Showing papers by "University of Marburg published in 1996"

Femtomole sequencing of proteins from polyacrylamide gels by nano-electrospray mass spectrometry

Abstract: Molecular analysis of complex biological structures and processes increasingly requires sensitive methods for protein sequencing. Electrospray mass spectrometry has been applied to the high-sensitivity sequencing of short peptides, but technical difficulties have prevented similar success with gel-isolated proteins. Here we report a simple and robust technique for the sequencing of proteins isolated by polyacrylamide gel electrophoresis, using nano-electrospray tandem mass spectrometry. As little as 5 ng protein starting material on Coomassie- or silver-stained gels can be sequenced. Multiple-sequence stretches of up to 16 amino acids are obtained, which identify the protein unambiguously if already present in databases or provide information to clone the corresponding gene. We have applied this method to the sequencing and cloning of a protein which inhibits the proliferation of capillary endothelial cells in vitro and thus may have potential antiangiogenic effects on solid tumours.

Seed banks and seed dispersal: important topics in restoration ecology

Abstract: Restoration ecology deals with the scientific and ecological background of nature management practices aiming at the re-establishment of plant species which have disappeared. As we focus on semi-natural landscapes, these disappearances can be caused by intensification of agricultural practices or cessation of human interference. Nature management practices attempt to re-establish the often species-rich original plant communities by the removal of nutrients (sod cutting, hay-making, grazing) after eutrophication (Schiefer 1984; Bobbink & Willems 1991; Oomes 1992; Bakker & OUT 1995), rewetting after severe drainage (Grootjans & Van Diggelen 1995; Koerselman & Verhoeven 1995), scrub and woodland removal (clear cutting, grazing) after bush encroachment (Willems 1988; Poschlod & Jordan 1992). The re-appearance of plant species may depend on their persistence in the soil seed bank as a ‘memory’ of the original plant community. If the species has been lost from the persistent soil seed bank, it has to be transported to the site of re-appearance by some vector, e.g. wind, water, animals, man, and incorporated into the fresh seed bank. The site of re-appearance after emerging either from the old seed bank or from the fresh seed bank has to be proven to be a safe site from the point of view of abiotic and biotic conditions (Harper 1977). Without the presence or arrival of seeds no re-appearance in the established vegetation will be possible. For this reason we focus on seed bank dynamics and seed dispersal in restoration ecology. We will present (i) a review of current methods of seed bank analysis including estimations of longevity and density, and (ii) the state of the art on methods and results of seed dispersal.

Gastric emptying and release of incretin hormones after glucose ingestion in humans.

Abstract: This study investigated in eight healthy male volunteers (a) the gastric emptying pattern of 50 and 100 grams of glucose; (b) its relation to the phase of interdigestive motility (phase I or II) existing when glucose was ingested; and (c) the interplay between gastric emptying or duodenal perfusion of glucose (1.1 and 2.2 kcal/min; identical total glucose loads as orally given) and release of glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1(7-36)amide (GLP-1), C-peptide, insulin, and plasma glucose. The phase of interdigestive motility existing at the time of glucose ingestion did not affect gastric emptying or any metabolic parameter. Gastric emptying of glucose displayed a power exponential pattern with a short initial lag period. Duodenal delivery of glucose was not constant but exponentially declined over time. Increasing the glucose load reduced the rate of gastric emptying by 27.5% (P < 0.05) but increased the fractional duodenal delivery of glucose. Both glucose loads induced a fed motor pattern which was terminated by an antral phase III when approximately 95% of the meal had emptied. Plasma GLP-1 rose from basal levels of approximately 1 pmol/liter of peaks of 3.2 +/- 0.6 pmol/liter with 50 grams of glucose and of 7.2 +/- 1.6 pmol/liter with 100 grams of glucose. These peaks occurred 20 min after glucose intake irrespective of the load. A duodenal delivery of glucose exceeding 1.4 kcal/min was required to maintain GLP-1 release in contrast to ongoing GIP release with negligibly low emptying of glucose. Oral administration of glucose yielded higher GLP-1 and insulin releases but an equal GIP release compared with the isocaloric duodenal perfusion. We conclude that (a) gastric emptying of glucose displays a power exponential pattern with duodenal delivery exponentially declining over time and (b) a threshold rate of gastric emptying of glucose must be exceeded to release GLP-1, whereas GIP release is not controlled by gastric emptying.

