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Biomedical subjects

C Moll

Publications and source records attributed to C Moll.

16 recordsLinked to original sources

Cloning of a putative glutamate receptor: a low affinity kainate-binding subunit.

Kainate, a glutamate receptor agonist, is a potent neuroexcitatory agent that produces epileptiform activity and selective neuronal degeneration. Binding studies using neuronal membrane homogenates or brain sections have identified sites having either high or low affinity for [3H]kainate. Here we report the cloning of a gene, GluR7, with approximately 75% sequence identity with the previously cloned GluR5 and GluR6 subunit genes. Transcripts of the GluR7 gene are evident in brain areas that bind [3H]kainate and are susceptible to kainate-induced neurotoxicity. We have performed ligand binding studies with membranes of transfected HeLa cells expressing GluR6 or GluR7 subunits. Our data show that the GluR6 and GluR7 subunits have a rank order of agonist affinity (domoate greater than kainate much greater than L-glutamate, quisqualate much greater than AMPA, NMDA) and a dissociation constant for kainate (95 and 77 nM, respectively) characteristic of the low affinity kainate-binding sites described in the brain.

Amino Acid Sequence

Increase of sodium channels in demyelinated lesions of multiple sclerosis.

Redistribution of sodium channels along demyelinated pathways in multiple sclerosis (MS) could be an important event in restoring conduction prior to other reparative mechanisms such as remyelination. Sodium channels in human multiple sclerosis lesions were identified by quantitative light microscopic autoradiography using tritiated saxitoxin (STX), a highly specific sodium channel ligand. Demyelinated areas in various central nervous system regions containing denuded but vital axons exhibited a high increase of STX-binding sites by up to a factor of 4 as compared to normal human white matter. This important finding could explain aspects of fast clinical remissions and 'silent' MS lesions on functional and morphological properties. Demyelinated axons may functionally reorganize their membranes and adapt properties similar to those of slow conducting unmyelinated nerve fibres which have a higher amount and a more diffuse distribution of STX binding sites. This report is the first description of an altered distribution of voltage-sensitive sodium channels in human multiple sclerosis lesions.

Aged

Cloning of a novel glutamate receptor subunit, GluR5: expression in the nervous system during development.

We have isolated cDNAs encoding a glutamate receptor subunit, designated GluR5, displaying 40%-41% amino acid identity with the kainate/AMPA receptor subunits GluR1, GluR2, GluR3, and GluR4. This level of sequence similarity is significantly below the approximately 70% intersubunit identity characteristic of kainate/AMPA receptors. The GluR5 protein forms homomeric ion channels in Xenopus oocytes that are weakly responsive to L-glutamate. The GluR5 gene is expressed in subsets of neurons throughout the developing and adult central and peripheral nervous systems. During embryogenesis, GluR5 transcripts are detected in areas of neuronal differentiation and synapse formation.

Aging

Distribution of voltage-dependent Na+ channels identified by high-affinity receptors for tetrodotoxin and saxitoxin in rat and human brains: quantitative autoradiographic analysis.

The localization of a putative voltage-dependent Na+ channel in adult rat and human brain was studied by light microscopic quantitative autoradiography using a tritiated derivative of tetrodotoxin ([3H]enTTX) and tritiated saxitoxin [( 3H]STX). Equilibrium binding experiments in the whole rat brain gave dissociation constants of 7.0 nM ([3H]enTTX) and 5.0 nM ([3H]STX). The dissociation constant for the binding of [3H]STX in the different human brain regions was near 1.5 nM. Autoradiograms demonstrated a heterogeneous distribution of toxin binding sites in the brain with a very good correlation of the mapping of tetrodotoxin and saxitoxin receptors. With the exception of a few regions, the same type of cartography was observed for human and rat brain structures. If toxin receptors were present in all brain regions, their density was particularly important in cerebral cortex, hippocampus, lateral septum and molecular layer of cerebellar cortex. Conversely, the medulla oblongata contained only low amounts of binding sites.

