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Biomedical subjects

K Schilling

Publications and source records attributed to K Schilling.

At least 19 recordsLinked to original sources
PubMed2003

Hereditary myoclonus-dystonia associated with epilepsy.

A five-generation Dutch family with inherited myoclonus-dystonia (M-D) is described. Genetic analysis revealed a novel truncating mutation within the epsilon-sarcoglycan gene (SGCE). In three of five gene carriers, epilepsy and/or EEG abnormalities were associated with the symptoms of myoclonus and dystonia. The genetic and clinical heterogeneity of M-D is extended. EEG changes and epilepsy should not be considered exclusion criteria for the clinical diagnosis of M-D.

Adult↗
PubMed2003

Morphological development and neurochemical differentiation of cerebellar inhibitory interneurons in microexplant cultures.

The cerebellar cortex comprises a rather limited variety of interneurons, prominently among them inhibitory basket and stellate cells and Golgi neurons. To identify mechanisms subserving the positioning, morphogenesis, and neurochemical maturation of these inhibitory interneurons, we analyzed their development in primary microexplant cultures of the early postnatal cerebellar cortex. These provide a well-defined, patterned lattice within which the development of individual cells is readily accessible to experimental manipulation and observation. Pax-2-positive precursors of inhibitory interneurons were found to effectively segregate from granule cell perikarya. They emigrate from the core explant and avoid the vicinity of granule cells, which also emigrate and aggregate into small clusters around the explant proper. This contrasts with the behavior of Purkinje neurons, which remain within the explant proper. During migration, a subset of Pax-2-positive cells gradually acquires a GABAergic phenotype, and subsequently also expresses the type 2 metabotropic receptor for glutamate, or parvalbumin, markers for Golgi neurons and basket or stellate cells, respectively. The latter eventually orient their dendrites such that they take a preferentially perpendicular orientation relative to granule cell axons. Both the neurochemical maturation of basket/stellate cells and the specific orientation of their dendrites are independent of their continuous contact with radially oriented glia or Purkinje cell dendrites projecting from the core explant. Numbers of parvalbumin-positive basket/stellate cells and the prevalence of glutamate-positive neurites, which form a dense network preferentially within cell clusters containing granule cell perikarya and their dendrites, are subject to regulation by chronic depolarization. In contrast, brain-derived neurotrophic factor results in a drastic decrease of numbers of basket/stellate cells. These findings document that granule cell axons (parallel fibers) are the major determinant of basket/stellate cell dendritic orientation. They also show that the neurochemical maturation of cerebellar interneurons is sensitive to regulation by activity and neurotrophic factors.

Animals↗
PubMed2003

Spatiotemporal transcription of connexin45 during brain development results in neuronal expression in adult mice.

Characterization of the expression pattern of connexins in neural tissue is a necessary prerequisite for understanding the functional relevance of the corresponding gap junction channels in brain. Here we describe the cell type-specific expression of connexin45 in the CNS and the spatiotemporal expression pattern from embryonic day 19.5 to adult brain using a recently described connexin45 LacZ-reporter mouse. The connexin45 gene is highly expressed during embryogenesis and up to 2 weeks after birth in nearly all brain regions. Afterward its expression is restricted to the thalamus, the CA3 region of hippocampus and the cerebellum. In adult mouse brain, the pattern of LacZ-staining in combination with the analysis of different neuronal and glial marker proteins strongly suggests that connexin45 is expressed in neurons, but presumably not in astrocytes or mature oligodendrocytes. Expression of the LacZ/connexin45 reporter gene in subsets of neurons, such as cerebral cortical, hippocampal and thalamic neurons as well as basket and stellate cells of cerebellum should be corroborated by functional investigations of connexin45 protein in electrical synapses. Based on its expression pattern during development, we suggest that the connexin45-containing gap junction channels have a rather ubiquitous role during brain development and may contribute to functional specification in certain subsets of neurons in the adult brain.

Aging↗
PubMed2002

Phenotypic features of myoclonus-dystonia in three kindreds.

