Mesoaxial polydactyly is a major feature in Bardet-Biedl syndrome patients with LZTFL1 (BBS17) mutations

Ciliopathies are heterogeneous disorders sharing different clinical signs due to a defect at the level of the primary cilia/centrosome complex. Postaxial polydactyly is frequently reported in ciliopathies, especially in Bardet-Biedl syndrome (BBS). Clinical features and genetic results observed in a pair of dizygotic twins with BBS are reported. The following manifestations were present: retinitis pigmentosa, bilateral insertional polydactyly, cognitive impairment and renal dysfunction. X-rays of the hands confirmed the presence of a 4th mesoaxial extra-digit with Y-shaped metacarpal bones. The sequencing of LZTFL1 identified a missense mutation (NM_020347.2: p.Leu87Pro; c.260T>C) and a nonsense mutation (p.Glu260*; c.778G>T), establishing a compound heterozygous status for the twins. A major decrease of LZTFL1 transcript and protein was observed in the patient's fibroblasts. This is the second report of LZTFL1 mutations in BBS patients confirming LZTFL1 as a BBS gene. Interestingly, the only two families reported in literature thus far with LZTFL1 mutations have in common mesoaxial polydactyly, a very uncommon feature for BBS. This special subtype of polydactyly in BBS patients is easily identified on clinical examination and prompts for priority sequencing of LZTFL1 (BBS17).

Experimental demonstration of the supersonic-subsonic bifurcation in the circular jump: a hydrodynamic white hole

We provide an experimental demonstration that the circular hydraulic jump represents a hydrodynamic white hole or gravitational fountain (the time reverse of a black hole) by measuring the angle of the Mach cone created by an object in the "supersonic" inner flow region. We emphasize the general character of this gravitational analogy by showing theoretically that the white hole horizon constitutes a stationary and spatial saddle-node bifurcation within dynamical-systems theory. We also demonstrate that the inner region has a "superluminal" dispersion relation, that is, that the group velocity of the surface waves increases with frequency, and discuss some possible consequences with respect to the robustness of Hawking radiation. Finally, we point out that our experiment shows a concrete example of a possible "trans-Planckian distortion" of black or white holes.

Impaired striatum-dependent behavior in GASP-1-knock-out mice

G protein-coupled receptor (GPCR) associated sorting protein-1 (GASP-1) is suspected to play a key role in recycling and degradation of several GPCRs. In a previous study, we have shown that GASP-1-knock-out (GASP-1-KO) mice displayed deficits in acquiring a cocaine self-administration task, associated with an exacerbated down-regulation of striatal dopaminergic and cholinergic receptors. Among several possibilities, GASP-1 deficiency could have impaired memory processes underlying the acquisition of the operant conditioning task. Therefore, the present study investigated cognitive performances of GASP-1-KO mice and their wild-type littermates (WT) in a broad variety of memory tasks. Consistent with a deficit in procedural memory, GASP-1-KO mice showed delayed acquisition of a food-reinforced bar-press task. During water-maze training in hidden- or visible-platform paradigms, mutant and WT mice acquired the tasks at the same rate. However, GASP-1 mice exhibited persistent thigmotaxic swimming, longer distance to the platform, and reduced swim speed. There was no deficit in several tasks requiring simple behavioral responses (Barnes maze, object recognition and passive avoidance tasks). Thus, the ability to acquire and/or express complex responses seems affected in GASP-1-deficient mice. Hippocampal functions were preserved, as the retention of an acquired memory in spatial tasks remained unaffected. The pattern of behavioral deficits observed in GASP-1-KO mice is coherent with current knowledge on the role of striatal GPCRs in acquisition/expression of skilled behavior and in motivation. Together with the previous findings, the so far established phenotype of GASP-1-KO mice makes them a potentially exciting tool to study striatal functions.

