Number Magnitude Processing and Verbal Working Memory in Children with Mild Intellectual Disabilities

ABSTRACT

This study examined if children (M_age = 14.60) with Mild Intellectual Disabilities (MID) display weaknesses in number processing and verbal working memory. An age-matched and mental age-matched (MA, M_age = 6.17) design extended by a group of 9–10-year-olds, and a group of 11–12-year-olds were used. The MID children’s working memory was equal to the MA group but poorer than the other groups. On number tasks, the MID group was faster than the MA group but slower than the other groups. All groups obtained equal Weber fraction scores and distance effects on the number comparison tasks. The MID group performed subitizing and counting faster than the MA group, but slower than the 11–12-year-olds. The results demonstrate that number processing and working memory in children with MID is characterized by a developmental delay, not a deficit. Their main problem is to access the quantitative meaning of Arabic numerals. The development of different types of cognitive abilities is differently affected by educational experience and intellectual ability. The innate number system appears to be unaffected by intellectual capacity or educational experience, while the innate working memory ability is affected by intellectual capacity but not by educational experience. Culturally acquired symbolic number abilities are strongly affected by educational experience.     

Adaptive Wiener Filtering for Improved Acquisition of Distortion Product Otoacoustic Emissions

An innovative acoustic noise canceling method using adaptive Wiener filtering (AWF) was developed for improved acquisition of distortion product otoacoustic emissions (DPOAEs). The system used one microphone placed in the test ear for the primary signal. Noise reference signals were obtained from three different sources: (a) pre-stimulus response from the test ear microphone, (b) post-stimulus response from a microphone placed near the head of the subject and (c) post-stimulus response obtained from a microphone placed in the subjects nontest ear. In order to improve spectral estimation, block averaging of a different number of single sweep responses was used. DPOAE data were obtained from 11 ears of healthy newborns in a well-baby nursery of a hospital under typical noise conditions. Simultaneously obtained recordings from all three microphones were digitized, stored and processed off-line to evaluate the effects of AWF with respect to DPOAE detection and signal-to-noise ratio (SNR) improvement. Results show that compared to standard DPOAE processing, AWF improved signal detection and improved SNR. © 1998 Biomedical Engineering Society. PAC98: 4364Jb, 4360-c, 8790+y     

Knowledge about asthma and COPD: associations with sick leave, health complaints, functional limitations, adaptation, and perceived control

We sought to investigate associations between knowledge about the disease and sick leave, health complaints, functional limitations, adaptation and perceived control. Patients with asthma (n = 101) and COPD (n = 64) underwent lung function tests and completed questionnaires. In addition, all were asked the question: ‘what is the diagnosis of your disease?’, with the response categories: ‘asthma’ and ‘COPD (chronic bronchitis or emphysema)’. Thirty-five percent of the asthma patients and 30% of the COPD patients did not know their correct diagnosis. Sick leave was not associated with knowledge about the disease in asthma and COPD. In asthma, much knowledge about management of the disease was associated with better adaptation (P = 0.01) and less perceived control over health by external factors (P = 0.02). Knowing the correct diagnosis was associated with less control over health by powerful others (P = 0.02). For COPD, more knowledge about management of the disease was associated with better adaptation (P = 0.02) and less control over health by internal factors (P = 0.01). Knowing the correct diagnosis was associated with less control over dyspnea at work (P = 0.01).     

Interlaboratory validation of a CD71-based flow cytometric method (Microflow) for the scoring of micronucleated reticulocytes in mouse peripheral blood

An interlaboratory study was performed to validate an anti-CD71/flow cytometry-based technique for enumerating micronucleated reticulocytes (MN-RETs) in mouse peripheral blood. These experiments were designed to address International Workshop on Genotoxicity Test Procedures validation criteria by evaluating the degree of correspondence between MN-RET measurements generated by flow cytometry (FCM) with those obtained using traditional microscopy-based methods. In addition to these cross-methods data, flow cytometric MN-RET measurements for each blood sample were performed at two separate sites in order to evaluate the reproducibility of data between laboratories. In these studies, groups of male CD-1 mice were treated with vehicle (saline or vegetable oil), a negative control (saline or vegetable oil), or four dose levels of five known genotoxicants (clastogens: cyclophosphamide, benzo[a]pyrene, 5-fluorouracil, methotrexate; aneugen: vincristine sulfate). Exposure occurred on 3 consecutive days via intraperitoneal injection, and blood samples were obtained approximately 24 hr after the final treatment. MN-RET frequencies were determined for each sample based on the analysis of 2,000 (microscopy) and 20,000 (FCM) reticulocytes. Regardless of the method utilized, each genotoxic agent was observed to cause statistically significant increases in the frequency of MN-RETs, and each response occurred in a dose-dependent manner. Spearman's correlation coefficient (rs) for FCM versus microscopy-based MN-RET measurements (nine experiments, 252 paired measurements) was 0.740, indicating a high degree of correspondence between methods. The rs value for all flow cytometric MN-RET measurements performed at the two independent sites was 0.857 (n = 248), suggesting that the automated method is highly transferable between laboratories. Additionally, the flow cytometric system offered advantages relative to microscopy-based scoring, including a greater number of cells analyzed, much faster analysis times, and a greater degree of objectivity. Collectively, data presented in this report suggest that the overall performance of mouse peripheral blood micronucleus tests is enhanced by the use of the flow cytometric scoring procedure.     

