Search PubMed⌕ Search

Biomedical subjects

A Reis

Publications and source records attributed to A Reis.

At least 109 records · Page 6Linked to original sources
PubMed2000

Language processing modulated by literacy: a network analysis of verbal repetition in literate and illiterate subjects.

Previous behavioral and functional neuroimaging data indicate that certain aspects of phonological processing may not be acquired spontaneously, but are modulated by learning an alphabetic written language, that is, learning to read and write. It appears that learning an alphabetic written language modifies the auditory-verbal (spoken) language processing competence in a nontrivial way. We have previously suggested, based on behavioral and functional neuroimaging data, that auditory-verbal and written language interact not only during certain language tasks, but that learning and developing alphabetic written language capacities significantly modulates the spoken language system. Specifically, the acquisition of alphabetic orthographic knowledge has a modulatory influence on sublexical phonological processing and the awareness of sublexical phonological structure. We have suggested that developing an orthographic representation system for an alphabetic written language, and integrating a phoneme-grapheme correspondence with an existing infrastructure for auditory-verbal language processing, will result in a modified language network. Specifically, we suggest that the parallel interactive processing characteristics of the underlying language-processing brain network differ in literate and illiterate subjects. Therefore, the pattern of interactions between the regions of a suitably defined large-scale functional-anatomical network for language processing will differ between literate and illiterate subjects during certain language tasks. In order to investigate this hypothesis further, we analyzed the observed covariance structure in a PET data set from a simple auditory-verbal repetition paradigm in literate and illiterate subjects, with a network approach based on structural equation modeling (SEM). Based on a simple network model for language processing, the results of the present network analysis indicate that the network interactions during word and pseudoword repetition in the illiterate group differ, while there were no significant differences in the literate group. The differences between the two tasks in the illiterate group may reflect differences in attentional modulation of the language network, executive aspects of verbal working memory and the articulatory organization of verbal output. There were no significant differences between the literate and illiterate group during word repetition. In contrast, the network interactions differed between the literate and illiterate group during pseudoword repetition. In addition to differences similar to those observed in the illiterate group between word and pseudoword repetition, there were differences related to the interactions of the phonological loop between the groups. In particular, these differences related to the interaction between Broca's area and the inferior parietal cortex as well as the posterior-midinsula bridge between Wernicke's and Broca's area. In conclusion, the results of this network analysis are consistent with our previously presented results and support the hypothesis that learning to read and write during childhood influences the functional architecture of the adult human brain. In particular, the basic auditory-verbal language network in the human brain is modified as a consequence of acquiring orthographic language skills.

Adult↗
PubMed1999

Mutation in the betaA3/A1-crystallin encoding gene Cryba1 causes a dominant cataract in the mouse.

During the mouse ENU mutagenesis screen, mice were tested for the occurrence of dominant cataracts. One particular mutant was discovered as a progressive opacity (Po). Heterozygotes show opacification of a superficial layer of the fetal nucleus, which progresses and finally forms a nuclear opacity. Since the homozygotes have already developed the total cataract at eye opening, the mode of inheritance is semidominant. Linkage analysis was performed using a set of genome-wide microsatellite markers. The mutation was mapped to chromosome 11 distal of the marker D11Mit242 (9.3 +/- 4.4 cM) and proximal to D11Mit36 (2.3 +/- 2.3 cM). This position makes the betaA3/A1-crystallin encoding gene Cryba1 an excellent candidate gene. Mouse Cryba1 was amplified from lens mRNA. Sequence analysis revealed a mutation of a T to an A at the second base of exon 6, leading to an exchange of Trp by Arg. Computer analysis predicts that the fourth Greek key motif of the affected betaA3/A1-crystallin will not be formed. Moreover, the mutation leads also to an additional splicing signal, to the skipping of the first 3 bp of exon 6, and finally to the deletion of the Trp residue. Both types of mRNA are present in the homozygous mutant lenses. The mutation will be referred to as Cryba1(po1). This particular mouse mutation provides an excellent animal model for a human congenital zonular cataract with suture opacities, which is caused by a mutation in the homologous gene.

Amino Acid Sequence↗
PubMed1999

Envoplakin, a possible candidate gene for focal NEPPK/esophageal cancer (TOC): the integration of genetic and physical maps of the TOC region on 17q25.

