PubMed Health⌕ Search

Biomedical subjects

T Naumann

Publications and source records attributed to T Naumann.

At least 37 records · Page 2Linked to original sources
PubMed1996

Development of cholinergic and GABAergic neurons in the rat medial septum: different onset of choline acetyltransferase and glutamate decarboxylase mRNA expression.

In the present study, we have investigated the developmental expression of the transmitter-synthesizing enzymes choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) in rat medial septal neurons by using in situ hybridization histochemistry. In addition, we have employed immunostaining for ChAT and the calcium-binding protein parvalbumin, known to be contained in septohippocampal GABAergic neurons. A large number of GAD67 mRNA-expressing neurons were already observed in the septal complex on embryonic day (E) 17, the earliest time point studied. During later developmental stages, there was mainly an increase in the intensity of labeling. Neurons expressing ChAT mRNA were first recognized at E 20, and their number slowly increased during postnatal development of the septal region. The adult pattern of ChAT mRNA-expressing neurons was observed around postnatal day (P) 16. By using a monoclonal ChAT antibody, the first immunoreactive cells were not seen before P 8. Similarly, the first weakly parvalbumin-immunoreactive neurons were seen in the septal complex by the end of the 1st postnatal week. These results indicate that in situ hybridization histochemistry may be an adequate method to monitor the different development of transmitter biosynthesis in cholinergic and GABAergic septal neurons. Moreover, the late onset of ChAT mRNA expression would be compatible with a role of target-derived factors for the differentiation of the cholinergic phenotype.

Animals↗
PubMed1996

Multiple projections are unlikely to account for the survival of rat medial septal neurons after axotomy.

Previous studies have demonstrated that numerous septohippocampal neurons survive axotomy disconnecting them from target-derived neurotrophins. One reason for survival could be that these neurons have additional projections to other targets supplying them with neurotrophic factor(s). We show that anterograde tracing indeed labeled additional targets of the medial septum (MS) in controls as well as in experimental animals. However, only very few MS neurons could be double-labeled by retrograde tracer injections into the hippocampus and these targets. Thus, for the majority of septohippocampal neurons multiple projections cannot account for their survival following axotomy.

Animals↗
PubMed1996

[Preoperative risk assessment of children with Duchenne muscular dystrophy and relevance for anesthesia and intra- and postoperative course].

BACKGROUND: Patients suffering from muscle disorders have an elevated anesthetic risk, i.e. to develop malignant hyperthermia or rhabdomyolysis. In addition serious cardial and pulmonal complications are imminent during anesthesia for surgery. PATIENTS AND METHODS: We investigated retrospectively the preoperative risk factors of 81 Duchenne patients undergoing 101 anesthesia (79 for muscle releasement operations and 23 for spine surgery) and the relation to possible complications due to the anesthesia and the intra- and postoperative course. RESULTS AND DISCUSSION: 83% of the patients showed pathologic ECG, 26% cardiac insufficiency in echocardiography, 31% pathologic X-rays of the thorax and 73% serious pulmonary restriction. Consequently avoiding of anesthetic agents with a high trigger potential for developing malignant hyperthermia (i.e. halothane or muscle relaxants type succinylcholine) prevented severest complications as malignant hyperthermia, rhabdomyolysis or cardiac arrest. Nevertheless other complications (i.e. arrhythmia, cardiac insufficiency) occurred due to the cardiac and pulmonary limitations more pronounced in the older patients of the spine surgery group.

Anesthesia, General↗
PubMed1996

Selective expression of the immediate early gene c-jun in axotomized rat medial septal neurons is not related to neuronal degeneration.