Interaction of Steroid Hormone Receptors with the Transcription Initiation Complex

Abstract: I. Introduction REGULATION of gene expression by steroid hormones is a traditional field of molecular endocrinology. The hormones act by binding to intracellular receptors, which themselves orchestrate the transcriptional response. After the cloning of the hormone receptors and the identification of their target sequences on DNA at the end of the 1980s, the question of how steroid hormones modulate the activity of various genes in target cells seemed to be solved. It was clear that steroid hormone receptors are ligand-activated transcriptional modulators, which in most cases act through binding to specific sequences on DNA called hormone-responsive elements (HREs) (1). Careful mutational analysis identified a modular structure of the receptors composed of a DNA-binding domain, nuclear localization signals, a ligand-binding domain, and several transactivation domains (2). Interactions of the receptors with components of the basal transcriptional machinery and with sequence-specific transcription factors we...

An asymptotically optimal multiversion B-tree

Abstract: In a variety of applications, we need to keep track of the development of a data set over time. For maintaining and querying these multiversion data efficiently, external storage structures are an absolute necessity. We propose a multiversion B-tree that supports insertions and deletions of data items at the current version and range queries and exact match queries for any version, current or past. Our multiversion B-tree is asymptotically optimal in the sense that the time and space bounds are asymptotically the same as those of the (single-version) B-tree in the worst case. The technique we present for transforming a (single-version) B-tree into a multiversion B-tree is quite general: it applies to a number of hierarchical external access structures with certain properties directly, and it can be modified for others.

Electronic Structure of Stable Carbenes, Silylenes, and Germylenes

Abstract: Quantum mechanical ab initio calculations at the MP4/6-311G(d,p)//MP2/6-31G(d) level of theory have been carried out for the parent compounds of the stable carbenes imidazol-2-ylidene (1) and the silylene (8) and germylene (9) analogues. The energies of hydrogenation of 1, 8, and 9 and the structures of the saturated derivatives 2, 10, and 11 have also been calculated. The analysis of the electronic structure shows clearly that the higher stability of 1 than that of 2 is caused by the enhanced pπ−pπ delocalization. However, a strong π-donor stabilization of the carbene pπ orbital by the nitrogen lone pairs is found already in the C−C-saturated imidazolin-2-ylidene 2. This explains why the N-mesityl derivative of 2, which is sterically protected against dimerization, could recently be synthesized. Also the silylene and germylene systems 8 and 9 are stabilized by enhanced pπ−pπ delocalization. The method of electron density mapping as used by Arduengo et al. (J. Am. Chem. Soc. 1994, 116, 6812) as evidence f...

Plectin deficiency results in muscular dystrophy with epidermolysis bullosa

Abstract: We report that mutation in the gene for plectin, a cytoskeleton–membrane anchorage protein, is a cause of autosomal recessive muscular dystrophy associated with skin blistering (epidermolysis bullosa simplex). The evidence comes from absence of plectin by antibody staining in affected individuals from four families, supportive genetic analysis (localization of the human plectin gene to chromosome 8q24.13–qter and evidence for disease segregation with markers in this region) and finally the identification of a homozygous frameshift mutation detected in plectin cDNA. Absence of the large multifunctional cytoskeleton protein plectin can simultaneously account for structural failure in both muscle and skin.

Visualization of the vesicular acetylcholine transporter in cholinergic nerve terminals and its targeting to a specific population of small synaptic vesicles

