The effect of audio-support on strategy, time, and performance on reading comprehension in secondary school students with dyslexia.

The use of adequate reading comprehension strategies is important to read efficiently. Students with dyslexia not only read slower and less accurately, they also use fewer reading comprehension strategies. To compensate for their decoding problems, they often receive audio-support (narration written text). However, audio-support linearly guides readers from beginning to end through texts, possibly hindering the use of reading comprehension strategies in expository texts and negatively impacting reading time and reading comprehension performance. We examined to what extent audio-support affects reading comprehension strategies, reading times, and reading comprehension performance in 21 secondary school students with dyslexia and 22 typically developing controls. Participants were provided with three types of assignments (summarizing, open-ended questions, statement questions) in each condition (written text with and without audio-support). SMI RED-500 eye tracker captured eye movements during reading. The standard deviation of the weighted fixation duration times on the three paragraphs was considered indicative of the disparity of readers' attention within the text. Following a discrimination based on experts' reading behavior and hand-coded validation, these scores visualized whether students used the intensive reading strategy (reading whole text) or selective reading strategy (focusing on part of the text). In open-ended assignments, students divided their attention more over the whole text instead of focusing on one specific part when audio was added. In addition, audio-support increased reading time in students with and without dyslexia in most tasks, while in neither of the tasks audio-support affected reading comprehension performance. Audio-support impacts reading comprehension strategy and reading time in all students.

Post-treatment reading development in children with dyslexia: the challenge remains.

The goal of this study was to examine the post-treatment development of word and pseudoword accuracy and fluency and its cognitive and linguistic predictors in Dutch children with dyslexia compared with typical readers in the upper primary grades. Word and pseudoword reading accuracy and fluency were assessed at the start and end of grade 5 and at the end of grade 6. Phonological awareness, rapid naming, verbal short-term memory, vocabulary, and visual attention span were assessed at the start of grade 5. Repeated measures ANOVAs revealed that children with dyslexia were less accurate than typical readers and showed very little improvements in accuracy over time. They were also less fluent and showed less growth in reading fluency than typical readers. The children with dyslexia did improve more in word reading fluency than in pseudoword reading fluency over time. Visual attention span and phonological awareness predicted reading accuracy development in typical readers, while rapid naming predicted individual differences in reading fluency in children with dyslexia. It can be concluded that in the upper grades, children with dyslexia not only struggled with fluent reading, but they also still struggled with accurate reading in a relatively transparent orthography like Dutch, even after they had received a reading intervention to remediate their reading difficulties.

Deficient Response to Altered Auditory Feedback in Dyslexia.

Although dyslexia is characterized by a deficit in phonological representations, the nature of this deficit is debated. Previously, it was shown that adults with dyslexia respond differently to online manipulations of auditory feedback. In the present study, we found that individual differences in reading and reading-related skills within a group of 30 children (10-13 years old) with dyslexia were associated with the response to altered feedback. The fractional anisotropy of the arcuate fasciculus/superior longitudinal fasciculus was not directly related to the response to altered feedback. This study corroborates that speech perception-production communication is important for phonological representations and reading.

Neural evidence of allophonic perception in children at risk for dyslexia.

Learning to read is a complex process that develops normally in the majority of children and requires the mapping of graphemes to their corresponding phonemes. Problems with the mapping process nevertheless occur in about 5% of the population and are typically attributed to poor phonological representations, which are--in turn--attributed to underlying speech processing difficulties. We examined auditory discrimination of speech sounds in 6-year-old beginning readers with a familial risk of dyslexia (n=31) and no such risk (n=30) using the mismatch negativity (MMN). MMNs were recorded for stimuli belonging to either the same phoneme category (acoustic variants of /bə/) or different phoneme categories (/bə/ vs. /də/). Stimuli from different phoneme categories elicited MMNs in both the control and at-risk children, but the MMN amplitude was clearly lower in the at-risk children. In contrast, the stimuli from the same phoneme category elicited an MMN in only the children at risk for dyslexia. These results show children at risk for dyslexia to be sensitive to acoustic properties that are irrelevant in their language. Our findings thus suggest a possible cause of dyslexia in that they show 6-year-old beginning readers with at least one parent diagnosed with dyslexia to have a neural sensitivity to speech contrasts that are irrelevant in the ambient language. This sensitivity clearly hampers the development of stable phonological representations and thus leads to significant reading impairment later in life.

