PubMed Health⌕ Search

Biomedical subjects

E Thies

Publications and source records attributed to E Thies.

At least 19 recordsLinked to original sources
PubMed2003

Clogging of axons by tau, inhibition of axonal traffic and starvation of synapses.

Loss of synapses and dying back of axons are considered early events in brain degeneration during Alzheimer's disease. This is accompanied by an aberrant behavior of the microtubule-associated protein tau (hyperphosphorylation, aggregation). Since microtubules are the tracks for axonal transport, we are testing the hypothesis that tau plays a role in the malfunctioning of transport. Experiments with various neuronal and non-neuronal cells show that tau is capable of reducing net anterograde transport of vesicles and cell organelles by blocking the microtubule tracks. Thus, a misregulation of tau could cause the starvation of synapses and enhanced oxidative stress, long before tau detaches from microtubules and aggregates into Alzheimer neurofibrillary tangles. In particular, the transport of amyloid precursor protein is retarded when tau is elevated, suggesting a possible link between the two key proteins that show abnormal behavior in Alzheimer's disease.

Alzheimer Disease↗
PubMed2002

Tau blocks traffic of organelles, neurofilaments, and APP vesicles in neurons and enhances oxidative stress.

We studied the effect of microtubule-associated tau protein on trafficking of vesicles and organelles in primary cortical neurons, retinal ganglion cells, and neuroblastoma cells. Tau inhibits kinesin-dependent transport of peroxisomes, neurofilaments, and Golgi-derived vesicles into neurites. Loss of peroxisomes makes cells vulnerable to oxidative stress and leads to degeneration. In particular, tau inhibits transport of amyloid precursor protein (APP) into axons and dendrites, causing its accumulation in the cell body. APP tagged with yellow fluorescent protein and transfected by adenovirus associates with vesicles moving rapidly forward in the axon (approximately 80%) and slowly back (approximately 20%). Both movements are strongly inhibited by cotransfection with fluorescently tagged tau (cyan fluorescent protein-tau) as seen by two-color confocal microscopy. The data suggests a linkage between tau and APP trafficking, which may be significant in Alzheimer's disease.

Alzheimer Disease↗
PubMed1999

Neuronal growth cone collapse triggers lateral extensions along trailing axons.

Axonal outgrowth is generally thought to be controlled by direct interaction of the lead growth cone with guidance cues, and, in trailing axons, by fasciculation with pioneer fibers. Responses of axons and growth cones were examined as cultured retinal ganglion cell (RGC) axons encountered repellent cues. Either contact with cells expressing ephrins or mechanical probing increased the probability of lead growth cone retraction. Lateral extension of filopodia and lamellipodia hundreds of microns behind the lead growth cone was correlated with its collapse. Transmission electron microscopy showed that some of the lateral extensions originate from the pioneer axon, whereas others represent growth cones of defasciculating trailing axons.

3T3 Cells↗
PubMed1998

Cellular localization of ephrin-A2, ephrin-A5, and other functional guidance cues underlies retinotopic development across species.

Avian retinotectal and rodent retinocollicular systems are general model systems used to examine developmental processes that underpin topographically organized neuronal circuits. The two systems rely on guidance components to establish their precise retinotopic maps, but many cellular events differ during their development. For example, compared with the chick, a generally less restricted outgrowth pattern is observed when retinae innervate their targets in rodents. Cellular or molecular distributions of guidance components may account for such differences in retinotopic development across species. Candidate repellent molecules, such as ephrin-A2 and ephrin-A5, have been cloned in both chick and rodents; however, it has not yet been shown in rodents that living cells express sufficient amounts of any repellent components to deter outgrowth. We used a coculture assay that gives cellular resolution of retinotarget interactions and demonstrate that living, caudal superior colliculus cells selectively prevent extension of axons from temporal regions of the retinae. Time-lapse video microscopy revealed the cellular localization of permissive and repulsive guidance components in rodents, which differed from that in chick. To analyze the potential molecular basis for these differences, we investigated the function and localization of ephrin-A2 and -A5. Cells transfected with ephrin-A2 and -A5 selectively repelled retinal axons. Ephrin-A2 and -A5 RNA expression patterns differed across cell populations and between species, suggesting molecular mechanisms and key cellular interactions that may underlie fundamental differences in the development of retinotectal and retinocollicular maps.

