Biomedical subjects

H Matthies

Publications and source records attributed to H Matthies.

At least 19 recordsLinked to original sources

PubMed2006

Evaluation of surface and volume rendering in 3D-CT of facial fractures.

OBJECTIVES: Three-dimensional computed tomography (3D-CT) of facial fractures has been reported as beneficial using surface (SR) and volume rendering (VR). There are controversial statements concerning the preferable algorithm. The purpose of this study was to evaluate and compare SR and VR for clinical 3D-CT in facial fractures on an experimental basis. METHODS: Multislice CT was obtained in 22 patients with facial fractures using two data acquisition protocols. Five SR and VR post-processing protocols were applied. Five assessors independently evaluated the quality of visualization of the fracture gap and dislocated fragments as well as the overall image quality using a five-point rating scale. The potential benefit of the 3D-images for radiological diagnosis and presentation was evaluated. The influence of the data acquisition protocol was analysed. RESULTS: SR in general achieved better evaluation scores than VR at corresponding thresholds. Variation of evaluation scores for all criteria was found for SR and VR depending on the segmentation threshold. Apart from the overall image quality no significant influence of the data acquisition technique was found for the evaluated criteria. CONCLUSIONS: SR provided sufficient and time efficient means for 3D-visualization of facial fractures in this study. No diagnostic benefit of VR over SR was found.

Adolescent↗

PubMed2004

The learning unit "Orthodontic set-up" as a new-media module in teaching.

The present study examines the extent to which computer-assisted learning units provided independently of place and time are used in self-study as a supplement to the classical classroom instruction of dental students. Indications as to whether such teaching modules improve training in orthodontics should be obtained from this. Attention was focussed on the implementation and evaluation of the "Orthodontic set-up" teaching module, which can be accessed in the Internet and Intranet of the university. The didactic arrangement offered classical university courses in parallel (four lectures on the subjects of occlusion, function, diagnostics, and therapy) in addition to the electronically communicated teaching contents. In addition, intensive supervision during the production of the set-up was guaranteed. The use of this multimedia learning concept was in general assessed positively by 63 surveyed students in the 2002/03 winter semester. The results revealed on the one hand the intensity of use and features of the acquisition of knowledge (use types), and on the other hand, in terms of professional relevance, the contents were found to be well explained, didactically attractive, and understandably presented. However, numerous drawbacks were also mentioned (technical and time problems; qualification deficits). The experience gained in this project should encourage more future investment in the development of alternative university didactic models.

Computer-Assisted Instruction↗

PubMed2002

[Personality, accentuated traits and personality disorders. A contribution to dimensional diagnosis of personality disorders].

A dimensional diagnostic system for personality disorders (PD) postulates continuous transition from normal to disordered personalities (continuity hypothesis) and universal validity of basic personality dimensions (universal hypothesis). The present study investigates the validity of Leonhard's concept of attenuated personalities that define a conceptual link between normal personality dimensions and PD. Nine possible continuous transitions between three conceptual levels (Big Five personality factors, nine attenuated personality traits, nine PD) were tested by questionnaire data obtained from a mentally healthy (n = 166) and a clinical sample (n = 78). Both samples differed significantly in nearly all variables. However, they showed substantial similarity concerning the (in)validity of single continua and the complex structure of all variables as analyzed by multidimensional scaling. The concept of attenuated personalities could be validated for six out of nine tested continua and can be recommended for application in dimensional models of personality and personality disorders.

Adult↗

PubMed2001

Neurocan is dispensable for brain development.

Neurocan is a component of the extracellular matrix in brain. Due to its inhibition of neuronal adhesion and outgrowth in vitro and its expression pattern in vivo it was suggested to play an important role in axon guidance and neurite growth. To study the role of neurocan in brain development we generated neurocan-deficient mice by targeted disruption of the neurocan gene. These mice are viable and fertile and have no obvious deficits in reproduction and general performance. Brain anatomy, morphology, and ultrastructure are similar to those of wild-type mice. Perineuronal nets surrounding neurons appear largely normal. Mild deficits in synaptic plasticity may exist, as maintenance of late-phase hippocampal long-term potentiation is reduced. These data indicate that neurocan has either a redundant or a more subtle function in the development of the brain.