Pattern formation in bubbles emerging periodically from a liquid free surface

Patterns formed by centimeter scale bubbles on the free surface of a viscous liquid are investigated in a cylindrical container. These bubbles emerge periodically at the surface and interact with each other in the central zone. Their radial emission, due to interaction and radial surface flow, leads to the formation of a variety of patterns. Different star-like and spiral patterns appear spontaneously by increasing the bubble emergence frequency. It is found that these patterns are due to a constant angular shift in the bubble emission direction. Measurements of this angular shift show a supercritical bifurcation accompanied by a transition from a pattern of two opposed straight arms to spiral patterns. By applying the tools and concepts from the study of leaf arrangement in botany (phyllotaxis), the recognized patterns and the mechanism of the pattern formation are discussed. Close similarities to the leaf arrangement are found in the behavior of the angular shift and the patterns. These findings suggest that the observed patterns are formed by a packing mechanism of successively appearing elements (bubbles), which is similar to that of the leaves at the earliest stage of phyllotaxis.

The effects of tegaserod, a 5-HT receptor agonist, on gastric emptying in a murine model of diabetes mellitus

The C57BLKS/J db/db transgenic mouse is a model of diabetes mellitus that has been shown to have delayed gastric emptying. We assessed gastric emptying rates in C57BLKS/J mice, and determined the effects of tegaserod, a new selective 5-HT(4) receptor partial agonist, on gastric emptying.

METHODS

Gastric emptying rates of a 20% glucose test meal were determined in 12-20-week-old female db/db mice and control littermates. The effects of tegaserod (0.1-2.0 mg kg(-1), i.p.) on gastric transit were tested in a second group of db/db mice. Pretreatment with GR11308, a specific 5-HT(4)antagonist, was used to confirm the mechanism of action of tegaserod on gastric emptying.

RESULTS

Gastric emptying of glucose was significantly slower in db/db mice than in control littermates. Tegaserod (0.1 mg kg(-1)) significantly accelerated the gastric emptying rate of glucose in db/db mice, reducing the fraction of the meal remaining in the stomach at 30 min by 80%. GR11308 blocked the gastrokinetic effects of tegaserod.

CONCLUSIONS

Gastric emptying was impaired in db/db mice. Low dose tegaserod improved gastric emptying rates in this model of gastroparesis through the activation of 5-HT(4) receptors. These findings suggest that 5-HT(4) receptor agonists may prove useful for improving delayed gastric emptying in gastroparesis.

Structures of a continuously fed two-dimensional viscous film under a destabilizing gravitational force

We study the gravity induced instability of a liquid film formed below a plane grid which is used as a porous media in an original hydrodynamic experiment. The film is continuously supplied with a controlled flow rate. We give through a phase diagram the full spectrum of the different flow regimes and we investigate the dynamics of the observed structures. True secondary instabilities of a 2D periodic pattern are described. The control parameters are the flow rate and the viscosity.

[SF-36 Health Survey in Rehabilitation Research. Findings from the North German Network for Rehabilitation Research, NVRF, within the rehabilitation research funding program]

The SF-36 Health Survey and its 12-item abridged form is an instrument for the assessment of health related quality of life that can be used with healthy persons and patient populations. Its use has been recommended within a large German multicentre rehabilitation research programme. The paper examines missing data across all five study projects of the North German Network for Rehabilitation Research (NVRF) as well as psychometric properties of the instrument. In addition, data were compared to representative norm data using the SF-36 (SF-12) in the German National Health Survey. Results showed that there were few missing data in the SF-36. Examining the impact of age, gender and health status yielded effects of higher age and female gender on missing data. Psychometric analyses showed good to excellent results of the instrument in terms of scale fit and reliability. In terms of convergent validity, medium to high correlation of the SF-36 subscales with comparable instruments (e. g. SCL-90-R) could be found. Summarizing, the SF-36/SF-12 can be recommended for use in rehabilitation research. Analyses regarding sensitivity should be conducted in future studies.

Does my mouse have Alzheimer's disease?

