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Biomedical subjects

O Michel

Publications and source records attributed to O Michel.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Transnasal surgery of the orbita. Review of current indications and techniques].

The endonasal surgery has a branch in the transnasal orbital surgery. For this transnasal approach the anterior skull base, the medial and infero-medial orbita, the orbital apex with the optical nerve and the sphenoid sinus are within reach. In all primary and secondary malignant lesions with extension into the orbita, the transnasal biopsy is of importance for diagnosis, particularly in metastasis to the orbit and pseudo-tumors. Benign lesions like mucoceles and osteomas are accessible and fully removable. Good results have been obtained in endonasal orbital decompression and inhomogeneous space occupying intraorbital lesions like bleedings. Among the orbital traumatism, with restrictions fractures of the medial orbital wall, medial orbital floor and foreign bodies could be operated. The transnasal approach is not indicated in all diseases, which are situated mostly intraconally, supraorbitally and lateral of the bulbus as well as in tumors with intracranial extension. In summary, the transnasal orbital approach has its place as helpful addition to the transfacial and transcranial techniques and can even replace them in certain selected indications.

Biopsy↗
PubMed2000

[The Stennert antiphlogistic-rheologic infusion schema in treatment of cochleovestibular disorders].

The pathogenetic mechanisms of acute cochleo-vestibular lesions are still unknown, but viral infections and vascular phenomena with impairment of microvascular perfusion are thought to play a major role. Between 1 July, 1986 and 28 February 1998, 1501 patients were treated with an infusion protocol using cortisone, dextrane 40 and pentoxifylline. Group 1 contained 1001 patients with sudden hearing loss, group 2a 107 patients with isolated tinnitus and group 2b 393 patients with labyrinthine disorders (among which were 81 patients with cochleovestibular dysfunction). The records were evaluated retrospectively. In group 1 complete hearing recovery occurred in 44.8%, partially in 40.4%, no change in 12.1% and worsened in 2.6%. In group 2a with isolated tinnitus 17.9% had a complete recovery, 43.9% partial recovery, 35.5% no change and 2.8% worsened symptoms. In group 2b vertigo disappeared in 56.8%, had partial recovery in 21.0% and did not change in 7.4%. In the 1501 patients treated, no significant side-effects were found to the medical interventions used. From these results we conclude that the infusion protocol is safe and effective in the treatment of cochleo-vestibular disorders.

Adolescent↗
PubMed2000

[Epithelialization model of non-biological tissue replacement materials in vitro].

Successful use of non-biologic implants in reconstructive head and neck surgery is dependent on tissue compatibility and epithelization. This is true not only for epithelial cells, but also for mesenchymatic cells. Therefore we tested several substrates with human fibroblasts or keratinocytes from the oral mucosa in cell culture. In tissue culture keratinocyte outgrowth from small mucosal flaps onto the surface was observed. Preparations were evaluated by histology and scanning electron microscopy. Cellulose-ester, polyvinylidene-difluoride and polyglactin developed monolayers of fibroblasts and keratinocytes in cell cultures. In tissue culture mucosal flaps showed good adherence to the surface of these materials and a fine outgrowth of keratinocytes. Expanded polytetrafluor-ethylene (ePTFE) was partially covered by a layer of fibroblasts and keratinocytes in cell culture, but cell adherence was not sufficient. In tissue culture the mucosal flaps failed to attach on ePTFE. These results illustrate that the mesenchymatic and epithelial component of cell and tissue cultures show different qualities of cellular adherence and growth on the surface of non-biologic implants. We propose our method for the development of an in-vitro model for the epithelization of non-biologic implantation materials.

Cell Adhesion↗
PubMed2000

[Detection of nitric oxide synthases in physiological and pathophysiological processes of the nasal mucosa].