Animals↗

PubMed2000

The synaptic glycoprotein neuroplastin is involved in long-term potentiation at hippocampal CA1 synapses.

Neuroplastin-65 and -55 (previously known as gp65 and gp55) are glycoproteins of the Ig superfamily that are enriched in rat forebrain synaptic membrane preparations. Whereas the two-Ig domain isoform neuroplastin-55 is expressed in many tissues, the three-Ig domain isoform neuroplastin-65 is brain-specific and enriched in postsynaptic density (PSD) protein preparations. Here, we have assessed the function of neuroplastin in long-term synaptic plasticity. Immunocytochemical studies with neuroplastin-65-specific antibodies differentially stain distinct synaptic neuropil regions of the rat hippocampus with most prominent immunoreactivity in the CA1 region and the proximal molecular layer of the dentate gyrus. Kainate-induced seizures cause a significant enhancement of neuroplastin-65 association with PSDs. Similarly, long-term potentiation (LTP) of CA1 synapses in hippocampal slices enhanced the association of neuroplastin-65 with a detergent-insoluble PSD-enriched protein fraction. Several antibodies against the neuroplastins, including one specific for neuroplastin-65, inhibited the maintenance of LTP. A similar effect was observed when recombinant fusion protein containing the three extracellular Ig domains of neuroplastin-65 was applied to hippocampal slices before LTP induction. Microsphere binding experiments using neuroplastin-F(c) chimeric proteins show that constructs containing Ig1-3 or Ig1 domains, but not Ig2-3 domains mediate homophilic adhesion. These data suggest that neuroplastin plays an essential role in implementing long-term changes in synaptic activity, possibly by means of a homophilic adhesion mechanism.

Animals↗

PubMed2000

Lack of expression of long-term potentiation in the dentate gyrus but not in the CA1 region of the hippocampus of mu-opioid receptor-deficient mice.

The possible involvement of the mu-opioid receptor subtype in mechanisms of long-term potentiation (LTP) of the lateral perforant pathway to the dentate gyrus neurons, as well as of the Schaffer collateral-commissural input of CA1 neurons, was investigated using mu-opioid receptor-deficient mutant mice. In transversal hippocampal slices from mice lacking the mu-opioid receptor (MOR) only a short potentiation in the dentate gyrus after tetanization of the lateral perforant pathway was found. In contrast, the loss of the mu-opioid receptor in the CA1 region did not affect the potentiation of the field potentials induced by tetanization of the Schaffer collaterals. In parallel experiments, the application of 10 microM of the selective MOR-antagonist, funaltrexamine, decreased LTP in the dentate gyrus of wild-type mice but again did not alter the potentiation of the field potentials in the CA1. The loss of MOR-binding in the hippocampus was accompanied by a reduction in D2-binding sites indicating a possible compensatory role of the dopaminergic system. The D1- and glutamate binding was not affected. These observations confirm earlier results with pharmacological blockade of opioid receptors in the dentate gyrus and demonstrate an essential role of MOR activation for the generation of LTP in the dentate gyrus of the mouse but not necessarily in the CA1 region.

Action Potentials↗

PubMed1999

[Quality of life. Construct validation and the development of a modular system].

The construct Quality of Life (QoL) is investigated by metaanalysis of eight (inter)nationally validated questionnaires in a multicenter study. Data have been collected in a mentally healthy (n = 479), a depressed (n = 171) and a schizophrenic (n = 139) sample. Conventional psychometric criteria and a facet analytical methodology have been applied. The resulting questionnaire "Modular System for Quality of Life" (MSQoL) consists of a core module with 47 items (one "G-factor" and six subdimensions), which is sufficiently valid for all three samples. Additionally, there are four specific modules (demography, family, partnership, profession). No specific modules can be identified for the psychopathological subgroups. The validated radex structure for subjective QoL offers the opportunity for a cumulative research design and for adaptations to the actual setting.

