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Biomedical subjects

P Reitsma

Publications and source records attributed to P Reitsma.

10 recordsLinked to original sources
PubMed1998

Analyzing the development of individual differences in terms of Matthew effects in reading: results from a Dutch Longitudinal study.

The Matthew effect hypothesis provides a theoretical framework to describe the development of individual differences in reading ability. The model predicts an increase of individual differences in reading. Reciprocal relationships between reading and other factors seem to cause these increasing differences. This longitudinal study of 3 years was concerned with uncovering the existence and causes of increasing individual differences in reading in the early elementary grades. Data were analyzed within a structural equation modeling framework. The results clearly indicate increasing individual differences for word recognition skills. For reading comprehension, no such effects could be established for this limited time period. More important, some evidence for interactive relationships between reading and other cognitive skills, behaviors, and motivational factors, hypothesized to cause increasing differences between readers, was found.

Child↗
PubMed1996

Effect of a whey protein concentrate used as a colostrum substitute or supplement on calf immunity, weight gain, and health.

The efficacy of a whey protein concentrate was evaluated as a colostrum substitute or supplement in two experiments using four groups of 29 calves. In Experiment 1, calves were fed either 2 L of pooled colostrum (group 1) or 500 g of whey protein concentrate (group 2). A mean total of 123.6 and 17.7 g of Ig was fed to calves in groups 1 and 2, respectively. Mean serum IgG, total protein, and globulin concentrations and Ig antibody activities to Escherichia coli K99 and rotavirus were significantly higher for calves in group 1 at 24 to 36 h and at 3 wk of age. Weight gain from birth to 3 wk of age was significantly lower for calves in group 2. The incidence of diarrhea was high but not different between treatments. The mortality rate (0 to 3 wk) was significantly higher for calves in group 2 (27.6%) than for calves in group 1 (3.4%). In Experiment 2, calves were fed either 2 L of pooled colostrum (group 3) or a solution of 1 L of pooled colostrum plus 500 g of whey protein concentrate (group 4). A mean total of 117.2 and 69.1 g of Ig was fed to calves in groups 3 and 4, respectively. Absorption rate of IgG was significantly lower for calves in group 4. Mean serum IgG, total protein, and globulin concentrations and Ig antibody activities to E. coli K99 and rotavirus were significantly higher for calves in group 3 at 24 to 36 h and at 3 wk of age. Mortality rate, BW gain, and incidence of diarrhea did not differ significantly between groups.

Animal Feed↗
PubMed1994

Processing units in word reading by disabled readers.

The article addresses the issue of whether disabled readers can be instructed to use within-word (multiletter) units. Several analogy methods were employed. In Experiments 1 and 2 short lists of words that differ in only one letter were repeatedly practiced. In Experiment 3 the subjects blended written and spoken words in which the place of segmentation was systematically manipulated. Subjects were tested in all experiments on the reading of practiced words, on nonpracticed words that orthographically as well as phonologically resemble the practiced words, and on nonpracticed nonsimilar words. The findings indicate that: (1) All types of practice were beneficial for the recognition of the practiced words. (2) Transfer to the reading of novel words appeared only when graphemic and orthographic aspects of words were strongly emphasized. (3) Transfer effects were based upon the improved handling of multiletter within-word units when word lists with auditory prompts were practiced, but on improved (single) letter-sound conversions when the analysis and synthesis of isolated words and word parts was trained. (4) At least in Dutch, segmentations according to the onset-rime principle were not more useful than segmenting written and spoken words at other boundaries.

Acoustic Stimulation↗
PubMed1993

The use of speech-based recoding in reading by prelingually deaf children.

We evaluated the extent to which prelingually deaf school children who were educated orally made functional use of speech-based codes in reading processes. The study involved two experimental reading tasks: (1) memorizing written words in association with meaning and (2) serial order recall of written word strings. The subjects were 78 school children 6 to 13 years of age. The results revealed a developmental change in the use of coding strategies: up to 9 years of age, most children seem to process written words by means of visual codes; older children tend to differentiate and appear to prefer either a visual or a speech-based strategy. The latter was found to be associated with better performance in reading tasks.

Child↗
PubMed1990

Somatic origin of inherited haemophilia A.

We found a partial deletion of the clotting factor VIII gene of about 2000 bp, spanning exon 5 and part of intervening sequence 4 and 5 in an isolated patient with severe haemophilia A. The mother of the patient, who appeared to be a non-carrier on the basis of coagulation assays and restriction fragment length polymorphism analysis in the family, turned out to be a mosaic for the deletion, not only in her germ cells, but also in various somatic cells. These findings suggest that the mutation is the result of an event in early embryogenesis. If mosaicism for a mutation, either gonadal or somatic, proves to be a common phenomenon in human genetics, it is imperative to reconsider genetic risks for (future) sibs of any apparently new mutant of a hereditary disease.