Nitric oxide (NO) can play an important role in the regulation of vascular tone and neurotransmission, as well as in non-specific immunoreactions and inflammation in a variety of tissues. Increased quantities of nitric oxide in respired air can be measured during inflammatory processes. However, the exact role and precise sources of NO under physiological and pathophysiological conditions within the airways remain to be defined. Three isoforms of NO-synthases can be distinguished: two constitutive (neuronal and endothelial) Ca(2+)-dependent cNOS and one inducible Ca(2+)-independent iNOS (NOS II). Constitutive NOS (NOS I and III) release a basal amount of NO under physiological conditions. The inducible form once expressed can catalyse the generation of large quantities of NO. Many kinds of cells, such as macrophages, neutrophils, endothelium and smooth muscle cells, are capable of expressing NOS II. Since all isoforms of NO-synthase seem to be present in nasal tissues and the expression of iNOS under inflammatory conditions seems to be responsible for excessive production of NO, the distribution of NOS-isoforms (especially NOS II) in normal and inflammatory nasal tissue, as well as the exact requirements for expression of iNOS remain to be proven. Non-inflamed fresh human nasal mucosa from the middle turbinate was compared immuno-histologically with nasal mucosa having the typical findings of chronic polypoid rhinosinusitis (i.e., polypoid middle turbinates and polyps of the middle nasal duct). In order to gain more information about the mechanisms of acute inflammation, non-inflamed vital turbinates were incubated in vitro with the proinflammatory substances bacterial lipopolysaccharides (LPS) and tumor necrosis-factor (TNF) for 30, 60, 90, 120, 180 and 240 min. Subsequent to exposure to NADPH-diaphorase and immunostaining with specific antibodies to each NOS-isoform, clearly increased or initiated expressions of inducible NOS (iNOS) in blood vessels, glands, macrophages and epithelium of chronically inflamed and LPS-incubated nasal tissue became apparent in comparison to the non-inflamed controls. In contrast, NOS III/NOS I seemed to be not affected. The onset of immunohistochemically recognizable NOS II expression was observed after 90 min incubation with of LPS/TNF-alpha. Polypoid tissue showed a strong increase in submucosal thickness and a high infiltration of iNOS-positive leukocytes (granulocytes and macrophages) compared to the LPS-incubated non-inflamed specimens. These findings implicate NOS II generated nitric oxide as a key agent for causing swelling, secretion and obstruction in patients with acute and chronic polypoid or allergic rhinitis. These findings also suggest that molecular NO has to be considered in the pathophysiology of chronic polypoid rhinosinusitis.

Chronic Disease↗
PubMed2000

[Beta-trace protein in diagnosis of cerebrospinal fluid fistula].

Beta-trace protein is a lipocalin that was recently identified as prostaglandin D synthase and represents a major constituent of human cerebrospinal fluid. Beta-trace protein, similar to beta 2-transferrin, has been used as an immunological marker for the detection of cerebrospinal fluid. Between 1982 and 1999, 130 specimens from 101 patients with suspected cerebrospinal fluid leaks of the anterior or lateral skull base have been investigated for beta-trace protein. The specimens were analyzed by one-dimensional immunoelectrophoresis using Laurrell's electroimmunoassay. In all, beta-trace protein could be detected in 57 specimens and was absent in 73. All case notes were studied retrospectively. In correlation with the clinical course and the findings of CT of the paranasal sinuses, high resolution CT of the petrous bones, CT cisternography, NMR, 111In-DTPA radionuclide cisternography, intraoperative findings, visualization of sodium-fluorescein stained cerebrospinal fluid using endoscopic blue light or testing for glucose, there was no false-positive result. A false-negative result occurred in two cases. These findings show that the beta-trace test has a sensitivity of 97.3% and a specificity of nearly 100%. Our findings show that analysis of beta-trace protein can be a valuable test for detecting CSF leakage and has certain advantages in comparison with the beta 2-transferrin assay.

Adolescent↗
PubMed2000

Effect of irrigation of the nose with isotonic salt solution on adult patients with chronic paranasal sinus disease.

