993 resultados para DOSE NUMBER
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PURPOSE: To evaluate the diagnostic performance of abdominal radiography in the detection of illegal intracorporeal containers (hereafter, packets), with low-dose computed tomography (CT) as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional ethical review board, with written informed consent. From July 2007 to July 2010, 330 people (296 men, 34 women; mean age, 32 years [range, 18-55 years]) suspected of having ingested drug packets underwent supine abdominal radiography and low-dose CT. The presence or absence of packets at abdominal radiography was reported, with low-dose CT as the reference standard. The density and number of packets (≤ 12 or >12) at low-dose CT were recorded and analyzed to determine whether those variables influence interpretation of results at abdominal radiography. RESULTS: Packets were detected at low-dose CT in 53 (16%) suspects. Sensitivity of abdominal radiography for depiction of packets was 0.77 (41 of 53), and specificity was 0.96 (267 of 277). The packets appeared isoattenuated to the bowel contents at low-dose CT in 16 (30%) of the 53 suspects with positive results. Nineteen (36%) of the 53 suspects with positive low-dose CT results had fewer than 12 packets. Packets that were isoattenuated at low-dose CT and a low number of packets (≤12) were both significantly associated with false-negative results at abdominal radiography (P = .004 and P = .016, respectively). CONCLUSION: Abdominal radiography is mainly limited by low sensitivity when compared with low-dose CT in the screening of people suspected of carrying drug packets. Low-dose CT is an effective imaging alternative to abdominal radiography.
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Since the early 1980s high dose chemotherapy with autologous hematopoietic stem cell support was adopted by many oncologists as a potentially curative option for solid tumors, supported by a strong rationale from laboratory studies and apparently convincing results of early phase II studies. As a result, the number and size of randomized trials comparing this approach with conventional chemotherapy initiated (and often abandoned before completion) to prove or disprove its value was largely insufficient. In fact, with the possible exception of breast carcinoma, the benefit of a greater escalation of dose of chemotherapy with stem cell support in solid tumors is still unsettled and many oncologists believe that this approach should cease. In this article, we critically review and comment on the data from studies of high dose chemotherapy so far reported in adult patients with small cell lung cancer, ovarian cancer, germ cell tumors and sarcomas.
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Abstract : A preliminary understanding of the phenotypic effect of copy number variation (CNV) of DNA segments is emerging. These rearrangements were shown to influence, in a somewhat dose-dependent manner, the expression of genes mapping within them. They were also shown to modify the expression of genes located on their Hanks, sometimes at great distance. Here, we demonstrate by monitoring these effects at multiple life stages, that these controls over expression are effective throughout mouse development. Similarly, we observe that the more specific spatial expression patterns of CNV genes are maintained through life. However, 'we find that some brain- expressed genes mapping within CNVS appear to be under compensatory loops only at specific time-points, indicating that the effect of CNVS on these genes is modulated during development. Notably, we also observe that CNV genes are significantly enriched within transcripts that show variable time-course expression between strains. Thus, modifying the copy number of a gene may potentially alter not only its expression level, but its timing of expression as well. Résume : Nous commençons à comprendre les effets phénotypiques liés aux séquences d'ADN qui changent de nombre de copies d'un individu a l'autre. Des travaux précédents ont montré que ces variante de nombre de copies (CNVS) avaient une influence sur l'expression non seulement des gènes se trouvant dans le réarrangement, mais aussi sur ceux se trouvant à une certaine distance. Le présent travail étudie ces effets à différents stades du développement de la souris allant