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Biomedical subjects

M Tos

Publications and source records attributed to M Tos.

At least 91 records · Page 5Linked to original sources
PubMed1996

Penicillin reduces secretory capacity in rat middle ear mucosa in acute otitis media.

In the United States, antibiotic treatment of acute otitis media is almost mandatory, whereas several other western countries are more reticent. Most clinical trails on antibiotic effect have important methodologic flaws, making an overall interpretation quite difficult. This study determined the effect of penicillin V administration on the secretory capacity of rat middle ear mucosa, during and after acute pneumococcal otitis media, by quantitative studies of the goblet cell density. The right middle ear bullae of 25 rats were inoculated with type 3 pneumococci. Beginning 2 days after inoculation, penicillin V 100 mg/kg/day was administered orally for 5 days. After inoculation, five randomly selected rats were killed on days 4, 8, 16, 90, and 180. The middle ear bullae were removed, split in half, stained with periodic acid-Schiff (PAS)-alcian blue, and the mucosae dissected from the bone. Whole mounts were prepared and the goblet cell density determined in 24 well-defined localities, making a total of 160 counts per ear and covering the entire bulla mucosa. Goblet cell densities were compared with those of 25 normal ears and 25 inoculated, untreated ears. Except on day 4, the penicillin V-treated ears had a significantly lower goblet cell density in almost all localities, on all days of death, when compared with untreated ears. Six months after the acute incident, the goblet cell density was almost normal. However, the enlargement of the mucosal area containing goblet cells seen in untreated ears was unaffected by penicillin V administration. We conclude that administration of penicillin V reduces the increase in secretory capacity of rat middle ear mucosa during and 6 months after acute pneumococcal otitis media.

Acute Disease↗
PubMed1995

[Acoustic neurinomas/vestibular schwannomas. Diagnostic evidence vs. surgery].

+-f having vestibular schwannoma (VS) was conducted in a series of 123 patients (127 tumours), over a 20 year-period from 1973 to 1993. Mean follow up period was 3.4 years, mean annual growth rate was 3.2 mm/year. Tumour growth was observed in 90 patients (94 tumours, 74%), no growth was seen in 23 patients (23 tumours, 18%) and negative tumour growth in 10 patients (10 tumours, 8%). Surgery due to tumour growth was performed in 35 patients (35 tumours, 28%). Seven patients (seven tumours, 6%) were treated with gamma radiation and/or shunt insertion. Seven patients (6%) died of brainstem herniation induced by tumour compression. Nine patients (7%) died of non tumour related causes. Twenty-eight patients were classified as candidates for hearing preservation surgery and 21 patients (75%) lost their candidature during the observation period due to tumour growth and/or deterioration of hearing. The results may limit indications for allocation of patients with VS to the "wait and see" group.

Adolescent↗
PubMed1995

Acoustic neuroma (vestibular schwannoma): growth and surgical and nonsurgical consequences of the wait-and-see policy.

A prospective study of the consequences of the wait-and-see policy in in patients with neuroradiologic diagnostic evidence of having vestibular schwannoma was conducted in a series of 123 patients (127 tumors) over a 20-year period, from 1973 to 1993. The mean follow-up period was 3.4 years, mean annual growth rate was 3.2 mm/year, mean annual volume growth rate was 0.72 ml/year, and mean annual relative growth rate was 41%. Tumor growth was observed in 90 (74%) patients (94 tumors), no growth was seen in 23 (18%) patients (23 tumors), and negative tumor growth was seen in 10 (8%) patients (10 tumors). Surgery due to tumor growth was performed in 35 (28%) patients (35 tumors), 7 (6%) patients (7 tumors) were treated with gamma-radiation and/or shunt insertion, 7 (6%) patients died of brain stem herniation induced by tumor compression, 9 (7%) patients died of non-tumor-related causes, 28 patients were classified as candidates for hearing preservation surgery, and 21 (75%) patients lost their candidacy during the observation period due to tumor growth and/or deterioration of hearing. The results may limit indications for allocation of patients with vestibular schwannoma to the wait-and-see group.

Adolescent↗
PubMed1995

Sinonasal papillomas: a report of 82 cases in Copenhagen County, including a longitudinal epidemiological and clinical study.