In a prospective, randomized, controlled, double-blind trial we compared the effectiveness of endonasal irrigations with Ems salt solution to that with sodium chloride solution in the treatment of adult patients with chronic paranasal sinus disease. Subjects (n = 40) were randomly allocated to treatment either with isotonic Ems salt solution or with isotonic sodium chloride solution. The treatment consisted of endonasal irrigation twice daily and additional nasal spray as required. Nasal endoscopy, plain radiography of the paranasal sinuses, olfactometry, anterior rhinomanometry, and a saccharin-clearance test were carried out on days 1 and 7. Patients recorded rating scales of general discomfort, nasal airway obstruction, agreeableness of the irrigation, duration of improved nasal resistance after each irrigation, and the amount of additional nasal spray in a diary. Nasal air flow was not improved significantly. Subjective complaints, endonasal endoscopy, and radiography results revealed a significant improvement in both groups (P = 0.0001). In comparison, the two groups were not significantly different in outcome. Endonasal irrigations with salt solutions are effective in the treatment of chronic sinusitis, and a significant difference between Ems salt and sodium chloride was not observed.

Adult↗
PubMed2000

Involvement of nitric oxide synthase in the physiology and pathophysiology of facial nerve function and dysfunction.

To date few reports have discussed the presence and function of nitric oxide (NO) in structures of the facial nerve. We performed nicotinamide adenine dinucleotide phosphate (NADPH-d)-diaphorase-histochemistry and immunohistochemistry on the intratemporal portion of the facial nerve, including the geniculate ganglion, of guinea pigs using specific antibodies to the three known isoforms of NO synthase and soluble guanylyl-cyclase (sGC). Normal facial nerves were compared to those treated intratympanically with bacterial lipopolysaccharides (LPS) and tumor necrosis factor-alpha (TNF-alpha). Both constitutive NOS isoforms and sGC could be detected in the bipolar ganglion cells of normal animals, while the inducible isoform (iNOS or NOS II) was not found. Endothelial NOS (NOS III) and sGC were present in blood vessels and were predominantly found in the perineurial sheath and less in the endoneurium. sGC could be detected in all fibers in a cross section of the facial nerve. LPS and TNF treatment led to the detection of iNOS in the perikaryia of the geniculate ganglion and the perineural sheath. These findings imply that NO may be involved in neurotransmission at least in the visceroafferent system. NO regulates vascular tone of nutrient blood vessels in the perineural sheath and endoneurium. The presence of sGC indicates that NO acts via its second messenger cGMP. NOS II expression may be a contributing factor to facial nerve palsy via two different mechanisms: NOS II-generated NO may lead to an overstimulation of the visceroefferent nerve fibers and motor fibers of the facial nerve. Dysregulation in facial nerve blood vessels could lead to edema and elevated pressure on the nerve within its osseous canal.

Animals↗
PubMed2000

Helper T-cell responses elicited by Der p 1-pulsed dendritic cells and recombinant IL-12 in atopic and healthy subjects.

BACKGROUND: Environmental allergens, such as Dermatophagoides pteronyssinus group 1 antigen (Der p 1), induce T(H2)-type responses in atopic patients, whereas healthy individuals have T(H1)-type responses to the same antigens. Because of their efficient synthesis of IL-12, dendritic cells (DCs) are potent inducers of T(H1)-type immune responses. OBJECTIVE: We sought to determine whether DCs would skew allergen-specific T(H2)-type responses from atopic individuals. METHODS: Purified CD4(+) T cells from healthy donors or atopic individuals were cultured in the absence or presence of recombinant (r)IL-12 with DCs derived from PBMCs and pulsed with Der p 1. Supernatants of DC-T cell cocultures were assayed by ELISA for IL-5 and IFN-gamma. RESULTS: A T(H1)-type response developed in purified CD4(+) T cells from healthy donors in response to Der p 1-pulsed DCs, as indicated by high levels of IFN-gamma in culture supernatants. In contrast, CD4(+) T cells from atopic donors displayed a T(H2)-type profile characterized by high levels of IL-5 and low levels of IFN-gamma. The addition of rIL-12 (10 ng/mL) to DC-T cell cocultures resulted in the induction of IFN-gamma secretion by Der p 1-specific CD4(+) T cells from atopic patients, whereas their production of IL-5 was not inhibited. Using flow cytometry after intracytoplasmic staining, we found that IFN-gamma and IL-5 were secreted by distinct CD4(+) T-cell subpopulations. CONCLUSION: The cytokine profile of Der p 1-specific T(H2)-like cells from atopic individuals is maintained when the allergen is presented by DCs, even in the presence of exogenous rIL-12.

