Biomedical subjects

E Stennert

Publications and source records attributed to E Stennert.

At least 55 records · Page 3Linked to original sources

PubMed1999

[Results of a prospective randomized trial with induction chemotherapy for cancer of the oral cavity and tonsils].

Although induction chemotherapy administered prior to local therapy produces encouraging initial response rates in head and neck cancer, randomized studies have failed to demonstrate an improvement in survival rates. All randomized studies included only patients with advanced stage III and IV disease. In our opinion, this is the main reason for the low rate of complete responses demonstrated in the randomized trials (maximum 18%). Frei et al. estimate that a 40%-50% complete response rate is necessary before improved survival rates are seen. To date, such complete response rates with induction chemotherapy have only been attainable in resectable T2-T3, N0-N2 disease. Therefore, we initiated a prospective randomized trial including only patients with the mentioned disease stages. Patients (pts) were randomized to receive either induction chemotherapy with three cycles of carboplatin/5-FU prior to surgery and radiotherapy (arm A, 70 pts) or standard treatment with surgery and radiotherapy (arm B, 74 pts). Patients were classified according to primary tumour site and neck disease. The observed remission rate after chemotherapy confirmed the primary estimated rate for this subgroup of patients with head and neck cancer (CR: 43%, PR: 37%, NR: 15%, PD: 5%). After a follow-up of 12-96 months overall survival was 58% in arm A and 45% in arm B (n.s.). Disease-free survival in arm A (61%) is statistically significantly better than in arm B (43%, P=0. 03). Therefore, we recommend further controlled trials to investigate the role of induction chemotherapy in patients with primary resectable carcinomas of the oral cavity and tonsils and stage T2-T3 and N0-N2 disease prior to surgery.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1999

[Pleomorphic adenoma (mixed tumor) of the external auditory canal. Differential diagnosis of the tumors of the ceruminal glands].

A tumor was removed from the right external auditory canal of a 69-year old female patient. The histopathological and immunhistochemical evaluation revealed a pleomorphic adenoma (mixed tumor). The differential diagnosis of the tumors derived from the ceruminal glands, their clinical and prognostic implications as well as the histogenesis of pleomorphic adenomas in this localization are discussed.

Adenoma, Pleomorphic↗

PubMed1999

Standardized measurements of the sound transmission of middle ear implants using a mechanical middle ear model.

Several ways to evaluate the sound transmission properties of middle ear implants are now established. Besides computer-based simulations using acoustic and electrical analog circuits or finite element analysis, measurements can be performed with temporal bone preparations. Experiments with these preparations consider various anatomical properties, but a large number of parameters influence the outcome of measurements. To facilitate standardized measurements, a mechanical middle ear model was developed that allows comparison of the transfer function of middle ear implants on defined conditions. The model approximates the impedances of the tympanic membrane and inner ear with the aid of thin, flexible membranes. The implants are fit between the membranes, and displacement at an artificial stapes foot-plate is measured with an optical probe. Fundamental influences on the sound transmission properties of nine different middle ear implants (total ossicular replacement prostheses) were examined. Although the material and shape were different, some of the prostheses revealed very similar transfer functions. The mass of the implant showed the largest influence on sound conduction. With a higher mass, the frequency area above approximately 1 kHz was found to be significantly deteriorated. The lightest implant used was 4 mg and showed the best overall results. These findings show that middle ear prostheses should be as light as possible for optimum high-frequency transmission.

Acoustics↗

PubMed1999

Localization of the NO/cGMP-pathway in the cochlea of guinea pigs.

