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Biomedical subjects

E Stennert

Publications and source records attributed to E Stennert.

At least 73 records · Page 4Linked to original sources
PubMed1997

Plastination of the larynx for whole-organ sectioning.

Whole-organ sectioning is an important technique for the assessment of laryngeal pathology. Since currently established methods require prior decalcification which causes morphological changes, the critical border area between cartilage and surrounding soft tissue cannot be investigated in the same specimen and morphometric studies are not possible. Plastination is a laboratory technique that has previously demonstrated its capacity to overcome these shortcomings. In so doing water and lipids are replaced by curable polymer within the laryngeal cells making decalcification unnecessary. In the present study, more than 50 human larynges were processed using block plastination (BP) and sheet plastination (SP). For BP the complete organ was plastinated as a whole and then cut into thin serial sections. For SP the fresh organ was sliced first and plastinated in a second step. Findings demonstrated that SP allowed for the production of whole-organ sections within a period of 1 week only. Section thicknesses were as thin as 15 mm using a diamond wire saw and an ultramilling device. Sectioning was possible in both coronary and horizontal planes. Following BP, specimens were cut in an industrial cutting machine to thicknesses of about 0.6 mm. Shrinkage of tissue was less than 10% for both methods. In all, SP was technically superior to routine paraffin histology, although cutting equipment is very expensive and delicate in handling. At present the technique of BP is the method of choice for macromorphometrical investigations on serial sections of the human larynx.

Acetone↗
PubMed1997

[A registration system for evaluating acusto-mechanical transmission of middle ear implants].

A measurement system was developed that permits objective comparisons of the sound conduction of middle ear implants. The implants are fitted into a mechanical middle ear model which approximates the impedances of the eardrum and the inner ear. A defined signal within the frequency range of 0-5 kHz is provided by a miniaturized loudspeaker at the input to the model and is measured by a probe microphone. Displacement of an artificial stapes footplate at the output of the model is measured by a fiberoptic probe with a sensitivity of 5 nm. The transmission function is calculated as the quotient of the output and the input signal. This system can be used to evaluate the sound-transmitting properties of different middle ear implants excepting other influences, such as surgical techniques. This work details the measurement system and demonstrates basic influences on the sound-transmission of middle ear implants.

Acoustic Impedance Tests↗
PubMed1997

Axotomy induces transient calbindin D28K immunoreactivity in hypoglossal motoneurons in vivo.

Calbindin D28K, an intracellular calcium-binding protein, acts as Ca2+ buffering system in the cytoplasm. By means of this property, calbindin may protect neurons against large fluctuations in free intracellular Ca2+ and, hence, may prevent cell death. Although axotomy causes a massive influx of calcium into the lesioned neurons, resection of the hypoglossal nerve does not induce extensive neuronal cell death in rats. Even several weeks after axotomy, about 70% of the motoneurons survive despite permanent target deprivation. The mechanisms responsible for this remarkable survival rate are unknown. In this study, we have looked at the modification of calbindin immunoreactivity in axotomized hypoglossal motoneurons. In non-axotomized motoneurons, no calbindin is detectable by immunocytochemistry. Axotomy induced an increase of calbindin immunoreactivity in lesioned motoneurons. This increase, visualised by the number of calbindin-immunoreactive neurons extended from 1 day to 28 days. At this time most, but not all, motoneurons located on the side of the lesion were calbindin-positive as shown by retrograde labeling and immunoquenching. From 14 days post operation, calbindin immunoreactivity decreased and reached its basal value after 35 days post operation. At that time, only fibres were still calbindin immunoreactive. Interestingly, calbindin-immunoreactivity was also increased in almost all cell nuclei, compatible with a nuclear regulation. These data are consistent with the hypothesis that, as a reaction to axotomy, motoneurons trigger an increase in calbindin expression which acts as a compensatory Ca(2+)-buffering system, enabling neurons to maintain Ca2+ homeostasis and the survival of many motoneurons after axotomy.

Animals↗
PubMed1997

Nimodipine maintains in vivo the increase in GFAP and enhances the astroglial ensheathment of surviving motoneurons in the rat following permanent target deprivation.