Abstract: Immunohistochemical visualization of the rat vesicular acetylcholine transporter (VAChT) in cholinergic neurons and nerve terminals has been compared to that for choline acetyltransferase (ChAT), heretofore the most specific marker for cholinergic neurons. VAChT-positive cell bodies were visualized in cerebral cortex, basal forebrain, medial habenula, striatum, brain stem, and spinal cord by using a polyclonal anti-VAChT antiserum. VAChT-immuno-reactive fibers and terminals were also visualized in these regions and in hippocampus, at neuromuscular junctions within skeletal muscle, and in sympathetic and parasympathetic autonomic ganglia and target tissues. Cholinergic nerve terminals contain more VAChT than ChAT immunoreactivity after routine fixation, consistent with a concentration of VAChT within terminal neuronal arborizations in which secretory vesicles are clustered. These include VAChT-positive terminals of the median eminence or the hypothalamus, not observed with ChAT antiserum after routine fixation. Subcellular localization of VAChT in specific organelles in neuronal cells was examined by immunoelectron microscopy in a rat neuronal cell line (PC 12-c4) expressing VAChT as well as the endocrine and neuronal forms of the vesicular monoamine transporters (VMAT1 and VMAT2). VAChT is targeted to small synaptic vesicles, while VMAT1 is found mainly but not exclusively on large dense-core vesicles. VMAT2 is found on large dense-core vesicles but not on the small synaptic vesicles that contain VAChT in PC12-c4 cells, despite the presence of VMAT2 immunoreactivity in central and peripheral nerve terminals known to contain monoamines in small synaptic vesicles. Thus, VAChT and VMAT2 may be specific markers for "cholinergic" and "adrenergic" small synaptic vesicles, with the latter not expressed in nonstimulated neuronally differentiated PC12-c4 cells.

Induction of tachykinin gene and peptide expression in guinea pig nodose primary afferent neurons by allergic airway inflammation.

Abstract: Substance P (SP), neurokinin A (NKA), and calcitonin gene-related peptide (CGRP) have potent proinflammatory effects in the airways. They are released from sensory nerve endings originating in jugular and dorsal root ganglia. However, the major sensory supply to the airways originates from the nodose ganglion. In this study, we evaluated changes in neuropeptide biosynthesis in the sensory airway innervation of ovalbumin-sensitized and -challenged guinea pigs at the mRNA and peptide level. In the airways, a three- to fourfold increase of SP, NKA, and CGRP, was seen 24 h following allergen challenge. Whereas no evidence of local tachykinin biosynthesis was found 12 h after challenge, increased levels of preprotachykinin (PPT)-A mRNA (encoding SP and NKA) were found in nodose ganglia. Quantitative in situ hybridization indicated that this increase could be accounted for by de novo induction of PPT-A mRNA in nodose ganglion neurons. Quantitative immunohistochemistry showed that 24 h after challenge, the number of tachykinin-immunoreactive nodose ganglion neurons had increased by 25%. Their projection to the airways was shown. Changes in other sensory ganglia innervating the airways were not evident. These findings suggest that an induction of sensory neuropeptides in nodose ganglion neurons is crucially involved in the increase of airway hyperreactivity in the late response to allergen challenge.

Cold shock stress-induced proteins in Bacillus subtilis.

Abstract: Bacteria respond to a decrease in temperature with the induction of proteins that are classified as cold-induced proteins (CIPs). Using two-dimensional gel electrophoresis, we analyzed the cold shock response in Bacillus subtilis. After a shift from 37 to 15 degrees C the synthesis of a majority of proteins was repressed; in contrast, 37 proteins were synthesized at rates higher than preshift rates. One hour after cold shock, the induction of CIPs decreased, and after 2 h, general protein synthesis resumed. The identified main CIPs were excised from two-dimensional gels and were subjected to microsequencing. Three small acidic proteins that showed the highest relative induction after cold shock were highly homologous and belonged to a protein family of which one member, the major cold shock protein, CspB, has previously been characterized. Two-dimensional gel analyses of a cspB null mutant revealed that CspB affects the level of induction of several CIPs. Other identified CIPs function at various levels of cellular physiology, such as chemotaxis (CheY), sugar uptake (Hpr), translation (ribosomal proteins S6 and L7/L12), protein folding (PPiB), and general metabolism (CysK, Ilvc, Gap, and triosephosphate isomerase).

Phase diagrams for sonoluminescing bubbles

Abstract: Sound driven gas bubbles in water can emit light pulses This phenomenon is called sonoluminescence (SL) Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL We present phase diagrams in the gas concentration versus forcing pressure state space and also in the ambient radius versus gas concentration and versus forcing pressure state spaces These phase diagrams are based on the thresholds for energy focusing in the bubble and two kinds of instabilities, namely (i) shape instabilities and (ii) diffusive instabilities Stable SL only occurs in a tiny parameter window of large forcing pressure amplitude Pa~12?15 atm and low gas concentration of less than 04% of the saturation The upper concentration threshold becomes smaller with increased forcing Our results quantitatively agree with experimental results of Putterman's UCLA group on argon, but not on air However, air bubbles and other gas mixtures can also successfully be treated in this approach if in addition (iii) chemical instabilities are considered All statements are based on the Rayleigh?Plesset ODE approximation of the bubble dynamics, extended in an adiabatic approximation to include mass diffusion effects This approximation is the only way to explore considerable portions of parameter space, as solving the full PDEs is numerically too expensive Therefore, we checked the adiabatic approximation by comparison with the full numerical solution of the advection diffusion PDE and find good agreemen

The snRNP core assembly pathway: identification of stable core protein heteromeric complexes and an snRNP subcore particle in vitro.