Chromosome Deletion↗
PubMed1984

Sound priming in beginning readers.

This research explored the issue of whether beginning readers proceed from print directly to meaning, as suggested by Barron and Baron , or whether it is necessary for them to use phonological information in order to obtain access to the meaning of printed words. Children between the ages of 7 and 12 were asked to make semantic interpretations from printed words. If beginning readers make use of an intermediate phonemic code in accessing the lexicon, speech sounds will affect decision times. For this reason, speech sounds were presented shortly before a visual word display. The results show that similarity between sound and the pronuciation of the word is facilitative for beginning readers (both for familiar and unfamiliar orthographies and independent of orthographic complexity) but has no effect for more fluent readers. 5 experiments to explore this phenomenon were carried out, and from the results it was concluded that at least at low levels of reading skill intermediate phonemic codes are used in lexical access.

Child↗
PubMed1983

Induction of monocytic differentiation and bone resorption by 1,25-dihydroxyvitamin D3.

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] stimulates bone resorption in man and other vertebrates, in part, by increasing the number of osteoclasts, the principal resorbing cells of bone. Because osteoclasts are very likely derived from a member(s) of the mononuclear phagocyte family, we determined if 1,25(OH)2D3 promotes maturation of these cells by studying its effects on the human promyelocytic leukemia cell line HL-60. Of the vitamin D3 metabolites tested, only 1,25(OH)2D3, at 10(-10) to 10(-7) M, induces the differentiation of HL60 into mono- and multinucleated macrophage-like cells. Phenotypic change is evident within 24 hr and reaches a plateau between 72 and 96 hr of incubation. The changes are metabolite-specific and include (i) adherence to substrate, (ii) acquisition of the morphological features of mature monocytes, (iii) a 4- to 6-fold enhancement in lysozyme synthesis and secretion, (iv) increase in the fraction of alpha-naphthyl acetate esterase-positive cells from approximately 2% to 100% of the population, and (v) the acquisition of several monocyte-associated cell surface antigens. More importantly, treated HL-60 cells acquire the capacity to bind and degrade bone matrix, two of the essential, functional characteristics of osteoclasts and related bone-resorbing cells. These results, considered together with the reported action of 1,25(OH)2D3 on nontransformed mononuclear cells, are consistent with the view that vitamin D3 enhances bone resorption and osteoclastogenesis in vivo by promoting the differentiation of precursor cells.

Animals↗
PubMedDate not supplied

Type-I protein-C deficiency caused by disruption of a hepatocyte nuclear factor (HNF)-6/HNF-1 binding site in the human protein-C gene promoter.

The level and tissue specificity of eukaryotic gene transcription is determined by the binding of specific transcription factors to DNA sequence elements located around the transcription start site. The availability and activity of specific transcription factors depends on a variety of developmental and environmental cues and, therefore, varies from cell type to cell type. For instance, liver tissue, the principal site of expression of the coagulation inhibitor protein C, expresses a heterogeneous group of transcription factors called hepatocyte nuclear factors (HNFs). Some of these HNFs are essential players in protein-C gene expression. This review discusses the significance of HNF-1 and HNF-6 in regulating the transcription of the protein-C gene and gives directions for future research.

DNA↗
PubMedDate not supplied

Effects of outpatient treatment of dyslexia.

The effects of a Dutch intervention program for dyslexia are reported. The program was individually tailored, depending on the style of reading, the phase of the learning process, and the intermediate results of the treatment. Two groups of participants were involved: (a) a group of children with pure dyslexia (n = 109) and (b) a group that had reading problems but also suffered from cognitive deficits or psychiatric symptoms (n = 29). Scores of reading single words and text at intake and after the intervention were analyzed to assess the efficacy of the intervention program. Furthermore, the effects of pre-intervention variables such as intelligence, reported speech, and language problems and of intervention variables such as the initial level of performance and the duration of the treatment were examined. Both groups benefitted from the intervention, but the children with pure dyslexia profited most. Neither of the groups could catch up the reading deficit. Intelligence and reported speech and language problems did not affect the treatment outcomes. Individual differences in treatment outcome were related to the absolute level of word reading and age at intake. In the group with comorbidity, the intervention program was more successful in relatively younger children. Within this group, the cognitive deficits and types of psychiatric problems were not related to the treatment.

Ambulatory Care↗