In the present study, we use the anatomically well defined septohippocampal projection to study the molecular events involved in the reaction of neurons to axotomy. The expression of three immediate early genes (c-fos, c-jun, and jun B) was investigated in rat septohippocampal neurons after axotomy by bilateral fimbria-fornix transection (FFT). Moreover, the extent of retrograde degeneration in the septal complex was assessed by analyzing DNA fragmentation. In a postoperative time course analysis, a strong increase of c-jun immunoreactivity (IR) was observed in the nuclei of neurons in the medial septum/diagonal band complex (MSDB) 2 and 6 d postaxotomy, which was followed by a decline after 12 d and 3 weeks, respectively. Nine weeks after FFT, c-jun IR had disappeared. The c-jun-positive MS neurons were identified as former septohippocampal projection cells by double-labeling with the retrogradely transported tracer Fluoro-Gold injected into the hippocampus before axotomy. In line with the immunocytochemical data, there was a massive induction of c-jun mRNA in the axotomized MS neurons as visualized by in situ hybridization histochemistry. c-fos mRNA and c-fos or jun B IR were not detectable in either unoperated or lesioned medial septal neurons. Experiments using the TdT-mediated deoxyuridine triphosphate nick-end-labeling technique, designed to detect nuclear DNA fragmentation in degenerating neurons, complemented this study. During the postoperative time range studied, MS neurons did not exhibit DNA fragmentation. We conclude that MSDB neurons survive axotomy by FFT and display characteristic changes in gene expression.

Acetylcholine↗
PubMed1996

Activity of choline acetyltransferase in the rat medial septal nucleus following fimbria-fornix transection or selective immunolesioning with 192 IgG-saporin.

Changes in the biochemical activity of choline acetyltransferase in the medial septal nucleus, diagonal band and hippocampus were determined following bilateral fimbria-fornix transection or selective immunolesioning of cholinergic septohippocampal neurons with 192 IgG-saporin. Following axotomy, choline acetyltransferase activity in the medial septal nucleus not only persisted but increased much above control values 6 months postlesion, confirming that many cholinergic neurons survive the transection of their axons. In contrast, immunolesioning led to a significant decrease in enzyme activity in the medial septal nucleus corresponding to the selective loss of septal cholinergic neurons in this lesion paradigm.

Animals↗
PubMed1996

Survival, regeneration and sprouting of central neurons: the rat septohippocampal projection as a model.

The septohippocampal projection was used to study the survival following axotomy, axonal regeneration, and sprouting of a defined group of central neurons. Septohippocampal projection neurons in adult rats were axotomized by bilateral lesions of the fimbria-fornix. Using prelabeling prior to axotomy, intracellular staining, electron microscopy, and immunocytochemical and in situ hybridization techniques, we were able to demonstrate that the majority of septohippocampal neurons survived after axotomy. At least in young postnatal rats, these axotomized neurons have the capacity to regenerate an axonal process that reinnervates its appropriate target tissue, the hippocampus. We demonstrated this by axotomizing young septohippocampal neurons and co-culturing them with sections of hippocampus. Septohippocampal neurons appear to retain their capacity for axonal growth in adulthood, since they are able to sprout within hippocampal layers partially denervated by removing entorhinal afferents. In this paradigm the terminals of septohippocampal neurons themselves were not lesioned. Our results point to a previously underestimated capacity of septohippocampal neurons for survival following axotomy, regeneration, and sprouting.

Acetylcholinesterase↗
PubMed1995

Fate of GABAergic septohippocampal neurons after fimbria-fornix transection as revealed by in situ hybridization for glutamate decarboxylase mRNA and parvalbumin immunocytochemistry.

Many septohippocampal neurons are GABAergic and are affected by transection of the fimbria-fornix, like the septohippocampal cholinergic cells. Here we have studied the changes that occur in GABAergic septohippocampal neurons following fimbria-fornix transection. For labeling of septohippocampal projection neurons, adult Sprague-Dawley rats received injections of the fluorescent tracer Fluoro-Gold into the hippocampus 1 week prior to bilateral transection of the fimbria-fornix. After axotomy, rats were allowed to survive for varying periods ranging from 3 weeks to 18 months. Following fixation of the animals, sections through the septal region were either stained by in situ hybridization for glutamate decarboxylase (GAD) mRNA or immunostained for parvalbumin (PARV), which is known to be present in GABAergic septohippocampal neurons. In situ hybridization for GAD mRNA revealed no statistically significant changes in cell number 3 weeks and 6 months postlesion. In contrast, PARV-immunoreactive neurons were reduced to 35% of control 3 weeks postlesion. This value increased to 66% after 6 months of survival. As seen in the electron microscope, axotomized PARV-positive neurons exhibited characteristics of vital cells. Most neurons contained lysosomes associated with Fluoro-Gold, resulting from retrograde labeling prior to fimbria-fornix transection. We conclude that mainly PARV-containing GABAergic neurons in the medial septal nucleus (MS) project to the hippocampus and are thus heavily affected by the lesion but are able to survive and restore the synthesis of PARV. The lack of significant changes in the number of GAD mRNA-expressing cells is explained by the presence of numerous GABAergic MS neurons not projecting to the hippocampus.