The presence of nitric oxide synthase (NOS) in substructures of the cochlea of guinea pigs is an issue of current focus. Moreover, information concerning the localization of cells effected by the NO/cGMP-pathway are rare. Paraffin sections of guinea pig cochlea were incubated with specific antibodies to the three known NOS isoforms, soluble guanylyl cyclase (sGC) and cyclic guanosine-monophosphate (cGMP), the second messenger system of NO. While detection of inducible iNOS failed in all cochlear structures, expression of endothelial eNOS was found in the spiral ligament, in the stria vascularis, in cells of the organ of Corti, in nerve fibers and in some perikaryia of the spiral ganglion. The cochlear nerve showed an accentuated affinity for immunostaining in distal, basal segments of the cochlea. Neuronal bNOS was found predominantly in the endosteum of the modiolus and cochlea and was less intensively present in all perikaryia of the spiral ganglion and in the spiral ligament. Supporting cells of the organ of Corti and cells in the limbus spiralis displayed only modest immunostaining, while bNOS was not found in outer and inner hair cells. NOS detection was accompanied by immunoreactivity to sGC and to cGMP. The presence of NOS and its second messenger system gives evidence for a possible involvement in neurotransmission, regulation of the cochlear amplifier and in homeostasis.

Animals↗

PubMed1999

Contralateral trigeminal nerve lesion reduces polyneuronal muscle innervation after facial nerve repair in rats.

Functional recovery after facial nerve surgery is poor. Axotomized motoneurons (hyperexcitable upon intracellular current injections, but unable to discharge upon afferent stimulation) outgrow supernumerary branches which are misrouted towards improper muscles. We hypothesized that alterations in the trigeminal input to axotomized electrophysiologically silent facial motoneurons might improve specificity of reinnervation. To test this we compared, in the rat, behavioural, electrophysiological, and morphological parameters after transection and suture of the buccal facial nerve (buccal-buccal anastomosis, BBA) with those after BBA plus excision of the ipsi- or contralateral infraorbital nerve (ION). After BBA, the mystacial vibrissae dropped and remained motionless until 18-21 days post operation (days PO). After BBA plus ipsilateral ION excision, there was no recovery of vibrissae whisking at all. Following BBA plus contralateral ION excision, full restoration of whisking occurred at 7-10 days PO. Electromyography of whiskerpad muscles showed normal waveform and amplitude was also most rapidly restored after BBA plus contralateral ION excision. Neuron counts after retrograde tracing showed that the intact buccal nerve contained axons of the superior (91%) and inferior (9%) buccolabial nerves. After BBA, the superior nerve comprised 56%, the inferior 21%, and 23% of the motoneurons projected within both nerves. After BBA plus ipsilateral ION excision, misdirection worsened and values changed to 48, 39 and 13%, respectively. After BBA plus contralateral ION excision, portions improved to 69, 23 and 8%. We conclude that, by reducing the redundant axon branching, lesion of contralateral ION provides the best conditions for recovery of vibrissae rhythmical whisking after reconstructive surgery on the facial nerve.

Anastomosis, Surgical↗

PubMed1999

Successful treatment of an invasive aspergillosis of the skull base and paranasal sinuses with liposomal amphotericin B and itraconazole.

Invasive aspergillosis and fulminant aspergillosis are rarities with a high mortality. In the literature there is no patient surviving an extended invasive aspergillosis of the paranasal sinuses and skull base after failure of operative intervention and of postoperative amphotericin B therapy. We report a complete remission of an invasive, partially fulminant aspergillosis. After an incomplete removal of the mycotic mass, we started postoperative drug therapy with amphotericin B. Under this treatment, the mycosis progressed. Additionally, the patient developed severe side effects, so that the treatment was interrupted. At this moment, we started a combined antimycotic drug therapy with liposomal amphotericin B and itraconazole. Within 10 weeks, clinically and radiologically, there was complete remission. The patient died 63 weeks after this treatment, due to a fulminant bacterial pneumonia. Postmortem histologic examination showed no aspergillosis in the skull base, paranasal sinuses, or lung.

Amphotericin B↗

PubMed1999

Morphology of the human larynx during the first five years of life studied on whole organ serial sections.