BACKGROUND: Myoclonus-dystonia (M-D) is a movement disorder with involuntary jerks and dystonic contractions. Autosomal dominant alcohol-responsive M-D is associated with mutations in the epsilon-sarcoglycan gene (SGCE) (six families) and with a missense change in the D2 dopamine receptor (DRD2)gene (one family). OBJECTIVE: To investigate the clinical phenotype associated with M-D including motor symptoms, psychiatric disorders, and neuropsychological deficits. METHODS: Fifty individuals in three M-D families were evaluated and a standardized neurologic examination and DNA analysis were performed. Psychiatric profiles were established with the Diagnostic Interviews for Genetic Studies (DIGS) and the Yale-Brown Obsessive-Compulsive Scale (YBOCS). Cognition was evaluated with standardized neuropsychological tests. RESULTS: Distinct truncating mutations in the SGCE gene were identified in each family. Additionally, a missense alteration in the DRD2 gene was previously found in one family. Motor expression was variable, with onset of myoclonus or dystonia or both affecting the upper body and progression to myoclonus and dystonia in most cases. Psychiatric profiles revealed depression, obsessive-compulsive disorder, substance abuse, anxiety/panic/phobic disorders, and psychosis in two families, and depression only in the third family. Averaged scores from cognitive testing showed impaired verbal learning and memory in one family, impaired memory in the second family, and no cognitive deficits in the third family. CONCLUSIONS: Cognitive deficits may be associated with M-D. Psychiatric abnormalities correlate with the motor symptoms in affected individuals. Assessment of additional M-D families with known mutations is needed to determine whether these are characteristic phenotypic manifestations of M-D.

Adult↗
PubMed2002

Hepatic veno-occlusive disease (VOD) with complete occlusion of liver venules after tandem autologous stem cell transplantation-- successful treatment with high-dose methylprednisolone and defibrotide.

Veno-occlusive disease (VOD) is a life-threatening complication following allogeneic or autologous stem cell transplantation. We report on a patient with a high grade B-cell lymphoma who presented 28 days after the second autologous stem cell transplantation with weight gain, ascites, hyperbilirubinemia, and liver venules occlusion as demonstrated by sonography. Starting with high-dose methylprednisolone treatment followed by defibrotide maintenance therapy the patient showed dramatic complete response of VOD, resulting in a normal sonography of the liver and normalization of laboratory values. The response of the occlusion of nearly all liver venules underlines the value of anti-inflammatory treatment combined with new thrombolytic medication such as defibrotide for the treatment of severe VOD.

Adult↗
PubMed2002

Myoclonus dystonia: possible association with obsessive-compulsive disorder and alcohol dependence.

BACKGROUND: Inherited myoclonus-dystonia (M-D) is a disorder that is characterized primarily by myoclonic jerks and is often accompanied by dystonia. In addition to motor features, psychiatric disease is reported in some families. METHODS: To determine whether the same genetic etiology underlies both neurologic and psychiatric signs, the authors studied psychiatric symptoms in nonmanifesting carriers (NMC), noncarriers (NC), and manifesting carriers (MC) in three families demonstrating linkage of M-D to the 7q21 locus. Interviewers administered the computerized version of the Composite International Diagnostic Interview. Algorithms for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnosis of obsessive-compulsive disorder (OCD), generalized anxiety disorder, major affective disorder, alcohol abuse, alcohol dependence, drug abuse, and drug dependence were used. Rates of disorders among the MC, NMC, and NC were compared. RESULTS: Of 55 participating individuals, 16 were MC, 11 were NMC, and 28 were NC. The rate of OCD was greater in carriers (5/27) compared with NC (0/28) (p = 0.023). It was also greater in the symptomatic gene carriers (4/16) compared with the asymptomatic group (1/11) (p = 0.022). Alcohol dependence was increased in the symptomatic carriers (7/16) (p = 0.027), but not in the carrier group overall (7/27). CONCLUSION: OCD may be associated with the DYT11 M-D gene; however, a larger sample is necessary to confirm this finding. Alcohol dependence is highly associated with expressing symptoms of M-D. This may be explained by self-medication with alcohol to improve motor symptoms of M-D.

