Carotid stenosis is one of several causes of ischemic stroke and entails a high risk of ischemic stroke recurrence. Removal of a carotid stenosis by carotid endarterectomy results in a risk reduction for ischemic stroke, but the magnitude of risk reduction depends on several factors. If the delay between the last symptom and carotid endarterectomy is less than 2 weeks, the absolute risk reduction is >10%, regardless of age, sex, or if the degree of carotid stenosis is 50–69% or 70–99%. Thus, speed is the key. However, if many patients suffers an ischemic stroke recurrence within the first 2 weeks of the presenting event, an additional benefit is likely be obtained if carotid endarterectomy is performed even earlier than within 2 week after the presenting event. Carotid endarterectomy for asymptomatic carotid stenoses carries a small risk reduction for stroke. Screening for asymptomatic carotid stenosis requires a prevalence of >5% in the examined population, i.e., higher than in the general population; however, directed screening in groups with a prevalence of >5% is beneficial. The aims of this thesis were to investigate the length of the delay to carotid endarterectomy, determine the risk of recurrent stroke before carotid endarterectomy, and determine if a calcification in the area of the carotid arteries seen on dental panoramic radiographs is a valid selection method for directed ultrasound screening to detect asymptomatic carotid stenosis. Consecutive patients with a symptomatic carotid stenosis who underwent a preoperative evaluation aimed at carotid endarterectomy at Umeå Stroke Centre between January 1, 2004–March 31, 2006 (n=275) were collected retrospectively and between August 1, 2007–December 31, 2009 (n=230) prospectively. In addition, 117 consecutive persons, all preliminarily eligible for asymptomatic carotid endarterectomy and with a calcification in the area of the carotid arteries seen on panoramic radiographs, were prospectively examined with carotid ultrasound. The median delay between the presenting event and carotid endarterectomy was 11.7 weeks in the first half year of 2004, dropped to 6.9 weeks in the first quarter year of 2006, and had dropped to 3.6 weeks in the second half year of 2009. The risk of ipsilateral ischemic stroke recurrence was 4.8% within 2 days, 7.9% within 1 week, and 11.2% within 2 weeks of the presenting event. For patients with a stroke or transient ischemic attack as the presenting event, this risk was 6.0% within 2 days, 9.7% within 1 week, and 14.3% within 2 weeks of the presenting event. For the 10 patients with a near-occlusion, the risk of ipsilateral ischemic stroke recurrence was 50% at 4 weeks after the presenting event. Among the 117 persons with a calcification in the area of the carotid arteries seen on panoramic radiographs, eight had a 50–99% carotid stenosis, equalling a prevalence of 6.8% (not statistically significantly over the pre-specified 5% threshold). Among men, the prevalence of 50–99% carotid stenosis was 12.5%, which was statistically significantly over the pre-specified 5% threshold. In conclusion: The delay to carotid endarterectomy was longer than 2 weeks. Additional benefit is likely to be gained by performing carotid endarterectomy within a few days of the presenting event instead of at 2 weeks because many patients suffer a stroke recurrence within a few days; speed is indeed the key. The finding that near-occlusion entails an early high risk of stroke recurrence stands in sharp contrast to previous studies; one possible explaination is that this was a high-risk period missed in previous studies. The incidental finding of a calcification in the area of the carotid arteries on a panoramic radiograph is a valid indication for carotid ultrasound screening in men who are otherwise eligible for asymptomatic carotid endarterectomy.

Early onset depression is associated with high recurrence rates later in life. Recurrent depressive episodes during childhood may be particularly problematic, if additional episodes have a scarring effect that hinders healthy development. Distinguishing between first onsets and recurrences has been useful in understanding adult depression. This distinction has seldom been examined in pediatric depression, in part because it is difficult to enroll adequate samples of children with recurrent depression. We conducted archival analyses of carefully-diagnosed pediatric probands with depression first onset between ages of 4 and 12. Probands who reported one depressive episode (N = 435) were compared with probands who reported two depression episodes (N = 115) on clinical (treatment, comorbidities), psychosocial (negative life events (NLEs), parental psychopathology) and emotion regulation measures. Based on previous findings in older adolescents and adults, we hypothesized that probands with two MDEs will have higher comorbidity, parental psychopathology, more NLEs, and higher maladaptive emotion regulation scale scores than probands with one MDE. Surprisingly, probands with one and two MDEs were indistinguishable on psychological and pharmacological treatment variables. As expected, probands with two MDEs had lower age of first onset, higher maladaptive emotion regulation scores, higher rates of comorbid anxiety and reported more NLEs than probands with one MDE. Probands with two MDEs also spent a longer total time in episode; group differences remained after controlling for time spent depressed. Distinguishing between first onsets and recurrences is meaningful in pediatric depression.