The present epidemiological and clinical study comprises 82 patients with sinonasal papillomas diagnosed from 1975 to 1993. Histology showed 58 cases of inverted papillomas including 5 cases of associated carcinoma, 19 cases of exophytic papilloma, and 5 cases of columnar cell papilloma. The incidence of sinonasal papillomas in Copenhagen County was 0.74 per 100,000 inhabitants per year. The inverted and columnar cell papillomas were typically located in the middle meatus with a varying degree of involvement of the adjacent sinuses. The exophytic papillomas were predominantly located multicentrically on the nasal septum. Good results of treatment, especially with regard to inverted papillomas, were not correlated to the aggressiveness of surgery. A lateral rhinotomy with medial maxillectomy was performed as primary surgery in 28 patients. In 50% of these patients there were recurrences. The preliminary results of endonasal endoscopic surgery revealed a high success rate, i.e., no recurrences in 5 cases so far. The septal papillomas were typically resected by a simple endonasal procedure. There were recurrences in 66% of these cases. The midfacial degloving procedure may be advocated instead of or as a supplement to the lateral rhinotomy if the tumor cannot be visualized sufficiently by endoscopy. Smoking may dispose to sinonasal papillomas.

Adolescent↗
PubMed1995

Polyp pathogenesis--a histopathological study in experimental otitis media.

We examined the mucosa of 50 rat middle ears in an experimental model of acute otitis media, in order to obtain information on the mechanisms of polyp formation. The right middle ear of 25 rats was inoculated with type 3 pneumococci, and the left ear served as a control. The animals were killed, the middle ear bulla removed, and the mucosa was dissected from the bone, stained PAS-alcian blue and embedded as a whole-mount. The whole-mounts were examined in a light microscope for polypous mucosal prominences. Serial sections were made of all polyps, and of relevant parts of the mucosa. 15 polyps were found in 11 (44%) of 25 infected ears; none were found in normal control ears. Goblet cell density was increased in polyps and the surrounding epithelium. Epithelial microruptures were seen in areas with widespread intra-epithelial liquid vacuoles and subepithelial accumulation of liquids, luminally migrating inflammatory cells, increased vascularization and edema. Connective tissue of the lamina propria was prolapsed through most ruptures. Some prolapses showed signs of re-epithelialization, while others had a full epithelial lining that resembled a fully developed polyp. Our findings support our earlier theory on nasal polyp pathogenesis, based on the following stages: i) Localized rupture of the epithelial lining. ii) Luminal protrusion of the lamina propria through the epithelial defect. iii) Re-epithelialization of protruded tissue, and formation of a polyp.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Electromagnetic ossicular augmentation device.

Conventional hearing aids have a number of limitations inherent to amplifying sound in the narrow confines of the external auditory canal. Disadvantages include acoustic feedback, poor fidelity, and the stigmata of aging. Since 1986, Michigan Ear Institute and Smith and Nephew Richards Company have been investigating the feasibility of a new device that converts sound to an electromagnetic field. The efficacy and safety of electromagnetic-induced hearing was sufficient enough to have the Federal Food and Drug Administration approve a pilot study of ten patients with a sensorineural hearing loss in whom a target magnet is implanted beneath the tympanic membrane. A status report of this study and a review of our preceeding investigations are presented in this article.

Audiometry, Pure-Tone↗
PubMed1995

Changes in goblet cell density in rat middle ear mucosa in acute otitis media.

This study was undertaken to determine quantitative histologic changes after a single episode of acute suppurative otitis media in the rat middle ear mucosa, with special reference to goblet cell density, and to determine the persistency of these changes. Drum vascularization, purulent effusion, mucosal thickness, bone and subepithelial gland formation was assessed. Twenty-five rats were inoculated with viable pneumococci type 3 through the right, bony middle ear bulla. The left bulla served as control. At days 4, 8, 16, 90, and 180 after inoculation, five rats were sacrificed on each occasion; the bullae were removed, opened, and divided into two halves, which were stained according to the periodic acid-Schiff (PAS)-alcian blue method. The stained mucosa was dissected from the bone and placed in an anise oil-colophonium chamber, for determination of interindividual median density and range of goblet cells by light microscopy. Counting was performed in 24 well-defined localities, covering the entire bulla mucosa and the drum. Areas normally containing goblet cells were extended. Goblet cell density was significantly (Mann-Whitney, p < .05) increased in almost all localities, reaching a maximum at day 16, whereafter the mucosa normalized. All changes quantitated, except drum vascularization and purulent effusion, were persisting at day 180. Cobblestone appearance of the epithelial surface and polypous mucosal prominences were found. Mucosal thickening was prominent in areas covered with flat epithelium, less so in other areas. Local differences in the degree of increased mucosal thickness were preventing intrinsic tubal occlusion. Enhanced secretory ability of the middle ear mucosa was persisting 6 months after a single episode of acute suppurative otitis media, perhaps predisposing secretory otitis media.

Acute Disease↗
PubMed1995

Site of origin of nasal polyps. Transcranially removed naso-ethmoidal blocks as a screening method for nasal polyps in autopsy material.