d'un embryon de deux semaines à la souris adulte. Nous avons observé que certains gènes exprimés dans le cerveau semblent soumis à un contrôle plus strict a certaines étapes du développement suggèrent que l'effet des CNVs est modulé différemment au cours de la vie. Notre travail sur trois souches différentes de souris a permis de montrer que les gènes ayant un profil d'expression différent dans le temps entre souches sont enrichis en gènes se trouvant dans des CNVs. Ceci nous amène à penser que les CNVs ont, non seulement une influence sur le niveau d'expression des gènes, mais aussi sur les moments durant lesquels ils seront exprimés. Résumé pour un large public : De nombreuses maladies sont dues soit a un gain (on parle alors de duplication) soit à une perte de matériel génétique (il s'agit dune délétion). Bien que les recherches visant à identifier les mécanismes moléculaires liés à ces réarrangements de notre génome progressent continuellement, la plupart des causes des maladies génétiques restent à élucider. Certaines parties de notre génome sont présentes en un nombre de copies qui diffère d'un individu à l'autre sans pour autant provoquer une ou des maladies. Ces segments d'ADN qui varient en nombre sont appelés Copy Number Variant (CNVs). Ils couvrent environ 12% de notre matériel génétique. Des études menées sur différents modèles animaux ont montré que les CNVs avaient une influence aussi bien sur les gènes qui sont a l'intérieur des CNVs que sur ceux qui sont dans leur voisinage. Ce travail étudie l'effet des CNVs à travers différents stades du développement de la souris. Nous avons démontré que les segments d'ADN qui varient en nombre de copies ont des effets variables selon le stade auxquels ils sont mesurés. Ainsi, les CNVs ont non seulement un impact sur l'expression des gènes présents dans ces régions et dans leur voisinage, mais influencent également leurs profils d'expression au cours du temps.
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In the last two decades, anti-cancer vaccines have yielded disappointing clinical results despite the fact that high numbers of self/tumor-specific T cells can be elicited in immunized patients. Understanding the reasons behind this lack of efficacy is critical in order to design better treatment regimes. Recombinant lentivectors (rLVs) have been successfully used to induce antigen-specific T cells to foreign or mutated tumor antigens. Here, we show that rLV expressing a murine nonmutated self/tumor antigen efficiently primes large numbers of self/tumor-specific CD8(+) T cells. In spite of the large number of tumor-specific T cells, however, no anti-tumor activity could be measured in a therapeutic setting, in mice vaccinated with rLV. Accumulating evidence shows that, in the presence of malignancies, inhibition of T-cell activity may predominate overstimulation. Analysis of tumor-infiltrating lymphocytes revealed that specific anti-tumor CD8(+) T cells fail to produce cytokines and express high levels of inhibitory receptors such as programmed death (PD)-1. Association of active immunization with chemotherapy or antibodies that block inhibitory pathways often leads to better anti-tumor effects. We show here that combining rLV vaccination with either cyclophosphamide or PD-1 and PD-L1 blocking antibodies enhances rLV vaccination efficacy and improves anti-tumor immunity.
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This work aimed at assessing the doses delivered in Switzerland to paediatric patients during computed tomography (CT) examinations of the brain, chest and abdomen, and at establishing diagnostic reference levels (DRLs) for various age groups. Forms were sent to the ten centres performing CT on children, addressing the demographics, the indication and the scanning parameters: number of series, kilovoltage, tube current, rotation time, reconstruction slice thickness and pitch, volume CT dose index (CTDI(vol)) and dose length product (DLP). Per age group, the proposed DRLs for brain, chest and abdomen are, respectively, in terms of CTDI(vol): 20, 30, 40, 60 mGy; 5, 8, 10, 12 mGy; 7, 9, 13, 16 mGy; and in terms of DLP: 270, 420, 560, 1,000 mGy cm; 110, 200, 220, 460 mGy cm; 130, 300, 380, 500 mGy cm. An optimisation process should be initiated to reduce the spread in dose recorded in this study. A major element of this process should be the use of DRLs.