Temos, nagrinėjamos šioje disertacijoje, buvo doktorantūros studijų Vilniaus universiteto Matematikos ir informatikos fakultete objektas. Pateikti tyrimai yra susiję su sudėtinių skaičių egzistavimu tokiose sekose kaip fiksuoto skaičiaus laipsnių sveikųjų dalių seka bei tiesinė rekurentinė seka, sudaryta iš sveikųjų skaičių. Disertaciją sudaro įvadas, 3 skyriai, išvados ir literatūros sąrašas. Pirmame skyriuje nagrinėjami sudėtiniai skaičiai racionaliųjų skaičių laipsnių sveikųjų dalių sekoje bei yra įrodoma, kad sekoje [ξ(5/4)^n], n=1,2,..., kur ξ yra bet koks teigiamas skaičius, yra be galo daug sudėtinių skaičių. Be to, įrodoma, kad yra be galo daug tokių natūraliųjų skaičių n, kad ([ξ(5/4)^n]; 6006)>1, čia 6006 = 2•3•7•11•13. Įrodoma panašių rezultatų pastumtoms kai kurių kitų racionaliųjų skaičių sekoms. Pavyzdžiui, tas pats įrodoma sveikųjų skaičių, esančių arčiausiai ξ(5/3)^n bei ξ(7/5)^n, n=1,2,..., sekoms. Vėlgi nurodomos atitinkamos galimų daliklių aibės. Antrame skyriuje nagrinėjami sudėtiniai skaičiai antros eilės tiesinėse rekurentinėse sekose bei įrodoma, kad kiekvienai tokiai sveikųjų skaičių porai (a; b), kad b≠0 ir (a; b)≠(±2; -1), egzistuoja tokie du natūralieji tarpusavyje pirminiai skaičiai x_1, x_2, kad sekoje, apibrėžtoje lygtimi x_{n+1}=ax_n+bx_{n-1}, n=2,3,..., visų narių moduliai yra sudėtiniai skaičiai. Trečiame skyriuje egiptietiškų trupmenų kontekste nagrinėjamos skaičių, užrašomų tam tikru tiesiniu pavidalu, aibės. Ieškoma, kokie skaičiai... [toliau žr. visą tekstą] / The topics examined in this thesis were the subject of my research as a PhD student at the Faculty of Mathematics and Informatics of Vilnius University. The presented investigation concerns the existence of composite numbers in some special sequences, such as the sequence of integer parts of powers of a fixed number and a linear recurrence sequence consisting of integer numbers. The thesis consists of the introduction, 3 sections, conclusions and bibliography. In Section 1 we consider composite numbers in the sequences of integer parts of powers of rational numbers and prove that the sequence [ξ(5/4)^n], n=1,2,..., where ξ is an arbitrary positive number, contains infinitely many composite numbers. Furthermore, it is shown that there are infinitely many positive integers n such that ([ξ(5/4)^n]; 6006)>1, where 6006 = 2•3•7•11•13. Similar results are obtained for shifted powers of some other rational numbers. In particular, the same is proved for the sets of integers nearest to ξ(5/3)^n and to ξ(7/5)^n, n=1,2,.... The corresponding sets of possible divisors are also described. In Section 2 we consider composite numbers in the binary linear recurrence sequences and prove that for every pair of integer numbers (a; b), where b≠0 and (a; b)≠(±2; -1), there exist two positive relatively prime composite integers x_1, x_2 such that the sequence given by x_{n+1}=ax_n+bx_{n-1}, n=2,3,..., consists of composite terms only, i.e., the absolute value of each term is a composite integer... [to full text]

Background: New genomic tests are being developed to predict an individual’s risk of cancer recurrence by analyzing the expression of multiple genes. However, it is unclear how to report the test results so that they would be most useful to clinicians. A mail-out questionnaire has the potential to help a) describe physicians’ attitudes towards the clinical use of new genomic tests, b) determine what information physicians prefer to have included in the test reports, and c) explore how physicians think the test results would impact their treatment recommendations. Objectives: To design such a questionnaire that could be used in the eventual large-scale survey, and to ensure that the questionnaire a) is comprehensible, b) has face validity, c) appears interesting to, and d) does not place undue response burden on, the target population. Methods: The first draft, based on a specific genomic test for breast cancer recurrence (Oncotype DX) and on two case scenarios, was created. Cognitive interviews with practicing oncologists were conducted to