In autopsy material naso-ethmoidal blocks were removed in 19 patients. None of the patients had a preceding rhinoscopy. Before removal, the maxillary and sphenoidal sinuses were opened and screened for polyps. After removal the total naso-ethmoidal complex was carefully examined for nasal polyps. The site of origin of the individual polyp was registered and documented photographically. Nine polyps were found in five patients, of which four had no history of asthma, allergy or sinusitis. Two patients had unilateral solitary polyps, three had polyps bilaterally. All polyps were found in the meatus. Eighty-nine per cent of the polyps were related to the clefts from the ethmoid. Polyps were not observed inside the ethmoidal and other paranasal sinuses.

Aged↗
PubMed1994

[Results of hearing preservation via middle fossa approach in surgery for acoustic neurinoma].

The results of hearing preservation surgery in a series of 10 patients with 10 unilateral acoustic neuromas are reported. Mortality was 0%, complications including rhinoliquorrhoea occurred in 10%, and the tumour was removed in 100%. Hearing preservation was obtained in 80%. Normal or nearly normal postoperative facial nerve function evaluated one year after surgery was achieved in all cases. According to House-Brackmann classification, 60% had HB-1 and 40% had HB-2. The fact that no audiovestibular or electrophysiological examinations are specific for acoustic neuroma can not be overemphasized. Early diagnosis of these small tumors in patients with good hearing has made this kind of surgery possible.

Adult↗
PubMed1994

Cystic acoustic neuromas. Results of translabyrinthine surgery.

OBJECTIVE: This study was designed to investigate the surgical outcome of translabyrinthine surgery of cystic acoustic neuromas. DESIGN: Prospective registration of audiovestibular, otoneurologic, and neuroradiologic data of all patients operated on for cystic neuromas in the period 1976 to 1992. The diagnosis was proposed by neuroradiologic investigation, confirmed at surgery, and verified histologically. Clinical follow-up was performed 1 year after surgery. SETTING: The study included all patients with cystic acoustic neuromas from the entire country, referred to the centralized otoneurosurgical team in the Department of Otorhinolaryngology-Head and Neck Surgery, Gentofte University Hospital, and Department of Neurosurgery, Rigshospitalet, University of Copenhagen, Denmark. PATIENTS: The study included 23 patients (11 female and 12 male). Ages ranged between 23 and 77 years with a median of 51.2 years. MAIN OUTCOME: Our hypothesis suggested that surgical outcome of cystic acoustic neuromas was poorer compared with noncystic acoustic neuromas of matching size. The results of this study seem to confirm the hypothesis. RESULTS: The results are rather poor compared with results achieved in surgery of noncystic tumors of matching size, particularly the poor postoperative facial nerve function. CONCLUSIONS: Even though the operation for a cystic acoustic neuroma may appear to be easier and faster than the operation for a solid tumor, there is a high risk for accidental lesion of the facial nerve, in spite of using facial nerve monitoring. Rapid symptomatic worsening may occur due to sudden expansion of cystic elements and, therefore, a wait-and-see policy should not be applied to patients with cystic tumors.

Adult↗
PubMed1994

A cohort study of point prevalence of eardrum pathology in children and teenagers from age 5 to age 16.

The aim of this prospective study was to estimate the prevalence of different types of eardrum pathology in a cohort of children and teenagers up to the age of 16. Among this initial group of 373 subjects, repetitive screening trials including otomicroscopy and tympanometry were performed from age 5 to 16 years. All clinical pathology of Shrapnell's membrane and the pars tensa was recorded systematically. At age 5 years, pathology of the eardrum was found in 19% of ears examined. At succeeding follow-ups until the age of 16 years, the prevalence of eardrum pathology increased to 33%. The tympanometric profile improved significantly from 49% of children with negative middle ear pressure at age 5 years to 4% at age 16 years. The patency of the eustachian tube was estimated in the group with eardrum pathology and compared to the group with no eardrum pathology. Our findings show that, despite improvement of middle ear ventilation through childhood, the prevalence of pathological changes of the eardrum seems to increase. The reason for this increase is discussed.

Acoustic Impedance Tests↗
PubMed1994

Cystic vestibular schwannomas: neuroimaging and growth rate.

In a series of 571 vestibular schwannomas (VS) operated on in the period 1976-1992, via the translabyrinthine approach, 23 tumours (4 per cent) from 23 patients were radiologically, peroperatively and histologically identified as cystic VS. Neuroimaging examinations (CT and MRI) revealed 15 tumours (2.6 per cent) with extracystic formations and in eight cases (1.4 per cent) intratumoural cysts. In 15 cases (65 per cent), tumours were located extracanalicularly with no involvement of the internal auditory canal (IAC). The extracanalicular tumour extension including the cystic elements ranged between 10 and 60 mm with a mean of 45 mm. In eight cases out of 23 (35 per cent) other diagnostic possibilities such as trigeminal schwannoma, epidermoid cyst and meningioma were proposed at the primary evaluation. Deformation, displacement and/or impression of the fourth ventricle was demonstrated in 17 cases (74 per cent). Three patients (13 per cent) had obstructive hydrocephalus which demanded shunt insertion. Residual tumour was detected in two patients (9 per cent). Growth rate in four cases was more than 10 times higher when compared to the annual growth rate of noncystic VS. The results of this study provide data on cystic VS attenuation demonstrated by CT or MRI which may be valuable in neuroradiological diagnosis of these cystic lesions and emphasizes that the wait-and-see policy should not be applied to the cystic variant of VS.