Adolescent↗
PubMed2001

Modulation of human T cell responses and macrophage functions by onchocystatin, a secreted protein of the filarial nematode Onchocerca volvulus.

Immune responses of individuals infected with filarial nematodes are characterized by a marked cellular hyporesponsiveness and a shift of the cytokine balance toward a Th2/Th3 response. This modulation of cellular immune responses is considered as an important mechanism to avoid inflammatory immune responses that could eliminate the parasites. We investigated the immunomodulatory potential of a secreted cysteine protease inhibitor (onchocystatin) of the human pathogenic filaria Onchocerca volvulus. Recombinant onchocystatin (rOv17), a biologically active cysteine protease inhibitor that inhibited among others the human cysteine proteases cathepsins L and S, suppressed the polyclonally stimulated and the Ag-driven proliferation of human PBMC. Stimulated as well as unstimulated PBMC in the presence of rOv17 produced significantly more IL-10, which was paralleled in some situations by a decrease of IL-12p40 and preceded by an increase of TNF-alpha. At the same time, rOv17 reduced the expression of HLA-DR proteins and of the costimulatory molecule CD86 on human monocytes. Neutralization of IL-10 by specific Abs restored the expression of HLA-DR and CD86, whereas the proliferative block remained unaffected. Depletion of monocytes from the PBMC reversed the rOv17-induced cellular hyporeactivity, indicating monocytes to be the target cells of immunomodulation. Therefore, onchocystatin has the potential to contribute to a state of cellular hyporesponsiveness and is a possible pathogenicity factor essential for the persistence of O. volvulus within its human host.

Animals↗
PubMed2001

Functional expression of the new gap junction gene connexin47 transcribed in mouse brain and spinal cord neurons.

A new mouse gap junction gene that codes for a protein of 46,551 Da has been identified and designated connexin47 (Cx47). It mapped as a single-copy gene to mouse chromosome 11. In human HeLa cells and Xenopus oocytes, expression of mouse Cx47 or a fusion protein of Cx47 and enhanced green fluorescent protein induced intercellular channels that displayed strong sensitivity to transjunctional voltage. Tracer injections in Cx47-transfected HeLa cells revealed intercellular diffusion of neurobiotin, Lucifer yellow, and 4',6-diamidino-2-phenylindole. Recordings of single channels yielded a unitary conductance of 55 pS main state and 8 pS substate. Cx47 mRNA expression was high in spinal cord and brain but was not found in retina, liver, heart, and lung. A low level of Cx47 expression was detected in ovaries. In situ hybridizations demonstrated high expression in alpha motor neurons of the spinal cord, pyramidal cells of the cortex and hippocampus, granular and molecular layers of the dentate gyrus, and Purkinje cells of the cerebellum as well as several nuclei of the brainstem. This expression pattern is distinct from, although partially overlapping with, that of the neuronally expressed connexin36 gene. Thus, electrical synapses in adult mammalian brain are likely to consist of different connexin proteins depending on the neuronal subtype.

Animals↗
PubMed2001

Developmental expression of heterotrimeric G-proteins in the murine cerebellar cortex.

We utilized the murine cerebellum to analyze the expression of G-proteins during vertebrate neural differentiation. Combining reverse transcription-polymerase chain reaction and immunocytochemistry, we monitored the expression and cellular localization, within the nascent cerebellar cortex, of G-proteins subunits known to mediate signal transduction in the adult cerebellum. The mRNAs encoding subunits Galphaq, Galphao, Galphai-2, and Galphaz are expressed in the cerebellar anlage at least from embryonic day 14 onward, and relative levels of these mRNAs do not change appreciably from E14 to adulthood. Galphao, Galphaz, and Galphai-2 could be localized to granule cell neuroblasts and postmigratory, mature granule cells, but not to early postmitotic, premigratory, and migrating granule neurons. All of the Galpha subunits analyzed could also be localized to the cell somata of postmitotic Purkinje neurons, irrespective of age. In contrast, Purkinje cell dendrites stained for Galphao only up to postnatal day 8, dendritic immunoreactivity for Galphaz increased during dendritogenesis, and appreciable levels of Galphai-2 and Galphaq were seen in Purkinje cell dendrites only transiently during the 2nd and 3rd postnatal week. Of the G-beta and -gamma subunits analyzed (beta1, beta2, gamma2, gamma3, gamma5, and gamma7), only expression of gamma3 varied with development. It could be localized to Purkinje cell somata and dendrites in early postnatal, but not in adult animals. These changes in the cellular distribution and subcellular segregation of G-proteins are correlated to tangible aspects of cerebellar cortical histogenesis and suggest a role for G-protein-mediated signaling in their mechanistic implementation.