Facial and hypoglossal nerves were resected unilaterally in a total of 108 rats. Rats were divided into two groups; one group received standard food pellets (placebo), the other received food pellets containing the Ca(2+)-blocking agent nimodipine. The expression of glial fibrillary acidic protein was examined in paraffin sections of the brainstem using light microscopical immunocytochemistry, and the degree of glial process ensheathment of the surviving neuronal perikarya in the hypoglossal and facial nuclei quantified on electron micrographs. Up to 28 days post-axotomy no differences in glial fibrillary acidic protein-immunoreactivity were observed between placebo and nimodipine-treated animals. By 42-56 days, glial fibrillary acid protein-immunoreactivity was stronger in the nimodipine treated animals and by 112 days, glial fibrillary acid protein-immunoreactive astrocytes occurred only in nimodipine-treated animals. Thin astrocytic processes were seen to ensheath neurons in both placebo and nimodipine-treated animals. By 28 days post axotomy, lesioned neurons in nimodipine treated animals were covered by a mean of 2.6 (hypoglossal) and 2.9 (facial nucleus) astrocytic lamellae, compared with 1.7 lamellae in the placebo group. This relatively greater ensheathment of hypoglossal and facial neurons was maintained up to 112 days post-lesion, but reduced in the placebo-treated group to approximately 1.4 lamellae. It is concluded that nimodipine enhances the formation of astrocytic lamellae on lesioned neurons and that this process may be associated with a protective role for activated astrocytes directed towards motoneurons suffering from permanent target-deprivation.

Animals↗
PubMed1997

[Drug treatment of invasive aspergillosis of the paranasal sinuses].

Aspergillosis belongs to the group of mycotic diseases of the paranasal sinuses. The invasive forms, and particularly the fulminant forms, are potentially fatal. Primary surgical intervention with complete removal of the mycotic mass should be performed. Additionally an antimycotic drug therapy with amphotericin B must be started. In a review of the literature, there is no case surviving an extended invasive aspergillosis after failure of the operative therapy and after failure of the postoperative amphotericin B treatment. We report an interesting case of a complete remission of an invasive, partially fulminant aspergillosis of the paranasal sinuses and frontal and basal regions. After incomplete removal of the mycotic mass by an endo- and extranasal approach, we started postoperative drug therapy with amphotericin B. Under this treatment the mycosis progressed. Additionally the patient developed severe renal side effects requiring suspension of the treatment. At this time, we started a combined antimycotic drug therapy with liposomal amphotericin B (AmBisome) and itraconazol. Within 10 weeks there was complete clinical and radiologic remission. The patient died 63 weeks after this treatment because of a fulminant bacterial pneumonia. Post mortem examination showed no aspergillosis in the skull base, the paranasal sinuses, or in the lung. The question arises as to whether this drug combination of liposomal amphotericin B (AmBisome) and itraconazol is a real alternative to high-risk surgical interventions in this region.

Amphotericin B↗
PubMed1997

Expression of different isoforms of nitric oxide synthase in experimentally denervated and reinnervated skeletal muscle.

Denervated muscle fibers express enhanced levels of stress and apoptosis-associated proteins and undergo apoptosis. In experimentally denervated and reinnervated rat facial muscle, we now evaluate changes in the expression patterns of different isoforms of nitric oxide synthase (NOS)-generating nitric oxide (NO), which mediates oxidative stress and apoptosis. Physiological expression of NOS corresponds to a constant sarcolemmal staining pattern for neuronal NOS (nNOS) and a patchy sarcolemmal and weak sarcoplasmic labeling for the endothelial NOS-isoform, with no expression for inducible NOS (iNOS). Denervated muscle displayed distinct downregulation of nNOS with preserved expression of dystrophin. Also, denervated and immediately reinnervated muscle fibers showed decreased expression of nNOS. However, muscle fibers reinnervated for 10 weeks revealed a restored physiological expression of nNOS. There were no changes in the expression of endothelial and inducible NOS. As NO is known to induce growth arrest and collapse of neuronal growth cones, downregulation of NOS may contribute to promotion of axonal regeneration by aiding formation of new endplates. NO is upregulated in reinnervated muscle fibers and thus prevents polyneural hyperinnervation by extrajunctional synapses. Furthermore, downregulation of NOS during denervation is compatible with the finding that low levels of NO contribute to apoptosis instead of necrosis in disease states of oxidative stress.