Allergens↗
PubMed2000

Expression of inducible nitric oxide synthase (iNOS/NOS II) in the hydropic cochlea of guinea pigs.

Immunohistochemical investigations of the guinea pig cochlea, using a specific antibody to the inducible isoform of NO synthase (iNOS/NOS II), have been performed 3 weeks after closure of the right endolymphatic duct (n=7). Endolymphatic hydrops, the morphological substrate of Meniere's disease, became evident by distension of the Reissner's membrane. iNOS expression could be noted in endothelium, spiral ganglion cells, in nerve fibers, in supporting cells of the organ of Corti and cells of the spiral ligament. Temporal bones of non-operated controls (n=6) as well as of sham-operated animals (n=3) did not show structures positive to iNOS. These findings imply that iNOS-generated NO could be involved in the pathophysiology of cochlear dysfunction in Meniere's disease.

Animals↗
PubMed2000

Changes of the compound action potential (CAP) and the expression of inducible nitric oxide synthase (iNOS/NOS II) in the cochlea under the inflammatory condition(1).

In this study, the effect of endotoxin on the guinea pig cochlea has been examined electrophysiologically and immunohistochemically. Bacterial lipopolysaccharide (LPS, 5 mg/ml, 0.2 ml) was injected into the middle ear trans-tympanically. The electrocochleograms were measured before, immediately upon, and 3, 6 and 12 h after the injection continuously with an electrode inserted into the facial canal. After each measurement, some of the animals were killed with an intracardiac perfusion of fixative, temporal bones were removed and were immunohistochemically examined for inducible nitric oxide synthase (iNOS/NOS II). On serial paraffin section, iNOS could be detected first after 3 h in the lateral wall, the supporting cells of the organ of Corti and in cells of the spiral ganglion and was observed up to 12 h. After the injection of LPS, the threshold of compound action potential became significantly worse after 12 h in the LPS group. These changes became evident first at higher frequency (8 kHz). These results suggest that iNOS-generated NO is involved in the cochlea dysfunction under inflammatory conditions.

Action Potentials↗
PubMed2000

Effect of anti-asthmatic drugs on the response to inhaled endotoxin.

BACKGROUND: Endotoxin is a pro-inflammatory agent contaminating the dust that has been associated with the risk to develop pulmonary diseases. There is no data on the protective efficacy of anti-asthmatic drugs on the response induced by inhaled endotoxin in human. METHODS: Twelve mildly asthmatic subjects were submitted weekly to bronchial challenge tests with 20 microg endotoxin. The response was evaluated by the changes in FEV1, blood cells count, neutrophils activation (measured with the luminol-enhanced chemiluminescence) and blood concentration in the acute phase proteins, C-reactive protein (CRP) and haptoglobin. In a double-blind randomized cross-over placebo-controlled design, a single dose each of 500 microg beclomethasone dipropionate, 200 microg salbutamol, and 50 microg salmeterol were administered 30 minutes before the endotoxin challenge test. RESULTS: The 20-microg endotoxin challenge test induced a significant decrease in FEV1 and luminol-enhanced chemiluminescence (P < .001 and <.05, respectively). There was an increase in the blood neutrophils count (P < .05), in CRP (P < .02) and in haptoglobin (P < .03) concentrations. Pretreatment with beclomethasone dipropionate did not have any significant effect on the response to inhaled endotoxin. Salbutamol and salmeterol completely prevent the FEV1 decline due to their potent bronchodilatation activity. Salmeterol and salbutamol did not have any significant effect on the blood inflammation induced by endotoxin inhalation. CONCLUSION: The bronchodilating properties of beta2-agonists prevent the lung function response to inhaled endotoxin. When given in a single dose, an inhaled corticosteroid does not have protective activity on the endotoxin-induced blood inflammation.

