ATP5PO levels regulate enteric nervous system development in zebrafish, linking Hirschsprung disease to Down Syndrome.

Hirschsprung disease (HSCR) is a complex genetic disorder characterized by the absence of enteric nervous system (ENS) in the distal region of the intestine. Down Syndrome (DS) patients have a >50-fold higher risk of developing HSCR than the general population, suggesting that overexpression of human chromosome 21 (Hsa21) genes contribute to HSCR etiology. However, identification of responsible genes remains challenging. Here, we describe a genetic screening of potential candidate genes located on Hsa21, using the zebrafish. Candidate genes were located in the DS-HSCR susceptibility region, expressed in the human intestine, were known potential biomarkers for DS prenatal diagnosis, and were present in the zebrafish genome. With this approach, four genes were selected: RCAN1, ITSN1, ATP5PO and SUMO3. However, only overexpression of ATP5PO, coding for a component of the mitochondrial ATPase, led to significant reduction of ENS cells. Paradoxically, in vitro studies showed that overexpression of ATP5PO led to a reduction of ATP5PO protein levels. Impaired neuronal differentiation and reduced mitochondrial ATP production, were also detected in vitro, after overexpression of ATP5PO in a neuroblastoma cell line. Finally, epistasis was observed between ATP5PO and ret, the most important HSCR gene. Taken together, our results identify ATP5PO as the gene responsible for the increased risk of HSCR in DS patients in particular if RET variants are also present, and show that a balanced expression of ATP5PO is required for normal ENS development.

Protective effect of a low single dose inhaled steroid against exercise induced bronchoconstriction.

OBJECTIVE: Daily use of inhaled corticosteroids (ICS) reduces exercise induced bronchoconstriction (EIB) in asthmatic children. A high single dose of ICS also provided acute protection against EIB. Objective of this study is to investigate whether a low single dose of ICS offers protection against EIB in asthmatic children. METHODS: 31 Mild asthmatic children not currently treated with inhaled corticosteroids, 5-16 years, with EIB (fall in FEV0.5/1 ≥ 13%) were included in a prospective intervention study. They performed two ECT's within 2 weeks. Four hours before the second test children inhaled 200 µg beclomethasone-dipropionate (BDP) with a breath-actuated inhaler (BAI). RESULTS: The median fall in FEV0.5/1 after 200 µg BDP was significantly reduced from 30.9% at baseline to 16.0% (P < 0.001). Twenty children (64.5%) showed a good response to 200 µg BDP (≥ 50% decrease in fall of FEV0.5/1), while 8 children showed a moderate response (25-50%), and three children showed no response at all (< 25%). CONCLUSION: A low single dose ICS offers acute protection against EIB in the majority of asthmatic children not currently treated with inhaled corticosteroids.

Assessment of disease severity in late infantile neuronal ceroid lipofuscinosis using multiparametric MR imaging.

BACKGROUND AND PURPOSE: LINCL is a uniformly fatal lysosomal storage disease resulting from mutations in the CLN2 gene that encodes for tripeptidyl peptidase 1, a lysosomal enzyme necessary for the degradation of products of cellular metabolism. With the goal of developing quantitative noninvasive imaging biomarkers sensitive to disease progression, we evaluated a 5-component MR imaging metric and tested its correlation with a clinically derived disease-severity score. MATERIALS AND METHODS: MR imaging parameters were measured across the brain, including quantitative measures of the ADC, FA, nuclear spin-spin relaxation times (T2), volume percentage of CSF (%CSF), and NAA/Cr ratios. Thirty MR imaging datasets were prospectively acquired from 23 subjects with LINCL (2.5-8.4 years of age; 8 male/15 female). Whole-brain histograms were created, and the mode and mean values of the histograms were used to characterize disease severity. RESULTS: Correlation of single MR imaging parameters against the clinical disease-severity scale yielded linear regressions with R2 ranging from 0.25 to 0.70. Combinations of the 5 biomarkers were evaluated by using PCA. The best combination included ADC, %CSF, and NAA/Cr (R2=0.76, P<.001). CONCLUSIONS: The multiparametric disease-severity score obtained from the combination of ADC, %CSF, and NAA/Cr whole-brain MR imaging techniques provided a robust measure of disease severity, which may be useful in clinical therapeutic trials of LINCL in which an objective assessment of therapeutic response is desired.

