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Helmut Wicht

Publications and source records attributed to Helmut Wicht.

4 recordsLinked to original sources
PubMed2004

Distribution of transcription factor inducible cyclicAMP early repressor (ICER) in rodent brain and pituitary.

In morphogenetic dynamics of neurons, and in adaptive physiology of brain function, transcription factors of the cyclicAMP signaling pathway, such as activator cyclicAMP responsive element binding protein (CREB) and inhibitor inducible cyclicAMP early repressor (ICER), play an important role. In particular, the presence of the transcription factor ICER in neurons or neuroendocrine cells suggests the need for the gating of an up-regulated gene expression. Little is known, however, about the natural distribution of the inhibitory transcription factor ICER. We, therefore, mapped the rodent brain and pituitary for an ICER immunoreaction and found a nuclear staining for this transcription factor. ICER-positive glial cells were found throughout the brain. ICER-positive neurons were found in sensory input centers, like the olfactory bulb, or sensory brain stem nuclei, and in hypothalamic nuclei involved in central neuroendocrine control. In addition, neuroendocrine/endocrine transducers, like the pituitary and the pineal gland showed a high basal presence of ICER. Our data show that a basic ICER level is required by many cell systems and can be seen as an anticipatory and/or a protective measure in systems with superior reactive dynamics.

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PubMed2003

Cytoarchitecture, topography, and descending supraspinal projections in the anterior central nervous system of Branchiostoma lanceolatum.

The central nervous system (CNS) of the chordate amphioxus (Branchiostoma lanceolatum) is divisible into a spinal cord and an anterior portion in some ways equivalent to the brain of craniates. The present study reports on this anterior portion, with respect to general topography, cytoarchitecture, and cells that give rise to descending supraspinal projections. The anterior portion of the CNS is located adjacent to the first four myomeres and rostral to the first giant cell of Rohde-it can be divided into several regions that differ with respect to their cytoarchitecture. The tip of the neural tube is formed by a small anterior vesicle; caudally, there is a much larger region that is intercalated between the anterior vesicle and the first cell of Rohde. This intercalated region, in turn, consists of three subdivisions: an anterior subdivision adjacent to myomere 1, an intermediate subdivision adjacent to myomere 2, and a posterior one adjacent to myomeres 3 and 4. After injections of tracers into the spinal cord a large number of cells were labeled in the intercalated region. The spinally projecting cells were not evenly distributed: their number was decreased in the center of the intermediate subdivision. These subdivisions, which have previously not been noted, may be aligned with the expression domains of regulatory genes (e.g., AmphiOtx, AmphiHox) in larval lancelets. In particular, the center of the intermediate subdivision may correspond to a "nonHox/nonOtx" domain in the CNS of the larva. A similar embryonic domain occurs in the brain of craniates in which it develops into the isthmus cerebri that separates mid- and hindbrain. A close structural and topographical inspection of the corresponding region of adult lancelets reveals, however, that this region is not the homolog of an isthmus, but a uniquely derived, autapomorphic feature of lancelets.

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PubMed2003

Bone-implant interface around titanium implants under different loading conditions: a histomorphometrical analysis in the Macaca fascicularis monkey.

BACKGROUND: Bone healing around endosseous dental implants is associated with peri-implant loading conditions. Therefore, the aim of this study was to evaluate histomorphometrically the bone response around unloaded, delayed, and immediately loaded implants with a progressive thread design that were placed in the posterior regions of the lower jaw in monkeys. METHODS: Nine adult monkeys (Macaca fascicularis) were used in this study. After extraction of the second premolars and first and second molars in the mandible, the bone was allowed to heal for a period of 3 months. Forty-eight 8 mm long implants with a diameter of 3.5 mm were placed according to the following protocol. In two of the monkeys, six implants were placed and left to heal submerged for 3 months (group A). In seven monkeys, 21 implants were placed in one side of the mandible and loaded after 3 months of submerged healing (group B). The group B implants were loaded with temporary resin bridges at the same time as another 21 implants that were loaded immediately (group C) after placement in the contralateral side of the mandibles of the same monkeys. The occlusion of group B and C implants was checked for optimal relationship of the resin bridges that were replaced 1 month later with metal bridges and loaded for an additional 2 months. The group A animals were sacrificed after 3 months of submerged healing without loading; group B and C animals were sacrificed after 3 months of implant loading. Specimens were examined histologically and histomorphometrically. RESULTS: All implants osseointegrated without presenting any gap in the metal-bone interface. Compact cortical bone was found in contact with the implant surfaces. Group A implants demonstrated in the interface cancellous bone with loose connective tissue. Group B and C implants showed a thick cortical plate with extensive bone trabeculae formation. There was a significant difference in bone-to-implant contact (BIC) between the various loading conditions. No significant difference (P < 0.05) was found between groups B and C. There was an increased area of bone (BA) within the threads as well as around the apices of group B and C implants. CONCLUSIONS: Implant loading might have stimulated increased bone formation and thus may be a key factor in influencing positive osseointegration. In addition, immediately loaded implants may osseointegrate in a similar manner as delayed loaded implants.

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