The morphologic development of the human larynx during the first years of life is poorly understood to date. This study used plastinated whole organ serial sections to determine the growth and structure of the infant larynx. The larynges of 43 children 1 to 60 months old were plastinated. Whole organ serial sections were obtained by cutting the resulting specimen with a diamond band saw. The slices were then submitted to computer-assisted morphometric investigation. We found that the subglottic airway rapidly increases in size during the first 2 years of life. Further growth follows a linear mode. The relative proportion of the mucosal lining decreases likewise. In contrast to that in adults, and comparable to that in most mammals, the cartilaginous glottis accounts for 60% to 75% of the vocal folds' length at <2 years. No sexual dimorphism of the larynx exists during childhood. This study supplies detailed morphometric data on the growth and structure of the human larynx during the first years of life. It is the first to use plastinated whole organ serial sections for morphology of the pediatric larynx. Therefore, this study provides quantitative anatomic data of clinical interest that have not been available to date.

Child, Preschool↗

PubMed1998

ED2-positive perivascular phagocytes produce interleukin-1beta during delayed neuronal loss in the facial nucleus of the rat.

Injection of Fluoro-Gold (FG) into the whisker pad of rats yields stable retrograde labeling of facial motoneurons. Subsequent removal of 10 mm from all facial nerve branches permanently deprives the FG-labeled motoneurons from their targets and the motoneurons gradually die. Neuronal debris is phagocytized by two types of neuronophages: parenchymal microglia (monoclonal antibody [MAb] OX42-positive, MAb ED2-negative) and perivascular phagocytes (OX42-negative, ED2-positive). Because both types of neuronophages express major histocompatibility complex (MHC) class II glycoproteins (MAb OX6-positive), they are considered to be the potential antigen-presenting cells of the brain. To check this hypothesis, we tested whether both types of neuronophages also synthetize the co-stimulatory cytokine interleukin-1beta (IL-1beta) immunocytochemically visualized by MAbs SILK-5/6. Employing combined fluorescent visualization of antigens (OX6, ED2, and SILK-5/6) in sections containing fluorescent (FG-prelabeled) neuronophages, we found that, during slowly occurring neuronal loss, the vast majority of IL-1beta immunoreactive neuronophages were of perivascular (ED2-positive) origin. We concluded that, during delayed neuronal death "behind" an intact blood-brain barrier, the perivascular phagocytes were more likely to function as antigen-presenting cells than the parenchymal microglia.

Animals↗

PubMed1998

Nitric oxide synthase in the vestibulocochlear system of mice.

The exact distribution of nitric oxide-synthases (NOS) and the NO-target enzyme soluble guanylyl cyclase (sGC) in the cochlea and vestibular organ is an issue of current discussion. The existence of NOS-isoforms in the cochlea of the guinea pig has been described recently, while information about the vestibular system are still rare and non-satisfying. In order to gain more information, immunostaining was performed, using specific antibodies to NOS I-III and to sGC, on paraffin sections of complete temporal bones from mice. NOS III could be detected in cochlea and vestibular ganglion cells, in nerve fibres, in outer hair cells of the cochlear and in the sensory epithelium of the maculae. Also, the spiral ligament and the limbus epithelium was positive to NOS III. NOS I was found in the sensory epithelium of the maculae and cristae ampullares, outer and inner hair cells of the cochlea, in nerve fibres and in ganglion cells. In contrast to that NOS II could not be detected at all. Furthermore, a strong NOS I immunoreaction was displayed on the endosteum of the bone, while the periosteum was lacking of NOS. NOS detection was accompanied by immunoreactivity to sGC. The findings imply that NOS I and III-generated NO is involved in neurotransmission and other regulative processes in the vestibulocochlear system.

Animals↗

PubMed1998

Localisation of the nitric oxide (NO)/cGMP-pathway in the vestibular system of guinea pigs.

