Karolinska Institutet

About: Karolinska Institutet is a education organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Population & Cancer. The organization has 46212 authors who have published 121142 publications receiving 6008130 citations.

The Swedish mutation causes early-onset Alzheimer's disease by beta-secretase cleavage within the secretory pathway.

Abstract: Several missense mutations causing early-onset Alzheimer's disease (AD) have been described in the gene coding for the beta-amyloid precursor protein (beta APP). A double mutation found in a Swedish family is located before the amyloid beta-peptide (A beta) region of beta APP and results in the increased production and secretion of A beta. Here we show that the increased production of A beta results from a cellular mechanism, which differs substantially from that responsible for the production of A beta from wild-type beta APP. In the latter case, A beta generation requires reinternalization and recycling of beta APP. In the case of the Swedish mutation the N-terminal beta-secretase cleavage of A beta occurs in Golgi-derived vesicles, most likely within secretory vesicles. Therefore, this cleavage occurs in the same compartment as the alpha-secretase cleavage, which normally prevents A beta production, explaining the increased A beta generation by a competition between alpha- and beta-secretase.

Associations of Breast Cancer Risk Factors With Tumor Subtypes: A Pooled Analysis From the Breast Cancer Association Consortium Studies

Abstract: BACKGROUND: Previous studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors. METHODS: We pooled tumor marker and epidemiological risk factor data from 35,568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies. All statistical tests were two-sided. RESULTS: In case-case analyses, of the epidemiological risk factors examined, early age at menarche (≤12 years) was less frequent in case patients with PR(-) than PR(+) tumors (P = .001). Nulliparity (P = 3 × 10(-6)) and increasing age at first birth (P = 2 × 10(-9)) were less frequent in ER(-) than in ER(+) tumors. Obesity (body mass index [BMI] ≥ 30 kg/m(2)) in younger women (≤50 years) was more frequent in ER(-)/PR(-) than in ER(+)/PR(+) tumors (P = 1 × 10(-7)), whereas obesity in older women (>50 years) was less frequent in PR(-) than in PR(+) tumors (P = 6 × 10(-4)). The triple-negative (ER(-)/PR(-)/HER2(-)) or core basal phenotype (CBP; triple-negative and cytokeratins [CK]5/6(+) and/or epidermal growth factor receptor [EGFR](+)) accounted for much of the heterogeneity in parity-related variables and BMI in younger women. Case-control analyses showed that nulliparity, increasing age at first birth, and obesity in younger women showed the expected associations with the risk of ER(+) or PR(+) tumors but not triple-negative (nulliparity vs parity, odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.75 to 1.19, P = .61; 5-year increase in age at first full-term birth, OR = 0.95, 95% CI = 0.86 to 1.05, P = .34; obesity in younger women, OR = 1.36, 95% CI = 0.95 to 1.94, P = .09) or CBP tumors. CONCLUSIONS: This study shows that reproductive factors and BMI are most clearly associated with hormone receptor-positive tumors and suggest that triple-negative or CBP tumors may have distinct etiology.

Dose-dependent risk of malformations with antiepileptic drugs: an analysis of data from the EURAP epilepsy and pregnancy registry.

Abstract: Summary Background Prenatal exposure to antiepileptic drugs is associated with a greater risk of major congenital malformations, but there is inadequate information on the comparative teratogenicity of individual antiepileptic drugs and the association with dose. We aimed to establish the risks of major congenital malformations after monotherapy exposure to four major antiepileptic drugs at different doses. Methods The EURAP epilepsy and pregnancy registry is an observational cohort study representing a collaboration of physicians from 42 countries. We prospectively monitored pregnancies exposed to monotherapy with different doses of four common drugs: carbamazepine, lamotrigine, valproic acid, or phenobarbital. Our primary endpoint was the rate of major congenital malformations detected up to 12 months after birth. We assessed pregnancy outcomes according to dose at the time of conception irrespective of subsequent dose changes. Findings After excluding pregnancies that ended in spontaneous abortions or chromosomal or genetic abnormalities, those in which the women had treatment changes in the first trimester, and those involving other diseases or treatments that could affect fetal outcome, we assessed rates of major congenital malformations in 1402 pregnancies exposed to carbamazepine, 1280 on lamotrigine, 1010 on valproic acid, and 217 on phenobarbital. An increase in malformation rates with increasing dose at the time of conception was recorded for all drugs. Multivariable analysis including ten covariates in addition to treatment with antiepileptic drugs showed that the risk of malformations was greater with a parental history of major congenital malformations (odds ratio 4·4, 95% CI 2·06–9·23). We noted the lowest rates of malformation with less than 300 mg per day lamotrigine (2·0% [17 events], 95% CI 1·19–3·24) and less than 400 mg per day carbamazepine (3·4% [5 events], 95% CI 1·11–7·71). Compared with lamotrigine monotherapy at doses less than 300 mg per day, risks of malformation were significantly higher with valproic acid and phenobarbital at all investigated doses, and with carbamazepine at doses greater than 400 mg per day. Interpretation The risk of major congenital malformations is influenced not only by type of antiepileptic drug, but also by dose and other variables, which should be taken into account in the management of epilepsy in women of childbearing potential. Funding Eisai, GlaxoSmithKline, Janssen-Cilag, Novartis, Pfizer, Sanofi-Aventis, UCB, Netherlands Epilepsy Foundation, Stockholm County Council, and ALF.

Prognostic subgroups in B-cell chronic lymphocytic leukemia defined by specific chromosomal abnormalities.

Abstract: Background and methods Specific chromosomal abnormalities have been shown to affect the overall survival of patients with acute leukemia, but the possibility that specific chromosomal defects may influence the course of B-cell chronic lymphocytic leukemia (CLL) is controversial. We assessed this possibility as follows: blood mononuclear cells from 433 patients with B-cell CLL in five European centers were cultured with B-cell mitogens, and banded metaphases were studied. Results Three hundred ninety-one patients could be evaluated cytogenetically, and 218 had clonal chromosomal changes. The most common abnormalities were trisomy 12 (n = 67) and structural abnormalities of chromosome 13 (n = 51; most involving the site of the retinoblastoma gene) and of chromosome 14 (n = 41). Patients with a normal karyotype had a median overall survival of more than 15 years, in contrast to 7.7 years for patients with clonal changes. Patients with single abnormalities (n = 113) did better than those with complex karyotypes (P less than 0.001). Patients with abnormalities involving chromosome 14q had poorer survival than those with aberrations of chromosome 13q (P less than 0.05). Among patients with single abnormalities, those with trisomy 12 alone had poorer survival than patients with single aberrations of chromosome 13q (P = 0.01); the latter had the same survival as those with a normal karyotype. A high percentage of cells in metaphase with chromosomal abnormalities, indicating highly proliferative leukemic cells, was associated with poor survival (P less than 0.001). Cox proportional-hazards analysis identified age, sex, the percentage of cells in metaphase with chromosomal abnormalities, and the clinical stage of the disease (Binet classification system) as independent prognostic variables. Conclusions Chromosomal analysis provides prognostic information about overall survival in addition to that supplied by clinical data in patients with B-cell CLL.