Adolescent↗

PubMed1999

Glycosylation of proteins during a critical time window is necessary for the maintenance of long-term potentiation in the hippocampal CA1 region.

This paper focuses on the role of glycoproteins in activity-dependent synaptic plasticity. The effect of the different inhibitors of protein glycosylation, Tunicamycin, Brefeldin A and Swainsonine, on long-term potentiation was studied in the CA1 region of rat hippocampal slices. Bath application of the inhibitors 60 min before and during tetanization did not interfere with the induction of long-term potentiation of the field excitatory postsynaptic potential. However, the potentiation in inhibitor-treated slices decreased to baseline levels during 90-180 min. Significant differences in the potentiation in non-treated slices were detectable 80 min (Tunicamycin), 60 min (Brefeldin A) and 75 min (Swainsonine) after tetanization, thus indicating the prevention of long-term potentiation maintenance. The application of Swainsonine 120 and 240 min after tetanization did not influence the potentiated field excitatory postsynaptic potential. These data demonstrate the need for undisturbed glycoprotein processing in a time window around long-term potentiation induction to maintain later phases of long-term potentiation and essential functional implications of protein glycosylation in mechanisms underlying synaptic plasticity.

Animals↗

PubMed1997

Design of a multiple slice interface chamber and application for resolving the temporal pattern of CREB phosphorylation in hippocampal long-term potentiation.

We describe an improved method for the investigation of time-dependent intracellular events giving rise to long-lasting changes in synaptic efficacy. A new interface chamber for the simultaneous superfusion of approximately 30 rat hippocampal slices was designed. The slice chamber contains an upper and a lower medium reservoir connected by a grooved incubation platform which is mounted at an angle of 7 degrees on a thermoregulation unit. Surface slices placed in the chamber are perfused with oxygenated medium at a rate of 1 ml/min and are maintained synaptically viable for at least 6 h. At different time points after induction of long-term potentiation by stimulation of the Schaffer collateral pathway, slices were either fixed in Zamboni's fixative or the CA1 region was excised and lysed in boiling SDS-sample buffer. Fixed 400 microm hippocampal slices were cut into 30 microm sections and immunocytochemically stained with an anti-serine 133 phosphorylated cAMP-responsive element binding protein (pCREB) antibody. Binding of primary antibody was detected with the avidin-biotinylated peroxidase complex method and enhanced using peroxidase-catalyzed deposition of biotinylated tyramine. Staining was visualized with streptavidin-cyanine 3.18 and observed under a confocal laser scanning microscope. CA1 lysates were electrophoresed and subjected to Western blot analysis. Both pCREB immunocytochemical staining and Western blotting showed that CREB is rapidly and transiently phosphorylated after induction of long-term potentiation. pCREB levels peaked within 30 min and declined back to control after 60 min. Immunocytochemistry also showed that pCREB was localized to the nuclei of CA1 pyramidal cells near the tetanization site.

Animals↗

PubMed1997

Dopamine D1-deficient mutant mice do not express the late phase of hippocampal long-term potentiation.

The possible involvement of the dopamine D1 receptor subtype in mechanisms of long-term potentiation (LTP) of the Schaffer collateral-commissural input of CA1 neurones was investigated using D1-deficient mutant mice. In transversal hippocampus slices from mice lacking the D1 receptor a normal post-tetanic and short-term potentiation could be induced after applying a triple 100 Hz tetanization. However, the potentiated fEPSP in the mutant mice declined to control value about 140 min following tetanization, whereas in the wild type mice a normal, non-decremental LTP was observed. These data support the idea that besides the glutamatergic system, the synergistic activation of dopaminergic synapses is necessary for LTP maintenance.

Animals↗

PubMed1997

Inhibition by compactin demonstrates a requirement of isoprenoid metabolism for long-term potentiation in rat hippocampal slices.

