301 research outputs found

    Extremal Vanishing Horizon Kerr-AdS Black Holes at Ultraspinning Limit

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    By utilizing the ultraspinning limit we generate a new class of extremal vanishing horizon (EVH) black holes in odd dimensions (d5d\geq5). Starting from the general multi-spinning Kerr-AdS metrics, we show the EVH limit commutes with the ultraspinning limit, in which the resulting solutions possess a non-compact but finite area manifold for all (t,rr+)=const.(t,r\neq r_+)=const. slices. We also demonstrate the near horizon geometries of obtained ultraspinning EVH solutions contain an AdS3_3 throats, where it would be a BTZ black hole in the near EVH cases. The commutativity of the ultraspinning and near horizon limits for EVH solutions is confirmed as well. Furthermore, we discuss only the five-dimensional case near the EVH point can be viewed as a super-entropic black hole. We also show that the thermodynamics of the obtained solutions agree with the BTZ black hole. Moreover we investigate the EVH/CFT proposal, demonstrating the entropy of 22d dual CFT and Bekenstein-Hawking entropy are equivalent.Comment: 29 pages, 3 figures, references added, typos corrected, revised version to match published versio

    Endoscopic screening for precancerous lesions of the esophagus in a high risk area in northern Iran

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    Background: Esophageal squamous cell carcinoma (ESCC) is a major health problem in many developing countries, including Iran. ESCC has a very poor prognosis, largely due to late diagnosis. As a first step in developing an early detection and treatment program, we conducted a population-based endoscopic screening for ESCC and its precursor lesion, esophageal squamous dysplasia (ESD), in asymptomatic adults from Golestan Province, northern Iran (a high-risk area for ESCC) to evaluate the feasibility of such a program and to document the prevalence and risk factor correlates of ESD. Methods: This cross-sectional study was conducted among participants of the Golestan Cohort Study (GCS), a population-based cohort of 50,000 adults in eastern Golestan Province. Randomly selected GCS participants were invited by telephone. Those who accepted were referred to a central endoscopy clinic. Eligible subjects who consented were asked to complete a brief questionnaire. Detailed information about selected risk factors was obtained from the GCS main database. Endoscopic examination with was performed with Lugol's iodine staining; biopsies were taken from unstained lesions as well as the normally stained mucosa of the esophagus, and the biopsies were diagnosed by expert pathologists according to previously described criteria. Results: In total, 1906 GCS subjects were invited, of whom only 302 (15.8%) were successfully enrolled. Esophagitis (29.5%) and ESD (6.0%) were the most common pathological diagnoses. Turkmen ethnicity (adjusted OR = 8.61; 95%CI: 2.48-29.83), being older than the median age (OR = 7.7; 95% CI: 1.99-29.87), and using deep frying cooking methods (OR = 4.65; 95%CI: 1.19-18.22) were the strongest predictors for ESD. There were significant relationships between esophagitis and smoking (p-value<0.001), drinking hot tea (P value = 0.02) and lack of education (P value = 0.004). Conclusion: We observed a low rate of participation in endoscopic screening. The overall prevalence of ESD was 6.0%. Developing non-endoscopic primary screening methods and screening individuals with one or more risk factors may improve these rates

    Evaluation of fluconazole effect in prevention of fungal infection and mortality and morbidity in very low-birth-weight infants

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    Background: Fungal infections especially Candida species are frequent cause of mortality and morbidity in very low-birth-weight (VLBW) infants receiving intensive care; Candida infections are tissue invasive. This infection increases the risks of adverse neurodevelopmental sequelae. Prevention and treatment of fungal infection is so important in very VLBW infants. The aim of this study was to determine the prophylactic effect of fluconazole in decreasing the mortality and morbidity in VLBW infants (less than 1500gr) admitted in NICU. Methods: This prospective case control study were conducted among 102 Infants (weighing less than 1500gr at birth at born) admitted in NICU department of Ali Asghar University Hospital from 2012 to 2013, Tehran, Iran. Weigh of birth in cases and groups were less than 1500 gr and both were culture negative. Cases received oral fluconazole 3 mg/kg in 3 days in 1st and 2nd weeks, alternate day in 3rd and 4th weeks, daily in 5th and 6th weeks. Control groups had not received fluconazole. Mortality and morbidity and hospital stay were compared between cases and controls groups. Results: We studied 49 very low-birth-weight infants with negative culture as cases (received fluconazole prophylaxis), 46 VLBW infants without fluconazole profilaxy (controls). No significant difference in gestational age (P=0.2), and mean weights (P=0.4) were observed between cases and controls. The mortality rate 8.7 (n=4) in controls (without prophylactic fluconazole) observed vs 2 (n=1) mortality rate in VLBW cases (with prophylactic fluconazole). Although the mortality rate in controls was 4 times higher than cases, but without significant differences (P=0.1). Indeed, mean duration of hospital stay in controls was longer than cases (28.41±9.93 vs 19.85±6.19 days, P=0.00001). Conclusion: Although prophylactic fluconazole in VLBW could decrease the mortality of cases (control the fungal infection) 4 fold in compare with controls (no treatment), it was not significant. The prophylactic effect of fluconazole might decrease the length of hospital stay of VLBW neonates in NICU. Due to limited number of cases and control. For further decision about prophylactic use of fluconazole, prospective RCT studies with larger cases and control would be helpful in future. © 2016, Tehran University of Medical Sciences. All rights reserved