Abstract: Stable association of the eight common Sm proteins with U1, U2, U4 or U5 snRNA to produce a spliceosomal snRNP core structure is required for snRNP biogenesis, including cap hypermethylation and nuclear transport. Here, the assembly of snRNP core particles was investigated in vitro using both native HeLa and in vitro generated Sm proteins. Several RNA-free, heteromeric protein complexes were identified, including E.F.G, B/B'.D3 and D1.D2.E.F.G. While the E.F.G complex alone did not stably bind to U1 snRNA, these proteins together with D1 and D2 were necessary and sufficient to form a stable U1 snRNP subcore particle. The subcore could be chased into a core particle by the subsequent addition of the B/B'.D3 protein complex even in the presence of free competitor U1 snRNA. Trimethylation of U1 snRNA's 5' cap, while not observed for the subcore, occurred in the stepwise-assembled U1 snRNP core particle, providing evidence for the involvement of the B/B' and D3 proteins in the hypermethylation reaction. Taken together, these results suggest that the various protein heterooligomers, as well as the snRNP subcore particle, are functional intermediates in the snRNP core assembly pathway.

Filovirus-induced endothelial leakage triggered by infected monocytes/macrophages.

Abstract: The pathogenetic mechanisms underlying hemorrhagic fevers are not fully understood, but hemorrhage, activation of coagulation, and shock suggest vascular instability. Here, we demonstrate that Marburg virus (MBG), a filovirus causing a severe form of hemorrhagic fever in humans, replicates in human monocytes/macrophages, resulting in cytolytic infection and release of infectious virus particles. Replication also led to intracellular budding and accumulation of viral particles in vacuoles, thus providing a mechanism by which the virus may escape immune surveillance. Monocytes/macrophages were activated by MBG infection as indicated by tumor necrosis factor alpha (TNF-alpha) release. Supernatants of monocyte/macrophage cultures infected with MBG increased the permeability of cultured human endothelial cell monolayers. The increase in endothelial permeability correlated with the time course of TNF-alpha release and was inhibited by a TNF-alpha specific monoclonal antibody. Furthermore, recombinant TNF-alpha added at concentrations present in supernatants of virus-infected macrophage cultures increased endothelial permeability in the presence of 10 micron H2O2. These results indicate that TNF-alpha plays a critical role in mediating increased permeability, which was identified as a paraendothelial route shown by formation of interendothelial gaps. The combination of viral replication in endothelial cells (H.-J. Schnittler, F. Mahner, D. Drenckhahn, H.-D. Klenk, and H. Feldmann, J. Clin. Invest. 19:1301-1309, 1993) and monocytes/macrophages and the permeability-increasing effect of virus-induced cytokine release provide the first experimental data for a novel concept in the pathogenesis of viral hemorrhagic fever.

Protection against atherogenesis in mice mediated by human apolipoprotein A-IV.

Abstract: Apolipoproteins are protein constituents of plasma lipid transport particles. Human apolipoprotein A-IV (apoA-IV) was expressed in the liver of C57BL/6 mice and mice deficient in apoE, both of which are prone to atherosclerosis, to investigate whether apoA-IV protects against this disease. In transgenic C57BL/6 mice on an atherogenic diet, the serum concentration of high density lipoprotein (HDL) cholesterol increased by 35 percent, whereas the concentration of endogenous apoA-I decreased by 29 percent, relative to those in transgenic mice on a normal diet. Expression of human apoA-IV in apoE-deficient mice on a normal diet resulted in an even more severe atherogenic lipoprotein profile, without affecting the concentration of HDL cholesterol, than that in nontransgenic apoE-deficient mice. However, transgenic mice of both backgrounds showed a substantial reduction in the size of atherosclerotic lesions. Thus, apoA-IV appears to protect against atherosclerosis by a mechanism that does not involve an increase in HDL cholesterol concentration.