Administration, Inhalation↗
PubMed2000

[Experience with endonasal endoscopic surgery of inverted papilloma of the nose and paranasal sinuses].

BACKGROUND: The inverted papilloma of the nasal cavity and the paranasal sinuses is a benign but locally aggressive neoplasm with a high recurrence rate and an unknown risk of malign transformation. This unsteadiness of biological behaviour requires a permanent control of the outcome of the available surgical treatments to ensure the utmost reliability for the patients. METHODS: In our investigation we analysed the surgical results in 54 patients with inverted papilloma of the last 30 years with an average followup of 55 months. 25 of them were endoscopically treated. The other group of 29 patients was treated by traditional surgical techniques using an extra-nasal approach. RESULTS: Using the endonasal-endoscopic technique we observed a recurrence rate of 48% whereas the other group treated by an extra-nasal approach reached a recurrence rate of only 24% and did not show any multiple recurrences. A malign transformation was found in two patients (< 5%) within the first 8 months after the first resection. CONCLUSION: In consequence patients with inverted papilloma have to be informed of the different surgical techniques and their recurrence rates. Especially an endonasal-endoscopic treatment of the maxillary sinus has to be carefully considered.

Endoscopy↗
PubMed2000

[Classification and prognosis of esthesioneuroblastoma based on 7 treated cases].

BACKGROUND: The esthesioneuroblastoma is a rare tumour of neuroectodermal origin, which arises usually in the area of the olfactory epithelium and invades the paranasal sinuses, the orbit and the brain. The low incidence of this disease makes a development of standardised clinical and histological classification difficult. Up to now this tumour is considered to be slow progressive but strained by a high rate of local recurrences. Metastasis are usually seen late at an advanced stage. PATIENTS: In the last 18 years 7 patients with an esthesioneuroblastoma were treated in our department. This relatively large number of patients allows a retrospective evaluation of the different already existing classifications concerning treatment and prognosis. RESULTS AND CONCLUSIONS: In all cases of a disease limited on the paranasal sinuses the patients were successfully treated either by a combination of resection and radiation (4 cases) or resection alone (1 case). No patient underwent a chemotherapy. Two cases with lethal outcome showed an extremely aggressive tumour progression. In such cases of extensive disease an additional chemotherapy has always to be taken into account. Our experiences and the analysis of the literature gives some indications that middle-aged patients have a worse prognosis than young or old patients.

Adult↗
PubMed2000

Preliminary report on the results of the second phase of a round- robin endotoxin assay study using cotton dust.

In an on-going endotoxin assay study, a two-part interlaboratory endotoxin assay study has been completed. The purpose of the study was to compare the variation in assay results between different laboratories, and, if the variation was high, to see if a common protocol would reduce the variation. In both parts of the study, membrane filters laden with the same approximate amount and type of cotton dust were sent for analysis to laboratories that "routinely" perform endotoxin analyses. First, each of these laboratories performed the analysis using the methodology common to its laboratory. In the second part of the study, membrane filters with cotton dust were again sent to the same laboratories where the analyses were performed as before but with a common extraction protocol. The preliminary results from the first phase of the study have been collected and showed that intra-laboratory variations were small, but large and significant interlaboratory variation was observed. The results were reported elsewhere. The preliminary results from the second part of the study consisting of the data currently collected are presented here. Again, intra-laboratory variations were small, but, also again, large and significant inter-laboratory variation was observed. However, in this part of the study, the range between the highest and lowest average results was narrower than in the first part of the study. Influence of the assay kit type was examined. The variation within assay kit type was small but significant differences in results were observed between assay kit types. The findings suggest that endotoxin concentration in samples can be ranked within laboratories, but not necessarily between laboratories. However, some of the variation between laboratories has been reduced by a common extraction protocol which suggests the possibility of further standardization that may lead to better comparability between laboratories.

Air Pollution, Indoor↗
PubMed2000

Inhibition of inducible nitric oxide synthase lowers the cochlear damage by lipopolysaccharide in guinea pigs.