A genome-wide linkage scan in a Dutch family identifies a premature ovarian failure susceptibility locus.

BACKGROUND: Premature ovarian failure (POF) is characterized by elevated gonadotrophins and amenorrhea before the age of 40 years and occurs approximately in 1% of women. POF etiology is highly heterogeneous with a wide spectrum of etiological pathogenic mechanisms including genetic causes. These mostly involve numerical, structural or monogenic defects on the X-chromosome. Mutations in a small number of autosomal genes (such as FOXL2 and NOBOX) have been identified as a cause of POF. However, in most cases, the disease underlying mechanisms are largely unknown. METHODS: We performed a genome-wide linkage analysis in a relatively large Dutch family with seven patients suffering from POF, showing a dominant pattern of inheritance. A genome-wide analysis, using 50K single nucleotide polymorphism arrays, was combined with conventional parametric linkage analysis. RESULTS: We identified three genomic regions on chromosomes 5, 14 and 18 yielding suggestive linkage (multipoint LOD score of 2.4 for each region). After inclusion of one elder unaffected family member, only the region on chromosome 5 remains as a putative POF locus. In addition, we investigated a second family (three living patients over three generations) for the regions on chromosome 5, 14 and 18. Haplotype analysis supported only the locus on chromosome 5q14.1-q15. CONCLUSION: We performed the first genome-wide linkage search in familial POF and identified a region on chromosome 5q14.1-q15, which may harbor a novel POF susceptibility gene.

A novel susceptibility locus for Hirschsprung's disease maps to 4q31.3-q32.3.

We report on a multigenerational family with isolated Hirschsprung's disease (HSCR). Five patients were affected by either short segment or long segment HSCR. The family consists of two main branches: one with four patients (three siblings and one maternal uncle) and one with one patient. Analysis of the RET gene, the major gene involved in HSCR susceptibility, revealed neither linkage nor mutations. A genome wide linkage analysis was performed, revealing suggestive linkage to a region on 4q31-q32 with a maximum parametric multipoint LOD score of 2.7. Furthermore, non-parametric linkage (NPL) analysis of the genome wide scan data revealed a NPL score of 2.54 (p = 0.003) for the same region on chromosome 4q (D4S413-D4S3351). The minimum linkage interval spans a region of 11.7 cM (12.2 Mb). No genes within this chromosomal interval have previously been implicated in HSCR. Considering the low penetrance of disease in this family, the 4q locus may be necessary but not sufficient to cause HSCR in the absence of modifying loci elsewhere in the genome. Our results suggest the existence of a new susceptibility locus for HSCR at 4q31.3-q32.3.

Familial multiple epiphyseal dysplasia due to a matrilin-3 mutation: further delineation of the phenotype including 40 years follow-up.

In this study, we followed-up the family with bilateral hereditary micro-epiphyseal dysplasia (BHMED) originally described by Elsbach [1959: J Bone Joint Surg [Br] 41-B:514-523]. Clinical re-examination of all available family members resulted in further delineation of the clinical and radiological phenotype, which is distinct from common multiple epiphyseal dysplasia (MED). Linkage analysis excluded EDM1, EDM2, and EDM3 as candidate genes. Linkage and mutation analysis of matrilin-3 (MATN-3) revealed a new pathogenic mutation confirming that BHMED is indeed a distinct disease entity among MED and MED-like disorders.

Characterization and localization of the transmitting tissue-specific PELPIII proteins of Nicotiana tabacum.