Allophonic mode of speech perception in Dutch children at risk for dyslexia: a longitudinal study.

There is ample evidence that individuals with dyslexia have a phonological deficit. A growing body of research also suggests that individuals with dyslexia have problems with categorical perception, as evidenced by weaker discrimination of between-category differences and better discrimination of within-category differences compared to average readers. Whether the categorical perception problems of individuals with dyslexia are a result of their reading problems or a cause has yet to be determined. Whether the observed perception deficit relates to a more general auditory deficit or is specific to speech also has yet to be determined. To shed more light on these issues, the categorical perception abilities of children at risk for dyslexia and chronological age controls were investigated before and after the onset of formal reading instruction in a longitudinal study. Both identification and discrimination data were collected using identical paradigms for speech and non-speech stimuli. Results showed the children at risk for dyslexia to shift from an allophonic mode of perception in kindergarten to a phonemic mode of perception in first grade, while the control group showed a phonemic mode already in kindergarten. The children at risk for dyslexia thus showed an allophonic perception deficit in kindergarten, which was later suppressed by phonemic perception as a result of formal reading instruction in first grade; allophonic perception in kindergarten can thus be treated as a clinical marker for the possibility of later reading problems.

Home literacy environment of pre-school children with intellectual disabilities.

BACKGROUND: For pre-school children, the home literacy environment (HLE) plays an important role in the development of language and literacy skills. As there is little known about the HLE of children with intellectual disabilities (ID), the aim of the present study was to investigate the HLE of children with ID in comparison with children without disabilities. METHOD: Parent questionnaires concerning aspects of the HLE were used to investigate differences between 48 children with ID, 107 children without disabilities of the same chronological age and 36 children without disabilities of the same mental age (MA). Furthermore, for the children with ID, correlations were computed between aspects of the HLE and children's non-verbal intelligence, speech intelligibility, language and early literacy skills. RESULTS AND CONCLUSIONS: From the results of the multivariate analyses of variance it could be concluded that the HLE of children with ID differed from that of children in the chronological age group on almost all aspects. When compared with children in the MA group, differences in the HLE remained. However, differences mainly concerned child-initiated activities and not parent-initiated activities. Correlation analyses showed that children's activities with literacy materials were positively related with MA, productive syntax and vocabulary age, and book orientation skills. Also, children's involvement during storybook reading was related with their MA, receptive language age, productive syntax and vocabulary age, book orientation and rapid naming of pictures. The amount of literacy materials parents provided was related to a higher productive syntax age and level of book orientation of the children. Parent play activities were also positively related to children's speech intelligibility. The cognitive disabilities of the children were the main cause of the differences found in the HLE between children with ID and children without disabilities. Parents also adapt their level to the developmental level of their child, which may not always be the most stimulating for the children.

Prevalence of herds with young sows seropositive to pseudorabies (Aujeszky's disease) in northern Belgium.

In Belgium, pseudorabies in swine has been the subject of a mandatory eradication programme since 1993. From December 1995 to February 1996, a survey was conducted in the five provinces of northern Belgium to estimate the provincial pseudorabies virus (PRV) herd seroprevalence. Seven hundred and twenty randomly selected herds were included in this survey. To detect recently infected animals, only young sows were sampled. The results show that 44% of these herds had an important number of PRV-seropositive young sows. The highest herd seroprevalence was observed in West Flanders (68%), followed by Antwerp (60%), East Flanders (43%), Limburg (18%), and Flemish Brabant (8%). Assuming a diagnostic test sensitivity and specificity of 95% and 99%, respectively, and a true PRV within-herd prevalence of 43%, the overall true PRV herd prevalence was estimated to be 35%. A logistic multiple-regression revealed that the presence of finishing pigs was associated with a two-fold increase in odds of a herd being seropositive (odds ratio (OR)=2.07, 95% confidence interval (CI) = 1.31-3.26); a breeding herd size > or =70 sows was associated with a four-fold increase in odds of a herd being seropositive (OR = 4.09, 95% CI = 2.18-7.67); a pig density in the municipality of >455 pigs/km2 was associated with a 10-fold increase in odds of a herd being seropositive (OR = 9.68, 95% CI = 5.17-18.12). No association was detected between the PRV herd seroprevalence and purchase policy of breeding pigs (purchased gilts, or use of homebred gilts only).