Focal nonepidermolytic palmoplantar keratoderma (NEPPK), or tylosis, is an autosomal, dominantly inherited disorder of the skin that manifests as focal thickening of the palmar and plantar surfaces. In three families studied, the skin disorder cosegregates with esophageal cancer and oral lesions. New haplotype analysis, presented here, places the tylosis esophageal cancer (TOC) locus between D17S1839 and D17S785. Envoplakin (EVPL) is a protein component of desmosomes and the cornified envelope that is expressed in epidermal and esophageal keratinocytes and has been localized to the TOC region. Mutation analysis of EVPL in the three affected families failed to show tylosis-specific mutations, and haplotype analysis of three intragenic sequence polymorphisms of the EVPL gene placed it proximal to D17S1839. Confirmation of the exclusion of EVPL as the TOC gene by location was obtained by integration of the genetic and physical mapping data using radiation hybrid, YAC, BAC, and PAC clones. This new physical map will allow further identification of candidate genes underlying NEPPK associated with esophageal cancer, which may also be implicated in the development of sporadic squamous cell esophageal carcinoma and Barrett's adenocarcinoma.

Base Sequence↗
PubMed1999

A genome-wide search for linkage to asthma. German Asthma Genetics Group.

Asthma is among the most frequent chronic diseases in childhood. Although numerous environmental risk factors have already been identified, the basis for familial occurrence of asthma remains unclear. Previous genome screens for atopy in British/Australian families and for asthma in different American populations showed inconsistent results. We report a sib pair study of a sample of 97 families, including 415 persons and 156 sib pairs. Following an extensive clinical evaluation, all participants were genotyped for 351 polymorphic dinucleotide markers. Linkage analysis for asthma identified four chromosomal regions that could to be linked to asthma: chromosome 2 (at marker D2S2298, P = 0.007), chromosome 6 (around D6S291, lowest P = 0.008), chromosome 9 (proximal to D9S1784, P = 0.007), and chromosome 12 (D12S351, P = 0.010). These linkage regions could be reproduced for all loci by analysis of total or specific immunoglobulin E (minimum P values at these regions were 0. 003, 0.001, 0.010, and 0.015, respectively).

Asthma↗
PubMed1999

Evaluation of a putative major susceptibility locus for juvenile myoclonic epilepsy on chromosome 15q14.

Juvenile myoclonic epilepsy (JME) is a genetically determined common subtype of idiopathic generalized epilepsy (IGE). Significant evidence for linkage has been reported for a susceptibility locus for JME in the chromosomal region 15q14 that harbors the gene encoding the alpha7 subunit of the neuronal nicotinic acetylcholine receptor (CHRNA7). The present study was designed to test the earlier linkage finding and to explore whether this susceptibility locus is involved in the epileptogenesis of a broader spectrum of IGE syndromes. Multipoint parametric and nonparametric linkage analyses with seven microsatellite polymorphisms encompassing the region of the CHRNA7 gene were performed using two diagnostic schemes of JME-related traits in two groups of multiplex families ascertained through probands with either JME (n = 27) or idiopathic absence epilepsy (n = 30). The present linkage study failed to replicate evidence for a major susceptibility locus for JME in the region encompassing the CHRNA7 gene. In addition, we found no hint in favor of linkage to 15q14 under the broad diagnostic scheme in any of the sets of families. If genetic variation in this region confers susceptibility to JME, then its effect size might be too small or its occurrence too rare to be detected in the investigated families.

Adolescent↗
PubMed1999

Nijmegen breakage syndrome: consequences of defective DNA double strand break repair.

The autosomal recessive genetic disorder, Nijmegen Breakage Syndrome, is characterised by an excessively high risk for the development of lymphatic tumours and an extreme sensitivity towards ionising radiation. The most likely explanation for these characteristics, a deficiency in the repair of DNA lesions, has been greatly substantiated by the recent cloning of the gene mutated in Nijmegen Breakage Syndrome patients and the analysis of its protein product, nibrin. The direct involvement of this protein in the processing of DNA double strand breaks caused by ionising radiation and those also necessary for normal DNA metabolism can be correlated with many of the cellular and clinical aspects of the disease, including the cancer predisposition of patients and their heterozygous relatives.

Amino Acid Sequence↗
PubMed1999

Effective auditory-verbal encoding activates the left prefrontal and the medial temporal lobes: A generalization to illiterate subjects.