Endotoxin-treated cochleas of the guinea pig were examined electrophysiologically and immunohistochemically concerning the expression of inducible nitric oxide synthase (iNOS/NOS II). One mg of bacterial lipopolysaccharide (LPS, 5 mg/ml) or mixed solution of 1 mg of LPS plus 1 mg of N(G)-nitro-L-arginine methyl ester (L-NAME, 5 mg/ml) (L-NAME/LPS) was injected into the middle ear of guinea pigs transtympanically. The electrocochleograms were measured prior to, immediately and 48 h after the injection. Immunohistological studies for iNOS followed after fixation, embedding and sectioning of the temporal bones. The threshold and amplitude of the compound action potential (CAP) became significantly worse in the LPS treated group. In contrast, the changes of the threshold and amplitude of CAP were decreased in the L-NAME/LPS group. iNOS was expressed in the stria vascularis, the spiral ligament, the organ of Corti and the spiral ganglion in the LPS group. These immunoreactivities in the L-NAME/LPS group were less intense than that in the LPS group. These results indicate that LPS has an ototoxic effect on the cochlea and that this effect could be mediated by iNOS produced high nitric oxide under inflammatory conditions.

Animals↗
PubMed2000

Oxidative stress occurs in absence of hyperglycaemia and inflammation in the onset of kidney lesions in normotensive obese rats.

BACKGROUND: Several factors favour the development of kidney lesions. We examined the role of oxidative stress in the onset of renal alterations that occur in Zucker obese (ZO) fa/fa rats. METHODS: Kidney structure, biological data, glycation parameters, advanced glycation end products (AGE), thiobarbituric acid-reactive substances (TBARS), circulating antibodies anti-malondialdehyde (MDA)-modified low-density lipoprotein (LDL), antioxidant defenses (Cu/Zn and Mn superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) activities, glutathione level), were determined in plasma and/or kidney of young and old ZO rats and lean (ZL) Fa/fa littermates. RESULTS: Renal lesions and functional decline appeared at 3 months in hyperlipidaemic, hyperinsulinaemic, normotensive ZO rats, independently of any macrophage-ED(1)(+)-cell infiltration. At 6 months and thereafter, kidney lesions and functional impairment worsened while numerous ED(1)(+)-cells invaded the interstitium. At 3 and 9 months, TBARS level in the LDL/very low-density lipoprotein fraction and in the kidney was higher in ZO than in ZL rats. Anti-MDA-LDL antibodies were increased in ZO rats. At 3 months, renal activity of Cu/Zn SOD was higher, and activities of catalase and GPx lower in ZO than in ZL rats, leading to an accumulation of hydrogen peroxide (H(2)O(2)). At 9 months, a decrease in Cu/Zn SOD activity and an increase in glutathione level were observed. Blood glucose and glycated proteins, as well as AGE in kidney, remained similar in both ZL and ZO rats, whatever their age. CONCLUSION: These data suggest that oxidative stress triggers, at an early age, the onset of kidney lesions and functional impairment in ZO rats, in absence of hyperglycaemia, hypertension and inflammation.

Animals↗
PubMed2000

Expression of inducible nitric oxide synthase (iNOS/NOS II) in the vestibule of guinea pigs after the application of cisplatin.

It is well known that the anti-cancer drug cisplatin has an ototoxic property; however, the details are not yet evident. In this study, the expression of inducible nitric oxide synthase (INOS/NOS II) in the vestibule of guinea pigs after i.p. injections of cisplatin was examined immunohistochemically. Three days after the injection of cisplatin (10 mg/kg) or placebo, animals were sacrificed. Then the temporal bones were removed and subjected to Immunohistochemical studies for iNOS. In the cisplatin group, INOS was detectable, whereas the tissue in the control group was negative for iNOS. The vestibule, the wall of blood vessels and the vestibular ganglion cells showed immunoreactivity for iNOS. It is known that INOS catalyzes an inadequate quantity of NO under pathological conditions. Increased NO levels lead to inner ear dysfunction. Therefore, our results indicate that iNOS could also mediate the vestibulo-toxicity of cisplatin.

Animals↗