Animals↗
PubMed1994

Fine structure of rat septohippocampal neurons. III. Recovery of choline acetyltransferase immunoreactivity after fimbria-fornix transection.

Most cholinergic projection neurons in the medial septal nucleus (MS) lose their capability to synthesize choline acetyltransferase (ChAT) after axotomy by bilateral fimbria-fornix transection. We have recently shown that identified septohippocampal neurons survive axotomy up to 10 weeks and display fine-structural characteristics of cells in control rats. However, the fate and functional role of these neurons remained unclear. Here we describe observations made in rats which survived axotomy for 6 months. Adult Sprague-Dawley rats were subjected to bilateral transection of the fimbria-fornix system. In some animals septohippocampal projection neurons were labeled by the retrograde fluorescent tracer Fluoro-Gold (FG) prior to axotomy. After varying survival times following fimbria-fornix transection, the animals were fixed and sections of the septal region immunostained for ChAT. Three weeks postlesion, the number of ChAT-positive cells in the MS was reduced to 19% of control, suggesting a severe neuronal loss. However, 10 weeks and 6 months after axotomy this value increased to 28% and 54%, respectively. Fine-structural analysis of ChAT-positive neurons after 6 months survival revealed all characteristics of vital cells including normal input synapses. The majority of these cells could be identified as former septohippocampal projection neurons by the presence of FG. We conclude that many neurons in the MS have the capacity to restore their transmitter synthesis in a long-lasting process following axotomy.

Animals↗
PubMed1994

Survival and transmitter expression of rat cholinergic medial septal neurons despite removal of hippocampus in the early postnatal period.

It has been shown that target-derived neurotrophins are not necessary for the survival of septohippocampal cholinergic neurons in adult rats. In this study, we have removed the hippocampus in early postnatal rats by unilateral excitotoxic N-methyl-D-aspartate lesions at postnatal days 5, 10 and 20. At postnatal day 70, numerous cholinergic neurons (60% of controls) were present in the medial septum on the lesioned side. This suggests that there is only a limited influence of target-derived neurotrophic factors to these cells also in development.

Animals↗
PubMed1994

Is there a long-lasting effect of a short-term nerve growth factor application on axotomized rat septohippocampal neurons?

Loss of choline acetyltransferase (ChAT)-immunoreactive neurons in the medial septum (MS) following fimbria transection can be prevented by nerve growth factor (NGF) application. Here we have studied the long-term effects of a short-term NGF treatment starting immediately after lesion and lasting for the first 3 weeks. We demonstrate that this NGF treatment rescues many ChAT neurons after short survival time (3 weeks) but does not have a long-lasting (6 months) effect on both ChAT- and parvalbumin-immunopositive (GABAergic) MS neurons.

Animals↗
PubMed1994

Intracellular Ca2+ concentrations are not elevated in resting cultured muscle from Duchenne (DMD) patients and in MDX mouse muscle fibres.