Decreased phenylalanine uptake and turnover in patients with vitiligo

The human epidermis has the full machinery for autocrine L-phenylalanine turnover to L-tyrosine in keratinocytes and melanocytes. Phenylalanine hydroxylase (PAH) activities increase linearly with inherited skin colour (skin phototype I-VI, Fitzpatrick classification) yielding eightfold more activities in black skin compared to white skin. Moreover, UVB irradiation (1 MED) significantly increases epidermal PAH activities 24 h after exposure. Importantly, L-phenylalanine uptake and turnover in the pigment forming melanocytes is vital for initiation of melanogenesis. In this context it was shown that the uptake of this amino acid is regulated by calcium. The depigmentation disorder vitiligo provides a unique model to follow impaired L-phenylalanine turnover in the skin as well as in serum because affected individuals hold an impaired epidermal 6BH4 de novo synthesis/recycling and regulation including low epidermal PAH activities. After overnight fasting and oral loading with L-phenylalanine (100 mg/kg body weight), 29.6% of 970 patients tested (n=287/970) yielded serum phenylalanine/tyrosine ratios >or=4 and 35.3% (n=342/970) had mild to moderate hyperphenylalaninaemia (HPA), while 9.3% (n=90/970) had both serum L-phenylalanine levels >or=2.0 mg/dl and phe/tyr ratios >or=4.0. Isolated HPA was found in 26% (n=252/970), whereas 20.3% had only increased ratios (n=197/970). None of the patients had phenylketonuria and the family history for this metabolic disease was negative. The IQ followed normal Gaussian distribution. In vitro L-phenylalanine uptake/turnover studies on primary epidermal melanocytes originating from these patients demonstrated a significantly decreased calcium dependent L-phenylalanine uptake and turnover compared to healthy control cells. Based on our observation, we would like to propose that phenylalanine uptake/turnover is under tight control by calcium which in turn could offer an additional novel mechanism in the aetiology of HPA.     

Renin gene and angiotensin II AT1 receptor gene expression in the kidneys of normal and of two-kidney/one-clip rats

This study aimed to investigate the inter-relation between the angiotensin II (ANG II) AT₁ receptor and renin gene expression in rat kidneys. To this end, renin mRNA levels and mRNA levels for AT_1a and AT_1b were assayed by RNase protection in the kidneys of normal rats, in animals treated with the AT₁ antagonist losartan and in rats bearing 0.2-mm left renal artery clips for 2 days. In normal rats, we found a negative correlation between renin mRNA levels and AT_1a receptor mRNA levels. Losartan led to a fourfold increase in renin mRNA levels without changing AT₁ receptor mRNA levels. Unilateral renal artery clipping increased renin mRNA levels fourfold in the clipped kidney and suppressed renin mRNA levels in the contralateral kidneys. AT₁ receptor mRNA levels were not changed in the contralateral intact kidneys, but were significantly decreased by 15–25% in the clipped kidneys. Renin mRNA levels were inversely correlated to AT_1a mRNA levels in the clipped, but not in the contralateral, kidneys. Our findings suggest that the systemic activity of the renin angiotensin system has no regulatory influence on renal AT₁ receptor gene expression. Renin mRNA levels in normal and in clipped kidneys appear to be negatively determined by the level of AT_1a receptor gene expression. Thus modulation of AT_1a receptor gene expression could be a pathway for indirect modulation of renin gene expression by ANG II. This conclusion is in agreement with the observation that AT₁ receptor antagonists are powerful stimulators of the renin system.     

CDK9/CYCLIN T1 expression during normal lymphoid differentiation and malignant transformation

CDK9 is a member of the CDC2-like family of kinases. Its cyclin partners are members of the CYCLIN T family (T1, T2a, and T2b) and CYCLIN K. The CDK9/CYCLIN T1 complex is very important in the differentiation programme of several cell types, controlling specific differentiation pathways. Limited data are available regarding the expression of CDK9/CYCLIN T1 in haematopoietic and lymphoid tissues. The aim of this study was to analyse the expression of the CDK9/CYCLIN T1 complex in lymphoid tissue, in order to assess its role in B- and T-cell differentiation and lymphomagenesis. CDK9/CYCLIN T1 expression was found by immunohistochemistry in precursor B and T cells. In peripheral lymphoid tissues, germinal centre cells and scattered B- and T-cell blasts in interfollicular areas expressed CDK9/CYCLIN T1, while mantle cells, plasma cells, and small resting T-lymphocytes displayed no expression of either molecule. CDK9/CYCLIN T1 expression therefore appears to be related to particular stages of lymphoid differentiation/activation. CDK9 and CYCLIN T1 were highly expressed in lymphomas derived from precursor B and T cells, from germinal centre cells, such as follicular lymphomas, and from activated T cells (ie anaplastic large cell lymphomas). Hodgkin and Reed-Sternberg cells of classical Hodgkin's lymphoma also showed strong nuclear staining. Diffuse large B-cell, Burkitt's lymphomas, and peripheral T-cell lymphomas, among T-cell lymphoproliferative disorders, showed a wide range of values. No expression of CDK9 or CYCLIN T1 was detected in mantle cell and marginal zone lymphomas. However, at the mRNA level, an imbalance in the CDK9/CYCLIN T1 ratio was found in follicular lymphoma and diffuse large B-cell lymphomas with germinal centre phenotype, and in the cell lines of classical Hodgkin's lymphomas, Burkitt's lymphomas, and anaplastic large cell lymphoma, in comparison with reactive lymph nodes. These results suggest that the CDK9/CYCLIN T1 complex may affect the activation and differentiation programme of lymphoid cells. The molecular mechanism through which the CDK9/CYCLIN T1 complex is altered in malignant transformation needs to be elucidated.