The exact distribution of nitric oxide-synthases (NOS) in the vestibular system has not been described satisfying yet. Immunostaining, using specific antibodies to the three known NOS-isoforms, to cyclic guanosine monophosphate (cGMP) and soluble guanylyl-cyclase (sGC), the second messenger system of nitric oxide (NO), was performed on paraffin sections of temporal bone from guinea pigs. eNOS could be detected in vestibular ganglion cells and in nerve fibres, including the calyces, surrounding the type 1 hair cells (HC). bNOS was found in the sensory epithelium, ganglion cells and in bone, while iNOS could not be found. NOS-detection was accompanied by reactivity to sGC and to cGMP. This finding implies that b- and eNOS-generated NO is involved in regulative processes in neurotransmission and regulation of blood flow.

Animals↗

PubMed1998

[Measuring vibration properties of middle ear implants with the mechanical middle ear model. Initial results].

With the aid of a mechanical middle ear model (MMM) the sound transmission properties of different middle ear implants were investigated. Input of the MMM involved a broad-band signal from 100 to 5000 Hz that was supplied by a miniaturized loudspeaker. Displacement of an artificial stapes footplate was measured by a fiberoptic probe. The transfer functions of four different total ossicular replacement prostheses (TORPs) of different materials and shapes were compared. Three of the devices revealed similar transfer functions which corresponded to the typical curve of the normal middle ear. One of the prostheses demonstrated a high-frequency deterioration of approximately 5 dB. This effect was explained by a 3- to 6-times higher mass of the implant when compared to the others. Altogether, the weight of the prosthesis seems to have the most marked impact on sound transmission to the inner ear, whereas stiffness of the implant itself is less crucial as long as it can be regarded as a rigid body.

Acoustic Impedance Tests↗

PubMed1998

In vitro expression of inducible nitric oxide synthase in the nasal mucosa of guinea pigs after incubation with lipopolysaccharides or cytokines.

In order to demonstrate the involvement of nitric oxide synthases (NOS)--in particular the inducible isoform (iNOS)--in inflammatory processes within the nasal airways, we used organ-bath incubation to study isolated inferior turbinates and mucosa of the maxillary sinus of guinea pigs. The pattern of the expression in various substructures of the nasal mucosa was of special interest. Mucosa was incubated for 6 h with lipopolysaccharides (LPS) produced by E. coli, interleukin II (IL-2) or tumor necrosis factor-alpha (TNF-alpha). Saline was used as the control solution. Following incubation the specimens were fixed in buffered 4% formaldehyde solution over a period of 4 h. Tissues were next exposed to nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase-reaction and immunostained with specific antibodies to iNOS. Results then showed a clearly increased or initiated expression of iNOS in epithelium, glands, leucocytes and blood vessels of treated tissues in comparison to the control specimens. The inflammatory mediator LPS and the cytokines Il-2 or TNF-alpha alone were found to be capable of increasing the expression of iNOS, although the effects of LPS clearly exceeded those of the cytokines. This finding implicates iNOS-generated nitric oxide as a key factor for causing nasal swelling, secretion and obstruction during nasal infections and allergic episodes.

Animals↗

PubMed1998

Significance of trigeminal sensory input on regrowth of hypoglossal and facial motoneurons after hypoglossal facial anastomosis in rats.

Hypoglossal facial anastomosis (HFA) is a standard surgical technique for restoration of facial movements in cases of intratemporal lesions of the facial nerve. Case reports provide evidence that an affected trigeminal system reduces functional outcome. In order to detect morphological changes in the hypoglossal nucleus responsible for this phenomenon, we used 18 Wistar rats and performed three different surgical combinations. In group 1, six animals received HFA only. In group 2, HFA was combined with resection of the contralateral infraorbital nerve. In group 3, HFA was combined with resection of the ipsilateral infraorbital nerve. Fifty-six days after the operation, horseradish peroxidase (HRP) was injected into the whisker pad. As shown in previous studies using HRP, retrograde-labelled motoneurons occurred in the hypoglossal and facial nuclei. Counts of the labelled motoneurons showed no change in the number of projecting hypoglossal motoneurons in group 2 when compared to HFA only, but a significantly smaller number in group 3 (-35%). Furthermore, the number of projecting facial motoneurons was significantly reduced in group 2 (-85%) and group 3 (-45%). These morphological findings indicate an absent or insufficient functional connection between the contralateral infraorbital nerve and the hypoglossal nucleus, and a strong influence of the infraorbital nerve to the ipsi- and contralateral facial nuclei. Additionally, our study provides morphological evidence that the integrity of the sensory trigeminal system is very important in reconstructive facial nerve surgery.