The free intracellular calcium concentration, [Ca2+]i, was studied in single myotubes using the fluorescent Ca2+ indicator fura-2. Myotubes cultured from satellite cells of small muscle specimens from Duchenne muscular dystrophy (DMD) patients were compared with human control myotubes and with myotubes cultured from MDX and control mouse muscle satellite cells. The resting [Ca2+]i levels in DMD and control myotubes were not significantly different, i.e. 104 +/- 26 nM (mean +/- SD, n = 190 cells from eight DMD patients) compared with 97 +/- 25 nM (175/seven controls) and were not significantly lower than the corresponding murine values (154 +/- 33 nM, n = 135 MDX myotubes; 159 +/- 34 nM, n = 135 controls). All myotubes reacted to 10 microM acetylcholine or 40 mM KCl with fast transient increases of [Ca2+]i. After application of a hyposmotic (130 mOsm) solution, [Ca2+]i was increased 1.5- to 3-fold within 2-3 min, the DMD myotubes tending to stronger reactions (significantly higher [Ca2+]i in 2 out of 6 cases). The response was usually transient, [Ca2+]i decreasing to the initial level within 10 min. Gadolinium (50 microM) reduced the response by 50%-70%, indicating that the osmotic shock increased Ca2+ influx. During exposure to high (15 mM) [Ca2+]e, [Ca2+]i of DMD and control cells was 1.5- to 2-fold higher. Adult muscle fibres from MDX mice and controls showed identical Ca2+ resting levels (n = 45 fibres from three mice in each case), but did not respond to decreased external osmolarity with a change in [Ca2+]i. The results indicate that lack of dystrophin in muscle fibres does not necessarily lead to increased [Ca2+]i.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1992

Fine structure of rat septohippocampal neurons: I. Identification of septohippocampal projection neurons by retrograde tracing combined with electron microscopic immunocytochemistry and intracellular staining.

In this report the normal dendritic organization and fine structure of identified septohippocampal projection neurons is described as a prerequisite for a time course analysis of retrograde changes in these neurons following axotomy (see Naumann et al., J. Comp. Neurol. 325:219-242, 1992). Septohippocampal projection neurons were retrogradely labeled by injection of the fluorescent tracer Fluoro-Gold into the hippocampus. Next, retrogradely labeled cells in Vibratome sections of the medial septum/diagonal band complex were intracellularly stained with the fluorescent dye Lucifer Yellow (LY). Photooxidation of LY resulted in a stable electron-dense reaction product, which allowed us to study these double-labeled neurons by electron microscopy. Another series of sections containing retrogradely labeled neurons were immunostained for choline acetyltransferase (ChAT) or parvalbumin (PARV). In this way the fine structure of two different chemically characterized subpopulations of septohippocampal neurons could be compared with that of the LY-injected neurons. Intracellular filling of retrogradely labeled neurons with LY stained the cell body and the entire dendritic arbor. Essentially, three classes of neurons could be distinguished, i.e., bipolar cells, multipolar neurons, and an intermediate group. All these neurons displayed smooth, often varicose dendrites lacking spines. Mainly located close to the midline, there was a group of cells with only very few if any LY-stained dendrites. In the electron microscope, the double-labeled neurons were easily identified by numerous electron-dense lysosomes associated with transported Fluoro-Gold and the diffuse reaction product resulting from photooxidation. They displayed fine-structural characteristics as previously described for cholinergic neurons. In fact, our fine-structural analysis of ChAT-positive Fluoro-Gold-labeled neurons, but also of back-filled PARV-positive cells, gave very similar results. All these neurons had infolded nuclei, abundant cytoplasmic organelles, and a few axosomatic synapses. Thus, a plain electron microscopic study does not allow one to distinguish between subpopulations of septohippocampal projection neurons.

Animals↗
PubMed1992

Fine structure of rat septohippocampal neurons: II. A time course analysis following axotomy.