Clinical usefulness and safety of bronchoalveolar lavage (BAL) in elderly patients.

Little is known about the indications, safety and clinical usefulness of bronchoalveolar lavage (BAL) in elderly patients. In order to address these issues, we reviewed our last 200 consecutive BAL procedures, of which 23 (11.5%) were performed in patients older than 75 years (range 75-90, mean age 80.7 years, 13 men and 10 women). All procedures were well tolerated and no complications were observed. In 17 of the 23 patients (74%), BAL results were compatible with or diagnostic for infectious pneumonia (6 cases), idiopathic pulmonary fibrosis (5 cases), lung cancer (2 cases), hypereosinophilic syndrome (2 cases), chronic eosinophilic pneumonia (1 case) and lymphoma (1 case). In 6 of the 23 patients (26%), BAL yielded no specific diagnostic information. These data indicate that BAL is a safe procedure with a high diagnostic yield in an elderly population with pulmonary disease of unknown origin.

Leukemia and lymphoma immunophenotyping in cell smears with immunogold-silver staining.

The potential of the immunogold-silver staining (IGSS) technique for immunophenotyping leukemia and lymphoma cells in cell smears was examined. Peripheral blood, bone marrow aspirates, lymph node biopsy specimens, fine-needle aspirates, and biologic fluids of 83 patients with acute or chronic leukemias, non-Hodgkin's lymphomas, or Hodgkin's disease were labeled. Cell smears, cytocentrifuge preparations, or imprints were fixed, incubated with the reagents, and counterstained with May-Grünwald-Giemsa. Stable immunostaining and good morphologic characteristics allowed accurate cell identification and rapid enumeration of the positive cells. The immunophenotypes obtained with the use of 35 monoclonal antibodies with different specificities were similar to those determined by flow cytometry or immunohistochemical studies on the same samples. This IGSS method was especially useful for the examination of poor samples or complex cell suspensions with rare malignant cells. It could be an alternative to the immunoenzyme methods that generally are used for this purpose.

Flow cytometric immunophenotyping of leukemia cells in clotted blood and bone marrow.

Immunophenotyping of leukemia cells is generally performed on cells in suspension. These suspensions are usually prepared from anticoagulated peripheral blood or bone marrow samples but when anticoagulation is suboptimal clotted samples may reach the laboratory. In this study cell suspensions were prepared from clotted blood and bone marrow samples of leukemia patients by lysis of the clots with streptokinase. The cell suspensions were then labeled with monoclonal or polyclonal antibodies and examined by flow cytometry or fluorescence microscopy. Enough cells could be isolated from small volumes of clotted blood or bone marrow aspirate to determine the immunophenotype of the cells. The morphology of the cells was well preserved and accurate identification of the cells was possible. The immunophenotypes determined on clotted samples from four patients with acute myeloblastic leukemia, five with acute lymphoblastic leukemia and two with chronic lymphocytic leukemia were identical to those established using EDTA anticoagulated samples of the same patients. When no unclotted samples are available this approach may avoid the necessity for a new sample and the concomitant delay in treatment of the patient.

Light microscopical detection of leukocyte cell surface antigens with a one-nanometer gold probe.

