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Well-defined Population (well-defined + population)
Selected AbstractsTime Trends in Incidence, Mortality, and Case-Fatality after First Episode of Status EpilepticusEPILEPSIA, Issue 8 2001Giancarlo Logroscino Summary: ,Purpose: Status epilepticus (SE) is a medical emergency associated with a high mortality. Clinical series have suggested that mortality after SE has decreased. No studies have systematically examined trends in incidence, mortality, and case fatality after SE in a well-defined population. Methods: All first episodes of SE receiving medical attention between January 1, 1935, and December 31, 1984, were ascertained through the Rochester Epidemiology Project Records-Linkage System and followed up until death or study termination (February 1, 1996). We calculated incidence rates in the 50-year period (1935,1984), while we considered mortality and case-fatality in the last 30-year period (1955,1984). Results: Incidence of SE increased over time to 18.1/100,000 (1975 through 1984). The increase was related to an increased incidence in the elderly and to the advent of myoclonic SE after cardiac arrest, a condition not seen in the early decades. In the last decade, ,16% of the incidence was due to myoclonic SE. The mortality rates increased from 3.6 per year in the decade 1955,1965 to 4.0/100,000 per year between 1975 and 1984. The 30-day case-fatality (CF) was unchanged, although a trend toward improvement was shown after excluding myoclonic SE. Conclusions: Incidence and mortality rates of SE have increased in the last 30 years. Case fatality remained the same. The increased incidence and mortality are due to the occurrence in the last decade of myoclonic SE after cardiac arrest. The mortality in the elderly was twice that of the youngest age group, across all study periods. Changes in the age and cause distribution of SE over time are responsible for the stable survivorship. There is improvement in survivorship in the last decade when myoclonic SE is excluded. [source] Non-participation and adjustment for bias in case,control studies of periodontitisEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2008Rodrigo López Periodontal researchers frequently use case,control studies, but information on participation rates and the reasons for participation are often missing in the publications, thus hindering the assessment of the validity of those studies. A nested case,control study based on a well-defined population was used to (i) describe the patterns of participation; (ii) show how some associations can be biased; and (iii) illustrate how inverse probability weights can be applied to reduce bias. Differential subject participation was quantified using the ratio between participation for each level and the overall participation. Possible biased associations were illustrated using the odds ratios found for eligible and participant subjects. Finally, we used the estimated probability that an individual participates in the case,control study conditional on that individual's covariate pattern, as observed in the screening study to attempt bias reduction. Considerable differential participation was observed for selected factors, including age, annual tuitions and fees, parental income, and parental education. The strategy used for adjustment of bias resulted in some degree of bias reduction. These findings challenge the inferential validity of many studies on periodontitis. The design and conduct of these studies should aim to improve subject participation and must consider and minimize this potential source of bias. [source] Aplasia Cutis Congenita in a Defined Population from Northwest SpainPEDIATRIC DERMATOLOGY, Issue 6 2006Soledad Martinez-Regueira M.D. It may occur as an isolated defect or associated with other anomalies. This study sought to determine the frequency of this condition over a 10-year-period at the single hospital for a well-defined population. A literature review of potential mechanisms implicated in the development of this condition was also conducted. A retrospective review of all case records of patients diagnosed with aplasia cutis congenita between January 1994 and December 2003 at Hospital Xeral-Calde, in the Lugo region of northwest Spain was undertaken. During the period of study four patients were diagnosed with this condition. Three of them were of the gypsy race. These three had aplasia cutis congenita associated with epidermolysis bullosa and deformed nails. The incidence of aplasia cutis congenita in our region was 2.8 cases per 10,000 newborns. It was found that the incidence of this disorder in northwest Spain was similar to that described in the literature. Careful study due to the frequent association of aplasia cutis congenita with other congenital anomalies and a complete obstetric and family history of all affected individuals are required to identify possible specific teratogens, intrauterine infections, chromosomal abnormalities, or history of this condition among relatives. [source] Phenotypic variation during cloning procedures: Analysis of the growth