Analysis of Variance↗

PubMed1998

Variability of repeated facial nerve electroneurography in healthy subjects.

BACKGROUND: Facial electroneurography is an objective measurement of a muscle compound action potential. The amplitude ratio between the paretic and the normal side is used as a basis for estimating the prognosis of facial palsy. According to Esslen, the difference of amplitudes in healthy subjects is only 3%. Twenty healthy test persons were investigated with the aim of 1. reproducing the published data on the left-right difference in normal test subjects and 2. determining whether the amplitude ratio is constant over time after repeated measurements. STUDY DESIGN: Bilateral electroneurography was conducted on 20 healthy volunteers (age range, 23-36 y; 12 men, eight women). Two investigators performed four measurements at 1-week intervals on every subject. RESULTS: Mean amplitude ratio was 32.5%. Repeated measurements on the same individual differed considerably-- from 0% to 80%. The 99% confidence interval computed from the data ranged from 26% to 39% amplitude ratio. CONCLUSION: The symmetry of facial evoked compound potentials postulated by Esslen and Fisch is not supported by these data. As have other investigators, the authors found significant left-right differences in healthy subjects. Furthermore, they showed for the first time that the amplitude ratio is not constant in every individual at repeated measurements. In light of these data, prognosis of facial palsy based on electroneurographic data alone seems doubtful.

Adult↗

PubMed1998

Altered expression of immune-related antigens by neuronophages does not improve neuronal survival after severe lesion of the facial nerve in rats.

Injection of Fluoro-Gold (FG) into the whiskerpad muscles of rats yields a permanent retrograde labeling of motoneurons in the facial nucleus. Following subsequent resection of 10 mm of the facial nerve, one-third of the facial motoneurons die and the microglia phagocytize the dead FG-labeled neurons, take up FG, and get labeled in vivo. The resulting identification of all FG-labeled cells allows long-term comparative investigations on the behavior of neuronophages. In this study, we used two groups of rats to test whether the quantified expression of five immune-related antigens by neuronophages was related to quantified decline in neuron number (counts after immunostaining for neuron-specific enolase) 3 to 224 days after resection of the facial nerve. Rats of the first group received standard food and those of the second group, pellets containing 1,000 ppm of the calcium channel blocker nimodipine. Image analysis of the number of FG-containing cells and the number and projection area of immunopositive neuronophages in serial sections for each antigen showed that nimodipine significantly attenuated the immunostaining for CR3, MHC class I, and class II antigens (monoclonal antibodies [MAbs] OX-42, OX-18, and OX-6); enhanced the expression of monocyte-macrophage-specific antigen (MAb ED1); and did not change the expression of rat macrophage differentiation antigen (MAb ED2). The altered expressions, however, had no effect on the loss of motoneurons in the lesioned facial nucleus. We conclude that the degree of expression of immune-related antigens by neuronophages has no influence on the delayed neuronal cell death induced by permanent target deprivation.

Animals↗

PubMed1997

The use of texture analysis to study the time course of chromatolysis.

Image analysis of the textural feature entropy of the Nissl substance was used to monitor the time course of chromatolysis in regenerating hypoglossal motoneurons and degenerating facial motoneurons 4-112 days after hypoglossal-facial anastomosis in rats. Changes in the Nissl substance were detected that were not obvious on the basis of subjective judgement of the light-microscopical appearance of the neurons. Chromatolysis started 4 days post operation (dpo) and was not reversed at 112 dpo in both nuclei. The increase of chromatolysis was 14-28 dpo faster in the regenerating hypoglossal neurons than in degenerating facial neurons. Maximal chromatolysis was measured at 56-70 dpo in both nuclei. Afterwards chromatolysis persisted at a significantly higher level in the degenerating facial motoneuron pool. In conclusion, chromatolysis is a very long persisting reaction. In the beginning chromatolysis is faster and greater in regenerating rather than in degenerating neurons. In contrast, passing the maximal reaction, chromatolysis is maintained at a higher level in degenerating motoneurons. Image analysis of textural features is a suitable and reliable tool to monitor the time course of neuronal cell body changes. The presented quantitative method could be applied in any neurobiological study influencing the regeneration or degeneration of motoneurons.