Animals↗
PubMed1997

Sheet plastination of the larynx for whole-organ histology.

Whole organ serial sections of the larynx are recognized to improve the assessment of laryngeal pathology. The human larynx with its complex anatomy of different types of tissue with their marked differences in hardness complicate the cutting process. The methods established are either very costly, time consuming and prone to artefacts, or sections are too thick for a histological work-up. Prior decalcification causes major shrinkage, thus morphometry is not feasible. We describe a technique of sheet plastination to produce whole-organ sections which allows a full-scale histological investigation without prior decalcification. Deep-frozen larynges are cut into 4-micron-thick sections using an ordinary slicing machine. Slices are dehydrated in acetone and plastinated in Biodur E50/E7/ AE10/E700. These specimens are cut into sections of about 80 microns thickness using a diamond-wire saw. An ultra-milling device reduces the section thickness down to about 10 microns. Surface staining of different kinds like Richardson, methylene blue or Paragon yields sufficient contrast for exact diagnosis. Deplastination and consecutive paraffin-like staining is possible, but results are not yet fully satisfying. Histological sheet plastination produces almost artefact- and shrinkage-free whole-organ sections in a period of about 1 week. The technique is useful for studies of micromorphometry or tumor spread. Theoretically, application of immunohistochemical staining methods seems to be possible. This might lead to mapping the proliferation activity of laryngeal cancer as it is presented on whole-organ sections.

Artifacts↗
PubMed1997

Effect of delayed facial-facial nerve suture on facial nerve regeneration. A horseradish peroxidase tracing study in the rat.

In clinical practice, the lesioned facial nerve is usually restored by facial-facial nerve anastomosis (FFA) with some delay. The optimal time-point for facial nerve reconstruction is still unknown. This study, using rats, compared the effects of immediate and delayed FFA, i.e. FFA 7-56 days after interruption of the facial nerve. Muscle reinnervation was studied 42 days after nerve suture by counting all retrogradely labelled facial motoneurons after injection of horseradish peroxidase (HRP) into the whiskerpad of the rats. Immediate FFA caused a local hyperinnervation of the target muscle, i.e. the projection of more neurons into the whiskerpad muscles than under normal conditions. FFA delayed for 7 days resulted in a significant suppression of this hyperinnervation, whereas longer delay times of 10-56 days showed no difference from immediate FFA.

Analysis of Variance↗
PubMed1997

DNA-fragmentation and expression of apoptosis-related proteins in experimentally denervated and reinnervated rat facial muscle.

Muscle fibres may undergo apoptotic cell death in several neuromuscular disorders such as denervated muscle fibres in spinal muscular atrophies. We investigated DNA-fragmentation (in situ by the TUNEL-method) and expression of apoptosis-associated proteins in experimentally denervated and reinnervated rat facial muscle up to 24 weeks after surgery to evaluate the rate and time lapse of apoptotic muscle fibre loss. While denervated muscle displayed constantly high rates of DNA-fragmentation, denervated and immediately reinnervated muscle showed a distinct decrease of primarily elevated DNA-cleavage, finally resembling rates of normal controls. Denervated muscle fibres revealed strong immunoreactivity of the anti-apoptotic proteins bcl-2 and bcl-xL, and the pro-apoptotic factor bax. In reinnervated muscle fibres, only bcl-2 was constantly upregulated while bcl-xL and bax diminished after the 7th week. The present findings indicate that denervation may prompt muscle fibres to activate an intrinsic 'suicide' programme to undergo apoptosis. High levels of bcl-2 after denervation may sustain cell survival until reinnervation, e.g. after accidental nerve damage or in neurodegenerative disorders. Furthermore, increasing levels of bcl-2 are able to neutralize high apoptosis-promoting bax levels. Interventions modifying DNA-fragmentation and the expression of apoptosis-related proteins may lead to new therapeutic concepts in denervating disorders of muscle in the absence of other primary therapies.

Animals↗
PubMed1997

[No evidence for hearing aid-induced progressive pediatric hearing loss in the Cologne region].