Some like it cold: response of microorganisms to cold shock

Abstract: Bacteria respond to an abrupt decrease in temperature with a specific response, in which cold-induced proteins (CIPs) are transiently expressed at a higher level Employing two-dimensional gel electrophoresis, several CIPs have been identified In spite of this, the overall function of the cold shock response is unclear Recently, the main attention has focused on a group of conserved cold shock proteins (CSPs) that have been shown to have the highest induction after cold shock and to play a major regulatory role in the physiology of adaptation to low temperatures CSPs, of which Escherichia coli, Bacillus subtilis, and B cereus possess a family comprising at least 3-7 proteins, are small acidic proteins that share over 45% of sequence identity Recent evidence suggests that members of this wide-spread protein family can function both at the transcriptional and translational level in vitro However, the exact mode of action has yet to be established In addition, post-transcriptional regulation seems to play a major role in the induction of CSPs, a process in which the ribosome may be involved This is in accordance with a model in which the ribosome has been proposed to be the sensor of temperature in bacteria

TGF-β1 Protects Hippocampal Neurons Against Degeneration Caused by Transient Global Ischemia: Dose-Response Relationship and Potential Neuroprotective Mechanisms

Abstract: Background and Purpose Transforming growth factor-β1 (TGF-β1) has been shown to rescue cultured neurons from excitotoxic and hypoxic cell death and to reduce infarct size after focal cerebral ischemia in mice and rabbits. The present study investigated the effects of TGF-β1 in a different pathophysiological setting and the delayed neuronal death of hippocampal pyramidal cells after transient global ischemia in rats, and evaluated the potential mechanisms of the neuroprotective activity of TGF-β1. Methods Transient forebrain ischemia was induced in male adult Wistar rats with bilateral occlusion of both common carotid arteries combined with systemic hypotension for 10 minutes. Seven days after ischemia, brains were perfusion-fixed and stained for histological evaluation. TGF-β1 or vehicle was injected intracerebroventricularly (ICV; 0.5, 4, and 50 ng) or intrahippocampally (4 ng) 1 hour before ischemia. For in vitro studies, hippocampal neurons were derived from E17 rat embryos and cultured for 10 to 14 da...

Clinical course, early diagnosis, treatment, and prevention of disease in glutaryl-CoA dehydrogenase deficiency.

Abstract: BackgroundGlutaryl-CoA dehydrogenase deficiency (GDD) is. recessively inheritedneurometabolic disorder associated with encephalopathic crises andsevere extrapyramidal symptoms. Treatment regimens including glucoseand electrolyte infusions during acute illnesses, oral carnitinesupplementation and/or a low-protein or lysine-restricted diet havebeen recommended, but their efficacy has been documented only on ananecdotal basis.Subjects and methodsWe conducted a retrospective analysis of 57 patients with provenGDD-relating appearance and severity of neurological disease to age andclinical status at diagnosis, glutaric acid levels in body fluids, anddifferent treatment regimens.ResultsThirty-six patients were diagnosed after the onset of neurologicaldisease (symptomatic group), twenty-one before (presymptomatic group).Carnitine levels were found to be reduced in all patients at diagnosis.In the symptomatic group, macrocephaly had been present around birthand was followed by rapid postnatal head growth in 70 % of thechildren. The patients often showed symptoms such as hypotonia,irritability, and jitteriness followed by an acute encephalopathiccrisis occurring on average at 12 months of age. Common neuroimagingfindings included frontotemporal atrophy, subependymal pseudocysts,delayed myelination, basal ganglia atrophy, chronic subdural effusionsand hematomas. In four patients the latter two findings were initiallymisinterpreted as resulting from child abuse. Other importantmisdiagnoses in older siblings who were affected and went undiagnosedinclude postencephalitic cerebral palsy, dystonic cerebral palsy andsudden infant death syndrome. Metabolic treatment did not convincinglyimprove the neurological disease, although it may have preventedfurther deterioration. Symptomatic treatment with baclofen orbenzodiazepines was effective in reducing muscle spasms.Children in the presymptomatic group were diagnosed because offamiliarity for the disease (n = 13), macrocephaly and/or additionalminor neurological signs in infancy (n = 6), or acute encephalopathy,which was fully reversible after prompt treatment (n = 2). Afterdiagnosis, all children were treated with oral carnitine, fluidinfusion during intercurrent illnesses and, in addition, a diet wasstarted in 13 of the 21 children. All 21 children except one (bornprematurely at 31 weeks) have continued to develop normally up to now.Mean age at report is 6.3 years with a range from 6 months to 14.8years. In older patients, the neuroradiological changes, present ininfancy as in the symptomatic patients, became less prominent and inone girl disappeared.ConclusionsIn presymptomatic children with GDD, the onset of neurological diseasecan be prevented by vigorous treatment of catabolic crises duringillnesses together with carnitine supplementation. The importance ofdietary therapy remains unclear and needs further evaluation. Thepotential treatability of GDD calls for increased attention to earlypresenting signs in order to recognize the disorder and to initiatetreatment before the onset of irreversible neurological disease.

