Showing papers by "Anders Björklund published in 2007"

Dopamine released from 5-HT terminals is the cause of L-DOPA-induced dyskinesia in parkinsonian rats.

Abstract: In patients with Parkinson’s disease, the therapeutic efficacy of L-DOPA medication is gradually lost over time, and abnormal involuntary movements, dyskinesias, gradually emerge as a prominent side-effect in response to previously beneficial doses of the drug. Here we show that dyskinesia induced by chronic L-DOPA treatment in rats with 6 -hydroxydopamine-induced lesions of the nigrostriatal dopamine pathway is critically dependent on the integrity and function of the serotonergic system. Removal of the serotonin afferents, or dampening of serotonin neuron activity by 5 -HT1A and 5 -HT1B agonist drugs, resulted in a near-complete block of the L-DOPA-induced dyskinesias, suggesting that dysregulated dopamine release from serotonin terminals is the prime trigger of dyskinesia in the rat Parkinson’s disease model. In animals with complete dopamine lesions, the spared serotonin innervation was unable to sustain the therapeutic effect of L-DOPA, suggesting that dopamine released as a ‘false transmitter’ from serotonin terminals is detrimental rather than beneficial.The potent synergistic effect of low doses of 5 -HT1A and 5 -HT1B agonists to suppress dyskinesia, without affecting the antiparkinsonian effect of L-DOPA in presence of spared dopamine terminals, suggests an early use of these drugs to counteract the development of dyskinesia in Parkinson’s disease patients.

Serotonin neuron transplants exacerbate L-DOPA-induced dyskinesias in a rat model of Parkinson's disease.

Abstract: Clinical trials in patients with Parkinson's disease have shown that transplants of fetal mesencephalic dopamine neurons can form a new functional innervation of the host striatum, but the clinical benefits have been highly variable: some patients have shown substantial recovery in motor function, whereas others have shown no improvement and even a worsening in the 3,4-dihydroxyphenyl-L-alanine (L-DOPA)-induced dyskinetic side effects. Differences in the composition of the grafted cell preparation may contribute to these discrepancies. In particular, the number of serotonin neurons contained in the graft can vary greatly depending on the dissection of the fetal tissue. Importantly, serotonin neurons have the ability to store and release dopamine, formed from exogenously administered L-DOPA. Here, we have evaluated the effect of transplants containing serotonin neurons, or a mixture of dopamine and serotonin neurons, on L-DOPA-induced dyskinesias in 6-hydroxydopamine-lesioned animals. As expected, dopamine neuron-rich grafts induced functional recovery, accompanied by a 60% reduction in L-DOPA-induced dyskinesia that developed gradually over the first 10 weeks. Rats with serotonin-rich grafts with few dopamine neurons, in contrast, showed a progressive worsening of their L-DOPA-induced dyskinesias over time, and no functional improvement. The antidyskinetic effect of dopamine-rich grafts was independent of the number of serotonin neurons present. We conclude that serotonin neurons in the grafts are likely to have a detrimental effect on L-DOPA-induced dyskinesias in cases in which the grafts contain no or few dopamine neurons.

Family structure and child outcomes in the USA and Sweden

Abstract: Previous research shows that living in a non-intact family is associated with educational disadvantages. This paper compares the relationships between childhood family structure, schooling, and earnings in Sweden and the USA. This comparison is interesting because both family structure and public policies differ significantly. We find a negative relationship between living in a non-intact family and child outcomes, and the estimates are remarkably similar in both countries. After using sibling-difference models, the correlation with family structure is no longer significant. These results cast doubt on the causal interpretation of the negative relationship between non-intact family structures and child outcomes.

In vitro characterization of a human neural progenitor cell coexpressing SSEA4 and CD133.

Abstract: The stage-specific embryonic antigen 4 (SSEA4) is commonly used as a cell surface marker to identify the pluripotent human embryonic stem (ES) cells. Immunohistochemistry on human embryonic central nervous system revealed that SSEA4 is detectable in the early neuroepithelium, and its expression decreases as development proceeds. Flow cytometry analysis of forebrain-derived cells demonstrated that the SSEA4-expressing cells are enriched in the neural stem/progenitor cell fraction (CD133(+)), but are rarely codetected with the neural stem cell (NSC) marker CD15. Using a sphere-forming assay, we showed that both subfractions CD133(+)/SSEA4(+) and CD133(+)/CD15(+) isolated from the embryonic forebrain are enriched in neurosphere-initiating cells. In addition CD133, SSEA4, and CD15 expression is sustained in the expanded neurosphere cells and also mark subfractions of neurosphere-initiating cells. Therefore, we propose that SSEA4 associated with CD133 can be used for both the positive selection and the enrichment of neural stem/progenitor cells from human embryonic forebrain.