Progressive hearing loss during childhood caused by a hearing-aid induced deterioration has been discussed controversely since 1939. However, it is unchallenged that in cases of profound sensorineural hearing loss in infancy and early childhood powerful hearing aids are necessary for auditory and speech development. Due to an increase of progressive hearing losses during the last 4 years, we discussed the possible causes and the probability of hearing aid induced progressions once more. Our study consists of two investigations: First, all patients since 1993 suffering from progressive hearing loss among all hearing impaired children in the department of Audiology and Pedaudiology of the ENT-Hospital of Cologne were taken into account. Second, all children of the Rheinische school for hearing impaired children were investigated. The evaluated data included the degree of severity and etiology of the hearing loss, the duration of the hearing aids use and the amplification of the hearing aid. 23 children were diagnosed with a progressive hearing loss in the period. We observed a massive increase over these years. No correlation between the duration of the hearing aid usage and the maximum output level was found. Furthermore, there was no difference between the causes of the hearing losses between the children of the school and the children with progressive hearing loss. At the moment, we do not see any reason to change our strategy for fitting hearing aids. The increase of progressive cases in the last 2 years should be the reason for further investigations in this field.

Adolescent↗
PubMed1996

Nimodipine accelerates axonal sprouting after surgical repair of rat facial nerve.

Facial-facial anastomosis (FFA), i.e., suture of transected facial nerve, was performed in adult Wistar rats. For 10-112 d post-operation (DPO), half of the animals received standard food (placebo) and half received food pellets containing 1000 ppm nimodipine, a Ca2+ channel blocker. The time course of mimetic reinnervation between these two groups was compared by counting all retrogradely labeled motoneurons after injection of horseradish peroxidase (HRP) into the whiskerpad. In unoperated animals, injection of HRP labeled 1280 +/- 113 motoneurons. After FFA, this number dropped to zero, and the first HRP-labeled facial motoneurons reappeared in both placebo- and nimodipine-treated animals at 14 DPO. The treatment with nimodipine yielded two beneficial effects. (1) It accelerated axonal sprouting until 28 DPO. Whereas the number of HRP-labeled cells in the placebo group was 171 +/- 9 (mean +/- SD) at 16 DPO, 372 +/- 43 at 21 DPO, and 636 +/- 187 at 28 DPO, the number of sprouted motoneurons in nimodipine-treated rats was twice as high: 386 +/- 34 at 16 DPO, 620 +/- 28 at 21 DPO, and 756 +/- 257 at 28 DPO. (2) Nimodipine reduced the polyneuronal innervation of the target muscles. Whereas the number of HRP-labeled cells in the placebo group increased to 1430 +/- 36 at 56 DPO and 1600 +/- 31 at 112 DPO, the number of labeled motoneurons in nimodipine-treated rats remained almost within the normal range: 1315 +/- 31 at 56 DPO and 1354 +/- 33 at 112 DPO.

Anastomosis, Surgical↗
PubMed1996

ED2-positive perivascular cells act as neuronophages during delayed neuronal loss in the facial nucleus of the rat.

Injection of Fluoro-Gold (FG) into the whisker pad of rats yields a stable retrograde labeling of facial motoneurons. After removal of 10 mm from the facial nerve the microglia phagocytose the FG-prelabeled dead neurons and assume the label. A subsequent brightfield immunostaining of the sections with HRP-DAB as end-product fully quenches the fluorescence of FG from all specifically stained structures (immunoquenching). Combining FG-labeling of neuronophages with immunoquenching, we recently described a population of enigmatic fluorescent cells, found in immediate vicinity to the motoneurons after the general neuronofugal migration of microglia. As the fluorescence of these cells was not quenched after a triple immunostaining with anti neuron-specific enolase, anti-GFAP, and OX-42 (quenching all fluorescence from neurons and glia), they seemed to represent a new, immunologically not identified neuronophage. Now we have further characterized this cell type. Following triple immunostaining, we tested a broad panel of mabs (OX-33, OX-19, OX-18, OX-6, R73, ED1, and ED2) to stain, quench fluorescence, and thus immunotype the unknown phagocytes. Only the mab ED2, the classical marker for perivascular cells, specifically stained the small round neuronophages. This surprising migration of perivascular cells toward decaying neurons was additionally tested and confirmed by intracerebroventricular application of FG prior to resection of the facial nerve Providing evidence for neuronophagia by ED2-positive cells, our results strongly support the hypothesis that the latter are the APC (antigen presenting cells) of the CNS.