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Patients with type 2 diabetes mellitus exhibit a marked increase in cardiovascular and renal risk. A number of interventional trials have shown that these patients benefit greatly from aggressive BP lowering, especially when the drug regimen comprises an inhibitor of the renin-angiotensin system. The results of the placebo-controlled ADVANCE (Action in Diabetes and Vascular disease: PreterAx and DiamicroN MR Controlled Evaluation) trial, conducted in patients with type 2 diabetes, are exemplary in this respect. The systematic use of a fixed-dose combination containing the ACE inhibitor perindopril and the diuretic indapamide afforded substantial protection against cardiovascular mortality and myocardial infarction, while providing important renoprotection, reducing the development of micro- and macroalbuminuria, and allowing regression of nephropathy. The beneficial effects were obtained regardless of baseline BP and whether or not the patients were receiving antihypertensive therapy.
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A preliminary understanding into the phenotypic effect of DNA segment copy number variation (CNV) is emerging. These rearrangements were demonstrated to influence, in a somewhat dose-dependent manner, the expression of genes that map within them. They were also shown to modify the expression of genes located on their flanks and sometimes those at a great distance from their boundary. Here we demonstrate, by monitoring these effects at multiple life stages, that these controls over expression are effective throughout mouse development. Similarly, we observe that the more specific spatial expression patterns of CNV genes are maintained through life. However, we find that some brain-expressed genes mapping within CNVs appear to be under compensatory loops only at specific time points, indicating that the effect of CNVs on these genes is modulated during development. Notably, we also observe that CNV genes are significantly enriched within transcripts that show variable time courses of expression between strains. Thus, modifying the copy number of a gene may potentially alter not only its expression level, but also the timing of its expression.
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Intravascular brachytherapy with beta sources has become a useful technique to prevent restenosis after cardiovascular intervention. In particular, the Beta-Cath high-dose-rate system, manufactured by Novoste Corporation, is a commercially available 90Sr 90Y source for intravascular brachytherapy that is achieving widespread use. Its dosimetric characterization has attracted considerable attention in recent years. Unfortunately, the short ranges of the emitted beta particles and the associated large dose gradients make experimental measurements particularly difficult. This circumstance has motivated the appearance of a number of papers addressing the characterization of this source by means of Monte Carlo simulation techniques.
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La tomodensitométrie (TDM) est une technique d'imagerie pour laquelle l'intérêt n'a cessé de croitre depuis son apparition au début des années 70. De nos jours, l'utilisation de cette technique est devenue incontournable, grâce entre autres à sa capacité à produire des images diagnostiques de haute qualité. Toutefois, et en dépit d'un bénéfice indiscutable sur la prise en charge des patients, l'augmentation importante du nombre d'examens TDM pratiqués soulève des questions sur l'effet potentiellement dangereux des rayonnements ionisants sur la population. Parmi ces effets néfastes, l'induction de cancers liés à l'exposition aux rayonnements ionisants reste l'un des risques majeurs. Afin que le rapport bénéfice-risques reste favorable au patient il est donc nécessaire de s'assurer que la dose délivrée permette de formuler le bon diagnostic tout en évitant d'avoir recours à des images dont la qualité est inutilement élevée. Ce processus d'optimisation, qui est une préoccupation importante pour les patients adultes, doit même devenir une priorité lorsque l'on examine des enfants ou des adolescents, en particulier lors d'études de suivi requérant plusieurs examens tout au long de leur vie. Enfants et jeunes adultes sont en effet beaucoup plus sensibles aux radiations du fait de leur métabolisme plus rapide que celui des adultes. De plus, les probabilités des évènements auxquels ils s'exposent sont également plus grandes du fait de leur plus longue espérance de vie. L'introduction des algorithmes de reconstruction itératifs, conçus pour réduire l'exposition des patients, est certainement l'une des plus grandes avancées en TDM, mais elle s'accompagne de certaines difficultés en ce qui concerne