Nature and Nurture in the Intergenerational Transmission of Socioeconomic Status: Evidence from Swedish Children and Their Biological and Rearing Parents

Abstract: This study uses an extraordinary Swedish data set to explore the sources of the intergenerational transmission of socioeconomic status. Merging data from administrative sources and censuses, we investigate the association between sons’ and daughters’ socioeconomic outcomes and those of their biological and rearing parents. Our analysis focuses on children raised in six different family circumstances: raised by both biological parents, raised by the biological mother without a stepfather, raised by the biological mother with a stepfather, raised by the biological father without a stepmother, raised by the biological father with a stepmother, and raised by two adoptive parents. Relative to the existing literature, the most remarkable feature of our data set is that it contains information on the biological parents even when they are not the rearing parents. We specify a simple additive model of pre-birth (including genetic) and post-birth influences and examine the model’s ability to provide a unified account of the intergenerational associations in all six family types. Our results suggest substantial roles for both pre-birth and post-birth factors.

Nature and Nurture in the Intergenerational Transmission of Socioeconomic Status: Evidence from Swedish Children and Their Biological and Rearing Parents

Abstract: This study uses an extraordinary Swedish data set to explore the sources of the intergenerational transmission of socioeconomic status. Merging data from administrative sources and censuses, we investigate the association between sons' and daughters' socioeconomic outcomes and those of their biological and rearing parents. Our analysis focuses on children raised in six different family circumstances: raised by both biological parents, raised by the biological mother without a stepfather, raised by the biological mother with a stepfather, raised by the biological father without a stepmother, raised by the biological father with a stepmother, and raised by two adoptive parents. Relative to the existing literature, the most remarkable feature of our data set is that it contains information on the biological parents even when they are not the rearing parents. We specify a simple additive model of pre-birth (including genetic) and post-birth influences and examine the model's ability to provide a unified account of the intergenerational associations in all six family types. Our results suggest substantial roles for both pre-birth and post-birth factors.

The Functional Impact of the Intrastriatal Dopamine Neuron Grafts in Parkinsonian Rats Is Reduced with Advancing Disease

Abstract: Clinical trials involving intrastriatal transplants of human embryonic mesencephalic tissue have provided proof-of-principle that nigral dopamine (DA) neurons can survive and functionally integrate into the host neural circuitry. However, the degree of graft-induced symptomatic relief differs significantly between the patients. This variability has led to investigations aimed at identifying factors that could affect the clinical outcome. The extent and pattern of dopaminergic denervation in the brain may be one of the major determinants of the functional outcome after intrastriatal DA cell grafts. Here, we report that in animals subjected to an intrastriatal 6-hydroxydopamine lesion of the striatal dopaminergic afferent, the integrity of the host dopaminergic innervation outside the areas innervated by the graft is critical for optimal function of DA neurons placed in the striatum. Established graft-induced functional recovery, as assessed in the stepping and cylinder tests, was compromised in animals in which the dopaminergic lesion was extended to include also the medial and ventral striatum as well as the cortical and limbic DA projections. Poor clinical outcome after transplantation may, thus, at least in part, be caused by dopaminergic denervation in areas outside the graft-innervated territories, and similarly beneficial effects initially observed in patients may regress if the degeneration of the host extrastriatal DA projection systems proceeds with advancing disease. This would have two implications: first, patients with advanced disease involving the ventral striatum and/or nonstriatal DA projections would be unlikely to respond well to intrastriatal DA grafts and, second, to retain the full benefit of the grafts, progression of the disease should be avoided by, for example, combining cell therapy with a neuroprotective approach.

Interindustry Wage Differentials and Unobserved Ability: Siblings Evidence from Five Countries

Abstract: We examine the role of unobserved ability in explaining interindustry wage differentials. By using data on brothers, we account for unmeasured abilities shared by siblings. The data came from four Nordic countries and the United States. In the Nordic countries, only a moderate proportion of the variability in industry wages can be attributed to unobserved ability, while unmeasured factors explain as much as half of the U.S. industry-wage variation. Accounting for such differences, we show that the U.S. interindustry wage dispersion is similar with that in the Nordic countries.