    Cytomegalovirus and toxoplasma gondii: Common causes of profound sensori neural hearing loss in children with cochlear implant surgery in a highly immune population: Tehran; Iran

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    Background: Iranian population is highly immune from T.Gondii and CMV infection. Objective: To determine the immunity to T.Gondii and CMV in children with the cochlear implant surgery accompanied with the profound Idiopathic type of SNHL Methods and Materials: We studied 45 cases with the cochlear implant surgery (Idiopathic profound SNHL) and 30 controls with the normal OAEs in a cross-sectional study in Rasoul Akram Hospital in Tehran (2010-2012). Blood samples (2 ml) were centrifuged and were kept frozen at-20°C. Sera searched for the specific antibodies against CMV and T.Gondii. The enzyme-linked immunosorbent assay (ELISA; BioChem Immune System) was calculated qualitatively. (P value< 0.05) Results: Range of age in cases with profound SNHL (<95 dB) was 6 months-to-14 years; mean=3.4+3.16 y; Idiopathic type of SNHL children diagnosed in 45 cases were younger than cases with non-Idiopathic SNHL (mean age=20 months; PV=0.05). Positive T.Gondii-IgM was found in 8 /45 (17.7) and also one of these cases (2.2) had positive T.Gondii �IgG test. Positive CMV-IgM & IgG were determined in 23 and 51 of cases, respectively. Positive T.Gondii �IgG was observed in 60 (18/30) of controls but none of them had positive T.Gondii � IgM. Positive CMV-IgM & IgG in controls was 3.3 and 90, respectively. Conclusion: CMV infection is one of the most common infections found in profound idiopathic SNHL children especially in younger cases (< 2 years) even in highly immune Iranian populations. Probably, T.Gondii infection has a relative role in younger cases with profound SNHL but a higher role in mild to moderate SNHL in our pediatric population. Most of the T.Gondii infected SNHL cases never require cochlear implant surgery. In future, a cohort study for prenatal diagnosis of the intrauterine infection and the role of infection in producing SNHLwould be very helpful. It has been recommended to search the specific antibodies against these two common infections in all types of SNHL in pediatric groups which are treatable especially in younger cases (<2 year). © 2019 Noorbakhsh et al

    BACTEC medium: A useful method for detection of microorganisms in sterile body fluids

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    Background: Infectious diseases are problematic in all around the world especially in the developing countries and early diagnosis of infections and one etiologic agents has a major role in the treatment of one patients. There are some culturing methods consist of conventional, semiautomatic and automatic. One of automatic methods is BACTEC system worked by fluorescent technology and Co2 production of organisms in culture media. Methods: This study is based on observational-descriptive method with simple convenient sampling. We analyzed 262 samples of body sterile fluids of patients admitted in pediatric and internal wards of a university (Rasol-Acram) Hospital. They are consisting of 150 blood, 46 synovial, 32 CSF, 24 pleural, and 10 peritoneal samples. Results: There were no differences between two sex in BACTEC and Conventional methods. Average age of patients with positive and negative culture in two methods had not differences. 72 (27.5) samples were positive that 32 (12.2) samples only in BACTEC method, 4 (1.5) in conventional method and 36 (13.7) in two methods had statistical differences (p=0.003). That means positive cultures are seeing in BACTEC more than Conventional method. Comparison of two methods in positive blood culture samples had statistical differences (p=0.02) but no statistical differences in other body fluids were seen. i. e. positive cultures were seen in BACTEC more than Conventional method. Positive culture in these two methods had statistical differences in antibiotic utilization (p&lt;0.001). Positive culture in antibiotic utility were seen in BACTEC more than Conventional method. The average time of culture to become positive were 17.5+ 5.88 hours in BACTEC against 62.36+ 13.98 hours in Conventional method. Contamination was seeing in 4 samples in BACTEC and 2 in Conventional method that had no significant differences. Conclusion: According to these data organism detection in BACTEC culture media from body sterile fluids overall and specially from blood is more successful than Conventional method. It is a better method in antibiotic utilization. BACTEC can isolate organism in shorter duration than Conventional method. BACTEC can facilitate early and accurate diagnosis of infectious etiology, shorten duration of hospital stay and decrease mortality and morbidity and cost. © 2008, Tehran University of Medical Sciences. All rights reserved

