Insights from research on children with a familiar risk for dyslexia

Al langer is bekend dat dyslexie in families voorkomt. Kinderen met een ouder met dyslexie hebben een grotere kans om ook lees- en spellingproblemen te ontwikkelen. In familiaire risico (FR) studies naar dyslexie worden kinderen met familiair risico op dyslexie voor langere tijd gevolgd. Dergelijke studies geven interessante inzichten over de oorzaken en ontwikkeling van dyslexie. In Nederland is recent een grootschalige FR-studie afgerond, het Dutch Dyslexia Program. In deze bijdrage gaan we in op de bevindingen die dit onderzoek heeft opgeleverd op een tweetal terreinen. In de eerste plaats zijn er bevindingen over de verschillen tussen FR- kinderen met en zonder dyslexie, en controle kinderen zonder familiair risico. Zoals verwacht, hadden de FR-kinderen met dyslexie een achterstand op een scala aan leesgerelateerde cognitieve factoren. Interessant was dat ze ook een wat hoger familiair risico hadden dan de FR-kinderen zonder dyslexie: hun ouders lazen nog wat slechter. De FR-kinderen zonder dyslexie hadden milde problemen met lezen en spellen en een kleine achterstand op de voorlopers van het lezen. Het tweede terrein betreft bevindingen over de invloed van FR op de ontwikkeling van geletterdheid, technisch en begrijpend lezen. Kinderen werden gevolgd vanaf 4-jarige leeftijd tot ongeveer 12 jaar, halverwege groep 8. In longitudinaal perspectief had een familiair risico een negatieve invloed op de ontwikkeling van technisch en begrijpend lezen. De invloed op technisch lezen liep gedeeltelijk via de voorlopers van het lezen, maar daar kwam nog een direct effect bij. Onverwacht, bleek familiair risico ook een direct effect op begrijpend lezen in groep 8 te hebben. Familiair risico had geen effect op de ontwikkeling van de woordenschat, naast technisch lezen de andere pijler van begrijpend lezen. De theoretische en praktische betekenis van deze bevindingen worden besproken

Individual human serum differs in the amount of antibodies with affinity for pig fetal ventral mesencephalic cells and the ability to lyse these cells by complement activation

Xenografting pig fetal ventral mesencephalic (pfVM) cells to repair the dopamine deficit in patients with Parkinson's disease is the focus of both experimental and clinical investigations. Although there have been marked advances in the experimental and even clinical application of these xenogeneic transplantations, questions regarding the host's xenospecific immune response remain unanswered. It has been shown that human serum is able to lyse pfVM tissue by both anti-gal-gal and non-anti-gal-gal antibodies by complement activation. The aim of this study was to investigate whether interindividual differences exist in the levels of pfVM cell-specific IgM and IgG subclass antibodies, their ability to lyse pfVM cells in vitro and the relationship between both. Pig fetal VM cells were incubated with heat-inactivated serum from 10 different individuals and binding of IgM antibodies and IgG subclass antibodies to pfVM cells was analyzed by flow cytometry. The ability to lyse pfVM cells was analyzed exposing Cr-51-labeled pfVM cells to fresh serum or isolated IgM and IgG from the same individuals and subsequent determination of released Cr-51 from lysed cells. Strong differences were found between individuals in the levels of pfVM cell-specific IgM antibodies: antibody levels differed up to 40-fold. pfVM-specific IgG1 and IgG2 levels were only detectable in a few individuals. The ability to lyse pfVM cells ranged from negligible lysis up to 66.5% specific lysis. There was a strong correlation between the levels of individual pfVM-specific IgM antibodies and the ability to lyse pfVM cells in vitro. Isolated IgM, but not IgG, was able to lyse pfVM cells in the presence of complement. In conclusion, the interindividual differences in the levels of IgM with affinity for pfVM cells and their ability to lyse pfVM cells in vitro are considerable. Only few individuals possessed IgG1 and IgG2 subclass antibodies with affinity for pfVM. These findings may influence patient selection for porcine transplants and chances of graft survival in individual patients

Acquiring reading and vocabulary in Dutch and English: the effect of concurrent instruction

To investigate the effect of concurrent instruction in Dutch and English on reading acquisition in both languages, 23 pupils were selected from a school with bilingual education, and 23 from a school with education in Dutch only. The pupils had a Dutch majority language background and were comparable with regard to social-economic status (SES). Reading and vocabulary were measured twice within an interval of 1 year in Grade 2 and 3. The bilingual group performed better on most English and some of the Dutch tests. Controlling for general variables and related skills, instruction in English contributed significantly to the prediction of L2 vocabulary and orthographic awareness at the second measurement. As expected, word reading fluency was easier to acquire in Dutch with its relatively transparent orthography in comparison to English with its deep orthography, but the skills intercorrelated highly. With regard to cross-linguistic transfer, orthographic knowledge and reading comprehension in Dutch were positively influenced by bilingual instruction, but there was no indication of generalization to orthographic awareness or knowledge of a language in which no instruction had been given (German). The results of the present study support the assumption that concurrent instruction in Dutch and English has positive effects on the acquisition of L2 English and L1 Dutch