Hippocampal long-term potentiation of synaptic transmission is the primary experimental model of learning and memory in the vertebrate brain. However, the detailed intracellular mechanisms giving rise to this persistent increase in synaptic efficacy remain incompletely understood. Mevalonic acid constitutes the basic precursor not only for cholesterol, dolichol and ubichinone but also for farnesyl-pyrophosphate and geranylgeranylpyrophosphate, which are required for post-translational modification of proteins. We have used the specific 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor, compactin, to examine the role of isoprenoid metabolism for long-term potentiation in rat hippocampal slices. Compactin was applied at a concentration of 25 microM for 70 min before and during tetanization and the orthodromic population spike amplitude and field excitatory postsynaptic potentials were recorded from CA1 pyramidal cells. Compactin had no effect on the initial tetanization. However, compactin-treated slices were not able to maintain long-term potentiation for more than 60 min and population spike as well as field excitatory postsynaptic potentiation returned to basal levels after 120 min. When the slices were retetanized after 180 min, an almost full potentiation of the population spike and an only partial potentiation of the field excitatory postsynaptic potentials were observed. These results suggest an essential role of isoprenoid intermediates for maintenance of hippocampal long-term potentiation.

Animals↗

PubMed1996

Fucose and fucosyllactose enhance in-vitro hippocampal long-term potentiation.

Bath application of L-fucose and 2-fucosyllactose (2FI) increases the potentiation of the population spike amplitude (POP-spike) and the field excitatory postsynaptic potential (fEPSP) after tetanization of the Schaffer collaterals of the rat hippocampus. The ineffective isomers D-fucose and 3-fucosyllactose (3-FI) have no such effect. Since not only the maintenance of long-term potentiation LTP is influenced but also its induction is drastically improved, an effect of the sugars via the formation of glycoproteins but also via different actions on induction mechanisms is discussed.

Animals↗

PubMed1995

NMDA/R1-antisense oligonucleotide influences the early stage of long-term potentiation in the CA1-region of rat hippocampus.

We have studied the role of the N-methyl-D-aspartate (NMDA)/R1 receptor subunit in the mechanism of long-term potentiation (LTP) using an antisense-oligodeoxynucleotide strategy. Antisense-oligodeoxynucleotide (aDON; 10 nmol) or sense-oligodeoxynucleotide (sDON) were applied into the right ventricle of 7 week old male Wistar rats every 12 h for 3 days. Thereafter, in hippocampal slices extracellular field potential recordings were made from the CA1 region. LTP was induced by tetanization of the Schaffer collaterals. In slices of rats pretreated with aDON the initial potentiation of the population spike (POP-spike) was significantly smaller than in those from saline controls and naive animals. The impairment of potentiation lasted for about 50 min posttetanus. However, the potentiation of the field excitatory postsynaptic potentials (fEPSPs) was significantly influenced for 15 min. In slices of rats pretreated with sDON only a small, insignificant difference in POP-spike and fEPSP potentiation was seen compared to saline controls. In the group pretreated with aDON the specific binding of [3H]glutamate to the NMDA-receptor subtype of hippocampal membranes was reduced to about 63% in comparison with the group treated with sDON. These results indicate that DONs reached the target region when applied intraventricularly and were able to suppress the translation of mRNA of the NMDA/R1 receptor subunit. They further support the assumption of the essential role of the NMDA/R1 receptor subunit in the induction of LTP.

Animals↗

PubMed1994

The influence of diazepam on learning processes impaired by pentylenetetrazol kindling.

Repeated administration of pentylenetetrazol (PTZ) induces kindling and impairs shuttle-box learning. The available literature suggesting a close connection between seizure frequency and mental deficits in human epileptics allows us to hypothesize that seizure inhibition prevents the progressive mental retardation associated with kindling. In order to investigate the effect of motor seizure inhibition on mental impairment we administered diazepam (DZP) doses of 0.5 and 2.5 mg/kg, respectively 60 min prior to the 10 convulsant injections. After completion of kindling the learning performance of the rats was tested in the shuttle-box. PTZ kindling resulted in diminished shuttle-box learning. In control rats treated with DZP no significant changes in their learning ability occurred. Although DZP was found to suppress kindling development effectively a worsened shuttle-box learning could be observed in all PTZ groups treated with DZP.