Animals↗
PubMed1997

Plasma fatty acids in sheep fed hydroxyethylsoyamide, a fatty acyl amide that resists biohydrogenation.

Hydroxyethylsoyamide (HESA) was made from soybean oil (SBO) and ethanolamine to determine the effectiveness of this fatty acyl amide to escape ruminal biohydrogenation and increase unsaturated fatty acids in plasma of sheep. The disappearance rate of 18:2n-6 from in vitro cultures was reduced 61% when the substrates contained added HESA compared to added linoleic acid. The decline in acetate to propionate ratio in the cultures also was less for HESA than for linoleic acid, which indicates lower inhibition of fermentation by HESA. Four sheep were housed in metabolism stalls for the collection of feces and urine and fed four diets in a Latin square design with 17-d periods. The diets contained no added fat (control) or were supplemented with 2.5% SBO, 5% butylsoyamide (BuSA), or 5% HESA. Plasma 18:2n-6 was not changed by feeding SBO. However, compared to the control diet, 18:2n-6 increased 19 and 35% in plasma fatty acids, and 74 and 113% in plasma triglycerides when sheep were fed BuSA and HESA, respectively. Digestibility of HESA was greater than for BuSA (99.5 vs. 48.4%, respectively). No amide was detected in plasma of sheep fed either BuSA or HESA. This study further supports that unsaturated oils can be converted to fatty acyl amides as a way to avoid ruminal biohydrogenation and elevate unsaturated fatty acids in body tissues of ruminants. Also, digestibility of the amide and plasma unsaturated fatty acids was enhanced more when the amide was synthesized from ethanolamine than when synthesized from butylamine.

Animals↗
PubMed1996

Cellular localization of guidance cues in the establishment of retinotectal topography.

Topographic projections of the nervous system are essential to numerous brain functions. They arise during development as a result of encounters between projecting growth cones and particular target cells. Cellular localization of guidance cues can indicate the sequential processes involved in establishment of such topography. The map formed by retinal ganglion cells on their target nuclei has served widely as a model system to investigate mechanisms underlying the highly precise and stereotypic connectivity of the nervous system. To investigate cellular localization of guidance cues in the developing retinotectal system, a three-compartment chamber was created to delimit areas where cultured embryonic chick retinal ganglion axons and tectal cells encounter one another and guidance behavior could be readily assessed. Whereas explants from nasal retinae extended fibers across their natural target population, fibers from temporal regions of retinae failed to invade areas of growing posterior tectal cells. This preservation of relevant guidance information on living cell populations enabled an evaluation of retinal ganglion cell growth cone behavior after encounter with individual tectal cells. Posterior tectal neurons appeared selectively repulsive for temporal retinal ganglion cell growth cones, causing growth cone collapse and retraction. On the contrary, neuroepithelial cells from all regions of the tectum attenuated retinal ganglion axon extension, without inducing sudden retraction. Nasal growth cones traversed or tracked more often along neuroepithelial cells from their natural target area, potentially indicating a second set of guidance cues possibly localized to posterior glia. Together, these differential interactions suggest that development of retinotectal topography critically depends on cell-specific cues, which are distributed selectively on particular populations of target cells.

Afferent Pathways↗
PubMed1996

Localized amyloid in the menisci of the knee joint.

This is, to the best of our knowledge, the first report on amyloid deposits in menisci. Fragments of menisci gained by arthroscopy from 316 patients between 20 and 80 years of age were examined. Amyloid was found in 70% of the cases from male, as well as female patients. The amyloid amount found was always very small, but the deposits seemed to increase with age. Patients more than 50 years of age all had menisceal amyloid. Two types of deposits were observed: a)stroma-deposits in the deep central portions of the menisci (tiny dots of intensely stained amyloid and/or ill defined patches of low staining intensity) and b) surface associated deposits: band-like amyloid imbibition of the collagenous stroma immediately beneath the surface of the menisci but not deeper than 0.2 mm. In all cases, amyloid was resistant when pretreated by KMn04 and immunohistologically antisera against amyloid types AA, AB and AF were negative. 3/25 cases showed a reaction with an amyloid-lambda-antibody. We assume, that amyloid in menisci is a further type of localized senile amyloidosis.

Adult↗
PubMed1993

A method for the generation of YAC transgenic mice by pronuclear microinjection.