Statistical analysis of the bidirectional inconsistency of spelling and sound in French

Abstract: Recent studies suggest that performance attendant on visual word perception is affected not only by the “traditional” feedforward inconsistency (spelling → phonology) but also by its feedback inconsistency (phonology → spelling). The present study presents a statistical analysis of the bidirectional inconsistency for all French monosyllabic words. We show that French is relatively consistent from spelling to phonology but highly inconsistent from phonology to spelling. Appendixes B and C list prior and conditional probabilities for all inconsistent mappings and thus provide a valuable tool for controlling, selecting, and constructing stimulus materials for psycholinguistic and neuropsychological research. Such large-scale statistical analyses about a language’s structure are crucial for developing metrics of inconsistency, generating hypotheses for cross-linguistic research, and building computational models of reading.

Facial Dominance of West Point Cadets as a Predictor of Later Military Rank

Abstract: Les AA. s'efforcent de montrer que l'apparence physique d'une personne affecte ses chances en matiere de reussite sociale. Ils affirment que ce type de perspective a ete negligee jusqu'a present. Ils proposent une etude de la physionomie faciale et du caractere dominant qu'elle reflete au travers de l'analyse des portraits des cadets de West Point. Ils estiment que cet aspect physique mis en evidence influe sur le long terme mais non a moyen terme sur les carrieres des futurs officiers

Risk of traffic accidents in patients with sleep-disordered breathing: reduction with nasal CPAP.

Abstract: Sleepiness whilst driving constitutes a road safety risk. Sleep-related breathing disorders are the most frequent medical cause of daytime sleepiness, and untreated patients with this condition have been shown to be at a higher risk of having accidents while driving. This study addressed the question of the extent to which treatment of sleep-disordered breathing by nasal continuous positive airway pressure (nCPAP) is related to changes in patient's accident risk. Seventy eight male patients requiring treatment of sleep-related breathing disorders with nCPAP were enrolled in the study. The protocol included a questionnaire dealing with alertness-related problems while driving, an 80 min vigilance test, and the Multiple Sleep Latency Test. These baseline evaluations were repeated after 1 year of treatment with nCPAP. Fifty nine patients completed the study. The accident rate was significantly decreased from 0.8 per 100,000 km (untreated) to 0.15 per 100,000 km with nCPAP treatment. Variables that were considered to be likely to increase accident risk (sleeping spells, fatigue, vigilance test reaction time, daytime sleep latency) also improved with treatment. We conclude that treatment of sleep-disordered breathing by nasal continuous positive airway pressure is related to reduction in patient motor vehicle accident rates, probably due to the reversal of excessive daytime sleepiness.

Fast Pulsing and Chaotic Itinerancy with a Drift in the Coherence Collapse of Semiconductor Lasers

Abstract: We report the first experimental observation of irregular picosecond light pulses within the coherence collapse of a semiconductor laser subject to delayed moderate optical feedback. This pulsing behavior agrees with the recent explanation of low frequency fluctuations as chaotic itinerancy with a drift. Theory and experiments show very good agreement.

Polynorbornene: synthesis, properties and simulations

Abstract: The vinylic polymerization of norbornenes upon catalysis with Pd2+ complexes with norbornylnitrile as ligands is reported. The polynorbornenes (Mw = 106) display a set of unique properties including a dense packing in the amorphous state, high glass transition temperatures, large refractive index, low birefringence and significant brittleness. To test the concept that these properties can be traced back to the conformational constraints of the polymer chains, we performed ab initio calculations, semi-empirical quantum mechanical calculations and force-field calculations employing a force field developed by us for polynorbornenes.