    Predicting progression of mild cognitive impairment to dementia using neuropsychological data: a supervised learning approach using time windows

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    Background: Predicting progression from a stage of Mild Cognitive Impairment to dementia is a major pursuit in current research. It is broadly accepted that cognition declines with a continuum between MCI and dementia. As such, cohorts of MCI patients are usually heterogeneous, containing patients at different stages of the neurodegenerative process. This hampers the prognostic task. Nevertheless, when learning prognostic models, most studies use the entire cohort of MCI patients regardless of their disease stages. In this paper, we propose a Time Windows approach to predict conversion to dementia, learning with patients stratified using time windows, thus fine-tuning the prognosis regarding the time to conversion. Methods: In the proposed Time Windows approach, we grouped patients based on the clinical information of whether they converted (converter MCI) or remained MCI (stable MCI) within a specific time window. We tested time windows of 2, 3, 4 and 5 years. We developed a prognostic model for each time window using clinical and neuropsychological data and compared this approach with the commonly used in the literature, where all patients are used to learn the models, named as First Last approach. This enables to move from the traditional question "Will a MCI patient convert to dementia somewhere in the future" to the question "Will a MCI patient convert to dementia in a specific time window". Results: The proposed Time Windows approach outperformed the First Last approach. The results showed that we can predict conversion to dementia as early as 5 years before the event with an AUC of 0.88 in the cross-validation set and 0.76 in an independent validation set. Conclusions: Prognostic models using time windows have higher performance when predicting progression from MCI to dementia, when compared to the prognostic approach commonly used in the literature. Furthermore, the proposed Time Windows approach is more relevant from a clinical point of view, predicting conversion within a temporal interval rather than sometime in the future and allowing clinicians to timely adjust treatments and clinical appointments.FCT under the Neuroclinomics2 project [PTDC/EEI-SII/1937/2014, SFRH/BD/95846/2013]; INESC-ID plurianual [UID/CEC/50021/2013]; LASIGE Research Unit [UID/CEC/00408/2013

    Biodegradable PEG-poly(ω-pentadecalactone- co - p -dioxanone) nanoparticles for enhanced and sustained drug delivery to treat brain tumors

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    Intracranial delivery of therapeutic agents is limited by penetration beyond the blood-brain barrier (BBB) and rapid metabolism of the drugs that are delivered. Convection-enhanced delivery (CED) of drugloaded nanoparticles (NPs) provides for local administration, control of distribution, and sustained drug release. While some investigators have shown that repeated CED procedures are possible, longer periods of sustained release could eliminate the need for repeated infusions, which would enhance safety and translatability of the approach. Here, we demonstrate that nanoparticles formed from poly(ethylene glycol)-poly(u-pentadecalactone-co-p-dioxanone) block copolymers [PEG-poly(PDL-co- DO)] are highly efficient nanocarriers that provide long-term release: small nanoparticles (less than 100 nm in diameter) continuously released a radiosensitizer (VE822) over a period of several weeks in vitro, provided widespread intracranial drug distribution during CED, and yielded significant drug retention within the brain for over 1 week. One advantage of PEG-poly(PDL-co-DO) nanoparticles is that hydrophobicity can be tuned by adjusting the ratio of hydrophobic PDL to hydrophilic DO monomers, thus making it possible to achieve a wide range of drug release rates and drug distribution profiles. When administered by CED to rats with intracranial RG2 tumors, and combined with a 5-day course of fractionated radiation therapy, VE822-loaded PEG-poly(PDL-co-DO) NPs significantly prolonged survival when compared to free VE822. Thus, PEG-poly(PDL-co-DO) NPs represent a new type of versatile nanocarrier system with potential for sustained intracranial delivery of therapeutic agents to treat brain tumors
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