Adult↗
PubMed1994

Histopathology and growth pattern of cystic acoustic neuromas.

In a series of 571 acoustic neuromas, 23 were identified as cystic tumors. An immunohistochemical study including nervous system-associated protein (S-100), glial fibrillary acidic protein (GFAP), neurofilament protein (NF), laminin, fibronectin, vimentin, factor VIII (von Willebrand factor)-related antigen, and the nuclear antibody Ki-67 was performed. The cyst walls contained numerous S-100-positive fibrils distributed throughout the whole extent of the walls. Laminin, fibronectin, and vimentin were predominantly located around the vessel walls, factor VIII was found inside the vessels. GFAP-positive lamellae occurred in 50% of the cases near the surface of the cyst walls. Ki-67 is an antigen associated with cell proliferation. The density of Ki-67-positive cells was found to be 36 times lower in 16 noncystic controls than in the 23 cystic neuromas, indicating that the increase in tumor size in cystic acoustic neuromas may be caused by expansion of the cysts and not by an actual increase in the growth rate of the tumor cells. The data achieved in this series may contribute to better planning of the surgical approach. Because of the risk of sudden expansion of cystic elements, a wait-and-see policy should not be applied to patients with cystic acoustic neuromas.

Adult↗
PubMed1994

Subcutaneous growth of human acoustic schwannomas in athymic nude mice.

In order to develop an in vivo model for growth of acoustic schwannomas, we studied tumor specimens from 10 patients, transplanted into a subcutaneous pocket of 67 nude mice. The number of tumors which survived or grew was 63 (94%). Obvious macroscopic growth was observed in 22 (33%), status quo in 28 (42%), and regression of tumor size in 13 (19%). The tumor disappeared in 4 cases (6%). Serial implantation was not possible due to the small amount of neuroma tissue in the surviving tumors. In animals with obvious macroscopic growth, neovascularization was clearly demonstrated. The presence of Schwann cells in the implants was confirmed immunohistochemically. The proliferative activity in the original and implanted tumors was evaluated by the proliferating cell nuclear antigen (PCNA) and Ki-67 nuclear antigen stainings and showed good correlation between primary tumors and implants. This in vivo tumor model will open new opportunities to study the biology of acoustic tumors and to test different therapeutic modalities.

Animals↗
PubMed1994

Clinical course of patients with primary nasal polyps.

A follow-up study on 180 patients treated for the first time for nasal polyps was performed. The follow-up period was from 1 to 8 years with a median of 57 months. The majority of patients had postoperative topical steroid treatment. 65.6% of patients had one polypectomy, 17.8% had two polypectomies, 10% had 3, 2.8% had 4, and 3.9% of patients had 5-10 polypectomies performed during the follow-up period. Patients without asthma, acute recurrent or chronic sinusitis, acetylsalicylic acid intolerance, or allergy had fewer polypectomies and less topical steroid treatment than patients with these characteristics. The recurrence profile between the first and second polypectomy described with the life-table method showed a slow decline in the number of patients with only one polypectomy. The time span needed before significant clinical symptoms occurred after the first polypectomy indicates that not all primary polyp patients are prone to recurrence. Nasal polyps is probably a manifestation of different clinical and aetio-pathogenetic entities. Further identification of such entities is needed to improve treatment strategy.

Adolescent↗
PubMed1994

The choice of approach in surgery for acoustic neuromas (vestibular schwannomas).

The advantages and disadvantages of the different surgical approaches for surgery of vestibular schwannomas are described, as well as the problems in evaluating the outcome of the treatment, regarding especially the evaluation of facial nerve function and hearing capacity. The eclectic Copenhagen treatment algorithm is outlined: 1) All tumors measuring 25 mm or more on MRI are operated via the translabyrinthine approach. 2) All patients with PTA poorer than 30 dB, and SDS poorer than 70% are operated via the translabyrinthine approach. 3) Tumors less than 10mm extrameatally, and PTA better than 30 dB and SDS better than 70% are removed via the middle fossa route. 4) Tumors measuring 10-25 mm and PTA better than 30 dB and SDS better than 70% are operated via the suboccipital route. Finally some consequences of postponing surgical treatment is described, demonstrating that 74% of 127 tumors continued to grow with a mean of 3.4 mm increased tumor diameter per year, and that 75% of patients, who were candidates for hearing preservation surgery lost the candidature in the observation period.

Algorithms↗