behavior of clonal cell linesBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2006Louise M. Barnes Abstract The production of recombinant protein from mammalian cells is a key feature of the biotechnology industry. However, the generation of recombinant mammalian cell lines is still largely performed on an empirical basis and there are many potential areas for enhancement. We have shown previously that despite two rounds of limiting dilution cloning (LDC) of recombinant cell lines, there remained a high degree of heterogeneity in the resulting cell lines. We suggested that a rapid phenotypic drift occurred with these cells. It was unclear if this was a consequence of the added burden of production of a recombinant protein, the selection procedures, or merely an inherent feature of cell growth in culture. To address this, we have subjected untransfected (parental) cells to three successive rounds of LDC and monitored the growth properties of the resultant cells. The results show that despite repeated rounds of cloning, it was not possible to obtain phenotypically similar cell lines. We also demonstated that this phenotypic drift is not due to gross changes in the protein p27, a key regulators of the cell cycle. Although cells with a range of growth properties were observed even after three rounds of cloning, the variation in growth patterns between cell lines decreased after cloning. Hence, we suggest that by cloning it may be possible to generate untransfected cells, which have particular growth properties. Starting with a well-defined population of parental cells may aid in the subsequent generation of tranfectants with desired growth properties. © 2006 Wiley Periodicals, Inc. [source] Renal oncocytoma: a clinicopathological analysis of 45 consecutive casesBJU INTERNATIONAL, Issue 9 2005Tomas Gudbjartsson OBJECTIVE To evaluate the clinical behaviour and pathology of renal oncocytoma in a well-defined population over a 30-year period. PATIENTS AND METHODS In a retrospective population-based study we assessed relevant clinical and pathological factors in 45 patients (31 men and 14 women) diagnosed with renal oncocytoma in Iceland between 1971 and 2000. Clinical presentation, pathology, survival and causes of death were evaluated. RESULTS The age-standardized incidence was 0.3 per 100 000 per year for both men and women, the incidence of oncocytomas being 5.5% of renal cell carcinomas (RCCs) diagnosed during the same period in Iceland. Fourteen patients were diagnosed at autopsy for an unrelated disease. Of 31 living patients (mean age 70.5 years), seven were diagnosed incidentally (23%), and the others had presented with haematuria (32%), abdominal pain (29%), and weight loss (10%). All the patients had a radical nephrectomy, except for one with bilateral oncocytoma who had a partial nephrectomy. The mean (range) tumour size was 5.7 (0.9,12) cm. Eighteen patients (58%) were diagnosed at Tumour-Node-Metastasis stage I, 10 at stage II (32%) and three at stage III (10%), all of those at stage III having renal capsular penetration or tumour invasion into perirenal fat tissue (T3aN0M0). No patients were diagnosed with lymph node or distant metastasis. Two cases of coexisting RCC were detected. After a median follow-up of 8.3 years there were no recurrences or deaths from oncocytoma (100% disease-specific survival). The overall 5-year survival was 63%, with most patients dying from cardiovascular diseases or nonrenal cancers. CONCLUSIONS In most cases renal oncocytoma behaves like a benign tumour; the long-term prognosis is excellent. Thus, in the present patients, radical nephrectomy could be regarded as an over-treatment and nephron-sparing surgery as more appropriate, especially in patients with small tumours. However, both coexisting RCC and perirenal fat invasion, a hallmark of malignant behaviour, might indicate that more radical surgery is warranted in some of these patients. [source] Change in sex ratio, disease course and age at diagnosis in Oslo MS patients through seven decadesACTA NEUROLOGICA SCANDINAVICA, Issue 2009E. G. Celius Objectives , To study changes in sex ratio, disease course, time from onset to diagnosis and age at diagnosis by year of birth in a well-defined population of multiple sclerosis (MS) patients. Materials and methods , Based on the Oslo MS Registry patients born from 1910 to 1980 with residence in Oslo at time of diagnosis were studied. Data were analyzed by 10-year intervals based on year of birth. Results , The female to male ratio increased significantly from 1.48 to 2.30 through seven decades. Also, the ratio of initial relapsing,remitting (RR-MS) to primary progressive (PP-MS) disease course increased significantly from 1.93 to 16.00. The time from onset to diagnosis and the mean age at diagnosis declined significantly during the same period. Conclusions , This study shows that there has been a change in MS sex ratio, disease course and age at diagnosis through a period of seven decades, suggesting an environmental factor mainly affecting women at a younger age and causing a RR-MS disease course. [source] | ||||||||||