Age Factors↗
PubMed2001

Novel lamin A/C mutations in two families with dilated cardiomyopathy and conduction system disease.

BACKGROUND: The LMNA gene, one of 6 autosomal disease genes implicated in familial dilated cardiomyopathy, encodes lamins A and C, alternatively spliced nuclear envelope proteins. Mutations in lamin A/C cause 4 diseases: Emery-Dreifuss muscular dystrophy, limb girdle muscular dystrophy type 1B, Dunnigan-type familial partial lipodystrophy, and dilated cardiomyopathy. METHODS AND RESULTS: Two 4-generation white families with autosomal dominant familial dilated cardiomyopathy and conduction system disease were found to have novel mutations in the rod segment of lamin A/C. In family A a missense mutation (nucleotide G607A, amino acid E203K) was identified in 14 adult subjects; disease was manifest as progressive conduction disease in the fourth and fifth decades. Death was caused by heart failure. In family B a nonsense mutation (nucleotide C673T, amino acid R225X) was identified in 10 adult subjects; disease was also manifest as progressive conduction disease but with earlier onset (third and fourth decades), ventricular dysrhythmias, left ventricular enlargement, and systolic dysfunction. Death was caused by heart failure and sudden cardiac death. Skeletal muscle disease was not observed in either family. CONCLUSIONS: Novel rod segment mutations in lamin A/C cause variable conduction system disease and dilated cardiomyopathy without skeletal myopathy.

Adult↗
PubMed2001

Folding incompetence of cathepsin L-like cysteine proteases may be compensated by the highly conserved, domain-building N-terminal extension of the proregion.

Folding of cathepsins L and S depend upon their proregion which extends the enzyme part by about 100 amino acids. Only a minority of the prosequence follows the structural template provided by the enzyme part; the majority forms an autonomous minidomain fairly distant from the active site cleft. We suggest that this prodomain may be the structural correlate of a foldase function of the proregion within the cathepsin L-like subfamily of papain-type cysteine proteases and report on a functional approach supporting this hypothesis.

Cathepsin L↗
PubMed2000

A major locus for myoclonus-dystonia maps to chromosome 7q in eight families.

Myoclonus-dystonia (M-D) is an autosomal dominant disorder characterized by myoclonic and dystonic muscle contractions that are often responsive to alcohol. The dopamine D2 receptor gene (DRD2) on chromosome 11q has been implicated in one family with this syndrome, and linkage to a 28-cM region on 7q has been reported in another. We performed genetic studies, using eight additional families with M-D, to assess these two loci. No evidence for linkage was found for 11q markers. However, all eight of these families showed linkage to chromosome 7 markers, with a combined multipoint LOD score of 11.71. Recombination events in the families define the disease gene within a 14-cM interval flanked by D7S2212 and D7S821. These data provide evidence for a major locus for M-D on chromosome 7q21.

Chromosome Mapping↗
PubMed2000

The alpha1/2 helical backbone of the prodomains defines the intrinsic inhibitory specificity in the cathepsin L-like cysteine protease subfamily.

Proregions of papain-like cysteine proteases are potent and often highly selective inhibitors of their parental enzymes. The molecular basis of their selectivity is poorly understood. For two closely related members of the cathepsin L-like subfamily we established strong selectivity differences. The propeptide of cathepsin S was observed to inhibit cathepsin L with a K(i) of 0.08 nM, yet cathepsin L propeptide inhibited cathepsin S only poorly. To identify the respective structural correlates we engineered chimeric propeptides and compared their inhibitory specificity with the wild-types. Specificity resided in the N-terminal part, strongly suggesting that the backbone of the prodomain was the underlying structure.