Small animal models that manifest many of the characteristic neuropathological and behavioral features of Alzheimer's disease (AD) have been developed and have proven of great value for studying the pathogenesis of this disorder at the molecular, cellular and behavioral levels. The great progress made in our understanding of the genetic factors that either cause or contribute to the risk of developing AD has prompted many laboratories to create transgenic (tg) mice that overexpress specific genes which cause familial forms of the disease. Several of these tg mice display neuropathological and behavioral features of AD including amyloid beta-peptide (A beta) and amyloid deposits, neuritic plaques, gliosis, synaptic alterations and signs of neurodegeneration as well as memory impairment. Despite these similarities, important differences in neuropathology and behavior between these tg mouse models and AD have also been observed, and to date no perfect animal model has emerged. Moreover, ascertaining which elements of the neuropathological and behavioral phenotype of these various strains of tg mice are relevant to that observed in AD continues to be a challenge. Here we provide a critical review of the AD-like neuropathology and behavioral phenotypes of several well-known and utilized tg mice that express human APP transgenes.

Serotonin type-4 receptors modulate the sensitivity of intramural mechanoreceptive afferents of the cat rectum

It has been suggested that serotonin (5-hydroxytryptamine) type-4 (5-HT4) receptors modulate the sensitivity of intrinsic afferents of the intestinal mucosa. We studied the involvement of 5-HT4receptors in the modulation of extrinsic afferent sensitivity of the intestinal wall. During distension ramps, mechanoreceptive rectal afferents in sacral dorsal roots were examined in decerebrate anaesthesia-free cats using the selective 5-HT4receptor partial agonist, tegaserod (HTF 919), and the 5-HT4receptor antagonist, SB 203186. The static discharge rate of the afferents evoked by rectal distension decreased after intravenous (i.v.) administration of tegaserod at intraluminal pressures above 30 mmHg, with the most effective reduction occurring at 50 mmHg. The effect was dose-dependent, with maximal reduction occurring at 1.2 mg kg-1 bodyweight, and could be partly reversed by i.v. administration of SB 203186. Tegaserod did not alter the pressure-volume relationship (compliance) of the rectum. It is tentatively concluded that 5-HT4receptor activation has an inhibitory effect on intramural mechanoreceptors in the cat's rectum. Our results are in line with the observation that tegaserod relieves the sensory symptoms of patients suffering from irritable bowel syndrome.

Essential role of oligodendrocytes in the formation and maintenance of central nervous system nodal regions

The membrane of myelinated axons is divided into functionally distinct domains characterized by the enrichment of specific proteins. The mechanisms responsible for this organization have not been fully identified. To further address the role of oligodendrocytes in the functional segmentation of the axolemma in vivo, the distribution of nodal (Na+ channels, ankyrin G), paranodal (paranodin/contactin-associated-protein) and juxtaparanodal (Kv1.1 K+ channels) axonal markers, was studied in the brain of MBP-TK and jimpy mice. In MBP-TK transgenic mice, oligodendrocyte ablation was selectively induced by FIAU treatment before and during the onset of myelination. In jimpy mice, oligodendrocytes degenerate spontaneously within the first postnatal weeks after the onset of myelination. Interestingly, in MBP-TK mice treated for 1-20 days with FIAU, despite the ablation of more than 95% of oligodendrocytes, the protein levels of all tested nodal markers was unaltered. Nevertheless, these proteins failed to cluster in the nodal regions. By contrast, in jimpy mice, despite a diffused localization of paranodin, the formation of nodal clusters of Na+ channels and ankyrin G was observed. Furthermore, K+ channels clusters were transiently visible, but were in direct contact with nodal markers. These results demonstrate that the organization of functional domains in myelinated axons is oligodendrocyte dependent. They also show that the presence of these cells is a requirement for the maintenance of nodal and paranodal regions.