Animals↗
PubMed1996

Human keratinocyte culture from the peritonsillar mucosa.

Tonsillectomy tissue can be used as a routine source for cultures of oropharyngeal keratinocytes. In so doing, a peritonsillar strip of unaltered mucosa was dissected in the upper submucosa. Subsequent trypsinization yielded 7.0 +/- 3.4 x 10(6) keratinocytes per bilateral tonsillectomy. Keratinocyte attachment and growth in primary culture were promoted by sublethally irradiated 3T3 murine fibroblasts. Three subcultures could be performed without a feeder layer and were characterized by a population doubling time of 4.5 days during log growth phase. Electrophoretic and immunoblot analysis of the third subculture revealed a strong expression of keratin pairs 5/14 and 6/16 as well as keratins 7 and 19, whereas keratins 8/18 were expressed less intensely. The lowest intensity, was found for keratin 13, which is known to be indicative of the differentiated mucosa. The culture technique thus provides an easily available in vitro model for morphological and functional studies on the epithelial compartment of human oropharyngeal mucosa.

3T3 Cells↗
PubMed1996

[Self-induced illness in ENT medical practice. Artefacts as a contribution to differential diagnosis of unusual illness courses].

Until now reports of factitious disease have not been found in the ENT literature. In contrast, the dermatologic literature estimates an incidence from 0.01 to 0.26%. In order to achieve effective treatment for these patients, knowledge of the characteristic symptoms is fundamental. The present paper describes the variety of disease possible, using three cases treated between 1992 and 1994 in the ENT Department of Cologne. According to the literature, females are involved in a ratio of 9:1, with the majority working in medically related professions. Depression and anorexia are typical symptoms. When a factitious disease is suspected, psychiatric consultation is essential. Confrontation of a suspect patient by the otolaryngologist is not often considered because several reports quote suicidal behavior in up to 25% of self-manipulating patients and tendencies to refuse to follow psychiatric treatment are considerable.

Adult↗
PubMed1996

Quantitative image analysis of the chromatolysis in rat facial and hypoglossal motoneurons following axotomy with and without reinnervation.

Image analysis was used to quantify the time course of chromatolysis in regenerating and degenerating motoneurons. Following facial-facial, hypoglossal-hypoglossal nerve suture, or resection of facial and hypoglossal nerves with postoperative survival times of 4 h to 112 days, the texture of the Nissl substance of facial and hypoglossal motoneurons was analyzed on both sides of the brainstem in paraffin serial sections with a VIDASplus image analyzer. In this quantitative study of 149 Wistar rats, alterations of the Nissl substance were measured that were statistically significant but not yet visible to the human eye. Chromatolysis started significantly as early as 8 h and was not fully reversed 112 days after any of the types of axotomy. The reaction was more intense and longer lasting following axotomy without reinnervation than with reinnervation. Thus, chromatolysis starts much faster and lasts far longer than was previously known. The quantified chromatolysis is much stronger after permanent target deprivation than during complete regeneration of motoneurons but is reversible in both cases.

Animals↗
PubMed1996

Changes in eye blink responses following hypoglossal-facial anastomosis in the cat: evidence of adult mammal motoneuron unadaptability to new motor tasks.

Hypoglossal-facial anastomosis is used in humans to restore the activity of the mimic musculature following irrecoverable facial nerve lesions. As eyelid movement kinetics is very well known, we have used this experimental model in cats to follow the evolution of blink responses and the adaptability of hypoglossal motor pools to new motor tasks. Although the electromyographic activity of the orbicularis oculi muscle in response to corneal air puffs, flashes of light or electrical stimulation of the supraorbital nerve was not recovered in the seven months following this crossed anastomosis, reflex blinks were got back by the increased activity of the retractor bulbi and extraocular recti muscles. The lid of the anastomosed side oscillated in perfect synchronization with tongue movements during licking, while it was severely affected in its motor function during optokinetic stimulation because of the spontaneous appearance of tongue-related hypoglossal activity. Present results suggest that adult mammal motoneurons are unable to readapt their motor programs to the kinetic needs of new motor targets and that most of the functional recovery observed in the cat was achieved by the compensatory hyperactivity of motor systems not directly affected by the surgery.

Adaptation, Physiological↗