Nature and Nurture in the Intergenerational Transmission of Socioeconomic Status: Evidence from Swedish Children and Their Biological and Rearing Parents

Abstract: Nature and Nurture in the Intergenerational Transmission of Socioeconomic Status: Evidence from Swedish Children and Their Biological and Rearing Parents

Does Marriage Matter for Children? Assessing the Causal Impact of Legal Marriage

Abstract: This paper examines whether parental marriage confers educational advantages to children relative to cohabitation. We exploit a dramatic marriage boom in Sweden in late 1989 created by a reform of the Widow’s Pension System that raised the attractiveness of marriage compared to cohabitation to identify the effect of marriage. Sweden’s rich administrative data sources enable us to identify the children who were affected by parental marriage due to this marriage boom. Our analysis addresses the policy relevant question whether marginal marriages created by a policy initiative have an impact on children. Using grade point average at age 16 as the outcome variable, we first confirm the expected pattern that children with married parents do better than children with cohabiting parents. However, once we control for observable family background, or use instrumental-variables estimation to compare the outcomes for those children whose parents married due to the reform with those children whose parents remained unmarried, the differences disappeared. A supplementary sibling difference analysis also supports the conclusion that the differentials among children of married and cohabiting parents reflect selection rather than causation.

Family Background and Income During the Rise of the Welfare State: Brother Correlations in Income for Swedish Men Born 1932-1968

Abstract: The goal of this study is to examine trends in the importance of family background in determining adult income in Sweden. We investigate whether the association between family background and income in Sweden has changed for cohorts born 1932-1968. Our main finding is that the share of the variance in long-run income that is attributable to family background, the so-called brother correlation in income, has fallen by some 11 percentage points from 0.34 for the cohorts of brothers born in the early 1930s to below 0.23 for the cohorts born around 1950. From then on, the correlations have been more or less stable and are in line with earlier estimates. When we adjust income for the income return to years of schooling, we find constant brother correlations in income. The main effect is coming from changes in the distribution of schooling across cohorts. This finding is consistent with the hypothesis that education policies have been a key factor in equalizing life chances in Sweden.

Family Background and Outcomes Later in Life: A (Partial and Personal) Survey of Recent Research Using Swedish Register Data

Abstract: Family Background and Outcomes Later in Life: A (Partial and Personal) Survey of Recent Research Using Swedish Register Data

Family Background and Income during the Rise of the Welfare State: Brother Correlations in Income for Swedish Men Born 1932-1968

Abstract: The goal of this study is to examine trends in the importance of family background in determining adult income in Sweden. We investigate whether the association between family background and income in Sweden has changed for cohorts born 1932-1968. Our main finding is that the share of the variance in long-run income that is attributable to family background, the so-called brother correlation in income, has fallen by some 11 percentage points from 0.34 for the cohorts of brothers born in the early 1930s to below 0.23 for the cohorts born around 1950. From then on, the correlations have been more or less stable and are in line with earlier estimates. When we adjust income for the income return to years of schooling, we find constant brother correlations in income. The main effect is coming from changes in the distribution of schooling across cohorts. This finding is consistent with the hypothesis that education policies have been a key factor in equalizing life chances in Sweden.

Globaliseringens motståndare: Mexikos Zapatister som fall av kontrahegemoni i det globala civila samhället

Abstract: Den 1 januari 1994, samma dag som den Mexikanska staten blev medlem i frihandelsavtalet NAFTA, kunde man hora ett ?iYa Basta!? runt om i delstaten Chiapas i sydostra Mexiko. Denna uppsats behandlar den Zapatistiska motstandsrorelsen utifran gramsciansk och neogramsciansk teoribildning for att forklara deras kamp som en reaktion pa den radande neoliberalistiska ekonomiska globaliseringen. Genom att studera deras ideologi och handlingar sa menar vi att de utgor en del av ett kontrahegemoniskt motstand belaget inom den nya globala anti-globaliseringsrorelsen som i sin tur utgor en del av det globala civila samhallet. Zapatisternas struktur och metod har, som ett resultat av den ekonomiska globaliseringen, omvandlats och anpassat sig for att kunna fora sin kamp och visa pa att alternativ till neoliberalismen existerar.