l'évaluation de la qualité des images produites. Le but de ce travail est de mettre en place une stratégie pour investiguer le potentiel des algorithmes itératifs vis-à-vis de la réduction de dose sans pour autant compromettre la qualité du diagnostic. La difficulté de cette tâche réside principalement dans le fait de disposer d'une méthode visant à évaluer la qualité d'image de façon pertinente d'un point de vue clinique. La première étape a consisté à caractériser la qualité d'image lors d'examen musculo-squelettique. Ce travail a été réalisé en étroite collaboration avec des radiologues pour s'assurer un choix pertinent de critères de qualité d'image. Une attention particulière a été portée au bruit et à la résolution des images reconstruites à l'aide d'algorithmes itératifs. L'analyse de ces paramètres a permis aux radiologues d'adapter leurs protocoles grâce à une possible estimation de la perte de qualité d'image liée à la réduction de dose. Notre travail nous a également permis d'investiguer la diminution de la détectabilité à bas contraste associée à une diminution de la dose ; difficulté majeure lorsque l'on pratique un examen dans la région abdominale. Sachant que des alternatives à la façon standard de caractériser la qualité d'image (métriques de l'espace Fourier) devaient être utilisées, nous nous sommes appuyés sur l'utilisation de modèles d'observateurs mathématiques. Nos paramètres expérimentaux ont ensuite permis de déterminer le type de modèle à utiliser. Les modèles idéaux ont été utilisés pour caractériser la qualité d'image lorsque des paramètres purement physiques concernant la détectabilité du signal devaient être estimés alors que les modèles anthropomorphes ont été utilisés dans des contextes cliniques où les résultats devaient être comparés à ceux d'observateurs humain, tirant profit des propriétés de ce type de modèles. Cette étude a confirmé que l'utilisation de modèles d'observateurs permettait d'évaluer la qualité d'image en utilisant une approche basée sur la tâche à effectuer, permettant ainsi d'établir un lien entre les physiciens médicaux et les radiologues. Nous avons également montré que les reconstructions itératives ont le potentiel de réduire la dose sans altérer la qualité du diagnostic. Parmi les différentes reconstructions itératives, celles de type « model-based » sont celles qui offrent le plus grand potentiel d'optimisation, puisque les images produites grâce à cette modalité conduisent à un diagnostic exact même lors d'acquisitions à très basse dose. Ce travail a également permis de clarifier le rôle du physicien médical en TDM: Les métriques standards restent utiles pour évaluer la conformité d'un appareil aux requis légaux, mais l'utilisation de modèles d'observateurs est inévitable pour optimiser les protocoles d'imagerie. -- Computed tomography (CT) is an imaging technique in which interest has been quickly growing since it began to be used in the 1970s. Today, it has become an extensively used modality because of its ability to produce accurate diagnostic images. However, even if a direct benefit to patient healthcare is attributed to CT, the dramatic increase in the number of CT examinations performed has raised concerns about the potential negative effects of ionising radiation on the population. Among those negative effects, one of the major risks remaining is the development of cancers associated with exposure to diagnostic X-ray procedures. In order to ensure that the benefits-risk ratio still remains in favour of the patient, it is necessary to make sure that the delivered dose leads to the proper diagnosis without producing unnecessarily high-quality images. This optimisation scheme is already an important concern for adult patients, but it must become an even greater priority when examinations are performed on children or young adults, in particular with follow-up studies which require several CT procedures over the patient's life. Indeed, children and young adults are more sensitive to radiation due to their faster metabolism. In addition, harmful consequences have a higher probability to occur because of a younger patient's longer life expectancy. The recent introduction of iterative reconstruction algorithms, which were designed to substantially reduce dose, is certainly a major achievement in CT evolution, but it has also created difficulties in the quality assessment of the images produced using those algorithms. The goal of the present work was to propose a strategy to investigate the potential of iterative reconstructions to reduce dose without compromising the ability to answer the diagnostic questions. The major difficulty entails disposing a clinically relevant way to estimate image quality. To ensure the choice of pertinent image quality criteria this work was continuously