The distribution of the residual lifetime and its applications

Ankara : Department of Industrial Engineering and Institute of Engineering and Sciences, Bilkent Univ., 1991.Thesis (Master's) -- Bilkent University, 1991.Includes bibliographical references.Let T be a continuous positive random variable representing the lifetime of an entitle This entity could be a human being, an animal or a plant, or a component of a mechanical or electrical system. For nonliving objects the lifetime is defined as the total amount of time for which the entitj'^ carries out its function satisfactoriljc The concept of aging involves the adverse effects of age such as increased probability of failure due to wear. In this thesis, we consider certain characteristics of the residual lifetime distribution at age t, such as the mean, median, and variance, as descril)ing aging. The following families of statistical distributions are studied from this point of view: 1. Gamma with two parameters, 2. Weil^ull with two paxameters, .3. Lognormal with two parameters, 4. Inverse Poljmomial with one parameter. Gamma and Weil)ull distrilDutions are fitted to actual data.Çağlar, Mine AlpM.S

Menstrual cycle variability of ca 72-4 in healthy women

Objectives: CA 72-4 is not approved as a tumormarker but has been used as an adjunct marker in gynecological practice. The study aims to evaluate the menstrual cycle variability of CA 72-4 in a population of healthy women. Design and methods: Forty apparently healthy regularly menstruating subjects were included in the crosssectional study designed in the University Obstetrics and Gynecology outpatient clinic. Venous blood samples from each participant were collected twice: first at the follicular phase (2nd–5th days of the menstrual cycle) for FSH, estradiol, CA 125, CA 72-4 and the other at the luteal phase (21st-24th days of the menstrual cycle) for progesterone, CA 125 and CA 72-4 levels. Results: CA 72-4 values were similar in follicular and luteal phase of the menstrual cycle in apparently healthy regularly menstruating subjects (1.15 U/mL (0.2–5.4) vs 1.15 U/mL (0.56–6.3); p= 0.326 respectively). Ovulatory or smoking status did not have an effect on CA 72-4 values (p N 0.05). Conclusion: This first clinical study about the menstrual cycle variability of CA 72-4 revealed that the menstrual cycle does not have a significant impact on CA 72-4 values and that it can be measured at any time during the menstrual period

Deformable MRI fusion for intracranial SRS: Can we trust?

Purpose/Objective: The aim of this study is to evaluate the reliability of MRI fusion for the determination of target volume when performing CT based intracranial stereotactic radiosurgery. Materials and Methods: Patients treated with CT based intracranial stereotactic radiosurgery with various diagnoses are included in the study. All patients were immobilized using stereotactic thermoplastic masks prior to simulation. The planning CT was obtained both with and without iv contrast with 1mm slice thickness

Clinical diagnosis and complications of paratubal cysts: review of the literature and report of uncommon presentations

Paraovarian or paratubal cysts (PTCs) constitute about 10 % of adnexial masses. Although they are not uncommon; they rarely cause symptoms and are usually incidentally found. Actual incidence is not known. The symptoms occur when they grow excessively, or in case of hemorrhage, rupture or torsion. Here, literature review reporting the incidence, presentation and complications of PTCs is performed. Uncommon presentations of PTCs in three different cases, a giant PTC, torsion of PTC and borderline paratubal tumor, are also reported and discussed. Ultrasonography, CT or MRI may be performed in preoperative evaluation; but none of these imaging techniques have specific criteria for diagnosis. So, in most cases misdiagnosis as an ovarian mass remains to be a problem. Paratubal cysts can become extremely big before causing symptoms. Torsion is another urgent issue regarding PTCs, necessiating urgent surgery for preservation of the ovary and the tube. Although malignancy is rare, borderline paratubal tumors have been reported in the literature

The association between ischemia modified albumin and placental histopathology in uncomplicated term deliveries

Ischemia modified albumin (IMA) is a marker of ischemia elevated in different clinical conditions and its use for hypoxia in perinatology is of current interest. We aimed to investigate the association between maternal and cord blood IMA levels and placental histopathological findings in uncomplicated term deliveries. In this study, placental histopathological evaluation in uncomplicated deliveries that ended with healthy newborns revealed 80.6% vasculopathy. The results support the hypothesis that hypoxia exceeding the placental reserve ends with fetal compromise. Moreover, the presence of maternal vasculopathy in placenta is not correlated with maternal and fetal IMA levels

Atherogenic dyslipidemia, subclinical atherosclerosis, non-alcoholic fatty liver disease and insulin resistance in polycystic ovarian syndrome