The potential of ultrasmall gold particles for the light microscopical detection of leukocyte cell surface differentiation antigens was investigated. Suspensions and cytocentrifuge preparations of peripheral blood leukocytes were first incubated with monoclonal antibodies and then with goat antimouse antibodies coupled to colloidal gold particles of 1-nanometer diameter. Cytocentrifuge preparations were made from the cell suspensions. Silver enhancement was performed on all preparations. Then they were counterstained with May-Grünwald Giemsa and examined in light microscopy. The immunostaining appeared as fine dark granules on the surface membrane of the cells. Labeling conditions were determined which gave a dense specific immunostaining and a low background. High dilutions of the ultrasmall gold probe could be used to detect all antigen expressing cells in the samples. The labeling efficiency of the IGSS method with the 1 nanometer probe was comparable to that described earlier for 5 nanometer gold particles. Lymphocyte subsets enumerated with this method in normal peripheral blood were similar to those found with immunofluorescence microscopy. We concluded that one nanometer probes do not offer a major advantage in comparison with 5 nanometer probes for the study of cell surface antigens.

An immunogold-silver staining method for detection of cell surface antigens in cell smears.

We developed an indirect immunogold-silver staining method for detection of leukocyte cell surface antigens in cell smears. Air-dried and fixed cytocentrifuge preparations or smears of peripheral blood leukocytes were incubated with monoclonal antibodies (MAb) and colloidal gold-labeled secondary antibodies. The preparations were post-fixed and silver enhancement was performed. The smears were counterstained with May-Grunwald-Giemsa and examined in brightfield light microscopy. The morphology of the cells was well preserved. Leukocytes reacting with the MAb showed black granules on their surface membranes. The intense immunostaining and the low background allowed a rapid enumeration of the positive cells. The labeling could be detected with high sensitivity by epipolarization microscopy. This immunogold-silver staining method was used to quantify T- and B-lymphocytes and natural killer cells in buffy coat smears of normal adult blood. These lymphocyte subsets correlated well with those obtained in smears with the alkaline phosphatase-anti-alkaline phosphatase (APAAP) method and with those found by labeling of mononuclear cells in suspension with immunogold-silver staining. This immunogold-silver staining method forms a good alternative to immunoenzyme methods for study of hematologic cells. In addition, it could be a general procedure for detection of cell surface antigens in all kinds of cell smears.

Sensitive detection of immunogold-silver staining with darkfield and epi-polarization microscopy.

We evaluated the contribution of darkfield and epi-polarization microscopy to the detection of leukocyte cell surface antigens with immunogold-silver staining (IGSS). Lymphocyte cell surface differentiation antigens were labeled with monoclonal antibodies and IGSS as described for brightfield microscopy. In darkfield and epi-polarization microscopy the labeling appeared as bright spots on a dark background. The sensitivity of detection was much higher than that of brightfield microscopy. Sixteenfold higher dilutions of the monoclonal antibody could be used to detect all cells expressing the antigen in the cell suspension. However, non-specific staining was also better visualized. The latter could be reduced to a level comparable to that of brightfield microscopy only by use of weaker labeling conditions. A 25% reduction of the silver enhancement time was necessary for this purpose. However, these weaker labeling conditions also reduced the intensity of the specific staining. Therefore, the efficiency of IGSS, as detected with darkfield and epi-polarization microscopy, was only fourfold greater than that found with brightfield microscopy or that of an immunofluorescence procedure. Especially in combination with transmitted light, to improve cell identification, epi-polarization microscopy is a reliable and sensitive method for detection of immunogold-silver-labeled cell surface antigens for diagnostic and research purposes.

Hematologic values and lymphocyte subsets in fetal blood.

Hematologic values and lymphocyte subpopulations were determined in normal fetal blood during the second trimester of gestation. In these samples the platelet, erythrocyte, and leukocyte counts were significantly lower than in adults. Large red blood cells with a high hemoglobin content were present. Before the twentieth week of gestation, erythroblasts made up about half of the nucleated elements. Lymphocytes formed most of the leukocytes, and their absolute numbers were comparable to those in adults. Most of the fetal blood lymphocytes expressed T- or B-cell surface differentiation antigens. The percentage of T-cells was lower and that of B-cells was higher than in the adult. A high OKT4/OKT8 ratio was present. It was due to a low percentage of OKT8-positive cells. Lymphocytes with a natural killer cell phenotype were rare. Most lymphocytes were OKT10 positive, but almost none reacted with the antithymocyte antibody OKT6. These results give additional information about the development of blood cells in early human life. They can be used as reference values for the prenatal diagnosis of hereditary or acquired anomalies of the hematologic and immunologic systems.