performed in close collaboration with radiologists. The work began by tackling the way to characterise image quality when dealing with musculo-skeletal examinations. We focused, in particular, on image noise and spatial resolution behaviours when iterative image reconstruction was used. The analyses of the physical parameters allowed radiologists to adapt their image acquisition and reconstruction protocols while knowing what loss of image quality to expect. This work also dealt with the loss of low-contrast detectability associated with dose reduction, something which is a major concern when dealing with patient dose reduction in abdominal investigations. Knowing that alternative ways had to be used to assess image quality rather than classical Fourier-space metrics, we focused on the use of mathematical model observers. Our experimental parameters determined the type of model to use. Ideal model observers were applied to characterise image quality when purely objective results about the signal detectability were researched, whereas anthropomorphic model observers were used in a more clinical context, when the results had to be compared with the eye of a radiologist thus taking advantage of their incorporation of human visual system elements. This work confirmed that the use of model observers makes it possible to assess image quality using a task-based approach, which, in turn, establishes a bridge between medical physicists and radiologists. It also demonstrated that statistical iterative reconstructions have the potential to reduce the delivered dose without impairing the quality of the diagnosis. Among the different types of iterative reconstructions, model-based ones offer the greatest potential, since images produced using this modality can still lead to an accurate diagnosis even when acquired at very low dose. This work has clarified the role of medical physicists when dealing with CT imaging. The use of the standard metrics used in the field of CT imaging remains quite important when dealing with the assessment of unit compliance to legal requirements, but the use of a model observer is the way to go when dealing with the optimisation of the imaging protocols.
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Objective The present study was aimed at estimating the doses received by physicians and patients during cerebral angiography procedures in a public hospital of Recife, PE, Brazil. Materials and Methods The study sample included 158 adult patients, and during the procedures the following parameters were evaluated: exposure parameters (kV, mAs), number of acquired images, reference air kerma value (Ka,r) and air kerma-area product (PKA). Additionally, the physicians involved in the procedures were evaluated as for absorbed dose in the eyes, thyroid, chest, hands and feet. Results The results demonstrated that the doses to the patients' eyes region were relatively close to the threshold for cataract occurrence. As regards the physicians, the average effective dose was 2.6 µSv, and the highest effective dose recorded was 16 µSv. Conclusion Depending on the number of procedures, the doses received by the physicians may exceed the annual dose limit for the crystalline lenses (20 mSv) established by national and international standards. It is important to note that the high doses received by the physicians are due to the lack of radiation protection equipment and accessories, such as leaded curtains, screens and protective goggles.
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AbstractObjective:To assess the reduction of estimated radiation dose in abdominal computed tomography following the implementation of new scan protocols on the basis of clinical suspicion and of adjusted images acquisition parameters.Materials and Methods:Retrospective and prospective review of reports on radiation dose from abdominal CT scans performed three months before (group A – 551 studies) and three months after (group B – 788 studies) implementation of new scan protocols proposed as a function of clinical indications. Also, the images acquisition parameters were adjusted to reduce the radiation dose at each scan phase. The groups were compared for mean number of acquisition phases, mean CTDIvol per phase, mean DLP per phase, and mean DLP per scan.Results:A significant reduction was observed for group B as regards all the analyzed aspects, as follows: 33.9%, 25.0%, 27.0% and 52.5%, respectively for number of acquisition phases, CTDIvol per phase, DLP per phase and DLP per scan (p < 0.001).Conclusion:The rational use of abdominal computed tomography scan phases based on the clinical suspicion in conjunction with the adjusted images acquisition parameters allows for a 50% reduction in the radiation dose from abdominal computed tomography scans.