The class III pistil-specific PELP proteins (PELPIII) of Nicotiana tabacum includes at least two members of highly soluble glycoproteins containing glucan modules that are characteristic for arabinogalactan proteins (AGPs). PELPIII accumulates in the style transmitting tissue (TT) during pistil development and, at flower anthesis, is present in the intercellular matrix (IM) of non-pollinated pistils. After pollination, PELPIII appears to be directly and completely translocated from the IM into the pollen tube callose walls, no significant accumulation was observed in the primary wall in the tip. In the spent parts of the pollen tubes these proteins become detectable against the remnants of the tube cell membrane and in the callose plugs. Different protein extraction procedures of PELPIII from pollinated tobacco pistils showed that these proteins remain in the highly soluble protein fraction and are not modified by the growing pollen tubes. These data concur with a role in IM development and pollen tube growth. In addition, the data show that the PELPIII are able to reach the cell membrane, facilitated by an already present or induced high porosity of the tube wall and an additional, yet unknown, mechanism. The differences in behaviour between the three related classes of style IM glycoproteins of Nicotiana, namely, PELPII, TTS and the 120 kDa glycoprotein, are proposed to connect more to their differences in glycosylation than to major differences in amino acid sequence.

Eye movements to yaw, pitch, and roll about vertical and horizontal axes: adaptation and motion sickness.

BACKGROUND: In the search for parameters to predict motion sickness that can be measured in the laboratory, we performed a longitudinal investigation in aviators. Since the vestibular system is involved in the generation of motion sickness as well as eye movements, vestibulo-ocular reflex (VOR) parameters seemed relevant. We investigated three topics: 1) the effect of axis orientation and its orientation to gravity on the VOR; 2) changes in VOR parameters depending on flight experience; and 3) differences in VOR parameters in aircrew with high and low susceptibility to motion sickness. HYPOTHESIS: Nystagmus decay after angular velocity steps would be faster for non-susceptible and trained aviators. METHODS: We recorded eye movements evoked by angular on-axis velocity steps (+/- 90 degrees x S(-2), to and from 90 degrees x S(-1)) in yaw, pitch, and roll, about both the Earth vertical and Earth horizontal axes in 14 subjects with a low susceptibility to motion sickness. These data were compared with those of 10 subjects with a high susceptibility. RESULTS: Horizontal axis rotations are nauseogenic. We found that during (per) and post-condition, left- and rightward rotation responses were equal, and the orientation with respect to gravity did not alter the basic nystagmus decay, apart from a sinusoidal modulation. Moreover, pitch and roll rotations show equal nystagmus decays, significantly faster than for yaw; yaw and pitch peak velocities were equal and were larger than for roll. With regard to changes in VOR parameters depending on flight experience, we found that repeated vestibular stimulation reduced nystagmus decay as well as the otolith modulation. With respect to the changes in VOR parameters and motion sickness susceptibility, we found that subjects highly susceptible to motion sickness showed a slower decay of nystagmus with a larger peak velocity than less susceptible subjects. CONCLUSIONS: Group averages indicate a difference in eye movement parameters, only in yaw, depending on flight experience; and between subjects with low and high susceptibility to motion sickness. The involvement of the velocity storage mechanism as realized by an internal model is given as a plausible explanation.

Hydroxyproline-rich glycoproteins in plant reproductive tissues: structure, functions and regulation.

The plant reproductive process of pollination involves a series of interactions between the male gametophyte (the pollen grain or pollen tube) and extracellular matrix (ECM) molecules secreted by different cell types along the pollen tube growth pathway in the female organ, the pistil. These interactions are believed to signal and regulate the pollen tube growth process to effect successful delivery of the sperm cells to the ovules where fertilization takes place. Hydroxyproline-rich glycoproteins secreted by plant cells are believed to play a broad range of functions, ranging from providing structural integrity to mediating cell-cell interactions and communication. The pistil and pollen tube ECM is enriched in these highly glycosylated proteins. Our discussions here will focus on a number of these proteins for which most information has been available, from Nicotiana tabacum, its self-incompatible relative N. alata, and Zea mays. In addition, the regulation of the synthesis and glyco-modification of one of these proteins, TTS (transmitting tissue-specific) protein from N. tabacum will be discussed in the light of how differential glycosylation may be used to regulate molecular interactions within the ECM.

