conventional light microscopic semen analysis. Nuclear DNA fragmentation was assessed using an alkaline Comet assay and concentrations of 7,8-dihydro-8-oxo-2-deoxyguanosine (8-OHdG), an oxidative adduct of the purine guanosine, were assessed by high-performance liquid chromatography. Conventional semen profiles were similar in both groups, whilst spermatozoa from type 1 diabetics showed significantly higher levels of DNA fragmentation (44% versus 27%; P < 0.05) and concentrations of 8-OHdG (3.6 versus 2.0 molecules of 8-OHdG per 10(5) molecules of deoxyguanosine; P < 0.05). Furthermore, a positive correlation was observed between DNA fragmentation and concentrations of 8-OHdG per 10(5) molecules of deoxyguanosine (rs = 0.7, P < 0.05). The genomic damage evident in spermatozoa of type 1 diabetics may have important implications for their fertility and the outcome of pregnancies fathered by these individuals. 相似文献
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97.
Platelet transfusion effectiveness may be limited in multiply transfused patients by the development of the refractory state. White cell (WBC)-reduction filters with variable efficiency (1-3 log10 reduction) are available and have been shown to be effective in reducing the incidence of platelet alloimmunization. However, the threshold number of WBCs below which alloimmunization would no longer occur is yet to be determined. A previously established animal model was used to examine the relative efficiency of second- and third- generation filters in reducing the frequency of refractoriness to allogeneic platelets. In this model, California Black rabbits are used as blood donors and New Zealand White rabbits as transfusion recipients. Eight weekly transfusions of either second-generation or third-generation WBC-reduced blood resulted in no difference between the two groups in mean platelet survival and rate of refractoriness to allogeneic platelets. To evaluate the possible incremental benefit of removing supernatant plasma to prevent platelet refractoriness, experiments were performed in which groups of animals were given transfusion(s) with red cell suspensions that had been WBC-reduced or both plasma-depleted and WBC-reduced. A significantly lower rate of allogeneic platelet refractoriness was seen in the rabbits that received WBC-reduced and plasma-depleted red cells than in those that received red cells that had been WBC-reduced only. These data provide evidence that the combined use of plasma depletion and WBC reduction can decrease still further the frequency of refractoriness produced by allogeneic blood transfusions. 相似文献
98.
Social intervention against AIDS among injecting drug users 总被引:2,自引:1,他引:1
SAMUEL R. FRIEDMAN ALAN NEAIGUS DON C. DES JARLAIS JO L. SOTHERAN JOYCELYN WOODS MERYL SUFIAN BRUCE STEPHERSON CLAIRE STERK 《Addiction (Abingdon, England)》1992,87(3):393-404
Many drug injectors continue to engage in behaviors that lead them to become infected with HIV in spite of a wide variety of public health programs. In addition, many persons have begun to inject drugs in spite of knowing the risks of AIDS. The inadequacy of current efforts to prevent these behaviors suggests that additional forms of intervention should be attempted. We suggest that social interventions be tried to complement current programs (almost all of which have an individual focus). Evidence that social factors such as peer pressure and the social relations of race affect risk behavior is presented. Social interventions that are discussed include organizing drug injectors against AIDS in ways analogous to those in which gays organized against the epidemic, and finding ways to change large-scale social relationships that predispose people to inject drugs. 相似文献
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100.
JO KIMBER RICHARD P. MATTICK JOHN KALDOR INGRID VAN BEEK STUART GILMOUR JAKE A. RANCE 《Drug and alcohol review》2008,27(6):602-612
Introduction and Aims . Low‐threshold drug services such as drug consumption rooms (DCRs) have been posited as referral gateways to drug treatment for injecting drug users (IDUs). We examined the process and predictors of drug treatment referral and referral uptake at an Australian DCR. Design and Methods . We undertook behavioural surveillance of the Sydney Medically Supervised Injecting Centre (MSIC) client cohort between May 2001 and October 2002. Data were collected for 3715 IDUs on demographics, injecting and drug use behaviours at registration and all subsequent MSIC service utilisation, including referrals. Referral uptake (defined as presentation for assessment at the relevant agency) was traced via reply‐paid postcards included with written referrals. Results . Sixteen per cent of clients who received written referrals to drug treatment had confirmed drug treatment referral uptake. Factors associated with drug treatment referral were frequent MSIC attendance [adjusted odds ratios (AOR = 9.4], receipt of written health (AOR = 4.8) or psychosocial (AOR = 4.3) referrals, heroin as main drug injected (AOR = 1.9) and completion of high school education (AOR = 1.6). Factors associated positively with drug treatment referral uptake were recent sex work (AOR = 2.6) and at least daily injection (AOR 2.3). Previous psychiatric illness or self‐harm was associated negatively with drug treatment referral uptake (AOR = 0.2). Discussion and Conclusions . MSIC engaged IDUs successfully in drug treatment referral and this was associated with presentation for drug treatment assessment and other health and psychosocial services. To improve rates of drug treatment referral and uptake, those with a history of mental health issues may require more intensive referral and case management. 相似文献