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BACKGROUND: The ongoing Ebola outbreak led to accelerated efforts to test vaccine candidates. On the basis of a request by WHO, we aimed to assess the safety and immunogenicity of the monovalent, recombinant, chimpanzee adenovirus type-3 vector-based Ebola Zaire vaccine (ChAd3-EBO-Z). METHODS: We did this randomised, double-blind, placebo-controlled, dose-finding, phase 1/2a trial at the Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. Participants (aged 18-65 years) were randomly assigned (2:2:1), via two computer-generated randomisation lists for individuals potentially deployed in endemic areas and those not deployed, to receive a single intramuscular dose of high-dose vaccine (5 × 10(10) viral particles), low-dose vaccine (2·5 × 10(10) viral particles), or placebo. Deployed participants were allocated to only the vaccine groups. Group allocation was concealed from non-deployed participants, investigators, and outcome assessors. The safety evaluation was not masked for potentially deployed participants, who were therefore not included in the safety analysis for comparison between the vaccine doses and placebo, but were pooled with the non-deployed group to compare immunogenicity. The main objectives were safety and immunogenicity of ChAd3-EBO-Z. We did analysis by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT02289027. FINDINGS: Between Oct 24, 2014, and June 22, 2015, we randomly assigned 120 participants, of whom 18 (15%) were potentially deployed and 102 (85%) were non-deployed, to receive high-dose vaccine (n=49), low-dose vaccine (n=51), or placebo (n=20). Participants were followed up for 6 months. No vaccine-related serious adverse events were reported. We recorded local adverse events in 30 (75%) of 40 participants in the high-dose group, 33 (79%) of 42 participants in the low-dose group, and five (25%) of 20 participants in the placebo group. Fatigue or malaise was the most common systemic adverse event, reported in 25 (62%) participants in the high-dose group, 25 (60%) participants in the low-dose group, and five (25%) participants in the placebo group, followed by headache, reported in 23 (57%), 25 (60%), and three (15%) participants, respectively. Fever occurred 24 h after injection in 12 (30%) participants in the high-dose group and 11 (26%) participants in the low-dose group versus one (5%) participant in the placebo group. Geometric mean concentrations of IgG antibodies against Ebola glycoprotein peaked on day 28 at 51 μg/mL (95% CI 41·1-63·3) in the high-dose group, 44·9 μg/mL (25·8-56·3) in the low-dose group, and 5·2 μg/mL (3·5-7·6) in the placebo group, with respective response rates of 96% (95% CI 85·7-99·5), 96% (86·5-99·5), and 5% (0·1-24·9). Geometric mean concentrations decreased by day 180 to 25·5 μg/mL (95% CI 20·6-31·5) in the high-dose group, 22·1 μg/mL (19·3-28·6) in the low-dose group, and 3·2 μg/mL (2·4-4·9) in the placebo group. 28 (57%) participants given high-dose vaccine and 31 (61%) participants given low-dose vaccine developed glycoprotein-specific CD4 cell responses, and 33 (67%) and 35 (69%), respectively, developed CD8 responses. INTERPRETATION: ChAd3-EBO-Z was safe and well tolerated, although mild to moderate systemic adverse events were common. A single dose was immunogenic in almost all vaccine recipients. Antibody responses were still significantly present at 6 months. There was no significant difference between doses for safety and immunogenicity outcomes. This acceptable safety profile provides a reliable basis to proceed with phase 2 and phase 3 efficacy trials in Africa. FUNDING: Swiss State Secretariat for Education, Research and Innovation (SERI), through the EU Horizon 2020 Research and Innovation Programme.
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In development of human medicines, it is important to predict early and accurately enough the disease and patient population to be treated as well as the effective and safe dose range of the studied medicine. This is pursued by using preclinical research models, clinical pharmacology and early clinical studies with small sample sizes. When successful, this enables effective development of medicines and reduces unnecessary exposure of healthy subjects and patients to ineffectice or harmfull doses of experimental compounds. Toremifene is a selective estrogen receptor modulator (SERM) used for treatment of breast cancer. Its development was initiated in 1980s when selection of treatment indications and doses were based on research in cell and animal models and on noncomparative clinical studies including small number of patients. Since the early development phase, the treatment indication, the patient population and the dose range were confirmed in large comparative clinical studies in patients. Based on the currently available large and long term clinical study data the aim of this study was to investigate how the early phase studies were able to predict the treatment indication, patient population and the dose range of the SERM. As a conclusion and based on the estrogen receptor mediated mechanism of action early studies were able to predict the treatment indication, target patient population and a dose range to be studied in confirmatory clinical studies. However, comparative clinical studies are needed to optimize dose selection of the SERM in treatment of breast cancer.