Recent event-related FMRI studies indicate that the prefrontal (PFC) and the medial temporal lobe (MTL) regions are more active during effective encoding than during ineffective encoding. The within-subject design and the use of well-educated young college students in these studies makes it important to replicate these results in other study populations. In this PET study, we used an auditory word-pair association cued-recall paradigm and investigated a group of healthy upper middle-aged/older illiterate women. We observed a positive correlation between cued-recall success and the regional cerebral blood flow of the left inferior PFC (BA 47) and the MTLs. Specifically, we used the cued-recall success as a covariate in a general linear model and the results confirmed that the left inferior PFC and the MTL are more active during effective encoding than during ineffective encoding. These effects were observed during encoding of both semantically and phonologically related word pairs, indicating that these effects are robust in the studied population, that is, reproducible within group. These results generalize the results of Brewer et al. (1998, Science 281, 1185-1187) and Wagner et al. (1998, Science 281, 1188-1191) to an upper middle aged/older illiterate population. In addition, the present study indicates that effective relational encoding correlates positively with the activity of the anterior medial temporal lobe regions.

Aged↗
PubMed1999

Beneficial effect of preoperative mycophenolate mofetil in murine corneal transplantation.

To investigate the effect of preoperative mycophenolate mofetil (MMF) on allograft survival in a murine corneal transplantation model. Corneal grafting was performed from Brown Norway to Lewis rats. Groups were divided as follows: Rats that received syngeneic or allogeneic grafts without therapy served as controls. MMF treatment was either started 7 days prior to transplantation and continued for 14 postoperative days (POD) or started at the day of corneal grafting until POD 14. MMF (20 mg/kg) administered postoperatively had no significant beneficial effect on corneal graft survival when compared with controls. However, the group receiving 40 mg/kg MMF postoperatively showed a statistically significant prolonged graft survival. A 1-week preoperative administration of 20 mg/kg MMF allowed superior graft survival. Priming the immune system of corneal transplant recipients preoperatively with MMF proved to be a beneficial therapeutic regimen for prolonging corneal allograft survival in rats.

Animals↗
PubMed1999

Cola drinks consumption and oesophagitis.

For oesophageal epithelial changes to develop from gastro-oesophageal reflux disease (GORD), the character of the refluxate must be acid enough to cause injury. Experimentally, copious perfusion of the oesophagus with weak acid is quite harmless. However, hydrochloric acid alone with a pH below 3.0 may cause oesophageal injury. Cola drinks are strongly acidic (pH 2.5). This study analyses the influence of and possible interaction between cola consumption and oesophagitis. Twenty rats were divided into two groups of 10. The animals received saline (pH 7.0) or cola (pH 2.6) per OS with 24 h free access to these solutions. After the experiment the oesophagus was dissected. The mucosa was macroscopically and histopathologically examined, and flow cytometric analysis was used to look for proliferative activity. The histopathological analysis showed that there is no difference between saline and cola. But the findings of cell cycle analysis showed that the effects of cola and saline in inducing oesophageal mucosal damage are different. In the cola group the values were G0/G1, 7.33 +/- 2.88; S, 29.88 +/- 2.88; G2/M, 0.10 +/- 0.01; PI (proliferative-regenerative index), 29.76 +/- 2.88. The rat cell population g0/g1 phases were found to be low (p < 0.01), and the cell population S and PI phases were found to be significantly elevated compared with the control group (p < 0.01). (G0/G1, 79.30 +/- 5.97; S, 16.06 +/- 8.27; G2/M, 4.66 +/- 4.03; PI, 20.03 +/- 6.01). These results were reflected in the proliferative index, which is used as a measure of the regeneration index. The data show that cola has proliferative and regenerative effects on the oesophageal mucosa, and it is possible that its regenerative effect is caused as a result of an irritant effect.

Animals↗
PubMed1999

Influence of learning to read and write on the morphology of the corpus callosum.

Variations in the individual anatomy of the corpus callosum have been reported in several conditions. There seem to be genetic influencing factors, but it is impossible to rule out some environmental ones. This study focuses on the question of the environmental factors, using formal learning to read and write as the main difference in the groups to be compared. Based on magnetic resonance imaging sagital images, the contour of the corpus callosum (CC) of 41 carefully selected women (18 illiterate and 23 literate) was digitized. The comparison between the two groups showed a small difference in the region of the CC where parietal fibres are thought to cross. This region is thinner in illiterate subjects. As illiteracy in this group is the result of social constraints, and the two groups that were compared are well matched for other cultural and pragmatic aspects than literacy, the results are interpreted as showing the possible influence of formal learning to read and write, on the biological development of the brain.