Amino Acid Sequence↗
PubMed2000

Spatial and temporal changes in natural and target deprivation-induced cell death in the mouse inferior olive.

The survival of inferior olive neurons is dependent on contact with cerebellar Purkinje cells. There is evidence that this dependence changes with time. Because inferior olivary axons, called climbing fibers, already show significant topographical ordering in cerebellar target zones during late embryogenesis in mice, the question arises as to whether olive neurons are dependent on target Purkinje cells for their survival at this early age. To better characterize this issue, inferior olive development was studied in two transgenic mouse mutants, wnt-1 and L7ADT, with embryonic and early postnatal loss of cerebellar target cells, respectively, and compared to that in the well-studied mutant, Lurcher. Morphological criteria as well as quantitative measures of apoptosis were considered in this developmental analysis. Survival of inferior olive neurons is observed to be independent of Purkinje cells throughout embryogenesis, but dependence begins immediately at birth in both wild types and mutants. Thereafter, wild types and mutants show a rapid increase in olive cell apoptosis, with a peak at postnatal day 4, followed by a period of low-level, but significant, apoptosis that continues to at least postnatal day 11; the main difference is that apoptosis is quantitatively enhanced in the mutants compared to wild types. The multiphasic course of these effects roughly parallels the known phases of climbing fiber synaptogenesis. In addition, despite significant temporal differences among the mutants with respect to absolute numbers of dying cells, there are common spatial features suggestive of distinct intrinsic programs linking different olivary subnuclei to their targets.

Animals↗
PubMed2000

Changing subcellular distribution and activity-dependent utilization of a dendritically localized mRNA in developing Purkinje cells.

In cerebellar Purkinje neurons, the degree of dendritic segregation of the Purkinje cell-specific mRNA L7/pcp-2 is correlated with their development and synaptic investment. This developmental pattern is also observed in Purkinje cells in primary dissociated culture. Short-term (12-48 h) stimulation of cultured Purkinje cells by potassium-induced depolarization or blockade of their inhibitory GABAergic input results in an increased incidence of Purkinje cells with L7/pcp-2 mRNA-positive dendrites and increased levels of L7 protein expression, the latter by a posttranscriptional mechanism. None of these treatments affected the localization of the mRNA encoding calbindin D28k nor the level of this protein in Purkinje neurons. Protracted exposure to depolarizing levels of potassium or elimination of GABAergic transmission resulted in conspicuous changes of Purkinje cell dendritic morphology. These data suggest a scenario in which activity-driven translation of subcellularly segregated mRNAs may contribute to the developmental and functional plasticity of nerve cells.

Animals↗
PubMed2000

Brain-derived neurotrophic factor modulates dendritic morphology of cerebellar basket and stellate cells: an in vitro study.

The dendrites of cerebellar basket/stellate cells show a highly stereotyped orientation relative to granule cell axons (parallel fibers) and Purkinje cell dendrites. This specific morphology is acquired during the early postnatal phase of cerebellar development, when basket/stellate cells become synaptically integrated with Purkinje neurons and granule cells. In the present study, we used primary cerebellar cultures to test how the spatial arrangement of granule cell axons affects basket/stellate cell dendritic morphology. In addition, we sought to determine whether active signals as might be provided by granule cells, i.e. synaptic input and the neurotrophin, brain-derived neurotrophic factor, affect basket/stellate cell development. Our results confirm the critical role of parallel fiber orientation for basket/stellate dendritic morphogenesis. Moreover, we found that both electrical activity and brain-derived neurotrophic factor increased basket and stellate cell dendritic arborization. Together with previously published findings, our data led to the conclusion that both structural cues and active interneuronal signaling collaborate to bring about the precise morphogenesis of cerebellar basket/stellate cells. The distinct responses of various cerebellar phenotypes towards the morphogenetic effects of brain-derived neurotrophic factor suggest that this neurotrophin, within the developing cerebellum, enhances synaptic connectivity by concerting the formation of appropriate pre- and postsynaptic structures.

Animals↗