Yeast artificial chromosomes (YACs) represent the latest generation of vectors which have the great advantage of large insert size. The introduction of YACs into mammalian cells and organisms has become an important goal, since it offers the potential to study the control of large and complex transcription units and identify genes by complementation. Microinjection into the nucleus is the most direct and efficient way of delivering YAC DNA into cells, but requires the purification of the YAC from the remaining yeast chromosomes. Here we describe a detailed method for the isolation of pure, intact and highly concentrated YAC DNA. As a model system the murine tyrosinase gene was chosen and four YACs covering this locus were isolated. Introduction by homologous recombination in yeast of sequences permitting YAC amplification greatly facilitated the isolation of YAC DNA at high concentrations. YAC DNA stabilized in a salt and polyamine containing buffer did not compromise the survival of microinjected oocytes and was suitable for the generation of transgenic mice. Applications and benefits of this technique will be discussed.

Animals↗
PubMed1993

Appearance of target-specific guidance information for regenerating axons after CNS lesions.

During development of the vertebrate visual system, an orderly projection of ganglion cells from the retina onto the superior colliculus (SC) is established. Mechanisms that might govern this process include the coordinated action of guidance and corresponding receptor molecules that are specifically distributed on the axons and their targets. In birds and mammals, information for axonal guidance and targeting appears to be confined to the time when the retinocollicular projection is being formed. Here we show that putative guidance activities for temporal and nasal retinal axons, which are not detectable in the normal adult SC, appear after optic nerve transection in adult rats. Both embryonic and adult retinal axons are able to respond to these guiding cues, although the guidance activities detectable in the deafferented adult rat SC might be different from those found during development. These findings imply that it might be possible to reestablish an ordered projection after lesions in the adult mammalian visual system.

Afferent Pathways↗
PubMed1993

[Traumatic false aneurysm of the subclavian artery].

Injuries of the subclavian artery are rare; still rarer are aneurysms of the subclavian artery due to blunt or penetrating trauma. Diagnosis can be performed by careful clinical investigation. To identify precisely the nature and site of the injury, angiography and CT are necessary. Rarely associated injuries, such as arteriovenous fistulas, can be recognized by means of these diagnostic tools. This will be of value for planning the surgical approach, which varies with the anatomical site of the injury and the kind of accompanying damage. Subclavian aneurysms should be treated surgically, because embolic or thrombotic complications may threaten the extremity and the brain.

Adolescent↗
PubMed1992

Transgenic mice generated by pronuclear injection of a yeast artificial chromosome.

Transgenic mice have become invaluable for analysing gene function and regulation in vivo. However, the size of constructs injected has been limited by the cloning capacity of conventional vectors, a constraint that could be overcome with yeast artificial chromosomes (YACs). We investigated the feasibility of making transgenic mice with YACs by pronuclear injection of a small YAC carrying a gene encoding tyrosinase. Use of a vector with a conditional centromere allowed fifteenfold amplification of the YAC in yeast and its recovery in high yield. The albino phenotype of the recipient mice was rescued demonstrating the correct expression of the tyrosine gene from the construct. Furthermore, the telomeric sequences added by the yeast integrated into the mouse genome and did not reduce efficiency of integration. Using this technique future experiments with longer YACs will allow the expression of gene complexes such as Hox and the globin gene clusters to be analysed in transgenic animals.

Animals↗
PubMed1992

Chromosome jumping from flanking markers defines the minimal region for alf/hsdr-1 within the albino-deletion complex.

The locus alf/hsdr-1, defined by the albino-deletion complex on mouse chromosome 7, is essential for neonatal survival. Animals homozygous for a subset of the deletions die shortly after birth due to impaired gene expression in liver parenchymal cells and kidney proximal tubular cells. Here, we describe a detailed analysis of the region containing alf/hsdr-1 by means of chromosome jumping from flanking markers. Three chromosome jumping libraries based on the restriction enzymes XmaI and SalI were constructed. Isolation of eight jumping clones distributed over 450 kb allowed more than 240 kb to be cloned in genomic lambda and cosmid libraries. Five of the probes map within the minimal genetic interval for alf/hsdr-1, which is defined by the proximal borders of the deletions c10R75M and c11DSD. The breakpoints of these deletions were precisely mapped, which allowed alf/hsdr-1 to be localized to a 310-kb interval.

Albinism↗
PubMed1992

Deficiency of an enzyme of tyrosine metabolism underlies altered gene expression in newborn liver of lethal albino mice.