Objective: We aimed to explore the relationship between insulin resistance (IR) and small dense lipoprotein (sd-LDL) particles, carotid intima-media thickness (CIMT) and non-alcoholic fatty liver disease (NAFLD) in young normal weight PCOS cases. Methods: This prospective, case-control study was designed in a University Hospital and 34 women with PCOS and 21 healthy controls were enrolled. Fasting plasma glucose, insulin, lipid (including sd-LDL particles) and hormone profiles, abdominal ultrasound and CIMT were evaluated. Results: IR was present in 68% of PCOS group while in none of controls. High density lipoprotein (HDL), very low density lipoprotein (VLDL), triglycerides (TG), and sd-LDL were higher in patients with IR (p<0.05). A positive correlation of sd-LDL with IR, VLDL and TG was found. A significantly higher rate of NAFLD and CIMT was found in PCOS. Totaltestosterone levels were weakly and positively correlated with CIMT (r=0.277, p=0.041). Conclusion: Insulin resistance and NAFLD are highly prevalent among young normal weight PCOS patients. When compared to controls levels of sd-LDL and CIMT are increased in PCOS. Insulin resistance is the key parameter for NAFLD and atherogenic dyslipidemia in PCOS. Hence, screening for NAFLD may be valuable for detection and prevention of liver disease. Higher levels of sd-LDL in insülin resistant PCOS cases necessiates treating PCOS for I

CRP at early follicular phase of menstrual cycle can cause misinterpretation for cardiovascular risk assessment

Objective: C-reactive protein (CRP) is a well-known marker of infl ammation and infection in clinical practice. This study is designed to evaluate CRP levels in diff erent phases of menstrual cycle, which might end up with misleading conclusions especially when used for cardiovascular risk assessment. Methods: Twenty-seven women were eligible for the cross-sectional study. Venous blood samples from each participant were collected twice during the menstrual cycle. The fi rst sampling was held at 2nd to 5th days of the menstrual cycle for FSH, estradiol, CRP, and sedimentation, and the second was done at 21st to 24th days of the menstrual cycle for measurement of progesterone, CRP, and sedimentation values. Results: CRP values were signifi cantly higher in the early follicular phase compared to luteal phase (1.8 mg/L [0.3–7.67] vs. 0.7 mg/L [0.1–8.3], p < 0.001, respectively). In both phases of the menstrual cycle, sedimentation rate was similar (12.1 ± 6.7 vs. 12.3 ± 7.7; p = 0.717, respectively). Conclusions: CRP levels in early follicular phase of the menstrual cycle (menstruation) are signifi cantly higher than CRP levels in luteal phase of the same cycle. In reproductive age women, detection of CRP for cardiovascular risk assessment during menstruation might not be appropriate

İleri yaşta dehidroepiandrosteron ile spontan gebelik: üç olgu sunumu ve literatür derlemesi

It has been reported recently that dehydroepiandrosterone (DHEA) supplementation in older patients with low ovarian reserve increases the response to infertility treatment. Three women of age >3S years with low ovarian reserve parameters including high FSH, low AFC have been treated with DHEA for various time intervals are reported here. They conceived spontaneously after a few months of treatment which resulted in healthy newborns. Although there are not many randomized controlled trials about the value of DHEA treatment in infertile patient population, previous case reports support that DHEA increases spontaneous pregnancy rates. Considering healthy livebirths of the relatively older age of the mentioned cases, DHEA might be improving also oocyte quality as an additional impact.Son yıllarda dehidroepiandrosteronun düşük over rezervli hasta grubunda infertilite tedavisine yanıtı arttırdığı saptanmıştır. Bu olgu serisinde, 35 yaşından büyük ve kötü over rezervi, yüksek 3. gün FSH’sı ve düşük antral folikül sayısı ile kanıtlanmış üç hastada kısa süreli dehidroepiandrosteron kullanımı ile spontan gelişen ve sağlıklı biçimde terme ulaşan gebelik olguları ve bu konudaki güncel literatür bilgileri gözden geçirilmektedir. Dehidroepiandrosteron ile yapılan çok geniş randomize çalışmalar bulunmasa da literatürdeki olgu sunumları ve burada sunulan vakalar, bu androjenin düşük over rezervli hastalarda spontan gebelik şansını arttırdığını kanıtlamaktadır. Gebeliklerin ileri anne yaşına rağmen sağlıklı canlı doğum ile sonuçlanmaları da oosit kalitesini iyileştirdiği fikrini desteklemektedir