identify problems in the questionnaire. The evaluation involved face-to-face interviews with Kingston oncologists who treat breast cancer, followed by telephone interviews with medical oncologists who treat breast cancer in other places in Ontario. Three-to-four oncologists were included in each round of interviewing after which the questionnaire was revised based on that round’s recommendations. Additional rounds of interviews were conducted until no new problems/issues were raised in one entire round. Results: A medium-length questionnaire was drafted. Four rounds of interviews were conducted with no new problems/issues being raised in the fourth round. Most of the problems identified in the questionnaire related to comprehensibility, followed by logical issues which detected fundamental problems in the questionnaire design. There was no evidence of fatigue or disinterest in participants and they deemed the response burden reasonable. Conclusion: The results suggest that the proposed questionnaire is comprehensible and has face validity. Additionally, it appears to be an interesting questionnaire to, and would not place undue burden on, the target population. Thus, the questionnaire is now ready for the field administration. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2009-05-05 17:23:10.551

The topics examined in this thesis were the subject of my research as a PhD student at the Faculty of Mathematics and Informatics of Vilnius University. The presented investigation concerns the existence of composite numbers in some special sequences, such as the sequence of integer parts of powers of a fixed number and a linear recurrence sequence consisting of integer numbers. The thesis consists of the introduction, 3 sections, conclusions and bibliography. In Section 1 we consider composite numbers in the sequences of integer parts of powers of rational numbers and prove that the sequence [ξ(5/4)^n], n=1,2,..., where ξ is an arbitrary positive number, contains infinitely many composite numbers. Furthermore, it is shown that there are infinitely many positive integers n such that ([ξ(5/4)^n]; 6006)>1, where 6006 = 2•3•7•11•13. Similar results are obtained for shifted powers of some other rational numbers. In particular, the same is proved for the sets of integers nearest to ξ(5/3)^n and to ξ(7/5)^n, n=1,2,.... The corresponding sets of possible divisors are also described. In Section 2 we consider composite numbers in the binary linear recurrence sequences and prove that for every pair of integer numbers (a; b), where b≠0 and (a; b)≠(±2; -1), there exist two positive relatively prime composite integers x_1, x_2 such that the sequence given by x_{n+1}=ax_n+bx_{n-1}, n=2,3,..., consists of composite terms only, i.e., the absolute value of each term is a composite integer... [to full text] / Temos, nagrinėjamos šioje disertacijoje, buvo doktorantūros studijų Vilniaus universiteto Matematikos ir informatikos fakultete objektas. Pateikti tyrimai yra susiję su sudėtinių skaičių egzistavimu tokiose sekose kaip fiksuoto skaičiaus laipsnių sveikųjų dalių seka bei tiesinė rekurentinė seka, sudaryta iš sveikųjų skaičių. Disertaciją sudaro įvadas, 3 skyriai, išvados ir literatūros sąrašas. Pirmame skyriuje nagrinėjami sudėtiniai skaičiai racionaliųjų skaičių laipsnių sveikųjų dalių sekoje bei yra įrodoma, kad sekoje [ξ(5/4)^n], n=1,2,..., kur ξ yra bet koks teigiamas skaičius, yra be galo daug sudėtinių skaičių. Be to, įrodoma, kad yra be galo daug tokių natūraliųjų skaičių n, kad ([ξ(5/4)^n]; 6006)>1, čia 6006 = 2•3•7•11•13. Įrodoma panašių rezultatų pastumtoms kai kurių kitų racionaliųjų skaičių sekoms. Pavyzdžiui, tas pats įrodoma sveikųjų skaičių, esančių arčiausiai ξ(5/3)^n bei ξ(7/5)^n, n=1,2,..., sekoms. Vėlgi nurodomos atitinkamos galimų daliklių aibės. Antrame skyriuje nagrinėjami sudėtiniai skaičiai antros eilės tiesinėse rekurentinėse sekose bei įrodoma, kad kiekvienai tokiai sveikųjų skaičių porai (a; b), kad b≠0 ir (a; b)≠(±2; -1), egzistuoja tokie du natūralieji tarpusavyje pirminiai skaičiai x_1, x_2, kad sekoje, apibrėžtoje lygtimi x_{n+1}=ax_n+bx_{n-1}, n=2,3,..., visų narių moduliai yra sudėtiniai skaičiai. Trečiame skyriuje egiptietiškų trupmenų kontekste nagrinėjamos skaičių, užrašomų tam tikru tiesiniu pavidalu, aibės. Ieškoma, kokie skaičiai... [toliau žr. visą tekstą]

