A VEP investigation of parallel visual pathway development in primary school age children

Different features of visual function mature along unique timescales through infancy and early childhood. It is not clear which functions continue to mature in school age children. Functions believed to be mediated by the Magnocellular (M) and Parvocellular (P) pathways were compared in five- (n=25), eight- (n=21) and eleven-year-old children (n=21) and young adult controls (n=20). Steady-state visual evoked potentials were recorded from occipital electrodes in response to very low spatial frequency gratings, at a series of contrasts (M), and to high contrast gratings at a series of spatial frequencies (P). No evidence was found to indicate M pathway development across these age groups. However, the youngest children demonstrated elevated VEP thresholds to the high contrast gratings compared with either the adults or eleven-year-olds. This difference in threshold implies an immaturity of the high contrast, high spatial frequency stream, i.e. the putative P pathway. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Study on the Compliance of the Patients with Ocular Fundus Diseases

Purpose: To investigate the compliance of the patients with ocular fundus diseases with recommendation for follow-up examination after laser treatment, and the underlying reasons for non-compliance.Methods: 53 patients with ocular fundus disease were asked to fill in a questionnaire which includes the socio-demographic characteristics, fear of the fundus disease, conception of the laser treatment and the motivation for staying healthy. Variables were compared for the compliers group and the non-compliers group by chi-square test. Result; Of the 53 subjects, 35 were classified as non-compliers and 18 were classified as compliers. There was no statistically significant difference between the two groups on all selected socio-demographic factors, conception of the laser treatment and the motivation for staying healthy. Significant difference was found between the two groups on two of those items concerning the fear of the diseases (P<0. 05). About half of the participants showed the lack of knowledge about     

Neurovascular developmental interaction: a specific form of vascular maldevelopment in the malformed brain

The process of the development of the intracranial vessels was studied by means of immunohistochemical analysis of factor VIII in normal and exencephalic chick fetuses. The results revealed that the development of blood vessels in exencephalic brain was far advanced beyond the norm, with intense immunoreactivity to factor VIII on postincubation day 16 exceeding that on day 21 in normal controls. Compared with results regarding the direction of the overgrowth in the neuronal maturation process in the previous study using the chick exencephaly model, the findings of overmatured blood vessels were compatible with NSE- and somatostatin-positive elements that appeared especially in the overgrowth foci. The results of the present study suggested the pathogenic development of the area cerebrovasculosa in the neural placode as a phenomenon consequent upon hypervascularization in response to neuronal overgrowth, as seen in human cases of exencephaly or anencephaly. We emphasize the significance of this specific phenomenon in the development of the fetal central nervous system, namely neurovascular developmental interaction.     

Role of mesenchymal-epithelial interactions in mammary gland development

The mammary gland is a hormone-target organ derived from epidermis and develops as a result of reciprocal mesenchymal-epithelial interactions. The induction of mammary differentiation from indifferent epidermal cells by mammary mesenchyme implies induction of the complement of hormone receptors characteristic of normal mammary epithelium in cells of the epidermis. Considering the facts that mammary epithelial differentiation is induced by mammary mesenchyme and that certain aspects of hormone response (androgen-induced mammary regression) are inextricably linked to mesenchymal-epithelial interactions, it is evident that the biology of the mammary gland arises from and is maintained via cell-cell interactions. As a corollary, perturbation of stromal-epithelial interactions in adulthood may play a role in mammary carcinogenesis and in turn may provide opportunities for differentiation therapy.     

Long-term outcome in 134 patients with galactosaemia

In a retrospective study 134 galactosaemic patients, born between 1955 and 1989 in the Federal Republic of Germany were traced and their long-term outcome evaluated. We investigated 83 galactosaemic patients (78 homozygotes, 5 compound heterozygotes) by clinical, psychometric and laboratory testing; 31 patients were evaluated by medical history, the remaining 20 patients had died due to sequelae of the underlying disease. In 48 out of 78 classical galactosaemia patients galactose-free therapy had been started before the 15th day, in 19 between days 15 and 56 and in 11 patients after the 56th day. Physical findings revealed that puberty was delayed in 1 out of 18 males and 6 out of 11 females. Neurological abnormalities included ataxia (n=6), intention tremor (n=11) and microcephaly (n=10). Speech abnormalities were found in 43 out of 66 patients over 3 years of age and disturbance of visual perception and/or arithmetic deficits in 29. Intelligence declined with age, i.e., a DQ or IQ less than 85 was found in 4 out of 34 patients less than 6 years of age (12%), in 10 out of 18 between 7 and 12 years (56%) and in 20 out of 24 older than 12 years (83%). Metabolite patterns (RBC galactose-1-phosphate and UDP-galactose, plasma and urinary galactitol) did not correlate with DQ or IQ. Dietary compliance was good in almost all patients. Compound heterozygotes (n=5) had normal mental and growth development and all laboratory parameters were in the normal range. The cause of the unsatisfactory outcome of well-treated galactosaemic patients with disturbances in long-term development remains unclear. This could be due to a chronic intoxication of galactose metabolites or a deficiency of UDP-galactose or galactose-containing glycoproteins or glycolipids.This study was supported by a grant from the Stifterverband für die Deutsche Wissenschaft (Huebner-stiftung), grant TS 114/18/89 and by the Arbeitsgemeinschaft für Pädiatrische Stoffwechselstörungen     

Septo-optic dysplasia and growth hormone deficiency: accelerated pubertal maturation during GH therapy

We report four patients (three male, one female) with septo-optic dysplasia and growth hormone deficiency. All had GH therapy for a period of four to eight years until reaching final height. In all four cases bone maturation during puberty was accelerated (1.4 to 1.9 "years"/year), resulting in a final height which was clearly below the predicted height. The progress of pubertal stages was very short in all patients. In three patients TSH and prolactin release after TRH stimulation were increased. These data support a hypothalamic original of the endocrine disorder. Insufficient GH release, even after repeated GHRH stimulation, is in contrast to this assumption. In one case there was a late manifestation of neurohormonal diabetes insipidus, which indicates the possibility of later disease progression. MR imaging of the brain demonstrated variable malformation of the septum pellucidum, chiasma and nervus opticus or the pituitary gland, respectively.     