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PURPOSE: To assess the effects of a soy dietary supplement on the main biomarkers of cardiovascular health in postmenopausal women compared with the effects of low-dose hormone therapy (HT) and placebo.METHODS: Double-blind, randomized and controlled intention-to-treat trial. Sixty healthy postmenopausal women, aged 40-60 years, 4.1 years mean time since menopause were recruited and randomly assigned to 3 groups: a soy dietary supplement group (isoflavone 90mg), a low-dose HT group (estradiol 1 mg plus noretisterone 0.5 mg) and a placebo group. Lipid profile, glucose level, body mass index, blood pressure and abdominal/hip ratio were evaluated in all the participants at baseline and after 16 weeks. Statistical analyses were performed using the χ2 test, Fisher's exact test, Kruskal-Wallis non-parametric test, analysis of variance (ANOVA), paired Student's t-test and Wilcoxon test.RESULTS: After a 16-week intervention period, total cholesterol decreased 11.3% and LDL-cholesterol decreased 18.6% in the HT group, but both did not change in the soy dietary supplement and placebo groups. Values for triglycerides, HDL-cholesterol, glucose level, body mass index, blood pressure and abdominal/hip ratio did not change over time in any of the three groups.CONCLUSION: The use of dietary soy supplement did not show any significant favorable effect on cardiovascular health biomarkers compared with HT. Clinical Trial Registry: The trial is registered at the Brazilian Clinical Trials Registry (Registro Brasileiro de Ensaios Clínicos - ReBEC), number RBR-76mm75.
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PURPOSE: To compare two single-agent chemotherapy (ChT) regimens evaluating, in first-line treatment, response and side effects and, in final single-agent treatment, the outcomes, among Brazilian patients with low-risk gestational trophoblastic neoplasia (GTN), according to International Federation of Gynecology and Obstetrics (FIGO) 2002. METHODS: Retrospective analysis of two concurrent cohorts with 194 low-risk GTN patients: from 1992 to 2012, as first-line treatment, 115 patients received 4 intramuscular doses of methotrexate alternated with 4 oral doses of folinic acid (MTX/FA) repetead every 14 days and, since 1996, 79 patients received an endovenous bolus-dose of actinomycin D (Act-D), biweekly. At GTN diagnosis, patient opinion was taken into consideration when defining the initial single-agent ChT regimen, and when there was resistance or toxicity to one regimen, the other drug was used preferentially. This study was approved by the Irmandade da Santa Casa de Misericórdia de Porto Alegre Ethical Committee. RESULTS: Both groups were clinically similar (p>0.05). In first-line treatments, frequency of complete response was similar (75.7% with MTX/FA and 67.1% with bolus Act-D); the number of ChT courses -median 3 (range: 1-10) with MTX/FA and 2 (range: 1-6) with bolus Act-D - and the time to remission -median 9 weeks (range: 2-16) with MTX/FA and 10 weeks (range: 2-16) with bolus Act-D) - were not different between the groups. In both groups, first-line side effects frequency were high but intensity was low; stomatitis was higher with MTX/FA (p<0.01) and nausea and vomit with Act-D (p<0.01). Final single-agent ChT responses were high in both groups (94.8% with MTX/FA and 83.5% with bolus Act-D; p<0.01) and 13% higher in the group initially treated with MTX/FA. Rates of hysterectomy and of GTN recurrence were low and similar. No patient died due to GTN. CONCLUSION: The two regimens had similar first-line ChT response. Final single-agent response rates were high and similar in both groups but the final single-agent remission rate was higher in the MTX/FA group.