Countries that have experienced civil war suffer a greater risk for new conflict than countries with no prior history of civil war. This empirical finding has been called a conflict trap where the legacy of previous war - unsolved issues, indecisive outcomes, and destruction – leads to renewed fighting. Yet, countries like Cambodia, El Salvador, Indonesia, and Mozambique have managed to overcome decade-long conflicts without relapse. This dissertation addresses this empirical puzzle by seeking to dismantle the conflict trap and look at microlevel explanations for civil war resolution and relapse. It adds to existing scholarship in three ways: first, by using disaggregated empirics on war termination and how fighting resumes; second, by exploring government agency in conflict processes; and third, by disaggregating rebel organizations. Essay I present original data on the start and end dates and means of termination for all armed conflicts, 1946-2005. Contrary to previous work, this data reveal that wars does not always end through victory or peace agreement, but commonly end under unclear circumstances. Essay II addresses how developments exogenous to the conflict influence governments’ decision to engage in a peace process. The results show that after natural disasters when state resources need to be allocated towards disaster relief, governments are more willing to negotiate and conclude ceasefires with insurgents. Essay III focuses on the post-conflict society, and posits that security concerns among former war participants will push them towards remobilizing into rebellion. The findings indicate that if ex-belligerent elite’s security is compromised, the parties of the previous war will resume fighting, while insecurity among former rank-and-file leads to the formation of violent splinter rebel groups. Finally, Essay IV seeks to explain why governments sometimes launch offensives on former rebels in post-conflict countries. The results show that internal power struggles provide leaders with incentives to use force against domestic third parties to strengthen their position against intra-government rivals. Taken together, this dissertation demonstrates that there is analytical leverage to be had by disaggregating the processes of violence in civil war and post-conflict societies, as well as the actors involved – both the government and rebel sides.

We present an unusual case of a late recurrent central neurocytoma that was rediagnosed as an ependymoma and neurocytoma in accordance with changes in histological classifications. Case Description. A 56-year-old male teacher presented with incomplete transverse syndrome due to several intradural extramedullary tumors at the level of lumbar vertebrae 1–3. The histological diagnosis at the time was atypical ependymoma. One year later, two additional tumors were removed at the L5-S1 vertebral level. For 12 years, the patient remained tumor free on followup. Fourteen years after the initial diagnosis, the patient presented with thoracic paresthesias due to two new extramedullary tumors in the C7-T1 and the T8-T9 vertebral levels. After complete removal of the tumors, a radiological survey revealed an intracranial lesion in the third ventricle. Five months later, an additional lesion recurrence was removed surgically. The most recent histological diagnosis revealed an atypical central neurocytoma. In retrospect, the previous tumors were reclassified as neurocytoma according to the additional immunohistochemistry evidence. Discussion. There is no standard adjuvant treatment regimen for atypical neurocytoma; therefore, the patient is currently under close followup. Modern histopathological diagnosis is essential in these cases. Potential routes for dissemination of the tumor should be considered upon first recurrence.