Familial frontotemporal dementia with ubiquitin-positive inclusions is linked to chromosome 17q21-22.

Hereditary frontotemporal dementia (FTD) is an autosomal dominant neurodegenerative disorder that is associated with mutations in the tau gene and with the pathological accumulation of hyperphosphorylated tau protein in affected brain cells in about a quarter of cases. However, most FTD families have no demonstrable tau mutations. Here we describe the clinical and neuropathological features of a large family with hereditary FTD. Genetic analysis showed strong evidence for linkage to chromosome 17q21-22 (maximum lod score 3.46, theta = 0 for marker D17S950), but mutations in the tau gene were not found. Clinical symptoms, neuropsychological deficits and neuroimaging findings of affected family members were similar to sporadic and tau-related FTD. The mean age at onset was 61.2 years, with loss of initiative and decreased spontaneous speech as the most prominent presenting symptoms. Pathological examination of the brains of two affected family members showed non-specific neuronal degeneration with dense cytoplasmic ubiquitin-positive inclusions in neurones of the second layer of the frontotemporal cortex and dentate gyrus of the hippocampus. In a number of neurones these inclusions appeared to be located inside the nucleus, although due to the small number of these inclusions this localization could not be confirmed by electron microscopy. The inclusions were not stained by tau, alpha-synuclein or polyglutamine antibodies. Biochemical analysis of soluble tau did not reveal abnormalities in tau isoform distribution and analysis of mRNA showed the presence of both three- and four-repeat transcripts. This is the first report of ubiquitin-positive, tau-negative inclusions in an FTD family with significant linkage to chromosome 17q21-22. Further characterization of the ubiquitin-positive inclusions may clarify the neurodegenerative pathways involved in this subtype of FTD.

Submergence induces expansin gene expression in flooding-tolerant Rumex palustris and not in flooding-intolerant R. acetosa.

Ethylene-enhanced leaf elongation upon submergence is part of the survival mechanism of Rumex palustris Sm. plants that grow in frequently flooded areas. Other Rumex species, like R. acetosa L., do not possess this ability and can therefore only survive in habitats that are not frequently inundated. Expansins are proteins that induce extension of isolated cell walls, and therefore might play a role in the stimulation of petiole elongation, also in Rumex. We report here on the identification of several gene sequences encoding for alpha-expansins in R. palustris and R. acetosa plants. The pattern of transcript accumulation of one of these genes, Rp-EXP1, could be correlated with the pattern of leaf elongation in R. palustris after submergence or ethylene treatment. Induction of expansin gene activity was not found in R. acetosa upon these treatments, indicating that ethylene induces the expression of expansin genes in leaves of species that exhibit flooding-induced shoot elongation.

Contribution of the otoliths to the human torsional vestibulo-ocular reflex.