A transgenic mouse model for inducible and reversible dysmyelination

Oligodendrocytes are glial cells devoted to the production of myelin sheaths. Myelination of the CNS occurs essentially after birth. To delineate both the times of oligodendrocyte proliferation and myelination, as well as to study the consequence of dysmyelination in vivo, a model of inducible dysmyelination was developed. To achieve oligodendrocyte ablation, transgenic animals were generated that express the herpes virus 1 thymidine kinase (HSV1-TK) gene under the control of the myelin basic protein (MBP) gene promoter. The expression of the MBP-TK transgene in oligodendrocytes is not toxic on its own; however, toxicity can be selectively induced by the systemic injection of animals with nucleoside analogs, such as FIAU [1-(2-deoxy-2-fluoro-beta-delta-arabinofuranosyl)-5-iodouracil]. This system allows us to control the precise duration of the toxic insult and the degree of ablation of oligodendrocytes in vivo. We show that chronic treatment of MBP-TK mice with FIAU during the first 3 postnatal weeks triggers almost a total depletion of oligodendrocytes in the CNS. These effects are accompanied by a behavioral phenotype characterized by tremors, seizures, retarded growth, and premature animal death. We identify the period of highest oligodendrocytes division in the first 9 postnatal days. Delaying the beginning of FIAU treatments results in different degrees of dysmyelination. Dysmyelination in MBP-TK mice is always accompanied by astrocytosis. Thus, this transgenic line provides a model to study the events occurring during dysmyelination of various intensities. It also represents an invaluable tool to investigate remyelination in vivo.

Serotonin type-1A receptor imaging in depression

Regional 5-hydroxytryptamine(1A) (5-HT(1A)) receptor binding potential (BP) of depressed subjects with primary, recurrent, familial mood disorders was compared to that of healthy controls by using positron emission tomography and [carbonyl-(11)C]WAY-100635 ¿[(11)C]N-(2-(4-(2-methoxyphenyl)-1-piperazin-1-yl)ethyl)-N-(2- pyridy l)cyclohexanecarboxamide¿. The mean 5-HT(1A) receptor BP was reduced 42% in the midbrain raphe and 25-33% in limbic and neocortical areas in the mesiotemporal, occipital, and parietal cortex. The magnitude of these abnormalities was most prominent in bipolar depressives and unipolar depressives who had bipolar relatives. These abnormal reductions in 5-HT(1A) receptor BP are consistent with in vivo evidence that 5-HT(1A) receptor sensitivity is reduced in major depressive disorder and postmortem data showing a widespread deficit of 5-HT(1A) receptor expression in primary mood disorders.

The beta-amyloid precursor protein and its derivatives: from biology to learning and memory processes

Intensive investigation towards the understanding of the biology and physiological functions of the beta-amyloid precursor protein (APP) have been supported since it is known that a 39-43 amino acid fragment of APP, called the beta-amyloid protein (Abeta), accumulates in the brain parenchyma to form the typical lesions associated with Alzheimer's disease (AD). It emerges from extensive data that APP and its derivatives show a wide range of contrasting physiological properties and therefore might be involved in distinct physiological functions. Abeta has been shown to disrupt neuronal activity and to demonstrate neurotoxic properties in a wide range of experimental procedures. In contrast, both in vitro and in vivo studies suggest that APP and/or its secreted forms are important factors involved in the viability, growth and morphological and functional plasticity of nerve cells. Furthermore, several recent studies suggest that APP and its derivatives have an important role in learning and memory processes. Memory impairments can be induced in animals by intracerebral treatment with Abeta. Altered expression of the APP gene in aged animals or in genetically-modified animals also leads to memory deficits. By contrast, secreted forms of APP have recently been shown to facilitate learning and memory processes in mice. These interesting findings open novel perspectives to understand the involvement of APP in the development of cognitive deficits associated with AD. In this review, we summarize the current data concerning the biology and the behavioral effects of APP and its derivatives which may be relevant to the roles of these proteins in memory and in AD pathology.

Neuroanatomical abnormalities in behaviorally characterized APP(V717F) transgenic mice

Histological analyses were performed on the brains of APP(V717F) transgenic (Tg)mice previously studied in a battery of behavioral tests. We describe here the regional and age-dependent deposition of amyloid in both heterozygous and homozygous Tg mice. We also report that Tg mice show significant and age-dependent changes in synaptic density measured by synaptophysin immunoreactivity. Surprisingly, a rather marked hippocampal atrophy is observed as early as 3 months of age in Tg mice (20-40%). Statistical analyses revealed that the deficits in object recognition memory are related to the number of amyloid deposits in specific brain regions, whereas deficits in spatial reference and working memory are related to the changes in synaptic density and hippocampal atrophy. Our study suggests that the behavioral deficits observed in Tg mice are only in part related to amyloid deposition, but are also related to neuroanatomical alterations secondary to overexpression of the APP(V717F) transgene and independent of amyloid deposition.