Objective: Primary transitional cell carcinoma (TCC) of the upper urinary tract represents 6–8% of all TCC cases. Nephroureterectomy with removal of a bladder cuff is the treatment of choice. The rates of TCC recurrence in the bladder after primary upper urinary tract surgery described in the literature range between 12.5 and 37.5%. In a retrospective analysis we examined the occurrence of TCC after nephroureterectomy for upper tract TCC in patients without a previous history of bladder TCC at the time of surgery. Methods: Between 1990 and 2002, 29 patients underwent primary nephroureterectomy for upper tract TCC. The mean age of the patients was 69.5 years. In 5 cases upper urinary tract tumors were multilocular, in the remaining cases unilocular in the renal pelvis (n = 12) or the ureter (n = 12). The follow-up was available for 29 patients with a mean follow-up of 3.37 (0.1–11.2) years. Results: 11/29 (37.9%) patients had TCC recurrence with 9/11 patients having bladder TCC diagnosed within 2.5 years (0.9–6.0) after nephroureterectomy. 13/29 patients are alive without TCC recurrence, 3/29 patients died due to systemic TCC progression and 5/29 died of unrelated causes without evidence of TCC recurrence. Conclusion: Our data indicate a high incidence of bladder TCC after nephroureterectomy for primary upper tract TCC of up to 6 years after primary surgery. Because of the high incidence of bladder TCC within the first 3 years of surgery, careful follow-up is needed over at least this period. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Objective: In this study, 22 cases of locally recurrent urological malignant fibrous histiocytoma were reviewed considering therapeutic options, follow-up and prognosis. Patients and Methods: In the available literature on this topic we identified 19 cases of locally recurrent genitourinary malignant fibrous histiocytoma. Three additional cases are discussed, primarily arising from the kidney, the bladder and the paratesticular region. Results: The prognosis of locally recurrent urological malignant fibrous histiocytoma was found to be extraordinarily poor. Only 2 of 22 patients have survived for longer than 3.5 years. One of them reported herein is still alive 10 years after extensive lymphatic spread accompanying the first local recurrence. In this case, late local recurrence occurred after an 8-year interval free of disease. Conclusion: Malignant fibrous histiocytoma is an unusual urological malignancy with a high rate of local recurrence. The latter is frequently accompanied by metastatic disease and unrelenting progression. Despite the poor prognosis early detection of local failure and aggressive salvage therapy might offer the chance of long-term survival in selected cases. Close and life-long follow-up is advisable for patients once treated for recurrent urological malignant fibrous histiocytoma. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Vienas iš būdų padėti pacientams, sergantiems kepenų navikais, yra lokalus naviko sunaikinimas radiodažnine abliacija. Pagrindine šio metodo problema išlieka aukštas naviko atkryčio dažnis. Disertacijos tikslas yra ištirti procesus, vykstančius radiodažnine abliacija paveiktame kepenų audinyje, išsiaiškinti šių procesų mechanizmus bei hipertermijos sąlygojamus pakitimus audinio, ląstelės ir subląsteliniame lygmenyje. Retrospektyviu tyrimu įvertintas pacientų, kuriems KMUK Chirurgijos klinikoje buvo atlikta kepenų navikų radiodažninė abliacija, navikų atkryčio dažnis, jo atsiradimo laikas ir veiksniai, galintys sąlygoti atkrytį. Eksperimentiškai įvertinti fizikiniai veiksniai, sąlygojantys šilumos plitimą kepenų audinyje, jų įtaka kepenų audinio pažeidimo mąstui ir tolygumui. Nustatyti morfologiniai ir biocheminiai pakitimai, vykstantys pereinamojoje kepenų audinio pažeidimo zonoje, bei šių pakitimų atsiradimo laikas. Ištirti pereinamosios kepenų audinio pažeidimo zonos hepatocitų mitochondrijų funkcijų pokyčiai ir apoptozės proceso vyksmui reikalingų energetinių resursų susidarymas, eksperimentiškai modeliuojant šios zonos temperatūrinius kitimus. Tyrimo naujumą lemia tai, kad darbe nustatyta jog apoptozės procesas pereinamoje radiodažninio pažeidimo zonoje gali būti nustatomas praėjus valandai po terminio pažeidimo. Eksperimentuose su hepatocitų mitochondrijomis nustatėme iki šiol neaprašytą neigiamą hipertermijos poveikį kepenų ląstelių mitochondrijų funkciniams rodikliams. / Radiofrequency ablation is one of the most widely accepted method for the local ablation of liver tumors. One of the negative aspects of this method is a high local recurrence rate, which is associated with the worse survival. The aim of the dissertation was to explore the processes in radiofrequency ablation affected liver tissue, ascertain the mechanisms of these processes and hyperthermia induced changes in the liver tissue, cells and subcellular level. The liver tumor recurrence rate, time and factors that could determine the recurrence were estimated using retrospective analysis of data. The physical parameters determining the spreading of the heat in liver tissue in experimental model and the influence of these parameters on extent and homogeneity of the damage were determined. The morphological and biochemical changes in the remote from the heat source zone were determined and the time of these changes was detected. The changes of liver cells mitochondria functions and the intracellular formation of energy resources necessary for these processes in subcellular level (apoptosis) were investigated simulating temperature changes in experimental model. The scientific novelty was governed by the data those support the activation of apoptotic pathway in the early period after exposure to hyperthermia. Our experimental study revealed yet unpublished data of the adverse effects of hyperthermia on the key functional parameters of the mitochondria.