Aged↗
PubMed1999

[Mycophenolate mofetil after penetrating high risk keratoplasty. A pilot study].

AIM: Mycophenolate mofetil (MMF, CellCept) has become a successful part of the standard immunosuppression regimes after solid organ transplantation. It was the aim of this study to compare the efficacy and the safety of MMF after penetrating high-risk keratoplasty with our standard immunosuppression, i.e. systemic cyclosporin A (CSA), in a pilot study. PATIENTS AND METHODS: Sixteen patients after penetrating high-risk keratoplasty were randomized to be treated either with MMF or with CSA for six months postoperatively. MMF was administered in an oral dose of two times 1 g daily whereas the CSA dose varied according to the blood trough levels of 120-150 ng/ml (monoclonal TDx) between 100 and 500 mg daily. RESULTS: During this first follow-up period of 11.4 (5-18) months neither in the MMF- nor in the CSA-group irreversible graft failure was observed. One serious acute endothelial immune reaction was observed in the CSA-group after systemic immunomodulation had been tapered. It was treated successfully with systemic and topical corticosteroids. In one patient CSA-prophylaxis had to be stopped five months postoperatively because of elevated liver enzymes. Side-effects did not occur in the MMF-group. CONCLUSIONS: Up to now MMF has been evaluated to be as efficacious as CSA and safe. If these results are confirmed in the long run in this study MMF may become an armament to avoid immune reactions in high-risk penetrating keratoplasty patients who must not receive systemic CSA.

Cyclosporine↗
PubMed1999

Hereditary isolated renal magnesium loss maps to chromosome 11q23.

Hypomagnesemia due to isolated renal magnesium loss has previously been demonstrated in two presumably unrelated Dutch families with autosomal dominant mode of inheritance. Patients with magnesium deficiency may suffer from tetany and convulsions, but the patients with hereditary renal magnesium wasting can also be clinically nonsymptomatic. In a genomewide linkage study, we first excluded a possible candidate region, on chromosome 9q, that encompasses the gene for intestinal hypomagnesemia with secondary hypocalcemia and, subsequently, found linkage to markers on chromosome 11q23. Detailed haplotype analyses identified a common haplotype segregating in both families, suggesting both their relationship through a common ancestor and the existence of a single, hypomagnesemia-causing mutation within them. The maximum two-point LOD score (Zmax) was found for marker D11S4127 (Zmax=6.41 at a recombination fraction of. 00), whereas a multipoint analysis gave a Zmax of 8.24 between markers D11S4142 and D11S4171. Key recombination events define a 5. 6-cM region between these two markers on chromosome 11q23. We conclude that this region encompasses a gene, involved in renal magnesium handling, that is mutated in our patients and is different from the gene involved in intestinal magnesium handling.

Adolescent↗
PubMed1999

Limb mammary syndrome: a new genetic disorder with mammary hypoplasia, ectrodactyly, and other Hand/Foot anomalies maps to human chromosome 3q27.

We report on a large Dutch family with a syndrome characterized by severe hand and/or foot anomalies, and hypoplasia/aplasia of the mammary gland and nipple. Less frequent findings include lacrimal-duct atresia, nail dysplasia, hypohydrosis, hypodontia, and cleft palate with or without bifid uvula. This combination of symptoms has not been reported previously, although there is overlap with the ulnar mammary syndrome (UMS) and with ectrodactyly, ectodermal dysplasia, and clefting syndrome. Allelism with UMS and other related syndromes was excluded by linkage studies with markers from the relevant chromosomal regions. A genomewide screening with polymorphic markers allowed the localization of the genetic defect to the subtelomeric region of chromosome 3q. Haplotype analysis reduced the critical region to a 3-cM interval of chromosome 3q27. This chromosomal segment has not been implicated previously in disorders with defective development of limbs and/or mammary tissue. Therefore, we propose to call this apparently new disorder "limb mammary syndrome" (LMS). The SOX2 gene at 3q27 might be considered an excellent candidate gene for LMS because the corresponding protein stimulates expression of FGF4, an important signaling molecule during limb outgrowth and development. However, no mutations were found in the SOX2 open reading frame, thus excluding its involvement in LMS.

Abnormalities, Multiple↗