Anastomosis, Surgical↗

PubMed1997

Delayed hypoglossal-facial nerve suture after predegeneration of the peripheral facial nerve stump improves the innervation of mimetic musculature by hypoglossal motoneurons.

Surgical reconstruction of the facial nerve is common clinical practice following destruction of the intracranial facial nerve. Delayed hypoglossal-facial anastomosis (HFA) is the procedure of choice, although the effect of delay on outcome remains unclear. To study the effect of delayed anastomosis on reinnervation, we sutured the proximal stump of a freshly transected hypoglossal nerve of Wistar rats to the distal stump of the ipsilateral facial nerve, which had been transected 7-56 days earlier. Animals that had received HFA without delay served as the control group. Forty days after HFA, horseradish peroxidase (HRP) was injected into the whisker pad; 2 days later, the animals were killed. Reinnervation was assessed by determining the proportion of labeled neuronal cell bodies in the brainstem. The control group had 68% reinnervation of these muscles by hypoglossal neurons and had 32% reinnervation by facial neurons. When the distal facial nerve had been allowed to degenerate for 7 days before HFA, reinnervation of the hypoglossal nerve decreased to 54%, and reinnervation by the facial nerve increased to 46%. However, after a delay of 10-56 days, the hypoglossal fraction increased and stabilized at 77%, and the facial motoneuron fraction decreased to 23%. The presence of new neuromuscular junctions was confirmed by HRP labeling of motor end plates in vivo and by electromyography. We conclude that, under the conditions of hypoglossal-facial crossed nerve suture, the predegeneration of the distal stump of a transected facial nerve enhances the reinnervation of facial muscles by hypoglossal axonal sprouts.

Animals↗

PubMed1997

Expression profile of stress proteins, intermediate filaments, and adhesion molecules in experimentally denervated and reinnervated rat facial muscle.

The immunohistochemical profiles of ubiquitin, heat shock protein 70, alpha-B-crystallin, desmin, vimentin, neural cell adhesion molecule (N-CAM), and tenascin in rat facial muscle were studied after permanent denervation by transection of the facial plexus on one side and compared with findings after immediate reinnervation by hypoglossal-facial nerve anastomosis subsequent to transection on the contralateral side. Levator labii muscle samples were collected sequentially at 2, 6, 7, 10, 20, and 24 weeks after surgery. Normal levator labii muscle fibers showed physiological expression of desmin and alpha-B-crystallin. Denervated rat facial muscle displayed distinct up-regulation of ubiquitin, alpha-B-crystallin, N-CAM, and tenascin. While alpha-B-crystallin and N-CAM decreased in long-standing denervation, tenascin had completely disappeared at 6 weeks. Like-wise, reinnervated muscles displayed enhanced expression of ubiquitin, alpha-B-crystallin, N-CAM, tenascin, and, additionally, desmin. Strong expression of desmin and ubiquitin was found up to the 10th week as well as of alpha-B-crystallin, N-CAM, and tenascin up to the 7th week of reinnervation. Afterward, expression of stress proteins, intermediate filaments, and adhesion molecules returned to expression profiles of normal controls, indicating that enhancement of these proteins was restricted to the "atrophic and regenerative" states with a decline to physiological levels after successful reinnervation and restoration of muscle fibers. Furthermore part of regeneration from damage seems to resemble reactivated developmental mechanisms by reappearance of developmentally expressed proteins like desmin, N-CAM, and tenascin.

Anastomosis, Surgical↗