Mice homozygous for albino deletions encompassing the locus alf/hsdr-1 die shortly after birth. Lethality is thought to be the consequence of hypoglycemia, which results from the failure to activate hormone-dependent genes in liver and kidney encoding enzymes important for gluconeogenesis. Within the region in which alf/hsdr-1 has been defined by physical mapping, we identified the gene encoding fumarylacetoacetate hydrolase (FAH), an enzyme of tyrosine metabolism. Lack of FAH activity should lead to accumulation of toxic tyrosine metabolites. In man, genetically determined FAH deficiency is the primary defect in tyrosinemia type I, a fatal liver disease of infants. Northern blot and in situ hybridization analysis of mouse tissues showed that the cell types that normally express FAH correspond to those that exhibit a phenotype in alf/hsdr-1 deletion mice. Moreover, we could mimic aspects of the alf/hsdr-1 deletion phenotype in vitro by treating primary hepatocyte cultures with an intermediate of tyrosine metabolism. These findings strongly suggest that alf/hsdr-1 encodes FAH and that absence of FAH is responsible for neonatal lethality in albino deletion mice. Mechanisms by which this metabolic defect might bring about alterations in gene expression characteristic of the alf/hsdr-1 deletion phenotype are discussed.

Amino Acid Sequence↗
PubMed1992

Multiple effects on liver-specific gene expression in albino lethal mice caused by deficiency of an enzyme in tyrosine metabolism.

alf/hsdr-1 is a locus in the mouse defined by albino deletions to be essential for neonatal viability. Homozygous deletion of alf/hsdr-1 leads to a pleiotropic phenotype in liver and kidney, including impaired perinatal activation of hormone-dependent genes, and the induction of detoxifying enzymes and early-response genes. To elucidate the molecular basis of this complex phenotype, we have identified the gene mapping at alf/hsdr-1 by positional cloning, using overlapping albino locus deletions to define the location of alf/hsdr-1. The gene encodes fumarylacetoacetate hydrolase, FAH, an enzyme of tyrosine metabolism. Genetically determined FAH deficiency in man leads to a severe liver failure in infants. In mice, we find that the normal sites of expression of FAH correlate tightly with cell-types which display abnormalities in albino lethal mice. The identification of the Fah gene as a candidate for alf/hsdr-1 offers a novel explanation for the complex phenotype, one into which all aspects can be accommodated. The phenotype can now be understood as a sequence of responses to toxic electrophilic metabolites.

Animals↗
PubMed1990

Expression of glutathione S-transferases in normal gastric mucosa and in gastric tumors.

Glutathione S-transferases from both normal gastric mucosa and its matched gastric tumors from 10 different patients were investigated. The transferases were purified and subsequently the isoenzyme composition was studied. Glutathione S-transferase (GST)-pi was present in all specimens in large amounts. Class alpha GSTs were present in 9 out of 10 normal specimens and in six tumors. In malignant tissue, expression of GST-pi was increased at the expense of class alpha GST. In six patients, the ratio GST-pi/GST-alpha was higher in tumorous versus normal tissue. On a Western blot, using a monoclonal antibody, GST-mu was shown to be present in both normal and malignant tissue from four patients, the other six patients completely missed the enzyme in their gastric tissue. When present, GST-mu amounts to only a few per cent of total GST protein. GST-pi was quantified by densitometric analysis of Western blots, treated with a monoclonal antibody against GST-pi. Both total GST enzyme activity as well as the absolute amounts of GST-pi protein were significantly higher in the tumors, as compared to its matched normal mucosa. The importance of this overexpression of GST-pi was previously unknown. However, the frequent occurrence of this phenomenon in many refractory tumors, and as shown now also in gastric cancers, suggests a role for GST-pi in the mechanism of anti-cancer drug resistance.

Adult↗
PubMed1990

[Management of ruptured aortic aneurysms in routine service of a surgical department].

In the year 1989 859 patients with infrarenal aortic aneurysms were treated in the Hessen county (5.6 mill inhabitants) (private survey). 64% of the ruptured aneurysms were operated in 24 departments for general surgery and 36% were operated in the 7 departments for vascular surgery. Corresponding numbers for elective operations are 55% respectively 45%. The results after resection of the aneurysms in our 22 patients with ruptured aneurysms (1986-1989) reveal a letality of 50%. No patient arriving at our clinic alive was excluded from operation. Letality in electively operated patients (n = 131) during the same period was 2.3% (n = 3).

Aged↗