Adult

[Schwannoma and neurofibroma of the neck].

Three schwannomas and one neurofibroma of the neck were treated surgically in our department during the last years (1980-1987). These tumors are relatively rare. The different clinical and histopathological criteria of the two tumors are discussed. In spite of these differences, in most cases a correct diagnosis is made only during surgery. Therefore, the possibility of temporary or permanent damage to major nerves is always present and the patient should be informed accordingly.

Adult

[Hereditary neuropathy with liability to pressure palsies. A contribution to the differential diagnosis of multiplex mononeuropathy].

Hereditary neuropathy with liability to pressure palsies could be diagnosed in two families. This little-known, dominantly inherited disorder is clinically characterised by recurring, spontaneously regressive palsies of peripheral nerves, mostly after minimal mechanical compression of the nerve concerned. It can be clearly differentiated from mononeuropathies of different pathogenesis even in clinically not involved nerves, by means of pathological neurographic findings and by the detection of pathognomonic myelinic thickenings in nerve biopsies. Prognosis is favourable if recurrences are avoided. This means that counselling of the patients and their families is of prophylactic significance.

Adult

Liver fibrosis in carbamoylphosphate synthetase deficiency.

Structural sequelae of inherited defects of the urea cycle in general, and their liver pathology in particular, are still not well understood. This holds true especially for the possible late effects in involved organs of patients now surviving longer because of more effective therapy. Some urea cycle defects may result in chronic and progressive liver damage, as has been reported. A peculiar type of liver fibrosis was observed in a girl with carbamoylphosphate synthetase deficiency, who survived for 1 year and 7 months. Hepatic fibrosis, or even cirrhosis, has been observed in argininosuccinic aciduria. Long-term survivors with urea cycle disorders may form a group at risk for the development of chronic fibrosing liver disease.

Carbon-Nitrogen Ligases

[Interactive microcomputer program for calculation and normal values for routine clinical neurophysiological research].

A BASIC program for a 128 KByte microcomputer is described which is deviced to support every day clinical neurophysiological investigations. It provides calculating routines and normal values with a hard copy print option for visual, auditory, and somatosensory evoked potentials, peripheral motor and sensory nerve conduction velocities, and needle EMG potential analysis. All important arm and leg nerves and muscles are included. By its simplicity the program gives easy access to changes according to individual requirements.

Computers

[Histomechanical studies on test specimens from hyaline cartilage under compressive loading with regard to rheology (author's transl)].

Modified rheological methods from high polymer physics (biorheology, historheology) have been applied to the testing of hyaline cartilage histomechanics. The following histomechanical properties of cartilage are discussed: transient behaviour, the influence of the mechanical history on the subsequent force-deformation processes, viscoelastic equilibrium status (histomechanical steady state), and relaxation phenomena in the pressure and tension range under alternating pressure-tension loading. Pressure force-time input and output curves in a closed loop system and the amplitude-increasing phenomenon under uniform sinus deformations with increasing superimposed linear deformation input were also demonstrated. The results are discussed from the point of view of functional anatomy.

Animals

[Tissue mechanical behavior of tendinous fibers under statistical and dynamic requirements].

With a device for dynamical processes tension tests were performed on bundles of collagen fibres of human and bovin origin. Part of the studies were performed under statical condition with an universal materials testing machine, equipped with a closed loop feed back control system. If the force is to be kept constant subsequently to a strain process on a collagen fiber bundle (isotonic condition), the fiber length must increase (creep phenomenon, retardation). The force decreases under constant length after a preceding strain process (relaxation). In analogy to the statical relaxation, statical isorheological line, and statical force recovery curve the dynamical (cyclic) relaxation, dynamical (cyclic) isorheological curve, and dynamical (cyclic) force recovery curve are described. The mechanical-rheological properties collagen fiber bundles are discussed in relation to functional anatomy.

Biomechanical Phenomena