Altered Topography in the Geniculo-cortical Projection of the Golden Hamster Following Neonatal Monocular Enucleation

The consequence of neonatal eye removal on the adult organization of the geniculo-cortical pathway was studied anatomically in hamsters. Separate discrete injections of rhodamine- and green-fluorescent latex microspheres were made into the primary visual cortex of adult hamsters. The distribution of labelling in the dorsal lateral geniculate nucleus (dLGN) of normal animals was compared with that seen in animals monocularly enucleated at birth. In the normal animals, as expected, the projection has a precise topographic order. This is also true of the projection contralateral to the remaining eye in the enucleated animals. However, on the side ipsilateral to the remaining eye, the visual cortex appears to receive two convergent projections from the deafferented dLGN, one mirroring the other. A single injection made in very lateral cortex labels cells in two discrete regions of the dLGN. As the injection is made progressively more medial, the two patches of labelled cells converge. Eventually, the two patches are no longer discrete so that injections into central area 17 produce just one, extended patch of labelling. These results suggest that the altered retinal input to the dLGN may affect the subsequent development of ordered geniculo-cortical projections.     

Developmental aspect of differences in hypothalamic preproneuropeptide y messenger ribonucleic Acid content in lean and genetically obese zucker rats

The genetically obese Zucker rat is a well characterized model of early onset human obesity. Many of the endocrine and metabolic abnormalities of obese animals are common to other strains of genetically obese animals as well as morbidly obese humans. Neuropeptide Y (NPY), a potent orexigenic agent, was recently found to be elevated in adult obese animals compared to their lean littermates. In this study we first examined hypothalamic expression of preproNPY mRNA, using solution hybridization/ nuclease protection analysis, in phenotypically-matched, i.e. lean or obese, immature (5-week-old) and mature (33-week-old) animals. Although changes were not statistically different, a trend toward decreased hypothalamic preproNPY mRNA levels was detected in both lean and obese mature animals. We next compared hypothalamic preproNPY mRNA levels between age-matched lean and obese animals at 5, 14 and 33 weeks of age and found elevated preproNPY mRNA levels in obese rats at all three ages. These data suggest that increased levels of hypothalamic NPY are an early manifestation of the obese phenotype and may, therefore, contribute to hyperphagia and increased weight gain in obese Zucker rats.     

Specificity in the Development of Vertical Connections in Cat Striate Cortex

The main efferent axons of pyramidal cells in layer 2/3 in the adult cat striate cortex make collateral connections specifically within layer 2/3 and layer 5 and avoid the intervening layer 4. Intracellular dye injections in vitro were used to determine how, during early postnatal development, this precise pattern of laminar connections was achieved. These investigations revealed that the pattern of collateral outgrowth was specific from the very earliest time that axons began sprouting collaterals. During the first postnatal week, sprouts were seen exclusively within layers 2/3 and 5; no evidence for a transient connection to layer 4 was observed. Furthermore, collaterals emerged simultaneously within layers 2/3 and 5, despite the large difference in the postmigratory ages of the two layers. By the end of the second postnatal week, the adult number of collaterals was achieved. Further elaboration of the local arbors occurred by repeated branching of already existing collaterals, rather than by addition of new collaterals to the main axon. These results demonstrate that the formation of local connections between cortical layers is highly specific, in contrast to the development of clustered horizontal connections by these same cells within layers 2/3 and 5, which involves extensive remodelling of local connections.     

Differential Distribution of Tau Proteins in Developing Cat Cerebral Cortex and Corpus Callosum

During the postnatal development of cat visual cortex and corpus callosum the molecular composition of tau proteins varied with age. In both structures, they changed between postnatal days 19 and 39 from a set of two juvenile forms to a set of at least two adult variants with higher molecular weights. During the first postnatal week, tau proteins were detectable with TAU-1 antibody in axons of corpus callosum and visual cortex, and in some perikarya and dendrites in the visual cortex. At later ages, tau proteins were located exclusively within axons in all cortical layers and in the corpus callosum. Dephosphorylation of postnatal day 11 cortical tissue by alkaline phosphatase strongly increased tau protein immunoreactivity on Western blots and in numerous perikarya and dendrites in all cortical layers, in sections, suggesting that some tau forms had been unmasked. During postnatal development the intensity of this phosphate-dependent somatodendritic staining decreased, but remained in a few neurons in cortical layers II and III. On blots, the immunoreactivity of adult tau to TAU-1 was only marginally increased by dephosphorylation. Other tau antibodies (TAU-2, B19 and BR133) recognized two juvenile and two adult cat tau proteins on blots, and localized tau in axons or perikarya and dendrites in tissue untreated with alkaline phosphatase. Tau proteins in mature tissue were soluble and not associated with detergent-resistant structures. Furthermore, dephosphorylation by alkaline phosphatase resulted in the appearance of more tau proteins in soluble fractions. Therefore tau proteins seem to alter their degree of phosphorylation during development. This could affect microtubule stability as well as influence axonal and dendritic differentiation.