Previous light microscopic immunocytochemical studies with antibodies against transmitter-synthesizing enzymes have suggested that septohippocampal neurons undergo retrograde degeneration following transection of their axons by cutting the fimbria-fornix. However, a fine-structural analysis of the degeneration process in these cells is lacking so far. Here we have identified septohippocampal neurons by retrograde tracing with Fluoro-Gold. Thereafter, the fimbria-fornix was transected bilaterally. Fine-structural changes in prelabeled septohippocampal neurons were then studied after varying survival times up to 10 weeks. Examination under the fluorescence microscope of Vibratome sections through the septal region revealed numerous retrogradely labeled cells after all survival times following axotomy. These neurons were then intracellularly injected with the fluorescent dye Lucifer Yellow in order to stain their dendritic arbor. Many cells were found after each survival time that displayed characteristics of septohippocampal neurons in control rats (see Naumann et al., J Comp Neurol 325:207-218, 1992). In addition, increasing with survival time, there were many shrunken neurons with a reduced dendritic arbor. Representative examples of both normal appearing and shrunken neurons were photoconverted for subsequent electron microscopic analysis. Relatively few signs of neuronal degeneration were found at each survival time analyzed. The majority of cells, including the heavily shrunken ones, displayed fine-structural characteristics of normal neurons. However, a few degenerating neurons and reactive glial cells were present in all survival stages. We conclude that axotomized septohippocampal projection neurons cease the expression of transmitter-synthesizing enzymes and shrink, but many more cells survive for extended periods of time without target-derived neurotrophic factor than was assumed in previous light microscopic studies.

Animals↗
PubMed1992

Identified septohippocampal neurons survive axotomy: a fine-structural analysis in the rat.

Previous studies have indicated that interruption of the connections between the medial septum and hippocampus by cutting the axons results in degeneration and death of the projecting septal neurons. However, in these studies cell death has been inferred primarily from the loss of immunoreactivity for transmitter-specific enzymes. In the present study, we labeled septohippocampal projection neurons by retrograde tracing and then cut their axons. Subsequent intracellular injection of prelabeled cells revealed the morphology of the soma and dendrites and allowed us to examine the ultrastructure of these neurons. A large number of septohippocampal neurons survived even 10 weeks after axotomy, suggesting that axotomized septohippocampal neurons survive for considerable periods beyond the time at which they stop expressing transmitter-specific immunoreactivity. Survival of axotomized neurons is a prerequisite for pharmacological interference aimed at reactivating transmitter expression, axonal re-growth, and the eventual reintegration into functionally relevant circuitries.

Animals↗
PubMed1992

Ultrasonographic evaluation of Legg-Calve-Perthes disease based on sonoanatomic criteria and the application of new measuring techniques.

This study attempts an ultrasonographic classification of Legg-Calve-Perthes disease according to sonoanatomic and sonometric criteria. Four stages, similar to standard radiological staging, could reproducibly be found in 29 patients with unilateral disease. The stages could be significantly differentiated according to descriptive sonoanatomic criteria and partially newly introduced sonographic measurements, including epiphysis-metaphysis-index and acetabulum-epiphysis-distance. Sonographic evaluation of Perthes hips is a simple and standardised procedure, which can serve to stage and monitor the course of the disease and hence reduce the amount of X-ray exposure and treatment costs.

Child↗
PubMed1991

Comparison of different in situ hybridization techniques for the detection of human papillomavirus DNA in cervical smears.

Different hybridization methods were used for detection of human papillomavirus (HPV) DNA in cervical smears. The results obtained by filter in situ hybridization (FISH) are consistent with most of the reports recently published. To overcome the unsatisfactory limitations of this method, especially the difficulties to distinguish clearly between positive and negative signals, we developed an in situ hybridization protocol using a cytospin and 35S-labelled as well as biotinylated DNA-probes. For direct comparison of different methods, the samples were obtained from two groups of patients. One group were women with reiterated Papanicolaou smears III, IV; the other were women with reiterated Pap III, IV and additional histological scoring. In all cases but one, the different methods used have shown the same results. In one case the hybridization on slides using 35S-labelled as well as biotinylated probes gave a negative result, whereas the FISH method using a 32P-labelled probe allowed to detect of HPV 16 and 18 DNA only when more than 1 x 10(6) cells were present per filter. Our data demonstrate that in situ hybridization on slides is a specific and sensitive technique, which enables a clear distinction between positive and negative results using a small number of cells and which, especially with biotinylated probes, is suitable for application in routine work.

Biotin↗