The dynamic contribution of the otolith organs to the human ocular torsion response was examined during passive sinusoidal body roll about an earth-horizontal axis (varying otolith inputs) and about an earth-vertical axis (invariant otolith inputs). Torsional eye movements were registered in 5 subjects by means of video-oculography. At a fixed amplitude of 25 degrees, the stimulus frequency was varied from 0.05 to 0.4 Hz. Additionally, at a fixed frequency of 0.2 Hz, the response was also measured at the amplitudes to 12.5 degrees and 50 degrees. The results showed that the gain and phase of the torsional slow component velocity (SCV) did not depend on stimulus amplitude, indicating a linear response. Contribution of the otoliths affected the ocular torsion response in three different ways. First, the gain of the SCV was slightly, but consistently, higher during rotation about an earth-horizontal axis than during rotation about an earth-vertical axis. With invariant otolith inputs the average gain increased from 0.10 at 0.05 Hz to 0.26 at 0.25 Hz. With varying otolith inputs, the average gain increased from 0.14 to 0.37. Second and more substantially, contribution of the otoliths improved the response dynamics by reducing the phase lead at frequencies up to 0.02 Hz. Third, the nystagmus showed considerably less anticompensatory saccades in upright conditions than in supine conditions, even though the SCV gain was lower in the latter. As a consequence, the average excursion of torsional eye position was highest during earth-horizontal rotation. This effect was observed in the entire frequency range. Thus, the otoliths controlled the human torsional VOR not only at low stimulus frequencies by keeping the slow component in phase with head motion, but also in a wider frequency range by modulating the saccadic behavior as to increase the amplitude of ocular torsion. We conclude that the primary concern of the otolith-oculomotor system during head tilt is to stabilize eye position in space, rather than to prevent retinal blur.

Motion sickness: only one provocative conflict?

In reviewing the various forms of motion sickness, the classic sensory rearrangement theory has been redefined by demonstrating that only one type of conflict is necessary and sufficient to explain all different kinds of motion sickness. A mathematical description is provided from the summarizing statement that "All situations which provoke motion sickness are characterised by a condition in which the sensed vertical as determined on the basis of integrated information from the eyes, the vestibular system and the nonvestibular proprioceptors is at variance with the subjective vertical as expected from previous experience."

Roll motion stimuli: sensory conflict, perceptual weighting and motion sickness.

In an experiment with 17 subjects, interactions of visual roll motion stimuli and vestibular body tilt stimuli were examined in determining the subjective vertical. Interindividual differences in weighting the visual information were observed, but in general, visual and vestibular responses added in setting the vertical. Despite the conflicting sensory information, motion sickness was not reported apart from one subject on one single occasion. This is in conflict with the sensory mismatch theory on motion sickness, but in agreement with the subjective vertical conflict theory.

A sustained hyper-g load as a tool to simulate space sickness.

In April 1989 the three European scientist astronauts of the D1 Spacelab Mission were exposed to a 1.5 hours +3G centrifuge run in supine position, resulting in a linear acceleration along the subjects' x-axis. Afterwards, severe motion sickness symptoms were provoked by head movements (Sickness Induced by Centrifugation: SIC). The astronauts mentioned close similarities with what they experienced in space during the D1-Spacelab Mission in 1985, where head movements also provoked motion sickness symptoms (Space Adaptation Syndrome: SAS). Moreover, the astronauts agreed that the rank order of their susceptibility to SAS was the same as for SIC. It was therefore postulated that with this method SAS could be simulated on earth. Additionally, in otolith function tests following the centrifuge run, changes in visual-vestibular interaction were observed, which replicated objective findings obtained with the same astronauts immediately after the D1 Spacelab Mission. During the last couple of years a series of experiments has been carried out to determine the nature of the stimulus causing SIC, the incidence of SIC, and the underlying cardio-vascular and/or vestibular mechanisms. These experiments were carried out on several astronauts and some 50 'normal' healthy subjects. In the next sections the main findings of all these experiments and the implications are summarized.

The retention of balance: an exploratory study into the limits of acceleration the human body can withstand without losing equilibrium.

The human limiting values for sudden accelerations we have determined can be used to evaluate specific physical conditions that cause problems in maintaining postural balance. A comparison between the data obtained in the laboratory and the situations occurring during public transport by tram, bus, and metro revealed that both the initial impetus ("jerk") and the level of acceleration found in practice were sufficient to ensure that none of the individuals measured in the laboratory would have been able to retain their balance without extra support. The study suggests that limiting the initial jerk component of the acceleration would help considerably in alleviating the problem.