Animals↗

PubMed1993

Influence of beta-casomorphins on apomorphine-induced hyperlocomotion.

Derivatives of beta-casomorphin Tyr-Pro-Phe-Pro-Gly and their des-Tyr1-derivatives were investigated on the model of apomorphine-induced hyperlocomotion (1 mg/kg = 3 microM/kg, IP). D-Pip4 CM 5 (5 nM) inhibited the apomorphine hypermotility completely, while D-Phe3 CM 5 (5 nM) and D-Pro4 CM 5 (5 nM) decreased it only to about 50%. The normal exploration was nearly completely inhibited by D-Pro4 CM 5 (40 nM), by D-Pip4 CM 5 (5 nM) depressed to 20%, and by D-Phe3 CM 5 (10 nM) to 35%. The maximum inhibition of apomorphine-induced hyperlocomotion by the des-Tyr-casomorphin derivatives was about 50%. The dose-response curves were U-shaped. The exploratory activity was not significantly influenced. The mode of action and the involvement of different neurotransmitter systems in the inhibitory effect of beta-casomorphin derivatives on apomorphine hyperlocomotion are discussed.

Amino Acid Sequence↗

PubMed1993

Adrenalectomy attenuates the improvement of memory in rats by peripheral application of Des-Tyr-D-Pro4-casomorphin.

beta-Casomorphin derivatives without the N-terminal amino acid tyrosine possess memory-improving effects after central and peripheral application. We investigated the significance of adrenal glands for the memory improving effect of the systemically applied beta-casomorphin derivative des-Tyr-D-Pro4CM (Pro-Phe-D-Pro-Gly) in a learning experiment. Seven-week-old rats were adrenalectomized or sham operated. One week after surgery the rats were trained in an active avoidance task in a shuttle box. Five avoidance reactions were taken as learning criterion. After training 10 nmol/kg des-Tyr-D-Pro4CM or saline (10 ml/kg) was subcutaneously applied. There were no differences in acquisition between adrenalectomized and sham-operated rats. The memory retention of sham-operated animals was improved by des-Tyr-D-Pro4CM. In adrenalectomized rats this positive effect could not be observed. The involvement of adrenal glands in the peptide effect during learning and retention is discussed.

Adrenal Glands↗

PubMed1993

Protein kinase A inhibitors prevent the maintenance of hippocampal long-term potentiation.

The possible involvement of cAMP-dependent protein kinase A (PKA) in mechanisms of long-term potentiation of the Schaffer collateral-commissural input of rat CA1 neurones was investigated using several inhibitors in vitro. If 10 microM H-8, 100 nM KT5720 or 50 microM Rp-cAMPs was applied to the bath before a triple 100 Hz/0.5 s tetanization, post-tetanic and short-term potentiation developed almost normally. However, from about 3 h after tetanization the long-term potentiation (LTP) of the field-EPSP declined with respect to the control in an irreversible manner. These data suggest that besides protein kinase C the synergistic activation of PKA is necessary for the maintenance of LTP.

Animals↗

PubMed1992

Kindling and its consequences on learning in rats.

To study the learning performance of pentylenetetrazol- and amygdala-kindled Wistar rats we used the following learning tests: short-term memory was tested in the response-to-change model, brightness discrimination was tested in a Y-chamber, and two-way active avoidance learning was tested in a shuttle-box. Short-term memory was not impaired by both kindling procedures. Considering two-way active avoidance learning the performance of pentylenetetrazol (PTZ)-kindled rats was significantly diminished. This effect persists over a period of 4 weeks. However, amygdala (AMY)-kindled rats acquired this task like the controls. In brightness discrimination reaction (BDR) the learning performance of PTZ-kindled animals was not influenced. Although the acquisition of BDR was nearly identical, the 24-h retention was remarkably diminished in AMY-kindled rats. It was hypothesized that the different kindling procedures interfere in different ways and extent with neuronal circuits resulting in different functional impairments.

Amygdala↗